Effects of high hydrostatic pressure on the structure and retrogradation inhibition of oat starch

As a non-thermal processing technology, high hydrostatic pressure (HHP) can be used for starch modification without affecting the quality and flavour constituents. The effect of HHP on starch is closely related to the treatment pressure of HHP. In this paper, we investigated the impacts of HHP treatment pressure (0, 100, 200, 300, 400, 500, 600 MPa) on the microstructure and retrogradation characteristics of oat starch, established the retrogradation kinetic model and elaborated the mechanism of HHP treatment inhibiting the retrogradation of oat starch. Results show that HHP treatment caused the microstructure of oat starch experienced crystallisation perfection (100–300 MPa), crystallisation destruction (400 MPa), crystallisation disintegration and gelatinisation (500–600 MPa). Results of oat starch retrogradation showed that, after treated at 500 MPa for 15 min, the recrystallisation rate of oat starch was reduced, the formation of nuclei at the early stage of oat starch retrogradation suppressed and its nucleation mode was changed from instantaneous to spontaneous, otherwise, the mobility of water in oat starch gel system reduced. Therefore, 500 MPa treated for 15 min can inhibits the retrogradation of oat starch. This study provides theoretical guidance for the application of HHP technology in starch modification and food processing.     

Microstructural refinement and mechanical response of Al2O3–ZrO2 eutectics fabricated by a novel pulse discharge plasma assisted melting method

In the present work, microstructural refinement and mechanical response of Al₂O₃–ZrO₂ eutectics fabricated by a pulse discharge plasma assisted melting (PDPAM) method were investigated. The solidified microstructure evolves from polygonal eutectic colonies into irregular cellular colonies with increasing the superheating temperature of the melt from 1820 °C to 1900 °C. The average eutectic spacing inside the colonies decreases from 1.80 ± 0.10 μm to 0.25 ± 0.06 μm, and the coarse inter-colonial structure is refined, which is attributed to the increase in undercooling temperature. High-temperature microstructural stability of Al₂O₃–ZrO₂ eutectics is improved significantly as contrasted with the as-sintered ceramics. Besides, the load dependence of Vickers hardness for Al₂O₃–ZrO₂ eutectics is investigated.     

MnS掺杂多孔碳复合材料的制备及电化学性能（两张发票1000+2500）

褐煤作为低级煤资源利用率不高，但褐煤中具有腐植酸成分，将褐煤中提取的腐植酸作为化肥原料，提取后剩余残渣作为碳源，与MnS纳米粒子制备了MnS@C复合材料。采用XRD、拉曼光谱、XPS、N2吸附-脱附、SEM和TEM对样品进行了表征。将该复合材料应用于锂离子电池负极材料，对其电化学性能进行了测试。结果表明，MnS@C复合材料的比表面积和孔容分别为117.19m2/g和0.044mL/g，该电极在0.1 A/g电流密度条件下循环200次后比容量高达830 mA‧h/g，且电极容量保持率为99%左右。在0.2、0.4、0.8、1.0、1.2和1.6 A/g电流密度下比容量分别为644、522、427、399、373和348mAh/g，展现出良好的倍率性能。MnS@C复合材料优异的电化学性能得益于碳基体的存在，不仅可以缓解MnS纳米粒子在嵌锂/脱锂过程中的体积膨胀，而且展示了锂离子电池高性能的巨大潜力，为褐煤的高值化利用作出巨大贡献。     

西藏燕麦主要种植区灌溉定额空间分布及影响因素

燕麦为西藏自治区典型牧草之一,由于种植区地域辽阔,灌溉试验结果受限,西藏燕麦主要种植区的灌溉定额尚不明确。本文在西藏燕麦主要种植区内选取28个典型站点进行资料收集,遵循农业气候相似原则进行区域划分,基于水量平衡法揭示了西藏燕麦主要种植区灌溉定额的空间分布特征,并根据统计学原理分析了其影响因素。研究表明:燕麦主要种植区的灌溉定额呈由西藏中部至东部呈现先递增后递减的趋势,50%水文年下的燕麦灌溉定额在56~265 mm之间变化。降雨量是影响研究区内燕麦灌溉定额的主要因素(R²为0.515),ET₀次之(R²为0.152);其它气象因素中,日照时数对研究区燕麦灌溉定额影响较大(R²为0.462),且呈正相关关系;相对湿度对燕麦灌溉定额影响较小。西藏燕麦主要种植区的灌溉定额及其空间分布可为西藏自治区灌溉用水管理提供支撑。     

Influence of size and shape on optical properties of cesium tungsten bronze: An experimental and theoretical approach

Although the optical properties of nanocrystalline cesium tungsten bronze have been widely studied, there is a lack of research on the effect of particle size on its optical properties. In order to further investigate size and shape effect on the NIR shielding performance, cesium tungsten bronze nanoparticles with different sizes and morphologies were prepared by two methods. The size of irregular shaped samples prepared by solvothermal method is tens of nanometers, while the size of hexagonal prism shaped samples prepared by solid state reaction method is hundreds of nanometers. The element spectrums shows that there are more oxygen vacancies in large particles than in small particles. The NIR shielding performance of large particles far lower than that of small particles, indicating that the influence of shape and size on optical properties is more obvious than that of oxygen vacancy. Theoretical calculation on hexagonal prism shaped particles exhibits that the NIR extinction of large aspect ratio is better at longer wavelength and small aspect ratio is better at shorter wavelength.     

Ni2V2O7 dandelion microsphere for a high-performance electrocatalyst in water splitting

Water splitting is an effective way to produce hydrogen to solve the energy crisis problem, and inorganic metal compounds are widely used in electrocatalysis field due to efficient hydrogen evolution reaction (HER). Herein, we synthesize Ni₂V₂O₇ dandelion microsphere from nickel nitrate and vanadium pentoxide by “one-step hydrothermal” way, which exhibits large specific surface area of 102.74 m² g⁻¹. The as-prepared Ni₂V₂O₇ microsphere shows good electrocatalysis performances including OER overpotential of 358 mV and good stability, as well as HER overpotential of 195 mV. Furthermore, the Ni₂V₂O₇ microsphere electrode is assembled to Ni₂V₂O₇ microsphere//Ni₂V₂O₇ microsphere system, showing the water splitting voltage of 1.50 V at 10 mA cm⁻² by two-electrode method, which is much lower than those of commercial RuO₂//Pt/C system and most of spinel oxides electrocatalysts. Our work opens up a new and facile avenue for fabricating inorganic microsphere electrocatalyst in hydrogen production field.     

Raman and X-ray photoelectron spectroscopy study on the influence of La2O3 on the melt structure of SiO2–CaO–Al2O3–MgO

In order to gain more insights into the influence of rare earth elements on the melt structure of SiO₂–CaO–Al₂O₃–MgO glass ceramics, Raman and X-ray photoelectron spectroscopy techniques were used to study the influence of La₂O₃ on the Si–O/Al–O tetrahedron structure within SiO₂–CaO–Al₂O₃–MgO–quenched glass samples in this study. Results showed that some Raman peak shapes at low frequencies (200–840 cm^?1) changed significantly after the addition of La₂O₃, compared to the high frequency (840–1200 cm^?1) region that corresponds to the [SiO₄] structure, suggesting that the depolymerization of the low-frequency T–O–T (T=Si or Al) structure was more prevalent with La³⁺ addition. Besides, the depolymerization extent of the Si–O/Al–O tetrahedral network varied when the melt composition altered. Most notably, depolymerization is the most significant at a low CaO/SiO₂ ratio (0.25) and a high Al₂O₃ content (8%). Meanwhile, La³⁺ can promote the transformation of Si–O–Si and Al–O–Al bonds to the Si–O–Al ones, thereby forming a complex ionic cluster network interwoven with Si–O and Al–O tetrahedrons.     

Development of a non-target metabolomics-based screening method for elucidating metabolic and probiotic potential of bifidobacteria

Traditional in vitro screening assays for identifying probiotics often fail to provide a metabolomic overview of candidate strains. Thus, this work aimed to develop a non-target metabolomics-based method for screening bifidobacteria from a broad perspective. First, methods for extracting intracellular metabolites of bifidobacteria were compared. Methanol extraction with bead mill and sonication was selected as it yielded the highest metabolome signal intensity and coverage. Multivariate analyses revealed obvious differences in the intracellular metabolome between species/strains. Fourteen differential metabolites that have previously been reported to possess probiotic function were identified. Bifidobacterium animalis subsp. lactis Probio-M8 (M8) had significantly more intracellular lactose than other species/strains but showed lower cell density and viable counts in stationary phase. Adding lactose in the culture medium significantly enhanced the growth of M8 strain but not other tested bifidobacteria. This work provided a new screening method and practical data for selecting potential candidates for further validation.     

Simplification and applicability studies of a hydrogen-air detailed reaction mechanism

The research of hydrogen fuel internal combustion engine (HICE) had great significance facing the challenges of energy and environmental problems. Based on the detailed hydrogen-air reaction mechanism, the pre-mix model of CHEMKIN-Pro software was selected to simplify the detailed mechanism GRI-3.0. The most important elements and reactions was chose to construct framework mechanism firstly based on the sensitivity coefficient for H₂O and NO formation, and additional elements and reactions were added to framework mechanism for complementing the oxidation path of N2 and H₂. A simplified mechanism including 24-step elementary reaction was obtained and the laminar burning velocity calculated by this simplified mechanism matches well with the detailed mechanism in a wide range. This simplified mechanism was also applied in a CFD model which predicted the cylinder instantaneous pressure and NOx emission accurately within a large range of fuel air equivalent ratio. Showing that this mechanism has good applicability.     

配加蒙古精矿对球团矿性能的影响

对蒙古精矿在包钢624 m2带式球团的合理利用进行了全面研究。研究表明，随着蒙古精矿配比增加，球团矿品位提高，还原膨胀率增加，当配比小于20%时，还原膨胀率小于20.0%，主要是由于还原后球团矿矿物组成中析出大量金属铁，在浮氏体(FexO)转变为铁的阶段，铁晶粒自浮士体表面向外长出晶须，晶须的生长让晶粒产生位移或晶粒开裂，导致球团结构疏松发生膨胀。通过添加适量矽石，可显著降低球团还原膨胀率，当配加30%～50%的蒙古精矿时，可通过添加1.0%～2.0%的矽石，将球团还原膨胀率降低至20%以内，球团矿质量满足高炉冶炼生产要求。