Friction stir scribe welding technique for dissimilar joining of aluminium and galvanised steel

Friction stir scribe technology, a derivative of friction stir welding, was applied for the dissimilar lap welding of an aluminium alloy and galvanised mild steel sheets. During the process, the rotating tool with a cobalt steel scribe first penetrated the top material – aluminium – and then the scribe cuts the bottom material – steel. The steel was displaced into the upper material to produce a characteristic hook feature. Lap welds were shear tested, and their fracture paths were studied. Welding parameters affected the welding features, including hook height, which turned out to be highly related to fracture position. Therefore, in this paper, the relationships among welding parameters, hook height, joint strength and fracture position are presented. In addition, the influence of zinc coating on joint strength was also studied.     

Diamondoid Phosphines – Selective Phosphorylation of Nanodiamonds[1]

The diamondoids (nanodiamonds) diamantane and triamantane were selectively converted into diorganophosphinic acid chlorides by reacting them with phosphorus trichloride under Friedel–Crafts‐like conditions. The di‐diamondoid phosphinic acid chlorides were subsequently reduced with trichlorosilane to give the hitherto unknown corresponding di‐diamondoid phosphines. These diamondoid phosphinic acid chlorides and phosphines are of great utility as starting materials in organo‐element and coordination chemistry due to their extraordinary rigidity and steric bulk.     

Analysis of solidification cracking susceptibility in side-by-side dual-beam laser welding of aluminum alloys

In this paper, an experimental study combined with a numerical model consideration of both thermal conduction and fluid flow in the molten pool were carried out, aiming to analyze solidification cracking susceptibility of dual-beam laser welding on Al alloys. The maximum accumulated transverse displacement in the mushy zone was calculated based on the strip expansion technique and employed to evaluate centerline solidification cracking susceptibility. Numerical calculations showed that increasing inter-beam spacing in side-by-side dual-beam laser welding of Al alloys could lead to increased accumulated transverse displacement in the weld, resulting in higher solidification cracking susceptibility, which agreed well with experimental observations. The analysis results also showed that increasing the laser power or reducing the welding velocity increased hot cracking susceptibility. The optimum cracking-free welding condition for dual-beam laser welding of Al can be determined with the help of numerical modeling, in which the hot cracking susceptibility can be evaluated and numerically reduced by adjusting welding process variables.     

Effects of Tomato and Soy Germ on Lipid Bioaccumulation and Atherosclerosis in ApoE−/− Mice

Dietary patterns with cardiovascular benefits have been recommended, but the relative contributions of individual foods and food components, alone or in combination, remain undefined. Male ApoE^?/? mice were fed either a purified AIN‐93G control diet, a Western diet (WD), or a WD with 10% tomato powder (TP), 2% soy germ (SG), or the combination, for 4 wk (n = 10 per group). Plasma total cholesterol and triglycerides were measured with enzymatic colorimetric kits, and serum amyloid A (SAA) was measured by ELISA. Liver lipids were extracted with chloroform:methanol, and triglycerides, free and esterified cholesterol measured with enzymatic colorimetric kits. Expression of Cyp27a1, Cyp7a1, Abcg5, and Abcg8 in the liver was determined by quantitative polymerase chain reaction. Sections of the aortic root and aorta were cut and stained with hematoxylin and eosin (H&E) to assess extent of atherosclerotic lesions. WD‐fed animals had greater liver and adipose weights, plasma cholesterol and SAA, hepatic lipids, and atherosclerosis than AIN‐93G animals. TP and SG did not decrease atherosclerosis as measured by H&E‐stained sections of the aortic root, aortic arch, and descending aorta. The TP diets further increased plasma cholesterol, but also led to increased expression of the Abcg5/8 transporters involved in cholesterol efflux. Addition of SG alone to the WD attenuated WD‐induced increases in plasma cholesterol, liver lipids, and gonadal adipose weight. The results of this study do not support the use of either TP or SG for reduction of atherosclerosis, but suggest some beneficial effects of SG on lipid metabolism in this model of cardiovascular disease.     

The effects of pre-slaughter pig management from the farm to the processing plant on pork quality

Two experiments (Exp.1, n = 80; Exp.2, n = 144) were conducted to determine the effects of pre-slaughter pig management on pork quality by monitoring blood lactate concentration ([LAC]) during marketing. [LAC] was measured at: (1) baseline at farm, (2) post-loading on truck, (3) pre-unloading after transport, (4) post-unloading at plant, (5) post-lairage, (6) post-movement to stun, and (7) exsanguination. Pearson correlations were used to determine relationships between [LAC] and meat quality. Higher [LAC] post-loading or a greater change in [LAC] during loading resulted in increased 24 h pH (P = 0.002, P = 0.0006, Exp.1; P = 0.0001, P = 0.01, Exp.2, respectively), decreased L* (P = 0.03, P = 0.04; P = 0.001, P = 0.01) and decreased drip loss (P = 0.02, P = 0.12; P = 0.002, P = 0.01). Even though improved handling during loading is important to animal well-being, it will not necessarily translate into improved pork quality.     

Two-pass laser welding of galvanized high-strength dual-phase steel for a zero-gap lap joint configuration

A welding procedure based on using two-pass laser scans is introduced for joining overlapped galvanized high-strength steel sheets. The first pass is based on a defocused laser spot that scans across the top of the overlapped sheets and heats the zinc coating at the faying surface to be melted and vaporized, while the second pass is executed with a focused laser spot in order to perform the welding. Completely defect-free welds were obtained by using this two-pass laser welding procedure. An on-line machine vision system and a spectrometer were applied to analyze the stability of the laser welding process. An energy-dispersive X-ray spectroscopy (EDS) was carried out to determine the atomic percent of zinc and iron of the DP980 coupons. Mechanical testing was conducted to evaluate the mechanical properties of the welds. The experimental results show that the weld joints obtained by the two-pass laser welding approach have a higher failure value than those obtained by a single pass laser welding of galvanized steel with mechanically removed zinc at the faying surface under the same welding speed and laser power.     

Effect of hook characteristics on the fracture behaviour of dissimilar friction stir welded aluminium alloy and mild steel sheets

ABSTRACT

Under tensile shear loading, fracture modes of dissimilar lap welds produced by friction stir scribe technology were studied. Three fracture modes were observed. For zone A fracture, the initial crack was restrained, and the joint ultimately fractured in the base mild steel. For zone B fracture, the initial crack progressed through the aluminium sheet just above the Al/steel interface. For zone C fracture, the initial crack proceeded along the steel hook to the aluminium sheet surface. Fracture mode and joint strength were greatly influenced by steel hook size, and the steel hook size was affected by welding parameters and tool scribe height. In this study, the experimental joint strength achieved the calculated joint load limit.     

Expression mosaic of odorant-binding proteins in Drosophila olfactory organs.

Deciphering the genome of the fruitfly, Drosophila melanogaster, has revealed 39 genes coding for putative odorant-binding proteins (OBPs), more than are known at present for any other insect species. Using specific antibodies, the expression mosaic of five such OBPs (OS-E, OS-F, LUSH, PBPRP2, PBPRP5) on the antenna and maxillary palp has been mapped in the electron microscope. It was found that (1) OBP expression does correlate with morphological sensillum types and subtypes, (2) several OBPs may be co-localized in the same sensillum, and (3) OBP localization is not restricted to olfactory sensilla. The expression of PBPRP2 in antennal epidermis sheds some light on the possible evolution of OBPs.     

Editorial: A new beginning for the journal.

Announces that the International Journal of Stress Management has a new publisher--The Educational Publishing Foundation of the American Psychological Association. The editor discusses what this means for the readership and focus of the journal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)