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Different Chemical Composition (different + chemical_composition)
Selected AbstractsGenomic variants of TLR1 , It takes (TLR-)two to tangoEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2007Abstract Toll-like receptors (TLR) are innate immune sensors of microbial cell wall products that initiate early host responses. The TLR2 receptor complex has been shown to contain heterodimers of TLR2 with either TLR1 or TLR6 enabling the host to detect different microbial molecules, such as lipopeptides of different chemical composition. In this issue of the European Journal of Immunology, an important role in the sensing of microbial products for I602S, a single nucleotide polymorphism (SNP) in human TLR1 has been identified. This result, in combination with another recently published report on this polymorphism elucidating a functional role in cell trafficking (surface expression of the receptor complex in individuals carrying the SNP was altered), provide genetic evidence affirming the important function of TLR1 as an essential co-receptor for TLR2. See accompanying article: http://dx.doi.org/10.1002/eji200737034 [source] Soil chemistry versus environmental controls on production of CH4 and CO2 in northern peatlandsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2005J. B. Yavitt Summary Rates of organic carbon mineralization (to CO2 and CH4) vary widely in peat soil. We transplanted four peat soils with different chemical composition into six sites with different environmental conditions to help resolve the debate about control of organic carbon mineralization by resource availability (e.g. carbon and nutrient chemistry) versus environmental conditions (e.g. temperature, moisture, pH). The four peat soils were derived from Sphagnum (bog moss). Two transplant sites were in mid-boreal Alberta, Canada, two were in low-boreal Ontario, Canada, and two were in the temperate United States. After 3 years in the field, CH4 production varied significantly as a function of peat type, transplant site, and the type,site interaction. All four peat soils had very small rates of CH4 production (< 20 nmol g,1 day,1) after transplant into two sites, presumably caused by acid site conditions (pH < 4.0). One peat soil had small CH4 production rates regardless of transplant site. A canonical discriminant analysis revealed that large rates of CH4 production (4000 nmol g,1 day,1) correlated with large holocellulose content, a large concentration of p -hydroxyl phenolic compounds in the Klason lignin, and small concentrations of N, Ca and Mn in peat. Significant variation in rates of CO2 production correlated positively with holocellulose content and negatively with N concentrations, regardless of transplant site. The temperature response for CO2 production varied as a function of climate, being greater for peat formed in a cold climate, but did not apply to transplanted peat. Although we succeeded in elucidating some aspects of peat chemistry controlling production of CH4 and CO2 in Sphagnum -derived peat soils, we also revealed idiosyncratic combinations of peat chemistry and site conditions that will complicate forecasting rates of peat carbon mineralization into the future. [source] Microstructural investigation of low-dose neutron irradiation effects in martensitic steels for nuclear application by means of small-angle neutron scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Rainer Lindau The microstructural effect of low-dose neutron irradiation and subsequent high-temperature tempering in the reduced activation ferritic/martensitic steel F82H-mod. (7.73 Cr, 0.09 C, 0.08 Mn, 0.19 V, 2.06 W, 0.02 Ta, wt%, bal. Fe) has been studied using small-angle neutron scattering (SANS). The investigated samples were irradiated with thermal neutrons at 523,K, to dose levels of 2.4 displacements per atom then tempered for 2,h at 1043,K. The SANS measurements were carried out at the D22 instrument of the High Flux Reactor at the Institut Max von Laue,Paul Langevin, Grenoble, France. The differences observed in nuclear and magnetic small-angle neutron scattering cross-sections after subtraction of the reference sample from the irradiated one suggest that the irradiation and the subsequent post-irradiation tempering produce the growth of non-magnetic precipitates; the results are also compared with those obtained on other ferritic/martensitic steels, with different chemical composition, irradiated under the same conditions. [source] RHEOLOGY AND TEXTURE OF SET YOGURT AS AFFECTED BY INULIN ADDITIONJOURNAL OF TEXTURE STUDIES, Issue 6 2008TATDAO PASEEPHOL ABSTRACT The effect of inulin addition on rheology and texture of nonfat yogurt (NFY) was studied by the large (texture analyzer) and small (dynamic oscillatory rheometry) deformation tests. Skim milks (12% solids) were supplemented with three commercial chicory inulins with different chain lengths at 4% level and inoculated with mixed cultures of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. Textural and rheological tests were conducted after an overnight storage at 4C and during a shelf life of 28 days. A good correlation was observed between the two tests. During storage, all inulin-containing yogurts in comparison with the control NFY were characterized by lower values of firmness, apparent viscosity, yield stress, complex viscosity, storage modulus and loss modulus. NFYs supplemented with long-chain inulin demonstrated a rheological behavior closer to that of control full-fat yogurt. PRACTICAL APPLICATIONS The use of inulin and oligofructose in the food industry has grown recently because of their interesting nutritional and technological properties. In the work presented here, three commercial inulin products with different chemical composition and functions were added to yogurt milk, and changes in rheological properties of yogurt were investigated in comparison with nonsupplemented control yogurts. According to the manufacturer's specifications, Raftiline HP and Raftiline GR are suitable for fat replacement because of the presence of long-chain inulins, while Raftilose P95, being rich in mono- and disaccharides, is highly recommended for sugar replacement. The knowledge obtained from this study may be applied for the development of nonfat yogurts to satisfy the nutritional expectations of ever-increasing health conscious consumers and at the same time to match the sensory and textural characteristics of full-fat yogurt. [source] An easy non-invasive X-ray diffraction method to determine the composition of Na-pyroxenes from high-density `greenstone' implementsACTA CRYSTALLOGRAPHICA SECTION A, Issue 1 2008Roberto Giustetto A large number of polished stone implements from Palaeolithic to Bronze Age sites of Northern Italy and Southern France are made of high-pressure (HP) metamorphic rocks (eclogite and related rocks), mainly consisting of Na-pyroxene (jadeite to omphacite) from the metamorphic belt of the Western Alps. The standard archaeometric study of prehistoric stone implements follows a procedure that is invasive, expensive and time-consuming. Since Na-pyroxenes may show a large compositional range, a thorough study of the variations affecting the dhkl values, obtained by X-ray diffraction, of three selected reflections as a function of different chemical composition was carried out, in order to determine the chemistry of Na-pyroxene isomorphic mixtures and roughly evaluate their relative amounts. These reflections (21, 310, 002) are sharp, intense and sensitive to the variation of pyroxene chemical composition. Using such dhkl values measured on pyroxenes of known chemistry, a Ca-pyroxene(Di),jadeite(Jd),aegirine(Ae) compositional diagram was constructed, from which the composition of an unknown pyroxene can be estimated within an error of about 5%. When the size of the object is relatively small and a flat polished surface is present, the proposed analytical procedure becomes totally non-invasive. The data obtained shed light on the provenance sources of such implements and the prehistoric trade routes. [source] The plug-based nanovolume Microcapillary Protein Crystallization System (MPCS)ACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2008Cory J. Gerdts The Microcapillary Protein Crystallization System (MPCS) embodies a new semi-automated plug-based crystallization technology which enables nanolitre-volume screening of crystallization conditions in a plasticware format that allows crystals to be easily removed for traditional cryoprotection and X-ray diffraction data collection. Protein crystals grown in these plastic devices can be directly subjected to in situ X-ray diffraction studies. The MPCS integrates the formulation of crystallization cocktails with the preparation of the crystallization experiments. Within microfluidic Teflon tubing or the microfluidic circuitry of a plastic CrystalCard, ,10,20,nl volume droplets are generated, each representing a microbatch-style crystallization experiment with a different chemical composition. The entire protein sample is utilized in crystallization experiments. Sparse-matrix screening and chemical gradient screening can be combined in one comprehensive `hybrid' crystallization trial. The technology lends itself well to optimization by high-granularity gradient screening using optimization reagents such as precipitation agents, ligands or cryoprotectants. [source] Impact of Kerogen Heterogeneity on Sorption of Organic Pollutants.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2009Abstract The overall goal of the present study was to establish correlations between organic pollutant sorption and physicochemical properties of kerogen materials. Three coal samples, each representing a typical kerogen type, were used as the starting materials. A thermal technique was employed to treat the kerogen materials under seven different temperatures ranging from 200 to 500C to simulate different diagenetic history. These samples were systematically characterized for their chemical compositions, functionalities, physical rigidity, and optical properties. The results showed that the chemical, spectroscopic, and optical microscopic properties of each kerogen series changed consistently as a function of treatment temperature or kerogen maturation. The oxygen-to-carbon atomic ratio decreased from 0.29, 0.12, and 0.07 for the original lignite (XF0), fusinite (HZ0), and lopinite (LP0) samples, respectively, to 0.07, 0.06, and 0.04 for XF7, HZ7, and LP7, respectively, that underwent the highest temperature treatment. The hydrogen-to-carbon atomic ratio exhibited similar reducing trend, which is consistent with the aromaticity increasing from 45 to 58% of the original samples to 76 to 81% of highly mature samples. Under the fluorescence microscope, the organic matrix changed from yellow (original lignite sample) and red-brown (original lopinite sample) to colorless for the samples of higher maturation. The measured reflecting index increased from the original samples to the highly mature samples. Moreover, the original and the slightly matured samples exhibited very different chemical compositions and structural units among the three types due to the difference in their source materials. As the kerogen maturation increased, such differences decreased, indicating highly mature kerogen became homogenized regardless of the source material. [source] Synthesis and rheological characterization of graft copolymers of butyl and hydroxyethyl methacrylates on starchesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Mariló Gurruchaga Abstract To study the possibility of using some acrylic-grafted polysaccharides as matrix tablets, graft copolymers of butyl methacrylate and hydroxyethyl methacrylate on starch and on hydroxypropyl starch were synthesized. In this work, the effects of the different chemical compositions of the various synthesized graft copolymers on the hydrophilicity and rheological characteristics were examined. Water absorption values that ranged from 5 to 45% were obtained. Rheological testing determined with dispersions (5% w/w) in water showed that the graft copolymers formed weak gels of high viscosity. Moreover, the synthesized powders showed good flow and good compaction. These measurements pointed toward the possibility of their application for drug release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Coordination-Driven Hierarchical Organization of ,-Conjugated Systems: From Molecular to Supramolecular ,-Stacked AssembliesCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2010Yishan Yao Dr. Abstract The reaction of U-shaped, bimetallic, CuI complexes, assembled from a heteroditopic pincer, with cyano-capped ,-conjugated linkers gives a straightforward access to ,-stacked metallocyclophanes in good yields. In these assemblies, the ,-walls have an almost face-to-face arrangement. The versatility of this rational supramolecular synthesis is demonstrated with the use of linkers that have nanoscale lengths (up to 27.7,Å), different chemical compositions (oligo(para -phenylenevinylene)s OPVs, oligo(phenylene)s, oligo(phenylethynylene)s), and alternative geometries (linear, angular). Linkers that incorporate an internal pyridyne moiety can also be employed. X-ray diffraction studies revealed that the metallocyclophanes based on linear linkers self-organize into infinite ,-stacked columns in the solid state with intermolecular distances of about 3.6,Å. This approach, based on coordination-driven self-assembly, provides a novel and rational strategy for the stacking of extended ,-systems in the solid state. [source] | ||||||||||