海藻酸钠凝胶球对铬(Ⅵ)的去除效果研究

研究海藻酸钠-钙凝胶球、海藻酸钠-铁(Ⅲ)凝胶球对废水中的铬(Ⅵ)的去除效果。结果表明:对50 m L(10 mg/L)的模拟废水进行吸附,海藻酸钠-铁(Ⅲ)凝胶球的吸附效果较好,而海藻酸钠-钙凝胶球对铬(Ⅵ)几乎不发生吸附作用。铬(Ⅵ)的去除率随吸附时间的增加而提高,吸附240 min后,海藻酸钠-铁(Ⅲ)凝胶球对铬(Ⅵ)的去除率可达99%以上,海藻酸钠-铁(Ⅲ)凝胶球在酸性条件下比较稳定,在强碱性条件下易被分解,海藻酸钠-铁(Ⅲ)凝胶球吸附铬(Ⅵ)的吸附等温线符合Langmuir型,最大吸附量为11.827 mg/g。利用海藻酸钠-铁(Ⅲ)凝胶球去除废水中的铬(Ⅵ)具有工艺简单、处理效率高、速度快等优点。     

Performance of a commercial recirculating alligator production system employing a paddle-washed floating bead filter

A 2.83 m³ prototype paddle-washed bead filter for combined solids capture and biological filtration was successfully operated in a commercial recirculating alligator (Alligator mississippiensis) facility. The bead filter was originally designed and operated as a downflow filter but due to operational and water quality problems, it was reconfigured to operate in an upflow mode. Water quality conditions and filter performance improved dramatically, with the upflow bead filter capable of handling the equivalent loading of 10.3 kg m⁻³ beads per day of 40% protein feed, despite oxygen limitations and hydraulic problems associated with the retrofitted alligator system.     

紫云英SSR分子标记的开发及在品种鉴别中的应用

利用生物素标记的(AG)₁₅、(CT)₁₅、(AC)₁₅、(GT)₁₅探针及链霉素亲和磁珠,从紫云英的基因组中富集微卫星(SSR)序列。在用富集片段构建插入文库的950个转化子中,经PCR检测及测序共得到127个SSR序列,微卫星序列的富集效率达15.8%。除去重复或无效的序列,得到33个序列用于引物设计。对征集的9个紫云英品种进行多态性分析,有6对引物扩增出明显且稳定的多态性位点18个。在紫云英的品种水平上,这些SSR位点产生的多态率为50%~100%,有效等位基因数为1.19~1.64,Nei氏遗传多样性为0.13~0.38,Shannon多态信息指数为0.22~0.56;利用这6对引物可将参试品种完全区分开,证明这些SSR位点可用于紫云英品种的指纹鉴别。根据SSR位点的相似性系数,将 9个紫云英品种主要聚成两个类群, 与传统按生育期的紫云英品种划分结果无必然的联系。     

低温工厂化养殖水体氨氮处理微生物的初步研究

为了研究低温环境下工厂化养殖水体氨氮处理微生物，用平板菌落计数法和最大几率数法对处理养殖水体的生物滤池中的微生物数量进行了跟踪检测，同时测定实验组和对照组养殖水体的理化性质。结果显示在实验过程中，硝化细菌和亚硝化细菌的数量持续上升，后期达到稳定；初期系统中没有反硝化细菌，后期数量开始逐渐增加。实验组与对照组的养殖水体的氨氮、硝酸盐和亚硝酸盐浓度的测定结果证明了生物滤池中的硝化——反硝化系统在发挥作用。实验表明经过低温环境的驯化和诱导，在12℃的低温条件下，微生物处理仍然是工厂化养殖水体中氨氮的有效处理手段。实验验证了在冷水鱼工厂化低温养殖中使用生物滤池处理氨氮的可行性。     

基于磁珠的细菌基因组DNA快速提取方法

[目的]为临床上大肠杆菌O157∶H7的快速检测提供参考。[方法]依据高盐离子浓度下多聚核苷酸与羧基修饰的磁珠表面可发生非特异性吸附,而蛋白、单糖、多糖和脂类等细胞成分不被吸附的原理,建立了一种以磁性微珠为载体的细菌基因组DNA纯化方法—磁性DNA纯化法。[结果]该方法可在7min内完成对大肠杆菌O157∶H7基因组DNA的高效富集与纯化;与德国进口同类试剂盒gene-MAG-DNA/Bacteria及AxyPrep细菌基因组DNA纯化试剂盒相比,该方法操作简单、耗时短、不需要使用离心机和有机试剂,且无需常规快速提取法的沸水浴等步骤,安全、快速、成本低,在临床、食品、环境病原体快速检测领域具有巨大的推广价值。[结论]该研究成功建立了一种细菌基因组DNA的快速提取方法。     

Evaluation of adjuvant carboplatin chemotherapy in the management of surgically excised anal sac apocrine gland adenocarcinoma in dogs

There is no widely accepted standard of care for canine anal sac apocrine gland adenocarcinoma (ASAGAC). Surgery alone is inadequate in many cases, but the benefit of adjuvant chemotherapy is not well established. The primary objective of this retrospective study was to evaluate the role of carboplatin chemotherapy in the post‐operative management of ASAGAC. Seventy‐four dogs with naturally occurring ASAGAC underwent surgery. Forty‐four dogs received adjuvant carboplatin and 30 did not. Median overall survival (OS) was 703 days. Median time to progression (TTP) was 384 days. Only primary tumour size and lymph node metastasis at diagnosis significantly impacted the outcome. Differences in OS and TTP, between the dogs that received adjuvant carboplatin and those that did not, failed to reach statistical significance. Treatment of progressive disease, whilst not limited to chemotherapy, significantly prolonged the survival. This study shows that adjuvant carboplatin chemotherapy is well tolerated and may have a role in the management of dogs with ASAGAC.     

乌鳢微卫星DNA分子标记的分离及筛选

利用磁珠富集法结合放射性同位素杂交方法分离乌鳢Ophiocephalus argus的微卫星分子标记,共获得阳性克隆1 200个,从中挑选466个进行测序,得到400个含有微卫星的序列（占86.6%）。结果表明：完美型微卫星座位325个,占76.11%;非完美型微卫星座位75个,占17.57%;复合型微卫星座位27个,占6.32%。在得到的微卫星序列中,重复单元除CAG/GTC外,还观察到二碱基重复单元。根据侧翼序列设计引物139对,选择合成50对,通过优化PCR反应条件,结果有27对引物可扩增出清晰可重复的目的条带,19对引物在黑龙江群体、山东群体乌鳢的DNA样本中表现出多态性。     

砂磨机制备铜基营养保护剂悬浮剂的工艺优化

为提高铜基营养保护剂悬浮剂的悬浮率和稳定性,通过正交实验和单因素实验方法,从浆料质量分数、研磨转速、研磨介质与浆料质量比及研磨时间4个因素出发,研究了通过砂磨机制备铜基营养保护剂悬浮剂的优化工艺。结果表明:研磨转速对制剂粒径影响最大;研磨介质与浆料质量比对制剂分散颗粒比表面积影响最大;浆料质量分数对粒径和比表面积的影响均最小。其最佳制备工艺条件为:浆料质量分数60%,研磨转速1 500 r/min,m(研磨介质):m(浆料)=1.5:1,研磨时间80 min。在此条件下,所得铜基营养保护剂悬浮剂的悬浮率均大于90%,且其分散性、水质适应性和水温实验均符合相关标准要求。研究结果可为铜基营养保护剂的开发应用提供理论基础及工艺参考。     

犊牛盲肠微生物总DNA的提取方法

采用反复冻融法、玻璃珠法和超声波+反复珠磨的方法提取犊牛盲肠的微生物总DNA,并对以上三种方法进行比较,从中确定最佳的方法,以实现普通实验条件下成功提取符合PCR扩增要求的DNA.经紫外分光光度分析表明,超声波+反复珠磨的方法所得的DNA的A<,260>/A<,280>的比值为1.81,0.8%琼脂糖凝胶电泳结果显示,所提DNA片段分子量大于20 kb,适于酶解和PCR扩增要求.以提取的DNA样品为模板,利用细菌通用引物,对其16S rDNA进行PCR扩增,获得了1.7 kb大小特异性很好的预期条带.这是研究犊牛盲肠微生物的关键一步.     

Three dimensional simulation of viscoelastic polymer melts flow in a cast film process

Three-dimensional simulation of the cast film process for viscoelastic polymer materials was carried out using the finite element method. The flow between the extrusion die and chill roll was assumed to be steady-state and isothermal and the rheological property of material was characterized by a single-mode PTT model. Gravity and inertial flow were considered in the simulation work, but neglecting die swell at the die exit, surface tension, crystallization, transient disturbance and film sag. Simulation results of the cast film production line were compared with the experimental data on the velocity profiles and neck-in values. Neck-in and edge bead was well predicted and the influence of strain-hardening nature, elasticity of materials and operation conditions on the final film shape was also investigated. It was found that the effect of strain-hardening nature was masked for the material with a very low relaxation time when the single-mode PTT model was adopted. Greater elasticity helped to produce a film with smaller neck-in and less waste edge. When the air gap length was increased, it was predicted that neck-in phenomenon would be promoted as well. Moreover, it was found that ratio of neck-in values under different air gap lengths was approximately equal to that of air gap lengths, which was consistent with experimental evidence.