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排序方式: 共有1043条查询结果,搜索用时 15 毫秒
41.
Geoffrey Lawrence Arun V Baskar Mohammed H El-Newehy Wang Soo Cha Salem S Al-Deyab Ajayan Vinu 《Science and Technology of Advanced Materials》2015,16(2)
Three-dimensional cage-like mesoporous FDU-12 materials with large tuneable pore sizes ranging from 9.9 to 15.6 nm were prepared by varying the synthesis temperature from 100 to 200 °C for the aging time of just 2 h using a tri-block copolymer F-127(EO106PO70EO106) as the surfactant and 1,3,5-trimethyl benzene as the swelling agent in an acidic condition. The mesoporous structure and textural features of FDU-12-HX (where H denotes the hydrothermal method and X denotes the synthesis temperature) samples were elucidated and probed using x-ray diffraction, N2 adsorption, 29Si magic angle spinning nuclear magnetic resonance, scanning electron microscopy and transmission electron microscopy. It has been demonstrated that the aging time can be significantly reduced from 72 to 2 h without affecting the structural order of the FDU-12 materials with a simple adjustment of the synthesis temperature from 100 to 200 °C. Among the materials prepared, the samples prepared at 200 °C had the highest pore volume and the largest pore diameter. Lysozyme adsorption experiments were conducted over FDU-12 samples prepared at different temperatures in order to understand their biomolecule adsorption capacity, where the FDU-12-HX samples displayed high adsorption performance of 29 μmol g−1 in spite of shortening the actual synthesis time from 72 to 2 h. Further, the influence of surface area, pore volume and pore diameter on the adsorption capacity of FDU-12-HX samples has been investigated and results are discussed in correlation with the textural parameters of the FDU-12-HX and other mesoporous adsorbents including SBA-15, MCM-41, KIT-5, KIT-6 and CMK-3. 相似文献
42.
A. F. Salem 《Journal of Superconductivity and Novel Magnetism》2014,27(12):2707-2711
We have used the AC susceptibility for MgAlB2 samples to investigate the grain boundary effects and the Al-doping effects on the critical current density. The Cole-Cole plots were used to obtain the grain boundary effects on the critical current density. We found that the grain boundaries are highly transparent to current flow and have virtually no effects on the critical current density in MgB2pure and Al-doped samples. Moreover, the lower critical field H c1 is found to be enhanced with Al doping. The highest H c1 value is achieved with the 4.5 % concentration of Al. 相似文献
43.
Intermittent drying may be of interest in the future to address energy issues. Such drying conditions are also likely to help stress relaxation through mechanosorptive creep. The influence of applying oscillations of temperature and relative humidity during the drying of beech timber on time and drying stresses is discussed in the paper by means of nonsymmetrical and loaded drying. Experimental data were used to validate a numerical model in the case of intermittent drying. The model was then used to perform a numerical investigation of the possibility of using an intermittent energy source to dry wood. 相似文献
44.
Christina Kopp Afshin Hosseini Shiva P. Singh Petra Regenhard Hamed Khalilvandi-Behroozyar Helga Sauerwein Manfred Mielenz 《International journal of molecular sciences》2014,15(11):21401-21418
The transition period in dairy cows (3 weeks prepartum until 3 weeks postpartum) is associated with substantial mobilization of energy stores, which is often associated with metabolic diseases. Nicotinic acid (NA) is an antilipolytic and lipid-lowering compound used to treat dyslipidaemia in humans, and it also reduces non-esterified fatty acids in cattle. In mice the G-protein coupled receptor 109A (GPR109A) ligand NA positively affects the secretion of adiponectin, an important modulator of glucose and fat metabolism. In cattle, the corresponding data linking NA to adiponectin are missing. Our objective was to examine the effects of NA on adiponectin and AMPK protein abundance and the expression of mRNAs of related genes such as chemerin, an adipokine that enhances adiponectin secretion in vitro. Differentiated bovine adipocytes were incubated with pertussis toxin (PTX) to verify the involvement of GPR signaling, and treated with 10 or 15 µM NA for 12 or 24 h. NA increased adiponectin concentrations (p ≤ 0.001) and the mRNA abundances of GPR109A (p ≤ 0.05) and chemerin (p ≤ 0.01). Pre-incubation with PTX reduced the adiponectin response to NA (p ≤ 0.001). The NA-stimulated secretion of adiponectin and the mRNA expression of chemerin in the bovine adipocytes were suggestive of GPR signaling-dependent improved insulin sensitivity and/or adipocyte metabolism in dairy cows. 相似文献
45.
Analytical and numerical assessments of local overpressure from hydrogen gas explosions in petrochemical plants 下载免费PDF全文
Boohyoung Bang Hyunsu Park Jonghun Kim Salem S. Al‐Deyab Alexander L. Yarin Sam S. Yoon 《火与材料》2017,41(6):587-597
Accurate prediction of pressure rise is important for safety assessments of a petrochemical plant in the event of an explosion accident. The sudden pressures arising from gas explosions at various hydrogen concentrations in air have been predicted analytically and numerically. These solutions were compared against experimental data. The analytical solution, based on the self‐similar solution for pointwise strong explosions in an open space, which assumed no energy loss and premixed fuel‐air mixture, reasonably predicted the explosive‐ignition detonation case while the numerical solutions were more suitable to model spark‐ignition deflagration cases that accounted for the effect of turbulence arising from three‐dimensionality and presence of obstacles in the computational domain. Comparison of both analytical and numerical results against experimental data indicates that their differences are within a 30% margin. The analytical model presented herein can be useful for field engineers who want conservative estimates of the overpressure resulting from explosive‐ignition detonation. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
46.
V. Shiva Sunil Goyal R. Sandhya K. Laha A. K. Bhaduri 《Transactions of the Indian Institute of Metals》2017,70(3):589-596
In this investigation, the flow behaviour of modified 9Cr–1Mo steel at elevated temperatures is reported. To understand the flow behaviour of the steel, tensile tests were performed at nominal strain rate of 3 × 10?3 s?1 and temperatures in the range of 300–823 K. The yield strength and ultimate tensile strength were found to decrease with increase in temperature with a plateau in a intermediate temperature regime (523–673 K). Serrations were also observed in the tensile curve at intermediate temperatures which caused plateau/peak in tensile behaviour of material and was a typical manifestation of dynamic strain ageing. An attempt was made to represent the flow behaviour of the material using different constitutive equations viz., Hollomon, Ludwik, Swift, Ludwigson and Voce. It was observed that the Voce equation could describe the experimental flow curve at different temperatures quite well. Instantaneous work hardening rate with respect to flow stress exhibited two stages of hardening especially at relatively lower temperatures. 相似文献
47.
48.
N. G. Shiva Prasad G. V. Ashok H. M. Mahesh 《The International journal of environmental studies》2013,70(1):83-92
Potable waters from various locations of the Bangalore environment were investigated for their 222Rn concentrations by the emanometry method. About 94 groundwater (borewell) samples were analysed for 222Rn concentrations and found to vary in the range 5.3–283.4 Bq L?1 with a mean value of 87 Bq L?1. Frequency distribution showed the 222Rn concentration in a large number of samples in the range of 0–50 Bq L?1. From the measured concentrations, the effective doses (lung and stomach) for the population of the region were estimated. The effective dose was found to vary from 42.6 to 2280.2 µSv y?1 with a mean value 702.5 µSv y?1. The effect of boiling of water showed a drastic reduction in the 222Rn concentration. The results of the present investigation are systematically analysed, compared with the literature values and discussed. 相似文献
49.
Freestanding fiber mats of zeolitic imidazolate framework 7 via one‐step,scalable electrospinning 下载免费PDF全文
Seongpil An Ji Sun Lee Bhavana N. Joshi Hong Seok Jo Kirill Titov Jong‐San Chang Chul‐Ho Jun Salem S. Al‐Deyab Young Kyu Hwang Jin‐Chong Tan Sam S. Yoon 《应用聚合物科学杂志》2016,133(32)
We demonstrated the fabrication of freestanding zeolitic imidazolate framework 7 (ZIF‐7) nanofiber (NF) mats by means of one‐step, scalable electrospinning. The formation of ZIF‐7 nanoparticles embedded in polymer fibers was unambiguously pinpointed via X‐ray diffraction, transmission electron microscopy, and adsorption studies. The NF mats exhibited excellent characteristics, with an average diameter of 245 nm, in the adsorption and desorption of carbon dioxide (CO2); this makes them attractive candidates for gas separation and other selective filtration applications. This excellent property of the ZIF‐7 mats was explained by the gate‐opening phenomenon of ZIF‐7, which yielded a stepwise increase in the overall CO2 uptake capacity. The mechanical strength of the NF mats was also obtained via large‐strain uniaxial tensile deformation, which enabled preliminary assessment of the mat's suitability for textiles and membranes in targeting separation and filtration applications with large‐area permeability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43788. 相似文献
50.
Musarat Amina Touseef Amna Mallick Shamshi Hassan Nawal Musayeib Al Musayeib Salem Slayyem Salem Al-Deyab Myung-Seob Khil 《Korean Journal of Chemical Engineering》2016,33(11):3169-3174
Pure water is the fundamental requisite for human life. The water has been recycled naturally but not in an adequate amount for consumption. Nanotechnology with extraordinary applications provides competent ways for the decontamination of contaminated water. In the present study MnWO4 nanoflowers endorsed with inherent antibacterial activity were successfully synthesized by facile hydrothermal approach. XRD, SEM, EDX spectroscopy and UVDRS were used to characterize the as-synthesized nanoflowers. Gram negative Escherichia coli ATCC 52922 bacterium was used as model organism to test antibacterial activity of as-synthesized MnWO4 nanoflowers. This study was conducted to optimize minimum concentration of MnWO4 nanoflowers and maximum contact time required to achieve complete inactivation of bacteria present in contaminated water. Minimum inhibitory concentration (MIC) of MnWO4 nanoflowers was found to be 10 μg/ml. The assessment and interpretation of bacterial viability was done using dual fluorescent staining. The synthesized 3D-nanoflowers were found as potent bactericides. Thus, MnWO4 nanoflowers emerged to be very good future material for disinfection of biological pollutants present in the contaminated water reservoirs and as an anti-biofouling agent. 相似文献