Reduction of noxious Cr(VI) ion to Cr(III) ion in aqueous solutions using H2O2 and UV/H2O2 systems

M.H. Dehghani,B. Heibati,A. Asadi,I. Tyagi,S. Agarwal,V.K. Gupta 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.33 No.-

Conversion of the toxic Cr(VI) to the less toxic Cr(III) in aqueous solutions by chemical andphotochemical reduction was carried out using H2O2 and UV radiation. The whole mechanism was wellelucidated and investigated using potassium dichromate (K2Cr2O7) as a standard model compound. Theeffects of potential factors affecting the reduction efficiency were well studied and optimized, theoptimized parameters such as concentration of H2O2 (from 0.5 to 1.5 M), pH (from 5 to 9), irradiationtime (0 to 140 min) and reaction time (0 to 120 min). Initial concentration of Cr(VI) in the solution wasvaried from 0.1 to 15 mg/L plays a significant role in the mechanism involves for the reduction of noxiousCr(VI) to less toxic Cr(III).

SENSITIVIY OF A NANOCANTILEVER-BASED MASS SENSOR

K. PRABAKAR,J. JAYAPANDIAN,A. K. TYAGI,C. S. SUNDAR,BALDEV RAJ 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2010 NANO Vol.5 No.1

In the present work, mass and position sensitivity of a nanocantilever is simulated using finite element analysis. Changes in resonant frequency of various modes of a polysilicon cantilever, with a gold coating of different thickness, area, and spatial distribution is simulated. It is found that for a uniform increase in gold coating thickness, torsional mode gives an order higher mass sensitivity than vertical bending and lateral bending modes. In other cases, sensitivity is highly dependent on the position of the coating and is explained on the basis of flexural rigidity. Apart from this, simulations were performed for a point mass (gold cube) loading at various positions along the length and width axis of the cantilever. Further, for localized mass loading, cantilever was tailored for enhanced sensitivity. It is found that by introducing a step discontinuity in thickness of the cantilever, the mass sensitivity increases by two orders of magnitude and it depends on the position of step from free end, step thickness, and step width.

A novel approach for preferential recovery of Sr from (Sr, Th)O₂

Vyas, C.K.,Joshirao, P.M.,Shukla, R.,Tyagi, A.K.,Manchanda, V.K. Elsevier Scientific Pub. Co 2012 Journal of hazardous materials Vol.241 No.-

Quantitative leaching of Sr from homogeneous and calcined (Th,Sr) O<SUB>2</SUB> in dilute perchloric acid medium suggests the possibility of reducing the hazardousness of discharged nuclear fuel by separation of <SUP>90</SUP>Sr, a prominent fission product at dissolution stage itself rather than the conventional approach of its recovery from high level nuclear waste. Apart from mitigating the radiotoxicity of the nuclear waste, recovered <SUP>90</SUP>Sr can be employed as a compact heat source and as parent radionuclide for <SUP>90</SUP>Y (used in therapy radiopharmaceuticals), provided it can be made available at desired high purity. Leaching behavior of few other fission products was also investigated to quantify their contamination in leached Sr. Feasibility of employing extraction chromatography using Sr selective resin was explored in perchloric acid medium. In this context, the distribution coefficients of <SUP>85</SUP>Sr(II), Th (IV), Zr(IV), Y(III), Pd(II) as well as <SUP>152</SUP>Eu(III) and <SUP>137</SUP>Cs (I) were determined under varying nitric acid/perchloric acid concentration and under varying loading conditions of metal ions. Perchloric acid medium appears better than nitric acid medium for preferential leaching of Sr from (Th,Sr)O<SUB>2</SUB> as well as for uptake of Sr by Sr selective chromatographic resin.

Genetic diversity assessment of Indian barley cultivars using RAPD markers

K. Tyagi,S. K. Jaiswal,L. C. Prasad,A. K. Joshi,S. J. Yun 한국작물학회 2008 한국작물학회 학술발표대회 논문집 Vol.2008 No.10

Assessment of the extent of genetic variability within a cultivated crop has important consequences in plant breeding and conservation of genetic resources. Random amplified polymorphic DNA (RAPD) markers were used to produce barley genomic DNA fingerprints. The aim of this work was to investigate the efficacy of polymorphism contained in such fingerprints on disclosing genetic relationships among 26 barley genotypes including advanced lines and released cultivars. Among the 21 primers the percentage of polymorphic bands ranged from 33% (OPG-07) to 83% (OPG-02), showing a high degree of molecular variation. The highest genetic similarity was observed between genotypes Karan-521 and Karan-741(58%), and the lowest genetic similarity was observed between the cultivars Lakhan and C 138 (3.7%). The similarity matrix by the UPGMA algorithm delineated the above genotypes into four major clusters. The results demonstrate the utility of RAPD markers in differentiating Indian barley varieties. KT and SJY were supported by 2008 National Agricultural Germplasm Management System Establishment Program.

Genetic Variation of Drought Tolerance at Early Stage of Plant Growth in Wild Barley (Hordeum vulgare L. ssp. spontaneum) Germplasm

K. Tyagi,M. R. Park,H. J. Lee,C. A. Lee,S. J. Yun 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04

Drought is one of the most important types of abiotic stress that affects stability and amount of yield. This study was conducted to screen for drought tolerance at early seedling stages for 318 ecogeographically diverse wild barley (HordeumvulgareL.spp.spontaneum) diversity collection (WBDC). Considerable variation was observed for all the seedling characters examined. Seedling growth was significantly reduced by 17% polyethyleneglycol -induced osmotic stress with significant variation among accessions. Comparison of mean performance under normal and osmotic stress conditions indicated that shoot length was the most sensitive trait, followed by seedling length, seminal root number, root-shoot length ratio and root length. The mean of root-shoot length ratio, however, increased under osmotic stress. Correlation studies indicated that the root length was the most important trait, followed by shoot length and root-shoot length ratio. The accessions from the Fertile Crescent and North Africa showed more drought tolerance than those from the other geographical regions. The accessions WBDC009 (Jordan), WBDC075 (Libya), WBDC181 (Jordan), WBDC242 (Jordan) and WBDC280 (Israel) exhibited the lowest stress susceptibility index ‘S’ values. Consequently, these accessions showed tolerance to drought at the early seedling stage and are considered to be good sources of drought tolerance for cultivated barley improvement. This work was supported by a grant from Regional Subgenebank Support Program of Rural Development Administration, Republic of Korea .

One Point In situ Incubation Estimation of Undegraded Protein in Forages

Gupta, Neeraj,Tyagi, A.K.,Singhal, K.K. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.11

To estimate undegraded intake protein (UIP) fraction in feeds and fodders, on the basis of their neutral detergent insoluble N content was studied. Samples of six feeds and forages were incubated in situ for a time equivalent to their mean retention time, estimated on the basis of their digestibility plus 10 h (to account for a lag in passage of particles from the rumen). The samples were incubated for 0, 25, 50, 75 and 100% of the estimated total mean retention time. UIP value of leguminous forages, obtained from the fractional rates of degradation and passage, were highly correlated with those estimated from samples incubated for 75% of total mean retention time, while incubating the non-leguminous forages and groundnut cake for this point over estimate the UIP fraction.

Influence of Post-Implantation Annealing Parameters on the Focused Ion Beam Directed Nucleation of InAs Quantum Dots

M. Mehta,D. Reuter,M. Kamruddin,A. K. Tyagi,A. D. Wieck 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.4

We present the effect of post-implantation annealing conditions on the structural and optical quality of InAs quantum dots (QDs) grown by combination of focused ion beam (FIB) and molecular beam epitaxy (MBE) approach. A FIB of Ga+ ion was employed to pattern a homogeneously GaAs buffer layers and then, an in situ annealing step followed by InAs deposition was performed. Three different post-implantation annealing conditions were tested and under well-optimized conditions, a dislocation and defect-free InAs QDs growth on FIB patterned surface was successfully achieved. Furthermore, using photoluminescence (PL) study, we demonstrate that our best sample shows almost similar optical quality as MBE grown QDs on unimplanted GaAs surface. The patterning technique described here can presumably be applied to systems other than InAs/GaAs and highly interesting for site-controlled nucleation of QDs that finds its potential applications in nanooptoelectronic devices.

Pre- and post-breakdown electrical studies in ultrathin Al2O3 films by conductive atomic force microscopy

K. Ganesan,S. Ilango,Mariyappan Shanmugam,M. Farrokh Baroughi,M. Kamruddin,A.K. Tyagi 한국물리학회 2013 Current Applied Physics Vol.13 No.9

The loss of local dielectric integrity in ultrathin Al2O3 films grown by atomic layer deposition is investigated using conducting atomic force microscopy. IeV spectra acquired at different regions of the samples by constant and ramping voltage stress are analyzed for their pre- and post-breakdown signatures. Based on these observations, the thickness dependent dielectric reliability and failure mechanism are discussed. Our results show that remarkable enhancement in breakdown electric field as high as 130 MV/cm is observed for ultrathin films of thickness less than 1 nm.

EXERGETIC ANALYSIS AND ASSESSMENT OF HYBRID REFRIGERATION SYSTEM FOR DAIRY APPLICATIONS

S. ANAND,A. GUPTA,S. K. TYAGI 대한설비공학회 2014 International Journal Of Air-Conditioning and Refr Vol.22 No.4

The application of biogas powered refrigeration system is being studied because of many folds increase in the cost of conventional fuels. This paper presents a numerical study of biogas operated ammonia–water hybrid vapor compression absorption refrigeration system for onsite dairy cooling applications. This system involves the compressor between the generator and condenser and use biogas (generated from the cattle dung) fired boiler to heat water which acts as an energy source for generator in the hybrid system. The variation of performance parameters such as heat load of different components, exergy loss, COPcooling, COPheating and exergy efficiency are studied with varying generator temperature. The results indicate that COPcooling as well COPheating values are in the range of 0.1125–0.2159 and 1.112–1.169, respectively, for the same variation in the generator temperature from 65°C to 130°C. The work done by the compressor is also calculated and found to be decreasing with an increase in the condenser, evaporator and generator temperature. The effect of the ambient temperature on the exergy loss in different components is also studied in the analysis and the results revealed that the maximum exergy loss is found in the generator and it is found to be the lowest in compressor.