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Duduku Krishnaiah,Collin G. Joseph,S. M. Anisuzzaman,W. M. A. W. Daud,M. Sundang,Y. C. Leow 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
Activated carbons (ACs) were prepared from papaya seeds with different dry weight impregnation ratios of zinc chloride (ZnCl2) to papaya seeds by using a two-stage self-generated atmosphere method. The papaya seeds were first semi-carbonized in a muffle furnace at 300 oC for 1 h and then impregnated with ZnCl2 before activation at 500 oC for 2 h. Several physical and chemical characteristics such as moisture, ash, pH, functional groups, morphological structure and porosity of prepared ACs were studied and presented here. AC2, with the impregnation ration of 1 : 2 (papaya seeds: ZnCl2), yielded a product that had the highest adsorption capacity, 91.75%, achieved after 180min contact time. The maximum Brunauer, Emmett and Teller (BET) surface area of AC2 was 546m2/g. Adsorption studies indicated that AC2 complied well with the Langmuir isotherm (qm=39.683mg g−1) and the pseudo-second-order (qe=29.36mg g−1). This indicated that chemisorption was the primary adsorption method for AC2. The intraparticle diffusion model proved that the mechanism of adsorption was separated into two stages: the instantaneous stage and the gradual adsorption stage. Overall, this work demonstrated the suitability of using papaya seeds as a precursor to manufacture activated carbon.
Coupled Analysis of Heat Transfer and Deformation in Equal Channel Angular Pressing of Al and Steel
Quang, Pham,Krishnaiah, A.,Hong, Sun Ig,Kim, Hyoung Seop The Japan Institute of Metals 2009 MATERIALS TRANSACTIONS Vol.50 No.1
<P>In the present paper, the heat transfer and plastic deformation during the equal channel angular pressing of Al alloy and steel were numerically analyzed. The finite element simulations were carried out at various pressing speeds ν=0.18, 1.8, and 18 mm/s, and the temperature and plastic strain distributions were investigated. It is concluded that the pressing speed is the most important processing parameter in rising temperature. Temperature rise in steel is higher than that in Al alloy due to the combined effect of high strength (heat generation effect) and low thermal diffusivity (heat release effect) in steel.</P>
Modeling medium carbon steels by using artificial neural networks
Reddy, N.S.,Krishnaiah, J.,Hong, S.G.,Lee, J.S. Elsevier Sequoia 2009 Materials science & engineering. properties, micro Vol.508 No.1
An artificial neural network (ANN) model has been developed for the analysis and simulation of the correlation between the mechanical properties and composition and heat treatment parameters of low alloy steels. The input parameters of the model consist of alloy compositions (C, Si, Mn, S, P, Ni, Cr, Mo, Ti, and Ni) and heat treatment parameters (cooling rate and tempering temperature). The outputs of the ANN model include property parameters namely: ultimate tensile strength, yield strength, percentage elongation, reduction in area and impact energy. The model can be used to calculate the properties of low alloy steels as a function of alloy composition and heat treatment variables. The individual and the combined influence of inputs on properties of medium carbon steels is simulated using the model. The current study achieved a good performance of the ANN model, and the results are in agreement with experimental knowledge. Explanation of the calculated results from the metallurgical point of view is attempted. The developed model can be used as a guide for further alloy development.
Prabhakar, J.,Kummara, Venkata Krishnaiah,Linganna, K.,Babu, P.,Jayasankar, C.K.,Kim, Jihoon,Venkatramu, V. Elsevier 2019 OPTIK -STUTTGART- Vol.176 No.-
<P><B>Abstract</B></P> <P>Trivalent dysprosium doped niobium zinc fluorosilicate glasses modified with different Nb<SUB>2</SUB>O<SUB>5</SUB>/ZnF<SUB>2</SUB> molar (M) ratios have been fabricated by the traditional melt-quenching technique and derived their structural, photoluminescence and decay properties using spectroscopic techniques. Induced structural modifications have been observed upon increasing content of Nb<SUB>2</SUB>O<SUB>5</SUB>. Maximum phonon energy of the glass matrix is found to be 1010 cm<SUP>−1</SUP> from the Raman spectrum. The emission spectra of these glasses exhibit two intense bands at 480 and 570 nm besides a weak red emission at 650 nm. The decay profiles of Dy<SUP>3+</SUP> ion for the <SUP>4</SUP>F<SUB>9/2</SUB> level exhibit a non-exponential behavior for all the glasses. The intrinsic lifetimes for the <SUP>4</SUP>F<SUB>9/2</SUB> level of Dy<SUP>3+</SUP> ion have been determined by using the Inokuti-Hirayama model and are found to be 409, 366 and 325μs for the glasses with Nb<SUB>2</SUB>O<SUB>5</SUB>/ZnF<SUB>2</SUB>:10/30, 20/20 and 30/10 M ratios, respectively. The color coordinates have been evaluated from the emission spectra of the glasses and found that the glass with Nb<SUB>2</SUB>O<SUB>5</SUB>/ZnF<SUB>2</SUB>:30/10 M ratio appears near to the equal energy point. The correlated color temperature matches well to the summer sunlight region (4900–5600 K), indicating that the glasses could be a potential candidate for white light emitting devices.</P>
Jin, Cheng Hua,Krishnaiah, Maddeboina,Sreenu, Domalapally,Subrahmanyam, Vura B.,Rao, Kota S.,Lee, Hwa Jeong,Park, So-Jung,Park, Hyun-Ju,Lee, Kiho,Sheen, Yhun Yhong,Kim, Dae-Kee American Chemical Society 2014 Journal of medicinal chemistry Vol.57 No.10
<P>A series of 2-substituted-4-([1,2,4]triazolo[1,5-<I>a</I>]pyridin-6-yl)-5-(6-methylpyridin-2-yl)imidazoles was synthesized and evaluated to optimize a prototype inhibitor of TGF-β type I receptor kinase (ALK5), <B>6</B>. Combination of replacement of a quinoxalin-6-yl moiety of <B>6</B> with a [1,2,4]triazolo[1,5-<I>a</I>]pyridin-6-yl moiety, insertion of a methyleneamino linker, and a <I>o</I>-F substituent in the phenyl ring markedly increased ALK5 inhibitory activity, kinase selectivity, and oral bioavailability. The <B>12b</B> (EW-7197) inhibited ALK5 with IC<SUB>50</SUB> value of 0.013 μM in a kinase assay and with IC<SUB>50</SUB> values of 0.0165 and 0.0121 μM in HaCaT (3TP-luc) stable cells and 4T1 (3TP-luc) stable cells, respectively, in a luciferase assay. Selectivity profiling of <B>12b</B> using a panel of 320 protein kinases revealed that it is a highly selective ALK5/ALK4 inhibitor. Pharmacokinetic study with <B>12b</B>·HCl in rats showed an oral bioavailability of 51% with high systemic exposure (AUC) of 1426 ng × h/mL and maximum plasma concentration (<I>C</I><SUB>max</SUB>) of 1620 ng/mL. Rational optimization of <B>6</B> has led to the identification of a highly potent, selective, and orally bioavailable ALK5 inhibitor <B>12b</B>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jmcmar/2014/jmcmar.2014.57.issue-10/jm500115w/production/images/medium/jm-2014-00115w_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jm500115w'>ACS Electronic Supporting Info</A></P>
Babu, P.,Martin, I.R.,Venkata Krishnaiah, K.,Seo, H.J.,Venkatramu, V.,Jayasankar, C.K.,Lavin, V. North Holland 2014 Chemical physics letters Vol.600 No.-
The Ho<SUP>3+</SUP>-Yb<SUP>3+</SUP> co-doped transparent glass and glass-ceramics containing CaF<SUB>2</SUB> nanocrystals have been prepared. Differential thermal analysis and X-ray diffraction measurements have been made to characterize thermal properties of glass and structural changes in glass-ceramics, respectively. Photon avalanche upconversion has been achieved by exciting the samples at 745nm at room temperature. An intense green and a weak red upconverted emissions corresponding to the <SUP>5</SUP>S<SUB>2</SUB>:<SUP>5</SUP>F<SUB>4</SUB>→<SUP>5</SUP>I<SUB>8</SUB> and <SUP>5</SUP>F<SUB>5</SUB>→<SUP>5</SUP>I<SUB>8</SUB> transitions, respectively, have been observed. The upconversion intensity has been found to increase with the increase in the size of the fluoride nanocrystals in glass-ceramics. Experimental evidences confirm that the mechanism of upconversion is photon avalanche.
Hydrodynamics of co-current downward liquid-liquid system with packing
Swaminathan Samdavid,Thiruvengadam Renganathan,Kamatam Krishnaiah 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.1
The effect of packing and its voidage on the hydrodynamic characteristics of co-current downward liquidliquid system (CCDLLS) was studied using water and three different oils (exxsol, kerosene and white oil). Two flow regimes, homogeneously dispersed oil regime and heterogeneously dispersed oil, were observed with the total pressure drop showing a minimum at the regime transition velocity. Depending on the packing, frictional pressure drop either shows a minimum or monotonically increases with water velocity. Low-density oil results in higher holdup and correspondingly higher frictional pressure drop. Higher dispersed phase holdup is obtained by using a low voidage packing. Semi-empirical/empirical equations are proposed to predict the frictional pressure drop and phase holdup.
Edward John Nevins,James Edward Dixon,Yirupaiahgari Krishnaiah Setty Viswanath 대한소화기내시경학회 2021 Clinical Endoscopy Vol.54 No.4
Background/Aims: STRETTA improves the quality of life and reduces the need for anti-reflux medication in select patients,especially those with uncomplicated gastroesophageal reflux disease (GERD). We aimed to review the outcomes of STRETTA inpatients with medically refractory GERD, who had undergone previous gastric surgery. Methods: This was a review of a prospective database in a British center. Since 2016, all GERD patients who underwent STRETTAand had a history of previous gastric surgery were studied (n=11). Anti-reflux medication pre- and post-STRETTA was evaluated. The outcomes were assessed objectively by the change in anti-reflux medication and subjectively through a pre- and post-procedureGERD-health-related quality of life (HRQL) questionnaire. Results: The median length of follow-up was 23 months. Nine patients demonstrated improved GERD-HRQL scoresfollowing STRETTA (82%). Of the 7 patients who underwent fundoplication, all reported improved symptoms, with 3 patientsdiscontinuing the medication and 3 patients on a reduced dose of proton pump inhibitor. Four patients underwent surgery otherthan fundoplication, of which 2 reported improvement and discontinued the proton pump inhibitor. Two patients reported noimprovement. Conclusions: This study demonstrates that STRETTA is successful in reducing refractory GERD in patients with previous gastricsurgery. The outcomes were comparable to published outcomes in patients with uncomplicated GERD with no previous history ofgastric surgery.
Dae-Kee, Kim,Hua Jin, Chung,Krishnaiah, Maddeboina,Sreenu, Domalapally,Kota Sudhakar, Rao,Subrahmanyam, Vura BaJa,Chui-Yong, Park,jee-Yeon, Son,Yhun Yhong, Sheen 이화여자대학교 약학연구소 2012 藥學硏究論文集 Vol.- No.22
A series of 1-substituted-3(5)-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)pyrazoles 14a-d, 15a-d, 17a, 17b, 18a-d, 19a, and 19b has been synthesized and evaluated for their ALK5 inhibitory activity in an enzyme assay and in a cell-based luciferase reporter assay. The 2-[3-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)-1H-pyrazol-1-yl]-N-phenylethanethioamide (18a) inhibited ALK5 phosphorylation with an IC(50) value of 0.013 μM and showed 80% inhibition at 0.1 μM in a luciferase reporter assay using HaCaT cells permanently transfected with p3TP-luc reporter construct.