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Development of non-precious metal catalysts for oxygen reduction reaction (ORR) is of great importance due to their significant potential application in energy converting and storing devices. In this work, based on the simple and low-cost N2 structure tetraethylenepentamine (TEPA) ligand, a class of non-precious metal catalyst is prepared from pyrolyzing cobalt tetraethylenepen-tamine chelate on carbon (CoTEPA/C) at 800°C in high purity N2. It indicates that the cobalt-nitrogen chelate decomposes and metallic Co nanoparticles are present after pyrolysis. The optimizedCoTEPA/C catalyst is found at the nominal mole ratio of Co:TEPA = 1:4 with more defect degree and smaller Co particles. For this catalyst, the nitrogen content is 1.12 at% mainly in pyridinic-N form. Electrochemical results show that this catalyst has a good catalytic activity and selectivity to water (4e reaction pathway) both in acid and alkaline electrolytes among the potential we studied. Furthermore, a better catalytic performance in terms of ORR peak potential (0.973 V vs. RHE), onset potential, half-wave potential and selectivity to water in alkaline medium is displayed. [ABSTRACT FROM AUTHOR]

Electrochemical and X-ray absorption techniques are applied to determine the influence of pyrolysis and nitrogen-containing precursor loading on the catalytic activity and structure of carbon-supported cobalt triethylenetetramine (CoTETA/C) catalyst. These CoTETA/C catalysts with different nitrogen-containing precursor loadings are synthesized from pyrolyzing cobalt triethylenetetramine supported on carbon at 800°C in Ar atmosphere. For comparison, the as-prepared (without pyrolysis) is also studied. Cyclic voltammograms and rotating disk electrode measurements indicate that the as-prepared presents very low activity, while the CoTETA/C catalysts with different nitrogen-containing precursor loadings show good catalytic activity and the maximum is found for CoTETA/C catalyst with Co:TETA = 1:4. X-ray absorption measurements at Co and N K edges show that after pyrolysis the CoN4 centers are no longer detected along with little nitrogen atoms inserted into carbon matrix and nanometallic α-Co clusters are formed. X-ray diffraction also confirms the presence of nanometallic α-Co particles on the catalysts. [ABSTRACT FROM AUTHOR]

The definition of cluster supply chain (CSC) is proposed to help small and medium-sized enterprises (SMEs) realize "ant colony effect" and gain more profits. Considering CSC is a complex adaptive dynamic system, it is still in the initial stage and the problem of evolution is difficult to solve by static method. This paper builds a two-stage supply chain evolution model based on computational experiment and generates Agent models. The evolution model is extended to three-stage supply chain model in simulation to research the influence factors of network evolution and predict the effectiveness of service support system, supporting the development of CSC. Preliminary results show that the evolution model can provide the reference for the development of CSC. [ABSTRACT FROM AUTHOR]

Background We previously identified TrkB as an oncogene involved in promoting metastasis in endometrial carcinoma (EC). Here, we sought to delineate the effect of changes in TrkB expression on the global profile of microRNAs (miRNAs) in EC cells and further investigated the correlation between the expression of certain miRNA and TrkB in the clinicopathologic characteristics of EC patients. Methods and results Using quantitative reverse transcription-PCR (qRT-PCR), we found that expression of TrkB mRNA has no significant difference in transcript levels between normal endometrium and EC cells captured by laser capture microdissection, while immunohistochemistry results demonstrated a markedly higher expression of TrkB protein in EC tissues. The microRNA array showed that ectopic overexpression and knockdown of TrkB expression caused global changes in miRNA expression in EC cells. qRT-PCR results showed that elevated TrkB repressed miR-204-5p expression in EC cells. Furthermore, immunoblotting assays revealed that TrkB overexpression in IshikawaTrkB cells noticeably increased JAK2 and STAT3 phosphorylation, which, however, was aborted by TrkB knockdown in HEC-1BshTrkB cells. Moreover, ChIP assays showed that phospho-STAT3 could directly bind to STAT3-binding sites near the TRPM3 promoter region upstream of miR-204-5p. Interestingly, using bioinformatics analysis and luciferase assays, we identified TrkB was a novel target of miR- 204-5p. Functionally, the MTT assays, clonogenic and Transwell assays showed that miR- 204-5p significantly suppressed the clonogenic growth, migration and invasion of EC cells. Furthermore, miR-204-5p also inhibited the growth of tumor xenografts bearing human EC cells. Importantly, we found lower miR-204-5p expression was associated with advanced FIGO stages, lymph node metastasis and probably a lower chance for survival in EC patients. Conclusions This study uncovers a new regulatory loop involving TrkB/miR-204-5p that is critical to the tumorigenesis of EC and proposes that reestablishment of miR-204-5p expression could be explored as a potential new therapeutic target for this disease. [ABSTRACT FROM AUTHOR]

The article presents a study which aims to understand the influence of specific steps on genotoxicity and toxicity during surface water treatment in a water treatment plant in China with liquid chlorine as the disinfectant. The study shows that prechlorination and postchlorination steps increase DNA damage and oxidative stress. It highlights the usefulness of comet and oxidative stress assays in evaluating surface water genetoxicity during drinking water treatment.

Hybrid PTFE/Kevlar fabric was treated by cryogenic approach. The untreated or cryo-treated fabric was incorporated into fabric/phenolic composite for friction and wear tests. It was found that the wear resistance of the fabric/phenolic composite was improved after cryo-treatment, although the friction coefficient increased to a certain extent. SEM observations showed that the roughness of hybrid fabric increased by cryo-treatment, which may enhance the mechanical interlocking of the phenolic resin on the fiber surface. Enhanced fiber/resin adhesion was considered to contribute to the improved wear resistance of cryo-treated fabric/phenolic composite. [ABSTRACT FROM AUTHOR]

Choriocarcinoma is a unique malignant neoplasm composed of mononuclear cytotrophoblasts and multinucleated syncytiotrophoblasts that produce human chorionic gonadotrophin. Choriocarcinoma can occur after a pregnancy, as a component of germ cell tumors, or in association with a poorly differentiated somatic carcinoma, each with distinct clinical features. Cytogenetic and molecular studies, predominantly on gestational choriocarcinoma, revealed the impact of oncogenes, tumor suppressor genes and imprinting genes on its pathogenesis. The role of stem cells in various types of choriocarcinoma has been studied recently. This review will discuss how such knowledge can enhance our understanding of the pathogenesis of choriocarcinoma, enable exploration of novel anti choriocarcinoma targeted therapy and possibly improve our insight on embryological and placental development. [ABSTRACT FROM AUTHOR]

The article discusses polymer engineering research wherein titanium dioxide (TiO2) was chemically grafted by covalently introducing glycidoxy-propyltrimethoxy silicane followed by polyoxymethylene to overcome disadvantages generated by the agglomeration of nanoparticles. Both modified and unmodified TiO2 nanoparticles were introduced into hybrid polytetrafluoroethylene (PTFE)/cotton fabric composites. Fabric composites filled with grafted nanoparticles showed a lower wear rate due to the disintegration of agglomeration and improved interfacial adhesion between the filler/matrix.

Abstract  Effects of low-molecular-weight organic acids on the accumulation and transportation of gadolinium (Gd) in tomato plants were studied under hydroponic condition. The results indicated that changes of organic acids occurred in the processes of Gd accumulation and transportation in tomato plants which were treated with extraneous Gd solutions. Malic, citric, and succinic acids contributed to both Gd accumulation in roots and transportation in xylem vessels. When Gd was unloaded from the xylem to the leaf cells, formic, lactic, citric, and succinic acids played important roles in Gd accumulation in leaves. When tomato plants were cultured in the uptake solution of Gd-containing malic, citric, or succinic acid for 48 h, the succinic acid in roots and leaves and the malic acid in xylem saps both increased obviously. From the results above, we can conclude that succinic acid had the most important role in Gd accumulation in tomato roots and leaves, while malic acid transported Gd via xylem vessels more effectively. [ABSTRACT FROM AUTHOR]

We have performed systematic spectroscopic titrations to characterize the binding reaction of cationic meso-tetrakis(4-(N-methylpyridiumyl))porphyrin (TMPyP4) with the G-quadruplex (G4) of human telomeric single-strand oligonucleotide d[TAGGG(TTAGGG)3T] (S24), for which special effort was made to examine the TMPyP4-G4 binding stoichiometry, the binding modes, and the conformational conversion of the G4 structure under different potassium ion (K+) concentration. It is found that, in the presence of 0, 10 mM, and 100 mM K+, TMPyP4 forms a complex with the anti-parallel G4 in a TMPyP4-to-G4 molar ratio of 5, 5 and 3, respectively, and the increase of K+ concentration would reduce the binding affinity of TMPyP4 to G4. For the TMPyP4–G4 complex, the end-stacking mode and groove binding mode were presumed mainly by the results of time-resolved fluorescence spectroscopy in the three cases. Most importantly, it is found that TMPyP4 can directly induce the formation of the anti-parallel G4 structure from the single-strand oligonucleotide S24 in the absence of K+, and that it can preferentially induce the conformational conversion of the G4 structure from the hybrid-type to the anti-parallel one in the presence of K+. [ABSTRACT FROM AUTHOR]

A simple, sensitive and low-cost method was developed for the determination of aspartate (Asp) and glutamate (Glu) in rabbit retina. Polymer monolith microextraction (PMME) using a poly(acrylamide–vinylpyridine– N,N′-methylene bisacrylamide) (AA–VP–Bis) monolithic column was combined with derivatization of Asp and Glu using 8-phenyl-(4-oxy-acetic acid N-hydroxysuccinimide ester)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza- s-indacene (TMPAB-OSu), and this was used to analyze the derivatives of Asp and Glu by high-performance liquid chromatography (HPLC) with fluorescence detection. The conditions for the derivatization and the subsequent extraction of Asp and Glu derivatives were optimized. The enrichment factors for the derivatives of Asp and Glu were found to be 14.1 and 14.7, respectively, by PMME. The limits of detection of Asp and Glu were 0.14 and 0.53 nmol/L, respectively. The precision and recovery were evaluated with spiked retina. The inter- and intraday relative standard deviations were less than 10%. The proposed method was successfully applied to the determination of Asp and Glu levels in rabbit retina samples with different stages of intraocular hypertension. [ABSTRACT FROM AUTHOR]

The article presents a study which demonstrates the oxygen reduction reaction activity of cobalt-polypyrrole-toluenesulfonic acid/carbon (Co-PPy-TsOH/C). It states that Co-PPy-TsOH/C is synthesized with p-TsOH-doped PPy/C as a nitrogen (N) rich and morphological support together with cobalt salt. Results show that increase of N-content significantly improve the electrocatalytic activity of Co-PPy-TsOH/C toward ORR compared with Co-PPy/C activity.

To reduce the influence of wind power output uncertainty on power system stable operation, demand response (DRPs) and energy storage system (ESSs) are introduced while solving scheduling optimization problems of system with wind power. To simulate wind power scenarios, this paper used interval method to generate the initial scenario set, and construct scenario reduction strategy based on Kantorovich distance. Then, DRPs and ESSs are respectively introduced in the demand-side and generation side, taking wind power day-ahead forecasting and ultra-short-term forecasting as a random variable and its implementation, a two-stage scheduling optimization model for wind energy storage systems is construct combined with two stage optimization theory. To solve the proposed model, the ergodic of chaos search is applied to improve the inadequate that binary particle swarm algorithm may fall into local optimum, chaotic binary particle swarm optimization algorithm is proposed. Finally, example simulation is made in the IEEE36 node 10 machine systems to analyze the influence of energy storage system and demand response on system's wind power consumptive capacity. The result shows chaotic binary particle swarm algorithm can get a global optimal solution, applicable to solve wind power energy storage systems two-stage model. The synergies of DRPs and ESSs can be used to suppress wind power uncertainty, improve the utilization efficiency of wind power, and reduce coal consumption level with significantly overall efficiency. [ABSTRACT FROM AUTHOR]