Browsing by Author "D.B. Singh"
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PublicationArticle Adsorption technique for the treatment of As(V)-rich effluents(Elsevier Science B.V., 1996) D.B. Singh; G. Prasad; D.C. RupainwarUnconventional adsorbents like hematite and feldspar have been employed for the removal of AS(V) from aqueous system. The effect of important parameters like solute concentration, detention time, pH, temperature, agitation rate and particle size of the adsorbent has been addressed. The process of uptake follows first-order kinetics and the data fit the Langmuir isotherm. Mass-transfer coefficients and diffusion coefficients have also been determined to study the dynamics of transport. The pH of the system has been found to play a key role in the uptake. The maximum removal was found to be 100% with hematite and 97% with feldspar under optimum conditions at 13.35 μmol L-1 arsenic concentration. The data were subjected to multiple-regression analysis and a model has been developed to predict the uptake capacity of the adsorbents under given boundary conditions.; Unconventional adsorbents like hematite and feldspar have been employed for the removal of AS(V) from aqueous system. The effect of important parameters like solute concentration, detention time, pH, temperature, agitation rate and particle size of the adsorbent has been addressed. The process of uptake follows first-order kinetics and the data fit the Langmuir isotherm. Mass-transfer coefficients and diffusion coefficients have also been determined to study the dynamics of transport. The pH of the system has been found to play a key role in the uptake. The maximum removal was found to be 100% with hematite and 97% with feldspar under optimum conditions at 13.35 μmol L-1 arsenic concentration. The data were subjected to multiple-regression analysis and a model has been developed to predict the uptake capacity of the adsorbents under given boundary conditions.PublicationArticle Colony interactions and mycoparasitism between Acremonium furcatum and Aspergillus spp.(Martinus Nijhoff/Dr. W. Junk Publishers, 1981) Atul K. Srivastava; D.B. Singh; Bharat RaiColony interactions and mycoparasitism between Acremonium furcatum and ten species of Aspergillus were studied in dual cultures. It was observed that A. furcatum overgrew the colonies of all the ten species of Aspergillus studied. During the mycoparasitic interactions frequent coiling, penetration and growth of hyphae of A. furcatum inside the conidiophores of six species of Aspergillus were observed. © 1981 Martinus Nijhoff/Dr W. Junk Publishers.PublicationArticle Trichoderma viride as a mycoparasite of Aspergillus spp.(Martinus Nijhoff, The Hague/Kluwer Academic Publishers, 1980) Bharat Rai; V.N. Singh; D.B. SinghTrichoderma viride was found to be parasitic on three species of Aspergillus. The mycoparasitism was characterized by frequent coiling, penetration and hyphal growth of the parasite inside the conidiophores of Aspergillus. The volatile and non-volatile metabolites of T. viride, more or less, inhibited radial growth of all the test Aspergillus spp. © 1980 Martinus Nijhoff Publishers.PublicationArticle Unattenuated global modes in a planar dielectric waveguide with a flare in the direction of propagation(John Wiley & Sons Inc, 1998) D.B. Singh; P. Khastgir; U.K. Singh; O.N. SinghIn this paper, continuing our earlier work on the modal properties of a planar waveguide with a flare, we examine whether unattenuated guided modes can exist in such waveguides. We use the scalar wave approximation and the cylindrical polar coordinates (ρ, φ, z) in a new way. Ordinarily, the guiding region lies between two distinct values of ρ, and the propagation is along the z-axis. In our case, however, we take the propagation in the ρ-direction, and the guiding region is bounded by two planes corresponding to two slightly different values of φ. This represents a planar waveguide with a flare, and we obtain the modal characteristic equation for unattenuated modes. Numerical computation shows the surprising result that global unattenuated modes can be sustained in such a structure for ν = 0, where ν is the modal index corresponding to the φ-coordinate.PublicationArticle Volatile and non-volatile metabolites of actinomycetes and the growth of some litter decomposing fungi(1981) Bharat Rai; Atul K. Srivastava; D.B. Singh[No abstract available]