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Yousaf Hameed Khattak,Faisal Baig,Hanae Toura,Shafi Ullah,Bernabé Marí,Saira Beg,Hanif Ullah 한국물리학회 2018 Current Applied Physics Vol.18 No.6
Cu2ZnSnS4 (CZTS) is non-toxic earth abundant material and a promising quaternary semiconductor compound of group I-II-IV-VI having kesterite symmetrical structure. Due to its optimum direct band gap, it has been considered suitable material for absorber layer for photovoltaic solar cell applications. This paper presents numerical modeling of experimentally designed CZTS solar cell by applying CZTSe as back surface field (BSF) layer. In this work we reproduced results for experimentally designed CZTS solar cell in SCAPS software. The simulated results are validated and compared with real experimental results. After optimization of cell parameters conversion efficiency of an optimized device is increased up to 6.42% (with CZTS thickness of 0.8 μm). With further optimization and applying CZTSe BSF layer conversion efficiency increased up to 12.92%. Under 1.5 AM illumination condition from the proposed cell promising results had been achieved with short circuit current (Jsc) 27.41 mA/cm2, open circuit voltage (Voc) 744.4mV, fill factor (FF) 63.35% and corresponding to a total area conversion efficiency of 12.92%.
Yousaf, A.M.,Jee, J.P.,Hwang, S.R.,Maeng, H.J.,Park, Y.J.,Kim, J.O.,Yong, C.S.,Choi, H.G.,Cho, K.H. Elsevier Sequoia 2014 Powder technology Vol.267 No.-
The aim of the present research was to develop direct compression entecavir 0.5mg-loaded tablet (DCET) providing enhanced content uniformity. Various compositions and preblending methods were tested at lab-scale, and the optimum composition and method were applied to pilot-scale production for further confirmation of the entire process. The content uniformity, physical properties and dissolution behavior of the final film-coated DCET were compared to the commercial product. In lab-scale preparation, the method involving preblending, micronization of API (d<SUB>0.5</SUB>=5.13μm), addition of a larger quantity of colloidal silicon dioxide (1%) and sieving through smaller pores (300μm) yielded an excellent acceptance value (AV) in the content uniformity criteria compared to a control method and composition (AV 1.0 vs. 9.8). In pilot-scale production, the film-coated DCET provided better content uniformity than the commercial product (AV 1.3 vs. 3.8). Furthermore, both products exhibited similar dissolution profiles in various media. Thus, direct compression entecavir 0.5mg-loaded tablet developed in this study would be a promising dosage form with excellent content uniformity that may be bioequivalent to the commercial product.
System Level ESD Analysis - A Comprehensive Review II on ESD Coupling Analysis Techniques
Yousaf, Jawad,Lee, Hosang,Nah, Wansoo The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5
This study presents states-of-the art overview of the system level electrostatic discharge (ESD) analysis and testing. After brief description of ESD compliance standards and ESD coupling mechanisms, the study provides an in-depth review and comparison of the various techniques for the system level ESD coupling analysis using time and frequency domain techniques, full wave electromagnetic modeling and hybrid modeling. The methods used for improving system level ESD testing using troubleshooting and determining the root causes of soft failures, the optimization of ESD testing and the countermeasures to mitigate ESD problems are also discussed.
Yousaf Iqbal,Hongsub Bae,이일수,Sungwook Hong 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.4
Polyethylene-glycol (PEG)-coated nickel-ferrite nanoparticles were prepared for magnetic hyperthermia applications by using the co-precipitation method. The PEG coating occurred during the synthesis of the nanoparticles. The coated nanoparticles were rod-shaped with an average length of 16 nm and an average diameter of 4.5 nm, as observed using transmission electron microscopy. The PEG coating on the surfaces of the nanoparticles was confirmed from the Fourier-transform infrared spectra. The nanoparticles exhibited superparamagnetic characteristics with negligible coercive force. Further, magnetic heating effects were observed in aqueous solutions of the coated nanoparticles. The saturation temperature could be controlled at 42 C by changing the concentration of the nanoparticles in the aqueous solution. Alternately, the saturation temperature could be controlled for a given concentration of nanoparticles by changing the intensity of the magnetic field. The Curie temperature of the nanoparticles was estimated to be 495 C. These results for the PEG-coated nickel-ferrite nanoparticles showed the possibility of utilizing them for controlled magnetic hyperthermia at 42 C.
Yousaf, Nageen,Afzal, Sibtain,Hayat, Tehreem,Shah, Jasmin,Ahmad, Nafees,Abbasi, Rashda,Ramzan, Khushnooda,Jan, Rasul,Khan, Imran,Ahmed, Jawad,Siraj, Sami Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.22
Background: Vitamin D receptor (VDR) gene has been a subject of extensive pharmacogenetic research recently. Association studies between different types of cancers including prostate cancer (PCa) and VDR gene polymorphism have also been conducted. The objective of this study was to find possible associations between PCa and VDR gene polymorphisms in the Pakistani population. Materials and Methods: A total of 162 subjects, including prostate cancer patients and controls, were genotyped for Apa I, Taq I and Fok I polymorphisms in the VDR gene using allele specific PCR, PCR-RFLP and direct DNA sequencing. Allelic frequencies were tested for Hardy-Weinberg equilibrium and associations between the genetic markers and PCa were calculated using logistic regression. Results: Apa I CC genotype was found to have strongest association with PCa risk, and "A" genotype was found to have protective effect. Fok I and Taq I did not have appreciable levels of association with PCa, although Taq I "TC" heterozygotes seemed to have some protective effect. Similarly the "C" allele of Fok I also seemed to have protective effect. Conclusions: To our knowledge, this is the first report showing association between VDR gene polymorphisms and PCa in Pakistan. Our findings may be somewhat skewed because of small sample size and tendency of consanguineous marriages in Pakistani society; nevertheless, it shows the trend of association and protective effects of certain VDR gene polymorphisms against PCa.
Yousaf, Abid Mehmood,Mustapha, Omer,Kim, Dong Wuk,Kim, Dong Shik,Kim, Kyeong Soo,Jin, Sung Giu,Yong, Chul Soon,Youn, Yu Seok,Oh, Yu-Kyoung,Kim, Jong Oh,Choi, Han-Gon Dove Medical Press 2016 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.11 No.-
<P><B>Purpose</B></P><P>The purpose of the present research was to develop a novel electrosprayed nanospherule providing the most optimized aqueous solubility and oral bioavailability for poorly water-soluble fenofibrate.</P><P><B>Methods</B></P><P>Numerous fenofibrate-loaded electrosprayed nanospherules were prepared with polyvinylpyrrolidone (PVP) and Labrafil<SUP>®</SUP> M 2125 as carriers using the electrospray technique, and the effect of the carriers on drug solubility and solvation was assessed. The solid state characterization of an optimized formulation was conducted by scanning electron microscopy, powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopic analyses. Oral bioavailability in rats was also evaluated for the formulation of an optimized nanospherule in comparison with free drug and a conventional fenofibrate-loaded solid dispersion.</P><P><B>Results</B></P><P>All of the electrosprayed nanospherule formulations had remarkably enhanced aqueous solubility and dissolution compared with free drug. Moreover, Labrafil M 2125, a surfactant, had a positive influence on the solubility and dissolution of the drug in the electrosprayed nanospherule. Increases were observed as the PVP/drug ratio increased to 4:1, but higher ratios gave no significant increases. In particular, an electrosprayed nanospherule composed of fenofibrate, PVP, and Labrafil M 2125 at the weight ratio of 1:4:0.5 resulted in a particle size of <200 nm with the drug present in the amorphous state. It demonstrated the highest solubility (32.51±2.41 μg/mL), an excellent dissolution (~85% in 10 minutes), and an oral bioavailability ~2.5-fold better than that of the free drug. It showed similar oral bioavailability compared to the conventional solid dispersion.</P><P><B>Conclusion</B></P><P>Electrosprayed nanospherules, which provide improved solubility and bioavailability, are promising drug delivery tools for oral administration of poorly water-soluble fenofibrate.</P>
Pool boiling of R-123/MO and R-134a/POE lubricant mixtures on pored surfaces
Yousaf Shah,Nae-Hyun Kim 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1
In a flooded refrigerant evaporator, where enhanced tubes are frequently used, lubrication oil inevitably circulates with the refrigerant. However, the literature shows that systematic studies on this subject are lacking. In this study, the effects of oil on the pool boiling of pored surfaces having a range of pore diameter (0.1 to 0.3 mm) and pitch (0.75 to 3.0 mm) were investigated using R-134a/polyester oil (POE) and R-123/mineral oil (MO) mixtures. The saturation temperature was 26.7°C, and the oil concentration was varied up to 10 %. The results showed that the oil reduced the heat transfer coefficient. This was true for all the pored surface as well as the smooth surface. Overall, the samples having a ‘small open area’ yielded a significant degradation at a low heat flux, whereas the samples having a ‘large open area’ yielded a noticeable degradation at a high heat flux. Meanwhile, the heat transfer degradation was larger for R-134a/POE than R-123/MO, and the reason was attributed to the oil effect on the surface tension, which was stronger for R-134a/POE. The flow visualization results showed that, with the increase of oil concentration, the bubble departure diameter decreased. Similarly, the bubble generation frequency and nucleation site density decreased. These changes of the bubble dynamic parameters certainly were responsible for the heat transfer degradation. A model was developed extending that of Pastuszko et al. [27] to predict the heat transfer coefficients as well as bubble dynamic parameters. The model predicted 92 % of the heat transfer coefficients within ± 40 %.