Investigation of a.c. conductivity measurements in a-Se80Te20 and a-Se80Te10M10 (M = Cd, in, Sb) alloys using correlated barrier hopping model

N. Chandel,N. Mehta,A. Kumar 한국물리학회 2012 Current Applied Physics Vol.12 No.2

The a.c. conductivity of a-Se80Te20 and a-Se80Te10M10 (M ¼ Cd, In, Sb) alloys has been investigated as a function of temperature in the range from 280 to 330 K and frequency in the range from 102 to 104 Hz. The experimental results indicate that a.c. conductivity sac is proportional to us where s < 1 and decreases with increasing temperature. The results obtained are discussed in terms of the correlated barrier hopping (CBH) model. An agreement between experimental and theoretical results suggests that the a.c. conductivity behavior of a-Se80Te20 and a-Se80Te10M10 (M ¼ Cd, In, Sb) system can be successfully explained by CBH model. The contribution of single polaron and bipolaron hopping to a.c. conductivity in present alloys is also studied. The a.c. conductivity of a-Se80Te20 and a-Se80Te10M10 (M ¼ Cd, In, Sb) alloys has been investigated as a function of temperature in the range from 280 to 330 K and frequency in the range from 102 to 104 Hz. The experimental results indicate that a.c. conductivity sac is proportional to us where s < 1 and decreases with increasing temperature. The results obtained are discussed in terms of the correlated barrier hopping (CBH) model. An agreement between experimental and theoretical results suggests that the a.c. conductivity behavior of a-Se80Te20 and a-Se80Te10M10 (M ¼ Cd, In, Sb) system can be successfully explained by CBH model. The contribution of single polaron and bipolaron hopping to a.c. conductivity in present alloys is also studied.

Radioprotective Role of Amaranthus gangeticus Linn.: A Biochemical Study on Mouse Brain

A.L. Bhatia,Rajesh Kumar Verma,R. Sisodia 한국식품영양과학회 2002 Journal of medicinal food Vol.5 No.4

Brain tissue is highly susceptible to oxidative damage due to its high utilization of oxygenand its poorly developed antioxidative defense mechanisms. Radiation or pro-oxidants in-teract with cells and tissues through secondary ionization mechanisms such as lipid pero-xidation (LPO). LPO can be inhibited by antioxidants such as vitamins A, C, and E and the carotenoid b-carotene. b-Carotene, the provitamin A, plays an important radioprotectiverole due to its properties as a potent fre radical scavenger, singlet oxygen quencher, and lipidantioxidant. Amaranthus gangeticus Linn., widely considered as a wed, has a high contentof carotene, ascorbic acid, and folate and may prove an efficient antioxidant. To evaluate theantioxidative efficacy of Amaranthus, healthy Swiss albino mice from an inbred colony weretreated with alcoholic extract of A. gangeticus leaves (AE) for 2 weks, at 80 mg/kg bodyweight, before radiation exposure. Irradiated mice were examined and autopsied at intervalsof 1, 3, 7, 15, and 30 days after exposure. Brain was removed by skull dissection, and variousbiochemical changes were sought. Radiation caused a maximum increase of 27% in LPO anda maximum decrease of 27.96% in protein content at day 7 in controls. However, in the ex-perimental group the increase in LPO was 9.98% and the increase in protein content was18.78% at day 7. By day 30 after irradiation, AE brought these values to near-normal levels.AE protected brain biochemical activity in this murine study and may prove beneficial forclinical use as a radioprotector.189

Synthesis of Tetrazolo[1,5-a]quinoxaline based Azetidinones & Thiazolidinones as Potent Antibacterial & Antifungal Agents

Kumar, Shiv,Khan, S.A.,Alam, Ozair,Azim, Rizwan,Khurana, Atul,Shaquiquzzaman, M.,Siddiqui, Nadeem,Ahsan, Waquar Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.7

4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff's bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff's bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of $^1H$-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.

FEM buckling analysis of quasi-isotropic symmetrically laminated rectangular composite plates with a square/rectangular cutout

A. Lakshmi Narayana,Krishnamohana Rao,R. Vijaya Kumar 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

A numerical study was conducted using the finite element method to determine the effects of square and rectangular cutouts on the buckling behavior of a 16-ply quasi-isotropic graphite/epoxy symmetrically laminated rectangular composite plate. The square/ rectangular cutouts were subjected to uniaxial compression loading. This study addresses the effects of the size of the square/rectangular cutout,orientation of the square/rectangular cutout, plate aspect ratio (a/b), and plate length/thickness ratio (a/t) on the buckling behavior of the symmetrically laminated rectangular composite plate under uniaxial compression loading. Buckling loads were computed for seven different quasi-isotropic laminate configurations [0°/+45°/-45°/90°]2s, [15°/+60°/-30°/-75°]2s, [30°/+75°/-15°/-60°]2s, [45°/+90°/0°/-45°]2s,[60°/-75°/+15°/-30°]2s, [75°/-60°/+30°/-15°]2s, [90°/-45°/+45/°0°]2s. Results showed that the magnitudes of the buckling loads decrease with increasing cutout positioned angle as well as c/b and d/b ratios for plates with a rectangular cutout. The symmetrically laminated quasi-isotropic [0°/+45°/-45°/90°]2s composite plate is stronger than all other symmetrically analyzed laminated quasi-isotropic composite plates. The magnitudes of the buckling loads of a rectangular composite plate with square/rectangular cutout decrease with increasing plate aspect ratio (a/b) and plate length/thickness (a/t) ratio.

Synthesis of Tetrazolo[1,5-a]quinoxaline based Azetidinones & Thiazolidinones as Potent Antibacterial & Antifungal Agents

Shiv Kumar,S. A. Khan,Ozair Alam,Rizwan Azim,Atul Khurana,M. Shaquiquzzaman,Nadeem Siddiqui,Waquar Ahsan 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.7

4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff’s bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff’s bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of ^1H-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.

Enantioseparation on cellulose dimethylphenylcarbamate-modified zirconia monolithic columns by reversed-phase capillary electrochromatography

Kumar, A.P.,Park, J.H. Elsevier 2010 Journal of chromatography Vol.1217 No.26

This work reports the preparation of monolithic zirconia chiral columns for separation of enantiomeric compounds by capillary electrochromatography (CEC). Using sol-gel technology, a porous monolith having interconnected globular-like structure with through-pores is synthesized in the capillary column as a first step in the synthesis of monolithic zirconia chiral capillary columns. In the second step, the surface of the monolith is modified by coating with cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC) as the chiral stationary phase to obtain a chiral column (CDMPCZM). The process of the preparation of the zirconia monolithic capillary column was investigated by varying the concentrations of the components of the sol solution including polyethylene glycol, water and acetic acid. CDMPCZM is mechanically stable and no bubble formation was detected with the applied current of up to 30μA. The enantioseparation behavior of the CDMPCZM columns was investigated by separating a set of 10 representative chiral compounds by varying the applied voltage and pH and organic composition of the aqueous organic mobile phases.

A Test of Relative Removal Properties of Various Offensive Odors by Zeolite

Adedeji A. Adelodun,Kowsalya Vellingiri,전병훈,오종민,Sandeep Kumar,김기현 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.1

The adsorptive removal properties of synthetic A4 zeolite were investigated against a total of 16 offensive odors consisting of reduced sulfur compounds (RSCs), nitrogenous compounds (NCs), volatile fatty acids (VFAs), and phenols/indoles (PnI). Removal of these odors was measured using a laboratory-scale impinger-based adsorption setup containing 25 g of the zeolite bed (flow rate of 100 mL min-1). The high est and lowest breakthrough (%) values were shown for PnIs and RSCs, respectively, and the maximum and minimum adsorption capacity (μg g-1) of the zeolite was observed for the RSCs (range of 0.77-3.4) and PnIs (0.06-0.104), respectively. As a result of sorptive removal by zeolite, a reduction in odor strength, measured as odor intensity (OI), was recorded from the minimum of approximately 0.7 OI units (indole [from 2.4 to 1.6]), skatole [2.2 to 1.4], and p-cresol [5.1 to 4.4]) to the maximum of approximately 4 OI units (methanethiol [11.4 to 7.5], n-valeric acid [10.4 to 6.5], i-butyric acid [7.9 to 4.4], and propionic acid [7.2 to 3.7]). Likewise, when removal was examined in terms of odor activity value (OAV), the extent of reduction was significant (i.e., 1000-fold) in the increasing order of amy acetate, ibutyric acid, phenol, propionic acid, and ammonia.

Analysis of activation, ohmic, and concentration losses in hydrogen fuelled PEM fuel cell

Rohan Kumar,K.A Subramanian Techno-Press 2022 Advances in energy research Vol.8 No.4

This paper deals with the effects of design (active area, current density, membrane conductivity) and operating parameters (temperature, relative humidity) on the performance of hydrogen-fuelled proton exchange membrane (PEM) fuel cell. The design parameter of a PEM fuel cell with the active area of the single cell considered in this study is 25 cm² (5 × 5). The operating voltage and current density of the fuel cell were 0.7 V and 0.5 A/cm² respectively. The variations of activation voltage, ohmic voltage, and concentration voltage with respect to current density are analyzed in detail. The membrane conductivity with variable relative humidity is also analyzed. The results show that the maximum activation overpotential of the fuel cell was 0.4358 V at 0.21 A/cm² due to slow reaction kinetics. The calculated ohmic and concentrated overpotential in the fuel cell was 0.01395 V at 0.76 A/cm² and 0.027 V at 1.46 A/cm² respectively.

Isoelectronic Pt(ii)- and Au(iii)-N-heterocyclic carbene complexes: a structural and biological comparison

Rana, Bidyut Kumar,Mishra, Snehasis,Sarkar, Deblina,Mondal, Tapan Kumar,Seth, Saikat K.,Bertolasi, Valerio,Das Saha, Krishna,Bielawski, Christopher W.,Isab, Anvarhusein A.,Dinda, Joydev The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.13

<P>To elucidate the intrinsic biological activities displayed by platinum <I>versus</I> gold-based organometallic reagents, the isoelectronic and isostructural square planar complexes [Pt(C∩N)(C)Cl][PF6] (2) and [Au(C∩N)(C)Cl][PF6]2 (3), which are supported by a common N-heterocyclic carbene, 1-methyl-2-pyridin-2-yl-2<I>H</I>-imidazo[1,5-<I>a</I>]pyridin-4-ylidene (1), were synthesized. The complexes were characterized using a range of spectroscopic techniques as well as single crystal X-ray diffraction and a series of computational studies were also performed to gain additional insight into their fundamental electronic bonding structures. The cytotoxicities of the complexes were tested <I>in vitro</I> against non-small lung carcinoma (A549), colorectal carcinoma (HCT-116) and human hepatocellular carcinoma (HepG2) cell lines. The measured IC50 values showed that the Au(iii)-NHC complex is more potent than its Pt analogue.</P>

Biology of Anagyrus kamali (Moursi) (Hymenoptera : Encyrtidae) - A Parasitoid of the Mealybug, Maconellicoccus hirsutus (Green, with a Note on Its Incidence

Katiyar, R.L.,Kumar, Vineet,Manjunath, D.,Sen, A.K.,Shekhar, M.A.,Datta, R.K. Korean Society of Sericultural Science 2000 International Journal of Industrial Entomology Vol.1 No.2

The occurrence of Anagyrus kamali, a solitary endoparasite of the mealybug, Maconellicoccus hirsutus has been reported for the first time from India. The parasitoid was fecund to parasitizing the field population of mealybug to the tune of 10.37 to 42.70% in different months. A comprehensive study on the development of the parasitoid on different stages of mealybug indicated that the parasitoid was able to complete its development in all the stages. Higher parasitism (67.48-78.08%) and more female progeny were observed when 3rd instar nymphs and adult female of the mealybug were exposed to the parasitoid. The biology of A. kamali studied at 25${\pm}1^{\circ}C$ temperature and 60${\pm}$</TEX10% R.H. The parasitoid completes its life cycle in 19.72$\pm$1.12 days. The duration of egg, larva (3 instars) and pupa were 2.67${\pm}$</TEX0.42, 8.80${\pm}$</TEX0.43 and 8.25${\pm}$</TEX0.38 days, respectively. On an average each female of A. kamali laid 39.0${\pm}$</TEX4.53 eggs. It was found to parasitising 8-10 mealybugs and depositing 1-3 eggs per host individual. Observations on adult longevity, parasitizing potential and sex ratio has also been recorded.