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Rui P. Queirós Daniel Rainho Mauro D. Santos Liliana G. Fidalgo Ivonne Delgadillo 《高压研究》2015,35(1):69-77
This study evaluated high pressure processing (P1 – 400?MPa/5?min; P2 – 550?MPa/2?min) and thermal pasteurization (TP – 70°C/30?s) effects on sweet cherry juice's microbiological and physicochemical parameters, during four weeks of refrigerated storage. All treatments reduced the microbiological load to undetectable levels not affecting total soluble solids and titratable acidity. The pH increased with all treatments, however, it decreased during storage. Phenols were differently affected: TP increased them by 6%, P1 had no effect while P2 decreased them by 11%. During storage, phenols in control and TP samples decreased by 26% and 20%, P1 samples decreased them by 11% whereas P2 showed no variation. TP had no effect on anthocyanins, while pressure treatments increased them by 8%. Anthocyanins decreased during storage, particularly in the control and P1 (decreasing 41%). All treatments had no effect on antioxidant activity until the 14th day, thereafter high pressure processing samples showed the highest antioxidant activity. 相似文献
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Paulo J. Amorim Madeira Ana Raquel Fernandes Sitoe Daniel Gonçalves Tiago Rodrigues Rita C. Guedes Francisca Lopes Rui Moreira M. Rosário Bronze 《Journal of the American Society for Mass Spectrometry》2014,25(9):1650-1661
The gas-phase behavior of 12 quinolon-4(1H)-imine derivatives with antiplasmodial activity was investigated using electrospray ionization tandem mass spectrometry together with collision induced dissociation and density functional theory (DFT) calculations. The most probable protonation site was predicted by calculating the proton affinity (PA) values for each possible protonation site and it was found to be the imine nitrogen for all compounds under study. Fragmentation pathways of the protonated molecules were proposed and the assignment of product ion structures was performed taking into account theoretical calculations. The nature of the quinoline substituent was found to influence the gas-phase behavior of the compounds under study. The data acquired allowed to bracket the proton affinity of the quinolin-4-imine scaffold, which can be a useful starting point to choose appropriate references for determining PA values of this scaffold. Figure
? 相似文献
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HF:H2O2:H2O solution (40%wt.HF: 30wt.%H2O2: H2O, 3:2:1 by volume) was used to reveal extended defects (line, face and volume defects) in bulk ZnTe crystals grown from Te solution. The etch patterns were analyzed based on their size, shape and distribution. The etch figures, both in the shape of pits and hillocks with high resolution, show forms controlled by the symmetries of the respective faces were produced. Two different sizes of pits were observed, the larger‐size pits correspond to dislocations penetrating the surface, however, the smaller‐size texture pits are produced on the defect‐free region, which serve as standard pits on respect faces. The face defects, such as grain boundaries, sub‐grain boundaries, dislocation walls, twins and stacking faults, can be all displayed clearly. Another essential feature of the etchant is that, it can effectively dissolve Te‐rich phase (Te inclusion/precipitates), which makes it promising to reveal the shape of this volume defect. 相似文献
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以天然高岭土为载体、利用化学共沉淀法成功地制备出纳米Fe3O4/高岭土复合粉体。采用XRD、FSEM对复合粉体的物相组成、粒径、显微结构、形貌进行了表征,并研究了其磁分离性能和对亚甲基蓝(MB)的吸附性能。结果显示,复合粉体中的铁氧化物呈单一的Fe3O4相,Fe3O4晶粒的尺寸为10~30 nm,且均匀负载于高岭石晶体表面。当Fe3O4、高岭土质量比为1∶5时,复合粉体的磁分离率高达90.12%,并具有良好的吸附性能。复合粉体对MB的去除率随着吸附时间的延长、吸附温度的升高、溶液p H的增大和投入量的增加而逐步提高,随着MB溶液初始浓度的增大而逐步减小;对MB的吸附量随初始浓度的增大而逐步增大。 相似文献
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Unusual Acetylation‐Dependent Reaction Cascade in the Biosynthesis of the Pyrroloindole Drug Physostigmine 下载免费PDF全文
Joyce Liu Tailun Ng Dr. Zhe Rui Omer Ad Prof. Dr. Wenjun Zhang 《Angewandte Chemie (International ed. in English)》2014,53(1):136-139
Physostigmine is a parasympathomimetic drug used to treat a variety of neurological disorders, including Alzheimer’s disease and glaucoma. Because of its potent biological activity and unique pyrroloindole skeleton, physostigmine has been the target of many organic syntheses. However, the biosynthesis of physostigmine has been relatively understudied. In this study, we identified a biosynthetic gene cluster for physostigmine by genome mining. The 8.5 kb gene cluster encodes eight proteins (PsmA–H), seven of which are required for the synthesis of physostigmine from 5‐hydroxytryptophan, as shown by in vitro total reconstitution. Further genetic and enzymatic studies enabled us to delineate the biosynthetic pathway for physostigmine. The pathway features an unusual reaction cascade consisting of highly coordinated methylation and acetylation/deacetylation reactions. 相似文献