Rapid determination of organochlorine pesticide residues in feeds by capillary gas chromatography

A simple micro-method is described for determination of 15 organochlorine pesticide residues in mixed feeds. Clean-up of the petroleum ether extract is by basic alumina minicolumn chromatography and quantitative identification is by capillary gas chromatography with electron capture detection. Cyanopropyl-polysiloxane chemically bonded fused silica capillary columns have been used to perform high resolution analyses in short time as well as to overcome possible interferences by PCBs. Recovery, repeatability, and detection limits of the proposed procedure are checked and results are also reported for non random samples of 180 feeds collected in Italy.     

Transferkoeffizienten im System Boden—Pflanze in verschiedenen Lokalitäten der Tschechoslovakei

Für die Ermittlung der Transferkoeffizienten im System Boden–Pflanze wurden in drei Stellen der Tschechoslovakei Boden- und Pflanzenproben entnommen. Die niedrigsten Transferkoeffizienten für Getreide und für mehrjährige Futterpflanzen wurden in der Ostslovakei festgestellt. Die Werte der Transferkoeffizienten waren durch den Bodentyp, den Gesamt-Sorptionskapazität und dem Grad der Sorptionssättigung beeinfluβt.

Soil and plant samples were sampled for the determination of soil to plant transfer coefficients in three various Czechoslovak sites. The lowesl transfer factors for cereals and fodder were determined in the site of Eastern Slovakia. Values of transfer factors depend on soil type, cation exchange capacity and base saturation of soils.     

UPLC - ESI MS/MS法测定动物饲料中苯二氮卓类药物

建立了超高效液相色谱-电喷雾串联质谱(UPLC - ESI MS/MS)同时检测动物饲料中地西泮、奥沙西泮、硝西泮、三唑仑、艾司唑仑和咪达唑仑6种苯二氮卓类药物的方法.饲料样品采用碱性叔丁基甲醚提取,Oasis MCX固相萃取柱净化,反相色谱柱分离,以0.1％甲酸和乙腈为流动相进行梯度洗脱,正离子模式扫描,多反应监测模...     

阵列馈源偏置抛物面天线合成高功率微波的研究

 运用物理光学分析方法，对使用7单元的扇形喇叭一维阵列和角锥喇叭或圆锥喇叭三角形阵列喇叭束作为单偏置抛物面天线的馈源，空间合成高功率微波进行了比较研究，数值分析表明在阵元输入功率、口面最大场强、天线口径、净空间及天线边缘照度相同,且阵列馈源具有准轴对称主瓣条件下，扇形喇叭构成的一维阵列馈源与单偏置抛物面组成的天线系统的方向性系数和溢出效率优于采用角锥喇叭三角形阵列馈源或圆锥喇叭三角形阵列馈源的天线系统。若将喇叭束直接作为辐射天线使用，由于圆锥喇叭三角形阵列方向性系数对阵元间相位波动的稳定性较好，而更具优势。     

固相萃取-液相色谱-质谱/质谱法同时测定蜂蜜中的多类药物残留

建立了采用固相萃取-液相色谱-质谱/质谱(SPE-LC-MS/MS)对蜂蜜中磺胺类、硝基咪唑类、喹诺酮类、大环内酯类、林可酰胺类和吡喹酮共计6大类54种药物残留同时测定的方法。蜂蜜经磷酸盐缓冲溶液(pH 8)稀释,Oasis HLB固相萃取柱净化后,通过液相色谱-质谱联用技术进行检测(正离子方式,多反应监测模式)。采用同位素稀释内标法或外标法进行定量,线性关系良好,相关系数大于0.992。方法的定量限(LOQ,以信噪比(S/N)大于10计)分别为磺胺类和硝基咪唑类药物1.0 μg/kg,喹诺酮类和林可酰胺类药物2.0 μg/kg,大环内酯类药物3.0 μg/kg,吡喹酮0.3 μg/kg。总体回收率为32.6%～114%,相对标准偏差为1.3%～28.9%。该方法的定量限满足目前国内外药物的最大残留限量要求,可作为蜂蜜中相关药物残留量的筛选检测方法。     

换能器前辐射头与轴向相平行方向的弯曲振动

复合棒型换能器前面的变截面组件在工作时常伴有弯曲振动现象，这在一定程度上会影响换能器的工作性能；利用复合棒型换能器的纵向振动基频与前辐射头弯曲振动的恰当耦合，可展宽换能器的频带。本文用有限元法，研究了前辐射头在声换能器组成中的弯曲振动问题，与测试结果相吻合。     

All General Solutions of Post Equations

In a previous paper, we have described all reproductive general solutions of a Post equation, supposing that a general solution is known. In this paper we describe all general solutions of Post equation, supposing that a general solution of this equation is known （Theorem 6）. As a special case we get the previous characterization of reproductive solutions and a similar result for Boolean equations （Theorem 9）.     

OPTIMAL MODEL OF COMBINED PHASE CENTER FOR HORN FEEDS AND ITS COMPUTATIONAL METHOD

A definition of combined phase center for horn feeds is given.Formulas of E-planeand H-plane combined phase center for conical horns and the corresponding Optimal model arepresented,and a fast optimization method for solving this model is described.By using thismethod,the phase center of corrugated horn is discussed and calculated,and the variation of thephase center with distance and operating frequency is given.     

Exclusive and essential sets of implicates of Boolean functions

In this paper we study relationships between CNF representations of a given Boolean function f and certain sets of implicates of f. We introduce two definitions of sets of implicates which are both based on the properties of resolution. The first type of sets, called exclusive sets of implicates, is shown to have a functional property useful for decompositions. The second type of sets, called essential sets of implicates, is proved to possess an orthogonality property, which implies that every CNF representation and every essential set must intersect. The latter property then leads to an interesting question, to which we give an affirmative answer for some special subclasses of Horn Boolean functions.     

On the Boolean connectivity problem for Horn relations

Gopalan et al. studied in [P. Gopalan, P.G. Kolaitis, E.N. Maneva, C.H. Papadimitriou, The connectivity of Boolean satisfiability: computational and structural dichotomies, in: Proceedings of the 33rd International Colloquium on Automata, Languages and Programming, ICALP 2006, 2006, pp. 346-357] and [P. Gopalan, P.G. Kolaitis, E.N. Maneva, C.H. Papadimitriou, The connectivity of Boolean satisfiability: computational and structural dichotomies, SIAM J. Comput. 38 (6) (2009) 2330-2355] connectivity properties of the solution-space of Boolean formulas, and investigated complexity issues on the connectivity problems in Schaefer’s framework. A set S of logical relations is Schaefer if all relations in S are either bijunctive, Horn, dual Horn, or affine. They first conjectured that the connectivity problem for Schaefer is in P. We disprove their conjecture by showing that there exists a set S of Horn relations such that the connectivity problem for S is -complete. We also investigate a tractable aspect of Horn and dual Horn relations with respect to characteristic sets.