Miscibility and thermal stability of ethyl vinyl acetate and ethylene-octane copolymer blends

Miscibility and thermal stability of ethyl vinyl acetate (EVA) and ethylene octane (EO) copolymer blends with different compositions were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The degradation behavior by TGA data under dynamic conditions in an inert atmosphere shows the blends to be immiscible. The addition of EO improves the thermal stability of EVA for all composition and temperature ranges. Using the DSC experiment, two single crystallization temperatures (T _c) for the blends were obtained and the crystallization and melting enthalpy with compositions abiding by the additive rules, confirm the immiscibility of the blends. The rate of crystallization seems to be independent of blend compositions. The surface morphology using AFM shows a thin and elongated crystallites of pure EO, and a bulky and random morphology for EVA, where a perfect mixture of aforementioned structures for 50/50 blend, with the immiscible domains of both EO and EVA. The 2D-power spectral density (PSD) analysis shows the surface roughness of 50/50 blends is in between of EO and EVA. Both AFM observations and quantitative PSD results, along the line with DSC and TGA. The experimental data for miscibility and stability by TGA, DSC and AFM techniques reveal that blends of EVA/EO are immiscible in the entire range of compositions.     

Blowup in solutions of a quasilinear wave equation with variable‐exponent nonlinearities

We consider, in this paper, the following nonlinear equation with variable exponents: where a,b>0 are constants and the exponents of nonlinearity m,p, and r are given functions. We prove a finite‐time blow‐up result for the solutions with negative initial energy and for certain solutions with positive energy.     

2-Mercaptobenzotellurazole Derivatives Obtained Using a Mercapto Group

Novel 2-mercaptobenzotellurazole derivatives with different functional groups were obtained using its mercapto group.     

Novel synthesis of oxa[9]helicenes by Lawesson’s reagent-mediated cyclization of helical quinone derivatives

New oxa[9]helicenes which possess one furan ring have been readily prepared by reactive helical quinone with Lawesson’s reagent or phosphorus pentasulfide in good yields. The versatility of this protocol has been demonstrated with various substituted helical quinones.     

Preparation and characterization of activated carbon from bagasse fly ash

Activated carbons from bagasse fly ash (BFA) were prepared by one step chemical activation using ZnCl₂ as activating agent, or combination method of chemical with CO₂ physical activation (physicochemical activation). The development of porosity was studied in correlation with the method of activation, activation temperature, and also the chemical weight ratio. A typical sample by the combination method at 600 °C and weight ratio of ZnCl₂:BFA = 2 exhibited micropore volume of 0.528 cc/g, mesopore volume of 0.106 cc/g and surface area of 1200 m²/g. For determining the adsorption capacity of the carbon samples in solutions, phenol and methylene blue equilibrium adsorption experiments were conducted. The properties and adsorption capacity of the synthesized activated carbons has been compared to commercial activated carbon (Norit^® SX Plus).     

A Simple and Effective Approach to Vesicles and Large Compound Vesicles via Complexation of Amphiphilic Block Copolymer With Polyelectrolyte in Water

This work reports for the first time a simple and effective approach to trigger a spheres‐to‐ vesicles morphological transition from amphiphilic block copolymer/polyelectrolyte complexes in aqueous solution. Vesicles and large compound vesicles (LCVs) were prepared via complexation of polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) with poly(acrylic acid) (PAA) in water and directly visualized using cryo‐TEM. The complexation and morphological transitions were driven by the hydrogen bonding between the complementary binding sites on the PAA and PEO blocks of the block copolymer. The findings in this work suggest that complexation between amphiphilic block copolymer and polyelectrolyte is a viable approach to vesicles and LCVs in aqueous media.     

A NAA collaborative study in white rice performed in seven Asian countries

Since 2000, collaborative studies for applying NAA have been performed through the Forum for Nuclear Cooperation in Asia (FNCA) sponsored by the Japanese Government. White rice is a main food for Asians and thus was selected as a common target sample for a collaborative study in 2008. Seven Asian countries including China, Indonesia, Japan, Korea, Malaysia, Philippines and Thailand, are greatly concerned about the composition of arsenic, heavy metals, and essential trace elements and took part in this study. Rice samples were purchased and prepared by following a protocol that had been proposed for this study. Samples were analyzed by their own NAA systems. In each country, more than 10 elements were examined and the results were compared. These data will be very useful in the monitoring of the levels of food contamination and to evaluate the nutritional status for people living in Asia.     

Characteristics of X‐ray attenuation in electrospun bismuth oxide/polylactic acid nanofibre mats

The characteristics of the X‐ray attenuation in electrospun nano(n)‐ and micro(m)‐Bi₂O₃/polylactic acid (PLA) nanofibre mats with different Bi₂O₃ loadings were compared as a function of energy using mammography (i.e. tube voltages of 22–49 kV) and X‐ray absorption spectroscopy (XAS) (7–20 keV). Results indicate that X‐ray attenuation by electrospun n‐Bi₂O₃/PLA nanofibre mats is distinctly higher than that of m‐Bi₂O₃/PLA nanofibre mats at all energies investigated. In addition, with increasing filler loading (n‐Bi₂O₃ or m‐Bi₂O₃), the porosity of the nanofibre mats decreased, thus increasing the X‐ray attenuation, except for the sample containing 38 wt% Bi₂O₃ (the highest loading in the present study). The latter showed higher porosity, with some beads formed, thus resulting in a sudden decrease in the X‐ray attenuation.     

Bridging techniques in a multi-scale modeling of pattern formation

Bridging techniques between microscopic and macroscopic models are discussed in the case of wrinkling analysis. The considered macroscopic models are related to envelope equations of Ginzburg–Landau type, but generally, they are not valid up to the boundary. To this end, a multi-scale approach is considered: the reduced model is implemented in the bulk while the full model is applied near the boundary and these two models are coupled with the Arlequin method (Ben Dhia, 1998). This paper focuses on the definition of the coupling model and the transition between two scales. Especially, a new nonlocal bridging technique is presented and compared with another recent one (Hu et al., 2011). The present method can also be seen as a guide for coupling techniques involving other reduced order models.