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91.
Ivan M. Mukisa Charles M.B.K. MuyanjaYusuf B. Byaruhanga Reidar B. SchüllerThor Langsrud Judith A. Narvhus 《Radiation Physics and Chemistry》2012,81(3):345-351
Malted and un-malted sorghum (Sorghum bicolor (L.) Moench) flour was gamma irradiated with a dose of 10 kGy and then re-irradiated with 25 kGy. The effects of irradiation on microbial decontamination, amylase activity, fermentability (using an amylolytic L. plantarum MNC 21 strain), starch granule structure and viscosity were determined. Standard methods were used during determinations. The 10 kGy dose had no effect on microbial load of un-malted flour but reduced that of malted flour by 3 log cycles. Re-irradiation resulted in complete decontamination. Irradiation of malt caused a significant (p<0.05) reduction in alpha and beta amylase activity (22% and 32%, respectively). Irradiation of un-malted flour increased the rates of utilization of glucose and maltose by 53% and 100%, respectively, during fermentation. However, microbial growth, rate of lactic acid production, final lactic acid concentration and pH were not affected. Starch granules appeared normal externally even after re-irradiation, however, granules ruptured and dissolved easily after hydration and gelatinization. Production of high dry matter density porridge (200 g dry matter/L) with a viscosity of 3500 cP was achieved by irradiation of un-malted flout at 10 kGy. Gamma irradiation can be used to decontaminate flours and could be utilized to produce weaning porridge from sorghum. 相似文献
92.
Victoria E. Campbell Xavier de Hatten Dr. Nicolas Delsuc Dr. Brice Kauffmann Dr. Ivan Huc Dr. Jonathan R. Nitschke Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(25):6138-6142
Systemic change : A system of transformations between helical structures was observed to be governed by interactions mediated by the electronic effects of substituents, entropic effects, the conformational preferences of organic building blocks, and the coordinative preferences of the metal ion. All of these effects were important, but all must be considered together to allow the prediction of the product observed (see scheme).
93.
Oleksii Zozulia Ivan V. Korendovych 《Angewandte Chemie (International ed. in English)》2020,59(21):8108-8112
The self‐assembly of short peptides gives rise to versatile nanoassemblies capable of promoting efficient catalysis. We have semi‐rationally designed a series of seven‐residue peptides that form hemin‐binding catalytic amyloids to facilitate enantioselective cyclopropanation with efficiencies that rival those of engineered hemin proteins. These results demonstrate that: 1) Catalytic amyloids can bind complex metallocofactors to promote practically important multisubstrate transformations. 2) Even essentially flat surfaces of amyloid assemblies can impart a substantial degree of enantioselectivity without the need for extensive optimization. 3) The ease of peptide preparation allows for straightforward incorporation of unnatural amino acids and the preparation of peptides made from d ‐amino acids with complete reversal of enantioselectivity. 相似文献
94.
Sayonara Maria Calado Gonçalves Glória Najara Silva Ivan da Rocha Pitta Moacyr Jesus Barreto de Melo Rêgo Simone Cristina Baggio Gnoato 《Natural product research》2020,34(12):1702-1711
AbstractBetulin (BE) is a pentacyclic triterpenes, obtained from natural sources and with several biological activities described, such as anti-tumoral and anti-inflammatory activities. The BE esterification at hydroxyl group (C-3 and C-28) resulted in five new ester derivatives with different numbers of carbons or halogens (chlorine and fluorine). Among these BE derivatives, two (2a e 2c) were able to significantly decrease IFN-g (*p?=?0.0391; **p?=?0.0156) and 2c modulated the expression of COX-2 better than Dexamethasone (DEXA). Regarding to cytotoxic assay, the best results were obtained for BE without modifications, with emphasis on tumoral cell lines Raji and MCF-7. The derivatives 2a and 2c showed immunomodulation activity (for the cytokines IFN-g). The presence of chorine in BE seems to be important for the ability of modulate COX-2 expression, since the ester chloride derivative 2c at 100?μM is more powerful inhibitor of COX-2 than DEXA. 相似文献
95.
96.
Nikica Šprem Ivan Babić Domagoj Barišić Delko Barišić 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(1):513-517
The aim of this study was to investigate 137Cs and 40K load in large mammal game species in the mountain forest region of Gorski Kotar in Croatia approximately a quarter of century after the Chernobyl accident. 137Cs and 40K activity were determined by the gamma-spectrometric method in 49 meat samples of five large game species: brown bear (Ursus arctos), wild boar (Sus scrofa), roe deer (Capreolus capreolus), red deer (Cervus elaphus), and chamois (Rupicapra rupicapra). The results indicated that herbivore game species (roe deer, red deer and chamois) show significantly lower 137Cs concentrations than omnivore species (brown bear, wild boar), thereby confirming the hypothesis that different dietary strategy impact caesium concentrations in meat. The measured caesium load in brown bear meat was in the range of two orders of magnitude, while caesium load in wild boar meat was found in the range of one order of magnitude. The estimated effective equivalent dose showed that uptake of the highest caesium doses would be from consumption of omnivore species meat, while much lower doses could be taken in with the consumption of meat from herbivore species. 相似文献
97.
The method is based on the oxidation of ethanol in the presence of alcohol oxidase, followed by oxidation of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonate) in the presence of peroxidase. 相似文献
98.
Jinhua Wang Dr. Barbara Wicher Dr. Victor Maurizot Prof. Ivan Huc 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):1031-1038
Quinoline based aromatic amide foldamers are known to adopt stable folded conformations. We have developed a synthetic approach to produce similar oligomers where all amide bonds, or part of them, have been replaced by an isosteric vinylene group. The results of solution and solid state structural studies show that oligomers exclusively containing vinylene linkages are not well folded, and adopt predominantly flat conformations. In contrast, a vinylene segment flanked by helical oligoamides also folds in a helix, albeit with a slightly lower curvature. The presence of vinylene functions also result in an extension of π-conjugation across the oligomer that may change charge transport properties. Altogether, these results pave the way to foldamers in which both structural control and specific electronic properties may be engineered. 相似文献
99.
Stíbr B Holub J Bakardjiev M Pavlík I Tok OL Císarová I Wrackmeyer B Herberhold M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(10):2239-2244
The reaction of nido-[7,8,9-PC(2)B(8)H(11)] (1) with [[CpFe(CO)(2)](2)] (Cp=eta(5)-C(5)H(5) (-)) in benzene (reflux, 3 days) gave an eta(1)-bonded complex [7-Fp-(eta(1)-nido-7,8,9,-PC(2)B(8)H(10))] (2; Fp=CpFe(CO)(2); yield 38 %). A similar reaction at elevated temperatures (xylene, reflux 24 h) gave the isomeric complex [7-Fp-(eta(1)-nido-7,9,10-PC(2)B(8)H(10))] (3; yield 28 %) together with the fully sandwiched complexes [1-Cp-closo-1,2,4,5-FePC(2)B(8)H(10)] 4 a (yield 30%) and [1-Cp-closo-1,2,4,8-FePC(2)B(8)H(10)] 4 b (yield 5%). Compounds 2 and 3 are isolable intermediates along the full eta(5)-complexation pathway of the phosphadicarbaborane cage; their heating (xylene, reflux, 24 h) leads finally to the isolation of compounds 4 a (yields 46 and 52%, respectively) and 4 b (yields 4 and 5%, respectively). Moreover, compound 3 is isolated as a side product from the heating of 2 (yield 10%). The structure of compound 4 a was determined by an X-ray structural analysis and the constitution of all compounds is consistent with the results of mass spectrometry and IR spectroscopy. Multinuclear ((1)H, (11)B, (31)P, and (13)C), two-dimensional [(11)B-(11)B]-COSY, and (1)H[(11)B(selective)] magnetic resonance measurements led to complete assignments of all resonances and are in excellent agreement with the structures proposed. 相似文献
100.
Electrical conductivity and elongation at break of epoxy filled with electroconductive carbon black, graphite or with silver-coated basalt particles or fibres were investigated in this paper. Percolation concentrations were determined to be 14 vol% for epoxy/carbon black composites, 22 vol% for epoxy/graphite composites, 28-29 vol% for both epoxy/silver-coated basalt particles and fibres. The steepest increase in electrical conductivity and the most pronounced decrease in elongation at break occurs at similar filler concentration range for all investigated systems. A good correlation between phenomenological model, introduced in [J. Mater. Sci. Lett. 18 (1998) 1457] and experimental data for all investigated systems was observed. 相似文献