固相萃取填料对有机磷农残萃取效率

以花椰菜中杀扑磷和马拉硫磷为研究对象,比较C18、Florisil和HLB柱的萃取效率.样品经过固相萃取柱富集后,使用高效液相色谱分析.通过比较不同固相填料的萃取回收率,选择最佳的萃取条件及萃取小柱.结果表明,3种固相填料中,Florisil柱的萃取回收率最高.经过对实际样品的加标实验后,两种有机磷农药的回收率在79%~112%之间,适合花椰菜中痕量有机磷农药残留测定的分析要求.     

SPE-HPLC/UV法同时检测牛奶中5种三嗪类除草剂的残留

建立了同时检测牛奶中残留的5种三嗪类除草剂的高效液相色谱法。实验使用不同的固相萃取柱(C18、LiChrolut EN)对目标物进行富集,以乙腈和磷酸盐缓冲溶液(pH=7.4)为流动相,在1.2 mL/min的流速、220 nm的紫外检测波长下进行高效液相色谱分析。结果表明,其检测限和量化限分别为0.13、0.38μg/L,回收率为62.2%~95.1%,精密度为2.3%~10.5%,线性关系非常好,r2(0.9970,且分析步骤易于程序化,可以满足牛奶中三嗪多残留检验工作的需要。     

以SPE作为UV法测定硝酸盐氮的预处理方法

针对水样中有机物和浊度严重干扰紫外分光光度法测定硝酸盐氮的问题,分析了ENVI-18,LC-8,HLB(亲水亲油平衡)和自制PAC(粉末活性炭)四种固相萃取柱对水样中有机物和浊度等干扰的消除效果.研究结果显示:当进水水样DOC质量浓度为4mg/L时,自制PAC固相萃取柱和LC-8型固相萃取柱对水样中有机物的保留率均大于99.5%,而HLB和ENVI-18型固相萃取柱对有机物的保留率低于6.75%.ENVI-18和LC-8柱对水中硝酸盐氮不具有保留效果也不会向水中释放干扰硝酸盐氮的物质,PAC柱对水中硝酸盐氮具有强烈的保留作用,HLB柱则会向水中释放少量的干扰硝酸盐氮测定的物质.优选LC-8型固相萃取柱作为预处理小柱,并在宜兴西氿水上进行了应用,结果显示:加标回收率为94.0%~97.0%,相对标准偏差为3.14%.每支规格为500mg/3mL的LC-8型固相萃取柱能保留水中约0.75mg有机物(以DOC计),可处理10~15个水样,使用后的固相萃取柱可采用甲醇再生后再次使用.     

HPLC测定牛奶中阿莫西林和青霉素G的残留

建立了高效液相色谱(HPLC)同时测定牛奶中阿莫西林和青霉素G的方法。牛奶样品用乙腈提取脱蛋白,离心取上清液,旋转蒸发干后,用磷酸二氢钾溶液溶解定容,经HYPERSEP C18固相萃取柱净化。以C18柱为分离柱,以乙腈和水为流动相,梯度洗脱。该方法采用外标法,在1.0 ng/mL～100.0 ng/mL范围内,青霉素G和阿莫西林的峰面积与对应的浓度成良好的线性关系(r=0.999 5、0.999 7)。在低、中、高三个水平下的加标回收率为89.25%～94.13%,相对标准偏差(RSD)1.02%～1.43%(n=3)。该方法简便快捷,可适用于牛奶中阿莫西林和青霉素G的同时测定。     

高效液相色谱测定蔬菜中拟除虫菊酯类农药残留

将自制的弗罗里硅土固相萃取柱用于蔬菜中拟除虫菊酯农药残留的研究,建立了固相萃取-高效液相色谱(SPE-HPLC)同时测定蔬菜中甲氰菊酯、三氟氯氰菊酯、溴氰菊酯、氰戊菊酯和氯菊酯农药残留的方法,测定了4种蔬菜样品,平均回收率分别为卷心菜80.7%~106.2%,花菜80.5%~102.6%,红萝卜63.0%~109.3%,青椒74.9%~109.0%,相对标准偏差≤14.5%.     

气相色谱法测定蔬菜中残留的甲氰菊酯农药

文章对蔬菜中甲氰菊酯农药残留测定的样品预处理方法和检测条件进行了优化研究。采用乙腈振荡提取、Strata FL-PR Florisil(1000mg/6mL)固相萃取柱净化、浓缩以及电子捕获/气相色谱法检测。蔬菜样品中的添加浓度为0.1~1.0μg/mL时,添加回收率为97.3%~100.1%,相对标准偏差为1.59%~2.36%。     

基于新型固相萃取-高效液相色谱法灵敏测定牛奶中的药物残留

利用水热法制备了还原氧化石墨烯-硅胶复合物,将其用于固相萃取柱制备,并与高效液相色谱相结合,建立了牛奶中磺胺类药物测定的新方法.对萃取条件进行了优化,优化条件为:0.1 mL的甲醇-乙酸(V∶V′=1∶1.5)混合液为洗脱剂,75mL的样品溶液.在优化条件下,目标物的线性范围为0.1~100μg/L,检出限为0.027~0.078μg/L(RSN=3).新方法用于牛奶样品分析,加标回收率为88.3%~113.6%.     

氯霉素分子烙印固相萃取柱的制备及萃取条件优化

采用分子烙印技术制备了氯霉素的分子烙印固相萃取柱,并通过对其吸附能力、解吸条件等特性的研究,确定了分子烙印固相萃取柱的上柱、淋洗和洗脱条件．结果表明,与目前氯霉素检测中所采用的传统C18柱相比,分子烙印固相萃取柱可采用甲醇含量较高的甲醇／水混合溶剂作为淋洗溶剂,用乙腈含量为40％(体积分数)的乙腈／水作为洗脱溶剂,且比传统C18柱具有更大的柱容量．分子烙印固相萃取柱的优点使其可应用于实际生物样品中氯霉素的检测,以解决目前氯霉素残留检测中面临的难题．     

液相色谱/质谱法测定生鲜牛奶中的两种氨基甲酸酯农药残留

建立了高效液相色谱-质谱法同时测定生鲜牛奶中杀线威、涕灭威残留量的方法。样品用乙酸乙酯提取,C18固相萃取柱纯化、富集,采用电喷雾正离子模式离子化。在质谱图中,[M Na] 强度最大,定量测定使用多离子监测模式m/z:242→72,213→116。杀线威、涕灭威的检测限分别为0.4 ng、0.1 ng,方法的平均回收率:杀线威为92.5%~95.6%、涕灭威为91.6%~93.4%。方法的灵敏度高,选择性好。用于实际样品的分析,获得满意的效果。     

固相萃取-高效液相色谱法测定蛹虫草中虫草素的含量

建立了超声提取样品、固相萃取-高效液相色谱法(SPE-HPLC)测定蛹虫草中虫草素的方法.实验对样品的提取和净化方法以及检测条件进行了选择和研究,具有操作简便、快速、重现性和精密度好的特点.方法用于实际样品中虫草素的测定,加标回收率在93.2%~98.7%之间,相对标准偏差<3.2%.     

二元序列的翻转与对换排序

序列的翻转与对换的排序问题因在基因组比较中的应用而受到关注．考虑二元序列的翻转与对换的排序问题，分别给出了二元序列的翻转排序与对换排序的近似算法．     

Replication by human DNA polymerase-iota occurs by Hoogsteen base-pairing

Almost all DNA polymerases show a strong preference for incorporating the nucleotide that forms the correct Watson-Crick base pair with the template base. In addition, the catalytic efficiencies with which any given polymerase forms the four possible correct base pairs are roughly the same. Human DNA polymerase-iota (hPoliota), a member of the Y family of DNA polymerases, is an exception to these rules. hPoliota incorporates the correct nucleotide opposite a template adenine with a several hundred to several thousand fold greater efficiency than it incorporates the correct nucleotide opposite a template thymine, whereas its efficiency for correct nucleotide incorporation opposite a template guanine or cytosine is intermediate between these two extremes. Here we present the crystal structure of hPoliota bound to a template primer and an incoming nucleotide. The structure reveals a polymerase that is 'specialized' for Hoogsteen base-pairing, whereby the templating base is driven to the syn conformation. Hoogsteen base-pairing offers a basis for the varied efficiencies and fidelities of hPoliota opposite different template bases, and it provides an elegant mechanism for promoting replication through minor-groove purine adducts that interfere with replication.     

用修正学习曲线测算井段的钻井时间

将学习曲线与传统的分段方法结合起来,既克服了分段法中不考虑学习效果的缺陷,又克报了学习曲线中不能灵活调整的缺陷,形成两种方法的优点叠加．用学习曲线测算井段的钻井时间,其前提条件是：各井在该井段的钻头选型基本相同,井段直径相同,所穿过的地层相同,所属的井型相同．对钻井参数（钻压、转速、泵压、排量）、泥浆密度与性能、喷嘴直径与个数等时变性因素,不单独列出,而作为在钻井过程中通过逐步学习加以改善的对象．用塔北某地区１号构造上所钻井的二开井段（４４４．５ｍｍ）实际资料测算,得到的结果明显优于钻井监督的计划时间,测算的最大相对误差１１．８％,平均为８．８％,而监督组计划误差为４１．９％,平均误差率降低了一半以上．     

Self powered systems by nanogenerators and smart MEMS by piezotronics

Developing wireless nanodevices and nanosystems is of critical importance for sensing, medical science, environmental/infrastructure monitoring, defense technology and even personal electronics. It is highly desirable for wireless devices to be self powered without using battery, without which most of the sensor network may be impossible. The piezoelectric nanogenerators have the potential to serve as self sufficient power sources for micro/nano systems. For wurtzite structures that have non central symmetry, such as ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a strain. The nanogenerator is invented by using the piezopotential as the driving force for electrons to flow in respond to a dynamic straining of piezoelectric nanowires. A gentle straining can produce an output voltage of up to 20～50 V from an integrated nanogenerator. Furthermore, piezopotential in the wurtzite structure can serve as gate voltage that can effectively tune/control the charge transport across an interface/junction; electronics fabricated based on such a mechanism is coined as piezotronics, with applications in force/pressure triggered/controlled electronic devices, sensors, logic units and memory. By using the piezotronic effect, it is showed that the optoelectronic devices fabricated using wurtzite materials can have superior performance as solar cell, photon detector and light emitting diode. Piezotronic is likely to serve as “mechanosensation” for directly interfacing biomechanical action with silicon based technology and active flexible electronics. The paper gives a brief review about the basis of nanogenertors and piezotronics and their potential applications in smart MEMS (micro electro mechanical systems).     

基于Fenton反应的羟基自由基对胶原蛋白的氧化降解作用

研究了Fenton反应产生的羟基自由基对Ⅰ型胶原蛋白的降解作用。单独的过氧化氢(H2O2),Fe2+以及超氧阴离子自由基(O2-·)均对胶原蛋白无降解作用。但是,在经过氧化氢和Fe2+构成的Fenton反应产生羟基自由基后,胶原蛋白发生了降解。胶原蛋白的降解作用随着羟基自由基的增加(H2O2+Fe2+浓度增加)而加强。但羟基自由基的生成是瞬间完成的,其对胶原蛋白的降解作用随着H2O2和Fe2+反应时间的延长而降低。