An Efficient Method for the Synthesis of 3-Cyano-6-hydroxy-2(1H)-pyridinones under Microwave Irradiation and Solvent-free Conditions

Summary. Three component condensation of alkylacetoacetates, primary amines, and alkyl cyanoacetates catalyzed by solid supports under microwave irradiation gave N-alkyl 3-cyano-6-hydroxy-2(1H)-pyridinones with high yields. Upon carrying out the reaction under the same condition on acidic alumina, zeolite HY, silica gel, and montmorillonite K-10, the best yields were achieved by silica gel. Corresponding author. E-mail: balalaie@yahoo.com Received August 28, 2002; accepted September 3, 2002     

Green and one‐pot surface coating of iron oxide magnetic nanoparticles with natural amino acids and biocompatibility investigation

We report the synthesis of iron oxide magnetic nanoparticles (IONPs) coated with various natural amino acids (AAs) using a one‐pot reaction in an aqueous medium. Several AAs, which contained hydrophilic and hydrophobic groups, were selected to study their effects on size, morphology and toxicity of IONPs. Functionalized IONPs were characterized using X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopies. Furthermore, vibrating sample magnetometry analysis shows these nanoparticles have excellent magnetic properties. Cellular toxicity of IONPs was also investigated on HFF2 cell lines. The AA‐coated IONPs are non‐toxic and biocompatible. Natural AA‐coated IONPs show a potential for their development in in vitro and in vivo biomedical fields due to their non‐toxicity, good ζ‐potential and related small size and narrow size distribution.     

A Novel Non-enzymatic Selective and Sensitive Glucose Sensor Based on Nickel-Copper Oxide@3D-rGO/MWCNTs

In this work, a modified 3D-rGO/MWCNT with nickel and copper oxide nanoparticles were synthesized. The structural properties of this nanocomposite were investigated by several techniques. The fabricated sensor at optimum condition potential of +0.60 V (vs. Ag/AgCl) and a rotational rate of 1800 rpm gave a detection limit of 0.04 μmol L⁻¹ with two dynamic ranges of 0.10–300 and 300–900 μmol L⁻¹ glucose with high stability. The good accuracy of the fabricated sensor was proved in the determination of glucose in a blood sample (with recoveries between 95 % to 105 % and RSDs of 1.2 to 2.5 %).     

Corrigendum to: When is a sum of annihilator ideals an annihilator ideal?

In this corrigendum, we correct the statement and proof of Lemma 3.2, revise the proofs of Lemma 3.3 and Theorem 3.5, retract Proposition 3.10 and correct several typographical errors.     

Restrictions on nonlinear constitutive equations for elastic shells

Constitutive equations for the resultant forces and moments applied to a shell-like body necessarily couple the influences of the shell geometry and the constitutive nature of the three-dimensional material from which the shell is constructed. Consequently, even when the nonlinear constitutive equation of the three-dimensional material is known, the complicated influence of the shell geometry on the constitutive response of the shell is not known. The main objective of this paper is to develop restrictions on the constitutive equations of nonlinear elastic shells which ensure that exact solutions of the shell equations are consistent with exact nonlinear solutions of the three-dimensional equations for homogeneous deformations. Since these restrictions are nonlinear in nature they provide valuable general theoretical guidance for specific constitutive assumptions about the coupling of material and geometric properties of shells. Examples of the linear theories of a plate and a spherical shell are considered.     

Thermodynamic Study of the Extraction of Inorganic Mercury Compounds in Fish Species of the International Anzali Wetland,Iran

Inorganic mercury concentration was measured in the muscle tissues of four types of fish in the aquatic international Anzali Wetland ecosystem in Guilan. In the same ecosystem, the northern pike is able to concentrate inorganic mercury in its body more than other fish. In each species, a fish with the highest amount of inorganic mercury was selected for determination of thermodynamic parameters of inorganic mercury extraction using calculation of the equilibrium constant and fitting of ln K_c versus inverse temperature at the atmospheric pressure. The origins of thermodynamic parameters were discussed. The extraction processes were done in the range of temperatures from 331.15 to 365.15 K and at atmospheric pressure. Results show that the extraction of mercury compounds from SH groups of sulfhydryl proteins in fish muscle tissue is an endothermic process with a positive value for entropy and Gibbs free energy changes at room temperature.     

Physically nonlinear and related approximate theories of elasticity,and their invariance properties

The existing developments of physically nonlinear elasticity have several shortcomings. With the aim of remedying these deficiencies, a number of approximate theories of elasticity are discussed in the present paper and, in particular, a theory of physically nonlinear elasticity is systematically developed. More specifically, stress-strain relations for anisotropic physically nonlinear materials are derived. The method of Casey & Naghdi [1] is then applied to obtain properly invariant results. This method involves the use of auxiliary motions obtained by removing from any given motion the translation and rotation at any one particle, called a pivot. The auxiliary motions represent the original motions in the approximate theory. The connection between the transformation of fields under a change of pivot and invariance requirements associated with the auxiliary motions is investigated.     

A Direct theory of viscous fluid flow in channels

This paper deals with an Eulerian formulation of the theory of directed fluid sheets appropriate for incompressible, linear viscous fluid flow in channels with arbitrary shapes for their major boundaries which may be moving or fixed. Special cases of the theory are applied to a number of two-dimensional fluid flow problems and these solutions are in general discussed for unsteady flow. Specific applications include fluid flow in a channel whose boundaries are symmetric with respect to a middle plane in the channel, subjected to time-dependent pressure gradient at one end; and to lubrication problems in a general shaped channel when one of the channel walls is a fixed plane while the other is moving with a constant velocity. Flow of a viscous fluid with a free surface over a fixed boundary is also discussed.Dedicated to J. L. Ericksen on the occasion of his Sixtieth Birthday     

The effect of a transverse shear acting on the edge of a circular cutout in a simply supported circular cylindrical shell

Summary First, the solution to the problem of a simply supported circular cylindrical shell (without a cutout) subjected to a circumferential segmental line load at the middle of the shell is derived. Next, the negatives of the stress resultants and stress couples at a given radius ₀, obtained from this solution, are combined with a transverse shear force to form the edge conditions for a circular cylindrical shell containing a circular cutout with radius ₀. The desired solution is finally obtained by superposing the above two solutions. The convergence of the series, obtained in the first part, is improved for the complete region near and on the segmental line load. Numerical results are presented.

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Übersicht Es wird zunächst die Lösung für die Spannungsverteilung in einer einfach gelagerten kreiszylindrischen Schale ohne Ausschnitt angegeben. Die Schale wird durch eine Linienlast längs eines Umfangs in der Mitte der Schale belastet. Die hierfür erhaltenen Kräfte und Momente für einen gegebenen Radius ₀ werden dann mit einer Quer-Schubkraft kombiniert, um die Randbedingungen für eine kreiszylindrische Schale mit rundem Ausschnitt vom Radius ₀ zu erhalten. Die gewünschte Lösung wird schließlich durch Überlagerung der beiden Teillösungen erhalten. Die Konvergenz der dabei auftretenden Reihenentwicklungen wird für den Bereich der Belastungslinie verbessert. Numerische Ergebnisse werden angegeben.

     

Stress distribution around large holes in flat plates

Summary Employing a special case of a new method, the solution for the problem of a rectangular flat plate with a central large circular cutout subject to some transverse load and/or moment is derived. This is achieved with the use of certain eigenfunctions generated by sets of circular line loadings of the plate. Numerical results are presented for special cases.

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Übersicht Die Spannungsverteilung für eine rechteckige Platte mit einem großen kreisförmigen Ausschnitt in der Mitte unter der Einwirkung von Querlasten und/oder Momenten wird mit Hilfe des Spezialfalles einer neuen Methode berechnet. Dabei werden Eigenfunktionen verwendet, die durch kreisförmige Linienlasten auf der Platte erzeugt werden. Einige numerische Ergebnisse werden angegeben.