Drinking water contamination in Calcutta

The following paper summarizes the results of a study on drinking water contamination in Calcutta undertaken since November 1999 which is still going on at the time of writing and which mainly deals with • the bacteriological and chemical quality of Calcutta’s drinking water and • public awareness with regard to related issues

Performance of Al-si-glass fiber composite piston in an IC Engine

The piston is one of the major part of the automobile. The piston purpose is to transfer force from expanding gas in the cylinder to the crankshaft. The piston acts as the vital link between the generation of power inside the combustion chamber to its transfer to the crankshaft and converting to-and-fro motion into continuous rotary motion. The piston assembly is probably subjected to the widest range of mechanical and thermal stresses. Now a days we using aluminium material for the piston because it having low density, high thermal conductivity and high corrosive resistant when compare to cast iron. One of the major problem in aluminium piston is piston slap. It occurs due to high thermal expansion of the aluminium material so providing more gap between the cylinder and the piston. The thermal expansion coefficient of the aluminium is hardly two to three time higher than the cast iron material. For reducing the thermal expansion coefficient of the aluminium material by adding the composite material which having low thermal expansion coefficient without decreasing the hardness of the material. The glass fiber material having theCoefficient of Expansion in inches of expansion per inch of material per degree Fahrenheit is “2.2â€. The aluminium and the glass fiber melting point are nearly same so it can be easily mixed with each other. By adding the glass fiber to aluminium piston it will increase the thermal and mechanical property of the piston

Severe historical floods on the river Roda, Thuringia: from reconstruction to implications for flood management

Using the Roda river (Thuringia) as an example, we present methods for and results of historical flood research in Germany. The Roda river is one of the tributaries of the Saale river with a length of approximately 33 km. Although the watershed only covers around 262 km², the Roda is very vulnerable to flooding. The river caused damages of catastrophic dimensions within the urban area of Stadtroda (until 1925 “Roda”). These damages were especially devastating after heavy rainfall events during the late spring and early summer seasons of June 1582, April 1654, June 1827, June 1871 and June 1876. This article discusses how the flood history of the Roda river and human response to the associated natural hazards can be analysed by a combination of archive and field work. By means of the available material (e.g. printed, handwritten and physical sources as well as maps, engravings and historical photos), the history of severe floods was reconstructed for several centuries. This specifically refers to 1) the genesis, magnitude, frequency and length of floods, 2) the extent of damages and losses, 3) the risk perception and evaluation by municipal and national administrations and 4) the planning and implementation of protective measures and their impacts. Interestingly, the analysis of the disastrous floods of 1871 and 1876 shows striking similarities to the current discussion (e.g. regarding the influence of land use changes). Furthermore, the combined historical accounts are an important basis for the derivation of future flood risk assessments for the Roda river. Going beyond the specific basin of the Roda, the findings also reveal important insights regarding the impacts of increases in heavy regionalized rainfall for small watersheds, which is predicted to occur more frequently in such watersheds in the state of Thuringia

Environmental Education through Fieldwork

In a project jointly organized by a German high school and the local university’s Department of Geography, students together with their teachers and scientists investigated the usage and state of water bodies in their home town (Göttingen, Germany). The environmental education impact of the project was evaluated by conducting written learner interviews prior to the project, immediately following the project work and 6 months after its completion. These were complemented by oral interviews of both the organizing scientists and teachers. Results of the evaluation revealed an increase in environmental knowledge and a sensibilization of the students for water-related environmental issues. The substantial raise in environmental awareness was only partly reflected by a modification of attitudes and willingness to act more eco-friendly. Nevertheless, it was demonstrated that a project involving scientific fieldwork can have an influence on students’ environmental science literacy and attitude.Peer Reviewe

A “dock, lock, and latch” Structural Model for a Staphylococcal Adhesin Binding to Fibrinogen

AbstractGram-positive pathogens such as staphylococci contain multiple cell wall-anchored proteins that serve as an interface between the microbe and its environment. Some of these proteins act as adhesins and mediate bacterial attachment to host tissues. SdrG is a cell wall-anchored adhesin from Staphylococcus epidermidis that binds to the Bβ chain of human fibrinogen (Fg) and is necessary and sufficient for bacterial attachment to Fg-coated biomaterials. Here, we present the crystal structures of the ligand binding region of SdrG as an apoprotein and in complex with a synthetic peptide analogous to its binding site in Fg. Analysis of the crystal structures, along with mutational studies of both the protein and of the peptide, reveals that SdrG binds to its ligand with a dynamic “dock, lock, and latch” mechanism. We propose that this mechanism represents a general mode of ligand binding for structurally related cell wall-anchored proteins of gram-positive bacteria

There is more to accommodation of the eye than simply minimizing retinal blur.

Eyes of children and young adults change their optical power to focus nearby objects at the retina. But does accommodation function by trial and error to minimize blur and maximize contrast as is generally accepted? Three experiments in monocular and monochromatic vision were performed under two conditions while aberrations were being corrected. In the first condition, feedback was available to the eye from both optical vergence and optical blur. In the second, feedback was only available from target blur. Accommodation was less precise for the second condition, suggesting that it is more than a trial-and-error function. Optical vergence itself seems to be an important cue for accommodation