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.

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.

Some Properties of q-Distance Energy

M. R. Rajesh Kanna,R. Pradeep Kumar,Soner Nandappa D,Ismail Naci CANGUL 장전수학회 2020 Advanced Studies in Contemporary Mathematics Vol.30 No.2

Graphs are nowadays frequently used in modelling. Especially the sub area of graph theory called the molecular graph theory deals with physicochemical proper- ties of chemical substances by means of mathematical methods. Three main methods to study graphs mathematically are to make use of the vertex degrees, distances and matrices. The classical graph energy was dened 1978 by I. Gutman and has a large number of applications in chemistry and physics. In this paper, a recently dened new type of energy called q-distance energy by means of distances and matrices is studied and q-distance energies of star graph, complete graph, crown graph, cocktail party graph, complete bipartite graph, windmill graph are computed.

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.

Radioprotective and Antioxidant Activity of Fractionated Extracts of Berries of Hippophae rhamnoides

Rakesh Kumar Sharma,Raman Chawla,Rajesh Arora,Shikha Singh,Ravinder Kumar Sagar,Raj Kumar,Ashok Sharma,Manju L. Gupta,Surender Singh,Jagdish Prasad,Haider A. Khan,Anand Swaroop,A.K. Sinha,A.K. Gupta,R 한국식품영양과학회 2007 Journal of medicinal food Vol.10 No.1

Plants are an abundant source of medicinal compounds, some of which are useful in combating free radical-1002 (flavonoid-poor fraction) of Hippophae rhamnoideswere screened on the basis of their reducing power in the aqueousphase. REC-1001 was selected for further study, since it exhibited 27.38 times higher antioxidant activity than REC-1002.REC-1001 also showed significant (P. .05) membrane protection potential at 50 .g/mL, which was attributed to its abilityto scavenge peroxyl radicals (64.82. 1.25% scavenging within 1,440 min). A significant (P. .05) difference of 67.02% infree radical scavenging activity at 1,000 ng/mL between REC-1001 and vitamin E demonstrated the extract fraction’s worthc-tion. Further, REC-1001 was found to be nontoxic up to 200 mg/kg of body weight. This research suggests that the REC-1001 fraction of H. rhamnoidesextract is a safe and effective antioxidant nutraceutical product.

SYNTHESIS OF CATALYST-FREE AND TEMPERATURE CONTROLLED MORPHOLOGIES OF CARBON NANOSTRUCTURES USING BOTANICAL HYDROCARBON: CASTOR OIL

RAJESH KUMAR,R. S. TIWARI,O. N. SRIVASTAVA 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.3

Castor oil (combination of fatty acids) precursor containing hydrocarbon with less amount of oxygen is used first time for synthesis of different carbon nanostructures (i.e., agglomerated carbon nanoparticles, carbon nanobeads and carbon tubular structure). The agglomerated carbon nanoparticles, carbon nanobeads and carbon tubular structure were synthesized by applying CVD method at different temperature using castor oil as new carbon precursor without any catalyst. The synthesis of carbon nanostructure is free from additional catalyst as this hydrocarbon (castor oil) is cheap with abundant sources of carbon. The effect of pyrolysis temperatures on the size, quality and quantity of the synthesized carbon shape were investigated. Interestingly, the morphology of the carbon nanostructures can be controlled in shape from agglomerated carbon nanoparticle to nanobeads to carbon tubular structure just by increasing the temperature from 750°C to 800°C to 850°C, respectively. These nanobeads are chains of uniform size of graphitized carbon spheres. These chains comprised individual carbon particles size of ~ 450 nm. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR).

Fabrication of Gas Metal Arc Welding Based Wire Plus Arc Additive Manufactured 347 Stainless Steel Structure: Behavioral Analysis Through Experimentation and Finite Element Method

R. Pramod,S. Mohan Kumar,A. Rajesh Kannan,N. Siva Shanmugam,Reza Tangestani 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1

Wire plus arc additive manufacturing (WAAM) technology is utilized to fabricate a 347 stainless steel (SS347) plate usingthe gas metal arc welding process. The tensile properties of the WAAM plate revealed enhanced strength in comparisonwith the wrought alloy SS347. The microhardness and the ferrite measurement along the building direction (BD) were inthe range of 265–226 HV0.5 and 2.2–5.1 FN (Ferrite number), respectively. The microstructural features were comprehensively examined using electron backscatter difraction (EBSD) analysis and the Inverse pole fgure (IPF) maps revealed astrong <001> texture along the BD. Also, well-aligned equiaxed and columnar dendrites with a lower fraction of niobiumcarbide (NbC) was noticed in the microstructures of the as-built WAAM plate. A three-dimensional fnite element modelwas developed to simulate the build-up of a WAAM plate. Goldak heat source is used to model heat fux in thermal analysis,and the temperature distributions were predicted. Further, residual stress and plastic strain distributions were examined atvarious stages of the WAAM process.

WHO Class of Obesity Influences Functional Recovery Post-TKA

Rajesh N Maniar,Parul R Maniar,Tushar Singhi,Bharat Kumar Gangaraju 대한정형외과학회 2018 Clinics in Orthopedic Surgery Vol.10 No.1

Background: No study in the literature has compared early functional recovery following total knee arthroplasty (TKA) in the obese with the nonobese using World Health Organization (WHO) classes of obesity. Our aim was to compare functional scores and flexion post-TKA in each class of obesity as per WHO classification against a matched control group of nonobese patients. Methods: Records of 885 consecutive primary TKA patients (919 knees) operated by a single surgeon were reviewed. The first 35 knees in each class I, class II and class III obesity group during the study period were then matched with a similar number of knees in nonobese TKA patients during the same period. Functional scores recorded pre- and postoperatively at 3 months and 1 year were Western Ontario and McMaster Osteoarthritis Index (WOMAC), Short-Form Health Survey (SF-12) score, and Knee Society Score (KSS). Results: There was no difference in any parameter between the class I obese and matched nonobese at any assessment point. In the class II obese, as compared to the nonobese, there was no difference in any parameter preoperatively and 3 months postoperatively. However, 1 year postoperatively, the SF-12 physical subscore was lower in the class II obese than the nonobese (44.7 vs. 48.6, p = 0.047) and the WOMAC score was significantly higher (15.8 vs. 9.7, p = 0.04). In the class III obese, the WOMAC score was significantly higher than the nonobese (58.1 vs. 44.3, p < 0.001 preoperatively; 15.7 vs. 8.1, p = 0.005 at 1 year) and KSS was significantly lower (83.5 vs. 96.5, p = 0.049 preoperatively; 172 vs. 185; p = 0.003 at 1 year). Knee flexion was significantly lower in the class III obese than the nonobese (95 vs. 113; p < 0.001 preoperatively; 120 vs. 127; p = 0.002 at 1 year). Conclusions: The class I obese can expect good early and late functional recovery as the nonobese. The class II obese can expect comparable early functional recovery as the nonobese but their late function may be lesser. The class III obese would have poorer functional scores and lesser knee flexion postoperatively compared to the nonobese. However, compared to their own preoperative status, there is definite improvement in function and knee flexion.

CFD Analysis of a Micro Shock Tube Flow

Arun Kumar.R,Rajesh.G,H.D. Kim 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

Past few decades have witnessed the growing importance of micro shock tube in various engineering applications like micro combustion, micro turbines, MEMS, particle delivery devices etc. Owing to its large surface area to volume ratio, micro shock tube exhibits different flow characteristics from the well established macro shock tube flows. One of the major changes involved in such kind of small scale flows is that the Knudsen Number becomes high enough to produce the molecular effects prominent. In these situations the operating pressure becomes a crucial factor in controlling the flow since a low operating pressure will induce rarefaction effects which makes the wall attached fluid slip and have a higher temperature than the wall value. Navier- Stokes equations becomes incompatible to predict such flows and depending on the Knudsen Number, N-S equations with slip wall conditions or molecular dynamics study are needed to be used to mathematically model the flow physics. In the present study, unsteady axi-symmetric CFD method has been applied to simulate the micro shock tube flow. Maxwells slip wall conditions were used to simulate the rarefaction effects produced by the large Knudsen Number. A comparative study on the unsteady behaviors of shock wave and contact discontinuity under different diameters and initial pressure conditions were, in detail, analyzed. The results obtained show much more attenuation of shock wave, compared with macro-shock tubes.