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Materials, Volume 5, Issue 9 (September 2012), Pages 1528-1739

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Research

Jump to: Review

Open AccessArticle Early Combination of Material Characteristics and Toxicology Is Useful in the Design of Low Toxicity Carbon Nanofiber
Materials 2012, 5(9), 1560-1580; doi:10.3390/ma5091560
Received: 20 June 2012 / Revised: 20 August 2012 / Accepted: 27 August 2012 / Published: 3 September 2012
Cited by 3 | PDF Full-text (1638 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF) with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a
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This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF) with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry) as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product. Full article
(This article belongs to the Special Issue Nanotoxicology)
Open AccessArticle Deposition of Metal-Organic Frameworks by Liquid-Phase Epitaxy: The Influence of Substrate Functional Group Density on Film Orientation
Materials 2012, 5(9), 1581-1592; doi:10.3390/ma5091581
Received: 11 July 2012 / Revised: 27 August 2012 / Accepted: 28 August 2012 / Published: 5 September 2012
Cited by 20 | PDF Full-text (302 KB) | HTML Full-text | XML Full-text
Abstract
The liquid phase epitaxy (LPE) of the metal-organic framework (MOF) HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs) on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA), 4’-carboxyterphenyl-4-methanethiol (TPMTA) and
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The liquid phase epitaxy (LPE) of the metal-organic framework (MOF) HKUST-1 has been studied for three different COOH-terminated templating organic surfaces prepared by the adsorption of self-assembled monolayers (SAMs) on gold substrates. Three different SAMs were used, mercaptohexadecanoic acid (MHDA), 4’-carboxyterphenyl-4-methanethiol (TPMTA) and 9-carboxy-10-(mercaptomethyl)triptycene (CMMT). The XRD data demonstrate that highly oriented HKUST-1 SURMOFs with an orientation along the (100) direction was obtained on MHDA-SAMs. In the case of the TPMTA-SAM, the quality of the deposited SURMOF films was found to be substantially inferior. Surprisingly, for the CMMT-SAMs, a different growth direction was obtained; XRD data reveal the deposition of highly oriented HKUST-1 SURMOFs grown along the (111) direction. Full article
(This article belongs to the Special Issue Epitaxial Materials)
Open AccessArticle Permeation of Light Gases through Hexagonal Ice
Materials 2012, 5(9), 1593-1601; doi:10.3390/ma5091593
Received: 16 July 2012 / Revised: 21 August 2012 / Accepted: 27 August 2012 / Published: 5 September 2012
PDF Full-text (252 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Gas separation using porous solids have attracted great attention due to their energetic applications. There is an enormous economic and environmental interest in the development of improved technologies for relevant processes, such as H2 production, CO2 separation or O2 and
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Gas separation using porous solids have attracted great attention due to their energetic applications. There is an enormous economic and environmental interest in the development of improved technologies for relevant processes, such as H2 production, CO2 separation or O2 and N2 purification from air. New materials are needed for achieving major improvements. Crystalline materials, displaying unidirectional and single-sized pores, preferentially with low pore tortuosity and high pore density, are promising candidates for membrane synthesis. Herein, we study hexagonal ice crystals as an example of this class of materials. By slowly growing ice crystals inside capillary tubes we were able to measure the permeation of several gas species through ice crystals and investigate its relation with both the size of the guest molecules and temperature of the crystal. Full article
Open AccessArticle Synthesis, Crystal Structure and Luminescent Property of Cd (II) Complex with N-Benzenesulphonyl-L-leucine
Materials 2012, 5(9), 1626-1634; doi:10.3390/ma5091626
Received: 13 July 2012 / Revised: 3 August 2012 / Accepted: 7 September 2012 / Published: 14 September 2012
Cited by 8 | PDF Full-text (385 KB) | HTML Full-text | XML Full-text
Abstract
A new trinuclear Cd (II) complex [Cd3(L)6(2,2-bipyridine)3] [L = N-phenylsulfonyl-L-leucinato] has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the complex belongs to the
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A new trinuclear Cd (II) complex [Cd3(L)6(2,2-bipyridine)3] [L = N-phenylsulfonyl-L-leucinato] has been synthesized and characterized by elemental analysis, IR and X-ray single crystal diffraction analysis. The results show that the complex belongs to the orthorhombic, space group P212121 with a = 16.877(3) Å, b = 22.875(5) Å, c = 29.495(6) Å, α = β = γ = 90°, V = 11387(4) Å3, Z = 4, Dc= 1.416 μg·m−3, μ = 0.737 mm−1, F (000) = 4992, and final R1 = 0.0390, ωR2 = 0.0989. The complex comprises two seven-coordinated Cd (II) atoms, with a N2O5 distorted pengonal bipyramidal coordination environment and a six-coordinated Cd (II) atom, with a N2O4 distorted octahedral coordination environment. The molecules form one dimensional chain structure by the interaction of bridged carboxylato groups, hydrogen bonds and p-p interaction of 2,2-bipyridine. The luminescent properties of the Cd (II) complex and N-Benzenesulphonyl-L-leucine in solid and in CH3OH solution also have been investigated. Full article
Open AccessArticle Pozzolanic Activity Assessment of LUSI (LUmpur SIdoarjo) Mud in Semi High Volume Pozzolanic Mortar
Materials 2012, 5(9), 1654-1660; doi:10.3390/ma5091654
Received: 5 July 2012 / Revised: 10 August 2012 / Accepted: 7 September 2012 / Published: 17 September 2012
Cited by 11 | PDF Full-text (183 KB) | HTML Full-text | XML Full-text
Abstract
LUSI mud obtained from the mud volcano in Sidoarjo, Indonesia, is a viable aluminosilicate material to be utilized as pozzolanic material. LUSI is an abbreviation of the local name of the mud, i.e., Lumpur Sidoarjo, meaning Sidoarjo mud. This paper reports the
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LUSI mud obtained from the mud volcano in Sidoarjo, Indonesia, is a viable aluminosilicate material to be utilized as pozzolanic material. LUSI is an abbreviation of the local name of the mud, i.e., Lumpur Sidoarjo, meaning Sidoarjo mud. This paper reports the results of an investigation to assess the pozzolanic activity of LUSI mud, especially in semi high volume pozzolanic mortar. In this case, the amount of mud incorporated is between 30% to 40% of total cementitious material, by mass. The content of SiO2 in the mud is about 30%, whilst the total content of SiO2, Fe2O3 and Al2O3 is more than 70%. Particle size and degree of partial cement replacement by treated LUSI mud affect the compressive strength, the strength activity index (SAI), the rate of pozzolanic activity development, and the workability of mortar incorporating LUSI mud. Manufacturing semi high volume LUSI mud mortar, up to at least 40% cement replacement, is a possibility, especially with a smaller particle size of LUSI mud, less than 63 μm. The use of a larger percentage of cement replacement by LUSI mud does not show any adverse effect on the water demand, as the flow of the fresh mortar increased with the increase of percentage of LUSI mud usage. Full article
Open AccessArticle Morphological Effect of Pd Catalyst on Ethanol Electro-Oxidation Reaction
Materials 2012, 5(9), 1686-1697; doi:10.3390/ma5091686
Received: 27 June 2012 / Revised: 31 July 2012 / Accepted: 13 August 2012 / Published: 19 September 2012
Cited by 23 | PDF Full-text (933 KB) | HTML Full-text | XML Full-text
Abstract
In the present study, three different structures with preferentially exposed crystal faces were supported on commercial carbon black by the polyol method (nanoparticles (NP/C), nanobars (NB/C) and nanorods (NR/C)). The electrocatalysts were characterized by XRD, TEM, TGA and cyclic voltammetry at three different
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In the present study, three different structures with preferentially exposed crystal faces were supported on commercial carbon black by the polyol method (nanoparticles (NP/C), nanobars (NB/C) and nanorods (NR/C)). The electrocatalysts were characterized by XRD, TEM, TGA and cyclic voltammetry at three different ethanol concentrations. Considerable differences were found in terms of catalytic electroactivity. At all ethanol concentrations, the trend observed for the ethanol oxidation peak potential was preserved as follows: NB/C < NP/C< NR/C < commercial Pd/C. This result indicates that, from a thermodynamics point of view, the NB/C catalyst enclosed by Pd(100) facets presented the highest activity with respect to ethanol electro-oxidation among all of the catalysts studied. Full article
(This article belongs to the Special Issue Metal Nanoparticles 2012)
Open AccessArticle Behavior of Plain Concrete of a High Water-Cement Ratio after Freeze-Thaw Cycles
Materials 2012, 5(9), 1698-1707; doi:10.3390/ma5091698
Received: 20 April 2012 / Revised: 13 September 2012 / Accepted: 13 September 2012 / Published: 24 September 2012
Cited by 7 | PDF Full-text (367 KB) | HTML Full-text | XML Full-text
Abstract
An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME), weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain
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An experimental study of plain concrete specimens of water-cement ratio 0.55, subjected to 0, 15, 25, 40, 50 and 75 cycles of freeze-thaw was completed. The dynamic modulus of elasticity (DME), weight loss, compressive strength, tensile strength, flexural strength, cleavage strength and stress-strain relationships of plain concrete specimens suffering from freeze-thaw cycles were measured. The experimental results showed that the strength decreased as the freeze-thaw cycles were repeated. A concise mathematic formula between DME, weight loss, mechanical properties and number of freeze-thaw cycles was also established. The influences of freeze-thaw cycles on the DME, weight loss and mechanical properties were analyzed. The experimental results serve as a reference for the maintenance, design and life prediction of dams, hydraulic structures, offshore structures, concrete roads and bridges in cold regions. Full article
Open AccessArticle Comparison of Copper Scavenging Capacity between Two Different Red Mud Types
Materials 2012, 5(9), 1708-1721; doi:10.3390/ma5091708
Received: 27 July 2012 / Revised: 28 August 2012 / Accepted: 3 September 2012 / Published: 24 September 2012
PDF Full-text (1307 KB) | HTML Full-text | XML Full-text
Abstract
A batch experiment was conducted to compare the Cu scavenging capacity between two different red mud types: the first one was a highly basic red mud derived from a combined sintering and Bayer process, and the second one was a seawater-neutralized red mud
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A batch experiment was conducted to compare the Cu scavenging capacity between two different red mud types: the first one was a highly basic red mud derived from a combined sintering and Bayer process, and the second one was a seawater-neutralized red mud derived from the Bayer process. The first red mud contained substantial amounts of CaCO3, which, in combination with the high OH activity, favored the immobilization of water-borne Cu through massive formation of atacamite. In comparison, the seawater-neutralized red mud had a lower pH and was dominated by boehmite, which was likely to play a significant role in Cu adsorption. Overall, it appears that Cu was more tightly retained by the CaCO3-dominated red mud than the boehmite-dominated red mud. It is concluded that the heterogeneity of red mud has marked influences on its capacity to immobilize water-borne Cu and maintain the long-term stability of the immobilized Cu species. The research findings obtained from this study have implications for the development of Cu immobilization technology by using appropriate waste materials generated from the aluminium industry. Full article
Open AccessArticle Hyperpolarized Xenon Nuclear Magnetic Resonance (NMR) of Building Stone Materials
Materials 2012, 5(9), 1722-1739; doi:10.3390/ma5091722
Received: 12 July 2012 / Revised: 27 August 2012 / Accepted: 14 September 2012 / Published: 24 September 2012
Cited by 4 | PDF Full-text (1039 KB) | HTML Full-text | XML Full-text
Abstract
We have investigated several building stone materials, including minerals and rocks, using continuous flow hyperpolarized xenon (CF-HP) NMR spectroscopy to probe the surface composition and porosity. Chemical shift and line width values are consistent with petrographic information. Rare upfield shifts were measured and
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We have investigated several building stone materials, including minerals and rocks, using continuous flow hyperpolarized xenon (CF-HP) NMR spectroscopy to probe the surface composition and porosity. Chemical shift and line width values are consistent with petrographic information. Rare upfield shifts were measured and attributed to the presence of transition metal cations on the surface. The evolution of freshly cleaved rocks exposed to the atmosphere was also characterized. The CF-HP 129Xe NMR technique is non-destructive and it could complement currently used techniques, like porosimetry and microscopy, providing additional information on the chemical nature of the rock surface and its evolution. Full article
(This article belongs to the Special Issue NMR in Materials Science)

Review

Jump to: Research

Open AccessReview Titanium as a Reconstruction and Implant Material in Dentistry: Advantages and Pitfalls
Materials 2012, 5(9), 1528-1545; doi:10.3390/ma5091528
Received: 14 June 2012 / Revised: 10 August 2012 / Accepted: 11 August 2012 / Published: 24 August 2012
Cited by 23 | PDF Full-text (136 KB) | HTML Full-text | XML Full-text
Abstract
Commercial pure titanium (cpTi) has been the material of choice in several disciplines of dentistry due to its biocompatibility, resistance to corrosion and mechanical properties. Despite a number of favorable characteristics, cpTi as a reconstruction and oral implant material has several shortcomings. This
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Commercial pure titanium (cpTi) has been the material of choice in several disciplines of dentistry due to its biocompatibility, resistance to corrosion and mechanical properties. Despite a number of favorable characteristics, cpTi as a reconstruction and oral implant material has several shortcomings. This paper highlights current knowledge on material properties, passive oxidation film formation, corrosion, surface activation, cell interactions, biofilm development, allergy, casting and machining properties of cpTi for better understanding and potential improvement of this material for its clinical applications. Full article
(This article belongs to the Special Issue Titanium Materials for Biomedical Application)
Open AccessReview Adaptive Holography in Liquid Crystal Light-Valves
Materials 2012, 5(9), 1546-1559; doi:10.3390/ma5091546
Received: 18 July 2012 / Revised: 13 August 2012 / Accepted: 20 August 2012 / Published: 27 August 2012
Cited by 15 | PDF Full-text (1296 KB) | HTML Full-text | XML Full-text
Abstract
By performing two-wave mixing experiments in a liquid crystal light-valve, optical beam amplification is obtained as a strongly resonant process to which a narrow frequency bandwidth is associated. This property is exploited to realize adaptive holographic interferometric systems able to efficiently detect displacements
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By performing two-wave mixing experiments in a liquid crystal light-valve, optical beam amplification is obtained as a strongly resonant process to which a narrow frequency bandwidth is associated. This property is exploited to realize adaptive holographic interferometric systems able to efficiently detect displacements as small as fraction of picometers. Pressure radiation induced deformations of a reflecting membrane are measured with the same type of system. Then, when used with complex wavefronts, like speckle fields, the LCLV-based interferometer allows to detect extremely small phase modulations. The examples shown demonstrate the potentialities of the light-valve for dynamic holography applications. Full article
(This article belongs to the Special Issue Advanced Materials for Modern Holographic Applications)
Open AccessReview Time Dependent Dielectric Breakdown in Copper Low-k Interconnects: Mechanisms and Reliability Models
Materials 2012, 5(9), 1602-1625; doi:10.3390/ma5091602
Received: 25 June 2012 / Revised: 30 August 2012 / Accepted: 4 September 2012 / Published: 12 September 2012
Cited by 16 | PDF Full-text (301 KB) | HTML Full-text | XML Full-text
Abstract
The time dependent dielectric breakdown phenomenon in copper low-k damascene interconnects for ultra large-scale integration is reviewed. The loss of insulation between neighboring interconnects represents an emerging back end-of-the-line reliability issue that is not fully understood. After describing the main dielectric leakage mechanisms
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The time dependent dielectric breakdown phenomenon in copper low-k damascene interconnects for ultra large-scale integration is reviewed. The loss of insulation between neighboring interconnects represents an emerging back end-of-the-line reliability issue that is not fully understood. After describing the main dielectric leakage mechanisms in low-k materials (Poole-Frenkel and Schottky emission), the major dielectric reliability models that had appeared in the literature are discussed, namely: the Lloyd model, 1/E model, thermochemical E model, E1/2 models, E2 model and the Haase model. These models can be broadly categorized into those that consider only intrinsic breakdown (Lloyd, 1/E, E and Haase) and those that take into account copper migration in low-k materials (E1/2, E2). For each model, the physical assumptions and the proposed breakdown mechanism will be discussed, together with the quantitative relationship predicting the time to breakdown and supporting experimental data. Experimental attempts on validation of dielectric reliability models using data obtained from low field stressing are briefly discussed. The phenomenon of soft breakdown, which often precedes hard breakdown in porous ultra low-k materials, is highlighted for future research. Full article
(This article belongs to the Special Issue Low k Dielectic Materials)
Figures

Open AccessReview Review of Random Phase Encoding in Volume Holographic Storage
Materials 2012, 5(9), 1635-1653; doi:10.3390/ma5091635
Received: 9 July 2012 / Revised: 5 September 2012 / Accepted: 5 September 2012 / Published: 17 September 2012
Cited by 1 | PDF Full-text (520 KB) | HTML Full-text | XML Full-text
Abstract
Random phase encoding is a unique technique for volume hologram which can be applied to various applications such as holographic multiplexing storage, image encryption, and optical sensing. In this review article, we first review and discuss diffraction selectivity of random phase encoding in
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Random phase encoding is a unique technique for volume hologram which can be applied to various applications such as holographic multiplexing storage, image encryption, and optical sensing. In this review article, we first review and discuss diffraction selectivity of random phase encoding in volume holograms, which is the most important parameter related to multiplexing capacity of volume holographic storage. We then review an image encryption system based on random phase encoding. The alignment of phase key for decryption of the encoded image stored in holographic memory is analyzed and discussed. In the latter part of the review, an all-optical sensing system implemented by random phase encoding and holographic interconnection is presented. Full article
(This article belongs to the Special Issue Advances in Materials Science)
Open AccessReview Natural Melanogenesis Inhibitors Acting Through the Down-Regulation of Tyrosinase Activity
Materials 2012, 5(9), 1661-1685; doi:10.3390/ma5091661
Received: 8 August 2012 / Revised: 30 August 2012 / Accepted: 5 September 2012 / Published: 17 September 2012
Cited by 28 | PDF Full-text (932 KB) | HTML Full-text | XML Full-text
Abstract
Melanogenesis is a biosynthetic pathway for the formation of the pigment melanin in human skin. A key enzyme, tyrosinase, catalyzes the first and only rate-limiting steps in melanogenesis, and the down-regulation of enzyme activity is the most reported method for the inhibition of
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Melanogenesis is a biosynthetic pathway for the formation of the pigment melanin in human skin. A key enzyme, tyrosinase, catalyzes the first and only rate-limiting steps in melanogenesis, and the down-regulation of enzyme activity is the most reported method for the inhibition of melanogenesis. Because of the cosmetically important issue of hyperpigmentation, there is a big demand for melanogenesis inhibitors. This encourages researchers to seek potent melanogenesis inhibitors for cosmetic uses. This article reviews melanogenesis inhibitors that have been recently discovered from natural sources. The reaction mechanisms of the inhibitors on tyrosinase activity are also discussed. Full article
(This article belongs to the Special Issue Advances in Cosmetics)

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