Molecular emission cavity analysis : Part VII. The determination of cadmium

Cadmium salts give an intense cadmium atomic emission in the MECA cavity in a hydrogen-nitrogen-air flame. When a carbon or stainless steel cavity is used, 10–120 ng of cadmium in 5-μl samples can be determined. In the presence of sulphuric acid, anionic interferences are removed. Of the cations, only Fe(III), Cr(III), Mg and Sn(II) interfere seriously.     

On the Relation Between Gegenbauer Polynomials and the Ferrers Function of the First Kind

Analysis Mathematica - Using the direct relation between the Gegenbauer polynomials $$C_n^\lambda(x)$$ and the Ferrers function of the first kind $${\rm{P}}_\nu^\mu(x)$$ , we compute interrelations...     

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Evaluation of new single crystal piezoelectric materials for surface acoustic-wave applications

Surface acoustic waves (SAW), or Rayleigh waves, bound to the surfaces of piezoelectric materials are becoming rapidly significant in electronic device applications, particularly as VHF-UHF frequency filters and versatile time-domain processors. The majority of available devices utilize either signle crystalline quartz or lithium niobate as the piezoelectric medium. This paper describes briefly the growth and critical evaluation of SAW impedance and propagation properties for certain new single crystal piezoelectric materials. Crystals discussed are Czochralski-grown bismuth germanium oxide, films of zinc oxide and aluminum nitride both epitaxially grown on single crystal sapphire, and flux-grown beryllium oxide. It is concluded that bismuth germanium oxide may prove an important cost-effective alternative to both quartz and lithium niobate, and that either zinc oxide or aluminum nitride is destined to prove invaluable in the realization of monolithic circuits such as programmable tapped delay lines, in which SAW will be interfaced with metal-oxide semiconductor (large scale integrated) technology, and active SAW elements employing functional integration.     

A method of general applicability for the micro determination of chlorine,bromine and iodine

Summary A method is described for the combustion of halogen containing organic compounds in milligram quantities in a closed system. It has been found to have greater applicability than existing techniques. After combustion the halogen is determined by an amperometric titration, which permits the determination of Cl^–, Br^– and I^– either singly or in admixture. The accuracy is probably better than existing micro methods for single halides and comparable with these methods for mixed halides.

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Zusammenfassung Eine Methode zur Verbrennung von Milligrammengen halogenhaltiger organischer Verbindungen im geschlossenen System wurde beschrieben. Sie hat einen größeren Anwendungsbereich als bisher bekannte Verfahren. Nach der Verbrennung wird das Halogen durch eine amperometrische Titration bestimmt, womit Chlorid, Bromid und Jodid sowohl einzeln wie in Gemischen bestimmt werden können. Die Genauigkeit seheint besser zu sein als bei bekannten Mikromethoden für die Bestimmung einzelner Halogene und etwa gleich gut wie bei Methoden zur Analyse von Halogengemischen.

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Résumé On décrit une méthode de combustion en vase clos, des composés organiques contenant des halogènes en quantités de l'ordre du milligramme. Cette méthode a été trouvée comme ayant un domaine d'applications plus grand que celui des techniques existant déjà. Après combustion, l'halogène est dosé par titrage ampérométrique, ce qui permet le dosage de Cl^–, Br^– et I^– isolés ou en mélange. La précision est probablement meilleure que celle des microméthodes existant pour les halogénures isolés et comparable à celle de ces méthodes pour les mélanges d'halogénures.

     

Studies in qualitative inorganic analysis. Part XXVIII

Summary Schemes for the analysis of the Copper-Tin group are reviewed. The advantages of the scheme recommended by the Midlands Association for Qualitative Analysis are discussed.

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Zusammenfassung Analysen-Schemata für die Kupfer-Zinn-Gruppe wurden besprochen. Die Vorteile des Analysenganges der Midlands Association for Qualitative Analysis werden diskutiert.

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Résumé Examen des différents processus d'analyse du groupe cuivre-étain. Discussion des avantages de la technique recommandée par la Midlands. Association pour l'analyse qualitative.

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Part XXVII: Mikrochim. Acta [Wien]1967, 389.     

Kinetics of the catalytic oxidation ofp-phenetidine with chlorate and the role of the catalyst vanadium(V)

Summary The kinetics of the catalytic oxidation ofp-phenetidine hydrochloride with potassium chlorate and vanadium(V) as catalyst is investigated. The mechanism of the catalyst action is studied and it is shown that vanadium acts by consecutive transitions between the oxidation states vanadium(V) and vanadium(IV). It is shown that the catalytically active forms of vanadium(V) are HVO₃ and especially VO₂ ⁺. It is found that a complex with a charge transfer transition is formed between vanadium(V) andp-phenetidine as a first stage of their interaction.

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Zusammenfassung Die Kinetik der katalytischen Oxydation von p-Phenetidinchlorhydrat mit Kaliumchlorat und Vanadin(V) als Katalysator wurde untersucht. Der Mechanismus der Katalysatorwirkung wurde studiert, wobei sich ergab, daß ein dauernder Wertigkeitswechsel zwischen V(V) und V(IV) stattfindet. Die katalytisch aktive Form ist HVO₃ und vor allem VO₂ ⁺. Es wurde gefunden, daß sich ein Komplex zwischen V(V) und p-Phenetidin als erste Stufe ihrer gegenseitigen Einwirkung bildet, wobei der Ladungsübergang stattfindet.

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Résumé On a étudié la cinétique de l'oxydation catalytique du chlorhydrate dep-phénétidine par le chlorate de potassium en présence de vanadium-V comme catalyseur. On a suivi le mécanisme de la réaction catalytique et on a montré que le vanadium agissait par transitions consécutives entre les états d'oxydation du vanadium-V et du vanadium-IV. On montre que les formes catalytiquement actives du vanadium-V sont HVO₃ et plus spécialement VO₂ ⁺. On a trouvé qu'un complexe avec transition de transfert de charge se formait entre le vanadium-V et lap-phénétidine comme première étape de leur interaction.

     

A system for defining reference materials applicable to all food matrices

Recently the subcommittee on Food Definition of the AOAC INTERNATIONAL Task Force on Methods for Nutrition Labeling proposed a Food Matrix Organizational System [4] to systematically judge the applicability of collaboratively studied methods over a range of food matrices. This system describes a food matrix by its location in one of nine sectors in a triangle, with each point of the triangle defined as representing 100% and the opposite side representing 0% of the normalized contents of each of three major components of FAT, PROTEIN and CARBOHYDRATE. Foods falling within the same sector would be chemically similar and thus should behave in a similar analytical manner. This same scheme can be used to select one or two food matrices representing each sector, for development of a series of reference materials representing all foods. The list of 5250 foods contained in the USDA Nutrient Data Base for Standard Reference has been sorted and matched to this schematic to determine the scope of the selection process. In addition the list of foods in the USDA Data Base for Food Consumption Surveys has been examined. Results and progress of this selection process are reported.     

Scanning Kelvin Microscope: a new method for surface investigations

Based on the well known Kelvin probe for work function measurements a new microstructure analysis system - the Scanning Kelvin Microscope - has been developed. It allows to measure simultaneously with high lateral resolution the distribution of the contact potential difference (CPD) between a conductive sample and a reference probe together with the topographical structure of the sample surface. The measurement is contact free and non-destructive and can be carried out in natural environments. At present the lateral resolution of the measurement approaches 5 microm. The results can be displayed on a computer in three dimensional colour pictures.