A new criterion for modeling multiple discontinuities passing through an element using XIGA

I. V. Singh,G. Bhardwaj,B. K. Mishra 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3

In this paper, a new criterion is proposed for the modeling multiple discontinuities i.e. crack, hole and inclusion passing through anelement by XIGA. The modeling of multiple discontinuities passing through an element is done by imposing the additional degrees offreedom at the control points lying inside the influence of elements intersected by the discontinuities. In XIGA, the crack faces are modeledby discontinuous Heaviside jump functions, whereas the singularity in stress field at the crack tip is modeled by crack tip enrichmentfunctions. The modeling of holes and inclusions is performed by Heaviside jump function and distance function respectively. The valueof stress intensity factor is computed using domain form of interaction integral approach. Few static plane edge crack problems are analyzedin the presence of holes and inclusions to validate the proposed criterion. The results obtained by XIGA are compared with XFEM.

Effect of Mechanical Alloying and Sintering Environment on the Crystallographic Evolution, Microstructure, Mechanical and Corrosion Properties of Porous Ti4Al4Co Alloy

Pradeep Singh,Vikas Shrivastava,I. B. Singh,D. P. Mondal 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

Three group of porous Ti4Al4Co samples made of (i) unmilled powder and vacuum sintered (S1), (ii) milled powder andvacuum sintered (S2), and (iii) milled powder sintered in open atmosphere (S3) were prepared. Phase change, crystallite sizeand lattice strain variations due to powder milling and sintering were examined by SEM and XRD. To evaluate mechanicalproperty, alloy samples were subjected to the uniaxial compression test. For corrosion analysis, Tafel plot was plotted usingelectrochemical corrosion system in simulated body fluid (SBF) as electrolytic medium. From the obtained results, it wasfound that significant microstructural transformation takes place due to milling and change in sintering atmosphere. SampleS1possessed 139 MPa compressive strength, which was about 48% and 76% higher than samples S2and S3respectively. Corrosion current density for S3was found as 5.5 ± 0.3 μA/cm2 which is 7 and 12 times lower than S2and S1samples.

Enhanced electrochemical performance and manganese redox activity of LiFe_0.4Mn_0.6PO₄ by iodine anion substitution as cathode material for Li-ion battery

Sin, B.C.,Singh, L.,An, J.,Lee, H.,Lee, H.i.,Lee, Y. Elsevier Sequoia 2016 Journal of Power Sources Vol.313 No.-

For the first time, an attempt has been made for the possible augmentation and exploration of iodine substitution into LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>PO<SUB>4</SUB> (LFMP) material is assessed as a cathode material for lithium ion batteries. Iodine substituted LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>1-x</SUB>I<SUB>x</SUB> (LFMPI, x = 0, 0.01, 0.015, and 0.02) have been synthesized by a solid-state reaction without any external carbon source. X-ray diffraction shows that the LFMP and LFMPI cathode materials have formed the same single crystalline phase; the values of lattice parameters and unit cell volume have been insignificantly changed by I<SUP>-</SUP> anion substitution. Uniformly distributed grains of the LFMPI samples with grain sizes in the range of 250 nm to 0.9 μm have been obtained by scanning electron microscopy. X-ray photoelectron spectroscopy for the LFMPI with x = 0.02 have clearly observed at 619.5 and 630.7 eV for I 3d<SUB>5/2</SUB> and I 3d<SUB>3/2</SUB>, respectively. The electrochemical properties of the pure LFMP cathode material have been compared with those of I<SUP>-</SUP> anion substituted LFMPI samples. LFMPI with x = 0.015 has delivered the highest discharge capacity of 141.5 mAh g<SUP>-1</SUP> at 0.1C, and LFMPI with x = 0.01 has 102.1 mAh g<SUP>-1</SUP> at high rate of 3C. Iodine substituted LFMPI have demonstrated improved electrochemical properties with excellent reversible cycling.

Trisodium phosphate dip, hot water dip, and combination dip with/without brushing on broiler carcass decontamination

Singh, P.,Lee, H.C.,Silva, M.F.,Chin, K.B.,Kang, I. Elsevier 2017 FOOD CONTROL Vol.77 No.-

<P>The purpose of this research was to evaluate the effects of trisodium phosphate dip (TSP), hot water dip (HWD) and their combination dip with/without brushing on broiler breast skin for bacterial reduction and structural changes. Eviscerated broiler carcasses were obtained from a local slaughter plant and immediately subjected to one of six treatments: 1) two tap water dips at 25 degrees C (TWD/TWD), 2) TWD/ TWD with brushing (TWD/TWD/B), 3) TWD and TSP at 8%/25 degrees C (TWD/TSP), 4) TWD and HWD at 71 degrees C (TWD/HWD), 5) TSP and HWD (TSP/HWD), and 6) TSP/HWD with brushing (TSPIHWD/B). Each dip was conducted for 45 s with or without brushing at 5 s on/off during the second dip. Compared to the control (TWD/TWD), TSP/HWD significantly reduced mesophilic aerobic bacteria (MAB), Escherichia coli (E. coli), and total coliforms by 1.1, 0.9 and 1.0 log CFU/g, respectively, and Salmonella prevalence by 53.3% (P < 0.05), whereas TWD/TSP and TWD/HWD showed intermediate reductions (P < 0.05). Upon brushing, TSP/HWD/B reduced populations of MAB, E. coli, and total coliforms, and the prevalence of Salmonella more effectively than control of brushing (TWID/TWD/B) (P < 0.05). When two sampling methods were compared, the method of stomaching released fewer MAB and total coliforms (named loosely-associated cells) than the grinding of the stomached skin (named tightly-associated cells). Compared to controls (TWD/TWD and TWD/TWD/B), both TSP/HWD and TSP/HWD/B generally resulted in darker, less reddish, and more yellowish breast skin. Scanning electron microscope and histological images indicated that both TSP/HWD and TSP/HWD/B had deeper skin penetration than controls or TWD/HWD and TWD/TSP. Overall, TSP/HWD/B showed the most effectiveness in broiler carcass decontamination. (C) 2017 Published by Elsevier Ltd.</P>

ON SOME H-STAR(*) CURVATURE TENSORS IN KAHLER MANIFOLD

Sinha, B.B.,Singh, I.J.P. Department of Mathematics 1974 Kyungpook mathematical journal Vol.14 No.1

Chemical Modification of Chitosan with pH-Sensitive Molecules and Specific Ligands for Efficient DNA Transfection and siRNA Silencing

Singh, B.,Choi, Y.-J.,Park, I.-K.,Akaike, T.,Cho, C.-S. American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.1

Successful gene therapy depends on the development of efficient and cell-specific gene delivery systems. Currently, animal viral vectors have been mostly used for in vivo and in clinical trials owing to their high transduction efficiency. However, they suffer from numerous limitations such as biosafety, immunogenicity, gene packaging capacity, complicated production and cell specificity. Therefore non-viral vectors are attractive alternatives to viral gene delivery systems due to their low toxicity, relatively easy production and greater diversity. Among non-viral vectors, chitosan and chitosan derivatives have been extensively utilized as gene carriers owing to their low immunogenicity, biocompatibility, biodegradability low toxicity and ease of chemical modifications. However, low transfection efficiency of DNA (or low gene silencing of siRNA) and low cell specificity of chitosan should be overcome before clinical trials. The objective of this review is to summarize several parameters affecting the transfection efficiency of DNA (or gene silencing of siRNA) for the promising use of chitosan as gene carriers. Besides, chemical modifications of chitosan with pH-sensitive molecules and specific ligands so as to enhance the transfection efficiency of DNA (or gene silencing of siRNA) and cell specificity will be covered.

A novel low cost non-aqueous chemical route for giant dielectric constant CaCu₃Ti₄O₁₂ ceramic

Singh, L.,Kim, I.W.,Woo, W.S.,Sin, B.C.,Lee, H.i.,Lee, Y. Elsevier 2015 SOLID STATE SCIENCES Vol.43 No.-

This paper reports a simple, fast, low cost and environment-friendly route for preparing a highly crystalline giant dielectric material, CaCu<SUB>3</SUB>Ti<SUB>4</SUB>O<SUB>12</SUB> (CCTO), through combustion of metal nitrates in non-aqueous precursor solution using inexpensive solid TiO<SUB>2</SUB> powder. The route to producing pure phase CCTO ceramic using stable solid TiO<SUB>2</SUB> is better than other several sol-gel routes reported earlier in which expensive alkoxides, oxynitrates, or chlorides of titanium are used as the titanium sources. X-ray diffraction revealed the formation of cubic perovskite CCTO. Scanning electron microscopy image showed the average grain sizes in the range of 1.5-5 μm. At 10 kHz and room temperature, the best CCTO ceramic exhibited a high dielectric constant, ε' ~43325.24, with low dielectric loss, tan δ ~0.088. The dielectric relaxation behavior was rationalized from impedance and modulus studies and the presence of a non-Debye type of relaxation was confirmed.

Dielectric, ac-impedance and modulus spectroscopic studies of nano-crystalline Bi0.5Na0.5TiO3 synthesized by using one pot glycine assisted solution combustion from inexpensive TiO2

Singh, L.,Kim, I. W.,Singh, S. V.,Sin, B. C.,Woo, S. K.,Lee, Y. Springer Science + Business Media 2015 Journal of materials science Materials in electron Vol.26 No.2

Enhanced electrochemical performance of LiFe_0.4Mn_0.6(PO₄)_1-x(BO₃)_x as cathode material for lithium ion batteries

Sin, B.C.,Singh, L.,Lee, K.E.,Kim, M.,Cho, M.,Yarger, J.L.,Woo, S.K.,Lee, H.i.,Lee, Y. Elsevier Sequoia 2015 Journal of Electroanalytical Chemistry Vol.756 No.-

A potential cathode material for lithium ion batteries has been developed using a boron polyanion substituted lithium iron manganese phosphate, LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>1-x</SUB>(BO<SUB>3</SUB>)<SUB>x</SUB> (x=0 to 0.03). Without any external carbon source, the material has been synthesized by solid-state reaction using ball-mill and was subsequently characterized by X-ray diffraction, scanning electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge measurement. The LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>1-x</SUB>(BO<SUB>3</SUB>)<SUB>x</SUB> samples show a single-phase crystalline nature with X-ray diffraction analysis, and enhanced discharge capacity at various C-rates as compared to that of pure LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>PO<SUB>4</SUB>. Among several LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>1-x</SUB>(BO<SUB>3</SUB>)<SUB>x</SUB> samples, LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>0.995</SUB>(BO<SUB>3</SUB>)<SUB>0.005</SUB> demonstrated the best cycleability, exhibiting an initial discharge capacity of 159.4mAhg<SUP>-1</SUP> at 0.1C and 113mAhg<SUP>-1</SUP> at 3C. LiFe<SUB>0.4</SUB>Mn<SUB>0.6</SUB>(PO<SUB>4</SUB>)<SUB>1-x</SUB>(BO<SUB>3</SUB>)<SUB>x</SUB> demonstrates enhanced electrochemical properties with excellent reversible cycling via boron polyanion substitution.

Potent, tumor-specific gene expression in an orthotopic hepatoma rat model using a Survivin-targeted, amplifiable adenoviral vector

Ahn, B-C,Ronald, J A,Kim, Y I,Katzenberg, R,Singh, A,Paulmurugan, R,Ray, S,Hofmann, L V,Gambhir, S S Macmillan Publishers Limited 2011 Gene therapy Vol.18 No.6

Ideal cancer gene therapies should have high tumor specificity and efficacy, and allow systemic administration to target metastases. We recently developed a bi-directional, two-step transcriptional amplification (TSTA) system driven by the tumor-specific Survivin promoter (pSurv) to amplify the correlated expression of both the reporter gene firefly luciferase (FL) and therapeutic gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we compare the specificity and potency of an adenovirus carrying this system (Ad-pSurv-TSTA-TRAIL-FL) to a nonspecific vector (Ad-pCMV-FL) in an orthotopic hepatocellular carcinoma (HCC) rat model after systemic administration. At 24 h after injection of Ad-pCMV-FL, bioluminescence imaging revealed a trend (P=0.30) towards greater FL expression in liver versus tumor. In striking contrast, Ad-pSurv-TSTA-TRAIL-FL showed increased FL activity within the tumor compared with the liver (P<0.01), a strong trend towards reduced liver expression compared with Ad-pCMV-FL (P=0.07), and importantly, similar FL levels within tumor compared with Ad-pCMV-FL (P=0.32). Hence, this vector shows potent, tumor-specific transgene expression even after extensive liver transduction and may be of significant value in avoiding hepatotoxicity in HCC patients. Future studies will explore the benefits of tumor-specific TRAIL expression in this model, the potential to target metastases and the extension of this vector for the treatment of other Survivin-positive tumors is warranted.