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1
Content available remote Optimized sound absorption of a rigid polyurethane foam
100%
Ibrahim M. A. , Melik R. W.
Archives of Acoustics
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2003
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tom Vol. 28, no. 4
305-312
EN
In this study, cast panel received as sound insulator was implemented as sound absorber. The panel is composed of prepainted metal skins with a rigid self extinguishing polyurethane foam. For the achievement of such material as sound absorber, holes are uniformly drilled in the sample to allow relatively easy access of sound to the interior structure. Using the two microphone impedance measurement tube, the sound absorption coefficient was studied for samples of different, coverings, opening pores (2 mm, 3 mm), open areas (0.04, 0.16), and at air space depths: 0, 5, 10, 20 and 40 mm from the reflected wall. The normalized acoustic impedance was also studied. The results revealed that when the sample was uniformly drilled with pores of opening 2~mm each to have 0.16 mm open area, and positioned at air space depth (5 mm), it showed optimum sound absorption greater than 0.80 in the frequency range from 700-1600 Hz. In dealing with noise reduction, this absorption gives, 6.9 dB drop in noise level.
2
Content available remote Analysis of X-ray structure, dielectric properties and AC conductivity of (4E)-2-amino-3-cyanobenzo[b]oxocin-6-one
100%
Ali H. A. M. , Ibrahim M. A.
Materials Science Poland
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2016
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tom Vol. 34, No. 2
386--392
EN
The crystal structure of (4E)-2-amino-3-cyanobenzo[b]oxocin-6-one, denoted as 4(E)-ACBO, was analyzed using X-ray diffraction technique. The dielectric and AC electrical conductivity measurements of the bulk 4(E)-ACBO in the form of pellet were studied in the range of frequency 42 Hz to 5 MHz and the temperature range of 303 K to 373 K. The temperature and frequency dependence of dielectric constant (ε1), dielectric loss (ε2) and AC electrical conductivity (δ εAC) were investigated. The relaxation time (τ) for electrons to hop over a barrier of height WH was calculated at different temperatures. The AC activation energy was determined from the temperature dependence of δ AC at different frequencies.
3
Content available In vitro culture of big-sage (Lantana camara L.) plant
80%
Ibrahim M. A. , Sabty M. Z. , Mussa S. H.
Acta Scientiarum Polonorum. Hortorum Cultus
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2020
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tom 19
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nr 2
EN
The study was conducted to mass micropropagation of big sage (Lantana camara L.) plant by shoot multiplication technique. The treatments 2.22 and 2.66 µmol·L⁻¹ BA gave the highest significant increase in the percentage of response to shoot multiplication and number of shoots per explant compared to the other treatments as reached 96.70% and 100.00% and 4.33 and 6.00 shoots, respectively. The results showed that these two treatments did not differ significantly between them. While the 1.33 µmol·L⁻¹ BA gave the lowest values in the percentage of response to shoot multiplication and number of shoots per explant were 80.00% and 2.00 shoots per explant, respectively. The MS medium supplemented with 4.30 or 5.37 µmol·L⁻¹ NAA gave a high response to root formation, number of roots per shoot and root length. While the MS medium supplemented with 6.44 or 7.52 µmol·L⁻¹ NAA gave low values in these characteristics. The MS medium with 2.22 or 2.66 µmol·L⁻¹ concentration of BA or 7.52 µmol·L⁻¹ concentration of NAA recorded the highest significant increase in the percentage of response to callus formation. While the MS medium supplemented with 1.33 µmol·L⁻¹ BA or 4.30 µmol·L⁻¹ NAA gave less response to the callus formation.
4
Content available Minerals content, essential oils composition and physicochemical properties of Citrus jambhiri Lush. (Rough Lemon) from the Sudan
70%
Mohammed A. M. H. , Ibrahim M. A. , Omran A. A. , Mohamed E. M. , Elsheikh S. E. M.
International Letters of Chemistry, Physics and Astronomy
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2013
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tom Vol. 9, iss. 1
25-30
EN
Minerals content of Citrus jambhiri (rough lemon) fruit was qualitatively and quantitatively analyzed using atomic absorption spectroscopy (AAS) and flame atomic emission spectrometry (FAES). The peel, moisture and ash contents of rough lemon were found to be 18.35 %, 23.75 % and 2.04 % respectively. Vitamin C (ascorbic acid) of rough lemon juice was found to be 70.0 mg/100 g. The chemical composition of essential oil of rough lemon peel was determined. The major compound was found to be limonene (84.5 %) followed by sabinene, β-myrcene, α-terpineol, 1,3-tetradecadiene and linalool.
5
Content available remote Linum usitatissimum seeds oil down-regulates mRNA expression for the steroidogenic acute regulatory protein and CYP11A1 genes, ameliorating letrozole-induced polycystic ovarian syndrome in a rat model
51%
Emam S. R. , Abd-Elsalam R. M. , Azouz A. A. , Ali S. E. , El Badawy S. A. , Ibrahim M. A. , Hassan B. B. , Issa M. Y. , Elmosalamy S. H.
Journal of Physiology and Pharmacology
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2021
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tom 72
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nr 1
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