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Ravi Kant,Keshav Kumar Saini,Ravindra Kumar Upadhyay,Yogender Singh,Y. Veera Manohara Reddy,Shishu Pal Singh,M. Abdul Kareem,K. R. Dasegowda,H. Prabhavati,Rakesh Kumar,박종필,Lalita S. Kumar 한국생물공학회 2023 Biotechnology and Bioprocess Engineering Vol.28 No.5
To explore novel and potent compounds with anticancer activity, two series of 1H-1,2,3-triazole tethered dibenzosuberane conjugates (5a-i and 5j-n) were synthesized using a linear and convergent approach. The synthesized novel compounds were screened for their in vitro antiproliferative activity against HepG2 cell lines using the MTT assay to explore their binding interactions with the 5EQG protein. IC50 values revealed that the most active combination against HepG2 cell lines was triazole tethered with an ortho chloro-substituted aryl ring (5g) (IC50: 99.64 μg/mL). The other compounds in the series exhibited comparable cytotoxic activities against HepG2 cell lines. The results were substantiated by molecular docking studies. The majority of the compounds demonstrated high binding affinity for the active site of the targeted protein. In addition, in silico drug-likeness prediction by the ADMET method has been explored with these compounds. All synthesized novel derivatives were characterized by mass spectrometry, infrared spectroscopy, 1H-nuclear magnetic resonance (NMR) spectroscopy, and 13C-NMR spectroscopy.
Electrical Properties of Copper Substituted Nickel Ferrites
G. Ravi Kumar,Y. C. Venudhar,A. T. Raghavender,K. Vijaya Kumar 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7
The Ni-Cu ferrites, Ni1−xCuxFe2O4 (0.0 ≤ x ≤ 1.0) were prepared by using the sol-gel method. The X-ray diffraction patterns of all the samples showed the formation of a single-phase spinel structure. The lattice parameter was found to increase with increasing copper concentration. The electrical properties, such as the d. c. conductivity as a function of the temperature, and the dielectric constant, the dielectric loss factor and the dielectric loss tangent as function of the frequency were investigated. The d. c. conductivity was found to increase with increasing temperature in accordance with the Verwey hopping mechanism. The dielectric constant, the dielectric loss factor and the dielectric loss tangent were found to decrease with increasing frequency. The dielectric constant followed the Maxwell-Wagner interfacial polarization. A suitable explanation was given for the frequency and the composition dependences of the dielectric properties.
Ravi Kumar H. S.,Vijay G Goni,Batra Y. K. 대한척추외과학회 2015 Asian Spine Journal Vol.9 No.6
Study Design: The study was conducted on patients who received autologous conditioned serum (ACS) as a line of treatment at the Orthopedics outpatient department of Post Graduate Institute of Medical Education and Research (PGIMER, Chandigarh) from January 2011 to June 2012. Of the 1,224 patients, 20 males or females were included in the study based on the inclusion and exclusion criteria. The institutional board of PGIMER approved the study before it was initiated. Purpose: To study the efficacy of ACS in the treatment of unilateral lumbar radiculopathy. Overview of Literature: Interleukin (IL)-1 appears to be of special importance among the cytokines identified in orthopedic diseases. ACS contains high concentrations of IL-1 receptor antagonist, antagonist to IL-1 in that is a biochemical ‘sensitizer’ of nerve roots in radiculopathy. Methods: We included 20 patients with unilateral lumbar radiculopathy after obtaining informed consent. We prepared ACS as described by Meijer et al. Under bi-planar fluoroscopic imaging in anterior-posterior and lateral views, ACS was administered via epidural perineural technique. Patients in both groups were evaluated by quadruple visual analogue scale, straight leg raising test, revised Oswestry disability index, and 12-Item Short Form of Health Survey before and after epidural injections at 3 weeks, 3 months, and 6 months. Results: There was a statistically significant change in all parameters from pre-injection to first, second, and third follow-up (p <0.001). Conclusions: ACS can modify the disease course in addition to reducing pain, disability and improving general health.
K. Benarji,Y. Ravi Kumar,A. N. Jinoop,C. P. Paul,K. S. Bindra 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3
This paper reports investigation on the effect of heat-treatment on the microstructure, mechanical, tribological and corrosioncharacteristics of laser directed energy deposition (LDED) built stainless steel (SS 316) bulk structures. LDED built SS316 structures are subjected to solution treatment at 1073 K (HT1073) and 1273 K (HT1273) and reduction in ferrite phasewith heat-treatment is observed from microstructure. X-ray diffraction and microstructure shows that the austenite phaseis observed at all conditions and reducing ferrite phase intensity is noticed with an increase in heat-treatment temperature. Improvement in the plasticity retaining capacity and reduction in micro-hardness by 72.8% and 6.75% are noticed withheat-treatment, respectively. It is observed that the corrosion rate and specific wear rate increases after heat-treatment. Themaximum specific wear rate of 0.19375 × 10–4 mm3/min is observed in the HT1273 sample with wide and deep groovesnoticed on the worn out surface of heat-treated samples. The SEM images of wear track is characterized with abrasive wearmechanism for as-built sample, while heat-treated samples shows plastic deformation, followed by spalling effect. The workpaves a way to understand the effect of heat-treatment on LDED built SS 316 bulk structures.
Ferromagnetic Properties of Bulk Fe-doped CeO2 Dilute Magnetic Semiconductors
S. K. Sharma,M. Knobel,C. T. Meneses,샤런드라쿠마르,Y. J. Kim,B. H. Koo,이찬규,D. K. Shukla,Ravi Kumar 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3
Polycrystalline Fe-doped Ce1−xFexO2−δ has been fabricated by using the standard solid state reaction technique in the concentration range 0 ≤ x ≤ 0.05. Reitveld refinement of the X-ray diffraction patterns shows a pure CeO2 phase when x ≤ 0.03, and the appearance of a secondary impurity phase of Fe2O3 beyond that. Furthermore, by doping Fe into CeO2 powder, the ferromagnetism can be significantly enhanced to a maximum value for x = 0.03, but degrades quickly with further doping. Magnetization results reveal that the large room-temperature ferromagnetism observed in Fe-doped CeO2 powder originates from a combined effect of oxygen vacancies and transition metal doping.
S. Das,S. Sanyal,P. Halder,A. Varma,Y. Ravi Kumar,S. Mandal 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8
In this study, the oxidation response of a T91 steel in dry air environment has been investigated by performing cyclic oxidationtests at 873, 973 and 1073 K for a total duration of 1000 h with intermediate intervals. The temperature range for thisstudy is chosen to be higher than the operating temperature range of the alloy to accelerate the oxidation kinetics. Developinga comprehensive understanding of the mechanisms and kinetics involved at such accelerated oxidation environmentswould help to formulate better strategies for countering oxidation related failure events. The results of this study showedthat the oxidation rate is greatly influenced by temperature as well as exposure time, and follows a near-parabolic rate law. Characterization of the oxide scales revealed formation of dual oxide layers where the inner layer is primarily rich in Feand Cr, and the outer layer in Fe only. At 1073 K, formation of cracks can be observed in the oxide scales after 24 h, whichbecame more severe after 1000 h. The oxidation kinetics, when fitted to an Arrhenius type equation, can be associated withactivation energy (Q) and parabolic rate constant (kp) values. The Q values lie within 104–109 kJ/mol, whereas the kp valuesincrease with temperature due to increase in the reaction rate. The kinetic equation developed based on the Q and kp valuescan be used to predict the thickness (inner, outer and overall) of the oxide scales in T91 steel at any temperature and timewithin the studied ranges.
P. Thakur,W. K. Choi,K. H. Chae,J.-Y. Kim,R. J. Choudhary,Shailja Tiwari,Ram Prakash,D. M. Phase,Ravi Kumar 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6
We report on the growth and the characterization of magnetite thin films grown on Si(111) substrates by using pulsed laser deposition at different substrate temperatures (TS = 350, 450 and 550 ℃) by performing X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) experiments. The O K− and Fe L3,2−edge XAS spectra reveal that the couplings of the O 2p with Fe 3d orbitals highly rely on the growth processes. The XMCD data of well-characterized thin films exhibit characteristic contributions from Fe3+ A ions in tetrahedral sites and Fe2+ B and Fe3+ B ions in octahedral sites and have spectral features similar to those of the Fe3O4 single crystal. The temperature dependence of the XMCD line shape features remain unchanged below and above the Verwey transition. These investigations demonstrate the experimental conditions for controlled growth of Fe3O4 thin films on Si(111) substrates and suggest that the Fe3O4/Si(111) might a promising spintronic materials for future technology.