High performance water-borne paints with high volume solids based on bimodal latexes

The performance of water-borne paints formulated with five different high solids content acrylic (MMA/BA/MAA) latexes was investigated. These latexes had different particle size distributions (unimodal at 61 wt% and bimodal with the large mode below or above 350 nm at 65 wt% solids), different types of surfactant and in one case the carboxylic monomer was omitted.     

The mechano-sorptive behavior of flexible water-blown polyurethane foams

Samples of flexible water-blown slabstock polyurethane foams were compressed under constant load to study the effects of cycling moisture content on creep behavior and compare this behavior with the creep response where either a constant high or low moisture environment existed at the same temperature. Three sets of foams were tested: (1) 4 pph water content slabstock foam; (2) 5 pph water content slabstock foam; and (3) 2 pph water content molded foam. As the moisture conditions were cycled from low to high humidity while maintaining constant temperature in an environmental chamber, the compressive strain increased in subsequent steps with larger increases observed during the desorption portion of the humidity cycling. All three sets of foams showed similar behavior at a given temperature. At a temperature of 40°C, the strain levels under cyclic moisture conditions surpassed those levels observed at the highest constant relative humidity. During the first absorption step, the creep level increased. During any subsequent absorption step, the creep level either increased very little or none at all. Finally, during any desorption step, the creep level increased. This overall phenomenon of enhanced creep under cyclic moisture levels is attributed to water interacting with the hydrogen bonded structure within the foam. These hydrophillic interactions, principally promoted within the hard segment regions due to high hydrogen bonding, are disrupted causing slippage and increased in strain. As the foam is rapidly dired, regions of free volume are induced by the loss of water thus causing further increases in strain Prior to the reestablishment of well ordered hydrogen bonding. Further support to this proposition was given by the results obtained at a temperature of 90° C where it is well known that hydrogen bonds are much more mobile. Here, the strain levels under cyclic moisture conditions were nearly the same as those under constant high relative humidity. Weakening of the hydrogen bonds by means such as increased temperature resulted in similar strain levels to those under cyclic moisture levels. © 1993 John Wiley & Sons, Inc.     

Thermal Characterization of Polyhydroxyalkanoates and Poly(lactic acid) Blends Obtained by Injection Molding

In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0–100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fraction increased the degree of crystallinity of the blend and the miscibility of the base polymers as verified by the Fox model. The WAXD analysis indicates that the presence of PHA hindered the PLA crystallization. The crystallization evolution trough PHA weight fraction (wf) shows a phase inversion around 50-60%. SEM analyses confirmed that the miscibility of PHA/PLA blends increased with the incorporation of PHA and became total for values of PHA higher that 50%.     

Photoinduced electron transfer mechanism between green fluorescent protein molecules and metal oxide nanoparticles

Green fluorescent protein (GFP) molecules are attached to titanium dioxide and cadmium oxide nanoparticles via sol–gel method and fluorescence dynamics of such a protein–metal oxide assembly is investigated with a conventional time correlated single photon counting technique. As compared to free fluorescent protein molecules, time-resolved experiments show that the fluorescence lifetime of GFP molecules bound to these metal oxide nanoparticles gets shortened dramatically. Such a decrease in the lifetime is measured to be 22 and 43 percent for cadmium oxide and titanium dioxide respectively, which is due to photoinduced electron transfer mechanism caused by the interaction of GFP molecules (donor) and metal oxide nanoparticles (acceptor). Our results yield electron transfer rates of 3.139×10⁸ s⁻¹ and 1.182×10⁸ s⁻¹ from the GFP molecules to titanium dioxide and cadmium oxide nanoparticles, respectively. The electron transfer rates show a marked decrease with increasing driving force energy. This effect represents a clear example of the Marcus inverted region electron transfer process.     

Effect of nucleation mechanism on complex poly(L‐lactide) nonisothermal crystallization process,part 2: Crystallization kinetics analysis

In the first part of this article, we reported the crystalline memory effect on the nonisothermal crystallization of poly(L ‐lactide). The experiments were carried out by using polymer single crystals growth from dilute solution as standard starting material. In this article (Part II), we have analyzed in detail the effect of the melting condition on the overall crystallization kinetics by applying the Nakamura‐Avrami model to DSC results. The absence or the low concentration of foreign infusible heterogeneous nuclei in our system allowed us to exalt the self‐nuclei role in polymer crystallization, to follow their concentration decrease during the melting process and to find the limiting melting temperature for their disappearance. Below such a temperature, a stable equilibrium number of self‐nuclei was observed, probably deriving from ordered structures, persisting in the melt, and originated from the single crystals thickening process during the polymer dynamic melting in the DSC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

A tabu-search based heuristic for the hub covering problem over incomplete hub networks

Hub location problems deal with finding the location of hub facilities and with the allocation of demand nodes to these located hub facilities. In this paper, we study the single allocation hub covering problem over incomplete hub networks and propose an integer programming formulation to this end. The aim of our model is to find the location of hubs, the hub links to be established between the located hubs, and the allocation of non-hub nodes to the located hub nodes such that the travel time between any origin–destination pair is within a given time bound. We present an efficient heuristic based on tabu search and test the performance of our heuristic on the CAB data set and on the Turkish network.     

Supply Estimation Using Coevolutionary Genetic Algorithms in the Spanish Electrical Market

The price of electrical energy in Spain has not been regulated by the government since 1998, but determined by the supply from the generators in a competitive market, the so-called electrical pool. A genetic method for analyzing data from this new market is presented in this paper. The eventual objective is to determine the individual supply curves of the competitive agents. Adopting the point of view of the game theory, different genetic algorithm configurations using coevolutionary and non-coevolutionary strategies combined with scalar and multi-objective fitness are compared. The results obtained are the first step toward solving the induction of the optimal individual strategies into the Spanish electrical market from data in terms of perfect oligopolistic behavior.     

Increasing program persistence in professional weight loss programs involving cognitive self-persuasion.

The authors evaluated the effectiveness of a new members' orientation program on attrition for female clients at 6 weight loss centers. 147 clients participated either in a 4-hr motivation enhancement program (MEP) based on cognitive self-persuasion principles from the elaboration likelihood model (ELM) or in 1 of 3 control conditions. The program emphasized the development and maintenance of positive attitudes and behavioral intentions toward regular behavioral education classes. Control groups were time-attention, standard program, and those refusing the new program. Results indicated that clients in the MEP attended significantly more consecutive weeks of classes than others. Results indicate the therapeutic value of cognitive self-persuasion techniques used in the MEP. Suggestions for future clinical studies are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Carbon Fiber Adsorption Using Quantitative Structure-Activity Relationship

Adsorption capacities of adsorbents are necessary for selecting and designing adsorption systems for separation and removal processes, such as air quality control devices, because they are indicators of service life. This paper describes the use of the Dubinin-Radushkevich (DR) equation and the quantitative structure-activated relationship to predict the equilibrium adsorption of select organic vapor by activated carbon fiber (ACF) adsorbents. The DR isotherm parameter, k, depends on the adsorbate as well as the adsorbent, and the prediction for k can be obtained indirectly from the affinity coefficient. A correlation is developed to compute the affinity coefficient from the modified, first-order, valence molecular connectivity index. This method provides an improved way to predict equilibrium adsorption capacities for select volatile organic compound adsorbates and activated carbon fiber adsorbents.     

Self-efficacy expectancy, outcome expectancy, and outcome value: Relative effects on behavioral intentions.

Used a persuasive communications paradigm to examine the relative contributions of self-efficacy expectancy, outcome expectancy, and outcome value (importance) in influencing and predicting behavioral intentions. 88 college students were asked to react to a promotional brochure presented as a discussion of the broken-record technique. Outcome expectancy was manipulated independent of self-efficacy expectancy and had a main effect on behavioral intentions, but self-efficacy expectancy failed to produce a main effect on intentions. The outcome-value manipulation also had a main effect on intentions, although problems with the manipulation check made interpretations of this effect problematic. Correlational data reveal that assessments of self-efficacy expectancy, outcome expectancy, and outcome value were all significant and roughly equivalent predictors of intentions. Each component significantly contributed to the other 2 components combined in the prediction of behavioral intentions. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)