Determination and Modelling of the Influence of Cooling in the Coil on the Mechanical Properties of Hot Strip Steels with Bainite

The phenomenon of bainite formation in the hot strip mill for unalloyed steels and the influence of the complex cooling process have hardly been dealt with in literature. Only two useful model equations were found, namely according to Suehiro et al. [4] for the determination of the strength parameters R_p0.2 and R_m of annealed bainite, and according to Umemoto et al. [2] for the calculation of the tensile strength R_m of bainite formed during the isothermal holding temperature. These equations could be optimized by structural complements and modification of the coefficients by adjusting them to the own measured values. For building up the necessary data base, experimental methods were developed, involving the use of a computerized deformation dilatometer. The results thus obtained can be applied to the industrial practice.     

Connection of surface tension with multiple tribological properties in epoxy + fluoropolymer systems

Contact angles of free liquids on solid samples were measured and the van Oss–Good method was applied for evaluating surface tensions of the solids. A parachor method was used for comparison: in this case the respective values were calculated for the polymer solids from molecular and group contributions. Surface tensions were computed from the parachors and the two methods compared. Effects of varying the fluoropolymer added to the epoxy before curing are discussed. For a given fluoropolymer, effects of changing its concentration on surface tension have also been evaluated and compared to the changes in scratch resistance (scratch penetration depth, recovery depth) and in static and dynamic friction. Morphological and phase structure changes are reflected in all these properties, showing a strong connection between the surface tension and tribological properties. Copyright © 2003 Society of Chemical Industry     

Formal timing analysis for distributed real-time programs

A static analysis method for verifying timing properties of real-time distributed programs is presented. The goal is to calculate the worst-case response time of concurrent tasks which run mainly independently but share, and may have to wait for, logical or physical devices. For such tasks, the determination of the worst-case waiting time is a crucial problem because of the unpredictable order of synchronization events. We investigate the class of distributed Client-Server programs in which independent, time-critical tasks (clients) are synchronized only through additional server tasks, playing the role of monitors or resource managers. This model follows well-known real-time design guidelines for distributed ADA programs proposed to enhance schedulability and synchronization analysis. Our formal analysis approach is flow graph oriented. It leads to generating reduced program paths each of which represents a sequence of ordered local and global operations, thus transforming and reducing the original problem of computing the worst-case waiting time of a concurrent task into a graph-theoretic problem of calculating the maximal blocking time for one of its corresponding program paths. While local operations are completely independent global operations require mutually exclusive access to shared resources. We prove that computing the worst-case blocking time for a program path is NP-complete. Even for a reduced problem solution—which would yield a good upper bound for the worst-case blocking time—there was a conjecture maintained over many years that this problem was NP-complete. A major result of this paper is to show that this is wrong. Instead, we construct a polynomial solution algorithm, and we prove its correctness. The effectiveness and complexity of our method are discussed, with particular emphasis on distributed real-time debugging.     

Antimutagenic and antiradical properties of flavones from the roots of Scutellaria baicalensis georgi

The four flavonoids baicalin, baicalein, wogonoside, and wogonin have been isolated from Scutellaria baicalensis (Lamiaceae) root extract as main bioactive components. We evaluated their antimutagenic activity as potential chemopreventive natural substances using the Ames test. Free radical scavenging properties have also been measured with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Both crude extract and isolated flavone glycosides and aglycones have antimutagenic and free radical scavenging properties. The lipophilic flavone baicalein has been confirmed to be the most powerful antimutagen among the compounds tested.     

Synthesis of polyetherols from melamine and ethylene carbonate

Attempts to synthesize s‐triazine ring containing polyetherols from melamine and ethylene carbonate are described. The conditions of synthesis providing optimal yields of the polyetherols were 165°C, melamine to ethylene carbonate molar ratio 1 : 9 to 1 : 18, and 4 g of potassium carbonate or diazabicyclo[2.2.2]octane catalyst per mole of melamine. The structure of the products was established by ¹H‐NMR and IR spectroscopy. The kind and amount of side products [mostly poly(ethylene glycols)] was determined by GLC. The polyetherols have been found useful in the synthesis of polyurethanes of improved thermal stability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1776–1784, 2001     

Microfluidic bioreactors for culture of non-adherent cells

Microfluidic bioreactors (μBR) are becoming increasingly popular for cell culture, sample preparation and analysis in case of routine genetic and clinical diagnostics. We present a novel μBR for non-adherent cells designed to mimic in vivo perfusion of cells based on diffusion of media through a sandwiched membrane. The culture chamber and perfusion chamber are separated by a sandwiched membrane and each chamber has separate inlet/outlets for easy loading/unloading of cells and perfusion of the media. The perfusion of media and exchange of nutrients occur through the sandwiched membrane, which was also verified with simulations. Finally, we present the application of this device for cytogenetic sample preparation, whereby we culture and arrest peripheral T-lymphocytes in metaphase and later fix them in the μBR. The expansion of T-lymphocytes from an unknown patient sample was quantified by means of CFSE staining and subsequent counting in a flow cytometer. To conclude on the applicability of μBR for genetic diagnostics, we prepare chromosome spreads on glass slides from the cultured samples, which is the primary step for metaphase FISH analysis.     

Fuel poverty and low carbon emissions: a comparative study of the feasibility of the hybrid renewable energy systems incorporating combined heat and power technology

Fuel poverty is most prevalent in North East England with 14.4% of fuel poor households in Newcastle upon Tyne. The aim of this paper was to identify a grid connected renewable energy system coupled with natural gas reciprocating combined heat and power unit, that is cost-effective and technically feasible with a potential to generate a profit from selling energy excess to the grid to help alleviate fuel poverty. The system was also aimed at low carbon emissions. Fourteen models were designed and optimized with the aid of the HOMER Pro software. Models were compared with respect to their economic, technical, and environmental performance. A solution was proposed where restrictions were placed on the size of renewable energy components. This configuration consists of 150 kW CHP, 300 kW PV cells, and 30 kW wind turbines. The renewable fraction is 5.10% and the system yields a carbon saving of 7.9% in comparison with conventional systems. The initial capital investment is $1.24 million which enables the system to have grid sales of 582689 kWh/a. A conservative calculation determined that 40% of the sales can be used to reduce the energy cost of fuel poor households by $706 per annum. This solution has the potential to eliminate fuel poverty at the site analyzed.     

Synthesis and characterization of cadmium(II)-imprinted poly(1-allyl-2-thiourea-co-ethylene glycol dimethacrylate) particles for selective separation

The synthesis and characterization of cadmium(II)-imprinted poly(1-allyl-2-thiourea-co-ethylene glycol dimethacrylate) particles are presented. Out of four functional monomers viz. allylurea, 1-vinylimidazole, acrylamide, and 1-allyl-2-thiourea, the last one was selected to produce a novel and selective separation material towards cadmium(II) ions. The energy dispersive X-ray spectroscopy confirmed the presence of monomer residues in the polymer matrix. The optimization of stoichiometry revealed that the highest binding capacity (3.79 ± 0.12 µg/g) and selectivity (imprinting factor of 13.68) were achieved when ion to monomer ratio was equal to 1:1. The structure, morphology and selectivity of imprinted polymer were examined. The imprinted particles possess regular, spherical shape and their surface is highly extended (10.31 ± 0.14 m²/g). The selectivity study towards ions which are present in the real sample showed highest uptake of cadmium(II) ions when compared to lead(II), cobalt(II) or nickel(II) ions with selectivity factors between 2.1 and 2.4.