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排序方式: 共有542条查询结果,搜索用时 15 毫秒
91.
92.
Mostafaie A Bidmeshkipour A Shirvani Z Mansouri K Chalabi M 《Applied biochemistry and biotechnology》2008,144(2):123-131
Actinidin is a cysteine protease abundant in Kiwifruit. This enzyme is known as a meat-tenderizing protease. In this project,
actinidin was purified from kiwifruit by salt precipitation and ion exchange chromatography. Collagenolytic effect of the
purified enzyme was tested in four different buffer systems. Thereafter, the enzyme was used for isolation and culture of
cells from three different tissues: endothelial cells from human umbilical vein, hepatocytes from rat liver, and thymic epithelial
cells from rat thymus. Our results revealed that actinidin can hydrolyze collagen types I and II at neutral and alkaline buffers.
Furthermore, actinidin compared with type II or IV collagenase isolated intact human umbilical vein endothelial cells, hepatocytes,
and thymic epithelial cells with viability more than 90%. These results address a novel and valuable collagenase, which can
be used efficiently for hydrolysis of collagen and isolation of different cell populations from various solid tissues. 相似文献
93.
The electrocatalytic oxidation of sulfite was investigated at carbon ionic liquid electrode (CILE). This electrode is a very good alternative to previously described electrodes because the electrocatalytic effect is achieved without any electrode modification. Comparative experiments were carried out using carbon paste electrode (CPE) and glassy carbon electrode (GCE). At CILE, highly reproducible and well-defined cyclic voltammograms were obtained for sulfite with a peak potential of 0.55 V vs. Ag/AgCl. Sulfite oxidation at CILE does not result in deactivation of the electrode surface. The kinetic parameters for this irreversible heterogeneous electron transfer process were determined. Under optimal experimental conditions, the peak current response increased linearly with sulfite concentration over the range of 6-1000 μM. The detection limit of the method was 4 μM. The method was applied to the determination of sulfite in mineral water, grape juice and non-alcoholic beer samples. 相似文献
94.
Milad Ghani Zahra Jafari Behrooz Maleki Maryam Chamani 《Journal of separation science》2023,46(2):2200745
Herein, polydopamine-coated Fe3O4 spheres were synthesized using a very simple, easy, cost-effective, efficient, and fast method. First, magnetic nanoparticles (Fe3O4) were synthesized and were followed by accommodating polydopamine on the surface of the prepared Fe3O4. The prepared polydopamine-coated Fe3O4 spheres were utilized as a sorbent in magnetic solid phase extraction of gemfibrozil and warfarin (as the model analytes). The extracted model analytes were desorbed by a suitable organic solvent and were analyzed by high-performance liquid chromatography. Under optimized condition, the linearity of the method was in the range of 0.1–200.0 μg/L for the selected analytes in water. The limits of detection were calculated to be in the range of 0.026–0.055 μg/L for warfarin and gemfibrozil, respectively. The limits of quantification were calculated to be in the range of 0.089–0.185 μg/L. The inter-day and intra-day relative standard deviations were determined to be in the range of 1.4%–3.3% in three concentrations in order to calculate the method precision. Furthermore, the enrichment factors were found to be 78 and 81 for warfarin and gemfibrozil, respectively. Moreover, the calculated absolute recoveries were between 78% and 81%. The obtained recoveries indicated that the method was useful and applicable in complicated real samples. 相似文献
95.
Reza Darvishi Cheshmeh Soltani Afshin Maleki Hatam Godini Mohammad Hassan Mahmoudian Mohammad Amin Pordel 《Journal of Dispersion Science and Technology》2016,37(5):723-732
The aim of the present investigation was to immobilize nanocrystalline diatomite within calcium alginate matrix for the adsorption of Direct Red23 (DR23) in aqueous media. Scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy were used to characterize the samples. As a result, the adsorption process obeyed pseudo-second-order kinetic model (R2 = 0.9934) and Langmuir isotherm model (R2 = 0.9732) with a maximum adsorption capacity of 24.10 mg/g. The value of mean free energy (15.81 kJ/mol) demonstrated that the process has been taken place chemically. As the adsorbent dosage increased from 0.5 to 3.0 g/L, the decolorization efficiency (%) increased from 26.0 to 75.5%, respectively. Inversely, the decolorization efficiency (%) decreased from 98.0 to 29.0% with increasing initial dye concentration from 5 to 160 mg/L, respectively. The negative values obtained for Gibbs free energy (ΔG°) and positive value of enthalpy change (ΔH°) indicated spontaneous and endothermic nature of the process. 相似文献
96.
On the Landau-Levich transition 总被引:1,自引:0,他引:1
Maleki M Reyssat E Quéré D Golestanian R 《Langmuir : the ACS journal of surfaces and colloids》2007,23(20):10116-10122
We discuss here the nature of the Landau-Levich transition, that is, the dynamical transition that occurs when drawing a solid out of a bath of a liquid that partially wets this solid. Above a threshold velocity, a film is entrained by the solid. We measure the macroscopic contact angle between the liquid and the solid by different methods, and conclude that this angle might be discontinuous at the transition. We also present a model to understand this fact and the shape of the meniscus as drawing the solid. 相似文献
97.
The ethyl acetate extract of an ISP-2 agar cultivation of the wasp nest-associated fungus Penicillium sp. CMB-MD14 exhibited promising antibacterial activity against vancomycin-resistant enterococci (VRE), with a bioassay guided chemical investigation yielding the new meroterpene, oxandrastin A (1), the first andrastin-like metabolite with an extra oxygenation at C-2. A culture media optimisation strategy informed a scaled-up rice cultivation that yielded 1, together with three new oxandrastins B–D (2–4), two known andrastins C (5) and F (6), and a new meroterpene of the austalide family, isoaustalide F (7). Structures of 1–7 were assigned based on detailed spectroscopic analysis and chemical interconversion. A GNPS molecular networking analysis of the rice cultivation extract detected the known austalides B (8), H (9), and H acid (10), tentatively identified based on molecular formulae and co-clustering with 7. That the anti-VRE properties of the CMB-MD14 extract were exclusively attributed to 1 (IC50 6.0 µM, MIC99 13.9 µM), highlights the importance of the 2-OAc and 3-OAc moieties to the oxandrastin anti-VRE pharmacophore. 相似文献
98.
Zeinab El Rashed Giulio Lupidi Elena Grasselli Laura Canesi Hala Khalifeh Ilaria Demori 《Molecules (Basel, Switzerland)》2021,26(15)
Fucoidan is a fucose-rich sulfated polysaccharide typically found in the cell wall of marine algae but also recently isolated from terrestrial sources. Due to a variety of biological activities, including antioxidant properties, fucoidan exhibits an attractive therapeutic potential against a wide array of metabolic diseases associated with oxidative stress. We used FTIR, 1H NMR and 13C NMR spectroscopy to investigate the structural features of a fucoidan fraction extracted from the brown alga Cystoseira compressa (CYS). The antioxidant potential of CYS was measured by DPPH, ABTS and FRAP assays, which revealed a radical scavenging capacity that was confirmed in in vitro cellular models of hepatic and endothelial cells. The same antioxidant effects were observed for another fucoidan fraction previously identified in the terrestrial tree Eucalyptus globulus (EUC). Moreover, in hepatic cells, CYS and EUC exhibited a significant antisteatotic action, being able to reduce intracellular triglyceride content through the regulation of key genes of hepatic lipid metabolism. EUC exerted stronger antioxidant and antisteatotic effects as compared to CYS, suggesting that both marine and terrestrial sources should be considered for fucoidan extraction and therapeutic applications. 相似文献
99.
Ramin Maleki Nasim Mohammad Nezhad Naser Samadi Khalil Farhadi 《Mikrochimica acta》2009,165(1-2):97-101
Dispersive liquid–liquid microextraction (DLLME) in conjunction with high-performance liquid chromatography-diode array detection (HPLC-DAD) has been applied to the extraction and determination of EDTA in sediments and water samples. The effect of extraction, nature and volume of disperser solvent, pH value of sample solution, extraction time and extraction temperature were investigated. Under the optimal conditions the analytical range of EDTA was from 3.0 to 50.0 μg L?1 with a correlation coefficient of 0.9982 and a detection limit of 1.7 μg L?1. The relative standard deviation (RSD) was less than 5.4% (n?=?5), and the recovery values were in the range of 89–95%. The simplicity, high enrichment, high recovery and good repeatability are the main advantages of the method presented. The DLLME-HPLC-DAD method was successfully applied to the analysis of EDTA in aqueous samples. 相似文献
100.
Silver nanoparticles (narrowly dispersed in diameter) were electrodeposited on carbon ionic liquid electrode (CILE) surface using a two‐step potentiostatic method. Potentiostatic double pulse technique was used as a suitable and simple method for controlling the size and morphologies of silver nanoparticles electrodeposited on CILE. The obtained silver nanoparticles deposited on CILE surface showed excellent electrocatalytic activity (low overpotential of ?0.35 V vs. Ag/AgCl) towards reduction of hydrogen peroxide. A linear dynamic range of 2–200 μM with an experimental detection limit of 0.7 μM (S/N=3) and reproducibility of 4.1% (n=5) make the constructed sensor suitable for peroxide determination in aqueous solutions. 相似文献