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Best Material (best + material)

Distribution by Scientific Domains

Polymers and Materials Science	50%

Selected Abstracts

Development of spray- and freeze-dried high-concentration sesamol emulsions and antioxidant evaluation in fibroblasts and UV-exposed rat skin slices

DRUG DEVELOPMENT RESEARCH, Issue 5 2008
Juliana Alencar
Abstract Dry sesamol emulsions were synthesized from several combinations of saccharose with hydroxypropylmethylcellulose (HPMC) or sodium caseinate (SC) using spray-drying techniques at 120° to 180°C, or freeze-drying. On the basis of physical characteristics such as droplet size distribution, residual moisture, and microscopic structure, the best material was obtained when spray-drying was applied at either 150° or 180°C with SC or HPMC as excipients, respectively. The extent to which the antioxidant properties of free sesamol towards a set of free radicals (galvinoxyl, diphenylpicrylhydrazyl, superoxide, and hydroxyl) were altered in the starting and reconstituted liquid emulsions submitted to normal storage or pre-exposed to a flux hydroxyl radicals was investigated. Emulsions were further evaluated for their antioxidant properties in cultured 3T3 murine fibroblasts and in an ex vivo model of ultraviolet irradiated rat skin. It was found that, in the material having the best physical properties, encapsulation was decisive in: (1) improving the overall antioxidant behavior of reconstituted versus starting liquid emulsions: (2) sparing sesamol consumption due to free radical attack; and (3) significantly protecting cells and skin against free radical- or irradiation-induced enzymatic release and/or lipid peroxidation. Demonstrating a high activity at high dilutions where interactions of excipient become negligible, the new emulsions could be of great interest in sesamol-based pharmacology or topical applications. Drug Dev Res 69:251,266, 2008. © 2008 Wiley-Liss, Inc. [source]

Study of human neutrophil peptides in saliva by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2009
Ming-Hui Yang
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is used to rapidly characterize the human neutrophil peptides , HNP 1, 2, and 3 , in saliva. The saliva excreted from the parotid and sublingual/submandibular glands of 70 individuals were collected and examined using MALDI-TOF. The MALDI approach requires no sample pretreatment other than mixing the saliva-absorbing material with the matrix and drying under ambient conditions. Tissue paper was the best material for collecting the saliva samples because of its strong texture and high absorbance, and sinapinic acid was the best MALDI matrix for the analysis of the HNPs. HNPs were detected in almost all the samples collected from the parotid glands, with no obvious differences among age or gender. In contrast, the distribution of the HNPs in the samples collected from the sublingual/submandibular glands was age-dependent: no HNPs were detected for those collected from individuals younger than 30, but the HNPs were present in all of the samples collected from those older than 60 years. The increased probability of detecting saliva HNPs with age suggests that HNPs may function as a biomarker for aging. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Symmetric Versus Unsymmetric Platinum(II) Bis(aryleneethynylene)s with Distinct Electronic Structures for Optical Power Limiting/Optical Transparency Trade-off Optimization

ADVANCED FUNCTIONAL MATERIALS, Issue 4 2009
Guijiang Zhou
Abstract A new series of symmetric and unsymmetric Pt(II) bis(acetylide) complexes of the type DC,CPt(PBu3)2C,CD (DPtD), AC,CPt(PBu3)2C,CA (APtA) and DC,CPt(PBu3)2C,CA (DPtA) (D, donor groups; A, acceptor groups) are synthesized, and show superior optical power limiting (OPL)/optical transparency trade-offs. By tailoring the electronic properties of the aryleneethynylene group, distinct electronic structures for these metalated complexes can be obtained, which significantly affect their photophysical behavior and OPL properties for a nanosecond laser pulse at 532,nm. Electronic influence of the ligand type and the molecular symmetry of metal group on the optical transparency/nonlinearity optimization is thoroughly elucidated. Generally, aryleneethynylene ligands with , electron-accepting nature will effectively enhance the harvesting efficiency of the triplet excited states. The ligand variation to the OPL strength of these Pt(II) compounds follows the order: DPtD,>,DPtA,>,APtA. These results could be attributed to the distinctive excited state character induced by their different electronic structures, on the basis of the data from both photophysical studies and theoretical calculations. All of the complexes show very good optical transparencies in the visible-light region and exhibit excellent OPL responses with very impressive figure of merit ,ex/,o values (up to 17), which remarkably outweigh those of state-of-the-art reverse saturable absorption dyes such as C60 and metallophthalocyanines with very poor transparencies. Their lower optical-limiting thresholds (0.05,J,cm,2 at 92% linear transmittance) compared with that of the best materials (ca. 0.07,J,cm,2 for InPc and PbPc dyes) currently in use will render these highly transparent materials promising candidates for practical OPL devices for the protection of human eyes and other delicate electro-optic sensors. [source]

Corrosion of coating materials in oxidizing and hydrogen chloride containing atmospheres

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 12 2002
S.C. Cha
The boiler tubes in waste incinerator plants and power plants are mainly corrosive strained. This paper presents the corrosion behaviour of various coating materials in two corrosive atmospheres at 500°C. In a first test, Ni-based materials applied by High Velocity Oxygen Fuel Flame (HVOF)-spraying and Atmospheric Plasma Spraying (APS) as well as Cr-based materials obtained by diffusion coating process are tested in oxidizing atmosphere with water saturation. The results of the corrosion test in this H2O-O2 -N2 -atmosphere show that NiCr applied by HVOF is less oxidized than that applied by APS-coating, whereas NiCrBSi coating by APS shows higher resistance than that applied by HVOF-spraying. The diffusion coating of Cr/Si is better than that of pure Cr. In a second test, metallic Mo and W-based materials applied by thermal spraying are tested to verify their corrosion resistance in HCl-H2O-O2 -N2 -atmosphere. It is shown that pure Mo applied by APS on 13 CrMo 44 and WCrNi sprayed on 15 Mo 3 by HVOF as well as on 13 CrMo 44 show relatively high corrosion resistance, whereas Mo sprayed by APS on 15 Mo 3 is not resistant. Both tungsten-cobalt-chromium mixtures show extremely high oxidation rates. Base materials in both tests were the standard boiler tube materials 15 Mo 3 and 13 CrMo 44. But even the low corrosion rates of the best materials in these tests are higher compared to those of materials already presented by Cha et al. in an earlier paper. Korrosion von Beschichtungswerkstoffen in oxidierenden und chlorwasser-stoffhaltigen Atmosphären Die Wärmetauscherrohre von Müllverbrennungsanlagen und Kraftwerken sind hauptsächlich korrosiv beansprucht. Die vorliegende Veröffentlichung stellt das Korrosionsverhalten von verschiedenen Beschichtungswerkstoffen in zwei korrosiven Atmosphären bei einer Temperatur von 500°C vor. Zuerst wurden die durch Hochgeschwindigkeitsflammspritzen (HVOF) und atmosphärisches Plasmaspritzen (APS) aufgetragenen Ni-Basiswerkstoffe und die diffusionsbeschichteten Cr-Basiswerkstoffe in oxidierender Atmosphäre mit Wassersättigung getestet. Die Ergebnisse der Korrosionsversuche in der H2O-O2 -N2 -Atmosphäre zeigen, dass NiCr (HVOF) resistenter ist als durch APS Beschichtung, wobei die Beschichtung mit NiCrBSi durch APS höhere Beständigkeit als die durch HVOF zeigt. Eine diffusionsbeschichtete Cr/Si-Schicht zeigt höhere Beständigkeit als eine reine Cr-Schicht. In einer zweiten Versuchsreihe wurden metallisches Mo und W-Basiswerkstoffe auf Korrosionsbeständigkeit in HCl-H2O-O2 -N2 -Atmosphäre untersucht. Dabei zeigt sich, dass die Proben mit Mo (APS) auf 13 CrMo 44, sowie WCrNi (HVOF) auf 15 Mo 3 und 13 CrMo 44 relativ hohe Korrosionsbeständigkeiten besitzen. Dagegen ist Mo (APS) auf 15 Mo 3 nicht beständig. Beide W-Co-Verbindungen zeigen extrem hohe Oxidationsraten. Als Basiswerkstoffe wurden die Standard Kesselrohr-Werkstoffe 15 Mo 3 und 13 CrMo 44 gewählt. Aber auch die niedrigsten Korrosionsraten der besten Werkstoffe in dieser Untersuchung sind höher als diejenigen der in einer früheren Arbeit von Cha et al. vorgestellten Werkstoffe. [source]