The exergy fields in transport processes: Their calculation and use

This paper is a brief review of the method for analyzing the space and time dependent exergy and irreversibility fields in processes. It presents the basic equations, the method for their use, major literature sources, and three examples from the authors' work: flow desiccation, combustion of oil droplets, and combustion of pulverized coal. Conclusions from this Second Law analysis are used to attempt process improvement suggestions.     

Study of the metal dusting behaviour of high‐temperature alloys

The corrosion phenomenon named metal dusting has been observed in many high‐temperature industrial plants. An experimental research programme is being carried out into the degradation resistance of wrought and cast commercial and development high‐temperature alloys in H₂/CO gas mixtures at temperatures of 550°C to 750°C. Emphasis is placed on very high carbon activities, consistent with the next generation of steam‐reforming and similar plants that are susceptible to metal dusting. The overall programme is concerned with the mechanisms of initiation and propagation of dusting and the sensitivity to damage of the more resistant alloys, as a function of environmental parameters. Initial tests have been carried out on a number of commercial alloys: Alloy 600, 693, 602CA, 601, 603 XL, 671, 617, 690 (wrought), and H46M (cast). The specimens were exposed to a gas mixture of high carbon activity at 650°C for a total of 1000 hours. Many of the alloys showed at least the initial stages of metal dusting. Preliminary analysis using electron microscopy revealed that initiation of metal dusting is influenced by microstructure, stress state and composition. In some cases, attack was enhanced at stress points, such as corners and edges. Sample holders were found to influence strongly the length of the initiation period for the onset of the corrosion phenomenon. The reaction layers in the alloy beneath areas of damage were analysed by EDX and EPMA. Mechanical characterisation of such areas has been carried out using nanoindentation methods. These early results are discussed in terms of the effectiveness of oxide scales in inhibiting the onset of damage and presence of impurities in the ceramic holder in initiating the onset of damage.     

Expression of N-acetyl-D-galactosamine associated epitope in synovium: a potential marker of glycoprotein production

OBJECTIVE: To investigate synovial glycoprotein production in situ, a novel monoclonal antibody (Mab), A13D8, was used to evaluate the expression of an epitope containing N-acetyl-D-galactosamine (GalNAc) in normal and pathological synovium. METHODS: Immunohistological and cytochemical analysis of synovial tissue samples was undertaken with single and double staining techniques using the A13D8 Mab, anti-CD68, vascular cell adhesion molecule-1 (VCAM-1), the hyaluronan associated enzyme uridine diphosphoglucose dehydrogenase (UDPGD), and the anti-Golgi Mab SSN/HR-1992. The specificity of the A13D8 Mab was established through blocking studies using carbohydrate residues, including GalNAc and N-acetylglucosamine (GlcNAc). RESULTS: A13D8 is expressed intensely in the cytoplasm of normal type B lining cells, which coexpress VCAM-1 and UDPGD, and is not expressed by CD68+ type A lining cells. In the lining layer of RA synovium, there is a negative correlation between A13D8 expression and the level of lymphocytic infiltration in the sublining areas (r = -0.43, p < 0.001). The endothelium of a subset of venules, typically in lymphocyte-rich aggregates, also stains intensely for A13D8. Pretreatment of the Mab with GalNAc completely eliminates the tissue staining, as well as the 110 kDa band seen on immunoblot, whereas pretreatment of A13D8 with GlcNAc and lactose has no effect. Double staining of HEp-2 cells with A13D8 and the anti-Golgi Mab SSN/HR-1992 reveals co-localization of the A13D8 epitope to the Golgi apparatus. CONCLUSION: Type B synovial lining cells and selected synovial endothelium express GalNAc containing epitope identified by Mab A13D8. Marked reduction in the expression of this epitope in the lining layer of inflamed RA synovium suggests that the synovial production of GalNAc containing glycoproteins, such as mucins, may be altered in this disorder.     

A new technique for determining long-term TDDB accelerationparameters of thin gate oxides

A new technique, the dual voltage versus time curve (V-t) integration technique, is presented as a much faster method to obtain time-dependent dielectric breakdown (TDDB) acceleration parameters (α and τ) of ultrathin gate oxides compared to conventional long-term constant voltage stress tests. The technique uses V-t curves measured during highly accelerated constant or ramped current injection breakdown tests. It is demonstrated that the technique yields acceleration parameters that are statistically identical to values obtained from long-term constant voltage TDDB tests. In contrast to traditional TDDB tests, the proposed technique requires over an order of magnitude less testing time, a smaller sample size, and can be used during production monitoring     

Vav regulates peptide-specific apoptosis in thymocytes

Homologies between vertebrate forebrain subdivisions are still uncertain. In particular the identification of homologs of the mammalian neocortex or the dorsal ventricular ridge (DVR) of birds and reptiles is still a matter of dispute. To get insight about the organization of the primordia of the main telencephalic subdivisions along the anteroposterior axis of the neural tube, a fate map of the dorsal prosencephalon was obtained in avian chimeras at the 8- to 9-somite stage. At this stage, the primordia of the pallium, DVR and striatum were located on the dorsal aspect of the prosencephalon and ordered caudorostrally along the longitudinal axis of the brain. Expression of homeobox-containing genes of the Emx, Dlx and Pax families were used as markers of anteroposterior developmental subdivisions of the forebrain in mouse, chick, turtle and frog. Their expression domains delineated three main telencephalic subdivisions in all species at the onset of neurogenesis: the pallial, intermediate and striatal neuroepithelial domains. The fate of the intermediate subdivisions diverged, however, between species at later stages of development. Homologies between forebrain subdivisions are proposed based on the conservation and divergence of these gene expression patterns.     

Passive smoking, active smoking, and education: their relationship to weight history in women in Geneva

OBJECTIVES: This study was undertaken to determine the relationship of education and tobacco smoke to lifetime weight history in women. METHODS: Information on passive smoking, active smoking, and weight history was collected from 928 women aged 29 to 74 years selected from the general population of Geneva, Switzerland. Multivariate analysis of variance was performed for weight, weight at age 20, and weight changes since age 20. RESULTS: Education was inversely related to weight at age 20, current weight, and weight gain since age 20. The least educated group had a current weight of 4 kg more than the most educated group. Differences across smoking categories were small: passive smokers had the highest current weight (63.4 kg) and former active smokers had the lowest (60.4 kg). Weight gain since age 20 tended to be smaller in former and current active smokers (5.5 to 7.2 kg) than in passive smokers (8.3 to 10.4 kg) and those never exposed (9.1 kg). CONCLUSIONS: In this sample, education was an important predictor of women's current weight and weight history. Passive and active smoking had little long-term effect on weight.     

InAs/AlSb/GaSb resonant interband tunneling diodes andAu-on-InAs/AlSb-superlattice Schottky diodes for logic circuits

Integrated resonant interband tunneling (RIT) and Schottky diode structures, based on the InAs/GaSb/AlSb heterostructure system, are demonstrated for the first time. The RIT diodes are advantageous for logic circuits due to the relatively low bias voltages (~100 mV) required to attain peak current densities in the mid-10⁴ A/cm ² range. The use of n-type InAs/AlSb superlattices for the semiconducting side of Schottky barrier devices provides a means for tailoring the barrier height for a given circuit architecture. The monolithically integrated RIT/Schottky structure is suitable for fabrication of a complete diode logic family (AND, OR, XOR, INV)