An improved and facile preparation of 3,7-dinitro-1,3,5,7-tetraazabicyclo [3,3,1] nonane(DPT) has been developed starting from urea. In the procedure DPT was synthesized viaN,N’-dinitrourea (DNU) as intermediate and various operating parameters such astemperature, pH and molar ratio of reagents have been optimized to give maximum yield ofthe desired product. The low cost method is concise, oper...

The title isochroman ( 8 ) was synthesized as a suitable substrate for acetoxylation studies leading to an intermediate of type (4), expected to afford, on condensation with diketen, the fungal metabolite "rotiorin" type linear product (1). Cyclocondensation of alcohol (6), obtained by the reduction of ketone (5) with paraform in the presence of anhydrous aluminum chloride afforded the dim...

In this paper we present a Hashed-Path Traveling Salesperson Problem (HPTSP), a new type of problem which has the interesting property of having no polynomial time solutions. Next we show that HPTSP is in the class NP by demonstrating that local information about subroutes is insufficient to compute the complete value of each route. As a consequence, via Ladner’s theorem, we show that the class...

OBJECTIVE To determine the prevalence and intensity of schistosomiasis in urban and peri-urban Kariba. DESIGN A cross sectional schistosomiasis survey involving screening people for infection and searching for intermediate host snails. SETTING Lake Kariba Research Station, Zimbabwe. SUBJECTS One thousand and seventy three people living in four residential areas of Kariba were screened for...

Due to the scarce information about the epidemiological features of schistosomiasis in which the vector is Biomphalaria tenagophila, an investigation was carried in Pedro de Toledo in 1980 where such peculiarity is observed. Stool examinations (Kato-Katz method) were performed in 4,741 individuals (22.8% positive to Schistosoma mansoni eggs) of this 583 had previously received chemotherapy and ...

As a part of a broader effort to determine the status of Paragonimus species infection in Lao PDR, an epidemiological survey was conducted on villagers and schoolchildren in Namback District between 2003 and 2005. Among 308 villagers and 633 primary and secondary schoolchildren, 156 villagers and 92 children evidenced a positive reaction on a Paragonimus skin test. Only 4 schoolchildren out of ...

Control of schistosomiasis in Venezuela has been a topic of major interest and controversy among the metaxenic parasitosis. A small area of transmission of approximately 15,000 km2 was thought to be eradicated some years ago. However, some epidemiological characteristics of our transmission area have limited the success on the way toward eradication. Since 1945, when the Schistosomiasis Control...

Denitrification is a reduction of nitrate by heterotrophic and autotrophic bacteria that may ultimately produce molecular nitrogen (N2) through a series of intermediate nitrogen compounds.Vermiculite is a hydrous phyllosilicate mineral (Mg, Fe+2,Fe+3)3[(Al,Si)4O10](OH)2·4H2O with several layers for bacterial immobilization. The goal of this study was removal of nitrate from water with vermiculi...