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Different Compositions (different + composition)
Selected AbstractsBrand specific responses to smokeless tobacco in a rat lip canal modelJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 6 2010Joel L. Schwartz J Oral Pathol Med (2010) 39: 453,459 Background:, Different compositions of smokeless tobacco (ST) are widely thought to cause oral carcinoma at different rates but there is little direct evidence for this hypothesis. Methods:, We used a rat lip canal model to examine the mucosal changes induced by chronic daily exposure to four different brands of ST: Skoal, Copenhagen, Ettan Swedish Snus, and Stonewall, differing in measured levels of: tobacco specific nitrosamines (TSNAs), unprotonated nicotine, moisture, and pH. Results:, Exposure to the lip canal for 12 months produced changes in the mucosa marked by increases in S phase and M phase cells for the Skoal and Copenhagen exposed rats. This correlated with the high level of TSNAs and nicotine in these products. All the tobacco products, to different degrees, induced sites of moderate to severe dysplasia some with extensive rete peg outgrowth from the oral mucosa not seen in the controls. Many of these sites showed a loss of p16 expression. Conclusions:, While all ST products caused dysplasia, the products with lower levels of TSNAs and unprotonated nicotine caused less, consistent with the model that tobacco with low levels of nitrosamines might potentially induce fewer carcinomas in human users. [source] A SPECTROSCOPIC INVESTIGATION OF PIGMENT AND CERAMIC SAMPLES FROM COPÁN, HONDURAS,ARCHAEOMETRY, Issue 1 2009R. A. GOODALL A combination of micro-Raman spectroscopy, micro-infrared spectroscopy and SEM,EDX was employed to characterize decorative pigments on Classic Maya ceramics from Copán, Honduras. Variation in red paint mixtures was correlated with changing ceramic types and improvements in process and firing techniques. We have confirmed the use of specular hematite on Coner ceramics by the difference in intensities of Raman bands. Different compositions of brown paint were correlated with imported and local wares. The carbon-iron composition of the ceramic type, Surlo Brown, was confirmed. By combining micro-Raman analysis with micro-ATR infrared and SEM,EDX, we have achieved a more comprehensive characterization of the paint mixtures. These spectroscopic techniques can be used non-destructively on raw samples as a rapid confirmation of ceramic type. [source] Structural, optical and photoconductive properties of electron beam evaporated CdSxSe1-x filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2010K. Sivaramamoorthy Abstract CdSxSe1-x films were deposited by the electron beam evaporation technique on glass substrates at different temperatures in the range 30 , 300 °C using the laboratory synthesized powders of different composition. The films exhibited hexagonal structure and the lattice parameters shifted from CdSe to CdS side as the composition changed from CdSe to CdS side. The bandgap of the films increased from 1.68 to 2.41 eV as the concentration of CdS increased. The root-mean-roughness (RMS) values are 3.4, 2.6, 1.2 and 0.6 nm as the composition of the films shifted towards CdS side. The conductivity varies from 30 ,cm -1 to 480 ,cm -1 as the ,x' value increases from 0 to 1. The films exhibited photosensitivity. The PL spectrum shifts towards lower energies with decreasing x, due to the decrease of the fundamental gap with Se composition. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Capillary electrophoresis using copolymers of different composition as physical coatings: A comparative studyELECTROPHORESIS, Issue 5-6 2006Guillaume L. Erny Abstract In this work, a comparative study on the use of different polymers as physically adsorbed coatings for CE is presented. It is demonstrated that the use of ad hoc synthesized polymers as coatings allows tailoring the EOF in CE increasing the flexibility of this analytical technique. Namely, different polymers were synthesized at our laboratory using different percentages of ethylpyrrolidine methacrylate (EpyM) and N,N -dimethylacrylamide (DMA). Thus, by modifying the percentage of EpyM and DMA monomers it is possible to manipulate the positive charge of the copolymer, varying the global electrical charge on the capillary wall and with that the EOF. These coated capillaries are obtained by simply flushing a given EpyM,DMA aqueous solution into bare silica capillaries. It is shown that by using these coated capillaries at adequate pHs, faster or more resolved CE separations can be achieved depending on the requirements of each analysis. Moreover, it is demonstrated that these coated capillaries reduce the electrostatic adsorption of basic proteins onto the capillary wall. Furthermore, EpyM,DMA coatings allow the reproducible chiral separation of enantiomers through the partial filling technique (PFT). The EpyM,DMA coated capillaries are demonstrated to provide reproducible EOF values independently of the pH and polymer composition with%RSD values lower than 2% for the same day. It is also demonstrated that the coating procedure is reproducible between capillaries. The compatibility of this coating protocol with CE in microchips is discussed. [source] Comparison of different algorithms to calculate electrophoretic mobility of analytes as a function of binary solvent compositionELECTROPHORESIS, Issue 10 2003Abolghasem Jouyban Abstract Ten different mathematical models representing the electrophoretic mobility of analytes in capillary electrophoresis in mixed solvents of different composition have been compared using 32 experimental data sets. The solvents are binary mixtures of water-methanol, water-ethanol and methanol-ethanol, respectively. Mean percentage deviation (MPD), overall MPD (OMPD) and individual percentage deviation (IPD) have been considered as comparison criteria. The results showed that a reorganized solution model, namely the combined nearly ideal binary solvent/Redlich-Kister equation, is the most accurate model among other similar models concerning both correlation ability and prediction capability. [source] The microbial community of Vetiver root and its involvement into essential oil biogenesisENVIRONMENTAL MICROBIOLOGY, Issue 10 2008Luigi Del Giudice Summary Vetiver is the only grass cultivated worldwide for the root essential oil, which is a mixture of sesquiterpene alcohols and hydrocarbons, used extensively in perfumery and cosmetics. Light and transmission electron microscopy demonstrated the presence of bacteria in the cortical parenchymatous essential oil-producing cells and in the lysigen lacunae in close association with the essential oil. This finding and the evidence that axenic Vetiver produces in vitro only trace amounts of oil with a strikingly different composition compared with the oils from in vivo Vetiver plants stimulated the hypothesis of an involvement of these bacteria in the oil metabolism. We used culture-based and culture-independent approaches to analyse the microbial community of the Vetiver root. Results demonstrate a broad phylogenetic spectrum of bacteria, including ,-, ,- and ,- Proteobacteria, high-G+C-content Gram-positive bacteria, and microbes belonging to the Fibrobacteres/Acidobacteria group. We isolated root-associated bacteria and showed that most of them are able to grow by using oil sesquiterpenes as a carbon source and to metabolize them releasing into the medium a large number of compounds typically found in commercial Vetiver oils. Several bacteria were also able to induce gene expression of a Vetiver sesquiterpene synthase. These results support the intriguing hypothesis that bacteria may have a role in essential oil biosynthesis opening the possibility to use them to manoeuvre the Vetiver oil molecular structure. [source] Volatile constituents of Vietnamese pummelo, orange, tangerine and lime peel oilsFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2002N. T. Minh Tu Abstract The compositions of Vietnamese pummelo (Citrus grandis Osbeck), orange (C. sinensis Osbeck), tangerine (C. reticulata Blanco var. tangerine) and lime (C. limonia Osbeck) peel oil samples have been investigated by GC and GC,MS. The essential oils were extracted by the cold-pressing method. Hydrocarbons, followed by aldehydes and alcohols, were the most abundant compounds in all four kinds of samples. Their percentages, respectively, were >98.7%, >97.6%, >98.6% and >95.4% in hydrocarbons; >0.3%, 0.4%, >0.3% and 1.1% in total aldehydes; 0.2%, 0.5%, 0.4% and 0.7% in alcohols. In Vietnamese pummelo oil, ,-terpinene was not detected, while terpinolene was detected in small amounts and nootkatone only at a level of <0.05%. Orange oil composition was comparable to that of other sweet orange oils. ,-3-Carene was detected at a level of 0.1%. Tangerine oil is easily distinguished from other citrus oils by its content of various aliphatic aldehydes. Lime oil presented a very different composition from the other oils studied. Its limonene content was substantially lower than that of pummelo, orange and tangerine oils, whereas ,-terpinene, ,-pinene and ,-pinene occurred in higher proportions, moreover, the sesquiterpene hydrocarbon fraction of this oil is qualitatively more complex and quantitatively more abundant than in the other oils. Copyright © 2002 John Wiley & Sons, Ltd. [source] Phase Reorganization in Self-Assembled Systems Through Interparticle Material Transfer,ADVANCED MATERIALS, Issue 10 2007C. Moitzi Transfer of material occurs when internally nanostructured emulsion droplets of different composition are mixed. This happens without droplet fusion. As the internal structure is dependent on the composition, the transfer can be followed by monitoring these changes using time-resolved small angle X-ray scattering (SAXS; see figure). [source] Influence of the copolymer architecture and composition on the response and mechanical properties of pH-sensitive fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Anasuya Sahoo Abstract A series of copolymers based on acrylonitrile (AN) and acrylic acid (AA) with varying architecture and composition were synthesized using free radical polymerization. The distribution of monomers in the copolymer chains could be successfully controlled by regulating the addition of more reactive monomer (AA). Copolymers having nearly random distribution of comonomer moieties to block type distribution with different composition (10,50 mol % AA) were synthesized to investigate the effect of polymer architecture and composition on pH response and mechanical properties of resultant structures. These copolymers were solution spun from dimethylformamide-water system, drawn in coagulation bath, and annealed at 120°C for 2 h to make pH-sensitive fibers which were structurally stable without the need of chemical crosslinking. The fibers from block copolymers showed significantly better tensile strength (34.3 MPa), higher retractive forces (0.26 MPa), and enhanced pH response (swelling 3890%) in comparison with fibers from random copolymer (13.55 MPa, 0.058 MPa, and 1723%, respectively). The tensile strength and retractive forces could be further improved to a value of 72 MPa and 0.36 MPa, respectively, by changing the composition of the block copolymer while retaining the swelling percentage similar to the random copolymer mentioned above. It is proposed that on processing to fibers, the block copolymers could form a segregated domain structure with separate domains of AA and AN, where AN domains were responsible for high structural integrity by providing connectivity among polymer chains, while AA domains showed improved response to changing pH of the environment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Cellular/intramuscular myxoma and grade I myxofibrosarcoma are characterized by distinct genetic alterations and specific composition of their extracellular matrixJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 7 2009Stefan M. Willems Abstract Cellular myxoma and grade I myxofibrosarcoma are mesenchymal tumours that are characterized by their abundant myxoid extracellular matrix (ECM). Despite their histological overlap, they differ clinically. Diagnosis is therefore difficult though important. We investigated their (cyto) genetics and ECM. GNAS1 -activating mutations have been described in intramuscular myxoma, and lead to downstream activation of cFos. KRAS and TP53 mutations are commonly involved in sarcomagenesis whereby KRAS subsequently activates c-Fos. A well-documented series of intramuscular myxoma (three typical cases and seven cases of the more challenging cellular variant) and grade I myxofibrosarcoma (n= 10) cases were karyotyped, analyzed for GNAS1, KRAS and TP53 mutations and downstream activation of c-Fos mRNA and protein expression. ECM was studied by liquid chromatography mass spectrometry and expression of proteins identified was validated by immunohistochemistry and qPCR. Grade I myxofibrosarcoma showed variable, non-specific cyto-genetic aberrations in 83,5% of cases (n= 6) whereas karyotypes of intramuscular myxoma were all normal (n= 7). GNAS1 -activating mutations were exclusively found in 50% of intramuscular myxoma. Both tumour types showed over-expression of c-Fos mRNA and protein. No mutations in KRAS codon 12/13 or in TP53 were detected. Liquid chromatography mass spectrometry revealed structural proteins (collagen types I, VI, XII, XIV and decorin) in grade I myxofibrosarcoma lacking in intramuscular myxoma. This was confirmed by immunohistochemistry and qPCR. Intramuscular/cellular myxoma and grade I myxofibrosarcoma show different molecular genetic aberrations and different composition of their ECM that probably contribute to their diverse clinical behaviour. GNAS1 mutation analysis can be helpful to distinguish intramuscular myxoma from grade I myxofibrosarcoma in selected cases. [source] Application of the parametric bootstrap method to determine statistical errors in quantitative X-ray microanalysis of thin filmsJOURNAL OF MICROSCOPY, Issue 1 2007ALDO ARMIGLIATO Summary We applied the parametric bootstrap to the X-ray microanalysis of Si-Ge binary alloys, in order to assess the dependence of the Ge concentrations and the local film thickness, obtained by using previously described Monte Carlo methods, on the precision of the measured intensities. We show how it is possible by this method to determine the statistical errors associated with the quantitative analysis performed in sample regions of different composition and thickness, but by conducting only one measurement. We recommend the use of the bootstrap for a broad range of applications for quantitative microanalysis to estimate the precision of the final results and to compare the performances of different methods to each other. Finally, we exploited a test based on bootstrap confidence intervals to ascertain if, for given X-ray intensities, different values of the estimated composition in two points of the sample are indicative of an actual lack of homogeneity. [source] NITROGEN LIMITATION EFFECTS OF DIFFERENT NITROGEN SOURCES ON NUTRITIONAL QUALITY OF TWO FRESHWATER ORGANISMS, SCENEDESMUS QUADRICAUDA (CHLOROPHYCEAE) AND SYNECHOCOCCUS SP. (CYANOPHYCEAE)JOURNAL OF PHYCOLOGY, Issue 5 2003Gunnel Ahlgren Food quality for grazers has been related to mineral (nitrogen, phosphorus) and biochemical (amino acids, fatty acids) constituents. The aim of the study was to examine the influence of different nitrogen sources on these constituents in two organisms, the green alga Scenedesmus quadricauda Turp. and the cyanobacterium Synechococcus sp., commonly used in feeding experiments. The two organisms were grown in continuous cultures at different growth rates. Nitrate or ammonium salts were used as nitrogen sources under both replete and limited conditions. Carbon content (mg·g,1 dry weight) was stable in both organisms independent of nitrogen source, nitrogen limitation, and growth rate. Nitrogen content decreased with limitation and growth rate in Scenedesmus and to a lesser degree in Synechococcus, whereas changes in phosphorus content were not statistically significant. The relative proportions of amino acids (% of total amino acids) were relatively stable in both organisms, whereas the proportions of fatty acids varied with growth rate and limitation. Fatty acid content was much lower in Synechococcus than in Scenedesmus. At N limitation, polyunsaturated fatty acids (PUFAs) showed lower levels in both organisms. The change occurred in the ,3 PUFA (linolenic acid) of the green alga and in the ,6 PUFA (linoleic acid) of the cyanobacterium. The difference in the response of N limitation in the two organisms may be traced to the different composition of the chloroplast membranes (the prokaryotic way) and the microsomal membranes (the eukaryotic way) where the desaturation takes place. [source] Soil organic matter beyond molecular structure Part I: Macromolecular and supramolecular characteristicsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2006Gabriele E. Schaumann Abstract This contribution reviews and discusses structural aspects of soil organic matter (SOM) and humic substances (HS) with special respect to the macromolecular and the supramolecular view. It can be concluded that (1) dissolved humic acids behave as supramolecular associations of relatively small molecules with an enormous flexibility of reaction of environmental conditions, (2) multivalent cations may increase the apparent molecular weight by the formation of coordinative crosslinks in dissolved and undissolved natural organic matter (NOM), (3) sorption nonlinearity in solid humic acids and SOM may be due to polymer properties of NOM, (4) sorbates affect sorbent characteristics of SOM, and (5) hysteresis and conditioning effects in SOM can up to now best be explained with the polymer analogy. A distinct polydispersivity of SOM over a wide range of molecular masses is to be assumed. The supramolecular and the macromolecular models were derived from humic acids with different composition and on the basis of different sample states. Although the supramolecular model has not explicitely been shown for unfractionated DOM, the combination of all discussed studies suggests supramolecular as well as macromolecular characteristics of NOM. Neither macromolecules nor small molecules can be fully excluded in solid and dissolved SOM. Microregions with different properties provide different types of sorption sites. SOM is suggested to be regarded as amorphous material. This point of view is not restricted to high molecular masses and may supplement our understanding of SOM by the model of physical aging. [source] Microbial biomass and activity in composts of different composition and ageJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2004Andreas Gattinger Abstract The aim of this study was to perform a comparison of microbial activity and biomass in biowaste (BWC), yard waste (YWC), and cattle-manure composts (CMC) of different age. Two different methods for either biomass (microbial C following fumigation-extraction and microbial lipid phosphate) or activity measurements (CO2 -production rate and fluorescein diacetate hydrolysis) provided comparable information, as judged from their strong correlation. Microbial biomass and activity declined with time in all composts. Microbial biomass C was strongly correlated with microbial activity but was even stronger correlated with pH. CMC proved to be very distinct from the two other compost types by having the highest biomass and the lowest specific activity (i.e., activity per unit biomass). The microbiological properties analyzed allow us to discriminate among different compost types, helping to assign their potential applications. Mikrobielle Biomasse und Aktivität in Komposten unterschiedlicher Zusammensetzung und unterschiedlichen Alters Ziel dieser Studie war es, Bioabfall-, Grünabfall- und Rindermistkomposte unterschiedlicher Altersgruppen hinsichtlich ihrer mikrobiellen Aktivität und Biomasse zu vergleichen. Die zwei unterschiedlichen Methoden für die Bestimmung der mikrobiellen Biomasse (Cmik mittels Fumigation-Extraktion und Lipidphosphat) und Aktivität (CO2 -Produktion und Hydrolyse von Fluoresceindiacetat) lieferten jeweils vergleichbare Aussagen, die Parameter waren eng miteinander korreliert. Mikrobielle Biomasse und Aktivität nahmen mit zunehmendem Alter in den einzelnen Komposten ab. Mikrobieller C war eng mit der mikrobiellen Aktivität korreliert, jedoch war die Korrelation zwischen dem pH-Wert und Cmik stärker ausgeprägt. Die größte mikrobielle Biomasse und die niedrigste spezifische Aktivität (Aktivität pro Biomasseeinheit) wurden im CMC festgestellt, wodurch sich dieser Kompost deutlich von den beiden anderen Komposten unterschied. Die in dieser Untersuchung beschriebenen mikrobiellen Eigenschaften ermöglichen es, zwischen Komposten unterschiedlicher Zusammensetzung zu unterscheiden und daraus mögliche Anwendungsbereiche für Komposte abzuleiten. [source] Synthesis and Characterization of Biodegradable Poly(, -caprolactone)-Polyglycolide-Poly(ethylene glycol) Monomethyl Ether Random CopolymerMACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2004Shaobing Zhou Abstract Summary: Poly(, -caprolactone)-polyglycolide-poly(ethylene glycol) monomethyl ether random copolymers were synthesized from , -caprolactone (, -CL), glycolide (GA) and poly(ethylene glycol) monomethyl ether (MPEG) using stannous octoate as catalyst at 160,°C by bulk polymerization. The copolymers with different composition were synthesized by adjusting the weight ration of reaction mixture. The resultant copolymer with a weight ratio (10:15:75) of MPEG2000, GA, and CL was characterized by IR, 1H NMR, GPC and DSC. The new biodegradable copolymer has potential for medical applications since it is combined with properties of PCL, PGA and MPEG. [source] Recent data on the number of active centers and propagation rate constants in olefin polymerization with supported ZN catalystsMACROMOLECULAR SYMPOSIA, Issue 1 2004V.A. Zakharov Abstract Data on the number of active centers (Cp) and propagation rate constants (Kp) have been obtained by means of polymerization quenching with 14CO of propylene and ethylene polymerization with supported titanium-magnesium catalysts (TMC) with different composition. In the case of propylene polymerization the Cp and Kp values have been measured separately for isospecific, aspecific and low stereospecific centers. Effects of MgCl2 support, internal and external donors are discussed on the basis of data obtained. Data on the strong effect of diffusion limitation at ethylene polymerization with number of TMC have been obtained and a set of methods have been used to exclude this effect. Data on Cp and Kp values at ethylene polymerization with low stereospecific and highly stereospecific catalysts are presented. [source] Optical bandgap and quantum well model in hydrogenated amorphous silicon carbon alloy filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003D.K. BasaArticle first published online: 14 JAN 200 Abstract Hydrogenated amorphous silicon carbon alloy (a-SiC : H) films of various composition were prepared by the rf glow discharge decomposition of acetylene and silane as well as ethylene and silane and were also annealed for various annealing temperatures. Careful and detailed IR absorption and the optical bandgap (Eopt) measurements were undertaken for a-SiC : H films of different composition (x) and annealing temperatures (Ta). Interesting variation of Eopt with x and Ta have been observed. Our study demonstrates, for the first time, that the models involving alloying or/and ordering break down and the proposed quantum well model based on heterogeneity is found to be the only model capable of explaining the observed variation of Eopt. This, consequently, may have considerable implications. [source] Compaction of fiber reinforcementsPOLYMER COMPOSITES, Issue 3 2002Gibson L. Batch In resin transfer molding, dry fiber reinforcements are compacted as the mold closes before injection of a curable resin matrix. This paper presents experimental data of compaction pressure as a function of fiber volume fraction. Data are presented for woven roving mats, random fiber mats, loose fiber rovings for pultrusion, and uniaxial or biaxial roving mats. These data are fit to a mathematical model derived in an Appendix. Experimental data are also given for six combinations of reinforcements. We use the compaction model of each constituent layer to predict the average volume fraction assuming that fiber layers do not interact. However, we see that most combinations of reinforcements have fiber volume fractions greater than expected at pressures under 50 psi, indicating a synergistic packing between the layers of different composition. [source] Dynamic mechanical behavior of LCP fiber/glass fiber,reinforced LLDPE compositesPOLYMER COMPOSITES, Issue 2 2001S. A. R. Hashmi Liquid crystalline polymer (LCP) fibers and glass fibers have been used to rein force linear low density polyethylene (LLDPE) by using an elastic melt extruder and the compression molding technique. The impact behavior of hybrid composites of different composition is compared and is explained on the basis of the volume frac tion of the fibers. Addition of glass fibers decreases the Izod impact strength LLDPE. The impact strength of the composites increases when glass fibers are placed by LCP fibers. Dynamic mechanical , and , relaxations are studied and effect of variation of fiber composition on these relaxations is reported in the tem perature range from ,50 to 150°C at 1 Hz frequency, a relaxation shifts toward higher temperatures with addition of fibers in LLDPE. Addition of fibers increases the storage modulus of LLDPE. [source] Diffuse scattering and short-range order in uranium iodine phthalocyanine [U1,xPc2]I2,y and the X-ray structure analysis of crystals with diffuse superstructure reflectionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2003J. Krawczyk Crystals of uranium iodine phthalocyanine present an example of a disordered commensurate modulated structure of the intergrowth type. The short-range order of both uranium ions and iodine chains [I]n has been analysed by Reverse Monte Carlo (RMC) simulation of X-ray diffuse scattering. The diffraction pattern of uranium iodine phthalocyanine contains diffuse superstructure reflections. In the routine crystal structure analysis diffuse superstructure reflections may be either omitted or measured and classified along with other Bragg reflections. The crystal structure of uranium iodine phthalocyanine is an example of such ambiguity. The crystal structures of two specimens of [U1,xPc2]I2,y with slightly different composition have been published in the literature with different space groups and unit cells. We have shown that the structure of both specimens differs only in the degree of short-range order and is isostructural with [YbPc2]I2. We have also shown that while the omission of diffuse reflections results in the average crystal structure, the treatment of these reflections as normal Bragg reflections is incorrect and produces the structure averaged over a limited small range. [source] ICP,MS ANALYSIS OF GLASS FRAGMENTS OF PARTHIAN AND SASANIAN EPOCH FROM SELEUCIA AND VEH ARDA,?R (CENTRAL IRAQ)*ARCHAEOMETRY, Issue 3 2008P. MIRTI Forty-one glass fragments were analysed by inductively coupled plasma , mass spectrometry, determining 40 major, minor and trace elements, including rare earth elements. The fragments came from excavations carried out at the archaeological sites of Seleucia and Veh Arda,?r in modern Iraq, and were dated to the Parthian and Sasanian epochs. Analytical data indicate that all the samples are silica,soda,lime glasses. Magnesium and potassium oxide contents below 1% suggest that eight out of nine glasses from Seleucia, dating from between the first and the third century ad, could have been obtained by use of an evaporite as a flux; the same conclusion can be drawn for some of the Sasanian glasses dating from the fourth and fifth centuries ad. The other glasses from Veh Arda,?r, as well as the remaining sample from Seleucia, are characterized by higher contents of magnesium and potassium, which suggests recourse to plant ash; different magnesium and phosphorus contents allow one to separate these samples into two main groups, pointing to the use of different kinds of plant ash. Aluminium and calcium contents, together with trace element data, may indicate that different sands were used for preparing glasses of different composition. Samples from Seleucia and Veh Arda,?r are mainly blue,green and green to yellow,green, respectively; iron and manganese contents suggest that the furnace atmosphere was mainly responsible for the development of these hues. [source] The first crystal structure of a gramicidin complex with sodium: high-resolution study of a nonstoichiometric gramicidin D,NaI complexACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2010A. Olczak The crystal structure of the nonstoichiometric complex of gramicidin D with NaI has been studied using synchrotron radiation at 100,K. The limiting resolution was 1.25,Å and the R factor was 16% for 19,883 observed reflections. The general architecture of the antiparallel two-stranded gramicidin dimers in the studied crystal was a right-handed antiparallel double-stranded form that closely resembles the structures of other right-handed species published to date. However, there were several surprising observations. In addition to the significantly different composition of linear gramicidins identified in the crystal structure, including the absence of the gramicidin C form, only two cationic sites were found in each of the two independent dimers (channels), which were partially occupied by sodium, compared with the seven sites found in the RbCl complex of gramicidin. The sum of the partial occupancies of Na+ was only 1.26 per two dimers and was confirmed by the similar content of iodine ions (1.21 ions distributed over seven sites), which was easily visible from their anomalous signal. Another surprising observation was the significant asymmetry of the distributions and occupancies of cations in the gramicidin dimers, which was in contrast to those observed in the high-resolution structures of the complexes of heavier alkali metals with gramicidin D, especially that of rubidium. [source] Structural Evolvement of Heating Treatment of Mg/Al-LDH and Preparation of Mineral Mesoporous MaterialsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2006CHEN Tianhu Abstract, Although hydrotalcite, or layered double hydroxides (LDHs), is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/Al-LDH is evaluated by XRD, TEM and N2 -BET analyses. The results indicate that the magnesium-aluminum LDH with carbonate as interlayer anion, periclase-like oxides was formed at temperatures of 400,800°C. Meanwhile, 2,3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase-like formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of (Mg, Al)-oxide nano-crystals and nanopores among the nano-crystals. When heating temperature exceeds 1000, the periclase-like (Mg, Al)-oxide is transformed into a composite with periclase (MgO) and spinel phases. The periclase can be re-hydrolyzed and dissolved in HCI solution. After acid treatment, the sample with a high surface area is composed of spinel nano-crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition. [source] Vitamin D status in female patients with primary hyperparathyroidism: does it play a role in skeletal damage?CLINICAL ENDOCRINOLOGY, Issue 1 2004Vincenzo Carnevale Summary objective, Vitamin D deficiency, even subclinical, has been considered to worsen the skeletal damage in primary hyperparathyroidism (PHPT). Our study aimed to investigate the impact of vitamin D status on skeletal involvement in PHPT. design and measurements, A cross-sectional study was designed involving 62 female patients with PHPT. Serum total calcium (tCa), phosphate (P), creatinine (Cr) and total alkaline phosphatase activity (AP), together with 24-h (uCa 24 h) and spot fasting (uCa/Cr) urinary calcium, were measured by autoanalyser; ionized calcium (iCa) was assessed by an ion-specific electrode; intact parathyroid hormone (PTH) was measured by immunoradiometric assay (IRMA) and 25-hydroxyvitamin D (25-OHD) by radioimmunoassay (RIA). Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at lumbar spine in 58 patients, and at femoral neck, Ward's triangle, greater trochanter, intertrochanteric line and total hip in 56 patients. The associations of all variables with age, 25-OHD, body mass index (BMI) and PTH were studied by linear multiple regression analysis, using progressively restricted models. results, The model including age, 25-OHD, PTH and BMI showed significant regression with BMD values. PTH, age and BMI exerted a leading role in determining such a significance, while no significant regression was found between the parameters studied and 25-OHD; this was confirmed by Pearson's linear correlation analysis. The progressively restricted models showed significant regression of BMD at femoral neck, femoral intertrochanteric line and total hip with age, BMI and PTH. BMD measured at the Ward's triangle and greater trochanter showed significant regression with age and BMI, and that measured at lumbar spine with age. conclusions, Our data indicate that in primary hyperparathyroidism patients the influence of 25-hydroxyvitamin D levels on bone mineral density, if any, was overwhelmed by the effects of parathyroid hormone excess, age and body mass index. The latter unequally affected bone mineral density of various measured sites with different composition. [source] Characterization of gel grown iron-manganese-cobalt ternary levo-tartrate crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010S. J. Joshi Abstract In the present investigation, iron,manganese,cobalt ternary levo-tartrate crystals of different compositions have been grown by single-diffusion gel growth technique in silica hydrogel medium. The metallic composition in the crystals was estimated by EDAX. The coloration of the crystals changed with composition of metallic content. The powder XRD study suggested the crystalline nature and indicated the presence of some extra phases. The grown crystals were characterized by FT-IR spectroscopy, TGA, dielectric and Vibrating Sample Magnetometer (VSM) studies. The FT-IR study suggested the presence of O-H, C=O, C-O and metal-oxygen bonds. The effect of composition of metallic content was observed in certain absorption regions in FT-IR spectra. The thermal stability of the crystals was studied by thermogravimetry and the kinetic and thermodynamic parameters of dehydration were calculated. The effect of composition of ternary levo-tartrate was observed in dielectric study. The dielectric study was carried out in the frequency range of applied field from 500 Hz to 1 MHz. The variations in dielectric constant, dielectric loss, a.c. resistivity and a.c. conductivity with frequency of applied field were studied. VSM study suggested that all crystals were of paramagnetic nature. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparative Studies of Tridentate Sulfur and Nitrogen-Containing Ligands as Ionophores for Construction of Cadmium Ion-Selective Membrane SensorsELECTROANALYSIS, Issue 11 2007Ashok, Kumar Singh Abstract New polymeric membrane cadmium-ion selective sensors have been prepared by incorporating nitrogen and sulfur containing tridentate ligands as the ionophores into the plasticized PVC membranes. Poly(vinyl chloride) (PVC) based membranes of potassium hydrotris[N -(2,6-xylyl)thioimdazolyl) borate] (KTt2,6-xylyl) and potassium hydrotris(3-phenyl-5-methylpyrazolyl) borate (KTpPh,Me) with sodium tetraphenyl borate (NaTPB) as an anionic excluder and dibutylphthalate (DBP), tributylphthalate (TBP), dioctylsebacate (DOS), and o -nitrophenyloctyl ether (o -NPOE) as plasticizing solvent mediators were investigated in different compositions. KTt2,6-xylyl was found to be a selective and sensitive ion carrier for Cd(II) membrane sensor. A membrane composed of KTt2,6-xylyl:NaTPB:PVC:DBP with the % mole ratio 2.3,:,1.1,:,34.8,:,61.8 (w/w) works well over a very wide concentration range (7.8×10,8,1.0×10,2,M) with a Nernstian slope of 29.4±0.2,mV/decades of activity between pH values of 3.5 to 9.0 with a detection limit of 4.37×10,8,M. The sensor displays very good discrimination toward Cd(II) ions with regard to most common cations. The proposed sensor shows a short response time for whole concentration range (ca. 8,s). The effects of the cationic (tetrabutylammonium chloride, TBC), anionic (sodium dodecyl sulfate, SDS) and nonionic (Triton X-100) surfactants were investigated on the potentiometric properties of proposed cadmium-selective sensor. The proposed sensor based on KTt2,6-xylyl ionophore has also been used for the direct determination of cadmium ions in different water samples and human urine samples. [source] Volatile organic compounds: a potential direct long-distance mechanism for antagonistic action of Fusarium oxysporum strain MSA 35ENVIRONMENTAL MICROBIOLOGY, Issue 4 2009Daniela Minerdi Summary Fusarium oxysporum MSA 35 [wild-type (WT) strain] is an antagonistic Fusarium that lives in association with a consortium of bacteria belonging to the genera Serratia, Achromobacter, Bacillus and Stenotrophomonas in an Italian soil suppressive to Fusarium wilt. Typing experiments and virulence tests provided evidence that the F. oxysporum isolate when cured of the bacterial symbionts [the cured (CU) form], is pathogenic, causing wilt symptoms identical to those caused by F. oxysporum f. sp. lactucae. Here, we demonstrate that small volatile organic compounds (VOCs) emitted from the WT strain negatively influence the mycelial growth of different formae speciales of F. oxysporum. Furthermore, these VOCs repress gene expression of two putative virulence genes in F. oxysporum lactucae strain Fuslat10, a fungus against which the WT strain MSA 35 has antagonistic activity. The VOC profile of the WT and CU fungus shows different compositions. Sesquiterpenes, mainly caryophyllene, were present in the headspace only of WT MSA 35. No sesquiterpenes were found in the volatiles of ectosymbiotic Serratia sp. strain DM1 and Achromobacter sp. strain MM1. Bacterial volatiles had no effects on the growth of the different ff. spp. of F. oxysporum examined. Hyphae grown with VOC from WT F. oxysporum f. sp. lactucae strain MSA 35 were hydrophobic whereas those grown without VOCs were not, suggesting a correlation between the presence of volatiles in the atmosphere and the phenotype of the mycelium. This is the first report of VOC production by antagonistic F. oxysporum MSA 35 and their effects on pathogenic F. oxysporum. The results obtained in this work led us to propose a new potential direct long-distance mechanism for antagonism by F. oxysporum MSA 35 mediated by VOCs. Antagonism could be the consequence of both reduction of pathogen mycelial growth and inhibition of pathogen virulence gene expression. [source] FEM-Simulation of Real and Artificial Microstructures of Mo-Si-B Alloys for Elastic Properties and Comparison with Analytical Methods,ADVANCED ENGINEERING MATERIALS, Issue 10 2007G. Biragoni Various three phase microstructures of Mo-Si-B alloys were simulated in tensile loading conditions using a 2D finite element method to predict the elastic properties of the composite material. Voronoi structures with the same areal fraction of phases as the real microstructures have been generated and simulated similarly. Also, with these Voronoi structures a variation of grain or phase sizes, respectively, was carried out for different compositions in order to study on the elastic properties of the composite. Finally, a comparison was made over the whole temperature range between the above numerical methods, classical analytical approaches and experimentally determined values for Young's modulus E, shear modulus G and Poisson's ratio ,. [source] Physico-chemical requirements for cellular uptake of pAntp peptideFEBS JOURNAL, Issue 5 2001Role of lipid-binding affinity The pAntp peptide, corresponding to the third helix of the Antennapedia homeodomain, is internalized by a receptor-independent process into eucaryotic cells. The precise mechanism of entry remains unclear but the interaction between the phospholipids of plasma membrane and pAntp is probably involved in the translocation process. In order to define the role of peptide,lipid interaction in this mechanism and the physico-chemical properties that are necessary for an efficient cellular uptake, we have carried out an Ala-Scan mapping. The peptides were labeled with a fluorescent group (7-nitrobenz-2-oxo-1,3-diazol-4-yl-; NBD) and their cell association was measured by flow cytometry. Furthermore, we determined the fraction of internalized peptide by using a dithionite treatment. Comparison between cell association and cell uptake suggests that the affinity of pAntp for the plasma membrane is required for the import process. To further investigate which are the physico-chemical requirements for phospholipid-binding of pAntp, we have determined the surface partition coefficient of peptides by titrating them with phospholipid vesicles having different compositions. In addition, we estimated by circular dichroism the conformation adopted by these peptides in a membrane-mimetic environment. We show that the phospholipid binding of pAntp depends on its helical amphipathicity, especially when the negative surface charge density of phospholipid vesicles is low. The cell uptake of pAntp, related to lipid-binding affinity, requires a minimal hydrophobicity and net charge. As pAntp does not seem to translocate through an artificial phospholipid bilayer, this might indicate that it could interact with other cell surface components or enters into cells by a nonelucidated biological mechanism. [source] Combinatorial Search for Quaternary Methanol Tolerant Oxygen Electro-Reduction CatalystFUEL CELLS, Issue 1 2010M. K. Jeon Abstract A combinatorial library containing 645 different compositions was synthesised and characterised for methanol tolerant oxygen electro-reduction reaction (ORR) catalytic performance. The library was composed of compositions involving between 1 and 4 metals among Pt, Ru, Fe, Mo and Se. In an optical screening test, Pt(50)Ru(10)Fe(20)Se(10) composition exhibited the highest ORR activity in the presence of methanol. This composition was further investigated by synthesis and characterisation of a powder version catalyst [Pt(50)Ru(10)Fe(20)Se(10)/C]. At 0.85,V [vs. reversible hydrogen electrode (RHE)] in the absence of methanol, the Pt/C catalyst exhibited higher ORR current (0.0990,mA) than the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst (0.0902,mA). But much higher specific activity (12.7 ,A cmpt,2) was observed in the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst than for the Pt/C catalyst 6.51 ,A cmpt,2). In the presence of methanol, the ORR current decreased by 0.0343 and 0.247,mA for the Pt(50)Ru(10)Fe(20)Se(10)/C and Pt/C catalysts, respectively, which proved the excellent methanol tolerance of the Pt(50)Ru(10)Fe(20)Se(10)/C catalyst. [source] | |||||||||||||||||||||||||||||||||||||