Minyat an Naşr, Egypt
Minyat an Naşr, Egypt

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Hamed S.M.,Cairo University | Khalil A.H.,Cairo University | Abdelhalim M.B.,Arab Academy for Science and Technology | Amer H.H.,American University in Cairo | Madian A.H.,NCRRT
WSEAS Transactions on Circuits and Systems | Year: 2013

Analog-to-Digital Converters (ADCs) became an integral part in most systems. The Pipelined ADC (PADC) is one of the preferred ADCs; it is perfect for applications requiring high speed and medium resolution. Hence, the test of ADCs in general as well as PADCs is not only interesting but mandatory; the need for a low cost and efficient test technique in order to test the PADC is increasing. The focus in this paper is on proposing a new efficient test technique fitting an N-stage PADC test. The proposed technique depends on the selection of test inputs that can be applied to the first stage of the PADC and it is guaranteed that they can be regenerated at the input of next stages in the PADC. This proposed technique does not use complex hardware and there is no need to access the input or output of each individual stage. It will be shown that only two DC test inputs are able to detect all catastrophic faults in the N-stage PADC producing 100% fault coverage. The simulation results are based on circuit-level simulations using the Eldo simulator provided by Mentor Graphics.


Hamed S.M.,Cairo University | Khalil A.H.,Cairo University | Abdelhalim M.B.,Arab Academy for Science and Technology | Amer H.H.,American University in Cairo | Madian A.H.,NCRRT
National Radio Science Conference, NRSC, Proceedings | Year: 2013

Nowadays, Analog to Digital converters are the main building blocks of mixed analog/digital signal circuits, hence testing ADC circuits has become mandatory. The pipelined Analog-to-Digital Converter (PADC) is widely used with its famous 1.5 bit/stage architecture. In this paper, a low-cost test is developed for a 5 bit PADC. The 5 bits PADC consists of 3-stage (1.5 bit/stage) PADC followed by a 2 bit flash ADC. Then, the digital output of the 4-stage PADC is followed by its time alignment and Digital Error Correction (DEC) circuits. They are based on a 90 nm CMOS technology. It is proved that only six DC test values can detect 96.3% of catastrophic faults in the fault set. An extra analog pin is required in order to achieve 100% fault coverage. The Eldo simulator provided by Mentor Graphics was used in the analysis. © 2013 IEEE.


PubMed | P.A. College, NCRRT, Cairo University and American University in Cairo
Type: Journal Article | Journal: Journal of advanced research | Year: 2016

Dynamic power estimation is essential in designing VLSI circuits where many parameters are involved but the only circuit parameter that is related to the circuit operation is the nodes toggle rate. This paper discusses a deterministic and fast method to estimate the dynamic power consumption for CMOS combinational logic circuits using gate-level descriptions based on the Logic Pictures concept to obtain the circuit nodes toggle rate. The delay model for the logic gates is the real-delay model. To validate the results, the method is applied to several circuits and compared against exhaustive, as well as Monte Carlo, simulations. The proposed technique was shown to save up to 96% processing time compared to exhaustive simulation.


The results of multi-angle ellipsometrical measurements of thermally evaporated Inx(As2Se3)1-x (x = 0, 0.01,0.05) films are presented. Optical parameters n and Es of thin Inx(As2Se3)1-x films show that indium atoms were incorporated into the host matrix of As2Se3 forming distinct features depending on the indium concentration. Refractive index, n, was found to decrease with the addition of In to the binary As2Se3. The real and imaginary parts of the dielectric function, ε′ and ε″ were also calculated from the obtained data and correlated with In concentration. It was found that ε′ decreases with the increase of In content while ε″ increases with the increase of In content. Absorption edge is shifted towards lower photon energy with the increase of In content. As a result, the optical energy gap decreases with increasing In content. This has been correlated with the chemical character of the additive as well as with the structural and bonding aspects of the amorphous composition. Nonlinear optical constants (χ(3) and n2) were determined from linear optical parameters using semi-empirical relations in the long wavelength limit. © 2015 Wroclaw University of Technology.


Amin G.A.M.,NCRRT
Journal of Optoelectronics and Advanced Materials | Year: 2011

This work reports on the characterization of Si and Ge layers deposited one after another using thermal deposition technique. The I-V characteristics of the Si/Ge samples were studied at different temperatures. The electrical resistance decreases with temperature in the range from 290K to 355K. The activation energy for electrical conduction was 0.31 eV. The temperature coefficient of resistance (TCR) was calculated for different temperatures and it was between 0.028 K -1 and 0.043 K -1. Optical absorption was measured for the Si/Ge samples and used to study the optical characteristics. γ-irradiation induced effect on optical absorption of Si/Ge samples kept at room temperature was also investigated. The absorption coefficient increases up to a dose of 15 kGy, further increase of the irradiation dose leads to an opposite behavior. Optical energy gap was found to decrease as a result of γ-irradiation up to a dose of 15 kGy and starts to increase for higher doses.


Guneidy R.A.,National Research Center of Egypt | Shahein Y.E.,National Research Center of Egypt | Abouelella A.M.K.,NCRRT | Zaki E.R.,National Research Center of Egypt | Hamed R.R.,National Research Center of Egypt
Ticks and Tick-borne Diseases | Year: 2014

Rhipicephalus (Boophilus) annulatus is a bloodsucking ectoparasite that causes severe production losses in the cattle industry. This study aims to evaluate the in vitro effects of tannic acid, hematin (GST inhibitors) and different plant extracts (rich in tannic acid) on the activity of the recombinant glutathione S-transferase enzyme of the Egyptian cattle tick R. annulatus (rRaGST), in order to confirm their ability to inhibit the parasitic essential detoxification enzyme glutathione S-transferase. Extraction with 70% ethanol of Hibiscus cannabinus (kenaf flowers), Punica granatum (red and white pomegranate peel), Musa acuminata (banana peel) (Musaceae), Medicago sativa (alfalfa seeds), Tamarindus indicus (seed) and Cuminum cyminum (cumin seed) were used to assess: (i) inhibitory capacities of rRaGST and (ii) their phenolic and flavonoid contents. Ethanol extraction of red pomegranate peel contained the highest content of phenolic compounds (29.95mg gallic acid/g dry tissue) compared to the other studied plant extracts. The highest inhibition activities of rRaGST were obtained with kenaf and red pomegranate peel (P. granatum) extracts with IC50 values of 0.123 and 0.136mg dry tissue/ml, respectively. Tannic acid was the more effective inhibitor of rRaGST with an IC50 value equal to 4.57μM compared to delphinidine-HCl (IC50=14.9±3.1μM). Gossypol had a weak inhibitory effect (IC50=43.7μM), and caffeic acid had almost no effect on tick GST activity. The IC50 values qualify ethacrynic acid as a potent inhibitor of rRaGST activity (IC50=0.034μM). Cibacron blue and hematin showed a considerable inhibition effect on rRaGST activity, and their IC50 values were 0.13μM and 7.5μM, respectively. The activity of rRaGST was highest for CDNB (30.2μmol/min/mg protein). The enzyme had also a peroxidatic activity (the specific activity equals 26.5μmol/min/mg protein). Both tannic acid and hematin inhibited rRaGST activity non-competitively with respect to GSH and competitively with respect to CDNB. While red pomegranate extracts inhibited rRaGST activity competitively with respect to GSH, uncompetitive inhibition was observed with respect to CDNB. © 2014 Elsevier GmbH.


Saad M.H.,NCRRT | Saleh H.I.,NCRRT | Konbor H.,NCRRT | Ashour M.,NCRRT
ICENCO'2011 - 2011 7th International Computer Engineering Conference: Today Information Society What's Next? | Year: 2012

Content-Based Image Retrieval (CBIR) considers the characteristics of the image itself, for example its shapes, colors and textures. The Current approaches to CBIR differ in terms of which image features are extracted. Recent work deals with combination of distances or scores from different and independent representations. Content-based image retrieval has many application areas such as, education, commerce, military, searching, biomedicine and web image classification. This paper proposes a new image retrieval system, which uses color and Shape descriptions information to form the feature vectors. Bhattacharyya distance and histogram intersection are used to perform feature matching. This framework integrates the yc bc r color histogram which represents the global feature and Fourier descriptor as local descriptor to enhance the retrieval results. The proposed technique is proper for precisely retrieving images even in deformation cases such as geometric deformations and noise. It is tested on a standard image databases such as Wang and UCID database. Experimental work show that the proposed approach improves the precision and recall of retrieval results compared to other approaches reported in literature. © 2011 IEEE.


Ibrahim M.M.,NCRRT | Fayek S.A.,NCRRT | Amin G.A.M.,NCRRT | Elnagar D.M.,NCRRT
Materials Science- Poland | Year: 2016

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott's condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the γ-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices. © Wroclaw University of Technology 2016.


Amin G.A.M.,NCRRT | Gregus J.,Comenius University | Zahoran M.,Comenius University
Materials Science in Semiconductor Processing | Year: 2012

Gamma(γ)-radiation induced effects in thin films of arsenic selenide (As 2Se 3) were investigated for possible applications in γ-radiation environment and/or γ-radiation dosimetry purposes. Thin film samples were fabricated using thermal evaporation. Optical properties of As 2Se 3 thin films were studied before and after irradiation. As a result of γ-irradiation, photodarkening of samples was observed for doses up to 10 4 Gy (10 kGy). Absorption coefficient was found to increase with increase of irradiation dose. Optical energy gap was found to decrease while the localized band tail width was found to increase with dose. SEM was used to examine irradiated films; small nucleation of the crystalline phase could be distinguished. Nucleation increases with dose indicating some local structural changes due to irradiation. Values of absorbance or absorption coefficient in the absorption edge region are suitable control parameters of the proposed dosimeter material. The observed changes in the optical properties suggest that As 2Se 3 thin film may be considered as an effective material for room temperature real time γ-radiation dosimetry for the relatively high dose industrial applications such as sterilization. © 2012 Elsevier Ltd. All rights reserved.


PubMed | NCRRT and National Research Center of Egypt
Type: Journal Article | Journal: Ticks and tick-borne diseases | Year: 2014

Rhipicephalus (Boophilus) annulatus is a bloodsucking ectoparasite that causes severe production losses in the cattle industry. This study aims to evaluate the in vitro effects of tannic acid, hematin (GST inhibitors) and different plant extracts (rich in tannic acid) on the activity of the recombinant glutathione S-transferase enzyme of the Egyptian cattle tick R. annulatus (rRaGST), in order to confirm their ability to inhibit the parasitic essential detoxification enzyme glutathione S-transferase. Extraction with 70% ethanol of Hibiscus cannabinus (kenaf flowers), Punica granatum (red and white pomegranate peel), Musa acuminata (banana peel) (Musaceae), Medicago sativa (alfalfa seeds), Tamarindus indicus (seed) and Cuminum cyminum (cumin seed) were used to assess: (i) inhibitory capacities of rRaGST and (ii) their phenolic and flavonoid contents. Ethanol extraction of red pomegranate peel contained the highest content of phenolic compounds (29.95mg gallic acid/g dry tissue) compared to the other studied plant extracts. The highest inhibition activities of rRaGST were obtained with kenaf and red pomegranate peel (P. granatum) extracts with IC50 values of 0.123 and 0.136mg dry tissue/ml, respectively. Tannic acid was the more effective inhibitor of rRaGST with an IC50 value equal to 4.57M compared to delphinidine-HCl (IC50=14.93.1M). Gossypol had a weak inhibitory effect (IC50=43.7M), and caffeic acid had almost no effect on tick GST activity. The IC50 values qualify ethacrynic acid as a potent inhibitor of rRaGST activity (IC50=0.034M). Cibacron blue and hematin showed a considerable inhibition effect on rRaGST activity, and their IC50 values were 0.13M and 7.5M, respectively. The activity of rRaGST was highest for CDNB (30.2mol/min/mg protein). The enzyme had also a peroxidatic activity (the specific activity equals 26.5mol/min/mg protein). Both tannic acid and hematin inhibited rRaGST activity non-competitively with respect to GSH and competitively with respect to CDNB. While red pomegranate extracts inhibited rRaGST activity competitively with respect to GSH, uncompetitive inhibition was observed with respect to CDNB.

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