Physical Aging of Amorphous Fructose

ABSTRACT: Physical aging of amorphous anhydrous fructose at temperature 5 °C and at 22 °C was studied using differential scanning calorimetry (DSC). The dynamic glass transition temperature, T_g0 for unaged samples was 16 °C and 13.3 °C for heating rate of 10 °C/min and 1 °C/min, respectively. The fictive temperature, T_f0 for unaged samples calculated by Richardson and Savill method was 12 °C, which is close to the dynamic value obtained from the lower DSC heating rate. The fictive temperature T_f of the aged fructose glasses at temperatures both below and above the transition region was fitted well by a non-exponential decay function (Williams-Watts form). Aging above the transition region (22 °C) for 18 d increased both the dynamic glass transition temperature T_g and the fictive temperature T_f. However, aging below the transition region (5 °C) for 1 d increased the dynamic glass transition temperature T_g but decreased the fictive temperature T_f.     

Efficient computation of the steady-state response of periodicnonlinear microwave circuits using a convolution-based sample-balancetechnique

The authors describe an efficient and robust approach to the computation of the steady-state response of periodic nonlinear microwave circuits. The problem of solving a set of differential equations is converted into that of solving a system of nonlinear algebraic equations using a technique called convolution-based sample balance. Although exact in all cases for which harmonic-balance techniques are exact, this technique does not require the use of discrete Fourier transforms, and calculating the Jacobian is straightforward. For the solution of the resulting system of nonlinear equations, an efficient and yet robust algorithm has been developed. In the examples given, savings in computational effort of over 85% are reported when this algorithm is compared with Newton's method     

A novel nucleation apparatus for regime separated granulation

A novel nucleation apparatus is presented for the production of narrow sized nuclei from various powder and binder liquid combinations. Mono-sized binder liquid droplets are produced by a specially designed mono-disperse droplet generator. The droplet generator is positioned above a conveyor belt, transporting a powder bed through the spray zone of the droplet generator. By nucleating powder on a conveyer belt, the nucleation mechanism is completely separated from all other granulation mechanisms due to the lack of relative motion between primary particles and/or formed nuclei. Nucleation tests were performed using chalcopyrite and limestone powders with water as the binder liquid. At all operating conditions, the formed nuclei were found to originate from multiplicities of drops that merged on the powder bed surface. Investigation of the dynamics of nuclei formation showed that powder-binder liquid combinations with fast penetration dynamics result in less variation in the number of droplets from which nuclei originate. Smaller and more narrowly distributed nuclei were also achieved by increasing powder speed through the spray zone.     

The effect of growth rate on anodically formed zirconium oxide films

Anodic oxide films have been grown on zirconium at constant current densities for a range of current densities extending over several orders of magnitude. Optical and scanning electron microscopy have shown structural differences for different current densities and the mechanical failure of the films has been studied by tensile testing after oxidation. As the current density was reduced, blistering and breaking of the oxide layer was found to increase and this has been associated with anomalies in the experimental voltage-time graphs. The relationship between electric field in the oxide and the current density has been investigated and values of the activation energies of diffusion have been estimated for both oxygen ions and zirconium ions. Possible mechanisms are discussed for the stress relaxation found to occur increasingly for current densities from 0·01 to 1 mAcm^?2.     

Experimental studies and kinetics of single drop drying and their relevance in drying of sugar‐rich foods: A review

Levitation and free‐flight techniques applied to investigate the drying kinetics and morphology of single drops containing dissolved solids and suspensions are reviewed. A review of works related to receding interface model proposed to quantify the drying kinetics of single drops along with techniques to measure the kinetic parameters such as moisture diffusivity, thermal conductivity and specific heat capacity is presented. Problems associated with spray drying of sugar‐rich compounds are briefly discussed and possible links of stickiness and flavor retention with glass transition temperature (T_g), temperature history, drying rate and morphological changes including skin formation, as monitored through single drop experiments, are explored.     

Ethnic differences in social-emotional development in preschool: The impact of teacher child relationships and classroom quality.

Drawing from the National Center for Early Development and Learning (NCEDL) Multi-State Study of Prekindergarten and the State-Wide Early Education Programs Study (SWEEP), this study examined the effects of classroom and teacher variables on social-emotional development in prekindergarten. Results indicated that prekindergarten teachers rated males significantly higher in behavioral problems and lower in social competence than females. However, when teacher-child ethnic match was taken into consideration these differences were not present. In contrast to existing evidence, African American males in particular were no more likely to have teachers who report behavior problems than their Latino and White male peers. Implications for the prevention of behavioral problems are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Simple formulas for microstrip lines

A modification to earlier work is presented which allows for finite strip thickness in the calculation of microstrip impedance and line wavelength. It shows a considerable improvement in accuracy and scope over some earlier work which included strip thickness, but remains simple in form. Expressions are presented which allow calculation of Z and ?g for any microstrip geometry and relative permittivity.     

Conversational and social responses to depressive interpersonal behavior.

Examined responses to depressive interpersonal behavior. 30 undergraduates interacted with a same-sex confederate for 7 min in the context of waiting together for an experiment to begin. Confederates employed either a depressed role (depressive interpersonal behavior and reporting serious deficits in functioning), a normal role (normal interpersonal behavior and reporting minimal deficits in functioning), or a physically ill role (normal interpersonal behavior and reporting serious deficits in functioning). Ss who interacted with a "depressive" responded with a higher rate of silences and directly negative comments and a lower rate of overall verbal responding. Their expressions of direct support were equivalent to those made to the "physically ill" confederates and greater than those in the normal condition. Ss also were more rejecting of partners who behaved in a depressed manner and described them in more negative terms and as having greater interpersonal impact than confederates in other roles. There were no induced mood differences. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Elastic recovery at hardness indentations

The mechanics of hardness indentation are considered. On the basis of a cycle in which the loading is elastic-plastic and the unloading (and subsequent reloading) elastic, an expression is derived for the relative depth recovery of the impression as a function of hardness/modulus,H/E. Experimental observations on indented surfaces of selected materials, mostly ceramics, using a tilting procedure in the scanning electron microscope to measure the residual depths, confirm the predicted trends. The analysis offers a simple means of characterizing the deformation properties of materials and should provide a basis for evaluating a range of contact-related properties, particularly surface damage phenomena in sharp-particle impact.