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Low Loss La5-xSrxTi4+xAl1-xO17 Ceramics for Microwave Dielectric Applications
Yaseen Iqbal,Raz Muhammad 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.3
La5-xSrxTi4+xAl1-xO17 (x = 0, 0.20, 0.25 and 0.30) ceramics were prepared through a mixed oxide solid state sintering route and characterized in terms of phase, crystal structure, microstructure and microwave dielectric properties. La5Ti4AlO17 exhibited reasonable relative permittivity εr ~ 42, a high quality factor Q×fo ~ 18906 GHz but the temperature coefficient of resonance frequency τf ~ −19 ppm/°C was too low for practical applications. In order to tune τf through zero, Sr was substituted for La which increased εr to 47.1, decreased Q×fo to 16678 GHz and decreased negative τf to −4.8 ppm/°C at x = 0.25. The observed decrease in negative τf may be due an increase in tolerance factor and hence change in tilt scheme of BO6 octahedra as a result of substitution of larger cations for smaller cations.
Yaseen Ghulam 한국국제경제학회 2018 International Economic Journal Vol.32 No.3
The long-run financial performances of privatised firms have rarely been investigated. This study examines the financial and operational performance within the Pakistani cement industry utilising two decades of post-privatisation data. Broadly speaking, regression analyses confirm that long-term positive impacts of reforms and privatisation on profitability, output and investment are uncertain. After controlling for firm, industry and economic factors, our estimates show that privatised firms initially improved their profitability but recorded a statistically significant decline over a longer period. The sale efficiency, capacity utilisation, and leverage indicators, however, improved over a considerably long post-ownership change period.
Muhammad Yaseen,Sikandar Ali,Abullah,Naeem Ullah 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.6
Context: Global Software Development (GSD) is the software development across the globe in which stakeholders are related to different countries and cultures, and they communicate each other by emails, fax, mobile, videoconferencing or any other communicating media. There are a lot of problems in implementing requirement engineering process for global software development. There is a need of requirement implementation model which guides us how to implement successfully requirement engineering in the context of GSD. Objective: To Find Critical Success factors (CSF) and challenges in requirement implementation in the context of GSD through Systematic literature Review (SLR), and to find the practices for the proper implementation CSF and challenges as proposed by Requirement Implementation Model (RIM). Method: - SLR is the methodology used to fulfill the objectives of this research. Expected Outcomes: - SLR protocol is developed for RIM. Expected output of this study is to list out all the factors and challenge which the stakeholders are facing in implementing requirement in the context of GSD through SLR.
Mohammad Yaseen Ahmad,차현실,오인택,Tirusew Tegafaw,XUMIAO,Son Long Ho,Shanti Marasini,Adibehalsadat Ghazanfari,Huan Yue,채권석,장용민,이강호 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.4
We prepared gadolinium oxide (Gd2O3) nanoparticles (GNPs) coated with a trans‐activator of transcription (TAT) peptide with cell‐penetrating ability (i.e., TAT‐GNPs) through one‐pot process. We characterized the particle diameter, surface‐coating structure, water proton relaxivities, and in vitro cellular toxicities of the TAT‐GNPs. We measured in vivo T1 magnetic resonance images (MRI) in a model nude mouse with liver cancer prior and posterior to intravenous administration. The average particle diameter of the GNPs was 1.5 nm. The sample solution exhibited a longitudinal water proton relaxivity (r1) of 18.2/s/mM (r2/r1 = 1.6, r2 = transverse water proton relaxivity), which is four to five times higher than those of commercial Gd‐chelates. The in vivo T1 MRI exhibited positively (or T1) enhanced contrasts in the mouse liver cancer after intravenous administration, demonstrating that the TAT‐GNPs acted as an enhanced cancer‐imaging agent similar to the cancer‐targeting agent in T1 MRI.
An Investigation into Scalability Production of Ultra-Fine Nanofiber Using Electrospinning Systems
Ruaa Yaseen Hammoudi Al-Mezrakchi 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1
An integrated experimental and modeling approach was utilized to study scalable production of nanofibers via electrospinning. Two concepts have been investigated to study the fabrication of PAN nanofibers, which are needle-based and orifice-guided electrospinning to utilize the optimum setup. Moreover, it was observed that the natural flow rate of electrospinning does not scale linearly with number of needles (unlike polymer processing methods such as dry spinning), which was explained based on the partial pressure of the solvent vapor, peculiar to multi-needle setup, and the stress relaxation in the solution. In addition, it was demonstrated that the minimum voltage required to continuously electrospun fibers increases as the distance between needles is reduced, which was explained by the shielding effect of neighboring needles and elucidated by the Finite Element Analysis (FEA) models. Nano-fibers with diameters less than 100 nm were produced in this investigation.
M.S. Yaseen,G. Murtaza,Rana M. Arif Khalil 한국물리학회 2018 Current Applied Physics Vol.18 No.10
Structural, electronic, optical, and thermoelectric aspects of chalcopyrite LiGaX2 (X=S, Se and Te) compounds have been investigated by density functional theory (DFT) based Wien2k simulator. The optimized ground state parameters are calculated by Wu-Cohen generalized gradient approximation (WC-GGA) and electronic structures, which have been further improved by modified Becke-Johnson (mBJ) potential. Moreover, a comparative study is given among the contribution of three anions (S, Se and Te) in the same symmetry of tetragonal phase. The calculated band gaps of the studied compounds are 3.39, 2.83, and 1.96 eV for LiGaS2, LiGaSe2 and LiGaTe2, respectively. The observed band gaps consider the studied compounds are potential materials for optoelectronic devices. In addition, the optical response of the studied materials has been analyzed in terms of dielectric constants, refraction, absorption, reflectivity and energy loss function. We have also reported the thermoelectric properties like Seebeck coefficient, thermal and electrical conductivities, and figure of merit as function of temperatures by using BoltzTrap code. The high thermal efficiency and absorption spectra in the visible region make the studied materials multifunctional for energy applications.