Materials

2056 KiB

Open AccessArticle

Analysis of Effective Interconnectivity of DegraPol-foams Designed for Negative Pressure Wound Therapy

by Vincent Milleret, Anne Greet Bittermann, Dieter Mayer and Heike Hall

Materials 2009, 2(1), 292-306; https://doi.org/10.3390/ma2010292 - 25 Mar 2009

Cited by 8 | Viewed by 14712

Many wounds heal slowly and are difficult to manage. Therefore Negative Pressure Wound Therapy (NPWT) was developed where polymer foams are applied and a defined negative pressure removes wound fluid, reduces bacterial burden and increases the formation of granulation tissue. Although NPWT is [...] Read more.

Many wounds heal slowly and are difficult to manage. Therefore Negative Pressure Wound Therapy (NPWT) was developed where polymer foams are applied and a defined negative pressure removes wound fluid, reduces bacterial burden and increases the formation of granulation tissue. Although NPWT is used successfully, its mechanisms are not well understood. In particular, different NPWT dressings were never compared. Here a poly-ester urethane Degrapol^® (DP)-foam was produced and compared with commercially available dressings (polyurethane-based and polyvinyl-alcohol-based) in terms of apparent pore sizes, swelling and effective interconnectivity of foam pores. DP-foams contain relatively small interconnected pores; PU-foams showed large pore size and interconnectivity; whereas PVA-foams displayed heterogeneous and poorly interconnected pores. PVA-foams swelled by 40 %, whereas DP- and PU-foams remained almost without swelling. Effective interconnectivity was investigated by submitting fluorescent beads of 3, 20 and 45 mm diameter through the foams. DP- and PU-foams removed 70-90 % of all beads within 4 h, independent of the bead diameter or bead pre-adsorption with serum albumin. For PVA-foams albumin pre-adsorbed beads circulated longer, where 20 % of 3 mm and 10 % of 20 mm diameter beads circulated after 96 h. The studies indicate that efficient bead perfusion does not only depend on pore size and swelling capacity, but effective interconnectivity might also depend on chemical composition of the foam itself. In addition due to the efficient sieve-effect of the foams uptake of wound components in vivo might occur only for short time suggesting other mechanisms being decisive for success of NPWT. Full article

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394 KiB

Open AccessReview

Calcium Orthophosphate Cements and Concretes

by Sergey V. Dorozhkin

Materials 2009, 2(1), 221-291; https://doi.org/10.3390/ma2010221 - 19 Mar 2009

Cited by 189 | Viewed by 22016

Abstract

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the [...] Read more.

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA) or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone), calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided. Full article

(This article belongs to the Special Issue Biocompatibility of Materials)

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731 KiB

Open AccessArticle

Polymer Hydrogel/Polybutadiene/Iron Oxide Nanoparticle Hybrid Actuators for the Characterization of NiTi Implants

by Aleksandra Jeličić, Alwin Friedrich, Katarina Jeremić, Gerd Siekmeyer and Andreas Taubert

Materials 2009, 2(1), 207-220; https://doi.org/10.3390/ma2010207 - 17 Mar 2009

Cited by 8 | Viewed by 14723

Abstract

One of the main issues with the use of nickel titanium alloy (NiTi) implants in cardiovascular implants (stents) is that these devices must be of very high quality in order to avoid subsequent operations due to failing stents. For small stents with diameters [...] Read more.

One of the main issues with the use of nickel titanium alloy (NiTi) implants in cardiovascular implants (stents) is that these devices must be of very high quality in order to avoid subsequent operations due to failing stents. For small stents with diameters below ca. 2 mm, however, stent characterization is not straightforward. One of the main problems is that there are virtually no methods to characterize the interior of the NiTi tubes used for fabrication of these tiny stents. The current paper reports on a robust hybrid actuator for the characterization of NiTi tubes prior to stent fabrication. The method is based on a polymer/hydrogel/magnetic nanoparticle hybrid material and allows for the determination of the inner diameter at virtually all places in the raw NiTi tubes. Knowledge of the inner structure of the raw NiTi tubes is crucial to avoid regions that are not hollow or regions that are likely to fail due to defects inside the raw tube. The actuator enables close contact of a magnetic polymer film with the inner NiTi tube surface. The magnetic signal can be detected from outside and be used for a direct mapping of the tube interior. As a result, it is possible to detect critical regions prior to expensive and slow stent fabrication processes. Full article

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187 KiB

Open AccessReview

Anaerobic Biodegradation of Detergent Surfactants

by Ute Merrettig-Bruns and Erich Jelen

Materials 2009, 2(1), 181-206; https://doi.org/10.3390/ma2010181 - 16 Mar 2009

Cited by 71 | Viewed by 22010

Abstract

Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly [...] Read more.

Detergent surfactantscan be found in wastewater in relevant concentrations. Most of them are known as ready degradable under aerobic conditions, as required by European legislation. Far fewer surfactants have been tested so far for biodegradability under anaerobic conditions. The natural environment is predominantly aerobic, but there are some environmental compartments such as river sediments, sub-surface soil layer and anaerobic sludge digesters of wastewater treatment plants which have strictly anaerobic conditions. This review gives an overview on anaerobic biodegradation processes, the methods for testing anaerobic biodegradability, and the anaerobic biodegradability of different detergent surfactant types (anionic, nonionic, cationic, amphoteric surfactants). Full article

(This article belongs to the Special Issue Biodegradability of Materials)

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649 KiB

Open AccessArticle

Polymerization Stress Development in Dental Composites: Effect of Cavity Design Factor

by Joseph M. Antonucci, Anthony A. Giuseppetti, Justin N.R. O’Donnell, Gary E. Schumacher and Drago Skrtic

Materials 2009, 2(1), 169-180; https://doi.org/10.3390/ma2010169 - 13 Mar 2009

Cited by 13 | Viewed by 13468

Abstract

The objective of the study was to assess the effect of the cavity design factor (C-factor) on polymerization stress development (PSD) in resin composites. An experimental resin (BT resin) was prepared, which contained 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenylene]propane (B) and triethylene glycol dimethacrylate (T) in [...] Read more.

The objective of the study was to assess the effect of the cavity design factor (C-factor) on polymerization stress development (PSD) in resin composites. An experimental resin (BT resin) was prepared, which contained 2,2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenylene]propane (B) and triethylene glycol dimethacrylate (T) in 1:1 mass ratio, and an activator for visible light polymerization. An experimental composite with demonstrated remineralizing potential was also formulated by inclusion into the BT resin of zirconia-hybridized amorphous calcium phosphate (ACP) filler at a mass fraction of 40 % (BT/ACP composite). A commercial glass-filled composite (TPH) was used as a control. To assess the effect of the test geometry on PSD, C-factor was systematically varied between 0.8 and 6.0 by varying the height of the cylindrical composite specimens. The measured PSD values obtained by cantilever beam tensometry for specimens with variable C-factors were normalized for mass to specimens with a C-factor of 1.33 (h=2.25 mm) as controls to give calculated PSD values. Degrees of vinyl conversions (DC) attained in the TPH control and in the experimental BT/ACP composites were measured by near-infrared spectroscopy. In both the TPH and BT/ACP composite series, PSD_calc increased with the increasing C-factor, confirming the hypothesis that the C-factor value influences PSD values. The higher PSD_meas and PSD_calc values for the experimental BT/ACP composite compared to the commercial TPH composite probably reflect differences in the type and mass of the resin and filler phases in the two types of composite. These differences also account for the observed variation (21 %) in DC attained in a BT/ACP composite 2 h after cure (69.5 %) and in the DC of the TPH composite (57.5 %) having the same C-factor. The cavity design factor seems to play a key role in influencing the PSD of bonded composites, but other factors such as composite mass and composition also must be considered for their effects on PSD. Full article

(This article belongs to the Special Issue Biocompatibility of Materials)

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197 KiB

Open AccessArticle

Preparation of Novel Banana-Shaped Triple Helical Liquid Crystals by Metal Coordination

by Parvez Iqbal, Manickam Mayanditheuar, Laura J. Childs, Michael J. Hannon, Neil Spencer, Peter R. Ashton and Jon A. Preece

Materials 2009, 2(1), 146-168; https://doi.org/10.3390/ma2010146 - 13 Mar 2009

Cited by 7 | Viewed by 14052

Abstract

The synthesis of a series of banana-shaped structures has been carried out, in which the bend unit is formed by a 4,4’-methylenedianiline or 3,3’-methylenedianiline core bearing two symmetric pyridylimine linkages to di- and tri- alkoxyphenylester moieties on the side arms. The molecules, in [...] Read more.

The synthesis of a series of banana-shaped structures has been carried out, in which the bend unit is formed by a 4,4’-methylenedianiline or 3,3’-methylenedianiline core bearing two symmetric pyridylimine linkages to di- and tri- alkoxyphenylester moieties on the side arms. The molecules, in addition to providing an elongated aromatic central core associated with liquid crystal (LC) molecules, also provide binding sites for metals. The methylenedianiline spacer incorporates phenylene groups that sterically prevent the two binding sites from co-ordinating to a single metal centre and the central methylene unit introduces enhanced flexibility into the ligand backbone. Furthermore, complexes have been formed by the co-ordination between 3, 3’-methylenedianiline containing ligands and Cu (I) ions [Cu₂(3a-c)₂][PF₆]₂. Electrospray Mass Spectrometry (ESMS) and Fast Atom Bombardment Mass Spectrometry (FABMS) showed the formation of dimeric species; [Cu (L)₂][PF₆]₂. Finally,thermal analysis of the ligands (1a-d, 2a-d, 3a-c and 4a-d) andCu complexes [Cu₂(3a-c)₂][PF₆]₂ has been carried out in order to investigate the phase properties of these materials. None of the banana-shaped ligands and the metal complexes [Cu₂(3a-c)₂][PF₆]₂ showed any mesophases. Full article

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437 KiB

Open AccessArticle

Biomaterial Studies on AISI 316L Stainless Steel after Magnetoelectropolishing

by Tadeusz Hryniewicz, Krzysztof Rokosz and Massimiliano Filippi

Materials 2009, 2(1), 129-145; https://doi.org/10.3390/ma2010129 - 11 Mar 2009

Cited by 54 | Viewed by 16223

Abstract

The polarisation characteristics of the electropolishing process in a magnetic field (MEP – magnetoelectropolishing), in comparison with those obtained under standard/conventional process (EP) conditions, have been obtained. The occurrence of an EP plateau has been observed in view of the optimization of MEP [...] Read more.

The polarisation characteristics of the electropolishing process in a magnetic field (MEP – magnetoelectropolishing), in comparison with those obtained under standard/conventional process (EP) conditions, have been obtained. The occurrence of an EP plateau has been observed in view of the optimization of MEP process. Up-to-date stainless steel surface studies always indicated some amount of free-metal atoms apart from the detected oxides and hydroxides. Such a morphology of the surface film usually affects the thermodynamic stability and corrosion resistance of surface oxide layer and is one of the most important features of stainless steels. With this new MEP process we can improve metal surface properties by making the stainless steel more resistant to halides encountered in a variety of environments. Furthermore, in this paper the stainless steel surface film study results have been presented. The results of the corrosion research carried out by the authors on the behaviour of the most commonly used material - medical grade AISI 316L stainless steel both in Ringer’s body fluid and in aqueous 3% NaCl solution have been investigated and presented earlier elsewhere, though some of these results, concerning the EIS Nyquist plots and polarization curves are also revealed herein. In this paper an attempt to explain this peculiar performance of 316L stainless steel has been undertaken. The SEM studies, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on 316L samples after three treatments: MP – abrasive polishing (800 grit size), EP – conventional electrolytic polishing, and MEP – magnetoelectropolishing. It has been found that the proposed magnetoelectropolishing (MEP) process considerably modifies the morphology and the composition of the surface film, thus leading to improved corrosion resistance of the studied 316L SS. Full article

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279 KiB

Open AccessReview

Side-chain Liquid Crystal Polymers (SCLCP): Methods and Materials. An Overview

by Tomasz Ganicz and Włodzimierz Stańczyk

Materials 2009, 2(1), 95-128; https://doi.org/10.3390/ma2010095 - 11 Mar 2009

Cited by 52 | Viewed by 19143

Abstract

This review focuses on recent developments in the chemistry of side chain liquid crystal polymers. It concentrates on current trends in synthetic methods and novel, well defined structures, supramolecular arrangements, properties, and applications. The review covers literature published in this century, apart from [...] Read more.

This review focuses on recent developments in the chemistry of side chain liquid crystal polymers. It concentrates on current trends in synthetic methods and novel, well defined structures, supramolecular arrangements, properties, and applications. The review covers literature published in this century, apart from some areas, such as dendritic and elastomeric systems, which have been recently reviewed. Full article

(This article belongs to the Special Issue Liquid Crystals)

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162 KiB

Open AccessReview

Surfactant-mediated Biodegradation of Polycyclic Aromatic Hydrocarbons

by Jing-Liang Li and Bing-Hung Chen

Materials 2009, 2(1), 76-94; https://doi.org/10.3390/ma2010076 - 23 Feb 2009

Cited by 124 | Viewed by 22285

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental pollutants that are known or suspected carcinogens or mutagens. Bioremediation has been used as a general way to eliminate them from the contaminated sites or aquifers, but their biodegradation is rather limited due to their low [...] Read more.

Polycyclic aromatic hydrocarbons (PAHs) are toxic environmental pollutants that are known or suspected carcinogens or mutagens. Bioremediation has been used as a general way to eliminate them from the contaminated sites or aquifers, but their biodegradation is rather limited due to their low bioavailability because of their sparingly soluble nature. Surfactant-mediated biodegradation is a promising alternative. The presence of surfactants can increase the solubility of PAHs and hence potentially increase their bioavailability. However, inconclusive results have been reported on the effects of surfactant on the biodegradation of PAHs. In this work, surfactant-mediated biodegradation of PAHs is reviewed. Full article

(This article belongs to the Special Issue Biodegradability of Materials)

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1582 KiB

Open AccessArticle

A Method for Digital Color Analysis of Spalted Wood Using Scion Image Software

by Sara C. Robinson, Peter E. Laks and Ethan J. Turnquist

Materials 2009, 2(1), 62-75; https://doi.org/10.3390/ma2010062 - 16 Feb 2009

Cited by 32 | Viewed by 15500

Abstract

Color analysis of spalted wood surfaces requires a non-subjective, repeatable method for determining percent of pigmentation on the wood surface. Previously published methods used human visual perception with a square grid overlay to determine the percent of surface pigmentation. Our new method uses [...] Read more.

Color analysis of spalted wood surfaces requires a non-subjective, repeatable method for determining percent of pigmentation on the wood surface. Previously published methods used human visual perception with a square grid overlay to determine the percent of surface pigmentation. Our new method uses Scion Image©, a graphical software program used for grayscale and color analysis, to separate fungal pigments from the wood background. These human interface processes render the wood block into HSV (hue, saturation, value, within the RGB color space), allowing subtle and drastic color changes to be visualized, selected and analyzed by the software. Analysis with Scion Image© allows for a faster, less subjective, and easily repeatable procedure that is superior to simple human visual perception. Full article

(This article belongs to the Special Issue Functional Colorants)

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1079 KiB

Open AccessArticle

Mesomorphic Behavior of Symmetrical and Unsymmetrical Azomethines with Two Imine Groups

by Agnieszka Iwan, Henryk Janeczek, Bozena Jarzabek and Patrice Rannou

Materials 2009, 2(1), 38-61; https://doi.org/10.3390/ma2010038 - 6 Feb 2009

Cited by 28 | Viewed by 13933

Abstract

Seven symmetrical azomethines with two imine groups (HC=N) were synthesized by condensation of the benzene-1,4-dicarboxaldehydewith five amines (first group: A1-A5) and of the 2,5-thiophenedicarboxaldehyde with two amines (second group: AT1-AT2). Additionally, two unsymmetrical azomethines were obtained by a two step condensation of benzene-1,4-dicarboxaldehydewith [...] Read more.

Seven symmetrical azomethines with two imine groups (HC=N) were synthesized by condensation of the benzene-1,4-dicarboxaldehydewith five amines (first group: A1-A5) and of the 2,5-thiophenedicarboxaldehyde with two amines (second group: AT1-AT2). Additionally, two unsymmetrical azomethines were obtained by a two step condensation of benzene-1,4-dicarboxaldehydewith pyren-1-amine(1^st step) (abbreviated hereinafter as AP1) and then AP1 was reacted with4-dodecylaniline or 4-hexadecylaniline (2^nd step) (third group: AP1A-AP1B). Liquid crystalline properties of the azomethines were studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and UV-vis spectroscopy in the function of temperature [UV-vis(T)]. The Wide-Angle X-ray Diffraction (WAXD) technique was used to probe the structural properties of the azomethines. Mesomorphic behavior was observed for symmetrical and unsymmetrical azomethines, obtained from the benzene-1,4-dicarboxaldehyde and symmetrical ones prepared from 2,5-thiophenedicarboxaldehyde and different amineshaving aliphatic chains. Based on the POM and DSC measurements the following mesophases were detected: nematic, smectic A, smectic C, smectic F (I), smectic G (J). Full article

(This article belongs to the Special Issue Liquid Crystals)

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795 KiB

Open AccessArticle

Liquid Crystalline π-Conjugated Copolymers Bearing a Pyrimidine Type Mesogenic Group

by Kohsuke Kawabata and Hiromasa Goto

Materials 2009, 2(1), 22-37; https://doi.org/10.3390/ma2010022 - 16 Jan 2009

Cited by 14 | Viewed by 12642 | Correction

Abstract

Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation [...] Read more.

Phenylene-thiophene-based liquid crystalline π-conjugated copolymers bearing mesogenic groups as side chains were synthesized via a Stille polycondensation reaction and confirmed to exhibit a nematic liquid crystal phase at appropriate temperatures. The formation of a nematic phase, but not a smectic phase indicates cooperation of the main chain and side chain in the formation of a nematic main-chain/side-chain liquid crystal phase. The generation of polarons in the main chain as charge carriers during in-situ vapor doping of iodine is confirmed to increase with a doping progresses, exhibiting Dysonian paramagnetic behavior typical of conductive polymers. Full article

(This article belongs to the Special Issue Liquid Crystals)

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420 KiB

Open AccessArticle

Colorimetric Assay and Antibacterial Activity of Cotton, Silk, and Wool Fabrics Dyed with Peony, Pomegranate, Clove, Coptis chinenis and Gallnut Extracts

by Young-Hee Lee, Eun-Kyung Hwang and Han-Do Kim

Materials 2009, 2(1), 10-21; https://doi.org/10.3390/ma2010010 - 15 Jan 2009

Cited by 77 | Viewed by 16734

Abstract

To investigate the antibacterial functionality of natural colorant extracts, five kinds of natural dying aqueous solutions were obtained by extraction from peony, pomegranate, clove, Coptis chinensis and gallnut using water at 90 °C for 90 min with a liquor ratio (solid natural colorant [...] Read more.

To investigate the antibacterial functionality of natural colorant extracts, five kinds of natural dying aqueous solutions were obtained by extraction from peony, pomegranate, clove, Coptis chinensis and gallnut using water at 90 °C for 90 min with a liquor ratio (solid natural colorant material/water, weight ratio) of 1:10. The colorimetric assay and antibacterial activity of cotton, silk, and wool fabrics dyed with these natural colorant extracts were examined. It was found that these properties were significantly dependent on the structure of colorant and the kind of fabrics. The hues (H) of all fabrics dyed with these natural colorants were in the range of 6.05YR -1.95Y. The order of value (V) was wool, silk and cotton. The chroma (C) of all samples was found to be at very low levels indicating the natural tone. All the fabrics dyed with the five natural colorants (peony, pomegranate, clove, Coptis chinensis and gallnut) extracts displayed excellent antibacterial activity (reduction rate: 96.8 - 99.9%) against Staphylococcus aureus. However, in the case of Klebsiella pneumoniae, the antibacterial activity was found to depend on the kind of natural colorant extract used. Full article

(This article belongs to the Special Issue Functional Colorants)

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514 KiB

Open AccessArticle

Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

by Hiroaki Onoda, Ken-ichi Okumoto, Atsushi Nakahira and Isao Tanaka

Materials 2009, 2(1), 1-9; https://doi.org/10.3390/ma2010001 - 9 Jan 2009

Cited by 19 | Viewed by 12355

Abstract

Copper orthophosphate, Cu₃(PO₄)₂, and cyclo-tetraphosphates, Cu₂P₄O₁₂, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and [...] Read more.

Copper orthophosphate, Cu₃(PO₄)₂, and cyclo-tetraphosphates, Cu₂P₄O₁₂, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied. Full article

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Materials, Volume 2, Issue 1 (March 2009) – 14 articles , Pages 1-306

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