Ultrafine Ir Nanowires with Microporous Channels and Superior Electrocatalytic Activity for Oxygen Evolution Reaction

Hydrogen energy is considered as an ideal candidate energy of traditional fossil fuels. Oxygen evolution reaction (OER) is a crucial reaction for the sustainable hydrogen generation as a half reaction of water splitting. It is important to develop efficient electrocatalysts for the OER. Herein, the porous iridium nanowires (Ir PNWs) with polyallylamine hydrochloride (PAH) as a complex-forming agent and capping agent have been successfully synthesized through a one-pot hydrothermal approach. Benefiting from the inherent anisotropic characteristic of one-dimensional nanowires structure, abundant microporous channels and high atom utilization efficiency, the synthesized Ir PNWs possess very large electrochemically active surface area (118.2 m(2) g(-1)), and thus exhibit superior electrocatalytic activity and stability towards the OER compared with commercial RuO2 catalyst and other Ir nanocrystals

A Fault Diagnosis Method for Rotating Machinery Based on PCA and Morlet Kernel SVM

A novel method to solve the rotating machinery fault diagnosis problem is proposed, which is based on principal components analysis (PCA) to extract the characteristic features and the Morlet kernel support vector machine (MSVM) to achieve the fault classification. Firstly, the gathered vibration signals were decomposed by the empirical mode decomposition (EMD) to obtain the corresponding intrinsic mode function (IMF). The EMD energy entropy that includes dominant fault information is defined as the characteristic features. However, the extracted features remained high-dimensional, and excessive redundant information still existed. So, the PCA is introduced to extract the characteristic features and reduce the dimension. The characteristic features are input into the MSVM to train and construct the running state identification model; the rotating machinery running state identification is realized. The running states of a bearing normal inner race and several inner races with different degree of fault were recognized; the results validate the effectiveness of the proposed algorithm

Minimum current stress operation of dual active half-bridge converter using triple phase shift control for renewable energy applications

With the development of renewable energy, dual active half bridge (DAHB) has been widely used in renewable energy systems. For the purpose of reducing the damage caused by excessive current stress and improve the operation performance of the DAHB, this article proposes an optimized strategy of minimum current based on the Karush–Kuhn–Tucker (KKT) method. The expressions of current stress corresponding to each mode are analyzed through mathematical derivation. Then the optimal solution of duty ratios are solved through KKT method. The proposed strategy decreases the current stress and improves the operation conditions compared to conventional single phase shift (SPS) and dual phase shift (DPS). Finally, simulation results conducted to validate the effect of proposed strategy

Discriminating the effects of local stressors from climatic factors and dispersal processes on multiple biodiversity dimensions of macroinvertebrate communities across subtropical drainage basins

Metacommunity ecology emphasizes that community structure and diversity are not only determined by local environmental conditions through environmental filtering, but also by dispersal-related processes, such as mass effects, dispersal limitation and patch dynamics. However, the roles of dispersal processes are typically ignored in bioassessment approaches. Here, we simultaneously explored the potential influences of four groups of factors: local stressors, climatic factors, within-basin spatial factors and basin identity in explaining variation in diversity indices of macroinvertebrate assemblages from seven subtropical tributary rivers. A total of 12 biodiversity indices based on species identities, functional traits and taxonomic relatedness were calculated and used in the subsequent statistical analysis. Our results showed that, although differing in their relative importance, the four explanatory factor groups all played important roles in explaining variation in biodiversity indices. Of the pure fractions, index variation was best explained by local environmental stressors, whereas the other three explanatory factor groups appeared less influential. Furthermore, diversity indices from species, functional and taxonomic dimensions responded distinctly to the focal ecological factors, and differed in their abilities to portray the effects of human disturbances on macroinvertebrate communities. Taxonomic distinctness indices performed best, with the highest amount of variation associated to local stressors and hardly any variation explained by other factors, implying that these indices are robust in portraying human disturbances in streams. However, species diversity and functional diversity indices were also affected by spatial processes and climatic factors, suggesting that these indices should be used with caution in bioassessment. We hence conclude that environmental assessment of riverine ecosystems should not rely entirely on the perspective of species sorting. In contrast, both roles of spatial processes and environmental variables related to human disturbances and climatic variation should be incorporated in management and conservation of riverine ecosystems. (C) 2019 Elsevier B.V. All rights reserved.</p

The Protective Effects of 5-Methoxytryptamine-α-lipoic Acid on Ionizing Radiation-Induced Hematopoietic Injury

Antioxidants are prospective radioprotectors because of their ability to scavenge radiation-induced reactive oxygen species (ROS). The hematopoietic system is widely studied in radiation research because of its high radiosensitivity. In the present study, we describe the beneficial effects of 5-methoxytryptamine-α-lipoic acid (MLA), which was synthesized from melatonin and α-lipoic acid, against radiation-induced hematopoietic injury. MLA administration significantly enhanced the survival rate of mice after 7.2 Gy total body irradiation. The results showed that MLA not only markedly increased the numbers and clonogenic potential of hematopoietic cells but also decreased DNA damage, as determined by flow cytometric analysis of histone H2AX phosphorylation. In addition, MLA decreased the levels of ROS in hematopoietic cells by inhibiting NOX4 expression. These data demonstrate that MLA prevents radiation-induced hematopoietic syndrome by increasing the number and function of and by inhibiting DNA damage and ROS production in hematopoietic cells. These data suggest MLA is beneficial for the protection of radiation injuries