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Materials, Volume 2, Issue 2 (June 2009), Pages 307-709

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Research

Jump to: Review

Open AccessCommunication Synthesis, X-ray Diffraction Study and Antimicrobial Activity of Calcium Sulphate Nanocomposites from Plant Charcoal
Materials 2009, 2(2), 345-352; doi:10.3390/ma2020345
Received: 4 March 2009 / Revised: 21 March 2009 / Accepted: 26 March 2009 / Published: 9 April 2009
Cited by 6 | PDF Full-text (451 KB)
Abstract
Calcium sulphate nanocomposite materials (CB) have been synthesised from plant charcoal. Crushed charcoal powder was heated to red hot over a Bunsen burner flame and produced a white material which has been isolated. The surface morphology of the material has been studied [...] Read more.
Calcium sulphate nanocomposite materials (CB) have been synthesised from plant charcoal. Crushed charcoal powder was heated to red hot over a Bunsen burner flame and produced a white material which has been isolated. The surface morphology of the material has been studied by Scanning Electron Microscopy (SEM) and the elements were analyzed by Energy Dispersion Spectroscopy (EDS). To explore the structural features of the materials X-Ray Diffraction (XRD) patterns were recorded. The material showed pronounced inhibitory effects against Streptococcus faecaelis, Bacillus subtilis, Klebsilla pneumoni, E. coli, Proteus vulgaris and Pseudomonas aeruginosa. Full article
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Open AccessArticle The Mechanical and Biological Properties of Chitosan Scaffolds for Tissue Regeneration Templates Are Significantly Enhanced by Chitosan from Gongronella butleri
Materials 2009, 2(2), 374-398; doi:10.3390/ma2020374
Received: 5 March 2009 / Revised: 5 April 2009 / Accepted: 14 April 2009 / Published: 20 April 2009
Cited by 43 | PDF Full-text (1121 KB) | HTML Full-text | XML Full-text
Abstract
Chitosan with a molecular weight (MW) of 104 Da and 13% degree of acetylation (DA) was extracted from the mycelia of the fungus Gongronella butleri USDB 0201 grown in solid substrate fermentation and used to prepare scaffolds by the freeze-drying method. [...] Read more.
Chitosan with a molecular weight (MW) of 104 Da and 13% degree of acetylation (DA) was extracted from the mycelia of the fungus Gongronella butleri USDB 0201 grown in solid substrate fermentation and used to prepare scaffolds by the freeze-drying method. The mechanical and biological properties of the fungal chitosan scaffolds were evaluated and compared with those of scaffolds prepared using chitosans obtained from shrimp and crab shells and squid bone plates (MW 105-106 Da and DA 10-20%). Under scanning electron microscopy, it was observed that all scaffolds had average pore sizes of approximately 60-90 mm in diameter. Elongated pores were observed in shrimp chitosan scaffolds and polygonal pores were found in crab, squid and fungal chitosan scaffolds. The physico-chemical properties of the chitosans had an effect on the formation of pores in the scaffolds, that consequently influenced the mechanical and biological properties of the scaffolds. Fungal chitosan scaffolds showed excellent mechanical, water absorption and lysozyme degradation properties, whereas shrimp chitosan scaffolds (MW 106Da and DA 12%) exhibited the lowest water absorption properties and lysozyme degradation rate. In the evaluation of biocompatibility of chitosan scaffolds, the ability of fibroblast NIH/3T3 cells to attach on all chitosan scaffolds was similar, but the proliferation of cells with polygonal morphology was faster on crab, squid and fungal chitosan scaffolds than on shrimp chitosan scaffolds. Therefore fungal chitosan scaffold, which has excellent mechanical and biological properties, is the most suitable scaffold to use as a template for tissue regeneration. Full article
(This article belongs to the Special Issue Biocompatibility of Materials)
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Open AccessArticle Focal Conic Stacking in Smectic A Liquid Crystals: Smectic Flower and Apollonius Tiling
Materials 2009, 2(2), 499-513; doi:10.3390/ma2020499
Received: 3 February 2009 / Revised: 16 April 2009 / Accepted: 20 April 2009 / Published: 22 April 2009
Cited by 14 | PDF Full-text (3558 KB) | HTML Full-text | XML Full-text
Abstract
We investigate two different textures of smectic A liquid crystals. These textures are particularly symmetric when they are observed at crossed polars optical microscopy. For both textures, a model has been made in order to examine the link between the defective macroscopic [...] Read more.
We investigate two different textures of smectic A liquid crystals. These textures are particularly symmetric when they are observed at crossed polars optical microscopy. For both textures, a model has been made in order to examine the link between the defective macroscopic texture and the microscopic disposition of the layers. We present in particular in the case of some hexagonal tiling of circles (similar to the Apollonius tiling) some numeric simulation in order to visualize the smectic layers. We discuss of the nature of the smectic layers, which permit to assure their continuity from one focal conic domain to another adjacent one. Full article
(This article belongs to the Special Issue Liquid Crystals)
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Open AccessArticle Characterization and Accelerated Ageing of UHMWPE Used in Orthopedic Prosthesis by Peroxide
Materials 2009, 2(2), 562-576; doi:10.3390/ma2020562
Received: 8 April 2009 / Revised: 29 April 2009 / Accepted: 8 May 2009 / Published: 13 May 2009
Cited by 8 | PDF Full-text (278 KB) | HTML Full-text | XML Full-text
Abstract
Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important mechanical properties to extend the longevity of knee prostheses. Though accelerated in vitro [...] Read more.
Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important mechanical properties to extend the longevity of knee prostheses. Though accelerated in vitro protocols have been developed to test the relative oxidation resistance of various types of UHMWPE, its mechanism is not accurately understood yet. Thus, in the present study an accelerated ageing of UHMWPE in hydrogen peroxide solution was performed and relative oxidation was extensively characterized by Fourier Transformed Infrared Spectroscopy (FTIR) spectroscopy and the morphological changes were analyzed by Scanning Electron Microscopy (SEM). Different chemical groups of UHMWPE associated with the degradation reaction were monitored for over 120 days in order to evaluate the possible oxidation mechanism(s) which may have occurred. The results have provided strong evidence that the oxidation mechanism is rather complex, and two stages with their own particular first-order kinetics reaction patterns have been clearly identified. Furthermore, hydrogen peroxide has proven to be an efficient oxidative medium to accelerate ageing of UHMWPE. Full article
(This article belongs to the Special Issue Biocompatibility of Materials)
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Open AccessArticle Role of Lifshitz Invariants in Liquid Crystals
Materials 2009, 2(2), 674-698; doi:10.3390/ma2020674
Received: 5 May 2009 / Revised: 12 June 2009 / Accepted: 16 June 2009 / Published: 16 June 2009
PDF Full-text (351 KB) | HTML Full-text | XML Full-text
Abstract
The interaction between an external action and the order parameter, via a dependence described by a so-called Lifshitz invariant, is very important to determine the final configuration of liquid crystal cells. The external action can be an electric field applied to the [...] Read more.
The interaction between an external action and the order parameter, via a dependence described by a so-called Lifshitz invariant, is very important to determine the final configuration of liquid crystal cells. The external action can be an electric field applied to the bulk or the confinement due to free surfaces or cell walls. The Lifshitz invariant includes the order parameter in the form of an elastic strain. This coupling between elastic strains and fields, inserted in a Landau-Ginzburg formalism, is well known and gives rise to striction effects causing undulations in the director configuration. We want to discuss here the role of Lifshitz coupling terms, following an approach similar to that introduced by Dzyaloshinskii for magnetic materials. Case studies on nematics in planar and cylindrical cells are also proposed. Full article
(This article belongs to the Special Issue Liquid Crystals)
Open AccessArticle Optimization of the Adhesion Strength of Arc Ion Plating TiAlN Films by the Taguchi Method
Materials 2009, 2(2), 699-709; doi:10.3390/ma2020699
Received: 7 June 2009 / Accepted: 17 June 2009 / Published: 17 June 2009
Cited by 5 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
A three-level six-factor (arc power, substrate temperature, pre-treatment bias voltage, working pressure, deposition bias voltage and pretreatment time) orthogonal experimental array (L18) to optimize the adhesion strength of arc ion plating (AIP) TiAlN films was designed using the Taguchi method. An optimized [...] Read more.
A three-level six-factor (arc power, substrate temperature, pre-treatment bias voltage, working pressure, deposition bias voltage and pretreatment time) orthogonal experimental array (L18) to optimize the adhesion strength of arc ion plating (AIP) TiAlN films was designed using the Taguchi method. An optimized film process, namely substrate temperature 220 °C, arc power 60 A, negative bias voltage -800 V, nitrogen pressure 10-2 Torr, pretreated voltage -450 V and pretreated time 15 minutes was obtained by the Taguchi program for the purpose of obtaining a larger critical load. The critical load of the optimized TiAlN film (53 N) was increased by 43% compared to the film with the highest critical load before optimization. The improvement in the adhesion strength of the films was attributed to the enhancement of hardness and the competitive growth of the (111), (200) and (220) orientations in the film. Full article

Review

Jump to: Research

Open AccessReview Biodegradable Polymers
Materials 2009, 2(2), 307-344; doi:10.3390/ma2020307
Received: 25 February 2009 / Revised: 25 March 2009 / Accepted: 30 March 2009 / Published: 1 April 2009
Cited by 178 | PDF Full-text (222 KB) | HTML Full-text | XML Full-text
Abstract
Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks [...] Read more.
Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. The following review presents an overview of the different biodegradable polymers that are currently being used and their properties, as well as new developments in their synthesis and applications. Full article
(This article belongs to the Special Issue Biodegradability of Materials)
Open AccessReview Biodegradable Cellulose-based Hydrogels: Design and Applications
Materials 2009, 2(2), 353-373; doi:10.3390/ma2020353
Received: 28 February 2009 / Revised: 3 April 2009 / Accepted: 9 April 2009 / Published: 16 April 2009
Cited by 127 | PDF Full-text (366 KB) | HTML Full-text | XML Full-text
Abstract
Hydrogels are macromolecular networks able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli. Such stimuli-sensitive behaviour makes hydrogels appealing for the design of ‘smart’ devices, applicable in a variety of technological fields. In particular, [...] Read more.
Hydrogels are macromolecular networks able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli. Such stimuli-sensitive behaviour makes hydrogels appealing for the design of ‘smart’ devices, applicable in a variety of technological fields. In particular, in cases where either ecological or biocompatibility issues are concerned, the biodegradability of the hydrogel network, together with the control of the degradation rate, may provide additional value to the developed device. This review surveys the design and the applications of cellulose-based hydrogels, which are extensively investigated due to the large availability of cellulose in nature, the intrinsic degradability of cellulose and the smart behaviour displayed by some cellulose derivatives. Full article
(This article belongs to the Special Issue Biodegradability of Materials)
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Open AccessReview Calcium Orthophosphates in Nature, Biology and Medicine
Materials 2009, 2(2), 399-498; doi:10.3390/ma2020399
Received: 24 February 2009 / Revised: 9 April 2009 / Accepted: 20 April 2009 / Published: 20 April 2009
Cited by 254 | PDF Full-text (1270 KB) | HTML Full-text | XML Full-text
Abstract
The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological (i.e. [...] Read more.
The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological (i.e. those appearing due to various diseases) calcified tissues of mammals. Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium orthophosphates. For example, self-setting hydraulic cements made of calcium orthophosphates are helpful in bone repair, while titanium substitutes covered by a surface layer of calcium orthophosphates are used for hip joint endoprostheses and as tooth substitutes. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. In addition, technical grade calcium orthophosphates are very popular mineral fertilizers. Thus ere calcium orthophosphates are of great significance for humankind and, in this paper, an overview on the current knowledge on this subject is provided. Full article
Open AccessReview Biocompatibility of Resin-based Dental Materials
Materials 2009, 2(2), 514-548; doi:10.3390/ma2020514
Received: 24 February 2009 / Revised: 24 April 2009 / Accepted: 27 April 2009 / Published: 28 April 2009
Cited by 12 | PDF Full-text (442 KB) | HTML Full-text | XML Full-text
Abstract
Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined thebiocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have [...] Read more.
Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined thebiocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have been developed. This article reviews the biological aspects of resin-based dental materials and discusses the conventional as well as the new techniques used for biocompatibility assessment of dental materials. Full article
(This article belongs to the Special Issue Biocompatibility of Materials)
Open AccessReview Impact of Liquid Crystals in Active and Adaptive Optics
Materials 2009, 2(2), 549-561; doi:10.3390/ma2020549
Received: 3 February 2009 / Revised: 24 April 2009 / Accepted: 11 May 2009 / Published: 12 May 2009
Cited by 8 | PDF Full-text (257 KB) | HTML Full-text | XML Full-text
Abstract
Active and dynamic modulation of light has been one of major contributions of liquid crystals to Optics. The spectrum of application range from signposting panels to high resolution imaging. The development of new materials is the key to continued progress in this [...] Read more.
Active and dynamic modulation of light has been one of major contributions of liquid crystals to Optics. The spectrum of application range from signposting panels to high resolution imaging. The development of new materials is the key to continued progress in this field. To promote this we will present in this paper recent uses of liquid crystals as active or adaptive modulators of light. Besides, we will reflect on their current limitations. We expect with this to contribute to the progress in the field of liquid crystals and thus the development of new useful tools for Active and Adaptive Optics. Full article
(This article belongs to the Special Issue Liquid Crystals)
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Open AccessReview Micro- and Nanoscale Hydrogel Systems for Drug Delivery and Tissue Engineering
Materials 2009, 2(2), 577-612; doi:10.3390/ma2020577
Received: 1 March 2009 / Revised: 11 April 2009 / Accepted: 6 May 2009 / Published: 13 May 2009
Cited by 28 | PDF Full-text (1076 KB) | HTML Full-text | XML Full-text
Abstract
The pursuit for targeted drug delivery systems has led to the development of highly improved biomaterials with enhanced biocompatibility and biodegradability properties. Micro- and nanoscale components of hydrogels prepared from both natural and artificial components have been gaining significant importance due to [...] Read more.
The pursuit for targeted drug delivery systems has led to the development of highly improved biomaterials with enhanced biocompatibility and biodegradability properties. Micro- and nanoscale components of hydrogels prepared from both natural and artificial components have been gaining significant importance due to their potential uses in cell based therapies, tissue engineering, liquid micro-lenses, cancer therapy, and drug delivery. In this review some of the recent methodologies used in the preparation of a number of synthetic hydrogels such as poly(N-isopropylacrylamide) (pNIPAm), poly(ethylene glycol) (PEG), poly(ethylene oxide) (PEO), polyvinyl alcohol methylacrylate co-polymers (PVA-MA) and polylactic acid (PLA), as well as some of the natural hydrogels and their applications have been discussed in detail. Full article
(This article belongs to the Special Issue Biocompatibility of Materials)
Open AccessReview Applications and Degradation of Proteins Used as Tissue Engineering Materials
Materials 2009, 2(2), 613-635; doi:10.3390/ma2020613
Received: 7 February 2009 / Revised: 21 April 2009 / Accepted: 22 May 2009 / Published: 26 May 2009
Cited by 7 | PDF Full-text (158 KB) | HTML Full-text | XML Full-text
Abstract
This article provides an up-to-date review on the applications of natural polymers, i.e., proteins, as materials for tissue engineering. Proteins are one of the important candidates for tissue engineering materials based on their superior biocompatibility, biodegradation, bioresorbability, and so on. However, their [...] Read more.
This article provides an up-to-date review on the applications of natural polymers, i.e., proteins, as materials for tissue engineering. Proteins are one of the important candidates for tissue engineering materials based on their superior biocompatibility, biodegradation, bioresorbability, and so on. However, their inferior mechanical properties limit their broad application. Currently-available proteins for application in tissue engineering or drug delivery systems, such as fibrin, collagen, zein, silk fibroin, keratin, casein and albumin, and the biodegradation of tissue-engineered substitutes based on proteins are presented. Techniques of scaffold fabrication are also mentioned. Problems and future possibilities for development of protein-based tissue-engineered substitutes are also introduced in this review. Full article
(This article belongs to the Special Issue Biocompatibility of Materials)
Open AccessReview Polymers Comprising Cholesterol: Synthesis, Self-Assembly, and Applications
Materials 2009, 2(2), 636-660; doi:10.3390/ma2020636
Received: 5 May 2009 / Revised: 21 May 2009 / Accepted: 25 May 2009 / Published: 2 June 2009
Cited by 35 | PDF Full-text (937 KB) | HTML Full-text | XML Full-text
Abstract
This article reviews the current status of self-assembling liquid crystalline polymers comprising cholesterol. This article will focus on synthesis, structure-property relationships and strategies to direct ordering and packing of meso- and nanostructures of cholesterol polymers in the neat- or melt state and [...] Read more.
This article reviews the current status of self-assembling liquid crystalline polymers comprising cholesterol. This article will focus on synthesis, structure-property relationships and strategies to direct ordering and packing of meso- and nanostructures of cholesterol polymers in the neat- or melt state and in solution. The applications of these self-assembled structures will be presented. Full article
(This article belongs to the Special Issue Liquid Crystals)
Open AccessReview Characteristics of Color Produced by Awa Natural Indigo and Synthetic Indigo
Materials 2009, 2(2), 661-673; doi:10.3390/ma2020661
Received: 12 May 2009 / Revised: 28 May 2009 / Accepted: 9 June 2009 / Published: 9 June 2009
Cited by 2 | PDF Full-text (704 KB) | HTML Full-text | XML Full-text
Abstract
Color of cloth dyed with Awa natural indigo is quantitatively compared with color of the cloth dyed with synthetic indigo. Results showed that: 1) color produced by Awa natural indigo is bluer and brighter than color produced by synthetic indigo; 2) a [...] Read more.
Color of cloth dyed with Awa natural indigo is quantitatively compared with color of the cloth dyed with synthetic indigo. Results showed that: 1) color produced by Awa natural indigo is bluer and brighter than color produced by synthetic indigo; 2) a single Gaussian function fits the profile of the running of color produced by Awa natural indigo and the running of color produced by synthetic indigo prepared with sodium hydrosulfite approximates a linear sum of two Gaussian functions; 3) before and after washing, color is quantitatively more uneven when produced by Awa natural indigo than when produced by synthetic indigo; 4) the diffusion coefficient of Awa natural indigo is lower than that of synthetic indigo; 5) color superiority of Awa natural indigorelates to smaller diffusion coefficient, slower reduction, poorer penetration, and higher dye aggregation. Full article
(This article belongs to the Special Issue Functional Colorants)

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