Kinetics of Ice Recrystallization in Aqueous Fructose Solutions

Recrystallization rates of ice in fructose solutions were determined over a range of temperatures and ice phase volumes. Accretive and migratory recrystallization both occur, the dominant mechanism being strongly dependent on the mean size of the crystals. Accretion dominated when crystals were small and close together. Recrystallization rates decreased with decreasing ice phase volume and decreasing temperature. The temperature dependence of the rates was consistent with Williams-Landell-Ferry kinetics. With a mean field correction for ice phase volume the observed data fit the recrystallization theory of Lifshitz, Slyozov and Wagner reasonably well.     

Recrystallization in Aqueous Fructose Solutions as Affected by Locust Bean Gum

Rates of ice recrystallization were measured in aqueous fructose solutions containing locust bean gum (LBG). The effects of temperature, ice phase volume and LBG concentration were determined. Decreasing temperature reduced the recrystallization rate: the dependency followed Williams Landell Ferry kinetics. An increase in ice phase volume resulted in an increase in the recrystallization rate. Addition of LBG reduced the recrystallization rate up to a concentration of 0.3% (w/w); further addition resulted in no further decrease. The hypothesized mechanism of action of LBG is via weak adsorption of the polysaccharide to the ice crystal. Freeze concentrated solution viscosity did not correlate with observed recrystallization rates.     

NONPROFIT HOUSING ORGANIZATIONS AND INSTITUTIONAL SUPPORT: The Management Challenge

ABSTRACT: The viability of the low income housing built by nonprofit organizations in US cities hinges on the ability of these groups to maintain and manage it. Nonprofit sponsors and their institutional support system have only recently begun to recognize the importance of property and asset management. First priority continues to be housing production, followed by organizational capacity building. This paper explores how the institutional support network for nonprofit housing has begun to address the need for stronger property management. Drawing from recent six city study, the authors examine different ways by which local and national networks provide financial and technical support for property management. They conclude with a series of recommendations for broadening and strengthening institutional support for property management in the nonprofit sector.     

FATIGUE LIFE BEHAVIOR OF COPPER SINGLE CRYSTALS. PART II: MODEL FOR CRACK NUCLEATION IN PERSISTENT SLIP BANDS

A crack nucleation model is constructed based on the random slip of the dislocations within the fatal persistent slip band (PSB). From such a model, we derive the notch-peak probability function. The crack is considered to nucleate when a critical notch depth is attained. This depth is constant for applied strains corresponding to the plateau of the cyclic stress- strain curve because the stress is constant. The PSBs behave in such a way that the more concentrated their localized slip the fewer the cycles required to attain the critical notch depth. Using the experimental relation between the applied strain and the magnitude of the slip offsets (reported in Part I) in conjunction with observations of the notch distributions along the gage surface, we have obtained the relation between the applied strain and the cycles for crack nucleation. A log-log plot of this relation shows a slightly different slope from that of the Coffin-Manson life data, previously reported. However, by allowing for cycles spent in Stage II propagation, good agreement is obtained.     

Studies on Processing of an Alnico Scrap

This paper presents the results of research and development work on processing of alnico scrap, a secondary resource of nickel and cobalt, generated during the manufacturing of alnico magnets. The scrap contains 8–10% nickel, 10–12% cobalt, 32–50% of iron, 8–10% aluminium, 2% copper and remaining silica. Various processes such as acid leaching, aqueous chlorine leaching, salt roasting and cupric chloride leaching were studied in detail. Of these cupric chloride leaching was found to be most effective with respect to recovery and purity. It has been possible to obtain pure nickel and cobalt salts by cupric chloride leaching of the scrap, solvent extraction and precipitation of the salts. The overall recovery by the above process was almost 99%.     

ЭГ-2.5静电加速器扩建离子束流管道

本文介绍了束流管道扩建后,ЭГ-2.5静电加速器束流管道的布局以及这次改进的特点和达到的指标。着重说明了磁束流导向器的使用(方便了调束操作)和真空系统采用铁泵、分子泵机组后的初步运行结果,并对几个新设计制作的元件作了简单介绍。     

THE ELUCIDATION OF THE KINETICS AND MECHANISMS OF THE CATALYTIC OXIDATION OF TRACE AMOUNTS OF DIMETHYL ETHER IN OXYGEN BY TRANSIENT PHENOMENA

Thermal desorption experiments with different heating schemes were used to study the kinetics and mechanisms of the catalytic oxidation of dimethyl ether (DME) on supported Pt catalysts. The experimental apparatuses were fully automated by using a microcomputer control system. This made possible direct evaluations of several key kinetic parameters as well as long-term evaluations of the catalysts. The oxidation of DME catalyzed by Pt/SiO₂-Al₂O₃, catalyst has been shown to involve the chemisorption of DME on the support and the chemisorption of oxygen on Pt metal sites. The surface reaction between chemisorbed DME and oxygen was found to be the rate-determining step under the experimental conditions investigated. The proposed reaction mechanism using the kinetic parameters estimated from the thermal desorption experiments predicts the experimental results very well. Acetylene was found to have a promotional effect for the reaction. It is believed that carbon from acetylene plays a key role in this reaction enhancement.     

INTELLIGENT MONITORING AND DIAGNOSIS SYSTEMS: A Survey

Monitoring of a physical/mechanical system's performance provides an application for knowledge-based systems that is rich in diversity, open for creative designs, and important as a testing ground for applicability of artificial intelligence methodologies. Although the field is relatively new, abundance of knowledge-based systems attest to its importance. We survey a number of more recent monitoring system. In doing so, we attempt to extract a number of important parameters distinguishing the various systems, and to classify these systems in a number of dimensions offered by these parameters. This article is not an exhaustive survey of the field but attempts to provide a representative sample of recent applied monitoring and diagnostic systems.     

Studies on Processing of an Alnico Scrap

Abstract

This paper presents the results of research and development work on processing of alnico scrap, a secondary resource of nickel and cobalt, generated during the manufacturing of alnico magnets. The scrap contains 8-10% nickel, 10-12% cobalt, 32-50% of iron, 8-10% aluminium, 2% copper and remaining silica. Various processes such as acid leaching, aqueous chlorine leaching, salt roasting and cupric chloride leaching were studied in detail. Of these cupric chloride leaching was found to be most effective with respect to recovery and purity. It has been possible to obtain pure nickel and cobalt salts by cupric chloride leaching of the scrap, solvent extraction and precipitation of the salts. The overall recovery by the above process was almost 99%.