Muhammad Zahir Iqbal  Salma Siddique  Muhammad Farooq Khan  Atteq ur Rehman  Adil Rehman  Jonghwa Eom 《Advanced Engineering Materials》2018,20(7)

Combining with layered thin crystalline films, graphene has expanded its application scope beyond the regime where a gapless semimetal cannot serve. Here, we report the modulation of tunneling characteristics in graphene/hexagonal boron nitride (hBN) vertical heterostructure at different interlayer hBN thickness. These results signify an upshift in threshold voltages with hBN layer thickness. Furthermore, the gate‐dependent tunneling characteristics of the device has been demonstrated. The back‐gate voltages are used to adjust the fermi level of bottom graphene layer, which in turns tune the threshold voltages and tunneling current through ultrathin hBN layer. Our findings offer an effective tool to modulate the tunneling characteristics of vertical transistors for their potential applications in high frequency logic and tunnel devices.

  相似文献   

    

Muhammad Ejaz  Naveed Iqbal Raja  Zia&#x;Ur&#x;Rehman Mashwani  Muhammad Sheeraz Ahmad  Mubashir Hussain  Muhammad Iqbal 《IET nanobiotechnology / IET》2018,12(7):927

This study was organised to check the effect of silver nanoparticles and silver nitrate on rice growth against biotic stress. Silver nanoparticles were synthesised by using plant extract as reducing agent, followed by characterisation through UV Vis spectroscopy, XRD, EDS and SEM. Aspergillus application significantly reduced rice plant fresh mass (0.9%), dry mass (0.21%), root length (2.3%), shoot length (5.2%) and root number (1%) in comparison to control. Similarly, leaf area, leaf fresh mass, dry mass and leaf number were also reduced by 23.1, 0.02, 0.11 and 0.9%, respectively. AgNPs and AgNO₃ treatments increased the root length (16.2 & 12.8%), shoot length (21 & 20%), root number (8.1 & 6.8%), plant fresh weight (6.4 & 5%) and plant dry weight (4.6 & 3.5%) in 75mg/l treatment of AgNPs and AgNO₃ respectively. Similarly, AgNPs and AgNO₃ treatment (75 mg/l concentrations) reflected remarkable increase in leaf area (58.8 & 57.2 %), leaf number (4.3 & 3.7 %), leaf fresh weight (1.7 & 1.4 %) and leaf dry weight (0.9 & 0.8 %). Overall AgNPs showed more significant results as compared to AgNO₃. The quantity of aflatoxins ranged from 3.1 to 7.7 μg/kg against tolerable limit (4 µg/kg). Overall AgNPs and AgNO₃ treatments showed significant results and it could be considered as a strategy for aflatoxin management in rice plants.Inspec keywords: crops, scanning electron microscopy, nanoparticles, X‐ray diffraction, toxicology, agricultural pollution, agricultural safety, silver compounds, ultraviolet spectroscopyOther keywords: biotic stress, silver nanoparticles, AgNPs, silver nitrate, super kernel rice, Kala Shah Kaku research centre, UV–Vis spectroscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, rice plant fresh mass, root number, leaf area, leaf fresh mass, dry mass, leaf number, root length, leaf fresh weight, leaf dry weight, examined rice plants, rice growth, aflatoxins, scanning electron microscopy, Aspergillus application, AgNO₃   相似文献   

    

Mubashir Hussain  Naveed Iqbal Raja  Zia&#x;Ur&#x;Rehman Mashwani  Farah Naz  Muhammad Iqbal  Sumaira Aslam 《IET nanobiotechnology / IET》2018,12(4):514

The synthesis of nanoparticles by utilising plant extract has revolutionised the field of nanotechnology. In the present study, AgNPs were synthesised by utilising the leaves of Moringa oleifera as reducing and stabilising agent. UV‐visible spectroscopy showed characteristic surface plasmon band in the range of 413–420 nm. Scanning electron microscopy (SEM) elucidated rectangular segments fused together. X‐ray diffraction (XRD) analysis confirmed the crystalline nature of AgNPs and presence of metallic silver ions was confirmed by energy dispersive X‐ray (EDX). The different concentrations (10, 20, 30 and 40 ppm) of AgNPs were exogenously applied on Citrus reticulata to record the disease incidence at different day intervals. The disease intensity was progressively increased in all the applied treatments with the passage of time. The 30 ppm concentration of AgNPs was found to be most suitable concentration for creating the resistance against brown spot disease. Moreover, the effects of AgNPs were also assessed for biochemical profiling in C. reticulata. The enhanced production of endogenous enzymes and non‐enzymatic components was observed in response to 30 ppm concentration of AgNPs. The present work highlighted that green synthesised AgNPs can be as used as biological control of citrus diseases and the enhanced production of secondary metabolites antioxidants.Inspec keywords: nanoparticles, silver, nanofabrication, nanomedicine, biomedical materials, biochemistry, enzymes, molecular biophysics, plant diseases, ultraviolet spectra, visible spectra, scanning electron microscopy, surface plasmon resonance, X‐ray diffraction, X‐ray chemical analysisOther keywords: green synthesis, silver nanoparticles, antimicrobial efficacy, biochemical profiling, Citrus reticulata, plant extract, nanotechnology, medical sciences, environment friendly AgNPs, biomedical fields, leaves, Moringa oleifera, reducing agent, stabilising agent, ultraviolet‐visible spectroscopy, characteristic surface plasmon band, scanning electron microscopy, rectangular shape, X‐ray diffraction analysis, crystalline nature, energy dispersive X‐ray spectroscopy, disease incidence, disease intensity, applied treatments, Alternaria brown spot disease, total phenolic content, dry weight, total flavonoid content, T4 treatment, superoxide dismutase activity, fresh weight, maximum peroxidase production, DPPH radical scavenging assay, biological control, citrus disease, secondary metabolites antioxidants  相似文献   

         下载免费PDF全文

Amjid Iqbal  Arshad Mahmood  Q.Raza  A.Shah  Rashad Rashid  Zahid Ali  A.Malik  U.Aziz 《半导体学报》2018,39(8):6-9

This paper demonstrates the structural,vibrational and photoluminescence characteristics of (ZnO)1-x(V2O5)x (x =0,3,6 and 9 mol％) composites semiconductor synthesized by using the solid state reaction method.X-ray diffraction (XRD) studies show that (ZnO)1-x(V2O5)x composites have the poly crystalline wurtzite structure of hexagonal ZnO.It is found from the XRD results that the lattice constants and the crystallite size increase while the dislocation density decreases with increase in doping concentration.The existence ofE1 (TO) and E2 (high) Raman modes show that the ZnO still preserve wurtzite structure after doping vanadium oxide,which is in agreement with XRD results.Room temperature photoluminescence (PL) exhibit near band edge and broad deep level emission while indicating the suppression of deep level emission with the incorporation of V2O5 up to a certain concentration (x ＜ 9).Moreover,the optical band gap increase with doping,which is accompanied by the blue shift of the NBE emission.  相似文献   

    

Omer Waqar  Muhammad Asim Ali  Mahrukh Liaqat  Ayesha Iqbal 《Transactions on Emerging Telecommunications Technologies》2021,32(1)

In this article, simultaneous wireless information and power transfer (SWIPT) has been studied for point‐to‐point decode‐and‐forward (DF) based multiple‐input‐multiple‐output (MIMO) relay network with an energy‐constrained relay. This relay is capable of harvesting energy from the wireless signals received from the source terminal. In particular, three different SWIPT schemes, that is, time switching, power splitting, and antenna switching are considered for EH at relay. New closed‐form approximations for the sum ergodic capacity of a DF MIMO relay network have been derived with spatial multiplexing at source, zero‐forcing receivers at relay and destination. Based on the sum capacity approximations, optimal splitting coefficients for aforementioned SWIPT schemes that maximize the sum capacity are presented. Moreover, the impact of system parameters on these optimal coefficients has been studied. In addition to this, first optimization problems for the number of antennas at relay have been formulated and then these problems are transformed into concave form by relaxing constraints to be defined over positive real numbers instead of taking only discrete values. New closed‐form solutions for the optimum number of antennas at relay have been derived. Furthermore, new closed‐form approximations for the ergodic capacities in the presence of an external co‐channel interference are also presented. Numerical results show that approximations for the sum capacity match well with the exact ones obtained through Monte‐Carlo simulations, particularly when the channel hardening effect kicks in, that is, for large degrees of freedom. Finally, the solutions for the optimization problems have also been validated by the numerical examples.  相似文献   

    

Hamna F. Iqbal  Matthew Waldrip  Hu Chen  Iain McCulloch  Oana D. Jurchescu 《Advanced Electronic Materials》2021,7(9):2100393

Conjugated polymers have gained momentum as serious contenders for next-generation flexible electronics, but their susceptibility to water represents a major problem. Atmospheric water is ubiquitous and its inadvertent diffusion into polymeric devices generates charge carrier traps, reducing their performance and stability. A good understanding of the physical processes associated with the presence of water is therefore necessary in order to be able to suppress the related trapping events and enable stable, high-performance devices. Here, evidence is shown that water introduces traps in the bandgap of organic semiconductors and the impact of these traps on the electrical properties of polymer organic field-effect transistors (OFETs) based on indacenodithiophene-co-benzothiadiazole (IDT-BT) is investigated. Monitoring device parameters and the trap density of states (t-DOS) during moisture extrication reveals the existence of two types of water-related traps: shallow traps originating from water inhabiting the voids of the polymer film and deeper traps arising from chemisorbed water present at the dielectric/polymer interface. A trap passivation method based on flame-annealing is introduced to eliminate the interfacial traps. As a result, stable OFETs, with threshold voltage shifts less than ΔV_th = −0.3 V and constant mobilities (<10% variation) after three months of storage, are fabricated.  相似文献   

    

Mehwish Iqbal  Muhammad Mohsin Riaz  Abdul Ghafoor  Attiq Ahmad 《International journal of imaging systems and technology》2021,31(1):160-167

Segmentation of the human eye retinal image is an essential step for proper examination and diagnosis by the ophthalmologists or eye care specialists. A technique for vessel segmentation of retinal images is proposed. Retinal images are mostly low‐light images, which are first processed for enhancement of light as well as for detail amplification. Illumination of low‐light images is enhanced, and details are amplified using content‐adaptive filters. For extraction of vessels from retinal images, after low‐light and detail enhancement, the B‐cosfire filter is modified by including extraction of details and small elements, which may otherwise be ignored. A modified B‐cosfire filter is used to extract vessels while minimizing false edges and halo artifacts. The morphological opening is performed to crop vessels that are falsely segmented. The technique is contrasted with other existing methods in terms of accuracy using publicly available datasets. The proposed technique is tested on STARE, CHASE‐DB1, and DRIVE databases. The outcome of the proposed procedure has better accuracy, preserved edges, minimum noise, and artifacts than the state‐of‐the‐art techniques.  相似文献   

    

Aqeel AHMED  Muhammad WASIF  Anis FATIMA  Liming WANG  Syed Amir IQBAL 《Frontiers of Mechanical Engineering》2021,16(2):298-314

Frontiers of Mechanical Engineering - The machining industry must maximize the machine tool utilization for its efficient and effective usage. Determining a feasible workpiece location is one of...  相似文献   

    

Muhammad S. Iqbal  Irfan Mustafa  Iram Riaz  Abuzar Ghaffari  Waqar A. Khan 《亚洲传热研究》2021,50(1):619-637

The transfer of heat is an important phenomenon in the several areas due to its numerous applications in industries. Several fluids like water, ethylene glycol and oil, and so on have very‐low thermal conductivities due to which the transfer of heat in these fluids become very low. To enhance heat transfer rate, carbon nanotubes (CNTs) including single‐walled CNTs and multi‐walled CNTs are suspended into base fluids, this mixture is known as nanofluid. The aim of this study is to examine the heat transfer rate of nanofluid in the presence of CNTs over a stretchable rotating disk. The mathematical model, developed by Tiwari and Das, is used and solved numerically by using the shooting method. The impacts of governing constraints on the dimensionless velocities, temperature, skin friction, and Nusselt number are investigated. It is noted that heat transfer rate increases by enhancing the concentration of CNTs into base fluids. The numerical results show that the solid volume fraction of the CNTs augment heat transfer rate more in ethylene glycol as compared with water.  相似文献   

    

Surajo Muhammad  Jun Jiat Tiang  Sew Kin Wong  Amjad Iqbal  Amor Smida  Mohamed Karim Azizi 《计算机、材料和连续体（英文）》2021,68(1):167-184

This paper presents a compact multi-band rectifier with an improved impedance matching bandwidth. It uses a combination of п–matching network (MN) at Port-1, with a parallel connection of three cell branch MN at Port-2. The proposed impedance matching network (IMN) is adopted to reduce circuit complexity, to improve circuit performance, and power conversion efficiency (PCE) of the rectifier at low input power. The fabricated rectifier prototype operates at 0.92, 1.82, 2.1, 2.46 and 2.65 GHz covering GSM/900, GSM/1800, UMTS2100, and Wi-Fi/2.45–LTE2600. The size of the compact rectifier on the PCB board is 0.13λ_g × 0.1λ_g. The fabricated rectifier achieved an RF-to DC (radio frequency direct current) PCE of 31.8%, 24%, 22.7%, and 15%, and 14.1% for −20 dBm at the five respective measured operating frequencies. The circuit attains a peak RF-to-DC PCE of 82.3% for an input power of 3 dBm at 0.92 GHz. The proposed rectifier realizes an ambient output dc voltage of 454 mV for multi-tone input signals from the two ports. The rectifier drives a bq25504-674 power management module (PMM) to achieve 1.21 V from the two-port connection. The rectifier has the ability to exploit both frequency domain through the multi-band operation with good impedance bandwidth and a spatial domain using dual-port configuration. Hence, it is a potential candidate for various applications in radio frequency energy harvesting (RFEH) system.  相似文献