Time filter

Source Type

Arish, Egypt

Elsaied H.,Toshiba Corporation | Abd Elrazzak M.M.,Almansoura University
MECAP'10, 1st Middle East Conference on Antennas and Propagation

This paper investigates and proposes novel planar microstrip low pass filters (LPF) employing EBG structures in the form of slots etched in the ground plane. The main feature of EBG structures is the existence of a band gap in the frequency spectrum of a propagating electromagnetic wave. In the present design, a band stop with a deep rejection ratio is obtained at the higher end of the pass band of the filters. The present LPF are designed with EBG lattice shapes include rectangular holes, split ring holes, triangular holes, complementary split ring resonator holes, circular holes, and 2-shape holes. The frequency responses of the filter include the scattering parameters, the input impedance, and the loss factors are obtained. The effect of the structure parameters such as the number of lattices, lattice shapes, lattice spacing, and the dielectric substrate thickness are studied. The numerical results obtained using an analytical technique with the aid of a numerical package based on the method of moment (MOM). © 2010-IEEE APS. Source

Abd-Elrazzak M.M.,Almansoura University
Progress In Electromagnetics Research C

In this work, the analysis and design of wideband microstrip yagi and bi-yagi antenna arrays with photonic band gap (PBG) is presented. By using the bi-yagi planar array, a high directive gain and a high front-to-back ratio are achieved in comparison with that of the single microstrip yagi structure. The current distribution, return loss, radiation pattern, and input impedance are calculated. For a single yagi, wide bandwidth up to 12.81% at 10.15 GHz is obtained. However, a high directive gain is achieved with the bi-yagi. The PBG structures force the antennas to have stop band at the higher end of the operating band. In addition, it increases the front-to back (F/B) ratio. The fi{dotless}nite difference time domain (FDTD) with the perfect matched (PML) and a numerical package based on the method of moment (MOM) are used in the present analysis and design. A closed form based on an approximate equivalent circuit is used to get approximate dimensions of the PBG structures. Source

El-Tarhouny S.A.,Taibah University | El-Tarhouny S.A.,Zagazig University | Almasry S.M.,Taibah University | Almasry S.M.,Almansoura University | And 4 more authors.
Histology and Histopathology

This study aimed to describe the prevalence of chorionic distal villous immaturity (DVI) in overt diabetic/gestational diabetic (OD/GD) women compared with normoglycemic ones and to analyze the relation of DVI index (DVII) to placental growth factor (PlGF) and soluble Fms-like tyrosine kinase 1 (sFlt-1). Three groups were studied; normoglycemics (n=21), OD (n=17) and GD (n=20). Maternal blood samples were evaluated regarding serum levels of PlGF and sFlt-1. Immunohistochemical methodologies were employed in term placentae of all subjects to assess DVII and area% of PlGF and sFlt-1 immunostaining. We found that mean Hemoglobin A1c (HbA1c) is 5.22±0.15 in normoglycemics, 6.2±0.3 in OD, and 5.70±0.23 in GD with significant differences between groups (p=0.012). DVII was significantly higher in OD (66.6±4.7) and GD (72.4±4.5) compared to controls (11.6±2.5; p=0.000). Healthy women have significantly lower levels of PlGF (86.6±14.5) compared to OD (166.6±22.4, p=0.000) and GD (150.3±23.97, p=0.000) and their placentae expressed a significantly lower area% of PlGF (6.5±0.8) compared to OD (14.8±1.0, p=0.000) and GD (18.8±1.3, p=0.000). Also, normoglycemic women have significantly lower levels of sFlt-1 (108.9±12.1) compared to OD (226.5±18.6, p=0.000) or GD (197.2±16.8, p=0.000) and their placentae expressed a significantly lower area% of sFlt-1 (3.2±0.3) compared to OD (15.4±1.7, p=0.000) and GD (16.9±1.2, p=0.000). There was significant correlation between DVII and both serum level and area% of PlGF and sFlt-1 expression in the 3 groups. This study provided a new score for evaluating DVI in normal and diabetic placentae and suggested a role for PlGF and sFlt-1 in regulation of DVI in diabetic pregnancies. Source

Elfayomy A.K.,Taibah University | Elfayomy A.K.,Zagazig University | Almasry S.M.,Taibah University | Almasry S.M.,Almansoura University
Journal of Molecular Histology

This study aimed to explore whether the altered expression of tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) and apoptotic changes in mid zone (MZ) and rupture zone (RZ) of fetal membranes (FM) are regulatory mechanisms associated with labor at term. Fifteen FM specimens were collected after vaginal deliveries and 13 specimens after elective caesarian section. Histological and immunohistochemical analysis were employed. Area percent of TNF-α and VEGF immunostaining and apoptotic index (AI) were evaluated using image analysis. The statistical data revealed significantly higher area % for TNF-α, VEGF immunoexpression and AI in labor compared to non-labor specimens (p < 0.0001). There was a significantly higher percentage of TNF-α immunoexpressed area in MZ compared with RZ in both groups (p < 0.0001). VEGF expression in RZ of both groups proved nearly double or triple the area % of expression relative to MZ with highly significant difference (p < 0.0001). quantitative analysis revealed near two fold increase in the AI in RZ (13.42 % ± 1.2 in labor; 11.20 % ± 0.96 in non-labor groups) when compared to MZ (7.20 % ± 0.6 in labor; 5.08 % ± 0.76 in non-labor groups) with highly significant zonal difference (p < 0.0001). Correlation analysis revealed significant correlation between apoptotic indices and area % of TNF-α (r = 0.575, p = 0.002 in non-labor; r = 0.652, p < 0.0001 in labor) and VEGF (r = 0.795, p < 0.0001 in non-labor; r = 0.668, p < 0.0001 in labor). In conclusion, Apoptosis may be regulated by TNF-α and VEGF expression in FM at labor. MZ is a step back from RZ and could participate actively in rupture of the FM during labor. TNF-α and VEGF increase with onset of labor and differentially expressed in the RZ and the MZ. These findings call for further study with tissue cultures or animal models. © 2013 Springer Science+Business Media. Source

Abd-Elrazzak M.M.,Almansoura University | Al-Nomay I.S.,King Abdulaziz City for Science and Technology
2010 9th International Symposium on Antennas Propagation and EM Theory, ISAPE 2010

This paper presents a design of a multiband microstrip circular patch antenna. The antenna of a single patch is designed for the operation at 2.45 GHz and 5.2 GHz ISM (industrial, scientific, and medical) band. This band is occupied by the bluetooth and high performance radio local area network (HIPERLAN) applications. In addition, with the aid of a circular array, the previous antenna can be designed to operate in a place of x band (8.4 GHZ) used by the spacecraft-to-ground communication link. The return loss, input impedance, and the radiation pattern are calculated. Under the condition of the return loss is less than 10dB, the bandwidth at 2.45, 5.2 and 8.4 GHz are 24 %, 7.7%, and 6.7%, respectively. The analysis and design of the antenna is carried out using of the finite difference time domain (FDTD) with the perfect matched layer (PML) in addition to a numerical package based on the method of moment (MOM). The obtained results are compared with the available published data and the results of the cavity resonance technique. Good agreements are found. ©2010 IEEE. Source

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