465 research outputs found

    Dynamic of Soil Mesofauna of Fixed Sand Dunes on the Songnen Grasslands, Northeastern China

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    Grasslands cover vast land areas in semi-arid and semi-humid regions. Sand dunes, most of which are fixed sand dunes, form a large portion of grasslands. Vegetation on fixed sand dunes is an important part of grassland ecosystem productivity, and topographic position is one of the important factors resulting in the differences among vegetation, soil, etc. (Sakai and Ohsawa, 1994; Nagamatsu and Miura, 1997). An important component of soil fauna ecology is to analyze the distribution of soil fauna and its influencing factors. On the small scale, the ozone factors become the dominant factor affecting the soil fauna (Frouz et al., 2011). Topographic position is an important factor affecting the distribution of soil fauna on fixed sand dunes (Xin et al., 2013). This paper takes fixed sand dunes on the Songnen Grasslands as the research objects, and aims to determine the structure and diversity of soil mesofauna on the different positions of the fixed sand dunes

    Uniaxial and Mixed Orientations of Poly(ethylene oxide) in Nanoporous Alumina Studied by X-ray Pole Figure Analysis

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    The orientation of polymers under confinement is a basic, yet not fully understood phenomenon. In this work, the texture of poly(ethylene oxide) (PEO) infiltrated in nanoporous anodic alumina oxide (AAO) templates was investigated by X-ray pole figures. The influence of geometry and crystallization conditions, such as pore diameter, aspect ratio, and cooling rates, was systematically examined. All the samples exhibited a single, volume-dependent crystallization temperature (Tc) at temperatures much lower than that exhibited by bulk PEO, indicating “clean” microdomains without detectable heterogeneous nucleation. An “orientation diagram” was established to account for the experimental observations. Under very high cooling rates (quenching), crystallization of PEO within AAO was nucleation-controlled, adopting a random distribution of crystallites. Under low cooling rates, growth kinetics played a decisive role on the crystal orientation. A relatively faster cooling rate (10 °C/min) and/or smaller pores lead to the * ║ pore axis (n⃗) mode (uniaxial orientation). When the cooling rate was lower (1 °C/min), and/or the pores were larger, a mixed orientation, with a coexistence of * ║ n⃗ and * ║ n⃗ , was observed. The results favor the kinetic model where the fastest growth direction tends to align parallel to the pore axis.This work is supported by the National Natural Science Foundation of China (NSFC, 21873109, 51820105005, 21274156). G. L. is grateful to the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2015026). G. L., D. W., and A. J. M. also acknowledge European funding by the RISE BIODEST project (H2020-MSCA-RISE-2017-778092). The authors thank Dr. Zhongkai Yang for assistance with pole figure measurement

    Effectiveness and safety of Compound Danshen injection as treatment for pregnancy-induced hypertension: A metaanalysis

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    Purpose: To systematically evaluate the effectiveness and safety of Compound Danshen injection in patients with pregnancy-induced hypertension (PIH).Methods: PubMed, Embase, Cochrane Library, Chinese biomedical literature database (CBM), VIP (xiAn), China National Knowledge Infrastructure (CNKI) and Wan Fang databases were searched up to March 20, 2018, for all randomized controlled trials (RCTs) on the use of Compound Danshen injection in patients with PIH. Data were extracted from included studies after assessing the quality of literature. Revman 5.3 software was used for statistical analysis.Results: A total of 18 RCTs involving 1735 patients were included. The results of meta-analysis indicated that the study group was superior to the control group in clinical effectiveness (RR = 1.15, 95 % CI: 1.02 - 1.30); intrauterine fetal distress (RR = 0.26, 95 % CI: 0.09 - 0.70); cesarean section (RR = 0.72, 95 % CI: 0.58 - 0.90), and neonatal asphyxia (RR = 0.23, 95 % CI: 0.11 - 0.48). There were no statistical differences in fetal heart rate abnormalities (RR = 0.58, 95 %, CI: 0.33 - 1.02, p > 0.05) and postpartum hemorrhage (RR = 0.86, 95 % CI: 0.53 - 1.42) between the two groups.Conclusion: Treatment of PIH with Compound Danshen injection (alone or in combination) is superior to the use of conventional western medical treatment in safety and effectiveness. However, higher quality clinical studies are needed to confirm these results because most trials included in this study were of low quality.Keywords: Pregnancy-induced hypertension (PIH), Compound Danshen injection, Meta-analysi

    Dimensionally Stable Anion Exchange Membranes Based on Macromolecular-Cross-Linked Poly(arylene piperidinium) for Water Electrolysis

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    The advancement of anion exchange membranes (AEMs) with superior ionic conductivity has been greatly hindered due to the inherent “trade-off” between membrane swelling and ionic conductivity. To resolve this dilemma, macromolecular covalently cross-linked C-FPVBC-x AEMs were fabricated by combining partially functionalized ether-bond-free polystyrene (FPVBC) with poly(arylene piperidinium). The results from atomic force microscopy reveal that an increase in the ratio of FPVBC promotes the fabrication of microphase separation morphology, resulting in a high ionic conductivity of 40.15 mS cm–1 (30 °C) for the C-FPVBC-1.7 membrane. Molecular dynamics simulations further examine the ionic conduction effect of cross-linked AEMs. Besides, the unique cross-linking structure significantly improves mechanical and alkaline stability. After treatment in 1 M KOH at 50 °C for 1200 h, the C-FPVBC-1.7 membrane shows only a 6.9% decrease in conductivity. The C-FPVBC-1.7 AEM-based water electrolyzer achieves a high current density of 890 mA cm–2 at 2.4 V (80 °C) and maintains good stability, enduring over 100 h at 100 mA cm–2 (50 °C). These results demonstrate the significant potential of macromolecularly cross-linked AEMs for practical applications in water electrolysis

    The influence of passivation and photovoltaic properties of α-Si:H coverage on silicon nanowire array solar cells

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    Silicon nanowire (SiNW) arrays for radial p-n junction solar cells offer potential advantages of light trapping effects and quick charge collection. Nevertheless, lower open circuit voltages (V(oc)) lead to lower energy conversion efficiencies. In such cases, the performance of the solar cells depends critically on the quality of the SiNW interfaces. In this study, SiNW core-shell solar cells have been fabricated by growing crystalline silicon (c-Si) nanowires via the metal-assisted chemical etching method and by depositing hydrogenated amorphous silicon (α-Si:H) via the plasma-enhanced chemical vapor deposition (PECVD) method. The influence of deposition parameters on the coverage and, consequently, the passivation and photovoltaic properties of α-Si:H layers on SiNW solar cells have been analyzed

    4-Meth­oxy-3-nitro­biphen­yl

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    In the title compound, C13H11NO3, the dihedral angle between the two benzene rings is 36.69 (2)° and the nitro and methy­oxy groups are oriented at 29.12 (14) and 2.14 (12)° with respect to the benzene ring to which they are bonded
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