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Microstructures and Mechanical Properties of Al-Zn-Sn Bearing Alloys for High Performance Applications

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World Journal of Engineering and Technology 2021年第3期9卷 637-652页

作者： Nermin Ali Abdelhakim rizk mostafa shalaby Metal Physics Laboratory Researsh Department of Physics Faculty of Science Mansoura University Mansoura Egypt

The mechanical behavior and indentation creep of Al-20 wt% Zn bearing alloy has been modified with adding 0.2 wt%, 0.5 wt%, 1 wt%, 1.5 wt% Sn. These bearing alloys were prepared by melt spinning technique. The scanning electron microscopy (SEM) was used to study the morphology of the melt spun alloys and x-ray diffractometer (XRD) for the identification of the phases pre- sent in these melt-spun bearing alloys. The results show that the structure of Al80-x-Zn20-SnX (X = 0.2%, 0.5%, 1% and 1.5%) bearing alloys is characterized by the presence of α-Al of FCC structure and S

关键词： Bearing Alloys Microstructure Mechanical Properties Microhardness Indentation Creep

A Study of Structure, Thermal and Mechanical Properties of Free Machining Al-Zn-Sn-Bi Alloys Rapidly Solidified from Molten State

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World Journal of Engineering and Technology 2018年第3期6卷 637-650页

作者： Nermin Ali Abdelhakim rizk mostafa shalaby Mustafa Kamal Metal Physics Laboratory Physics Department Faculty of Science Mansoura University Mansoura Egypt

The objective of our study is to investigate the effect of rapid solidification technology using melt spun process from melt on environmentally free machining Al-0.1Zn alloys with tin-bismuth as free machining constituents. The main purpose of rapid solidification from melt is to have a high strength and thermal stability. Structural and thermal properties have been investigated by x-ray diffraction (XRD), scanning electron microscope (SEM) and differential scanning calorimetry (DSC) techniques. Tensile test machine is used to study the mechanical properties such as ultimate tensile strength, elastic constants, yield strength and critical shear stress for free machining alloys. We find?the best free machining aluminum alloy that has excellent machinability qualities is Al-0.1Zn-0.5Sn-0.54Bi melt spun alloy because it offers excellent mechanical properties. The highest values of tensile strength (431.5 MPa), yield strength (393.9 MPa), fracture strength (431.6 Mpa), toughness (15.8 × 106?J/m3) generated from Al-0.1Zn-0.5Sn-0.54Bi alloy to meet the needs of free machining aluminum alloy applications.

关键词： Free Machining Aluminum Alloys Structural Analysis Mechanical Behavior Microhardness Micro Indentation Creep

Ultrafast hydrogen bond dynamics of liquid water revealed by terahertz-induced transient birefringence

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Light(Science & Applications) 2020年第1期9卷 707-716页

作者： Hang Zhao Yong Tan Liangliang Zhang Rui Zhang mostafa shalaby Cunlin Zhang Yuejin Zhao Xi-Cheng Zhang Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Beijing Advanced Innovation Center for Imaging Technology and Key Laboratory of Terahertz Optoelectronics(MoE) Department of PhysicsCapital Normal UniversityBeijing 100048China Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055China The Institute of Optics University of RochesterRochesterNY 14627USA

The fundamental properties of water molecules,such as their molecular polarizability,have not yet been *** hydrogen bond network is generally considered to play an important role in the thermodynamic properties of *** terahertz(THz)Kerr effect technique,as a novel tool,is expected to be useful in exploring the low-frequency molecular dynamics of liquid ***,we use an intense and ultrabroadband THz pulse(peak electric field strength of 14.9 MV/cm,centre frequency of 3.9 THz,and bandwidth of 1–10 THz)to resonantly excite intermolecular modes of liquid *** THz field-induced transient birefringence signals are observed in a free-flowing water *** propose a hydrogen bond harmonic oscillator model associated with the dielectric susceptibility and combine it with the Lorentz dynamic equation to investigate the intermolecular structure and dynamics of liquid *** mainly decompose the bipolar signals into a positive signal caused by hydrogen bond stretching vibration and a negative signal caused by hydrogen bond bending vibration,indicating that the polarizability perturbation of water presents competing contributions under bending and stretching conditions.A Kerr coefficient equation related to the intermolecular modes of water is *** ultrafast intermolecular hydrogen bond dynamics of water revealed by an ultrabroadband THz pump pulse can provide further insights into the transient structure of liquid water corresponding to the pertinent modes.

关键词： transient dynamics liquid

Aqueous extracts of microalgae exhibit antioxidant and anticancer activities

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Asian Pacific Journal of Tropical Biomedicine 2012年第8期2卷 608-615页

作者： Sanaa MM Shanab Soha SM mostafa Emad A shalaby Ghada I Mahmoud Botany Department Faculty of ScienceCairo University Microbiology Department SoilsWater and Environment Research InstituteAgrientural Research Center Biochemistry Department Faculty of AgricultureCairo University

Objective:To investigate the antioxidant and anticancer activities of aqueous extracts of nine microalgal ***:Variable percentages of major secondary metabolites(total phenolic content,terpenoids and alkaloids) as well as phycobiliprotein pigments(phycocyanin, allophycocyanin and phycoerythrin) in the aqueous algal extracts were *** activity of the algal extracts was performed using 2,2 diphenyl-1-picrylhydrazyl(DPPH) test and 2,2'azino-bis(ethylbenzthiazoline-6-sulfonic acid(ABTS.) radical cation *** efficiency of the algal water extracts was investigated against Ehrlich Ascites Carcinoma cell(EACC) and Human hepatocellular cancer cell line(HepG2).Results:Antioxidant activity of the algal extracts was performed using DPPH test and ABTS.^+ radical cation assays which revealed 30.1-72.4%and 32.0-75.9%*** efficiency of the algal water extracts was investigated against Ehdich Ascites Carcinoma Cell(EACC) and Human Hepatocellular cancer cell line(HepG2) with an activity ranged 87.25%and 89.4%*** the promising cyanobacteria species;Nostoc muscorum and Oscillatoria *** nitrogen stress conditions(increasing and decreasing nitrate content of the normal BG11 medium,1.5 g/L),increased nitrate concentration(3,6 and 9 g/L) led to a remarkable increase in phycobilin pigments followed by an increase in both antioxidant and anticancer activities in both cyanobacterial *** the decreased nitrate concentration(0.75,0.37 and 0.0 g/L) induced an obvious decrease in phycobilin pigments with complete absence of allophycocyanin in case of Oscillatoria ***:Nitrogen starvation(0.00 g/L nitrate) induced an increase and comparable antioxidant and anticancer activities to those cultured in the highest nitrate content.

关键词： Microalgae Antioxidant Anticancer Nitrogen starvation Cyanobacteria

Phytochemical, antioxidant and hepatoprotective effects of different fractions of Moringa oleifera leaves methanol extract against liver injury in animal model

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Asian Pacific Journal of Tropical Medicine 2018年第7期11卷 423-429页

作者： Attia H.Atta Soad M.Nasr Abduljalil H.Almaweri Doaa Sedky Amany M.Mohamed Hassan M.Desouky mostafa A.shalaby Department of Pharmacology Faculty of Veterinary Medicine Cairo University Department of Parasitology & Animal Diseases National Research Centre(Egypt) Department of Animal Reproduction and Artificial Insemination National Research Centre(Egypt)

Objective: To evaluate the potential antioxidant and hepatoprotective effects of n-hexane, dichloromethane(DCM), ethyl acetate(EtOAc), n-butanol and aqueous fractions of Moringa oleifera(M. oleifera) leaves methanol extract against carbon tetrachloride(CCl_4)-induced liver injury in rats. Methods: These fractions were prepared from the M. oleifera leaves methanol extract by solubilization in water and partitioning in n-hexane, EtOAc, DCM and n-butanol. Their phyto-components were identified by GC-MS analysis. The in vitro antioxidant effect of these fractions was carried out by assessment of 1,1-diphenyl-2-picrylhydrazyl scavenging activity. A total of 40 Sprague Dawley rats were allocated into 8 equal groups: group 1 given olive oil(1 m L/kg ***.), group 2 injected with CCl_4, group 3 to 7 administered with n-hexane, DCM, EtOAc, n-butanol and aqueous fractions, respectively after CCl_4, group 8 administered with silymarin after CCl_4. The activities of aspartate aminotransferase, alanine aminotransferase, and the levels of total cholesterol, triglycerides, glucose, total proteins and albumin in serum were determined spectrophotometrically. Glutathione reduced, lipid peroxide by-products levels, glutathione-s-transferase and catalase enzyme activities in the liver homogenate were determined by spectrophotometer. Liver specimens were also examined for histopathological alterations under light microscope. Results: The GCMS analysis of different fractions of the M. oleifera leaves methanol extract revealed that n-hexane, DCM, EtOAc, n-butanol, and aqueous fractions contained 17, 22, 23, 19 and 32 compounds, respectively. The percent and the molecular structure of each component in each fraction were identified. The n-butanol and EtOAc fractions exhibited the strongest in vitro antioxidant activity against 1,1-diphenyl-2-picrylhydrazyl. CCl_4 significantly decreased glutathione reduced and total proteins concentration and glutathione-s-transferase and catalase activiti

关键词： Hepatoprotective Antioxidants Moringa oleifera Fractions Phytochemical

Interaction of insulin with prokinetic drugs in STZ-induced diabetic mice

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World Journal of Gastrointestinal Pharmacology and Therapeutics 2013年第2期4卷 28-38页

作者： Mohamed A Fouad shalaby Hekma A Abd El Latif mostafa E El Sayed Department of Pharmacology Kahira Pharmaceutical CompanyCairo 793Egypt Faculty of Pharmacy Cairo UniversityCairo 11562Egypt

AIM:To study the possible interactions of metoclopramide,domperidone and erythromycin in streptozotocin-induced diabetic mice treated with insulin by various ***:Effects of the individual as well as combined drugs were studied in diabetic mice via estimation of the blood glucose and serum insulin levels,small intestinal transit(SIT),gastric emptying(GE),xylose absorption and glucose tolerance *** were given insulin 2 IU/kg s.c.,metoclopramide 20 mg/kg p.o.,domperidone 20 mg/kg *** erythromycin 6 mg/kg *** and in *** were also normal and diabetic control *** first set of experiments was carried out to investigate the subchronic effect on blood glucose and serum insulin levels in diabetic mice of one week of daily dose administration of the tested drugs individually as well as the combination of insulin with each prokinetic *** other five sets of experiments were carried out to investigate the acute effect of a single dose of each drug individually and in combination on blood glucose and serum insulin levels,SIT,GE,oral xylose absorption and glucose tolerance ***:The study included the prokinetic drugs metoclopramide(20 mg/kg),domperidone(20 mg/kg) and erythromycin(6 mg/kg),as well as insulin(2 IU/kg),which was individually effective in decreasing SIT,enhancing GE and increasing xylose absorption significantly in diabetic *** tended to decrease blood glucose level and increase serum insulin level after 1 wk of daily administration in diabetic *** potentiated the effect of insulin on blood glucose level and serum insulin level whereas other prokinetic agents failed to do so after repeated dose administration in diabetic *** or erythromycin in combination with insulin significantly decreased SIT,in diabetic mice,to lower levels than with insulin *** of prokinetic drugs along with insulin antagonized the action of insulin on xylose abs

关键词： Streptozotocin Gastrointestinal motility Insulin Prokinetic drugs Intestinal absorption

Preventive strategies for anastomotic leakage after colorectal resections: A review

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World Journal of Meta-Analysis 2019年第8期7卷 389-398页

作者： mostafa shalaby Waleed Thabet Mosaad Morshed Mohamed Farid Pierpaolo Sileri Department of General Surgery Mansoura University Hospitals Mansoura University Dakahliya Mansoura 35516 Egypt Department of General Surgery UOC C Policlinico Tor Vergata Hospital University of Rome Tor Vergata Rome 00133 Italy

Anastomosis is a crucial step in radical cancer surgery. Despite being a daily practice in gastrointestinal surgery, anastomotic leakage (AL) stands as a frequent postoperative complication. Because of increased morbidity, mortality, combined with longer hospital stay, the rate of re-intervention, and poor oncological outcomes, AL is considered the most feared and life-threatening complication after colorectal resections. Furthermore, poor functional outcomes with a higher rate of a permeant stoma in 56% of patients this could negatively affect the patient’s quality of life. This a narrative review which will cover intraoperative anastomotic integrity assessment and preventive measures in order to reduce AL. Although the most important prerequisites for the creation of anastomosis is well-perfused and tension-free anastomosis, surgeons have proposed several preventive measures, which were assumed to reduce the incidence of AL, including antibiotic prophylaxis, intraoperative air leak test, omental pedicle flap, defunctioning stoma, pelvic drain insertion, stapled anastomosis, and general surgical technique. However, lack of clear evidence of which preventive measures is superior over the other combined with the fact that the decision remains based on the surgeon’s choice. Despite the advances in surgical techniques, AL remains a serious health problem associated with increased morbidity, mortality with additional cost. Many preventative measures were employed with no clear evidence supporting the superiority of stapled anastomosis over hand-Sewn anastomosis, coating of the anastomosis, or pelvic drain. Defunctioning stoma, when justified it could decrease the leakage-related complications and the incidence of reoperation. MBP combined with oral antibiotics still recommended.

关键词： Anastomotic leakage Colorectal Resection Anastomosis Cancer Anastomotic disruption