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Search Results: 1 - 10 of 26803 matches for " Ahmed Al-Harrasi "
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Dimethylformamide Dimethyl Acetal (DMFDMA) in Heterocyclic Synthesis: Synthesis of Polysubstituted Pyridines, Pyrimidines, Pyridazine and Their Fused Derivatives  [PDF]
Fathi A. Abu-Shanab, Sayed A. S. Mousa, E. A. Eshak, Ahmed Z. Sayed, Ahmed Al-Harrasi
International Journal of Organic Chemistry (IJOC) , 2011, DOI: 10.4236/ijoc.2011.14030
Abstract: Reaction of N,N’-dimethylformamide dimethyl acetal (DMFDMA) with malononitrile dimer 8 (1:1) mole afforded 9 while, this reaction when carried out in (2:1) mole to give amidine 11 which can be used for the preparation of pyrimidine 13, amidine 14 and pyridine 19 when reacted with 4-nitroaniline, 4-methylaniline and alkoxide respectively. Malononitrile dimer reacted with diazonium chloride to give pyridazine 21, which can be reacted with DMFDMA, AcOH/HCl and cyanoacetamide to give pyridazine 22, 23 and pyrido[4,3-c] pyridazine 24 respectively. The latter reacted with DMFDMA to afford tricyclic compound 25.
Phytochemical Analysis of the Essential Oil from Botanically Certified Oleogum Resin of Boswellia sacra (Omani Luban)
Ahmed Al-Harrasi,Salim Al-Saidi
Molecules , 2008, DOI: 10.3390/molecules13092181
Abstract: The yield of hydrodistillation of a botanically certified Oleogum Resin of Boswellia sacra essential oil (5.5%); and its chemical constituents were determined. The GC/MS technique was used for the analysis of the oil. Several oil components were identified based upon comparison of their mass spectral data with those of reference compounds published in literature or stored in a computer library. The oil was characterized by the high content of the monoterpenes (34) which constituted 97.3% in which E-β-ocimene and limonene were the major constituents. The remaining 2.7% was accounted for the sesquiterpenes (16) in which the E-caryophyllene was the major constituent. The analysis proved the complete absence of the diterpenes.
Chemistry and Biology of Essential Oils of Genus Boswellia
Hidayat Hussain,Ahmed Al-Harrasi,Ahmed Al-Rawahi,Javid Hussain
Evidence-Based Complementary and Alternative Medicine , 2013, DOI: 10.1155/2013/140509
Abstract:
Erratum to “Chemistry and Biology of Essential Oils of Genus Boswellia”
Hidayat Hussain,Ahmed Al-Harrasi,Ahmed Al-Rawahi,Javid Hussain
Evidence-Based Complementary and Alternative Medicine , 2014, DOI: 10.1155/2014/792517
Abstract:
Organotin(IV) compounds of n-propyl and isopropyl glutarate: their synthesis, spectral characterization and antibacterial activity
Javid Hussain,Hidayat Hussain,Viqar Uddin Ahmad,Ahmed Al-Harrasi
Organic Communications , 2012,
Abstract: A series of new di- and triorganotin(IV) complexes of monoisopropyl and mono n-propyl glutarate have been synthesized and characterized by 1H- 13C- 119Sn-NMR, UV, IR and Mass spectrometry. The spectroscopic investigation demonstrated that the carboxylate group acts as a bidentate ligand in diorganotin(IV) and as a monodentate ligand in triorganotin(IV) compounds. Biological evaluation against various microorganisms indicates that the diorganotin(IV) complexes are slightly less reactive than triorganotin(IV) complexes.
Generation of Electricity by Electrogenic Bacteria in a Microbial Fuel Cell Powered by Waste Water  [PDF]
Zakira Naureen, Zainab Ali Rashid Al Matani, Miyassa Nasser Al Jabri, Saif Khalfan Al Housni, Syed Abdullah Gilani, Fazal Mabood, Saima Farooq, Javid Hussain, Ahmed Al Harrasi
Advances in Bioscience and Biotechnology (ABB) , 2016, DOI: 10.4236/abb.2016.77031
Abstract: The present study aimed at isolation characterization and evaluation of electrogenic bacteria for electricity generation using waste water. In this context, waste water samples were collected from University of Nizwa waste water treatment plant. A total of eight distinct bacterial isolates were isolated from these samples by serial dilution and plating on LB Agar medium. The bacterial isolates were than grown at different temperatures and pH. DNA from bacterial samples was isolated and 16S rRNA gene amplification was carried out. The 16S rRNA gene PCR products were directly sequenced and the resulting sequence was blasted using BLASTn. Based on BLAST results, the bacterial strains were identified. The bacteria were used in different combinations to generate electricity from waste water in microbial fuel cells constructed using plastic bottles. The microbial isolates were found to produce varying levels of currents and their electrogenic potential in waste water was observed to increase with the passage of time.
Using Stories in English Omani Curriculum
Kothar Talib Sulaiman Al Harrasi
English Language Teaching , 2012, DOI: 10.5539/elt.v5n11p51
Abstract: Learning a FL may be frustrating for some young learners; however, integrating fun in learning would encourage them to develop positive attitudes towards learning a language (Ellis & Brewster, 1991). Stories are an effective and enthusiastic technique in teaching young learners; they inject lots of amusement and help children enjoy learning language in purposeful communication. This paper is an attempt to explore the effectiveness of the stories in Omani curriculum (English for Me) and eventually suggests some efficient techniques and activities in teaching stories based on the analysis. Preliminary findings show that stories in the textbooks are enthusiastic and suit learners' interest and level, and the follow-up activities increase their benefits. However, there are some stories or activities that are repetitive and too long, and need to be modified or replaced by others.
Comparison of the Bayesian Methods on Interval-Censored Data for Weibull Distribution  [PDF]
Al Omari Mohammed Ahmed
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.48053
Abstract: This study considers the estimation of Maximum Likelihood Estimator and the Bayesian Estimator of the Weibull distribution with interval-censored data. The Bayesian estimation can’t be used to solve the parameters analytically and therefore Markov Chain Monte Carlo is used, where the full conditional distribution for the scale and shape parameters are obtained via Metropolis-Hastings algorithm. Also Lindley’s approximation is used. The two methods are compared to maximum likelihood counterparts and the comparisons are made with respect to the mean square error (MSE) to determine the best for estimating of the scale and shape parameters.
The Environmental Impacts of Kabd Landfill on the Soil and Groundwater in Kuwait: A Case Study  [PDF]
Ahmed R. Al Rashed
International Journal of Geosciences (IJG) , 2018, DOI: 10.4236/ijg.2018.95016
Abstract: The environmental impacts of the Kabd Landfill on the soil and groundwater in Kuwait were evaluated. Physical and chemical analyses were carried out on thirty pairs of surface, subsurface soil and five groundwater samples. The groundwater samples are collected from boreholes nearby and downstream of the landfill while the soil samples collected along six profiles. The groundwater samples were geochemically analyzed to determine the total dissolved solids, cations, anions and heavy metals, particularly Iron (Fe), Copper (Cu), zinc (Zn), Cadmium (Cd), Nickel (Ni), Chromium (Cr) and Aluminum (Al), Lithium (Li), Boron (B), Fluoride (F) and Vanadium (V). The soil samples were geochemically analyzed to determine concentration of Cadmium (Cd), Lead (Pb), Nickel (Ni), Iron (Fe), Aluminum (Al) and organics. The results show that the soil and groundwater are contaminated with high TDS, Na, Ca, Mg, Cl, SO4 and heavy metals, especially Ni, Cd, Cu, Al, V and F. The heavy metal concentrations in both the soil and groundwater samples are compared to the World Health Organization (WHO) standard permissible limits. The results revealed that the Zn, Li, B and Fe metals are below the WHO limits for consumption. The soil lithology, natures of dumping, the depth of quarry and the depth to the groundwater level play roles in leachate generation and groundwater contaminations. Such leachate may be originated from the capillary fringe water, moisture content and rising water table, due to its close level at the bottom of the waste disposal site. The organic strength of the soil was reduced due to waste decomposition and continuous gas
Validation of Chaviaro Poulos and Hansen Stall Delay Model in the Case of Horizontal Axis Wind Turbine Operating in Yaw Conditions  [PDF]
Abdelfattah Bouatem, Ahmed Al Mers
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.51003
Abstract:

Operating in natural wind field, the horizontal axis wind turbines are subject to cyclical variation of aerodynamic loads. This cyclical loads fluctuation is a result of two aerodynamic phenomenon: the first one is the advancing and retreating blade effect; the second one is related to the cyclical variation of induced velocity at the rotor plane. In these operating conditions, the correct prediction of this load variation is necessary to predict some important parameters linked to the fatigue and stability of free yawing turbines. The main objective of the present study is the evaluation of the azimuthal variation of normal force at different radial positions. To model the problem, the blade element momentum theory is used and wind turbine is supposed operate in yaw conditions. The aerodynamic coefficients are corrected using Chaviaropoulos and Hansen model to take into account the phenomenon of stall delay. A computer code was developed to obtain the numerical values and results are compared with measurements performed in the NASA Ames wind tunnel.

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