Yehia Badr

Abstract Free convection over a vertical rectangular duct filled with porous matrix with variable viscosity and variable thermal conductivity is studied in this paper. We consider the two-dimensional steady laminar flow and Brinkman–Forchheimer extended Darcy model to define the porous medium. Using the appropriate variables the basic governing equations are transformed to non-dimensional governing equations. The fluid viscosity is assumed to vary exponentially with temperature whereas the thermal conductivity is assumed to vary linearly with temperature. One of the vertical walls of the duct is cooled with constant temperature while the other wall is heated to constant but different temperature. The governing coupled nonlinear momentum and energy equations are solved numerically using finite difference method. The effect of pertinent parameters such as variable viscosity, variable thermal conductivity, Darcy number, inertial parameter, Grashof number, Brinkman number and aspect ratio on the velocity, temperature, volumetric flow rate, shear stress and heat transfer are discussed.

Abstract Silica nanostructured materials are often used as catalyst support but their catalytic role has not been deeply investigated yet. In the present study, the photocatalytic degradation of acridine orange zinc chloride double salt (AO) has been studied using silica nanoparticles (NPs) as catalysts. \{NPs\} of different size (55 and 146 nm) were prepared by a sol–gel procedure and their surface was modified with amino groups to investigate the role of the chemical groups linked to the silica surface on the dye degradation. The silica nanomaterials were fully characterized by use of transmission electron microscopy (TEM), zeta potential measurements and UV–vis spectrophotometric methods. The photodegradation experiments were carried out irradiating at 313 or 490 nm for 50 min the aqueous samples containing the dye and the silica \{NPs\} of 55 or 146 nm in diameter. The photocatalytic degradation of the dye was determined from the decrease of its fluorescence intensity. \{AO\} fluorescence intensity did not change when bare SiO2 beads were used as catalysts, whereas an efficient decoloration (up to 58%) was achieved with amino functionalized NPs, with a photodegradation rate constant value of 0.136 m−1. The data collected from the degradation experiments demonstrated that the functional groups on the silica surface have a fundamental role in the efficiency of the degradation processes.

Two types of coeval acid-intermediate rocks with different petrological, geochemical and isotopic features have been discovered among volcanic rocks and surrounding synkinematic tonalite–trondhjemite–granodiorite (TTG) plutons of Late Archaean greenstone belts in the Karelian granite–greenstone terrane. Type-1 rocks comprise trondhjemites and sub-volcanic, occasionally volcanic dacite–rhyolite rocks. They are characterized by high Sr, low Y and \{HREE\} contents, high Sr/Y ratios, and strongly fractionated \{REE\} patterns with no significant positive or negative Eu anomaly. Initial ɛNd is positive, indicating a generation from juvenile source with little or no contribution of ancient continental crust. Type 2 is represented by diorite–granodiorites and calc-alkaline basalt–andesite–dacite–rhyolite (BADR) series. As compared to type 1, these rocks differ by their lower Sr, higher Y and \{HREE\} contents, lower Sr/Y ratios and less fractionated \{HREE\} patterns with negative Eu anomalies. Initial ɛNd varies from negative to positive values, thus indicating a variable contribution of sialic crust. Geochemistry of the two magmatic series suggests their formation in a convergent plate margin setting. The type-1 rocks resemble Phanerozoic adakites, which represent slab-derived melts contaminated by overlying mantle wedge. The type-2 rocks resemble \{BADR\} series, which were derived from a mantle wedge metasomatized by slab-derived fluids and melts, with subsequent variable crustal contamination. The spatial distribution of these two types of magmatic series defines the asymmetry of the studied granite–greenstone structures, which presumably reflects the primary lateral zoning of island arc formed under specific thermal conditions in the Archaean mantle. Adakite melts upraised to the surface in the frontal part of the island arc, where mantle wedge was thin, showing no or little interaction with metasomatized mantle, and formed adakite-type plutonic and sub-volcanic rocks. At greater depths, adakitic melts and fluids interacted with the overlying mantle wedge and caused its partial melting with generation of calc-alkaline \{BADR\} volcanic rocks and diorite–granodiorite plutons in the rear part of the island arc. Our data suggest that greenstone belt volcano-plutonic arcs were initiated on different types of crust, which presumably determined the petrogenetic and isotope variations of the studied BADR- and adakite-type island-arc complexes.

Abstract Cyproheptadine hydrochloride (CYP HCl) {4-(5H-dibenzo[a,d]-cyclohepten-5-ylidene)-1-methylpiperidine hydrochloride} is a first-generation antihistamine with additional anticholinergic, antiserotonergic, and local-anesthetic properties. The geometry optimization, Mulliken atomic charges and wavenumber and intensity of the vibrational bands of all of the possible modes of \{CYP\} \{HCl\} have been calculated using ab initio Hartree–Fock (HF) and density functional theory (DFT) employing the \{B3LYP\} functional with the 6-311G(d,p) basis set. We have compared the calculated İR\} and Raman wavenumbers with experimental data. Quantum-chemical calculations of the geometrical structure, energies, and molecular electrostatic potential and \{NBO\} analysis of \{CYP\} \{HCl\} have been performed using the B3LYP/6-311G(d,p) method. The electric dipole moment (μ), static polarizability (α) and the first hyperpolarizability (β) values of the title compound have been computed using \{HF\} and \{DFT\} methods. The study reveals that the antihistaminic pharmacological property of \{CYP\} \{HCl\} has a large β value and, hence, may in general have potential applications in the development of non-linear optical materials. The experimental and calculated results for \{CYP\} \{HCl\} have also been compared with those for mianserin HCl.

Abstract This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a \{PDMS\} support that contains the Berthelot's reaction reagents. To prepare the PDMS–thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the \{PDMS\} matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS–thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4+ could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LOD < 0.4 mg L− 1) and reproducibility (RSD < 10%) for the rapid detection of ammonium. The PDMS–NH4+ sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter \{PM10\} samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS–NH4+ sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods.

In this paper, we describe research to extend the capability of an existing talking head, Baldi, to be multilingual. We use parsimonious client/server architecture to impose autonomy in the functioning of an auditory speech module and a visual speech synthesis module. This scheme enables the implementation and the joint application of text-to-speech synthesis and facial animation in many languages simultaneously. Additional languages can be added to the system by defining a unique phoneme set and unique phoneme definitions for the visible speech for each language. The accuracy of these definitions is tested in perceptual experiments in which human observers identify auditory speech in noise presented alone or paired with the synthetic versus a comparable natural face. We illustrate the development of an Arabic talking head, Badr, and demonstrate how the empirical evaluation enabled the improvement of the visible speech synthesis from one version to another.

Medieval Arabic algebra books intended for practical training generally have in common a first “book” which is divided into two sections: one on the methods of solving simplified equations and manipulating expressions, followed by one consisting of worked-out problems. By paying close attention to the wording of the problems in the books of al-Khwārizmī, Abū Kāmil, and Ibn Badr, we reveal the different ways the word māl was used. In the enunciation of a problem it is a common noun meaning “quantity,” while in the solution it is the proper noun naming the square of “thing” (shay '). We then look into the differences between the wording of enunciations and equations, which clarify certain problems solved without “thing,” and help explain the development of algebra before the time of al-Khwārizmī.

Abstract In laser beam machining with oxygen gas, striations are formed on the cut surface due to the cyclic oxidization reaction, which is affected by the cutting conditions and the thermal properties of the workpiece. The formation of striations causes an increase in surface roughness. In order to reduce the surface roughness, we propose controlling the formation of striations by utilizing multi-DOF oscillation of the focus position of the laser. In this paper, we construct a laser machining system in which positioning control of the focus position is achieved by driving the focal lens. The effect of orbital oscillation of the laser focus position parallel to the top surface of the workpiece and vertical oscillation perpendicular to this surface on the formation of striations was evaluated by performing laser cutting tests on thick mild steel plates. The experimental results show that control of the formation of striations can be realized by choosing the appropriate oscillation conditions. The surface roughness with oscillation was less than half that without oscillation.