Anisotropic tomography of heavy quark dissociation by using general propagator structure at finite magnetic field

In this work we have explored the imaginary part of the Heavy Quark (HQ) potential and subsequently the dissociation of heavy quarkonia, within the most general scenario of magnetized hot medium. We have used the general structure of the gauge boson propagator in a hot magnetized medium and derived the most general result for the imaginary HQ potential and the decay width for the heavy quarkonia. In the process we have investigated the rich anisotropic structure of the complex HQ potential which explicitly depends on the longitudinal and transverse distance. We have also compared our full structure rich result with various approximated results available in the literature and explained the differences between them.Comment: 23 pages, 9 figure

Heavy quark potential and LQCD based quark condensate at finite magnetic field

We have studied various properties of heavy quarkonia in hot and magnetized quark gluon plasma. Inverse magnetic catalysis (IMC) effect is incorporated by modifying the effective quark masses. Then we obtain the real and imaginary part of the heavy quark potential. After evaluating binding energy and decay width we obtain the dissociation temperature of heavy quarkonia in presence of magnetic field.Comment: 15 pages, 7 figure

Assessment of creep and rupture behavior of 2.25Cr-1Mo steel – A strain-based approach and its limitation

Increasing demand of 2.25Cr-1Mo steel, among different grades of low alloy Cr-Mo steels, in power plants and petrochemical industries is mainly because of its high creep resistance. Application of a strain based approach for a reliable assessment of creep and rupture behavior is thus of great importance. Creep data were generated under different microstructural conditions in the laboratory and collected from literature as well. The influence of thermal ageing and pre-strain on the shape of creep curves has been studied. Analysis of data revealed that irrespective of initial microstructures, thermal ageing increases the tendency to soften but not the pre-strain. Softening due to carbide coarsening thus appears to be the dominant mechanism of creep. Based on this, a strain based approach for creep life assessment was developed. A fairly accurate prediction of creep life up to 5% creep is achieved using eight materials constants extracted from the creep curves of steel having similar initial microstructure. The limitation and reliability of the approach used to assess creep behavior of service-exposed steels have been discussed

Probabilistic creep life assessment of austenitic stainless steel

Experimental investigations on the creep behaviour of engineering materials are frequently conducted for the purposes of design, development and service life prediction. However, tests on a single specimen yield a definite value for each material parameter. But when a number of specimens are tested, the parameter values randomly fluctuate from specimen to specimen. The scatter observed in creep deformation and failure data is of considerable technological importance because it greatly complicates the task of making accurate deformation and lifetime estimates for high temperature components. Repeat data on austenitic stainless steel provided a unique opportunity to identify stochastic creep properties and to use this information to build a probabilistic creep damage assessment for this alloy

Seasonal variation of arsenic concentrations in tubewells in west Bengal, India.

This study was conducted to monitor the changes in arsenic concentration during different seasons in a one-year period during 2002-2003 in selected tubewells in an arsenic-affected area in the district of South 24 Parganas in West Bengal, India, and to map the location of the wells. Seasonal variations in concentrations of arsenic in water were measured from 74 selected tubewells, ranging in depth from 40 to 500 feet. Water samples were collected from these wells during winter, summer, monsoon, and the following winter in 2002-2003. A global positioning system was used for locating the tubewells, and a geographic information system was used for mapping. There was evidence of seasonal variation in concentrations of arsenic in water (p=0.02) with the minimum average concentration occurring in the summer season (694 microg/L) and the maximum in the monsoon season (906 microg/L). From the winter of 2002 to the winter of 2003, arsenic concentrations increased, irrespective of the depth of the tubewells, from an average of 464 microg/L to 820 microg/L (p<0.001). This extent of variation in arsenic concentration, if confirmed, has important implications for both epidemiological research and mitigation programmes

Creatinine, diet, micronutrients, and arsenic methylation in West Bengal, India.

BackgroundIngested inorganic arsenic (InAs) is methylated to monomethylated (MMA) and dimethylated metabolites (DMA). Methylation may have an important role in arsenic toxicity, because the monomethylated trivalent metabolite [MMA(III)] is highly toxic.ObjectivesWe assessed the relationship of creatinine and nutrition--using dietary intake and blood concentrations of micronutrients--with arsenic metabolism, as reflected in the proportions of InAS, MMA, and DMA in urine, in the first study that incorporated both dietary and micronutrient data.MethodsWe studied methylation patterns and nutritional factors in 405 persons who were selected from a cross-sectional survey of 7,638 people in an arsenic-exposed population in West Bengal, India. We assessed associations of urine creatinine and nutritional factors (19 dietary intake variables and 16 blood micronutrients) with arsenic metabolites in urine.ResultsUrinary creatinine had the strongest relationship with overall arsenic methylation to DMA. Those with the highest urinary creatinine concentrations had 7.2% more arsenic as DMA compared with those with low creatinine (p < 0.001). Animal fat intake had the strongest relationship with MMA% (highest tertile animal fat intake had 2.3% more arsenic as MMA, p < 0.001). Low serum selenium and low folate were also associated with increased MMA%.ConclusionsUrine creatinine concentration was the strongest biological marker of arsenic methylation efficiency, and therefore should not be used to adjust for urine concentration in arsenic studies. The new finding that animal fat intake has a positive relationship with MMA% warrants further assessment in other studies. Increased MMA% was also associated, to a lesser extent, with low serum selenium and folate

Nutritional Factors and Susceptibility to Arsenic-Caused Skin Lesions in West Bengal, India

There has been widespread speculation about whether nutritional deficiencies increase the susceptibility to arsenic health effects. This is the first study to investigate whether dietary micronutrient and macronutrient intake modulates the well-established human risk of arsenic-induced skin lesions, including alterations in skin pigmentation and keratoses. The study was conducted in West Bengal, India, which along with Bangladesh constitutes the largest population in the world exposed to arsenic from drinking water. In this case–control study design, cases were patients with arsenic-induced skin lesions and had < 500 μg/L arsenic in their drinking water. For each case, an age- and sex-matched control was selected from participants of a 1995–1996 cross-sectional survey, whose drinking water at that time also contained < 500 μg/L arsenic. Nutritional assessment was based on a 24-hr recall for major dietary constituents and a 1-week recall for less common constituents. Modest increases in risk were related to being in the lowest quintiles of intake of animal protein [odds ratio (OR) = 1.94; 95% confidence interval (CI), 1.05–3.59], calcium (OR = 1.89; 95% CI, 1.04–3.43), fiber (OR = 2.20; 95% CI, 1.15–4.21), and folate (OR = 1.67; 95% CI, 0.87–3.2). Conditional logistic regression suggested that the strongest associations were with low calcium, low animal protein, low folate, and low fiber intake. Nutrient intake was not related to arsenic exposure. We conclude that low intake of calcium, animal protein, folate, and fiber may increase susceptibility to arsenic-caused skin lesions. However, in light of the small magnitude of increased risks related to these dietary deficiencies, prevention should focus on reducing exposure to arsenic

Modelling high temperature creep of Cr---Mo steel

A computer based design aid called CRISPEN using established physical models of creep deformation has been developed jointly by NPL Teddington and Cambridge University for creep strain prediction of engineering alloys. This has been used to successfully predict the creep behaviour of a range of superalloys where strain softening is the most dominant mechanism of creep deformation. The present work examines how this approach could be modified to include the effect of softening due to time dependent particle coarsening, which is the most dominant mechanism of creep deformation in Cr---Mo steel. A computer program has been developed to analyse creep curves to extract the relevant constants. A large volume of existing database on 2.25 Cr---1Mo steel has been used to validate the approach. The physical significance of the parameters used has been analysed to identify the nature of stress dependence of particle coarsening behaviour in these steels

Stress rupture ductility diagram - A diagnostic tool

The present work suggests a methodology for construction of stress rupture ductility diagram using the concept of geometrical factor k that determines the nature of creep rupture. Large volumes of stress rupture ductility data of a range of engineering materials generated experimentally in the laboratory and reported in the literature have been used to study the nature of creep rupture by superimposition of these data on the above diagram. The rupture ductility of Ni-base superalloy, when superimposed on such diagram, indicates that the failure in this alloy could be due to limited amount of localised deformation or cavitation. In case of Zr-Nb alloy, the rupture ductility data lie in the necking regime extending from k=0.9 to 0.4. In contrast, the data on Cr-Mo steel show a wider variation extending from the regime of cavitation to extensive necking. Reliable prediction of rupture ductility is possible within a narrow range of k in which the nature of creep rupture remains the same