Buckling analysis of sandwich beam rested on elastic foundation and subjected to varying axial in-plane loads

Mostafa A. Hamed,Salwa A Mohamed,Mohamed A. Eltaher 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.1

The current paper illustrates the effect of in-plane varying compressive force on critical buckling loads and buckling modes of sandwich composite laminated beam rested on elastic foundation. To generalize a proposed model, unified higher order shear deformation beam theories are exploited through analysis; those satisfy the parabolic variation of shear across the thickness. Therefore, there is no need for shear correction factor. Winkler and Pasternak elastic foundations are presented to consider the effect of any elastic medium surrounding beam structure. The Hamilton’s principle is proposed to derive the equilibrium equations of unified sandwich composite laminated beams. Differential quadrature numerical method (DQNM) is used to discretize the differential equilibrium equations in spatial direction. After that, eigenvalue problem is solved to obtain the buckling loads and associated mode shapes. The proposed model is validated with previous published works and good matching is observed. The numerical results are carried out to show effects of axial load functions, lamination thicknesses, orthotropy and elastic foundation constants on the buckling loads and mode shapes of sandwich composite beam. This model is important in designing of aircrafts and ships when non-uniform compressive load and shear loading is dominated.

Microbial colonization of sacral nerve stimulators pseudo-capsule: A single institution experience

Mostafa M. Mostafa,Mohamed Kamel,Ayman Mahdy 대한비뇨의학회 2023 Investigative and Clinical Urology Vol.64 No.5

Purpose: To evaluate the incidence and type of microbial colonization of the pseudo-capsule (PC) that forms around sacral nerve stimulators (SNS) and consequently the significance of surgical excision of this PC at time of SNS revision or removal. Materials and Methods: A cohort of 31 patients who underwent SNS revision or removal from January 2018 to June 2021 were retrospectively reviewed. The baseline demographics, rate and type of PC microbial colonization and development of SNS insertion site infection were reported. Results: A cohort of 31 patients who underwent “InterStim device (Medtronic)” revision or removal were included. The majority were females (93.5%). The most common indication for SNS insertion was refractory overactive bladder (67.7%). Nine patients (29.0%) underwent SNS revision due to malfunctional device, and 9 patients had SNS removal for the need of MRI procedures. Four patients (12.9%) had positive tissue culture growing Coryneform bacillus (50.0%), Cutibacterium acnes (25.0%) and Pseudomonas aeruginosa (25.0%). Conclusions: PC colonization was uncommon at the time of SNS explant. However, more research is needed to better understand the role of PC-positive culture in increasing the risk of SNS device infections if strict adherence to sterile techniques is adopted.

Ductile damage prediction of AA 5754 sheet during cold forming condition

Mohamed Amer,Mostafa Shazly,Mohamed Mohamed,Abdel Aziz Hegazy 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10

Aluminium sheet parts manufactured by cold-forming processes are subjected to ductile damage due to the plastic deformation. Tool design based on the experience and failure prediction using simple criteria in sheet metal forming can cause high cost of material scrap and tools modifications. Consequently, the ability to predict ductile damage gives full control of the forming process. This work was conducted to evaluate the predictive capability of different damage models for AA 5754 under cold forming condition. The models are calibrated using published tensile and forming limit diagram data for AA 5754. A set of experimental cup tests for AA 5754 sheet were conducted to validate the selected models. An FE model was developed to simulate the cup test process using LS-DYNA software. The selected models used were the Johnson-Cook, continuum damage model (CDM), Gurson model and the generalized incremental stress state-dependent model (GISSMO) model. The experimental results of the cup tests were compared with the simulation results from different damage models concluding that the Gissmo model was able to show a good agreement with the experimental results.

Synthesis and Antimicrobial Activity of Some New 1-Alkyl-2-alkylthio-1,2,4-triazolobenzimidazole Derivatives

Mohamed, Bahaa Gamal,Hussein, Mostafa Ahmed,Abdel-Alim, Abdel-Alim Mohamed,Hashem, Mohammed The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.1

Some new derivatives of 1,2,4-triazolo[2,3-a]benzimidazoles were synthesized through the reaction of 1,2-diaminobenzimidazole with carbon disulfide. The resulting 1,2,4-triazolo-[2,3a]benzimidazole-2-thione intermediate was reacted with one equivalent of alkyl halides to give the corresponding 2-alkylthio derivatives, which were further alkylated through the reaction with another one equivalent of different alkyl halides to afford the target compounds; 1-alkyl-2alkylthio-1,2,4-traizolo[2,3-a]benzimidazoles. On the other hand, the 1,2-disubstituted derivatives with two identical alkyl substituents were prepared by the reaction of 1,2,4-triazolo[2,3-a]benzimidazole-2-thione with two equivalents of the alkyl halides. The structures of the new compounds were assigned by spectral and elemental methods of analyses. The synthesized compounds were tested for their antibacterial and antifungal activities. Most of the tested compounds proved comparable results with those of ampicillin and fluconazole reference drugs. The study indicated that, the antibacterial as well as the antifungal activities of the test compounds were improved with increase in the bulkiness of the introduced alkyl groups. Also, some active antibacterial compounds were tested for their antimycobacterial activity. All the test compounds showed equipotent antitubercular activity as that of INH as a reference drug.

MAP: A Balanced Energy Consumption Routing Protocol for Wireless Sensor Networks

( Mohamed Mostafa A. Azim ) 한국정보처리학회 2010 Journal of information processing systems Vol.6 No.3

Network lifetime is a critical issue in Wireless Sensor Networks (WSNs). In which, a large number of sensor nodes communicate together to perform a predetermined sensing task. In such networks, the network life time depends mainly on the lifetime of the sensor nodes constituting the network. Therefore, it is essential to balance the energy consumption among all sensor nodes to ensure the network connectivity. In this paper, we propose an energy-efficient data routing protocol for wireless sensor networks. Contrary to the protocol proposed in [6], that always selects the path with minimum hop count to the base station, our proposed routing protocol may choose a longer path that will provide better distribution of the energy consumption among the sensor nodes. Simulation results indicate clearly that compared to the routing protocol proposed in [6], our proposed protocol evenly distributes the energy consumption among the network nodes thus maximizing the network life time.

Hemodynamic effects of norepinephrine versus phenylephrine infusion for prophylaxis against spinal anesthesia-induced hypotension in the elderly population undergoing hip fracture surgery: a randomized controlled trial

Mostafa Maha,Hasanin Ahmed,Mostafa Mahmoud,Taha Mai Y,Elsayad Mohamed,Haggag Fatma Alzahraa,Taalab Omar,Rady Ashraf,Abdelhamid Bassant 대한마취통증의학회 2021 Korean Journal of Anesthesiology Vol.74 No.4

Background: Elderly population are at increased risk of spinal anesthesia-induced hypotension increasing their risk for postoperative morbidity and mortality. This study aimed to compare the hemodynamic effects of prophylactic infusion of norepinephrine (NE) versus phenylephrine (PE) in elderly patients undergoing hip fracture surgery under spinal anesthesia. Methods: Elderly patients scheduled for hip fracture surgery were randomized to receive either NE infusion (8 µg/min) (NE group, n = 31) or PE infusion (100 µg/min) (PE group, n = 31) after spinal anesthesia. Outcomes included mean heart rate, mean blood pressure, cardiac output, incidence of spinal anesthesia-induced hypotension, incidence of bradycardia, and incidence of hypertension. Results: Sixty-two patients with a mean age of 71 ± 6 years were included in the final analysis (31 patients in each group). The NE group showed a higher mean heart rate and cardiac output than the PE group. The NE group had a lower incidence of reactive bradycardia (10% vs. 36%, P = 0.03) and hypertension (3% vs. 36%, P = 0.003) than the PE group. No study participant developed hypotension, and the mean blood pressure was comparable between the two groups. Conclusions: Both NE and PE infusions effectively prevented spinal anesthesia-induced hypotension in elderly patients undergoing hip fracture surgery. However, NE provided more hemodynamic stability than PE; maintaining the heart rate, higher cardiac output, less reactive bradycardia, and hypertension.

Comparative study of levobupivacaine and bupivacaine for bilateral maxillary nerve block during pediatric primary cleft palate surgery: a randomized double-blind controlled study

Mohamed F. Mostafa,Ragaa Herdan,Mohamed Elshazly 대한마취통증의학회 2018 Korean Journal of Anesthesiology Vol.71 No.2

Background: Cleft lip and palate are common major congenital anomalies. Cleft palate (CP) repair causes pain and needs large doses of intravenous opioids. The risk of postoperative airway obstruction or respiratory depression is high, requiring continuous and vigilant monitoring. The primary outcome was to evaluate the efficacy of using different local anesthetics during bilateral maxillary nerve block (MNB) with general anesthesia on quality of recovery after primary CP repair. We hypothesized that levobupivacaine would be better than bupivacaine. Also, to investigate the potency of bilateral MNB in improving quality of postoperative analgesia. Methods: Sixty children undergoing primary CP repair surgery were enrolled in the study. Combined general anesthesia and regional bilateral MNB were used for all patients. Group L (n = 30): children received 0.15 ml/kg of 0.2% levobupivacaine, while in Group B (n = 30): children received 0.15 ml/kg of 0.2% bupivacaine. Results: Face, Legs, Activity, Cry, and Consolability pain score readings were 0 score in 7 cases of the Group L and 10 cases of Group B, 1 score in 14 cases of the Group L and 12 cases of Group B, and 2 score in 9 cases of the Group L and 8 cases of Group B. We found no statistically significant difference between the two study groups as regarding pain score or serious complications. Conclusions: Levobupivacaine is as effective and safe as bupivacaine to be used for MNB block with a lower incidence of complications. Bilateral suprazygomatic MNB is an effective, easy, and safe method for pain relief in children undergoing primary cleft palate repair surgeries.

Effect of Sewage Wastewater Treated by Nostoc muscorum and Anabaena subcylindrica on the Growth of Zea mays and Phaseolus vulgaris

Mohamed El Anwar Hosain Osman,Wagih Abd EL Fatah EI Shouny,Mostafa Mohamed El Sheekh,Eman Wahba El Sayed El Gammal 한국식물학회 2006 Journal of Plant Biology Vol.49 No.5

Plasmonic-Multichromatic Sensor for Gallic Acid Assay Utilizing Ag-Coated Au Nanobipyramids

Mostafa Mohamed H.,Shaban Samy M.,Hafez Eslam,Shin Jihoon,김동환 한국바이오칩학회 2023 BioChip Journal Vol.17 No.4

Gallic acid (GA) is known for its valuable properties as an antioxidant, anti-cancer, and anti-mutagenic compound, making its detection in foods and drugs of paramount importance. In this research, we introduce a novel multichromatic sensor for GA detection, which employs the controlled growth of silver nanoparticles (AgNPs) on the surface of gold nanobipyramids (AuNBPs). The sensor exploits GA's capability to reduce AgNO 3, resulting in the growth of AgNPs and a subsequent blue shift of localized surface plasmon resonance (LSPR) as large as 195 nm. This unique multicolor response ranges from light gray to green, blue–violet, and pink, allowing for distinctive visual identifi cation of GA concentrations. The sensor's performance demonstrates a wide dynamic range of 0–175 μM, and a detection limit (LOD) as low as 0.139 μM. Notably, the applicability of this multichromic plasmonic probe was successfully tested for GA assay in both Black and Green tea, showcasing highly satisfactory recovery effi ciencies and affi rming its potential for food quality control applications. The presented multichromatic sensor off ers a promising approach for rapid and sensitive GA detection in various food and pharmaceutical products, enhancing the monitoring and assessment of GA content for improved product quality and safety.

Early assessment of aspiration risk in acute stroke by fiberoptic endoscopy in critically ill patients

Mohamed Saad Abdelaziz Elsyaad,Akram Muhammad Fayed,Mohamed Mostafa Abdel Salam Megahed,Nesrine Hazem Hamouda,Ahmed Moustafa Elmenshawy 대한중환자의학회 2022 Acute and Critical Care Vol.37 No.3

Background: Fiberoptic endoscopic evaluation of swallowing (FEES) has been recommended to assess aspiration in stroke. This study aimed to determine the diagnostic and prognostic roles of FEES in the early assessment of aspiration, intensive care unit (ICU) stay and mortality in acute stroke patients.Methods: Fifty-two patients with acute stroke admitted to the Alexandria Main University Hospital were included. Complete examinations and assessment of aspiration using the 8-point penetration-aspiration scale (PAS) with FEES protocol were performed.Results: The patients were classified into three groups: normal with no or low risk of aspiration (n=15, 27.3%; PAS level 1), low to moderate risk (n=8, 14.5%; PAS level 2–4), and high risk (n=32, 58.2%; PAS ≥5). There was high incidence of aspiration pneumonia, prolonged ICU stay, and mortality in both moderate- and high-risk groups (P=0.001, P<0.001, and P<0.001, respectively). The PAS score predicted aspiration pneumonia (hospital-acquired pneumonia) with sensitivity and specificity of 80.0% and 76.0%, respectively (negative predictive value [NPV], 76.0; positive predictive value [PPV], 80.0; 95% confidence interval [CI], 0.706–0.940) and mortality with sensitivity and specificity of 88.46% and 68.97% (NPV, 87.0; PPV, 71.9; 95% CI, 0.749–0.951). The PAS score could predict the length of ICU stay with sensitivity and specificity of 70.21% and 87.50, respectively (NPV, 33.3; PPV, 97.1; 95% CI, 0.605–0.906).Conclusions: The standard FEES protocol using PAS score is a useful tool to assess aspiration in acute stroke patients and could be used to predict length of ICU stay and mortality.