http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Investigations on the structural, optical and electronic properties of Nd doped ZnO thin films
Subramanian, M,Thakur, P,Gautam, S,Chae, K H,Tanemura, M,Hihara, T,Vijayalakshmi, S,Soga, T,Kim, S S,Asokan, K,Jayavel, R Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.10
<P>We report the synthesis and characterization of Nd doped ZnO thin films grown on Si (1 0 0) substrates by the spray pyrolysis method. The surface morphology of these thin films was investigated by scanning electron microscopy and shows the presence of randomly distributed structures of nanorods. Grazing angle x-ray diffraction studies confirm that the doped Nd ions occupied Zn sites and these samples exhibited a wurtzite hexagonal-like crystal structure similar to that of the parent compound, ZnO. The micro-photoluminescence measurement shows a decrease in the near band edge position with Nd doping in the ZnO matrix due to the impurity levels. The near-edge x-ray absorption fine structure (NEXAFS) measurements at the O K edge clearly exhibit a pre-edge spectral feature which evolves with Nd doping, suggesting incorporation of more charge carriers in the ZnO system and the presence of strong hybridization between O 2p–Nd 5d orbitals. The Nd M<SUB>5</SUB> edge NEXAFS spectra reveal that the Nd ions are in the trivalent state.</P>
A study of glass and carbon fibers in FRAC utilizing machine learning approach
Ankita Upadhya,M. S. Thakur,Nitisha Sharma,Fadi H. Almohammed,Parveen Sihag Techno-Press 2024 Advances in materials research Vol.13 No.1
Asphalt concrete (AC), is a mixture of bitumen and aggregates, which is very sensitive in the design of flexible pavement. In this study, the Marshall stability of the glass and carbon fiber bituminous concrete was predicted by using Artificial Neural Network (ANN), Support Vector Machine (SVM), Random Forest (RF), and M5P Tree machine learning algorithms. To predict the Marshall stability, nine inputs parameters i.e., Bitumen, Glass and Carbon fibers mixed in 100:0, 75:25, 50:50, 25:75, 0:100 percentage (designated as 100GF:0CF, 75GF:25CF, 50GF:50 CF, 25GF:75CF, 0GF:100CF), Bitumen grade (VG), Fiber length (FL), and Fiber diameter (FD) were utilized from the experimental and literary data. Seven statistical indices i.e., coefficient of correlation (CC), mean absolute error (MAE), root mean squared error (RMSE), relative absolute error (RAE), root relative squared error (RRSE), Scattering index (SI), and BIAS were applied to assess the effectiveness of the developed models. According to the performance evaluation results, Artificial neural network (ANN) was outperforming among other models with CC values as 0.9147 and 0.8648, MAE values as 1.3757 and 1.978, RMSE values as 1.843 and 2.6951, RAE values as 39.88 and 49.31, RRSE values as 40.62 and 50.50, SI values as 0.1379 and 0.2027 and BIAS value as -0.1 290 and -0.2357 in training and testing stage respectively. The Taylor diagram (testing stage) also confirmed that the ANN-based model outperforms the other models. Results of sensitivity analysis showed that the fiber length is the most influential in all nine input parameters whereas the fiber combination of 25GF:75CF was the most effective among all the fiber mixes in Marshall stability.
Bashir, Abida,Ikram, M,Kumar, Ravi,Thakur, P,Chae, K H,Choi, W K,Reddy, V R IOP Pub 2009 Journal of Physics, Condensed Matter Vol.21 No.32
<P>We present here the structural, electronic structure, magnetic and Mossbauer studies of NdFe1-xNixO3 (0 <= x <= 0.3) samples. All the samples exhibit a single-phase orthorhombic structure with space group Pbnm. The near-edge x-ray absorption fine structure (NEXAFS) studies reveal that, with the Ni substitution at Fe sites, a new spectral feature about 1.5 eV lower than the pre-edge structure of NdFeO3 in the O K edge is observed due to the 3d contraction effect and is growing monotonically with the increase of Ni concentration. The Fe L-3,L-2, Ni L-3,L-2 and Nd M-5,M-4 edges confirm the trivalent state of Fe, Ni and Nd ions. The Mossbauer spectra fitted with two Zeeman sextets confirm the different surroundings of Ni around Fe ions. With the increase in Ni concentration, the sextets are broadened. The increase of quadrupole splitting and the decrease of the hyperfine field suggest the change in the ordered regime of the system. The magnetic behaviour at low temperatures is explained in the context of competition among moments of rare earth (Nd) and transition metal ions (Fe/Ni). The strong paramagnetic contribution of the Nd magnetic sublattice and spin flip phenomenon is observed from the temperature dependence of zero-field-cooled and field-cooled magnetization where spin crossover is observed. The isothermal hysteresis loops show a decrease of magnetization and increase of coercivity with the increase in temperature and complements magnetization versus temperature. The results are explained on the basis of the spin reorientation phenomenon.</P>
In vitro Antioxidant Activity of Ethanolic Extract of Chlorophytum borivilianum
R. Govindarajan1,,N. Sreevidya1,,M. Vijayakumar1,,M. Thakur2,,V.K. Dixit2,,S. Mehrotra*1,,P. Pushpangadan1 한국생약학회 2005 Natural Product Sciences Vol.11 No.3
Chlorophytum borivilianum Baker (Antharicaceae) comonly referred as ‘Safed Musli’ has beenwidely used in the Indian traditional systems of medicine to treat various diseases like rheumatism apart fromaphordisiac properties. C. borivilianum was screened for the first time to determine its antioxidant activity,isolation of the sapogenins and standardization of the isolated sapogenin fraction using HPTLC. Potent antioxidantactivity of ethanolic extract was found by their ability to scavenge DPPH (84.51%), hydroxyl radical (48.95 %),feryl bi-pyridyl complex (84.53%) along with the inhibition of lipid peroxidation (67.17%) at 100g/mlconcentration. The ethanolic extract also exhibited significant inhibition of superoxide anion radical generated byplant in the traditional system especially its use as a Rasayana drug.
Bashir, A.,Ikram, M.,Kumar, R.,Lisboa-Filho, P.N.,Thakur, P. Elsevier 2010 Materials science and engineering B. Advanced Func Vol.172 No.3
We present the structural, electronic structure and magnetic studies of Ni doped SmFeO<SUB>3</SUB>. The X-ray diffraction (XRD) studies confirm the single phase nature of the samples having orthorhombic Pbnm structure and the unit-cell volume is decreasing with the increase of Ni concentration. X-ray absorption spectroscopy (XAS) studies on O K, Fe L<SUB>3,2</SUB>, Ni L<SUB>3,2</SUB> and Sm M<SUB>5,4</SUB> edges of SmFe<SUB>1-x</SUB>Ni<SUB>x</SUB>O<SUB>3</SUB> (x@?0.5) samples along with the reference compounds revealed the homo-valence state of Fe and Ni in these materials. From magnetization studies it has been observed the materials exhibit ferromagnetic and antiferromagnetic sub-lattices, which are strongly dependent on the thermo-magnetic state of the system.
Thakur, A.K.,Nisola, G.M.,Limjuco, L.A.,Parohinog, K.J.,Torrejos, R.E.C.,Shahi, V.K.,Chung, W.J. Korean Society of Industrial and Engineering Chemi 2017 Journal of industrial and engineering chemistry Vol.49 No.-
<P>Nano-spherical amine-rich polyethylenimine (PEI) grafted on mesoporous silica (MCM-41) (PEI/MCM-41) was developed for Cd(II) and Ni(II) removal from water. Characterization of PEI/MCM-41 using various techniques confirms its successful fabrication. Adsorption results reveal that pH and adsorbent dosage must be controlled for maximum removal. The adsorption rate was pseudo-second-order, and fitted well with Langmuir and Freundlich isotherms at equilibrium. The adsorption was thermodynamically spontaneous, endothermic and favourable. Adsorption capacities of 156.0 mg g(-1) Cd(II) and 139.7 mg g(-1) Ni(II) were on par with other high performing reported adsorbents. The PEI/MCM-41 was successfully reused demonstrating its potential for heavy metal decontamination application. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>
Electronic Structure of Mn-Doped ZnO Studied by Using X-ray Absorption Spectroscopy
P. Thakur,K. H. Chae,M. Subramanain,R. Jayavel,K. Asokan 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5
Mn-doped ZnO thin films that showed ferromagnetism at room temperature were synthesized with nominal compositions Zn1-xMnxO (x = 0.03, 0.05, 0.07, 0.10 and 0.15) by using a spray pyrolysis technique. High-resolution X-ray diffraction studies suggested that the doped Mn ions occupied Zn sites and that all the samples exhibited a wurtzite hexagonal-like crystal structure similar to that of the parent compound, ZnO. The near-edge X-ray absorption fine structure (NEXAFS) measurements at the O K-edge clearly exhibited a pre-edge spectral feature, which evolved with Mn doping, similar to one observed in hole-doped cuprates and manganites. The Mn L3;2-edge NEXAFS spectra exhibited divalent Mn apart from mixed valent Mn3+ / Mn4+ states, which were well supported by Mn K-edge spectra.