Browsing by Author "V. Srivastava"

Now showing 1 - 10 of 10

Adsorption of cadmium(II) from aqueous solutions by an indigenous clay mineral
(2006) Y.C. Sharma; V. Srivastava
Removal of cadmium, a priority pollutant, has been investigated by a locally available clay mineral, China clay. The removal depends on initial concentration of cadmium in solution and higher removal has been obtained in lower concentration ranges. The removal increased from 41.0 to 80.3% by decreasing the concentration of cadmium in solution from 2.0×10 -4 to 0.5×10-4 M at 6.5 pH, 100 rpm and 0.01 M NaC104 ionic strength. The pH of the solution plays an important role in the removal of cadmium. Rate of the removal was calculated by Lagergren's model and was found to be 5.10×10-2 min-1 in optimum conditions. The process of removal proceeds with intraparticle diffusion and the value of the coefficient of intraparticle diffusion was found to be 3.25×10-10 cm2 s-1. The parameters can be used for designing a plant for treatment of Cd(II) rich water and wastewater economically.
Alumina nanoparticles for the removal of Ni(II) from aqueous solutions
(2008) Y.C. Sharma; V. Srivastava; S.N. Upadhyay; C.H. Weng
Alumina nanoparticles were developed by the sol-gel method and were used for the removal of Ni(II) ions from aqueous solutions. The nanoparticles were characterized by TEM and XRD. Nanoparticles of alumina were then used for removal of Ni(II) ions from aqueous solutions of nickel. The nanosize of the adsorbent was confirmed by TEM and XRD. Removal (%) was found to be dependent on the initial concentration of nickel, and maximum removal was found to be 96.6% at 25 mg/L Ni(II). The removal increased from 99 to 99.6% by decreasing the initial concentration from 75 to 25 mg/L. Equilibrium time was found to be 120 min. As expected, higher removal was obtained at higher adsorbent dose. The removal was governed by first-order kinetics, and the value of the rate constant of adsorption was found to be 1.83 × 10-2 min-1 at 25 mg/L and 25°C. The removal was found to be pH dependent, and maximum removal was found to be at pH 8.0. The adsorption process was endothermic in nature. The experimental data fit well the Langmuir and Freundlich isotherms. Constants of the two isotherm equations were determined. Thermodynamic studies for the present process were performed by determining the values of ΔG̊, ΔH̊, and ΔS̊ at different temperatures. © 2008 American Chemical Society.
Characterisation of carbonaceous materials using Raman spectroscopy: A comparison of carbon nanotube filters, single- And multi-walled nanotubes, graphitised porous carbon and graphite
(John Wiley and Sons Ltd, 2009) H.M. Heise; R. Kuckuk; A.K. Ojha; A. Srivastava; V. Srivastava; B.P. Asthana
Multi-walled carbon nanotube (MWCNT) filters have been recently synthesised which have specific moleeularfiltering capabilities and good mechanical strength. Optical and scanning electron microscopy (SEM) reveals the formation of highly aligned arrays of bundles of carbon nanotubes having lengths up to 500 μm. The Raman spectra of this material along with four other carbonaceous materials, commercially available single-walled carbon nanotubes (SWCNTs) and MWCNTs, graphitised porous carbon (Carbotrap) and graphite have been recorded using two-excitation wavelengths, 532 and 785 nm, and analysed for band positions and shape with special emphasis paid to the D-, G- and G'-bands. A major difference between the different MWCNT varieties analysed is that G-bands in the MWCNT filters exhibit almost no dispersion, whereas the other MWCNTs show a noticeable dispersive behaviour with a change in the excitation wavelength. Spectral features similar to those of the MWCNT filter varieties were observed for the Carbotrap material. From the line shape analysis, the intensity ratio, ID/IG, of the more ordered MWCNT filter material using the integral G-band turns out to be two times lower than that of the less ordered MWCNT filter product at both excitation wavelengths. This parameter can, therefore, be used as a measure of the degree of MWCNT alignment in filter varieties, which is well supported also by our SEM study. Copyright © 2009 John Wiley & Sons, Ltd.
Evaluation of some acylamide derivatives as potential hypoglycemic agents
(1996) V. Srivastava; A.J. Suresh; S.N. Pandeya; A. Pandey
A series of new acylamide derivatives with piperidine, pyrrolidinyl and alanyl have been tested for their hypoglycemic activities. 2-(Pyrrolidinyl)-N-(3-chlorophenyl) acetamide and 2-(Piperazinyl)-N-(4-methoxy phenyl) acetamide were found to be the most active hypoglycemic compounds. Probably the amides have mode of action similar to sulphonylureas.
IAPSM declaration 2018: Definition, role, scope of community medicine and functions of community medicine specialists
(Medknow Publications, 2018) Abraham Joseph; A. Kadri; Anand Krishnan; Bishan Garg; F. Ahmed; Pradeep Kumar; Rajesh Kumar; Ratan Srivastava; V. Srivastava
[No abstract available]
Management of COVID-19: Ayurvedic perspective
(National Institute of Science Communication and Information Resources, 2020) Y.B. Tripathi; N. Joshi; S.K. Dubey; P.S. Byadgi; S. Bhat; R. Prasad; B.K. Dwivedi; K.K. Pandey; J.S. Tripathi; C.S. Pandey; K.H.H.V.S.S.N. Murthy; S. Suman; A.K. Pandey; V. Srivastava; V. Jaisawal; K.N. Dwivedi
Ayurveda, a branch of AYUSH system of health care in India is considered as alternative/complementary of medicine (CAM) in WHO. Here, its products are covered under “drug and cosmetics” act but in abroad they are supplements or functional foods. The aim of Ayurveda is to maintain the wellness of a healthy person and to treat a patient. For treatment, Ayurveda adopts 3 approaches i.e., (1) Daivavyapasharya chikitsa) (ypareht enivid 2 ( Yuktivyapashraya chikitsa (Rational therapy) 3 Satvavajaya chikitsa (Psychotherapy) and focuses to enhance the Vyadhikshmatwa (capacity to fight against spread of pathogenesis by strengthening all 7 dhatus (rasa, rakta, meda, mansa, asthi, majja and shukra). The disease COVID-19 falls under “Bhootvidya (GrahaVidya)", which is one of the 8 branches of “Astanga Ayurveda”. It is an “Agantuja” disease, where the disease symptoms appear in 1st stage followed by its spread in the body. Thus, progress of disease (Samprapti) has been considered under concept of shatkriyakala (6 stages of disease development), which has been given high importance for deciding the stage of disease progress and its treatment protocol. Here, we have described the introduction to Astang Ayurveda, concept of disease pathogenesis and holistic approach of treatment in respect to management of COVID-19. It specifically covers symptom based stage of disease progress and its targeted treatment guideline by including all 3 approaches of treatment, described above. Here, the current line of diagnosis, treatment and research related to COVID-19 management has been included, which are reported by basic scientists and physicians of allopathic system. These are indexed in Pubmed and web of science and also described in classical text books of Ayurveda. The same has been reviewed and summarized here, with an objective of possible correlation between the 2 languages of science of health care. © 2020, National Institute of Science Communication and Information Resources. All rights reserved.
Preparation of isomeric hydrazones : Role of lone electron pair of nitrogen in controlling the stability
(2001) A. Srivastava; V. Srivastava; S.M. Verma; A.K. Saxena
Isomeric hydrazones (E and Z) derived from N-aminoimide of anthracene-maleic anhydride adduct and alkyl aryl ketones have been isolated and characterised by 1H, 13C NMR and IR spectral data. The dissymmetric cage moiety has demonstrated restricted rotation about N-N bond and the ketimino group (R1R2C=N-) in orthogonal geometry to the succinimidyl plane. The electronic interaction of the lone electron pair of ketimino nitrogen with the cage phenyl ring restricts inversion of nitrogen lone pair and provides stability to the stereoisomers. The phenomenon supports the lateral shift mechanism reported for the less enthalpy of activation for E-Z isomerization. Sterically crowded configuration in case of alkyl aryl hydrazones has been found to be thermodynamically more stable as compared to its isomeric product. Conformational energy analysis also suggested the Z-isomer to be the lower energy conformer.
Synthesis of N'-aryl-N3-(substituted)-α,α'-thio-bis-formamidine dihydrochlorides and their effect on blood sugar level of albino rats
(1983) S.N. Pandeya; D.P. Pathak; V. Srivastava
[No abstract available]
Synthesis of some new amidine derivatives as potent hypoglycemic agents
(1985) S.N. Pandeya; V. Srivastava
A series of S-arylformamidino-N-(alkyl/arylisothiourea) Cyclicamino dihydrochlorides were synthesised and screened for their hypoglycemic activity in normal as well as alloxanized diabetic rats. Some of the compounds (Id, Ie, Ih-1) showed more than 30% lowering of blood sugar level of Albino rats. © 1985.
Vagal paraganglioma
(2006) M. Tewari; V. Srivastava; H.S. Shukla
Vagal paragangliomas (VP) arise from paraganglia associated with the vagus nerve. Approximately 200 cases have been reported in the medical literature. The management of VP is associated with partial or total loss of vagal function. We report a case of VP in a young boy who presented with neck mass associated with recurrent laryngeal nerve paralysis. Evaluation of the patient was done by laryngoscope and ultrasound examination of the neck. The paraganglioma was excised along with the vagus nerve with ipsilateral loss of vagal function.