用ICP—MS法测定四个不同地区泽泻中微量元素的含量

本文采用电热板—HNO_3—H_2O_2消解体系,电感耦合等离子体质谱(ICP—MS)法对分别产于福建建瓯、福建龙海、江西彭山、四川罐县等四个不同地区的泽泻进行微量元素的定量分析,通过数据处理统计,对泽泻中微量元素含量测定的结果、方法的准确性及其应用进行初步探讨。     

用络合滴定法测定镀铬液中硫酸的含量

一、方法要点在硝酸溶液中,硫酸根能与醋酸铅作用生成不溶于水的硫酸铅沉淀: H_2SO_4+Pb(C_2H_3O_2)_2=PbSO_4↓+2CH_3COOH 为了防止铬酸根与铅盐作用生成不溶于水的铬酸铅黄色沉淀,故用乙醇先将六价铬还原为三价铬: 2H_2CrO_4+6HNO_3+3C_H_5OH=2Cr(NO_3)_3     

饲料粗蛋白测定——前处理方法的改进

本文采用H_2O_2—H_2SO_4消解体系测定粗蛋白,用一种特制的消化装置滴加H_2O_2,结果表明,它与标准方法相比,具有省时、省电、省试剂的优点,可提高检测速度,而测定结果与标准法相近,证明该方法是可行的。     

Fenton试剂特性及其在水处理中的应用

根据文献资料,概述羟基自由基(HO·)的性质,系统介绍Fenton试剂及其几种类Fenton试剂H_2O_2+UV(ultraviolet),H_2O_2+Fe~(2+)+UV,H_2O_2+Fe~(2+)+O_2,H_2O_2+UV+O_2和H_2O_2+Fe~(2+)+UV+O_2的氧化特性,并对该领域国内外研究动态及在工业废水处理中的应用状况进行较为详细的阐述。     

不同消解方法对HG-AFS测定植物样品硒含量的影响

为研究不同消解方法对植物样品中硒含量测定的影响,分别采用电热板敞开消解、高压罐密闭加热消解和微波密闭消解3种方法对富硒荞麦的籽粒、茎叶和壳以及国家标准物质灌木枝叶(GSV-1、GSV-2、GSV-3)进行前处理。在氢化物原子荧光光谱法(HG-AFS)优化条件下,对样品中的硒含量进行测定。结果显示3种消解方法都能获得准确的结果,其中微波消解法的准确度、精密度和回收率最好;电热板敞开消解法波动性较大,但是该方法适合于大批量样品分析。在分析实践中,应根据样品量、硒含量和结果准确度要求选择合适的消解方法。     

铝及其合金在海水中的电化学保护

<正> 在中性介质中,在铝的阳极区和阴极区发生了如下反应[1]: 6H_2O+6_e=3H_2+60H——阴极反应 2Al+60H-be=Al_2O_3.3H_2O——阳极反应阴极极化时,阳极过程受到抑制,而阴极过程加强。结果,阴极附近水层的PH值增大;阳极极化时,电极附近水层稍有酸化。     

聚苯硫醚的大分子异相反应

采用KMnO_4、H_2O_2和浓H_2SO_4等氧化剂,在水介质中对聚苯硫醚(PPS)进行处理,结果表明,KMnO_4能将PPS表面层的S大部分氧化为砜基—SO_2—,但使PPS分子量增大的效果较差;H_2O_2能将PPS表面层的S氧化成亚砜基—SO—或砜基—SO_2—,以哪一种为主取决于H_2O_2的用量与反应时间。同时,氧化过程能使PPS的分子量增大,96％的H_2SO_4可使PPS表面层部分磺化而具有一定的H~+交换能力。然而,这些异相氧化反应对PPS的T_s无明显影响,它未能完全破坏粉末PPS的结晶相,但影响了PPS熔融后再结晶的能力。     

气体渗硼的热力学分析

本文通过热力学分析表明,在BCl_3+H_2介质中进行气体渗硼时,气氛中残留的 H_2O,O_2不仅使 BCl_3和 B 原子失去渗硼能力,加大了 BCl_3的消耗,而且加剧了 Fe—Cl 化合物的生成,导致渗层孔洞增加。     

304Cu抗菌不锈钢盐酸基酸洗工艺的研究

为了明确盐酸基酸洗液对含Cu抗菌不锈钢表面氧化层的酸洗行为,采用正交试验法研究以盐酸为基础,Fe~(3+)、H_2O_2和HNO_3为氧化剂的304Cu抗菌不锈钢酸洗工艺.并运用扫描电镜、透射电镜及电化学等手段分析经最佳配方酸洗后试样的表面形貌、成分及酸洗机理.结果表明:最佳酸洗工艺配方为HCl(36%~38%)120 ml/L、H_2O_2(30%)80 ml/L、FeCl_3·6H_2O 20g/L、HNO_310 ml/L,酸洗温度30℃,酸洗时间15 min.经该配方酸洗后材料表面平整度和光亮度较好,具有抗菌性能的点状ε-Cu相在基体上弥散分布.材料经酸洗去除氧化层后,仍具有足够含量的抗菌元素Cu存在.酸洗脱除氧化层过程由电荷传递过程控制,该酸洗液对不锈钢具有孔蚀诱导性,酸洗时间不宜过长.     

两种前处理方法对地表水中重金属含量测定效果比较

电热板消解法和微波消解法作为地表水及废水常规前处理方法在检验检测领域一直得到广泛使用。这两种前处理方法对于测定水质的金属含量各有各的特点。本文以漳州市古雷经济开发区东港南溪特殊水质为基体开展了电热板消解法和微波消解法在水质金属含量测定应用科学分析。研究结果表明;采用这两种前处理方法测得的Cu、Ni和Cr含量均低于国家标准方法检出限,在检测同一瓶样品的情况下,经微波消解法处理后的样品所测出金属含量均略高于电热板消解法。在其他同等条件下,微波消解法回收率比电热板消解法更接近于100%,且微波消解法具有速度快、所需实验人员要求人数少、药品用量少及不容易受污染等优点,使其成为本区域水质重金属首选方法。     

Stochastic Particle Barcoding for Single‐Cell Tracking and Multiparametric Analysis

This study presents stochastic particle barcoding (SPB), a method for tracking cell identity across bioanalytical platforms. In this approach, single cells or small collections of cells are co‐encapsulated within an enzymatically‐degradable hydrogel block along with a random collection of fluorescent beads, whose number, color, and position encode the identity of the cell, enabling samples to be transferred in bulk between single‐cell assay platforms without losing the identity of individual cells. The application of SPB is demonstrated for transferring cells from a subnanoliter protein secretion/phenotyping array platform into a microtiter plate, with re‐identification accuracies in the plate assay of 96±2%. Encapsulated cells are recovered by digesting the hydrogel, allowing subsequent genotyping and phenotyping of cell lysates. Finally, a model scaling is developed to illustrate how different parameters affect the accuracy of SPB and to motivate scaling of the method to thousands of unique blocks.     

Peptide-mediated constructs of quantum dot nanocomposites for enzymatic control of nonradiative energy transfer

A bottom-up approach for constructing colloidal semiconductor quantum dot (QDot) nanocomposites that facilitate nonradiative Fo?rster-type resonance energy transfer (FRET) using polyelectrolyte peptides was proposed and realized. The electrostatic interaction of these polypeptides with altering chain lengths was probed for thermodynamic, structural, and morphological aspects. The resulting nanocomposite film was successfully cut with the protease by digesting the biomimetic peptide layer upon which the QDot assembly was constructed. The ability to control photoluminescence decay lifetime was demonstrated by proteolytic enzyme activity, opening up new possibilities for biosensor applications.     

Propagation of the Anisimkin Jr.' and quasi-longitudinal acoustic plate modes in low-symmetry crystals of arbitrary orientation

The Anisimkin Jr. (AN) acoustic plate mode having dominant and depth-independent longitudinal displacement (u(1) > u(2), u(3); u(1) ≈ constant) is numerically found in tetragonal 4mm Li(2)B(4)O(7) crystal with one of the low-symmetry orientations (Euler angles 89°, 37°, 104°), as an example. The quasi-longitudinal (QL) modes with dominant and depth-dependent longitudinal displacement (u(1) > u(2), u(3); u(1) ≠ constant) are experimentally detected along several propagation directions Θ in 128°y-LiNbO(3) plate, where Θ = 0°, 30°, 60°, and 90° with respect to the x-axis. Compared with more symmetrical plate materials and orientations, the displacement profiles of the AN and QL modes in lower-symmetry counterparts are qualitatively the same, but their phase profiles are more complicated. Moreover, like any acoustic wave, all plate modes in anisotropic crystals suffer from beam steering, in general. The power flow angles of the modes propagating in a fixed direction are different and depend on the mode order n.     

Mass sensitivities of shear horizontal waves in three-layer platesensors

Explicit velocity and mass sensitivity formulas for shear-horizontal (SH) plate wave sensors loaded symmetrically on both sides of a plate are presented. The sensor geometry is a composite plate which consists of a central isotropic plate sandwiched symmetrically between two identical layers of isotropic solids. It is demonstrated that if the side layers are considered as the mass loading, for the lowest SH mode (SSo) the sensitivity decreases by a factor of (1-(μ ₂/ρ₂)/(μ₁/ρ₁)) due to the elasticity and by a factor of (1+ρ₂h/ρ₁d)^-1 due to the inertia of the mass loading layers, where μ₁,μ₂ ; ρ₁, ρ₂ and 2d, h are the shear moduli, densities and thickness of the central plate and of the side layers, respectively. For higher order modes, the behavior of sensors which are operated near cutoff frequency is analyzed. The mass loading decreases the cutoff frequencies of the higher order modes and near the cutoff frequencies the mass sensitivities are very high but decrease dramatically as the mass loading increases. Specific examples are given for the case of a fused silica plate sandwiched between two thin lucite layers     

圆板轴对称弯曲振动的模态声辐射效率

采用将声强对辐射面积分的方法获得轴对称弯曲振动圆板在固定、简支及自由边界条件下的模态辐射声功率,进而获得其模态声辐射效率.采用高斯-勒让德数值积分法计算出固定、简支及自由边界条件下圆板的模态声辐射效率的数值解,并将同阶模态三种不同边界条件下的圆板声辐射效率进行了对比.结果表明:(1)圆板的模态声辐射效率在全频段内大体呈...     

NK-HITEN610U2钢板及其焊接头抗H_2S应力腐蚀开裂性能

NK-HITEN610U2钢板已在我国用于液态烃球罐,由于液体烃中常含有水分和硫化氢,该材料在湿硫化氢环境中的耐蚀特性尚不明确.对采用回火焊道的焊接接头,经恒负荷拉伸、恒应变、焊接约束试板、氢诱导开裂、断裂韧性等试验和断口分析,对该钢板及其焊接接头在湿硫化氢环境中的抗H2S应力腐蚀开裂(SSC)性能进行了系统研究.发现其因母材中存在夹杂物偏析而对氢诱导裂纹(HIC)敏感,未经热处理的焊接接头,临界开裂应力指数Sc值小于10,材料在H2S介质中的临界应力强度因子KISCC值38 MPa·m-1/2,对SSC有一定的敏感性,认为用该材料在湿硫化氢环境中存在发生SSC的危险.据此,提出了球罐的检验和监控措施.     

石墨/ 高铝水泥模压复合材料双极板的特性

采用高铝水泥作为粘结剂, 石墨作为导电填料, 通过室温模压的方法制备了导电复合材料, 拟用于制作质子交换膜燃料电池的双极板。对石墨/ 高铝水泥复合材料双极板的电性能和力学性能的影响因数进行了分析和评价, 并测量了该复合材料双极板的含水量、凝胶毛细孔尺寸分布和氢气渗透性。实验结果表明: 含有60 wt %石墨的石墨/ 高铝水泥模压复合材料双极板的电导率和力学强度基本上可以同时满足质子交换膜燃料电池的使用要求; 并且该复合材料双极板含有凝胶毛细孔, 约具有7 wt %的含水量, 具有自增湿功能; 此外, 氢气渗透率也较低。      

硅氧烷改性水性聚氨酯乳液的附着性能

利用硅氧烷（γ-氨丙基三乙氧基硅烷（KH550）、γ-缩水甘油氧丙基三甲氧基硅烷（KH560））改性水性聚氨酯乳液,考察了改性后乳液成膜在无机基材表面附着力的变化。KH560改性的乳液成膜在无机基材表面具有较好的附着力,其中对玻璃的干附着力可达1级,对标准马口铁也可达1～2级;在浸水后,尤其在玻璃表面附着力保持最好,附...     

A proposed method of predicting ship collision damage

In the past, research on ship collision strength has centered on nuclear ship structures, but now emphasis is shifting to low-energy collisions of ordinary ships carrying hazardous cargoes including crude oil.A ship collision is too complex to study using theoretical methods alone, yet tests with small-scale models of thin steel plate fail to duplicate actual ship collision damage for the following reasons:

1. (1) The fracture of actual ship shell plate and model shell plate defies the law of similarity;

2. (2) Some structural members are usually omitted for ease of fabrication in relatively small models.

Accordingly, the authors propose a method for predicting ship collision damage that resorts to three combined experiments:

1. (1) A fundamental test determining the initiation of plate fracture;

2. (2) A local structure model test evaluating the effects of structural details;

3. (3) A structural model test investigating the deformation of a ship hull.

This paper reviews, by way of example, some results of the experimental studies which the authors have performed.The laws of similarity proved very important in the study of plate fracture.The authors believe that the proposed method will prove useful especially in dealing with low-energy ship collisions.     

Photothermal deflection determination of iron(II) with ferrozine with sorption preconcentration on Silufol plates

Photothermal deflection spectroscopy was applied to the selective detection of iron(II) chelate with ferrozine by its sorption preconcentration on Silufol plates. The linearity range was 1 x 10(-11) - 6 x 10(-8) mol cm(-2) of chelate at the plate surface, which corresponded to 1 x 10(-9) -4 x 10(-6) M of chelate in solution. The limits of detection and quantification are 8 x 10(-12) and 2.5 x 10(-11) mol cm(-2) at the plate from 15 microL of test solution (0.5 nM and 1.5 nM in solution, respectively), and the absolute detection limit is 8 fmol in the whole spot applied to a plate. Characteristics and features of photothermal deflection detection are discussed.