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A SUFFICIENT CONDITION FOR THE INTEGRABILITY OF REES-STANOJEVIĆ SUM
Ram, Babu Department of Mathematics 1979 Kyungpook mathematical journal Vol.19 No.2
We show that the condition S of Sidon is sufficient for the integrability of the limit of Rees-$Stanojevi{\acute{c}$ cosine sums $g_n(x)={\frac{1}{2}}{\limits\sum^{n}_{k=0}}{\Delta}a_k+{\limits\sum^{n}_{k=1}}{\limits\sum^{n}_{j=k}}{\Delta}a_j\;cos\;kx$.
Tetrahexcarbon: A two-dimensional allotrope of carbon
Ram, Babu,Mizuseki, Hiroshi Elsevier 2018 Carbon Vol.137 No.-
<P><B>Abstract</B></P> <P>A two-dimensional structurally stable carbon allotrope is predicted using first-principles calculations. This unique network is composed of tetra and hexa-rings of carbon atoms known as Tetrahexcarbon. Tetrahexcarbon has a quasiparticle (QP) direct band gap of 3.70 eV at Γ , which is closer to the ZnS, a well-known direct bandgap semiconductor. Interestingly, it is dynamically stable and can withstand temperature up to 1000 K, which is confirmed by performing phonon and <I>ab initio</I> molecular dynamics (AIMD) simulations. The mobilities of both electrons and holes in this material are found to be anisotropic. It exhibits extraordinary room temperature in-plane electron mobility of order ∼ <SUP> 10 4 </SUP> <SUP> cm 2 </SUP> <SUP> V − 1 </SUP> <SUP> s − 1 </SUP> , which is an order of magnitude higher than the black phosphorus monolayer ( ∼ <SUP> 10 3 </SUP> <SUP> cm 2 </SUP> <SUP> V − 1 </SUP> <SUP> s − 1 </SUP> ) and two orders of magnitude higher than MoS<SUB>2</SUB> ( ∼ 200 <SUP> cm 2 </SUP> <SUP> V − 1 </SUP> <SUP> s − 1 </SUP> ) monolayer. The optical response of Tetrahexcarbon obtained by applying Bethe-Salpeter equation (BSE) to include excitonic effects on top of the partially self-consistent GW<SUB>0</SUB> calculation. The absorption onsets strongly depend on the light polarization directions indicating Tetrahexcarbon an anisotropic material.</P>
Rambabu N. Reddi,Changbum Jo,Arumugam Sudalai 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.10
This article describes a concise synthesis of two important fragments (tetrahydropyran [THP] and ketone moieties) of the cytotoxic macrolide (+)-neopeltolide in 10 long linear steps in enantiomerically pure form. Asymmetric Keck allylation to install the required C11 and C13 stereocenters, N-heterocyclic carbene (NHC)-catalyzed oxoacyloxylation to functionalize alkenes, and reductive oxa-Michael addition to construct 2,6-difunctionalized THP unit intramolecularly are the important steps in synthetic efforts. Finally, Keck asymmetric allylation and Lewis acid-catalyzed diastereoselective allylation of the aldehyde were sequentially employed to establish the stereocenters at C11 and C13 positions, respectively.
Rambabu Kusuma,V. K. Hanumantha Rao Talari 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.3
Fully Depleted Silicon On Insulator (FDSOI) structures are present-era technology as it has enhanced control over Short Channel Effects in the sub-nanometre regime. This paper studies the analog and radio frequency performance of junctionless FinFET with dual material gate (DMG JLFinFET) based on FDSOI for low power applications. We extracted analog and radio frequency parameters with the variation of fin height (FH = 10 nm to 30 nm) and fin width (FW = 46 nm). The parameters like transconductance (gm), transconductance generation factor, cut-off frequency (fT), intrinsic delay (τ), gate capacitance (Cgg), gate to source capacitance (Cgs), gate to drain capacitance (Cgd), and transconductance frequency product, gain bandwidth product are calculated. At FH = 6 nm all the parameters are increased except time delay which was small decrement. Similarly for FW also all the parameters are improved with increment of fin width except time delay. In contempt Cgd and Cgg are less impact on dimensional variation. From this study it reveals that, in FinFET design, designers have to consider dimensional variations in Anlog/RF parameters and FinFET is suitable candidate for nano scale low power Anlog/RF applications. In this work all these simulations are carried out by Cogenda Visual TCAD.
Rambabu Kuchi,Seunghyun Kim,Vitalii Galkin,Dongsoo Kim 한국자기학회 2021 한국자기학회 학술연구발표회 논문개요집 Vol.31 No.1
NdFeB magnets are widely used in advanced electric vehicles, electric motors for power generators, wind turbine generators, energy conversion systems and many other novel applications. However, the high energy density (BHmax) magnets are needed to utilise them. For this purpose, the NdFeB magnetic particles should prepare with higher magnetic properties which could mainly depends on the Nd<sub>2</sub>Fe<sub>14</sub>B phase purity, crystallinity and microstructure. To wards this direction, we report the cost effective and a facile chemical synthesis including spray drying and reduction-diffusion (RD) process with some modifications [1, 2]. Since the RD process has considerably affected the structural and magnetic properties of Nd-Fe-B particles so the optimization of heat treatments for RD is in high demand. Different heating rates (5, 10, 20, and 30℃/min) to reach annealing temperature (1000℃) of RD and keeping times for the RD process were used to prepare Nd-Fe-B particles. Among them, the sample prepared at 20℃/min heating rate (HR) with a 5 h RD time exhibited superior magnetic properties including the remanence (M<sub>R</sub>) of 125 emu/g, saturation magnetization (M<sub>S</sub>) of 140 emu/g, and (BH)max of 10.66 MGOe. This was ascribed to the narrow particle size distribution, and phase purity with high crystallinity at optimized HR and RD time. Because the HR was controlling the particle nucleation and growth process and keeping time could ensure the completion of the RD process. This present modified RD process will also be useful to prepare other potential hard-magnetic particles.