The influence of couple-stresses on singular stress concentrations in elastic solids

Zusammenfassung Es werden im Rahmen einer linearisierten Theorie, welche Spannungsmomente berücksichtigt, singuläre Spannungskonzentrationen untersucht. Zu diesem Zweck wird mit Hilfe der exponentiellen Fouriertransformation für das Problem der Halbebene unter verteilter Oberflächenbelastung im ebenen Verschiebungszustand eine exakte Lösung aufgestellt. Diese Lösung wird anschliessend zum Studium des singulären Spannungsfeldes benützt, welches sich unter konzentrierter Normal-oder Tangentiallast sowie unter unstetiger Schubbelastung einstellt; sie wird auch zur Ermittlung der Spannungskonzentration benützt, welche von einem flachen Stempel herrührt. In jedem Falle werden die erhaltenen Singularitäten im einzelnen studiert und mit den entsprechenden Singularitäten der klassischen Elastizitätstheorie verglichen.

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This paper was prepared under Contral Nonr-220 (58) with the Office of Naval Research in Washington, D. C.

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The work underlying this paper was carried out in part while the second author was a Guggenheim Fellow at Keio University, where he held a Visiting Professorship.     

Syntheses and electrochemical behaviour of novel dmit or dmio (dithiolato) cobalt(iii) complexes with a η5-cyclopentadienyl or η5-pentamethylcyclopentadienyl ring

Four novel cobalt(III) complexes with a cyclopentadienyl or pentamethylcyclopentadienyl ring and dmit or dmio ligands were synthesized, and their electrochemical behaviour was investigated. All these complexes exhibited three one-electron transfer steps: one reduction and two oxidation steps. In addition, a novel organosulphur compound was afforded by electrochemical oxidation of dmit cobalt complex. Thus, these complexes may have considerable synthetic potential as precursors for electron reservoirs and organosulphur compounds.     

Sonochemical degradation of azo dyes in aqueous solution: a new heterogeneous kinetics model taking into account the local concentration of OH radicals and azo dyes

The sonochemical decolorization and decomposition of azo dyes, such as C. I. Reactive Red 22 and methyl orange, were performed from the viewpoints of wastewater treatment and to determine the reaction kinetics. A low concentration of the azo dye solution was irradiated with a 200 kHz and 1.25 W/cm2 ultrasound in a homogeneous aqueous solution. The azo dye solutions were readily decolorized by the irradiation. The sonochemical decolorization was also depressed by the addition of the t-butyl alcohol radical scavenger. These results indicated that azo dye molecules were mainly decomposed by OH radicals formed from the water sonolysis. In this paper, we propose a new kinetics model taking into account the heterogeneous reaction kinetics similar to a Langmuir-Hinshelwood mechanism or an Eley-Rideal mechanism. The proposed kinetics model is based on the local reaction site at the interface region of the cavitation bubbles, where azo dye molecules are quickly decomposed because an extremely high concentration of OH radicals exists in this region. To confirm the proposed kinetics model, the effects of the initial concentration of azo dyes, irradiated atmosphere and pH on the decomposition rates were investigated. The obtained results were in good agreement with the proposed kinetics model.     

Colour reaction of scandium with quercetin and its application to the analysis of scandium

A spectrophotometric study of the scandium-quercetin complex is described; μg amounts of scandium can be determined with quercetin at 43.5 mμ and pH 4.4. A 1:1 complex is formed. The apparent instability constant of the complex was estimated as 2.7·10^-7 by a spectrophotometric method. An ion-exchange method for separating scandium from several interfering ions is described.     

Pyrolysis of sulfoxide. III. Conversion of 2-(phenylsulfinyl)enoate to 2,4-dienoate and synthesis of pellitorine

2,4-Dienoate was prepared by pyrolysis of 2-(phenylsulfinyl)enoate. N-Isobutyl-E,E-2,4-decadieneamide (pellitorine) was synthesized from decanoic acid in a satisfactory yield.     

Rapid continuous determination of aluminium in copper-base alloys by flow-injection spectrophotometry

Summary A flow-injection spectrophotometric method has been developed for the rapid, continuous determination of aluminium in copper-base alloys. The system consists of the masking of copper, zinc, iron, etc. with a combined use of thiourea, ascorbic acid and EDTA and the measurement of light absorption of aluminium-Xylenol Orange complex at 506 nm. With appropriate standardization satisfactory results are obtained in spite of sluggish reaction of aluminium and Xylenol Orange. The system allows the analysis of solutions of copper-base alloys for aluminium to be conducted at a rate of 50 determinations per hour without any carryover. The results obtained for standard brasses and aluminium bronze (Al 1.43–10.2%) agreed well with the certified values. The precision (rsd) ranges are 0.2–0.3%.

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Kontinuierliches Schnellverfahren zur Bestimmung von Aluminium in Kupferlegierungen mit Hilfe der Flow-Injection-Spektralphotometrie

Zusammenfassung Bei dem empfohlenen Verfahren werden Cu, Zn, Fe und andere Störelemente mit Hilfe von Thioharnstoff, Ascorbinsäure und EDTA maskiert und der Al-Xylenolorange-Komplex bei 506 nm gemessen. Mit Hilfe eines geeigneten Eichverfahrens werden trotz der trägen Reaktion von Al mit Xylenolorange zufriedenstellende Werte erhalten. 50 Bestimmungen können innerhalb von 1 h ohne jedes Verschleppen durchgeführt werden. Bei der Analyse von Messing und Al-Bronze (1,43–10,2% Al) wurde gute Übereinstimmung mit zertifizierten Werten erzielt. Die Standardabweichungen lagen im Bereich von 0,2–0,3%.

     

Adsorption behavior of various metals on a weakly basic anion-exchange resin in sulfuric acid media

A systematic study is presented on the adsorption behavior of some 20 metals on a weakly basic condensed phenol resin, Amberlite CG-4B, in sulfuric acid media. The distribution coefficients were determined over a sulfuric acid concentration range of 0.005 M to 2 M. The metals adsorbed are similar to those which exhibit strong adsorption on a strongly basic resin, but the magnitudes of the distribution coefficients and the adsorption sequences differ considerably between the two types of the resin. Several two- and three-component separations of analytical interest are possible. A new method for the separation of titanium(IV) is described; this is based on its high adsorption on CG-4B from sulfuric acid media containing hydrogen peroxide.     

Ion Transport in Glyme- and Sulfolane-Based Highly Concentrated Electrolytes

Highly concentrated electrolytes (HCEs) have a similarity to ionic liquids (ILs) in high ionic nature, and indeed some of HECs are found to behave like an IL. HCEs have attracted considerable attention as prospective candidates for electrolyte materials in future lithium secondary batteries owing to their favorable properties both in the bulk and at the electrochemical interface. In this study, we highlight the effects of the solvent, counter anion, and diluent of HCEs on the Li⁺ ion coordination structure and transport properties (e. g., ionic conductivity and apparent Li⁺ ion transference number measured under anion-blocking conditions, ). Our studies on dynamic ion correlations unveiled the difference in the ion conduction mechanisms in HCEs and their intimate relevance to values. Our systematic analysis of the transport properties of HCEs also suggests the need for a compromise to simultaneously achieve high ionic conductivity and high values.