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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%.
An Experimental Study on R-134a Distribution in a 2-row/6-pass Evaporator
Yousaf Shah,Cheol-hwan kim,Nae-Hyun Kim 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.6
There are many factors to be considered for investigation to improve the performance of air-conditioning and refrigeration. In this particular study we carried out experiments on the parallel flow distribution of refrigerant effected by the geometrical parameters, Orientation of header assembly, and variation in mass flux. R-134a flow distribution was experimentally investigated for 2-row and 6-pass configuration of micro-channel heat exchanger. Experiments were carried out with downward flow and upward flow for mass flux from 70 to 120 kg/hr and quality was maintained 0.2 at inlet of header. Tubes were protruded into D-shape header. Additional heaters were used at micro-channels to maintain the superheated condition of 5°C.
Yousaf Iqbal,배홍섭,이일수,홍성욱 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.10
Spinel-structured manganese (Mn)-nickel (Ni)-ferrite nanoparticles were synthesized using achemical co-precipitation method. Coating with PEG (polyethylene glycol) was simultaneouslyconducted along with the synthesis of Mn-Ni-ferrites. The X-ray diffraction (XRD) and theFourier-transform infrared (FTIR) analyses revealed a cubic spinel ferrite structure of the synthesizednanoparticles. Transmission electron microscopy (TEM) images showed that the synthesizednanoparticles were rod-shaped with a uniform size distribution and that the average length andwidth were 15.13 ± 1.32 nm and 3.78 ± 0.71 nm, respectively. The bonding status of PEG onthe nanoparticle surface was checked by using FTIR. The relaxivities of the hydrogen protons inthe aqueous solutions of the coated particles were determined by using nuclear magnetic resonance(NMR) spectrometry. The T1 and the T2 relaxivities were 0.34 ± 0.11 mM−1s−1 and 29.91 ± 0.98mM−1s−1, respectively. This indicates that the synthesized PEG-coated Mn-Ni-ferrite nanoparticlesare suitable for use as T2 contrast agents.
Yousaf, Abid Mehmood,Kim, Dong Wuk,Oh, Yu-Kyoung,Yong, Chul Soon,Kim, Jong Oh,Choi, Han-Gon Dove Medical Press 2015 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.10 No.-
<P><B>Background</B></P><P>The intention of this research was to prepare and compare various solubility-enhancing nanoparticulated systems in order to select a nanoparticulated formulation with the most improved oral bioavailability of poorly water-soluble fenofibrate.</P><P><B>Methods</B></P><P>The most appropriate excipients for different nanoparticulated preparations were selected by determining the drug solubility in 1% (w/v) aqueous solutions of each carrier. The polyvinylpyrrolidone (PVP) nanospheres, hydroxypropyl-β-cyclodextrin (HP-β-CD) nanocorpuscles, and gelatin nanocapsules were formulated as fenofibrate/PVP/sodium lauryl sulfate (SLS), fenofibrate/HP-β-CD, and fenofibrate/gelatin at the optimized weight ratios of 2.5:4.5:1, 1:4, and 1:8, respectively. The three solid-state products were achieved using the solvent-evaporation method through the spray-drying technique. The physicochemical characterization of these nanoparticles was accomplished by powder X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Their physicochemical properties, aqueous solubility, dissolution rate, and pharmacokinetics in rats were investigated in comparison with the drug powder.</P><P><B>Results</B></P><P>Among the tested carriers, PVP, HP-β-CD, gelatin, and SLS showed better solubility and were selected as the most appropriate constituents for various nanoparticulated systems. All of the formulations significantly improved the aqueous solubility, dissolution rate, and oral bioavailability of fenofibrate compared to the drug powder. The drug was present in the amorphous form in HP-β-CD nanocorpuscles; however, in other formulations, it existed in the crystalline state with a reduced intensity. The aqueous solubility and dissolution rates of the nanoparticles (after 30 minutes) were not significantly different from one another. Among the nanoparticulated systems tested in this study, the initial dissolution rates (up to 10 minutes) were higher with the PVP nanospheres and HP-β-CD nanocorpuscles; however, neither of them resulted in the highest oral bioavailability. Irrespective of relatively retarded dissolution rate, gelatin nanocapsules showed the highest apparent aqueous solubility and furnished the most improved oral bioavailability of the drug (~5.5-fold), owing to better wetting and diminution in crystallinity.</P><P><B>Conclusion</B></P><P>Fenofibrate-loaded gelatin nanocapsules prepared using the solvent-evaporation method through the spray-drying technique could be a potential oral pharmaceutical product for administering the poorly water-soluble fenofibrate with an enhanced bioavailability.</P>
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 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.
Efficient Circuit and an EM Model of an Electrostatic Discharge Generator
Yousaf, Jawad,Park, Myeongkoo,Lee, Hosang,Youn, Jinsung,Lee, Daehee,Hwang, Chanseok,Nah, Wansoo [Institute of Electrical and Electronics Engineers 2018 IEEE transactions on electromagnetic compatibility Vol.60 No.4
<P>In this work, a new technique for an efficient, simple, and fast equivalent circuit and full wave numerical modeling of the electrostatic discharge (ESD) generator is presented. A novel circuit model of the NoiseKen ESD simulator is proposed based on the frequency domain measurement of the standard waveform calibration setup. The simple full wave electromagnetic model of the same generator, which requires much less computation resources, is also proposed using commercial CST Microwave Studio software. The reliability of the proposed models as an authentic ESD excitation source is validated through an example discharge application. The good agreement between the ESD reference waveform obtained through measurement, circuit model, and 3-D model of the generator is observed.</P>
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.