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Precepitation and purification of amylase enzyme produced by streptomyces aureofaciens 77
Ibrahim, A.N.,Ahmed, F.H.,Ibrahim, M.M.K.,Arafa, M.A.I. The Pharmaceutical Society of Korea 1990 Archives of Pharmacal Research Vol.13 No.1
Precipitation and purification of amylase secreted by Streptomyces aureofaciens 77 in liquid inorganic salts-starch medium under the optimum conditions were carried out. Ammonium sulphate fractionation was used to precipitate amylase in cell free culture filtrate. (NH/sub 4/)/sub 2/ SO/sub 4/ at a concentration of 50-70% saturation gave the highest enzyme yield. The obtained precipitates were redissolved in phosphate buffer (pH 7.0) and subjected to dialysis. The dialyzed enzyme preparation was applied to DEAE-cellulose column chromatography which resulted in an increase of purification up to 59.48 fold. A further step of purification was done by applying the obtained purified sample to Sephadex-G200 column chromatography which resulted in ann increase of purification up to 73. 92 fold. The results clearly indicated that the isolated amylase from S. aureofaciens 77 was only on type.
Behaviour and design of guyed pre-stressed concrete poles under downbursts
Ahmed M. Ibrahim,Ashraf A. El Damatty 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.5
Pre-stressed concrete poles are among the supporting systems used to support transmission lines. It is essential to protect transmission line systems from harsh environmental attacks such as downburst wind events. Typically, these poles are designed to resist synoptic wind loading as current codes do not address high wind events in the form of downbursts. In the current study, the behavior of guyed pre-stressed concrete Transmission lines is studied under downburst loads. To the best of the authors’ knowledge, this study is the first investigation to assess the behaviour of guyed pre-stressed concrete poles under downburst events. Due to the localized nature of those events, identifying the critical locations and parameters leading to peak forces on the poles is a challenging task. To overcome this challenge, an in-house built numerical model is developed incorporating the following: (1) a three-dimensional downburst wind field previously developed and validated using computational fluid dynamics simulations; (2) a computationally efficient analytical technique previously developed and validated to predict the non-linear behaviour of the conductors including the effects of the pretension force, sagging, insulator’s stiffness and the non-uniform distribution of wind loads, and (3) a non-linear finite element model utilized to simulate the structural behaviour of the guyed pre-stressed concrete pole considering material nonlinearity. A parametric study is conducted by varying the downbursts locations relative to the guyed pole while considering three different span values. The results of this parametric study are utilized to identify critical downburst configurations leading to peak straining actions on the pole and the guys. This is followed by comparing the obtained critical load cases to new load cases proposed to ASCE-74 loading committee. A non-linear failure analysis is then conducted for the three considered guyed pre-stressed concrete transmission line systems to determine the downburst jet velocity at which the pole systems fail.
Ibrahim, Ahmed Mohamed,Zakhary, Siza Yacoub,Amin, Suzan Abdul Wanees The Korean Academy of Conservative Dentistry 2020 Restorative Dentistry & Endodontics Vol.45 No.3
Objectives: This study aimed to systematically review the pain and flare-up effects of calcium hydroxide (CH) as intracanal medication (ICM) in non-vital mature teeth. Materials and Methods: Electronic-databases searching for published and grey literature and manual searching were conducted. Only randomized clinical trials (RCTs) were included comparing CH to other ICMs in non-vital mature teeth. The risk of bias was assessed using the RoB 2.0 Cochrane tool. The main outcomes were pain and flare-up. Qualitative and quantitative analysis, wherever applicable, was performed. The certainty of evidence (CoE) was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). Results: Sixteen articles were included in 6 comparisons at different time points for different outcomes. CH reduced pain risk than no ICM within the 1-14-days interval (p < 0.05) and than triple-antibiotic paste within the first day (p < 0.05) and was similar to corticosteroid/antibiotics combination (p > 0.05). Chlorhexidine (CHX) or CH/CHX, however, reduced pain levels than CH alone (p < 0.05). CH showed higher flare-up risk than CHX (p < 0.05). CoE, however, ranged from very low to moderate. Conclusion: Most comparisons for different outcomes are based on very few studies, mostly low-powered, with an overall low CoE. Thus, the available evidence is considered insufficient to either support or refute CH effectiveness or to recommend one ICM over another. Therefore, further well-designed, larger RCTs are required.
Ahmed El Zayat,Mahmoud Abdelaziz,Ahmed Yousry,Ismail Ibrahim 한국심초음파학회 2021 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.29 No.4
BACKGROUND: Diastolic function has been reported to be impaired in many patients with coronary slow flow phenomenon (CSFP). CSFP has broad spectrum of clinical presentations, including non-ST elevation myocardial infarction (NSTEMI). We sought to study the short-term evolution of diastolic function in CSFP patients presenting with NSTEMI. METHODS: This study included 92 patients with CSFP and acute NSTEMI. Conventional echocardiography Doppler imaging and tissue Doppler echocardiography imaging were used to evaluate diastolic function during index NSTEMI and after 3 months. RESULTS: Mean age of study patients was 45.7 ± 6.8 years. The prevalence of diastolic dysfunction (DD) at baseline was 69 patients (75%) and 28 patients (30.4%) at 3 months, p < 0.001. Various diastolic function indices showed significant improvement from baseline to 3 months follow-up. E/Em was 17.32 ± 3.41 at baseline compared to 12.41 ± 5.58 at 3 months, p = 0.039. Septal e′ velocity was 5.67 ± 4.56 cm/s at baseline compared to 7.78 ± 3.22 cm/s at 3 months, p = 0.023. Medications used were not significantly different between those with improved versus unimproved DD. CONCLUSIONS: Diastolic function seems to improve over short-term follow-up in patients with CSFP presenting with NSTEMI. This could reflect a transient worsening during acute NSTEMI.
Storage Proteins of Diamondback Moth, Plutella xylostella:Purification and Expression Profile
Ahmed M. A. Ibrahim,Keewoo Lee,이혁수,Yonggyun Kim 한국응용곤충학회 2006 Journal of Asia-Pacific Entomology Vol.9 No.2
Storage proteins (SPs) were significantly detected in the hemolymph during the late instar larvae of diamondback moth, Plutella xylostella. These SPs were resolved into three proteins (SP1, SP2, and SP3) at 7% SDS-PAGE. Their apparent molecular sizes were around 80 kDa. SP1 was synthesized later than SP2 and SP3 during the development of the last instar. Total soluble proteins of last instar larvae were extracted and fractionated sequentially with ammonium sulfate, size-exclusion chromatography, and ion-exchange chromatography. The SPs were purified and their developmental expression was discussed.
Ahmed M.A. Ibrahim,Lamia A. ALRAKAN,Saleh Ahmed ALAIFAN 한국곤충학회 2015 Entomological Research Vol.45 No.5
Female mosquitoes feed on human blood, which can be collected to analyze human short tandem repeat (STR) sequences; these are specific to each human individual. Analysis of STRs might help in identification of a person found near a crime scene. Aedes aegypti and Culex pipiens mosquitoes fed on human blood were cultured at 18°C or 40°C (median temperature for summer and winter time in Riyadh governorate, Saudi Arabia) for 3, 6, 12, 24, 48 and 72 h. In A. aegypti, human DNA concentration was reduced with time at both temperatures. At 18°C, we obtained full STR profiles up to 48 h post feeding on human blood while none of the 16 loci were obtained at 72 h. At 40°C, we missed six sites at 12 h after blood sucking, 12 at 24 h, and 15 at 48 h and 72 h. In C. pipiens cultured at 18°C, full profiles were developed up to 48 h following blood feeding while we could not amplify five sites at 72 h. At 40°C, mortality among females was 50% at 24 h and 100% at both 48 h and 72 h; however, we had full profiles in all samples including dead insects. This research addressed the possibility of using mosquitoes in forensic research by DNA genotyping by changing the mosquito culturing temperature and mosquito genus. Our findings proved that different types of mosquito change the temporal pattern of STR analysis and showed that the mosquito culturing temperature affects the integrity of DNA for STR analysis.
Vibration analysis of cracked frame structures
Ibrahim, Ahmed M.,Ozturk, Hasan,Sabuncu, Mustafa Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.1
In this study, the effects of crack depth and crack location on the in-plane free vibration of cracked frame structures have been investigated numerically by using the Finite Element Method. For the rectangular cross-section beam, a crack element is developed by using the principles of fracture mechanics. The effects of crack depth and location on the natural frequency of multi-bay and multi-store frame structures are presented in 3D graphs. The comparison between the present work and the results obtained from ANSYS shows a very good agreement.
Storage Proteins of Diamondback Moth, Plutella xylostella: Purification and Expression Profile
Ibrahim Ahmed M.A.,Lee Kee-Woo,Lee Hyuk-Soo,Kim Yong-Gyun Korean Society of Applied Entomology 2006 Journal of Asia-Pacific Entomology Vol.9 No.2
Storage proteins (SPs) were significantly detected in the hemolymph during the late instar larvae of diamondback moth, Plutella xylostella. These SPs were resolved into three proteins (SP1, SP2, and SP3) at 7% SDS-PAGE. Their apparent molecular sizes were around 80 kDa. SP1 was synthesized later than SP2 and SP3 during the development of the last instar. Total soluble proteins of last instar larvae were extracted and fractionated sequentially with ammonium sulfate, size-exclusion chromatography, and ion-exchange chromatography. The SPs were purified and their developmental expression was discussed.