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PublicationArticle Stage- and sex-dependent changes in the lipid profile of Dysdercus koenigii (Heteroptera: Pyrrhocoridae) during development(2004) Archana Mishra; A.K. Singh; Dinesh KumarLipids were extracted from the plasma and gonads of fourth and fifth instars and adults of Dysdercus koenigii (Heteroptera: Pyrrhocoridae). Thin layer chromatography of the extracts revealed fractions of free fatty acids (FFA), monoglycerides (MG), diglycerides (DG), triglycerides (TG), phospholipids (PL), free cholesterol (FC) and esterified cholesterol (EC). There were distinct differences in the lipid profiles within sexes for both tissues during development. Phospholipid from female plasma showed significant fluctuation during development, while that from males remained constant. In female gonads, PL levels increased significantly from the fouth instar to the fifth instar. Monoglycerides were detected only in adult male plasma and adult female gonads, at very low levels. Plasma DG in males was found to increase significantly during development. Maximum gonadal DG was recorded in male fourth instars and female fifth instars. Triglycerides in female plasma declined from the fourth instar to the adult stage. In contrast, TG in gonads increased significantly in the fifth instar of both sexes. Plasma FFA of both sexes fluctuated during development. Free cholesterol was detected only in adult male plasma. Plasma EC increased from the fourth instar to the adult stage in males, and it was highest in gonads of fifth instars of both sexes. © ICIPE 2004.PublicationArticle Influence of chemical reaction on transient natural convective flow in an infinite vertical cylinder packed with porous material(Taylor and Francis Ltd., 2024) Anurag; Anand Kumar; A.K. Singh; Atul JakharA study of mass and heat transport on fully developed laminar and transient free convective flow in a vertical cylinder containing a porous substance inside it. The Laplace Transform Method (LTM) is used to solve the governing equations with suitable boundary conditions. A compact form solution represented by using Bessel and modified Bessel functions. The numerical results were thoroughly scrutinized using graphs and tables to illustrate the effects of newly discovered fluid characteristics, including time, Grashof, mass Grashof, Schmidt, Prandtl, Darcy numbers, viscosity ratio on the concentration and the velocity profiles. The velocity and concentration profiles progressively increase with varying time values until reaching a steady state. Furthermore, it is found that the velocity profiles are decreased by the Prandtl, Schmidt number, and viscosity ratio. In contrast, the Darcy, Grashof, and mass Grashof numbers exhibit an opposite effect. The rate of mass transport, skin friction, and mass flux are presented in tables. The major finding of the current research is that the viscosity ratio parameter decelerates the skin friction and mass flux. This study has potential applications in innovative fields such as solar energy systems, chemical engineering processes, etc. © 2024 Taylor & Francis Group, LLC.PublicationArticle Effect of intense solar flares on TEC variation at low-latitude station Varanasi(Springer, 2020) Abha Singh; S.S. Rao; V.S. Rathore; Sudesh K. Singh; A.K. SinghThe effect of intense solar flares on total electron content (TEC) variability during the declining phase of solar cycle-24 is studied at the low-latitude station at Varanasi, India (Geog. Lat. 25.31° N, Geog. Long. 82.97° E, Geomag. Lat. 16.54° N, Geomag. Long. 157.09° E). In the present paper, we have chosen the intense solar flares that occurred during 9–13 March 2015, 1–2 January 2016, 12–14 February 2016, 6–8 August 2016, and 6–8 September 2017 in the solar cycle-24 period for which the data is available. Our results showed significant enhancements in TEC up to the order of 15 TECU during and after the solar flare events. We have also given a brief account of solar flare effect in TEC with and without geomagnetic disturbances, local time effects (solar zenith angle effects) and changing the location of the solar active region. In a few cases, our results revealed a delay in TEC response during the flare peak time as well as recovery time. © 2020, Indian Academy of Sciences.PublicationArticle Study of heat and mass transport in Bénard-Darcy convection with g-jitter and variable viscosity liquids in a porous layer with internal heat source(Isfahan University of Technology, 2018) A. Srivastava; B.S. Bhadauria; A.K. SinghIn this research article, we investigated the weakly non-linear effect of gravity modulation for the temperature dependent viscous fluid in a horizontal porous layer in the presence of internal heat source. We use power series expansion in terms of the amplitude of gravity modulation, which is considered to be small for double-diffusive convection in porous media. We graphically show the effect of internal heat source, solute Rayleigh number, Lewis number, Vadász number, thermo-rheological parameter, the amplitude of gravity modulation, the frequency of modulation on the heat and mass transfer using Ginzburg-Landau equation. The effect of gravity modulation is found significant and is more effective for the low values of frequency of modulation. © 2018, Isfahan University of Technology.PublicationArticle Weed management in rice (Oryza sativa)-lentil (Lens culinaris) sequence under dryland condition of Varanasi(1994) A.K. Singh; R.A. Singh[No abstract available]PublicationArticle Thermal stability of a layer with permeable boundaries and variable gravitational field(Kluwer Academic Publishers, 1990) A.K. Singh; Mohammad YusufThe aim of this paper is to investigate the thermal stability of a fluid layer with permeable boundaries and a variable gravitational field. It is observed that the principle of exchange of stabilities is valid when the layer is heated form below and the complex growth rate of an arbitrary oscillatory mode exists outside of a circle whose radius depends upon the permeability parameter, Prandtl number and wavelength of the mode. In the case of a layer heated from below, gravity increasing upward has a destabilizing effect whereas the permeability parameter has a stabilizing effect. © 1990 Kluwer Academic Publishers.PublicationArticle Influence of heat and mass transfer on free convection of micropolar fluid between vertical concentric cylinders(Isfahan University of Technology, 2019) A.K. SinghNatural convective flow of a micropolar fluid is examined analytically in order to see the effect of heat and mass transfer between two concentric vertical cylinders of infinite length. The governing equations of model in non-dimensional form corresponding to the temperature, velocity and microrotational velocity, using the Boussinesq approximation and Eringen equation with suitable boundary conditions are expressed in terms of cylindrical coordinate system and then their exact solutions are obtained. The influence of the non-dimensional physical parameters such as the material and vortex viscosity parameters on the velocity, microrotational velocity is evaluated by showing on the graphs while the values of skin friction in non-dimensional form at the outer and inner surfaces of inner and outer cylinders have been presented in the tabular form. © 2019 Journal of Applied Fluid Mechanics.PublicationReview Constipation: A common gut dysmotility problem in the elderly(1999) D.S. Singh; A.K. Singh; A. Mehrotra; I.S. Gambhir[No abstract available]PublicationArticle Transient MHD free convection in a rotating system(Kluwer Academic Publishers, 1989) A.K. Singh; J.N. SinghThe classical Rayleigh problem has been extended to the case of the hydromagnetic free-convective flow of an electrically-conducting and incompressible viscous fluid past an infinite vertical naturally permeable wall in a rotating system. The applied transverse magnetic field is fixed with the moving wall and the magnetic Reynolds number of the flow is taken small so that the induced magnetic field can be neglected in comparison to the applied magnetic field. The permeable wall starts moving from rest in the still fluid and thus arises an initial value problem whose solution has been obtained by the Laplace transform method for two important cases impulsive as well as accelerated start of the plate. Mathematical expression for skin friction components have been also obtained in a closed form. Asymptotic behaviour of the solution is analysed for both the cases, and some interesting particular cases have also been encountered. Influence of various physical parameters occurring into the problem has been discussed with the aid of graphs and tables. © 1989 Kluwer Academic Publishers.PublicationArticle Physicochemical characterization and organoleptic analysis in rice cultivars(Agricultural Research Communication Centre, 2014) Sana Eram; A.K. Singh; Aparajita Singh; N.K. Singh; P.K. SinghA study was conducted during Kharif 2012 to evaluate physicochemical and organoleptic analysis of twenty six rice cultivars. The cultivar IR09F-434 and CR 1009 recorded highest and lowest kernel length, respectively before and after cooking. Mahadikwee recorded highest kernel breadth before and after cooking, while lowest kernel breadth before and after cooking was recorded by Sambha Sub1 and CR 1009, respectively. The 92.30% cultivars were categorized as soft, whereas 88.46% showed high amylose content. The cultivar FR 13A and Madal recorded highest and lowest water uptake ratio, respectively. Low alkali digestion value and high gelatinization temperature were detected in 34.62% cultivars. Cultivar Ausboro showed the presence of strong aroma, while mild aroma was also detected in Dular and Karkati 87. Kernel length/breath ratio showed positive and significant association with kernel length before and after cooking. Organoleptic analysis revealed the cultivars Sambha Sub-1, HUR 38B, Swarna Sub-1, BD-2010 early, BD-2010 late, IR09F-434 and IR09F-436 showed overall very good acceptability, indicating their potential for consumer preferences.