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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.

      • KCI등재

        Artificial intelligence can help individualize Wilms tumor treatment by predicting tumor response to preoperative chemotherapy

        Ahmed Nashat,Ahmed Alksas,Rasha T. Aboulelkheir,Ahmed Elmahdy,Sherry M. Khater,Hossam M. Balaha,Israa Sharaby,Mohamed Shehata,Mohammed Ghazal,Salama Abd El-Wadoud,Ayman El-Baz,Ahmed Mosbah,Ahmed Abdel 대한비뇨의학회 2025 Investigative and Clinical Urology Vol.66 No.1

        Purpose: To create a computer-aided prediction (CAP) system to predict Wilms tumor (WT) responsiveness to preoperative chemotherapy (PC) using pre-therapy contrast-enhanced computed tomography (CECT). Materials and Methods: A single-center database was reviewed for children <18 years diagnosed with WT and received PC between 2001 and 2021. Patients were excluded if pre- and post-PC CECT were not retrievable. According to the Response Evaluation Criteria in Solid Tumors criteria, volumetric response was considered favorable if PC resulted in ≥30% tumor volume reduction. Histological response was considered favorable if post-nephrectomy specimens had ≥66% necrosis. Four steps were used to create the prediction model: tumor delineation; extraction of shape, texture and functionality-based features; integration of the extracted features and selection of the prediction model with the highest diagnostic performance. K-fold cross-validation allowed the presentation of all data in the training and testing phases. Results: A total of 63 tumors in 54 patients were used to train and test the prediction model. Patients were treated with 4–8 weeks of vincristine/actinomycin-D combination. Favorable volumetric and histologic responses were achieved in 46 tumors (73.0%) and 38 tumors (60.3%), respectively. Among machine learning classifiers, support vector machine had the best diagnostic performance with an accuracy, sensitivity, and specificity of 95.24%, 95.65%, and 94.12% for volumetric and 84.13%, 89.47%, 88% for histologic response prediction. Conclusions: Based on pre-therapy CECT, CAP systems can help identify WT that are less likely to respond to PC with excellent accuracy. These tumors can be offered upfront surgery, avoiding the cons of PC.

      • 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.

      • KCI등재

        Fundamental Output Voltage Enhancement of Half-Bridge Voltage Source Inverter with Low DC-link Capacitance

        Ahmed Elserougi,Ahmed Massoud,Shehab Ahmed 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.1

        Conventionally, in order to reduce the ac components of the dc-link capacitors of the two-level Half-Bridge Voltage Source Inverter (HB-VSI), high dc-link capacitances are required. This necessitates the employment of short-lifetime and bulky electrolytic capacitors. In this paper, an analysis for the performance of low dc-link capacitances-based HB-VSI is presented to elucidate its ability to generate an enhanced fundamental output voltage magnitude without increasing the voltage rating of the involved switches. This feature is constrained by the load displacement factor. The introduced enhancement is due to the ac components of the capacitors’ voltages. The presented approach can be employed for multi-phase systems through using multi single-phase HB-VSI(s). Mathematical analysis of the proposed approach is presented in this paper. To ensure a successful operation of the proposed approach, a closed loop current controller is examined. An expression for the critical dc-link capacitance, which is the lowest dc-link capacitance that can be employed for unipolar capacitors’ voltages, is derived. Finally, simulation and experimental results are presented to validate the proposed claims.

      • 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 추계학술발표논문집 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.

      • KCI등재SCOPUS

        Review : Nanoparticles as Alternative Pesticides: Concept, Manufacturing and Activities

        ( Ahmed I S Ahmed ),( Youn Su Lee ) 한국균학회 2015 韓國菌學會誌 Vol.43 No.4

        Nanotechnology, which has become an important area of science, has caused an enormous developmental revolution in many fields. In the last two decades researchers have focused on overcoming the obstacles encountered during the preparation of nanoparticles. This article highlights the nanotechnology, along with a brief description of the manufacturing, concepts and activities of nanoparticles as alternative pesticides against plant pathogens, some methods for evaluation of nanoparticles against phytopathogens in vitro and in vivo, and explains the importance of some common nanoparticle types used in agricultural applications and plant pathology.

      • 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.

      • KCI등재

        Minimally Invasive Transforaminal Lumbar Interbody Fusion for the Surgical Management of Post-Discectomy Syndrome

        Ahmed Bahaa Al Din AlShazli,Ashraf Yassin Amer,Ahmed Maher Sultan,Ahmed Samir Barakat,Wael Koptan,Yasser ElMiligui,Hesham Shaker 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.2

        Study Design: This was a prospective case series of 30 patients with post-discectomy syndrome with an average of 18 months of follow-up (level IV). Purpose: The efficacy of post-discectomy syndrome managed by minimally invasive surgery transforaminal lumbar interbody fusion (MIS-TLIF) was evaluated. Overview of Literature: In post-discectomy syndrome wherein conservative treatment had failed, the best surgical treatment modality still remains controversial. Methods: Patients were functionally assessed using the Visual Analog Scale (VAS) for low back pain (LBP) and leg pain (LP) and Oswestry Disability Index (ODI). Radiological fusion was confirmed with plain X-rays and when indicated with computed tomography scan at 12 months postoperatively. A total of 30 patients with 37 operated at lumbar levels with failed discectomy surgery who met our inclusion criteria were treated with MIS-TLIF. Results: The ODI of all patients showed significant improvement from a mean of 73.78% preoperatively to 16.67% at 1 month and 14.13% at 12 months postoperatively. The preoperative LBP VAS score (mean, 4.37) showed a significant decrease (p<0.001) to 1.90 at 1 month and 1.10 at 12 months. Preoperative LP VAS score of limb pain averaged 7.53 and showed a significant (p<0.001) decrease to 3.47 at 1 month and 1.10 at 12 months. All patients attained radiological fusion at 12 months. Conclusions: MIS-TILF constitutes a valid and effective treatment option for patients with post-discectomy syndrome.

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