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Vishwakarma, Niraj K.,Hwang, Yoon-Ho,Adiyala, Praveen Reddy,Kim, Dong-Pyo American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.49
<P>Many efforts have been made on stimuli-responsive switchable catalysis to trigger catalytic activity over various chemical reactions. However, the reported light-, pH- or chemically responsive organocatalysts are mostly incomplete in the aspects of shielding efficiency and long-term performance. Here, we advance the flow-assisted switchable catalysis of metal ions in a microenvelope system that allows the on-off catalysis mode on demand for long-lasting catalytic activity. Various metal-ion catalysts can be selectively embedded in a novel polymeric core-shell of the heteroarm star copolymer of poly(styrene) and poly(4-vinylpyridine) emanated from a polyhedral oligomeric silsesquioxane center. The immobilized core-shell polymer on the inner wall of a poly(dimethylsiloxane) envelope microreactor shows on-off switching catalysis between the expanded active mode and contracted protective mode under continuous flow of solvents or subsequent dry conditions. In particular, the preserved catalytic activity of toxic Hg<SUP>2+</SUP> for oxymercuration was demonstrated even for 2 weeks without leaching, whereas the activity of moisture-sensitive Ru<SUP>3+</SUP> ions for polymerization of methyl methacrylate was maintained even after 5 days from an open atmosphere. It is practical that the tight environment of the enveloped microfluidic system facilitates cyclic switching between the reaction-“on” and -“off” modes of such toxic, sensitive/expensive catalysts for long-term prevention and preservation.</P> [FIG OMISSION]</BR>
Designing of Antiepileptic Ligands by Esterification and Acetylation of Dipeptides
Vishwakarma, K.K.,Saraf, S.K.,Uppadhyay, R.K.,Kohli, D.V. The Pharmaceutical Society of Korea 1992 Archives of Pharmacal Research Vol.15 No.3
Glycylglycine, alanylalanine and alanylglycine were synthesized, their free carboxylic and amino groups were converted to methyl esters of N-acetylglycyglycine, N-acetylalanylglycine and N-acetylalanylalanine. The synthesized compounds were evaluated for antiepileptic activity, plasmaprotein binding, $TD_{50}$ and potentiating effect of phenobarbitone sodium.
Vishwakarma, Santosh L.,Rajani, M.,Goyal, Ramesh K. Kyung Hee Oriental Medicine Research Center 2003 Oriental pharmacy and experimental medicine Vol.3 No.4
Aqueous extract of Enicostemma littorale is reported to have antidiabetic activity. In the present investigation, we studied the effect of aqueous extract of E. littorale and its different fractions i.e., toluene, chloroform, ethyl acetate, n-butanol fractions and remaining residual fraction in streptozotocin (STZ)-induced neonatal type 2 diabetic rats. Fasting glucose and insulin levels in NIDDM were significantly (P<0.05) higher than control rats and they were significantly decreased by treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions. Results of oral glucose tolerance test (OGTT) showed that aqueous extract and its n-butanol and ethyl acetate fractions significantly (P<0.05) decrease both $AUC_{glucose}$ and $AUC_{insulin}$ values in NIDDM treated groups. Insulin sensitivity $(K_{ITT})$ index of NIDDM control was significantly lower as compared to normal control and this was significantly (P<0.05) increased after treatment with aqueous extract, its n-butanol and ethyl acetate fractions. Treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions lowered the elevated cholesterol and triglyceride levels observed in NIDDM rats. Treatment with aqueous extract of E. littorale and its n-butanol fraction showed significant decrease in creatinine, urea, SGPT and SGOT levels as compared to NIDDM control rats. However ethyl acetate fraction showed significant changes only in creatinine and SGOT levels, and not in the levels of urea, and SGPT as compared to NIDDM control rats. Treatment with toluene, chloroform and residual fractions of E. littorale did not produce any effect on glucose, insulin, triglyceride, cholesterol, creatinine, urea, SGPT or SGOT levels as compared to NIDDM control rats. Our data suggest that n-butanol and ethyl acetate fractions contain the active compounds which may be responsible for the above activity and associated complications in NIDDM diabetes mellitus.
Avinash Vishwakarma,Sivaiah Bathula,Nagendra S. Chauhan,Ruchi Bhardwaj,Bhasker Gahtori,Avanish K. Srivastava,Ajay Dhar 한국물리학회 2018 Current Applied Physics Vol.18 No.12
SiGe alloy is widely used thermoelectric materials for high temperature thermoelectric generator applications. However, its high thermoelectric performance has been thus far realized only in alloys synthesized employing mechanical alloying techniques, which are time-consuming and employ several materials processing steps. In the current study, for the first time, we report an enhanced thermoelectric figure-of-merit (ZT)∼1.1 at 900 °C in ntype Si80Ge20 nano-alloys, synthesized using a facile and up-scalable methodology consisting of rapid solidification at high optimized cooling rate∼3.4×107 K/s, employing melt spinning followed by spark plasma sintering of the resulting nano-crystalline melt-spun ribbons. This enhancement in ZT>20% over its bulk counterpart, owes its origin to the nano-crystalline microstructure formed at high cooling rates, which results in crystallite size ∼7 nm leading to high density of grain boundaries, which scatter heat-carrying phonons. This abundant scattering resulted in a very low thermal conductivity ∼2.1 Wm−1K−1, which corresponds to ∼50% reduction over its bulk counterpart and is amongst the lowest reported thus far in n-type SiGe alloys. The synthesized samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy, based on which the enhancement in their thermoelectric performance has been discussed.
Gautam Vishwakarma,Ravi Prakash Sanyal,Abhijit Shitre,D. A. Gadekar,Ajay Saini,Bikram Kishore Das 한국작물학회 2019 Journal of crop science and biotechnology Vol.22 No.4
Stem rust resistance gene Sr2 is an important slow-rusting gene which has provided resistance against stem rust for many years. The Sr2 gene has durable resistance against all stem rust pathogens including the Ug99 group of races. It shows recessive inheritance and is linked with two phenotypic markers, Pseudo Black Chaff (PBC) and High Temperature-Induced Seedling Chlorosis (HTISC). However, direct screening as well as phenotypic marker-based screening for selection of Sr2 is difficult due to the effect of environmental factors and genetic background. Microsatellite marker Xgwm533 linked to Sr2 gene is useful for rapid screening of large populations. Here we report validation and use of Xgwm533 for screening 21 wheat lines and 24 wheat genotypes for the presence of the Sr2 gene. Furthermore, we also report the presence of a new, smaller allele (97 bp) of Xgwm533 locus in a few genotypes that was also confirmed by sequencing. We also demonstrate a new SYBR green dye, melt-curve/profile-based assay for convenient screening of the Xgwm533 locus, where the presence of different alleles can be differentiated in a gel-free manner.
Dinesh Kumar Vishwakarma,Konark Jain 한국전자통신연구원 2022 ETRI Journal Vol.44 No.2
Human activity recognition in real time is a challenging task. Recently, a plethora of studies has been proposed using deep learning architectures. The implementation of these architectures requires the high computing power of the machine and a massive database. However, handcrafted features-based machine learning models need less computing power and very accurate where features are effectively extracted. In this study, we propose a handcrafted model based on three-dimensional sequential skeleton data. The human body skeleton movement over a frame is computed through joint positions in a frame. The joints of these skeletal frames are projected into two-dimensional space, forming a “movement polygon.” These polygons are further transformed into a one-dimensional space by computing amplitudes at different angles from the centroid of polygons. The feature vector is formed by the sampling of these amplitudes at different angles. The performance of the algorithm is evaluated using a support vector machine on four public datasets: MSR Action3D, Berkeley MHAD, TST Fall Detection, and NTU-RGB+D, and the highest accuracies achieved on these datasets are 94.13%, 93.34%, 95.7%, and 86.8%, respectively. These accuracies are compared with similar state-of-the-art and show superior performance.
Simplified approach for the evaluation of critical stresses in concrete pavement
Rameshwar J. Vishwakarma,Ramakant K. Ingle 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.3
Concrete pavements are subjected to traffic and environmental loadings. Repetitive type of such loading cause fatigue distress which leads to failure by forming cracks in pavement. Fatigue life of concrete pavement is calculated from the stress ratio (i.e. the ratio of applied flexural stress to the flexural strength of concrete). For the correct estimation of fatigue life, it is necessary to determine the maximum flexural tensile stress developed for practical loading conditions. Portland cement association PCA (1984) and Indian road congress IRC 58 (2015) has given charts and tables to determine maximum edge stresses for particular loading and subgrade conditions. It is difficult to determine maximum stresses for intermediate loading and subgrade conditions. The main purpose of this study is to simplify the analysis of rigid pavement without compromising the accuracy. Equations proposed for determination of maximum flexural tensile stress of pavement are verified by finite element analysis.
Non-blinking dendritic crystals from C-dot solution
Ashmi Mewada,Ritesh Vishwakarma,Bhushan Patil,Chinmay Phadke,Golap Kalita,Maheshwar Sharon,Madhuri Sharon 한국탄소학회 2015 Carbon Letters Vol.16 No.3
Bio-imaging and drug carriers for delivery have created a huge demand for crystals. Crystals are fascinating materials that have been grown for a long time but obtaining biocompatible fluorescent crystals is a challenging task. We report on the growth of fluorescent crystals using a carbon dot (C-dot) solution by a hydrothermal process. The crystallization pattern of these C-dots exhibited a unique dendritic structure having a feather-like morphology. The growth temperature and pressure were maintained at 60°C and 200 mmHg, respectively, for crystal growth. A green fluorescence (under UV light) that was observed in the C-dot solution was retained in the crystals formed from the solution. Cytotoxicity studies on Vero cells revealed the crystals to be extremely biocompatible. These fluorescent crystals are extremely well suited for biomedical and optoelectronic applications.