Facile synthesis of monodispersed 3D hierarchical Fe₃O₄ nanostructures decorated r-GO as the negative electrodes for Li-ion batteries

Kumar, S. Rajesh,Kim, Jong Guk,Viswanathan, C.,Kim, Won Bae,Selvan, R. Kalai,Ponpandian, N. Elsevier 2018 Materials research bulletin Vol.97 No.-

<P><B>Abstract</B></P> <P>One-pot solvothermal process is adopted to develop, 3D hierarchical Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles supported 2D reduced graphene oxide sheets (Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO) as possible negative electrodes for lithium ion batteries. The synthesis parameters are optimized to prepare agglomeration-free Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures with uniform size and shape on r-GO. The field emission scanning electron microscopic (FESEM) image reveals that the 3D hierarchical Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures are uniformly decorated on r-GO. The physicochemical and functional properties of Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO are systematically investigated using various techniques. The fabricated Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO electrode delivers an initial discharge capacity of 1221mAhg<SUP>−1</SUP> at a current density of 100mAg<SUP>−1</SUP> and retains the specific capacity of 1560mAhg<SUP>−1</SUP> after 100 cycles. Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO significantly enhances cyclic performance, when compared with bare Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles due to the uniform distribution of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles on the graphene sheet with the more number of electrochemically active sites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Monodispersed Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures with different shapes synthesized by solvothermal method. </LI> <LI> The fabricated Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO electrode delivers an initial discharge capacity of 1221mAhg<SUP>−1</SUP> at 100mAhg<SUP>−1</SUP>. </LI> <LI> Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO significantly enhances the cyclic stability and rate capability than bare Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A note on vertex pair sum $k$-zero ring labeling

Antony Sanoj Jerome,K.R. Santhosh Kumar,T.J. Rajesh Kumar 한국전산응용수학회 2024 Journal of applied mathematics & informatics Vol.42 No.2

Let $G=(V,E)$ be a graph with $p$-vertices and $q$-edges and let $R^{\circ}$ be a finite zero ring of order $n$. An injective function $f:V(G)\to \{r_1,r_2,\ldots,r_k\}$, where $r_i\in R^\circ$ is called vertex pair sum $k$-zero ring labeling, if it is possible to label the vertices $x\in V$ with distinct labels from $R^{\circ}$ such that each edge $e=uv$ is labeled with $f(e=uv)=[f(u)+f(v)] \pmod n$ and the edge labels are distinct. A graph admits such labeling is called vertex pair sum $k$-zero ring graph. The minimum value of positive integer $k$ for a graph $G$ which admits a vertex pair sum $k$-zero ring labeling is called the vertex pair sum $k$-zero ring index denoted by $\psi_{pz}(G)$. In this paper, we defined the vertex pair sum $k$-zero ring labeling and applied to some graphs.

Substituted <i>N</i> -(Biphenyl-4′-yl)methyl ( <i>R</i> )-2-Acetamido-3-methoxypropionamides: Potent Anticonvulsants That Affect Frequency (Use) Dependence and Slow Inactivation of Sodium Channels

Lee, Hyosung,Park, Ki Duk,Torregrosa, Robert,Yang, Xiao-Fang,Dustrude, Erik T.,Wang, Yuying,Wilson, Sarah M.,Barbosa, Cindy,Xiao, Yucheng,Cummins, Theodore R.,Khanna, Rajesh,Kohn, Harold American Chemical Society 2014 Journal of medicinal chemistry Vol.57 No.14

<P/><P>We prepared 13 derivatives of <I>N</I>-(biphenyl-4′-yl)methyl (<I>R</I>)-2-acetamido-3-methoxypropionamide that differed in type and placement of a R-substituent in the terminal aryl unit. We demonstrated that the R-substituent impacted the compound’s whole animal and cellular pharmacological activities. In rodents, select compounds exhibited excellent anticonvulsant activities and protective indices (PI = TD<SUB>50</SUB>/ED<SUB>50</SUB>) that compared favorably with clinical antiseizure drugs. Compounds with a polar, aprotic R-substituent potently promoted Na<SUP>+</SUP> channel slow inactivation and displayed frequency (use) inhibition of Na<SUP>+</SUP> currents at low micromolar concentrations. The possible advantage of affecting these two pathways to decrease neurological hyperexcitability is discussed.</P>

Recommended girth weld spacing on process pipe

Rajesh S.R.(라제쉬),Chang-Min Hyun(현충민) 대한용접·접합학회 2019 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2019 No.5

Thermal Deformation Analysis Methodology Development for Inconel Overlaying

Rajesh S.R.,Yoo JinSun,Park JungGoo,Choi DooJin 대한용접·접합학회 2022 대한용접·접합학회지 Vol.40 No.2

Overlaying of Inconel on carbon steel base material is widely used in offshore and shipbuilding. The prediction of the overlay related deformation is important to accurately carry out this work with minimum loss and maximum profit. So, in this research, a detailed experimental study on the variation of the weld deposit and the HAZ area while overlay FCAW welding with carbon steel wire as well as Inconel wire on carbon steel plate was carried out and finally, with Inconel Strip to observe the material related and heat input related factor associated with overlay welding. Using this modified heat input and material related values as scale factor is applied to (Strain as Direct Boundary condition) SDB method which is presently applied for welding deformation analysis of large ship block in our shipyard. Based on this research outcome, the overlay welding related deformation was accurately predicted. By predicting the deformation accurately, optimum thickness (always above design thickness) of overlay could be ap- plied and thus reduce the grinding related man-hour to a great extend in this process.

Shunt Active Filter for Multi-Level Inverters Using DDSRF with State Delay Controller

Rajesh, C.R.,Umayal, S.P. The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

The traditional power control theories for the harmonic reduction methods in multilevel inverters are found to be unreliable under unbalanced load conditions. The unreliability in harmonic mitigation is caused by voltage fluctuations, non-linear loads, the use of power switches, etc. In general, the harmonics are reduced by filters. However, such devices are an expensive way to provide a smooth and fast response to secure power systems during dynamic conditions. Hence, the Decoupled Double Synchronous Reference Frame (DDSRF) theory combined with a State Delay Controller (SDC) is proposed to achieve a harmonic reduction in power systems. The DDSRF produces a sinusoidal harmonic that is the opposite of the load harmonic. Then, it injects this harmonic into power systems, which reduces the effect of harmonics. The SDC is used to reduce the delay between the compensation time for power injection and the generation of a reference signal. The proposed technique has been simulated using MATLAB and its reliability has been verified experimentally under unbalanced conditions.

Parameterization of Rain Induced Surface Roughness and Its Validation Study Using a Third Generation Wave Model

R. Rajesh Kumar,B. Prasad Kumar,D. Bala Subrahamanyam 한국해양과학기술원 2009 Ocean science journal Vol.44 No.3

The effect of raindrops striking water surface and their role in modifying the prevailing sea-surface roughness is investigated. The work presents a new theoretical formulation developed to study rain-induced stress on sea-surface based on dimensional analysis. Rain parameters include drop size, rain intensity and rain duration. The influences of these rain parameters on young and mature waves were studied separately under varying wind speeds, rain intensity and rain duration. Contrary to popular belief that rain only attenuates surface waves, this study also points out rain duration under certain condition can contribute to wave growth at high wind speeds. Strong winds in conjunction with high rain intensity enhance the horizontal stress component on the sea-surface, leading to wave growth. Previous studies based on laboratory experiments and dimensional analysis do not account for rain duration when attempting to parameterize sea-surface roughness. This study signifies the importance of rain duration as an important parameter modifying sea-surface roughness. Qualitative as well quantitative support for the developed formulation is established through critical validation with reports of several researchers and satellite measurements for an extreme cyclonic event in the Indian Ocean. Based on skill assessment, it is suggested that the present formulation is superior to prior studies. Numerical experiments and validation performed by incorporating in state-of-art WAM wave model show the importance of treating rain-induced surface roughness as an essential pre-requisite for ocean wave modeling studies. The effect of raindrops striking water surface and their role in modifying the prevailing sea-surface roughness is investigated. The work presents a new theoretical formulation developed to study rain-induced stress on sea-surface based on dimensional analysis. Rain parameters include drop size, rain intensity and rain duration. The influences of these rain parameters on young and mature waves were studied separately under varying wind speeds, rain intensity and rain duration. Contrary to popular belief that rain only attenuates surface waves, this study also points out rain duration under certain condition can contribute to wave growth at high wind speeds. Strong winds in conjunction with high rain intensity enhance the horizontal stress component on the sea-surface, leading to wave growth. Previous studies based on laboratory experiments and dimensional analysis do not account for rain duration when attempting to parameterize sea-surface roughness. This study signifies the importance of rain duration as an important parameter modifying sea-surface roughness. Qualitative as well quantitative support for the developed formulation is established through critical validation with reports of several researchers and satellite measurements for an extreme cyclonic event in the Indian Ocean. Based on skill assessment, it is suggested that the present formulation is superior to prior studies. Numerical experiments and validation performed by incorporating in state-of-art WAM wave model show the importance of treating rain-induced surface roughness as an essential pre-requisite for ocean wave modeling studies.

The Effect of Welding Residual Stress on Whole Structure with T-Joint RHS

Rajesh S. R.,Bang H. S.,Kim H. The Korean Welding and Joining Society 2005 International journal of Korean welding society Vol.5 No.1

In the field of welding the mechanical behavior of a welded structure under consideration may be predicted via heat transfer and welding residual stress analysis. Usually such numerical analyses are limited to small regular mesh models or test specimens. Nevertheless, there is very few strength assessment of the whole structure that includes the effect of welded residual stress. The present work is based on the specialized finite element codes for the calculation of nonlinear heat transfer details and residual stress including the external load on the welded RHS (Rectangular Hollow Section) T-joint connections of the whole structure. First the thermal history of the combined fillet and butt-welded T-joint equal width cold-formed RHS are calculated using nonlinear finite element analysis (FEA) considering the quarter model of the joint. Then using this thermal history the residual stress around the joints has been evaluated. To validity the FEA result, the calculated residual stresses were compared with the available experimental results. The residual stress obtained from the quarter model is mapped to the full model and then to the whole structure model using FEM codes. The results from the FEM codes were exported to the commercial package for visualization and further analysis applying loads and boundary conditions on the whole structure. The residual stress redistribution along with the external applied load is examined computationally.

Efficient methods for the synthesis of 5-(4-[¹⁸F]fluorophenyl)-10,15,20-tris(3-methoxyphenyl)porphyrin as a potential imaging agent for tumor

Kavali, Rajesh R.,Chul Lee, Byung,Seok Moon, Byung,Dae Yang, Seung,Soo Chun, Kwon,Woon Choi, Chang,Lee, Chang-Hee,Yoon Chi, Dae John Wiley Sons, Ltd. 2005 Journal of labelled compounds & radiopharmaceutica Vol.48 No.10

<P>F-18-labeled porphyrins, the potential tracing and detecting agents for tumor have been synthesized and characterized by two convenient routes: one is a mixed aldehyde condensation, which involves acid-catalyzed condensation of pyrrole, m-anisaldehyde and 4-[<SUP>18</SUP>F]fluorobenzaldehyde. The other is the acid-catalyzed condensation of tetrapyrrane with 4-[<SUP>18</SUP>F]fluorobenzaldehyde. The synthetic methodologies including solvents, reaction concentrations and catalysts are optimized for radiolabeled porphyrins. The methods also provide the desired product in reasonable radiochemical yield (20–26%) compared with those of cold chemical synthesis (1–3%) and with high radiochemical purity (>95%). The methods described here would be effective and convenient ways to produce radiolabeled porphyrin. Copyright © 2005 John Wiley & Sons, Ltd.</P>

An Intelligent 2D Secret Share Construction using Visual Cryptography for Secure Transmission

( N. Rajesh Kumar ),( R. Bala Krishnan ),( G. Manikandan ),( N. R. Raajan ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.7

Data Security is the most challenging area in Internet communication, where most of the secret sharing schemes are proposed for binary images. But still it lacks in providing security for data communication, especially in image transmission. Traditional visual cryptography scheme generate meaningless diwies and the reconstruction phase leads to quality degradation over the secret image. In this work, an intelligent two dimensional secret share construction scheme is proposed. A secret image is expanded into n diwies with the choice of scheme selection. By Stacking all the qualified diwies to revert the secret image without content loss and less than s* - 1 shares could not reveal any information about the secret image. The experimental results emphasize that the proposed secret share scheme is highly secured for image transmission.