Search

Aim: The aim of this study was to explore the mediating role of perceived social support in the association between perceived stress and job burnout in midwives. Design: A descriptive, cross‐sectional online survey. Methods: Using the stratified cluster sampling method, 329 midwives in 20 hospitals in China were selected as the participants. They completed self‐report assessment measures of job burnout, perceived stress and perceived social support. Results: 63.5% of the participants had job burnout. Perceived stress was negatively associated with social support (r = −.350, p <.01), while it was positively associated with job burnout (r = −.382, p <.01). Social support was negatively correlated with job burnout (r = −.569, p <.01). The total effect of perceived stress on job burnout was 0.474 (95% CI: 0.367 ~ 0.596, p <.01), the direct effect was 0.242 (95% CI: 0.142 ~ 0.355, p <.01), and the indirect effect was 0.232 (95% CI: 0.160 ~ 0.316, p <.01). Social support programmes for midwives should be implemented to control the impact of perceived stress on job burnout. [ABSTRACT FROM AUTHOR]

It is crucial to obtain better fatigue property for the safe application of materials, while nature provides new structural design ideas for effectively improving fatigue property. In this study, a "soft‐hard" alternating bionic structure was fabricated on the surface of TIG welded AZ31B Mg alloy joints by laser bionic treatment (LBT). Microstructure of welded joints was tailored by LBT, resulting in fine equiaxed grains with random orientations and increased microhardness. The fatigue crack growth threshold of the welded joints with bionic structure is increased by more than 40%, and crack growth rate was lower. LBT could significantly affect crack growth behavior and presented obvious crack deflection, resulting in a rougher fracture surface and more second cracks and branches. LBT significantly improved the fatigue crack growth resistance, inducing a series of strengthening mechanisms. The present work opens a new alternative to improve the fatigue properties of welded joints. Highlights: "Soft‐hard" alternating structure was formed in joints by laser bionic treatment (LBT).The refined grains coupled with coarser grains provide the ideal microstructure.Fatigue crack growth resistance of welded joints was improved significantly by LBT.Strengthening mechanisms induced by LBT were discussed. [ABSTRACT FROM AUTHOR]

Ecological flow has attracted considerable attention because intensive dam construction can cause changes in the hydrological situation and subsequent ecological environment problems. In the Hanjiang River basin, 15 cascade reservoirs are due to become operational in the main stream in the coming years. In this study, the calculation method of ecological flow surplus and deficit was proposed, and the key periods (KPs) and key areas (KAs) of ecological flow deficits were identified. Adaptive regulation strategies were proposed based on a new method. Results show that (1) the wet and normal years are in a state of ecological surplus. In the dry year, there is an ecological flow deficit of 370 million m3. The off‐stream ecological water shortage is at its most serious in June. In the river channel, the ecological flow deficit usually appears in the winter. The Xiantao section in the lower reaches has a deficit every month in the typical water years. (2) In the off‐stream region, the KPs cover months 6 to 9, and the KAs are the southeastern Hanzhong plain, Shiyan City, southeastern Nanyang basin, and the midwest of Xiangyang City. In the river channel, the KPs cover months 12 to 2 above the Shayang section, while in the downstream Xiantao section KA, the KP covers the whole year. The cooperative analysis of KPs and KAs can effectively improve the pertinence of watershed ecological flow regulation. Priority for water resources regulation in water deficient areas should be given to key areas in the key periods. [ABSTRACT FROM AUTHOR]

This study focuses on developing an optimal setting method for the first integrated coking flue gas desulphurization and denitration device in China. Maintaining the denitration process in a state of optimal economic efficiency has become an issue in production optimization control. This paper proposes a data‐based two‐stage nonparametric optimization method to optimize the operation of the denitration process. A principal component regression (PCR)‐based multiple case fusion case‐based reasoning (CBR) method is proposed to obtain the initial optimization set points. To overcome the steady‐state modelling difficulties associated with the process, a local modelling method for the coking flue gas denitration process is developed using an improved just‐in‐time learning (JITL) algorithm. Taking the preset values obtained above as the initial value of an active set algorithm, the optimization problem can be solved in a timely and precise manner. The intelligent setting software has been developed for running industrial applications, and the results demonstrate the effectiveness of the proposed optimization approach. [ABSTRACT FROM AUTHOR]

Abstract: Theoretically, metal Sn owns higher initial coulombic efficiency than SnO2 in the sodium‐ion batteries (SIBs). Metal Sn is commonly obtained by the thermal reduction of SnO2 at present. However, the uncontrollable growth of metal Sn particles during the reduction progress is a key challenge. In this work, a composite material of refined metal Sn particles (particle size about 20∼200 nm) and carbon buffer medium has been prepared by a novel method, which is simple thermal reduction adopted after the treatment of SnO2/RGO in the pitch kerosene solution. The results show that this method overcomes the uncontrollable growth of metal Sn particles. Electrochemical tests show that C/Sn/RGO possesses a higher initial reversible capacity of 476.2 mAh g−1, and a higher initial coulombic efficiency of 70.3%. This method would have wider applications for the attractive properties of Na‐ion batteries in the future. [ABSTRACT FROM AUTHOR]

Dissolved gas analysis (DGA) is a prevailing methodology being widely used to detect incipient faults in power transformers. Although various methods have been developed to interpret DGA results, they may sometimes fail to diagnose precisely, especially when solid insulation deterioration is involved. This study presents a time series correlation technique, in which the sampled data of dissolved gases in the transformer oil are considered as a time series and the series correlation scheme in statistics is adopted to explore and manipulate the fault information. Both the constant and variable characteristic parameters are initially chosen based on analysis in terms of frequency histograms. With quantitative correlation analysis between the constant and variable characteristic parameters, a new criterion for solid insulation diagnosis is thereby proposed, which can be used to diagnose whether solid insulation deterioration is involved in a transformer fault, as well as further distinguish the electrical faults from the thermal ones. According to the proposed technique, explorative tests regarding two power transformers have shown promising results. With regard to the 91 fault samples collected from China Power Grid, the diagnosis accuracies for electrical and thermal faults were 86.5 and 77.7%, respectively, whereas it was 61.5% for the prevailing CO2/CO criterion. [ABSTRACT FROM AUTHOR]

ABSTRACT Hydrological characteristics significantly drive the formation of and variations in wetland vegetation. Given increasing impact from human activities and climate change, the hydrological regime has become exceedingly unstable, thereby heavily affecting the distribution and dynamics of wetland vegetation. The relationship between inundation frequency - an important hydrological factor - and vegetation community distribution in Dongting Lake was analysed to depict how the hydrological regime determines the distribution of wetland vegetation cover. Wide tempo-spatial scales were used to calculate the inundation frequency in the lake and to compare the distribution patterns of the communities. For the implementation of the aforementioned tasks, this study provides remote sensing- and geographical information system-based methods. The responses of individual vegetation communities to inundation frequency differ depending on their specific physiological characteristics. Wood and reed communities are more suitable for regions with low inundation frequency, whereas grass and lake-grass communities are more adaptable to areas of high inundation frequency. The variations in inundation frequency may explain the succession of vegetation communities, which occurs when inundation frequency decreases with increasing wood and reed communities. These results can serve as support for evaluating the impact of hydrological changes on the community structures and distributions of wetland vegetation. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Non-point source pollution is a key issue in integrated river basin management around the world and has resulted in water contamination, aquatic ecology deterioration and eutrophication. Xin'anjiang catchment is the key drinking water source area for Hangzhou City, China. A promising model (Soil and Water Assessment Tool) was applied to assess the non-point source pollution and its effect on drinking water. Sensitivity analysis of model parameters was carried out using the Sequential Uncertainty Domain Parameter Fitting 2 sensitivity technique. Water discharge, sediment, total nitrogen and total phosphorus load processes from 2000 to 2010 were simulated, and the spatial distributions of non-point source pollutants were evaluated at the catchment and administrative country levels. The results show that the hydrological parameters of the Soil and Water Assessment Tool were dominantly sensitive for non-point source pollution simulation, including CN2, RCHRG_DP, ALPHA_BF, SOL_AWC, ESCO and SOL_K and the characteristic parameters of sub-basins (viz. HRU_SLP and SLSUBBSN). Also, water quality parameters (viz. CH_EROD, NPERCO, RSDCO and PPERCO, PHOSKD, etc.) have a significant effect on nutrients. The model performance was very satisfactory, especially for runoff, sediment and total phosphorus simulation. The non-point source pollutant load increased from 2001 to 2010 in the whole catchment. Total nitrogen load increased from 3428 tons (0.59 ton km−2) to 7315 tons (1.25 ton km−2), and total phosphorus load increased from 299 tons (0.05 ton km−2) to 867 tons (0.15 ton km−2). The contribution of rice land was the largest, accounting for nearly 95%, followed by tea garden (3.56%), winter wheat (1.37%), forest (0.07%) and grassland (0.02%). Moreover, She County and Xiuning County contributed more than half of the non-point source pollutants. This study was expected to provide a method and reference for non-point source pollution quantification and to support water quality management implementation in China. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The three-dimensional (3D) inorganic-organic hybrid framework cobalt phosphite (C2H6N)[Co1.5(OH)(HPO3)] (CoHPO-CJ10) was synthesized hydrothermally. Its structure is constructed by the connection of CoO6 octahedra, CoO5N octahedra, HPO3 pseudo-pyramids, and 1,4-butanediamine molecules. It exhibits a pillared-layer structure with an unusual Co/P ratio of 3/2. The 1,4-butanediamine molecule acts as a pillar to link the adjacent cobalt phosphite layers to form open framework. Interestingly, such structure contains infinite edge-sharing connected Co-O-Co chains, that are rarely occurred in the structures of cobalt phosphates/phosphites. It was characterized by single-crystal X-ray diffraction, X-ray powder diffraction (XRD), infrared (IR) spectra, UV/Vis spectroscopy, thermal gravimetric analyses (TGA), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), and elemental analyses. It exhibits antiferromagnetic interaction. [ABSTRACT FROM AUTHOR]

The in situ open-circuit voltages ( Voc) and the in situ photoconductivities have been measured to study electron behavior in photocatalysis and its effect on the photocatalytic oxidation of methanol. It was observed that electron injection to the conduction band (CB) of TiO2 under light illumination during photocatalysis includes two sources: from the valence band (VB) of TiO2 and from the methanol molecule. The electron injection from methanol to TiO2 is slower than that directly from the VB, which indicates that the adsorption mode of methanol on the TiO2 surface can change between dark and illuminated states. The electron injection from methanol to the CB of TiO2 leads to the upshift of the Fermi level of electrons in TiO2, which is the thermodynamic driving force of photocatalytic oxidation. It was also found that the charge state of nano-TiO2 is continuously changing during photocatalysis as electrons are injected from methanol to TiO2. Combined with the apparent Langmuir-Hinshelwood kinetic model, the relation between photocatalytic kinetics and electrons in the TiO2 CB was developed and verified experimentally. The photocatalytic rate constant is the variation of the Fermi level with time, based on which a new method was developed to calculate the photocatalytic kinetic rate constant by monitoring the change of Voc with time during photocatalysis. [ABSTRACT FROM AUTHOR]

Allogeneic umbilical cord blood haematopoietic stem cells (UCB-HSCs) can be transplanted into a host with the intact innate immunity with limited immuno-reaction, although the mechanisms remain unclear. The present studies aimed at investigating potential mechanisms of allogeneic UCB-HSCs escape from the cytolysis of natural killer (NK) cells. We compared UCB-HSCs ability to protect from NK-mediated cytotoxicity with peripheral blood or bone marrow haematopoietic stem cells (PB-HSCs and BM-HSCs). HSCs expressed lower levels of natural cytotoxicity receptor ligands including NKp30L, NKp44L and NKp46L than monocytes. Blocking these ligands respectively or in combination could increase the resistance of HSCs against NK cell mediated cytotoxicity. High expression of HLA-G was noticed on UCB-HSCs, rather than PB-HSCs or BM-HSCs, whereas blockade of HLA-G significantly elevated NK cell mediated cytolysis to UCB-HSCs. Thus, we conclude that natural cytotoxicity receptors and HLA-G on HSCs may contribute to the escape from NK cells, and activate and inhibitory NK cell receptors and their ligands can be novel therapeutic targets in cell transplantation. [ABSTRACT FROM AUTHOR]

(dab)[Co3(OH)2(HPO3)2] (dab: 1,4-diaminobutane) is prepared by hydrothermal reaction of Co(OAc)2, H3PO3, and dab (H2O, autoclave, 160 °C, 3 d). [ABSTRACT FROM AUTHOR]