Gasifier-based power generation: technology and economics

The paper describes a 100 kW power generation system installed at Port Blair, Andaman and Nicobar Islands, under a project sponsored by the Department of Non-Conventional Energy Sources, Government of India. The system consists of a wood gasifier utilising the waste wood from a saw mill and a diesel engine genset. The performance of the total system and its elements are presented along with economics of operation. To bring out the economics of using such renewable energy devices for power generation, some realistic situations are considered for which the effective cost of power and the pay-back period for the investment are evaluated. The economics is compared with that of a similar system of 3.7 kW capacity

Five-kilowatt wood gasifier technology: evolution and field experience

Various elements of an efficient and reliable 5k W wood gasifier system developed over the last ten years are described. The good performance obtained from the system is related to the careful design of its components and sub-systems. Results from extensive testing of gasifier prototypes at two national centres are discussed along with the experience gained in the field from their use at more than one hundred and fifty locations spread over five states in the country. Issues related to acceptance of the technology are also included. Improvements in design to extend the life, to reduce the cost, and to reduce the number of components are also discussed. A few variants of the design to meet the specific requirements of water pumping, power generation and to exploit specific site characteristics are presented

EFFECT OF TOBACCO EXTRACT ON STREPTOCOCCUS MUTANS: POSSIBLE ROLE IN MODULATING CARCINOGENESIS

Objective: Tobacco use in the smoking or smokeless form is the most common form of substance abuse recorded in the world. Not only does tobacco influence carcinogenesis but also modifies the oral microflora. The aim of our study was to assess the growth pattern of Streptococcus mutans under the influence of cigarette extract.Methods: Pure stock culture of S. mutans was grown in brain heart infusion broth mixed with three concentrations of aqueous cigarette extract. Quantification of the S. mutans colonies was performed in Mitis Salivarius Agar subculture. Biofilm assessment was also performed to find the adherent property of microorganisms.Statistical Analysis used: One-way ANOVA was used to compare the effect of cigarette extract on growth and biofilm formation of S. mutans. Results: There was increase in the colony counts with increasing concentration of cigarette extract (p<0.001). There was an observable trend noted in the biofilm assay.Conclusion: The colony growth is positively influenced by the cigarette additives (sugars and sweeteners), carbon dioxide environment, and biofilm modification. The altered flora with higher S. mutans may be linked with the higher salivary acetaldehyde production which promotes carcinogenesis. The flora may be protective by production of antitumorigenic or antimutagenic compounds. The balance between the carcinogenic and anticarcinogenic signals produced by tobacco and microflora influences the outcome of the disease

Promoter analysis by saturation mutagenesis

Gene expression and regulation are mediated by DNA sequences, in most instances, directly upstream to the coding sequences by recruiting transcription factors, regulators, and a RNA polymerase in a spatially defined fashion. Few nucleotides within a promoter make contact with the bound proteins. The minimal set of nucleotides that can recruit a protein factor is called a cis-acting element. This article addresses a powerful mutagenesis strategy that can be employed to define cis-acting elements at a molecular level. Technical details including primer design, saturation mutagenesis, construction of promoter libraries, phenotypic analysis, data analysis, and interpretation are discussed

Design of qos-aware energy-efficient fiber–wireless access networks

Energy-efficient network design has recently become a very important topic because of the energy cost increases in service providers’ infrastructures. This is of particular importance in access networks because of the growing demand for digital traffic by end users. Here we address the challenge of reducing the energy consumption of fiber–wireless (FiWi) access networks, that use both optical and radio frequency technologies to provide high bandwidth and ubiquity for end-user applications, while keeping delay under a threshold. Our goal is to find optimal sleep mode schedulings that allow energy consumption to be reduced while keeping packet delay acceptable. For this purpose a mathematical formalization and an algorithm are developed. The results show that the proposed approach is able to reduce the average packet delay, with negligible energy cost increases, in many scenarios, besides being computationally efficient and scalable. The proposed approach may, therefore, serve as a basis for planning and design of quality of service-aware energy-efficient FiWi access networks.This work was supported by FCT (Foundation for Science and Technology) of Portugal within CEOT (Center for Electronic, Optoelectronic and Telecommunications)