Entity

Time filter

Source Type


Mitwally M.E.,Kyoto University | Tsuchiya T.,Kyoto University | Tabata O.,Kyoto University | Sedky S.,Zewail City of Science and Technology
Microsystem Technologies | Year: 2016

Microscale silicon structures oriented along <100> and <110> orientations were laser treated with different conditions with the cross section shape and tensile strength investigated after the treatment. Finite element simulation was performed to examine the temperature distribution at different conditions during laser treatment. Using a low energy (1.2 J/cm2) and high tilt angle (65°) led to a more preserved cross section with a slight strength improvement. The strength improvement was limited due to other surfaces that were not affected by laser treatment. An improvement of 30 % in tensile strength was achieved with a higher energy (4 J/cm2) lower tilt angle (45°) treatment that was consistent for different sample orientations. The cross section of the samples treated at such condition was significantly changed however. The effect of sample orientation on fracture behaviour was studied and unstable crack propagation was observed for <100> oriented samples that was more significant after laser treatment. © 2015, Springer-Verlag Berlin Heidelberg. Source


Fadda A.A.,Mansoura University | Bayoumy N.M.,Delta University for Science and Technology | El-Sherbiny I.M.,Zewail City of Science and Technology
Drug Development and Industrial Pharmacy | Year: 2016

The present work reports the synthesis of a new series of pyridopyrimidine derivatives. The newly synthesized compounds were characterized by various analytical and spectral techniques. In addition, their antimicrobial activity was evaluated as well as modeling studies were performed to investigate their ability to recognize and bind to the biotin carboxylase (BC)-active site. The results showed a broad spectrum antibacterial and antifungal profile of the synthesized derivatives. Docking results demonstrated that all members of this class of new derivatives were able to recognize the active site of Escherichia coli BC and form different types of bonding interactions with key active site amino acid residues. Besides the compounds with promising antimicrobial activity in addition to 6-aminothiouracil, as control, were incorporated into polycaprolactone nanoparticles to improve their water solubility, permeability through physiological barriers and consequently enhanced therapeutic efficacy. The compounds-loaded nanoparticles were prepared using single emulsion-solvent evaporation technique, and their diameters were found to be in the range 136 ± 30 to 213 ± 28 nm. Transmission electron microscopy (TEM) showed a spherical and dense morphology of the nanoparticles. The results also showed high entrapment efficiency of the synthesized bioactive compounds in the nanoparticles (85 ± 5% to 91 ± 2%) with a desirable in vitro biodegradation and release profiles. © 2015 Taylor & Francis. Source


Mitwally M.E.,Kyoto University | Tsuchiya T.,Kyoto University | Tabata O.,Kyoto University | Sedky S.,Zewail City of Science and Technology
Microsystem Technologies | Year: 2015

Microscale silicon structures oriented along <100> and <110> orientations were laser treated with different conditions with the cross section shape and tensile strength investigated after the treatment. Finite element simulation was performed to examine the temperature distribution at different conditions during laser treatment. Using a low energy (1.2 J/cm2) and high tilt angle (65°) led to a more preserved cross section with a slight strength improvement. The strength improvement was limited due to other surfaces that were not affected by laser treatment. An improvement of 30 % in tensile strength was achieved with a higher energy (4 J/cm2) lower tilt angle (45°) treatment that was consistent for different sample orientations. The cross section of the samples treated at such condition was significantly changed however. The effect of sample orientation on fracture behaviour was studied and unstable crack propagation was observed for <100> oriented samples that was more significant after laser treatment. © 2015 Springer-Verlag Berlin Heidelberg Source


Khirallah K.,American University in Cairo | Ramsis I.,American University in Cairo | Serry M.,American University in Cairo | Swillam M.A.,American University in Cairo | Sedky S.,Zewail City of Science and Technology
Optics Communications | Year: 2013

In this paper, we propose a novel design of Micro-Electro-Mechanical System MEMS based Fourier transform spectrometer. This design is based on spatial truncation of the input Gaussian beam into two symmetric semi-Gaussian beams using V shape mirror. The design is fully integrated and can operate in the Infrared and visible region. The analysis shows that, a minimum resolution of 9 nm at wavelength 1.45 μm and mechanical displacement of 160 μm is achievable. Unlike the traditional Michelson interferometer which returns half of the optical power to the source, this design uses the full optical power to get one original and two complementary interferograms. Here, analytical model that describes the beams propagation and interference is derived using Fourier optics techniques and verified using Finite Difference Time Domain (FDTD) method. Then, a mechanical model that describes the mirror displacement to produce optical path difference is derived and verified using finite element method (FEM). Finally, the effect of different design parameters on the interference pattern, interferograme and resolution are alsoshown. © 2013 Elsevier B.V. Source


Serry M.,American University in Cairo | Rubin A.,King Abdullah University of Science and Technology | Ibrahem M.,American University in Cairo | Sedky S.,Zewail City of Science and Technology
Journal of Microelectromechanical Systems | Year: 2013

This paper reports on the use of p-type polycrystalline silicon germanium (poly-Si1-xGex) thin films as a new masking material for the cryogenic deep reactive ion etching (DRIE) of silicon. We investigated the etching behavior of various poly-Si1-xGex:B (01:800). Furthermore, the SiGe mask was etched in SF6/O2 plasma at temperatures ≥ - 80°C and at rates exceeding 8 μm/min (i.e., more than 37 times faster than SiO2 or SiN masks). Because of the chemical and thermodynamic stability of the SiGe film as well as the electronic properties of the mask, it was possible to deposit the proposed film at CMOS backend compatible temperatures. The paper also confirms that the mask can easily be dry-removed after the process with high etching-rate by controlling the ICP and RF power and the SF6 to O2 ratios, and without affecting the underlying silicon substrate. Using low ICP and RF power, elevated temperatures (i.e., > - 80°C), and an adjusted O2:SF6 ratio (i.e., ~6%), we were able to etch away the SiGe mask without adversely affecting the final profile. Ultimately, we were able to develop deep silicon- trenches with high aspect ratio etching straight profiles. © 1992-2012 IEEE. Source

Discover hidden collaborations