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      • KCI등재

        Characterization of alanyl aminopeptidase from insecticide resistant and susceptible strains of Musca domestica L.

        Sohail AHMED1,Waqas WAKIL,David MANTLE,Richard M. WILKINS,권용정 한국곤충학회 2008 Entomological Research Vol.38 No.3

        To investigate the high activity of intracellular proteases in insecticide resistant strains of Musca domestica L., purification by anion-exchange chromatography and gel filtration of one of the enzymes, alanyl aminopeptidase (Ala AP), in three strains of Musca domestica was carried out. The fractions collected by gel filtration of soluble homogenates of the three strains (571ab, 17bb and Cooper) showed a single peak of Ala AP activity. Partially purified Ala AP of the three strains showed high activity at pH 7.5. The presence or absence of Ca2+ in the assay medium did not produce any difference in activity of Ala AP in the 571ab and Cooper strains, but there was a significant difference in the 17bb strain. The activity of Ala AP in all three strains was essentially unaltered in the presence of inhibitors of serine (PMSF), cysteine (E-64) proteases and carboxypeptidases (pepstatin). Ala AP hydrolyzed alanine amino methylcoumarin (Ala-AMC) maximally, followed by phenyl alanine amino methylcoumarin (Phe-AMC), leucyl amino methylcoumarin (Leu-AMC) and ornithine amino methylcoumarin (Orn-AMC). Ala AP from the three strains showed differential activity towards various substrates. The comparison of alanyl aminopeptidase’'s activity from different sources is discussed.

      • KCI등재후보

        A modified trans-anconeus approach to facilitate fixation of a posterior radial head fracture: a cadaveric feasibility study

        Ahmed Mohamed Desouky(Ahmed Mohamed Desouky ),Ahmed Naeem Atiyya(Ahmed Naeem Atiyya ),Mohamed Elbishbishi(Mohamed Elbishbishi ),Marwa Mohamed El Sawy(Marwa Mohamed El Sawy ) 대한해부학회 2023 Anatomy & Cell Biology Vol.56 No.1

        Fixation of radial head fracture with minimally invasive posterior approach remains a significant challenge. The aim of this study was to determine the feasibility of trans-anconeus posterior elbow approach and to observe lateral ulnar collateral ligament (LUCL) in extended elbows. This cadaveric study was performed in twenty upper limbs of fresh fixed adult male cadavers. An oblique incision was made in the middle segment of anconeus until the lateral ligament complex and the joint capsule had been revealed. A deep dissection was explored to observe the anatomical relationship of the LUCL to the anconeus. Measurements of the LUCL were recorded while the elbow was fully extended. The mean distance between the edge of the radial head and the proximal insertion of the LUCL was 13.3 mm (11.5–16.2 mm); the mean distance between the edge of the radial head and the distal insertion of the LUCL was 20.9 mm (19.2–23.4 mm); the distance between the edge of the radial head and the distal edge of the annular ligament was 11.2 mm (8.22–11.7 mm). By estimate correlation of the previous measurements, the direct and accessible way to expose the posterolateral articular capsule of the elbow joint was through a window in medial 2/3 of the middle segment of anconeus muscle. These trans-anconeus approach is useful. It provides good visualization, facilitates applying the implants, and lessens the risk of radial nerve injury. Awareness of the anatomy is mandatory to avoid injury of LUCL.

      • SCOPUS

        The Interplay between Comprehensive Use of Performance Management Systems and Corporate Financial and Non-Financial Performance: Evidence from Saudi Arabia

        Ahmed Abdullah Saad AL-DHUBAIBI(Ahmed Abdullah Saad AL-DHUBAIBI ) 한국유통과학회 2023 The Journal of Asian Finance, Economics and Busine Vol.10 No.1

        A significant body of prior research on performance management systems (PMSs) either explains the components and the design of the systems or investigates the link between particular system/s and organizational functions, capabilities, or performance. In contrast, this study investigates the comprehensive use of PMSs and relates them to corporate financial and non-financial performance. Further, this study examines whether the association between PMSs and performance varies between industries or is moderated by the size of the company. Data was collected using a questionnaire that was sent to companies from different industries operating in Riyadh province, where the most important businesses in Saudi Arabia are located. A total of 152 usable responses were received. The results of this study revealed that companies use a variety of PMSs at a balanced level. The extent of each category of PMS use is associated with the extent of other PMS categories’ use. However, the larger the company, the more PMSs it uses. Importantly, the results showed a positive and significant association between PMSs’ extent of use and both financial and non-financial performance. This association was minimally moderated by the company size and industry for specific categories of PMSs and performance.

      • Static bending response of axially randomly oriented functionally graded carbon nanotubes reinforced composite nanobeams

        Ahmed Amine Daikh,Ahmed Drai,Mohamed Ouejdi Belarbi,Mohammed Sid Ahmed Houari,Benoumer Aour,Mohamed A. Eltaher,Norhan A. Mohamed Techno-Press 2024 Advances in nano research Vol.16 No.3

        In this work, an analytical model employing a new higher-order shear deformation beam theory is utilized to investigate the bending behavior of axially randomly oriented functionally graded carbon nanotubes reinforced composite nanobeams. A modified continuum nonlocal strain gradient theory is employed to incorporate both microstructural effects and geometric nano-scale length scales. The extended rule of mixture, along with molecular dynamics simulations, is used to assess the equivalent mechanical properties of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beams. Carbon nanotube reinforcements are randomly distributed axially along the length of the beam. The equilibrium equations, accompanied by nonclassical boundary conditions, are formulated, and Navier's procedure is used to solve the resulting differential equation, yielding the response of the nanobeam under various mechanical loadings, including uniform, linear, and sinusoidal loads. Numerical analysis is conducted to examine the influence of inhomogeneity parameters, geometric parameters, types of loading, as well as nonlocal and length scale parameters on the deflections and stresses of axially functionally graded carbon nanotubes reinforced composite (AFG CNTRC) nanobeams. The results indicate that, in contrast to the nonlocal parameter, the beam stiffness is increased by both the CNTs volume fraction and the length-scale parameter. The presented model is applicable for designing and analyzing microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) constructed from carbon nanotubes reinforced composite nanobeams.

      • KCI등재

        Static analysis of multilayer nonlocal strain gradient nanobeam reinforced by carbon nanotubes

        Ahmed Amine Daikh,Ahmed Drai,Mohamed Sid Ahmed Houari,Mohamed A. Eltaher 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.6

        This article presents a comprehensive static analysis of simply supported cross-ply carbon nanotubes reinforced composite (CNTRC) laminated nanobeams under various loading profiles. The nonlocal strain gradient constitutive relation is exploited to present the size-dependence of nano-scale. New higher shear deformation beam theory with hyperbolic function is proposed to satisfy the zero-shear effect at boundaries and parabolic variation through the thickness. Carbon nanotubes (CNTs), as the reinforced elements, are distributed through the beam thickness with different distribution functions, which are, uniform distribution (UD-CNTRC), V- distribution (FG-V CNTRC), O- distribution (FG-O CNTRC) and X- distribution (FG-X CNTRC). The equilibrium equations are derived, and Fourier series function are used to solve the obtained differential equation and get the response of nanobeam under uniform, linear or sinusoidal mechanical loadings. Numerical results are obtained to present influences of CNTs reinforcement patterns, composite laminate structure, nonlocal parameter, length scale parameter, geometric parameters on center deflection ad stresses of CNTRC laminated nanobeams. The proposed model is effective in analysis and design of composite structure ranging from macro-scale to nano-scale.

      • Poster Session : PS 0590 ; Critical Care Medicine ; Early CT Scan to Detect Anastomotic Leak: Is It Worth It?

        ( Ahmed Ahmed ),( Ayan Banerjea ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

        Background: Early diagnosis of anastomotic leakage after colorectal surgery and adequate treatment is crucial to reduce both morbidity and mortality. Computed tomography(CT) scanning is the diagnostic investigation of preference, but its role is questionable in the early postoperative days. The accuracy of CT scanning in the early postoperative period within the fi rst few days after surgery may even be lower when compared to a CT scan more than a week after surgery. Methods: 185 patients underwent 1 or more bowel anastomosis during the period of 6 months. A prospective data sheet was updated regularly with post op morbidity and mortality. The type of anastomosis, timing of postoperative CT scan, diagnosis of leakage and accuracy of the CT scan in detecting it were all recorded. Results: 54 patients (29%) had CT scans post operatively, of whom 48 happened during the same admission with a mean time of 5±3 days postoperatively.A total of 9 patients had their fi rst CT scan onday 3 or earlier postoperatively with one leak detected on that. The mean time for diagnosing a leak was 14±8 days. Conclusions: Timely and correct diagnosis and treatment of anastomotic leakage after bowel surgery remains to be a major challenge.Clinical decision remains of utmost importance in the individual patient and should therefore not depend on one specifi c clinical or additional diagnostic factor.

      • KCI등재

        A Buck-Boost Converter-Based Bipolar Pulse Generator

        Ahmed A. Elserougi,Ahmed M. Massoud,Shehab Ahmed 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

        This paper presents a buck-boost converter-based bipolar pulse generator, which is able to generate bipolar exponential pulses across a resistive load. The concept of the proposed approach depends on operating the involved buck-boost converters in discontinuous current conduction mode with high-voltage gain and enhanced efficiency. A full design of the pulse generator and its passive components is presented to ensure generating the pulses with the desired specifications (rise time, pulse width, and pulse magnitude) for a given load resistance and input dc voltage. In case of moderate pulsed output voltages (i.e. few of kV), one module of the presented bipolar generator can be employed. While in case of high-voltage pulsed output, multi-module version can be employed, where each module is fed from an isolated dc source and their outputs are connected in series. Simulation models for the proposed approach are built to elucidate their performance in case of one-module as well as multi-module based generator. Finally, a scaled-down prototype for one-module of buck-boost converter-based bipolar pulse generator is implemented to validate the proposed concept.

      • Bending of axially functionally graded carbon nanotubes reinforced composite nanobeams

        Ahmed Drai,Ahmed Amine Daikh,Mohamed Oujedi Belarbi,Mohammed Sid Ahmed Houari,Benoumer Aour,Amin Hamdi,Mohamed A. Eltaher Techno-Press 2023 Advances in nano research Vol.14 No.3

        This work presents a modified analytical model for the bending behavior of axially functionally graded (AFG) carbon nanotubes reinforced composite (CNTRC) nanobeams. New higher order shear deformation beam theory is exploited to satisfy parabolic variation of shear through thickness direction and zero shears at the bottom and top surfaces.A Modified continuum nonlocal strain gradient theoryis employed to include the microstructure and the geometrical nano-size length scales. The extended rule of the mixture and the molecular dynamics simulations are exploited to evaluate the equivalent mechanical properties of FG-CNTRC beams. Carbon nanotubes reinforcements are distributed axially through the beam length direction with a new power graded function with two parameters. The equilibrium equations are derived with associated nonclassical boundary conditions, and Navier's procedure are used to solve the obtained differential equation and get the response of nanobeam under uniform, linear, or sinusoidal mechanical loadings. Numerical results are carried out to investigate the impact of inhomogeneity parameters, geometrical parameters, loadings type, nonlocal and length scale parameters on deflections and stresses of the AFG CNTRC nanobeams. The proposed model can be used in the design and analysis of MEMS and NEMS systems fabricated from carbon nanotubes reinforced composite nanobeam.

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