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Mechanical, thermal and swelling properties of cellulose nanocrystals/PVA nanocomposites membranes
Zaib Jahan,Muhammad Bilal Khan Niazi,Øyvind Weiby Gregersen 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.57 No.-
Cellulose nanocrystals (CNC) have strong reinforcing properties when incorporated in a compatiblepolymer matrix. The study was conducted to investigate the effect of addition of different proportions ofCNC on the mechanical, thermal and swelling properties of poly(vinyl alcohol) (PVA) nanocompositemembranes for biogas separation. The incorporation of CNC in PVA increased the crystallinity at allinvestigated relative humidities. No apparent trend is observed for mechanical properties for drymembranes (0% RH) with addition of CNC in PVA matrix. However, at 93% RH the elastic modulusincreased 25 times with addition of CNC compared to pure PVA membranes. Moreover, tensile strengthalso showed twice the values at 53% RH and 93% RH after the addition of CNC. Membranes containinghigher CNC content absorbed 9% less moisture. Swelling, thermal and mechanical properties indicate agood potential of CNC/PVA nanocomposite membranes for use in CO2 separation membranes.
Sangchul Park,Qammer Zaib,Hung-Suck Park 대한환경공학회 2021 Environmental Engineering Research Vol.26 No.2
The effects of environmental factors (temperature, humidity, and airflow) on gross calorific value (GCV) and proximate analysis of low grade coal were systematically investigated. The factorial experiments were conducted according to the statistical experimental design. The results were empirically modeled, statistically tested, and experimentally verified to quantify the change in GCV and proximate analysis of coal directed by environmental factors. The GCV of the coal were most affected by the humidity followed by the temperature. The GCV was increased from 5,365 to 5,986 (kcal/kg) through the decrease in humidity from 80 to 29 (% R.H.) and increase in temperature from 28 to 36 (°C). This increase in GCV could be attributed to the decrease in moisture content of the coal from 16.2 to 7.1 (%). Also, the optimized environmental conditions were identified where GCV ≈ 6,000 kcal/kg of the coal could be obtained. This study can be helpful in (i) managing the variability in GCV of a coal at different places, environment, and weather conditions and, thereby, settling the disputes between buyers and sellers over its variability and (ii) in maintaining the optimum conditions to enhance the GCV of the low grade coal in the power plants.
Mechanical and thermal properties of carboxymethyl fibers (CMF)/PVA based nanocomposite membranes
Muhammad Bilal Khan Niazi,Zaib Jahan,Arooj Ahmed,Bushra Uzair,Ahmad Mukhtar,Øyvind Weiby Gregersen 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-
Carboxymethylfibers (CMF) of cellulose are renewable biopolymer and have shown strong reinforcingproperties when added to a compatible polymer matrix. The objective of this study was to investigate theeffect of CMF on the mechanical, thermal and swelling properties of polyvinyl alcohol (PVA) membranes. The PVA/CMF composite membranes with different proportions of CMF ranging from 1 wt.% to 6 wt.%were prepared by solution casting method. The membranes were characterized by SEM, TGA, XRD, FTIRand mechanical testing. The results revealed that at low CMF concentration composite membranesshowed homogenous dispersion of CMF in PVA matrix. The incorporation of CMF enhanced thecrystallinity of composite membranes with increase in relative humidity (RH). Furthermore, themechanical strength and moisture uptake of PVA/CMF nanocomposite membranes were enhanced afterinclusion of CMF. TGA and DSC results revealed that the addition of CMF has no significant impact on thethermal properties. PVA/CMF nanocomposite membranes showed good potential to be applied for gasseparation application particularly for CO2 capture.
Asam Farid,Perveiz Khalid,Khan Zaib Jadoon,Muhammad Asim Iqbal,James Small 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.5
This study describes a method of combining geostatistical analysis with geophysical inversion of 1D electrical resistivity data acquired in the Bannu Basin, northwestern Himalayas of Pakistan. The data has been integrated and broadened from single dimension resistivity data into a 2D model that can be fully visualized and interpreted in a spatial sense. By interpreting and calibrating the electrical resistivity curves with the lithologies and geophysical logs of boreholes, it has been possible to identify unique sedimentary accumulations that occur throughout the basin. Through the use of variogram modelling the spatial extent of these accumulations can be identified and associated with measured hydraulic properties. It has become possible to map the extents and facies of the alluvial systems of the Bannu Basin formed during periods of heightened tectonic activity. The coarser sediments are associated with higher levels of resistivity as measured in the electrical surveys, whereas the finer sediments exhibit characteristically lower resistivities. Thus, the zones of high and low resistivity values become indicative of sediments associated with alluvial fans and lacustrine environments, respectively. The sediments of alluvial fans show relatively low gamma ray levels and higher transmissivities, whereas those of the piedmont deposits as well as lacustrine and sandy plains tend to show medium to high gamma ray values and lower transmissivities. Gross transmissivities were estimated by studying regression relationships between transmissivities measured in boreholes and the apparent formation factors of sediments. These relationships indicate an exponential increase in transmissivity with increasing apparent formation factor. These trends suggest a contrast in transmissivities between alluvial fan and other environments where lacustrine and sandy plains are characterized by low transmissivities. These estimated transmissivities do not represent absolute values but are merely indicative of any high or low trends in transmissivity of sediments, throughout the basin.
Comparison of cavitation prediction for a centrifugal pump with or without volute casing
Xianwu Luo,Wei Wei,Bin Ji,Zaibing Pan,Wenchao Zhou,Hongyuan Xu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6
Cavitation may not only cause head and efficiency breakdown of hydraulic machines but also generate other unfavorable phenomena such as noise and vibration. Therefore, the accurate prediction of cavitation development is important for various pump applications. In this paper, two numerical models, namely, models A and B, are applied to simulate the turbulent cavitating flows inside a centrifugal pump to investigate the effect of calculation domain on the prediction accuracy of cavitation performance for hydraulic machines. Model A has a calculation domain with volute casing, whereas model B has a single blade-to-blade flow passage without volute casing. Steady simulations of cavitating flow in the pump have been conducted based on the shear stress transport k-ω turbulence model and the homogeneous cavitation model. Both models A and B predicted that the pump performance decreases with decreasing cavitation number. Experimental results show that model B can predict better the critical cavitation number at the best efficiency point compared with model A, which is the full flow passage model. Internal flow investigations indicate that an asymmetrical feature of cavitating flow exists when the calculation domain with volute casing is applied. The asymmetrical cavitation development in different blade-to-blade flow passages for model A results in an over-estimation of the decrease in pump performance because of the interaction between the impeller blade and the tongue of the volute casing. A simple calculation domain without volute casing is preferred for steady cavitation prediction in pumps rather than the full flow passage with volute casing because the former has better convergence, less resource requirements, and lower time consumption.
Maqsood, Muhammad Rizwan,Hanif, Muhammad,Rafiq, Muhammad,Saleem, Muhammad,Zaib, Sumera,Khan, Aftab Ahmed,Iqbal, Mazhar,Iqbal, Jamshed,Rama, Nasim Hasan,Seo, Sung-Yum,Lee, Ki-Hwan Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.12
The target compounds 6-11a-e were synthesized by condensing 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones 5a-f with various aromatic carboxylic acids in the presence of phosphorous oxychloride. The structures of newly synthesized compounds were characterized by IR, $^1H$ NMR, $^{13}C$ NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were screened for their antibacterial activity. Almost all the tested compounds were potent against four different strains of bacteria when compared with that of reference drug ciprofloxacin. Compounds 6c, 6e, 8d, 9b, 9e, 11a and 11b showed nearly equal or lower MIC values than standard drug, against all four tested bacterial strains but rest of the compounds showed excellent antibacterial activities.
Muhammad Rizwan Maqsood,Muhammad Hanif,Muhammad Rafiq,Muhammad Saleem,Sumera Zaib,Aftab Ahmed Khan,Mazhar Iqbal,Jamshed Iqbal,Nasim Hasan Rama,서승염,Ki-Hwan Lee 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.12
The target compounds 6-11a-e were synthesized by condensing 4-amino-5-aryl-3H-1,2,4-triazole-3-thiones 5a-f with various aromatic carboxylic acids in the presence of phosphorous oxychloride. The structures of newly synthesized compounds were characterized by IR, 1H NMR, 13C NMR, elemental analysis and mass spectrometric studies. All the synthesized compounds were screened for their antibacterial activity. Almost all the tested compounds were potent against four different strains of bacteria when compared with that of reference drug ciprofloxacin. Compounds 6c, 6e, 8d, 9b, 9e, 11a and 11b showed nearly equal or lower MIC values than standard drug, against all four tested bacterial strains but rest of the compounds showed excellent antibacterial activities.