SWIR-LWIR Photoluminescence from Sb-based Epilayers Grown on GaAs Substrates by using MBE

Laiq Hussain,Hakan Pettersson,Qin Wang,Amir Karim,Jan Anderson,Mehrdad Jafari,Jin Dong Song,Won Jun Choi,Il Ki Han,Ju Young Lim 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.73 No.11

Utilizing Sb-based bulk epilayers on large-scale low-cost substrates such as GaAs for fabricating infrared (IR) photodetectors is presently attracting significant attention worldwide. For this study, three sample series of GaAsxSb1x, In1xGaxSb, and InAsxSb1x with different compositions were grown on semi-insulating GaAs substrates by using molecular beam epitaxy (MBE) and appropriate InAs quantum dots (QDs) as a defect-reduction buffer layer. Photoluminescence (PL) signals from these samples were observed over a wide IR wavelength range from 2 m to 12 m in agreement with the expected bandgap, including bowing effects. In particular, interband PL signals from InAsxSb1x and In1xGaxSb samples even at room temperature show promising potential for IR photodetector applications.

Reversible hydrogen storage properties of defect-engineered _{C 4} N nanosheets under ambient conditions

Alhameedi, Khidhir,Hussain, Tanveer,Bae, Hyeonhu,Jayatilaka, Dylan,Lee, Hoonkyung,Karton, Amir Elsevier 2019 Carbon Vol.152 No.-

<P><B>Abstract</B></P> <P>Inspired by the promise of hydrogen (H<SUB>2</SUB>) as a clean alternate to the existing energy sources, we have employed spin-polarized density functional theory calculations on a recently designed two-dimensional <SUB> C 4 </SUB> N monolayer as a promising <SUB> H 2 </SUB> storage material. By means of first principles DFT calculations, we have comprehensively studied the geometric and electronic properties of pristine, defected and metal-doped <SUB> C 4 </SUB> N nanosheets and further explored their <SUB> H 2 </SUB> storage properties. We found that light metal dopants such as Li, Na, K, Mg, and Ca bind strongly to defects on a <SUB> C 4 </SUB> N nanosheet with binding energies of 3–4 eV per dopant. These binding energies are sufficiently strong to surpass metal clustering. Thermal stability of the metal-doped <SUB> C 4 </SUB> N nanosheets has been further verified by means of ab initio molecular dynamics simulations. The bonding nature of the metal dopants with the <SUB> C 4 </SUB> N nanosheet has been studied through Bader analysis and Roby-Gould methods and the electronic properties were studied through density of states. We found that each dopant in the metal-doped <SUB> C 4 </SUB> N nanosheet can bind up to five <SUB> H 2 </SUB> molecules with adsorption energies ranging between 0.15 and 0.60 eV/ <SUB> H 2 </SUB> , which results in optimal <SUB> H 2 </SUB> storage capacities. Finally, we employed thermodynamic analysis to investigate the <SUB> H 2 </SUB> adsorption/desorption mechanism under practical operating conditions.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Stiff, Strong, Yet Tough Free-Standing Dielectric Films of Graphene Nanosheets-Polyurethane Nanocomposites with Very High Dielectric Constant and Loss

Rahim Jan,AMIR HABIB,Iftikhar Hussain Gul 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.1

In this study, graphene nanosheets (GNS) prepared through a liquid exfoliationtechnique are dispersed in thermoplastic polyurethane (TPU) at a volume fraction(Vf) of up to 0.19. Then, the electrical and mechanical properties of the obtainedcomposites are characterized. The dielectric spectroscopy shows an excessivevariation in dielectric constant (1.1 to 3.53 × 107) and dielectric tangent loss (0.03to 2515) with varying Vf over the frequency range of 25 kHz to 5 MHz. Aconsiderable enhancement in electrical conductivity (DC) is found, from3.87 × 10−10 S/m (base polymer) to 53.5 S/m for the 0.19 Vf GNS-TPUnanocomposite. The GNS-TPU composites are mechanically robust, with aconsiderable increase in stiffness (~4-fold) and strength (almost twice),maintaining its ductility up to 0.09 Vf GNS. The high dielectric constant at lowerfrequencies is attributed to the well-established Maxwell-Wagner polarizationeffect, whereas the high dielectric tangent loss is due to leakage currents as aphysical conducting network is formed at high filler loadings. The layeredstructure, high aspect ratio, and improved dispersion of GNS are the main reasonsfor the improvement in both the dielectric characteristics and the mechanicalproperties of the host polymer.

Novel aryl carbamate derivatives of metronidazole as potential antiamoebic agents

Hayat Faisal,HUSSAIN MUSTATAB WAHEDI,Seonghyeok Park,Saba Tariq,Amir Azam,신동윤 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.1

A series of novel aryl carbamate derivatives of metronidazole (MNZ) were designed, synthesized, and screened for antiamoebic activity. As compared to MNZ, most of the derivatives exhibited moderate to excellent activity against the HM1:IMSS strain of Entamoeba histolytica. Compounds 7, 14, 16, 19, and 21 exhibited the most promising antiamoebic activity with IC50 values of 0.24, 0.08, 0.26, 0.26, and 0.15 lM, respectively, compared to that of MNZ (1.78 lM). Moreover, from the toxicological studies of these compounds on human melanocytes, the melan-a cell line revealed that the potent compounds are nontoxic at concentrations ranging from 2.5 to 50 lM.

Molecular and in silico analyses validates pathogenicity of homozygous mutations in the <i>NPR2</i> gene underlying variable phenotypes of <i>Acromesomelic dysplasia</i>, type Maroteaux

Irfanullah,Zeb, Amir,Shinwari, Naila,Shah, Khadim,Gilani, Syed Zohaib Tayyab,Khan, Saadullah,Lee, Keun Woo,Raza, Syed Irfan,Hussain, Shabir,Liaqat, Khurram,Ahmad, Wasim Pergamon 2018 The international journal of biochemistry & cell b Vol.102 No.-

<P><B>Abstract</B></P> <P>Homozygous and/or heterozygous loss of function mutations in the natriuretic peptide receptor B (<I>NPR2</I>) have been reported in causing acromesomelic dysplasia, type Maroteaux with variable clinical features and idiopathic short stature with nonspecific skeletal deformities. On the other hand, gain of function mutations in the same gene result in overgrowth disorder suggesting that NPR2 and its ligand, natriuretic peptide precursor C (CNP), are the key players of endochondral bone growth. However, the precise mechanism behind phenotypic variability of the <I>NPR2</I> mutations is not fully understood so far.</P> <P>In the present study, three consanguineous families of Pakistani origin (A, B, C) with variable phenotypes of acromesomelic dysplasia, type Maroteaux were evaluated at clinical and molecular levels. Linkage analysis followed by Sanger sequencing of the <I>NPR2</I> gene revealed three homozygous mutations including p.(Leu314 Arg), p.(Arg371*), and p.(Arg1032*) in family A, B and C, respectively. In silico structural and functional analyses substantiated that a novel missense mutation [p.(Leu314 Arg)] in family A allosterically affects binding of NPR2 homodimer to its ligand (CNP) which ultimately results in defective guanylate cyclase activity. A nonsense mutation [p.(Arg371*)] in family B entirely removed the transmembrane domain, protein kinase domain and guanylate cyclase domains of the NPR2 resulting in abolishing its guanylate cyclase activity. Another novel mutation [p.(Arg1032*)], found in family C, deteriorated the guanylate cyclase domain of the protein and probably plundered its guanylate cyclase activity. These results suggest that guanylate cyclase activity is the most critical function of the NPR2 and phenotypic severity of the NPR2 mutations is proportional to the reduction in its guanylate cyclase activity.</P>

Comparative Analysis of Arabic Vowels using Formants and an Automatic Speech Recognition System

Yousef Ajami Alotaibi,Amir Hussain 보안공학연구지원센터(IJSIP) 2010 International Journal of Signal Processing, Image Vol.3 No.2

Exponential Stabilization of a Class of Underactuated Mechanical Systems using Dynamic Surface Control

Nadeem Qaiser,Naeem Iqbal,Amir Hussain,Naeem Qaiser 대한전기학회 2007 International Journal of Control, Automation, and Vol.5 No.5

This paper proposes a simpler solution to the stabilization problem of a special class of nonlinear underactuated mechanical systems which includes widely studied benchmark systems like Inertia Wheel Pendulum, TORA and Acrobot. Complex internal dynamics and lack of exact feedback linearizibility of these systems makes design of control law a challenging task. Stabilization of these systems has been achieved using Energy Shaping and damping injection and Backstepping technique. Former results in hybrid or switching architectures that make stability analysis complicated whereas use of backstepping some times requires closed form explicit solutions of highly nonlinear equations resulting from partial feedback linearization. It also exhibits the phenomenon of explosions of terms resulting in a highly complicated control law. Exploiting recently introduced Dynamic Surface Control technique and using control Lyapunov function method, a novel nonlinear controller design is presented as a solution to these problems. The stability of the closed loop system is analyzed by exploiting its two-time scale nature and applying concepts from Singular Perturbation Theory. The design procedure is shown to be simpler and more intuitive than existing designs. Design has been applied to important benchmark systems belonging to the class demonstrating controller design simplicity. Advantages over conventional Energy Shaping and Backstepping controllers are analyzed theoretically and performance is verified using numerical simulations.

Analysis of a Non-Evaporable Getter of Ti-Al-Zr Thin Film with Enhanced Performance Used for Ultra-High Vacuum Generation

Muhammad Khalid Alamgir,M. Ikram,Ghalib Hussain Mughal,Ghulam Asghar,Sha q ur Rehman,S. Qaseem,M. Kamran,Amir Ullah,Sartaj Khan 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.5

Non-evaporable getter (NEG) thin films of Ti-Al-Zr and Ti-Zr were prepared on stainless-steel substrate by using the cathodic arc deposition technique. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and in-situ X-ray photoelectron spectroscopy (XPS) were used to analyze the getter behavior of the non-evaporable getter thin films. The SEM images displayed the porous and rough surfaces of the thin films, which is an indication of high adsorption and sticking probabilities for the residual gases present in the chamber. The volume elemental composition of the thin films was measured by using EDX. The XRD patterns of the synthesized thin films indicated that the films had an amorphous nature and high structural stability. The in-situ X-ray photoelectron spectroscopy (XPS) studies revealed that the superficial layers disappeared when the non-evaporable getter of Ti-Al-Zr thin films was heated at a temperature below 250~$^\circ$C for 30 minutes, there by activating the surface. However, for Ti-Zr thin films, no reasonable activation was observed at 250~$^\circ$C. This outcome reveals that thin films of Ti-Al-Zr are good for reducing the outgassing and producing an ultra-high vacuum.

Mortality Prediction from Hospital-Acquired Infections in Trauma Patients Using an Unbalanced Dataset

Mehrdad Karajizadeh,Mahdi Nasiri,Mahnaz Yadollahi,Amir Hussain Zolfaghari,Ali Pakdam 대한의료정보학회 2020 Healthcare Informatics Research Vol.26 No.4

Objectives: Machine learning has been widely used to predict diseases, and it is used to derive impressive knowledge in thehealthcare domain. Our objective was to predict in-hospital mortality from hospital-acquired infections in trauma patientson an unbalanced dataset. Methods: Our study was a cross-sectional analysis on trauma patients with hospital-acquired infectionswho were admitted to Shiraz Trauma Hospital from March 20, 2017, to March 21, 2018. The study data was obtainedfrom the surveillance hospital infection database. The data included sex, age, mechanism of injury, body region injured, severityscore, type of intervention, infection day after admission, and microorganism causes of infections. We developed ourmortality prediction model by random under-sampling, random over-sampling, clustering (k-mean)-C5.0, SMOTE-C5.0,ADASYN-C5.5, SMOTE-SVM, ADASYN-SVM, SMOTE-ANN, and ADASYN-ANN among hospital-acquired infectionsin trauma patients. All mortality predictions were conducted by IBM SPSS Modeler 18. Results: We studied 549 individualswith hospital-acquired infections in a trauma hospital in Shiraz during 2017 and 2018. Prediction accuracy before balancingof the dataset was 86.16%. In contrast, the prediction accuracy for the balanced dataset achieved by random under-sampling,random over-sampling, clustering (k-mean)-C5.0, SMOTE-C5.0, ADASYN-C5.5, and SMOTE-SVM was 70.69%, 94.74%,93.02%, 93.66%, 90.93%, and 100%, respectively. Conclusions: Our findings demonstrate that cleaning an unbalanced datasetincreases the accuracy of the classification model. Also, predicting mortality by a clustered under-sampling approach wasmore precise in comparison to random under-sampling and random over-sampling methods.

The Impact of ENSO Phase Transition on the Atmospheric Circulation, Precipitation and Temperature in the Middle East Autumn

Faranak Bahrami,Abbas Ranjbar Saadatabadi,Amir Hussain Meshkatee,Gholamali Kamali 한국기상학회 2020 Asia-Pacific Journal of Atmospheric Sciences Vol.56 No.3

The impact of El Niño–Southern Oscillation (ENSO) phase transition on the atmospheric circulations, precipitation and temperature in the Middle East (ME) during the period of 1950–2018 autumn seasons were analyzed. ENSO events were selected based on the Oceanic Nino Index (ONI) and its phase transition from ElNino to LaNina (type 1) and fromLaNina to ElNino (type 2) events during the study period. Monthly and climatemeans of data for precipitation, temperature, geopotential height,wind components (u and v) and Sea level pressure (SLP) obtained from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. Composites of the means and anomalies were derived from selected case studies of the ENSO phase transitions. Finally, the student’s t test is used to determine the significance of the composite means in each grid point. The results show during transitions, the SLP structure over the Atlantic region changes, in a way that pressure differences between Iceland low and the Azores high during type 1 (type 2) is minimum (Maximum) and also statistically significant at 95% confidence level which, these conditions are accompanied by statistically significant enhancing (decreasing) rainfall over the most parts of the ME. In addition, the variability of upper level geopotential height and zonal wind were found over the region which lead to favorable or less favorable conditions for infiltration of planetary Rossby waves to the ME in type 2 and type 1, respectively. Also this study reveals that, moisture flux transport from the adjoining seas to the ME is extremely different in both types, so that during type 2 (type 1), the ME receives significant (insignificant) amounts of moisture. This study therefore identified that most parts of the ME experienced statistically significant positive (negative) anomalies of precipitation during type 2 and type 1 respectively.