基于电磁感应数据的电导率反演模型研究

【目的】土壤盐渍化是限制新疆南部棉花高产的主要因子,准确获取区域尺度土壤剖面盐分信息。【方法】以南疆阿拉尔垦区为研究区,以田间尺度采集的30个不同盐渍化程度棉田的540个样点的0~0.375、0~0.750、0~1.000 m的土壤剖面电导率数据和对应的电磁感应数据为数据源,采用线性模型和非线性模型分别构建了田间尺度和区域尺度的土壤剖面电导率的电磁感应反演模型,并采用缩减建模样本量方法进一步检验了区域尺度模型的可靠性和稳定性。【结果】多元线性回归(MLR)、偏最小二乘回归(PLSR)和主成分回归(PCR)建模方法的田间尺度模型R²在0.88~0.95,而对应的区域尺度模型R²在0.34~0.53。基于随机森林(RF)、神经网络(NN)和支持向量机(SVM)非线性建模方法构建的土壤剖面电导率的区域尺度电磁感应反演模型R²在0.60~0.85,其中RF模型的精度最高。0~0.375、0~0.750、0~1.000 m土壤剖面电导率的RF反演模型R²分别为0.80、0.85和0.84,相较于线性建模方法的区域尺度模型精度有明显的提高。RF区域尺度模型的样本数量由540个缩减到240个,模型精度没有明显变化,表明采用区域尺度模型,可大幅度降低土壤剖面样本采集数量,从而可显著提高采样效率和降低采样成本。【结论】区域尺度下构建土壤剖面电导率反演模型时,随机森林建模方法效果较优,模型预测能力具有较高的可靠性。     

54 份鲜食玉米品种草地贪夜蛾抗虫性鉴定与评价

[目的]鉴定评价54份鲜食玉米品种(组合)对草地贪夜蛾Spodoptera frugiperda的抗性级别,为鲜食玉米抗虫育种提供参考依据.[方法]在草地贪夜蛾大爆发的自然条件下,于2020年春季、秋季对54份鲜食玉米品种(组合)的叶片和果穗开展其对草地贪夜蛾抗虫性鉴定和评价,综合两季结果分析鲜食玉米品种(组合)对草地贪夜蛾的抗虫性.[结果]大部分鲜食玉米的叶片和穗部对草地贪夜蛾表现为感或高感,无高抗和抗虫品种(组合),仅有粤五彩甜糯品种的穗部和叶片抗性表现为中抗,占1.85％.粤鲜糯2号、粤白甜糯5号、粤甜33号等14份品种(组合)只在穗部表现为中抗,占25.93％.[结论]综合54个鲜食玉米品种(组合)的叶片和果穗的初步鉴定结果,鲜食玉米抗虫资源较少,草地贪夜蛾对不同品种(组合)叶片和果穗偏好性不同.不同类型玉米在叶片抗性无显著差异,糯性玉米和具有热带血源的甜玉米果穗存在一定程度抗虫性,在抗虫新品种选育时可加以利用.     

土壤和沉积物中PAHs环境行为研究进展

PAHs作为持久性有机污染物对人类健康和生态安全构成威胁,研究PAHs环境行为对明确我国PAHs污染现状和防治PAHs污染具有重要意义.文章综述国内外对城市、河流和山区土壤和沉积物中PAHs区域分布和纵向分布研究,列举常见PAHs来源和来源判断方法.归纳PAHs释放和迁移两种重要环境行为,针对释放行为详细讨论沉积物再悬浮过程和PAHs吸附-解吸机制,针对迁移行为探讨PAHs远距离迁移、纵向迁移和生物富集.阐明研究PAHs环境的重要意义,展望PAHs环境行为研究前景.     

温度、盐度和光照对海蜇足囊繁殖的影响

在实验室条件下，就温度、盐度和光照对海蜇（Ｒｈｏｐｉｌｅｍａｅｓｃｕｌｅｎｔａｋｉｓｈｉｎｏｕｙｅ）足囊形成和萌发的影响进行观察。温度实验在０～３０℃范围内设７组，盐度实验在２～３２．１‰范围内设１６个梯度，光照分为自然光和黑暗两组。实验显示：１０℃以上海蜇无足囊繁殖迹象，１５～３０℃范围内，随温度升高，海蜇足囊繁殖能力增强；６‰以下盐度，海蜇不能进行足囊繁殖，２０～２２‰是海蜇足囊繁殖的最适盐度；黑暗有利于足囊繁殖。温度是足囊繁殖的关键因子，盐度和光照是足囊繁殖的充分条件。作者认为，适宜的环境因子是海蜇螅状体形成的必要条件，尽管足囊可以抵御外界的恶劣环境，但足囊形成并非需要不良环境因子诱导，足囊繁殖是海蜇螅状体一种正常的无性繁殖方式     

大口黑鲈鲁氏耶尔森氏菌的分离鉴定、主要毒力基因及致病性研究

为探明2021年3月福建某水库养殖大口黑鲈疾病暴发的原因,实验从患病大口黑鲈肝脏、肾脏、脾脏中分离优势菌,通过人工感染实验确定病原菌,并综合16S rDNA基因序列分析、生理生化和质谱特征等技术对该病原菌进行种属鉴定,同时,进行毒力基因检测、药物敏感性实验以及组织病理学观察。结果显示,从病鱼脾脏中分离获得1株优势菌并鉴定为鲁氏耶尔森氏菌;该菌株对大口黑鲈的半致死剂量为3.8×10⁵ CFU/尾;该菌株携带yrP1、yhl A、yhl B等毒力基因,对恩诺沙星、盐酸多西环素、氟甲喹、硫酸新霉素、氟苯尼考等5种药物相对敏感。组织病理学观察发现,鲁氏耶尔森氏菌的感染造成大口黑鲈肝脏、肾脏、脾脏不同程度的损伤,表现为明显的变性、坏死及炎症细胞的浸润等。本研究首次报道了鲁氏耶尔森氏菌对养殖大口黑鲈的致病性,可为养殖大口黑鲈鲁氏耶尔森氏菌病的诊断和药物防治提供参考依据。     

羔羊卵巢AMH的免疫组织化学分析

为探讨AMH在羔羊和成年羊卵巢中时间和空间表达变化,揭示卵泡生长发育调控的机制。收集1月龄羔羊和正常成年羊卵巢,采用HE染色观察卵巢的组织学特征,免疫组化法检测绵羊卵巢AMH蛋白表达分布,RT-PCR技术分析卵巢卵丘细胞中AMH基因的表达变化。结果显示,卵巢HE染色后,对外源激素处理有反应的卵巢存在大量的大直径卵泡,且无中等卵泡和小卵泡,也没有黄体化和排卵;对外源激素没有反应的卵巢仅存在原始卵泡和少量的初级卵泡,无有腔卵泡。免疫组化结果显示,AMH存在于生长期的腔前卵泡和小的有腔卵泡,以及卵丘细胞,大多原始卵泡无AMH的表达,而在原始卵泡向初级卵泡转变,外层的颗粒细胞由扁平向柱状转变时AMH有表达,颗粒细胞存在表达AMH和不表达AMH 2种类型。RT-PCR结果显示,羔羊卵丘细胞的表达量高于成年羊。AMH可能参与卵泡发育的启动、向促性腺激素依赖期的转变等过程的调控,其功能作用还有待于深入研究。     

黄土高原半干旱区景观化集水造绿空间网络构建——以甘肃环县为例

在"聚居背景—聚居活动—聚居建设"的景观"三元论"的哲学基础上,风景园林这一综合学科应对黄土高原的人居环境改善产生重要的作用。文章以黄土高原东部半干旱区环县的人居环境为研究对象,从人居角度分析影响集水造绿的各类因素,从降水、坡度、坡向、河流、泉眼等自然因素以及城镇、道路、水库等人工因素的角度评价集水造绿的适宜性;以GIS技术进行数据整理与量化分级,通过综合考量确定集水造绿的优势地带等级,即适宜度分析;识别集水造绿的"节点"与"路径";规划水绿双赢的空间网络。研究证明,在引入适当人为干预的情况下,通过"基底—节点—路径"方式构建的集水造绿优势空间网络能够适应人居环境集水造绿的需求。     

基于FPGA的Buck变换器新型DPWM技术研究

文章针对Buck型DC-DC变换器中DPWM（数字脉冲宽度调制）技术进行研究,指出传统DPWM技术不足,提出MDPWM（改进的脉冲宽度调制）技术。采用FPGA的QuartusⅡ软件进行仿真,仿真结果表明,MDPWM技术能够减少开关管的开通和关断延迟时间、减小器件的功率损耗,当负载波动时,输出电压瞬态响应快,使输出电压稳定性好。     

Biochemical composition of pond-reared and lake-stocked Chinese mitten crab Eriocheir sinensis (H. Milne-Edwards) broodstock

The morphological characteristics, tissue indices, proximate and fatty acid compositions of hepatopancreas, gonad and muscle of pond‐reared (PR) and lake‐stocked (LS) Eriocheir sinensis broodstock were compared. Lake‐stocked crabs are characterized by a blue carapace, white abdomen, golden legs and yellow setae while PR crabs have a brown carapace, grey abdomen, black legs and similar yellow setae. The carapace length and width of PR crabs were significantly less than those of LS crabs of the same wet weight (WW). The results showed that the hepatosomatic index (HSI) of PR males was significantly higher, but the gonadosomatic index (GSI) was significantly lower for PR females when compared with LS individuals of the same sex. Regardless of their origin, the muscular index (MI) of males was higher than that of females. The hepatopancreas of LS crabs had higher protein levels and lower lipid levels compared with PR crabs. The results of proximate analysis of male gonads from two different sources were similar, while the protein level in the ovary of LS females was higher than that of PR females. The tissues of males had higher water content but lower lipid and protein levels compared with females regardless of their source. The LS crabs had higher highly unsaturated fatty acid (HUFA) levels than PR crabs in their gonad and hepatopancreas. In conclusion, our results suggest that the nutritional quality of LS crabs is better than that of PR crabs, the nutritional quality of males is poorer than that of females. The reproductive performance and larval quality of crabs from these two rearing systems should be further verified.     

Potassium antagonizes damage of coronary artery induced by high salt intake

AIM：To investigate the effect of potassium treatment on coronary arterial impairment induced by high salt intake. METHODS：Sprague-Dawley rats (4-week-old, n=10 in each group) received distilled water (NS), water containing 1.5% NaCl (HS), or 1.5% NaCl and 0.5% KCl (HS+HP) for 16 weeks. Systolic blood pressure (SBP) was determined by tail plethysmography every 2 weeks. After 16 weeks of treatment, vascular remodeling, superoxide production, malondialdehyde (MDA) content, and endothelial nitric oxide synthase (eNOS) and gp91 expression in the coronary arteries were detected. RESULTS：After 16 weeks of salt loading, the rats in HS group was divided into salt sensitive subgroup and salt resistance subgroup according to the tail-cuff blood pressure. In this experiment, the salt-sensitive rats were selected as HS group. In HS group, salt loading significantly increased SBP, serum MDA and gp91 expression, decreased serum NO and eNOS expression in the coronary arteries, and induced the coronary artery remodeling compared with NS group. In salt-loaded SD rats, 16-week potassium treatment abrogated the effects induced by salt loading. CONCLUSION：High salt may affect structural and functional changes in coronary arteries by activating oxidative stress. Potassium treatment antagonizes the effect of high salt intake.