Vibrio cholerae serogroup O139 Bengal, a novel strain with epidemic potential, completely displaced V. cholerae serogroup 01 in Calcutta in January 1993, which was followed by an epidemic caused by V. cholerae O139 in March-May 1993. From November 1992 to July 1993, 95.6% of 916 V. cholerae isolates submitted to the National Institute of Cholera and Enteric Diseases from 28 locations in India were confirmed as serogroup O139. As of July 1993, V. cholerae O139 had been isolated from 13 Indian states and a union territory, and large outbreaks of cholera caused by the O139 serogroup had occurred in several cities. The extent of spread of V. cholerae O139 Bengal in India and its ability to swiftly disseminate leaves little doubt that this is the beginning of the eighth pandemic of cholera.
THE estimation and removal of the free iron oxides resent in soils are of considerable interest in view of the importance o P iron oxides in the process of odzolization, laterization, and phosphate fixation. The removal of P ree iron oxides also facilitates the identification and estimation of minerals present in soils and clays by X-ray, petrographic, and thermal analyses.A number of methods has been suggested since Tamm (1922) first proposed acid ammonium oxalate to remove free oxides of silicon, aluminium, and iron. Mattson (1931) used hot saturated aluminium chloride to remove the free sesquioxides from clays. Drosdoff and Truog (1935) found that when soil or clay suspensions were saturated with hydrogen sulphide under alkaline conditions, free iron oxides were converted into sulphides which could subsequently be removed by 0.05 N hydrochloric acid. This treatment dissolved finely ground ferric oxide, but had no appreciable effect on the iron in biotite, basalt, and granite. Truog and co-workers (1936) later modified the method. Instead of passing hydrogen sul hide through the suspension, nascent hydrogen sulphide was produce c f within the suspension by the action of oxalic acid on sodium sulphide. The iron sul hide was dissolved by the stable towards the reagent, but the iron exchange complex was less stable. Jeffries (1941) pro osed a method for removing iron oxides from action of nascent hydrogen produced by the action of oxalic acid on an aluminium cylinder immersed in a boiling solution. Dion (I 44) modisoil suspension with 10 per cent. ammonium tartrate in presence of metallic aluminium. Allison and Scarseth (1942) used anaerobic decomposition of a sugar solution in soil to reduce the iron oxide to the ferrous and soluble state.The present investigation was carried out in an attempt to find a suitable method or modification of existing methods for estimating and removing free iron oxides from soils and clays without affecting the other clay minerals. With this end in view preliminary experiments were carried out to find the effect of:(I) Soil-solution ratio, 2 Time of digestion or shaking, I) 3 Effect of repeated treatments, on the removal of iron oxides by different methods. The soil used was a subsoil from Knott Wood, Rothamsted. Organic matter was destroyed by the action of hydrogen peroxide and the oxalic acid. The aluminium exchange comp e ex was found to be quite sand and silt for minera f ogical estimation. Iron was reduced by the fied the method of Jeffries and carried out the reduction by R eating the
Our objective was to assess HIV risk perceptions, risk behaviours and factors that may facilitate an increase in injection drug use in Calcutta. Focus group discussions and in-depth interviews were conducted with a selected group of drug users to delineate drug use patterns, languages used to express addictive and related experiences and acceptance of harm minimization messages. Results from these were used to develop a semi-structured interview instrument which was used to interview 111 drug users (76 IDUs and 35 non-IDUs) recruited from jails and detoxification centres. Secondary data of narcotic seizures for the last 5 years were collected from the Calcutta police department. Data on percentage of IDUs admitted to large detox facility in the city was also collected. Findings show that HIV/AIDS knowledge and risk perceptions were low; sharing of injection equipment was reported by 66% of the injectors; and condom use was insignificant. Non-availability, rising cost and increasing tolerance to heroin were cited as factors contributing to switch to injection. Ecological association was found between intensified police activity and an increase in: the amount of smokable heroin seized; increased injection of buprenorphine; and admission to detoxification centres. In addition to HIV, IDUs were also found to be prone to hepatitis B and C. The findings suggest an urgent need for developing and implementing community-based HIV prevention interventions targeting drug users in Calcutta.
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