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Magnetic ground state of the multiferroic hexagonal LuFeO3
Suresh, Pittala,Vijaya Laxmi, K.,Bera, A. K.,Yusuf, S. M.,Chittari, Bheema Lingam,Jung, Jeil,Anil Kumar, P. S. American Physical Society 2018 Physical Review B Vol.97 No.18
<P>The structural, electric, and magnetic properties of bulk hexagonal LuFeO3 are investigated. Single phase hexagonal LuFeO3 has been successfully stabilized in the bulk form without any doping by sol-gel method. The hexagonal crystal structure with P6(3)cm space group has been confirmed by x-ray-diffraction, neutron-diffraction, and Raman spectroscopy study at room temperature. Neutron diffraction confirms the hexagonal phase of LuFeO3 persists down to 6 K. Further, the x-ray photoelectron spectroscopy established the 3+ oxidation state of Fe ions. The temperature-dependent magnetic dc susceptibility, specific heat, and neutron-diffraction studies confirm an antiferromagnetic ordering below the Neel temperature (T-N) similar to 130 K. Analysis of magnetic neutron-diffraction patterns reveals an in-plane (ab-plane) 120 degrees antiferromagnetic structure, characterized by a propagation vector k = (0 0 0) with an ordered moment of 2.84 mu(B)/Fe3+ at 6 K. The 120 degrees antifferomagnetic ordering is further confirmed by spin-orbit coupling density functional theory calculations. The on-site coulomb interaction (U) and Hund's parameter (J(H)) on Fe atoms reproduced the neutron-diffraction Gamma(1) spin pattern among the Fe atoms. P-E loop measurements at room temperature confirm an intrinsic ferroelectricity of the sample with remnant polarization P-r similar to 0.18 mu(C) cm(2). A clear anomaly in the dielectric data is observed at similar to T-N revealing the presence of magnetoelectric coupling. A change in the lattice constants at T-N has also been found, indicating the presence of a strong magnetoelastic coupling. Thus a coupling between lattice, electric, and magnetic degrees of freedom is established in bulk hexagonal LuFeO3.</P>
K. Krishna Prasad,S. Venkata Mohan,Y. Vijaya Bhaskar,S. V. Ramanaiah,V. Lalit Babu,B. R. Pati,P. N. Sarma 한국미생물학회 2005 The journal of microbiology Vol.43 No.3
The feasibility of laccase production by immobilization of Pleurotus ostreatus 1804 on polyurethane foam (PUF) cubes with respect to media composition was studied in both batch and reactor systems. Enhanced laccase yield was evidenced due to immobilization. A relatively high maximum laccase activity of 312.6 U was observed with immobilized mycelia in shake flasks compared to the maximum laccase activity of free mycelia (272.2 U). It is evident from this study that the culture conditions studied, i.e. biomass level, pH, substrate concentration, yeast extract concentration, Cu2+ concentration, and alcohol nature, showed significant influence on the laccase yield. Gel electrophoretic analysis showed the molecular weight of the laccase produced by immobilized P. ostreatus to be 66 kDa. The laccase yield was significantly higher and more rapid in the packed bed reactor than in the shake flask experiments. A maximum laccase yield of 392.9 U was observed within 144 h of the fermentation period with complete glucose depletion.
Prasad K. Krishna,Mohan S. Venkata,Bhaskar Y. Vijaya,Ramanaiah S. V.,Babu V. Lalit,Pati B. R.,Sarma P. N. The Microbiological Society of Korea 2005 The journal of microbiology Vol.43 No.3
The feasibility of laccase production by immobilization of Pleurotus ostreatus 1804 on polyurethane foam (PUF) cubes with respect to media composition was studied in both batch and reactor systems. Enhanced laccase yield was evidenced due to immobilization. A relatively high maximum laccase activity of 312.6 U was observed with immobilized mycelia in shake flasks compared to the maximum laccase activity of free mycelia (272.2 U). It is evident from this study that the culture conditions studied, i.e. biomass level, pH, substrate concentration, yeast extract concentration, $Cu^{2+}$ concentration, and alcohol nature, showed significant influence on the laccase yield. Gel electrophoretic analysis showed the molecular weight of the laccase produced by immobilized P. ostreatus to be 66 kDa. The laccase yield was significantly higher and more rapid in the packed bed reactor than in the shake flask experiments. A maximum laccase yield of 392.9 U was observed within 144 h of the fermentation period with complete glucose depletion.
Robot-assisted modifications of gait in healthy individuals.
Kim, Seok Hun,Banala, Sai K,Brackbill, Elizabeth A,Agrawal, Sunil K,Krishnamoorthy, Vijaya,Scholz, John P Springer-Verlag 2010 Experimental brain research Vol.202 No.4
<P>This study investigated whether short-term modifications of gait could be induced in healthy adults and whether a combination of kinetic (a compliant force resisting deviation of the foot from the prescribed footpath) and visual guidance was superior to either kinetic guidance or visual guidance alone in producing this modification. Thirty-nine healthy adults, 20-33 years old, were randomly assigned to the three groups receiving six 10-min blocks of treadmill training requiring them to modify their footpath to match a scaled-down path. Changes of the footpath, specific joint events and joint moments were analyzed. Persons receiving combined kinetic and visual guidance showed larger modifications of their gait patterns that were maintained longer, persisting up to 2 h after intervening over-ground activities, than did persons receiving training with primarily kinetic guidance or with visual guidance alone. The results emphasize the short-term plasticity of locomotor circuits and provide a possible basis for persons learning to achieve more functional gait patterns following a stroke or other neurological disorders.</P>
Babu, P.,Jang, Kyoung Hyuk,Kim, Eun Sik,Shi, Liang,Vijaya, R.,Laví,n, V.,Jayasankar, C.K.,Seo, Hyo Jin Elsevier 2010 Journal of non-crystalline solids Vol.356 No.4
<P><B>Abstract</B></P><P>Dysprosium-doped oxyfluoride glasses and nanocrystalline glass–ceramics have been synthesized and studied by X-ray diffraction, transmission electron microscope, optical spectroscopy and time-resolved decay curves measurements. From the absorption spectra, Judd–Ofelt intensity parameters have been obtained and are used to predict radiative properties for the excited states of Dy<SUP>3+</SUP> ions. From the visible emission spectra, yellow to blue intensity ratios have been calculated and their relative variations have been discussed based on the concentration of Dy<SUP>3+</SUP> ions and the heat treatment conditions used to prepare the glass–ceramics. Luminescence decay curves of the <SUP>4</SUP>F<SUB>9/2</SUB> emitting level are found to be single exponential for 0.01mol% Dy<SUP>3+</SUP>-doped glass and non-exponential for the remaining samples. The nature of energy transfer processes between Dy<SUP>3+</SUP> ions, responsible for the non-exponential behavior of the decay curves, has been analyzed in the frame work of the Inokuti–Hirayama model. Lifetimes of the <SUP>4</SUP>F<SUB>9/2</SUB> level are found to decrease with the concentration of Dy<SUP>3+</SUP> ions as well as with the time of heat treatment.</P>
Characterizations of plasma sprayed composite coatings over 1020 mild steel
P. Vijayanand,Amitesh Kumar,K. R. Vijaya Kumar,A. Vinod,P. Kumaran,S. Arungalai Vendan 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
The present work deals with the coating of mild steel using plasma spray coating technique to improve surface properties for various industrial applications. Three different composite coating powders namely Al 2 O 3 :TiO 2 , Al 2 O 3 :TiO 2 : CNT and Al 2 O 3 : CNT were coated on the surface of mild steel for a thickness of 0.25 mm. Subsequently, the coated samples were tested for their mechanical characteristics namely tensile, compression and hardness followed by tribological investigations primarily comprising of wear analysis. Further, metallurgical analysis engrossing the Scanning electron microscopy, X-Ray diffraction and Energy-dispersive X-ray spectroscopy analysis were carried out to assess the homogeneity, spread uniformity and bond integrity of the developed samples. The test results revealed that the performance measure of Al 2 O 3 :TiO 2 : CNT is way ahead than other two powder coatings while carbon nanotube majorly contributes to the strength and quality of the surface coating.
Rao, P.Sudhakara,Datta, R.K.,Vijaya Kumari, K.M.,Palit, A.K.,Haque Rufaie, S.Z. Korean Society of Sericultural Science 2004 International Journal of Industrial Entomology Vol.9 No.1
Studies on heterotic expression in the silk productivity of 66 thermo-tolerant bivoltine hybrids reared under high temperature $(36{\times}1^{\circ}C)$ and low humidity (60${\times}$5%) conditions revealed that manifestation of heterosis was highly significant for majority of the quantitative traits contributing to more cocoon productivity. Observations were made on 8 economically important traits such as fecundity, pupation rate, cocoon yield, cocoon weight, cocoon shell weight, cocoon shell ratio, cocoon filament length and raw silk. Analysis of variance results revealed great deal of variability indicating significant (P < 0.001) variations. Out of 66 hybrids, 7 hybrids exhibited positive heterosis for seven traits and 4 hybrids expressed significant hetero-beltiosis for 6 traits, out of 8 traits evaluated. Based on results, the hybrids ${SR_1} {\times} {SR_5}and {CSR_2} {\times} {SR_5}$ are adjudged as most promising ones and can be exploited commercially in tropical climates to increase the cocoon productivity.
Characterization of fully and partially penetrated Nd: YAG laser-weld dissimilar metal joints
A. P. Tadamalle,Y. P. Reddy,E. Ramjee,K. Vijaya Kumar Reddy 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2
Welding dissimilar metals and alloys is essential to emerging new technologies in manufacturing industries. This process is difficult because of the formation of intermetallic layers and the variations in the chemical and mechanical properties in the weld region. This paper aimed to characterize fully and partially penetrated dissimilar metal weld joints. The welding experiments were conducted on 0.5 mm-thick dissimilar weld joints for the investigation of the effects of the process parameters on the weld joints. Variations in chemical composition, oxide formation, imperfections and mechanical properties were analyzed. Results revealed that the weld joint characteristics notably deviated from the base metal properties in terms of hardness, strength, chemical composition, oxide formation and other constituents of the weld pool region. This study offers insight into the effects of process parameters and the necessary changes in weld composition for the improvement of welds joints.