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RISS 인기검색어
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- 저자 : Vandna (검색결과 6 건)
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Mishra, Vandna,Parveen, Nazneen,Khan, Nizam U.,Singhal, KC Kyung Hee Oriental Medicine Research Center 2005 Oriental pharmacy and experimental medicine Vol.5 No.2
The effect of alcohol and aqueous extracts of the leaves and stem of Pluchea lanceolata on the spontaneous movements of both the whole worm and the nerve muscle preparation of Setaria cervi, and on the survival of microfilariae in vitro was studied. Alcohol and aqueous extracts of the leaves and stem of P. lanceolata caused the inhibition of spontaneous movements of the whole worm and the nerve muscle preparation of S. cervi, characterized by short lasting small increase in tone and amplitude of contractions followed by paralysis. The concentrations required to inhibit the movements of whole worm and nerve muscle preparations for alcohol extract were 200 and $25\;{\mu}g/ml$, and for aqueous extract were 250 and $100\;{\mu}g/ml$, respectively, suggesting a cuticular permeability barrier. Both the extracts (alcohol and aqueous) caused death of microfilariae in vitro, $LC_{50}$ and $LC_{90}$ being 12 and 18 ng/ml for alcohol extract and 25 and 40 ng/ml for aqueous extract, respectively.
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Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3
Indian geographical populations of D. kikkawai, collected along 20˚N latitudinal range, revealed significant genetic divergence not only of ethanol and acetic acid utilisation but also dessication and starvation tolerance. Latitudinal patterns of ethanol utilization (2.60 to 4.15%) and significantly higher acetic acid utilization (3.50 to 5.25%) were observed in adult individuals of seven geographical populations of D. kikkawai. Very low concentrations (upto 1%) of n-propanol and isopropanol served as resources while secondary alcohols were found to be toxic to D. kikkawai. populations. Thus, the northern and southern populations of D. kikkawai revealed divergence in the patterns of resource utilisation. The parallel occurrence of latitudinal genetic divergence for ethanol and acetic acid utilisation and for propanols in Indian populations of D. kikkawai could be maintained by balancing natural selection varying spatially along the north-south axis of the Indian subcontinent. The observed genetic differentiation in desiccation(17 to 26 hrs) as well as starvation tolerance (92 to 129 hrs) in D. kikkawai populations suggest the role of climatic selection along the latitudinal transect.
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Utilisation of Alcoholic Resources in Five Colonising Drosophilids from Himachal Pradesh , India
Parkash, Ravi,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3
Drosophila melanogaster, Zaprionus indianus and D. repleta revealed significantly higher ethanol and acetic acid tolerance levels as compared with D. kikkawai and D. immigrans. The parallel patterns of utilisation of other primary and secondary alcohols seem to be correlated with the concentrations of these metabolites found in natural food resources. The longevity effects of n-butanol (0.4 to 1.5%) were found to be significantly high in all the five drosophilids as compared to 2-butanol. The interspecific differences for resource utilisation are in agreement with niche-width hypothesis and seem to be adaptively maintained by natural selection mechanisms.
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Allozyme Phylogeny of Five Species of Takahashii Species Subgroup of Drosophilla
Parkash, Ravi,Jyoutsna,Vandna 한국유전학회 1994 Genes & Genomics Vol.16 No.3
Allozymic variations at eight polymorphic loci in five species belonging to takahashii species subgroup were analysed through horizontal starch gel electrophoresis. Phylogenetic relationships based on NEI's as well as NAIR's indices revealed two main lineages. In one of the lineage, D. paralutea and D. prostipennis constitute one group while other main lineage includes two closely related species i. e. D. takahashii and D. lutescens and one distantly related species i. e. D. nepalensis. Thus, observed phylogenetic relationships based on allozymic data concur with the interrelation based on interspecific hybridization tests. The extent of observed allozymic divergence among five specis of takahashii subgroup seem to be correlated with their allopatric and endemic geographical distribution pattern throughout the oriental region.
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Functionalization of polyethylene by graft copolymerization for separation processes
Kaur, Inderjeet,Gupta, Nitika,Kumari, Vandna Techno-Press 2013 Advances in materials research Vol.2 No.1
Incorporation of polar functional moieties into polyethylene (PE) film has been achieved by graft copolymerization of polar monomers such as methacrylic acid (MAAc) and acrylamide (AAm) on to PE film, preirradiated with ${\gamma}$-rays from $^{60}Co$ source, using benzoyl peroxide (BPO) as initiator in aqueous medium. Percentage of grafting of MAAc and AAm was determined as a function of irradiation dose, monomer and initiator concentration, temperature, reaction time and amount of water. Maximum percentage of grafting of MAAc (1453%) and AAm (21.28%) was obtained at [MAAc] = $235.3{\times}10^{-2}$ mol/L, [AAm] = $23.4{\times}10^{-2}$ mol/L, [BPO] = $5.5{\times}10^{-2}$ mol/L and $16.5{\times}10^{-2}$ mol/L at $80^{\circ}C$, $90^{\circ}C$ in 180 min and 90 min respectively. The grafted PE films were characterized by FTIR, Thermogravimetric analysis (TGA) Scanning Electron Micrography (SEM) and X-ray diffraction methods. Some selective properties of grafted films such as swelling behavior, ion and metal uptake have been carried out. The biodegradation studies of the grafted PE films have also been investigated. The grafted films developed superior swelling behavior with maximum swelling (480%) in water as compared to pristine PE (13.55%), better thermal stability and ion and metal uptake studies showed promising results that can be effectively used for desalination of brackish water and separation of metals from the industrial effluents.
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Elucidating iron doping induced n- to p- characteristics of Strontium titanate based ethanol sensors
Neha Sarin,Monu Mishra,Govind Gupta,Ivan P. Parkin,Vandna Luthra 한국물리학회 2018 Current Applied Physics Vol.18 No.2
A series of pure and iron doped strontium titanate, (SrFexTi1-xO3; x = 0, 0.1 and 0.2) powders were synthesized, characterized and used to fabricate ethanol sensors for low concentration. X-Ray Diffraction (XRD) technique was used to confirm the single phase formation. Microstructural properties of the powders were investigated using scanning electron microscopy (SEM). Electrical conductivity of all the samples at room temperature (RT) was measured. Sensors were optimized for best responsiveness by varying the operating temperature from 350 °C to 500 °C.The sensor with doping x = 0.2 exhibited best sensing response at 400 °C for ethanol gas. The undoped sensor demonstrated a decrease in resistance on exposure to ethanol gas whereas Fe-doped sensors showed increase in resistance. The doping induced changeover from n to p behavior in the sensing response on doping has been investigated and corroborated with an observed shift in the Fermi level position by X-ray photoelectron spectroscopy (XPS). The disparity in gas sensing response clearly demonstrates inter-connection of multiple influencing factors such as electrical conductivity, morphology, porosity and change in chemical composition on doping. The sensors were exposed to ethanol, nitrogen dioxide, carbon monoxide, butane gases at concentration between 5 ppm and 50 ppm. The sensor exhibited much reduced relative response to all gases other than ethanol which can be utilized for wide range of applications.
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