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Sarathi, P.A.,Gnanasekaran, C.,Shunmugasundaram, A. Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.4
Nucleophilic addition reaction of benzenethiols (PhSH) to 1-(2-nitrovinyl) benzenes ($\beta$ NS) in the presence of triethylamine (TEA) has been studied in acetonitrile at 25 ${^{\circ}C}$. The rate is first order with respect to [PhSH], [TEA] and [$\beta$ NS]. The reaction is found to proceed with the formation of ion-pair between benzenethiol and TEA. A suitable mechanism with the formation of an adduct between ion-pair and substrate in a slow step followed by its rearrangement to 1,2-addition product in a fast step has been proposed and corresponding rate law derived. From the rate law, the rate constants for the interaction between ion-pair and $\beta$NS have been evaluated. Interestingly, in both para-substituted substrates and benzenethiols the rate increases with the electron-withdrawing power of the substituents. The positive sign of $\rho_x$ in benzenethiols has been explained. The magnitude of cross-interaction constant, $\rho_{xy}$ is small (0.08). The magnitude of the Hammett $\rho_x$ values is higher than that of the Bronsted, $\beta_x$ values for benzenethiols. The kinetic isotope effect, $k_H/k_D$, is found to be greater than unity. A suitable transition state with simultaneous formation of $C_\beta$ -H and $B_\alpha$ -S bonds involving the ion-pair and $\beta$NS in a single concerted step has been proposed to account for these observations.
Surjya Sarathi Bhattacharyya,M. Rahman,A. Mukherjee,S.L. Wu,B.K. Chaudhuri 한국물리학회 2009 Current Applied Physics Vol.9 No.3
The temperature and frequency dependent dielectric relaxation data and simultaneous observation of optical texture reveal co-existence of ferroelectric (SmC*) and antiferroelectric (SmCA *) phases in the pre-transition regime of the antiferroelectric liquid crystal (AFLC) sample viz. (R)-4-[1-methyl-2-(2,2,3,3,3-pentafluoropropyloxy)ethyloxy)carbonyl]phenyl 4'-decyloxybiphenyl-4-caboxylate. Interestingly, this sample shows irreversible change in the antiferroelectric to ferroelectric (AFE → FE) phase transition temperature (T0) for consecutively increasing bias field treatment in successive cycles. The lowest upper bound of the threshold field for AFE →FE transition at the boundary of the said phases is found to be ~1 kV cm-1. The temperature and frequency dependent dielectric relaxation data and simultaneous observation of optical texture reveal co-existence of ferroelectric (SmC*) and antiferroelectric (SmCA *) phases in the pre-transition regime of the antiferroelectric liquid crystal (AFLC) sample viz. (R)-4-[1-methyl-2-(2,2,3,3,3-pentafluoropropyloxy)ethyloxy)carbonyl]phenyl 4'-decyloxybiphenyl-4-caboxylate. Interestingly, this sample shows irreversible change in the antiferroelectric to ferroelectric (AFE → FE) phase transition temperature (T0) for consecutively increasing bias field treatment in successive cycles. The lowest upper bound of the threshold field for AFE →FE transition at the boundary of the said phases is found to be ~1 kV cm-1.
Total Synthesis of Azasugar 1,4-Dideoxy-1,4-imino-D-galacitol
Partha Sarathi Sadhu,Amlipur Santhoshi,Vaidya Jayathirtha Rao,강한영,강성호 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.11
A new highly stereoselective synthesis of pyrrolidine azasugar 1,4-dideoxy-1,4-imino-D-galacitol is being reported herein. The synthesis was achieved in a linear sequence and inexpensive chiral source (+)-diethyl tartarate was used as the starting material. The key step involved during the synthesis was Pd catalysed amino cyclization of alkenylamine, Bose modified Mitsunobu reaction and Sharpless asymmetric dihydroxylation.
Total Synthesis of Azasugar 1,4-Dideoxy-1,4-imino-D-galacitol
Sadhu, Partha Sarathi,Santhoshi, Amlipur,Rao, Vaidya Jayathirtha Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.11
A new highly stereoselective synthesis of pyrrolidine azasugar 1,4-dideoxy-1,4-imino-D-galacitol is being reported herein. The synthesis was achieved in a linear sequence and inexpensive chiral source (+)-diethyl tartarate was used as the starting material. The key step involved during the synthesis was Pd catalysed amino cyclization of alkenylamine, Bose modified Mitsunobu reaction and Sharpless asymmetric dihydroxylation.
P. A. Sarathi,C. Gnanasekaran,A. Shunmugasundaram* 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.4
Nucleophilic addition reaction of benzenethiols (PhSH) to 1-(2-nitrovinyl) benzenes (b NS) in the presence of triethylamine (TEA) has been studied in acetonitrile at 25℃. The rate is first order with respect to [PhSH], [TEA] and [b NS]. The reaction is found to proceed with the formation of ion-pair between benzenethiol and TEA. A suitable mechanism with the formation of an adduct between ion-pair and substrate in a slow step followed by its rearrangement to 1,2-addition product in a fast step has been proposed and corresponding rate law derived. From the rate law, the rate constants for the interaction between ion-pair and b NS have been evaluated. Interestingly, in both para-substituted substrates and benzenethiols the rate increases with the electron-withdrawing power of the substituents. The positive sign of r x in benzenethiols has been explained. The magnitude of cross-interaction constant, r xy is small (0.08). The magnitude of the Hammett r x values is higher than that of the Bronsted, b x values for benzenethiols. The kinetic isotope effect, kH/kD, is found to be greater than unity. A suitable transition state with simultaneous formation of Cb -H and Ca -S bonds involving the ion-pair and b NS in a single concerted step has been proposed to account for these observations.
Electric-field induced elastic stretching of multiwalled carbon nanotube clusters: a realistic model
Bhattacharyya, Surjya Sarathi,Yang, Gyu Hyung,Tie, Weiwei,Lee, Young Hee,Lee, Seung Hee Royal Society of Chemistry 2011 Physical chemistry chemical physics Vol.13 No.45
<P>The oscillating electric-field induced stretching phenomenon of multiwalled carbon nanotube (MWCNT) clusters in liquid crystal medium demonstrates distinct threshold behaviour under optical microscopic investigation. The optimum field required for the initiation of MWCNT cluster stretching is found to depend on their length in the field-off state. The phenomenon has been explained in light of a classical theoretical model assuming MWCNT agglomerates as a single electric dipole. The spring constant and induced charge obtained by fitting the formulated theoretical model show good agreement with previous reports, hence establish the proposed dipolar reorientation mechanism of MWCNT clusters induced by the electric field.</P> <P>Graphic Abstract</P><P>Threshold behavior in electric-field induced elastic stretching of multiwalled carbon nanotube clusters has been explained by single electric dipole approximation theory. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cp22311a'> </P>
Photochemical dehydrogenation of 3,4-dihydro-2-pyridones
Sadhu, Partha Sarathi,Ravinder, Mettu,Kumar, Perepogu Arun,Rao, Vaidya Jayathirtha Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.4
Photochemical dehydrogenation of various substituted 3,4-dihydro-2-pyridones was achieved in a very efficient way by employing 10-15 mol% of photo-induced electron transfer sensitizers like 9-cyanoanthracene, 9-cyanophenanthrene and 1-cyanonaphthalene in presence of molecular oxygen, for the first time.
Tie, Weiwei,Bhattacharyya, Surjya Sarathi,Park, Hye Ryung,Lee, Joong Hee,Lee, Sang Won,Lee, Tae Hoon,Lee, Young Hee,Lee, Seung Hee Published by the American Physical Society through 2014 Physical review. E, Statistical, nonlinear, and so Vol.90 No.1
<P>We demonstrate distinct entanglement of single-walled carbon nanotube (SWCNT) and multiwalled carbon nanotube (MWCNT) clusters in nematic liquid crystal medium using scanning electron microscopy technique and the entanglement influence on electric field-induced stretching phenomena of the said clusters in the same medium under optical microscopy investigation. The observed stretching threshold field for MWCNT clusters is found to be higher than the SWCNT counterpart caused by the interplay between attractive field-induced dipolar interaction of intercarbon nanotube (CNT) bundles and the distinct degree of entanglement of neighboring CNT bundles. Subsequently observed different tensile elasticity modulus results for different CNT kinds also confirm different CNT bundle entanglement and attractive dipolar interaction between adjacent CNT bundles in CNT clusters are responsible for distinct stretching threshold field behavior.</P>
A Multiband Shunt Hybrid Active Filter with Sensorless Control
Surendra Kumar S,Partha Sarathi Sensarma 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.4
This paper proposes a Multiband Shunt Hybrid Active Filter (SHAF) with sensorless control. A plant is modeled in the discrete- time domain and a controller is designed using the Pole shifting law in the polynomial domain. This control approach is very useful for filtering the load harmonics with reduced sensor counts where a low cost solution like SHAF is required. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure the 5<SUP>th</SUP> and 7<SUP>th</SUP> harmonic components separately from the load and filter currents. Individual current controllers are designed for the 5<SUP>th</SUP> and 7<SUP>th</SUP> harmonic currents. Control is realized in the stationary, three-phase (abc) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models, as well as experimentally on a fullscale distribution system.
Manoj Gupta,Partha Sarathi Choudhury,Sudhir Rawal,Harish Chandra Goel,S. Avinash Rao 대한핵의학회 2018 핵의학 분자영상 Vol.52 No.6
Purpose The aim of the study was to compare response evaluation criteria in solid tumours 1.1 (RECIST 1.1), positron emissiontomography response criteria in solid tumours (PERCIST), European organisation for research and treatment of cancer (EORTC),andMDAnderson (MDA) criteria for response assessment by Gallium 68-prostate-specific membrane antigen positron emissiontomography-computed tomography (Ga68-PSMA PET-CT) in metastatic adenocarcinoma prostate cancer (mPCa) patients withbiochemical progression. Methods Eighty-eight mPCa patients with pre and post treatment Ga68-PSMA PET-CTwere included. A ≥ 25% increase and ≥2 ng/ml above the nadir if prostate specific antigen (PSA) drop or ≥ 2 ng/ml above the baseline if PSA does not drop wasconsidered as biochemical progression. RECIST 1.1 and MDA criteria for morphology and PERCIST and EORTC criteria formolecular response were investigated. Percentages of progressive disease (PD), partial response (PR), and stable disease (SD)were calculated. Chi-square test was used for statistical significance. Results Proportion of PD, SD, and PR by RECIST 1.1 and MDA criteria were 44 (50.57%), 39 (44.83%), 4 (4.6%), and 33(39.76%), 48 (57.83%), 2 (2.41%) respectively. Proportion of PD, SD, and PR by PERCIST and EORTC criteria were 71(80.68%), 11 (12.50%), 6 (6.82%), and 74 (84.09%), 8 (9.09%), 6 (6.82%) respectively. Chi-square test showed statisticallysignificant (P < 0.05) higher proportion of progression detected by both molecular criteria as compare to both morphologicalcriteria. Conclusion We concluded that for Ga68-PSMA PET-CT response evaluation, molecular criteria performed better than morphologicalcriteria in mPCa patient with PSA progression.