OALib Journal期刊

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匹配条件: “Youssef A. Mahmoud” ,找到相关结果约462429条。
Microwave Assisted Synthesis of Some New Thiazolopyrimidine, Thiazolodipyrimidine and Thiazolopyrimidothiazolopyrimidine Derivatives with Potential Antioxidant and Antimicrobial Activity
Mohamed M. Youssef,Mahmoud A. Amin
Molecules , 2012, DOI: 10.3390/molecules17089652
Abstract: Biginelli reaction of ethyl acetoacetate, thiourea and the appropriate aromatic aldehyde was used to produce ethyl 4-aryl-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylates, that reacted with bromomalononitrile to give ethyl 3-amino-5-aryl-2-cyano-7-methyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylates rather than the isomeric 7H-thiazolo[3,2-a]pyrimidines. Thiazolopyrimidine derivatives reacted with carbon disulphide to yield ethyl 9-aryl-7-methyl-2,4-dithioxo-2,3,4,9-tetrahydro-1H-thiazolo[3,2-a:4,5-d']dipyrimidine-8-carboxylates, that reacted with phenacyl bromide to produce ethyl 8-methyl-10-(4-methoxyphenyl)-3-substituted-5-thioxo-2(un)subatituted-10H-thiazolo[3'',2'':1',2']pyrimido[4',5':4,5]thiazolo[3,2-a]pyrimidine-9-carboxylates. The aforementioned reactions were carried out using both conventional chemical methods and with the assistance of microwave irradaition. Comparison between both methods showed that the microwave assisted method is preferable because of the time reduction and yield improvements achieved. The new compounds were tested for their biological activity as antioxidants, antibacterial or antifungal agents. Some of the new compounds were found to have moderate to good antioxidant and antimicrobial activities.
Computing the Pressure Drop of Nanofluid Turbulent Flows in a Pipe Using an Artificial Neural Network Model  [PDF]
Mahmoud S. Youssef, Ayman A. Aly, El-Shafei B. Zeidan
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24013
Abstract: In this study, an Artificial Neural Network (ANN) model to predict the pressure drop of turbulent flow of titanium dioxide-water (TiO2-water) is presented. Experimental measurements of TiO2-water under fully developed turbulent flow regime in pipe with different particle volumetric concentrations, nanoparticle diameters, nanofluid temperatures and Reynolds numbers have been used to construct the proposed ANN model. The ANN model was then tested by comparing the predicted results with the measured values at different experimental conditions. The predicted values of pressure drop agreed almost completely with the measured values.
Improved Production of Endoglucanase Enzyme by Aspergillus terreus; Application of Plackett Burman Design for Optimization of Process Parameters
Gahda A. Youssef,Mahmoud M. Berekaa
Biotechnology , 2009,
Abstract: In this study, bagasse was used as substrate for endoglucanase (carboxymethyl-cellulase; CMCase) production using locally isolated Aspergillus terreus and the culture parameters were optimized for enhancing cellulase yield. The fungus showed 0.9 U mL-1 endoglucanase (CMCase) activity, during growth on basal salts medium at 35oC, initial pH value of 5.5 and in presence of 5% bagasse as a sole c-source. Preliminary experiments to address the most suitable nitrogen source as well as the optimal substrate (bagasse) treatment revealed that the optimal enzyme activity were 2.1 and 2.43 U mL-1 in presence of 3 g yeast extract and 1 N HCl or 1 NaOH, respectively. Statistically based experimental design was applied to optimize the production of endogluconase by A. terreus. To evaluate the effect of different culture conditions on the production of CMCase enzyme, Plackett-Burman factorial design was carried out. Twelve variables were examined for their significance on enzyme production. Treated bagasse (T2), non treated bagasse (NT), K2HPO4, NaNO3, trace elements, KCl, temperature and pH were the most significant factors encourage CMCase enzyme production, whereas treated bagasse (T3), yeast extract and MgSO4, were the most significant factors decreasing CMCase enzyme production. The pre-optimized medium showed approximately 4 folds increase in cellulase enzyme production.
Potato Disc Bioassay and Cytotoxic Effect of Leptadenia pyrotechnica: Comparative Study of Diverse Extracts
Amal M. Youssef Moustafa,Ahmed I. Khodair,Mahmoud A. Saleh
Pakistan Journal of Biological Sciences , 2011,
Abstract: Comparative acute toxicity studies of the latex and sequential extracts of Leptadenia pyrotechnica (Forsk.) Decne (Asclepiadaceae) were recorded using brine shrimp. The higher toxicities were exhibited in latex; methanol, methanol/dichloromethane (1:1), defatted methanol/dichloromethane (1:1), defatted methanol and dichloromethane extracts. The other extracts; aqueous, alkaloids, ethyl acetate and n-butanol exhibited less toxicities compared with the other extracts. The estimated LC50 and its 95% confidence limits for these extracts expressed in ppm were: methanol, latex 18.84 (11.22-31.61), methanol/dichloromethane 19.95 (7.76-53.70), defatted methanol/dichloromethane 21.38 (7.24-63.10), defatted methanol 28.19 (16.27-48.81) and dichloromethane 30.90 (11.75-79.43). The anti-tumor activities; potato disc assays of methanol, ethyl acetate and alkaloids extracts showed good activities as anti-tumor agent which represented-49.30,-43.20 an -33.60%, respectively. While latex and aqueous extract represented-30.80 and-28.17%, respectively.
Distributed Flooding-based Storage Algorithms for Large-scale Sensor Networks
Salah A. Aly,Hager S. Darwish,Moustafa Youssef,Mahmoud Zidan
Mathematics , 2009,
Abstract: In this paper we propose distributed flooding-based storage algorithms for large-scale wireless sensor networks. Assume a wireless sensor network with $n$ nodes that have limited power, memory, and bandwidth. Each node is capable of both sensing and storing data. Such sensor nodes might disappear from the network due to failures or battery depletion. Hence it is desired to design efficient schemes to collect data from these $n$ nodes. We propose two distributed storage algorithms (DSA's) that utilize network flooding to solve this problem. In the first algorithm, DSA-I, we assume that every node utilizes network flooding to disseminate its data throughout the network using a mixing time of approximately O(n). We show that this algorithm is efficient in terms of the encoding and decoding operations. In the second algorithm, DSA-II, we assume that the total number of nodes is not known to every sensor; hence dissemination of the data does not depend on $n$. The encoding operations in this case take $O(C\mu^2)$, where $\mu$ is the mean degree of the network graph and $C$ is a system parameter. We evaluate the performance of the proposed algorithms through analysis and simulation, and show that their performance matches the derived theoretical results.
Natural Plant Essential Oils for Controlling the Grasshopper (Heteracris littoralis) and their Pathological Effects on the Alimentary Canal
Aziza Sharaby,Sayed A. Montasser,Youssef A. Mahmoud,Sobhi A. Ibrahim
Ecologia Balkanica , 2012,
Abstract: In the present study, the toxic effect of three different natural essential oils of medicinal plants, namely Garlic (Allium sativum), Mint (Mintha pipereta) and Eucalyptus (Eucalyptus globulus) were tested on 1st nymphal instar of the grasshopper (Heteracris littoralis). The LC50 values of the tested oils were estimated after 14 days from feeding on treated diet mixed with different concentrations of the oil. The LC50 of the tested oils were arranged as follows: 0.067, 0.075 and 0.084ml. /100ml. diet for Garlic, Eucalyptus and Mint respectively. The effect of LC50 concentration of the oils on the biological aspects and histological changes that observed on the alimentary canal and fat bodies were recorded. The normal development of the grasshopper was exhibited. Results cleared that there was statistical variable numbers of increased the nymphal periods, life cycle, adults longevity and life span comparing with the control test. Garlic oil inhibited egg lying by the resulting females offspring of the treated1st instar nymphs. High reduction in the deposited eggs and egg fertility caused by Eucalyptus or Mint oil and marked malformation were observed. Histological changes on the alimentary canal and fat bodies of the remaining nymphs after treatment with Garlic oil (the most effective oil) were detected by the light microscope have been recorded. The results suggest that the natural plant essential oils of Garlic, Eucalyptus and Mint may be used in IPM control program against H. littoralis grasshopper.
Antifungal activity of different neem leaf extracts and the nimonol against some important human pathogens
Mahmoud, D.A;Hassanein, N.M;Youssef, K.A;Abou Zeid, M.A;
Brazilian Journal of Microbiology , 2011, DOI: 10.1590/S1517-83822011000300021
Abstract: this study was conducted to evaluate the effect of aqueous, ethanolic and ethyl acetate extracts from neem leaves on growth of some human pathogens (aspergillus flavus, aspergillus fumigatus, aspergillus niger, aspergillus terreus, candida albicans and microsporum gypseum) in vitro. different concentrations (5, 10, 15 and 20%) prepared from these extracts inhibited the growth of the test pathogens and the effect gradually increased with concentration. the 20% ethyl acetate extract gave the strongest inhibition compared with the activity obtained by the same concentration of the other extracts. high performance liquid chromatography (hplc) analysis of ethyl acetate extract showed the presence of a main component (nimonol) which was purified and chemically confirmed by nuclear magnetic resonance (nmr) spectroscopic analysis. the 20% ethyl acetate extract lost a part of its antifungal effect after pooling out the nimonol and this loss in activity was variable on test pathogens. the purified nimonol as a separate compound did not show any antifungal activity when assayed against all the six fungal pathogens.
Effect of Unilateral Ureteral Ligation on Blood Constituents, Renal Histopathology and Ultrasonography in Dogs
M.A.H. Abd El-Hakiem,Mahmoud R. Abd Ellah,H.A. Youssef,A.S. Saleh,Khaled M.A. Hassanein
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2011.356.364
Abstract: The goal of the present study was to evaluate the effect of unilateral ureteral ligation on blood constituents, renal histopathology and ultrasonography in dogs. A total number of 25 apparently healthy adult mongrel dogs belong to Assiut city, Egypt were subjected to study. Animals were divided into 5 equal groups; the left ureter was ligated for 2, 7, 14 and 21 days in group I, II, III and IV, respectively. Group V represented the control group. The animals of the groups I-IV were euthanized on days 2, 7, 14 and 21, respectively. Right and left uretronephrectomies were performed and specimens were taken for the histopathological examination. Results revealed significant increases in total leucocytes and neutrophils counts from day 2-17. There were significant decreases (p<0.01) in total RBCs count and PCV% at day 14. Creatinine level was significantly increased on days 7 and 17. Histopathological changes were varied from glomerular swelling and congestion to glomerular atrophy.
The Role of Radiography in Detection of Unilateral Obstructed Kidney in Dog
M.A.H. Abd El-Hakiem,Mahmoud R. Abd Ellah,H.A. Youssef,A.S. Saleh
Veterinary Research , 2012, DOI: 10.3923/vr.2011.121.125
Abstract: The present study was carried out on twenty five apparently healthy adult mongrel dogs. The animals were 12 males and 13 females. Their age ranged from 9 months to 4 years and their weight from 9-31 kg. The animals were divided into five groups; each of five dogs. The groups were treated in the following manner according to the time of ligation of the left ureter into: 2, 7, 14 and 21 days for groups 1, 2, 3 and 4, respectively in addition to the control group. The kidneys were evaluated radiographically according to the renal opacification, perisestance of opacification and renal dimensions in relation to L2. It was found that the renal opacification was the poorest in the animals in group 4. The perisestance of opacification increased with the increase the time of ligation.
Vascular endothelial growth factor, p53, and the H-ras oncogene in Egyptian patients with bladder cancer
Farha A El-Chennawi, Fatma A Auf, Shereen S Metwally, Youssef M Mosaad, Atallah A Shaaban, Mahmoud Abdo El-Baz, Ziyad E Tawhid, Zakaria F Lotfy
World Journal of Gastrointestinal Oncology , 2009,
Abstract: AIM: To evaluate the relationship between vascular endothelial growth factor (VEGF), p53, and the H-ras oncogene and different clinicopathological parameters in Egyptian patients with Schistosoma-associated transitional cell carcinoma of the bladder. METHODS: The study included 50 patients with transitional cell carcinoma for whom radical cystectomy and urinary diversions were carried out. VEGF and p53 protein expressions were evaluated with an immunohistochemical staining method, and H-ras oncogene mutations were analyzed with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. RESULTS: High grade tumors revealed higher p53 immunostaining than low grade tumors ( P = 0.016). p53 and VEGF protein expressions, as well as H-ras oncogene mutations, had an insignificant impact on patient outcomes ( P = 0.962, P = 0.791, and P = 967, respectively). Cancer extension to regional lymph nodes was associated with poor outcomes ( P = 0.008). CONCLUSION: VEGF, p53 and the H-ras oncogene have no relation to patient survival and outcome in Schistosoma-associated transitional cell carcinoma.

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