Analysis of Symmetric Dual Switch Converter under High Switching Frequency Conditions

Electric vehicle batteries have the problem of low output voltage, so the application of a high-gain converter is a research hotspot. The symmetrical dual-switch high gain converter has the merits of simple structure, low voltage and current stress, and low EMI. Due to the deterioration of circuit performance caused by circuit parasitic parameters under high frequency operating conditions, the former analysis under low frequency condition cannot satisfy the requirements for performance evaluation. To clarify whether the symmetrical dual-switch high-gain converter can maintain its operating characteristics under high-frequency operating conditions, this paper establishes the converter model considering parasitic parameters, and deduces the sneak circuit modes at high frequency. The effects of parasitic parameters at high frequency on voltage gain, switch stress, and symmetrical operating are analyzed, which is beneficial for the selection and optimization of power devices. This paper believes that considering parasitic parameters may reduce the output gain of the symmetrical double-switch high-gain converter considering parasitic parameters under high frequency conditions, increase the switching stress, and affect the symmetry of the circuit operation when the parasitic parameter values are different. Finally, an experimental platform rated on 200 W with 200 kHz switching frequency is established, and experimental verification is given to verify the analysis

Spraying foliar selenium fertilizer on quality of table grape (Vitisvinifera L.) from different source varieties

Table grape is a fruit well suited for consumption as fresh-cut product. Selenium (Se) is an essential min-eral nutrient for human growth, and Se-deficiency is a worldwide nutrition problem. Meanwhile, withSe-enriched fruits is becoming more and more popularity, improving Se content and fruit quality in grapeis especially important for human health. Se content of grape berries was increased by Se fertilizer appli-cation, the maximum Se content and raise ratio of European and American species was 34.96 ug kg−1FWand 36.88% respectively, higher than those of Eurasian species 19.46 ug kg−1FW and 21.40%. In addition,Se fertilizer increased nutrition quality, including soluble sugar, Vc, soluble protein, soluble solid, reducedorganic acid, while it had no effect on polyphenol antioxidants of Eurasian species. K and Ca content ofgrape berries was significantly increased, and reduced accumulation of heavy metals Pb, Cr, Cd, As, Ni. Sein fruits was positively related to fruit quality, and negatively correlation of heavy metals. In conclusion,Se fertilizer can be used to increase Se content of grape, especially for European and American species,with significant effect of increasing grape nutrition quality and an effective means of lowering heavymetals

Template-Mediated Synthesis of Hierarchically Porous Metal–Organic Frameworks for Efficient CO2/N2 Separation

Carbon dioxide (CO2) is generally unavoidable during the production of fuel gases such as hydrogen (H2) from steam reformation and syngas composed of carbon monoxide (CO) and hydrogen (H2). Efficient separation of CO2 from these gases is highly important to improve the energetic utilization efficiency and prevent poisoning during specific applications. Metal–organic frameworks (MOFs), featuring ordered porous frameworks, high surface areas and tunable pore structures, are emerging porous materials utilized as solid adsorbents for efficient CO2 capture and separation. Furthermore, the construction of hierarchical MOFs with micropores and mesopores could further promote the dynamic separation processes, accelerating the diffusion of gas flow and exposing more adsorptive pore surface. Herein, we report a simple, efficient, one-pot template-mediated strategy to fabricate a hierarchically porous CuBTC (CuBTC-Water, BTC = 1,3,5-benzenetricarboxylate) for CO2 separation, which demonstrates abundant mesopores and the superb dynamic separation ability of CO2/N2. Therefore, CuBTC-Water demonstrated a CO2 uptake of 180.529 cm3 g−1 at 273 K and 1 bar, and 94.147 cm3 g−1 at 298 K and 1 bar, with selectivity for CO2/N2 mixtures as high as 56.547 at 273 K, much higher than microporous CuBTC. This work opens up a novel avenue to facilely fabricate hierarchically porous MOFs through one-pot synthesis for efficient dynamic CO2 separation

Tailoring Amine-Functionalized Ti-MOFs via a Mixed Ligands Strategy for High-Efficiency CO2 Capture

Amine-functionalized metal-organic frameworks (MOFs) are a promising strategy for the high-efficiency capture and separation of CO2. In this work, by tuning the ratio of 1,3,5-benzenetricarboxylic acid (H3BTC) to 5-aminoisophthalic acid (5-NH2-H2IPA), we designed and synthesized a series of amine-functionalized highly stable Ti-based MOFs (named MIP-207-NH2-n, in which n represents 15%, 25%, 50%, 60%, and 100%). The structural analysis shows that the original framework of MIP-207 in the MIP-207-NH2-n (n = 15%, 25%, and 50%) MOFs remains intact when the mole ratio of ligand H3BTC to 5-NH2-H2IPA is less than 1 to 1 in the resulting MOFs. By the introduction of amino groups, MIP-207-NH2-25% demonstrates outstanding CO2 capture performance up to 3.96 and 2.91 mmol g−1, 20.7% and 43.3% higher than those of unmodified MIP-207 at 0 and 25 °C, respectively. Furthermore, the breakthrough experiment indicates that the dynamic CO2 adsorption capacity and CO2/N2 separation factors of MIP-207-NH2-25% are increased by about 25% and 15%, respectively. This work provides an additional strategy to construct amine-functionalized MOFs with the maintenance of the original MOF structure and high performance of CO2 capture and separation

Changes in sugar content and related enzyme activities in table grape (Vitis vinifera L.) in response to foliar selenium fertilizer

BACKGROUNDSpraying selenium (Se) fertilizer is an effective method for Se-enriched fruit production. Sugar content in fruit is the major factor determining berry quality. However, changes in sugar metabolism in response to Se fertilizer are unclear. Hence, this study was conducted to identify the effects of Se fertilizer on sugar metabolism and related enzyme activities of grape berries. Additionally, production of leaves with and without Se fertilizer was also investigated. RESULTSAcid invertase (AI) activity, total soluble sugar and Se content in berries, and photosynthetic rate in leaves produced under Se fertilizer treatments were higher than that of control. Glucose and fructose were the primary sugars in berries, with a trace of sucrose. In both berries and leaves, neutral invertase activity was lower than AI, there was no significant difference in neutral invertase, sucrose synthase and sucrose phosphate synthase between Se fertilizer-treated and control. In berries, AI showed a significant positive correlation with glucose and fructose; also Se content was significantly correlated with sugar content. CONCLUSIONAI played an important role in the process of sugar accumulation in berries; high AI activity in berries and photosynthetic rate in leaves could explain the mechanism by which Se fertilizer affected sugar accumulation in berries. (c) 2017 Society of Chemical Industr

Treatment of cholestatic fibrosis by altering gene expression of Cthrc1: Implications for autoimmune and non-autoimmune liver disease

Collagen triple helix repeat containing-1 (Cthrc1) is a documented specific inhibitor of TGF-β signaling. Based on this observation, we developed the hypothesis that knocking in/knocking out the Cthrc1 gene in murine models of cholestasis would alter the natural history of cholestatic fibrosis. To study this thesis, we studied two murine models of fibrosis, first, common bile duct ligation (CBDL) and second, feeding of 3, 5-diethoxy-carbonyl-1, 4-dihydrocollidine (DDC). In both models, we administered well-defined adenoviral vectors that expressed either Cthrc1 or, alternatively, a short hairpin RNA (shRNA)-targeting Cthrc1 either before or after establishment of fibrosis. Importantly, when Cthrc1 gene expression was enhanced, we noted a significant improvement of hepatic fibrosis, both microscopically and by analysis of fibrotic gene expression. In contrast, when Cthrc1 gene expression was deleted, there was a significant exacerbation of fibrosis. To identify the mechanism of action of these significant effects produced by knocking in/knocking out Cthrc gene expression, we thence studied the interaction of Cthrc1 gene expression using hepatic stellate cells (HSCs) and human LX-2 cells. Importantly, we demonstrate that Cthrc1 is induced by TGF-β1 via phospho-Smad3 binding to the promoter with subsequent transcription activation. In addition, we demonstrate that Cthrc1 inhibits TGF-β signaling by accelerating degradation of phospho-Smad3 through a proteosomal pathway. Importantly, the anti-fibrotic effects can be recapitulated with a truncated fragment of Cthrc1. In conclusion, our findings uncover a critical negative feedback regulatory loop in which TGF-β1 induces Cthrc1, which can attenuate fibrosis by accelerating degradation of phospho-Smad3