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Effect of ultrasonic assisted sintering on mechanical properties and degradation behaviour of Mg15Nb3Zn1Ca biomaterial 被引量:1
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作者 ajit kumar Pulak M Pandey 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2021年第6期1989-2008,共20页
The present work investigates the effect of ultrasonic power(%)and the time of ultrasonic vibration on the sintered density and ultimate compressive strength(UCS)of Mg15Nb3Zn1Ca fabricated using ultrasonic assisted co... The present work investigates the effect of ultrasonic power(%)and the time of ultrasonic vibration on the sintered density and ultimate compressive strength(UCS)of Mg15Nb3Zn1Ca fabricated using ultrasonic assisted conventional sintering(UACS).The customized UACS setup was designed and manufactured to conduct the experimentations.A customized ultrasonic stepped horn assembly was used for providing vibrations to the sample during sintering.Further,to evaluate the efficacy of ultrasonic vibration parameters,the developed setup was used to sinter Mg15Nb3Zn1Ca composite material.The study unveiled an increased sintered density and UCS of the fabricated sample by the increase in ultrasonic power(%).Moreover,a decrease in sintered density and UCS was observed with an increase in the time of ultrasonic vibration beyond a certain limit.Samples sintered with the assistance of ultrasonic vibration at 100%ultrasonic power,and 20 min of ultrasonic vibration resulted in a sintered density of 1.928±0.062 g·cm^(-3)and UCS of 234.9±12.3 MPa.The obtained mechanical properties of the fabricated sample were comparable to the properties of cortical bone.The surface morphology and elemental compositions of samples fabricated using UACS declared a fair dispersion of reinforcement in the matrix containing merely the source elements.The results of corrosion test have showed that the assistance of ultrasonic vibration suppressed the degradation behaviour of the sintered sample after performing electrochemical study of samples using 3-electorde cell voltammetry.Mg15Nb3Zn1Ca fabricated using UACS showed a 50.18%and 9.08%of reduction in corrosion rate over conventionally sintered pure Mg and Mg15Nb3Zn1Ca respectively.In addition,electrochemical impedance spectroscopy(EIS)results indicated an enhanced corrosion resistance of the Mg15Nb3Zn1Ca composite material when fabricated at 100%of ultrasonic power with 20 min of vibration time.Apart from that,electrochemical equivalent circuits also resulted in good fitting of the experimental data obtained from EIS. 展开更多
关键词 Ultrasonic assisted sintering MAGNESIUM Corrosion EIS Mechanical properties
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Development of Mg based biomaterial with improved mechanical and degradation properties using powder metallurgy 被引量:1
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作者 ajit kumar Pulak M.Pandey 《Journal of Magnesium and Alloys》 SCIE EI CAS 2020年第3期883-898,共16页
In the present work,biocompatible materials such as niobium(Nb),zinc(Zn)and calcium(Ca)have been blended with magnesium(Mg)to develop a novel biomaterial(BM)with improved mechanical and corrosion resistant properties.... In the present work,biocompatible materials such as niobium(Nb),zinc(Zn)and calcium(Ca)have been blended with magnesium(Mg)to develop a novel biomaterial(BM)with improved mechanical and corrosion resistant properties.Powder metallurgy(PM)technique was used to fabricate Mg based BM.The powder of all aforementioned materials were mixed homogenously in specific quantities to create a uniform composite component.In order to analyse the influence of process parameters on the mechanical properties of the fabricated part,experiments were performed considering central composite design(CCD).The effect of powder metallurgical parameters namely percentage Nb,compaction pressure,heating rate,sintering temperature and soaking time on the ultimate compressive strength(UCS)and sintered density was studied in the present study.It was found that the UCS and sintered density increased with increase in compaction pressure,heating rate and sintering temperature.The results also revealed that the increase in soaking time and percentage Nb,increased sintered density and UCS to a certain limit.Subsequent increase in these two parameters,sintered density and UCS decreased.Scanning electron microscopy(SEM)images of the fabricated samples showed reduction in porosity with the increase in heating rate.Moreover,X-ray diffraction(XRD)results revealed that no other phase or impurities were found during sintering of Mg based BMs.The optimum process parameters were obtained to develop Mg based BM for maximum UCS and sintered density.Furthermore,the Mg based BM samples fabricated at optimum process parameters were used for corrosion testing in simulated body fluid(SBF)solution at a temperature of 37±0.5℃.The Mg based BM yielded improved mechanical properties with reduced corrosion rates as compared to pure Mg. 展开更多
关键词 BIOMATERIALS Powder metallurgy MAGNESIUM CORROSION Metal matrix composite
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Coping up with the Information Overload in the Medical Profession 被引量:1
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作者 ajit kumar Sanjeev Maskara 《Journal of Biosciences and Medicines》 2015年第11期124-127,共4页
The recent technological advancement has proved to be tremendously helpful for medical consultants. However, this advancement has also generated an enormous volume and variety of data, with a high velocity causing an ... The recent technological advancement has proved to be tremendously helpful for medical consultants. However, this advancement has also generated an enormous volume and variety of data, with a high velocity causing an information load for the medical consultants. Information overload can be defined as a difficulty a person can have in comprehending issue and making judgments that are caused by the presence of too much information. Information overload occurs when the amount of input to a system surpasses its processing capability. Decision-makers have a limited cognitive processing ability. Consequently, when information overload happens, it is possible that a decline in decision quality will take place. Decision-makers, such as medical consultants, have fairly limited cognitive processing capacity. Consequently, when information overload occurs, it is likely that a reduction in decision quality will occur. The aim of this study is to assess the impact of information overload on medical consultants’ life, its causes, and potential ways to deal with it. We performed a literature review to find the effects of information overload on medical consultants. Twelve research papers were considered for thematic analysis using NVivo 10 tool. These papers revealed four themes: 1) traditional methods of data collection;2) modern ways of data collection;3) consequences of modern ways of data collection;and 4) the need for handling information overload. This study suggests the development of a Continuing Professional Development course that explains how to deal with information overload, and availing the same through E-Learning mode might be one immediate solution. 展开更多
关键词 Information OVERLOAD E-LEARNING Continuous PROFESSIONAL Development MEDICAL CONSULTANT
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Mitigation on self-discharge behaviors via morphological control of hierarchical Ni-sulfides/Ni-oxides electrodes for long-life-supercapacitors
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作者 Dhananjay Mishra Niraj kumar +2 位作者 ajit kumar SeungGi Seo SungHun Jin 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2022年第18期217-228,共12页
To cope up with the sustainable energy storage goals for supercapacitors(SCs),the self-discharge in SC electrodes is a significant hurdle,and thereby,nickel sulfide(NS)with high conductivity is adopted as a test vehic... To cope up with the sustainable energy storage goals for supercapacitors(SCs),the self-discharge in SC electrodes is a significant hurdle,and thereby,nickel sulfide(NS)with high conductivity is adopted as a test vehicle for understanding the morphological evolution effects for long-life SCs.Herein,honeycomb-like NS is hierarchically formed over hydrothermally grown nickel oxide(NO)via successive ionic layer adsorption reaction(SILAR)method.Their heterostructure shows a fivefold improvement in specific capacitance from 348 F g^(−1) to 2077 F g^(−1)at 1 mV s^(−1) over bare NO.Furthermore,the remarkable upliftment of capacitance retention is achieved from 60.7%to 92.3%even after 3000 cycles via morphological control of NS/NO hetero-structure with the help of highly conductive NS.More importantly,the self-discharge behaviors and synergistic role of leakage current associated with morphological evolution via NS overcoating are studied in detail.In particular,the self-discharge mitigation from 45%(NO)to 35%(NS20/NO)due to the NS/NO heterostructure and the behind mechanism are ascribed to the activated-controlled Faradaic reaction coupled with a charge redistribution.This study emphasizes the potential importance of composite heterostructure by tuning the electrical conductivity and morphological adjustment NO via consecutive overcoating of NS through SILAR as a novel strategy.This enhances charge storage,redox kinetics,and the mitigation of self-discharge properties of the active electrode materials.For practical validation on sustainable energy storage,NS20/NO supercapacitors illuminate the LED for 35%longer than NO after one-time charging,potentially beneficial for the next generation SCs. 展开更多
关键词 Morphological evolution SELF-DISCHARGE SILAR overcoating SUPERCAPACITORS HETEROSTRUCTURE
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Identifying Semantic in High-Dimensional Web Data Using Latent Semantic Manifold
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作者 ajit kumar Sanjeev Maskara I-Jen Chiang 《Journal of Data Analysis and Information Processing》 2015年第4期136-152,共17页
Latent Semantic Analysis involves natural language processing techniques for analyzing relationships between a set of documents and the terms they contain, by producing a set of concepts (related to the documents and ... Latent Semantic Analysis involves natural language processing techniques for analyzing relationships between a set of documents and the terms they contain, by producing a set of concepts (related to the documents and terms) called semantic topics. These semantic topics assist search engine users by providing leads to the more relevant document. We develope a novel algorithm called Latent Semantic Manifold (LSM) that can identify the semantic topics in the high-dimensional web data. The LSM algorithm is established upon the concepts of topology and probability. Asearch tool is also developed using the LSM algorithm. This search tool is deployed for two years at two sites in Taiwan: 1) Taipei Medical University Library, Taipei, and 2) Biomedical Engineering Laboratory, Institute of Biomedical Engineering, National Taiwan University, Taipei. We evaluate the effectiveness and efficiency of the LSM algorithm by comparing with other contemporary algorithms. The results show that the LSM algorithm outperforms compared with others. This algorithm can be used to enhance the functionality of currently available search engines. 展开更多
关键词 LATENT SEMANTIC MANIFOLD Conditional Random Field Hidden Markov Model Graph-Based TREE-WIDTH Decomposition
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Effect of Filler Content and Alkalization on Mechanical and Erosion Wear Behavior of CBPD Filled Bamboo Fiber Composites
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作者 Anu Gupta ajit kumar +1 位作者 Amar Patnaik Sandhyarani Biswas 《Journal of Surface Engineered Materials and Advanced Technology》 2012年第3期149-157,共9页
In this study the mechanical and erosion wear behavior of bamboo fiber reinforce epoxy composites filled with Cement By-Pass Dust (CBPD) were studied. The effect of CBPD content and alkalization on the various propert... In this study the mechanical and erosion wear behavior of bamboo fiber reinforce epoxy composites filled with Cement By-Pass Dust (CBPD) were studied. The effect of CBPD content and alkalization on the various properties of these composites was also investigated. Taguchi’s orthogonal arrays are used for analysis of experiential results. It identifies significant control factors influencing the erosion wear and also outlines significant interaction effects. Analysis of variance (ANOVA) test has also been performed on the measured data to find the most significant factors affecting erosion rate. Finally, eroded surfaces of both untreated and alkali treated bamboo fiber reinforced composites were characterized using SEM. 展开更多
关键词 COMPOSITES BAMBOO Fiber MECHANICAL Property EROSION Wear CBPD
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Document Clustering Using Semantic Cliques Aggregation
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作者 ajit kumar I-Jen Chiang 《Journal of Computer and Communications》 2015年第12期28-40,共13页
The search engines are indispensable tools to find information amidst massive web pages and documents. A good search engine needs to retrieve information not only in a shorter time, but also relevant to the users’ qu... The search engines are indispensable tools to find information amidst massive web pages and documents. A good search engine needs to retrieve information not only in a shorter time, but also relevant to the users’ queries. Most search engines provide short time retrieval to user queries;however, they provide a little guarantee of precision even to the highly detailed users’ queries. In such cases, documents clustering centered on the subject and contents might improve search results. This paper presents a novel method of document clustering, which uses semantic clique. First, we extracted the Features from the documents. Later, the associations between frequently co-occurring terms were defined, which were called as semantic cliques. Each connected component in the semantic clique represented a theme. The documents clustered based on the theme, for which we designed an aggregation algorithm. We evaluated the aggregation algorithm effectiveness using four kinds of datasets. The result showed that the semantic clique based document clustering algorithm performed significantly better than traditional clustering algorithms such as Principal Direction Divisive Partitioning (PDDP), k-means, Auto-Class, and Hierarchical Clustering (HAC). We found that the Semantic Clique Aggregation is a potential model to represent association rules in text and could be immensely useful for automatic document clustering. 展开更多
关键词 Document Clustering SEMANTIC CLIQUE ASSOCIATION AGGREGATION THEME
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Reversible and controllable threshold voltage modulation for n-channel MoS2 and p-channel MoTe_(2 )field-effect transistors via multiple counter doping with ODTS/poly-L-lysine charge enhancers 被引量:2
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作者 Seung Gi Seo Jinheon Jeong +2 位作者 Seung Yeob Kim ajit kumar Sung Hun Jin 《Nano Research》 SCIE EI CSCD 2021年第9期3214-3227,共14页
Confronted by the inherent physical limitations in scaling down Si technology,transition metal dichalcogenides(TMDCs)as alternatives are being tremendously researched and paid attention to.However,mature counter dopin... Confronted by the inherent physical limitations in scaling down Si technology,transition metal dichalcogenides(TMDCs)as alternatives are being tremendously researched and paid attention to.However,mature counter doping technology for TMDCs is still elusive,and thus,a controllable and reversible charge enhancer is adopted for acceptor(or donor)-like doping via octadecyltrichlorosilane(ODTS)(or poly-L-lysine(PLL))treatment.Furthermore,multiple counter doping for TMDC field-effect transistors(FETs),combined with a threshold voltage(V;h)freezing scheme,renders the V_(th) modulation controllable,with negligible degradation and decent sustainability of FETs even after each treatment of a representative charge enhancer.In parallel,the counter doping mechanism is systematically investigated via photoluminescence spectroscopy,X-ray photoelectron spectroscopy,atomic force microscopy(AFM),surface energy characterization,and measurement of optoelectronic properties under illumination with light of various wavelengths.More impressively,complementary inverters,composed of type-converted molybdenum ditelluride(MoTe_(2)>FETs and hetero-TMDC FETs in enhancement mode,are demonstrated via respective ODTS/PLL treatments.Herein,driving backplane application for micro-light-emitting diode(p-LED)displays and physical validation of a corresponding counter doping scheme even for flexible polyethylene terephthalate(PET)substrates could be leveraged to relieve daunting challenges in the application of nanoscale Si-based three-dimensional(3D)stacked systems,with potential adoption of ultralow power and monolithic optical interconnection technology. 展开更多
关键词 transition metal dichalcogenides(TMDCs) counter doping charge enhancer field-effect transistors micro-light-emitting diode(m-LED)
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