Influence of calcium carbonate filler and mixing type process on structure and properties of styrene–acrylonitrile/ethylene–propylene–diene polymer blends

The properties of styrene–acrylonitrile (SAN) and ethylene–propylene–diene (EPDM) blends containing different types of calcium carbonate filler were studied. The influence of mixing type process on the blend properties was also studied. Two different mixing processes were used. The first one includes mixing of all components together. The other process is a two‐step mixing procedure: masterbatch (MB; EPDM/SAN/filler blend) was prepared and then it was mixed with previously prepared polymer blend. Surface energy of samples was determined to predict the strength of interactions between polymer blend components and used fillers. The phase morphology of blends and their thermal and mechanical properties were studied. From the results, it can be concluded that the type of mixing process has a strong influence on the morphological, thermal, and mechanical properties of blends. The two‐step mixing process causes better dispersion of fillers in blends as well as better dispersion of EPDM in SAN matrix, and therefore, the finest morphology and improved properties are observed in blends with MB. It can be concluded that the type of mixing process and carefully chosen compatibilizer are the important factors for obtaining the improved compatibility of SAN/EPDM blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Investigation of Scents on Cheeks and Foreheads of Large Felines in Connection to the Facial Marking Behavior

We investigated head- and cheek-rubbing behavior in four species of large felines, lions (Leo panther), leopards (Panthera pardus), tigers (Panthera tigris), and cougars (Puma concolor), in captivity. Preliminary behavioral observations found that lions and tigers, but not leopards and cougars, showed behavioral responses to cardboard rubbing samples from head and cheek areas from conspecific felines, compared to the blank cardboard controls. In this context, surface samples on the facial areas of each species were collected to analyze volatile organic compounds that could be involved in the facial marking of felines. Previously developed stir bar surface sampling methodology was used. From all cheek and forehead samples, 100 volatile organic compounds were identified or tentatively identified. Among these, 41 have been previously reported to be present in feline urine and marking secretions. Several new compounds were identified on facial surfaces. Some of the compounds showed substantial quantitative differences among the species. One compound, that has not been reported previously in mammals, 3-acetamidofuran, was found in all investigated species. It was synthesized and tested for behavioral responses. No responses were elicited in a preliminary test. Future research will test other potential signaling compounds and their mixtures for ability to elicit behavioral responses.     

Preliminary investigations of the production of MgAlON bonded refractories

The aim of the work was to find an appropriate composition for the formation of MgAlON bonding phase for Al₂O₃ and MgO based refractories. The first step was the preparation of pure MgAlON. AlN and Al₂O₃ were used as starting powders and either MgO or MgAl₂O₄ was added as a source of magnesium. The results verified the possibility to produce MgAlON under the prevailing conditions. Afterwards, MgAlON bonded alumina and magnesia refractories were investigated. The obtained results confirmed the possibility of the production of MgAlON bonded alumina refractories. However, in the case of magnesia-based samples MgAlON was not formed and instead stoichiometric spinel, AlN and alumina rich spinel were detected in the bonding phase. Additionally, the joining between the MgO grains and the matrix was poor with wide gaps on the interface.     

Nanocrystaline solid solution CeO2–Bi2O3

Nanocrystalline powders of solid solution CeO₂–Bi₂O₃ were synthesized by self-propagating room temperature reaction (SPRT) procedure with composition (Ce_1?xBi_xO_2?δ where the x = 0.1–0.5). X-ray diffraction analyses show that for x < 0.50 a solid solution with fluorite structure is formed. Rietveld's structure refinement method was applied to characterize prepared powders and its microstructure (size–strain). The lattice parameters increase according to Vegard's rule with increasing of Bi concentration. The average crystallite size is about 2–3 nm. Spectroscopic ellipsometry and Raman scattering measurements were used to characterize the samples at room temperature. The Raman measurements demonstrated electron molecular vibrational coupling and increase of oxygen vacancy concentration whereas increase of Bi content provokes a small decrease of optical absorption edge in comparison with pure ceria. Specific surface area of obtained powders was measured by Brunauer–Emmet–Teller (BET) method.     

The effect of nano-structured alumina coating on the bond strength of resin-modified glass ionomer cements to zirconia ceramics

The purpose of this study was to evaluate the effect of Y-TZP ceramic surface functionalization with a nano-structured alumina coating on bond strength of the resin modified glass ionomer dental cement. A total of 160 disc-shaped specimens were produced and randomly divided into two groups of 80. Half of the discs in each group received an alumina coating which was fabricated by exploiting the hydrolysis of aluminum nitride (AlN) powder. The shear bond strengths of the resin-modified glass ionomer cement FUJI+ (GC Japan) and the composite resin luting agent RelyX Unicem (3M ESPE, USA) were then studied for the coated and uncoated surfaces The SEM analyses revealed that the application of an alumina coating to the Y-TZP ceramics created a highly retentive surface for bonding. The bond strengths for the coated groups in both cements were significantly higher than the uncoated groups.     

Luminescence during anodization of magnesium alloy AZ31

In this paper, we have presented our recent investigation of luminescence during anodization of magnesium alloy AZ31 at 100 mA/cm² in water solution containing 4 g/L Na₂SiO₃·5H₂O + 4 g/L KOH. Spectral characterization of anodic luminescence (galvanoluminescence GL) showed that there are wide GL bands in the range from 375 nm to 875 nm, with three spectral peaks around 430 nm, 600 nm and 780 nm. As the anodization voltage approaches the breakdown voltage, a large number of microdischarges appear superimposed on the GL. The microdischarges characteristics above breakdown (so-called plasma electrolytic oxidation PEO) were studied using real-time imaging. The spatial density of microdischarges is the highest in the early stage of PEO, while the percentage of oxide coating area covered by active discharge sites has maximum after about 120 s from the beginning of PEO and then stays almost constant. The elements present in PEO microdischares were identified using optical emission spectroscopy technique.     

Numerical modelling of calcination reaction mechanism for cement production

Calcination is a thermo-chemical process, widely used in the cement industry, where limestone is converted by thermal decomposition into lime CaO and carbon dioxide CO₂. The focus of this paper is on the implementation and validation of the endothermic calcination reaction mechanism of limestone in a commercial finite volume based CFD code. This code is used to simulate the turbulent flow field, the temperature field, concentrations of the reactants and products, as well as the interaction of particles with the gas phase, by solving the mathematical equations, which govern these processes. For calcination, the effects of temperature, decomposition pressure, diffusion and pore efficiency were taken into account. A simple three-dimensional geometry of a pipe reactor was used for numerical simulations. To verify the accuracy of the modelling approach, the numerical predictions were compared with experimental data, yielding satisfying results and proper trends of physical parameters influencing the process.     

Stereometric analysis of nanostructured boehmite coatings synthesized by aluminum nitride powder hydrolysis

We studied the morphological properties of precipitated, nanostructured, boehmite coatings on a polished alumina surface by exploiting the aluminum nitride (AlN) powder hydrolysis at elevated temperatures. The hydrolysis tests of the 3 wt% AlN powder suspensions in the temperature range 50–90 °C were performed in order to estimate the time needed for the synthesis of the coatings. They consisted of interlocked boehmite lamellas, positioned perpendicularly to the ceramic surface, and they exhibited a strong temperature-dependent size and surface density. The aim of this research was a quantitative assessment of the as-formed boehmite coatings. Based on electron microscopy micrographs, a stereometric analysis of the as-prepared coatings was performed in order to estimate the relevant geometric parameters of the lamellas. In spite of the temperature-dependent lamellas’ size and surface density, the specific volume of the coatings was similar for all the synthesis temperatures.     

Microencapsulation of cashew apple (Anacardium occidentale,L.) juice using a new chitosan–commercial bovine whey protein isolate system in spray drying

The aim of this work was to obtain a new stable food product from cashew apple juice encapsulated by spray-drying technique using chitosan–whey protein isolate systems. The materials were evaluated according to their physicochemical stability during storage at different conditions and characterized with respect to their particle size distribution and structure. Encapsulated commercial and natural juices showed homogenous and unimodal particle size distribution with diameters ranging from 0.2 to 5.0 μm and from 0.2 to 40.0 μm, respectively. Both juices demonstrated higher physicochemical stability for vitamin C and color measurements than their respective non-encapsulated juices. X-ray diffractograms evidenced that the powder juices after the 140th day of storage were still in amorphous state. These results indicate that the new product was effective in protecting sensitive compounds present in the food matrix and it was also able to remain stable throughout the study period.