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排序方式: 共有175条查询结果,搜索用时 15 毫秒
31.
Shailesh Pandey 《Petroleum Science and Technology》2018,36(1):40-47
Present study reports catalytic oxidative-extractive desulfurization (COEDS) of model oil (dibenzothiophene (DBT) dissolved in iso-octane) using an acid mixture (composed of Lewis acid and organic acid (glacial acetic acid)) as catalyst and inorganic oxysalt, potassium dichromate, as oxidant. A series of acid mixtures were prepared by mixing different amount of Lewis acids (SnCl2, CaCl2 or CuCl2) in specific amount of acetic acid and tested for the removal of sulfur from model oil. SnCl2, which performed best as a Lewis acid, was used in further studies. Effect of Lewis acid to sulfur (molar) ratio was studied in the range of 1–5. Effects of other parameters i.e. oxidant to sulfur (O/S) molar ratio, temperature and time on desulfurization efficiency were also investigated. Fourier transform infrared (FTIR) spectroscopy of SnCl2-CH3COOH mixture, model oil (before COEDS), raffinate and extract layers was carried out to understand the removal mechanism. Apparent activation energy for COEDS process with SnCl2-CH3COOH system was calculated as 11.65 kJ/mol. At the optimized conditions of oxidant to sulfur molar ratio (O/S = 2:1) and Lewis acid to sulfur molar ratio (SnCl2/S = 5:1), maximum 61.3% sulfur removal was observed from model oil containing 1000 ppm of sulfur at 308 K. 相似文献
32.
The extraction and transport behaviour of uranium from nitric acid medium across a supported liquid membrane has been studied using di(2-ethylhexyl)isobutyramide as the carrier. The effects of experimental parameters such as nature of diluents, e.g., n-dodecane, benzene, chloroform, tert-butyl benzene, diethyl benzene, n-octanol, 1,2-dichlorbenzene, and 2-nitrophenyl octyl ether, the membrane thickness, and the nitrate ion concentration, on the extraction/transport behaviour of uranium are reported. The experimentally obtained and the theoretically calculated values of permeability coefficients for uranium transport have been compared for different diluents. 相似文献
33.
Alok Chaube Shailesh Gupta Prakash Verma 《Journal of Mechanical Science and Technology》2014,28(5):1927-1937
The influence of a gap provided in integral inclined ribs on heat transfer and friction factor enhancement is investigated. Experiments are conducted to obtain heat transfer and friction factor characteristics in a square channel with two opposite in-line ribbed walls for Reynolds numbers from 5000 to 40000. The test section of square channel composed of integral inclined ribs with a gap and has a length-tohydraulic diameter ratio (L/D h ) of 20. The rib pitch-to-height ratio (p/e) is 10, the rib height-to-hydraulic diameter ratio (e/D h ) is 0.060 and rib attack angle (α) varies in the range of 300 to 900 (4 steps). The relative gap position (d/W) and relative gap width (g/e) is varied in the range of 1/5–2/3 (5 steps) and 0.5–2.0 (4 steps), respectively. The enhancement in heat transfer and friction factor of this roughened duct was compared with smooth duct and duct roughened with continuous inclined ribs (with no gap) under similar flow condition. Presence of inclined ribs with a gap yields about 4-fold enhancements in Nusselt number and about 8-fold increase in the friction factor compared with smooth duct and about 1.3 times and 1.4 times higher than the case of continuous ribs (without gaps) for the entire range of parameters investigated. Ribs with relative gap width of 1.0 at relative gap position of 1/3 and attack angle of 60° provides maximum heat transfer and friction factor enhancement. 相似文献
34.
Arun Kumar Kareem A. Mosa Liyao Ji Udaykumar Kage Dhananjay Dhokane Shailesh Karre 《Critical reviews in food science and nutrition》2018,58(11):1791-1807
Today, the dramatic changes in types of food consumed have led to an increased burden of chronic diseases. Therefore, the emphasis of food research is not only to ensure quality food that can supply adequate nutrients to prevent nutrition related diseases, but also to ensure overall physical and mental-health. This has led to the concept of functional foods and nutraceuticals (FFNs), which can be ideally produced and delivered through plants. Metabolomics can help in getting the most relevant functional information, and thus has been considered the greatest –OMICS technology to date. However, metabolomics has not been exploited to the best potential in plant sciences. The technology can be leveraged to identify the health promoting compounds and metabolites that can be used for the development of FFNs. This article reviews (i) plant-based FFNs-related metabolites and their health benefits; (ii) use of different analytic platforms for targeted and non-targeted metabolite profiling along with experimental considerations; (iii) exploitation of metabolomics to develop FFNs in plants using various biotechnological tools; and (iv) potential use of metabolomics in plant breeding. We have also provided some insights into integration of metabolomics with latest genome editing tools for metabolic pathway regulation in plants. 相似文献
35.
Vinodkumar M Rajagopalan S Bhagwat IP Singh S Parmar BS Mishra OP Upadhyay SS Bhalia NB Deshpande SR 《Food and nutrition bulletin》2007,28(1):100-108
BACKGROUND: Iron and iodine deficiencies affect more than 30% of the world's population. Typical Indian diets contain adequate amounts of iron, but the bioavailability is poor. This serious limiting factor is caused by low intake of meat products rich in heme iron and intake of phytates in staple foods in the Indian diet, which inhibits iron absorption. OBJECTIVE: To test the stability of double-fortified salt (DFS) during storage and to assess its efficacy in improving the iron and iodine status of the communities. METHODS: The stability of both iodized salt and DFS during storage for a 2-year period was determined. The bioefficacy of DFS was assessed in communities covering three states of the country for a period of 1 year. This was a multicenter, single-blind trial covering seven clusters. The experimental group used DFS and the control group used iodized salt. The salts were used in all meals prepared for family members, but determination of hemoglobin by the cyanmethemoglobin method was performed in only two or three members per family, and not in children under 10 years of age (n = 393 and 436 in the experimental and control groups, respectively). The family size was usually four or five, with a male: female ratio of 1:1, consisting of two parents with two or three children. Hemoglobin was measured at baseline, 6 months (midpoint), and 12 months (endpoint). Urinary iodine was measured in only one cluster at baseline and endpoint. All the participants were dewormed at baseline, 6 months, and 12 months. RESULTS: The iron and iodine in the DFS were stable during storage for 2 years. Over a period of 1 year, there was an increase of 1.98 g/dL of hemoglobin in the experimental group and 0.77 g/dL of hemoglobin in the control group; the latter increase may have been due to deworming. The median urinary iodine changed from 200 microg/dL at baseline to 205 microg/dL at the end of the study in the experimental group and from 225 microg/dL to 220 microg/dL in the control group. There was a statistically significant (p < .05) improvement in the median urinary iodine status of subjects who were iodine deficient (urinary iodine < 100 microg/L) in both the experimental and the control groups, a result showing that DFS was as efficient as iodized salt in increasing urinary iodine from a deficient to sufficient status. There was a statistically significant increase (p < .05) in hemoglobin in all seven clusters in the experimental group compared with the control. CONCLUSIONS: The iron and iodine in the DFS are stable in storage for 2 years. The DFS has proved beneficial in the delivery of bioavailable iron and iodine. 相似文献
36.
The possibility for the switch-over of the growth mode from a continuous network to unidirectional arrays of well-separated, self-organized, vertically oriented graphene nanosheets has been demonstrated using a unique, yet simple plasma-based approach. The process enables highly reproducible, catalyst-free synthesis of arrays of graphene nanosheets with reactive open graphitic edges facing upwards. Effective control over the nanosheet length, number density, and the degree of alignment along the electric field direction is achieved by a simple variation of the substrate bias. These results are of interest for environment-friendly fabrication of next-generation nanodevices based on three-dimensional, ordered self-organized nanoarrays of active nanostructures with very large surface areas and aspect ratios, highly reactive edges, and controlled density on the substrate. Our simple and versatile plasma-based approach paves the way for direct integration of such nanoarrays directly into the Si-based nanodevice platform. 相似文献
37.
GB Proctor XS Zhang JR Garrett DK Shori KM Chan J Chao 《Canadian Metallurgical Quarterly》1997,82(6):977-983
The enzymic activity and immunoreactivity of rat tissue kallikrein (rK1) secreted at rest by granular duct cells of unstimulated submandibular glands has been compared with that secreted on autonomic nerve stimulation. Although a direct vesicular, constitutive secretory pathway operates for rK1 secretion from granular duct cells of unstimulated and parasympathetically stimulated glands the rK1 was not present in a pro-form and actually showed a greater enzymic activity per unit immunoreactive protein than the granule-derived rK1 in sympathetically evoked saliva. Constitutively secreted rK1 was found to be in a single chain molecular form by reducing SDS gel electrophoresis. In contrast rK1 secreted from the storage granule pool of granular duct cells on sympathetic nerve stimulation was present in much higher amounts and occurred in both one-chain and two-chain forms as revealed by SDS gel electrophoresis under reducing conditions. The lower enzymic potential of rK1 in sympathetically evoked saliva might be accounted for by its conversion to a two-chain form. 相似文献
38.
Shailesh Kumar Singh Dr. Syed Masood Husain 《Chembiochem : a European journal of chemical biology》2018,19(15):1657-1663
Superoxide (O2.?) generation in biological systems is achieved through some of the most complex enzymatic systems. Of these, only xanthine/xanthine oxidase has been used for in vitro biochemical studies. However, it suffers from limitations such as a lack of suitable heterologous expression system for xanthine oxidase and the irreversible consumption and low solubility of xanthine under physiological conditions. Herein, we report a redox‐based, enzyme‐catalyzed system, in which autoxidation of hydroquinone to quinone via semiquinone results in superoxide generation. Quinone is reduced back to hydroquinone by using the NfsB (oxygen‐insensitive nitroreductase) enzyme of Escherichia coli strain K‐12 and nicotinamide adenine dinucleotide phosphate hydride (NADPH; which is regenerated by using the glucose/glucose dehydrogenase system). This new system relies on quinones that can be recycled and have superior water solubility, as well as enzymes that are heterologously expressed. By using a variety of quinones and reaction conditions, along with a comparison of real‐time fluorescence, menadione has been identified as the optimal substrate for superoxide generation. The new redox‐based system presents a viable alternative for studying the biochemistry of superoxide under different physiological and pathological conditions. 相似文献
39.
Khanolkar Shailesh Sharma Nitin Anpalagan Alagan 《Wireless Personal Communications》2022,124(2):1443-1455
Wireless Personal Communications - Due to the limited resources of Internet of Things (IoT) nodes, routing protocols for these networks should be designed in such a way that not only reduce the... 相似文献
40.
The scope of this paper is to evaluate and discuss the flow phenomena of Al–2Si and Al–12Si alloys, which were joined through friction stir welding processes. The feed rate of 50mm/min and tool rotation of 600, 900, and 1200 rpm were selected for the processes. There was much change in the surface morphology with smoothness for Al–2Si alloy and roughness for Al–12 Si alloys. The microstructure studies on the weld zone were performed. The mechanical properties like tensile strength and hardness are discussed in detail. 相似文献