新型液-液微萃取--气相色谱法测定海水中的有机氯农药

本文采用了一种新型的液---液两相微萃取技术作为海水样品前处理方法,对海水中的八种有机氯农药(α-BHC,β-BHC,γ-BHC,δ-BHC,p,p,-DDE,o,p,-DDT,p,p,-DDD,p,p,-DDT)进行萃取、富集和分离,采用配微池电子捕获检测器气相色谱法分析测定。对影响萃取效率的因素进行了优化。结果表明,在优化条件下,六六六、滴滴涕在1.0-100.0μg/L范围内有良好的线性关系,R≥0.9963,检测限为0.004~0.016μg/L。     

茶叶中六六六、滴滴涕含量检验方法初探

有机氯农药六六六，滴滴涕的结构稳定，不易分解，特别是在酸性土壤中可保持10年以上．因此，国家已明文规定不再使用六六六，滴滴涕这类农药。但是，由于过去长期使用该种农药，土壤中已积蓄了大量的六六六和滴滴涕，部分农副产品中已有了农残存在。作为与人们生活密切相关的产品茶叶，     

气相色谱法快速测定灌溉水和土壤中六六六、滴滴涕的残留量

本文介绍了利用配有电子捕获检测器的气相色谱仪测定灌溉水和土壤中六六六、滴滴涕残留量的方法。试样加水稀释,加入少量氯化钠,再用正己烷提取,浓硫酸净化样品,排除干扰杂质,以GC-ECD测定,外标法定量,六六六和滴滴涕在0.005～0.2μg·mL-1范围内,质量浓度与峰面积呈良好的线性关系。该方法准确,分析时间短,重现性、精密度好,杂质干扰少。样品回收率在85.1%～109.5%之间,适用于大量样品中六六六、滴滴涕的检测。     

畜禽产品质量安全与标准化

一、我国畜禽产品（主要指肉产品）质量安全现状（１）畜禽产品中农药残留现状分析据安徽（国家）农业标准化与监测中心在２００１年全年的抽检报告显示，现国内畜禽肉农药残留主要为蝇毒磷、敌百虫、敌敌畏、滴滴涕、六六六、和三氯乙烯等的有机氯、有机磷农药公害问题最大。以滴滴涕和六六六为例，猪肉、猪内脏、鸡肉、鸡蛋中，六六六的检出率在６０％－１００％，超标率在３％－８％（超标９倍以内者居多）。滴滴涕的检出率在０％－１００％，超标率在０％－７４％（超标６．５倍以内者居多）。就残留平均值来看，滴滴涕和六六六虽大都超…     

亮镍液直接转化为镍铁合金镀液

镍铁合金电镀,因为镀层中以25%左右的廉价铁取代了价格昂贵的镍,使电镀成本显著降低,加之合金镀层的韧性、整平性好,产品质量可与亮镍媲美。由于亮镍镀液很容易转化为镍铁合金镀液,且镀液转化配制方法简单可行,所以近年来发展很快。但目前乡镇企业中大多仍用传统镀镍法,无疑加重了工厂负担,甚有因镍材短缺而面临停产的危机。因此,如果利用原有亮镍液直接转化为镍铁合金镀液,定会收到较好的经济效益。     

实验室液-液转盘萃取装置的改进

转盘塔为液液萃取中的重要设备之一，广泛应用于石油化工、废液处理、制药生产等工业。它具有结构简单、操作方便、处理量大、适应性强与萃譬效率高等诸多优势。随着工业的发展，对转盘塔做了不少的的研究和改进，进一步更好的提高分离效率。     

气相色谱法测定土壤中的六六六、滴滴涕

建立了土壤中六六六、滴滴涕残留量的气相色谱检测方法。样品经石油醚／丙酮（1：1）提取、浓硫酸净化，气相色谱分离后，电子捕获检测器检测，外标法定量。样品加标回收率在89．7％-113．6％之间，精密度RSD为1．4％-3．0％。结果表明，该法简便、灵敏、准确，适用于土壤中的六六六、滴滴涕残留量的分析。     

液-液界面生长法制备C_(60)晶体

常温常压下利用液-液界面生长法制备了不同形貌的C60晶体,并对其生长机理进行了初步探讨。采用扫描电镜和X射线衍射分别对晶体形貌和结构进行了表征,结果表明,在CS2-异丙醇两相界面上可以生长形貌均匀的棒状晶体,且获得的晶体结构为简单六方。     

巧用Origin8.0软件绘制双液系气液平衡相图

结合双液系气液平衡相图实例,利用Origin8.0软件强大的图形绘制和数据处理功能,介绍了3种双液系气液平衡相图绘制方法,同时给出了具体的操作步骤。该方法简单、实用,不仅适用于物理化学试验,还可应用于其他试验教学和科学研究的数据处理和图形绘制。     

分散固相萃取-气相色谱-质谱方法快速检测丝瓜中的六六六和滴滴涕

建立了快速测定丝瓜中的六六六和滴滴涕残留的方法(QuEChERS).该方法以乙腈作提取剂,以PSA和C18作分散净化剂,用气相色谱-质谱在选择离子监测模式下检测,并使用以外标法定量,六六六和滴滴涕的线性良好,3个添加水平的回收率分别为66%～119%,63%～120%和68%～98%,检测限在0.4～16.4ug/kg.     

特种工程塑料聚醚砜、聚醚醚酮树脂国内外研究、开发、生产现状

本文在简单介绍了特种工程塑料的 2个主要品种———PES、PEEK的国内外研究、开发、生产现状基础上 ,对 2种树脂的主要特性、应用领域和国产树脂的主要牌号和情生指标等作了较详细的介绍。     

Ideal Point Discriminant Analysis and Ordered Response Categories

Many contingency tables have ordered response categories. This paper compares two major approaches to ordinal response categories, namely the point representation and the block (interval) representation. Specifically, two methods are compared, each representing each of the two approaches. One is ideal point discriminant analysis (IPDA) and the other the succes sive categories method (SCM). Similarities and distinctions between the two methods are explicated. The goodness-of-fit (GOF) is compared through AIC using several example data sets. IPDA and SCM were found to provide similar GOF, but IPDA was found to provide a slightly better fit in all the data sets examined.

     

Constructivity and completeness of the general solutions in elastodynamics

Summary There are two general solutions in clastodynamics, which are the Cauchy-Kovalevski-Somigliana general solution (call it CKS for short) and the Boussinesq-Papkovich-Neuber general solution (BPN). In this paper, by constructing two new kinds of decomposition for any vector, the potential functions in CKS and BPN are constructed. Thus the completeness of the two general solutions gets proved in a pithy style. In addition, we also establish the evident relation between the two general solutions.     

Optimal control and anti-control of the nonlinear dynamics of a rigid block

This paper deals with control and anti-control of overturning of a rigid block subjected to a generic periodic excitation. Attention is focused on two relevant thresholds, corresponding to heteroclinic bifurcation and immediate overturning, and representing lower and upper bounds of the region where toppling can occur. The two opposite problems of increasing (control) or decreasing (anti-control) of these two curves by properly modifying the shape of the excitation are investigated in depth and the optimal excitations permitting their maximum variations are determined. The notions of 'global' and 'one-side' control (anti-control) are utilized and their different importance for the various cases is discussed. The effects of control (anti-control) of one curve on the uncontrolled (non-anti-controlled) curve are also investigated, both analytically and with numerical overturning charts. A good agreement is seen to occur.     

New adders using hybrid circuit consisting of three-gate single-electron transistors (TG-SETs) and MOSFETs

A half-adder (HA) and a full-adder (FA) using hybrid circuits combining three-gate single-electron transistors (TG-SETs) with metal-oxide-semiconductor field-effect-transistors (MOSFETs) are proposed. The proposed HA consists of three TG-SETs, two enhanced-mode NMOSFETs, and two depletion-mode NMOSFETs, and the proposed FA consists of eight TG-SETs, two enhanced-mode NMOSFETs, and two depletion-mode NMOSFETs. The complexities in the HA and the FA are 7 and 12, respectively, and the worst-case delays in the HA and the FA are 1.48 ns and 2.25 ns, respectively. Compared with the conventional CMOS FA with 0.35 microm technology, the proposed FA can be constructed with 0.43 of devices, and can operate with 3.5 of worst-case delay, 1/534 of average power consumption, and 1/152 of power-delay-product (PDP). The proposed HA and FA can be operated as a half-subtractor (HS) and a full-subtractor (FS) in the case when the levels of the control gates in the HA and the FA are fitly determined. The basic operations of the proposed HA and the proposed FA have been successfully confirmed through SPICE circuit simulation based on the physical device model of TG-SETs.     

Frequency-selective surfaces with two sharp sidebands realised by cascading and shunting substrate integrated waveguide cavities

Frequency-selective surfaces (FSSs) with two sharp sidebands have been investigated, which are constructed by cascading and shunting two substrate integrated waveguide cavities (SIWCs) of different sizes with periodic slots at top and bottom metal surfaces. The lower and upper sharp sidebands are induced by two transmission nulls that are generated by coupling between the slot aperture resonance and the resonances in the two cavities. Samples of the shunted SIWC-FSS with different size cavities were fabricated. Measured results are in good agreement with the predicted ones and its performance, such as high selectivity and passband bandwidth, is stable at oblique incidence.     

Assessing technophobia and technophilia: Development and validation of a questionnaire

Nowadays technology is in every aspect of our lives. The exponential growth of new information technologies during recent years has increased society's enthusiasm and visionary expectations (technophilia), as well as fears and discomfort (technophobia). However, technophobia and technophilia are two concepts that are hardly studied, with very few specific measurements developed so far. The present paper aims to develop and validate the Technophobia and Technophilia Questionnaire (TTQ) in a sample composed of 534 participants from two different countries (Poland and Estonia). Practical implications, study limitations and directions for future research are discussed.     

Thermo-optical parameters and dispersion of pure and Yb(3+)-doped KY(WO4)2 laser crystals

Dispersion of the principal refractive indices of pure and Yb(3+) (20 at.%)-doped KY(WO(4))(2) crystal is obtained in the visible range of the spectrum. A comparatively strong increase of the refractive indices (0.005-0.007) was observed for the doped crystal. Temperature dependence of the principal refractive indices is measured in the temperature region of 290-690 K. Thermo-optical coefficients (TOCs) of the first dn/dt and the second (1/2)(d(2)n/dT(2)) order are determined. It is found that TOCs are negative for n(p) and n(g) and positive for n(m) in both crystals. Doping increases dn(p)/dT almost two times more in comparison to that of the pure crystal, while for the other two indices TOC changes are insignificant.     

CO2角焊中手工与角焊机作业方式的对比研究

利用工作研究的技术和方法对船厂焊接操作中常用的两种CO2角焊工作方式进行了研究,建立了标准化的操作程序,并为两种工作方式建立了评价指标及评价函数,从而得出适用于两种作业方式的选择条件,为合理选择手工焊作业与角焊机作业,提高焊接作业生产效率提供了依据。     

Fast and meta-heuristics for common due-date assignment and scheduling on parallel machines

This study considers common due-date assignment and scheduling on parallel machines. The problem has three decision variables: assigning the common-due-date, allocating jobs to parallel machines, and sequencing the jobs assigned to each machine. The objective is to minimise the sum of due-date assignment, earliness and tardiness penalties. A mathematical programming model is presented, and then two types of heuristics are suggested after characterising the optimal solution properties. The two types of heuristics are: (a) a fast two-stage heuristic with obtaining an initial solution and improvement; and (b) two meta-heuristics, tabu search and simulated annealing, with new neighbourhood generation methods. Computational experiments were conducted on a number of test instances, and the results show that each of the heuristic types outperforms the existing one. In particular, the meta-heuristics suggested in this study are significantly better than the existing genetic algorithm.