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Shahzada Qamar Hussain,Kumar Mallem,Muhammad Ali Khan,Muhammad Quddamah Khokhar,Youngseok Lee,박진주,이경수,김영국,조은철,조영현,이준신 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.1
Excellent surface passivation and carrier selective contact formed by the metal oxide induced junctions is required for future high efficiency silicon solar cells. Due to wide optical bandgap and high work function of molybdenum oxide (MoOx,x < 3) films envisioned as a superior hole selective layer in organic light emitting diodes and photovoltaics applications. We have studied the influence of ultrathin MoOx layer, as a hole-selective contact for high efficiency of silicon heterojunction (SHJ) solar cell. MoOx films can be deposited by atomic layer deposition, magnetron sputtering and thermal evaporation. Due to higher work function of MoOx films, a potential barrier can develop against electrons while it supports the hole carriers flow hence current density of SHJ solar cells can be enhanced. A summary of single layer and solar cell characteristics of MoOx layer for the application of carrier selective contact and dopant-free asymmetric heterocontact (DASH) solar cells is reported.
Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Tufail, Muhammad,Shahzada, Khan,Gencturk, Bora,Wei, Jianqiang Korea Concrete Institute 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to $650^{\circ}C$ for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete
Muhammad Tufail,Khan Shahzada,Bora Gencturk,Jianqiang Wei 한국콘크리트학회 2017 International Journal of Concrete Structures and M Vol.11 No.1
Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650 『C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.
Anam Naseer,Muhammad Mumtaz,Muhammad Raffi,Izhar Ahmad,Sabih D. Khan,Rana I. Shakoor,Shaista Shahzada 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.2
With the recent developments in the millimeter and sub-millimeter wave instruments and devices, there is a need to developelectromagnetic (EM) wave absorbing materials in these frequency bands for applications like electromagnetic interferencecontrol, electromagnetic compatibility, etc. In this work, carbon nanofi bers (CNF) were uniformly dispersed in a blend ofpoly(methyl methacrylate), polyvinylidene fl uoride and cyanoacrylate for air spray coating a fi lm on the cellulosic substrates. The samples were characterized for evaluation of their structure, morphology, electrical and EM absorption properties in0.15–1.2 THz range by X-ray diff raction, fi eld emission electron microscopy, I–V measurements and terahertz time domainspectroscopy. These coatings can conveniently be applied to the material surfaces by conventional air spray painting method,which makes this technique cost-eff ective as well as easy to deploy in various applications. The electrical conductivityenhancement in the samples has been attributed to the formation of conducting network by uniform distribution of CNFs inthe insulating polymer matrix. As a result, the shielding eff ectiveness (SE) has been observed to improve with the increasein CNF’s loading in the polymer matrix. The SE is also a function of frequency, which is attributed to the increase in theskin depth. A SE of 20 dB has been estimated in these samples for the frequencies 1 THz and higher, which is of signifi cantimportance for the use of this technique in practical applications.
Larik, Fayaz Ali,Faisal, Muhammad,Saeed, Aamer,Channar, Pervaiz Ali,Korabecny, Jan,Jabeen, Farukh,Mahar, Ihsan Ali,Kazi, Mehar Ali,Abbas, Qamar,Murtaza, Ghulam,Khan, Gul Shahzada,Hassan, Mubashir,Seo, Academic Press 2019 Bioorganic chemistry Vol.86 No.-
<P><B>Abstract</B></P> <P>The increasing resistance of pathogens to common antibiotics, as well as the need to control urease activity to improve the yield of soil nitrogen fertilization in agricultural applications, has stimulated the development of novel classes of molecules that target urease as an enzyme. In this context, the newly developed compounds on the basis of 1-heptanoyl-3-arylthiourea family were evaluated for Jack bean urease enzyme inhibition activity to validate their role as potent inhibitors of this enzyme. 1-Heptanoyl-3-arylthioureas were obtained in excellent yield and characterized through spectral and elemental analysis. All the compounds displayed remarkable potency against urease inhibition as compared to thiourea standard. It was found that novel compounds fulfill the criteria of drug-likeness by obeying Lipinski’s rule of five. Particularly compound <B>4a</B> and <B>4c</B> can serve as lead molecules in 4D (drug designing discovery and development). Kinetic mechanism and molecular docking studies also carried out to delineate the mode of inhibition and binding affinity of the molecules.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new family of 1-heptanoyl-3-arylthioureas (<B>4a-4j</B>) was synthesized in excellent yield. </LI> <LI> The synthesized 1-heptanoyl-3-arylthiourea family were evaluated for Jack bean urease enzyme inhibition activity. </LI> <LI> Particularly compound <B>4a</B> and <B>4c</B> can serve as lead molecules in 4D (drug designing discovery and development). </LI> <LI> Kinetic mechanism and molecular docking studies also carried out to delineate the mode of inhibition and binding affinity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Shah Zada,Saleem Raza,Sikandar Khan,Arshad Iqbal,Zhang Kai,Aftab Ahmad,Midrar Ullah,Mohib Kakar,Pengcheng Fu,Haifeng Dong,Zhang Xueji 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-
Heavy metals and other organic pollutants are the hazardous materials causing soil and water pollution,hence, bioremediation of these components is a matter of concern for environmental biotechnologists. Twenty one microalgal and cyanobacterial strains were evaluated for removal of copper from aqueoussolutions and soil containing 10 ppm copper. 5 out of 21 strains have shown comparatively higher toleranceto copper stress. The biosorption capabilities of all the five strains were assessed using techniqueslike ultraviolet (UV) spectrophotometers, scanning electron microscope (SEM), inductively coupledplasma mass spectrometry (ICP-MS), and confocal Microscopy. It was found that the five selected strainscould grow normally upon incubating with 20 ppm of Cu. Copper removal efficiencies of these microalgae(S. obliquus, A. braunii, C. fusca, L. JSC-1 and C. saccharophila in water were 99.9, 99.3, 97, 96.7, and 96%,while for soil was 73, 75, 71, 70, 68%, respectively. A minor leakage of nucleic acid and protein weredetected with time. Furthermore, no any visible morphological changes were observed after six daysof treatment, while minor changes were noticed after 12 days in water, and severe morphological deformationsoccurred after 24 days of bioremediation in soil. Our findings reveal that the selected microalgalstrains have high potential for Cu bioremediation at certain concentration for 12 days exposure fromwater and 24 from soil.