1-site/2-pK_a表面络合模型预测土壤中Cd²⁺的吸附及生物有效性     

郁何敏  李焱  石振清  王玉军 《农业环境科学学报》2022,41(6):1211-1220

土壤中重金属的生物有效性与其在土壤中的吸附行为密切相关,本研究选取我国9个不同类型的非石灰性土壤,探究了Cd²⁺在土壤中的吸附过程。通过电位滴定获得土壤表面酸碱性质（pK_a1和pK_a2）,基于1-site/2-pK_a模型,使用ECOSAT和FIT拟合得到土壤与Cd²⁺的络合常数（lg K _{（SOCd⁺）}）,结果显示该模型能很好地描述Cd²⁺在土壤中的吸附过程。为了进一步探究土壤性质对Cd吸附固定的影响,通过逐步回归分析了pK_a1、pK_a2、lg K _{（SOCd⁺）}与土壤性质间的关系,发现土壤pH和CEC是pK_a1的主控因子,土壤pH同时也是pK_a2、lg K _{（SOCd⁺）}的主控因子。为了验证模型的可靠性,结合历史文献,基于土壤pH和CEC预测了历史文献中土壤表面酸碱性质和lg K _{（SOCd⁺）},利用得到的参数预测了Cd的吸附过程,发现预测值与实测值之间有很好的相关性,该模型能解释86%的变异。此外,利用回归模型得到的结合常数预测了历史文献中土壤溶液中的Cd含量,发现模型预测的Cd含量与蚯蚓体内Cd含量同样具有很好的相关性,能解释83%的变异。本研究基于Cd²⁺在不同性质土壤中的吸附行为,使用广义复合法建立的表面络合模型可以描述Cd²⁺在非石灰性土壤中的吸附与分配过程。  相似文献   

有机污染土壤生物修复效果的限制因素及提升措施   总被引：1，自引：0，他引：1  

吴敏  施柯廷  陈全  梁妮  潘波 《农业环境科学学报》2022,41(5):919-932

土壤中的有机污染物主要来源于有机农药、石油污染、工业生产等,其对生态环境和人体健康造成了极大的危害。受有机物污染的土壤能通过物理、化学、生物等一系列的修复技术进行治理,其中生物修复技术被认为是处理有机污染土壤最有效、经济且环境友好的修复技术,但其修复效率受诸多因素影响。本文从气候地理条件、有机污染物的存在形态和土壤自身环境与营养3个方面系统地分析了生物修复技术的限制因素,并从物种选择、生物有效性提升（引入微生物或土壤动物、添加表面活性剂和有机溶剂）及稳定生态系统的构建（添加生物炭、营养补充剂,采用电强化生物修复技术）3个角度科学地提出了提升生物修复技术效率的方法,最后对加强有机物污染土壤复合修复技术的研究进行了展望。  相似文献   

中国淡水硅藻新记录——冈瓦纳舟形藻     

汪妮  蔡梅  王元元  丁改变  孙尚省  张玮 《上海海洋大学学报》2022,31(5):1041-1047

2021年,在对福建省莆田市东圳水库进行藻类多样性调查过程中,发现了中国淡水硅藻的一个新记录种———冈瓦纳舟形藻(Navicula gondwana Lange-Bertalot)。该种在澳大利亚首次被报道,但原文提供的超微结构特征有限,亦未提供内壳面电镜图。使用光镜和扫描电镜对采集自福建的冈瓦纳舟形藻种群的形态特征,进行了详细观察及描述,并将其与模式种,以及其他相似种的形态特征,进行了比较。结果表明：(1)壳面整体呈狭披针形,壳面末端钝圆锥形;(2)壳缝简单,直线状,近缝端略微膨大,稍偏向壳体一侧,远缝端延伸成强烈的弯钩状,两末端的壳缝弯向一侧,且与近缝端偏斜方向一致;(3)中轴区窄,线形,中央区相对较大,呈不规则圆形;(4)壳面横线纹由单列的短线形孔纹组成,在中部呈辐射状排列,两端聚束状排列,10 μm内有11~14条。研究结果与冈瓦纳舟形藻模式产地种群的形态、线纹等特征吻合,该物种在中国是首次报道。  相似文献   

他克林对猪精子冻后质量、抗氧化能力及糖代谢的影响     

陈志英  胡传活  唐胤晟  邓祝新  许鹏  冯显钤  许春荣  刘德玉  冯妮  谢运法  李铭 《西北农业学报》2021,(7):981-988

旨在研究他克林对猪精液冻后质量、抗氧化能力及糖代谢的影响机制。手握法采集12头18～24月龄健康杜洛克种公猪精液,在其冷冻保存稀释液中加0.10mmol/L他克林并冷冻保存,检测冻后精子活率、质膜完整率、顶体完整率和畸形率、线粒体膜电位、DNA完整性,同时利用试剂盒检测总抗氧能力、丙二醛含量、超氧化物歧化酶活性、总胆固醇含量、丙酮酸含量及己糖激酶活性。结果表明,与鲜精相比,冻融后精子活率和质膜完整率、顶体完整率、线粒体膜电位、DNA完整性、抗氧化能力及糖代谢指标均极显著下降,畸形率极显著升高。与空白组相比,他克林显著提高冻后精子顶体完整率、DNA完整率、超氧化物歧化酶、丙酮酸含量;极显著提高精子活率、质膜完整率、线粒体膜电位、总抗氧能力、丙二醛含量、总胆固醇含量及己糖激酶活性,极显著降低畸形率。总之,猪精液冷冻前添加浓度为0.10 mmol/L的他克林可能通过提高抗氧化能力和糖代谢水平改善冻融后猪精子的质量。  相似文献   

东海区发展水产资源增养殖的设想   总被引：2，自引：0，他引：2  

倪正泉  陶虎德 《海洋水产研究》1994,(15):131-139

东海区海岸线和岛屿岸线分别占全国的34%和49.1%,面积大于500m~2的岛屿共3481个,潍涂面积占全国的46.7%。港湾众多,总面积25507 km~2,0～20 m 水深的浅海面积64461 km~2,约占全国50%。东海区栖息了许多名特优的渔业资源,海洋生物具有相当的丰度和广度,水文环境稳定,营养盐类丰富,初级生产力高,也是多种鱼类、虾类、蟹类的栖息、繁殖场所。东海区(包括福建省、浙江省、上海市和江苏省)1991年海水增养殖面积达1335 km~2,总产量48.0万 t。全区具有较大规模的海带育苗、紫菜育苗、贝类育苗、虾类育苗、海蜇育苗的场地和设备。鱼类育苗技术不断提高.现已进行了约80个种类的人工、半人工育苗及20个种类的增殖放流或移植、自然增殖的试验。海水养殖种类达40～50种。东海区得天独厚的具有高经济价值的鳗苗和中华绒螫蟹苗的天然苗种资源。东海区既是全国海水增养殖业的重要基地也希望取得周边国家和地区的支持和合作。提出了今后(2000年止)发展的具体设想内容及主要项目,以及应采取的措施等,具有指导意义。  相似文献   

The siderophore-interacting protein is involved in iron acquisition and virulence of Riemerella anatipestifer strain CH3     

Jing Tu  Fengying Lu  Shuang Miao  Xintao Ni  Pan Jiang  Hui Yu  Linlin Xing  Shengqing Yu  Chan Ding  Qinghai Hu 《Veterinary microbiology》2014,168(2-4):395-402

Riemerella anatipestifer causes epizootic infectious disease in poultry and serious economic losses especially to the duck industry. However, little is known regarding the molecular basis of its pathogenesis. The ability to acquire iron under low-iron conditions is related to the virulence of a variety of bacterial pathogens. In this study, a sip (Riean_1281) deletion mutant CH3Δsip was constructed and characterized for iron-limited growth, biofilm formation, and pathogenicity to ducklings. Results showed that siderophore-interacting protein (SIP) was involved in iron utilization and the sip deletion significantly reduced biofilm formation and adherence to and invasion of Vero cells. In addition, the sip gene was absent in 1 of 24 (4.17%) virulent strains and 2 of 3 (66.7%) avirulent strains of R. anatipestifer, and the sip gene from six R. anatipestifer strains, which belong to serotypes 1, 2, and 10, respectively, shared 100% amino acid identities to those of R. anatipestifer strains DSM15868 and RA-GD. These results suggested that siderophore-mediated iron acquisition may be an important iron-uptake pathway in R. anatipestifer. Animal experiments indicated that the median lethal dose of the CH3Δsip mutant in ducklings was about 35-fold higher than that of the wild-type CH3 strain. Thus, our results demonstrated that R. anatipestifer SIP was involved in iron acquisition and necessary for its optimal virulence.  相似文献   

Effects of physical attributes and chemical composition of novel foods on food selection by Norway rats (Rattus norvegicus)     

Ibrahim M. Hegab  Hemin Pan  Junyan Dong  Aiqin Wang  Baofa Yin  Shengmei Yang  Wanhong Wei 《Journal of pest science》2014,87(1):99-106

An organism’s food is a fundamental aspect of its survival niche. Free-ranging rodents are presented regularly with different types of novel food. To investigate the novel food selection process in Norway rats concerning chemical and physical characteristics, 288 laboratory bred Norway rats (Rattus norvegicus) were tested with a 2-h free choice for each animal. First, rats were tested against eight kinds of novel foods: corn, beans, broiler ration, soybeans, peanuts, rice, potatoes, and millet. Rats preferred corn over the other novel food types, and there was a significant positive correlation between the selective coefficient and carbohydrate content; rats chose novel food with highest energy content. Rats also appeared to be less neophobic to foods of high sugar content. Regarding physical characteristic, rats effectively differentiated between spectral colors of different wavelengths, and red-colored food was more attractive for rats than foods of four other colors. Small-sized food received the highest numbers of visits and longest feeding bouts compared to other sizes. These results suggest that the carbohydrates content, red color, and small size of novel food play a role in the novel food selection of Norway rats.  相似文献   

液压Stewart主从系统六维控制策略     

侯敬巍  倪涛  唐新星  赵丁选 《农业机械学报》2014,45(8):334-338,346

设计了一种主从手均为液压Stewart机构的主从控制系统,用于操作者以遥操作的方式进行复杂曲面的研磨,避免研磨粉尘对现场工作的工人造成呼吸道伤害。针对该机构需具有六维力反馈的工作要求,采用基于工作空间的四通道力觉双向伺服策略,以降低连杆差异和外界干扰力等非线性因素的影响,提高力反馈精度。在此基础上提出了六维的策略切换控制,解决因从端遭遇刚性冲击引起的主手震荡问题。通过柔性及刚性碰撞实验证明了该策略的有效性。  相似文献   

Effect of pH on the gelation of walleye pollack surimi and carp actomyosin pastes   总被引：2，自引：0，他引：2  

Shaowei Ni  Hisanori Nozawa  Nobuo Seki 《Fisheries Science》2001,67(5):920-927

ABSTRACT: The effect of pH on thermal gelation and transglutaminase (TGase; EC2.3.2.13)-induced suwari (setting) of surimi and actomyosin pastes was investigated. A strong and elastic gel was produced from walleye pollack surimi paste at pH 7.0 in the presence of Ca²⁺ using a two-step heating method. In contrast, walleye pollack actomyosin paste formed a weak gel under the same conditions as a result of the low concentration of endogenous TGase. In the presence of EGTA [ethyleneglycol bis(2-aminoethylether) tetraacetic acid], weak gels were formed at pH values of 7.0 and 6.0. Non-proteolytic modori (gel weakening) occurred extensively in the course of actomyosin gelation, but not in surimi gelation. Maximum TGase-induced myosin heavy chain cross-linking was observed at a slightly higher pH of 7.5 than at the optimal pH of endogenous TGase activity; the difference being derived from different substrates. Gelation of carp actomyosin paste at pH values of 5.5, 6.0, 6.5 and 7.0 was monitored by measuring storage modulus (G') and loss modulus (G"). A weak gel was formed at all pH values, but a slightly rigid and less elastic gel was obtained at lower pH values. The addition of microbial TGase (MTGase) formed strong elastic gels at pH 7.0 and 6.5. MTGase cross-linked myosin heavy chains even at pH 5.5, but contributed neither to suwari response nor strong gel formation. Overall, results suggest that the optimal pH for the gelation of surimi paste from easy-setting fish species is a compromise between the pH-optima of TGase activity and of preferable actomyosin conformation for myosin cross-linking.  相似文献   

围网渔船起网时受力的实测与分析   总被引：1，自引：0，他引：1       下载免费PDF全文

胡明堉  周应祺  韦义辉  倪谷来 《水产学报》1991,15(1):17-26

通过对围网渔船起网过程中所受外力的实测和分析,表明在绞收括纲阶段临近结束时,即底环集中串挂在船舷括纲吊柱处时的外力,最大可达7,140公斤。起网时外力对船作用最终表现为外力矩,其数值与网具的纲索或网衣相对于船的出水点位置以及各种捕捞、起吊设备的安装位置有关,也即与力的作用线方向和作用点有关。作者认为在围网渔船稳性核核中,仅校核起吊底环和绞收网衣时的倾侧力矩是不够的,应选取整个起网过程中最大起网力矩(绞纲阶段末尾的倾侧力矩)用于渔船稳性校核和摇摆计算。  相似文献