Kekulé structure count in corazulenic fullerenes

Tiling modification in fullerene modeling can be achieved by some map operations. In this respect, sequences of classical operations, or single generalized operations, were used to obtain corannulene-like azulenic patterns. The aromaticity of such cages tessellated by "corazulenic" supra-faces is discussed in terms of several criteria. Particularly, the number of Kekulé valence structures, was considered as a rough measure of the fullerene aromaticity and implicitely of their stability. The covering was given as a pi-electron partition within some Kekulé valence structures. The well-known geometric index of aromaticity HOMA (harmonic oscillator model of aromaticity) enabled the evaluation of local aromaticity of the discussed supra-faces and brought evidence for several dominant Kekulé valence structures.     

Rheological Properties of Honey from Burkina Faso: Loss Modulus and Complex Viscosity Modeling

This study evaluated the rheological behavior of Burkina Faso honey and the use of exponential and polynomial models to predict the influence of chemical composition and temperature on the viscoelastic parameters: complex viscosity (η*) and loss modulus (G’’). Samples were first characterized by evaluating: water activity, 5-hydroxy methyl furfural, sugars (fructose, glucose, and sucrose), electrical conductivity, moisture, and color. Dynamic rheological properties were obtained at different temperatures (5, 10, 15, 20, 25, 30, and 40°C). All the honeys displayed Newtonian behavior. Complex viscosity and loss modulus can be predicted based on the chemical composition and temperature using polynomial models (R² > 98.00%).     

Post-growth annealing of type-II GaSb/GaAs quantum dots grown with different V/III ratios

We report the influence of V/III beam-equivalent-pressure ratios and post-growth annealing on the photoluminescence of GaSb quantum dots grown on GaAs(1 0 0) by molecular beam epitaxy. Increasing the V/III beam-equivalent-pressure ratio from 3 to 5 and then to 7 results in decreased photoluminescence intensity and redshifts the photoluminescence wavelength. The post-growth annealing blueshifts the quantum dot photoluminescence emission and decreases the full-width-at-half-maximum of the photoluminescence peak when annealing temperature is increased above 800 °C. The blueshift behavior is found to be independent on the V/III ratios indicating a similar atomic interdiffusion mechanism for all investigated samples regardless of the quantum dot properties. The photoluminescence intensities of the three samples experience an increase after moderate annealing. Whereas the intensity of the sample with the highest V/III ratio further increases, the intensity of the sample with lower V/III ratios decreases again upon higher annealing steps above 900 °C. Furthermore, temperature- and power dependent photoluminescence measurements are performed on as-grown and 870 °C annealed samples with V/III ratios of 3 and 7 in order to study the reduced quantum dot confinement in more detail.     

Linear random vibration by stochastic reduced‐order models

A practical method is developed for calculating statistics of the states of linear dynamic systems with deterministic properties subjected to non‐Gaussian noise and systems with uncertain properties subjected to Gaussian and non‐Gaussian noise. These classes of problems are relevant as most systems have uncertain properties, physical noise is rarely Gaussian, and the classical theory of linear random vibration applies to deterministic systems and can only deliver the first two moments of a system state if the noise is non‐Gaussian. The method (1) is based on approximate representations of all or some of the random elements in the definition of linear random vibration problems by stochastic reduced‐order models (SROMs), that is, simple random elements having a finite number of outcomes of unequal probabilities, (2) can be used to calculate statistics of a system state beyond its first two moments, and (3) establishes bounds on the discrepancy between exact and SROM‐based solutions of linear random vibration problems. The implementation of the method has required to integrate existing and new numerical algorithms. Examples are presented to illustrate the application of the proposed method and assess its accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

Emotion regulation and decision making under risk and uncertainty.

It is well established that emotion plays a key role in human social and economic decision making. The recent literature on emotion regulation (ER), however, highlights that humans typically make efforts to control emotion experiences. This leaves open the possibility that decision effects previously attributed to acute emotion may be a consequence of acute ER strategies such as cognitive reappraisal and expressive suppression. In Study 1, we manipulated ER of laboratory-induced fear and disgust, and found that the cognitive reappraisal of these negative emotions promotes risky decisions (reduces risk aversion) in the Balloon Analogue Risk Task and is associated with increased performance in the prehunch/hunch period of the Iowa Gambling Task. In Study 2, we found that naturally occurring negative emotions also increase risk aversion in Balloon Analogue Risk Task, but the incidental use of cognitive reappraisal of emotions impedes this effect. We offer evidence that the increased effectiveness of cognitive reappraisal in reducing the experience of emotions underlies its beneficial effects on decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drug absorption and release properties of crosslinked hydrogels based on diepoxy-terminated poly(ethylene glycol)s and aliphatic polyamines — a study on the effect of the gel molecular structure

Crosslinked hydrogels with well-defined chemical structures and characteristics were prepared through the reaction between diepoxy-terminated poly(ethylene glycol)s of various molecular weights and aliphatic polyamines of different hydrocarbon chain length and functionalities, and the influence of some network parameters (molecular weight between crosslinking points, crosslinking degree, hydrophobic character) upon the absorption and release of drugs of different capacity to interact with the polymer chains was comparatively investigated. Diclofenac sodium (DCFNa) and 5-fluorouracil (5FU) were used as model drugs, based on their dissimilar hydrophobic character and ability of DCFNa to form crown ether-like complexes with PEG chains through the sodium cation. The experiments showed that the most important interactions occurring in these systems were mainly the hydrophobic ones and to a lesser extent the complexation of the Na⁺ ion by the PEG chains. Both of them were in favor of DCFNa, resulting in a larger incorporation and a slower release of this one in comparison with 5FU. For both drugs, loading was larger for hydrogels with shorter PEG chains and/or crosslinked with amines with longer hydrocarbon chain or higher functionality. Drug release tests showed a lower rate for stronger drug–network interactions in agreement with the absorption experiments.     

Thermoelastic Deformations of Cylindrical Multi-Layered Shells Using a Direct Approach

In this article we study the deformation of thermo-elastic multi-layered shells, using a Cosserat model. By this direct approach, the shell-like bodies are modeled as deformable surfaces with a triad of rigidly rotating directors assigned to every point. The thermal effects are described with the help of two independent temperature fields. Concerning cylindrical orthotropic layered shells, we establish a general solution procedure for a class of thermal stresses problems. These analytical solutions are compared in some special cases with the corresponding three-dimensional solutions and thus, the thermo-elastic coupling coefficients for shells are identified in terms of the material/geometrical parameters of the layers. Finally, we present a comparison between our theoretical results and the numerical solutions obtained by a finite element analysis of a 3-layered cylindrical shell.     

应用GT-Styrene~苯乙烯回收技术对裂解汽油的改质分析

通过采用GT-Styrene苯乙烯回收技术对传统的裂解汽油处理工艺进行改进,汽油的产品性能可以得到有效的改善,并回收有价值的苯乙烯产品和得到高质量的混合二甲苯产品。     

Interphase of polyoctenamer-single-wall carbon nanotubes by thermogravimetric analysis in air

Non-isothermal thermogravimetric analysis in air, of polyoctenamer-single wall carbon nanotubes (PO-SWNTs), loaded by various amounts of SWNTs up to 10% wt., at different heating rates (ranging from 5 to 40°C/min) is reported. The thermal degradation in the air of PO_SWNTs is dominated by a main single sigmoidal dependence, assigned to the polymer and eventually polymer-nanofiller interphase, over which a weaker sigmoid assigned to the thermo-oxidative degradation of the nanofiller is superimposed at higher temperatures. The temperature at which the nanocomposite's residual mass fraction reaches x% wt. of the initial mass, T_x%, is reported (for x = 5, 50, and 85). The dependence of T_x% on the heating rate and the loading by nanotubes is analyzed. The temperature derivative of the thermograms defines new parameters (inflection residual mass fraction and inflection temperature) and (degradation) width. Their dependence on the loading by SWNTs was reported. Estimation of the interphase in polymer-based nanocomposites is based on the postulate that the dependence of the inflection temperature on the composition of the nanocomposite obeys a Fox-like dependence, where the bulk polymer and the polymer trapped within the interphase are considered as a blend of two miscible polymers. Complementary Raman, x-ray diffraction, and differential scanning calorimetry support these results.