Model for variation of laser power with M2

A functional relationship between M2 of a multimode laser and its extraction efficiency from a uniformly pumped cylindrical laser medium is derived from numerical calculations by use of helicoid modes.     

Enhanced T-cell immunogenicity and protective efficacy of a human immunodeficiency virus type 1 vaccine regimen consisting of consecutive priming with DNA and boosting with recombinant fowlpox virus

The induction of human immunodeficiency virus (HIV)-specific T-cell responses is widely seen as critical to the development of effective immunity to HIV type 1 (HIV-1). Plasmid DNA and recombinant fowlpox virus (rFPV) vaccines are among the most promising safe HIV-1 vaccine candidates. However, the immunity induced by either vaccine alone may be insufficient to provide durable protection against HIV-1 infection. We evaluated a consecutive immunization strategy involving priming with DNA and boosting with rFPV vaccines encoding common HIV-1 antigens. In mice, this approach induced greater HIV-1-specific immunity than either vector alone and protected mice from challenge with a recombinant vaccinia virus expressing HIV-1 antigens. In macaques, a dramatic boosting effect on DNA vaccine-primed HIV-1-specific helper and cytotoxic T-lymphocyte responses, but a decline in HIV-1 antibody titers, was observed following rFPV immunization. The vaccine regimen protected macaques from an intravenous HIV-1 challenge, with the resistance most likely mediated by T-cell responses. These studies suggest a safe strategy for the enhanced generation of T-cell-mediated protective immunity to HIV-1.     

Abattoir survey of sheep and goats in The Gambia

An abattoir survey of sheep and goats was carried out in The Gambia for one year. A total of 1248 goats and 438 sheep, predominantly young females, were slaughtered and sampled. Sixty per cent of the females of both species were pregnant. There were no significant differences between the dressing percentages of different breeds and age groups. Sex and stage of pregnancy had a significant influence on carcase yields in both species. In goats the highest carcase yields were obtained during the early dry season. Most of the animals were clinically healthy and there were few pathological findings postmortem. In both species, there was a seasonal fluctuation of packed cell volume (PCV), with a minimum during the rains, and although the prevalence of trypanosomiasis was low it reduced the PCV. Faecal egg counts of Trichostrongylidae were highest during the rainy season and goats had higher faecal egg and coccidial oocyst counts than sheep. In sheep, a breed difference was observed for PCV and an age difference for egg excretion. The peak or higher rates of egg excretion occurred during the rains in both species. The immune status against peste des petits ruminants was significantly lower in goats (39 per cent) than in sheep (49.5 per cent). Antibodies against bluetongue virus were found in 62.6 per cent of goats and 55.8 per cent of sheep.     

In vivo characterisation of a novel bioresorbable poly(lactide-co-glycolide) tubular foam scaffold for tissue engineering applications

Polylactide-co-glycolide (PLGA) foams of tubular shape were assessed for their use as soft-tissue engineering scaffolds in vitro and in vivo. Porous membranes were fabricated by a thermally induced phase separation process of PLGA solutions in dimethylcarbonate. The parameters investigated were the PLGA concentration and the casting volume of solution. Membranes produced from 5 wt/v % polymer solutions and a 6 ml casting volume of polymer solution were selected for fabricating tubes of 3 mm diameter, 20 mm length and a nominal wall thickness of 1.5 mm. Scanning electron microscopy revealed that the structure of the tubular foams consisted of radially oriented and highly interconnected pores with a large size distribution (50-300 microm). Selected tubes were implanted subcutaneously into adult male Lewis rats. Although the lumen of the tubes collapsed within one week of implantation, histological examination of the implanted scaffolds revealed that the foam tubes were well tolerated. Cellular infiltration into the foams, consisting mainly of fibrovascular tissue, was evident after two weeks and complete within eight weeks of implantation. The polymer was still evident in the scaffolds after eight weeks of implantation. The results from this study demonstrate that the PLGA tubular foams may be useful as soft-tissue engineering scaffolds with modification holding promise for the regeneration of tissues requiring a tubular shape scaffold such as intestine.     

Development of the Eco-Cascade- cell reactor

The development of multicompartment rotating cylinder electrode reactors for the removal of metal from aqueous solutions is described. Such reactors approximate to a cascade of continuously stirred tank reactors and the results illustrate that, for electrodeposition of copper powder from acid sulphate solutions, high overall conversions (about 98%) may be realised, with low exit metal concentrations (about 1 mg dm^–3) and reasonable current efficiencies (65–87%).Nomenclature A electroactive surface area (cm²) - C _in inlet concentration of metal (mg dm^–3) - C _out outlet concentration of metal (mg dm^–3) - C _reactor reactor concentration of metal (mg dm^–3) - f _R fractional conversion - (f _R)n overall fractional conversion - F Faraday=96 500 (C mol^–1) - I _L limiting current (A) - k _l mass transfer coefficient (cms^–1) - m weight of metal (g) - M molecular weight of metal - n number of reactor elements in the cascade - N volumetric flow rate (cm³ s^–1) - z electron change - dm/dt rate of removal of metal (gs^–1) This paper was presented, in part, at the Electrochemical Reaction Engineering Symposium, Southampton University, April (1979).     

Deposition thickness based high-throughput nano-imprint template

International Technology Roadmap for Semiconductors 2003 projected nano-imprint lithography has the potential of high throughput, sub-20 nm resolution, and low cost [S.Y. Chou, P.R. Krauss, P.J. Renstrom, Appl. Phys. Lett. 67 (1995) 3144; Science 272 (1996) 85, J.A. Rogers, C. Mirkin, Mater. Res. Bull. 26 (2001)]. For nano-imprint lithography, a template with 1X resolution is required. The existing industrial infrastructure for supporting deep ultra violet 4X photo masks by e-beam and/or a laser beam scanning writer does not offer pitch (center-to-center distance of an array of patterned lines) less than ∼60 nm [<http://public.itrs.net/2003ITRS>]. For nano-imprint lithography to be accepted across the industry, a reproducible simple fabrication process to make a high resolution, single emboss template is essential [L. Jay Guo, J. Phys. D: Appl. Phys. 37 (2004) R123-R141]. Here we show, a general fabrication method and fabricated nano-imprint templates with sub-15 nm template line width and 10 nm pitch length through out the entire 200 mm wafer, varying the deposition thickness of multiple alternate films, using atomic layer deposition. Although multilayer nano-imprint templates and their exciting use have been demonstrated, [W.J. Dauksher et al., J. Vac. Sci. Technol. B 22 (2004) 3306, B. Heidari, et al., The 49th international conference on electron, ion and photon beam technology and nanofabrication, Orlando, Florida, 2005, William M. Tong, et al., Proc. SPIE 5751 (2005) 46-55, N.A. Melosh, A. Boukai, F. Diana, B. Gerardot, A. Badolato, P.M. Petroff, J.R. Heath, Science 300 (2003) 112] such a small pitch was not shown and either complex lattice mismatch-based epitaxially grown films or unconventional etch chemistry was used. The bare necessity was a simple and economical fabrication process for a high throughput nano-imprint template. In that context, we have developed a template fabrication process using classical micro-fabrication techniques. Successful use of these techniques made the template fabrication process simple, economical, and expedient. Also a novel technique to provide flexible and accurate alignment for nanowire patterning has been described. In this technique, nanowire patterning is accomplished on the entire wafer with a single impression. Industry level batch-fabrication of our scheme illustrates its reproducibility and manufacturability. We anticipate, this simple, economical and time saving technique will help researchers and developers to perform their experiment on nano-scale feature patterned substrates easily and conveniently.