Oxidation of liquid solders for die attachment

This study deals with thermal oxidation behaviour in the liquid state of a commonly-used die-attach solder, Pb–Sn, and its potential Pb-free alternatives (Bi–Ag and Zn–Sn) from viewpoints of thermodynamics and kinetics. The characteristics of the oxidation reaction layers were investigated using XPS, XRD and AES. The superior performance in oxidation prevention of the Zn based alloys can be ascribed to their stable oxidative product, ZnO, which exhibits low free energy of formation, as well as slow growth rate.     

Social functioning and adjustment in Canadian-born children with Chinese and European backgrounds.

The purpose of the study was to examine social functioning and adjustment in peer context in Chinese Canadian and European Canadian children. A sample of elementary school children participated in the study. Data on social functioning, peer acceptance and rejection, and victimization were collected from peer assessments and sociometric nominations. The results indicated that Chinese Canadian children were viewed by peers as less aggressive-disruptive than European Canadian children. Chinese Canadian girls, but not boys, were more shy-sensitive than their European Canadian counterparts. Sociability was associated with peer acceptance, whereas aggression was associated with peer rejection and victimization. Shyness was associated with peer relationship difficulties more evidently in European Canadian children than in Chinese Canadian children. These results indicate the relevance of ethnic background to children's peer social experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postoperative analgesia with intramuscular morphine at fixed rate versus epidural morphine or sufentanil and bupivacaine in patients undergoing major abdominal surgery

Hydrofluoroalkane-134a (HFA) beclomethasone dipropionate (BDP) was formulated in a metered-dose inhaler (MDI) to deliver a particle size of 1.1 microm compared with 35 microns for currently marketed chlorofluorocarbon (CFC)-BDP products. Two phase I single-dose human deposition studies were conducted using technetium 99m-radiolabelled BDP in a press-and-breathe actuator without an add-on spacer. A healthy volunteer study (n=6) showed that 55-60% of the HFA-BDP ex-actuator dose was deposited in the lungs, with 29-30% deposited in the oropharynx. CFC-BDP deposition was 4-7% in the lungs and 90-94% in the oropharynx. The pattern of deposition within the lung showed that HFA-BDP was spread diffusely throughout the lung airways, whereas CFC-BDP was confined to the central airways with little, if any, peripheral airway deposition. A second study with asthmatics (n=16) confirmed that 56% of the HFA-BDP dose was deposited in the airways, with 33% in the oropharynx. In conclusion, hydrofluoroalkane-134a-beclomethasone dipropionate deposition was much greater in the airways than chlorofluorocarbon-beclomethasone dipropionate, with a concomitant reduction in oropharyngeal deposition. The increased lung deposition efficiency of the hydrofluoroalkane propellant has led to a reduction in the amount of beclomethasone dipropionate needed to achieve a similar efficacy. The penetration of the hydrofluoroalkane to the small airways may provide asthma treatment not afforded by conventional chlorofluorocarbons.     

Screening the fabrication conditions of ultrafiltration membranes by using the uniform design and regression analysis methods

In this work, the concerned casting conditions for the fabrication of the ultrafiltration (UF) membrane from polysulfone were the gelation medium used, the temperature of the gelation bath, the gelation period, and the evaporation time of the cast sheet. The uniform design method was applied to substantially reduce the number of experiments for studying the influence of each of four casting conditions introduced in the preparation of UF-membranes. The pure water flux and the molecular weight cutoff (MWCO) of each of the four macromolecule-standards, namely egg white lysozyme, egg white albumin, bovine serum albumin and bovine γ-globulius, of each prepared UF-membrane were determined. These experimental responses were then analyzed by using a non-linear model with the backward regression method. The results of this work showed that the uniform design-non linear model (UD-NLM) method can substantially reduce the number of experimental runs for predicting the influences of the studied casting conditions on the ultrafiltration performance of the prepared asymmetric polysulfone membranes.     

Synthesis and hydrogen adsorption properties of a new phthalocyanine-based metal–organic framework

The first member of a new class of phthalocyanine-based metal–organic frameworks, MOF-IP, has been synthesized in order to gauge the potential of this type of materials for hydrogen storage. Preliminary studies indicate that MOF-IP is a robust material with a hydrogen uptake capacity of 1.15 wt% at 77 K under atmospheric pressure.     

Electrochemical corrosion behaviour of Bi-11Ag alloy for electronic packaging applications

This study investigated the electrochemical corrosion properties of the solders for die-attach applications in 3.5% NaCl solution. Compared with Pb-5Sn and Zn-40Sn, Bi-11Ag exhibited higher corrosion potential and relatively low corrosion current density. The ductile Ag-rich phase which dispersed in the Bi matrix was able to accommodate the stress arising from the formation of a passive layer and contributed to the two-stage passivation. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results confirm that the corrosion products comprised BiOCl, Bi₂O₃ and AgCl.     

Hereditary increase of plasma histidine-rich glycoprotein associated with abnormal heparin binding (HRG Eindhoven)

Plasma histidine-rich glycoprotein (HRG) was found to be persistently increased in a patient with a history of recurrent arterial thromboembolic events. The mean concentration was 270% of normal pooled plasma. Increased HRG was found in eight of the 17 relatives studied, but none of them has experienced thrombo-embolism yet. Apparently, increased HRG was hereditary with autosomal dominant inheritance. A significant correlation was found between the increased plasma concentration of the protein and the age of the subjects (P < 0.02), whereas no such relation is present in a normal population. The plasma HRG of the proposita and 9 of her family members displayed abnormal binding to heparin, as assessed in a crossed affinity immuno-electrophoresis system: the usual increase in mobility after binding to heparin was absent. The binding of this variant HRG to plasminogen was normal. This case represents the first abnormal HRG variant reported and it is proposed to designate it: HRG Eindhoven.     

Fast Kinetic Monte Carlo Simulation of Strained Heteroepitaxy in Three Dimensions

Accelerated algorithms for simulating the morphological evolution of strained heteroepitaxy based on a ball and spring lattice model in three dimensions are explained. We derive exact Green’s function formalisms for boundary values in the associated lattice elasticity problems. The computational efficiency is further enhanced by using a superparticle surface coarsening approximation. Atomic hoppings simulating surface diffusion are sampled using a multi-step acceptance-rejection algorithm. It utilizes quick estimates of the atomic elastic energies from extensively tabulated values modulated by the local strain. A parameter controls the compromise between accuracy and efficiency of the acceptance-rejection algorithm.