http://www.mdpi.com/journal/materials Latest open access articles published in Materials at http://www.mdpi.com/journal/materials/ http://www.mdpi.com/1996-1944/3/3/2087/ Olefin metathesis using ruthenium carbene complexes is a useful method in synthetic organic chemistry. Enyne metathesis is also catalyzed by these complexes and various carbo- and heterocycles could be synthesized from the corresponding enynes. Dienyne metathesis, cross enyne metathesis and ring-opening enyne metathesis have been further developed. Various complicated compounds, such as the natural products and the related biologically active substances, could be synthesized using these metatheses reactions. Skeletal reorganization using the transition metals and metallotropic rearrangement are also discussed. http://www.mdpi.com/1996-1944/3/3/2087/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Review 2087 2140 1996-1944 Recent Progress on Enyne Metathesis: Its Application to Syntheses of Natural Products and Related Compounds 2010-03-19 doi: 10.3390/ma3032087 Mori http://www.mdpi.com/1996-1944/3/3/2069/ Two new mesogenic monomers, namely 3,3’-dimethoxy-4,4’-di(hydroxyhexoxy)-N-benzylidene-o-Tolidine (Ia) and 4,4’-di(6-hydroxyhexoxy)-N-benzylidene-o-Tolidine (IIa), were reacted with cadmium sulfide (CdS) via an in situ chemical precipitation method in ethanol to produce CdS nanocomposites. A series of different mass compositions of CdS with Ia and IIa ranging from 0.1:1.0 to 1.0:1.0 (w/w) were prepared and characterized using X-ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Polarizing Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC), X-ray Photoelectron Spectroscopy (XPS) and Photoluminescence Spectroscopy (PL). XRD showed that the broad peaks are ascribed to the formation of cubic CdS nanoparticles in both Ia and IIa. The average particle size for both nanocomposites was less than 5 nm with a narrower size distribution when compared with pure CdS nanoparticles. The analyses from POM and DSC demonstrated that mass composition from 0.1:1.0 up to 0.5:1.0 of CdS:Ia nanocomposites showed their enantiotropic nematic phase. On the other hand, polarizing optical microscopy (POM) for IIa nanocomposites showed that the liquid crystal property vanished completely when the mass composition was at 0.2:1.0. PL emissions for CdS: Ia or IIa nanocomposites indicated deep trap defects occurred in these both samples. The PL results revealed that addition of CdS to Ia monomers suppressed the photoluminescence intensity of Ia. However, the introduction of CdS to IIa monomers increased the photoluminescence and was at a maximum when the mass composition was 0.3:1.0, then decreased in intensity as more CdS was added. The XPS results also showed that the stoichiometric ratios of S/Cd were close to 1.0:1.0 for both types of nanocomposites for a mass composition of 1.0:1.0 (CdS:matrix). http://www.mdpi.com/1996-1944/3/3/2069/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Article 2069 2086 1996-1944 Thermal and Optical Properties of CdS Nanoparticles in Thermotropic Liquid Crystal Monomers 2010-03-19 doi: 10.3390/ma3032069 Lee Mohammed Belmahi Assouar Rinnert Alnot http://www.mdpi.com/1996-1944/3/3/2053/ This paper reviews the synthesis, structure and applications of metal fluoride nanoparticles, with particular focus on rare earth (RE) doped fluoride nanoparticles obtained by our research group. Nanoparticles were produced by precipitation methods using the ligand ammonium di-n-octadecyldithiophosphate (ADDP) that allows the growth of shells around a core particle while simultaneously avoiding particle aggregation. Nanoparticles were characterized on their structure, morphology, and luminescent properties. We discuss the synthesis, properties, and application of heavy metal fluorides; specifically LaF3:RE and PbF2, and group IIA fluorides. Particular attention is given to the synthesis of core/shell nanoparticles, including selectively RE-doped LaF3/LaF3, and CaF2/CaF2 core/(multi-)shell nanoparticles, and the CaF2-LaF3 system. http://www.mdpi.com/1996-1944/3/3/2053/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Review 2053 2068 1996-1944 Preparation and Characterization of Rare Earth Doped Fluoride Nanoparticles 2010-03-19 doi: 10.3390/ma3032053 Jacobsohn Kucera James Sprinkle DiMaio Kokuoz Yazgan-Kukouz DeVol Ballato http://www.mdpi.com/1996-1944/3/3/2037/ Octithiophene sterically segregated by annelation with bicyclo[2.2.2]octene (BCO) units was synthesized to study the unimolecular properties of longer oligothiophene dications. For the preparation of such longer oligomers, a new route for the synthesis of the monomer annelated with BCO unit at the 3,4-positions of thiophene ring was developed. Attempted synthesis of octithiophene 1(8T) fully annelated with BCO units was hampered by low solubility of the product, and octithiophene 2(8T) having octyl groups instead of the BCO units at the second rings from the both ends of 1(8T) was synthesized to solve the solubility problem. Neutral 2(8T) has a lower planarity due to the steric repulsion between the octyl substituents and the neighboring thiophene units. However, dication 2(8T)2+, which was obtained as a stable salt by chemical two-electron oxidation with NO+SbF6-, has a planar quinoid structure, as judged from a linear correlation between the inverse chain length and the absorption energy for 1(nT)2+ (n = 3,4,6) and 2(8T)2+. Based on the comparison with the calculated absorption spectra and the result of ESR inactive properties, 2(8T)2+ appears to have a singlet ground state with open-shell biradical character rather than a closed-shell singlet structure. http://www.mdpi.com/1996-1944/3/3/2037/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Article 2037 2052 1996-1944 Synthesis and Properties of Octithiophene Dication Sterically Segregated by Annelation with Bicyclo[2.2.2]octene Units 2010-03-19 doi: 10.3390/ma3032037 Nishinaga Yamazaki Tateno Iyoda Komatsu http://www.mdpi.com/1996-1944/3/3/2027/ The charge ordered organic salt θ-(BEDT-TTF)2CsZn(SCN)4 exhibits a giant nonlinear conduction at low temperatures. The voltage-current characteristics of this compound are similar to those of a thyristor device, after which we named it the organic thyristor. This material shows current oscillation in the presense of dc voltage, which arises from a mechanism different from conventional oscillating circuits, because the oscillation appears in a sample that does not show negative derivative resistance. We have performed a standard circuit analysis, and show that the voltage-current curve is “blurred” in the high current region, and the oscillation occurs in the blurred region. This type of oscillation has never been reported, and a possible origin for this is suggested. http://www.mdpi.com/1996-1944/3/3/2027/ Fri, 19 Mar 2010 00:00:00 CET Materials 2010-03-19 3 3 Article 2027 2036 1996-1944 A Mechanism of DC-AC Conversion in the Organic Thyristor 2010-03-19 doi: 10.3390/ma3032027 Suko Terasaki Mori Mori http://www.mdpi.com/1996-1944/3/3/1981/ Organic/inorganic nanohybrid materials have attracted particular scientific and technological interest because they combine the properties of the organic and the inorganic component. Inorganic nanoparticles exhibit interesting electrical, optical, magnetic and/or catalytic properties, which are related with their nano-scale dimensions. However, their high surface-to-volume ratio often induces agglomeration and leads to the loss of their attractive properties. Surface modification of the inorganic nano-objects with physically or chemically end-tethered polymer chains has been employed to overcome this problem. Covalent tethered polymer chains are realized by three different approaches: the “grafting to”, the “grafting from” and the “grafting through” method. This article reviews the synthesis of end-grafted polymer chains onto inorganic nanoparticles using “controlled/living” polymerization techniques, which allow control over the polymer characteristics and the grafting density of the end-tethered polymer chains. http://www.mdpi.com/1996-1944/3/3/1981/ Thu, 18 Mar 2010 00:00:00 CET Materials 2010-03-18 3 3 Review 1981 2026 1996-1944 End-Grafted Polymer Chains onto Inorganic Nano-Objects 2010-03-18 doi: 10.3390/ma3031981 Achilleos Vamvakaki http://www.mdpi.com/1996-1944/3/3/1928/ Recent advances in biotechnology demonstrate that peptides and proteins are the basis of a new generation of drugs. However, the transportation of protein drugs in the body is limited by their high molecular weight, which prevents the crossing of tissue barriers, and by their short lifetime due to immuno response and enzymatic degradation. Moreover, the ability to selectively deliver drugs to target organs, tissues or cells is a major challenge in the treatment of several human diseases, including cancer. Indeed, targeted delivery can be much more efficient than systemic application, while improving bioavailability and limiting undesirable side effects. This review describes how the use of targeted nanocarriers such as nanoparticles and liposomes can improve the pharmacokinetic properties of protein drugs, thus increasing their safety and maximizing the therapeutic effect. http://www.mdpi.com/1996-1944/3/3/1928/ Wed, 17 Mar 2010 00:00:00 CET Materials 2010-03-17 3 3 Review 1928 1980 1996-1944 Targeted Delivery of Protein Drugs by Nanocarriers 2010-03-17 doi: 10.3390/ma3031928 Solaro Chiellini Battisti http://www.mdpi.com/1996-1944/3/3/1913/ The freeze-casting of porous materials has received a great deal of attention during the past few years. This simple process, where a material suspension is simply frozen and then sublimated, provides materials with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. This review focuses on the recent results on the process and the derived porous structures with regards to the biomaterials applications. Of particular interest is the architecture of the materials and the versatility of the process, which can be readily controlled and applied to biomaterials applications. A careful control of the starting formulation and processing conditions is required to control the integrity of the structure and resulting properties. Further in vitro and in vivo investigations are required to validate the potential of this new class of porous materials. http://www.mdpi.com/1996-1944/3/3/1913/ Wed, 17 Mar 2010 00:00:00 CET Materials 2010-03-17 3 3 Review 1913 1927 1996-1944 Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities 2010-03-17 doi: 10.3390/ma3031913 Deville http://www.mdpi.com/1996-1944/3/3/1904/ A model donor-acceptor oligomer consisting of benzodithiophene-diketone and thiophene has been investigated with regard to its molecular packing and opto-electronic properties. The crystal structure suggests that the packing is dominated by charge-transfer interactions between the electron-rich part of the molecule and the electron-poor part. A series of observations corroborate this assumption, among them are a charge-transfer band in the film absorption spectra and exceptionally low π-π distances. A detailed analysis of the energetic levels of the present system reveals that only the HOMO level of the acceptor is shifted by conjugation to the donor. The results can contribute to the development of improved materials for organic electronics. http://www.mdpi.com/1996-1944/3/3/1904/ Wed, 17 Mar 2010 00:00:00 CET Materials 2010-03-17 3 3 Communication 1904 1912 1996-1944 Charge-Transfer Controlled Crystallization of a Model Oligomer for Donor-Acceptor-Polythiophenes 2010-03-17 doi: 10.3390/ma3031904 Rieger Enkelmann Müllen http://www.mdpi.com/1996-1944/3/3/1888/ Chemical pulps are produced by chemical delignification of lignocelluloses such as wood or annual non-woody plants. After pulping (e.g., kraft pulping), the remaining lignin is removed by bleaching to produce a high quality, bright paper. The goal of bleaching is to remove lignin from the pulp without a negative effect on the cellulose; for this reason, delignification should be performed in a highly selective manner. New environmentally-friendly alternatives to conventional chlorine-based bleaching technologies (e.g., oxygen, ozone, or peroxide bleaching) have been suggested or implemented. In an attempt to find inorganic agents that mimic the action of highly selective lignin-degrading enzymes and that can be applicable in industrial conditions, the researchers have focused on polyoxometalates (POMs), used either as regenerable redox reagents (in anaerobic conditions) or as catalysts (in aerobic conditions) of oxidative delignification. The aim of this paper is to review the basic concepts of POM delignification in these two processes. http://www.mdpi.com/1996-1944/3/3/1888/ Tue, 16 Mar 2010 00:00:00 CET Materials 2010-03-16 3 3 Review 1888 1903 1996-1944 Polyoxometalates in Oxidative Delignification of Chemical Pulps: Effect on Lignin 2010-03-16 doi: 10.3390/ma3031888 Bujanovic Ralph Reiner Hirth Atalla http://www.mdpi.com/1996-1944/3/3/1863/ Collagen is the most widely distributed class of proteins in the human body. The use of collagen-based biomaterials in the field of tissue engineering applications has been intensively growing over the past decades. Multiple cross-linking methods were investigated and different combinations with other biopolymers were explored in order to improve tissue function. Collagen possesses a major advantage in being biodegradable, biocompatible, easily available and highly versatile. However, since collagen is a protein, it remains difficult to sterilize without alterations to its structure. This review presents a comprehensive overview of the various applications of collagen-based biomaterials developed for tissue engineering, aimed at providing a functional material for use in regenerative medicine from the laboratory bench to the patient bedside. http://www.mdpi.com/1996-1944/3/3/1863/ Tue, 16 Mar 2010 00:00:00 CET Materials 2010-03-16 3 3 Review 1863 1887 1996-1944 Collagen-Based Biomaterials for Tissue Engineering Applications 2010-03-16 doi: 10.3390/ma3031863 Parenteau-Bareil Gauvin Berthod http://www.mdpi.com/1996-1944/3/3/1845/ The combination of nanodiamond (ND) with biomolecular mass spectrometry (MS) makes rapid, sensitive detection of biopolymers from complex biosamples feasible. Due to its chemical inertness, optical transparency and biocompatibility, the advantage of NDs in MS study is unique. Furthermore, functionalization on the surfaces of NDs expands their application in the fields of proteomics and genomics for specific requirements greatly. This review presents methods of MS analysis based on solid phase extraction and elution on NDs and different application examples including peptide, protein, DNA, glycan and others. Owing to the quick development of nanotechnology, surface chemistry, new MS methods and the intense interest in proteomics and genomics, a huge increase of their applications in biomolecular MS analysis in the near future can be predicted. http://www.mdpi.com/1996-1944/3/3/1845/ Mon, 15 Mar 2010 00:00:00 CET Materials 2010-03-15 3 3 Review 1845 1862 1996-1944 Application of Nanodiamonds in Biomolecular Mass Spectrometry 2010-03-15 doi: 10.3390/ma3031845 Kong Cheng http://www.mdpi.com/1996-1944/3/3/1833/ One of the principal challenges in the field of tissue engineering and regenerative medicine is the formation of functional microvascular networks capable of sustaining tissue constructs. Complex tissues and vital organs require a means to support oxygen and nutrient transport during the development of constructs both prior to and after host integration, and current approaches have not demonstrated robust solutions to this challenge. Here, we present a technology platform encompassing the design, construction, cell seeding and functional evaluation of tissue equivalents for wound healing and other clinical applications. These tissue equivalents are comprised of biodegradable microfluidic scaffolds lined with microvascular cells and designed to replicate microenvironmental cues necessary to generate and sustain cell populations to replace dermal and/or epidermal tissues lost due to trauma or disease. Initial results demonstrate that these biodegradable microfluidic devices promote cell adherence and support basic cell functions. These systems represent a promising pathway towards highly integrated three-dimensional engineered tissue constructs for a wide range of clinical applications. http://www.mdpi.com/1996-1944/3/3/1833/ Mon, 15 Mar 2010 00:00:00 CET Materials 2010-03-15 3 3 Article 1833 1844 1996-1944 Tissue Equivalents Based on Cell-Seeded Biodegradable Microfluidic Constructs 2010-03-15 doi: 10.3390/ma3031833 Borenstein Megley Wall Pritchard Truong Kaplan Tao Herman http://www.mdpi.com/1996-1944/3/3/1803/ Parylene is a family of chemically vapour deposited polymer with material properties that are attractive for biomedicine and nanobiotechnology. Chemically inert parylene “peel-off” stencils have been demonstrated for micropatterning biomolecular arrays with high uniformity, precise spatial control down to nanoscale resolution. Such micropatterned surfaces are beneficial in engineering biosensors and biological microenvironments. A variety of substituted precursors enables direct coating of functionalised parylenes onto biomedical implants and microfluidics, providing a convenient method for designing biocompatible and bioactive surfaces. This article will review the emerging role and applications of parylene as a biomaterial for surface chemical modification and provide a future outlook. http://www.mdpi.com/1996-1944/3/3/1803/ Mon, 15 Mar 2010 00:00:00 CET Materials 2010-03-15 3 3 Review 1803 1832 1996-1944 Surface Engineering and Patterning Using Parylene for Biological Applications 2010-03-15 doi: 10.3390/ma3031803 Tan Craighead http://www.mdpi.com/1996-1944/3/3/1782/ A review of recent progress in hybrid integrated platforms for silicon photonics is presented. Integration of III-V semiconductors onto silicon-on-insulator substrates based on two different bonding techniques is compared, one comprising only inorganic materials, the other technique using an organic bonding agent. Issues such as bonding process and mechanism, bonding strength, uniformity, wafer surface requirement, and stress distribution are studied in detail. The application in silicon photonics to realize high-performance active and passive photonic devices on low-cost silicon wafers is discussed. Hybrid integration is believed to be a promising technology in a variety of applications of silicon photonics. http://www.mdpi.com/1996-1944/3/3/1782/ Fri, 12 Mar 2010 00:00:00 CET Materials 2010-03-12 3 3 Review 1782 1802 1996-1944 Hybrid Integrated Platforms for Silicon Photonics 2010-03-12 doi: 10.3390/ma3031782 Liang Roelkens Baets Bowers http://www.mdpi.com/1996-1944/3/3/1768/ Diamond, with its exceptionally high optical nuclear potential and low absorption cross-section, is a unique material for a series of applications in VCN (very cold neutron) physics and techniques. In particular, powder of diamond nanoparticles provides the best reflector for neutrons in the complete VCN energy range. It allowed also the first observation of quasi-specular reflection of cold neutrons (CN) from disordered medium. Effective critical velocity for such a quasi-specular reflection is higher than that for the best super-mirror. Nano-diamonds survive in high radiation fluxes; therefore they could be used, under certain conditions, in the vicinity of intense neutron sources. http://www.mdpi.com/1996-1944/3/3/1768/ Wed, 10 Mar 2010 00:00:00 CET Materials 2010-03-10 3 3 Communication 1768 1781 1996-1944 Application of Diamond Nanoparticles in Low-Energy Neutron Physics 2010-03-10 doi: 10.3390/ma3031768 Valery Nesvizhevsky Robert Cubitt Egor Lychagin Alexei Muzychka Grigory Nekhaev Guillaume Pignol Konstantin Protasov Alexander Strelkov http://www.mdpi.com/1996-1944/3/3/1746/ Hydrogels have many different applications in the field of regenerative medicine. Biodegradable, injectable hydrogels could be utilized as delivery systems, cell carriers, and scaffolds for tissue engineering. Injectable hydrogels are an appealing scaffold because they are structurally similar to the extracellular matrix of many tissues, can often be processed under relatively mild conditions, and may be delivered in a minimally invasive manner. This review will discuss recent advances in the field of injectable hydrogels, including both synthetic and native polymeric materials, which can be potentially used in cartilage and soft tissue engineering applications. http://www.mdpi.com/1996-1944/3/3/1746/ Wed, 10 Mar 2010 00:00:00 CET Materials 2010-03-10 3 3 Review 1746 1767 1996-1944 Injectable, Biodegradable Hydrogels for Tissue Engineering Applications 2010-03-10 doi: 10.3390/ma3031746 Huaping Tan Kacey G. Marra http://www.mdpi.com/1996-1944/3/3/1709/ This paper presents an overview on recent developments of imogolite reinforced nanocomposites, including fundamental structure, synthesis/purification of imogolite, physicochemical properties of nanocomposites and potential applications in industry. The naturally derived nanotubular material of imogolite represents a distinctive class of nanofiller for industrially significant polymer. The incompatibility between the surface properties of inorganic nanofiller and organic matrix has prompted the need to surface modify the imogolite. Early problems in increasing the binding properties of surface modifier to imogolite have been overcome by using a phosphonic acid group. Different approaches have been used to gain better control over the dispersal of nanofiller and to further improve the physicochemical properties of nanocomposites. Among these, polymer grafting, in situ synthesis of imogolite in polymer matrix, and spin-assembly are some of the promising methods that will be described herein. This imogolite reinforced nanocomposite of enhanced optical and mechanical properties, and with unique biological and electronic properties, is expected to become an important category of hybrid material that shows potential for industrial applications. http://www.mdpi.com/1996-1944/3/3/1709/ Tue, 09 Mar 2010 00:00:00 CET Materials 2010-03-09 3 3 Review 1709 1745 1996-1944 Imogolite Reinforced Nanocomposites: Multifaceted Green Materials 2010-03-09 doi: 10.3390/ma3031709 Weng On Yah Kazuya Yamamoto Nattha Jiravanichanun Hideyuki Otsuka Atsushi Takahara http://www.mdpi.com/1996-1944/3/3/1692/ The crystal structure and the photoluminescence properties of novel green Ba4-yEuySi6O16-3x/2Nx phosphors were investigated. The electronic structures of the Ba4Si6O16 host were calculated by first principles pseudopotential method based on density functional theory. The results reveal that the top of the valence bands are dominated by O-2p states hybridized with Ba-6s and Si-3p states, while the conduction bands are mainly determined by Ba-6s states for the host, which is an insulator with a direct energy gap of 4.6 eV at Γ. A small amount of nitrogen can be incorporated into the host to replace oxygen and forms Ba4-yEuySi6O16-3x/2Nx solid solutions crystallized in a monoclinic (space group P21/c, Z = 2) having the lattice parameters a = 12.4663(5) Å, b = 4.6829(2) Å, c = 13.9236(6) Å, and β = 93.61(1)°, with a maximum solubility of nitrogen at about x = 0.1. Ba4Si6O16-3x/2Nx:Eu2+ exhibits efficient green emission centered at 515–525 nm varying with the Eu2+ concentration when excited under UV to 400 nm. Furthermore, the incorporation of nitrogen can slightly enhance the photoluminescence intensity. Excitation in the UV-blue spectral range (λexc = 375 nm), the absorption and quantum efficiency of Ba4-yEuySi6O16-3x/2Nx (x = 0.1, y = 0.2) reach about 80% and 46%, respectively. Through further improvement of the thermal stability, novel green phosphor of Ba4-yEuySi6O16-3x/2Nx is promising for application in white UV-LEDs. http://www.mdpi.com/1996-1944/3/3/1692/ Mon, 08 Mar 2010 00:00:00 CET Materials 2010-03-08 3 3 Article 1692 1708 1996-1944 Crystal and Electronic Structures, Photoluminescence Properties of Eu2+-Doped Novel Oxynitride Ba4Si6O16-3x/2Nx 2010-03-08 doi: 10.3390/ma3031692 Yuanqiang Li Yuan Fang Naoto Hirosaki Rong-Jun Xie Lihong Liu Takashi Takeda Xiaoyun Li http://www.mdpi.com/1996-1944/3/3/1674/ Nanotechnologies are predicted to revolutionize: (a) the control over materials properties at ultrafine scales; and (b) the sensitivity of tools and devices applied in various scientific and technological fields. In this short review, we argue that dentistry will be no exception to this trend. Here, we present a dynamic view of dental tissues, an adoption of which may lead to finer, more effective and minimally invasive reparation approaches. By doing so, we aim at providing insights into some of the breakthroughs relevant to understanding the genesis of dental tissues at the nanostructural level or generating dental materials with nanoscale critical boundaries. The lineage of the progress of dental science, including the projected path along the presumed nanotechnological direction of research and clinical application is mentioned too. We conclude by claiming that dentistry should follow the trend of probing matter at nanoscale that currently dominates both materials and biological sciences in order to improve on the research strategies and clinical techniques that have traditionally rested on mechanistic assumptions. http://www.mdpi.com/1996-1944/3/3/1674/ Mon, 08 Mar 2010 00:00:00 CET Materials 2010-03-08 3 3 Review 1674 1691 1996-1944 Nanotechnology in Dental Sciences: Moving towards a Finer Way of Doing Dentistry 2010-03-08 doi: 10.3390/ma3031674 Vuk Uskoković Luiz Eduardo Bertassoni http://www.mdpi.com/1996-1944/3/3/1640/ A lot of molecular (magnetic) conductors are prepared largely using charge-transfer (CT) salts of donor molecules with acceptor molecules or nonmagnetic or magnetic anions such as metal halides and oxides; their CT salts are usually obtained as bulk crystals, which are used to elucidate the electrical conducting (magnetic) properties. In contrast, a small number of micro/nano-crystals of the molecular (magnetic) conductors, especially micro/nano-wires, are known, of which highly conducting nanowires are necessary as a key component in the development of the next generation of nano-size transistors and spin-transistors. Very recently, we succeeded in preparing highly conductive micro/nano-wires of CT salts between bent donor molecules developed by one of the author’s group and magnetic FeX4– (X = Cl, Br) ions: (1) by electrochemical oxidation of the bent donor molecules with a silicon wafer electrode coated with a phospholipid multi-lamellar structure as well as, (ii) by electrochemical oxidation of the bent donor molecules with a large arc structure, in the presence of NBu4FeX4 supporting electrolytes. This article reviews template-free and template-assisted methods developed so far for the preparation of micro/nano-wires of molecular (magnetic) conductors along with our new methods. The conducting properties of these micro/nano-wires are compared with those of the corresponding bulk crystals. http://www.mdpi.com/1996-1944/3/3/1640/ Mon, 08 Mar 2010 00:00:00 CET Materials 2010-03-08 3 3 Review 1640 1673 1996-1944 New Development in the Preparation of Micro/Nano-Wires of Molecular (Magnetic) Conductors 2010-03-08 doi: 10.3390/ma3031640 Toyonari Sugimoto Hisashi Tanaka Dominique de Caro Lydie Valade http://www.mdpi.com/1996-1944/3/3/1620/ Human vascular endothelial cells (VEC) line the vessels of the body and are critical for the maintenance of vessel integrity and trafficking of biochemical cues. They are fundamental structural elements and are central to the signaling environment. Alterations in the normal functioning of the VEC population are associated with a number of vascular disorders among which are some of the leading causes of death in both the United States and abroad. VECs attach to their underlying stromal elements through a specialization of the extracellular matrix, the basement membrane. The basement membrane provides signaling cues to the VEC through its chemical constituents, by serving as a reservoir for cytoactive factors and through its intrinsic biophysical properties. This specialized matrix is composed of a topographically rich 3D felt-like network of fibers and pores on the nano (1–100 nm) and submicron (100–1,000 nm) size scale. The basement membrane provides biophysical cues to the overlying VECs through its intrinsic topography as well as through its local compliance (relative stiffness). These biophysical cues modulate VEC adhesion, migration, proliferation, differentiation, and the cytoskeletal signaling network of the individual cells. This review focuses on the impact of biophysical cues on VEC behaviors and demonstrates the need for their consideration in future vascular studies and the design of improved prosthetics. http://www.mdpi.com/1996-1944/3/3/1620/ Fri, 05 Mar 2010 00:00:00 CET Materials 2010-03-05 3 3 Review 1620 1639 1996-1944 Biophysical Cueing and Vascular Endothelial Cell Behavior 2010-03-05 doi: 10.3390/ma3031620 Joshua A. Wood Sara J. Liliensiek Paul Russell Paul F. Nealey Christopher J. Murphy http://www.mdpi.com/1996-1944/3/3/1593/ Many attempts have been made to fabricate various types of inorganic nanoparticle-filled polymers (filler/polymer nanocomposites) by a mechanical or chemical approach. However, these approaches require modification of the nanofiller surfaces and/or complicated polymerization reactions, making them unsuitable for industrial-scale production of the nanocomposites. The author and coworkers have proposed a simple melt-compounding method for the fabrication of silica/polymer nanocomposites, wherein silica nanoparticles without surface modification were dispersed through the breakdown of loose agglomerates of colloidal nano-silica spheres in a kneaded polymer melt. This review aims to discuss experimental techniques of the proposed method and its advantages over other developed methods. http://www.mdpi.com/1996-1944/3/3/1593/ Thu, 04 Mar 2010 00:00:00 CET Materials 2010-03-04 3 3 Review 1593 1619 1996-1944 Development of Fabrication Methods of Filler/Polymer Nanocomposites: With Focus on Simple Melt-Compounding-Based Approach without Surface Modification of Nanofillers 2010-03-04 doi: 10.3390/ma3031593 Mitsuru Tanahashi http://www.mdpi.com/1996-1944/3/3/1573/ Ti1-xAlxN coated tools are commonly used in high-speed machining, where the cutting edge of an end-mill or insert is exposed to temperatures up to 1100 °C. Here, we investigate the effect of Yttrium addition on the thermal stability of Ti1-xAlxN coatings. Reactive DC magnetron sputtering of powder metallurgically prepared Ti0.50Al0.50, Ti0.49Al0.49Y0.02, and Ti0.46Al0.46Y0.08 targets result in the formation of single-phase cubic (c) Ti0.45Al0.55N, binary cubic/wurtzite c/w-Ti0.41Al0.57Y0.02N and singe-phase w-Ti0.38Al0.54Y0.08N coatings. Using pulsed DC reactive magnetron sputtering for the Ti0.49Al0.49Y0.02 target allows preparing single-phase c-Ti0.46Al0.52Y0.02N coatings. By employing thermal analyses in combination with X-ray diffraction and transmission electron microscopy investigations of as deposited and annealed (in He atmosphere) samples, we revealed that Y effectively retards the decomposition of the Ti1-x-yAlxYyN solid-solution to higher temperatures and promotes the precipitation of c-TiN, c-YN, and w-AlN. Due to their different microstructure and morphology already in the as deposited state, the hardness of the coatings decreases from ~35 to 22 GPa with increasing Y-content and increasing wurtzite phase fraction. Highest peak hardness of ~38 GPa is obtained for the Y-free c-Ti0.45Al0.55N coating after annealing at Ta = 950 °C, due to spinodal decomposition. After annealing above 1000 °C the highest hardness is obtained for the 2 mol % YN containing c-Ti0.46Al0.52Y0.02N coating with ~29 and 28 GPa for Ta = 1150 and 1200 °C, respectively. http://www.mdpi.com/1996-1944/3/3/1573/ Thu, 04 Mar 2010 00:00:00 CET Materials 2010-03-04 3 3 Article 1573 1592 1996-1944 Influence of Yttrium on the Thermal Stability of Ti-Al-N Thin Films 2010-03-04 doi: 10.3390/ma3031573 Martin Moser Daniel Kiener Christina Scheu Paul H. Mayrhofer http://www.mdpi.com/1996-1944/3/3/1559/ We have developed a method of forming platinum (Pt) nanoparticles using a metal organic chemical fluid deposition (MOCFD) process employing a supercritical fluid (SCF), and have demonstrated the synthesis of dispersed Pt nanoparticles on the surfaces of carbon nanowalls (CNWs), two-dimensional carbon nanostructures, and carbon nanotubes (CNTs). By using SCF-MOCFD with supercritical carbon dioxide as a solvent of metal-organic compounds, highly dispersed Pt nanoparticles of 2 nm diameter were deposited on the entire surface of CNWs and CNTs. The SCF-MOCFD process proved to be effective for the synthesis of Pt nanoparticles on the entire surface of intricate carbon nanostructures with narrow interspaces. http://www.mdpi.com/1996-1944/3/3/1559/ Wed, 03 Mar 2010 00:00:00 CET Materials 2010-03-03 3 3 Review 1559 1572 1996-1944 Preparation of Dispersed Platinum Nanoparticles on a Carbon Nanostructured Surface Using Supercritical Fluid Chemical Deposition 2010-03-03 doi: 10.3390/ma3031559 Mineo Hiramatsu Masaru Hori http://www.mdpi.com/1996-1944/3/3/1533/ In the organic electronics research field, several strategies have been used to modulate the transport properties of thiophene-derived semiconductors via sequential functionalization of their π-conjugated cores. This review summarizes the major design and synthetic strategies for tuning thiophene-containing small molecule and polymer properties by introducing electron-deficient nitrogen-containing azine and azole moieties. Several examples are presented which elucidate the structural, optical, and electronic consequences of incorporating these electron-deficient fragments in the conjugated skeletons, particularly relating to applications in organic thin-film transistors. http://www.mdpi.com/1996-1944/3/3/1533/ Wed, 03 Mar 2010 00:00:00 CET Materials 2010-03-03 3 3 Review 1533 1558 1996-1944 Azine- and Azole-Functionalized Oligo´ and Polythiophene Semiconductors for Organic Thin-Film Transistors 2010-03-03 doi: 10.3390/ma3031533 Rocío Ponce Ortiz He Yan Antonio Facchetti Tobin J. Marks http://www.mdpi.com/1996-1944/3/3/1515/ High performance coatings tailored to medical devices represent a recognised approach to modulate surface properties. Plasma-deposited fluorocarbon films have been proposed as a potential stent coating. Previous studies have shown promising adhesion properties: the 35 nm-thick film sustained plastic deformation up to 25% such as induced during the clinical implantation. In this study, the compositional and morphological changes of plasma-deposited fluorocarbon films were examined during ageing in a pseudo-physiological medium, a phosphate buffer solution (PBS), by angle-resolved XPS, FT-IR data and AFM images. The evolution of the ageing process is discussed: defluorination and crosslinking yielded an oxidized protective top layer onto the films, which showed further degradation. http://www.mdpi.com/1996-1944/3/3/1515/ Tue, 02 Mar 2010 00:00:00 CET Materials 2010-03-02 3 3 Article 1515 1532 1996-1944 Toward High-Performance Coatings for Biomedical Devices: Study on Plasma-Deposited Fluorocarbon Films and Ageing in PBS 2010-03-02 doi: 10.3390/ma3031515 Servaas Holvoet Pascale Chevallier Stéphane Turgeon Diego Mantovani http://www.mdpi.com/1996-1944/3/3/1509/ We report resistivity and thermo-electric power measurements of the anatase phase of TiO2under pressure up to 2.3 GPa. Despite its transparent appearance, the single crystal of anatase exhibits a metallic-like resistivity above 60 K, at all pressures. The rather high value of the thermo-electric power at room temperature points to complex transport mechanism in this phase. http://www.mdpi.com/1996-1944/3/3/1509/ Mon, 01 Mar 2010 00:00:00 CET Materials 2010-03-01 3 3 Article 1509 1514 1996-1944 High-Pressure Study of Anatase TiO2 2010-03-01 doi: 10.3390/ma3031509 Jaćim Jaćimović Cristian Vâju Richard Gaál Arnaud Magrez Helmuth Berger László Forró http://www.mdpi.com/1996-1944/3/3/1497/ An in-depth optimization of growth conditions and investigation of optical properties including discussions on band alignment of GaAsSb/GaAs quantum well (QW) on GaAs by molecular beam epitaxy (MBE) are reported. Optimal MBE growth temperature of GaAsSb QW is found to be 470 ± 10 °C. GaAsSb/GaAs QW with Sb content ~0.36 has a weak type-II band alignment with valence band offset ratio QV ~1.06. A full width at half maximum (FWHM) of ~60 meV in room temperature (RT) photoluminescence (PL) indicates fluctuation in electrostatic potential to be less than 20 meV. Samples grown under optimal conditions do not exhibit any blue shift of peak in RT PL spectra under varying excitation. http://www.mdpi.com/1996-1944/3/3/1497/ Fri, 26 Feb 2010 00:00:00 CET Materials 2010-02-26 3 3 Article 1497 1508 1996-1944 Photoluminescence and Band Alignment of Strained GaAsSb/GaAs QW Structures Grown by MBE on GaAs 2010-02-26 doi: 10.3390/ma3031497 Yuri G. Sadofyev Nigamananda Samal http://www.mdpi.com/1996-1944/3/2/1478/ Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i) dispersion of carbon nanotubes in the polymer host, (ii) carbon nanotube-polymer interaction and the nature of the interface, and (iii) alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported. http://www.mdpi.com/1996-1944/3/2/1478/ Thu, 25 Feb 2010 00:00:00 CET Materials 2010-02-25 3 2 Review 1478 1496 1996-1944 Electrically and Thermally Conducting Nanocomposites for Electronic Applications 2010-02-25 doi: 10.3390/ma3021478 Wayne E. Jones Jasper Chiguma Edwin Johnson Ashok Pachamuthu Daryl Santos http://www.mdpi.com/1996-1944/3/2/1461/ Polymer/metal nanocomposite containing intrinsically anisotropic metal nanostructures such as metal nanorods and nanowires appeared extremely more sensitive and responsive to mechanical stimuli than nanocomposites containing spherical nanoparticles. After uniaxial stretching of the supporting polymer matrix (poly(vinyl alcohol)), the elongated silver nanostructures embedded at low concentration into the polymer matrix (<1 wt % of Ag) assume the direction of the drawing, yielding materials with a strong dichroic response of the absorption behavior. Accordingly, the film changed its color when observed under linearly polarized light already at moderate drawings. The results obtained suggest that nanocomposite films have potential in applications such as color polarizing filters, radiation responsive polymeric objects and smart flexible films in packaging applications. http://www.mdpi.com/1996-1944/3/2/1461/ Wed, 24 Feb 2010 00:00:00 CET Materials 2010-02-24 3 2 Article 1461 1477 1996-1944 Polymer Nanocomposites Containing Anisotropic Metal Nanostructures as Internal Strain Indicators 2010-02-24 doi: 10.3390/ma3021461 Marco Bernabò Andrea Pucci Hasina Harimino Ramanitra Giacomo Ruggeri http://www.mdpi.com/1996-1944/3/2/1420/ Hydrogel nanoparticles—also referred to as polymeric nanogels or macromolecular micelles—are emerging as promising drug carriers for therapeutic applications. These nanostructures hold versatility and properties suitable for the delivery of bioactive molecules, namely of biopharmaceuticals. This article reviews the latest developments in the use of self-assembled polymeric nanogels for drug delivery applications, including small molecular weight drugs, proteins, peptides, oligosaccharides, vaccines and nucleic acids. The materials and techniques used in the development of self-assembling nanogels are also described. http://www.mdpi.com/1996-1944/3/2/1420/ Wed, 24 Feb 2010 00:00:00 CET Materials 2010-02-24 3 2 Review 1420 1460 1996-1944 Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications 2010-02-24 doi: 10.3390/ma3021420 Catarina Gonçalves Paula Pereira Miguel Gama http://www.mdpi.com/1996-1944/3/2/1390/ Since the initial research leading to the production of diamond composite materials, there have been several important developments leading to significant improvements in the properties of these superhard composite materials. Apart from the fact that diamonds, whether originating from natural resources or synthesised commercially, are the hardest and most wear-resistant materials commonly available, there are other mechanical properties that limit their industrial application. These include the low fracture toughness and low impact strength of diamond. By incorporating a range of binder phases into the sintering production process of these composites, these critically important properties have been radically improved. These new composites can withstand much higher operating temperatures without markedly reducing their strength and wear resistance. Further innovative steps are now being made to improve the properties of diamond composites by reducing grain and particle sizes into the nano range. This review will cover recent developments in diamond composite materials with special emphasis on microstructural characterisation. The results of such studies should assist in the design of new, innovative diamond tools as well as leading to radical improvements in the productivity of cutting, drilling and sawing operations in the exploration, mining, civil construction and manufacturing industries. http://www.mdpi.com/1996-1944/3/2/1390/ Wed, 24 Feb 2010 00:00:00 CET Materials 2010-02-24 3 2 Review 1390 1419 1996-1944 Microstructural Characterisation and Wear Behaviour of Diamond Composite Materials 2010-02-24 doi: 10.3390/ma3021390 James N. Boland Xing S. Li http://www.mdpi.com/1996-1944/3/2/1375/ Creating heterogeneous tissue constructs with an even cell distribution and robust mechanical strength remain important challenges to the success of in vivo tissue engineering. To address these issues, we are developing a scaffold sheet tissue engineering strategy consisting of thin (~200 μm), strong, elastic, and porous crosslinked urethane- doped polyester (CUPE) scaffold sheets that are bonded together chemically or through cell culture. Suture retention of the tissue constructs (four sheets) fabricated by the scaffold sheet tissue engineering strategy is close to the surgical requirement (1.8 N) rendering their potential for immediate implantation without a need for long cell culture times. Cell culture results using 3T3 fibroblasts show that the scaffold sheets are bonded into a tissue construct via the extracellular matrix produced by the cells after 2 weeks of in vitro cell culture. http://www.mdpi.com/1996-1944/3/2/1375/ Wed, 24 Feb 2010 00:00:00 CET Materials 2010-02-24 3 2 Article 1375 1389 1996-1944 Scaffold Sheet Design Strategy for Soft Tissue Engineering 2010-02-24 doi: 10.3390/ma3021375 Richard T. Tran Paul Thevenot Yi Zhang Dipendra Gyawali Liping Tang Jian Yang http://www.mdpi.com/1996-1944/3/2/1353/ At present, thick film (powder based) alternating current electroluminescence (AC-EL) is the only technology available for the fabrication of large area, laterally structured and coloured light sources by simple printing techniques. Substrates for printing may be based on flexible polymers or glass, so the final devices can take up a huge variety of shapes. After an introduction of the underlying physics and chemistry, the review highlights the technical progress behind this development, concentrating on luminescent and dielectric materials used. Limitations of the available materials as well as room for further improvement are also discussed. http://www.mdpi.com/1996-1944/3/2/1353/ Tue, 23 Feb 2010 00:00:00 CET Materials 2010-02-23 3 2 Review 1353 1374 1996-1944 Materials for Powder-Based AC-Electroluminescence 2010-02-23 doi: 10.3390/ma3021353 Michael Bredol Hubert Schulze Dieckhoff http://www.mdpi.com/1996-1944/3/2/1316/ The unique size- and shape-dependent electronic properties of nanocrystals (NCs) make them extremely attractive as novel structural building blocks for constructing a new generation of innovative materials and solid-state devices. Recent advances in material chemistry has allowed the synthesis of colloidal NCs with a wide range of compositions, with a precise control on size, shape and uniformity as well as specific surface chemistry. By incorporating such nanostructures in polymers, mesoscopic materials can be achieved and their properties engineered by choosing NCs differing in size and/or composition, properly tuning the interaction between NCs and surrounding environment. In this contribution, different approaches will be presented as effective opportunities for conveying colloidal NC properties to nanocomposite materials for micro and nanofabrication. Patterning of such nanocomposites either by conventional lithographic techniques and emerging patterning tools, such as ink jet printing and nanoimprint lithography, will be illustrated, pointing out their technological impact on developing new optoelectronic and sensing devices. http://www.mdpi.com/1996-1944/3/2/1316/ Tue, 23 Feb 2010 00:00:00 CET Materials 2010-02-23 3 2 Review 1316 1352 1996-1944 Colloidal Inorganic Nanocrystal Based Nanocomposites: Functional Materials for Micro and Nanofabrication 2010-02-23 doi: 10.3390/ma3021316 Chiara Ingrosso AnnaMaria Panniello Roberto Comparelli Maria Lucia Curri Marinella Striccoli http://www.mdpi.com/1996-1944/3/2/1302/ A layer-by-layer method has been developed for the synthesis of metal-organic frameworks (MOFs) and their deposition on functionalized organic surfaces. The approach is based on the sequential immersion of functionalized organic surfaces into solutions of the building blocks of the MOF, i.e., the organic ligand and the inorganic unit. The synthesis and growth of different types of MOFs on substrates with different functionalization, like COOH, OH and pyridine terminated surfaces, were studied and characterized with different surface characterization techniques. A controlled and highly oriented growth of very homogenous films was obtained using this method. The layer-by-layer method offered also the possibility to study the kinetics of film formation in more detail using surface plasmon resonance and quartz crystal microbalance. In addition, this method demonstrates the potential to synthesize new classes of MOFs not accessible by conventional methods. Finally, the controlled growth of MOF thin films is important for many applications like chemical sensors, membranes and related electrodes. http://www.mdpi.com/1996-1944/3/2/1302/ Tue, 23 Feb 2010 00:00:00 CET Materials 2010-02-23 3 2 Article 1302 1315 1996-1944 Layer-by-Layer Method for the Synthesis and Growth of Surface Mounted Metal-Organic Frameworks (SURMOFs) 2010-02-23 doi: 10.3390/ma3021302 Osama Shekhah http://www.mdpi.com/1996-1944/3/2/1281/ Correlative studies of three oxalato-bridged polymers, obtained under hydrothermal conditions for the two isostructural compounds {Rb(HC2O4)(H2C2O4)(H2O)2}∞1, 1, {H3O(HC2O4)(H2C2O4).2H2O}∞1, 2, and by conventional synthetic method for {Rb(HC2O4)}∞3, 3, allowed the identification of H-bond patterns and structural dimensionality. Ferroïc domain structures are confirmed by electric measurements performed on 3. Although 2 resembles one oxalic acid sesquihydrate, its structure determination doesn’t display any kind of disorder and leads to recognition of a supramolecular network identical to hybrid s-block series, where moreover, unusual H3O+ and NH4+ similarity is brought out. Thermal behaviors show that 1D frameworks with extended H-bonds, whether with or without a metal center, have the same stability. Inversely, despite the dimensionalities, the same metallic intermediate and final compounds are obtained for the two Rb+ ferroïc materials. http://www.mdpi.com/1996-1944/3/2/1281/ Tue, 23 Feb 2010 00:00:00 CET Materials 2010-02-23 3 2 Article 1281 1301 1996-1944 Synthesis, Structure and Thermal Behavior of Oxalato-Bridged Rb+ and H3O+ Extended Frameworks with Different Dimensionalities 2010-02-23 doi: 10.3390/ma3021281 Hamza Kherfi Malika Hamadène Achoura Guehria-Laïdoudi Slimane Dahaoui Claude Lecomte http://www.mdpi.com/1996-1944/3/2/1269/ This article will highlight our recent work using conjugated oligomers as precursors to electroactive polymer films and self-assembling nanomaterials. One area of investigation has focused on nonbenzenoid aromaticity in the context of charge delocalization in conjugated polymers. In these studies, polymerizable pi-conjugated units were coupled onto unusual aromatic cores such as methano[10]annulene. This article will also show how biologically-inspired assembly of molecularly well-defined oligopeptides that flank pi-conjugated oligomers has resulted in the aqueous construction of 1-dimensional nanomaterials that encourage electronic delocalization among the pi-electron systems. http://www.mdpi.com/1996-1944/3/2/1269/ Tue, 23 Feb 2010 00:00:00 CET Materials 2010-02-23 3 2 Review 1269 1280 1996-1944 Non-Traditional Aromatic Topologies and Biomimetic Assembly Motifs as Components of Functional Pi-Conjugated Oligomers 2010-02-23 doi: 10.3390/ma3021269 John D. Tovar Stephen R. Diegelmann Patricia A. Peart http://www.mdpi.com/1996-1944/3/2/1244/ Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties. http://www.mdpi.com/1996-1944/3/2/1244/ Sun, 21 Feb 2010 00:00:00 CET Materials 2010-02-21 3 2 Review 1244 1268 1996-1944 Magnetic and Optical Properties of Submicron-Size Hollow Spheres 2010-02-21 doi: 10.3390/ma3021244 Quan-Lin Ye Hirofumi Yoshikawa Kunio Awaga http://www.mdpi.com/1996-1944/3/2/1228/ The leading cause of oral pain and tooth loss is from caries and their treatment include restoration using amalgam, resin, porcelain and gold, endodontic therapy and extraction. Resin composite restorations have grown popular over the last half a century because it can take shades more similar to enamel. Here, we discuss the history and use of resin, comparison between amalgam and resin, clinical procedures involved and finishing and polishing techniques for resin restoration. Although resin composite has aesthetic advantages over amalgam, one of the major disadvantage include polymerization shrinkage and future research is needed on reaction kinetics and viscoelastic behaviour to minimize shrinkage stress. http://www.mdpi.com/1996-1944/3/2/1228/ Fri, 19 Feb 2010 00:00:00 CET Materials 2010-02-19 3 2 Review 1228 1243 1996-1944 Review: Resin Composite Filling 2010-02-19 doi: 10.3390/ma3021228 Keith H. S. Chan Yanjie Mai Harry Kim Keith C. T. Tong Desmond Ng Jimmy C. M. Hsiao http://www.mdpi.com/1996-1944/3/2/1203/ Honeycomb monoliths consist of a large number of parallel channels that provide high contact efficiencies between the monolith and gas flow streams. These structures are used as adsorbents or supports for catalysts when large gas volumes are treated, because they offer very low pressure drop, short diffusion lengths and no obstruction by particulate matter. Carbon-based honeycomb monoliths can be integral or carbon-coated ceramic monoliths, and they take advantage of the versatility of the surface area, pore texture and surface chemistry of carbon materials. Here, we review the preparation methods of these monoliths, their characteristics and environmental applications. http://www.mdpi.com/1996-1944/3/2/1203/ Fri, 19 Feb 2010 00:00:00 CET Materials 2010-02-19 3 2 Review 1203 1227 1996-1944 Carbon-Based Honeycomb Monoliths for Environmental Gas-Phase Applications 2010-02-19 doi: 10.3390/ma3021203 Carlos Moreno-Castilla Agustín F. Pérez-Cadenas http://www.mdpi.com/1996-1944/3/2/1186/ Polystyrene-silica core-shell nanocomposite particles are successfully prepared via one-step Pickering emulsion polymerization. Possible mechanisms of Pickering emulsion polymerization are addressed in the synthesis of polystyrene-silica nanocomposite particles using 2,2-azobis(2-methyl-N-(2-hydroxyethyl)propionamide (VA-086) and potassium persulfate (KPS) as the initiator. Motivated by potential applications of “smart” composite particles in controlled drug delivery, the one-step Pickering emulsion polymerization route is further applied to synthesize polystyrene/poly(N-isopropylacrylamide) (PNIPAAm)-silica core-shell nanoparticles with N-isopropylacrylamide incorporated into the core as a co-monomer. The polystyrene/PNIPAAm-silica composite nanoparticles are temperature sensitive and can be taken up by human prostate cancer (PC3-PSMA) cells. http://www.mdpi.com/1996-1944/3/2/1186/ Tue, 16 Feb 2010 00:00:00 CET Materials 2010-02-16 3 2 Article 1186 1202 1996-1944 The One-Step Pickering Emulsion Polymerization Route for Synthesizing Organic-Inorganic Nanocomposite Particles 2010-02-16 doi: 10.3390/ma3021186 Huan Ma Mingxiang Luo Sriya Sanyal Kaushal Rege Lenore L. Dai http://www.mdpi.com/1996-1944/3/2/1172/ We set out to study the use of a series of ruthenocenes as possible and promising sources for ruthenium and/or ruthenium oxide film formation.The thermal stability of a series of ruthenocenes, including (η5-C5H4R)(η5-C5H4R´)Ru (1), R = R´ = H (3), R = H, R´ = CH2NMe2 (5), R = H, R´= C(O)Me (6), R = R´ = C(O)Me (7), R = H, R´ = C(O)(CH2)3CO2H (8), R = H, R´ = C(O)(CH2)2CO2H (9), R = H, R´ = C(O)(CH2)3CO2Me (10), R = H, R´= C(O)(CH2)2CO2Me (11), R = R´ = SiMe3), (η5-C4H3O-2,4-Me2)2Ru (2), and (η5-C5H5-2,4-Me2)2Ru (4) was studied by thermogravimetry. From these studies, it could be concluded that 1–4, 6 and 9–11 are the most thermally stable molecules. The sublimation pressure of these sandwich compounds was measured using a Knudsen cell. Among these, the compound 11 shows the highest vapor pressure. http://www.mdpi.com/1996-1944/3/2/1172/ Mon, 15 Feb 2010 00:00:00 CET Materials 2010-02-15 3 2 Article 1172 1185 1996-1944 Thermal Stability and Sublimation Pressures of Some Ruthenocene Compounds 2010-02-15 doi: 10.3390/ma3021172 M. Aslam Siddiqi Rehan A. Siddiqui Burak Atakan Nina Roth Heinrich Lang http://www.mdpi.com/1996-1944/3/2/1156/ Cylindrical elastomers were prepared through the UV-initiated crosslinking of terminally acrylated, 8,000 Da star-poly(trimethylene carbonate-co-ε-caprolactone) and star-poly(trimethylene carbonate-co-D,L-lactide). These elastomers were implanted intramuscularly into the hind legs of male Wistar rats to determine the influence of the comonomer on the weight loss, tissue response, and change in mechanical properties of the elastomer. The elastomers exhibited only a mild inflammatory response that subsided after the first week; the response was greater for the stiffer D,L-lactide-containing elastomers. The elastomers exhibited weight loss and sol content changes consistent with a bulk degradation mechanism. The D,L-lactide-containing elastomers displayed a nearly zeroorder change in Young’s modulus and stress at break over the 30 week degradation time, while the ε-caprolactone-containing elastomers exhibited little change in modulus or stress at break. http://www.mdpi.com/1996-1944/3/2/1156/ Thu, 11 Feb 2010 00:00:00 CET Materials 2010-02-11 3 2 Article 1156 1171 1996-1944 Tissue Response to, and Degradation Rate of, Photocrosslinked Trimethylene Carbonate-Based Elastomers Following Intramuscular Implantation 2010-02-11 doi: 10.3390/ma3021156 Laurianne Timbart Man Yat Tse Stephen C. Pang Brian G. Amsden http://www.mdpi.com/1996-1944/3/2/1138/ Although block- or granular-type sintered hydroxyapatite are known to show excellent tissue responses and good osteoconductivity, apatite powder elicits inflammatory response. For the fabrication of hydroxyapatite block or granules, sintering is commonly employed. However, the inorganic component of bone and tooth is not high crystalline hydroxyapatite but low crystalline B-type carbonate apatite. Unfortunately, carbonate apatite powder cannot be sintered due to its instability at high temperature. Another method to fabricate apatite block and/or granule is through phase transformation based on dissolution-precipitation reactions using a precursor phase. This reaction basically is the same as a setting and hardening reaction of calcium sulfate or plaster. In this paper, apatite block fabrication methods by phase transformation based on dissolution-precipitation reactions will be discussed, with a focus on the similarity of the setting and hardening reaction of calcium sulfate. http://www.mdpi.com/1996-1944/3/2/1138/ Wed, 10 Feb 2010 00:00:00 CET Materials 2010-02-10 3 2 Review 1138 1155 1996-1944 Bone Substitute Fabrication Based on Dissolution-Precipitation Reactions 2010-02-10 doi: 10.3390/ma3021138 Kunio Ishikawa http://www.mdpi.com/1996-1944/3/2/1125/ The Cp2ZrCl2/2 BuLi catalyzed co-polymerization of H2MeSiSiMeH2 and PhSiH3 was compared to the homo-polymerization of H2MeSiSiPhH2. In contrast to the co-polymerization, which gave molecular weights comparable to homo-polymerization of phenylsilane, the reaction of 1-methyl-2-phenyldisilane yielded a partially cross-linked high molecular weight polymer with very broad molecular weight distribution. A higher reactivity of phenyl-substituted silicon atoms compared to methyl-substituted ones was detected. Stoichiometric reactions of some disilanes with the slow dehydropolymerization catalyst CpCp*Hf(Cl)Si(SiMe3)3 gave metal disilanyl intermediates with selectivities that reflect the observed polymerization behavior. http://www.mdpi.com/1996-1944/3/2/1125/ Wed, 10 Feb 2010 00:00:00 CET Materials 2010-02-10 3 2 Article 1125 1137 1996-1944 Chemoselectivity in the Dehydrocoupling Synthesis of Higher Molecular Weight Polysilanes 2010-02-10 doi: 10.3390/ma3021125 Florian Lunzer Christoph Marschner http://www.mdpi.com/1996-1944/3/2/1104/ Timber gridshells have become a very popular, efficient, sustainable and beautiful structural application of timber. However, given the slender laths involved in this form of construction, there is concern over the durability of timber for this purpose, and Glass FRP (GFRP) laths have been proposed as a possible substitution. This paper considers this possibility. It goes on to look at the possible use of Basalt FRP (BFRP) for the same purpose, from the perspective of its creep characteristics. It is shown that the use of GFRP gridshells is a viable form of construction, and that enhanced durability characteristics of BFRP could lead to their adoption for gridshells, given that the creep characteristics of basalt fibres presented here are comparable to those of glass fibres. An altogether different form of timber construction is that of joist-and-floorboard. In the UK, there are thousands of historic buildings which use this floor construction, and a sizeable proportion of this building stock now requires upgrade, strengthening and/or stiffening to allow these buildings to be fit for purpose into the future. This paper goes on to consider the possible use of Carbon FRP (CFRP) to strengthen and stiffen such timber floors. It is shown that such strengthening and stiffening is entirely feasible, offering the potential for greatly enhanced stiffness, in particular. Further, it is shown that mechanical shear connection between CFRP and timber is best conducted using perpendicular-positioned screws, rather than raked screws. http://www.mdpi.com/1996-1944/3/2/1104/ Wed, 10 Feb 2010 00:00:00 CET Materials 2010-02-10 3 2 Article 1104 1124 1996-1944 Innovative Use and Characterization of Polymers for Timber-Related Construction 2010-02-10 doi: 10.3390/ma3021104 Antony Darby Tim Ibell Mark Evernden http://www.mdpi.com/1996-1944/3/2/1089/ Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape), intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment. http://www.mdpi.com/1996-1944/3/2/1089/ Tue, 09 Feb 2010 00:00:00 CET Materials 2010-02-09 3 2 Article 1089 1103 1996-1944 A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold 2010-02-09 doi: 10.3390/ma3021089 Kyriaki Kalaitzidou Hiroyuki Fukushima Lawrence T. Drzal http://www.mdpi.com/1996-1944/3/2/1049/ The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, a-FeSi2 and b-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR). The silicon-rich b-FeSi2 is a direct band gap material usable in light emitting diode (LED) applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM) of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe)-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions. http://www.mdpi.com/1996-1944/3/2/1049/ Tue, 09 Feb 2010 00:00:00 CET Materials 2010-02-09 3 2 Review 1049 1088 1996-1944 Organometallic Routes into the Nanorealms of Binary Fe-Si Phases 2010-02-09 doi: 10.3390/ma3021049 Manoj K. Kolel-Veetil Teddy M. Keller http://www.mdpi.com/1996-1944/3/2/1031/ Ductile fracture is the macroscopic result of a micromechanical process consisting in void nucleation and growth to coalescence. While growing in size, voids also evolve in shape because of the non-uniform deformation field in the surrounding material; this shape evolution is either disregarded or approximately accounted for by constitutive laws for porous-plastic solids. To assess the effect of void distortion on the overall properties of a porous-plastic material prior to any coalescence-dominated event, we here present a micromechanical study in which the void-containing material is treated as a two-phase (matrix and inclusion) composite. A cylindrical representative volume element (RVE), featuring elliptic cross-section and containing a coaxial and confocal elliptic cylindrical cavity, is considered. In case of a matrix obeying J2 flow theory of plasticity, the overall yield domain and the evolution laws for the volume fraction and aspect ratio of the void are obtained. Under assigned strain histories, these theoretical findings are then compared to finite element unit-cell simulations, in order to assess the capability of the proposed results to track microstructure evolution. The improvements with respect to the customarily adopted Gurson’s model are also discussed. http://www.mdpi.com/1996-1944/3/2/1031/ Thu, 04 Feb 2010 00:00:00 CET Materials 2010-02-04 3 2 Article 1031 1048 1996-1944 Effect of Microstructure Evolution on the Overall Response of Porous-Plastic Solids 2010-02-04 doi: 10.3390/ma3021031 Stefano Mariani http://www.mdpi.com/1996-1944/3/2/1015/ In this work we report the polymerization behaviour of natural clays (montmorillonites, MMT) as activating supports. These materials have been modified by treatment with different aluminium compounds in order to obtain enriched aluminium clays and to modify the global Brönsted/Lewis acidity. As a consequence, the intrinsic structural properties of the starting materials have been changed. These changes were studied and these new materials used for ethylene polymerization using a zirconocene complex as catalyst. All the systems were shown to be active in ethylene polymerization. The catalyst activity and the dependence on acid strength and textural properties have been also studied. The behaviour of an artificial silica (SBA 15) modified with an aluminium compound to obtain a silicoaluminate has been studied, but no ethylene polymerization activity has been found yet. http://www.mdpi.com/1996-1944/3/2/1015/ Wed, 03 Feb 2010 00:00:00 CET Materials 2010-02-03 3 2 Article 1015 1030 1996-1944 Silicoaluminates as “Support Activator” Systems in Olefin Polymerization Processes 2010-02-03 doi: 10.3390/ma3021015 Vanessa Tabernero Claudimar Camejo Pilar Terreros María Dolores Alba Tomás Cuenca http://www.mdpi.com/1996-1944/3/2/999/ Advances in the extraction, purification, and characterization of keratin proteins from hair and wool fibers over the past century have led to the development of a keratin-based biomaterials platform. Like many naturally-derived biomolecules, keratins have intrinsic biological activity and biocompatibility. In addition, extracted keratins are capable of forming self-assembled structures that regulate cellular recognition and behavior. These qualities have led to the development of keratin biomaterials with applications in wound healing, drug delivery, tissue engineering, trauma and medical devices. This review discusses the history of keratin research and the advancement of keratin biomaterials for biomedical applications. http://www.mdpi.com/1996-1944/3/2/999/ Wed, 03 Feb 2010 00:00:00 CET Materials 2010-02-03 3 2 Review 999 1014 1996-1944 A Review of Keratin-Based Biomaterials for Biomedical Applications 2010-02-03 doi: 10.3390/ma3020999 Jillian G. Rouse Mark E. Van Dyke http://www.mdpi.com/1996-1944/3/2/943/ This work reviews the use of porous silicon (PS) as a nanomaterial which is extensively investigated and utilized for various applications, e.g., in the fields of optics, sensor technology and biomedicine. Furthermore the combination of PS with one or more materials which are also nanostructured due to their deposition within the porous matrix is discussed. Such nanocompounds offer a broad avenue of new and interesting properties depending on the kind of involved materials as well as on their morphology. The filling of the pores performed by electroless or electrochemical deposition is described, whereas different morphologies, reaching from micro- to macro pores are utilized as host material which can be self-organized or fabricated by prestructuring. For metal-deposition within the porous structures, both ferromagnetic and non-magnetic metals are used. Emphasis will be put on self-arranged mesoporous silicon, offering a quasi-regular pore arrangement, employed as template for filling with ferromagnetic metals. By varying the deposition parameters the precipitation of the metal structures within the pores can be tuned in geometry and spatial distribution leading to samples with desired magnetic properties. The correlation between morphology and magnetic behaviour of such semiconducting/magnetic systems will be determined. Porous silicon and its combination with a variety of filling materials leads to nanocomposites with specific physical properties caused by the nanometric size and give rise to a multiplicity of potential applications in spintronics, magnetic and magneto-optic devices, nutritional food additives as well as drug delivery. http://www.mdpi.com/1996-1944/3/2/943/ Wed, 03 Feb 2010 00:00:00 CET Materials 2010-02-03 3 2 Review 943 998 1996-1944 Porous Silicon—A Versatile Host Material 2010-02-03 doi: 10.3390/ma3020943 Petra Granitzer Klemens Rumpf http://www.mdpi.com/1996-1944/3/2/918/ Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. Recent work at the National Research Council Canada in the area of concrete materials research has shown the potential of improving concrete properties by modifying the structure of cement hydrates, addition of nanoparticles and nanotubes and controlling the delivery of admixtures. This article will focus on a review of these innovative achievements. http://www.mdpi.com/1996-1944/3/2/918/ Wed, 03 Feb 2010 00:00:00 CET Materials 2010-02-03 3 2 Review 918 942 1996-1944 Cement and Concrete Nanoscience and Nanotechnology 2010-02-03 doi: 10.3390/ma3020918 Laila Raki James Beaudoin Rouhollah Alizadeh Jon Makar Taijiro Sato http://www.mdpi.com/1996-1944/3/2/897/ The synthesis and characterization of a Keggin-type mono-rhenium(V)-substituted polyoxotungstate are described. The dimethylammonium salt [Me2NH2]4[PW11ReVO40] was obtained as analytically pure homogeneous black-purple crystals by reacting mono-lacunary Keggin polyoxotungstate with [ReIVCl6]2- in water, followed by crystallization from acetone at ca. 5 °C. Single-crystal X-ray structural analysis of [PW11ReVO40]4- revealed a monomeric structure with overall Td symmetry. Characterization of [Me2NH2]4[PW11ReVO40] was also accomplished by elemental analysis, magnetic susceptibility, TG/DTA, FTIR, UV-vis, diffuse reflectance (DR) UV-vis, and solution 31P-NMR spectroscopy. Furthermore, [PW11ReVO40]4- and the Dawson-type dirhenium(V)-oxido-bridged polyoxotungstate [O{ReV(OH)(α2-P2W17O61)}2]14- were supported onto anatase TiO2 surface by the precipitation methods using CsCl and Pt(NH3)4Cl2. With these materials, hydrogen evolution from water in the presence of EDTA⋅2Na (ethylenediamine tetraacetic acid disodium salt) under visible light irradiation (≥400 nm) was achieved. http://www.mdpi.com/1996-1944/3/2/897/ Tue, 02 Feb 2010 00:00:00 CET Materials 2010-02-02 3 2 Article 897 917 1996-1944 EDTA-Reduction of Water to Molecular Hydrogen Catalyzed by Visible-Light-Response TiO2-Based Materials Sensitized by Dawson- and Keggin-Type Rhenium(V)-Containing Polyoxotungstates 2010-02-02 doi: 10.3390/ma3020897 Chika Nozaki Kato Kazunobu Hara Masao Kato Hidekuni Amano Konomi Sato Yusuke Kataoka Wasuke Mori http://www.mdpi.com/1996-1944/3/2/863/ The positive results of the performance of zirconia for orthopedics devices have led the dental community to explore possible esthetical and mechanical outcomes using this material. However, questions regarding long-term results have opened strong and controversial discussions regarding the utilization of zirconia as a substitute for alloys for restorations and implants. This narrative review presents the current knowledge on zirconia utilized for dental restorations, oral implant components, and zirconia oral implants, and also addresses laboratory tests and developments, clinical performance, and possible future trends of this material for dental healthcare. http://www.mdpi.com/1996-1944/3/2/863/ Mon, 01 Feb 2010 00:00:00 CET Materials 2010-02-01 3 2 Review 863 896 1996-1944 Performance of Zirconia for Dental Healthcare 2010-02-01 doi: 10.3390/ma3020863 Nelson R.F.A. Silva Irena Sailer Yu Zhang Paulo G. Coelho Petra C. Guess Anja Zembic Ralf J. Kohal http://www.mdpi.com/1996-1944/3/2/841/ This paper reviews the current array of complexes of relevance to achieving lanthanide mediated nitrogen fixation. A brief history of nitrogen fixation is described, including a limited discussion of successful transition metal facilitated nitrogen fixation systems. A detailed discussion of the numerous lanthanide-nitrogen species relevant to nitrogen fixation are discussed and are related to the Chatt cycle for nitrogen fixation. http://www.mdpi.com/1996-1944/3/2/841/ Mon, 01 Feb 2010 00:00:00 CET Materials 2010-02-01 3 2 Review 841 862 1996-1944 Dinitrogen and Related Chemistry of the Lanthanides: A Review of the Reductive Capture of Dinitrogen, As Well As Mono- and Di-aza Containing Ligand Chemistry of Relevance to Known and Postulated Metal Mediated Dinitrogen Derivatives 2010-02-01 doi: 10.3390/ma3020841 Michael G. Gardiner Damien N. Stringer http://www.mdpi.com/1996-1944/3/2/827/ The liquid crystalline dimer of 4-(4-pentenyloxy)benzoic acid, a member of the n-alkoxybenzoic acid homologous series, was synthesized using potassium carbonate supported on alumina as catalyst. The acid dimer complex exhibited three mesophases; identified as nematic, smectic X1 and smectic X2. Phase transition temperatures and the corresponding enthalpies were recorded using differential scanning calorimetry upon both heating and cooling. The mesophases were identified by detailed texture observations by variable temperature polarized light microscopy. The nematic phase was distinguished by a fluid Schlieren texture and defect points (four and two brushes) while the smectic phases were distinguished by rigid marble and mosaic textures, respectively. http://www.mdpi.com/1996-1944/3/2/827/ Fri, 29 Jan 2010 00:00:00 CET Materials 2010-01-29 3 2 Article 827 840 1996-1944 Probing the Texture of the Calamitic Liquid Crystalline Dimer of 4-(4-Pentenyloxy)benzoic Acid 2010-01-29 doi: 10.3390/ma3020827 Maher A. Qaddoura Kevin D. Belfield http://www.mdpi.com/1996-1944/3/2/815/ Biphasic calcium phosphates (BCP) have been sought after as biomaterials for the reconstruction of bone defects in maxillofacial, dental and orthopaedic applications. They have demonstrated proven biocompatibility, osteoconductivity, safety and predictability in in vitro, in vivo and clinical models. More recently, in vitro and in vivo studies have shown that BCP can be osteoinductive. In the field of tissue engineering, they represent promising scaffolds capable of carrying and modulating the behavior of stem cells. This review article will highlight the latest advancements in the use of BCP and the characteristics that create a unique microenvironment that favors bone regeneration. http://www.mdpi.com/1996-1944/3/2/815/ Fri, 29 Jan 2010 00:00:00 CET Materials 2010-01-29 3 2 Review 815 826 1996-1944 Biphasic Calcium Phosphate Ceramics for Bone Regeneration and Tissue Engineering Applications 2010-01-29 doi: 10.3390/ma3020815 Sonja Ellen Lobo Treena Livingston Arinzeh http://www.mdpi.com/1996-1944/3/2/800/ Spark plasma sintered 3Y-TZP has been investigated with respect to hydrothermal ageing and grinding. The sintering was performed between the temperatures of 1,100 and 1,600 °C for a soaking time of 5 minutes and the resulting materials were obtained with grain sizes between 65 to 800 nm and relative densities between 88.5 to 98.8%. Experiments on hydrothermal ageing in water vapour at 131 °C, 2 bars during 60 hours shows that phase stability is retained, elastic modulus and hardness of near surface region measured by nanoindentation does not change in fine grain (<200 nm) materials, in spite of porosity. In ground specimens, very small amount of transformation was found for all grain sizes studied. http://www.mdpi.com/1996-1944/3/2/800/ Thu, 28 Jan 2010 00:00:00 CET Materials 2010-01-28 3 2 Article 800 814 1996-1944 Stability of Nanocrystalline Spark Plasma Sintered 3Y-TZP 2010-01-28 doi: 10.3390/ma3020800 Ravikiran Chintapalli Alvaro Mestra Fernando García Marro Haixue Yan Michael Reece Marc Anglada http://www.mdpi.com/1996-1944/3/2/786/ We show why and how the spin state of transition-metal ions affects the thermoelectric properties of transition-metal oxides by investigating two perovskite-related oxides. In the A-site ordered cobalt oxide Sr3YCo4O10.5, partial substitution of Ca for Sr acts as chemical pressure, which compresses the unit cell volume to drive the spin state crossover, and concomitantly changes the magnetization and thermopower. In the perovskite rhodium oxide LaRhO3, partial substitution of Sr for La acts as hole-doping, and the resistivity and thermopower decrease systematically with the Sr concentration. The thermopower remains large values at high temperatures (>150 μV/K at 800 K), which makes a remarkable contrast to La1-xSrxCoO3. We associate this with the stability of the low spin state of the Rh3+ ions. http://www.mdpi.com/1996-1944/3/2/786/ Wed, 27 Jan 2010 00:00:00 CET Materials 2010-01-27 3 2 Article 786 799 1996-1944 Spin State Control of the Perovskite Rh/Co Oxides 2010-01-27 doi: 10.3390/ma3020786 Ichiro Terasaki Soichiro Shibasaki Shin Yoshida Wataru Kobayashi http://www.mdpi.com/1996-1944/3/2/764/ Mesoporous silica molecular sieves are a kind of unique catalyst support due to their large pore size and high surface area. Several methods have been developed to immobilize heteropolyacids (HPAs) inside the channels of these mesoporous silicas. The mesoporous silica-supported HPA materials have been widely used as recyclable catalysts in heterogeneous systems. They have shown high catalytic activities and shape selectivities in some reactions, compared to the parent HPAs in homogeneous systems. This review summarizes recent progress in the field of mesoporous silica-supported HPAs applied in the heterogeneous catalysis area and preparation of nanostructured metal oxides using HPAs as precursors and mesoporous silicas as hard templates. http://www.mdpi.com/1996-1944/3/2/764/ Wed, 27 Jan 2010 00:00:00 CET Materials 2010-01-27 3 2 Review 764 785 1996-1944 Progress of the Application of Mesoporous Silica-Supported Heteropolyacids in Heterogeneous Catalysis and Preparation of Nanostructured Metal Oxides 2010-01-27 doi: 10.3390/ma3020764 Yuanhang Ren Bin Yue Min Gu Heyong He http://www.mdpi.com/1996-1944/3/2/755/ The typical large specific surface area and high reactivity of nanostructured porous silicon (nanoPS) make this material very suitable for the development of sensors. Moreover, its biocompatibility and biodegradability opens the way to the development of biosensors. As such, in this work the use of nanoPS in the field of electrical biosensing is explored. More specifically, nanoPS-based devices with Al/nanoPS/Al and Au-NiCr/nanoPS/Au-NiCr structures were fabricated for the electrical detection of glucose and Escherichia Coli bacteria at different concentrations. The experimental results show that the current-voltage characteristics of these symmetric metal/nanoPS/metal structures strongly depend on the presence/absence and concentration of species immobilized on the surface. http://www.mdpi.com/1996-1944/3/2/755/ Wed, 27 Jan 2010 00:00:00 CET Materials 2010-01-27 3 2 Article 755 763 1996-1944 Towards the Development of Electrical Biosensors Based on Nanostructured Porous Silicon 2010-01-27 doi: 10.3390/ma3020755 Gonzalo Recio-Sánchez Vicente Torres-Costa Miguel Manso Darío Gallach Juan López-García Raúl J. Martín-Palma http://www.mdpi.com/1996-1944/3/1/741/ Green-chemistry type procedures were used to synthesize Pd0 nanostructures encapsulated by a vanadium-substituted Wells-Dawson-type polyoxometalate (Pd0@POM). The cyclic voltammogram run with the Pd0@POM-modified glassy carbon electrode shows well-defined waves, associated with Pd0 nanostructures and the VV/VIV redox couple. The Pd0@POM-modified electrode displayed remarkably reproducible cyclic voltammetry patterns. The hydrogen evolution reaction (HER) was selected as an illustrative example to test the electrocatalytic behavior of the electrode. The kinetic parameters of the HER show the high efficiency of the Pd0@POM-modified electrode. This is the first example of electrochemical characterization of a modified electrode based on a vanado-tungstic POM and Pd0 nanostructures. http://www.mdpi.com/1996-1944/3/1/741/ Tue, 26 Jan 2010 00:00:00 CET Materials 2010-01-26 3 1 Article 741 754 1996-1944 Pd0@Polyoxometalate Nanostructures as Green Electrocatalysts: Illustrative Example of Hydrogen Production 2010-01-26 doi: 10.3390/ma3010741 Rosa N. Biboum Bineta Keita Sylvain Franger Charles P. Nanseu Njiki Guangjin Zhang Jie Zhang Tianbo Liu Israel-Martyr Mbomekalle Louis Nadjo http://www.mdpi.com/1996-1944/3/1/704/ Silica or various silicate aerogels can be characterized by highly porous, open cell, low density structures. The synthesis parameters influence the three-dimensional porous structures by modifying the kinetics and mechanism of hydrolysis and condensation processes. Numerous investigations have shown that the structure of porous materials can be tailored by variations in synthesis conditions (e.g., the type of precursors, catalyst, and surfactants; the ratio of water/precursor; the concentrations; the medium pH; and the solvent). The objectives of this review are to summarize and elucidate the effects of chemical conditions on the nanoporous structure of sol-gel derived silicate aerogels. http://www.mdpi.com/1996-1944/3/1/704/ Tue, 26 Jan 2010 00:00:00 CET Materials 2010-01-26 3 1 Review 704 740 1996-1944 Influence of Chemical Conditions on the Nanoporous Structure of Silicate Aerogels 2010-01-26 doi: 10.3390/ma3010704 Katalin Sinkó http://www.mdpi.com/1996-1944/3/1/682/ This review describes the synthesis and characterization of inorganic materials containing polyoxometalates encapsulated in oxide matrices. Examples illustrating key aspects in terms of synthesis and applications are presented according to the nature of the final hybrid material: those based on non-structured silicas, on mesostructured silicas, on macrostructured silicas and on other oxides. In each part, key points of the synthetic protocols are highlighted and structural features and properties of the resultant hybrid nanocomposites are discussed. http://www.mdpi.com/1996-1944/3/1/682/ Mon, 25 Jan 2010 00:00:00 CET Materials 2010-01-25 3 1 Review 682 703 1996-1944 Inorganic Hybrid Materials with Encapsulated Polyoxometalates 2010-01-25 doi: 10.3390/ma3010682 Véronique Dufaud Frédéric Lefebvre http://www.mdpi.com/1996-1944/3/1/672/ Arrays of aligned multi-walled carbon nanotube-ionic liquid (MIL) were assembled on silicon wafers (Si-MIL). Formation of Si-MIL was confirmed by ATR-FTIR, AFM and Raman techniques. The electrochemical measurements indicated that Si-MIL showed good electrocatalysis towards oxygen reduction compared with MIL drop-cast on a glassy carbon electrode. http://www.mdpi.com/1996-1944/3/1/672/ Mon, 25 Jan 2010 00:00:00 CET Materials 2010-01-25 3 1 Article 672 681 1996-1944 Preparation of Multi-Walled Carbon Nanotube/Amino-Terminated Ionic Liquid Arrays and Their Electrocatalysis towards Oxygen Reduction 2010-01-25 doi: 10.3390/ma3010672 Zhijuan Wang Rose-Marie Latonen Carita Kvarnström Ari Ivaska Li Niu http://www.mdpi.com/1996-1944/3/1/656/ The electrorheological properties (ER) of natural rubber (XL)/alumina (Al2O3) composites were investigated in oscillatory shear mode under DC electrical field strengths between 0 to 2 kV/mm. SEM micrographs indicate a mean particle size of 9.873 ± 0.034 µm and particles that are moderately dispersed in the matrix. The XRD patterns indicate Al2O3 is of the β-phase polytype which possesses high ionic conductivity. The storage modulus (G′) of the composites, or the rigidity, increases by nearly two orders of magnitude, with variations in particle volume fraction and electrical field strength. The increase in the storage modulus is caused the ionic polarization of the alumina particles and the induced dipole moments set up in the natural rubber matrix. http://www.mdpi.com/1996-1944/3/1/656/ Fri, 22 Jan 2010 00:00:00 CET Materials 2010-01-22 3 1 Article 656 671 1996-1944 Electrical and Electrorheological Properties of Alumina/Natural Rubber (STR XL) Composites 2010-01-22 doi: 10.3390/ma3010656 Nuchnapa Tangboriboon Nuttapot Uttanawanit Mean Longtong Piraya Wongpinthong Anuvat Sirivat Ruksapong Kunanuruksapong http://www.mdpi.com/1996-1944/3/1/638/ Prevention of the coagulation cascade and platelet activation is the foremost demand for biomaterials in contact with blood. In this review we describe the underlying mechanisms of these processes and offer the current state of antithrombotic strategies. We give an overview of methods to prevent protein and platelet adhesion, as well as techniques to immobilize biochemically active molecules on biomaterial surfaces. Finally, recent strategies in biofunctionalization by endothelial cell seeding as well as their possible clinical applications are discussed. http://www.mdpi.com/1996-1944/3/1/638/ Fri, 22 Jan 2010 00:00:00 CET Materials 2010-01-22 3 1 Review 638 655 1996-1944 Current Strategies in Cardiovascular Biomaterial Functionalization 2010-01-22 doi: 10.3390/ma3010638 Simon Schopka Thomas Schmid Christof Schmid Karla Lehle http://www.mdpi.com/1996-1944/3/1/614/ Semiconductor nanocrystals hybridized with functional ligands represent an important new class of composite nanomaterials. The development of these new nanoscale building blocks has intensified over the past few years and offer significant advantages in a wide array of applications. Functional ligands allow for incorporation of nanocrystals into areas where their unique photophysics can be exploited. Energy and charge transfer between the ligands and the nanocrystal also result in enhanced physical properties that can be tuned by the choice of ligand architecture. Here, progress in the development and applications involving this new class of composite materials will be discussed. http://www.mdpi.com/1996-1944/3/1/614/ Fri, 22 Jan 2010 00:00:00 CET Materials 2010-01-22 3 1 Review 614 637 1996-1944 Semiconductor Nanocrystals Hybridized with Functional Ligands: New Composite Materials with Tunable Properties 2010-01-22 doi: 10.3390/ma3010614 Matthew McDowell Ashley E. Wright Nathan I. Hammer http://www.mdpi.com/1996-1944/3/1/585/ In this review, the dielectric permittivity of dielectric mixtures is discussed in view of the spectral density representation method. A distinct representation is derived for predicting the dielectric properties, permittivities ε, of mixtures. The presentation of the dielectric properties is based on a scaled permittivity approach, ξ = (εe − εm)(εi − εm)−1, where the subscripts e, m and i denote the dielectric permittivities of the effective, matrix and inclusion media, respectively [Tuncer, E. J. Phys.: Condens. Matter 2005, 17, L125]. This novel representation transforms the spectral density formalism to a form similar to the distribution of relaxation times method of dielectric relaxation. Consequently, I propose that any dielectric relaxation formula, i.e., the Havriliak-Negami empirical dielectric relaxation expression, can be adopted as a scaled permittivity. The presented scaled permittivity representation has potential to be improved and implemented into the existing data analyzing routines for dielectric relaxation; however, the information to extract would be the topological/morphological description in mixtures. To arrive at the description, one needs to know the dielectric properties of the constituents and the composite prior to the spectral analysis. To illustrate the strength of the representation and confirm the proposed hypothesis, the Landau-Lifshitz/Looyenga (LLL) [Looyenga, H. Physica 1965, 31, 401] expression is selected. The structural information of a mixture obeying LLL is extracted for different volume fractions of phases. Both an in-house computational tool based on the Monte Carlo method to solve inverse integral transforms and the proposed empirical scaled permittivity expression are employed to estimate the spectral density function of the LLL expression. The estimated spectral functions for mixtures with different inclusion concentration compositions show similarities; they are composed of a couple of bell-shaped distributions, with coinciding peak locations but different heights. It is speculated that the coincidence in the peak locations is an absolute illustration of the self-similar fractal nature of the mixture topology (structure) created with the LLL expression. Consequently, the spectra are not altered significantly with increased filler concentration level—they exhibit a self-similar spectral density function for different concentration levels. Last but not least, the estimated percolation strengths also confirm the fractal nature of the systems characterized by the LLL mixture expression. It is concluded that the LLL expression is suitable for complex composite systems that have hierarchical order in their structure. These observations confirm the finding in the literature. http://www.mdpi.com/1996-1944/3/1/585/ Thu, 21 Jan 2010 00:00:00 CET Materials 2010-01-21 3 1 Review 585 613 1996-1944 Geometrical Description in Binary Composites and Spectral Density Representation 2010-01-21 doi: 10.3390/ma3010585 Enis Tuncer http://www.mdpi.com/1996-1944/3/1/572/ Thermo-exfoliated graphite (TEG)/CuO/Cu2(OH)3NO3:(Co2+/Fe3+) composites were prepared using a wet impregnation method and subsequent thermal treatment. The physicochemical characterization of the composites was carried out by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Ar temperature-desorption techniques. The catalytic efficiency toward CO conversion to CO2 was examined under atmospheric pressure. Characterization of species adsorbed over the composites taken after the activity tests were performed by means of temperature programmed desorption massspectrometry (TPD MS). (TEG)/CuO/Cu2(OH)3NO3:(Co2+/Fe3+) composites show superior performance results if lower temperatures and extra treatment with H2SO4 or HNO3 are used at the preparation stages. The catalytic properties enhancements can be related to the Cu2(OH)3NO3 phase providing reaction centers for the CO conversion. It has been found that prevalence of low-temperature states of desorbed CO2 over high-temperature ones in the TPD MS spectra is characteristic of the most active composite catalysts. http://www.mdpi.com/1996-1944/3/1/572/ Wed, 20 Jan 2010 00:00:00 CET Materials 2010-01-20 3 1 Article 572 584 1996-1944 Thermo-Exfoliated Graphite Containing CuO/Cu2(OH)3NO3:(Co2+/Fe3+) Composites: Preparation, Characterization and Catalytic Performance in CO Conversion 2010-01-20 doi: 10.3390/ma3010572 Elena V. Ischenko Ludmila Yu. Matzui Snezhanna V. Gayday Ludmila L. Vovchenko Tatyana V. Kartashova Vladyslav V. Lisnyak http://www.mdpi.com/1996-1944/3/1/563/ A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force) were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a stronginterpenetration of adjacent layers was observed. http://www.mdpi.com/1996-1944/3/1/563/ Wed, 20 Jan 2010 00:00:00 CET Materials 2010-01-20 3 1 Article 563 571 1996-1944 Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites 2010-01-20 doi: 10.3390/ma3010563 Fabrizio Quadrini Erica Anna Squeo Claudia Prosperi http://www.mdpi.com/1996-1944/3/1/536/ Porous insulators are utilized in the wiring structure of microelectronic devices as a means of reducing, through low dielectric permittivity, power consumption and signal delay in integrated circuits. They are typically based on low density modifications of amorphous SiO2 known as SiCOH or carbon-doped oxides, in which free volume is created through the removal of labile organic phases. Porous dielectrics pose a number of technological challenges related to chemical and mechanical stability, particularly in regard to semiconductor processing methods. This review discusses porous dielectric film preparation techniques, key issues encountered, and mitigation strategies. http://www.mdpi.com/1996-1944/3/1/536/ Mon, 18 Jan 2010 00:00:00 CET Materials 2010-01-18 3 1 Review 536 562 1996-1944 Porous Dielectrics in Microelectronic Wiring Applications 2010-01-18 doi: 10.3390/ma3010536 Vincent McGahay http://www.mdpi.com/1996-1944/3/1/519/ Calcium phosphate cements have been in clinical use for the last 10 years. Their most salient features include good biocompatibility, excellent bioactivity, self-setting characteristics, low setting temperature, adequate stiffness, and easy shaping to accomodate any complicated geometry. They are commonly used in filling bone defects and trauma surgeries as mouldable paste-like bone substitute materials. Substitution of trace elements, such as Mg, Sr and Zn ions, into the structure of calcium phosphates is the subject of widespread investigation nowadays, because of their impending role in the biological process. Subtle differences in composition and structure of these materials may have a profound effect on their in vivo behaviour. Therefore, the main goal of this paper is to provide a simple, but comprehensive overview of the present achievements relating to brushite-forming cements doped with Mg, Zn and Sr, and to identify new developments and trends. In particular, the influence of ionic substitution on the chemical, physical and biological properties of these materials is discussed. http://www.mdpi.com/1996-1944/3/1/519/ Mon, 18 Jan 2010 00:00:00 CET Materials 2010-01-18 3 1 Review 519 535 1996-1944 Brushite-Forming Mg-, Zn- and Sr-Substituted Bone Cements for Clinical Applications 2010-01-18 doi: 10.3390/ma3010519 Sandra Pina José M.F. Ferreira http://www.mdpi.com/1996-1944/3/1/503/ Reaction products of titanium(IV) sulfate in HCl-acidic aqueous solution with the dimeric species linked through three intermolecular Ti-O-Ti bonds of the two tri-titanium(IV)-substituted α-Keggin polyoxometalate (POM) subunits are described. Two novel titanium(IV)-containing α-Keggin POMs were obtained under different conditions. One product was a dimeric species through two intermolecular Ti-O-Ti bonds of the two tetra-titanium(IV)-substituted α-Keggin POM subunits, i.e., [[{Ti(H2O)3}2(μ-O)](α-PW9Ti2O38)]26- (1). The other product was a monomeric α-Keggin species containing the tetra-titanium(IV) oxide cluster and two coordinated sulfate ions, i.e., [{Ti4(μ-O)3(SO4)2(H2O)8}(α-PW9O34)]3- (2). Molecular structures of 1 and 2 were also discussed based on host (lacunary site)-guest (titanium atom) chemistry. http://www.mdpi.com/1996-1944/3/1/503/ Fri, 15 Jan 2010 00:00:00 CET Materials 2010-01-15 3 1 Article 503 518 1996-1944 Transformation of Tri-Titanium(IV)-Substituted α-Keggin Polyoxometalate (POM) into Tetra-Titanium(IV)-Substituted POMs : Reaction Products of Titanium(IV) Sulfate with the Dimeric Keggin POM Precursor under Acidic Conditions 2010-01-15 doi: 10.3390/ma3010503 Yuki Mouri Yoshitaka Sakai Yoshitaka Kobayashi Shoko Yoshida Kenji Nomiya http://www.mdpi.com/1996-1944/3/1/467/ We review our approach to the generation of nanoporous materials, both semiconducting and metallic, which leads to the existence of nanopores within the bulk structure. This method, which we have named as the expanding lattice method, is a novel transferable approach which consists first of constructing crystalline supercells with a large number of atoms and a density close to the real value and then lowering the density by increasing the volume. The resulting supercells are subjected to either ab initio or parameterized—Tersoff-based—molecular dynamics processes at various temperatures, all below the corresponding bulk melting points, followed by geometry relaxations. The resulting samples are essentially amorphous and display pores along some of the “crystallographic” directions without the need of incorporating ad hoc semiconducting atomic structural elements such as graphene-like sheets and/or chain-like patterns (reconstructive simulations) or of reproducing the experimental processes (mimetic simulations). We report radial (pair) distribution functions, nanoporous structures of C and Si, and some computational predictions for their vibrational density of states. We present numerical estimates and discuss possible applications of semiconducting materials for hydrogen storage in potential fuel tanks. Nanopore structures for metallic elements like Al and Au also obtained through the expanding lattice method are reported. http://www.mdpi.com/1996-1944/3/1/467/ Fri, 15 Jan 2010 00:00:00 CET Materials 2010-01-15 3 1 Review 467 502 1996-1944 A New Approach to the Computer Modeling of Amorphous Nanoporous Structures of Semiconducting and Metallic Materials: A Review 2010-01-15 doi: 10.3390/ma3010467 Cristina Romero Juan C. Noyola Ulises Santiago Renela M. Valladares Alexander Valladares Ariel A. Valladares http://www.mdpi.com/1996-1944/3/1/452/ Cow bone charcoal (CBC) was synthesized and used for the removal of metals ions (manganese, iron, nickel and copper) from aqueous solutions. Two different adsorption models were used for analyzing the data. Adsorption capacities were determined: copper ions exhibit the greatest adsorption on cow bone charcoal because of their size and pH conditions. Adsorption capacity varies as a function of pH. Adsorption isotherms from aqueous solution of heavy metals on CBC were determined. Adsorption isotherms are consistent with Langmuir´s adsorption model. Adsorbent quantity and immersion enthalpy were studied. http://www.mdpi.com/1996-1944/3/1/452/ Thu, 14 Jan 2010 00:00:00 CET Materials 2010-01-14 3 1 Article 452 466 1996-1944 Removal of Mn, Fe, Ni and Cu Ions from Wastewater Using Cow Bone Charcoal 2010-01-14 doi: 10.3390/ma3010452 Juan Carlos Moreno Rigoberto Gómez Liliana Giraldo http://www.mdpi.com/1996-1944/3/1/434/ The present paper aims at computational simulations of particle reinforced Metal Matrix Composites as well as parts and specimens made thereof. An incremental Mori-Tanaka approach with isotropization of the matrix tangent operator is adopted. It is extended to account for large strains by means of co-rotational Cauchy stresses and logarithmic strains and is implemented into Finite Element Method software as constitutive material law. Periodic unit cell predictions in the finite strain regime are used to verify the analytical approach with respect to non-proportional loading scenarios and assumptions concerning finite strain localization. The response of parts made of Metal Matrix Composites is predicted by a multiscale approach based on these two micromechanical methods. Results for the mesoscopic stress and strain fields as well as the microfields are presented to demonstrate to capabilities of the developed methods. http://www.mdpi.com/1996-1944/3/1/434/ Wed, 13 Jan 2010 00:00:00 CET Materials 2010-01-13 3 1 Article 434 451 1996-1944 An Incremental Mori-Tanaka Homogenization Scheme for Finite Strain Thermoelastoplasticity of MMCs 2010-01-13 doi: 10.3390/ma3010434 Heinz E. Pettermann Christopher O. Huber Mathias H. Luxner Sergio Nogales Helmut J. Böhm http://www.mdpi.com/1996-1944/3/1/401/ Transition metal sulfides are scientifically and technologically important materials. This review summarizes recent progress on the synthetic fabrication of transition metal sulfides nanocrystals with controlled shape, size, and surface functionality. Special attention is paid to the case of MoS2 nanoparticles, where organic (surfactant, polymer), inorganic (support, promoter, doping) compounds and intercalation chemistry are applied. http://www.mdpi.com/1996-1944/3/1/401/ Tue, 12 Jan 2010 00:00:00 CET Materials 2010-01-12 3 1 Review 401 433 1996-1944 Synthetic Fabrication of Nanoscale MoS2-Based Transition Metal Sulfides 2010-01-12 doi: 10.3390/ma3010401 Shutao Wang Changhua An Jikang Yuan http://www.mdpi.com/1996-1944/3/1/386/ Extrudate swell is often observed to be weakened in nanocomposites compared to the pure polymer matrix. A theory quantifying this would be significant either for optimum processing or for understanding their viscoelasticity. A unified extrudate swell correlation with material properties and capillary parameters was suggested for polymer melt and their nanocomposites when considering the reservoir entry effect. More importantly, it was the first to find that the composite swell ratio can be the matrix swell ratio multiplied by the concentration shift factor, which is similar to the dynamic moduli expression for composites. The factor is a function of the shear field (stress or shear rate), filler content, filler internal structure and the surface state as well as the matrix properties. Several sets of swell data for nanocomposites were chosen from publications to test the new theories. The proposed quantitative model displayed good fit for the five kinds of nanocomposites, which verified the rationality of the swell theory for nanocomposites. http://www.mdpi.com/1996-1944/3/1/386/ Tue, 12 Jan 2010 00:00:00 CET Materials 2010-01-12 3 1 Article 386 400 1996-1944 Description of Extrudate Swell for Polymer Nanocomposites 2010-01-12 doi: 10.3390/ma3010386 Kejian Wang http://www.mdpi.com/1996-1944/3/1/369/ Difurfurylidene trehalose (DFTreh) was synthesized from trehalose and furfural by an acetalization reaction. Maleimide-terminated dimethylsiloxane oligomers (DMS-BMI) were synthesized from amine-terminated dimethylsiloxane oligomers by condensation with maleic anhydride. Three types of DMS-BMI with different length were prepared. Trehalose-based polymers were synthesized by Diels-Alder reaction of DFTreh and DMS-BMI. The reaction proceeded at 40~70 °C to produce a polymer with a maximum weight average molecular weight of ~19,000. The thermal degradation temperature increased with the increase of the length of the oligo(dimethylsiloxane) units. The differential scanning calorimetry (DSC) measurements revealed the glass transition temperature (Tg) of the polymer at -130~-120 °C, and no distinct Tg not observed above room temperature in the DSC measurement. The polymer products are not liquid at room temperature, and solid films can be obtained by casting from solution, implying a phase-separated structure made up of soft and hard segments. The phase-separated structure was confirmed by transmission electron microscope (TEM) study. The DSC curve of the polymer showed a broad endothermic peak at 110~160 °C, suggesting that a retro-Diels-Alder reaction occurred. When a N,N-dimethylformamide solution of the polymer was kept at 100 °C and the resulting solution was analyzed by gel permeation chromatography (GPC), the molecular weight decreased and monomers appeared. http://www.mdpi.com/1996-1944/3/1/369/ Tue, 12 Jan 2010 00:00:00 CET Materials 2010-01-12 3 1 Article 369 385 1996-1944 Synthesis and Properties of Trehalose-Based Flexible Polymers Prepared from Difurfurylidene Trehalose and Maleimide- Terminated Oligo(dimethylsiloxane) by Diels-Alder Reactions 2010-01-12 doi: 10.3390/ma3010369 Naozumi Teramoto Masashi Niwa Mitsuhiro Shibata http://www.mdpi.com/1996-1944/3/1/351/ Over the past forty years, the technological evolution of ceramics for dental applications has been remarkable, as new materials and processing techniques are steadily being introduced. The improvement in both strength and toughness has made it possible to expand the range of indications to long-span fixed partial prostheses, implant abutments and implants. The present review provides a state of the art of ceramics for dental applications. http://www.mdpi.com/1996-1944/3/1/351/ Mon, 11 Jan 2010 00:00:00 CET Materials 2010-01-11 3 1 Review 351 368 1996-1944 Ceramics for Dental Applications: A Review 2010-01-11 doi: 10.3390/ma3010351 Isabelle Denry Julie A. Holloway http://www.mdpi.com/1996-1944/3/1/329/ The objective of this article is to provide a review of friction stir processing (FSP) technology and its application for microstructure modification of particle reinforced composite materials. The main focus of FSP was on aluminum based alloys and composites. Recently, many researchers have investigated this technology for treating other alloys and materials including stainless steels, magnesium, titanium, and copper. It is shown that FSP technology is very effective in microstructure modification of reinforced metal matrix composite materials. FSP has also been used in the processing and structure modification of polymeric composite materials. Compared with other manufacturing processes, friction stir processing has the advantage of reducing distortion and defects in materials. The layout of this paper is as follows. The friction stir processing technology will be presented first. Then, the application of this technology in manufacturing and structure modification of particle reinforced composite materials will be introduced. Future application of friction stir processing in energy field, for example, for vanadium alloy and composites will be discussed. Finally, the challenges for improving friction stir processing technology will be mentioned. http://www.mdpi.com/1996-1944/3/1/329/ Mon, 11 Jan 2010 00:00:00 CET Materials 2010-01-11 3 1 Review 329 350 1996-1944 Friction Stir Processing of Particle Reinforced Composite Materials 2010-01-11 doi: 10.3390/ma3010329 Yong X. Gan Daniel Solomon Michael Reinbolt http://www.mdpi.com/1996-1944/3/1/318/ Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied. The addition of Ag and Zn was found to enhance the formation of CuAlO2 phase and to increase the electrical conductivity. The addition of Ag or Ag and Ni on the other hand decreases the electrical conductivity. The highest power factor of 1.26 × 10-4 W/mK2 was obtained for the addition of Ag and Zn at 1,060 K, indicating a significant improvement compared with the non-doped CuAlO2 sample. http://www.mdpi.com/1996-1944/3/1/318/ Mon, 11 Jan 2010 00:00:00 CET Materials 2010-01-11 3 1 Article 318 328 1996-1944 The Effect of (Ag, Ni, Zn)-Addition on the Thermoelectric Properties of Copper Aluminate 2010-01-11 doi: 10.3390/ma3010318 Shun-ichi Yanagiya Ngo Van Nong Jianxiao Xu Nini Pryds http://www.mdpi.com/1996-1944/3/1/264/ Interface reactions in composite systems often determine their overall properties, since product phases usually formed at interfaces during composite fabrication processing make up a large portion of the composites. Since most composite materials represent a ternary or higher order materials system, many studies have focused on analyses of diffusion phenomena and kinetics in multicomponent systems. However, the understanding of the kinetic behavior increases the complexity, since the kinetics of each component during interdiffusion reactions need to be defined for interpreting composite behaviors. From this standpoint, it is important to clarify the interface reactions for producing compatible interfaces with desired product phases. A thermodynamic evaluation such as a chemical potential of involving components can provide an understanding of the diffusion reactions, which govern diffusion pathways and product phase formation. A strategic approach for designing compatible interfaces is discussed in terms of chemical potential diagrams and interface morphology, with some material examples. http://www.mdpi.com/1996-1944/3/1/264/ Fri, 08 Jan 2010 00:00:00 CET Materials 2010-01-08 3 1 Review 264 295 1996-1944 Interface Reactions and Synthetic Reaction of Composite Systems 2010-01-08 doi: 10.3390/ma3010264 Joon Sik Park Jeong Min Kim http://www.mdpi.com/1996-1944/3/1/296/ This paper is devoted to the description of the general relationships between microscopic and macroscopic mechanical quantities in non-linear mechanics. From a thermodynamical viewpoint, it is only necessary to know the two macroscopic potentials (macroscopic free energy and macroscopic potential of dissipation) to describe the state of the body and its quasistatic evolution. These global potentials are the averages of the local ones. We point out some particular cases of non-linearities, especially the case of damaged materials. http://www.mdpi.com/1996-1944/3/1/296/ Fri, 08 Jan 2010 00:00:00 CET Materials 2010-01-08 3 1 Review 296 317 1996-1944 On Micro-Macro Transition in Non-Linear Mechanics 2010-01-08 doi: 10.3390/ma3010296 Claude Stolz http://www.mdpi.com/1996-1944/3/1/241/ Many medical conditions require surgical reconstruction of hollow organs. Tissue engineering of organs and tissues is a promising new technique without harvest site morbidity. An ideal biomaterial should be biocompatible, support tissue formation and provide adequate structural support. It should degrade gradually and provide an environment allowing for cell-cell interaction, adhesion, proliferation, migration, and differentiation. Although tissue formation is feasible, functionality has never been demonstrated. Mainly the lack of proper innervation and vascularisation are hindering contractility and normal function. In this chapter we critically review the current state of engineering hollow organs with a special focus on innervation and vascularisation. http://www.mdpi.com/1996-1944/3/1/241/ Fri, 08 Jan 2010 00:00:00 CET Materials 2010-01-08 3 1 Review 241 263 1996-1944 Scaffold Characteristics for Functional Hollow Organ Regeneration 2010-01-08 doi: 10.3390/ma3010241 Maya Horst Srinivas Madduri Rita Gobet Tullio Sulser Heike Hall Daniel Eberli http://www.mdpi.com/1996-1944/3/1/232/ The synthesis and structural characterization of two families of low-valent vanadium(III) {V6P4} and vanadium(III/IV) {V13P8} phosphonate complexes are reported. Magnetic characterization is reported for representative examples. http://www.mdpi.com/1996-1944/3/1/232/ Fri, 08 Jan 2010 00:00:00 CET Materials 2010-01-08 3 1 Article 232 240 1996-1944 Families of Molecular Hexa- and Trideca-Metallic Vanadium(III) Phosphonates 2010-01-08 doi: 10.3390/ma3010232 Sumit Khanra Rachel Shaw Madeleine Helliwell Floriana Tuna Christopher A. Muryn Eric J. L. McInnes Richard E. P. Winpenny http://www.mdpi.com/1996-1944/3/1/216/ The present study is concerned with the assessment of the relative resistance of a monumental dolomitic limestone (Laspra – Spain) used as building material in stone monuments and submitted to artificial ageing by SO2 dry deposition in the presence of humidity. To investigate the protection efficiency of different polymeric coatings, three commercially available siloxane-based oligomers (Lotexan-N, Silres BS 290 and Tegosivin HL 100) and a newly synthesized hybrid nanocomposite with silsesquioxane units (TMSPMA) were used. A comparative assessment of the data obtained in this study underlines that a better limestone protection was obtained when treated with the hybrid nanocomposite with silsesquioxane units. http://www.mdpi.com/1996-1944/3/1/216/ Thu, 07 Jan 2010 00:00:00 CET Materials 2010-01-07 3 1 Article 216 231 1996-1944 Effect of SO2 Dry Deposition on Porous Dolomitic Limestones 2010-01-07 doi: 10.3390/ma3010216 Mihaela Olaru Magdalena Aflori Bogdana Simionescu Florica Doroftei Lacramioara Stratulat http://www.mdpi.com/1996-1944/3/1/201/ A new approach for the chemical modification of the surface of paper based on the application of colloidal mixtures containing cationic starch and polyoxometalates on uncoated base paper is presented. Polyoxometalates with the Keggin-type structure and physical properties similar to those presented by coating pigments, namely H3PW12O40·23H2O, H4SiW12O40·24H2O, and K7PW11O39·9H2O, have been used in order to improve the quality of inkjet printing. The analysis of the different samples by FTIR-ATR spectroscopy showed the presence of the polyoxometalates (and the cationic starch) on the top surface of the paper. In addition, the determination of surface energy parameters, namely the polar component (σsp) and the dispersive component (σsd) of the surface energy, by contact angle measurements revealed that, for the new samples, the polar component level was much higher than that of the uncoated base paper. The quality of inkjet printing, evaluated by parameters such as the gamut area and the optical density, was considerably improved by these surface treatments. http://www.mdpi.com/1996-1944/3/1/201/ Thu, 07 Jan 2010 00:00:00 CET Materials 2010-01-07 3 1 Article 201 215 1996-1944 A New Approach for the Modification of Paper Surface Properties Using Polyoxometalates 2010-01-07 doi: 10.3390/ma3010201 Mikhail S. Saraiva José A. F. Gamelas António P. Mendes de Sousa Bruno M. Reis José L. Amaral Paulo J. Ferreira http://www.mdpi.com/1996-1944/3/1/165/ Artificial nanomembranes may be defined as synthetic freestanding structures with a thickness below 100 nm and a very large aspect ratio, of at least a few orders of magnitude. Being quasi-2D, they exhibit a host of unusual properties useful for various applications in energy harvesting, sensing, optics, plasmonics, biomedicine, etc. We review the main approaches to nanomembrane functionalization through nanocompositing, which ensures performance far superior to that of simple nanomembranes. These approaches include lamination (stacking of nanometer-thin strata of different materials), introduction of nanoparticle fillers into the nanomembrane scaffold, nanomembrane surface sculpting and modification through patterning (including formation of nanohole arrays and introduction of ion channels similar in function to those in biological nanomembranes). We also present some of our original results related to functionalization of metal matrix composite nanomembranes. http://www.mdpi.com/1996-1944/3/1/165/ Thu, 07 Jan 2010 00:00:00 CET Materials 2010-01-07 3 1 Review 165 200 1996-1944 Functionalization of Artificial Freestanding Composite Nanomembranes 2010-01-07 doi: 10.3390/ma3010165 Zoran Jakšić Jovan Matovic http://www.mdpi.com/1996-1944/3/1/158/ Inorganic-organic hybrid crystals containing α-octamolybdate (Mo8) or hexamolybdate (Mo6) were isolated by using hexadecyltrimethylammonium (C16) surfactant. The packing mode of the inorganic layers depended on a difference in the polyoxomolybdate molecular structure. The structure for both crystals consisted of alternate stacking of C16 organic bilayers and polyoxomolybdate inorganic layers with a periodicity of 24.4–24.6 Å. However, the C16-Mo8 crystals contained Mo8 monolayers, while the C16-Mo6 crystals contained Mo6 bilayers. These lattice structures for the polyoxometalate/organic hybrid will be designed by the molecular structures of polyoxometalate. http://www.mdpi.com/1996-1944/3/1/158/ Wed, 06 Jan 2010 00:00:00 CET Materials 2010-01-06 3 1 Article 158 164 1996-1944 Controllable Layered Structures in Polyoxomolybdate-Surfactant Hybrid Crystals 2010-01-06 doi: 10.3390/ma3010158 Takeru Ito Toshihiro Yamase http://www.mdpi.com/1996-1944/3/1/150/ A mononuclear complex [MoOCl4(H2O)]− readily forms a metal−metal bonded {Mo2O4}2+ core. A high content of pyridine in the reaction mixture prevents further aggregation of dinuclear cores into larger clusters and a neutral, dinuclear complex with the [Mo2O4Cl2(Py)4] composition is isolated as a product. Solid state structures of two compounds containing this complex, [Mo2O4Cl2(Py)4]·2.25Py (1) and [Mo2O4Cl2(Py)4]·1.5PyHCl (2), were investigated by X-ray crystallography. http://www.mdpi.com/1996-1944/3/1/150/ Mon, 04 Jan 2010 00:00:00 CET Materials 2010-01-04 3 1 Article 150 157 1996-1944 Syntheses and a Solid State Structure of a Dinuclear Molybdenum(V) Complex with Pyridine 2010-01-04 doi: 10.3390/ma3010150 Barbara Modec Jon Zubieta http://www.mdpi.com/1996-1944/3/1/127/ Carbon nanotubes (CNTs) are nanoscale cylinders of graphene with exceptional properties such as high mechanical strength, high aspect ratio and large specific surface area. To exploit these properties for membranes, macroscopic structures need to be designed with controlled porosity and pore size. This manuscript reviews recent progress on two such structures: (i) CNT Bucky-papers, a non-woven, paper like structure of randomly entangled CNTs, and (ii) isoporous CNT membranes, where the hollow CNT interior acts as a membrane pore. The construction of these two types of membranes will be discussed, characterization and permeance results compared, and some promising applications presented. http://www.mdpi.com/1996-1944/3/1/127/ Mon, 04 Jan 2010 00:00:00 CET Materials 2010-01-04 3 1 Review 127 149 1996-1944 Recent Developments in Carbon Nanotube Membranes for Water Purification and Gas Separation 2010-01-04 doi: 10.3390/ma3010127 Kallista Sears Ludovic Dumée Jürg Schütz Mary She Chi Huynh Stephen Hawkins Mikel Duke Stephen Gray http://www.mdpi.com/1996-1944/3/1/110/ This paper is a brief review of our recent research into novel uses for heteropoly compounds as precursors for thin films that can be used as catalysts and materials with good optical, conductive and other characteristics. In view of this, we have chosen thin film obtained with 12-tungsphosphoric acid on aluminum substrates. In all cases, a relatively new, microarc oxidation technique has been used to prepare oxide coatings on substrate surfaces. Advanced physicochemical methods, AFM and SEM-EDS, XRD, Raman and Micro-Raman, and luminescence spectroscopy, as the most powerful techniques, have been used for the characterization of new materials. Possible applications have been discussed as well. http://www.mdpi.com/1996-1944/3/1/110/ Thu, 31 Dec 2009 00:00:00 CET Materials 2009-12-31 3 1 Review 110 126 1996-1944 Characterization of Bronze Surface Layer Formed by Microarc Oxidation Process in 12-Tungstophosphoric Acid 2009-12-31 doi: 10.3390/ma3010110 Ubavka B. Mioč Stevan Stojadinović Zoran Nedić http://www.mdpi.com/1996-1944/3/1/97/ Co- and Fe-based alloys produced by powder technology are being widely used as a matrix for diamond-containing composites in cutting, drilling, grinding pplications, etc. The severe service conditions demand that the mechanical and tribological properties of these alloys be improved. Development of metal-matrix composites (MMCs) and alloys reinforced with nanoparticles is a promising way to resolve this problem. In this work, we have investigated the effect of nano-sized WC, ZrO2, Al2O3, and Si3N4 additives on the properties of sintered dispersion-strengthened Co- and Fe-based MMCs. The results show an increase in the hardness (up to 10 HRB), bending strength (up to 50%), wear resistance (by a factor of 2–10) and a decrease in the friction coefficient (up to 4-fold) of the dispersion-strengthened materials. The use of designed alloys as a binder of cutting diamond tools gave a 4-fold increment in the service life, without reduction in their cutting speed. http://www.mdpi.com/1996-1944/3/1/97/ Tue, 29 Dec 2009 00:00:00 CET Materials 2009-12-29 3 1 Article 97 109 1996-1944 Improved Mechanical and Tribological Properties of Metal-Matrix Composites Dispersion-Strengthened by Nanoparticles 2009-12-29 doi: 10.3390/ma3010097 Evgenii Levashov Victoria Kurbatkina Zaytsev Alexandr http://www.mdpi.com/1996-1944/3/1/76/ Glass ionomer cements (GICs) are clinically attractive dental materials that have certain unique properties that make them useful as restorative and luting materials. This includes adhesion to moist tooth structures and base metals, anticariogenic properties due to release of fluoride, thermal compatibility with tooth enamel, biocompatibility and low toxicity. The use of GICs in a mechanically loaded situation, however, has been hampered by their low mechanical performance. Poor mechanical properties, such as low fracture strength, toughness and wear, limit their extensive use in dentistry as a filling material in stress-bearing applications. In the posterior dental region, glass ionomer cements are mostly used as a temporary filling material. The requirement to strengthen those cements has lead to an ever increasing research effort into reinforcement or strengthening concepts. http://www.mdpi.com/1996-1944/3/1/76/ Mon, 28 Dec 2009 00:00:00 CET Materials 2009-12-28 3 1 Review 76 96 1996-1944 Dental Glass Ionomer Cements as Permanent Filling Materials? – Properties, Limitations and Future Trends 2009-12-28 doi: 10.3390/ma3010076 Ulrich Lohbauer http://www.mdpi.com/1996-1944/3/1/64/ A28-electron reduced C2h-Mo-blue 34Ǻ outer ring diameter circular ring, [Mo142O429H10(H2O)49(CH3CO2)5(C2H5CO2)]30- (≡{Mo142(CH3CO2)5(C2H5CO2)}) comprising eight carboxylate-coordinated (with disorder) {Mo2} linkers and six defect pockets in two inner rings (four and three for each, respectively), reacts with La3+ in aqueous solutions at pH 3.5 to yield a 28-electron reduced elliptical Ci-Mo-blue ring of formula [Mo134O416H20(H2O)46{La(H2O)5}4{La(H2O)7}4{LaCl2(H2O)5}2]10- (≡{Mo134La10}), isolated as the Na10[Mo134O416H20(H2O)46{La(H2O)5}4{La(H2O)7}4{LaCl2(H2O)5}2]·144 H2O Na+ salt. The elliptical structure of {Mo134La10} showing 36 and 31 Å long and short axes for the outer ring diameters is attributed to four (A-D) modes of LaO9/LaO7Cl2 tricapped-trigonal-prismatic coordination (TTP) geometries. Two different LaO2(H2O)7 and one LaO2(H2O)2Cl2 TTP geometries (as A-C modes) for each of two inner rings result from the coordination of all three defect pockets of the inner ring for {Mo142(CH3CO2)5(C2H5CO2)}, and two LaO4(H2O)5 TTP geometries (as D mode) result from the displacement of two (acetate/propionate-coordinated) binuclear {Mo2} linkers with La3+ in each inner ring. The isothermal titration calorimetry (ITC) of the ring modification from circle to ellipsoid, showing the endothermic reaction of [La3+]/[{Mo142(CH3CO2)5(C2H5CO2)}] = 6/1 with DH = 22 kJ×mol-1, DS = 172 J×K-1×mol-1, DG = −28 kJ×mol-1, and K = 9.9 ´ 104 M-1 at 293 K, leads to the conclusion that the coordination of the defect pockets to La3+ precedes the replacement of the {Mo2} linkers with La3+. 139La- NMR spectrometry of the coordination of {Mo142(CH3CO2)5(C2H5CO2)} ring to La3+ is also discussed. http://www.mdpi.com/1996-1944/3/1/64/ Mon, 28 Dec 2009 00:00:00 CET Materials 2009-12-28 3 1 Article 64 75 1996-1944 Coordination of {Mo142} Ring to La3+ Provides Elliptical {Mo134La10} Ring with a Variety of Coordination Modes 2009-12-28 doi: 10.3390/ma3010064 Eri Ishikawa Yutaka Yano Toshihiro Yamase