Synthesis of homo- and heteronuclear ruthenium-gold clusters with diphosphine and thiolato bridged ligands. Single crystal molecular structure of [Ru3(CO)10(μ-AuPPh3)(μ-SC5H4N)] and [Ru3(CO)8(μ-H)(μ-SC5H4N)(μ-dppe)]

The reaction between [Ru₃(CO)₁₀(NCMe)₂] and [AuClPPh₃] gave compound [Ru₃(CO)₁₀(μ-Cl)(μ-AuPPh₃)] (1) in quantitative yield under very mild conditions. The reaction of 1 with 4-mercaptopyridine (4-pyS) using ultrasonic reaction conditions gave the heteronuclear compound [Ru₃(CO)₁₀(μ-AuPPh₃)(μ-SC₅H₄N)] (2) in moderate yield. There was no spectroscopic evidence that indicates the formation of the hydride isolobal analog in this reaction. The homonuclear cluster [Ru₃(CO)₈(μ-H)(μ-SC₅H₄N)(μ-dppe)] (3) was prepared by a selective reaction employing the ruthenium-diphosphine derivative [Ru₃(CO)₁₀(μ-dppe)] (dppe = 1,2-bis(diphenylphosphine)ethane) with 4-pyS in THF solution. The isolobal analog to compound 3, compound [Ru₃(CO)₈(μ-AuPPh₃)(μ-SC₅H₄N)(μ-dppe)] (4) was synthesized by the reaction between compound 2 and dppe in refluxing dichloromethane. Compounds 1-4 were characterized in solution by spectroscopic methods and the molecular structure of compounds 2 and 3 in the solid state was obtained by single crystal X-ray diffraction studies.     

Improvements in monitoring the N-terminal valine adduct in human globin after exposure to sulfur mustard and synthesis of reference chemicals

The N-terminal valine adduct (HETE-Val) in globin is believed to behave as a long-lived biomarker after exposure to sulfur mustard (HD). Development of a highly sensitive method for monitoring HETE-Val, particularly at low HD exposure levels or for retrospective detection, would be a significant achievement. In this study, by improving the sample preparation method, a sensitive NCI-GC/MS method was established for the analysis of HETE-Val in globin after HD exposure. To optimize and investigate the sample preparation method, all the relevant HETE-Val chemicals were synthesized, purified, and characterized. By carrying out optimized solid phase extraction (SPE) cleanup followed by modified Edman degradation results in a low detection level and clean baseline. The minimum detectable exposure level of human blood (in vitro) to HD is 20 nmol/L (S/N > 3). The interday and intraday precisions of the proposed method were found to be acceptable with less than a 15% relative standard deviation (RSD). A nearly linear dose-effect relationship was observed between HETE-Val and a HD exposure concentration range of 0.1-120 μmol/L. The percentage of HD that reacted with N-terminal valine in globin obtained from human blood (in vitro) was quantified using the proposed method.     

离子色谱同时测定中草药中磷硫含量

应用离子色谱法同时测定了硫酸根和磷酸根的含量。用茶叶(GBW10016)、柑橘叶(GBW10020)和黄芪(GBW10028)标准物质来验证方法的准确性,测定值与标准值基本吻合。磷在0.01～100.0μg/mL,硫在0.01～60.00μg/mL范围内呈良好的线性关系(R2≥0.9993),磷和硫的检出限分别为0.0...     

苯并三唑对水泥砂浆中钢筋的阻锈作用

应用腐蚀电位(E_corr)、极化电阻(R_p)和砂浆保护层电阻率(ρ_c)研究了苯并三唑(BTA)对钢筋电极腐蚀电化学行为的影响. 通过电化学阻抗谱(EIS)、循环极化(CP)和循环伏安(CV)结果对比了BTA与NaNO₂ (SN)对钢筋电极在未处理、预锈蚀和内掺氯盐3种状态下3.5% (w)氯盐浸泡360 d后的阻锈效率. 利用环境扫描电镜(ESEM)与能谱分析(EDS)解释了BTA对水泥基材料中钢筋的阻锈机理. 结果表明: 3种状态下BTA均能明显降低砂浆中钢筋的均匀腐蚀速率, 且其阻锈效率高于SN. 在未处理与预锈状态下, BTA抑制点蚀的能力稍弱于SN; 但在内掺氯盐的状态下, BTA表现出了较大的点蚀阻力. BTA除了能在钢筋表面形成复杂的保护膜, 从而有效抑制氯盐的破钝化作用. ESEM/EDS结果表明BTA还能与砂浆基体形成较多富钙C-S-H凝胶, 可能优化了钢筋/砂浆界面区的孔结构, 形成更致密的微观结构, 显著延缓了氯盐向钢筋表面的传输进程, 较好地保护了钢筋. 适量的BTA对砂浆360 d的基本力学性能无明显影响.     

溶胶-凝胶-水热晶化法制备锐钛矿TiO2纳米膜的耐蚀性能

以钛酸正丁酯为前驱体, 采用溶胶-凝胶-水热晶化法在不锈钢(SS)表面制备TiO₂纳米膜. 利用X射线衍射(XRD)、Raman光谱、场发射扫描电子显微镜(SEM)、原子力显微镜(AFM)和俄歇电子能谱(AES)表征了TiO₂纳米膜的晶型、表面形貌和表面化学组成. 通过极化曲线和电化学阻抗谱(EIS)研究了TiO₂纳米膜的耐蚀性能. 170 °C下水热晶化制备的锐钛矿TiO₂与450 °C焙烧制备的锐钛矿TiO₂的结晶度类似, 但两种TiO₂薄膜的表面结构存在明显差异, 水热晶化法制备的TiO₂纳米膜在3.5% (w) NaCl溶液中的耐蚀性能优于焙烧法制备的.     

Application of Modified Tafel Analysis to the Identification of Corrosion Products on Archaeological Metals Using Voltammetry of Microparticles

An operational modification of Tafel analysis, applied to the intermediate region of square wave voltammetric curves, devoted to the identification of corrosion products on archaeological metal, is described. This is based on the voltammetry of microparticles methodology using conventional abrasive conditioning of the electrode, as well as ‘one‐touch’ and layer‐by‐layer techniques. The proposed methodology is applied to the identification of copper and silver corrosion products in mediaeval silver‐copper coins from the Libertad street hoard in Valencia (Spain).     

A combined redox-competition and negative-feedback SECM study of self-healing anticorrosive coatings

In this paper, the long-term anticorrosive efficiency of a damaged self-healing coating is studied for the first time using scanning electrochemical microscopy (SECM). In the study an epoxy-coating with embedded-capsules containing a silyl-ester is employed. The properties of the silyl-ester as a healing-agent for the protection of AA2024-T3 were evaluated by complementary SECM experiments operating in negative-feedback and redox-competition modes. The experimental approach here presented allowed for monitoring the early-stages of corrosion activity and subsequent healing mechanisms offered by the release of silyl-ester into a relatively large coating defect. This result was observed by detecting the transition of the oxygen reduction response from a redox-competition mode to a negative-feedback behavior. These measurements demonstrated that the silyl-ester is released efficiently after capsules break upon coating damage, covering relatively large areas and gradually healing the damaged-site hindering the corrosion processes and providing an effective protection for at least one month of immersion in chloride solution.     

Corrosion inhibition of iron in hydrochloric acid using pyrazole

The corrosion and corrosion inhibition of iron in HCl solutions in the absence and presence of pyrazole (PA) were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Changes in impedance parameters (R_ct and C_dl) were indicative of the adsorption of PA on the iron surface. The adsorption of PA is found to obey Langmuir adsorption isotherm. The study suggests that this compound is an anodic inhibitor.     

镍腐蚀的影响因素与改善方法探讨

镍腐蚀是指发生在化学镍金的化镍、沉金过程中发生的金对镍的攻击过度造成局部位置或整体位置镍腐蚀的现象,严重者则导致＂黑盘＂的出现,严重影响PCB的可靠性。报告通过评估分析镍腐蚀影响的因素,提出相应的改善方法,改善流程的稳定性。     

PCB焊点焊接缺陷原因分析

PCB焊点焊接缺陷产生的原因可能很多,如果你从扩散焊接的特点考虑就会变得明了起来！熔化的焊料原子沿着被焊接金属的结晶晶界的扩散,扩散所需要的激活能也可称为“表面自由能”比体扩散小。一般锡料的活性能约为380达因/厘米,鲜活的铜面在助焊剂的辅助下约为1265达因/厘米,所以焊接可以良好进行。