Inquiry of Water-Soluble Polysaccharide Extraction Conditions from Grapefruit Skin

Water-soluble polysaccharide was isolated from grapefruit with the method of water-dissolving and ethanol-precipitating. By single factor test and orthogonal experimental method, the extraction conditions of the water-soluble polysaccharide were investigated, which contained liquid-solid ratio, temperature, time and pH. The results showed that pH was the most important factor of polysaccharide extraction, followed by temperature. The optimized extraction technology conditions were obtained. The liquid-solid ratio was 1:40, temperature was 90?C, time was 2.0 h, and pH was 2. The highest extraction rate of crude polysaccharide was 8.30%.

Particle Kinematics Analysis of Droplet Drift in Spraying Operation of Plant Protection UAV

[Objectives]The paper was to study the effect of droplet drift on spray quality of plant protection UAV.[Methods]Based on the theory of multiphase flow and the method of particle kinematics,the force and motion trajectory of droplet sprayed by plant protection UAV were theoretically analyzed and mathematically modeled.On the basis of the assumption of wind speed in the ground layer and the laminar sublayer,that is,it is assumed that the wind speed in the area of wind measurement was approximately a linear distribution,the coupling iterative solution of the equations was carried out.The influence of droplet diameter,flight height,flight speed of plant protection UAV,course angle,wind speed,wind direction,initial droplet velocity and direction of initial velocity on droplet drift were analyzed.The influence of the coupling effect of each factor on droplet drift was further discussed and the distribution of droplet drift concentration was obtained.[Results]The wind speed and direction had much influence on the drift distance of droplets,and the drift distance and the initial velocity angle show a quadratic function distribution.Under the given conditions,the drift distance was the closest when the initial velocity angle was about 20°.The droplet drift was mainly distributed scatteredly around the nozzle.[Conclusions]The study provides a reference for improving the spraying quality of plant protection UAV.

福建海岛滨海特有植物种–面积关系及物种丰富度决定因素

福建海岛具有丰富的滨海特有植物资源,研究其物种丰富度的分布格局及机制,能够为滨海特有植物资源保护提供依据。本研究探讨了福建53个海岛滨海特有植物的种–面积关系,以及景观、人为干扰和气候3个方面10个环境因子对滨海特有植物物种丰富度的影响。同时还探讨了不同生活型(乔木、灌木、草本)对海岛环境因子的响应。结果表明:滨海特有植物和不同生活型植物的种–面积关系呈现物种丰富度随着面积增加而增加的趋势,滨海特有植物、乔木、灌木和草本的种–面积关系的斜率(z)分别为0.16、0.15、0.15和0.14。景观环境因子中的面积、形状指数和周长面积比是解释福建海岛滨海特有植物及不同生活型植物物种丰富度的主要决定因素,滨海特有植物及各生活型植物物种丰富度随着面积和形状指数的增加而增加,而滨海特有植物、灌木和草本的物种丰富度随着周长面积比的增加而减少。此外,不同生活型植物的物种丰富度对海岛环境因子的响应存在差异,除景观方面的因子外,气候对乔木的解释率最大,达9.82%。综上所述,相比于其他海岛生态系统,福建海岛滨海特有植物及不同生活型植物的物种丰富度与面积密切相关,其较低的斜率(z)表明滨海特有植物对海岛生境的敏感性较弱。景观方面的环境因子相比气候和人为干扰方面贡献了更多的解释率。以往研究发现岛屿环境因子与生境异质性显著相关,如岛屿越大、形状越不规则、周长面积比越低,则生境异质性越高。因此生境异质性的提升可能是解释滨海特有植物丰富度随景观环境因子变化的内在机制。

Development of metal-recycling technology in waste crystalline-silicon solar cells

Solar energy is currently one of the most promising clean energy sources and the use of solar energy has led to a rapid increase in the number of solar cells.As one of the fastest-growing electronic wastes,the resource treatment of solar cells at the end of their life should not be neglected.This review discusses the trend for the market development of crystalline-silicon solar cells and analyzes their physical structure and composition.It also discusses the current domestic and international recycling technologies for crystalline-silicon solar cells,including manual dismantling,inorganic acid dissolution,the combination of heat-treatment and chemical methods,and organic solvent dissolution.The shortcomings of the above treatment methods are discussed and some views on the recycling of waste crystalline-silicon solar cells are presented.Constructive suggestions for the green and sustainable development of crystalline-silicon solar cells are put forward by comparing different treatment-recycling processes.

表达Elafin的益生菌Nissle 1917对小鼠实验性结肠炎的保护作用

目的构建能够表达人重组蛋白Elafin的益生菌大肠杆菌Nissle 1917(EcN),并探讨其对葡聚糖硫酸钠(DSS)诱导的急性小鼠结肠炎的保护作用。方法构建带有Elafin基因的重组质粒,将其转入感受态EcN,构建能够表达Elafin蛋白的益生菌EcN-Elafin。通过Western印迹证实该益生菌在体外成功表达Elafin。C57/BL6J小鼠随机分为4组:健康对照组(PBS组)、结肠炎组(DSS组)、野生型EcN(EcN-WT)治疗结肠炎组(EcN-WT组)、EcN-Elafin治疗结肠炎组(EcN-Elafin组)。每天同一时间测量小鼠体重、观察小鼠排便情况及计算疾病活动度指数(DAI)。小鼠处以安乐死后测量结肠长度,苏木精-伊红(HE)染色及组织病理学评分比较各组肠黏膜炎症程度,流式细胞术检测结肠固有层浸润中性粒细胞和巨噬细胞的比例,酶联免疫吸附法(ELISA)定量结肠组织中的肿瘤坏死因子(TNF)-α、白细胞介素(IL)-6及趋化因子CXCL-1的蛋白表达水平。结果在EcN-Elafin的培养基上清和菌体沉淀中均能检测到Elafin蛋白。与DSS组相比,EcN-Elafin组和EcN-WT组小鼠体重减轻状况和DAI评分均明显改善。EcN-Elafin组小鼠结肠长度显著长于DSS组。EcN-Elafin组结肠炎组织学评分显著低于DSS组(5.3±2.3比9.3±1.4,P<0.05)。与DSS组小鼠相比,EcN-Elafin组小鼠结肠固有层浸润的中性粒细胞[(8.65±1.49)%比(17.60±2.16)%,P<0.01]和巨噬细胞[(3.79±0.26)%比(5.73±0.45)%,P<0.01]比例均显著降低。EcN-Elafin组和EcN-WT组结肠中TNF-α、IL-6、和CXCL-1蛋白质表达水平均显著低于DSS组。结论表达Elafin的益生菌EcN-Elafin能够显著减轻DSS诱导的急性小鼠结肠炎,对肠黏膜炎症具有保护作用,为临床炎症性肠病的治疗提供一种新的经济有效的方法。