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Statistical and Geospatial Assessment of Groundwater Quality in the Megacity of Karachi

Journal of Water Resource and Protection 2019年第3期11卷 311-332页

作者： Muhammad Kamran Khan Waill Ayoub Sumayya Saied Mirza Muzammil Hussain Saiyada Shadiah Masood Azhar Siddique haider abbas khwaja Department of Chemistry University of Karachi Karachi Pakistan Wadsworth Center New York State Department of Health Albany NY USA Department of Environmental Health Sciences School of Public Health University at Albany Albany NY USA Jinnah University for Women Karachi Pakistan Unit for Ain Zubaida Rehabilitation & Groundwater Research King Abdulaziz University Jeddah Saudi Arabia

Inserting Groundwater quality variability and sources potentially contributing to aquifer recharge was evaluated in metropolitan Karachi. Selected sampling sites were characterized by large waste dumping sites, industrial zones, and the presence of open streams receiving heavy loads of industrial and domestic wastes. Levels of pH, electrical conductivity (EC), fluoride (F-), chloride (Cl-), bromide (Br-), nitrate-N (NO-3-N), sulfate (SO2-4), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), and ammonium (NH+4) were determined and compared with the WHO permissible limits. Concentrations of the measured ions were in the order of Cl- > Na+ > SO2-4 > Mg2+ > Ca2+ > NO-3-N > K+ > F- > Br-. EC values were above the WHO guidelines, representing the presence of high ionic concentration in the groundwater. The health risk index (HRI) for indicated that inhabitants of Karachi are at risk of high exposure. Ingestion of high concentrations of NO-3-N in water can cause methemoglobinemia and birth defects. Results of multivariate statistical analysis, principal component analysis (PCA), cluster analysis (CA), and geographic information system (GIS) map analysis revealed that human activities are leading to adverse effects on the existing groundwater quality in Karachi.

关键词： Groundwater Karachi Water Quality Multivariate Analysis Geospatial Health Risk Index

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Optimizing the thickness of Ta_(2)O_(5) interfacial barrier layer to limit the oxidization of Ta ohmic interface and ZrO_(2) switching layer for multilevel data storage

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Journal of Materials Science & Technology 2022年第11期106卷 98-107页

作者： Muhammad Ismail haider abbas Chandreswar Mahata Changhwan Choi Sungjun Kim Division of Electronics and Electrical Engineering Dongguk UniversitySeoul 04620Republic of Korea Division of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea

The multilevel storage capability of nonvolatile resistive random access memory(ReRAM)is greatly de-sired to accomplish high functioning memory *** this study,Ta_(2)O_(5) thin film with different thick-nesses(2,4,and 6 nm)was exploited as an appropriate interfacial barrier layer for limiting the formation of the interfacial layer between the 10 nm thick sputtering deposited resistive switching(RS)layer and Ta ohmic electrode to improve the switching cycle endurance and *** show that lower form-ing voltage,narrow distribution of SET-voltages,good dc switching cycles(10^(3)),high pulse endurance(10^(6) cycles),long retention time(10^(4) s at room temperature and 100℃),and reliable multilevel resis-tance states were obtained at an appropriate thickness of∼2 nm Ta_(2)O_(5) interfacial barrier layer instead of without Ta_(2)O_(5) and with∼4 nm,and∼6 nm Ta_(2)O_(5) barrier layer,ZrO_(2)-based memristive ***,multilevel resistance states have been scientifically investigated via modulating the compliance current(CC)and RESET-stop voltages,which displays that all of the resistance states were distinct and stayed stable without any considerable deprivation over 10^(4) s retention time and 104 pulse endurance *** I-V characteristics of RESET-stop voltage(from−1.7 to−2.3 V)of HRS are found to be a good linear fit with the Schottky *** can be seen that Schottky barrier height rises by increasing the stop-voltage during RESET-operation,resulting in enhancing the data storage memory window(on/offratio).Moreover,RESET-voltage and CC control of HRS and LRS revealed the physical origin of the RS mecha-nism,which entails the formation and rupture of conducting *** is thoroughly investigated that proper optimization of the barrier layer at the ohmic interface and the switching layer is essential in memristive *** results demonstrate that the ZrO_(2)-based memristive device with an optimized∼2 nm Ta_(2)O_(5) barrier

关键词： Resistive switching Ta_(2)O_(5)/ZrO_(2)bilayer film Barrier layer thickness Multilevel resistance states RESET-stop voltage

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Thickness-dependent monochalcogenide GeSe-based CBRAM for memory and artificial electronic synapses

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Nano Research 2022年第3期15卷 2263-2277页

作者： Asif Ali haider abbas Muhammad Hussain Syed Hassan abbas Jaffery Sajjad Hussain Changhwan Choi Jongwan Jung HMC(Hybrid Materials Center)and Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 143–747Republic of Korea Division of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea

Investigating the promising chalcogenide materials for the development of memory and advanced neuromorphic computing applications is a critical step in realizing electronic memory and synaptic devices that can efficiently emulate biological synaptic ***,the assessment of monochalcogenide materials for the fabrication of highly scalable memory and electronic synaptic devices that can accurately mimic synaptic functions remain *** the present study,we investigated the thickness-dependent resistive switching(RS)behavior of conductive bridge random access memory(CBRAM)based on a monochalcogenide GeSe switching medium for its possible application in high-performance memory and electronic *** thin films of different thicknesses(6,13,24,35,47,and 56 nm)were deposited via sputtering to fabricate CBRAM devices with a stacking sequence of Ag/GeSe/Pt/Ti/SiO_(2).The devices exhibited compliance current(CC)-free and electroforming-free RS with highly stable endurance and retention characteristics with no major *** devices with a thickness of 6 nm had a low-resistance state(LRS),which required an initial reset to ensure reliable switching *** devices with a thickness of 47 nm and above exhibited the co-existence of unipolar resistive switching(U-RS)and bipolar resistive switching(B-RS)with the CC-controlled transition between the two switching *** resistance states in the 24-nm device between a high-resistance state(HRS)and an LRS were achieved by controlling the set-CC(from 5 mA to CC-free)and the reset stop voltage(from–0.5 to–1.0 V)during the set and reset processes,*** analog RS behavior of the device was further investigated with appropriate pulse measurements to emulate vital synaptic functions,including long-term potentiation(LTP),long-term depression(LTD),spike-rate-dependent plasticity(SRDP),spike-timing-dependent plasticity(STDP),paired-pulse facilitation(PPF),paired-pulse depression(PPD)and

关键词： conductive bridge random access memory(CBRAM) resistive memory switching monochalcogenide material bipolar and unipolar resistive switching multilevel resistive switching electronic synapses

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AI-Driven Energy Optimization in UAV-Assisted Routing for Enhanced Wireless Sensor Networks Performance

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Computers, Materials & Continua 2024年第9期80卷 4085-4110页

作者： Syed Kamran haider abbas Ahmed Noman Mujeeb Khan Ali Nauman Sung Won Kim College of Internet of Things(IoT)Engineering Hohai UniversityChangzhou213001China Department of Electrical and Electronics Engineering Beaconhouse International CollegeIslamabad44000Pakistan School of Computer Science and Engineering Yeungnam UniversityGyeongsan38428Republic of Korea

In recent advancements within wireless sensor networks(WSN),the deployment of unmanned aerial vehicles(UAVs)has emerged as a groundbreaking strategy for enhancing routing efficiency and overall network *** research introduces a sophisticated framework,driven by computational intelligence,that merges clustering techniques with UAV mobility to refine routing strategies in *** proposed approach divides the sensor field into distinct sectors and implements a novel weighting system for the selection of cluster heads(CHs).This system is primarily aimed at reducing energy consumption through meticulously planned routing and path *** a greedy algorithm for inter-cluster dialogue,our framework orchestrates CHs into an efficient communication *** comparative analysis,the proposed model demonstrates a marked improvement over traditional methods such as the cluster chain mobile agent routing(CCMAR)and the energy-efficient cluster-based dynamic algorithms(ECCRA).Specifically,it showcases an impressive 15%increase in energy conservation and a 20%reduction in data transmission time,highlighting its advanced ***,this paper investigates the impact of various network parameters on the efficiency and robustness of the WSN,emphasizing the vital role of sophisticated computational strategies in optimizing network operations.

关键词： UAV trajectory clustering next-generation wireless sensor network(NGWSN) energy efficiency mobile sink

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Inexpensive synthesis of a high-performance Fe3O4-SiO2-TiO2 photocatalyst： Magnetic recovery and reuse

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Frontiers of Chemical Science and Engineering 2016年第3期10卷 405-416页

作者： Nadir abbas Godlisten N. Shao Syed M. Imran Muhammad S. haider Hee Taik Kim Department of Chemical Engineering Hanyang University Ansan-si Gyeonggi-do 426-791 Republic of Korea Department of Civil and Environmental Engineering Hanyang University Ansan-si Gyeonggi-do 426-791 Republic of Korea Department of Chemical Engineering University of Gujrat HH Campus Punjab Pakistan

A sol-gel technique has been developed for the synthesis of a magnetite-silica-titania （Fe3O4-SiO2-TiO2） tertiary nanocomposite with improved photocatalytic properties based on the use of inexpensive titania and silica precursors. The exceptional photocatalytic activity of the resulting materials was demonstrated by using them to photocatalyze the degradation of methylene blue solution. The best formulation achieved 98% methylene blue degradation. An interesting feature of the present work was the ability to magnetically separate and reuse the catalyst. The efficiency of the catalyst remained high during two reuses. The synthesized nanomaterials were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron micro- scopy （TEM）, Fourier transform infrared （FTIR） spectro- scopy, ultra-violet-visible spectroscopy, diffuse reflectance spectroscopy, and thermogravimetric analysis. XRD ana- lysis revealed the formation of multicrystalline systems of cubic magnetite and anatase titania crystals. SEM and TEM characterization revealed well-developed and homo- geneously dispersed particles of size less than 15 nm. FTIR spectra confirmed the chemical interaction of titania and silica. It was further noticed that the optical properties of the prepared materials were dependent on the relative contents of their constituent metal oxides.

关键词： sol-gel photocatalysis magnetic recovery,TiO2 Fe3O4 SiO2

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Towards engineering in memristors for emerging memory and neuromorphic computing: A review

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Journal of Semiconductors 2021年第1期42卷 33-61页

作者： Andrey S.Sokolov haider abbas Yawar abbas Changhwan Choi Division of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea Department of Physics Khalifa UniversityAbu Dhabi 127788United Arab Emirates

Resistive random-access memory(RRAM),also known as memristors,having a very simple device structure with two terminals,fulfill almost all of the fundamental requirements of volatile memory,nonvolatile memory,and neuromorphic *** memory and neuromorphic behaviors are currently being explored in relation to a range of materials,such as biological materials,perovskites,2D materials,and transition metal *** this review,we discuss the different electrical behaviors exhibited by RRAM devices based on these materials by briefly explaining their corresponding switching *** then discuss emergent memory technologies using memristors,together with its potential neuromorphic applications,by elucidating the different material engineering techniques used during device fabrication to improve the memory and neuromorphic performance of devices,in areas such as ION/IOFF ratio,endurance,spike time-dependent plasticity(STDP),and paired-pulse facilitation(PPF),among *** emulation of essential biological synaptic functions realized in various switching materials,including inorganic metal oxides and new organic materials,as well as diverse device structures such as single-layer and multilayer hetero-structured devices,and crossbar arrays,is analyzed in ***,we discuss current challenges and future prospects for the development of inorganic and new materials-based memristors.

关键词： RRAM memristor emerging memories neuromorphic computing electronic synapse resistive switching memristor engineering

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Memristive SRAM cell of seven transistors and one memristor

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Journal of Semiconductors 2016年第10期37卷 56-59页

作者： Patrick W.C.Ho haider abbas F.Almurib T.Nandha Kumar Department of Electrical & Electronic Engineering University of Nottingham Malaysia Campus

In this work, a novel memristive SRAM cell is designed using seven transistors and one memristor（7T1M）. In this 7T1 M SRAM cell, the non-volatile functionality is achieved by adding a single memristor and a transistor to the design of a volatile SRAM cell. The designing of the 7T1 M SRAM cell also introduces VCTRL which allows bidirectional current flowing through the memristor, instead of relying on complementary input sources which would require more design components. In this article, memristive SRAM cells available from the literature are simulated using the same simulation environment for a fair comparison. Simulations show that the7T1 M SRAM cell has the least power consumption against other memristive SRAM cells in the literature. The7T1 M SRAM cell operates with an average switching speed of 176.21 ns and an average power consumption of2.9665μW. The 7T1 M SRAM cell has an energy-delay-area product value of 1.61, which is the lowest among the memristive SRAM cells available in the literature.

关键词： memristor memristive SRAM cell EDAP non-volatile memory cell

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Appraisal of Biofertilizers in Rice: To Supplement Inorganic Chemical Fertilizer

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Rice science 2018年第6期25卷 357-366页

作者： haider Iqbal KHAN C 36 Gateway Building The University of Nottingham Sutton Bonington Campus

A field experiment was carried out to evaluate the feasibility of inoculating rice seedlings with biofertilizers(Azospirillum and Trichoderma) in order to reduce the use of chemical inorganic nitrogen(N)fertilizer on rice variety BU Dhan 1. The plant performances were better when 25% less inorganic N was applied with Trichoderma and combined application of Trichoderma and Azospirillum. Plants contained the highest chlorophyll concentrations when they were treated with 75% N + Trichoderma. Considering the yield attributes, 75% N + Trichoderma and 75% N + Trichoderma + Azospirillum performed similar to the control. The grain yield of rice was similar to the recommended dose even with 25% less N application. Application of Trichoderma resulted higher yield, followed by combined application with Azospirillum. Results revealed the greater scope of applying biofertilizer(Trichoderma) to supplement chemical N fertilizer with optimum yield of rice.

关键词： Azospirillum biofertilizer inorganic chemical fertilizer rice Trichoderma nitrogen

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Solitons and quasi-Grammians of the generalized lattice Heisenberg magnet model

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Communications in Theoretical Physics 2023年第8期75卷 42-53页

作者： Zeeshan Amjad Bushra haider Department of Physics University of the PunjabQuaid-e-Azam CampusLahore-54590Pakistan

In this paper,we study the discrete Darboux and standard binary Darboux transformation for the generalized lattice Heisenberg magnet *** calculate the quasi-Grammian solutions by the iteration of standard binary Darboux ***,we derive the explicit matrix solutions for the binary Darboux matrix and then reduce them to the elementary Darboux matrix and plot the dynamics of solutions.

关键词： quasi-Grammian discrete integrable systems binary Darboux transformation

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Multifunctional transition and temperature-responsive contact lenses

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Light(Science & Applications) 2023年第12期12卷 2624-2635页

作者： Ahmed E.Salih haider Butt Department of Mechanical Engineering Khalifa UniversityAbu DhabiUAE

Smart contact lenses have recently gained traction due to their functionalization as noninvasive diagnostic and therapeutic wearables that can address several ocular ***,multifunctional contact lenses exhibiting UV-transition and temperature-responsive capabilities were developed utilizing chromogenic materials that were integrated simultaneously into poly(2-hydroxyethyl methacrylate)(pHEMA)contact *** functionalities of the contact lenses were optically evaluated in both their activated and non-activated *** contact lenses offered excellent UV and blue light blocking capabilities(~45%)at their inactive *** activated via UV exposure,the transparent lenses darkened instantaneously and absorbed portions of the visible light *** absorption intensity and transient discoloration of the transition lenses relied primarily on the utilized photochromic ***,the temperature-responsive contact lenses exhibited distinct colorimetric variations in response to temperature changes within the physiological range(33-38℃).The maximum sensitivity of the thermochromic lens was 8%transmitted light per Celsius degree *** and morphological analysis indicated the adequacy of the contact ***,the multifunctional contact lenses can be deployed as smart wearables to manage ophthalmic deficiencies that are deterred by UV radiations and variations in ocular surface temperature.

关键词： temperature spectrum material

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