Kinetics of AuSn4 migration in lead-free solders

The relatively fast diffusion of Au atoms in eutectic PbSn matrix is considered one of the contributing factors to the Au embrittlement problem. In this study, we further investigated the Au embrittlement problem in high-Sn solders. Experimentally, Sn3.5Ag (wt.%) spheres with 500-μm diameter were soldered over the Au/Ni soldering pads. It was found that some of the AuSn₄ needles that formed after reflow inside the solder migrated back to the solder/pad interface during thermal aging. However, the migration kinetics in high-Sn solders was slower compared to that in eutectic PbSn. The difference in migration kinetics of AuSn₄ in eutectic PbSn and SnAg was ascribed to the difference in the magnitudes of the Au flux and the Ni flux. In eutectic PbSn, the Au flux was much greater than that of the Ni flux, and the Au and Ni flux were in the same order of magnitude in eutectic SnAg. The relative magnitude of the Au and Ni flux changed in eutectic PbSn and SnAg because the homologous temperatures of PbSn and SnAg were different.     

Superconductivity at differentTc in CdBa2Ca2Cu3Oy

A Cd analogue of the Tl and Hgn =3 series with nominal composition CdBa₂Ca₂Cu₃O_y has been synthesized. The samples were superconducting according to magnetic susceptibility measurements. The critical temperature was 103 or 107 K depending on the preparation conditions. The EDX analysis revealed the presence of Cd-1111, Cd-1121, and Cd-2333 as minor phases. The observed diamagnetic effects were attributed to the differentT _c of these phases.     

锆(Ⅳ)-3,5-diBr-PADAP-安替比林三元配合物的分光光度研究与应用

本文提出在安替比林存在下,以3,5-diBr-PADAP为显色剂,分光光度测定微量锆的新方法。在pH1～2的HCl介质中,锆(W)与试剂和安替比林形成配合比为1:1:1的红色三元配合物,最大吸收值在615nm波长处,摩尔吸光系数ε=1.35×10~5。锆(Ⅳ)量在0～25μg/25ml范围内,遵守比尔定律。方法简单、快速、准确。若采用钽试剂—苯萃取法分离共存离子,可适用于钽铌矿和合金中痕量锆的测定。     

悬浮床加氢裂化油溶性催化剂与沥青质的作用

在高压釜反应器中对添加了油溶性 Ni 催化剂(UPC-O)和水溶性 Ni 催化剂(UPC-W)的辽河稠油常压渣油(LHAR)进行了悬浮床加氢裂化实验。通过元素分析和傅里叶变换红外光谱(FTIR)分析对抑制反应生焦效果好的 UPC-O 与 LHAR 沥青质的作用进行了研究。元素分析结果显示,在 LHAR 中加入 UPC-O1000μg/g,沥青质和脱沥青质油中 Ni 含量分别出476μg/g和110μg/g 增加到7 559μg/g 和1 024μg/g,表明 UPC-O 在沥青质中有富集的趋势。FTIR 表征结果显示,UPC-O 和沥青质发生了相互作用。UPC-O 可在沥青质原位硫化为活性组分,对沥青质在悬浮床加氢裂化反应中的缩合起到好的抑制作用。     

Phase composition and properties of solid solutions of GdFeO3–GdInO3 bulks

Solid solutions of the GdFeO₃–GdInO₃ system were prepared at 1550 °C by ceramic powder processing. The formulated composition was Gd(Fe_1−xIn_x)O₃ (GFI) with the indium contents at x = 0, 0.25, 0.5, 0.75, and 1.0. A stable phase of Gd(Fe_1/3In_2/3)O₃ in our system was identified by X-ray diffraction and phase composition analysis. Multi-phase morphologies were observed for GFI bulks with x = 0.5 and 0.75. Dielectric and electrical properties of the GFI bulks were investigated. The addition of 25% In³⁺ in GdFeO₃ had an obvious enhancement in polarization and led to an elevated resonance frequency. Dielectric properties of GFI bulks except GdInO₃ were strongly dependent upon the test frequency, which corresponded to the response of polarization mechanism. GdInO₃ displayed as a stable dielectric, which was frequency- and temperature-insensitive. GdInO₃ was thermally activated and became leaky until above 600 °C.     

Photocatalytic degradation of 2,2‐bis(4‐hydroxy‐3‐methylphenyl) propane (BPP) based on molecular recognition interaction

BACKGROUND: Endocrine disruptors in the aquatic environment and their potential adverse effects are currently issues of concern. One of these endocrine disruptors is 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane (BPP). In this work the molecular recognition interaction of BPP with β‐cyclodextrin (β‐CD) was studied using IR spectroscopy and steady state fluorescence spectroscopy, and the photocatalytic degradation behaviour of BPP based on molecular recognition interaction was investigated in a TiO₂/UV–visible (λ_max = 365 nm) system. This might provide a new method for the treatment of some organic pollutants in wastewater. RESULTS: β‐CD reacts with BPP to form a 1:1 inclusion complex, the formation constant of which is 4.94 × 10³ L mol^?1. The photodegradation rate constant of BPP after molecular recognition by β‐CD showed a 1.42‐fold increase in the TiO₂/UV–visible (λ_max = 365 nm) system. The photodegradation of BPP depended on the concentration of β‐CD, the pH value, the gaseous medium and the initial concentration of BPP. The photodegradation efficiency of BPP with molecular recognition was higher than that without molecular recognition. After 100 min of irradiation the mineralisation efficiency of BPP after molecular recognition by β‐CD reached 94.8%, whereas the mineralisation efficiency of BPP before molecular recognition by β‐CD was only 40.6%. CONCLUSION: The photocatalytic degradation of BPP after molecular recognition by β‐CD can be enhanced in the TiO₂/UV‐visible (λ_max = 365 nm) system. This enhancement is dependent on the enhancement of the adsorption of BPP, the moderate inclusion depth of BPP in the β‐CD cavity and the increase in the frontier electron density of BPP after molecular recognition. Copyright © 2008 Society of Chemical Industry     

One‐step production of 2,3‐butanediol from starch by secretory over‐expression of amylase in Klebsiella pneumoniae

BACKGROUND: 2,3‐Butanediol (2,3‐BD) is a valuable chemical that can be biosynthesized from many kinds of substrates. For commercial biological production of 2,3‐BD, it is desirable to use cheap substrate without pretreatment, such as starch. However, there have been few reports on the production of 2,3‐BD directly from starch. RESULTS: In this work, gene malS coding for α‐amylase (EC 3.2.1.1) precursor was inserted into plasmid pUC18K, and secretory over‐expression of α‐amylase was achieved by engineered Klebsiella pneumoniae. The extracellular recombinant amylase accelerated the hydrolyzation of starch, and one‐step production of 2,3‐BD from starch was carried out by engineered K. pneumoniae. A 2,3‐BD concentration of 3.8 g L^?1 and yield of 0.19 g 2,3‐BD g^?1 starch were obtained after 24 h fermentation. CONCLUSION: The one‐step production of 2,3‐BD from starch was achieved by secretory over‐expression of amylase in K. pneumoniae. This would simplify the process and reduce the production cost considerably by enabling use of starch with minimal pretreatment. Copyright © 2008 Society of Chemical Industry     

Material removal and surface damage in EDM of Ti3SiC2 ceramic

Material removal and surface damage of Ti₃SiC₂ ceramic during electrical discharge machining (EDM) were investigated. Melting and decomposition were found to be the main material removal mechanisms during the machining process. Material removal rate was enhanced acceleratively with increasing discharge current, i_e, working voltage, u_i, but increased deceleratively with pulse duration, t_e. Microcracks in the surface and loose grains in the subsurface resulted from thermal shock were confirmed, and the surface damage in Ti₃SiC₂ ceramic led to a degradation of both strength and reliability.     

3ds Max和Photoshop在水利工程中的结合应用

通过在水利行业中对3dsMax和Photoshop使用,总结出5个针对水利工程中3dsMax和Photoshop结合使用的一些方法,为水利工程申报和水利建设汇报提供一些参考方法.     

Comparative study of the elimination of toluene vapours in twin biotrickling filters using two microorganisms Bacillus cereus S1 and S2

BACKGROUND: To investigate the microbial degradation performance of organic pollutants in the atmosphere using a biotrickling filter, two microorganism strains, Bacillus cereus S1 and Bacillus cereus S2, were selected, identified and inoculated into a twin biotrickling filter for comparison. RESULTS: Both strains showed good performance towards the degradation of model organic pollutants when gas flow rates ranged from 100 to 600 L h⁻¹. For S1, the total maximum removal efficiency (RE) of toluene was maintained nearly 100% not only at gas flow rates of 100 L h⁻¹ corresponding to empty bed residence time (EBRT) 199.44 s, but also at gas flow rates of 200 L h⁻¹ (EBRT = 99.72 s) and 300 L h⁻¹ (EBRT = 66.48 s). However, S2 had a much lower degradation capability; near 100% removal efficiency was obtained only at the gas flow rate of 100 L h⁻¹ although both bacteria belong to the same Bacillus cereus. With further increase in gas flow rate, the total REs for both S1 and S2 decreased slightly at first and then dropped sharply to 46% and 35%, respectively, at an EBRT of 33.24 s, corresponding to a gas flow rate of 600 L h⁻¹. Starvation for between 2 and 10 days resulted in the re‐acclimation times of both strains ranging between 1.0 and 15.5 h. CONCLUSION: Strain S1 would be a better choice for inoculation into a biotrickling filter than strain S2, because of its much higher toluene removal capacity and rapid recovery to full performance. Copyright © 2008 Society of Chemical Industry