Strain Dependent Performance Analysis of InGaN Multi-junction Solar Cell

Md. Aminur Rahman,Md. Jahirul Islam,Md. Rafiqul Islam,M. A. Parvez Mahmud 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6

This study reports the strain-dependent efficiency of the InGaN-based multi-junction solar cell (MJSC) for the first time. The route of strain in MJSC is identifi ed to be the results of dissimilar lattice constants between layers of sub-cell grown epitaxially with bandgap stepping. Utilising multi-layered strain model, the state of strain and its magnitude is evaluated for three types of MJSC structures referred to as MJSC-1, MJSC-2, and MJSC-3. It is found that the MJSC position-dependent strain is strongly dependent on the sub-cell thickness as well as on the number of sub-cells. Employing the MJSC position-dependent strain in combination with deformation potentials, strain-induced energy bandgap is calculated when imposed under tensile strain condition. Finally, the strain-dependent efficiencies of different MJSC structures are estimated and obtained to be lower with that of reported with strain effects over sighted. The loss of efficiency is identifi ed to be due to the open circuit voltage which decreases under tensile strain condition. Among the MJSC structures studied here, MJSC-3 with 7-layers is less efficient and its efficiency decreases up to 3.01% when strain effect is taken into consideration.

Sectoral Wage Differentials in Bangladesh: A Comparison Between the Government and Other Ownerships

Rahman Md Aminur,김우영 한국국제경제학회 2023 International Economic Journal Vol.37 No.4

Most of the studies of wage discrimination in Bangladesh have calculated the gap between pairs of sectors, while this study uses multiple sectors using multinomial logit estimation where the sector selection is endogenous. The employment sector is divided into six heterogeneous sectors depending on ownership status. Using QLFS 2016–2017 data from the Bangladesh Bureau of Statistics, the probability of being employed in a certain sector is initially estimated by the sector choice equation, and then we estimate both the conditional and unconditional wage gaps between government and other sectors. The estimation result of the sector choice shows that the probability of being included in the government sector mostly depends on educational qualification, and the rural population is mostly included in marginal sectors like individual proprietorship. The decomposition of wage discrimination indicates that government employees have a wage advantage over every other sector, except for females. The decomposition result also suggests that thewagegapis mostly driven by discrimination, with NGOs showing the most discrimination in wages offered, followed by the individual sector. Monitoring the wage structure and implementation of the minimum wage is our main policy recommendation, along with others.

Electrochemical Biosensors for Biomedical and Clinical Applications: A Review

Rahman Md. Aminur,Park Deog-Su,Shim Yoon-Bo The Korean Society of Medical and Biological Engin 2005 의공학회지 Vol.26 No.5

There are strong demands for accurate, fast, and inexpensive devices in the medical diagnostic laboratories, such as biosensors and chemical sensors. Biosensors can provide the reliable and accurate informations on the desired biochemical parameters, which is an essential prerequisite for a patient before going for a treatment. They can be used for continuous measurements of metabolites, blood cations, gases, etc. Of these, electrochemical biosensors play an important role in the improvement of public health, because rapid detection, high sensitivity, small size, and specificity are achievable for clinical diagnostics. In this paper, the clinical applications with electrochemical biosensors are reviewed. An attempt is also made to highlight some of the trends that govern the research and developments of the important biosensors that are associated to clinical diagnosis.

Xanthine Sensors Based on Anodic and Cathodic Detection of Enzymatically Generated Hydrogen Peroxide

Rahman, Md. ,Aminur,Won, Mi-Sook,Shim, Yoon-Bo WILEY-VCH Verlag 2007 Electroanalysis Vol.19 No.6

<P>A xanthine biosensor was fabricated by the covalent immobilization of xanthine oxidase (XO) onto a functionalized conducting polymer (Poly-5, 2′: 5′, 2″-terthiophine-3-carboxylic acid), poly-TTCA through the formation of amide bond between carboxylic acid groups of poly-TTCA and amine groups of enzyme. The immobilization of XO onto the conducting polymer (XO/poly-TTCA) was characterized using cyclic voltammetry, quartz crystal microbalance (QCM), and X-ray photoelectron spectroscopy (XPS) techniques. The direct electron transfer of the immobilized XO at poly-TTCA was found to be quasireversible and the electron transfer rate constant was determined to be 0.73 s<SUP>−1</SUP>. The biosensor efficiently detected xanthine through oxidation at +0.35 V and reduction at −0.25 V (versus Ag/AgCl) of enzymatically generated hydrogen peroxide. Various experimental parameters, such as pH, temperature, and applied potential were optimized. The linear dynamic ranges of anodic and cathodic detections of xanthine were between 5.0×10<SUP>−6</SUP>−1.0×10<SUP>−4</SUP> M and 5.0×10<SUP>−7</SUP> to 1.0×10<SUP>−4</SUP> M, respectively. The detection limits were determined to be of 1.0×10<SUP>−6</SUP> M and 9.0×10<SUP>−8</SUP> M with anodic and cathodic processes, respectively. The applicability of the biosensor was tested by detecting xanthine in blood serum and urine real samples.</P>

Stimulated mass enhancement strategy-based highly sensitive detection of a protein in serum using quartz crystal microbalance technique

Akter, Rashida,Jeong, Bongjin,Rahman, Md. Aminur The Royal Society of Chemistry 2015 The Analyst Vol.140 No.4

<P>A stimulated mass enhancement strategy based on enormous biocatalytic precipitation of 4-chloro-1-naphthol using magnetic bead-supported horseradish peroxidase and glucose oxidase bienzymes was developed for the highly sensitive detection of interleukin-6 in serum using a quartz crystal microbalance technique.</P> <P>Graphic Abstract</P><P>A quartz crystal microbalance immunosensor is described for highly sensitive detection of interleukin-6 in serum using a magnetic bead-supported bienzyme-catalyzed stimulated mass enhancement strategy. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4an01555j'> </P>

Analysis of polymerase chain reaction amplifications through phosphate detection using an enzyme–based microbiosensor in a microfluidic device

Shiddiky, Muhammad J. A.,Rahman, Md. Aminur,Park, Jang-Su,Shim, Yoon-Bo WILEY-VCH Verlag 2006 Electrophoresis Vol.27 No.14

<P>An electrochemical method was developed for analyzing PCR amplification through the detection of inorganic phosphates (Pi). This method coupled a microchip to a nanoparticle comprising poly-5,2'-5',2''-terthiophene-3'-carboxylic acid (poly-TTCA)/pyruvate oxidase (PyO) modified microbiosensor. It detects Pi produced from the pyrophosphate (PPi), which is released as a byproduct of PCR. After completion of PCR, PPi is hydrolyzed to Pi by inorganic pyrophosphatase. On the microbiosensor surface, pyruvate was converted to H<SUB>2</SUB>O<SUB>2</SUB> by PyO in the presence of Pi and oxygen, and subsequently, the anodic current of enzymatically generated H<SUB>2</SUB>O<SUB>2</SUB> was detected at +0.5 V versus Ag/AgCl. The CE-EC analysis was completed within 2 min in a coated channel with 75.0 mm separation length at the field strength of −200 V/cm. Excellent operation stability of poly-TTCA/PyO was observed for a long period of analysis. The reproducibility of the analysis yielded an RSD of 3.4% (n = 22) for the peak areas and 1.8% (n = 22) for the migration times. The sensitivity of the analysis was 0.59 ± 0.01 nA/cycle with a regression coefficient of 0.971.</P>

Simultaneous Determination of Hydroquinone and Catechol at an Activated Glassy Carbon Electrode

Ahammad, A. J. Saleh,Sarker, Subrata,Rahman, Md Aminur,Lee, Jae-Joon WILEY-VCH Verlag 2010 Electroanalysis Vol.22 No.6

<P>A selective and very simple electrochemical method, based on anodization of a glassy carbon electrode (GCE), was developed for the simultaneous detection of hydroquinone (HQ) and catechol (CT). It was found that the activated GCE showed an excellent catalytic behavior and enhanced reversibility towards the oxidation of both HQ and CT. The redox responses from the mixture of HQ and CT were easily resolved at an activated GCE. The detection limits for HQ and CT were calculated to be 0.16 and 0.11 μM, respectively. The activated GCE was successfully examined for real sample analysis with tap water and it showed a stable and reliable recovery data.</P>

Repeated cocaine administration increases <i>N</i>-methyl-<small>D</small>-aspartate NR1 subunit, extracellular signal-regulated kinase and cyclic AMP response element-binding protein phosphorylation and glutamate release in the rat dorsal striatum

Lee, Dong Kun,Bian, Shengjie,Rahman, Md. Aminur,Shim, Yoon-Bo,Shim, Insop,Choe, Eun Sang Elsevier 2008 european journal of pharmacology Vol.590 No.1

<P><B>Abstract</B></P><P>This study was conducted to determine the phosphorylation state of <I>N</I>-methyl-<SMALL>D</SMALL>-aspartate (NMDA) NR1 subunit on serine residues 896 (Ser896) and 897 (Ser897), the extracellular signal-regulated kinase 1/2 (ERK1/2), and the cyclic AMP response element-binding protein (CREB) after repeated exposure to cocaine (20?mg/kg, once daily for 9?days) in the dorsal striatum of rats. The real-time changes of glutamate concentration evoked by repeated cocaine injections were examined using a glutamate biosensor in order to evaluate the correlation between glutamate concentration and the change in these phosphoproteins. The results of this study showed that the immunoreactivity of phosphorylated (p)NMDA NR1 subunit at Ser896 and Ser897 as well as pERK1/2, but not pCREB, in the dorsal striatum was increased at 30?min and then returned to basal levels 4?h after repeated cocaine injections. Similarly, glutamate responses evoked by repeated cocaine injections were also increased 30?min after repeated cocaine injections for 3?days and were prolonged by the 9th day of treatment. However, the glutamate responses were not detected at 4?h after repeated cocaine injections for 5?days. In addition, the elevated immunoreactivity of the phosphoproteins 2?h after repeated cocaine injections was attenuated by the blockade of dopamine D1 receptors and NMDA receptors with the SCH23390 or MK801 antagonists, respectively. These findings suggest that glutamate release and dopamine D1 and NMDA receptor stimulation after repeated exposure to cocaine are associated with NMDA NR1 subunit, ERK1/2 and CREB phosphorylation in the dorsal striatum.</P>

Ultrasensitive Nanoimmunosensor by coupling non-covalent functionalized graphene oxide platform and numerous ferritin labels on carbon nanotubes

Akter, Rashida,Jeong, Bongjin,Choi, Jong-Soon,Rahman, Md. Aminur Elsevier Applied Science 2016 Biosensors & bioelectronics Vol. No.

<P><B>Abstract</B></P> <P>An ultrasensitive electrochemical nanostructured immunosensor for a breast cancer biomarker carbohydrate antigen 15-3 (CA 15-3) was fabricated using non-covalent functionalized graphene oxides (GO/Py-COOH) as sensor probe and multiwalled carbon nanotube (MWCNTs)-supported numerous ferritin as labels. The immunosensor was constructed by immobilizing a monoclonal anti-CA 15-3 antibody on the GO modified cysteamine (Cys) self-assembled monolayer (SAM) on an Au electrode (Au/Cys) through the amide bond formation between the carboxylic acid groups of GO/Py-COOH and amine groups of anti-CA 15-3. Secondary antibody conjugated MWCNT-supported ferritin labels (Ab<SUB>2</SUB>-MWCNT-Ferritin) were prepared through the amide bond formation between amine groups of Ab<SUB>2</SUB> and ferritin and carboxylic acid groups of MWCNTs. The detection of CA 15-3 was based on the enhanced bioelectrocatalytic reduction of hydrogen peroxide mediated by hydroquinone (HQ) at the GO/Py-COOH-based sensor probe. The GO/Py-COOH-based sensor probe and Ab<SUB>2</SUB>-MWCNT-Ferritin labels were characterized using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), transmission electron microscope (TEM), and x-ray photoelectron spectroscopy (XPS) techniques. Using differential pulse voltammetry (DPV) technique, CA 15-3 can be selectively detected as low as 0.01±0.07U/mL in human serum samples. Additionally, the proposed CA 15-3 immunosensor showed excellent selectivity and better stability in human serum samples, which demonstrated that the proposed immunosensor has potentials in proteomic researches and diagnostics.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Serum-based CA 15-3 immunosensor was fabricated. </LI> <LI> Immunosensor was fabricated using non-covalent graphene oxide probe. </LI> <LI> Enhanced detection was achieved using carbon nanotube supported ferritin labels. </LI> <LI> The catalytic activity of ferritin was utilized for the signal generation. </LI> <LI> Detection limit of CA 15-3 in serum was as low as 0.01U/mL. </LI> </UL> </P>

Influence of hard rock dust on the physical and microstructural properties of red ceramic materials

Ahmed Aninda Nafis,Sultana Mst. Shanjida,Zaman Mohammad Nazim,Rahman Md. Aminur 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.1

Rock dust disposal is a concern in a hard rock mining site which results from blasting operation during mining. Signifi cant amount of rock dust is generated during mining which causes dusting problem as well. In this work, Rock dust was used with red clay to produce ceramic tiles. XRF analysis revealed the existence of more than 60 wt.% SiO 2 in red clay and more than 50 wt.% SiO 2 in rock dust. Pressed ceramic bodies having diff erent amount (10–30 wt.%) of rock dust were sintered at 1050 °C, 1100 °C and 1150 °C. Diff erent properties were measured for ceramics samples such as water absorption, porosity, mechanical strength, linear shrinkage and bulk density. Lowering of porosity (1.88–10.17%) and water absorption (1.1–6.03%) were found with 10–30 wt.% rock dust addition. Above 50 MPa of compressive strength was found, which is satisfactory for producing ceramic tiles. Microstructures of ceramics samples studied by FESEM provided eff ective information on structure-property relationships. Maximum quantities of rock dust waste were utilized, in reducing environmental pollution and establishing it as a raw material for ceramics industries.