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排序方式: 共有196条查询结果,搜索用时 15 毫秒
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İbrahim Kivrak Mehmet Emin Duru Mehmet Öztürk Nazime Mercan Mansur Harmandar Gülaçtı Topçu 《Food chemistry》2009
The essential oil of Salvia potentillifolia was analysed by GC and GC–MS. Totally, 123 components were detected in both hydrodistilled and steam-distilled oils, α- and β-pinenes being major compounds. The antioxidant activities were determined by using complementary tests, namely, DPPH radical-scavenging, β-carotene-linoleic acid and reducing power assays. The ethanol extract also showed better activity (IC50 = 69.4 ± 0.99 μg/ml) than that of BHT in the DPPH system, and showed great lipid peroxidation inhibition in the β-carotene-linoleic acid system (IC50 = 30.4 ± 0.50 μg/ml). The essential oil showed meaningful butyrylcholinesterase activity (65.7 ± 0.21%), and α-pinene showed high acetylcholinesterase inhibitory activity (IC50 = 86.2 ± 0.96 μM) while β-pinene was inactive. Antimicrobial activity was also investigated on several microorganisms, and the essential oil showed high activity against Bacillus subtilis and B. cereus. It also exhibited remarkable anticandidal activity against Candida albicans and C. tropicalis with MIC values of 18.5 and 15.5 μg/ml, respectively, while α- and β-pinenes showed moderate activity. 相似文献
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Maria Helena Santos Rafael M. Silva Vitor C. Dumont Juliana S. Neves Herman S. Mansur Luiz Guilherme D. Heneine 《Materials science & engineering. C, Materials for biological applications》2013,33(2):790-800
Bovine pericardium is widely used as a raw material in bioengineering as a source of collagen, a fundamental structural molecule. The physical, chemical, and biocompatibility characteristics of these natural fibers enable their broad use in several areas of the health sciences. For these applications, it is important to obtain collagen of the highest possible purity. The lack of a method to produce these pure biocompatible materials using simple and economically feasible techniques presents a major challenge to their production on an industrial scale. This study aimed to extract, purify, and characterize the type I collagen protein originating from bovine pericardium, considered to be an abundant tissue resource. The pericardium tissue was collected from male animals at slaughter age. Pieces of bovine pericardium were enzymatically digested, followed by a novel protocol developed for protein purification using ion-exchange chromatography. The material was extensively characterized by electrophoresis, scanning electron microscopy, energy dispersive X-ray spectroscopy, and infrared spectroscopy. The results showed a purified material with morphological properties and chemical functionalities compatible with type I collagen and similar to a highly purified commercial collagen. Thus, an innovative and relatively simple processing method was developed to extract and purify type I collagen from bovine tissue with potential applications as a biomaterial for regenerative tissue engineering. 相似文献
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Hasan Yildirim Mansur Sümer Veysel Akyüncü Emrah Gürbüz 《Construction and Building Materials》2011,25(6):2939-2947
Fly ashes are obtained from thermal power plants and they are pozzolanic materials, which can act as partial replacement material for both portland cement and fine aggregate. With their economical advantages and potential for improving fresh and hardened concrete performance, they have some benefits for using in concrete industry. In this study, the objective was to find the efficiency factors of Turkish C and F-type fly ashes and to compare their properties. Three different cement dosages were used (260, 320, 400 kg/m3), two different ratios (10% and 17%) of cement reduced from the control concretes and three different ratios (depending on cement reduction ratio) of fly ash were added into the mixtures. At the ages of 28 and 90 days, compressive strength, modulus of elasticity and ultrasound velocity tests were carried out. From the compressive strength results, the k efficiency factors of C and F-type fly ashes were obtained. As a result, it is seen that efficiency factors of the concrete produced by the replacement of F and C type fly ashes with cement increase with the increase in cement dosage and concrete age. 相似文献
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Investigation on the effect of spinning conditions on the properties of hollow fiber membrane for hemodialysis application 下载免费PDF全文
Sumarni Mansur Mohd Hafiz Dzarfan Othman A. F. Ismail Siti Hamimah Sheikh Abdul Kadir Fatmawati Kamal Pei Sean Goh Hasrinah Hasbullah Bee Cheer Ng Mohd Sohaimi Abdullah 《应用聚合物科学杂志》2016,133(30)
Polyethersulfone (PES) hollow fiber membranes were fabricated via the dry‐wet phase inversion spinning technique, aiming to produce an asymmetric, micro porous ultrafiltration hollow‐fiber specifically for hemodialysis membrane. The objective of this study is to investigate the effect of spinning conditions on the morphological and permeation properties of the fabricated membrane. Among the parameters that were studied in this work are air gap distance, dope extrusion rate, bore fluid flow rate, and the take‐up speed. The contact angle was measured to determine the hydrophilicity of the fibers. Membrane with sufficient hydrophilicity properties is desired for hemodialysis application to avoid fouling and increase its biocompatibility. The influences of the hollow fiber's morphology (i.e., diameter and wall thickness) on the performance of the membranes were evaluated by pure water flux and BSA rejection. The experimental results showed that the dope extrusion rate to bore fluid flow rate ratio should be maintained at 1:1 ratio to produce a perfectly rounded asymmetric hollow fiber membrane. Moreover, the flux of the hollow fiber spun at higher air gap distance had better flux than the one spun at lower air gap distance. Furthermore, spinning asymmetric hollow fiber membranes at high air gap distance helps to produce a thin and porous skin layer, leading to a better flux but a relatively low percentage of rejection for BSA separation. Findings from this study would serve as primary data which will be a useful guide for fabricating a high performance hemodialysis hollow fiber membrane. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43633. 相似文献
6.
Hélida V. P. Vieira Priscila F. Oliveira Josane A. Costa Leonardo A. de Oliveira Letícia S. Mota Claudia R. E. Mansur 《应用聚合物科学杂志》2021,138(44):51301
Partially hydrolyzed polyacrylamide (PHPA) is the most widely used polymer in enhanced oil recovery (EOR) applications. However, under conditions of high temperature and salinity, the PHPA molecules become hydrolyzed, causing a drastic reduction of the viscosity of the polymer solution due to the presence of negative charges, making the molecules more susceptible to interactions with cations. In this sense, in order to increase the stability of these polymers, an anionic monomer more resistant to cations such as 2-acrylamido-2-methylpropane sulfonic acid (AMPS) has been incorporated into the HPAM molecules. This work evaluated the thermal stability of a copolymer (acrylamide and AMPS - AN125) and a terpolymer (acrylamide, acrylate, and AMPS-FP5115) in the time course of 360 days. The tests were carried out in typical conditions of Brazilian offshore reservoirs, such as absence of oxygen, high temperature, and high salt concentration. The test method involved measurements of intrinsic viscosity in function of time and determination of the hydrolysis degree of the polymers by elemental analysis. The copolymer AN125 was more stable under the test conditions than the terpolymer FP 5115 due to the presence of a higher concentration of AMPS in the copolymer. The AMPS group was hydrolyzed to AA at a temperature of 100 °C, however, the increase in salt concentration delayed the onset of this degradation. The tests indicated that the presence of a higher AMPS content in the copolymer does not prevent the polymer from undergoing hydrolysis, but delays the polymer precipitation step in the solution. 相似文献
7.
Herman S. Mansur Carolina M. Sadahira Adriana N. Souza Alexandra A.P. Mansur 《Materials science & engineering. C, Materials for biological applications》2008,28(4):539-548
In this work, poly (vinyl alcohol) (PVA) hydrogels with different degree of hydrolysis (DH) were prepared by chemical crosslinking with glutaraldehyde (GA). The nanostructure of the resulting hydrogels was investigated by Fourier Transform Infrared Spectroscopy (FTIR) and Synchrotron small-angle X-ray scattering characterization (SAXS). In vitro tests were performed by swelling ratio assays in different pH solutions. The infrared spectra of the crosslinked PVA showed absorption bands of the acetal bridges resulted from the reaction of the GA with the OH groups from PVA. Also the FTIR spectroscopy was used to determine the crystallinity of the PVA film based on the relative intensity of the vibration band at 1141 cm− 1. The results have showed an increase of hydrogel crystallinity with higher DH of PVA. SAXS patterns have clearly indicated important modifications on the PVA semicrystalline structure when it was crosslinked by GA. The swelling ratio was significantly reduced by chemically crosslinking the PVA network. PVA-derived hydrogel with chemically modified network was found to be pH-sensitive, indicating a high potential to be used in drug delivery polymer system. 相似文献
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