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Effect of Lanthanum Addition on Grain Refinement and Mechanical Properties of Mg–9Li–3Al Alloy
P. Dinesh,S. P. KumareshBabu,S. Natarajan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
The impact of lanthanum addition on the microstructural changes and mechanical characteristics of Mg–9Li–3Al + xLaalloys are studied. The alloys are fabricated through a liquid metallurgy route involving stir casting by an electrical resistancefurnace. The microstructural analysis showed that the as-cast alloys primarily comprises of α-Mg and β-Li phases. Irregular distribution of Al–Li lamellar and some granular fragments MgLi2Alobserved over the magnesium-rich α-phaseand lithium-rich β-phase. The influence of lanthanum addition to the alloy system leads to grain refinement by formingAl11La3and Al4Laintermetallics. Among the series of cast alloys, the Mg–9Li–3Al–1La alloy exhibits excellent ultimatetensile strength—178 MPa with 10.2% elongation. Addition of 1.5 wt% La and beyond tends to coarsen the grains leadingto a reduction in mechanical strength. Hot extruded Mg–9Li–3Al–1La alloy exhibited more refinement in the microstructureand breakdown of intermetallic (Al4La and Al11La3)is observed. A significant improvement in the UTS values around 39%displayed by the Mg–9Li–3Al–1La alloy extruded at a ratio of 25:1.
Durable keratin-based bilayered electrospun mats for wound closure
Singaravelu, Sivakumar,Ramanathan, Giriprasath,Muthukumar, Thangavelu,Raja, M. D.,Nagiah, Naveen,Thyagarajan, Sitalakshmi,Aravinthan, Adithan,P., Gunasekaran,Natarajan, T. S.,V. N. Geetha Selva, Ganga The Royal Society of Chemistry 2016 Journal of Materials Chemistry B Vol.4 No.22
<P>A bilayered nanofibrous scaffold with rapid wound healing properties is found to be suitable for tissue regeneration applications. The objective of this study is to reveal the fabrication of a poly(3-hydroxybutyric acid) (P)-gelatin (G) nanofibrous mat through electrospinning, with a horn keratin-chitosan-based biosheet (KC) as a bilayered nanofibrous scaffold. The mupirocin (D)-loaded horn KC biosheet (KCD) acts as the primary layer over which PG nanofibers were electrospun to act as the secondary layer. It is shown that this engineered bilayered nanofibrous scaffold material (KC-PG) should fulfill the functions of the extracellular matrix (ECM) by elucidating its function<I>in vitro</I>and<I>in vivo</I>. The bilayered nanofibrous scaffold was designed to exhibit improved physiochemical, biological and mechanical properties, with better swelling and porosity for enhanced oxygen permeability, and it also exhibits an acceptable antibacterial property to prevent infection at the wound site. The bilayered nanofibrous scaffold assists in better biocompatibility towards fibroblast and keratinocyte cell lines. The morphology of the nanofibrous scaffold aids increased cell adhesion and proliferation with cell material interactions. This was elucidated with the help of<I>in vitro</I>fluorescence staining against both cell lines. The bilayered KCD-PG nanofibrous scaffold material gives accelerated wound healing efficiency during<I>in vivo</I>wound healing. The results showed the regulation of growth factors with enhanced collagen synthesis, thereby helping in faster wound healing.</P>
Phenotypic Characterization of Genetically Lowered Human Lipoprotein(a) Levels
CHARGE-Heart Failure Consortium,CARDIoGRAM Exome Consortium,Emdin, C.A.,Khera, A.V.,Natarajan, P.,Klarin, D.,Won, H.H.,Peloso, G.M.,Stitziel, N.O.,Nomura, A.,Zekavat, S.M.,Bick, A.G.,Gupta, N.,Asselta Elsevier Inc. 2016 Journal of the American College of Cardiology Vol.68 No.25
<P>CONCLUSIONS Beyond CHD, genetically lowered Lp(a) levels are associated with a lower risk of peripheral vascular disease, stroke, heart failure, and aortic stenosis. As such, pharmacological lowering of plasma Lp(a) may influence a range of atherosclerosis-related diseases. (C) 2016 by the American College of Cardiology Foundation.</P>
Gunniya Hariyanandam, G.,Hyun, D.,Natarajan, P.,Jung, K.D.,Yoon, S. Elsevier Science Publishers 2016 CATALYSIS TODAY - Vol.265 No.-
<P>Heterogenized Ir(III) catalysts were synthesized through the formation of coordination bonds between Ir( III) ions and heptazine-based covalent organic frameworks (COFs). The coordination environment of the Ir(III) ion contained the two heptazinyl nitrogen atoms as well as Cp* and Cl- anions. The heterogeneous catalyst exhibits high CO2 hydrogenation activity (turnover number (TON) = 6400 and turnover frequency (TOF) = 1500 h(-1)). In addition, the sub-micron sized catalyst was easily separated by filtration and the catalytic efficiency of the isolated catalyst was demonstrated over repeated cycles. (C) 2015 Elsevier B.V. All rights reserved.</P>
Assessment of Single Phase Cascaded Multilevel Inverter using Equal and Unequal Amplitude Carriers
P. Sureshpandiarajan,S. P. Natarajan,C. R. Balamurugan,R. Bensraj 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.5
This work presents the comparison of various multicarrier based Pulse Width Modulation (PWM) techniques for the chosen single phase CMLI (Cascaded Multi Level Inverter). In this paper, a single phase symmetrical cascaded multilevel inverter is controlled with sinusoidal, THI (Third Harmonic Injection), Trapezoidal, TAR (Trapezoidal Amalgamated Reference) and Stepped Wave reference with Equal Amplitude Carriers (EAC) and UEAC (Un Equal Amplitude Carriers). The proposed EAC and UEAC are applied for various PWM strategies. The PWM methods used for the analysis are PD (Phase Disposition) PWM, POD (Phase Opposition and Disposition) PWM, APOD (Alternative Phase Opposition and Disposition) PWM, CO (Carrier Overlapping) PWM, PS (Phase Shift) PWM and VF (Variable Frequency) PWM with EAC and UEAC. For all the PWM methods and references the UEAC produces less THD and higher fundamental RMS (Root Mean Square) values except for ma =1. For ma =1 the EAC provides less THD (Total Harmonic Distortion) and higher fundamental RMS (Root Mean Square) values for all the PWM methods and references. To validate the developed technique, simulations are carried out through MATLAB/SIMULINK.
P. Geetha,S. Krishnan,R.K. Natarajan,V. Chithambaram 한국물리학회 2015 Current Applied Physics Vol.15 No.3
L-Valine Ferric Chloride single crystal is a new semi organic nonlinear optical material. It has been grown from a mixture of aqueous solutions of L-Valine and Ferric Chloride by slow evaporation solution growth technique at room temperature for the first time. Single crystal XRD analysis revealed that the crystal system belongs to Cubic P with cell parameters are a = 24.38 Å, b = 24.38 Å, c = 24.38 Å and volume is 14,485 Å3. The UV spectrum shows existence of wide transparency window suitable for optoelectronic applications. Thermal stability and melting temperature of the as grown crystal was identified from TGDTA analysis. Spectroscopic studies have been carried out for analyzing the presence of functional groups, thermal stability and phase transition of the grown crystal. The dielectric loss and the dielectric constant of the crystals were measured as a function of frequency. Photoluminescence study was carried out for grown crystals and the maximum emission occurs has good optical transmission in the entire visible region. Second harmonic generation (SHG) conversion efficiency has been estimated.
M. Vasudevan,P. S. Ajithkumar,R. P. Singh,N. Natarajan 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.2
Present study investigates the potential of cassava peel and rubber tree bark for the removal of Cr (VI) from aqueous solution. Removal efficiency of more than 99% was obtained during the kinetic adsorption experiments with dosage of 3.5 g/L for cassava peel and 8 g/L for rubber tree bark. By comparing popular isotherm models and kinetic models for evaluating the kinetics of mass transfer, it was observed that Redlich-Peterson model and Langmuir model fitted well (R2 > 0.99) resulting in maximum adsorption capacity as 79.37 mg/g and 43.86 mg/g for cassava peel and rubber tree bark respectively. Validation of pseudo-second order model and Elovich model indicated the possibility of chemisorption being the rate limiting step. The multi-linearity in the diffusion model was further addressed using multi-sites models (two-site series interface (TSSI) and two-site parallel interface (TSPI) models). Considering the influence of interface properties on the kinetic nature of sorption, TSSI model resulted in low mass transfer rate (5% for cassava peel and 10% for rubber tree bark) compared to TSPI model. The study highlights the employability of two-site sorption model for simultaneous representation of different stages of kinetic sorption for finding the rate-limiting process, compared to the separate equilibrium and kinetic modeling attempts.
FUZZY CONTROL OF NEGATIVE OUTPUT LUO RE-LIFT CONVERTER
R.Kayalvizh,S.P Natarajan,S. Ramesh 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
DC-DC converters convert power at one voltage level to power at another voltage level. They are widely used in switched mode power supplies, car auxiliary power supplies, servo motor drives and medical equipments. Because of the effect of parasitic elements, the output voltage and power transfer efficiency of all DC-DC converters are restricted. Luo converter, a new DC-DC converter which overcomes the effect of parasitic elements, is an example of a non-linear timevariant system. In positive output Luo converters, the input and output DC voltages are positive whereas the negative<br/> output Luo converters provide negative output voltage for positive input voltage. Luo converters are also classified as selflift,<br/> re-lift, triple-lift, quadruple-lift and super-lift converters<br/> depending on the magnitude of boosting of output voltage. Conventional controllers cannot generally provide good dynamic performance for power electronic systems which are generally complex. Fuzzy controller works well for these systems. Hence this paper addresses the design and MATLAB simulation of a Fuzzy Logic Controller (FLC) for a negative output Luo re-lift converter. Tests for load regulation and line regulation are carried out using the discretized state-space models of the converter. The proposed FLC maintains the output voltage constant irrespective of line and load<br/> disturbances.