A Five-Day Progesterone Plus eCG-Based Fixed-Time AI Protocol Improves Fertility Over Spontaneous Estrus in High-Producing Dairy Cows Under Heat Stress

This study compared the efficiency of a five-day or standard (nine-day) progesterone-based regimen combined with equine chorionic gonadotrophin (eCG) in a fixed-time AI (FTAI) protocol for dairy cows. The data examined were derived from 3577 inseminations conducted in three dairy herds. Animals with no estrus signs detected over 21 days were randomly assigned to a PRID-9 or PRID-5 group. Cows in each group received a progesterone intravaginal device (PRID) for 9 or 5 days, respectively, PGF_2α and eCG on PRID removal, and GnRH 48 h later. Fixed-time AI was performed 12 h after the GnRH dose. Cows artificially inseminated following spontaneous estrus during the study period were considered as controls. Based on the odds ratio, the likelihoods of animals in PRID-9 in the warm (conception rate [CR] of 22.3%) and cool (32% CR) periods, and control animals in the warm period (26.6% CR) becoming pregnant were reduced (by factors of 0.6, 0.3 and 0.4, respectively) compared with the control animals in the cool period (CR of 43.7%). The risk of a twin pregnancy was higher (51.4%) for cystic PRID-9 cows (by a factor of 3.6) and lower (9.9%) for cyclic PRID-5 animals (by a factor of 0.4) compared with the PRID-9 cyclic cows. These findings indicate that the proposed protocol achieves similar results during the cool or warm season to those obtained when AI is conducted at spontaneous estrus during the cool season. In addition, PRID-5 reduced twin pregnancy compared with PRID-9.     

观赏鱼常见寄生虫病的诊治初探

观赏鱼资源丰富,却常发生寄生虫病,给水族爱好者带来较大的损失。本文通过对病鱼或死鱼的临床检查、病理剖检及实验室检查,对常见的瓣体虫病、车轮虫病、小瓜虫病、指环虫病和本尼登虫病的诊断进行了初步研究,并在此基础上进行了治疗。结果表明,以上5种寄生虫病在症状上有很多相似之处,只有经过刮片镜检,才能准确诊断。当鱼体诊断出有寄生虫时要迅速用硫酸铜、甲醛、吡喹酮和黄药粉等高效药物进行治疗。     

基于政府管制的新农村垃圾处理对策研究

新农村的垃圾日益严重的原因,即人们认识的不足与私利的存在、政府的投入不足以及缺乏政府管制及科学的处理方法等。指出要从根本上解决新农村的垃圾问题,就必须要强化当地政府责任,多渠道全面地推进农村垃圾处理:建立并完善农村垃圾治理的政策法规;转变政绩观念,加强基础设施建设投入;建立行之有效的行政管理部门或管制机构,健全监督体系;实行市场化改革;并加强宣传教育,大力提高村民的环境保护意识。     

地表水中总磷测定误差的预测与处理

[目的]预测与处理地表水中总磷的测定误差.[方法]应用钼酸铵分光光度法测定地表水中的总磷,对在测定过程中可能出现的误差问题提出处理建议.[结果]通过对地表水中总磷测定误差的预测与处理,可以得到较准确的数据,对水体有较准确的评价,从而使水体污染能够得到合理的预防和治理.[结论]只有熟练掌握总磷测定方法,消除各步骤误差,才能减少可能出现的误差,为水资源保护提供真实可靠的分析数据.     

我国城市生活垃圾处理技术现状及展望

城市生活垃圾处置是我国城市可持续发展面临的亟待解决的问题.介绍了我国现阶段垃圾处理几种方式：卫生填法埋、堆肥法、焚烧法以及综合处理方法的优点和缺点.通过几种处理技术的比较,对未来我国城市生活垃圾处理方法进行展望.     

Regrowth Rates of Timothy and Meadow Fescue as Related to the Content of Remaining Water-soluble Carbohydrates and Non-elongated Tillers

The relationship between regrowth rates and the content of water-soluble carbohydrates in stubble (WSC) and percentage of non-elongated tillers (PNT) was studied in timothy (Phleum pratense L.) and meadow fescue (Festuca pratensis Huds.) cut at different phenological stages. Single plants were grown in pots and cut outdoors and then regrown under controlled climatic conditions. The data for the dry matter production during the following 3 weeks were fitted to an expolinear growth equation to determine an initial maximum relative regrowth rate (R _m) and a daily maximum regrowth rate (C _m). C _m appeared to be positively correlated to PNT in both species, whereas R _m was increased with increasing WSC. For regrowth after later cuts of meadow fescue there was a positive contribution to R _m by PNT.     

农用水泵轴断裂故障分析与工艺改进

农用水泵轴在使用过程中部分出现早期断裂,为了找出水泵轴早期断裂的原因,采用直读光谱仪、扫描电镜、金相显微镜、布氏硬度计和冲击试验机等仪器对断轴的化学成分、宏观断口、显微组织、硬度及冲击功进行了综合分析。分析结果认为,结构设计不合理,表面氧化脱碳以及水泵断轴显微组织存在呈魏氏组织形态的铁素体是导致水泵轴在服役时早期疲劳断裂的主要原因。按照分析的结论,通过增大轴肩处预留圆角尺寸,采用水泵轴热处理炉内气氛保护及提高水泵轴淬火加热温度与冷却速度等改进和优化生产工艺的方法,解决了水泵轴在使用过程中出现早期断裂的问题。该文对提高农业机械产品质量控制和水泵关键零件设计与加工具有重要的参考价值。     

土壤铅镉污染修复中植物修复技术的研究进展

近年来,由于工业"三废"治理不彻底、化肥农药的过量使用以及剩余污泥回用农田等原因,导致我国土壤重金属污染日趋严重。重金属无法被降解,易在土壤中累积,并通过生物富集和生物放大效应对环境和人类健康造成危害。土壤重金属污染修复与治理成为研究热点。重金属污染治理包括客土法、石灰改良法、化学淋洗法、植物修复等,这些方法各具特点,均有其适用范围,得到国内外学者的普遍关注。文章针对土壤铅镉污染的植物修复技术展开综述,并对可能影响植物修复的一些因素进行了介绍,最后对本领域的研究方向进行了展望,以期为同行业的从业者提供一定的借鉴。     

加拿大一枝黄花生物炭对Cd2+的吸附特性及机理

以外来入侵种加拿大一枝黄花为原料,探究不同成分在不同热解温度下制得的生物炭的基本性质及其对水中Cd~(2+)的吸附能力、最优吸附工艺条件和吸附机制,以提高其资源化利用效率。结果表明:以茎叶混合作为原料在450℃下热解制得的加拿大一枝黄花生物炭(SCBC450)对Cd~(2+)吸附能力最优。正交结果显示,3种所选因素对生物炭吸附Cd~(2+)的影响程度依次为吸附质起始浓度pH温度;当pH=6、温度35℃、吸附质起始浓度50 mg·L~(-1)时,Cd~(2+)的吸附效率最高,可达(95.6±0.38)%。SCBC450对Cd~(2+)的吸附过程符合二级动力学模型,以化学吸附为主,且符合Langmuir等温吸附模型,最大理论吸附量达107.03 mg·g~(-1)。通过对生物炭吸附前后的XPS、FTIR和SEM-EDS分析可知,其对Cd~(2+)的吸附机制包括离子交换、络合反应、沉淀作用和物理吸附。因此,加拿大一枝黄花生物炭对Cd~(2+)的吸附具有极大的应用潜力。     

常规阳离子存在时Mg-Al-CO3 LDH对土壤中Cd吸附迁移的影响

层状双氢氧化物(Layered double hydroxide, LDH)是土壤中常见的矿物组分,而Na~+、K~+、Ca~(2+)和Mg~(2+)更是土壤溶液中的主要阳离子,它们共存条件下对重金属污染物在土壤中的行为过程影响如何是一个需要探讨的科学问题。通过批量静态吸附实验、动力学实验和室内土柱迁移实验,研究不同阳离子与Mg-Al-CO_3 LDH共存时对重金属Cd在土壤中吸附迁移的影响。运用伪二级动力学模型、Elovich模型及内扩散模型对吸附动力学数据进行拟合,并对Mg-Al-CO_3 LDH吸附Cd前后的样品进行红外光谱分析及X射线衍射分析,以探究其吸附机理。结果表明:Mg-Al-CO_3 LDH的存在使土壤pH升高,且Mg-Al-CO_3 LDH含有大量CO_3~(2-),使得土壤对Cd的吸附能力增强;阳离子类型不同时,无论土壤中是否含有LDH,其对Cd的吸附量均表现为阳离子价态越高,吸附量越小。伪二级动力学模型拟合效果非常好,R~2均接近于1,说明土壤对Cd的吸附能力与吸附位点有关;内扩散模型拟合结果揭示土壤对Cd~(2+)吸附的速率受液膜扩散、颗粒间扩散、化学反应等综合作用的控制。不同阳离子类型对Cd在土壤中吸附迁移的影响不同,Cd迁移能力表现为随背景阳离子价态升高迁移能力增强;Mg-Al-CO_3 LDH的存在抑制了Cd的迁移。红外光谱及X射线衍射分析表明,Mg-Al-CO_3 LDH对Cd~(2+)的吸附机理主要为Cd~(2+)与Mg-Al-CO_3 LDH上的CO_3~(2-)反应生成CdCO_3沉淀。Mg-Al-CO_3 LDH对不同阳离子的吸附机制不同,影响着重金属Cd在土壤中的吸附迁移过程。