Arsenic Contamination in Groundwater: A Global Perspective with Emphasis on the Asian Scenario

The incidence of high concentrations of arsenic in drinking-water has emerged as a major public-health problem. With newer-affected sites discovered during the last decade, a significant change has been observed in the global scenario of arsenic contamination, especially in Asian countries. This communication presents an overview of the current scenario of arsenic contamination in countries across the globe with an emphasis on Asia. Along with the present situation in severely-affected countries in Asia, such as Bangladesh, India, and China, recent instances from Pakistan, Myanmar, Afghanistan, Cambodia, etc. are presented

An Eight-year Study Report on Arsenic Contamination in Groundwater and Health Effects in Eruani Village, Bangladesh and an Approach for Its Mitigation

Based on several surveys during 1997-2005 and visits of a medical team to Eruani village, Laksham upazila, Comilla district, Bangladesh, the arsenic contamination situation and consequent clinical manifestations of arsenicosis among the villagers, including dermatology, neuropathy, and obstetric outcome, are reported here. Analysis of biological samples from patients and non-patients showed high body burden of arsenic. Even after eight years of known exposure, village children were still drinking arsenic-contaminated water, and many of them had arsenical skin lesions. There were social problems due to the symptoms of arsenicosis. The last survey established that there is a lack of proper awareness among villagers about different aspects of arsenic toxicity. The viability of different options of safe water, such as dugwells, deep tubewells, rainwater harvesting, and surface water with watershed management in the village, was studied. Finally, based on 19 years of field experience, it was felt that, for any successful mitigation programme, emphasis should be given to creating awareness among villagers about the arsenic problem, role of arsenic-free water, better nutrition from local fruits and vegetables, and, above all, active participation of women along with others in the struggle against the arsenic menace

Expression, purification and binding of upstream regulatory proteins of GhCYC3

Asteraceae comprises of approximately 10% of all angiosperm plant species. These species are well known for their highly compressed inflorescences known as capitula which consists of morphologically different types of flowers: ray, trans and disc flowers. This immense morphological difference excels Gerbera as an ideal plant to study flower type differentiations. Even though this complex process is governed by several genes, the ray flower identity is believed to be greatly influenced by GhCYC3 promoter mediated gene regulations. In previous studies two TCP transcription factors (TF): GhCIN1and GhCIN2, and two MADS TFs: GAGA1 and RCD5 were identified as the potential upstream regulators of GhCYC3. So, the aim of this study is to test whether these potential upstream regulators physically bind to GhCYC3 promoter in in vitro conditions. In order to achieve the goal, these transcription factor proteins from Gerbera hybrida were successfully expressed in E. coli and purified as fusion proteins to maltose-binding protein (MBP). Physical binding of the purified fusion proteins to the putative target DNA sites in the promoter region of GhCYC3 gene was tested by electrophoretic mobility shift assay (EMSA). The results showed that none of the gerbera transcription factors (GhCIN1, GhCIN2, GAGA1 and RCD5) bind to their putative target sites under the condition tested in this study. However, it might not be justifiable to deduce that these TFs do not interact with GhCYC3 promoter. The absence of in vitro interaction between the tested TFs and GhCYC3 promoter might be caused by either lack of proper folding and activity of the TFs or absence of co-factors which are available in vivo

Urea-based ruthenium (II)-polypyridyl complex as an optical sensor for anions: Synthesis, characterization, and binding studies

A new ruthenium(II) complex [Ru(bpy)2(1-(6-nitro-[1,10]phenanthrolin-5-yl)-3-(4-nitrophenyl)-urea)] (bpy = 2,2'-bipyridyl) was synthesized and characterized using standard analytical and spectroscopic techniques. Detailed absorption, emission, and 1H NMR spectral studies revealed that this receptor molecule acts as a sensor for F-, CH3COO-, and H2PO4- in acetonitrile solution. Binding of these anions caused an appreciable change in the color of the acetonitrile solution, which could be detected with the naked eye. At relatively lower concentration of anions, 1:1 H-bonded adduct was formed; however, at higher concentration, classical Bronsted acid-base-type reaction prevailed. The relative binding affinity of different anions toward this receptor was evaluated and was rationalized with quantum chemical calculations. Narrowing of the gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels on deprotonation of the receptor molecule caused a faster decay of the luminescence lifetime for the RudΠ → LΠ*/bpyΠ*-based triplet excited state

Microwave-Assisted Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones Using Acid-Functionalized Mesoporous Polymer

Synthesis and application of acid-functionalized mesoporous polymer catalyst for the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli condensation reaction under microwave irradiation is investigated. Several analytical techniques such as FT-IR, BET, TEM, SEM and EDX were employed to characterize the synthesized polymeric catalyst. High acidity (1.15 mmol g-1 ), high surface area (90.44 m2 g -1 ) and mesoporous nature of the catalyst effectively promoted the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones. Microwave irradiation shows higher yield (89-98 %) as compared to conventional heating (15-25 % yield) under our optimized reaction conditions such as 1:1:1.2 molar ratio of aldehyde/ethylacetoacetate/urea, catalyst loading of 6 wt.% (with respect to aldehyde), the temperature of 80 °C and microwave power of 50 W. The synthesized Biginelli products were fully characterized by 1H and 13C NMR. The reusability of the catalyst was investigated up to 5 successive cycles and it showed great stability towards the synthesis of 3,4-Dihydropyrimidin-2(1H)-ones without any significant depreciation in yields

A density functional study towards substituent effects on anion sensing with urea receptors

Effects of substituents on anion binding in different urea based receptors have been examined using density functional (B3LYP/6-311+G**) level of theory. The complexes formed by a variety of substituted urea with a halide anion (fluoride) and an oxy-anion (acetate) have been calculated. The stronger complexes were predicted for receptors with fluoride ion than that of acetate ion, however, in water the preference was found to be reversed. The pKa calculations showed the preferred sites of deprotonation for positional isomers, while interacting with anions. The position of the substituent in the receptor, however, could change the preferred sites of deprotonation compared to the site predicted with pKa values