[Hydrogenotrophic denitrification of water using zero valent iron Nano particles]

Nitrate is a water contaminant that can cause health problems in human and animals, in addition to eutrophication of the water body. So, Nitrate-contaminated water may be treated by treatment systems. In this study, hydrogenotrophic denitrification using hydrogen produced by Fe[0] as an electron donor to nitrate removal was evaluated to assess the feasibility of employing Fe[0] in the biological nitrate treatment. Batch experiments were conducted using 250 ml amber bottles at 20-35°C under anoxic conditions. The nitrate concentration in each reactor was 20 mg N/L and triplicate samples were prepared for the following treatment: Fe[0] plus cells, Fe[0] only, and control. The effect of Fe[+2] and temperature on nitrate reduction was evaluated. 97 percent of Nitrate was reduced within 2 day in a Fe[0]-cell reactor, while only 30% of the nitrate was abiotically reduced over 2 day at 30°C. Fe[+2], which is produced during anaerobic iron corrosion in the Fe[0]-cell system, might act as an electron donor for nitrate. Abiotic reduction and microbial reduction of nitrate was significantly affected by temperature conditions. The reduction rate decreased as the temperature deceased. This study demonstrated the potential applicability of employing Fe[0] as a source of electrons for biological nitrate reduction. Use of Fe[0] for microbial nitrate reduction can obviate the disadvantages associated with traditional biological denitrification that relies on the use of organic substrates or explosive hydrogen gas

Anodically deposited Mn-Mo-o electrodes by direct and pulse current as novel anode materials for hydrogen production during seawater electrolysis

Hydrogen is currently well recognized as a future fuel. Its production from seawater electrolysis using electroactive anode is presented in this study. Mn-Mo-O which is known for its efficiency as well as environmentally benign nature is used in this work. Direct and pulse electro-deposition methods were applied for preparation of the Mn-Mo-O electrode. Variation of both direct and pulse current. using sulfuric MnSO4-Na2MoO4 electrolyte solutions were the basis of the experiments. The electrodes were characterized by X-Ray Diffraction [XRD], Scanning Electron Microscopy [SEM] and electrochemical measurements. The performance of the electrodes were evaluated in 0.5M NaC1 electrolyte solution by electrolysis at 1000 Am[-2]. The findings indicated that pulse electrodeposition provide anode materials with better activity and durability as compared to direct electrodeposition method. The results are discussed in terms of structure, composition and mechanical properties of the anodes

Hydrogen production by photosynthetic green algae.

Oxygenic photosynthetic organisms such as cyanobacteria, green algae and diatoms are capable of absorbing light and storing up to 10-13% of its energy into the H-H bond of hydrogen gas. This process, which takes advantage of the photosynthetic apparatus of these organisms to convert sunlight into chemical energy, could conceivably be harnessed for production of significant amounts of energy from a renewable resource, water. The harnessed energy could then be coupled to a fuel cell for electricity generation and recycling of water molecules. In this review, current biochemical understanding of this reaction in green algae, and some of the major challenges facing the development of future commercial algal photobiological systems for H2 production have been discussed.

Molecular aspects on the interaction of sanguinarine with B-form, Z-form and HL-form DNA structures.

The interaction of sanguinarine with right-handed (B-form), left-handed (Z-form) and left-handed (HL-form) structures of poly(dG-dC).poly(dG-dC) has been investigated by measuring the circular dichroism (CD) and UV-absorption spectral analysis. Sanguinarine binds strongly to the B-form DNA and does not bind to Z-form or HL-form, but it converts the Z-form and the HL-form back to the bound right handed form as evidenced from CD spectroscopy. Sanguinarine inhibits the rate of B to Z transition under ionic conditions that otherwise favour the left-handed conformation of the polynucleotides. UV absorption kinetic studies show that the Z-form reverses back to B-form to B-form on binding to sanguinarine. Binding isotherms obtained from spectrophotometric data show that sanguinarine binds strongly to the B-form polymer in a non-cooperative manner, in sharp contrast to the highly cooperative interaction under Z-form and HL-form polynucleotides. These studies reveal that the alternating GC sequence undergoes defined conformational changes and interacts with sanguinarine which may be an important aspect in understanding its extensive biological activities.

Structural basis of DNA flexibility.

It has been recently shown by us, on the basis of crystal structure database that the flexibility of B-DNA double helices depends significantly on their base sequence. Our model building studies further indicated that the existence of bifurcated cross-strand hydrogen bonds between successive base pairs is possibly the main factor behind the sequence directed DNA flexibility. These cross-strand hydrogen bonds are, of course, weaker than the usual Watson-Crick hydrogen bonds and their bond geometry is characterized by relatively larger bond lengths and smaller bond angles. We have tried to improve our model structures by incorporating non-planarity of the amino groups in DNA bases due to the presence of lone pair electrons at the nitrogen atoms. Energy minimization studies have been carried out by using different quantum chemical methods, whereby it is found that in all cases of N-H....O type cross-strand hydrogen bonds, the bond geometry improves significantly. In the cases of N-H....N type hydrogen bonds, however, no such consistent improvements can be noticed. Perhaps the true picture would emerge only if all the other interactions present in the DNA macromolecule could be appropriately taken into account.