Two-dimensional numerical model for the analysis of macrosegregation during solidification

This paper presents a 2D extension of a one-dimensional model proposed initially for the analysis of macrosegregation of multicomponent alloys. Some simulations were carried out to compare the performance of an explicit/implicit time integration scheme for coupling thermal-solutal fields with a fully implicit one. Simulations carried out for the analysis of a two-dimensional solidification problem has fitted the unidirectional and two-dimensional experimental data very well.     

Apple Allergy: The cDNA Sequence of the Major Allergen of Apple,Determined by Performing PCR with a Primer Based on the N-Terminal Amino Acid Sequence,is Highly Homologous to the Sequence of the Major Birch Pollen Allergen

Considering the known N-terminal amino acid sequence of the major apple allergen, a polymerase chain reaction (PCR) primer was selected to amplify cDNA encoding this protein. A single PCR product was obtained, cloned into Escherichia coli and subsequently sequenced. The missing 5′-end of the apple cDNA sequence was obtained by a 5′-RACE method. The cDNA sequence showed 72% identity with the coding region of one of the known isoforms of Bet v 1, the major allergen of birch pollen. The deduced amino acid sequence resulted in a 158-residue protein with a calculated molecular mass of 17·5 kDa and 63% amino acid sequence identity to Bet v 1. In addition, further protein alignments showed a high degree of identity with allergens from other tree pollens and some ‘pathogenesis-related proteins’ from food plants. According to international regulations the allergen was termed Mal d 1 for this protein, it being the first major allergen discovered and characterised in fruits of apple (Malus domestica).     

Opposite modulation of opiate withdrawal behaviors on microinfusion of a protein kinase A inhibitor versus activator into the locus coeruleus or periaqueductal gray

Chronic opiate administration upregulates the cAMP pathway in the locus coeruleus (LC). This adaptation is thought to increase the electrical excitability of LC neurons and contribute to the dramatic increase in LC firing induced by opioid receptor antagonists in opiate-dependent animals. The goal of the present study was to evaluate directly a role of the cAMP pathway in opiate withdrawal behaviors by studying, in vivo, whether withdrawal is influenced by intra-LC infusion of compounds known to activate or inhibit protein kinase A (PKA). Infusions into amygdala or periaqueductal gray (PAG) were studied for comparison. In one series of experiments the effect of intra-LC, intra-amygdala, or intra-PAG infusions of the PKA inhibitor Rp-cAMPS on naloxone-precipitated withdrawal from morphine was examined. Intra-LC infusions of Rp-cAMPS significantly attenuated several prominent behavioral signs of morphine withdrawal. Intra-PAG infusions of Rp-cAMPS also significantly attenuated opiate withdrawal behaviors, although different behaviors were affected. In contrast, intra-amygdala infusions of Rp-cAMPS were without significant effect. In a second series of experiments the effect of intra-LC or intra-PAG infusions of the PKA activator Sp-cAMPS on behavior in nondependent drug-naive animals was determined. Sp-cAMPS infusions into either brain region induced a quasi-withdrawal syndrome, but the observed behaviors differed between the two groups. Analysis of the phosphorylation state of tyrosine hydroxylase, a well characterized substrate for PKA, confirmed the ability of Rp-cAMPS and Sp-cAMPS to inhibit and activate, respectively, PKA activity in vivo. Together, these data provide direct evidence for involvement of the cAMP-PKA system in the LC, as well as in the PAG, in opiate withdrawal and withdrawal-related behaviors.     

Insulin stimulates testosterone biosynthesis by human thecal cells from women with polycystic ovary syndrome by activating its own receptor and using inositolglycan mediators as the signal transduction system

To determine whether insulin stimulates human ovarian testosterone production in the polycystic ovary syndrome by activating its own receptor and using inositolglycan mediators as the signal transduction system, thecal cells from polycystic ovary syndrome women were isolated and cultured. Insulin and insulin-like growth factor I stimulated thecal testosterone biosynthesis. Antibody blockade of the insulin receptor abolished insulin's stimulatory action, whereas effective antibody blockade of the insulin-like growth factor I receptor did not alter insulin's stimulation of thecal testosterone biosynthesis. A chiro-inositol containing glycan (INS-2) increased thecal testosterone biosynthesis. Preincubation of cells with an antiinositolglycan antibody (A23939 or alpha IGP) abolished insulin's stimulatory effect, but not that of hCG. These findings suggest that inositolglycans serve as the signal transduction system for insulin's stimulation of human thecal testosterone biosynthesis.     

Observation of rhombic facets on platinum wire after heating in air using scanning tunnelling microscopy

Evidence is provided for the formation of surface faceting due to heating in air at 1160 K. For the first time diamond-shaped facets with angles of 60 and 120° have been observed on the surface of a sample of ultrapure platinum wire in air using scanning tunnelling microscopy. The maximum extension of the facets is about 1000 Å.     

Transmission electron microscopic investigations on SiC- and BN-coated carbon fibres

Carbon fibres were coated with layers of silicon carbide (SiC) and boron nitride (BN) by conventional chemical vapour deposition. The SiC films were deposited by thermal decomposition of methyltrichlorosilane, whereas the BN films were deposited using the stepwise disproportion reaction of boron chloride with ammonia. Samples for electron microscopic investigations were prepared by separating film from fibre or by conventional mechanical thinning and subsequent ion milling of cross sections of coated fibres. Bright- and dark-field images of both planar and cross-sectional electron microscopic investigations on the fibre coatings gave detailed information on film thickness and morphology. High-resolution images improved the structural information of electron diffraction patterns. Crystal dimensions in the SiC film vary between 10 and 40 nm. Electron diffraction revealed the crystal structure to be a mixture of disordered hexagonal 2H-SiC and cubic -SiC. High-resolution images showed the (1 1 1)-planes to be preferred for deposition. In BN films, a hexagonal turbostratic structure similar to turbostratic carbon was observed. Apart from amorphous regions, nanocrystalline parts were detected, which have a higher structural perfection in the stacking sequence of their (0 0 2)-planes compared to the (0 0 2)-planes of the turbostratic carbon fibre. High-resolution images located the film-fibre interface that was confirmed by electron energy loss spectroscopy.     

Microfluidic chips for cells capture using 3-D hydrodynamic structure array

Microfluidic chips were designed and fabricated to capture cells in a relative small volume to generate the desired concentration needed for analysis. The microfluidic chips comprise three-dimensional (3-D) cell capture structures array fabricated in PDMS. The capture structure includes two layers. The first layer consists of spacers to create small gap between the upper layer and glass. The second layer is a sharp corner U-shaped compartment with sharp corners at the fore-end. And another type capture structure with Y-shaped fluidic guide has been designed. It was demonstrated that the structures can capture cells in theory, using Darcy–Weisbach equation and COMSOL Multiphysics. Then yeast cell was chosen to test the performance of the chips. The chip without fluid guides captured ~1.44 × 10⁵ cells and the capture efficiency was up to 71 %. And the chip with fluid guides captured ~5.0 × 10⁴ cells and the capture efficiency was ~25 %. The chip without fluid guides can capture more cells because the yeast cells in the chip without fluid guides are subject to larger hydrodynamic drag force.