Home About us Contact
|
Home About us Contact | ||
|
|
||
Main Peaks (main + peak)
Selected AbstractsTrace metal distribution in soluble organic matter from municipal solid waste compost determined by size-exclusion chromatographyENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2002Arno Kaschl Abstract Municipal solid waste (MSW) composts carry high amounts of trace metals and organic complexing agents that may influence metal bioavailability and mobility after application to soils. In order to assess the degree of organic complexation of trace metals in the solution phase of MSW compost and the relevance of organic ligand type, size exclusion chromatography (SEC) was applied to compost-extracted organic ligands. Adjustment of the elution conditions minimized the interaction with the gel matrix for compost humic substances and dissolved organic matter (DOM) fractions. The SEC was then used to separate the aqueous compost extract into samples with distinct differences in chemical constituents. The highest quantities of Cu, Zn, Ni, Mn, and Cd were found to coelute with the main peak of the SEC elution curve, which, as observed by Fourier-transformed infrared (FTIR) spectroscopy, also had the highest density of carboxyl groups. The ratio of aromatic to aliphatic structures was higher for eluates with low retention times, and cations such as Al, Cr, and Fe were preferably associated with these larger organic molecules. All trace metals in the compost solution phase were bound mostly to DOM rather than forming inorganic complexes. [source] Processing, properties and stability of biodegradable composites based on Mater-Bi® and cellulose fibresPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2003D. Puglia Abstract In this work, the behaviour of biocomposites obtained by the addition of flax cellulose pulp to Mater-Bi®, a commercial thermoplastic matrix based on starch, has been studied in comparison with traditional glass fibre composites. The composites were produced by compounding with a twin-screw extruder. Depending on the kind of fibre, reinforcement contents of 10,40% were obtained. The mechanical behaviour, both in normal conditions and after water absorption, was analysed. It has been noted that the addition of cellulose pulp increases the composite modulus more than glass fibre: in fact, a poor adhesion of the interface between the glass fibre and Mater-Bi® has been observed. The thermal degradation behaviour of the composite has been studied by thermogravimetric analysis (TGA). Different degradation peaks have been observed and the activation energies, related to the main peak, have been calculated. The addition of cellulose pulp produces better mechanical properties and higher thermal stability. Copyright © 2003 John Wiley & Sons, Ltd. [source] Correcting electron-density resolution bias in reciprocal spaceACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2009Angela Altomare Fourier syntheses are always affected by series-termination errors, which generate sets of positive and negative ripples around each main peak in the map. The interaction among the ripples distorts the profile of the map and moves peaks away from their correct positions. In a previous paper [Altomare et al. (2008). Acta Cryst. A64, 326,336] an algorithm was described which reduces the resolution bias by removing the effects of the ripples in direct space. In this paper the correction is performed in reciprocal space: the effect of the ripples on the atomic scattering factors is calculated and subtracted from the usual atomic scattering factors. The modified scattering factors are used to calculate new structure factors, from which more accurate electron-density maps may be obtained. The experimental tests show that the procedure minimizes the effects of the resolution bias and provides atomic positions that are more accurate than those provided by traditional approaches. [source] Extraction, purification and characterization of wax from flax (Linum usitatissimum) strawEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2009Yasantha Athukorala Abstract The chemical composition and selected physical parameters of wax extracted from flax straw with supercritical CO2 (SC-CO2) and hexane have been determined. From the GC/MS results, clear variations in composition and component distributions were observed between SC-CO2 - and hexane-extracted samples. The major components of the SC-CO2 and hexane extracts from three flax cultivars were: fatty acids (36,49%), fatty alcohols (20,26%), aldehydes (10,14%), wax esters (5,12%), sterols (7,9%) and alkanes (4,5%). Purification of SC-CO2 -extracted wax with silica gel chromatography yielded 0.4,0.5% (dry matter) and was composed primarily of wax esters (C44, C46 and C48) and alkanes (C27, C29 and C31). UV-Vis scans of the purified wax samples exhibited two main peaks indicating the presence of conjugated dienes and carotenoids or related compounds. Fourier transform infrared results showed prominent peaks at 2918 (-C-H), 2849 (-C-H), 1745 (-C=O), 1462 (-C-H), 1169 (-C-O) and 719,cm,1 (-(CH2)n -), with NorLin wax showing a slightly deviating pattern compared to the other samples. Thermal analysis by differential scanning calorimetry revealed a mean melting point of 55,56,°C and oxidation temperatures of 146,153,°C for purified wax from flax straw processed using different procedures. [source] STUDY OF CONFORMATIONAL CHANGES OF EWE'S HOLO (NATIVE) AND APO-,-LACTALBUMIN BY SPECTROSCOPY AND TRYPSINOLYSISJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2006JEAN-MARC CHOBERT ABSTRACT Conformational changes of ewe's ,-lactalbumin (ALA) upon removal of Ca2+ were determined by surface hydrophobicity, calorimetry and circular dichroism. Native ewe's ALA resisted trypsinolysis, showing 4% maximum degradation after 20 h of hydrolysis. Removal of bound calcium by addition of either ethylenediaminetetraacetic acid or ethylene glycol bis ,-aminoethyl ether-N,N,N,N-tetraacetic acid induced major protein conformational changes, enhancing its susceptibility to trypsinolysis, and leading to complete degradation of the protein. Reversed-phase high-performance liquid chromatography profiles of tryptic hydrolysate of Ca2+ -free ALA were nearly the same through the whole enzymatic incubation period (24 h) showing the absence of sequential hydrolytic mechanism. They were characterized by the presence of five main peaks representing hydrophobic large-sized peptides. Cleaving the S-S bonds in the resulting hydrolysates with 2-mercaptoethanol gave rise to new peaks representing more hydrophilic and hydrophobic peptides. [source] Changes in the pectic fraction of bush butter (Dacryodes edulis (G Don) HJ Lam) fruit pulp during ripeningJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001Crépin Ella Missang Abstract CDTA-soluble polysaccharides were extracted from cell wall material (prepared as alcohol-insoluble solids) of bush butter fruit endocarp tissue at three stages of ripeness. The amount of soluble pectins remained constant but they underwent a gradual depolymerisation during ripening. The CDTA extracts were fractionated by anion exchange and the subfractions were analysed for their sugar composition and molecular weight distribution. For all degrees of ripeness the extracts were composed of three minor peaks and two major peaks. The minor peaks appeared to be composed of xyloglucan and mannan-type polymers for the first peak and arabinogalactan-type polymers for the other two peaks. The two main peaks were retained on the column. The first was exclusively composed of homogalacturonan polymers and the second contained principally highly branched rhamnogalacturonan polymers. During ripening, both homogalacturonan and rhamnogalacturonan populations were modified. Modifications in the rhamnogalacturonan fraction were principally marked by the accumulation of low-molecular-weight rhamnoglacturonan polymers in the course of ripening. © 2001 Society of Chemical Industry [source] Characterization of reduced iso-,-acids derived from hops (Humulus lupulus) by NMRMAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2003Lars I. Nord Abstract Reduced forms of iso-,-acids (isohumulones), used in modern beer brewing were separated and characterized by 1H and 13C NMR spectroscopy. Components from mixtures of rho-iso-,-acids, tetrahydro-iso-,-acids, and hexahydro-iso-,-acids were isolated using high-performance liquid chromatography (HPLC) and analyzed by use of one- and two-dimensional NMR experiments. The data presented assign the identities of the main peaks in the HPLC traces for the reduced iso-,-acids. Previous tentative assignments regarding the cis and trans configurations and the structures of the acyl residues of the reduced iso-,-acids were confirmed and extensive NMR assignments were made. Furthermore, the previously unknown stereochemistry in the C-4 side-chain of the rho- and hexahydro-iso-,-acids was assigned. Copyright © 2003 John Wiley & Sons, Ltd. [source] Neural damage due to temporal lobe epilepsy: Dual-nuclei (proton and phosphorus) magnetic resonance spectroscopy studyPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 1 2004TAKAYUKI OBATA md Abstract, The aim of this study was to evaluate the usefulness of proton and phosphorus (1H and 31P) magnetic resonance spectroscopy (MRS) for temporal lobe epilepsy (TLE) patients, and to evaluate neural damage and metabolite dysfunction in the TLE patient brain. We performed 1H and 31P MRS of medial temporal lobes (MTL) in the same TLE patients (n = 14) with a relatively wide range of severity from almost seizure-free to intractable, and calculated the ratio of N-acetylasparate to choline-containing compounds and creatine + phosphocreatine (NAA/Cho + Cr) in 1H MRS and inorganic phosphate to all main peaks (%Pi) in 31P MRS. There was no significant correlation between NAA/(Cho + Cr) and %Pi ,in ,each ,side ,(ipsilateral, ,r = ,0.20; ,contralateral, ,r =,0.19). The values of NAA/(Cho + Cr) showed a significant difference between ipsilateral and contralateral MTLs to the focus of TLE patients (P < 0.01, paired t -test). Although %Pi also had a tendency to show the laterality of TLE, there was no significance. Ipsilateral (r = ,0.90, P < 0.0001) and contralateral (r = ,0.70, P < 0.005) NAA/(Cho + Cr) decreases and contralateral %Pi increase (r = 0.81, P < 0.001) had significant correlation with seizure frequency. 1H MRS provides more important information concerning neuronal dysfunction in MTL of TLE patients than 31P MRS. [source] Diffractive CIE 1931 chromaticity diagramCOLOR RESEARCH & APPLICATION, Issue 5 2007Joni Orava Abstract A novel diffractive CIE 1931 chromaticity diagram is generated by utilizing surface relief gratings on a plastic sample. A properly illuminated sample is shown to reflect the CIE chromaticity diagram with exact colors and large gamut. Additive color mixing is accomplished by utilizing the four main peaks of a 4000 K fluorescent lamp's spectrum as the primary colors. The primary grating units are reflecting the combination of the primary colors to the desired viewing angle and thereby forming the correct chromaticity (x, y) at each pixel of chromaticity diagram. Weights of primary colors at each pixel of the diagram are controlled by fixing the relative areas of the primary gratings. The master grating is fabricated with aid of electron beam lithography. The final grating is hot embossed on a polycarbonate sample using an electroplated nickel shim. Chromaticity values are measured from the plastic sample by a spectroradiometer. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 409,413, 2007 [source] | |||||||||||||