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211.
212.
Agar extraction process was developed for Gracilaria cliftonii by investigating the effects of various extraction variables and alkali treatments on agar yield and properties. The tested variables were soaking time, soaking temperature, seaweed to water ratio of, extraction temperatures and extraction time. Alkali treatments were carried out in alkali concentrations of 1%, 2%, 3% and 5% in a water bath at 60, 70 and 80 °C prior to agar extraction. The results showed that agar yield was significantly affected by all the tested variables. The agar yield was maximised when extraction process was carried out with 1 h soaking time at 30 °C with seaweed to water ratio of 1:150 and extracted for 3 h at 100 °C. The alkali-temperature combinations significantly influenced agar yield and properties. Irrespective of temperature, alkali treatments at 3% and 5% significantly increased the gel strength. 相似文献
213.
The structure of the crystalline addition product (1) formed between d-galactose and potassium bisulfite (potassium hydrogen sulfite) has been determined by X-ray diffraction analysis and compared with those structures reported for the related addition products from d-glucose and d-mannose. As with the latter two sulfonates, the d-galactose derived compound has an open-chain structure, with the carbon chain adopting a near planar zigzag conformation extending to the sulfur atom, similar to the d-mannose derivative but in contrast to the sickle conformation adopted by the d-glucose derivative. This last compound also differs in crystallising as a monohydrate. Inter-chain linking through cation coordination leads to a three dimensional network in the crystal. 相似文献
214.
215.
ERIC DONOIS VRONIQUE DEL MARMOL KAZUMASA WAKAMATSU SHOSUKE ITO GHANEM GHANEM JEAN-TIENNE SURLVE-BAZEILLE 《Pigment cell & melanoma research》1998,11(2):86-93
The aim of the study was to compare two methods quantifying eumelanins and pheomelanins, pigments synthesized by melanocytes. One is based on the high performance liquid chromatography (HPLC) quantitation of specific degradation products of each melanin type. The other requires image analysis, transmission election microscopy (TEM), and stereology. This study was carried out in cultured human melanoma cells and for each line, melanins were measured by HPLC and cells were fixed and embedded as pellets for TEM. Ultrathin sections were treated or not by the alkali elution method allowing the elimination of pheomelanins. The obtained micrographs were analyzed with our image analysis program permitting the estimation of several primary parameters. Stereology was used for estimating melanosomal maturation, intracellular melanins content, and number of melanized melanosomes per cell, for total melanin, eumelanins, or pheomelanins. Our results show a good correlation between both methods for total melanin, particularly when using the cytoplasmic volume density of melanin (r=0.93). Moreover, we report that the number of melanized melanosomes per cell and not the melanosomal maturation is responsible for the differences in total melanin content observed between the different cell lines. However, none of the stereological melanization parameters was correlated in the case of eumelanins or pheomelanins. In order to demonstrate the utter relevancy of this stereological approach, utilization of more pigmented melanoma cells, comparative study of HPLC and stereology, in normal epidermal melanocytes and a new evaluation of the alkali elution method in appropriate animal models would help us to explain the present results. 相似文献
216.
P. H. Janssen Alexandra Schuhmann F. Bak Werner Liesack 《Archives of microbiology》1996,166(3):184-192
A new strictly anaerobic, gram-negative bacterium was isolated from the sediment of a freshwater lake after enrichment with
thiosulfate as the energy source. The strain, named Bra2 (DSM 7269), is able to grow by disproportionation of thiosulfate
or sulfite to sulfate plus sulfide. Elemental sulfur is also disproportionated to sulfate and sulfide, but this only supports
growth if free sulfide is chemically removed from the culture, e.g., by precipitation with amorphous ferric hydroxide. Growth
is also possible by coupling the reduction of sulfate to sulfide with the oxidation of ethanol, propanol, or butanol to the
corresponding fatty acid. The cells are rod-shaped, motile, and have genomic DNA with a mol% G+C content of 50.7. Cytochromes
are present, but desulfoviridin is not. The new strain was shown to be related to, but distinct from members of the genus
Desulfobulbus on the basis of physiological characteristics and by comparative sequence analysis of its 16S rDNA. Strain Bra2 is described
as the type strain of a new taxon, Desulfocapsa thiozymogenes gen. nov., sp. nov.
Received: 29 January 1996 / Accepted: 31 May 1996 相似文献
217.
The effects of sulfide, sulfite and sulfate on the methanogenesis in an upflow anaerobic sludge blanket process indicated that their relative toxicity towards degradation of total volatile fatty acid varied as SO42–-S>SO32–-S>S2–. The anaerobic biogranules' activity decreased by 50% when each gram of biomass came into contact with 32, 24 and 16 mg of S2–, SO32–-S and SO42–-S, respectively. 相似文献
218.
219.
Aqueous suspensions of diesel soot particles in combination with sulfite influence certain functions of human polymorphonuclear neutrophils in vitro. Chemiluminescence, generated after activation by opsonized zymosan as well as oxygen uptake were decreased, whereas phagocytosis was increased. An enhancement of degranulation could not be observed. The single substances show little or no effects on the above properties. The results indicate that combinations of air pollutants such as diesel soot and sulfite may modulate vital functions of activated leukocytes in vivo. 相似文献
220.
This study looked at incorporation of iron(III) hexacyanoferrate onto chemically treated pine cone via iron(III) surface loading and its application for cesium (Cs) adsorption in the presence of alkali/alkali earth metals. The optimum iron(III) loading concentration was 2.50 mol l−1 at pH 7, while optimum hexacyanoferrate (HCF) loading was achieved at a hexacyanoferrate concentration of 0.26 mol l−1. The best-fitting kinetic model was confirmed using the closeness of the predicted equilibrium capacities to the experimentally determined capacity, three error determination methods, and the comparative plots of predictive and experimental uptake of Cs with time. The adsorption rate constants were reduced by alkali/alkali metal addition and the reduction was higher in the HCF-modified pine. The mechanism of Cs adsorption onto raw pine followed the pseudo-second-order model and involved stripping of the hydration water from the metal ion. The presence of Na+ did not alter the adsorption mechanism but Ca2+ addition changed the best-fitting model to pseudo-first-order. The diffusion-chemisorption model best fitted Cs adsorption onto HCF-modified pine and involved adsorption of Cs in its hydrated form, which migrated easily through the zeolite-like lattice of hexacyanoferrate. Addition of Na+ and Ca2+ changed the best-fitting model to a pseudo-first-order model. 相似文献