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51.
An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones using Amberlyst-70 as a recyclable catalyst has been developed. The use of resinous, nontoxic, thermally stable and inexpensive Amberlyst-70, as a recyclable heterogeneous catalyst, makes the process simple with negligible chemical waste. Thus renders this method an environmentally acceptable synthetic tool for Biginelli reaction. 相似文献
52.
A Power Control MAC Protocol for Ad Hoc Networks 总被引:6,自引:0,他引:6
This paper presents a power control MAC protocol that allows nodes to vary transmit power level on a per-packet basis. Several researchers have proposed simple modifications of IEEE 802.11 to incorporate power control. The main idea of these power control schemes is to use different power levels for RTS–CTS and DATA–ACK. Specifically, maximum transmit power is used for RTS–CTS, and the minimum required transmit power is used for DATA–ACK transmissions in order to save energy. However, we show that these schemes can degrade network throughput and can result in higher energy consumption than when using IEEE 802.11 without power control. We propose a power control protocol which does not degrade throughput and yields energy saving. 相似文献
53.
Shih Chieh Huang Jui Kung Wu Wei-Jen Hsu Hsin Hsiung Chang Hsien Yen Hung Chi Lian Lin Hung-Yuan Su Nitin Bagkar Wei-Chih Ke Hui Tung Kuo Ru-Shi Liu 《International Journal of Applied Ceramic Technology》2009,6(4):465-469
The synthesis of cerium-doped yttrium aluminum garnet (YAG:Ce) phosphor of different sizes with uniform size distribution was carried out using solid-state reaction followed by grinding and sieving method. The effect of particle size distribution of YAG:Ce phosphors on the photoluminescence (PL) properties was investigated. The results demonstrate that the uniform size distribution and particle size affects the packaging performance in white light emitting diode (LED) applications. The YAG:Ce phosphors with different particle sizes were packaged in white LEDs using different amounts of each phosphors in order to get similar efficiency as that of commercially available YAG:Ce phosphors. It was observed that minimum amount of phosphor material is required for smaller particle size for getting the similar efficiency as that exhibited by commercially available YAG:Ce phosphors. The results are particularly interesting in view of reducing the cost of current LEDs by lowering the amount of phosphors without compromising the efficiencies of final LED package. A systematic study of YAG:Ce phosphors on the packing performance in white LEDs is reported. 相似文献
54.
Kuttan Prabhakaran Anand Melkeri Mohd Oveas Beigh Nitin Madhusudan Gokhale Suresh Chandra Sharma 《Journal of the American Ceramic Society》2007,90(2):622-625
A porous NiO–YSZ substrate for anode-supported solid oxide fuel cells has been prepared by gelcasting of NiO–YSZ powders using urea–formaldehyde monomers, followed by humidity-controlled drying, binder removal, and sintering of the gelled bodies. The gelled bodies had sufficient strength to remove even 2-mm-thick samples from the mold immediately after gelation. A gelcast NiO–YSZ sample sintered at 1450°C for 2 h showed an open porosity of ∼53 vol%, and the porosity increased to ∼58% upon reduction with hydrogen. Pore sizes measured on the scanning electron microscopy photomicrograph of NiO–YSZ and Ni–YSZ cermet substrates are in the range of 2–5 μm. Urea–formaldehyde polymer, present in a high amount (∼13 wt%) in the gelcast body, acts as a template for pores. 相似文献
55.
Nainital City of Kumaun Lesser Himalaya is prone to mass wasting processes during monsoon season, which mischievously triggers the hill slope instability in this region. Slate, dolomitic limestone, silty sandstone and rhythmite of the Krol Formation are the main rock types. The present study focuses on the investigation of slope stability in the region in terms of potential seismicity and landslide. Geological and geotechnical mapping indicates that the major portion of the area is characterized by slope wash materials and buildings. The combination of 3–4 joint sets with one random joint is the main structure at outcrops. The major geological structures of this area are Nainital lake fault passing from the center of the lake, Main Boundary Thrust at SW, and Khuriya Fault passing from the SE direction of Nainital City. This work finds that different types of discontinuities (e.g. joints and faults), overburden due to unplanned civil structures, and neotectonic activity in the vicinity of this area affect the stability of the city. The slate forms the base of the city, dipping slightly towards the lake side along the NW direction, thus accelerating the instability of this area. Rock mass rating (RMR), slope mass rating, factor of safety (FOS) and graphical analysis of the discontinuity for slope kinematics indicate that the study area is a landslide-prone zone. This study can facilitate reducing the risk of human life, and contribute to the ongoing construction works in the area. 相似文献
56.
Nitin Chitranshi Vivek Gupta Sanjay Kumar Stuart L. Graham 《International journal of molecular sciences》2015,16(9):21087-21108
7,8-Dihydroxyflavone (7,8-DHF) is a TrkB receptor agonist, and treatment with this flavonoid derivative brings about an enhanced TrkB phosphorylation and promotes downstream cellular signalling. Flavonoids are also known to exert an inhibitory effect on the vascular endothelial growth factor receptor (VEGFR) family of tyrosine kinase receptors. VEGFR2 is one of the important receptors involved in the regulation of vasculogenesis and angiogenesis and has also been implicated to exhibit various neuroprotective roles. Its upregulation and uncontrolled activity is associated with a range of pathological conditions such as age-related macular degeneration and various proliferative disorders. In this study, we investigated molecular interactions of 7,8-DHF and its derivatives with both the TrkB receptor as well as VEGFR2. Using a combination of molecular docking and computational mapping tools involving molecular dynamics approaches we have elucidated additional residues and binding energies involved in 7,8-DHF interactions with the TrkB Ig2 domain and VEGFR2. Our investigations have revealed for the first time that 7,8-DHF has dual biochemical action and its treatment may have divergent effects on the TrkB via its extracellular Ig2 domain and on the VEGFR2 receptor through the intracellular kinase domain. Contrary to its agonistic effects on the TrkB receptor, 7,8-DHF was found to downregulate VEGFR2 phosphorylation both in 661W photoreceptor cells and in retinal tissue. 相似文献
57.
Rakesh Kumar Soni Harjeet Singh Krishna Dutt Priyanka Arora 《Journal of Polymer Research》2010,17(3):411-427
The mixing torque behavior of ter blends of isotactic-polypropylene (iPP) with ethylene-propylene diene rubber (EPDM)/Nitrile
rubber (NBR) was studied with the help of Rheometer using resole type phenolic resin as a cross-linking agents. Systematic
changes with varying blend composition were observed in stress-strain behavior in the yield region viz., width of yield peak,
work of yield, yield stress and yield strain. Analysis of yield stress data was made on the basis of various mathematical
expressions of first power and two-thirds power laws of blend composition dependence and the porosity model. It led to consistent
result from the expressions about the variation of stress concentration effect in both uncross-linked and cross-linked blend
systems. With the aid of scanning electron microscopy (SEM) shapes and sizes of dispersed elastomer phase (EPDM / NBR) domains
at varying blend compositions were studied. 相似文献
58.
Kang Huang Yuyang Tian Deepti Salvi Mukund Karwe Nitin Nitin 《Food and Bioprocess Technology》2018,11(3):621-633
Washing and sanitation of fresh produce are critical for detachment and inactivation of pathogenic and spoilage microorganisms. The overall goal of this study was to evaluate the influence of processing conditions such as washing time, shear stress, and a food grade surfactant on the detachment of Escherichia coli O157:H7 from lettuce leaf surfaces during a simulated washing process. A benchtop scale rotating disk washing device was designed to simulate the processing conditions used in commercial washing systems. Numerical simulations were carried out to calculate the flow profile and shear stress near the leaf surface. Removal of E. coli O157:H7 as a function of processing conditions in the rotating disk washing device was evaluated by enumeration of bacterial population using plate counting and changes in bioluminescence intensity and further confirmed by bioluminescence imaging. The results showed that shear stress was necessary to remove attached bacteria from inoculated leaf samples and simple incubation of inoculated leaves with wash water was not effective. Furthermore, detachment of bacteria from inoculated leaf samples increased with increasing shear stress and incubation time. Shear stress values in the range of 0 – 300 mPa were adequate to induce removal of approximately 1.5 log CFU/cm2 of bacteria from inoculated samples. The addition of a surfactant increased the removal of bacteria from inoculated leaf samples by 0.5 log CFU/cm2. Overall, these results may guide the design of new produce wash systems as well as current industrial practice related to flow conditions and use of surfactants during washing of fresh produce. 相似文献
59.
Harish Chandra AndolaRanbeer Singh Rawal Indra Dutt Bhatt 《Food research international (Ottawa, Ont.)》2011,44(7):2352-2356
Nutritional and anti-nutritional factors of five Berberis species, widely known for their wild edible fruits and medicinal properties, were investigated in the Indian west Himalaya. These fruits contained high content of fiber (pulp 7.0-8.1%; seeds 4.4-5.3%), protein (pulp 4.7-7.2%; seeds 5.9-8.5%) and fat (pulp 2.6-4.0%; seeds 4.6-5.3%) as compared to most of the known wild edibles in the region. They, however, contained reasonably lower food energy, largely due to low carbohydrate content. All the five species emerged as good source of minerals, especially Ca and K. The values of various nutrient and mineral elements varied significantly among species, which implies potential of different species can be harnessed for diverse attributes. The fruits, however, possessed anti-nutritional factors like tannins and phytic acid, which need to be tackled appropriately while considering these fruits for value addition as health food. 相似文献
60.
Scientometrics of the international journal Scientometrics 总被引:4,自引:0,他引:4
An analysis of 1317 papers published in first fifty volumes during 1978 to 2001 of the international journal Scientometrics indicates the heterogeneity of the field with emphasis on scientometric assessment. The study indicates that the US share of papers is constantly on the decline while that of the Netherlands, India, France and Japan is on the rise. The research output is highly scattered as indicated by the average number of papers per institution. The scientometric output is dominated by the single authored papers, however, multi-authored papers are gaining momentum. Similar pattern has been observed for domestic and international collaboration. 相似文献