小国光苹果贮藏保鲜紫外光、红光照射与钴辐射处理

选取小国光苹果分别做紫外光和红光照射及钴辐射3种物理处理后,进行保鲜贮藏试验。在贮藏期定期测定果实的呼吸强度和主要化学成分的变化,对测定数据作统计分析。结果表明,红光照射与钴辐射处理能显著地抑制苹果的呼吸强度,推迟苹果呼吸高峰的时间,起到贮藏保鲜作用。     

钴和铜对肉用绵羊维生素B_(12)合成、瘤胃发酵及造血机能的影响

为研究不同水平的钴和铜对肉用绵羊维生素B12合成、瘤胃发酵及造血机能的影响,试验选20只体重相近(28.9±1.1)kg、装有永久瘤胃瘘管的杂交一代羯羊,随机均分为5组,定量饲喂对照组日粮,4种不同水平的钴铜(0.3:10、0.3:20、0.6:10和0.6:20)日粮。结果表明:瘤胃维生素B12合成主要取决于钴的摄入量,日粮中同时添加钴、铜及其不同的配比对维生素B12合成未显协同效应和影响。钴与铜合用可增加瘤胃挥发性脂肪酸的浓度,并改变乙酸、丙酸和丁酸比例,用量越多其影响越大。随肉羊日粮中钴与铜合用及其用量增加,可更有效地促进铁的吸收和利用,从而更加明显地改善机体的造血机能。     

山西小麦主产区土壤中钴含量状况及影响因素研究

试验分析研究了山西省小麦主产区之一——运城市土壤中钴的含量状况及其影响因素。研究结果表明。运城市4县区土壤全钴含量为1.65～17．85mg／kg，平均6．00mg／kg，略高于缺钴临界值5．0mg／kg，而低于全国平均值11．2mg／kg;土壤有效钴含量为0．060～2．235mg／kg,平均0．694mg／kg。在34个土样中，大约有60％的样品有效钴含量低于均值．而含量高于均值的土样仅占总样品数的40％。试验区主要土类褐土和潮土全钴含量分别为6．17mg／kg和4．73mg／kg，有效钴含量分别为0．708mg／kg和0．589mg／kg。影响土壤中全钴含量的因素主要是成土母质、成土过程和铁锰含量，影响有效钴含量的因素主要是成土母质、成土过程和有机质。     

重金属钴污染土壤的修复研究进展

土壤污染是全球面临的一个主要环境问题之一,修复方法的选择至关重要。主要综述了重金属钴污染土壤的特性、危害及其治理的方法,分析了放射性钴污染及非放射性钴污染修复方法的区别和联系,并对钴污染土壤修复的研究进行了展望。     

Absence of a weight gain response to Vitamin B12 supplementation in weaned dairy heifers grazing pastures of marginal cobalt content

Aim. To obtain information on serum and liver vitamin B₁₂ and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B₁₂ in young dairy cattle when grazing pasture of low cobalt content.

Methodology. Forty dairy cattle (12 Friesian, 14 Friesian × Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for Vitamin B₁₂ concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations.

Results. No weight gain response occurred to Vitamin B₁₂ supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver Vitamin B₁₂ concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B₁₂ concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation.

Conclusion. Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum Vitamin B₁₂ concentrations at which growth responses to Vitamin B₁₂ or cobalt supplementation are likely under New Zealand pastoral grazing conditions.     

Type III von Willebrand's disease in Dutch kooiker dogs

Summary

Type III von Willebrand's disease (vWD) was diagnosed in 38 Dutch kooiker dogs. Ten male and 9 female probands had been referred independently of each other to the Utrecht University Clinic for Companion Animals because of a moderate to severe bleeding tendency. Screening of 717 Dutch kooiker dogs, including 356 puppies, detected vWD in another 19 dogs. Diagnosis was based on non‐detectable amounts (< 1.6%) of von Willebrand factor antigen (vWF:Ag) in plasma by ELISA. Capillary bleeding time (CBT) was prolonged (> 10 min) and polybrene cofactor activity (vWF:PbCo) was not detectable in 11 dogs tested. No distinguishable protein bands were detected by multimer analysis. As in Scottish terriers with type III vWD, factor VIII clotting activity (F_VIII:C) in affected Dutch kooiker dogs was decreased but considerably less than in humans with type III vWD. A recessive mode of inheritance was indicated by the normal or subnormal but measurable amounts of vWF:Ag in the plasma of eight pairs of parents of affected dogs. The F₁ offspring resulting from the experimental mating of two affected dogs consisted of three affected males and four affected females. In 39 obligatory carriers vWF:Ag ranged from 30% to 114% with median and mean vWF values of 64% and 64.2%, respectively, and was subnormal (< 50%) in only 9 animals.     

铁酸钴纳米粒子的化学共沉淀法制备及表征

采用弱碱 NH4 HCO3作为沉淀剂,CoCl·6H2 O和 FeCl3·6H2 O作为反应物,在一定摩尔比条件下,通过化学共沉淀法制备了铁酸钴纳米粒子,并采用 FT-IR、XRD、TEM和振动样品磁强计对其进行了表征。结果表明,制得的铁酸钴纳米粒子为尖晶石型结构,其粒径为20 nm左右,并且由于反应过程中弱碱 NH4 HCO3分解产生的CO2和 H2 O 气体对产物的阻隔作用,制得的铁酸钴纳米粒子的分散性较好,饱和磁化强度为55.5 Am2·kg-1。     

钴资源的开发和利用

介绍了世界钴资源的储量及分布,生产现状与近期趋势,概述了钴的应用．指出中国作为钴资源缺乏的国家,提高再生钴的回收利用重要性．