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排序方式: 共有683条查询结果,搜索用时 15 毫秒
31.
Gagan Kumar Ritu Rani Sucheta Sharma Khalid M. Batoo M. Singh 《Ceramics International》2013,39(5):4813-4818
Cobalt substituted Mg–Mn nanoferrites with formulae Mg0.9Mn0.1CoxFe2?xO4, x=0.0, 0.1, 0.2 and 0.3, have been synthesized for the first time by the solution combustion technique. The effects of Co2+ ions on the dc resistivity, dielectric constant and dielectric loss tangent of Mg–Mn nanoferrites at room temperature are presented in this paper. X-ray diffraction confirmed the formation of a single phase spinel structure. Particle size was found to increase, 20.9–23.9 nm, with increasing Co2+ concentration. The dc resistivity was increased by two order of magnitude with substitution of Co2+ ions while the dielectric constant was found to be decreasing with the increasing concentration of cobalt ions. The value of dc resistivity obtained for Mg0.9Mn0.1Fe2O4 nanoferrite in our work is greater than the value obtained for the same composition prepared by the conventional ceramic technique. Further, the dielectric constant and dielectric loss tangent were observed to be decreasing with the increase in frequency. 相似文献
32.
Epoxidized linolenic acid salts as multifunctional additives for the thermal stability of plasticized PVC
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Fiaz S. Mohammed Mark Conley Steven R. Saunders Jackson Switzer Rani Jha Jeffrey M. Cogen Bharat I. Chaudhary Pamela Pollet Charles A. Eckert Charles L. Liotta 《应用聚合物科学杂志》2015,132(13)
Calcium and zinc salts of epoxidized linolenic acid were synthesized and used as multifunctional additives, to minimize or prevent the reaction of epoxidized soybean oil (ESO) with liberated hydrochloric acid (HCl) during the thermal degradation of poly(vinyl chloride) (PVC) in particular. These metal epoxy salts were incorporated as thermal stabilizers for both diisodecyl phthalate and ESO–plasticized PVC blends that underwent thermal degradation studies at 170°C. The overall performance of these metal epoxy salts was examined by thermal gravimetric analysis and visual color retention of the PVC blends. The weight loss profiles of the metal salt stabilized PVC were comparable to those of blends containing metal stearates. There were, however, vast improvements in color retention of the plasticized PVC using these novel additives. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41736. 相似文献
33.
Yew Joon Tam Morvarid Akhavan Rezaei Mohd Lila Mohd Azmi Abdul Rani Bahaman Sewn Cen Lo 《分离科学与技术》2016,51(5):816-829
Univariate screening on factors affecting the purification performance of recombinant hepatitis B surface antigen (HBsAg) on ion exchange chromatography (IEC) and size exclusion chromatography (SEC) and the establishment of a two-step purification strategy were performed. Amongst four IEC adsorbents examined, the use of Q Sepharose XL IEC adsorbent under optimized conditions together with optimized SEC purification was able to efficiently purify HBsAg. An established purification strategy comprising the two techniques further demonstrated adaptability for scale-up operations with a final total purification factor (PF) of 94.82 ± 16.20, HBsAg purity of 95.48% and recovery yield of 78.07%. 相似文献
34.
Rathika G. Suba V. Lakshmi D. Shanthana Rani Roopala 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(8):3153-3169
Journal of Inorganic and Organometallic Polymers and Materials - In recent decades, the analysis of nanoparticles is of greater importance for their applications in various fields. This present... 相似文献
35.
Nursiati Mohamad Taridi Nazirah Abd Rani Azian Abd Latiff Wan Zurinah Wan Ngah Musalmah Mazlan 《Lipids》2014,49(9):855-869
Little is known about the effect of vitamin E on brain function. Therefore, in this study we evaluated the effect of tocotrienol rich fraction (TRF) on behavioral impairment and oxidative stress in aged rats. Thirty-six male Wistar rats (young: 3-months-old; aged: 21-months-old) were treated with either the control (olive oil) or TRF (200 mg/kg) for 3 months. Behavioral studies were performed using the open field test and Morris water maze (MWM) task. Blood was taken for assessment of DNA damage, plasma malondialdehyde (MDA) and vitamin E, and erythrocyte antioxidant enzyme activity. Brains were also collected to measure vitamin E levels. Results showed that aged rats exhibited reduced exploratory activity, enhanced anxiety and decreased spatial learning and memory compared with young rats. DNA damage and plasma MDA were increased, and vitamin E levels in plasma and brain were reduced in aged rats. Aged rats supplemented with TRF showed a markedly reduced level of anxiety, improved spatial learning and memory, reduced amount and severity of DNA damage, a reduced level of MDA, and increased levels of antioxidant enzyme activity and plasma/brain vitamin E compared with age-matched controls. In conclusion, TRF supplementation reverses spatial learning and memory decline and decreases oxidative stress in aged rats. 相似文献
36.
The research reported in this paper is concerned with gaining a better understanding of human factors issues in machining and the automation of manufacturing tasks. Mismatches between operators' performance and the requirements of machining tasks were experimentally studied with respect to the relationships with various human characteristics, including skill, age, work experience, self-confidence and trust. Twelve hypotheses concerning interrelationships between these characteristics were evaluated and important relationships established. It is considered that this increased knowledge of the rate of mismatches and an understanding of the causes is essential for the successful design of new working environments, machines and tasks. Much of this change to the working environment is likely to involve some degree of automation of the operators' tasks and so a second and important aspect of the study was designed to establish the extent to which preferred levels of automation were related to the same human characteristics. Four further hypotheses relating preferred levels of automation to skill, age, work experience, self-confidence and trust were tested with results that, in some cases, were unexpected and in others contradict the findings of previous research. 相似文献
37.
Sachin D. Kore P. P. Date S. V. Kulkarni Satendra Kumar Dolly Rani M. R. Kulkarni S. V. Desai R. K. Rajawat K. V. Nagesh D. P. Chakravarty 《The International Journal of Advanced Manufacturing Technology》2011,54(9-12):949-955
The ability to manufacture a product using different metal combinations greatly increases flexibility in design and production. Joining of dissimilar metal combinations like Copper-to-Stainless Steel (Cu-to-SS) is, however, a challenging task owing to the large differences in physical and chemical properties. The application of electromagnetic (EM) impact technique is demonstrated for welding copper (Cu) to stainless steel (SS) sheets. The welding Cu-to-SS is accomplished by using Al drivers to accelerate Cu and SS work sheets. The tensile shear strength test and the metallographic studies are carried out for Cu-to-SS EM welds. 相似文献
38.
39.
Studies on the growth and stability of silver nanoparticles synthesized by electron beam irradiation
Manjunatha Pattabi Rani M. Pattabi Ganesh Sanjeev 《Journal of Materials Science: Materials in Electronics》2009,20(12):1233-1238
Stable Ag nanoparticles have been synthesized by irradiating an aqueous solution of AgNO3 and Poly-vinyl alcohol (PVA) with 8 MeV electrons from a Microtron. The rate of formation of nanoparticles could be controlled by changing either the irradiation dosage or the relative concentration of the precursors. The size, shape, and the rate of formation of the nanoparticles depend on the final dosage, as well as the weight ratio of AgNO3 and PVA. The formation of Ag nanoparticles and their size were established through UV–Vis spectroscopy and Transmission electron microscopy (TEM) analysis, respectively. Increasing the irradiation dosage seem to favour the formation of polygonal nanostructures. Differential scanning calorimetry (DSC) measurements show that there exists a strong interaction between the PVA matrix and the Ag nanoparticles. 相似文献
40.
Suman Rani Neetu Ahlawat R. Punia Kanta Maan Sangwan Sunita Rani 《Ceramics International》2018,44(6):5996-6001
In this work, Sr and Zn co-doped calcium copper titanate having nominal formula Ca0.90Sr0.10Cu3Ti3.95Zn0.05O12 has been synthesized and systematically studied for structure, dielectric and electrical properties. The phase purity of the prepared composition has been confirmed by X-ray diffraction (XRD) pattern and various structural parameters are presented here with Rietveld refinement data. The Scanning electron microscopy (SEM) image revealed the presence of homogeneous fine-grained microstructure investigated in the prepared ceramic. The impedance data well fitted with 2 R-CPE model confirmed the non-ideality of the system. Dielectric studies have shown the existence of two relaxation processes in low and high frequency domains. Low frequency dielectric response proposed as a combination of Maxwell-Wagner relaxation and intrinsic defect (Vo++) while high frequency behavior has been interpreted in terms of polaronic relaxation caused by hopping process of an electron between Ti3+ and Ti4+ states. The frequency dependent behavior of conductivity has been well fitted to Dong’s model and interpreted in term of Overlapping Large Polaron Tunneling (OLPT) mechanism. The various parameters; relaxation angular frequency (ω1) of Debye process, ionic hopping frequency (ω2), dc conductivity (σo), cole- cole parameter (α) and frequency exponent (s) have been determined by Dong’s Model fitting. 相似文献