Stereochemical correlation of diastereomeric 3-amino- with 3-arylamino acids,and their derivatives via stereospecific N-phenylation by diphenylhalonium salts

Diphenylhalonium salts were used in stereospecific N-phenylation of racemic and optically active 3-amino-2,3-diphenyl-1-propanols leading to 3-anilino-2,3-diphenyl-1-propanols. The absolute configurations of the latter and of genetically related compounds were established.

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Stereochemische Korrelation von diastereomeren 3-Amino- mit 3-Arylaminosäuren bzw. ihrer Derivate durch stereospezifische N-Phenylierung mit DiphenylhaloniumsalzenKurze Mitteilung

Zusammenfassung Durch stereospezifische N-Phenylierung mit Hilfe von Diphenylhaloniumsalzen werden racemische sowie optische aktive 3-Amino-2,3-diphenyl-1-propanole in die entsprechenden 3-Anilino-2,3-diphenyl-1-propanole übergeführt. Auf Grund dieser Umwandlung wird die absolute Konfiguration der Aminoalkohole und davon abgeleiteter Derivate ermittelt.

     

Low-Temperature Catalytic Oxidation of Sulfide Ions in Aqueous Solutions on a Ni-Oxide System

Catalytic oxidation of sulfide ions in aqueous solutions by air oxygen has been investigated using a Ni-oxide system as a catalyst. The kinetics and the selectivity of the oxidation process were studied by varying the pH, catalyst amount and reaction temperature. A reduction/oxidation mechanism of the reaction has been supposed comprising interaction between the surface active oxygen of the catalyst and HS^– and reoxidizing of the reduced catalyst by the dissolved oxygen. The results obtained show that the Ni-oxide system is a promising catalyst for practical application.     

Low-temperature aqueous phase oxidation of cyanide ions with the participation of nickel oxide system

The low-temperature oxidation of cyanide ions to CO₂ and N₂ in an aqueous phase in the presence of Ni-oxide system has been studied. The effect of pH, temperature and catalyst amount on the rate and selectivity of the oxidation process have been investigated. A kinetic model of the reaction studied is proposed based on the experimental results. It can be used to develop a catalytic method for purification of CN containing wastewaters.     

On the Relationship Between Regression Analysis and Mathematical Programming

The interaction between linear, quadratic programming and regression analysis are explored by both statistical and operations research methods. Estimation and optimization problems are formulated in two different ways: on one hand linear and quadratic programming problems are formulated and solved by statistical methods, and on the other hand the solution of the linear regression model with constraints makes use of the simplex methods of linear or quadratic programming. Examples are given to illustrate the ideas.     

Active Oxygen in Oxide Catalytic Systems for Environmental Catalysis

The effect of the synthesis conditions of individual and modified with Mn Ni- and Co-oxide systems on the content and the mobility of their active oxygen has been studied by means of chemical and IR spectral analyses. The results obtained show that the main part of the active oxygen in Ni-oxide system is located on the catalyst’s surface (O_s ^* is approximately 73% of the total active oxygen), while Co-oxide system is characterized by much lower surface active oxygen content. Ni- and Co-oxide systems modified with Mn have comparatively higher active oxygen content as compared to the individual ones. Data of the IR spectral analysis reveal that Mn, as a modifying component, affects the mobility of the active oxygen, the latter contributing to the activity of oxide systems in oxidation processes. The high content of loosely bonded active oxygen formed during the synthesis determines a high catalytic activity of the studied samples in reactions of complete oxidation in the low temperature region.     

Catalytic degradation of methylene blue in aqueous solutions over Ni- and Co- oxide systems

The oxidative catalytic degradation of the cationic dye methylene blue (MB) with NaOCl in aqueous solutions was studied using individual and iron modified Ni- and Co-oxide systems as catalysts. The adsorption extent and the contribution of the uncatalyzed oxidation on the overall degree of MB were determined. The results indicate that methylene blue—a representative of a class of dyestuffs resistant to biodegradation—could be successfully decolorized and degraded using nickel and cobalt oxide catalysts at room temperature. The highest catalytic activity manifests in the Co-oxide system which is consistent with the adsorption data. The oxidative degradation reaction proceeds via first-order kinetics. Temperature has a relatively small effect on the methylene blue degradation kinetics. The results obtained reveal that the catalysts investigated are suitable for oxidative destruction of methytlene blue dye in wastewaters.      

Maintenance models in warranty: A literature review

Along with increasing the warranty period for complex systems, reducing the warranty servicing costs has become an issue of great importance to the manufacturers. One possible way to reduce the expected warranty servicing cost is by making sound decision on the product warranty and maintenance strategies. Therefore, warranties (basic warranty and extended warranty) and maintenance (corrective and preventive) are strongly interlinked and of great interest to both manufacturers and customers. This paper is the first identifiable academic literature review to deal with warranty and maintenance. It provides a classification scheme for the articles that link warranty and maintenance published between 2001 and 2011 covering 44 journals and proposes a taxonomy scheme to classify these articles. Nine hundred articles were identified for their relevance to warranty and were carefully reviewed. One-hundred and twenty-two articles were subsequently selected for their relevance to maintenance and included in the classification.     

Warranty cost analysis: Increasing warranty repair times

In this study, we model the warranty servicing costs under nonrenewing and renewing free repair warranties. We assume nonzero increasing repair times with the warranty cost depending on the length of the repair time. An increasing geometric process is used to model the consecutive repair times. We introduce the generalised alternating renewal process, which is an alternating process with cycles consisting of an item's operational time followed by the corresponding repair time. We derive analytical results for a generalised alternating renewal process with a finite time horizon and use them to evaluate the warranty costs over the warranty period and over the life cycle of the product under the nonrenewing free repair warranty and renewing free repair warranty. Properties of the model are demonstrated through a simulation study and through the application to warranty claims data from an automotive manufacturer.     

Mechanically Stable Hydrophilic Films Based on Oxialkylated Macromers Polymerizable by UV Irradiation

The preparation and characterization of films based on ethoxylated and acrylated triethanolamine or ϵ-aminecaprolactam or acrylated block copolymer of ethylene oxide (EO) and propylene oxide (PO) are described. Chemical characterization of films and migration of the plasticizers through the films were monitored with electron spectroscopy for chemical analysis. The (EO)_x(PO)_y(EO)_x–3A film was shown to be unique in the sense that it efficiently prevents migration of hydrophobic species. © 1997 John Wiley & Sons, Ltd.     

Low-temperature heterogeneous oxidation of sulfide ions on a higher Co oxide system in aqueous medium

Low-temperature heterogenous oxidation of sulfide ions on a higher Co oxide system in aqueous medium has been studied. The effects of pH, temperature and catalyst amount on the kinetic parameters as well as on the selectivity of the oxidation process were investigated. An oxidation mechanism has been proposed based on the results of kinetic investigations and on the data obtained by IR and XPS spectroscopic studies of Co oxide before and after sulfide ion oxidation.