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排序方式: 共有250条查询结果,搜索用时 15 毫秒
81.
Sudheer Kumar Sushanta K. Samal Smita Mohanty Sanjay K. Nayak 《Polymer-Plastics Technology and Engineering》2018,57(3):133-155
Currently, the utilization of renewable resources for sustainable technology is in the renown of consumer as well as industrial attention, especially, chemical industries because of their availability, low cost, credentials toward environmental issues such as lower ecotoxicity, CO2 footprints, and inbuilt biodegradability. These natural properties are being taken advantage of in research and development, with vegetable oil-, furan-, lignin-, rosin-,vanillin-, and itaconic acid-derived biobased epoxy resin being used in various applications including paints, coatings, adhesives, and biomedicine. The present review mainly focuses on the utilization of natural resources for the synthesis of biobased epoxy and its curing agents. 相似文献
82.
An analytical model for bedload layer thickness 总被引:1,自引:0,他引:1
A theoretical study has been carried out to determine the thickness of the bedload layer in an open channel turbulent flow with non-cohesive sediment, which is very crucial in sediment transport problems as this is treated as saltation height of a sediment particle and the reference level in suspension studies. A new expression of viscous shear stress is proposed, which is a function of effective viscosity of sediment–fluid mixture, velocity gradient and volumetric concentration of sediment particles. During particle collisions, impact shear stress is generated, which is another important parameter near the sediment bed. By including both the shear stresses, an expression for the thickness of the bedload layer is developed. The predicted bedload layer thickness is a function of viscous coefficient, impact coefficient, particle diameter, relative mass density of sediment particle, maximum bed concentration and non-dimensional shear stress. It agrees reasonably well when compared with a wide class of experimental data under different hydraulic conditions. 相似文献
83.
Sushanta K. Badamali Rafael Luque James H. ClarkSimon W. Breeden 《Catalysis communications》2011,12(11):993-995
The microwave-assisted oxidative degradation of a lignin model phenolic dimer [1-(4-hydroxy-3-methoxyphenoxy)-2-(2-methoxyphenoxy)-propane-1,3-diol, 1] catalysed by Co(salen)/SBA-15 is reported. The investigated model compound 1 was prepared through a multistep synthesis and characterized by 1H,13C NMR, and GC–MS studies. The catalyst was prepared by immobilizing [N,N′-bis(salicylidene)ethane-1,2-diaminato]Cobalt(II), Co(salen) complex onto the periodic mesopore channels of siliceous SBA-15. The activity of the Co(salen)/SBA-15 was investigated in the oxidation of 1 in the presence of hydrogen peroxide as oxidant, both under microwave irradiation and conventional heating. The phenolic dimer was selectively oxidized to 2-methoxy phenol with very high TON under microwave activation conditions. Comparatively, reactions run under conventional heating led to oligomerisation of the dimer and resulted in a mixture of products. 相似文献
84.
Sushanta Kumar Panigrahi R. Jayaganthan 《Metallurgical and Materials Transactions A》2011,42(10):3208-3217
The effect of annealing on microstructural stability, precipitate evolution, and mechanical properties of cryorolled (CR)
Al 7075 alloy was investigated in the present work employing hardness measurements, tensile test, X-ray diffraction (XRD),
differential scanning calorimetry (DSC), electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM).
The solution-treated bulk Al 7075 alloy was subjected to cryorolling to produce fine grain structures and, subsequently, annealing
treatment to investigate its thermal stability. The recrystallization of CR Al 7075 alloys started at an annealing temperature
of 423 K (150 °C) and completed at an annealing temperature of 523 K (250 °C). The CR Al 7075 alloys with ultrafine-grained
microstructure are thermally stable up to 623 K (350 °C). Within the range of 523 K to 623 K (250 °C to 350 °C), the size
of small η phase particles and AlZr3 dispersoids lies within 300 nm. These small precipitate particles pin the grain boundaries due to the Zener pinning effect,
which suppresses grain growth. The hardness and tensile strength of the CR Al 7075 alloys was reduced during the annealing
treatment from 423 K to 523 K (150 °C to 250 °C) and subsequently it remains constant. 相似文献
85.
High strength age hardenable Al 7XXX series alloys are difficult to process by many of the severe plastic deformation processes at room temperature. The Al 7075 alloy has been processed at cryogenic temperature and room temperature up to different rolling strains, in the present work, with the objective of developing a processing strategy to obtain ultrafine grained microstructure with enhanced mechanical properties in the alloy. It has been identified that the Al 7075 alloy samples can be successfully cryorolled to higher strains (up to 3.4) if the reduction per pass is less than 0.3 mm, however it was found to be difficult to deform the samples at room temperature. A cryorolling strain of 3.4 has been found to be desirable for producing the ultrafine grained Al 7075 alloys with the high angle grain boundaries. However, the subgrains are not recrystallized up to this strain in the case of room temperature rolled Al alloys. The strength and hardness of the cryorolled Al 7075 alloy samples are higher than that of the room temperature rolled samples as observed in the present work. The improved strength and hardness of cryorolled samples are due to the grain size effect and higher dislocation density. The reduction in dimple size of cryorolled Al 7075 alloy upon failure confirms the grain refinement and strain hardening mechanism operating in the heavily deformed samples. 相似文献
86.
Electrochemical micromachining (EMM) is gaining importance day by day due its advantages that include no tool wear, absence of stress/burr, high MRR, bright surface finish and ability to machine complex shapes regardless of hardness. Overcut and taper formation is the main problem during micro borehole machining. In this paper, an electrical circuit model of EMM is presented for better understanding of the process and experimental MRR is found to be in good agreement with theoretical MRR. In the present set up variation of overcut with voltage, pulsed frequency, vibration amplitude of tool and vibration frequency of tool are investigated. To reduce overcut and taper angle of micro borehole, machining zone is simulated with a reversed taper tool and verified by practical experiments for proper shape control during micro borehole generation. Variation of micro nozzle angle with different feed rates and different times of machining are also investigated for the shape control during micromachining with conical tool. Finally, it has been shown that both reversed taper and forward taper tool can be used for generation of taper less micro features i.e. boreholes. 相似文献
87.
Paz Otero Sushanta Kumar Saha Azzam Hussein John Barron Patrick Murray 《Food Analytical Methods》2017,10(4):876-884
The present work describes the development and validation of a simple, quick and precise gas chromatography-mass spectrometry (GC-MS) method for the analysis of 23 azo dye breakdown products in paprika samples. After the extraction procedure, dyes were identified on an Agilent J&W DB-5ms Ultra Inert capillary column using dichloroethane as a sample dissolvent. Limits of detection (LODs) were comprised between 10.6 and 84.4 ng/mL. Accuracy values in the range of 90–104 % for the 23 azo dye breakdown products were obtained, and RSD% for the analysis of 2.4 μg/mL of each compound was below 4.6 % (n = 9). The recovery for the azo dyes in paprika samples was comprised between 71.2 ± 3.5 % (benzidine) and 118.9 ± 2.5 % (para-cresidine). Results of this study suggest that the developed method is suitable for detection and quantification of azo dye breakdown products in the range of 60–240 μg/kg paprika. In addition, this GC-MS method allowed the simultaneous determination of disperse orange 3 (azo dye) with high accuracy and precision. The method has numerous advantages such as simplicity, low cost, easy operation and short analysis time and constitutes an efficient method for the monitoring of a large number of azo dyes in food matrices. 相似文献
88.
Sanjay K. Chattopadhyay Sanjay Singh Nilay Pramanik U. K. Niyogi R. K. Khandal Ramagopal Uppaluri Aloke K. Ghoshal 《应用聚合物科学杂志》2011,121(4):2226-2232
Various composites of polypropylene (PP) produced using natural fibers such as pineapple leaf fiber, banana fiber, and bamboo fiber were studied for their degree and rate of aerobic biodegradation. Composites used contained 10, 15, and 50% volume fractions of pineapple leaf fiber, banana fiber, and bamboo fiber, respectively, which are the optimum fiber percentages of the respective composites as reported by these authors in their previous works. Cellulose has been used as positive reference material. All the composites exhibited partial biodegradation in the range of 5–15% depending on the fiber content. Degradation had not taken place in the covalent ester linkages between the natural fiber and the MA‐g‐PP compatibilizer but in those areas of the fibers which have remained only physically embedded in the resin matrix. Thus, although natural fibers reinforced PP composites are not excellent biodegradable material, they can address to the management of waste plastics by reducing the amount of polymer content used that in turn will reduce the generation of nonbiodegradable polymeric wastes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
89.
Policosanol, a well-defined mixture of very long chain primary alcohols that is available as a nutraceutical product, has
been reported to lower blood cholesterol levels. The present studies demonstrate that policosanol promotes the phosphorylation
of AMP-kinase and HMG-CoA reductase in hepatoma cells and in mouse liver after intragastric administration, providing a possible
means by which policosanol might lower blood cholesterol levels. Treatment of hepatoma cells with policosanol produced a 2.5-fold
or greater increase in the phosphorylation of AMP-kinase and HMG-CoA reductase, and increased the phosphorylation of Ca++/calmodulin-dependent kinase kinase (CaMKK), an upstream AMP-kinase kinase. Intragastric administration of policosanol to
mice similarly increased the phosphorylation of hepatic HMG-CoA reductase and AMP-kinase by greater than 2-fold. siRNA-mediated
suppression of fatty aldehyde dehydrogenase, fatty acyl-CoA synthetase 4, and acyl-CoA acetyltransferase expression in hepatoma
cells prevented the phosphorylation of AMP-kinase and HMG-CoA reductase by policosanol, indicating that metabolism of these
very long chain alcohols to activated fatty acids is necessary for the suppression of cholesterol synthesis, presumably by
increasing cellular AMP levels. Subsequent peroxisomal β-oxidation probably augments this effect. 相似文献
90.
Sanjay K. Chattopadhyay R. K. Khandal Ramagopal Uppaluri Aloke K. Ghoshal 《应用聚合物科学杂志》2011,119(3):1619-1626
Short bamboo fiber reinforced polypropylene composites were prepared by incorporation of various loadings of chemically modified bamboo fibers. Maleic anhydride grafted polypropylene (MA‐g‐PP) was used as compatibilizer to improve fiber–matrix adhesion. The effects of bamboo fiber loading and modification of the resin on the physical, mechanical, thermal, and morphological properties of the bamboo reinforced modified PP composites were studied. Scanning electron microscopy studies of the composites were carried out on the interface and fractured surfaces. Thermogravimetric analysis and IR spectroscopy were also carried out. At 50% volume fraction of the extracted bamboo fiber in the composites, considerable increase in mechanical properties like impact, flexural, tensile, and thermal behavior like heat deflection temperature were observed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献