Porosity and tensile ductility in Al-Zn alloys

The tensile ductility of Al-Zn alloys processed in two different ways was examined over a broad range of temperature and strain rates. The different processing conditions produced materials with differing initial void andJor inclusion contents. If all the defects present are assumed to be in the form of voids, their respective volume fractions in the two alloys are 0.5 and 1.5 pct. Testing at temperatures from 77 to 480 K encompasses a range of mechanical behavior, ranging from brittle to superplastic. The poorly processed material has markedly less ductility than the one containing fewer defects both at high temperatures and at near cryogenic ones (196 K), where the alloys are marginally ductile. Increasing strain rate embrittles alloys in the temperature range 196 K to 300 K. At 196 K the strain rate needed to induce brittleness in the low defect alloy is over two orders of magnitude higher than in the alloy with a greater voidJinclusion content. Critical embrittling strain rates at room temperature are in the range common to conventional metal-forming operations for the poorly processed alloy, and thus cold formability devolves importantly on initial processing. In the vicinity of room temperature and at low strain rates, tensile ductility is greater for alloys with a higher defect concentration; this behavior is related to the development of multiple necks in the poorly processed materials. At the highest temperatures investigated, tensile ductility correlates directly with strain rate sensitivity and material defect concentration. Materials with low defect concentrations resist neck development during quasi-uniform flow to a much greater degree than do those with a high defect concentration. B. HARRIPRASHAD, formerly Graduate Student at Michigan Technological University T. H. COURTNEY, formerly Professor, Department of Metallurgical Engineering, and Dean of the Graduate School at Michigan Technological University.     

Altered specificities of genetically engineered {alpha}1 antitrypsin variants

Seven active site variants of human ₁-antitrypsin (₁AT) wereproduced in Escherichia coli following site-specific mutagenesisof the ₁AT complementary DNA. ₁AT (Ala ³⁵⁸), ₁AT (Ile³⁵⁸ and₁AT (Val³⁵⁸), were efficient inhibitors of both neutrophil andpancreatic elastases, but not of cathepsin G. ₁AT (Ala³⁵⁸, Val³⁵⁸)and ₁AT (Phe³⁵⁸ specifically inhibited pancreatic elastase andcathepsin G respectively. The most potent inhibitor of neutrophilelastase was ₁AT (Leu³⁵⁸), which also proved to be effectiveagainst cathepsin G. The ₁AT (Arg³⁵⁸) variant inactivated thrombinwith kinetics similar to antithrombin III in the presence ofheparin. Electrophoretic analysis showed that SDS-stable highmol. wt complexes were formed between the mutant inhibitorsand the cognate proteases in each case. These data indicatethat effective inhibition occurs when the ₁AT P1 residue (position358) corresponds to the primary specificity of the target protease.Moreover, alteration of the P3 residue (position 356) can furthermodify the reactivity of the inhibitor. Two of the variantshave therapeutic potential: ₁AT (Leu³⁵⁸ may be more useful thanplasma ₁AT in the treatment of destructive lung disorders and₁ (Arg³⁵⁸ could be effective in the control of thrombosis.     

Electronic Records Management in Local Government Agencies: The Case of the Clerk of Courts Office in Lake County Florida

ABSTRACT

Local governments must provide public access to records such as court proceedings, deeds, marriage licenses, birth, and death records, and so on, often on tight budgets. This article focuses on how a local agency, the Clerk of Courts office in Lake County, Florida, used a planning process developed by the National Center for State Courts. This process was loosely coupled with the principles of sensemaking (Weick, 1995 Weick, K. E. 1995. Sensemaking in organizations. Thousand Oaks, CA: Sage Publications.  [Google Scholar]) to stay ahead of the curve concerning changes that would significantly affect its records management system. By applying the scanning methods, the organization was able to paint a plausible picture of its future environment that allowed it to attack the issues related to legislative changes in its electronic records management (ERM) practices proactively rather than reactively.     

Anthropometry of the Hong Kong male and the design of bus driver cabs

This study investigated the proposition that the crabs of buses imported into Hong Kong were not suited to the anthropometric characteristics of the local Chinese bus drivers. A ‘recommended’ cab design was derived from static anthropometric data; relationships between pedals, steering wheel and seat, and the range of seat adjustments were specified. Overall static anthropometric data were available but additional data had to be estimated by constructing manikins based on the available Hong Kong static data with joint positions derived from data for the US male population. Seven bus cab designs in current use were compared with the ‘ recommended’ design. None of them satisfied all the ‘recommended’ design specifications, the most serious deviations being the excessive height of the seat above the floor and pedals, and insufficient lateral separation between the pedals.     

Mediated disclosure on Twitter: The roles of gender and identity in boundary impermeability,valence, disclosure,and stage

Social media such as microblogs (Twitter™) allow more people to disclose more personal and private information more frequently to more others than ever before. But what is the nature of, and what factors influence, those disclosures? Applying concepts from research and theory on self-disclosure research and microblogging, this study analyses 3751 tweets, with nearly half including disclosures, over a three-day period. At the user level, user-controlled boundary impermeability varied by user gender, feed identity (parenting, social media professional), and their interaction. At the tweet level, tweet valence, presence of disclosure, and front- or back-stage disclosure were variously influenced by user gender, Twitter feed identity, interactions between them, and boundary impermeability. Social construction of gender roles and social identities, as well as individual tendencies, and possibly communication contexts, are reflected in the valence, presence, and stage of disclosures in microblog content.     

Micropatterned Surfaces for the Study of Cancer and Endothelial Cell Interactions with Hyaluronic Acid

Hyaluronic acid (HA) is a glycosaminoglycan component of the extracellular matrix. Studies have shown that various cancers exhibit high levels of HA content, and that an increased amount of HA corresponds to poor patient prognosis. HA has been implicated in cellular interactions that are associated with cancer progression, including cell adhesion, motility, and differentiation. Micropatterned functional HA surfaces were developed to study interactions between cancer cells and HA. The adhesion and migration of cancer cells representing different stages of tumorigenesis were examined. A similar surface patterning approach was used to create HA regions next to fibronectin in two- and three-dimensional settings to visualize and study the interactions between cancer and endothelial cells. The ability to observe the dynamic interactions of cancer cells and angiogenesis within a HA-rich microenvironment will improve the fundamental understanding of cancer progression and contribute to the development of advanced therapeutic targets.     

Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces

Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of bio-recognition elements such as antibodies tethered to sensor surfaces. The search for novel surfaces that improve the stability of biomolecules and assay performance has been pursued for a long time. However, the anticipated improvements in stability have not been realized in practice under physiological conditions because the surface functionalization layers on commonly used substrates, silica and gold, are themselves unstable on time scales of days. In this paper, we show that covalent linking of antibodies to diamond surfaces leads to substantial improvements in biological activity of proteins as measured by the ability to selectively capture cells of the pathogenic bacterium Escherichia coli O157:H7 even after exposure to buffer solutions at 37 °C for extended periods of time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD simulations suggest that by using highly stable surface chemistry and controlling the nanoscale organization of the antibodies on the surface, it is possible to achieve significant improvements in biological activity and stability. Our findings can be easily extended to functionalization of micro and nanodimensional sensors and structures of biomedical diagnostic and therapeutic interest.