A review of soil nematodes as biological indicators for the assessment of soil health

Healthy soils are essential for sustainable agricultural development and soil health requires careful assessment with increasing societal concern over environmentally friendly agricultural development. Soil health is the capacity of soil to function within ecological boundaries to sustain productivity, maintain environmental quality, and promote plant and animal health. Physical, chemical and biological indicators are used to evaluate soil health; the biological indicators include microbes, protozoa and metazoa. Nematodes are the most abundant metazoa and they vary in their sensitivity to pollutants and environmental disturbance. Soil nematode communities are useful biological indicators of soil health, with community characteristics such as abundance, diversity, community structure and metabolic footprint all closely correlated with the soil environment. The community size, complexity and structure reflect the condition of the soil. Both free-living and plant-parasitic nematodes are effective ecological indicators, contributing to nutrient cycling and having important roles as primary, secondary and tertiary consumers in food webs. Tillage inversion, cropping patterns and nutrient management may have strong effects on soil nematodes, with changes in soil nematode communities reflecting soil disturbance. Some free-living nematodes serve as biological models to test soil condition in the laboratory and because of these advantages soil nematodes are increasingly being used as biological indicators of soil health.     

发酵处理对大豆中总异黄酮含量的影响

以大豆及其发酵制品--淡豆豉为试验对象,总黄酮含量为指标,染料木素为对照品,利用染料木素与氢氧化钠产生反应,在271 nm波长处有最大吸收峰,采用紫外分光光度法测定豆豉中总异黄酮的含量.大豆与淡豆豉中总异黄酮的含量分别为4.784 mg/g、9.884 mg/g,结果表明发酵处理使淡豆豉中总异黄酮相对含量增加.     

自测系统中基于多策略的组卷方法研究

开发适合多种教学模式的教学支撑系统是现代教育技术的一个不可缺少的部分,在此一背景下,设计开发了自测系统。文章针对自测系统中的组卷方法给予了详细的讨论,提出多种组卷策略并存,补偿选题算法配合的组卷方法。     

LEVERAGING LIVESTOCK TO PROMOTE A CIRCULAR FOOD SYSTEM

Livestock provide multifaceted services to human societies worldwide. In developing countries, they are crucial assets and safety net for rural poor, and they provide nutrients-dense food to nourish people. In developed economies, growth in demand for animal-derived food is slowing while attention is growing over the role of livestock farming in an enhanced circular food system for sustainability. This analysis, focusing on the modern food systems in developed countries, aims to highlight the unique function of livestock that helps people re-harvest and upcycle crop and food residues generated along the food chain that are otherwise unfit for human consumption. First, human-unusable crop and food residue materials are described in three broad categories based on their characteristics and potential feeding attributes; the magnitude of biomass materials that are already used in routine animal feeding as well as residues that remain as underutilized resources are illustrated using the USA as an example. Then, the research and technology development critically needed for the future is discussed. As the world strives to produce more food with smaller environmental and climate footprints, upcycling the residual biomass via livestock for food production presents a viable pathway toward improved resource use, reduced pollution and enhanced food system efficiency.     

人源羊水干细胞的培养、鉴定及影响因素分析

取人羊水标本进行羊水干细胞原代,分离培养,并探讨人羊水标本性状等因素对原代分离培养的影响.结果表明,分离的羊水干细胞表达Oct-4等胚胎干细胞和CD29等成体干细胞的特异基因,细胞生长迅速,增殖能力较强,并可分化为Nestin阳性的神经细胞和α-actia阳性的心肌细胞.同时,在羊水干细胞原代培养时,羊水标本性状在一定程度上影响细胞的贴壁数量及贴壁时间.羊水标本细胞的贴壁时间孕中期(4.7±0.6)d与孕晚期(6±0.5)d有明显差异(P<0.05),孕晚期贴壁时间较长.羊水中血液污染程度对贴壁时间有明显影响,重度污染组(10.8±0.3)d与无污染组(6±0.5)d、轻度污染组(6.3±0.6)d贴壁时间差异均显著(P<0.05).羊水体积对原代细胞的贴壁数量和细胞贴壁时间有一定影响,羊水体积增大贴壁时间延长,但差异不显著,而贴壁细胞数量随羊水体积增加而增加,各组之间差异显著(P<0.05).实验系统地检测了羊水干细胞原代培养的影响因素,为羊水干细胞研究提供了可以借鉴的资料,同时分离得到的羊水干细胞,具有分化为神经细胞和心肌细胞的潜能,有望作为种子细胞进行临床应用.     

几种天然助剂配苦参碱防治棉花伏蚜的增效作用

为了提高苦参碱对棉花伏蚜的防治效果和持效期,同时又确保农产品质量安全.利用褐藻胶、黄原胶等天然助剂加入苦参碱中防治棉花蚜虫.试验结果表明,药后30天,褐藻胶处理、黄原胶处理的防治效果仍在90％以上,褐藻胶、黄原胶作为天然助剂对苦参碱防治棉蚜表现出显著的增效作用,具有广阔的应用前景.     

基于语义分割和几何分析的火龙果果实与枝条的三维重建

针对非结构化环境中采摘机器人缺少足够环境信息的问题,该研究提出了一种用于机器臂避障和路径规划的果实与枝条检测和三维重建方法。采用MobileNetV2取代传统DeepLabV3+主干特征提取网络Xception,并在特征提取模块引入了坐标注意力机制,通过改进网络对采集的RGB图像进行目标检测,并将检测到的火龙果和枝条语义掩膜转换成三维点云。提出一种基于非线性最小二乘法的椭球体拟合方法用于重建火龙果,用有限数量的AABB包围盒获取不规则的枝条的三维空间位姿信息。测试表明,改进后模型的平均交并比（mean intersection over union,mIoU）和平均像素精度（mean pixel accuracy,mPA）分别达到95.59%、98.01%,相较原模型分别提升2.57个百分点和1.44个百分点;平均推理时间和模型内存占用量分别降至94.74ms和22.52MB,分别仅为原模型的59%和11%。三维重建试验表明,火龙果果实重建的短轴尺寸和深度距离的平均绝对误差分别为0.44和2.04mm,枝条重建的样本标准差在各坐标轴上均小于10mm。结果证实了该研究方法可以有效地重建火龙果果实和枝条,可以为火龙果采摘机器人的采摘路径规划避障提供基础。     

基于H蛋白表位合成肽的小反刍兽疫病毒抗体间接ELISA检测方法的建立

本研究旨在建立针对小反刍兽疫病毒(peste des petits ruminants virus,PPRV)H蛋白抗体的iELISA检测方法.以筛选的H蛋白B细胞表位为基础,选择反应原性较好的4个抗原表位肽串联后合成作为包被抗原,优化各步反应条件及筛选各种缓冲液,并确定检测临界值.经优化后,多表位抗原肽的最佳包被量为...     

不同基质和硫磺粉对越橘土壤和叶片矿质营养的影响

采用盆栽和塑料大棚试验,研究黑土中加入不同基质和硫磺粉对土壤和越橘叶片矿质元素含量的影响。结果表明:加入不同基质(苔藓、草炭、锯末、河沙、酒糟)和硫磺粉后,改变了土壤中各种矿质元素的含量,进而影响了叶片对各种矿质元素的吸收。其中,盆栽试验苔藓 草炭的处理土壤中N含量为160.8 mg/kg,P为15.46 mg/kg;叶片中N、P、Fe的含量分别为1.42%,1.30%和73.1 mg/kg;塑料大棚试验加入2.0 kg/m3和2.5 kg/m3硫磺粉的处理土壤中N、P的含量分别为3.89,3.07 mg/kg,叶片中N、P含量分别为1.528%,0.101%和1.684%,0.109%,表现为植株生长旺盛,适宜越橘生长。     

草鱼鱼鳞酶溶性胶原蛋白的提取及基本特性

利用胃蛋白酶从草鱼鱼鳞中提取酶溶性胶原蛋白(PSC)。并用氨基酸自动分析仪、SDS-PAGE电泳、DSC、FT-IR和圆二色谱对草鱼鱼鳞胶原蛋白的氨基酸组成、相对分子量、变性温度和结构进行了研究。试验结果表明:所提草鱼鱼鳞蛋白为典型的I型胶原蛋白;且至少含有2条α链,α1和α2链;DSC分析表明其变性温度为37.1℃。