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Batch supercritical antisolvent precipitation (SAS) process was used to coprecipitate Cefuroxime Axetil amorphous (CFA, antibiotic) and Polyvinylpyrrolidone (PVP-K30) for preparing drug-polymer composite particles. Solutions of CFA and PVP-K30 in methanol with overall concentrations of 50-150 mg/ml and polymer/drug ratios of 1/1-4/1 were sprayed into the CO2 at 70-200 bar and 35-50 °C with drug + polymer solution injection rates of 0.85 and 2.5 ml/min. Spherical particles having mean diameters of 1.88-3.97 μm, distribution ranges of 0.82-9.7 μm (the narrowest distribution) and 0.91-46.64 μm (the broadest distribution) were obtained. Mean particle size was not affected significantly with the change of process parameters. It was only affected by pressure change. On the other hand particle size distribution was affected by pressure, temperature, drug + polymer solution injection rate and concentration. It was observed that temperature and polymer/drug ratio affected the particle morphology most. The drug release rate of SAS-coprecipitated CFA-PVP (1/1) particles was almost 10 times slower than the drug alone. As the ratio of the polymer increased drug release rate also increased due to the wetting effect of PVP. 相似文献
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Zeki Karaca Nimet ÖztankMehmedi Vehbi Gökçe Hakan Elçi 《Cold Regions Science and Technology》2011,68(3):124-129
This work studies the influences of both surface-finishing forms and cement-filling on the durability of dimension limestone in cold regions. Freeze-thaw cycles, aqueous saline solution and their interactions with surface-finishing forms and cement-filling on stones were investigated for two types of porous limestone, Caribbean and Pewter Blend. Both deionised water and saline water composed of 20% NaCl by weight were used, and 28 freeze-thaw cycles were applied to the samples. The change in dry weight, porosity, and Böhme abrasion loss value was obtained for all test samples. It was observed that two types of porous limestone with cement-filling and different types of surface-finishing were influenced to different extents by freeze-thaw and salt. Experiments showed that stones to be used outdoors in cold regions should have relatively low initial porosity and that they should be fine-finished and cement-filled; these modifications to the stones will maximise the benefit received from the stones. 相似文献
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Required routine monitoring of endocrine disrupting compounds (EDCs) in water samples, as posed by EPA Unregulated Contaminant Regulation (UCMR3), demands for cost-effective, reliable and sensitive EDC detection methods. This study reports a reusable evanescent wave aptamer-based biosensor for rapid, sensitive and highly selective detection of 17β-estradiol, an EDC that is frequently detected in environmental water samples. In this system, the capture molecular, β-estradiol 6-(O-carboxy-methyl)oxime-BSA, was covalently immobilized onto the optical fiber sensor surface. With an indirect competitive detection mode, samples containing different concentrations of 17β-estradiol were premixed with a given concentration of fluorescence-labeled DNA aptamer, which highly specifically binds to 17β-estradiol. Then, the sample mixture is pumped to the sensor surface, and a higher concentration of 17β-estradiol leads to less fluorescence-labeled DNA aptamer bound to the sensor surface and thus to lower fluorescence signal. The dose-response curve of 17β-estradiol was established and a detection limit was determined as 2.1 nM (0.6 ng mL(-1)). The high specificity and selectivity of the sensor were demonstrated by evaluating its response to a number of potentially interfering EDCs. Potential interference of real environmental sample matrix was assessed by spiked samples in several tertiary wastewater effluents. The sensor can be regenerated with a 0.5% SDS solution (pH 1.9) over tens of times without significant deterioration of the sensor performance. This portable sensor system can be potentially applied for on-site real-time inexpensive and easy-to-use monitoring of 17β-estradiol in environmental samples such as effluents or water bodies. 相似文献
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Mohammed Saleh Didem Demir Yasin Ozay Mutlu Yalvac Nimet Bolgen Nadir Dizge 《应用聚合物科学杂志》2021,138(25):50599
In this study, a novel basalt embedded fiber membranes was prepared by the electrospinning method. The effects of the feed rate, voltage, tip to collector distance, and the basalt content on the prepared composite fiber membranes were investigated and optimized using the response surface method. Four models were built to compare the fibers in terms of deionized water flux (DWF), activated sludge flux, chemical oxygen demand (COD) removal, and porosity of fiber membranes. All the developed models were significant and adequately precise. The maximum flux of DWF was obtained when the voltage was 17.25 kV, the tip to collector distance of 19 cm, and a basalt content in polymer of 1.25%. COD removal decreased at higher voltage values as the feed rate increased. The porosity, pore size, and the contact angle values decreased for basalt embedded fiber membrane. The increases in the basalt percentage in polymer increased the hydrophilicity of the fiber. The flux decline for the basalt embedded fiber membrane was compared with the pristine fiber membrane. The permeate fluxes of pristine and basalt embedded fiber membranes were 42.3 and 59.6 L/m2/h, respectively. The biofouling performances of pristine and basalt embedded fiber membranes were also examined. Irreversible fouling decreased from 42.9% to 8.0%, and reversible fouling increased from 56.5% to 91.1% after modification of the membrane with basalt powder. Scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDX) analysis showed that basalt powder was successfully embedded into polyether sulfone polymer. 相似文献
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Neural Processing Letters - In general, the equivalent amplitude values and the specific phase differences between the oscillators/neurons are desired to obtain the smooth movements in the CPG... 相似文献
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Diospyros lotus fruit polyphenol oxidase was purified using affinity chromatography, resulting in a 15-fold enrichment in specific activity. The purified enzyme, having 16.5 kDa molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, exhibited the highest activity toward 4-methylcatechol. Maximum diphenolase activity was reached at pH 7.0 and 60°C in the presence of 4-methylcatechol. Km and Vmax values were calculated as 3.8 mM and 1250 U/mg protein, respectively. Ascorbic acid was a promising inhibitor with an IC50 value of 0.121 µM. The activity of the purified enzyme was stimulated by Fe2+, Sr2+, Zn2+, and K+ and deeply inhibited by Hg2+, at 1 mM final concentration. Aqueous extract of Diospyros lotus L. fruit showed strong substantial urease and acetylcholinesterase inhibition, with IC50 values of 1.55 ± 0.05 and 16.75 ± 0.11 mg/mL, respectively. 相似文献
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Belkz Bilgin Eran Arif Nesrullajev Nimet Ylmaz Canl 《Materials Chemistry and Physics》2008,111(2-3):555-558
Synthesis, characterization and investigation of the mesogenic, thermo-morphologic and thermotropic properties of a new chiral liquid crystalline compound are presented in this work. This new compound has prolate molecules and exhibits the chiral smectic C* mesophase in a sufficiently large temperature interval. Two types of solid crystalline phases have been found in this compound. Typical textures and temperatures of the direct and reverse phase transitions, taking place in the compound, are given. Typical peculiarities for the first-order transition between the smectic C* mesophase and isotropic liquid have been observed. 相似文献
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Neda Shah Hosseini Nimet Bölgen Nabyl Khenoussi Şakir Necat Yılmaz Derya Yetkin Amir Houshang Hekmati 《国际聚合物材料杂志》2018,67(3):143-150
Electrospinning is significantly one of the simple and versatile methods for producing micro- and nanofibrous scaffolds. Its assembly can be modified in different ways to combine material properties with different morphological structures for biomedical applications. In this process, collector design plays an important role to determine the nanofiber orientation in electrospun nanoweb. In this work, 3D patterned scaffolds were produced by electrospinning of polyamide-66 solution on different 3D collectors that have been obtained. The aim of this work is to investigate the attachment of the chondrocyte cells on the prepared electrospun scaffolds that have different types of nanofiber orientations that could be used in tissue engineering applications. 相似文献