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1.
Two-freedom seven-bar linkages with sliding inputs and output are especially compact as two-variable function generators. When two of the sliders, appropriately chosen, have parallel directions the method of identical link positions[6] is shown to split up the synthesis of the linkage into that of a double slider and a slider-crank while as many as 11 precision points are obtained.  相似文献   
2.
Though present in small amounts, the minor constituents of dietary oils may supplement the dietary therapies for rheumatoid arthritis (RA). Hence, in the present study, we assessed the effect of minor constituents from sesame oil (SO) and rice bran oil (RBO) and their fatty acids on the severity of adjuvant‐induced arthritis in experimental rats. Rats were gavaged with 1 mL of SO or RBO or groundnut oil (GNO, control) with or without its minor components for a period 15 days before and 15 days after the induction of arthritis. Oxidative stress, markers of RA, eicosanoids, cytokines, paw swelling and joint integrity were measured in experimental and control rats. Results demonstrated that native SO and RBO but not SO and RBO stripped of their minor components decreased severity of paw inflammation, oxidative stress (lipid peroxides, protein carbonyls, nitric oxide), RA markers (RF and CRP), inflammatory eicosanoids (PGE2, LTB4 and LTC4) and cytokines (IL‐1β, IL‐6, MCP‐1 and TNF‐α) compared to control rats. Native SO and RBO inhibited hydrolytic enzymes (collagenase, elastase and hyaluronidase) in the synovial tissue compared to SO and RBO without minor components. The arthritic scores assessed based on the digital and X‐ray images indicated that native oils but not those without their minor components reduced the paw swelling and bone loss. Our results indicated that minor components of SO and RBO possess a significant degree of an anti‐arthritic effect and are responsible for down regulating inflammation in the experimentally induced arthritis in rats.  相似文献   
3.
We study a scheduling problem in a wireless network where vehicles are used as store-and-forward relays, a situation that might arise, for example, in practical rural communication networks. A fixed source node wants to transfer a file to a fixed destination node, located beyond its communication range. In the absence of any infrastructure connecting the two nodes, we consider the possibility of communication using vehicles passing by. Vehicles arrive at the source node at renewal instants and are known to travel towards the destination node with average speed v sampled from a given probability distribution. The source node communicates data packets (or fragments) of the file to the destination node using these vehicles as relays. We assume that the vehicles communicate with the source node and the destination node only, and hence, every packet communication involves two hops. In this setup, we study the source node’s sequential decision problem of transferring packets of the file to vehicles as they pass by, with the objective of minimizing delay in the network. We study both the finite file size case and the infinite file size case. In the finite file size case, we aim to minimize the expected file transfer delay, i.e., expected value of the maximum of the packet sojourn times. In the infinite file size case, we study the average packet delay minimization problem as well as the optimal tradeoff achievable between the average queueing delay at the source node buffer and the average transit delay in the relay vehicle.  相似文献   
4.
Dielectric study over a broadband was carried out from 10 to 70 K on ceramic Gd1?xYxMnO3 (x=0.2, 0.3 and 0.4). For all the compositions, a prominent sharp peak about ~18 K was observed in the temperature dependence of both ε′(T) and ε″(T) at all frequencies, indicating a long‐range ferroelectric (FE) transition. Using Cole‐Cole fit to the permittivity data, the relaxation time τ and the dielectric strength ?ε were estimated. Temperature variation of τ(T) in the Arrhenius representation is found to be nonlinear (non‐Debyean relaxation), with increasing barrier‐activation energy over successive temperature‐windows. Interestingly, for all the compositions, we witness a jump in τ(T) about the ferroelectric transition temperature, concurred by a broad‐maximum in ?ε(T),signifying the critical slow down of relaxations near long‐range FE‐correlations.  相似文献   
5.
Sekar R  Wu HF 《Analytical chemistry》2006,78(18):6306-6313
A simple and selective analytical method for the quantitative determination of low concentrations of monensin in soil, surface water, and human urine has been developed. Prior to atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) analysis, the samples were preconcentrated by using the single-drop microextraction (SDME) technique. Several factors that affect the analyte's extraction, including selection of solvent, microdrop volume, extraction time, and ionic strength, were investigated. Chloroform-toluene (1:1, v/v) was selected as the extraction solvent. Reliable results were obtained using dibenzo-30-crown-10-ether as an internal standard. The proposed method has been successfully applied for the determination of monensin in soil, surface water, and human urine spiked samples. Under the optimized conditions, the limits of quantification of the analyte in surface water, soil, and human urine were 6.7, 12.4 and 7.8 ng/mL, respectively. The intraday and interday precision variation and accuracy of the present method is within the acceptable ranges. The present method avoids the pre- and postderivatization of weak UV absorbing monensin determination using high performance liquid chromatography-ultraviolet detection (HPLC-UV). Furthermore, these techniques are time-consuming, nonreproducible at trace levels, and form undesirable products. The proposed SDME combined with AP-MALDI-MS is simple, fast, and selective for the determination of monensin in environmental and urine samples.  相似文献   
6.
Methods of synthesizing nine-link plane mechanisms for two-variable function generation are presented. These are simplified procedures which employ identical relative positions and identical absolute positions of links. These techniques split the problem into syntheses of two single-freedom linkages when proper mechanisms are chosen, out of the available nine-link mechanisms. Up to 16 precision points (specified) can be directly satisfied, depending on the mechanism chosen. Numerical examples demonstrate that nine-link mechanisms as two-variable function generators are a practical proposition, especially with the synthesis techniques presented.  相似文献   
7.
The present study assessed the role of dietary unsaturated fatty acids in maternal dyslipidemia‐induced DNA methylation and histone acetylation in placenta and fetal liver and accumulation of lipids in the fetal liver. Weanling female Wistar rats were fed control and experimental diets for 2 months, mated, and continued on their diets during pregnancy. At gestation days of 18–20, rats were euthanized to isolate placenta and fetal liver. DNA methylation, DNA methyl transferase‐1 (DNMT1) activity, acetylation of histones (H2A and H2B), and histone acyl transferase (HAT) activity were evaluated in placenta and fetal liver. Fetal liver lipid accumulation and activation of peroxisome proliferator‐activated receptor‐α (PPAR‐α) were assessed. Maternal dyslipidemia caused significant epigenetic changes in placenta and fetal liver. In the placenta, (1) global DNA methylation increased by 37% and DNMT1 activity by 86%, (2) acetylated H2A and H2B levels decreased by 46% and 24% respectively, and (3) HAT activity decreased by 39%. In fetal liver, (1) global DNA methylation increased by 52% and DNMT1 activity by 78%, (2) acetylated H2A and H2B levels decreased by 28% and 26% respectively, and (3) HAT activity decreased by 37%. Maternal dyslipidemia caused a 4.75‐fold increase in fetal liver triacylglycerol accumulation with a 78% decrease in DNA‐binding ability of PPAR‐α. Incorporation of dietary unsaturated fatty acids in the maternal high‐fat diet significantly (p < 0.05) modulated dyslipidemia‐induced effects in placenta and fetal liver. Eicosapentaenoic acid (EPA, 20:5n‐3) + docosahexaenoic acid (DHA, 22:6n‐3) exhibited a profound effect followed by alpha‐linolenic acid (ALA, 18:3n‐3) than linoleic acid (LNA, 18:2n‐6) in modulating the epigenetic parameters in placenta and fetal liver.  相似文献   
8.
Nine-link plane mechanisms come in for consideration for two-variable function generation when a satisfactory design is not obtained using the seven-link mechanism. In this paper, all the possible nine-link mechanisms that can be used for function generation are listed. These are arrived at by a simple device from one-freedom eight-link mechanisms, a complete list of the latter being already available. There are 17 such nine-link mechanisms. Significant double-pivot mechanisms derived from the above are also listed.  相似文献   
9.
The effectiveness of phosphoric acid doped polybenzimidazole as a polymer electrolyte membrane to fabricate an all solid-state super capacitor has been explored using hydrous RuO2/carbon composite electrodes (20 wt.%) of surface area 250 m2 g−1 with many intrinsic advantages. The electrochemical evaluation of these super capacitors through cyclic voltammetry, charge/discharge and impedance measurements demonstrate the utility of this type of thin, compact and flexible supercapacitor capable of functioning at 150 °C to yield a maximum capacitance of about 290 F g−1 along with a life of more than 1,000 cycles. A power density of 300 W kg−1 and energy density of 10 Wh kg−1 have been accomplished although the equivalent series resistance (ESR) of about 3.7 Ω needs to be reduced further for high rated applications.  相似文献   
10.
A dwell mechanism has been developed based on a coupler curve approximating an involute and utilising a rack and pinion arrangement. The proportions of the basic linkage have been synthesised and the dwell characteristics of the output link have been computed and presented.  相似文献   
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