R.K. Sahu

Bio: R.K. Sahu is an academic researcher from Jawaharlal Nehru Agricultural University. The author has contributed to research in topics: Medicine & Runoff curve number. The author has an hindex of 12, co-authored 30 publications receiving 627 citations. Previous affiliations of R.K. Sahu include Rajendra Agricultural University & Indian Institute of Technology Bombay.

A Review on Biosurfactants: Fermentation, Current Developments and Perspectives

Abstract: Surfactants are compounds that reduce the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid. Surfactants are characteristically organic compounds containing both hydrophobic groups (their tails) and hydrophilic groups (their heads). Therefore, a surfactant molecule contains both a water insoluble (and oil soluble component) and a water soluble component. Biosurfactants encompass the properties of dropping surface tension, stabilizing emulsions, promoting foaming and are usually non-toxic and biodegradable. Interest in microbial surfactants has been progressively escalating in recent years due to their diversity, environmentally friendly nature, possibility of large-scale production, selectivity, performance under intense circumstances and their impending applications in environmental fortification. These molecules have a potential to be used in a variety of industries like cosmetics, pharmaceuticals, humectants, food preservatives and detergents. Presently the production of biosurfactants is highly expensive due to the use of synthetic culture media. Therefore, greater emphasis is being laid on procurement of various cheap agro-industrial substrates including vegetable oils, distillery and dairy wastes, soya molasses, animal fat, waste and starchy waste as raw materials. These wastes can be used as substrates for large-scale production of biosurfactants with advanced technology which is the matter of future research. This review article represents an exhaustive evaluation of the raw materials, with respect to their commercial production, fermentation mechanisms, current developments and future perspectives of a variety of approaches of biosurfactant production.

An Improved I a S Relation Incorporating Antecedent Moisture in SCS-CN Methodology

Abstract: Employing a large dataset of 84 small watersheds (area = 0.17 to 71.99 ha) of U.S.A., this paper investigates a number of initial abstraction (Ia)-potential maximum retention (S) relations incorporating antecedent moisture (M) as a function of antecedent precipitation (P5), and finally suggests an improved relation for use in the popular Soil Conservation Service Curve Number (SCS-CN) methodology for determination of direct runoff from given rainfall. The improved performance of the incorporated M = α \(sqrt{P_5S}\) and Ia = λ S2/(S + M) relations, where λ is the initial abstraction coefficient, in the SCS-CN methodology exhibits the dependence of Ia on M, which is close to reality; the larger the M, the lesser will be Ia, and vice versa. Such incorporation obviates sudden jumps in the curve number variation with antecedent moisture condition, an unreasonable and undesirable feature of the existing SCS-CN model.

An advanced soil moisture accounting procedure for SCS curve number method

Abstract: The Soil Conservation Service Curve Number (SCS-CN) method has been a topic of much discussion, especially in the last three decades. Recently, Michel et al. (2005) pointed out several inconsistencies in the soil moisture accounting (SMA) procedure used in the SCS-CN method and developed a procedure that is more consistent from the SMA viewpoint. However, the model proposed by them does not have any expression for initial soil moisture store level (V0) and hence there is a scope for further improvement. Like the original method, there is sudden jump in V0 and therefore a quantum jump in computed runoff is possible. In the present study, an attempt is made to develop an expression for V0 to make the model a continuous watershed model. Then, the performance of the new model is compared with the model proposed by Michel et al. and the original SCS-CN model by applying them in a large number of small watersheds in the United States. The present model was found to perform significantly better than both the original SCS-CN model and the model proposed by Michel et al. Copyright © 2007 John Wiley & Sons, Ltd.

An improved AMC-coupled runoff curve number model

Abstract: In the Soil Conservation Service Curve Number (SCS-CN) method, the three levels of antecedent moisture condition (AMC) permit unreasonable sudden jumps in curve numbers, which result into corresponding jumps in the estimated runoff. A few recently developed SCS-CN-based models obviate this problem, yet they have several limitations. In this study, such a model incorporating a continuous function for antecedent moisture has been presented. It has several advantages over the other existing SCS-CN-based models. Its application to a large dataset from US watersheds showed to perform better than the existing SCS-CN method and the others based on it. Copyright © 2010 John Wiley & Sons, Ltd.

Comparing farmers and breeders rankings in varietal selection for low-input environments: A case study of rainfed rice in eastern India

Abstract: A number of breeding institutions developed a project to assess importance of participatory plant breeding approaches for rainfed rice improvement in eastern India. The results of the first two years of participatory varietal selection are reported here. The objective was to evaluate the respective effects of participation of farmers in varietal evaluation and decentralization of varietal testing from breeding stations to farmers' fields on varietal ranking. Fields representing various hydrological situations were chosen in two to three villages at four rainfed lowland sites and one upland site. Sets of 15 to 25 varieties were tested both in farmers' fields and on-station in 1997 and 1998 and ranked by both farmers and breeders. The effect of participation was judged by comparing the rankings attributed by farmers and breeders to a given set of material in a given trial. The effect of decentralization was determined through comparisons between individual breeders' rankings across trials. Farmers' rankings were not randomly allocated, but agreement within the farmers' group was not always very strong. Except at one site, concordance among breeders' ranking was high, but, because of the limited number of breeders involved, it was seldom significant. In about two-thirds of the trials, there was a good agreement between farmers' and breeders' mean rankings. The consensus was particularly strong when severe constraints induced contrasting behavior in the genotypes. The decentralization effect appeared to be moderate, but variations due to a breeder effect were recorded. The part of genotype by environment interactions for grain yield due to location within one site and year was evaluated through various methods, showing more effect of G × E interactions at some sites than at others. Crossover interactions inducing changes in ranks represented a limited part of the yearly G × E interactions at all sites. Both farmer participation and decentralization of varietal testing in farmers' field would help in best matching the varieties to the needs, although their combined contribution would be more useful in some sites than in others.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Accounting for water use and productivity

Abstract: This paper presents a conceptual framework for water accounting and provides generic terminologies and procedures to describe the status of water resource use and consequences of water resources related actions. The framework applies to water resource use at three levels of analysis: a use level such as an irrigated field or household, a service level such as an irrigation or water supply system, and a water basin level that may include several uses. Water accounting terminology and performance indicators are developed and presented with examples at all the three levels. Concepts and terminologies presented are developed to be supportive in a number of activities including: identification of opportunities for water savings and increasing water productivity; developing a better understanding of present patterns of water use and impacts of interventions; improving communication among professionals and communication to non-water professionals; and improving the rationale for allocation of water among uses. It is expected that with further application, these water accounting concepts will evolve into a robust, supporting methodology for water basin analysis.

Water Accounting to Assess Use and Productivity of Water

Abstract: A methodology is demonstrated to account for the use and productivity of water resources. This water accounting methodology presents useful information to water resource stakeholders and decision makers to better understand the present use of water and to formulate actions for improvements in integrated water resources management systems. Based on a water balance approach, it classifies outflows from a water balance domain into various categories to provide information on the quantity of water depleted by various uses, and the amount available for further use. The methodology is applicable to different levels of analysis ranging from a micro level such as a household, to a macro level such as a complete water basin. Indicators are defined to give information on the productivity of the water resource. Examples from Egypt's Nile River and a cascade of tanks in Sri Lanka are presented to demonstrate the methodology.

Cost effective technologies and renewable substrates for biosurfactants' production.

Abstract: Diverse types of microbial surface-active amphiphilic molecules are produced by a range of microbial communities. The extraordinary properties of biosurfactant / bioemulsifier (BS/BE) as surface active products allows them to have key roles in various field of applications such as bioremediation, biodegradation, enhanced oil recovery, pharmaceutics, food processing among many others. This leads to a vast number of potential applications of these BS/BE in different industrial sectors. Despite the huge number of reports and patents describing BS and BE applications and advantages, commercialization of these compounds remain difficult, costly and to a large extent irregular. This is mainly due to the usage of chemically synthesized media for growing producing microorganism and in turn the production of preferred quality products. It is important to note that although a number of developments have taken place in the field of biosurfactant industries, large scale production remains economically challenging for many types of these products. This is mainly due to the huge monetary difference between the investment and achievable productivity from the commercial point of view. This review discusses low cost, renewable raw substrates and fermentation technology in BS/BE production processes and their role in reducing the production cost.