Design and Development of Mechanical Solar Tracking System

In recent years, the growing global interest in the conservation of environment has provided a fresh motivation for research in the area of solar energy utilization. Already, installation of solar energy extraction devices such as solar panels, solar water heaters, solar cookers etc. is becoming popular in urban buildings. Most of these devices consist of a solar receptor that is kept facing the sun during the day, but the sun moves from east to west and the efficiency of the panel decreases. If one could trap this extra energy source then the efficiency of the solar panel would be increased. A tracking mechanism following the sun would achieve this aim. An attempt has been made to develop a simple yet efficient sun tracking mechanism using a motor, a speed reduction mechanism and real timer. The mechanism has been designed such that the sunrays falling on the panel are always perpendicular to the panel resulting in increase in efficiency of the electricity generation. This report presents, in detail, the design and construction adopted to develop the functional model that was fabricated and tested for performance which yielded the efficiency increase of 28.41% as compared to the conventional stationary panel position

Characterization of the Escherichia coli pyridoxal 5'-phosphate homeostasis protein (YggS): Role of lysine residues in PLP binding and protein stability

The pyridoxal 5'-phosphate (PLP) homeostasis protein (PLPHP) is a ubiquitous member of the COG0325 family with apparently no catalytic activity. Although the actual cellular role of this protein is unknown, it has been observed that mutations of the PLPHP encoding gene affect the activity of PLP-dependent enzymes, B6 vitamers and amino acid levels. Here we report a detailed characterization of the Escherichia coli ortholog of PLPHP (YggS) with respect to its PLP binding and transfer properties, stability, and structure. YggS binds PLP very tightly and is able to slowly transfer it to a model PLP-dependent enzyme, serine hydroxymethyltransferase. PLP binding to YggS elicits a conformational/flexibility change in the protein structure that is detectable in solution but not in crystals. We serendipitously discovered that the K36A variant of YggS, affecting the lysine residue that binds PLP at the active site, is able to bind PLP covalently. This observation led us to recognize that a number of lysine residues, located at the entrance of the active site, can replace Lys36 in its PLP binding role. These lysines form a cluster of charged residues that affect protein stability and conformation, playing an important role in PLP binding and possibly in YggS function

Bacterial laccases: some recent advances and applications

Laccases belong to the large family of multi-copper oxidases (MCOs) that couple the one-electron oxidation of substrates with the four-electron reduction of molecular oxygen to water. Because of their high relative non-specific oxidation capacity particularly on phenols and aromatic amines as well as the lack of requirement for expensive organic cofactors, they have found application in a large number of biotechnological fields. The vast majority of studies and applications were performed using fungal laccases, but bacterial laccases show interesting properties such as optimal temperature above 50 °C, optimal pH at the neutral to alkaline range, thermal and chemical stability and increased salt tolerance. Additionally, bacterial systems benefit from a wide range of molecular biology tools that facilitates their engineering and achievement of high yields of protein production and set-up of cost-effective bioprocesses. In this review we will provide up-to-date information on the distribution and putative physiological role of bacterial laccases and highlight their distinctive structural and biochemical properties, discuss the key role of copper in the biochemical properties, discuss thermostability determinants and, finally, review biotechnological applications with a focus on catalytic mechanisms on phenolics and aromatic amines.info:eu-repo/semantics/publishedVersio

Use of aromatic polyamide membranes in desalination

173-177Piperazine containing polymers, having no 'H' atom at amide nitrogen have been prepared from diaminobenzanilides and diacid chlorides by low temperature polycondensation method. These polymers have been characterised by inherent viscosity, percent moisture regain, solubility, IR and thermal analysis. Amount of chlorine absorbed by the polyamides has been calculated by titrating polymer suspension with sodium thiosulphate. Membranes were cast from the polymer solution in dimethyl acetamide containing lithium chloride as an additive. These membranes' were studied for reverse osmosis (RO) performance in salt water with and without chlorine containing medium.</span