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Das, Sanjeev,Lim, N.S.,Kim, H.W.,Park, C.G. Elsevier 2010 MATERIALS AND DESIGN Vol.31 No.6
<P><B>Abstract</B></P><P>In the present investigation the Al–5.5Mg–0.02Ti alloy produced by twin roll casting (TRC) process (varying rolling speed, i.e., 3, 4, and 5rpm) has been subjected to heat treatment for microstructure modification. Grain coarsening at the center of the strip has been observed during heat treatment process. Homogeneous microstructure of the alloys has been achieved by heat treatment process, and it has been found that the time to achieve homogeneous structure depends on the rolling speed. Transmission electron microscope (TEM) studies revealed that undesired Mg rich phase (Mg<SUB>5</SUB>Al<SUB>8</SUB>) has been successfully eliminated by heat treatment process. Fine and equi-axed grains in the alloys obtained by heat treatment process shows high strength and elongation.</P>
Sahu Deepak Kumar,Das Amlan,Das Sanjeev,Mallik Archana 한국탄소학회 2024 Carbon Letters Vol.34 No.1
The current study explores the possibility of graphene as a protective layer on the zinc substrate through an optimized electrophoretic deposition process. Graphene has been synthesized from H2SO4, HNO3, and HClO4 solutions by an electrochemical exfoliation route. This method is known for providing a scalable and economical approach to the synthesis of graphene. The exfoliated graphene nano-sheets were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, UV–visible, and field emission scanning electron microscope to evaluate its properties. The three different synthesized forms of graphene nano-sheets were electrophoretically deposited onto Zn substrates at two different potentials. Scratch testing was employed to check the adhesion quality of the coatings. The corrosion behaviour of Zn and graphene-coated Zn substrates was studied in borate buffer and 3.5 wt% NaCl solutions through potentiodynamic polarization and electrochemical impedance spectroscopy. It was observed that graphene synthesized from H2SO4 exhibited superior anti-corrosion properties in comparison to others.
Nam Suk Lim,Chan Woo Bang,Sanjeev Das,Hyun Woo Jin,Raghavan Ayer,박찬경 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1
In the present study, the influence of tempering temperature on the microstructural evolution and prior austenite grain boundary segregation of AISI 4340 steels was investigated by transmission electron microscope and atom probe. The transmission electron microscopy results showed a variation in the microstructure and the morphology of carbides with a change in tempering temperature. Additionally, the chemical compositions of the prior austenite grain boundaries and carbides were quantified by atom probe tomography. An increase in the tempering temperature led to a decrease in the amount of carbon segregated at the prior austenite grain boundary from 7.9 to 1.3 at.%. It was found that a higher tempering temperature can accelerate the diffusion of carbon from the prior austenite grain boundary into carbide. However, phosphorus atoms were segregated mainly at the prior austenite grain boundary in steel tempered at 400 °C (up to 0.18 at.%). It was found that formation of film-like carbide and phosphorus segregation along the prior austenite grain boundary is the main cause of embrittlement in steel tempered at 400°C.
Deepak Patel,Prasenjit Biswas,Anil Kumar,Hiren R. Kotadia,Archana Mallik,Sanjeev Das 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
The present investigation focuses on grain refinement in pure aluminum and its alloy under mechanical stirring with a verylow degree of forced convection of 800 rpm as compared to reported values of up to 8000 rpm during direct chill castingprocess (DC). Commercially pure aluminum (99.7%) and Al6082 alloy billets were fabricated in an in-house designed DCcasting simulator. Mechanical forced convection (MFC) was applied to the melt during casting by a common four-bladedimpeller. The microstructural properties of the as-cast billets have been analysed to study the effect of MFC during casting andsolidification. The structure of both Al and its alloy is found to be refined in presence of MFC as compared to conventionalDC. A combination of simulation, experimental and theoretical approaches has been used to determine the effect of MFCin melt-temperature distribution to propose the mechanism of grain refinement. It has been observed that MFC prominentlyreduces the temperature gradient and extends undercooling time, resulting in fine grain structure.
Mutation analysis and characterisation of F9 gene in haemophilia- B population of India
Sujayendra Kulkarni,Rajat Hegde,Smita Hegde,Suyamindra S. Kulkarni,Suresh Hanagvadi,Kusal K. Das,Sanjeev Kolagi,Pramod B. Gai,Rudragouda Bulagouda 대한혈액학회 2021 Blood Research Vol.56 No.4
Background Hemophilia B (HB) is an X-linked bleeding disorder resulting from coagulation factor IX defects. Over 3,000 pathogenic, HB-associated mutations in the F9 gene have been identified. We aimed to investigate the role of F9 variants in 150 HB patients using sequencing technology. Methods F9 gene sequences were amplified from peripheral blood-derived DNA and sequenced on an Applied Biosystems (ABI) 3500 Sanger sequencing platform. Functional and structural predictions of mutant FIX were analyzed. Results Among 150 HB patients, 102 (68%), 30 (20%), and 18 (12%) suffered from severe, moderate, and mild HB, respectively. Genetic analysis identified 16 mutations, including 3 novel mutations. Nine mutations (7 missense and 2 stop-gain) were found to be pathogenic. Only 3 mutations (c.127C>T, c.470G>A, and c.1070G>A) were associated with different severities. While 2 mutations were associated with mild HB cases (c.304C>T and c.580A>G), 2 (c.195G>A and c.1385A>G) and 3 mutations (c.223C>T, c.1187G>A, and c.1232G>A) resulted in moderate and severe disease, respectively. Additionally, 1 mutation each was associated with mild-moderate (c.*1110A>G) and mild-severe HB disease (c.197A>T), 4 mutations were associated with moderate-severe HB cases (c.314A>G, c.198A>T, c.676C>T, and c.1094C>A). FIX concentrations were lower in the mutated group (5.5±2.5% vs. 8.0±2.5%). Novel p.E66D and p.S365 mutations were predicted to be pathogenic based on changes in FIX structure and function. Conclusion Novel single nucleotide polymorphisms (SNPs) largely contributed to the pathogenesis of HB. Our study strongly suggests that population-based genetic screening will be particularly helpful to identify risk prediction and carrier detection tools for Indian HB patients.