Application of fly ash as a catalyst for synthesis of carbon nanotube ribbons

The larger diameter-based carbon nanotube (CNT) ropes and ribbons are currently synthesized by catalytic decomposition of hydrocarbons with transition metal-based catalysts e.g., Co, Ni, Fe and Mo at 1100-1200 °C, using chemical vapour deposition (CVD) and electric arc methods. We produced CNT ribbons by fly ash (FA) catalyzed pyrolysis of a composite film of poly (vinyl alcohol) (PVA) with FA at 500 °C for 10 min under a nitrogen flow of 2 L/min. Different geometrical structures, e.g.; knotted and twisted, U- and spiral-shaped CNT ribbons were observed in the images of scanning and transmission electron microscopy. The widths of the CNT ribbons measured varied in the ranges 18-80 nm. X-ray photoelectron spectroscopy analysis showed five types of carbon binding peaks, C-C/C-H (∼77%), C-O-H (∼9%), -C-O-C (∼5%), CO (∼5%) and -O-CO (∼3%). The ratio of intensities of G and D bands, IG/ID was 1.61 analysed by Raman Spectroscopy. CNT ribbons grown on the surface of FA have potential for the fabrication of high-strength composite materials with polymer and metal.     

Temperature and intensity dependence of Yb-fiber laser light absorption in water

Absorption of CW Yb-fiber laser light of 1.07 μm wavelength in water has been measured at different water temperatures and laser intensities. The absorption coefficient was estimated to be 0.135 cm(-1) at 25 °C water temperature, and this was found to decrease with temperature at a rate of 5.7 × 10(-4) cm(-1) °C(-1). The absorption coefficient increased significantly when the laser beam was focused in water, and the increase depended on the distance of the focal point from the water surface. This has been attributed to the absorption and scattering losses of laser radiation in a cavity formed in water by the focused beam at laser intensities in the megawatts per square centimeter and higher range.     

Synthesis and characterization of indium intercalation compounds of tungsten disulphide: InxWS2 (0 ⩽ x ⩽ 1)

The present work reports on the synthesis of indium intercalation compounds In_xWS₂ (0 ? x ? 1). The material has been characterized by X-ray studies for structure determination and particle size distribution, room temperature magnetic susceptibility, thermoelectric power experiments and conductivity measurements in the temperature range 150–300 K. These results have indicated that, like the host material WS₂, the intercalated compounds also possess hexagonal symmetry and are diamagnetic p-type semiconductors. The activation energy for these compounds was determined from the conductivity data.     

Effect of partial dehydration on quality of canned potatoes

During commercial sterilization, mild to severe breakage of individual potatoes sometimes occurs and the outer layers of potatoes disintegrate into a floury texture referred to as sloughing. Four cultivars of potatoes namely Kufri Badshah, Kufri Bahar, Kufri Chandramukhi and HPS-1/13 were either treated with CaCl₂ or dehydrated before canning to reduce the sloughing. The extent of sloughing in terms of breakage observed visually depended on the cultivar of potatoes. Although CaCl₂ treatment reduces sloughing, it causes turbidity of the brine. Partial dehydration of potatoes before canning was helpful in reducing sloughing and it allowed a higher filling of potato solids in the can thereby increasing drained weight. HPS-1/13 cultivar was found most suitable for dehydrocanning.     

1,N2-propanodeoxyguanosine adducts: potential new biomarkers of smoking-induced DNA damage in human oral tissue

Diarrhea is a non-specific symptom which may be associated with Addison's disease and several causes had been demonstrated in the aetiology. We describe a patient with Addison's disease who was suffering from chronic diarrhea for three months. She was diagnosed as having collagenous colitis and successfully treated with Sulphasalazine, 2 g/day. Collagenous colitis is an uncommon cause of chronic diarrhea and the association of collagenous colitis with Addison's disease has not previously been described. We think that collagenous colitis may play a role in the aetiology of diarrhea in patients with Addison's disease and therefore we suggest a full colonoscopic examination in other patients with Addison's disease and diarrhea to determine the incidence of collagenous colitis in the aetiology of diarrhea.     

Laser power coupling efficiency in conduction and keyhole welding of austenitic stainless steel

Laser welding of thin sheets of AISI 304 stainless steel was carried out with high power CW CO₂ laser. The laser power utilized in the welding process was estimated using the experimental results and the dimensionless parameter model for laser welding; and also the energy balance equation model. Variation of laser welding efficiency with welding speed and mode of welding was studied. Welding efficiency was high for high-speed conduction welding of thin sheets and also in keyhole welding process at high laser powers. Effect of pre-oxidization of the surface and powder as filler material on laser power coupling is also reported. The paper also discusses effect of microstructure on the cracking susceptibility of laser welds.     

The regulation of collagen in fetal skin wounds: mRNA localization and analysis

The deposition of collagen in fetal skin wounds has been shown in several animal models. The authors used a radiolabeled RNA antisense probe, complementary to the mRNA for the alpha-1 chain of human procollagen type I, to assess regulation of this collagen species in fetal and adult rabbit wounds. Dorsal skin wounds were placed on fetal and maternal animals at the beginning of the third trimester, and were harvested 3, 5, and 7 days later. In situ RNA/RNA hybridization was performed on suitable specimens, and morphometric analysis was carried out with a computerized LECO image analyzer. Fetal wounds exhibited an inflow of mesenchymal cells that produced collagen type I at levels higher than the surrounding tissue; this activity was highest on days 3 and 5 after wounding. Adult wounds had increased fibroblast presence by day 7, producing collagen type I at levels higher than those of adjacent unwounded tissue. Morphometric analysis of the signal produced by in situ hybridization and of the number of cells producing the signal in a given field showed that fetal wounds appear to produce collagen type I by an increase in the number of cells in the area of the wound--not by induction of the gene for procollagen type I. In contrast, adult wounds had both fibroblast migration and induction of procollagen type I mRNA synthesis. These findings imply multilevel regulation of collagen production in the adult and posttranslational regulation in the fetus.     

AIDS dementia complex with generalized myoclonus

Focal and segmental, but not generalized, myoclonus have been described with human immunodeficiency virus (HIV) infection. We describe three patients with generalized myoclonus and acquired immunodeficiency syndrome (AIDS) dementia complex. In each, myoclonus persisted until death, invariably after a course of a few months. In two patients, myoclonus was elicited by sudden auditory stimuli and resembled a startle response. This form of myoclonus may be subcortical in origin. We suggest that the AIDS dementia complex be included among the causes of myoclonic dementia.     

Clinical trials and tribulations: lessons learned from recruiting pregnant ex-smokers for relapse prevention.

The development of smoking cessation and relapse prevention interventions for pregnant and postpartum women is a public health priority. However, researchers have consistently reported substantial difficulty in recruiting this population into clinical trials. The problem is particularly acute for relapse prevention studies, which must recruit women who have already quit smoking because of their pregnancy. Although these individuals are an important target for tobacco control efforts, they represent an extremely small subgroup of the general population. This paper describes multiple recruitment strategies used for a clinical trial of a self-help relapse prevention program for pregnant women. The effectiveness of the strategies and the direct expense per participant recruited are provided. A proactive recruitment strategy (telephoning women whose phone numbers were purchased from a marketing firm) was ultimately much more successful than a variety of reactive strategies (advertisements, press releases, direct mail, Web placement, health care provider outreach). We found few differences between proactively and reactively recruited participants on baseline variables. The primary difference was that the former had smoked fewer cigarettes per day and reported lower nicotine dependence prior to quitting. Strengths and limitations of the recruitment strategies are discussed.