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Finite Element Analysis of a 2-Span Pedestrian Bridge Collapse due to Trucks Collision
Amin H. Almasri,Rajai Z. Alrousan,Al-harith Manasrah 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6
The collapse of a 2-span steel pedestrian bridges caused by a truck collision is investigated and studied in detail using a Nonlinear Finite Element program. Typical bridge widely used in Jordan is studied and modeled under vehicle collision using one dimensional beam finite element in order to minimize analysis time due to the dynamic nature of the problem. Truck collision with the bridge is simulated at different speeds and locations of collisions using dynamic explicit finite element scheme with material nonlinearity taken into account. Energy absorption of bridge is investigated through principle of energy conservation, where truck kinetic energy is assumed to be stored in the bridge as strain energy. Weak failure points in the bridges were identified, and modifications are proposed in order to strengthen the bridge structure and prevent total collapse. The proposed design modifications on bridge structure were successful in allowing the bridge to fail locally rather than globally and expected to help in saving lives.
New leads for DPP IV inhibition: structure-based pharmacophore mapping and virtual screening study
Ihab M. Almasri,Mutasem O. Taha,Mohammad K. Mohammad 대한약학회 2013 Archives of Pharmacal Research Vol.36 No.11
Dipeptidyl peptidase IV (DPP IV) is an attractivetarget for the development of new antidiabetic drugs. DPP IV inhibitors improve glycemic control by preventingthe rapid inactivation of the incretin hormones; glucagonlikepeptide 1 (GLP-1) and glucose-dependent insulinotropicpeptide. In the current study, virtual screening, using2D and 3D filters implemented in a hierarchical cascade,was employed to identify new DPP IV inhibitors. Cocrystallizedligands, with potent DPP IV-inhibitory activities,were utilized to generate structure-based pharmacophoremodels using DS Visualizer software. The derivedpharmacophore maps were validated using in-house builtdatabase containing active and inactive DPP IV inhibitors. Subsequently, the optimum validated pharmacophoremodel was used as a search query against two 3D-databases(NCI and in-house built drug databases). Further hit filtrationwas carried out employing 2D virtual filters based onLipinski’s rule of 5; number of rotatable bonds and otherphysicochemical filters. 3D filter using high-throughputmolecular docking was also applied. As a result, 5 novelDPP IV inhibitors were discovered as potential lead compoundsand later confirmed via in vitro bioassay.
Alghyamah Abdulaziz A.,Haider Sajjad,Khalil Uzma,Khan Rawaiz,Haider Adnan,Almasry Waheed A.,Ihsan Rida,Tahira Perveen,Wazeer Irfan,Chafidz Achmad 한국물리학회 2022 Current Applied Physics Vol.40 No.-
This work describes the synthesis of GO, rGO and their nanocomposites with PEO. GO and rGO were prepared by the modified Hummers method and in-situ reduction of GO utilizing green reductant L (+) Ascorbic acid. The nanocomposites were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Thermogravimetric Analysis (TGA), and Universal Testing Machine (UTM). FT-IR and XRD confirmed the synthesis of GO and rGO. FE-SEM confirmed the uniformly exfoliated GO and rGO nanosheets in the polymer matrix. Hydrogen bonding was the main interaction mechanism for GO with PEO while no interaction was detected by FT-IR for rGO. Enhanced thermal stability was observed for both GO/PEO and rGO/PEO nanocomposites. The mechanical analysis showed an increase in Young’s modulus, tensile strength, and elongation at break for GO/PEO nanocomposites, which is attributed to the homogeneous dispersion and hydrophilic hydrogen bonding interaction of GO with PEO.
Epoxylite Influence on Field Electron Emission Properties of Tungsten and Carbon Fiber Tips
Alnawasreh, Shady S,Al-Qudah, Ala'a M,Madanat, Mazen A,Bani Ali, Emad S,Almasri, Ayman M,Mousa, Marwan S Korean Society of Microscopy 2016 Applied microscopy Vol.46 No.4
This investigation deals with the process of field electron emission from composite microemitters. Tested emitters consisted of a tungsten or carbon-fiber core, coated with a dielectric material. Two coating materials were used: (1) Clark Electromedical Instruments Epoxylite resin and (2) Epidian 6 Epoxy resin (based on bisphenol A). Various properties of these emitters were measured, including the current-voltage characteristics, which are presented as Fowler-Nordheim plots, and the corresponding electron emission images. A field electron microscope with a tip (cathode) to screen (anode) distance of 10 mm was used to electrically characterize the emitters. Measurements were carried out under ultra-high vacuum conditions with a base pressure of $10^{-6}$ Pascal ($10^{-8}$ mbar).