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Nitrogen-doped graphene quantum dots: Optical properties modification and photovoltaic applications

Nano Research 2019年第5期12卷 1041-1047页

作者： md tanvir hasan Roberto Gonzalez-Rodriguez Conor Ryan Kristof Pota Kayla Green Jeffery L.Coffer Anton V.Naumov Department of Physics and Astronomy Texas Christian UniversityTCU Box 298840Fort WorthTexas 76129USA Department cf Chemistry and Eiochemistry Texas Christian UniversityTCU Box 298860Fort WorthTexas 76129USA

In this work,we utilize a bottom-up approach to synthesize nitrogen self-doped graphene quantum dots (NGQDs) from a single glucosamine precursor via an eco-friendly microwave-assisted hydrothermal *** and optical properties of as-produced NGQDs are further modified using controlled ozone ***-treated NGQDs (Oz-NGQDs) are reduced in size to 5.5 nm with clear changes in the lattice structure and/D//G Raman ratios due to the introduction/alteration of oxygen-containing functional groups detected by Fourier-transform infrared (FTIR) spectrometer and further verified by energy dispersive X-ray spectroscopy (EDX) showing increased atomic/weight percentage of oxygen *** with structural modifications,GQDs experience decrease in ultraviolet-visible (UV-vis) absorption coupled with progressive enhancement of visible (up to 16 min treatment) and near-infrared (NIR)(up to 45 min treatment) *** allows fine-tuning optical properties of NGQDs for solar cell applications yielding controlled emission increase,while controlled emission quenching was achieved by either blue laser or thermal *** Oz-NGQDs were further used to form a photoactive layer of solar calls with a maximum efficiency of 2.64% providing a 6-fold enhancement over untreated NGQD devices and a 3-fold increase in fill factor/current *** study suggests simple routes to alter and optimize optical properties of scalably produced NGQDs to boost the photovoltaic performance of solar cells.

关键词： nitrogen-doped graphene quantum dots ozone treatment optical properties photovoltaics solar cells

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Numerical Analysis and Design of Photonic Crystal Fiber Based Surface Plasmon Resonance Biosensor

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Journal of Sensor Technology 2019年第2期9卷 27-34页

作者： md. Biplob Hossain md. Sanwar Hossain md. Moznuzzaman md. Amzad Hossain md. Tariquzzaman md. tanvir hasan md. Masud Rana Department of Electrical and Electronic Engineering Jashore University of Science and Technology Jashore Bangladesh Department of Electrical and Electronic Engineering Jashore University of Science and Technology Jashore BangladeshMd. Amzad Department of Electrical and Electronic Engineering Bangladesh University of Business and Technology Dhaka Bangladesh Department of Electrical and Electronic Engineering Rajshahi University of Engineering & Technology Rajshahi Bangladesh.

In this paper, a high sensitive photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor is numerically studied. In this structure, as a plasmonic material, gold (Au) is used because of its chemical activeness. And a layer of sensing medium is used outside of the fiber to make the structure effective. Any unknown biomolecular analyte can be detected by placing or flowing it on the metal surface. Guiding properties and results are investigated using Finite element method (FEM). Results show that maximum sensitivity is 4000 nm/RIU, as well as resolution, is 2.5 × 10−5 RIU of the proposed sensor.

关键词： Biosensor PCF SPR SPP Mode Sensitivity

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Study of the Bulk Magnetic and Electrical Properties of MgFe<sub>2</sub>O<sub>4</sub>Synthesized by Chemical Method

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Materials Sciences and Applications 2011年第11期2卷 1564-1571页

作者： Sheikh Manjura Hoque M. Abdul Hakim Al Mamun Shireen Akhter md. tanvir hasan Deba Prasad Paul Kamanio Chattopadhayay 不详

Nanocrystalline Magnesium ferrite has been prepared by chemical co-precipitation technique. Structural characterization has been performed by X-ray diffraction. Formation of ferrites has also been studied by using FTIR. Frequency dependence of real and imaginary part of initial permeability has been presented for the samples sintered at different temperatures. Real part of initial permeability, increases with the increase of grain growth. The loss component repre- sented by imaginary part of initial permeability decreases with frequency up to the measured frequency of this study of 13 MHz. Curie temperatures have been determined from the temperature dependence of permeability. Curie temperatures for the samples of this composition do not vary significantly with the variation of sintering temperatures. B-H loop measurements have been carried out by B-H loop tracer. Transport property measurements haven been carried out by electrometer and impedance analyzer.

关键词： MgFe2O4 Nanograins Complex Initial Permeability B-H Curves Transport Properties

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Ru/NiMnB spherical cluster pillar for highly proficient green hydrogen electrocatalyst at high current density

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Journal of Energy Chemistry 2025年第1期100卷 397-408页

作者： md Ahasan Habib Shusen Lin Mehedi hasan Joni Sumiya Akter Dristy Rutuja Mandavkar Jae-Hun Jeong Jihoon Lee Department of Electronic Engineering College of Electronics and InformationKwangwoon UniversityNowon-guSeoul 01897Republic of Korea

Advanced OER/HER electrocatalytic alternatives are crucial for the wide adaptation of green hydrogen ***,Ru/NiMnB spherical cluster pillar(SCP),denoted as Ru/NiMnB,is synthesized using a combination of electro-deposition and hydrothermal *** investigation of Ru doping in the NiMnB matrix revealed significant improvements in electrocatalytic *** Ru/NiMnB SCPs demonstrate superior OER/HER activity with low overpotentials of 150 and 103 mV at 50mA/cm^(2)in 1 M KOH,making them highly competitive with state-of-the-art ***,the Ru/NiMnB SCPs exhibit a low 2-E cell voltage of 2.80 V at ultra-high current density of 2,000 m A/cm^(2)in 1 M KOH,outperforming the standard benchmark electrodes of RuO_(2)||Pt/C,thereby positioning Ru/NiMnB as one of the best bifunctional *** SCPs exhibit exceptional high-current characteristics,stability and corrosion resistance,as evidenced by continuous operation at 1,000 mA/cm^(2)high-current density for over 150 h in 6 M KOH at elevated temperatures under harsh industrial *** a small amount of Ru incorporation significantly enhances the electrocatalytic performances of NiMnB,attributed to increased active sites and improved intrinsic properties such as conductivity,adsorption/desorption capability and reaction ***,Ru/NiMnB SCPs present a promising bi-functional electrode concept for efficient green H_(2)production.

关键词： Advanced electrocatalyst High current Corrosion resistance Industrial requirement

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High Efficient Design of a Reconfigurable Step-Up DC-DC Converter with Fault-Tolerant Capability

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CSEE Journal of Power and Energy Systems 2025年第1期11卷 296-305页

作者： Farid Mohammadi hasan Rastegar Mohammad Pichan Amirkabir University of Technology TehranIran Arak University of Technology ArakIran

Power electronic converters often malfunction because semiconductor power switches are prone to *** paper proposes a DC-DC converter that is capable of safe operation under switch *** proposed fault-tolerant(FT)technique is based on a reconfiguration strategy without requiring additional ***,power flow is considered in the configuration design,resulting in a reduced amount of additional power to be processed,thus producing a more efficient converter *** addition,voltage stress across the active elements is low and always equals half of the output *** switch-fault modes,the presented control system minimizes the transient impact of the faults to preserve normal operation of the *** various switch faults,the new configuration of the proposed converter supports operation with new ***,a fuse-MOSFET pair is embedded to protect the FT DC-DC converter from excessive current that might damage circuit *** proposed converter in a continuous current mode(CCM)is evaluated,and its characteristics are discussed in *** proposed converter has been implemented,and necessary evaluations have been conducted to verify the theoretical study and feasibility of the control system.

关键词： FT DC-DC converter fuse-MOSFET pair power electronic converters power flow reconfiguration strategy

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Differences in Seedling and Sapling Densities and Species Composition between Canopy Gaps and Forest Understories in a Subtropical Forest in Bangladesh

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Journal of Resources and Ecology 2025年第1期16卷 105-114页

作者： Tarit Kumar BAUL Anwarul Islam CHOWDHURY md Jamal UDDIN Mohammad Kamrul hasan Tapan Kumar NATH Lars Holger SCHMIDT Institute of Forestry and Environmental Sciences University of ChittagongChittagong 4331Bangladesh Faculty of Science Forestry and TechnologySchool of Forest SciencesUniversity of Eastern FinlandJoensuu 80101Finland Department of Agricultural and Forest Sciences and Engineering University of LleidaLleida 25001Spain Natural Resources Institute Finland(Luke) Helsinki 00790Finland Faculty of Science and Engineering University of Nottingham MalaysiaJalan Broga 43500Malaysia Department of Geoscience and Natural Resource Management University of CopenhagenFrederiksberg C 1958Denmark

Canopy openings have a vital role in forest structure,regeneration,and plant *** this study,we investigated and compared the species composition and densities of seedlings and saplings between canopy gaps(openings)and forest understories(in dense canopies)in a sub-tropical forest of *** objectively identified 42 canopy openings between transect lines and 42 main plots in dense canopies,sampled for regeneration and young tree *** the regeneration study,we placed 2 m×2 m four subplots in each canopy opening and the main plot of dense canopy,thus making a total of 336 *** species diversity of seedlings,saplings,and trees were significantly(P≤0.05)higher in the dense canopy than in the canopy ***,most dominant and frequent regenerating species such as Diospyros pilosula,Garcinia cowa,Brownlowia elata,and Lithocarpus polystachya were common in both dense canopy and openings,the canopy openings had the highest Importance Value Index,suggesting the significance of gap dynamics in the dominance of native floral *** dense canopy played an important role in forest compositions because 12 regenerating species,including Stereospermum suaveolens and Diospyros montana,were not found in the canopy openings,implying that rain forests must maintain a high canopy cover for regeneration.

关键词： canopy opening disturbance forest dynamics native flora seedling sapling

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Steady-State Solution ofMHD Flow with Induced Magnetic Field

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Fluid Dynamics & Materials Processing 2025年第2期21卷 233-252页

作者： Saykat Poddar JuiSaha Badhan Neogi Mohammad Sanjeed hasan Muhammad Minarul Islam Giulio Lorenzini md.Mahmud Alam Department of Mathematics Faculty of ScienceBangabandhu Sheikh Mujibur Rahman Science and Technology UniversityGopalganj8100Bangladesh Department of Industrial Systems and Technologies Engineering University of ParmaParma43124Italy Mathematics Discipline ScienceEngineering and Technology SchoolKhulna UniversityKhulna9208Bangladesh

This study presents a numerical analysis of the steady-state solution for transient magnetohydrodynamic(MHD)dissipative and radiative fluid flow,incorporating an inducedmagnetic field(IMF)and considering a relatively high concentration of foreign mass(accounting for Soret and Dufour effects)over a vertically oriented semi-infinite *** governing equations were normalized using boundary layer(BL)*** resulting nonlinear system of partial differential equations(PDEs)was discretized and solved using an efficient explicit finite difference method(FDM).Numerical simulations were conducted using MATLAB R2015a,and the developed numerical code was verified through comparison with another code written in FORTRAN *** ensure the reliability of the results,both mesh refinement and steady-state time validation tests were ***,a comparison with existing published studies was made to confirm the accuracy of the *** dimensionless equations revealed the impacts of several key *** IMF initially intensifies near the plate before gradually diminishing as the magnetic parameter *** the range 0≤y≤1.8(where y is the horizontal direction),the IMF decreases with a rise in the magnetic Prandtl number;however,for 1.8≤y≤7(approximately),the magnetic field begins to *** this,the profile of the magnetic field becomes somewhat irregular through the remaining part of the BL.

关键词： MHD stability analysis finite difference method(FDM)

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Photobiomodulation in ocular therapy:current status and future perspectives

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International Journal of Ophthalmology(English edition) 2025年第2期18卷 351-357页

作者： hasan Chichan Iftkhar Hamzah Aldujaly Konstantinos Michalakis Levent Kanal Al-Mustaqbal University College of ScienceHillah 51001BabylonIraq Lumedico Eye Clinics Düsseldorf Germany Münsterstraße 96Düsseldorf 40476Germany

Photobiomodulation has been known to have potential medicinal effects for *** involves the use of specific wavelengths to target specific regions in the *** health conditions have been reported to be treated with exposure to light such as cardiovascular conditions,inflammatory diseases,infectious diseases,and most importantly ocular *** review specifically targets the treatment of retinal diseases including age-related macular degeneration,diabetic macular edema,myopia and acute retinal light injury with *** light is used in this therapy since this wavelength has lower frequency and hence minimal chance of causing any *** light has the potential to penetrate cellular structures such as mitochondria and facilitate cellular *** ocular diseases,the target wavelength ranges between 630 to 800 *** most of the cases the primary target for red light is the cytochrome C oxidase enzyme in mitochondria,which alters the gene expression and promotes cellular energy *** evidence shows improvement of visual activity and reduction in thickness of retina post *** prospects of photobiomodulation involve target-specific treatment,combinational therapy to treat complex retinal diseases including gene therapy,and longitudinal studies to predict long-term efficacy and the chance of any recurrence in the *** the future of photobiomodulation holds significant potential in medicine especially in ocular diseases characterized by progress in research,technology,and clinical trials.

关键词： photobiomodulation retina near-infrared ocular diseases light therapy

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Classifying Cognitive Decline in Older Drivers from Behavior on Adverse Roads Detected Using Computer Vision

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Journal of Transportation Technologies 2025年第1期15卷 135-154页

作者： md Zahid hasan Guillermo Basulto-Elias Shauna Hallmark Jun Ha Chang Anuj Sharma Jeffrey D. Dawson Soumik Sarkar Matthew Rizzo Institute for Transportation Iowa State University Ames Iowa USA Department of Neurological Sciences University of Nebraska Medical Center Omaha Nebraska USA

As drivers age, roadway conditions may become more challenging, particularly when normal aging is coupled with cognitive decline. Driving during lower visibility conditions, such as inclement weather, is especially challenging for older drivers due to their sensitivity to glare and reduced visibility. As a result, older drivers may adjust their behavior during adverse weather. This paper explores the differential impacts of weather on older drivers with cognitive decline compared to older drivers with normal cognitive function. Data were from a naturalistic driving study of older drivers in Omaha, Nebraska. Driver speed and weather data were extracted and the correlation between speed compliance, road weather conditions, and the cognitive/neurological status of the drivers was examined. Speed compliance was used as the surrogate safety measure since driving at lower speeds can indicate that the driver is challenged by roadway or environmental conditions and can therefore indicate a risk. The percentage of time during a trip when drivers were 16.1 kph under the speed limit was modeled as the dependent variable using beta regression. The variables that resulted in the best fit model were mild cognitive impairment (MCI), age group, traffic density, and weather. Results indicated that the youngest group of older drivers (young-old) spent less time driving at impeding speeds and had the least variability compared to the other two age groups. The middle group of older drivers (middle-old) had the highest amount of time driving at impeding speeds and had more variability than young-old drivers. The oldest group of older drivers (old-old) were the most likely to drive at impeding speeds and had the most variability. In general, older drivers were more likely to drive at impeding speeds during peak hours than during non-peak hours. Additionally, in most cases, older drivers spent less time below the speed limit when the weather was clear than in adverse conditions. Results i

关键词： Traffic Safety Older Driver Cognitive Impairment Machine Learning Speed

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Experimental and analytical assessment of the hypervelocity impact damage of GLAss fiber REinforced aluminum

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Defence Technology（防务技术） 2022年第7期18卷 1232-1246页

作者： md.Zahid hasan Bangladesh Air Force Academy Bangladesh Air Force Base Matiur RahmanBAF Academy Road7404 JessoreKhulnaBangladesh

This article addresses the response of GLAss fiber REinforced aluminum to hypervelocity impacts of micrometeoroid analogs at impact velocities of 7 km/s and *** relation,the damage modes of different GLAss fiber REinforced aluminum configurations have been *** GLAss fiber REinforced aluminum configurations comprised six to twelve variably thick aluminum layers and up to four plies of glass fiber reinforced epoxy per composite *** impact experiments have been conducted with the help of a two-stage light-gas gun,wherein aluminum-and stainless steel projectiles were launched at velocities up to 7.15 km/*** inspection of the damage area suggested the dissipation of impact energy in elastic-plastic deformation,petalling,delamination,debonding,tensile failure of fibers,and pyrolysis of epoxy.A prevailing damage mode was not apparent *** quasi-isotropic ply orientation of S2-glass/FM94-epoxy laminates promoted the interference of shockand rarefaction waves and suppressed the damage area of GLAss fiber REinforced *** discriminate between the impact performance of different GLAss fiber REinforced aluminum configurations,the energy dissipated in different damage modes of GLAss fiber REinforced aluminum has been assessed *** terms of normalized energy,the cross-ply GLAss fiber REinforced aluminum dissipated higher energy in petal formation than in other primary damage *** normalized petalling energy was found to decline with the increase of impact *** outcomes of this study will help to optimize the GLAss fiber REinforced aluminum laminate,which will be employed as a bumper shield to prevent the fatal damage and the unzipping of a spacecraft pressure bulkhead.

关键词： Hypervelocity impact Petalling Fiber failure Volumetric compression Sublimation of epoxy

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