Showing papers by "Ain Shams University published in 1995"

Mutations in the gene for transglutaminase 1 in autosomal recessive lamellar ichthyosis

Abstract: We recently mapped the disease locus for severe autosomal recessive lamellar ichthyosis (LI) to chromosome 14q11 and showed complete linkage with TGM1, the gene encoding transglutaminase 1. We have now identified point mutations in TGM1 in two of the multiplex LI families used in the linkage study. Each nucleotide change causes a non–conservative amino acid substitution of histidine for one of two adjacent arginine residues in exon 3 of the gene (Arg141His, Arg142His). Within the transglutaminase family, these arginines are invariant within a conserved region, distant from the catalytic site of the enzyme. We hypothesize that these mutations adversely affect formation of crosslinks essential in production of cornified cell envelopes and a normal stratum corneum layer of the skin.

Superposed deformation in the northern suez rift, egypt: relevance to hydrocarbons exploration

Abstract: Detailed subsurface studies of the northern part of the Suez Rift and adjacent areas indicate the superposition of two different episodes of deformation. During the earlier (Late Cretaceous) phase of deformation, folds with NE-SW oriented axes were formed in northern Egypt as a result of convergence between Africa and Eurasia and the closure of the Neotethys. During the later (early Miocene) deformation, NW-oriented normal faults were formed as a result of the opening of the Suez Rift.

Potentiometric anion selectivity of polymer membranes doped with palladium organophosphine complex.

Abstract: The potentiometric anion selectivity of polymer membrane-based electrodes formulated with a palladium organophosphine complex (benzylbis(triphenylphosphine)palladium(II) chloride) as the membrane active component is examined. The electrode is shown to exhibit a non-Hofmeister selectivity pattern with a significantly enhanced response toward nitrite over the concentration range of 10 microM-10 mM (log-linear range) and a detection limit 5.0 microM. The effect of lipophilic anionic (tetraphenylborate derivatives) and cationic (tetraalkylammonium) site additives within the membrane on the anion selectivity is examined in detail. Addition of both cationic and anionic sites is shown to improve potentiometric anion selectivity, suggesting that the palladium complex may operate simultaneously as a neutral and charged carrier-type ionophore within the polymer membrane phase. Using optimal membrane formulations (with added 20-30 mol % cationic sites), the sensors prepared with the palladium complex do not exhibit proton/hydroxide response in the range of pH 3.5-12, a potential advantage over previously reported nitrite electrodes prepared with Co(III) corrins and porphyrin complexes.

Combined micro-endoscopic trans-sphenoid excisions of pituitary macroadenomas.

Abstract: Refined microsurgical techniques with the operating microscope have greatly facilitated removal of pituitary tumors by the trans-sphenoid approach. However, extensions of macroadenomas in presellar and parasellar regions and in the lateral recesses of the sphenoid sinuses can be partially hidden, resulting in their removal by relatively blind curettage. In 37 patients with pituitary macroadenomas, the rigid 30° angled fiberoptic nasoscope fitted to a suction-irrigation sheath was found to be highly beneficial. Hidden areas could be visualized in 84% of the patients and tumor residues detected in 40.5%. In the majority of the patients with detected tumor residues, adenomatous remnants were safely removed by meticulous endoscopic dissection under optimum visual control after the main part of the tumor had been removed with the operating microscope.

Optical, infrared and electrical conductivity of glasses in the TeO2-B2O3 system

Abstract: Infrared (IR) and optical absorption spectra were measured in order to study the structure of some tellurite glasses containing boric oxide. The compositions (mol%) were (100-X) TeO2,XB2O3 whereX=5, 10, 20, 25, 30. The optical spectra were measured at room temperature in the wavelength range 350–450 nm, and the results show that the fundamental absorption edge is a function of composition, with the optical absorption due to indirect transitions. The optical band gap increases with increasing B2O3 content. The validity of the Urbach rule was investigated. The IR results prove the distribution of the TeO4 polyhedra which determines the network and the basic oscillations of the building units in the tellurite glasses. The IR results also prove the distribution of the boroxal group. The electrical conductivity was measured as a function of temperature in the temperature range (300–573 K). Both the conductivity and activation energy were found to be a function of added oxide type.

I.v. tenoxicam for analgesia during Caesarean section

Abstract: We have studied the analgesic efficacy of a single i.v. dose of tenoxicam 20 mg, given 10 min before induction of anaesthesia in 25 patients undergoing elective Caesarean section. Another group of 25 similar patients served as controls. Nalbuphine consumption in the first 24 h after operation was reduced by 50% when tenoxicam was given. The median time to first request for analgesia was increased from 25 to 110 min in the tenoxicam group. Subjective experiences of pain and sedation were significantly greater in the control group up to 24 h after operation. The haemodynamic variability after intubation was of shorter duration in the tenoxicam group. There was no significant difference in incidence and severity of postoperative nausea and vomiting between the two groups. The surgeon's assessment of uterine relaxation and bleeding, using a visual analogue score, and infant well-being, as judged by Apgar score and cord blood-gas analysis, showed no significant difference between the two groups. There was no evidence of premature closure of the ductus arteriosus or pulmonary hypertension. We conclude that a single i.v. dose of tenoxicam is a useful pretreatment to minimize the haemodynamic variability of light general anaesthesia at induction-delivery and in reducing 24 h postoperative opioid consumption.

Optical properties of tin-selenid films

Abstract: SnSe thin films of different thicknesses were prepared by the thermal evaporation technique in vacuum of 10−4 Pa. The structure analysis of the films as determined from the electron diffraction pattern and X-ray diffraction indicate that the films were polycrystalline of orthorhombic structure. The transmittance and reflectance of SnSe films were measured at normal incidence in the wavelength range of 760–2200 nm. It was found that the refractive index n and the absorption index k are independent of the film thickness. Graphical representation of log(α) as a function of (1/λ) shows two distinct linear parts indicating the existence of two optical transitions. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region revealed an indirect and direct allowed transition with energy gaps Egind = 0.895 eV and Egd = 1.27, respectively.

Evaluation of a recombinant antigen-based antibody assay for diagnosis of bancroftian filariasis in Egypt.

Abstract: (1995). Evaluation of a recombinant antigen-based antibody assay for diagnosis of bancroftian filariasis in Egypt. Annals of Tropical Medicine & Parasitology: Vol. 89, No. 4, pp. 443-446.

Pulsatile Magnetohydrodynamic Viscoelastic Flow through a Channel Bounded by Two Permeable Parallel Plates

Abstract: Velocity profiles for unsteady pulsatile laminar flows of viscoelastic non-Newtonian conducting fluids through a channel have derived using the perturbation method The induced magnetic field and wall shear have been obtained The effects of pulsation, elasticity and the magnetic parameter on the velocity, induced magnetic field and wall shear are discussed Results are illustrated numerically and graphically It is found that amplitude of the pulsation increases the velocity distribution which would be obtained under steady flow conditions at the same mean pressure gradient The effect of both the magnetic and elasticity parameters decrease the velocity distribution Also the properties of the fluid on the induced magnetic field and the skin-friction are discussed

Passivity and passivity breakdown of zinc anode in alkaline medium

Abstract: The electrochemical behaviour of zinc in NaOH solutions has been investigated by using potentiodynamic technique and complemented by X-ray analysis. The E/i curves exhibit active, passive and transpassive regions prior to oxygen evolution. The active region displays two anodic peaks. The passivity is due to the Formation of a compact Zn(OH)2 film on the anode surface. The transpassive region is assigned to the electroformation of ZnO2. The reverse sweep shows an activation anodic peak and one catholic peak prior to hydrogen evolution. The influence of increasing additives of NaCl, NaBr and Nal on the anodic behaviour of zinc in NaOH solutions has been studied. The halides stimulate the active dissolution of zinc and tend to break down the passive film, leading to pitting corrosion. The aggressiveness of the halide anions towards the stability of the passive film decreases in the order: I− > Br− > Cl−. The susceptibility of zinc anode to pitting corrosion enhances with increasing the halide ion concentration but decreases with increasing both the alkali concentration and the sweep rate. Passivitat und Passivitatsverlust von Zinkanoden im alkalischen Medium Das elektrochemische Verhalten von Zink in NaOH-Losungen wurde mittels potentiodynamischer Messungen und erganzenden Rontgenanalysen untersucht. Die E/i-Kurven weisen vor der Sauerstoffentwicklung aktive, passive und transpassive Bereiche auf. Der aktive Bereich zeigt zwei anodische Maxima. Die Passivitat wird durch die Bildung eines kompakten Zn(OH)2-Films auf der Anodenoerflache bewirkt. Der transpassive Bereich ist durch die Bildung von ZnO2 gekennzeichnet. Der Rucklauf zeigt ein anodisches Maximum sowie ein kathodisches Maximum vor der Wasserstoffentwicklung. Des weiteren wurde der Einflus steigender Zugaben von NaCl, NaBr and Nal auf das anodische Verhalten von Zink in NaOH-Losungen untersucht. Die Halogenide stimulieren die aktive Auflosung des Zinks und neigen daze, den Passivfilm zu zerstoren, was zu Lochfras fuhrt. Die Aggressivitat der Halogenidionen bezuglich der Stabilitat des Passivfilms nimmt in der Reihenfolge I− > Br− > Cl− ab. Die Empfindlichkeit der Zinkanode erhoht sich mit zunehmender Halogenidionenkonzentration und sinkt sowohl mit steigender Alkalikonzentration als auch mit steigender Potentialanderungsgeschwindigkeit.

Impact of LDD structures on the operation of silicon MOSFETs at low temperature

Abstract: The impact of Lightly Doped Drain structures (LDD) on the electrical characteristics of Si MOS transistors is investigated from liquid helium up to room temperature. It is found that the presence of LDD regions strongly alters the ohmic drain current characteristics at low temperatures ( ≤ 100 K). This feature is attributed to the increase of the source-drain series resistance due to the impurity freeze-out which takes place in the LDD regions. In contrast, it is also found that, for sufficiently high drain and gate voltages, the drain current is only weakly affected by the presence of LDDs. The analysis of the drain current and output conductance characteristics allows us to demonstrate that the LDD resistance is indeed a non-linear function of the longitudinal electric field. The above LDD resistance dependence with electric field is interpreted in term of field assisted impurity ionization which occurs in the LDD regions. The mechanisms responsible for the field assisted impurity ionization are discussed with regard to the Poole-Frenkel effect and the shallow level impact ionization process. Moreover, a simple model for the field dependent LDD resistance is proposed and makes it possible to explain quantitatively the change of the output conductance with temperature for MOS devices operated at low and very low temperatures.