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Search Results: 1 - 10 of 150074 matches for " Upendra K. Singh Shekhawat "
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Petunia Floral Defensins with Unique Prodomains as Novel Candidates for Development of Fusarium Wilt Resistance in Transgenic Banana Plants
Siddhesh B. Ghag, Upendra K. Singh Shekhawat, Thumballi R. Ganapathi
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0039557
Abstract: Antimicrobial peptides are a potent group of defense active molecules that have been utilized in developing resistance against a multitude of plant pathogens. Floral defensins constitute a group of cysteine-rich peptides showing potent growth inhibition of pathogenic filamentous fungi especially Fusarium oxysporum in vitro. Full length genes coding for two Petunia floral defensins, PhDef1 and PhDef2 having unique C- terminal 31 and 27 amino acid long predicted prodomains, were overexpressed in transgenic banana plants using embryogenic cells as explants for Agrobacterium–mediated genetic transformation. High level constitutive expression of these defensins in elite banana cv. Rasthali led to significant resistance against infection of Fusarium oxysporum f. sp. cubense as shown by in vitro and ex vivo bioassay studies. Transgenic banana lines expressing either of the two defensins were clearly less chlorotic and had significantly less infestation and discoloration in the vital corm region of the plant as compared to untransformed controls. Transgenic banana plants expressing high level of full-length PhDef1 and PhDef2 were phenotypically normal and no stunting was observed. In conclusion, our results suggest that high-level constitutive expression of floral defensins having distinctive prodomains is an efficient strategy for development of fungal resistance in economically important fruit crops like banana.
MusaWRKY71 Overexpression in Banana Plants Leads to Altered Abiotic and Biotic Stress Responses
Upendra K. S. Shekhawat, Thumballi R. Ganapathi
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075506
Abstract: WRKY transcription factors are specifically involved in the transcriptional reprogramming following incidence of abiotic or biotic stress on plants. We have previously documented a novel WRKY gene from banana, MusaWRKY71, which was inducible in response to a wide array of abiotic or biotic stress stimuli. The present work details the effects of MusaWRKY71 overexpression in transgenic banana plants. Stable integration and overexpression of MusaWRKY71 in transgenic banana plants was proved by Southern blot analysis and quantitative real time PCR. Transgenic banana plants overexpressing MusaWRKY71 displayed enhanced tolerance towards oxidative and salt stress as indicated by better photosynthesis efficiency (Fv/Fm) and lower membrane damage of the assayed leaves. Further, differential regulation of putative downstream genes of MusaWRKY71 was investigated using real-time RT-PCR expression analysis. Out of a total of 122 genes belonging to WRKY, pathogenesis-related (PR) protein genes, non-expressor of pathogenesis-related genes 1 (NPR1) and chitinase families analyzed, 10 genes (six belonging to WRKY family, three belonging to PR proteins family and one belonging to chitinase family) showed significant differential regulation in MusaWRKY71 overexpressing lines. These results indicate that MusaWRKY71 is an important constituent in the transcriptional reprogramming involved in diverse stress responses in banana.
A Novel Packet Switch Node Architecture for Contention Resolution in Synchronous Optical Packet Switched Networks  [PDF]
Virendra Singh SHEKHAWAT, Dinesh Kumar TYAGI, V. K. CHAUBEY
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.26062
Abstract: Packet contention is a key issue in optical packet switch (OPS) networks and finds a viable solution by including optical buffering techniques incorporating fiber delay lines (FDLs) in the switch architecture. The present paper proposes a novel switch architecture for packet contention resolution in synchronous OPS network employing the packet circulation in FDLs in a synchronized manner. A mathematical model for the proposed switch architecture is developed employing packet queuing control to estimate the blocking probability for the incoming traffic. The switch performance is analyzed with a suitable contention resolution al-gorithm through the computer simulation. The simulation results substantiate the proposed model for the switch architecture.
A quantitative structure-activity relationship study of novel inhibitors of cyclooxygenase-2: The 5-aryl-2,2-dialkyl-4-phenyl-3(2 H)furanone derivatives
Singh P,Shekhawat Manju
Indian Journal of Pharmaceutical Sciences , 2007,
Abstract: The cyclooxygenase-2 enzyme inhibition activity of 5-aryl-2,2-dialkyl-4-phenyl-3(2 H )furanone derivatives is quantitatively analyzed through Fujita-Ban and Hansch type of approaches. The analyses have helped to ascertain the role of different substituents in explaining the observed inhibitory activity of these congeners. From both approaches it is revealed that more hydrophobic susbtituents at 4- R1, a non-hydrogen bond acceptor substitutent, preferably a -F substituent, at 3- R1 in 4-phenyl ring of 3(2 H )furanone scaffold improve inhibitory action of a compound. The substituents exhibiting collective molecular bulk smaller than spirocyclopentyl at X and Y positions are preferred as these geminal positions seems to be involved in steric interation. Similarly, 4-aminosulfonyl in 5-aryl ring of 3(2 H )furanone moiety emerged as a better choice than 4-methylsulfonyl substitution.
CHARACTERIZATION PROFILE OF PLANT MEDIATED BIOGENIC SILVER NANOPARTICLES: AN OVERVIEW
PRITAM SINGH SHEKHAWAT
International Journal of Pharmaceutical Research and Bio-Science , 2013,
Abstract: Nano-biotechnology is at leading edge of research development, making an impact in all spheres of human life. The size of nanoparticles is comparable to that of most of biological molecules (e.g., proteins, DNA) and structures (e.g., viruses and bacteria) therefore; nanoparticles can be developed for diagnostic devices, contrast agents, analytical tools, physical therapy applications, and drug delivery vehicles. This review illustrates possibilities of development of reliable experimental protocols for the bio synthesis of nanomaterial’s using different plant extracts by performing analytical comparisons of characterization techniques like Ultra Violet visible spectroscopy, Scanning Electron Microscope, Transmission Electron Microscope and X-Ray Diffraction. Biological methods of synthesis have paved way for the “greener synthesis” of nanoparticles and these have proven to be better methods due to slower kinetics, being environmentally friendly, less expensive. Also they offer better manipulation and control over stabilization of nanoparticles.
Spontaneous rupture of kidney: a rare presentation of nephrolithiasis
Poras Chaudhary,Sachin Khandelwal,Rana A.K. Singh,Upendra C. Biswal
Clinics and Practice , 2012, DOI: 10.4081/cp.2012.e77
Abstract: Spontaneous rupture of kidney is a rare clinical entity. A 35-year-old female presented in emergency with left flank pain and features suggestive of haemorrhagic shock. Investiga - tions showed rupture of kidney with perinephric haematoma. Emergency left nephrectomy was done. Patient was discharged in satisfactory condition. Nephrolithiasis with secondary bacterial infection rarely presents as spontaneous kidney rupture. In presence of haemorrhagic shock management is emergency surgery.
An integral involving general polynomials and the $H$-function of several complex variables
V. B. L. Chaurasia,Ashok Singh Shekhawat
Tamkang Journal of Mathematics , 2005, DOI: 10.5556/j.tkjm.36.2005.255-260
Abstract: The aim of this paper is to derive an integral pertaining to a product of Fox's $ H $-function [1], general polynomials given by Srivastava [6, p.185, Eq.(7)] and $ H $-function of several complex variables given by Srivastava and Panda [7, p.271, Eq. (4.1)] with general arguments of quadratic nature. The integral thus obtained is believed to be one of the most general integral established so far. The findings of this paper are sufficiently general in nature and are capable of yielding numerous (known or new) results involving classical orthogonal polynomials hitherto scattered in the literature.
Hybrid Cloud Computing in E-Governance: Related Security Risks and Solutions
Hardayal Singh Shekhawat,D.P. Sharma
Research Journal of Information Technology , 2012,
Abstract: This study gives insights on security issues and related solutions in hybrid cloud computing especially in e-governance. Cloud computing is rapidly picking its speed and popularity in Information and Communication Technology (ICT) world. The main factors behind its popularity and universal acceptability are pay per use, rapid elasticity, on demand self service, economical etc. Public cloud services, where all controls remain with the provider are provided by Google.com, Amazon.com, Microsoft, Oracle/Sun, Canonical/Eucalyptus and many other vendors. Private cloud services, where all controls remain in house and software loaded on local servers are provided by VMware, Eucalyptus, Citrix, Microsoft and many other vendors. Governments around the world have adapted or planning to adapt cloud computing as a means to increasing efficiency and reducing cost of their IT infrastructure and services. On the track of successful journey of cloud computing, there are several security issues that can retard its speed during adaptation in government sector. The study and conclusions of this paper is based on review of selected literature confined to security and solutions in current era.
A QSAR STUDY ON PYRAZOLE AND TRIAZOLE DERIVATIVES AS SELECTIVE CANINE COX-2 INHIBITORS
Sharma Brij Kishore,Shekhawat Manju,Singh Prithvi
International Journal of Research in Ayurveda and Pharmacy , 2011,
Abstract: The canine COX-2 inhibitory activity of pyrazole and triazole derivatives has been quantitatively analyzed in terms of Dragon descriptors using CP-MLR. The analysis has provided a rational approach for the development of new pyrazole and triazole derivatives as selective canine COX-2 inhibitors. The descriptors identified in CP-MLR analysis have highlighted the role of atomic properties in respective lags of 2D-autocorrelations (MATS8m, GATS4v and GATS6p) and Modified Burden eigenvalues (BELp2 and BELm6), E-state topological parameter (TIE) and 3rd order mean Galvez topological charge (JGI3) to explain the canine COX-2 inhibitory actions of pyrazole and triazole derivatives. Certain structural fragment (C-001) and functionality (nCs) in molecular structures and 9th order self-returning molecular walk counts have also shown prevalence to optimize the canine COX-2 inhibitory activity of titled compounds. Applicability domain analysis revealed that the suggested model matches the high quality parameters with good fitting power and the capability of assessing external data and all of the compounds was within the applicability domain of the proposed model and were evaluated correctly.
Modeling of Partially Hydrolyzed Polyacrylamide-Hexamine-Hydroquinone Gel System Used for Profile Modification Jobs in the Oil Field
Upendra Singh Yadav,Vikas Mahto
Journal of Petroleum Engineering , 2013, DOI: 10.1155/2013/709248
Abstract: The cross-linked polymer gel systems are being used increasingly to redirect or modify reservoir fluid movement in the vicinity of injection wells for the purpose of permeability/profile modification job in the oil field due to their high temperature stability and capability to provide rigid gel having high mechanical strength. In this study, a partially hydrolyzed polyacrylamide-hexamine-hydroquinonegel is used for the development of polymer gel system. The experimental investigation demonstrates that the gelation time varies with polymer and crosslinker concentration and the temperature. The mathematical model is developed with the help of gelation kinetics of polymer gel and using Arrhenius equation, which relates the gelation time with polymer, crosslinker concentrations, and temperature. The developed model is solved with the help of multivariate regression method. It is observed in this study that the theoretical values of gelation time have good agreement with the experimental values. 1. Introduction The reservoir heterogeneity, permeability variations, and presence of fractures and fracture network in the reservoir are the main hurdles of the water flooding operations used to enhance the oil recovery from matured oil fields. Normally during water flooding, water sweeps through more permeable sections of the reservoir leaving back oil in low permeability channels leading to low oil recovery and early water breakthrough. This excessive water production from the producers leads to rise in handling and disposal costs and reduces the economic life of the well. The polymer gels block or reduce the permeability in high permeability channels and divert the injected water through the low permeability sections, which were not flooded or swept earlier, leading to improvement in oil recovery. This technique is known as profile modification or permeability modification technique and the proper application of this technique is essential for the success of water flooding projects in the oil fields [1–3]. Basically two types of polymers have been used for profile modification jobs. These are polyacrylamides with different degrees of hydrolysis and polysaccharide such as xanthan biopolymer. These are cross linked with inorganic and organic crosslinkers to produce a three-dimensional polymer structure of the gel [4–7]. The inorganic gel system based on the crosslinking of the carboxylate groups on the partially hydrolyzed polyacrylamide chain (PHPA) with a trivalent cation like Cr (III). This crosslinking is believed to rely on coordination covalent bonding. It
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