Pharmacological Mechanisms Underlying Gastroprotective Activities of the Fractions Obtained from Polygonum minus in Sprague Dawley Rats

The leaves of Polygonum minus were fractionated using an eluting solvent to evaluate the pharmacological mechanisms underlying the anti-ulcerogenic activity of P. minus. Different P. minus fractions were obtained and evaluated for their ulcer preventing capabilities using the ethanol induction method. In this study, Sprague Dawley rats weighing 150-200 g were used. Different parameters were estimated to identify the active fraction underlying the mechanism of the gastroprotective action of P. minus: the gastric mucus barrier, as well as superoxide dismutase, total hexosamine, and prostaglandin synthesis. Amongst the five fractions from the ethanolic extract of P. minus, the ethyl acetate:methanol 1:1 v/v fraction (F2) significantly (p < 0.005) exhibited better inhibition of ulcer lesions in a dose-dependent manner. In addition, rats pre-treated with F2 showed a significant elevation in superoxide dismutase (SOD), hexosamine and PGE2 levels in the stomach wall mucosa in a dose-dependent matter. Based on these results, the ethyl acetate:methanol 1:1 v/v fraction was considered to be the best fraction for mucous protection in the ethanol induction model. The mechanisms underlying this protection were attributed to the synthesis of antioxidants and PGE2.     

Adsorption characteristics of toxic chromium(VI) from aqueous media onto nanosized silver nanoparticles-treated activated carbon

The present study reports the use of nanomaterial, e.g. Ag nanoparticles (AgNPs), immobilized activated carbon as an effective solid adsorbent for removal of toxic chromium(VI) from water. Chromium(VI) uptake was found favorable in acidic media at pH ≤ 3. Based on Langmuir model, monolayer adsorption capacities of chromium(VI) found equal 93.5 mg/g. The results fitted well with pseudo second-order and Langmuir models. The mechanism of adsorption was explored using the intra-particle diffusion model and the liquid-film model. Chromatographic separation of chromium(VI) was achieved. The AC-AgNPs was successfully recycled for five successive adsorption–desorption cycles indicating its high reusability.     

Preparation of void-free casts from vinyl polysiloxane impressions

PURPOSE: To investigate two techniques to produce void-free casts from vinyl polysiloxane impressions. MATERIALS AND METHODS: Thirty casts prepared using a conventional technique were compared with 30 casts prepared using a technique involving syringing of stone in terms of numbers of surface voids. RESULTS: Significantly fewer surface voids were observed in the casts prepared using syringing technique. CONCLUSION: The syringing technique investigated is considered to have advantages over the conventional technique for the production of casts from vinyl polysiloxane impressions.     

Approximated parameterized verification of infinite-state processes with global conditions

We present a simple and effective approximated backward reachability procedure for parameterized systems with existentially and universally quantified global conditions. The individual processes operate on unbounded local variables ranging over the natural numbers. In addition, processes may communicate via broadcast, rendez-vous and shared variables. The procedure operates on an over-approximation of the transition system induced by the parameterized system. We verify mutual exclusion for complex protocols such as atomic, non-atomic and distributed versions of Lamport’s bakery algorithm.     

A photovoltaic utilization system with bang–bang self-adjusting maximum energy tracking controller

The paper presents an error driven controller for maximum energy utilization of photovoltaic PV renewable energy interface schemes. The error driven comprises of regulation loops ensuring on-line dynamic tracking of the maximum power point under different variations in solar insulation levels or sudden mechanical load excursions. The bang–bang regulator limiter block is self-adjusting as it is driven by the error excursion vector magnitude. This ensures that the control signal is modulated in magnitude by the distance of error deviation in the error hyper plane. The paper details a digital simulation MATLAB/SIMULINK model of a PV−PMDC motor utilization system driving a ventilation, pumping or air-conditioning mechanical load. © 1998 John Wiley & Sons, Ltd.     

Comparative study of single and multi-layered packed-bed thermal energy storage systems for CSP plants

The Multi-layered Thermal Energy Storage (TES) tank consists of three regions–top and bottom part is packed with suitable Phase Change Materials (PCM) and low-cost pebbles are placed in the middle region, whereas entire tank portion is filled by solid fillers in Single-layered tank system. For a storage tank operating between 563 and 663 K with bed dimensions of 12 and 14.38 m using Solar salt as Heat Transfer Fluid (HTF), it is observed that the duration of discharge for multi-layered tank is 5.32 h whereas it is 4.19 h for single-layered tank with a Reynolds number of 10. The effect of intermediate melting temperature range of PCMs are also analyzed by taking PCMs with sharp as well as intermediate melting ranges. Further, comparison of single and multi-layered systems is carried out by analyzing the temperature profiles and width of both PCM layers. The width of top and bottom PCM layers of tank is varied from 0 to 30% to analyze its effect on the discharging duration. It is observed that multi-layered system provides extra discharge of 1 h with introduction of PCM at top and bottom with a width of 10%. Discharge duration increases with increase in PCM width whereas the percentage increase in duration of discharge with increase in PCM width is comparatively less. It is also seen that PCMs with sharp melting point performs better compared to one having intermediate range of melting temperatures. Multi-layered configuration concept offers best possibilities as integration to CSP plants with desired efficiency.     

酸浆花萼色素的提取及理化性质研究

采用不同的试剂提取酸浆花萼的天然色素，并且对色素的理化性质进行研究。结果表明：该色素在丙酮中提取效果最好，其最大吸收峰在406nm处；色素在不同温度下稳定性良好：在不同食品添加剂条件下稳定性良好：在太阳光照条件下对色素有减色作用；色素有较明显的抑菌作用。     

Photovoltaic cells energy performance enhancement with down‐converting photoluminescence phosphors

Phosphors, synthesized by the urea homo‐precipitation method, were examined as ultraviolet‐spectral down conversion materials for improving the light absorption and electrical characteristics of commercial single‐junction silicon solar cells. The photovoltaic (PV) cells were coated with erbium and terbium doped gadolinium oxysulfide phosphors encapsulated in ethyl vinyl‐acetate binder using blade screen printing technique, and the optimum concentration of phosphor in the composite resulted in the largest light conversion, and superior electrical output and energy transfer efficiency. Moreover, the results demonstrated that the composition of dispersed phosphors has a strong influence on the amount of ultraviolet‐light converted and electron transition capacity of PV cells. The experimental results showed in an optimized PV cell, an enhancement of 0.54% (from 12.11% to 12.65%) in the energy conversion of a Si‐based PV cell was achieved. Copyright © 2015 John Wiley & Sons, Ltd.     

黄花软紫草多糖的提取及清除自由基的研究

研究了黄花软紫草水溶性多糖的提取及对Fenton反应产生·OH自由基的清除效果。结果表明,以水为溶剂提取的紫草多糖的得率为2.53%,且此粗多糖清除自由基的能力与其浓度呈线性关系。