Effect of the preparation method on crystallinity, particle size, aqueous solubility and dissolution of different samples of the poorly water-soluble fenofibrate with HP-β-CD

Yousaf, Abid Mehmood,Kim, Dong Wuk,Cho, Kwan Hyung,Kim, Jong Oh,Yong, Chul Soon,Choi, Han-Gon Springer-Verlag 2015 JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHE Vol.81 No.3

Effect of CZTSe BSF and minority carrier life time on the efficiency enhancement of CZTS kesterite solar cell

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%.

Enhanced oral bioavailability of fenofibrate using polymeric nanoparticulated systems: physicochemical characterization and in vivo investigation

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>

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.

Use of abdominal compression device in colonoscopy: a systematic review and meta-analysis

Yousaf Zafar,Ahmed Mustafa Rashid,Syed Sarmad Javaid,Ahmed Kamal Siddiqi,Adnan Zafar,Arsalan Zafar Iqbal,Jagpal Singh Klair,Rajesh Krishnamoorthi 대한소화기내시경학회 2023 Clinical Endoscopy Vol.56 No.4

Background/Aims: Colonoscopy for screening is associated with unpleasant experiences for patients, and abdominal compression devices have been developed to minimize these problems. However, there is a paucity of data supporting the therapeutic benefits of this strategy. This study examined the effects of using an abdominal compression device during colonoscopy on the cecal intubation time (CIT), abdominal compression, patient comfort, and postural changes. Methods: We searched PubMed and Scopus (from inception to November 2021) for randomized controlled trials that assessed the effects of an abdominal compression device during colonoscopy on CIT, abdominal compression, patient comfort, and postural change. A random-effects meta-analysis was performed. Weighted mean differences (WMDs) and Mantel-Haenszel odds ratios (ORs) were calculated. Results: Our pooled analysis of seven randomized controlled trials revealed that abdominal compression devices significantly reduced CIT (WMD, –0.76 [–1.49 to –0.03] minutes; p=0.04), abdominal compression (OR, 0.52; 95% confidence interval [CI], 0.28–0.94; p=0.03), and postural changes (OR, 0.46; 95% CI, 0.27–0.78; p=0.004) during colonoscopy. However, our results did not show a significant change in patient comfort (WMD, –0.48; 95% CI, –1.05 to 0.08; p=0.09) when using an abdominal compression device. Conclusions: Our findings demonstrate that employing an abdominal compression device may reduce CIT, abdominal compression, and postural change but have no impact on patient comfort.

Association of Vitamin D Receptor Gene Polymorphisms with Prostate Cancer Risk in the Pakistani Population

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.

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 %.

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.

Control of the Saturation Temperature in Magnetic Heating by Using Polyethylene-glycol-coated Rod-shaped Nickel-ferrite (NiFe2O4) Nanoparticles

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.

Numerical analysis of magnetic flux leakage for defect characterization in reinforcing steel using permanent magnets

Yousaf, Jamal(자말 유사프),Lee, Changkye(이창계),Yee, Jurng-Jae(이정재),Kee, Seong-Hoon(기성훈) 대한건축학회 2022 대한건축학회 학술발표대회 논문집 Vol.42 No.2