XFEM for fatigue and fracture analysis of cracked stiffened panels

M.R. Nanda Kumar,A. Ramachandra Murthy,Smitha Gopinath,Nagesh R. Iyer 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

This paper presents the development of methodologies using Extended Finite Element Method (XFEM) for cracked unstiffened and concentric stiffened panels subjected to constant amplitude tensile fatigue loading. XFEM formulations such as level set representation of crack, element stiffness matrix formulation and numerical integration are presented and implemented in MATLAB software. Stiffeners of the stiffened panels are modelled using truss elements such that nodes of the panel and nodes of the stiffener coincide. Stress Intensity Factor (SIF) is computed from the solutions of XFEM using domain form of interaction integral. Paris’s crack growth law is used to compute the number of fatigue cycles up to failure. Numerical investigations are carried out to model the crack growth, estimate the remaining life and generate damage tolerant curves. From the studies, it is observed that (i) there is a considerable increase in fatigue life of stiffened panels compared to unstiffened panels and (ii) as the external applied stress is decreasing number of fatigue life cycles taken by the component is increasing.

A nuetrosophic single acceptance sampling plan with quality parameters

S. Jayalakshmi,M. Gopinath 한국전산응용수학회 2024 Journal of applied mathematics & informatics Vol.42 No.1

In the Quality Control and inspection processes, the use of attribute sampling strategies is crucial. In this study, we incorporate the neutrosophic fuzzy acceptance sampling plan method to present a fresh approach to attribute sampling plans. Utilizing the benefits of neutrosophic fuzzy sets, the proposed sampling plan method models and assesses the acceptance standards for attribute sampling. We compare the suggested method to already-in-use attribute sampling techniques plans with new attribute six sigma sampling techniques plan is proposed in order to verified its efficacy. The outcomes show the neutrosophic fuzzy acceptance sampling plan's superiority in terms of its capacity to manage uncertainties, account for ambiguity, and produce more precise quality evaluation outputs.

Comparative Analysis of Latex Plants by GC-MS using Methanol Extraction

J. Varshini premakumari,M. Job Gopinath,B. Narmadha 사단법인 한국질량분석학회 2023 Mass spectrometry letters Vol.14 No.1

Plants are able to produce a large number of diverse bioactive compounds. Solvent extraction is used for isolation of plant metabolites. The extract yield for plant metabolite extraction strongly depends on the nature of solvent. A review showed the methanol can yield more bioactive compounds. Drying of the sample material is also important for the extraction of plant material. The present study was carried out to analyze the phytocomponents of 5 different latex producing plants. The plants like Calotropis gigantea, Carica papaya, Nerium oleander, Ficus benghalensis and Plumeria alba leaves and latex. The GC-MS analysis of the metabolites revealed phytocomponents. Calotropis gigantea leaves showed 14 compounds and latex produced 5 compounds out of this 4,4,6A,6B,8A,11,11,14B-Octamethyl-1,4,4A,5,6,6A,6B,7,8,8A,9,10,11,12,12A,14,14A,14B-Octadeca- hydro-2 and 2R- Acetoxymethyl-1,3,3-trimethyl-4T-(3-Methyl-2-Buten-1-Yl)-1T-Cyclohexanol compound was present in both latex and leaf extraction. Beta. -carotene compound was present in both latex and leaf of Carica papaya. It was observed that Ficus benghalensis contained 2R-Acetoxymethyl-1,3,3-trimethyl-4T-(3-Methyl-2-Buten-1-Yl)-1T-Cyclohexanol was same in latex and leaf extraction.

GC-MS Analysis of Ricinus communis, Pongamia pinnata, Datura metal, Azadirachta indica, Acalypha indica (leaf) Extract Using Methanol Extraction

J. Varshini premakumari,M. Job Gopinath 사단법인 한국질량분석학회 2023 Mass spectrometry letters Vol.14 No.3

Natural goods, especially therapeutic plants, are abundant in the World. Because they have the ability to pro- vide all humanity with countless advantages as a source of medicines, medicinal plants are presently receiving more atten- tion than ever. These plants' therapeutic efficacy is based on bioactive phytochemical components that have clear physiological effects on the human body. The drying process is crucial for the preparation of plant materials prior to extraction since freshly harvested plant materials include active enzymes that create active components, intermediates, and metabolic processes. Many of the phytoconstituents may be extracted using the semi-polar solvent methanol. The goal of the current work is to use the GC-MS gas chromatography- mass spectrometry technology to identify the phytochemicals and review their biological activity. In methanol leaf extract, 5 phytocompounds were found in Ricinus communis, 5 phy- tocompounds in Pongamia pinnata, 12 phytocompounds in Datura metal, 7 phytocompounds in Azadirachta indica, 11 phytocompounds in Acalypha indica.

A First-Time-in-Human Study of GSK2636771, a Phosphoinositide 3 Kinase Beta-Selective Inhibitor, in Patients with Advanced Solid Tumors

Mateo, Joaquin,Ganji, Gopinath,Lemech, Charlotte,Burris, Howard A.,Han, Sae-Won,Swales, Karen,Decordova, Shaun,DeYoung, M. Phillip,Smith, Deborah A.,Kalyana-Sundaram, Shanker,Wu, Jiuhua,Motwani, Monic American Association for Cancer Research 2017 Clinical Cancer Research Vol.23 No.19

<P><B>Background:</B> The PI3K/protein kinase B (AKT) pathway is commonly activated in several tumor types. Selective targeting of p110β could result in successful pathway inhibition while avoiding the on- and off-target effects of pan-PI3K inhibitors. GSK2636771 is a potent, orally bioavailable, adenosine triphosphate-competitive, selective inhibitor of PI3Kβ.</P><P><B>Methods:</B> We evaluated the safety, pharmacokinetics, pharmacodynamics and antitumor activity of GSK2636771 to define the recommended phase II dose (RP2D). During the dose-selection and dose-escalation stages (parts 1 and 2), patients with <I>PTEN</I>-deficient advanced solid tumors received escalating doses of GSK2636771 (25–500 mg once daily) using a modified 3+3 design to determine the RP2D; tumor type-specific expansion cohorts (part 3) were implemented to further assess tumor responses at the RP2D.</P><P><B>Results:</B> A total of 65 patients were enrolled; dose-limiting toxicities were hypophosphatemia and hypocalcemia. Adverse events included diarrhea (48%), nausea (40%), and vomiting (31%). Single- and repeat-dose exposure increased generally dose proportionally. GSK2636771 400 mg once daily was the RP2D. Phospho/total AKT ratio decreased with GSK2636771 in tumor and surrogate tissue. A castrate-resistant prostate cancer (CRPC) patient harboring <I>PIK3CB</I> amplification had a partial response for over a year; an additional 10 patients derived durable (≥24 weeks) clinical benefit, including two other patients with CRPC with <I>PIK3CB</I> alterations (≥34 weeks). GSK2636771 400 mg once daily orally induced sufficient exposure and target inhibition with a manageable safety profile.</P><P><B>Conclusions:</B> Genomic aberrations of <I>PIK3CB</I> may be associated with clinical benefit from GSK2636771. <I>Clin Cancer Res; 23(19); 5981–92. ©2017 AACR</I>.</P>

The physical origins of transit time measurements for rapid, single cell mechanotyping

Nyberg, K.,Scott, M.,Bruce, S.,Gopinath, A.,Bikos, D.,Mason, T.,Kim, J.,Choi, H.,Rowat, A. GENERAL AND APPLIED CHEMISTRY JOURNALS 2016 LAB ON A CHIP Vol.16 No.17

<P>The mechanical phenotype or 'mechanotype' of cells is emerging as a potential biomarker for cell types ranging from pluripotent stem cells to cancer cells. Using a microfluidic device, cell mechanotype can be rapidly analyzed by measuring the time required for cells to deform as they flow through constricted channels. While cells typically exhibit deformation timescales, or transit times, on the order of milliseconds to tens of seconds, transit times can span several orders of magnitude and vary from day to day within a population of single cells; this makes it challenging to characterize different cell samples based on transit time data. Here we investigate how variability in transit time measurements depends on both experimental factors and heterogeneity in physical properties across a population of single cells. We find that simultaneous transit events that occur across neighboring constrictions can alter transit time, but only significantly when more than 65% of channels in the parallel array are occluded. Variability in transit time measurements is also affected by the age of the device following plasma treatment, which could be attributed to changes in channel surface properties. We additionally investigate the role of variability in cell physical properties. Transit time depends on cell size; by binning transit time data for cells of similar diameters, we reduce measurement variability by 20%. To gain further insight into the effects of cell-to-cell differences in physical properties, we fabricate a panel of gel particles and oil droplets with tunable mechanical properties. We demonstrate that particles with homogeneous composition exhibit a marked reduction in transit time variability, suggesting that the width of transit time distributions reflects the degree of heterogeneity in subcellular structure and mechanical properties within a cell population. Our results also provide fundamental insight into the physical underpinnings of transit measurements: transit time depends strongly on particle elastic modulus, and weakly on viscosity and surface tension. Based on our findings, we present a comprehensive methodology for designing, analyzing, and reducing variability in transit time measurements; this should facilitate broader implementation of transit experiments for rapid mechanical phenotyping in basic research and clinical settings.</P>

An electrochromic device (ECD) cell characterization on electron beam evaporated MoO3 films by intercalating/deintercalating the H+ ions

R. Sivakumar,C.S. Gopinath,M. Jayachandran,C. Sanjeeviraja 한국물리학회 2007 Current Applied Physics Vol.7 No.1

Thin lms of molybdenum oxide (MoO3) is one of the most interesting layered intercalation materials because of its excellent appli-transmittance electrochromic devices (ECD) based on Li+, H+ and K+ intercalation in transition metal oxide (MoO3) thin lms. Inthe present investigation, thin lms of MoO3 were prepared by electron beam evaporation technique on microscopic glass and uorinedoped tin oxide (FTO) coated glass substrates for the application in electrochromic device cells. The compositional stoichiometry of the+ions from the H2SO4 electrolyte solution using the cyclic-voltammetry (CV) technique. We studied the electrochromic device cells (ECD)incorporating an evaporated MoO3 thin lms as electrochromic layers. The devices exhibit good optical properties with low transmit-tance values in the colored state, which make them suitable for large-area window applications. The maximum coloration eciencyof the cell was observed at about 70 cm2/C.

Designing metal oxide-vertical graphene nanosheets structures for 2.6 V aqueous asymmetric electrochemical capacitor

Subrata Ghosh,S.R. Polaki,Gopinath Sahoo,En Mei Jin,M. Kamruddin,조정상,정상문 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

The asymmetric electrochemical capacitor was realized by MnO2/Vertical graphene nanosheets (VGN)and Fe2O3/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton isindependently decorated with MnO2 having sponge gourd-like morphology and Fe2O3 having nanoricelike morphology. Both the electrodes have shown around 250 times higher charge-storage capacity thanthe bare VGN (0.47 mF/cm2) with the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). The fabricated asymmetric device exhibited a specific capacitance of 76 mF/cm2 and energydensity of 71 mWh/cm2 with an excellent electrochemical stability up to 12,000 cycles, over a potentialwindow of 2.6 V.

Designing metal oxide-vertical graphene nanosheets structures for 2.6V aqueous asymmetric electrochemical capacitor

Ghosh, Subrata,Polaki, S.R.,Sahoo, Gopinath,Jin, En-Mei,Kamruddin, M.,Cho, Jung Sang,Jeong, Sang Mun Elsevier 2019 Journal of industrial and engineering chemistry Vol.72 No.-

<P><B>Abstract</B></P> <P>The asymmetric electrochemical capacitor was realized by MnO<SUB>2</SUB>/Vertical graphene nanosheets (VGN) and Fe<SUB>2</SUB>O<SUB>3</SUB>/VGN as positive and negative electrodes, respectively. The surface of VGN skeleton is independently decorated with MnO<SUB>2</SUB> having sponge gourd-like morphology and Fe<SUB>2</SUB>O<SUB>3</SUB> having nanorice like morphology. Both the electrodes have shown around 250 times higher charge-storage capacity than the bare VGN (0.47mF/cm<SUP>2</SUP>) with the specific capacitance of 118 (MnO<SUB>2</SUB>/VGN) and 151mF/cm<SUP>2</SUP> (Fe<SUB>2</SUB>O<SUB>3</SUB>/VGN). The fabricated asymmetric device exhibited a specific capacitance of 76mF/cm<SUP>2</SUP> and energy density of 71μWh/cm<SUP>2</SUP> with an excellent electrochemical stability up to 12,000 cycles, over a potential window of 2.6V.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Metal oxide-vertical graphene electrodes were prepared. </LI> <LI> Metal oxide-vertical graphene nanoshees structure was found to be super-hydrophilic. </LI> <LI> A plausible formation mechanism of metal oxides on the surface of vertical graphene is propsed. </LI> <LI> As fabricated asymmetric supercapacitor device was operated in an extended window of 2.6V. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of cold atmospheric pressure plasma gas composition on the surface and cyto-compatible properties of low density polyethylene (LDPE) films

K. Navaneetha Pandiyaraj,A. Arun Kumar,M.C. RamKumar,K. Thirupugalmani,Avi Bendavid,Pi-Guey Su,S. Uday Kumar,P. Gopinath 한국물리학회 2016 Current Applied Physics Vol.16 No.7

In the present investigation, we have studied the influence of oxygen (O2) flow rate in the atmospheric pressure argon (Ar) plasma zone for improvement of the surface and cell compatible properties of LDPE film. Various characterization techniques such as contact angle (CA), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), etc were used to investigate the hydrophilicity, surface chemistry and morphology of LDPE films respectively. Fowke's approximation method was used to evaluate the polar and dispersion components of the total surface energy of LDPE films using contact angle values of three testing liquids. Moreover T-peel and lap shear tests were used to analyze the adhesive strength of the surface modified LDPE films. Finally cyto-compatibility of the surface modified LDPE film was analyzed by in vitro cell compatibility analysis which includes the cell viability and adhesion using NIH-3T3 fibroblast cells. The results obtained from various characterization techniques evidently revealed that cold atmospheric pressure (CAP) plasma treatment enhanced the surface properties (hydrophilicity, surface morphology and surface chemistry) of LDPE film. Owing to tailored physico-chemical changes induced by the CAP plasma treatment facilitates improvement in adhesive strength as well as adhesion and proliferation of cells on the surface of LDPE films.