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Journal of Materials Science and Chemical Engineering 2020年第9期8卷 31-44页

作者： muhammad Awais muhammad Shahid Mohsin Saleem Fariz Aneeq muhammad Shoaib Butt malik Adeel Umer School of Chemical and Materials Engineering National University of Sciences & Technology Islamabad Pakistan

Polychloroprene (PC) based contact adhesives are widely used in various applications;however, there is a possibility to improve the properties of PC adhesive. Modifications of polymers can enhance the properties of the material, e.g. increase in thermal stability, compatibility, rigidity, physical response, flexibility and improve the polymer process ability. In the current study, improved formulation of solvent-based adhesive was developed, and the properties were further enhanced by the addition of nano-reinforcement of multiwall carbon nanotubes (MWCNTs). The addition of nano-reinforcement was optimized to obtain improvement in the bond strength and also to enhance its resistance at a high temperature (~100°C). This paper discusses the uniform dispersion of MWCNTs during the synthesis of polychloroprene solvent-based adhesive, thereby improving its structural properties. Incorporation of MWCNTs-solvent-based adhesives resulted in a 20% - 35% improvement in 180° peel strength determined on flexible substrates such as canvas, leather. The reinforced based adhesive also exhibited improved thermal stability and weather resistance compared with unreinforced adhesive. The MWCNTs- solvent-based contact adhesives is a potential candidate in an industrially relevant branch of adhesives commonly used in structural applications, e.g., footwear, plastic, leather, automobile, construction industries, etc.

关键词： Nanocomposite Polychloroprene Adhesive Peel Strength Carbon Nanotubes

Corrosion Resistance of AZ91 Magnesium Alloy after Laser Remelting Treatment

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Journal of Wuhan University of Technology(Materials Science) 2016年第5期31卷 1075-1080页

作者： STRZELECKA Monika IWASZKO Jozef malik Marcin A Czestochowa University of Technology 42-200 Czestochowa Poland

The main objective of the study was the modification of the surface layer of magnesium alloy by the COlaser. The studied material was the commercial AZ91 magnesium alloy. The effectiveness of the alternations caused by the remelting process was verified on the basis of microscopic observation and corrosion investigations, i e, recording of potentiodynamic polarization curves, electrochemical noise measurements and hydrogen evolution rate measurements. For the adopted range of the treatment parameters, favourable changes were observed in the surface layer such as the refinement of structure and more uniform arrangement of individual phases. As a consequence of those favourable structural changes the improvement of the corrosion resistance of the alloy was achieved in comparison to its non-remelted equivalent. For the treated material corrosion rates expressed as corrosion current densities were at least three times lower than the appropriate values for the untreated alloy comparing them for the same period of samples immersion in the test solution. The obtained results have confirmed the effectiveness of the applied surface treatment resulting in favourable changes in the structure and corrosion properties of the AZ91 magnesium alloy.

关键词： magnesium alloy CO_2 laser surface layer modification corrosion

Behavior of Anisotropic Compact Stars in f(R,∅) Gravity

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Communications in Theoretical Physics 2019年第5期71卷 599-609页

作者： M.Farasat Shamir Adnan malik Department of Sciences and Humanities National University of Computer and Emerging Sciences

The aim of this paper is to investigate modified f(R, ?) theory of gravity, where R and ? represent the Ricci scalar and scalar potential respectively. Specifically, we take the spherically symmetric spacetime to discuss the possible emergence of compact stars. We study the physical behavior of compact stars by considering 4 U 1820-30, SAX J1808-3658 and Her X1, which are three popular models of compact stars. The graphical analysis of energy density, radial pressure, tangential pressure, energy conditions as well as stability of compact stars has been shown. It is concluded that behavior of these three stars is usual for f(R, ?) gravity models with some specific choices of model parameters.

关键词： f(R,∅) gravity spherically symmetric spacetime compact stars Klein-Gordon equation

Syntheses, Crystal Structures and Fluorescence Properties of Four Coordination Polymers Based on Enantiomeric 2-(4-Carboxyphenyl)-4,5-dihydrothiazole-4-carboxylic Acid Ligands

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Chinese Journal of Structural Chemistry 2020年第3期39卷 567-578,380页

作者： LIU Lu malik Abaid Ullah SHU Mou-Hai School of Chemistry and Chemical Engineering Shanghai Jiaotong UniversityShanghai 200240China

A pair of enatiomerically pure ligands,(R-)/(S-)2-(4-carboxyphenyl)-4,5-dihydrothiazole-4-carboxylic acid(H2L^R & H2L^S), have been synthesized by the reactions of 4-cyanobenzoic acid with L-and D-cysteine, respectively. Four coordination polymers have been prepared from the ligands and structurally determined by single-crystal X-ray diffraction analysis. Complexes 1 R and 1 S([NiL(Py)(H2 O)]×H2 O, for 1 R, L =(L^R)^(2-);for 1 S, L =(L^S)^(2-)) exhibit chiral helical one-dimensional chains, and complexes 2 R and 2 S({[ZnL2(H2 O)3]×CH3 CN}n, for 2 R L =(L^R)^(2-), for 2 S L =(LS)^(2-)) are two-dimensional sheets. Luminescent and chir-optical properties have been investigated and compared with the free ligands. The complexes have blue-shift in luminescence spectrum compared with the free ligands.

关键词： coordination polymer crystal structure chiral ligand fluorescence

Reprogramming cells with synthetic proteins

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Asian Journal of Andrology 2015年第3期17卷 394-402页

作者： Xiaoxiao Yang Vikas malik Ralf Jauch Genome Regulation Laboratory Guangzhou Institutes of Biomedicine and Health Chinese Academy of Sciences 190 Kai Yuan Avenue Science Park Guangzhou China

Conversion of one cell type into another cell type by forcibly expressing specific cocktails of transcription factors （TFs） has demonstrated that cell fates are not fixed and that cellular differentiation can be a two-way street with many intersections. These experiments also illustrated the sweeping potential of TFs to ＂read＂ genetically hardwired regulatory information even in cells where they are not normally expressed and to access and open up tightly packed chromatin to execute gene expression programs. Cellular reprogramming enables the modeling of diseases in a dish, to test the efficacy and toxicity of drugs in patient-derived cells and ultimately, could enable cell-based therapies to cure degenerative diseases. Yet, producing terminally differentiated cells that fully resemble their in vivo counterparts in sufficient quantities is still an unmet clinical need. While efforts are being made to reprogram cells nongeneticaUy by using *** molecules, defined TF cocktails still dominate reprogramming protocols. Therefore; the optimization of TFs by protein engineering has emerged as a strategy to enhance reprogramming to produce functional, stable and safe cells for regenerative biomedicine. Engineering approaches focused on Oct4, MyoD, Sox17, Nanog and Mef2c and range from chimeric TFs with added transactivation domains, designer transcription activator-like effectors to activate endogenous TFs to reprogramming TFs with rationally engineered DNA recognition principles. Possibly, applying the complete toolkit of protein design to cellular reprogramming can help to remove the hurdles that, thus far, impeded the clinical use of cells derived from reprogramming technologies.

关键词： cellular reprogramming protein design protein engineering synthetic transcription factors transactivation

Fault Detection for Microgrid Feeders Using Features Based on Superimposed Positive-sequence Power

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Journal of Modern Power Systems and Clean Energy 2023年第6期11卷 1948-1958页

作者： Salauddin Ansari Om Hari Gupta Om P.malik Department of Electrical Engineering National Institute of TechnologyJamshedpur 831014India IEEE Department of Electrical and Software Engineering University of Calgary2500 University Drive NWCalgary Alberta T2N 1N4Canada

With the integration of distributed generation(DG) into a microgrid, fault detection has become a major task to accomplish. A scheme for microgrid feeder protection based on a newly proposed feature, ΔRP, defined as the ratio of the sum of positive-sequence real power(PSRP) at the two ends of the feeder to the larger of the PSRPs among the two ends, is proposed. If ΔRP is larger than a threshold, an internal fault is detected;otherwise, the fault is external or there is no fault. The proposed scheme is tested in various scenarios, including fault type, fault resistance, fault location, fault inception angle, varying DG penetration levels, and simultaneous, evolving, and composite faults. In addition to this, the proposed scheme offers a robust performance when subjected to noise, synchronization error, changes in sampling frequency, and changes in the topology of a microgrid. The dominancy of the proposed scheme is proven by a comprehensive comparative study with various available recent schemes. Test results on the IEEE 13-bus network indicate the viability of the proposed protection scheme for a microgrid. Finally, the proposed scheme has been validated on a real-time simulator.

关键词： Fault detection distributed generation microgrid protection superimposed power

Exact solutions of MHD second Stokes flow of generalized Burgers fluid

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Applied Mathematics and Mechanics(English Edition) 2015年第2期36卷 211-224页

作者： M.KHAN R.malik A.ANJUM Department of Mathematics Quaid-i-Azam University

This work concerns with the exact solutions of magnetohydrodynamic（MHD）flow of generalized Burgers fluid describing the second Stokes problem. The modified Darcy law is taken into account. The related velocity distribution and shear stress are expressed as a combination of steady-state and transient solutions computed by means of integral transformations. The effects of various parameters on the flow field are investigated. The MHD flow results in reduction of velocity distribution and associated thickness of the boundary layer.

关键词： generalized Burgers fluid magnetohydrodynamic(MHD) flow porous medium exact solution

Reduced bit low power VLSI architectures for motion estimation

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Journal of Systems Engineering and Electronics 2013年第3期24卷 382-399页

作者： Shahrukh Agha Shahid Khan Shahzad malik Raja Riaz Department of Electrical Engineering COMSATS Institute of Information Technology

Low power and real time very large scale integration （VLSI） architectures of motion estimation （ME） algorithms for mobile devices and applications are presented. The power reduction is achieved by devising a novel correction recovery mechanism based on algorithms which allow the use of reduced bit sum of absolute difference （RBSAD） metric for calculating matching error and conversion to full resolution sum of absolute difference （SAD） metric whenever necessary. Parallel and pipelined architectures for high throughput of full search ME corresponding to both the full resolution SAD and the generalized RBSAD algorithm are synthe- sized using Xilinx Synthesis Tools （XST）, where the ME designs based on reduced bit （RB） algorithms demonstrate the reduction in power consumption up to 45% and/or the reduction in area up to 38%.

关键词： motion estimation (ME) very large scale integration (VLSI) reduced bit sum of absolute difference (RBSAD).

A Correlation Visual Analytics System for Air Quality

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Chinese Journal of Electronics 2018年第5期27卷 920-926页

作者： DU Yi Abish malik ZHOU Lianke ZHOU Yuanchun Department of Big Data Technology and Application Development Computer Network Information CenterChinese Academy of Sciences

A visual analytics system is proposed to reveal the lead/lag correlation when air pollution is detected. In this system, an Overview + Detail approach is utilized for analyzing the correlation of air quality under both the spatial and temporal dimensions and different spatial-temporal scales. An annular container is proposed to preserve the context spatial information while the zoom level of the map changes. Based on the annular container, several analysis techniques such as STL decomposition view and correlation algorithm are integrated.

关键词： Spatial-temporal visualization Time series visualization Correlation analysis Air pollution

Qualification of Atomic Absorption Spectrometer in Prospective View of Pharmaceutical Analysis

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American Journal of Analytical Chemistry 2014年第10期5卷 674-680页

作者： Mahmood Ahmed muhammad Abdul Qadir malik Qaiser Hussain Institute of Chemistry University of the Punjab Lahore Pakistan Pharma Services Lahore Pakistan

AAS was qualified as per pharmacopoeia requirements. Copper, manganese, mercury and cadmium hallow cathode lamps were used for qualification purposes. Design qualification and installation qualification met the criteria of user requirements. Wavelength accuracy and reproducibility, resolution and baseline stability are in compliance with user requirements. Characteristics concentration or sensitivity, detection limit and characteristics mass were performed as a part of operational qualification which is 0.062 μg/mL, 0.00354 μg/mL, 1.41 pg respectively. Results of % RSD for precision study is 0.352 and 0.487 for flame and graphite furnace mode respectively fulfilled criteria of qualification. Performance qualification results of 20 consecutive days demonstrate the predetermined specification. Analytical instrument qualification and method validation relationship is also described by assay performed on haemodialysis concentrate. Good precision (2) greater than 0.9997 for potassium, magnesium and calcium linear curves, lower detection limits for all three ingredients and robust assay data as a part of validation studies conform the qualified AAS for its intended application.

关键词： AAS Qualification Pharmaceuticals Validation