Electronic Simulation of Neutronic Transient Studies for PWR-900 MW(e)

To study different functionalities of the PWR-900 MW(e) reactor core, an electronic model of Simulation Program with Integrated Circuit Enfesied (PSPICE) for electronic circuit design was adopted to model the mathematical models. A classical breadboard electronically simulates the physical terminal characteristics of each network. The electronic simulator, parity simulator, for reactor core can simulate six-delayed neutron groups, single prompt neutron, neutron source, fuel channel, the coolant, reactor poisons, temperature feedback, control rods, safety rods, and boron injection. Positive/negative step or sin reactivity functions are two case studies were analyzed. The obtained results were found to be in a good agreement with the available data of El-Dabaa PWR 900 MW(e) basic simulator.     

Solution of pressure diffusion in radially composite reservoirs

This paper presents a new general method for solving the pressure-diffusion equation in cylindrically radial composite reservoirs, where the rock and fluid properties may change radially as a function ofr. Composite systems, such as formations with wellbore filtrate invasion and reservoirs with peripheral water encroachment, can be encountered as a result of drilling, secondary oil recovery, and water influx.The new solution method utilizes the reflection and transmission concept of electromagnetics to solve fluid flow problems in three-dimensional cylindrically radial reservoirs, where heterogeneity is in only one direction. The Green's function for a point source in a three-dimensional radially composite system is developed by using the reflection and transmission method. The method as well as the point source solution are sufficiently general that they may be applied to similar fluid flow and well testing problems involving single-phase flow.     

The class of infinite dimensional neat reducts of quasi‐polyadic algebras is not axiomatizable

SC, CA, QA and QEA denote the classes of Pinter's substitution algebras, Tarski's cylindric algebras, Halmos' quasi‐polyadic algebras and quasi‐polyadic equality algebras, respectively. Let ω ≤ α < β and let K ∈ {SC,CA,QA,QEA}. We show that the class of α ‐dimensional neat reducts of algebras in K_β is not elementary. This solves a problem in [3]. Also our result generalizes results proved in [2] and [3]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Use of iodide and silver/sulfide ion-selective electrodes for the determination of some tertiary amines and alkaloids

Summary Some tertiary amines and alkaloides were determined by reaction with methyl iodide at 43 °C. The produced quaternary ammonium iodide salts were potentiometrically titrated with standard silver nitrate solution using either the iodide or silver/sulfide ion-selective electrode. The effects of solvent, temperature and time of reaction were examined. An average recovery of 99.0% and 98.9% with standard deviations of 0.73 and 0.52 were obtained for the studied amines and alkaloides, respectively.

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Verwendung der Iodid-bzw. Silber/Sulfid-selektiven Elektrode zur Bestimmung einiger tertiärer Amine und Alkaloide

     

Fluorimetric determination of iron(III) by quenching the luminescence of the zinc-morin-Triton X-100 system

Summary Simple and highly sensitive fluorimetric methods for iron determination are described. The methods are based on quenching the fluorescence of an aqueous morin solution or zinc-morin-Triton X-100 ternary system. The fluorescence emission is measured at 500 and 503 nm (wavelength of excitation 420 and 433 nm) for morin and the ternary system, respectively. The quenching calibration graphs are linear over the range 0–250 and 0–55 ng Fe/ml and the iron detection limits are 20 and 5 ng/ml using morin and zinc-morin-Triton X-100 system, respectively. The influence of experimental variables such as pH, reagent and surfactant concentrations, temperature, standing time and diverse ions are studied to obtain the optimum conditions. The method has been applied to the determination of iron in aluminium metal.

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Fluorimetrische Eisen(III)-bestimmung durch Luminescenzlöschung des Systems Zink-Morin-Triton X-100

     

Chemical and Physical Analysis of Acetate-Oxide Sol-Gel Processing Routes for the Y-Ba-Cu-O System

The formation of three sols by fluorine-free aqueous and non-aqueous processes were analyzed and modified to vary the chemical properties of the sols (inks) to suit a variety of deposition processes such as dip-coating and ink-jet coating/printing. Ink-jet printing requires high wetting angles; choosing the right complexing agents to modify the ink allows the formation of droplets with high wetting angles on the surface. Dip-coating and ink-jet coating require low wetting angles; additives added to the sols reduce wetting angles to 10^∘ and allow complete coverage of the substrate surface. The deposition theories and requirements are briefly discussed, as are some initial tests with the printing and converting of the developed superconducting inks.     

On the Mechanism of Oxazoline-Directed Metalations: Evidence for Nitrogen-Directed Reactions

We recently described a method for the synthesis of ferrocene complexes possessing planar chirality which relies on the asymmetric deprotonation of chiral ferrocenyloxazolines. The unexpected stereochemical outcome of these reactions led us to examine whether the metalation is directed by the oxygen or the nitrogen of the oxazoline. In this paper, we describe the synthesis of a constrained ferrocenyloxazoline (compound 13) in which oxygen- and nitrogen-directed metalations provide different stereochemical outcomes. Our results show that nitrogen is responsible for the directive effects of the oxazoline when alkyllithium reagents are used to deprotonate the ferrocene. The implications of this result on the origin of asymmetric induction in the metalation of the unconstrained ferrocenyloxazolines 19 and 20 are discussed.     

A SiCl4-ZnCl2 induced general, mild and efficient one-pot, three-component synthesis of β-amido ketone libraries

A general, mild and efficient protocol for the synthesis of β-amido ketone libraries was achieved utilizing tetrachlorosilane and zinc chloride in dichloromethane at ambient temperature via a one-pot, three-component condensation of various aldehydes, ketones and nitriles.     

Polyurethane‐nanocomposite materials via in situ polymerization into organoclay interlayers

New nanocomposite materials based on polyurethane intercalated into organoclay layers have been synthesized via in situ polymerization. The syntheses of polyurethane–organoclay hybrid films were carried out by swelling the organoclay [12‐aminododecanoic acid montmorillonite] into different kinds of diols followed by addition of diisocyanate then casting in a film. The homogeneous dispersion of MMT in the polymer matrix is evidenced by scanning electron microscope and x‐ray diffraction, which showed the disappearance of the peak characteristic to d₀₀₁ spacing. It was found that the presence of organoclay has improved the thermal, solvent resistance and mechanical properties. Also, the tensile strength is increased with increasing the organoclay contents to 20% by the ratio 182% related to the PU with 0% organoclay. On the contrary, the elongation has decreased with increasing the organoclay contents. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of 6-Heterocyclically Appended Tri-<Emphasis Type="Italic">O</Emphasis>-methyl Protected 6-Desmethyl Emodin Derivatives

Summary. A convenient synthesis of several 6-heterocyclically appended tri-O-methyl 6-desmethyl emodin derivatives including the tetrazolyl, oxazolyl, oxazolinyl, benzimidazolyl, benzoxazolyl, and benzothiazolyl derivatives of potential biological and medicinal interest was achieved starting from the tri-O-methyl protected emodin aldehyde or nitrile. In addition, these derivatives could serve as synthons for heterocyclic hypericin derivatives.