Sub-Synchronous Range of Operation for a Wind Driven Double-Fed Induction Generator

Mahmoud Abdel Halim Saleh,Mona Naguib Eskander 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.1

In this paper the operation of a double-fed wound-rotor induction machine, coupled to a wind turbine, as a generator at sub-synchronous speeds is investigated. A novel approach is used in the analysis, namely, the rotor power flow approach. The conditions necessary for operating the machine as a double-fed induction generator (DFIG) are deduced. Formulae describing the factors affecting the range of sub-synchronous speeds within which generation occurs are deduced. The variations in the magnitude and phase angle of the voltage injected to the rotor circuit as the speed of the machine changes to achieve generation at the widest possible sub-synchronous speed range is presented. Also, the effect of the rotor parameters on the generation range is presented. The analysis proved that the generation range could increase from sub-synchronous to super- synchronous speeds, which increases the amount of energy captured by the wind energy conversion system (WECS) as result of utilizing the power available in the wind at low wind speeds.

Isoflavonoids and Alkaloids from Spartidium saharae

Osama B. Abdel Halim,Hosny A. Abdel Fattah,Fathi T. Halaweish,Ahmed F. Halim 한국생약학회 2000 Natural Product Sciences Vol.6 No.4

A new isoflavone, (+)-4`-O-methyl-8-C-β-D-glucopyranosylgenistein, was isolated from the aerial parts of Spartidium saharae together with the known isoflavone, (+)-8-C-β-D-glucopyranosylgenistein as well as dipiperidine alkaloids, (+)-ammodendrine and (+)-N-acetyl hystrine. Details of their structure elucidation are based on chemical and spectroscopic methods. N-formyl ammodendrine was detected by GC-MS. The potential chemotaxonomic value of the alkaloid content is explored. Cytotoxic activity has been determined for both alcoholic extract and isolated compounds.

Use of DNA adduct and histopathological defects as indications for bio-persistence potency of zinc oxide nanoparticles in gastropod, Monacha cartusiana (Mǜller) after short-term exposure

Khaled Yassin Abdel-Halim,Safaa Ramadan Osman,Atef Mohamed Khedr Nassar,Alaa Khozimy,Heba Mohamed El-Danasoury 환경독성보건학회 2022 환경독성보건학회지 Vol.37 No.3

The cytotoxic effects of metallic nanoparticles (MNPs) might be revealed in genomic and histopathological defects. Therefore current study aimed to assess the bio-persistence and adverse effects potency of zinc oxide nanoparticles (ZnONPs) in the gastropod, Monacha cartusiana. Gastropods were exposed to 74 μg/mL for 14 d then the DNA adduct and histopathological defect profiles were assessed. The results demonstrated significant decline in the estimated genomic template stability (GTS%) in haemolymph and digestive gland ranging from 10.0 to 42.9% in treated animals compared to controls. In the treated and recovered snails, randomly amplified polymorphic (RAPD)-DNA showed the appearance and/or disappearance of DNA bands, indicating DNA damage due to the cytotoxicity of ZnONPs on gastropods. Significant defects in microvilli (MV), nucleus (N), mitochondria (M), and execratory glands (EXG) were noticed in the treated individuals with respect to controls. The remaining live animals were subjected to a recovery period (14 d, without treatment) and slight recovery profiles were reported for both measures compared to the control group. The recovery pattern was recognized in the nucleus/cytoplasm ratio with 0.186 and 0.428 in the treated and recovered groups concerning their control (0.176). The studied parameters reported herein might be reliable tools to assess accumulation and bio-persistence patterns of NPs in the organisms for short-term exposure indicating the cytotoxic and genotoxic effects. Also, gastropods may provide simple models for evaluating the ecotoxicological effects of nanomaterials.

Original Article: Food Science/Microbiology : Extraction of β-glucosidase from Bagasse Fermented by Mixed Culture under Solid State Fermentation

( Hoda Mohamed Abdel Halim Shata ),( Mohamed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2014 Journal of Applied Biological Chemistry (J. Appl. Vol.57 No.3

Various parameters such as solvent selection, concentration, solid/liquid ratio, soaking time, temperature, stationary, shaking conditions, and repeated extractions were investigated in order to determine the optimum extraction conditions of β-glucosidase from bagasse fermented by mixed culture of Aspergillus niger NRC 7A and Aspergillus oryzae NRRL 447. Among various solvents tested, non ionic detergents gave the best results than the inorganic or organic salt solutions and distilled water. The optimum conditions for extraction of β-glucosidase were 30 min soaking time at 40oC under shaking condition at 150 rpm, with solid/liquid ratio 1:15 (w/v), which yielded 2882.74±95.52 U/g fermented culture (g fc) of enzyme activity. With repeated washes under the above optimum conditions, the results showed that enzyme extracted in the 1st and 2nd washes represents about 90% of the total activity.

Tissue distribution, placental transfer and excretion of silver nanoparticles in pregnant rats after a single oral dose

Khaled Y. Abdel-Halim,Elsayed I. Salim,Ahmed S. Abdel-Latif,Sally E. Abu-Risha 환경독성보건학회 2023 환경독성보건학회지 Vol.38 No.4

A quantitative assessment of silver nanoparticles (AgNPs) in fluids and some organs of pregnant rats as well as their fetal blood were carried out in this study. A single oral dose (1mg/kg) of AgNPs with a size range of 4-20 nm was administered to pregnant rats on the 19th of gestation. Five groups were euthanized after 10 min, 1, 6, 12, and 24 hr as well as the control group. Total Silver (Ag) contents were measured in bloods (maternal and fetal) and several organs using Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES) followed by acid digestion. In maternal blood, AgNPs were found to increase time-dependently after 12 and 24 hr into 0.135 and 0.224 μg/ml, but it was slightly higher in fetal blood (0.32 and 0.31 μg/ml) after 10 min and 1 hr. In other samples: kidneys, liver, spleen, placenta, and uterus the data indicated that NPs were rapidly absorbed from the dosing site (gastrointestinal tract) as evidenced by the detection of Ag in the analyzed samples (fluids and tissues). On the other hand, the cumulative percentages of excretion level in urine was 8.25% which was higher than in feces (4.77%) after 24 hr. These findings indicate the ability of AgNPs to accumulate in pregnant rats and transfer to their fetus imposing adverse outcomes and male formation. Thus, further investigations must be followed for direct and/or indirect exposure to such NPs before decision for their practices.

Sub-Synchronous Range of Operation for a Wind Driven Double-Fed Induction Generator

Saleh, Mahmoud Abdel Halim,Eskander, Mona Naguib The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.1

In this paper the operation of a double-fed wound-rotor induction machine, coupled to a wind turbine, as a generator at sub-synchronous speeds is investigated. A novel approach is used in the analysis, namely, the rotor power flow approach. The conditions necessary for operating the machine as a double-fed induction generator (DFIG) are deduced. Formulae describing the factors affecting the range of sub-synchronous speeds within which generation occurs are deduced. The variations in the magnitude and phase angle of the voltage injected to the rotor circuit as the speed of the machine changes to achieve generation at the widest possible sub-synchronous speed range is presented. Also, the effect of the rotor parameters on the generation range is presented. The analysis proved that the generation range could increase from sub-synchronous to super-synchronous speeds, which increases the amount of energy captured by the wind energy conversion system (WECS) as result of utilizing the power available in the wind at low wind speeds.

TALENs Construction: Slowly but Surely

Hegazy, Wael Abdel Halim,Youns, Mahmoud Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.7

Cancer is thought to be a direct result of transcriptional misregulation. Broad analysis of transcriptional regulatory elements in healthy and cancer cells is needed to understand cancer development. Nucleases regulatory domains are recruited to bind and manipulate a specific genomic locus with high efficacy and specificity. TALENs (transcription activator-like effector nuclease) fused to endonuclease FokI have been used widely to target specific sequences to edit several genes in healthy and cancer cells. This approach is promising to target specific cancer genes and for this purpose it is needed to pack such TALENs into viral vectors. There are some considerations which control the success of this approach, targeting appropriate sequences with efficient construction of TALENs being crucial factors. We face some obstacles in construction of TALENs; in this study we made a modification to the method of Cermk et al 2011 and added one step to make it easier and increase the availability of constructs.

Medium optimization for keratinase production by a Local Streptomyces sp. NRC 13S under solid state fermentation

( Hoda Mohamed Abdel Halim Shata ),( Mohamed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2013 Journal of Applied Biological Chemistry (J. Appl. Vol.56 No.2

Thirteen different Streptomyces isolates were evaluated for their ability to produce keratinase using chicken feather as a sole carbon and nitrogen sources under solid state fermentation (SSF). Streptomyces sp. NRC 13S produced the highest keratinase activity [1,792 U/g fermented substrate (fs)]. The phenotypic characterization and analysis of 16S rDNA sequencing of the isolate were studied. Optimization of SSF medium for keratinase production by the local isolate, Streptomyces sp. NRC13S, was carried out using the one-variable-at-a-time and the statistical approaches. In the first optimization step, the effect of incubation period, initial moisture content, initial pH value of the fermentation medium, and supplementation of some agro-industrial by-products on keratinase production were evaluated. The strain produced about 2,310 U/gfs when it grew on chicken feather with moisture content of 75% (w/w), feather: fodder yeast ratio of 70:30 (w/w), and initial pH 7 using phosphate buffer after 8 days. Based on the results, the Box-Behnken design and response surface methodology were applied to find out the optimal conditions for the enzyme production. The corresponding maximal production of keratinase was about 2,569.38 U/gfs.

Original Article: Food Science/Microbiology : Xylanase Production by Mixed Culture Using Crude Hemicellulose from Rice Straw Black Liquor and Peat Moss as an Inert Support

( Hoda Mohamed Abdel Halim Shata ),( Azza Mohmed Noor El-deen ),( Galal Abdel Moen Nawwar ),( Mohmed Abdel Fattah Farid ) 한국응용생명화학회(구 한국농화학회) 2014 Journal of Applied Biological Chemistry (J. Appl. Vol.57 No.4

Black liquor (BL) is a by-product of rice straw pulping process. It is a low costs raw material for production value-adding proteins and enzymes, which has been paid more and more attention to reduce its environmental pollution. Mixed cultures of micelial fungi, Trichoderma reesei Northern Regional Research Laboratory (NRRL)11236, Trichoderma reesei NRRL 6165 and Aspergillus niger strains NRC 5A, NRC 7A, and NRC 9A were evaluated for their ability to produce xylanase using crude hemicellulose (CHC) prepared from BL and peat moss as an inert support under solid state fermentation (SSF). The most potent strains, A. niger NRC 9A (818.26 U/g CHC) and T. reesei NRRL 6165 (100.9±57.14 U/g CHC), were used in a mixed culture to enhance xylanase production by co-culturing under SSF. In the mixed culture, xylanase production (1070.52±12.57 U/g CHC) was nearly1.3 and 10.6-fold increases over the activities attained in their monocultures, A. niger NRC 9A and T. reesei NRRL 6165, respectively. Optimization of the culture parameters of the mixed culture SSF process, concentration of ammonium sulfateand corn steep liquor, CHC/peat moss ratio, inoculum size and ratios of the two strains, initial pH value, initial moisture content and incubation time, exhibited a significant increase (2414.98± 84.02 U/g CHC) in xylanase production than before optimization.

Experimental and numerical study on the tensile, three-point-bending, and interlaminar fracture toughness of GLARE

Bassem Dahshan,Abdel-Halim M. El-Habbak,Mahmoud A. Adly,Mostafa Shazly 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8

Fiber metal laminates (FMLs) are a special type of composite structure consisting of metal sheets bonded to composite laminas. The current study investigated the effect of the replacement of cross-ply (0/90 ◦ ) glass fiber reinforced epoxy laminas with woven glass fiber reinforced polyester laminas in GLARE laminates on the tensile, bending and interlaminar fracture toughness of the laminate. Test results showed that the existence of woven glass fiber laminas increased the tensile strength with a decrease in corresponding strain, the flexure strength decreased significantly due to the existence of polyester instead of epoxy resin, and the mode I interlaminar fracture toughness increased. ABAQUS® software was used to simulate the tests, and ductile damage was employed to detect the failure of aluminum layers, the Hashin failure criteria to model the failure of composite layers in the laminate, and the cohesive surface interaction to capture delamination between layers.