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Magnesium based implants for functional bone tissue regeneration–A review

Journal of Magnesium and Alloys 2022年第2期10卷 384-419页

作者： Gavish Uppal amit thakur amit Chauhan Saroj Bala University Institute of Engineering and Technology Panjab Universitysector-14ChandigarhIndia Sri Guru Gobind Singh College Panjab Universitysector-26ChandigarhIndia

Magnesium(Mg)has emerged as one of the third-generation biomaterials for regeneration and support of functional bone *** is a better choice over permanent implants such as titanium,stainless steel,cobalt-chrome as magnesium is biodegradable and does not require a second surgery for its removal after bone tissue *** also reduces the risk of stress shielding as its elastic modulus is closer to human bone in comparison to permanent implants and other biodegradable metallic implants based on Iron and *** importantly,Mg is osteoconductive thus stimulates new bone formation and possess anti-bacterial properties hence reducing the risk of failure due to *** its advantages,a major concern with pure Mg is its rapid bio-corrosion in presence of body fluids due to which the mechanical integrity of the implant deteriorates before healing of the tissue is *** properties of Mg-based implants can be enhanced by mechanical processing,alloying,and topology *** reduce the corrosion/degradation rate,Mg has been alloyed with metals,reinforced with ceramics,and surface coatings have been applied so that the degradation rate of Mg-based implant matches with that of healing rate of bone *** present review discusses the effect of alloying elements and reinforcing ceramics on microstructure,mechanical,and corrosion properties of Mg-based orthopedic *** addition,the biocompatibility of Mg-based alloys,composites,and coatings applied on Mg implants has been ***,different methods of fabricating porous implants have been highlighted as making the implant porous facilitates the growth of new bone tissue through the pores.

关键词： Magnesium Biodegradable orthopedic implant Porous structure Osteo-conductive Antibacterial

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Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes

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Earthquake Engineering and Engineering Vibration 2019年第2期18卷 351-362页

作者： amit thakur Deepankar Kumar Ashish Surender Kumar Verma Civil Engineering Department Kurukshetra University Civil Engineering Department Maharaja Agrasen Institute of Technology Maharaja Agrasen University Civil Engineering Department Punjab Engineering College (Deemed to be University)

In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y).

关键词： rooftop telecommunication tower set back-step back building response spectrum analysis steel, RC frame, earthquake SAP2000

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Combustion enhancement in rearward step based scramjet combustor by air injection at step base

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Propulsion and Power Research 2021年第3期10卷 224-234页

作者： amit thakur Nishanth Thillai Amritesh Sinha Mechanical Engineering PES UniversityIndia Institute for Aerospace Studies University of TorontoCanada Aerodynamics Energetics and PropulsionISAE SupaeroFrance

Numerical simulations were performed to model the non-reacting and reacting flow behind a rearward step flameholder in Mach 1.6 supersonic flow with fuel injection at the step *** combustor geometry was based on the University of Florida scramjet experimental *** was modeled using k-u shear stress transport(SST),laminar flamelet was used for combustion *** static pressure showed good agreement with experimental data for non-reacting and reacting *** non-reacting flow,dummy fuel helium mole fraction distribution in the recirculation region behind the step was validated with planar laser induced fluorescence(PLIF)images in *** improve the combustion characteristics,air was injected in tandem with hydrogen at step base using various *** all fuel injection as baseline,the case with 2 air jets around each fuel jet and air injected at 2 times the stagnation pressure of fuel showed the most improvement compared to other *** was most effective in reducing the local fuel richness,shortening the flame length and increasing combustion efficiency.

关键词： Step flameholder Scramjet combustor Local equivalence ratio Air injection Combustion efficiency

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Analysis of flow-field in a dual mode ramjet combustor with boundary layer bleed in isolator

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Propulsion and Power Research 2021年第1期10卷 37-47页

作者： Nishanth Thillai amit thakur Srikrishnateja K. Dharani J. Department of Mechanical Engineering PES UniversityBangaloreIndia

A two-dimensional Reynolds averaged Navier Stokes(RANS)simulation of a dual mode ramjet(DMRJ)combustor is performed,modeling the University of Michigan dual-mode combustor experimental setup operating in reacting mode with different equivalence ratios(4).The simulations are carried out using a k-u SST turbulence model and a steady diffusion flamelet model for non-premixed *** enters the isolator at Mach 2.2,stagnation pressure and temperature of 549.2 kPa and 1400 K *** is injected transverse to the flow direction and upstream of the cavity flame holder to simulate ramjet(4 Z 0.29)and scramjet(4 Z 0.19)modes of *** static pressure plots are used to validate numerical results against experimental *** of flow separation in ramjet mode due to the presence of a shock train in the isolator is carried out by means of numerical Schlieren images overlapped with contours of negative axial velocity,showing the effects of shock wave boundary layer interaction(SWBLI).Active control through wall normal boundary layer bleed in the separated flow region is implemented,which weakens the shock train and moves it downstream closer to the *** results in an improved stagnation pressure recovery in ramjet mode,with a marginal increase in combustion efficiency.

关键词： Dual mode ramjet Scramjet combustor Shock wave boundary layer interaction Boundary-layer bleed Flamelet combustion model

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Design and development of a plastic scintillator based whole body β/γ contamination monitoring system

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Nuclear Science and Techniques 2021年第5期32卷 33-42页

作者： Vaishali M.thakur amit Jain P.Ashokkumar Rekha Anilkumar Pravin Sawant Probal Chaudhury L.M.Chaudhari Radiation Safety Systems Division Bhabha Atomic Research CentreMumbai 400085India Health Physics Division Bhabha Atomic Research CentreMumbai 400085India Department of Physics Nowrosjee Wadia CollegePuneMaharashtra 411001India

Plastic scintillation detectors based whole body β/γ contamination monitors are developed for use in radiation *** microcontroller-based multi-detector system uses 13 plastic scintillator detectors,with minimized dead detection zones,monitoring the whole body,and conforming to the contamination limit prescribed by the regulatory *** system has the features for monitoring hands,feet,head,and faceβ/γusing contamination monitors and portal exit *** can detect gamma sources at a dose rate of 10 n Gyh^(-1).The system is calibrated using b sources^(90)Sr/^(90)Y,^(204)Tl,and^(36)Cl,and the efficiency is found to be 29%,22%,and 18%,***β/γcontaminationis0.15 Bqcm^(-2),which is significantly less than the minimum detection objectives on head,face,hands,and feet.

关键词： Plastic scintillation detector Contamination monitor Microcontroller Minimum Detection Objective(MDO) Minimum Detection Concentration(MDC)

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Comparison of rare earths doping(neodymium and samarium) on structural and magnetic properties of Ni-Zn-Bi nanoferrites

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Journal of Rare Earths 2024年第3期42卷 534-542,I0004页

作者： Shilpa Taneja Preeti thakur Dinesh Kumar Yassine Slimani Atul thakur NanoLatticeX Amity University HaryanaGururam122413HaryanaIndia Nanotechnology Wing Innovative Science Research SocietyShimla177002India Centre for Nanotechnology Amity University HaryanaGururam122413HaryanaIndia Department of Biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia School of Electronics and Information Engineering Nanjing University of Information Science&TechnologyNanjing210044China

Excellent magnetic properties in ferrites are required for high-frequency applications and for wastewater treatment. Thus, the present study shows the comparison of magnetic and structural properties of Nd and Sm substituted Ni-Zn-Bi ferrites with the series Ni_(0.5)Zn_(0.5)Bi_(0.04)Nd_(x)Fe_(1.96-x)O_4(with step size 0.002)and Ni_(0.5)Zn_(0.5)Bi_(0.04)Sm_(x)Fe_(1.96-x)O_4(with step size 0.02) prepared using citrate precursor method. The impact of the substitution of rare earth ions(Nd and Sm) on magnetic properties of the synthesized samples is observed using a vibrating sample magnetometer(VSM). The saturation magnetization values enhance considerably from 52 to 58 emu/g for Nd^(3+)ions and 39 to 57 emu/g for Sm^(3+) ions, thus, making these materials magnetically hard. Further, the higher value of coercivity is also observed ranging from133 to 167 Oe for Nd^(3+)ions and 81 to 155 Oe for Sm^(3+) ions. The shape of hysteresis loops indicates a super paramagnetic and ferromagnetic behavior in the obtained samples. The squareness ratio value is<0.5, suggesting the uniaxial anisotropy of particles and hence, these ferrites are suitable for microwaveabsorbing and in permanent magnetic materials. The X-ray diffraction(XRD) pattern shows the formation of pure cubic crystallites, where, lattice parameters range from 0.840 to 0.839 nm and from 0.838to 0.839 nm for Nd^(3+)and Sm^(3+) ions substitution, respectively. The crystallite size ranges between 28.63to 29.89 nm and 18.33 to 26.23 nm, for substitution of Nd^(3+)and Sm^(3+) ions, respectively. Field emission scanning electron microscopy(FESEM) shows the formation of homogeneous grains, whereas, energy dispersive spectrometer(EDS) counts describe the purity of the samples. The Sm concentration x = 0.10has the maximum surface area with value of 42.6 m^(2)/g which proves to be having good data storage application due to high surface area. The zero-field cooled(ZFC) and field cooled(FC) data show that Nddoped Ni-Zn-Bi nano

关键词： Citrate precursor X-ray diffraction Vibrating sample magnetometer Coercivity Field emission scanning electron microscopy Rare earths

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Modified chitosan hydrogels as drug delivery and tissue engineering systems:present status and applications

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Acta Pharmaceutica Sinica B 2012年第5期2卷 439-449页

作者： Tapan Kumar Giri Amrita thakur amit Alexander Ajazuddin Hemant Badwaik Dulal Krishna Tripathi Rungta College of Pharmaceutical Sciences and Research KurudBhilai 491024India

Chitosan,a natural cationic polysaccharide,is prepared industrially by the hydrolysis of the aminoacetyl groups of chitin,a naturally available marine *** is a non-toxic,biocompatible and biodegradable polymer and has attracted considerable interest in a wide range of biomedical and pharmaceutical applications including drug delivery,cosmetics,and tissue *** primary hydroxyl and amine groups located on the backbone of chitosan are responsible for the reactivity of the polymer and also act as sites for chemical ***,chitosan has certain limitations for use in controlled drug delivery and tissue *** limitations can be overcome by chemical ***,modified chitosan hydrogels have gained importance in current research on drug delivery and tissue engineering *** paper reviews the general properties of chitosan,various methods of modification,and applications of modified chitosan hydrogels.

关键词： Modified chitosan Hydrogels Drug delivery Oral delivery of protein Tissue engineering

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Plastic scintillator detector for qualitative and quantitative measurements of gamma radiation

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Radiation Detection Technology and Methods 2023年第4期7卷 578-588页

作者： Vaishali M.thakur Nitin Bhosale amit Jain Mukesh Sharma L.M.Chaudhari Probal Chaudhury Radiation Safety Systems Division Bhabha Atomic Research CentreTrombayMumbai400085India Department of Physics Nowrosjee Wadia CollegePune411001India

Background Plastic scintillator detectors are rugged and easily manufactured in desired shape,sizes and response time to gamma radiation is prompt as compared with any other scintillator *** popular these detectors are used in radiation monitors one of the application to restrict radioactive material *** are used in gross counting mode to know the presence of *** secondary survey is required to know the nature of the *** The feasibility study of Cylindrical Plastic Scintillator Detector(CPSD)was carried out for the qualitative and quantitative assessment of gamma emitting *** In this work limited gamma spectrometry was carried out using NE110 equivalent cylindrical plastic scintillating material of 5.1 cm diameter and 100 cm *** is optically coupled to photomultiplier tube(PMT).The detector signal is processed using preamplifier,shaping amplifier and further analysed by a multi channel analyser(MCA).CPSD gamma spectrum consists of Compton continuum and Gaussian shaped Compton edge energy(λ_(e))appearing as Compton maxima energy(λ_(max)).Photon transport simulation is used to characterizeλ_(max) as a signature for radionuclides emitting gamma energy/*** case of unresolved gamma energies,it appears as weighted effective Compton maxima *** prominent gamma energies observed across nuclear industries are in the energy range 0.03–3 *** is grouped as low energy,intermediate energy,high energy and ultra-high energy *** simulated spectrum is obtained suing Gaussian broadening parameters deduced from experimentally measured *** efficiency response function is developed from simulated response of detector to standard gamma sources under known source detector *** The mono energetic gamma emitting radioisotopes are identified againstλ_(max) from data *** analysis of spectrum is used to discriminate artificial radioactive materi

关键词： Plastic scintillator detector Gaussian broadening Compton edge Compton maxima Weighted effective Compton maxima Gamma spectrum Multi-channel analyzer

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Identification and characterization of integron mediated antibiotic resistance in pentachlorophenol degrading bacterium isolated from the chemostat

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Journal of Environmental Sciences 2009年第6期21卷 858-864页

作者： SHARMA Ashwani thakur Indu Shekhar Environmental Biotechnology Laboratory School of Environmental SciencesJawaharlal Nehru UniversityNew Mehrauli Road

A bacterial consortium was developed by continuous enrichment of microbial population isolated from sediment core of pulp and paper mill effluent in mineral salts medium（MSM） supplemented with pentachlorophenol（PCP） as sole source of carbon and energy in the *** consortia contained three bacterial *** were identified as Escherichia coli,Pseudomonas aeruginosa and Acinetobacter *** 16S rRNA gene sequence *** *** degraded PCP through the formation of tetrachloro-p-hydroquinone（TecH）,2-chloro-1,4-benzenediol and products of ortho ring cleavage detected by gas chromatograph/mass spectrometer（GC-MS）.Out of the three acclimated PCP degrading bacterial strains only one strain,Acinetobacter *** the presence of integron gene cassette as a marker of its stability and antibiotic *** strain possessed a 4.17 kb amplicon with 22 ORF＇*** plasmid isolated from the Acinetobacter *** subjected to shotgun cloning through restriction digestion by BamHI,HindIII and SalI,ligated to pUC19 vector and transformed into *** XLBlue1α,and finally selected on MSM containing PCP as sole source of carbon and energy with ampicillin as antibiotic *** sequence analysis of recombinant clones indicated homology with integron gene cassette and multiple antibiotic resistance genes.

关键词： Acinetobacter sp. antibiotic resistance gene chemostat integron gene cassette pentachlorophenol recombinant clone

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Towards POI-based large-scale land use modeling: spatial scale, semantic granularity, and geographic context

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International Journal of Digital Earth 2023年第1期16卷 430-445页

作者： Junchuan Fan Gautam thakur Geospatial Science and Human Security Division Oak Ridge National LaboratoryOak RidgeTNUSA

The combination of spatial distribution,semantic characteristics,and sometimes temporal dynamics of POIs inside a geographic region can capture its unique land use *** previous studies on POI-based land use modeling research focused on one geographic region and select one spatial scale and semantic granularity for land use *** is a lack of understanding on the impact of spatial scale,semantic granularity,and geographic context on POI-based land use modeling,particularly large-scale land use *** this study,we developed a scalable POI-based land use modeling framework and examined the impact of these three factors on POI-based land use characterization using data from three geographic *** developed a unified semantic representation framework for POI semantics that can help fuse heterogeneous POI data ***,by combining POIs with a neural network language model,we developed a spatially explicit approach to learn the embedding representation of POIs and *** trained multiple supervised classifiers using AOI embeddings as input features to predict AOI land use at different semantic *** classification performance of different land use classes was analyzed and compared across three geographic regions to identify the semantic representativeness of POI-based AOI embedding and the impact of geographic context.

关键词： Land use POI geospatial semantic deep learning semantic granularity spatial scale

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