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Das, H.,Lee, K. J.,Hong, S. T. SPRINGER INTRNATIONAL 2017 JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE Vol.26 No.7
<P>Friction stir lap welding of dual phase 590 steel has been successfully performed within the A1 to A3 temperature range upon adjusting the process parameters. The microstructures and the texture have been characterized using scanning electron microscopy and electron back scattered diffraction analysis. The martensite volume fraction increases with an increasing travel speed from 100 to 300 mm/min for a constant tool rotational speed of 300 rpm. Under severe deformation and high strain rate during friction stir welding, the grain orientation < 101 > shifts toward the < 111 > and < 001 > directions compared to the base metal. The base metal shows gamma fiber components, whereas the friction stir welded specimen shows strong brass with weak cube fibers.</P>
Dash, U.,Raveendra, N.V.,Jung, C.U. Elsevier Sequoia 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.684 No.-
Bulk BiMnO<SUB>3</SUB> has a monoclinic structure and exhibits ferromagnetic properties below Tc~105 K. The existence of ferroelectricity was one of the hottest issues in this compound. To investigate the ferroelectricity in BiMnO<SUB>3</SUB>, a good film with low-enough leakage is highly required. However the reported quality of BiMnO<SUB>3</SUB> thin films has shown critical dependence on stoichiometry. Previously, we reported that a BiMnO<SUB>3</SUB> thin film grown on top of a SrTiO<SUB>3</SUB> (001) substrate has good stoichiometry, as well as bulk-quality ferromagnetic properties, but our results did not demonstrate the Q-E hysteresis curves. However, we could not exclude the possibility that non-ferroelectricity observed in the BiMnO<SUB>3</SUB> film is partly due to the tetragonal symmetry enforced by the strong epitaxial strain of the substrate since the ferroicity in most oxides accompanies with or equivalently originates from crystal symmetry breaking and/or lowering. In the present work, we used a SrTiO<SUB>3</SUB> (110) substrate with an anisotropic in-plane atomic arrangement to stabilize the BiMnO<SUB>3</SUB> thin film having the symmetry lower than tetragonal symmetry. After observing the stabilization of twined monoclinic phase in the BiMnO<SUB>3</SUB> film, we solved the twin problem by trying a novel substrate; i.e., miscut SrTiO<SUB>3</SUB> (110) substrate. The physical properties for the stoichiometric, twin-free, monoclinic BiMnO<SUB>3</SUB> thin film were notably similar to those reported for the stoichiometric BiMnO<SUB>3</SUB> bulk with monoclinic symmetry. We believe this new data more rigorously demonstrates the absence of ferroelectricity in stoichiometric monoclinic BiMnO<SUB>3</SUB>.
Dash Sujit,Kanungo Sunil Kumar,Mishra Bishwanath,Sahoo Amaresh Chandra,Senapati Aswini Kumar,Pattnaik Sangyarani 경희대학교 융합한의과학연구소 2021 Oriental Pharmacy and Experimental Medicine Vol.21 No.4
PCOS is considered as common endocrine diseases among the females in their regenerative age. The purpose of the study was to analyze phytochemicals by GC–MS followed by the pharmacological evaluation of Sukumaram Kasayam on PCOS induced rats. GC–MS analysis of Sukumaram Kasayam was accomplish to identify phytoconstituents. Twenty-four female rats were used (n = 6/group) in the study consisting of healthy control (Group-I). The experimental groups were divided into 3 subgroups, including rats with PCOS which received no treatment (Group-II), PCOS group (Group-III and Group-IV) was administered daily dose of Clomifene citrate 200 mg/kg and Sukumaram Kasayam 0.5 ml/kg for 3 weeks, respectively. In all experimental groups, oral dose of 1 mg/kg letrozole for 21 days to induce PCOS. After treatment period, rats were anesthetized, blood sex hormone and lipid profile was carried. The GC–MS analysis identified Butane, 1, 1-diethoxy-3-, (+)-2-Bornanone abundant compound in formulation. The PCOS induced rats were treated with Clomiphene citrate, Sukumaram Kasayam, the testosterone decreased significantly (P < 0.01), progesterone increased significantly (P < 0.01), estradiol increased significantly (P < 0.01), the serum LH decreased (P < 0.05), the FSH levels were decreased significantly (P < 0.01). In case of the lipid profile the result showed that the triglyceride, cholesterol, LDL decreased significantly (P < 0.01), whereas the HDL increased significantly (P < 0.01) in comparison to PCOS control rats. Results concluded that Sukumaram Kasayam has beneficial effect on levels of the testosterone, progesterone, estradiol, LH, and FSH in alleviating the complications of PCOS.
Large magnetoresistance in LaFeO<sub>3</sub>-substituted SrRuO<sub>3</sub> epitaxial thin films
Dash, Umasankar,Acharya, Susant Kumar,Cho, Seong Won,Lee, Suyoun,Lee, Kyoungjun,Chae, Seung Chul,Cho, Myung Rae,Jung, Chang Uk Elsevier 2017 Journal of alloys and compounds Vol.724 No.-
<P><B>Abstract</B></P> <P>In this work, the magnetotransport properties of epitaxial Sr<SUB>1-<I>x</I> </SUB>La<SUB> <I>x</I> </SUB>Ru<SUB>1-<I>x</I> </SUB>Fe<SUB> <I>x</I> </SUB>O<SUB>3</SUB> (<I>x</I> = 0.05, 0.10, 0.20, and 0.30) thin films grown by pulsed laser deposition on SrTiO<SUB>3</SUB> (001) substrates were investigated. Compared to doping Fe into the Ru<SUP>4+</SUP> site of SrRuO<SUB>3</SUB>, doping LaFeO<SUB>3</SUB> into SrRuO<SUB>3</SUB> resulted in an increase in the zero-field resistivity. A larger zero-field resistivity value in magnetic perovskite oxide is, in many cases, favorable for obtaining high magnetoresistance. The films (0.0 ≤ <I>x</I> ≤ 0.10) showed metallic behavior and ferromagnetic ordering, although the resistivity increased and the ferromagnetic transition temperature <I>T</I> <SUB>C</SUB> decreased with an increase in <I>x</I>. The thin film with <I>x</I> = 0.20 displayed a clear metal-to-insulator phase transition at low temperature and also displayed a well-defined resistivity minimum. This upturn in the resistivity curve is associated with the large electron-electron interaction present in the material. The magnetoresistance values increased as <I>x</I> increased, and we observed a large negative magnetoresistance (MR = −35%) for the thin film with <I>x</I> = 0.30. The observed high MR values are associated with spin fluctuation of the mobile electronic carriers in the material.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sr<SUB>1-<I>x</I> </SUB>La<SUB> <I>x</I> </SUB>Ru<SUB>1-<I>x</I> </SUB>Fe<SUB> <I>x</I> </SUB>O<SUB>3</SUB> epitaxial thin films were grown by PLD. </LI> <LI> The structural and magnet-transport properties of thin films were investigated. </LI> <LI> Metal-insulator transition was found in Sr<SUB>0.8</SUB>La<SUB>0.2</SUB>Ru<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3</SUB> thin film. </LI> <LI> The upturn of <I>ρ</I> of Sr<SUB>0.8</SUB>La<SUB>0.2</SUB>Ru<SUB>0.8</SUB>Fe<SUB>0.2</SUB>O<SUB>3</SUB> film was explained by e-e interactions. </LI> <LI> Magnetoresistance up to ∼35% were found for Sr<SUB>0.7</SUB>La<SUB>0.3</SUB>Ru<SUB>0.7</SUB>Fe<SUB>0.3</SUB>O<SUB>3</SUB> film. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
The dynamics of glassy behavior in SrRu1-Fe O3 heterostructure
Dash Umasankar,Pradhan Soumen,Rao M.S. Ramachandra,Veillon F.,Prellier W.,Jung Chang Uk 한국물리학회 2024 Current Applied Physics Vol.58 No.-
We report the magnetic interactions in SrRu1-xFexO3 epitaxial thin films. All the films showed a single-phase and good step-terrace structure with minimal surface roughness. The X-ray photoelectron spectra of Fe and Ru revealed that both transition metal elements exist in the films as Fe3+ and Ru4+. With Fe doping, the itinerant ferromagnetic behavior and ferromagnetic transition temperature gradually decreased, but the coercivity field increased. The magnetic interplay between Fe3+-O-Fe3+ is coined as antiferromagnetic. There was another interaction between Ru4+-O-Fe3+ which is best described as ferromagnetic. Furthermore, the magnetic frustration in our films caused by the doped Fe resulted in dynamic glassy behavior. On the other hand, the epitaxial strain from the imminent SrTiO3 substrate along with change in oxygen vacancy might have strong evidence for the spin-glass nature in our thin films.
Dash, Umasankar,Acharya, Susant Kumar,Lee, Bo Wha,Jung, Chang Uk Springer US 2017 Nanoscale research letters Vol.12 No.1
<P>Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxide materials. Here, we studied the influence of oxygen vacancies on the magnetoresistance (MR) properties of SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 - <I>δ</I></SUB> epitaxial thin films (<I>x</I> = 0.10, 0.20, and 0.30). For this purpose, we synthesized highly strained epitaxial SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 − <I>δ</I></SUB> thin films with atomically flat surfaces containing different amounts of oxygen vacancies using pulsed laser deposition. Without an applied magnetic field, the films with <I>x</I> = 0.10 and 0.20 showed a metal–insulator transition, while the <I>x</I> = 0.30 thin film showed insulating behavior over the entire temperature range of 2–300 K. Both Fe doping and the concentration of oxygen vacancies had large effects on the negative MR contributions. For the low Fe doping case of <I>x</I> = 0.10, in which both films exhibited metallic behavior, MR was more prominent in the film with fewer oxygen vacancies or equivalently a more metallic film. For semiconducting films, higher MR was observed for more semiconducting films having more oxygen vacancies. A relatively large negative MR (~36.4%) was observed for the <I>x</I> = 0.30 thin film with a high concentration of oxygen vacancies (<I>δ</I> = 0.12). The obtained results were compared with MR studies for a polycrystal of (Sr<SUB>1 − <I>x</I></SUB>La<SUB><I>x</I></SUB>)(Ru<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>)O<SUB>3</SUB>. These results highlight the crucial role of oxygen stoichiometry in determining the magneto-transport properties in SrRu<SUB>1 − <I>x</I></SUB>Fe<SUB><I>x</I></SUB>O<SUB>3 − <I>δ</I></SUB> thin films.</P>
Dash Devi Prasad,Sethi Narayan,Barik Paresh Chandra 한국국제경제학회 2023 International Economic Journal Vol.37 No.4
Does foreign aid impede or catalyze human development in South and South-East Asia post-1990s? We argue that foreign aid impacts human development negatively in the region overall due to the structural differences in infrastructure development, democratic regimes, patterns of external debt, trading intensity and other macroeconomic factors. Our empirical evidence further justifies that other than aid, improvements in infrastructure sectors and quality of democratic settings beget human development in the region. Considering further angles of external debt and domestic investment into the picture, we find that rising external debt negates, improves domestic investment and accelerates human development. While comparing both regions, we find a noticeable difference in the impacts of macro-institutional factors on human development. However, the impacts of aid on human development remain insignificant.