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Tensile Strength of Squeeze Cast Carbon Fibers Reinforced Al-Si Matrix Composites

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Journal of Minerals and Materials Characterization and Engineering 2011年第2期10卷 127-141页

作者： ahmed A. Moosa Kahtan K. Al-Khazraji Osama S. Muhammed Department of Production Engineering and Metallurgy University of Technology Baghdad Materials Engineering Department University of Technology Baghdad Iraq.

Squeeze casting is a pressure casting process in which molten metal is solidified under the direct action of a pressure. In squeeze casting, the relationship between the process parameters and the quality of the squeeze cast components is not fully understood;thus the need for more studies in this area of technology for better understanding of the process. The present work encompasses studying the effect of direct squeeze casting process parameters on the production of (3 and 20%) volume fraction carbon fibers (CF) reinforced Al-Si matrix composites. The evaluated process parameters are squeeze pressure in the range (7.5-53) MPa, die preheating temperature (100,200,300)°C, pouring temperature (700,780)°C, squeeze time (30 sec.), and delay time (5 sec.). The results show a good distribution of the matrix between the carbon fibers when using higher casting pressures of (38 and 53MPa), lower pouring temperature of (700°C) and lower die temperatures of (100 and 200°C). Increasing the carbon fibers volume fraction had led to increasing the tensile strength. The using of higher pressure (53MPa), lower pouring temperature (700°C), and lower die temperature (200°C) have increased the ultimate tensile strength of the CF/Al-Si composites to (183MPa) when compared to that of the nonreinforced alloy which was (168MPa) because of the increased bonding, decreased shrinkage defects and fibers degradation based on the results. Also, UTS is increased at P=38MPa, Tp=700°C, and Td=100°C.

关键词： Tensile Strength Squeeze Cast Carbon Fibers

Design of Environmental Biosensor Based on Photonic Crystal Fiber with Bends Using Finite Element Method

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Optics and Photonics Journal 2015年第3期5卷 69-78页

作者： Shyqyri Haxha ahmed Teyeb Fathi Abdel Malek Emmanuel Kofi Akowuah Iyad Dayoub Department of Computer Science and Technology University of Bedfordshire Luton UK ESPRIT School of Engineering and Technology Ariana Tunisia National Institute of Applied Sciences and Technology The University of Carthage Tunis Tunisia IEMN DOAE University of Valenciennes Valenciennes France

In this paper, a biosensor based on photonic crystal fiber (PCF) is proposed and designed using Full-Vectorial Finite Element Method (FVFEM). The proposed PCF sensor consists of three concentric circles surrounding the core. The key optical sensor characteristics such as sensitivity, the field profiles and real part of the refractive index of the proposed PCF structure are investigated by employing the FVFEM. The proposed sensor can be deployed for environmental sensing when the PCF active region is filled with either analytes such as liquids or gas. By careful selection of the design parameters such as the radius of the sensing circle, the diameter of air holes in the core region and hole to hole spacing, Λ, the sensitivity analytes is determined. Our simulation results show that, the electric field distribution is primary localized in the third concentric circle with a radius of 16 μm. Effects of PCF bending on the sensitivity is also studied and reported.

关键词： Biosensors Photonic Crystal Fibres Sensor Nanosensor Finite Element Method

Laparoscopic Rectopexy;Is It Useful for Persistent Rectal Prolapse in Children?

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Surgical Science 2014年第3期5卷 128-133页

作者： Medhat M. Ibrahim Mohammed Abd El Razik ahmed M. Abdelkader General Surgery Unite RCMC Yanbu Industrial City KSA Pediatric Surgery Unit Faculty of Medicine Al-Azhar University Nasr City Cairo Egypt

Introduction: Rectal prolapse is a relatively common, usually self-limiting illness in children. Peak incidence is between 1 and 3 years. The intervention is required for the persistent rectal prolapse (PRP). Only scanty experience is available with laparoscopic rectopexy in children. There is no available work using both mesh and suture laparoscopic rectopexy in literature. This work is unique that it presents our clinical experience with both mesh and suture laparoscopic rectopexy in children. This is a prospective clinical study for the outcome of laparoscopic rectopexy (LRP) by both mesh and suture technique in children with persistent rectal prolapse (PRP). Materials and Methods: Fourteen cases of PRP were managed with LRP from February 2008 to August 2012. Results: Of the 14 children, 10 (71.42%) were males and 4 (28.57%) were females. Male to female ratio was 2:1. The mean age of presentation was 5 years (range 3 - 8 years). The presenting complaints were mass descending per rectum along with bleeding per rectum lasting from 1 to 3 years. All had rectal prolapse of 5 - 7 cm in length. 12 out of 14 children had recurrence even after sclerotherapy before referral to laparoscopic rectpexy. The mean duration of surgery was 30 minutes (range 20 - 60 minutes). No intraoperative complications were reported;only one case got constipation and was managed conservatively and no recurrence. Conclusion: LRP is safe, feasible in children and gives satisfactory results after failure of all conservative even sclerotherapy injection.

关键词： Rectal Prolapse Laparoscopy Rectopexy

The Effect of Incorporation of Ferrite Nano-particles on Compressive Strength and Re-sistivity of Self-Compacting Concrete

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Open Journal of Civil Engineering 2015年第1期5卷 131-138页

作者： Mohamed A. ahmed Yehia A. Hassanean Kamal A. Assaf Moustafa A. Shawkey Materials Science Lab. (1) Physics Department Faculty of Science Cairo University Giza Egypt Department of Civil Engineering Assiut University Assiut Egypt

Mn-Ferrite nanoparticles were prepared using citrate auto combustion method. The prepared sample was characterized by X-ray diffraction (XRD), HRTEM and BET to measure the particle diameter and the surface area of the prepared sample. The data of XRD clarified that the sample was formed in single phase spinel structure without any extra peaks indicating non-existence of any secondary phase. The HRTEM micrograph indicated that the particles were in an agglomerated state due to the absence of surfactant and high magnetic properties of Mn-Ferrite nanoparticles. The mechanical properties were measured at different ratios of nano-Ferrite to concrete. The obtained values of mercury intrusion porosimetry (MIP) indicated that the addition of Mn-Ferrite nanoparticles increased the compressive strength and decreased the total intrusion volume. This was due to the rapid consuming of Ca(OH)2 which was formed during hydration of Portland cement especially at early ages due to the high reactivity of MnFe2O4 nanoparticles. Moreover, MnFe2O4 nanoparticles recovered the particle packing density of the blended cement, leading to a reduced volume of pores in the cement paste.

关键词： Compressive Strength Concrete XRD HRTEM Reactivity

Non-anthracycline chemotherapy associated with a poor outcome in elderly Egyptian patients with diffuse large B-cell non-Hodgkin lymphoma

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Journal of Cancer Metastasis and Treatment 2015年第1期1卷 76-83页

作者： ahmed A.Zeeneldin Yasser A.Sallam Ayman A.Gaber Amgad A.Shaheen Department of Medical Oncology National Cancer InstituteCairo University12622 CairoEgypt.

Aim:Rituximab plus cyclophosphamide,doxorubicin,vincristine,and prednisone(CHOP)is the standard treatment for patients with diffuse large B-cell non-Hodgkin lymphoma(DLBCNHL).Nevertheless,anthracyclines are contraindicated for some patients,*** dysfunction,severe hepatic dysfunction,***,this study assessed the effectiveness of non-anthracycline chemotherapy regimen cyclophosphamide,vincristine,and prednisone(CVP)in elderly DLBCNHL patients *** standard ***:This retrospective study included 418 DLBCNHL patients diagnosed between 2003 and 2006 and followed until March *** this period of time,rituximab was not available for all patients,particularly for patients older than 60 ***:CHOP and CVP were administered to 351(84%)and 67(16%)patients,*** age and comorbidities,particularly cardiovascular and diabetes mellitus,were independent determinants for not receiving *** received more courses of CHOP treatment than that of CVP(6 vs.3 courses;P<0.001)and developed more toxicities(48.4%vs.23.9%;P<0.001),particularly fatigue,alopecia,and gastrointestinal tract *** response rate was higher in CHOP than in CVP(69.9%vs.29.9%;P<0.001).Moreover,early death was significantly higher in CVP group of patients than in CHOP(43.3%vs.8.6%;P<0.001).After a median follow-up of 71 months,the median overall survival(OS)and event-free survival(EFS)were signifi cantly better in CHOP than in CVP(49.5 vs.3.7 months and 32.2 vs.3.5 months;P<0.001 for both,respectively).Older age,poor age-adjusted International Prognostic Index scores,not receiving CHOP or consolidative radiotherapy were independent predictors of poor OS and ***:Use of the CVP regime to treat DLBCNHL patients who were unfit to the standard CHOP treatment was associated with lower remission rates and poorer EFS and OS in this group of patients.

关键词： Non-Hodgkin’s lymphoma diffuse large B-cell anthracycline chemotherapy treatment

The Impact of Implementing the International Convention on the Control of Harmful Anti-fouling Systems in Ships （AFS Convention） on the Marine Environment

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Journal of Shipping and Ocean Engineering 2016年第1期6卷 57-63页

作者： Capt. ahmed Saad Hassan Noufal Capt. Mohamed Hussein Nassar Hassan Arab Academy for Science Technology & Maritime Transport Alexandria 21913 Egypt

Marine fouling is the settlement and growth of a variety of marine organisms, such as bacteria, diatoms, protozoa and algae spores on structures immersed in seawater, such as ship＇s hulls, navigation buoys, and sonar equipment. Anti-fouling refers to material or systems used to prevent the accumulation of biological material on submerged surfaces. Bio-fouling results in higher fuel consumption and can also facilitate the transport of harmful NIS （Non-Indigenous Species）. Antifouling technologies incorporating biocides （e.g., Tributyltin） have been developed to prevent fouling. Their widespread use, however, raised concerns about their toxic effects on marine communities. The AFS Convention （International Convention on the Control of Harmful Anti-fouling Systems in Ships） is a 2001 IMO （International Maritime Organization） treaty, whereby states agree to ban the use of harmful anti-fouling paints and other anti-fouling systems that contain harmful substances. Particularly, the use of the organotinTributyltin is prohibited, since leaching of that chemical from the hulls of ships has been shown to cause deleterious effects on some sea creatures. Although the AFS Convention has entered into force, its full implementation has not yet been appropriately achieved. Most of the ratifying States have delegated the Classification Society to inspect their ships to ensure the implementation of the provisions of the Convention. Since painting ships takes place in dry docks, the full control falls in the hands of Classification Societies.

关键词： Anti-fouling environment Tributyltin organotins biocide.

Analysing the Impact of Roof Obstructions on Daylight Levels in Atrium Buildings:Physical Scale Model Measurements under Real Sky Conditions

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Analysing the Impact of Roof Obstructions on Daylight Levels...

Trends and risk factors for opioid administration for non-emergent lower back pain

International Conference on Environmental Science and Technology（ICEST 2011）

作者： Julitta Yunus Sabarinah Sh Ahmad Azni Zain-ahmed Faculty of Architecture Planning & SurveyingUniversiti Teknologi MARA Research Management Institute Universiti Teknologi MARA Centre of Research in Innovation and Sustainable Energy Institute of ScienceUniversiti Teknologi MARA

This paper describes the effects of atrium roof forms and internal structural obstructions（roof truss） upon the daylight levels in atrium buildings under tropical real sky conditions（intermediate sky）.Daylight measurements were made inside one atrium model with four different types of structured roof forms（flat,pitched,pyramidal-gridded and south facing saw-tooth）.Results showed intermediate skies revealed a generally linear relationship and had a good degree of correlation with the overall reduction of daylight *** obstructions tend to reduce about 55% of light transmittance with similar pattern of losses for all roof *** was observed that the internal obstructions of roof created relatively constant attenuation of the daylight compared with the clear unobstructed *** structured flat roof had the least impact on roof transmittance,and generally all four roof forms had similar patterns of light *** measurements also confirmed that as the sky brightened,the daylight availability became more significant as the inclined glazing and internal obstructions tend to reflect or splay sunlight away or into the *** analysis showed significant differences between the effects of roof forms and internal roof obstructions（roof truss） on daylight levels that will support the authors’ future project of using innovative glazing panels as roof glazing material.

关键词： Daylight Atrium Roof Transmittance Scale Model Real Sky Conditions

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World Journal of Orthopedics 2021年第9期12卷 700-709页

作者： Chukwuweike U Gwam ahmed K Emara Noor Chughtai Sameer Javed T David Luo Kevin Y Wang Morad Chughtai Tadhg O'Gara Johannes F Plate Department of Orthopedic Surgery Wake Forest School of MedicineWinston-SalemNC 27157United States Department of Orthopedic Surgery Cleveland Clinic FoundationClevelandOH 44195United States Department of Orthopaedic Surgery University of Pittsburgh5200 Centre AvenueSuite 415PittsburghPA 15232USA

BACKGROUND Non-emergent low-back pain(LBP)is one of the most prevalent presenting complaints to the emergency department(ED)and has been shown to contribute to overcrowding in the ED as well as diverting attention away from more serious *** has been an increasing focus in current literature regarding ED admission and opioid prescriptions for general complaints of pain,however,there is limited data concerning the trends over the last decade in ED admissions for non-emergent LBP as well as any subsequent opioid prescriptions by the ED for this *** To determine trends in non-emergent ED visits for back pain;annual trends in opioid administration for patients presenting to the ED for back pain;and factors associated with receiving an opioid-based medication for non-emergent LBP in the ED METHODS Patients presenting to the ED for non-emergent LBP from 2010 to 2017 were retrospectively identified from the National Hospital Ambulatory Medical Care Survey ***“year”variable was transformed to two-year intervals,and a weighted survey analysis was conducted utilizing the weighted variables to generate incidence *** statistics were used to assess differences in count data,and logistic regression was performed to identify factors associated with patients being discharged from the ED with *** significance was set to a P value of *** Out of a total of 41658475 total ED visits,3.8%(7726)met our inclusion and exclusion *** was a decrease in the rates of non-emergent back pain to the ED from 4.05%of all cases during 2010 and 2011 to 3.56%during 2016 and *** most common opioids prescribed over the period included hydrocodone-based medications(49.1%)and tramadol-based medications(16.9),with the combination of all other opioid types contributing to 35.7%of total opioids *** significantly associated with being prescribed narcotics included age over 43.84-years-old,higher income,priva

关键词： Opioids Low back pain Emergency Department Spine Complications Trends

Kigelia africana Fruit:Constituents,Bioactivity, and Reflection on Composition Disparities

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World Journal of Traditional Chinese Medicine 2017年第4期3卷 1-6页

作者： ahmed Galal Osman Zulfiqar Ali Amar G.Chittiboyina lkhlas A.Khan National Center for Natural Products Research University of Mississippi Department of BioMolecular Sciences Division of Pharmacognosy School of PharmacyUniversity of Mississippi

Objective: Kigelia africana, a tropical tree, which has long been used in African traditional medicine. The objective of the current study has been identifying the constituents of K. africana and verifying its utilities in traditional medicine. Materials and Methods: The methanol extract of K. africana fruits was subjected to chromatographic fractionation utilizing different techniques. The methanol extract together with the isolated compounds were tested for their bioactivities in a series of cell-based assays. Results: The current work led to isolation and characterization of nine constituents including iridoid glycosides, phenylpropanoid derivatives, and a eucommiol derivative. The hexanes extract caused inhibition of the opportunistic yeast; Cryptococcus neoformans Pinh. The chloroform extract exhibited substantial antileishmanial activity of Leishmania donovani. Verminoside(1) showed weak inhibition of the CB1, CB2, and Kappa opioid receptors. Compound 4 exhibited weak inhibition of the Kappa and Mu opioid receptors. The hexanes and the chloroform extracts of K. africana exhibited inhibitory activity against the pathogenic parasite Trypanosoma brucei. The ethyl acetate extract showed the same activity. Conclusions: This is the first report on the isolation of coniferyl 4-0-(3-D-glucopyranoside(7), a eucommiol derivative(crescentin IV)(6), and 6-feruloylcatalpol(4) from the genus Kigelia. It is also the first report on the separation of ajugol(2), catalpol(3), and specioside(5) from the fruits of K. africana. Revision of the^1 H and ^(13)C-NMR spectra of 6-feruloylcatalop(4) and 6-p-hydroxycinnamoylcatalpol(5, specioside) is described. Further, the results of the in vitro assays corroborate the traditional utility of this plant in medicine.

关键词： Anticryptoccocal antileishmanial cannabinoid receptors Kigelia africana opioid receptors