Electronic, Magnetic and Optical Properties of 2D Metal Nanolayers: A DFT Study

Prabal Dev Bhuyan,Sanjeev K. Gupta,Deobrat Singh,Yogesh Sonvane,P. N. Gajjar 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.4

In the recent work, we have investigated the structural, electronic, magnetic and optical properties of graphene-like hexagonalmonolayers and multilayers (up to fi ve layers) of 3 d -transition metals Fe, Co and Ni based on spin-polarized density functionaltheory. Here, we have taken two types of pattern namely AA-stacking and AB-stacking for the calculations. The bindingenergy calculations show that the AA-type confi guration is energetically more stable. The calculated binding energies of Fe,Co and Ni-bilayer monolayer are − 3.24, − 2.53 and − 1.94 eV, respectively. The electronic band structures show metallicbehavior for all the systems and each confi gurations of Fe, Co and Ni-atoms. While, the quantum ballistic conductancesof these metallic systems are found to be higher for pentalayer than other layered systems. The density of states confi rmsthe ferromagnetic behavior of monolayers and multilayers of Fe and Co having negative spin polarizations. We have alsocalculated frequency dependent complex dielectric function, electronic energy loss spectrum and refl ectance spectrum ofmonolayer to pentalayer metallic systems. The ferromagnetic material shows Different permittivity tensor ( ɛ ), which is dueto high spin magnetic moment for n-layered Fe and Co two-dimensional (2D) nanolayers. The theoretical investigation suggeststhat the electronic, magnetic and optical properties of 3 d -transition metal nanolayers off ers great promise for their usein spintronics nanodevices and magneto-optical nanodevices applications.

Leucaena Seeds as Protein Supplement in the Rations of Growing Sheep

Singh, Sultan,Kundu, S.S.,Negi, A.S.,Gupta, S.K.,Singh, N.P.,Pachouri, V.C. Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.10

The study was carried out to evaluate leucaena seeds as a protein replacement of mustard seed cake (MSC) in the concentrate mixture of growing lambs. Fifteen owing male lambs (Local${\times}$Corridale) with an average body weight of 16.3 kg were allocated into three dietary treatments (T1, T2, and T3) with five animals in each group. Animals were offered dry mixed grass, berseem hay and concentrate mixture to meet their nutrient requirements. In concentrate mixture of T1, (Control) MSC was used as protein source, while in T2 and T3 groups, 25 and 50% of MSC was replaced by leucaena leucocephala seeds. On completion of three months (90 days) of feeding, a digestion cum-metabolism trial was conducted to determine DMI, nutrient utilization, and nitrogen balance. Changes in body weight were recorded at 15 day internals and eating patterns were recorded for 3 consecutive days at the end of the feeding trial. MSC had higher CP contents than leucaena seeds (27.0%). Mimosine contents in leucaena seeds were 1.1 compared to 0.2 and 0.4% in concentrate mixture of T2 and T3 group, respectively. Dry matter intake varied non-significantly ($79.3{\pm}1.2$ to $83.4{\pm}1.3g/kg$ $w^{0.75}$) across the dietary treatments. Digestibility of DM and cell wall polysaccharides (NDF, ADF. Cellulose and hemicellulose) were comparable, however CP digestibility was relatively lower in leucaena luecocephala seeds based groups (T2 $45.5{\pm}1.7$ and T3 $46.7{\pm}3.5$) compared to MSC supplemented group (T1 $47.7{\pm}0.9%$). The growth rate of lambs was non-significantly higher in T1 ($79.2{\pm}5.4$) compared to T2 ($73.8{\pm}8.8$) and T3 ($73.9{\pm}7.0$), respectively. The animals were in positive nitrogen balance and N-balance varied from 1.8 to 2.9 g/d across treatment groups. The eating rate (% of total offered) of concentrate up-to 15 min was relatively higher in T1 (82.4) than T2 (74.2) and T3 (77.8%). However no effect of leucaena seeds was recorded on total DMI of animals. The results of the study revealed that the inclusion of up to 50% leucaena seeds, as protein source in concentrate mixture of lambs had no adverse effect on DMI, nutrient utilization, eating patterns, nitrogen balance and growth performance of lambs.

An analysis of 175 MeV Nickel ion irradiation and annealing effects on silicon NPN rf power transistors

N. Pushpa,K.C. Praveen,A.P. Gnana Prakash,S.K. Gupta,D. Revannasiddaiah 한국물리학회 2013 Current Applied Physics Vol.13 No.1

In this study NPN rf power transistors were irradiated by 175 MeV Ni13þ ions in the dose range of 100 krad to 100 Mrad. Their characteristics such as excess base current (DIB ¼ IBpost IBpre), dc current gain (hFE), transconductance (gm) and collector-saturation current (ICSat) were studied before and after irradiation. The damage factor (K) for hFE was calculated using MessengereSpratt relation. The base current (IB) was found to increase significantly after irradiation and in turn decreases the hFE. The gm and collector current (IC) in the saturation region (ICSat) were found to decrease with increase in radiation dose. The results obtained here were also compared with that obtained by 140 MeV Si10þ ions, 100 MeV F8þ ions, 95 MeV O7þ ions and 50 MeV Li3þ ions irradiation studies in the same dose ranges to understand the LET effects. The recovery in the IeV characteristics of irradiated NPN transistors were studied by isothermal and isochronal annealing methods.

MULTIOBJECTIVE SECOND-ORDER NONDIFFERENTIABLE SYMMETRIC DUALITY INVOLVING (F, $\alpha$, $\rho$, d)-CONVEX FUNCTIONS

Gupta, S.K.,Kailey, N.,Sharma, M.K. The Korean Society for Computational and Applied M 2010 Journal of applied mathematics & informatics Vol.28 No.5

In this paper, a pair of Wolfe type second-order nondifferentiable multiobjective symmetric dual program over arbitrary cones is formulated. Weak, strong and converse duality theorems are established under second-order (F, $\alpha$, $\rho$, d)-convexity assumptions. An illustration is given to show that second-order (F, $\alpha$, $\rho$, d)-convex functions are generalization of second-order F-convex functions. Several known results including many recent works are obtained as special cases.

Convergence of q-Meyer-König-Zeller-Durrmeyer operators

N. K. Govil,V. Gupta 장전수학회 2009 Advanced Studies in Contemporary Mathematics Vol.19 No.1

In the present paper, we introduce a new type of q integrated Meyer-Konig-Zeller-Durrmeyer operators, obtain moments for the these operators and estimate the convergence of these integrated q-MKZD operators.

Photoluminescence, thermoluminescence and evaluation of some parameters of Dy³⁺ activated Sr₅(PO₄)₃F phosphor synthesized by sol-gel method

Gupta, K.K.,Kadam, R.M.,Dhoble, N.S.,Lochab, S.P.,Singh, V.,Dhoble, S.J. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.688 No.2

In this study, we have synthesized Dy<SUP>3+</SUP> activated Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F (S-FAP) phosphors by sol-gel synthesis method. The synthesized phosphors were characterized by X-ray diffraction pattern (XRD), scanning electron microscopic (SEM), photoluminescence (PL) and thermoluminescence (TL) for structural, morphological and luminescent properties. Dy<SUP>3+</SUP> activated Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphor shows its characteristic PL emission at 481 nm and 574 nm due to <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>15/2</SUB> and <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>13/2</SUB> transitions, respectively. TL characteristics of Dy<SUP>3+</SUP> doped Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphors were taken after irradiation by <SUP>60</SUP>Co gamma exposure. Two separate TL peaks at 126 <SUP>o</SUP>C and 279 <SUP>o</SUP>C were observed in case of Dy<SUP>3+</SUP> doped phosphor. Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor was irradiated within a wide range of exposure of 50 Gy to 7 kGy doses. Linearity was found up to 2 kGy and thereafter TL response saturates. Fading study was also carried out over the duration of six weeks for Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F phosphor. Trapping parameters were calculated using Chen's peak shape method, initial rise method and various heating rate method. Glow curve is deconvoluted using computerized glow curve deconvolution program. TL sensitivity of Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor is found to be less by a factor of 2.08 than commercially used CaSO<SUB>4</SUB>:Dy phosphor. In order to identify the defect centers formed upon γ-ray irradiation in Sr<SUB>5</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB>F:Dy<SUP>3+</SUP> phosphor, EPR measurements were carried out on un-irradiated and irradiated phosphors.

Differential responses of two rice varieties to salt stress

Ghosh, N.,Adak, M.K.,Ghosh, P.D.,Gupta, S.,Sen Gupta, D.N.,Mandal, C. The Korean Society of Plant Biotechnology 2011 Plant biotechnology reports Vol.5 No.1

Two rice varieties, viz. Nonabokra and Pokkali, have been evaluated for their responses to salinity in terms of some physiological and biochemical attributes. During the exposure to salinity (200 mM concentration of sodium chloride for 24, 48, and 72 h), a significant increase in sodium was recorded which was also concomitant with the changes of other metabolic profiles like proline, phenol, polyamine, etc. The protein oxidation was significantly increased and also varied between the two cultivars. The changes in activities of anti-oxidative enzymes under stress were significantly different to the control. The detrimental effects of salinity were also evident in terms of lipid peroxidation, chlorophyll content, protein profiles, and generation of free radicals; and these were more pronounced in Pokkali than in Nonabokra. The assessment and analysis of these physiological characters under salinity could unravel the mechanism of salt responses revealed in this present study and thus might be useful for selection of tolerant plant types under the above conditions of salinity.

Carbon Fibres for the Repair of Abdominal Wall Defects in Rabbits

A.K. Gangwar,A.K. Sharma,Naveen Kumar,S.K. Maiti,N. Kumar,O.P. Gupta,T.K. Goswami,Rajendra Singh 한국탄소학회 2005 Carbon Letters Vol.6 No.1

Sixteen clinically healthy New Zealand white rabbits of either sex were divided into two equal groups I and II of 8 animals each. Under thiopental sodium (2.5%) anaesthesia a linear full thickness abdominal wall defect of 3 cm in length was created and repaired with continuous suture pattern using 3000 filaments of carbon fibres and 1~0 black braided nylon suture, ingroup I and II respectively. Increased vascularity was observed in carbon fibres (group I) and on day 30 the carbon fibres were covered by white fibrous tissue. Significantly higher (P < 0.05) values of glucose was seen on day 14 in group I, whereas, decrease in glucose value was observed in group II. Histopathologically, the carbon fiber implant induced extensive fibrous tissue (collagen fiber) reaction. Negligible inflammatory cells in the stroma indicate the host tissue tolerance to carbon fibers. Histochemically, gradually increased alkaline phosphatase activity up to day 14 in group I, suggested the proliferation of fibroblasts in early stages.

Isolation of Thermotolerant Phytase Producing Fungi and Optimisation of Phytase Production by Aspergillus niger NRF9 in Solid State Fermentation Using Response Surface Methodology

R. K. Gupta,S. S. Gangoliya,N. K. Singh 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.6

Phytase is an enzyme that hydrolyses phyticacid into myo-inositol and inorganic phosphate. Onehundred thirteen fungi were isolated from 58 soil samplescollected from different sites with high organic mattercontent. They were screened for phytate hydrolysing activityon phytase screening medium (PSM). Clear zones wereformed around the colonies of 72 isolates on Ca-containingPSM. Solid state fermentation was done for the selectedfungal isolates for production of the phytase enzyme. Among the isolates, NRF9 showed maximum enzymeactivity (39.2 U/gds) upon quantitative screening after5 days of incubation at 30°C. The fungus grew vigorouslyand secreted enzyme at temperatures of 30, 37, and 45°C. The maximum phytase production was obtained at 30°C;the next-best production was obtained at 37°C. The isolatewas identified and characterised as Aspergillus niger NRF9on the basis of 18S rDNA sequencing. Various processparameters were optimised using a one-variable-at-a-timeapproach’. The significant factors for phytase productionwere identified as incubation time, solid:liquid ratio andglucose concentration. These factors were further optimisedusing a Box-Behnken design. Maximum phytase production(112.1 U/gds) was observed at 5 days of incubation time,a 1:2 solid:liquid ratio and a 1% glucose concentration. Validation of these optimised variables was done in shakeflasks. Optimisation resulted in a 2.9-fold increase in phytaseproduction compared to unoptimised cultivation conditions.

X-ray/gamma radiation shielding properties of Aluminium-Barium Zinc Oxide nanoparticles synthesized via low temperature solution combustion method

Sathish K.V.,Sridhar K.N.,Seenappa L.,Manjunatha H.C.,Vidya Y.S.,Chinnappa Reddy B.,Manjunatha S.,Santhosh A.N.,Munirathnam R.,Raj Alfred Cecil,Damodara Gupta P.S.,Sankarshan B.M. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.5

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (6000 C) to study the electromagnetic (EM) (X/g) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl2O4, cubic BaðNO3Þ2, a and g phase of Al2O3 which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc’s relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/g) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/g) radiation shielding