Emulsifier Composition of Solid Lipid Nanoparticles (SLN) Affects Mechanical and Barrier Properties of SLN‐Protein Composite Films

Protein films can be applied to improve food quality and to reduce packaging waste. To overcome their poor water barrier properties, lipids are often incorporated. The function of incorporated lipid depends on the interface between filler and matrix. This study aimed to tailor the properties of a protein–lipid film by designing the oil/water interface to see if the concept of inactive/active filler is valid. Therefore, we varied the emulsifier stabilizing solid lipid nanoparticles (SLN) to promote (via β‐lactoglobulin) or to minimize (via Tween 20) interactions between particle surface and protein. SLN were incorporated into protein films and film properties were determined. Addition of SLN led to significantly decreased water vapor permeability (WVP) of protein films. However, WVP was mainly affected by the emulsifiers and not by the lipid. Protein‐stabilized SLN (BS) replaced a lacking protein in the protein network and therefore did not influence the mechanical properties of the films at ambient temperature. BS‐composite films were temperature sensitive, as lipid and sucrose palmitate melted at temperatures above 40 °C. Tween 20‐stabilized SLN (TS) led to reduced tensile strengths, probably due to perturbative effects of TS and plasticizing effects of Tween 20. Dynamic mechanical analysis showed that TS and Tween 20 increased film mobility. Melting of lipid and emulsifiers, and temperature‐dependent behavior of Tween 20 led to a strong temperature dependence of the film stiffness. By designing the interface, particles can be used to tailor mechanical properties of protein films. Tuned edible films could be used to control mass transfers between foods.     

Creating false memories: Remembering words not presented in lists.

Two experiments (modeled after J. Deese's 1959 study) revealed remarkable levels of false recall and false recognition in a list learning paradigm. In Exp 1, Ss studied lists of 12 words (e.g., bed, rest, awake); each list was composed of associates of 1 nonpresented word (e.g., sleep). On immediate free recall tests, the nonpresented associates were recalled 40% of the time and were later recognized with high confidence. In Exp 2, a false recall rate of 55% was obtained with an expanded set of lists, and on a later recognition test, Ss produced false alarms to these items at a rate comparable to the hit rate. The act of recall enhanced later remembering of both studied and nonstudied material. The results reveal a powerful illusion of memory: People remember events that never happened. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of selected organic compounds on the response of a calcium ion-selective electrode

The influence of some naturally occurring organic compounds on the response of a calcium ion-selective electrode has been investigated. Phenol, resorcinol, phthalate, salicylate and humic acid cause significant interference when their concentrations are greater than 10 mg¹⁻¹.     

Beyond neighborhood poverty: Family management, neighborhood disorder, and adolescents’ early sexual onset.

The authors examined how neighborhood disorder modifies associations between family management practices and youth transitions to sex among low-income African American and Latino urban families. The sample included 846 young adolescents and their mothers who participated in Welfare, Children and Families: A Three-City Study. Results from multilevel logistic regression models indicated no main effects of family management practices or neighborhood-level conditions on transitions to sex once accounting for demographics. However, higher levels of family routines and parental knowledge (i.e., awareness of youths’ friends, whereabouts, and activities) were more strongly associated with a lower probability of youth sexual onset as neighborhood disorder increased. Results provide further evidence for the contextually specific nature of parenting impacts on adolescent adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SURFACTANT ADSORPTION TO SPHERICAL PARTICLES: THE INTRINSIC LENGTH SCALE GOVERNING THE SHIFT FROM DIFFUSION TO KINETIC-CONTROLLED MASS TRANSFER

When a drop or bubble of radius b is formed in surfactant solution, surfactant adsorbs, diffuses from solution, and desorbs to establish the equilibrium surface concentration. The transport coefficients for diffusion, adsorption, and desorption are fundamental parameters. However, the transport mechanisms that control the interface far from equilibrium are highly context dependent. Thus, no surfactant has universal “diffusion-controlled” transport. Here we identify a new length scale, R _D-K , that depends on surfactant physicochemistry, and which ranges from roughly 15 to 65 microns. For drops or bubbles with b?R _D-K , mass transfer is kinetically controlled. For b?R _D-K , mass transfer is diffusion controlled. Simulations of adsorption to quiescent spherical interfaces support the importance of R _D-K in determining the controlling transport mechanism for surfactant solutions with concentrations below the critical micelle concentration (CMC). While the case of surfactant adsorbing to a bubble is discussed in detail, the arguments presented are quite general and should apply to adsorption of any solute to any spherical particle.     

Damage evolution in SiC/SiC unidirectional composites by X-ray tomography

Melt infiltrated SiC/SiC ceramic matrix composite unidirectional (UD) composite specimens were imaged under load using X-ray microtomography techniques in order to visualize the evolution of damage accumulation and to quantify damage mechanisms within the composite such as matrix cracking and fiber breaking. The data obtained from these in situ tensile tests were used in comparison with current models and literature results. Three-dimensional (3D) tomography images were used to measure the location and spacing of matrix cracking that occurred at increasing stress increments during testing within two UD composite specimens. The number of broken fibers and the location of each fiber break gap that occurred within the volume of both specimens were also quantified. The 3D locations of fiber breaks were correlated with the location of each matrix crack within the volume of the specimen and it was found that at the stress scanned directly before failure, most of the fiber breaks occur within 100 microns of a matrix crack.     

Grain Size Effect on Creep Deformation of Alumina-Silicon Carbide Composites

A study of the flexural creep response of aluminas reinforced with 10 vol% SiC whiskers was conducted at 1200° and 1300°C at stresses from 50 to 230 MPa in air to evaluate the effect of matrix grain size. The average matrix grain size was varied from 1.2 to 8.0 μm by controlling the hot-pressing conditions. At 1200°C, the creep resistance of alumina composites increases with an increase in matrix grain size, and the creep rate (at constant applied stress) exhibits a grain size exponent of approximately 1. The stress exponent of the creep rate at 1200°C is approximately 2, consistent with a grain boundary sliding mechanism. On the other hand, the creep deformation rate of 1300°C was not sensitive to the alumina grain size. This was seen to be a result of enhanced nucleation and coalescence of creep cavities and the development of macroscopic cracks as the grain size increases. Observations also indicated that the prevalent site for nucleation and growth of creep cavities in coarsegrained materials is at two-grain junctions (grain faces), whereas in fine-grained materials cavities nucleate primarily at triple-grain junctions (grain edges). Electron microscopy studies revealed that the content of any amorphous phase present at whisker-alumina interfaces is independent of alumina grain size (and hot-pressing conditions). In addition, the alumina grain boundaries are quite devoid of amorphous phase(s). This variation in amorphous phase content does not appear to be a factor in the present creep results.     

Effects of imperfect automation on decision making in a simulated command and control task

OBJECTIVE: Effects of four types of automation support and two levels of automation reliability were examined. The objective was to examine the differential impact of information and decision automation and to investigate the costs of automation unreliability. BACKGROUND: Research has shown that imperfect automation can lead to differential effects of stages and levels of automation on human performance. Method: Eighteen participants performed a "sensor to shooter" targeting simulation of command and control. Dependent variables included accuracy and response time of target engagement decisions, secondary task performance, and subjective ratings of mental work-load, trust, and self-confidence. RESULTS: Compared with manual performance, reliable automation significantly reduced decision times. Unreliable automation led to greater cost in decision-making accuracy under the higher automation reliability condition for three different forms of decision automation relative to information automation. At low automation reliability, however, there was a cost in performance for both information and decision automation. CONCLUSION: The results are consistent with a model of human-automation interaction that requires evaluation of the different stages of information processing to which automation support can be applied. APPLICATION: If fully reliable decision automation cannot be guaranteed, designers should provide users with information automation support or other tools that allow for inspection and analysis of raw data.     

Does switching to low tar/nicotine/carbon-monoxide-yield cigarettes decrease alveolar carbon monoxide measures? A randomized controlled trial.

Assessed the effects of changing to low tar/nicotine/carbon-monoxide-(CO)-yield cigarettes on alveolar carbon monoxide over a 5–6 wk period for 40 adult chronic smokers of high tar/nicotine/CO cigarettes. Ss were assigned to either a 5-wk step-wise brand-reduction treatment or to a delayed-treatment control group. Ss were assessed for (a) resting CO body burden and CO uptake per cigarette and (b) smoking topography and rate. Although CO uptake was significantly lower after Ss smoked low tar/nicotine/CO cigarettes than after smoking their original brand, resting CO body burden did not change. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pretherapy information: An investigation of client responses.

36 female undergraduates who had expressed profeminist attitudes as operationally defined by the Attitudes Toward Women Scale were randomly assigned to 1 of 3 groups. Each group received differing amounts of pretherapy information about the therapist's values and therapy orientation. Results indicate that Ss did not perceive themselves as similar to the "explicit feminist" therapist, did not believe that she would be as helpful as either the "traditional" or "feminist label" therapists, and were not as willing to see the explicit feminist therapist. Implications for therapist disclosure of explicit value orientations are considered. (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)