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Synthetic and biological studies on a cyclopolypeptide of plant origin

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第5期9卷 391-400页

作者： rajiv DAHIYA Akhilesh kumar Department of Pharmaceutical Chemistry Rajiv Academy for Pharmacy

Objective:A natural cyclic peptide previously isolated from Citrus medica was synthesized by coupling of tetrapep-tide units Boc-Leu-Pro-Trp-Leu-OMe and Boc-Ile-Ala-Ala-Gly-OMe after proper deprotection at carboxyl and amino terminals followed by cyclization of linear octapeptide segment. Methods:Solution phase technique was adopted for the synthesis of cyclooctapeptide-sarcodactylamide. Required tetrapeptide units were prepared by coupling of Boc-protected dipeptides viz. Boc-Leu-Pro-OH and Boc-Ile-Ala-OH with respective dipeptide methyl esters Trp-Leu-OMe and Ala-Gly-OMe. Cyclization of linear octapeptide unit was done by p-nitrophenyl ester method. The structure of synthesized cyclopolypeptide was elucidated by FTIR,1H NMR,13C NMR,FABMS spectral data and elemental analysis. The newly synthesized peptide was evaluated for dif-ferent pharmacological activities including antimicrobial,anthelmintic and cytotoxic activities. Results:Synthesis of sarcodac-tylamide was accomplished with >78% yield utilizing dicyclohexylcarbodiimide(DCC) as coupling agent. Newly synthesized peptide possessed potent cytotoxic activity against Dalton's lymphoma ascites(DLA) and Ehrlich's ascites carcinoma(EAC) cell lines,in addition to moderate anthelmintic activity against earthworms Megascoplex konkanensis,Pontoscotex corethruses and Eudrilus sp. Moreover,cyclopolypeptide displayed good antimicrobial activity against pathogenic fungi Candida albicans and Gram-negative bacteria Pseudomonas aeruginosa,in comparison to standard drugs griseofulvin and ciprofloxacin. Conclusion:Solution phase technique employing DCC and triethylamine(TEA) as base proved to be effective for the synthesis of natural cyclooctapeptide. N-methyl morpholine(NMM) was found to be a better base for the cyclization of linear octapeptide unit in comparison to TEA and pyridine.

关键词： Cyclic octapeptide Citrus medica var. sarcodactylis Sarcodactylamide Peptide synthesis Anthelmintic activity Antimicrobial activity Cytotoxicity

Optical anisotropy and the direction of polarization of exciton emissions in a semiconductor quantum dot:Effect of heavy-and light-hole mixing

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Chinese Physics B 2017年第8期26卷 400-406页

作者： Ranber Singh rajiv kumar Vikramjeet Singh Department of Physics Sri Guru Gobind Singh CollegeSector 26Chandigarh 160019India Department of Physics DAV University JalandharPunjab 144012India IKGPTU Campus HoshiarpurPunjab 146001India

The dependence of the directions of polarization of exciton emissions, fine structure splittings （FSS）, and polarization anisotropy on the light- and heavy-hole （LH-HH） mixing in semiconductor quantum dots （QDs） is investigated using a mesoscopic model. In general, all QDs have a four-fold exciton ground state. Two exciton states have directions of polarization in the growth-plane, while the other two are along the growth direction of the QD. The LH-HH mixing does affect the FSS and polarization anisotropy of bright exciton states in the growth-plane in the low symmetry QDs （e.g., C2v, CS, C1 ）, while it has no effect on the FSS and polarization anisotropy in high symmetry QDs （e.g., C3V, D2d）. When the hole ground state is pure HH or LH, the bright exciton states in the growth-plane are normal to each other. The LH-HH mixing affects the relative intensities and directions of bright exciton states in the growth-plane of the QD. The polarization anisotropy of exciton emissions in the growth-plane of the QD is independent of the phase angle of LH-HH mixing but strongly depends on the magnitude of LH-HH mixing in low symmetry QDs.

关键词： light-heavy hole mixing excitons quantum dots

Catalytic effects of Cu-Co~* on the thermal decomposition of AN and AN/KDN based green oxidizer and propellant samples

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Defence Technology（防务技术） 2018年第3期14卷 250-260页

作者： Pratim kumar Puran Chandra Joshi rajiv kumar Shelly Biswas Department of Space Engineering & Rocketry Birla Institute of Technology Department of Mechanical Engineering Vidya Vihar Institute of Technology

This paper presents the catalytic effects of Cu-Co~* catalyst on the decomposition of AN and AN/KDN based oxidizer and propellant samples. Ozawa-Flynn-Wall(OFW) iso-conversional method was used for the kinetic studies and to compute the activation energy(Ea) values for various decomposition steps of the prepared oxidizer and propellant samples in the temperature range of 50 e500C. TG-DTG experiments were carried out for both oxidizer and propellant samples at the heating rates of 3, 5, and 10C/min. AN/KDN based oxidizer samples were prepared by an evaporative co-crystallization method. Citric acid sol-gel method was used for the synthesis of Cu-Co~* catalyst. The propellant sample contains HTPB as the fuel binder along with other ingredients such as TDI, DOA, and Glycerol. The Cu-Co~* catalyst was used as 2% by weight to the total weight of catalyzed oxidizer and propellant samples. It was observed from the present study that, Cu-Co~* catalyst helps in reducing the Ea values for AN and AN based propellant samples. However, with the percentage increment of KDN in the AN crystals, Ea value ***, it was observed that Cu-Co~* catalyst stabilizes the initial partial decomposition of KDN.

关键词：催化氧化剂催化效果热分解 Cu 燃料取样 TG-DTG 催化剂

Assessing the effects of different dielectrics onenvironmentally conscious powder-mixed EDM of difficult-to-machine material （WC-Co）

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Frontiers of Mechanical Engineering 2016年第4期11卷 374-387页

作者： Jagdeep SINGH rajiv kumar SHARMA Department of Mechanical Engineering National Institute of Technol-ogy Hamirpur Himachal Pradesh-177005 India

Electrical discharge machining (EDM) is a well-known nontraditional manufacturing process to machine the difficult-to-machine (DTM) materials which have unique hardness properties. Researchers have successfully performed hybridization to improve this process by incorporating powders into the EDM process known as powder-mixed EDM process. This process drastically improves process efficiency by increasing material removal rate, micro-hardness, as well as reducing the tool wear rate and surface roughness. EDM also has some input parameters, including pulse-on time, dielectric levels and its type, current setting, flushing pressure, and so on, which have a significant effect on EDM performance. However, despite their positive influence, investigating the effects of these parameters on environmental conditions is necessary. Most studies demonstrate the use of kerosene oil as dielectric fluid. Nevertheless, in this work, the authors highlight the findings with respect to three different dielectric fluids, including kerosene oil, EDM oil, and distilled water using one-variable-at-a-time approach for machining as well as environmental aspects. The hazard and operability analysis is employed to identify the inherent safety factors associated with powder-mixed EDM of WC-Co.

关键词： WC hazard and operability analysis (HAZOP) discharging aerosol concentration dielectrics powders

Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings:a novel trial misalignment approach

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Propulsion and Power Research 2021年第1期10卷 58-82页

作者： Prabhat kumar rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries,transport vehicles,and in several other *** vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous ***,there is a need for perceiving the dynamic nature and identifying the faults for the safe,smooth and effective operation of *** paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor *** magnetic bearing(AMB)misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment *** trial misalignments are provided in addition to the unknown misalignments of the residual misalignment *** the execution of this methodology,the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically *** offset discs result in the gyroscopic effect at high rotor *** of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions.A fast Fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and forcecurrent stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification *** values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown *** of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness

关键词： Misalignment Unbalance Active magnetic bearing Gyroscopic moment Fast Fourier transform Identification

Grid Tied Solar PV System with Power Quality Enhancement Using Adaptive Generalized Maximum Versoria Criterion

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CSEE Journal of Power and Energy Systems 2023年第2期9卷 722-732页

作者： Manoj Badoni Alka Singh Ankit kumar Singh Hemant saxena Rajeev kumar Delhi Technological University Delhi 110042India.A.K.Singh is with Netaji Subhas University of TechnologyDelhi 110078India Netaji Subhas University of Technology Delhi 110078India Electrical and Electronics Engineering Department KIET Group of InstitutionsGhaziabadIndia Electrical Engineering Department Jamia Millia IslamiaNew DelhiIndia

A three phase grid tied solar photovoltaic(PV)system with power quality compensation features is presented in this *** system is used to transfer power generated from a solar PV array to feed linear and nonlinear loads along with compensation for several power quality(PQ)issues,such as harmonics,redundant reactive power and load *** generated DC power from the PV array is converted into AC by implementing a three-phase voltage source converter(VSC).In order to transfer active power and mitigate PQ problems,an efficient control technique is required for the grid tied solar PV *** study presents the use of an adaptive generalized maximum Versoria criterion(AGMVC)controller for VSC used in a solar PV energy conversion *** utilization of the solar PV array is accomplished by using the Perturb and Observe based maximum power point tracking(MPPT)*** experimental setup of the grid integrated PV system is implemented in the laboratory using an IGBT based VSC and DSP(dSPACE DS-1202).The performance of the AGMVC control technique is verified experimentally using laboratory *** control technique is compared with different conventional controllers,such as synchronous reference frame theory(SRFT)and instantaneous reactive power theory(IRPT)along with recently developed weight-based controllers viz.,least mean square(LMS),least mean mixed norm(LMMN)and normalized kernel least mean fourth-neural network(NKLMFNN).Numerous terms,such as fundamental weight convergence,steady state error,computational complexity,phase lock loop(PLL)requirement and harmonic compensation capability,are considered for comparison purposes of AGMVC with the above listed control *** system performance is verified according to the IEEE-519 standard.

关键词： Harmonics maximum versoria criterion power factor corection(PFC) solar photovoltaic

Design of a Lightweight Compressed Video Stream-Based Patient Activity Monitoring System

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Computers, Materials & Continua 2024年第1期78卷 1253-1274页

作者： Sangeeta Yadav Preeti Gulia Nasib Singh Gill Piyush kumar Shukla Arfat Ahmad Khan Sultan Alharby Ahmed Alhussen Mohd Anul Haq Department of Computer Science&Applications Maharshi Dayanand UniversityRohtak124001India University Institute of Technology Rajiv Gandhi Proudyogiki VishwavidyalayaBhopal462033India Department of Computer Science College of ComputingKhon Kaen UniversityKhon Kaen40002Thailand Department of Computer Science College of Computer and Information SciencesMajmaah UniversityAl Majmaah11952Kingdom of Saudi Arabia Department of Computer Engineering College of Computer and Information SciencesMajmaah UniversityAl Majmaah11952Kingdom of Saudi Arabia

Inpatient falls from beds in hospitals are a common *** falls may result in severe *** problem can be addressed by continuous monitoring of patients using *** advancements in deep learning-based video analytics have made this task of fall detection more effective and *** with fall detection,monitoring of different activities of the patients is also of significant concern to assess the improvement in their *** computation-intensive models are required to monitor every action of the patient *** requirement limits the applicability of such ***,to keep the model lightweight,the already designed fall detection networks can be extended to monitor the general activities of the patients along with the fall *** by the same notion,we propose a novel,lightweight,and efficient patient activity monitoring system that broadly classifies the patients’activities into fall,activity,and rest classes based on their *** whole network comprises three sub-networks,namely a Convolutional Neural Networks(CNN)based video compression network,a Lightweight Pose Network(LPN)and a Residual Network(ResNet)Mixer block-based activity recognition *** compression network compresses the video streams using deep learning networks for efficient storage and retrieval;after that,LPN estimates human ***,the activity recognition network classifies the patients’activities based on their *** proposed system shows an overall accuracy of approx.99.7% over a standard dataset with 99.63% fall detection accuracy and efficiently monitors different events,which may help monitor the falls and improve the inpatients’health.

关键词： Fall detection activity recognition human pose estimation accuracy

Estimation of the internal and external damping from the forward and backward spectrum of a rotor with a fatigue crack

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Propulsion and Power Research 2020年第1期9卷 62-74页

作者： Dipendra kumar Roy rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India Faculty of Mechanical Engineering Indian Institute of Technology GuwahatiAssam781039India

Both internal and external damping are concurrently present in a rotor ***,the internal damping that originates from various sources often leads to instability in the rotor system,and hence its accurate estimation is *** goal of the present paper is to distinctly estimate both external and internal damping in a Jeffcott rotor containing transverse *** modelling of the fatigue crack is based on the assumption of a switching crack,which additionally provides the internal damping due to rubbing on crack faces,which is hardly addressed in ***,the fatigue crack leads to the forward and backward whirls due to asymmetry in the *** the process of development of the identification procedure in the form of the regression equation for the estimation of internal damping,other important unknown rotor system parameters,like the external damping,unbalance and loss of stiffness of the shaft due to the crack,are also *** reduces the estimation error of the internal damping due to reduction in deviations of other model *** simulated responses are obtained from equations of motion of the rotor system in the form of a closed-form expression and by the Runge-Kutta integration *** full-spectrum response data(both magnitude and phase)are utilized during the testing of the proposed identification *** corrections have been incorporated in the *** noise is added in numerical responses during identification of parameters to check the robustness of the algorithm and found to be working satisfactorily.

关键词： Internal damping External damping Switching crack Unbalance Full spectrum

Impact of open dumping of municipal solid waste on soil properties in mountainous region

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 725-739页

作者： Anchal Sharma Ashok kumar Gupta rajiv Ganguly Department of Civil Engineering Jaypee University of Information Technology

This paper presents the effect of open dumping of municipal solid waste(MSW) on soil characteristics in the mountainous region of Himachal Pradesh, India. The solid waste of dumpsite contains various complex characteristics with organic fractions of the highest proportions. As leachate percolates into the soil, it migrates contaminants into the soil and affects soil stability and strength. The study includes the geotechnical investigation of dump soil characteristics and its comparison with the natural soil samples taken from outside the proximity of dumpsites. The geochemical analysis of dumpsite soil samples was also carried out by scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS).Visual inspection revealed that the MSW consists of high fraction of organics, followed by paper. The soil samples were collected from five trial pits in the dumpsites at depths of 0.5 m, 1 m and 1.5 m. Then the collected soil samples were subjected to specific gravity test, grain size analysis, Atterberg’s limit test,compaction test, direct shear test, California bearing ratio(CBR) test and permeability analysis. The study indicated that the dumpsite soils from four study regions show decreasing trends in the values of maximum dry density(MDD), specific gravity, cohesion and CBR, and increasing permeability as compared to the natural soil. The results show that the geotechnical properties of the soils at all four study locations have been severely hampered due to contamination induced by open dumping of waste.

关键词： Municipal solid waste (MSW) Physical characterization Soil pollution Open dumping Scanning electron microscopy (SEM) Energy disperse X-ray spectroscopy (EDS)