Edible mushrooms: a potential source of essential amino acids,glucans and minerals

The main chemical and biochemical constituents of nine edible mushrooms were evaluated in this study. An enzymatic method was used to determine the α‐ and β‐glucan contents, and the amino acid (AA) profiles were evaluated by RP‐HPLC‐DAD. The recommended dietary allowance (RDA) of the nutrients was evaluated. Finally, principal component analysis (PCA) was used to group the mushrooms according to their AA, glucans and chemical composition. All mushrooms evaluated can be considered as a potential and alternative source of dietary fibre (24.4–46.62%) and protein (16.47–36.96%) in a diet, with low contents of fat (1.40–2.08%). Phosphorus, potassium, iron, copper and zinc were the main minerals found in the mushrooms, whereas sodium concentration was negligible. All essential AA were detected in the mushrooms, with Pleurotus ostreatus (black oyster) representing the main source of essential amino acids among the samples. The contents of β‐glucan ranged from 1.58 to 16.91 mg g^?1 of dry matter among the mushrooms and Pleurotus eryngii presented the highest amount of this component. Pleurotus ostreatus (black oyster) and P. eryngii were also grouped together due to similarities in their phosphorous and arginine contents. Among the main results, it can highlight the high concentration of dietary fibre and essential amino acids of the edible mushrooms.     

Power-to-Gas integration in the Transition towards Future Urban Energy Systems

Temperature levels play a key role in the thermal energy demand of urban contexts affecting their associated primary energy consumption and Renewable Energy Fraction. A Smart Heating strategy accounts for those supply features requiring new solutions to be effectively renewable and to solve the RES capacity firming. Power-to-Gas (P2G) is the way to decarbonize the energy supply chain as fraction of Hybrid fuels, combination of fossil ones and Renewable Hydrogen, as immediate responsive storage solution. While, Power-To-Heat is conceived as the strategy to modernize the high and medium temperature heating systems by electricity-driven machines to switch from Fuel-to-Heat to Electricity-to-Heat solutions. The authors investigated on different urban energy scenarios at RES share increase from 25% up to 50% in the energy mix to highlight strengths and weaknesses of the P2G applications. Primary Energy Consumption was chosen as the objective function. Three Reference Cities were chosen as reference scenarios. Moreover, the analytical models of P2G was designed and implemented in the reference energy system. The results of the twelve scenarios, four for each Reference City were evaluated in terms of amount of Renewable Heat delivered. Finally, the interaction between P2G and renewable heat production was evaluated.     

Development of an experimentally validated semi-empirical fully-coupled performance model of a PEM electrolysis cell with a 3-D structured porous transport layer

A semi-empirical non-isothermal model incorporating coupled momentum, heat and mass transport phenomena for predicting the performance of a proton exchange membrane (PEM) water electrolysis cell operating without flow channels is presented. Model input parameters such as electro-kinetics properties and mean pore size of the porous transport layer (PTL) were determined by rotating disc electrode and capillary flow porometry, respectively. This is the first report of a semi-empirical fully coupled model which allows one to quantify and investigate the effect of the gas phase and bubble coverage on PEM cell performance up to very high current densities of about 5 A/cm². The mass transport effects are discussed in terms of the operating conditions, design parameters and the microstructure of the PTL. The results show that, the operating temperature and pressure, and the inlet water flowrate and thickness of the PTL are the critical parameters for mitigating mass transport limitation at high current densities. The model presented here can serve as a tool for further development and scale-up effort in the area of PEM water electrolysis, and provide insight during the design stage.     

基于无监督聚类算法的风电场高压电缆局放脉冲识别

针对风电场高压电缆局部放电在线监测中脉冲型干扰难以抑制的技术难题,分析了风电场高压电缆局部放电脉冲及各类干扰脉冲的分布特征,并在此基础上,提出了基于无监督聚类算法的风电场局部放电脉冲识别策略。首先对现场多个工频周期的原始脉冲群依次进行自适应、自学习聚类,然后根据聚类结果计算不同脉冲群的三维分布谱图,最后根据不同类脉冲的分布差异有效地识别出局部放电脉冲。该策略不需要脉冲样本知识,面向复杂的电磁干扰环境具有很强的适应性与实用性,某风电场工程应用实践证明了该策略能准确地实现脉冲识别。     

低气压环境被服系统总热阻计算模型

服装热阻是影响人体热舒适的重要因素之一,夜间睡眠状态下的被服系统总热阻包括人体所穿服装热阻与整个床褥系统热阻。针对低气压环境,目前,尚缺乏被服热阻实验数据,也没有可参考的被服系统总热阻的理论计算模型。以人体睡眠状态被服系统总热阻计算方法为依据,引入气压修正项对相关参数进行修正,建立了适用于低气压环境的被服系统总热阻的修正计算模型,并用模型计算了冬夏典型被服系统总热阻,分析了气压减小对总热阻的影响,发现冬夏季被服系统总热阻均随大气压力降低而升高,增加百分比最大值均为42%,且均出现在被子覆盖率为23.3%的条件下,当海拔低于3 000m时,由被子覆盖率引起的被服系统总热阻增加系数不超过0.05。     

适用多种铝土矿的氧化铝溶出新方案

溶出是拜尔法生产氧化铝的关键工序,铝土矿中氧化铝水合物的存在状态直接影响着溶出条件的选择。本文结合近期所设计的某氧化铝厂项目中的一套装置实现高温和低温两种溶出工艺的设计方案,对如何通过一套溶出装置,来实现两种溶出工艺,以适应不同矿石的工艺方法和装置,做详尽分析。     

城市配网规划电压等级合理配置及经济比较

通过建立电压等级与投资、运行成本的函数关系,以成本最小为原则对电压等级进行优化。提出了考虑经济性因素的＂几何均值＂原则,并从经济性角度对电压等级序列优化提出数学模型。     

Hydration of a low‐grade magnesium oxide. Lab‐scale study

BACKGROUND: Low grade magnesium oxide (LG‐MgO) is a by‐product from the calcination of natural magnesite that is currently hydrated to magnesium hydroxide by storing it in the open for up to 6 months. It is eight to ten times cheaper than pure magnesium oxide and therefore the revalorization of this by‐product is very attractive for those applications requiring great quantities of magnesium hydroxide for which high purity is not required. Here the hydration of LG‐MgO is studied as a function of two parameters: hydrating agent and temperature. RESULTS: Addition of acetic acid during the hydration of LG‐MgO improved the effectiveness of treatment. At 50 °C, the maximum percentage hydration was 40% in pure water and increased to 65% and 70% using aqueous solutions of 0.5 and 1.0 mol L^?1 acetic acid. Increase of temperature also had a positive effect on the final degree of hydration. When the treatment was carried out with 0.5 mol L^?1 acetic acid, the hydration increased from 50 to 65 and 80% at 25, 50 and 90 °C respectively. Accordingly under the optimum conditions of 90 °C and 0.5 mol L^?1 acetic acid 80% hydration was achieved within 8 h. CONCLUSIONS: The results showed that much shorter hydration times are possible and therefore an industrial alternative to the spontaneous process could satisfy an increasing demand for magnesium hydroxide. Moreover, agitation is not needed as the reaction is chemically controlled. Copyright © 2012 Society of Chemical Industry     

Electrical Properties of 10 MeV Electron Beam Irradiated and Aged Low Density Polyethylene

Polymers play a very important role in electrical systems as insulation materials. The microscopic failures occurring in the polymer under working conditions will be important in its required characteristics. In this work we focused on the effects of accelerated aging on the electrical properties of low density polyethylene (LDPE) and crosslinked polyethylene (XLDPE). The samples of LDPE were prepared in sheet form with the thickness of 0.6 ± 0.1 mm and were irradiated under the 10 MeV electron beam of a Rhodotron accelerator at the dose range of 70 to 370 kGy. Then, the samples were stored in an oven at temperature 75°C for 3, 6, 10 and 13 days. Electrical properties such as the breakdown voltage and resistance of the aged samples were measured and compared. Increasing the aging time for unirradiated samples has a serious and moderate influence on their surface resistivity and breakdown voltage, respectively. The results indicated a maximum value for the surface resistance at the optimum radiation absorbed dose, which is approximately 220 kGy for all the samples.