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In multiphase flow analyses, rheological behavior has a significant influence on not only the heat and mass transfer but also the dynamics of the solid and fluid during melting and solidification. Based on previous work, it is possible to consider rheological behavior by estimating the viscosity of the liquid phase with its compositional development. The present study investigates this rheological behavior through simulations of multiphase heat transfer problems using the moving finite volume particle (FVP) method, by introducing a viscosity model that takes into account viscosity changes due to phase changes. To validate the applicability of this viscosity model, a series of melting experiments using Wood's metal are conducted, and the observed melting characteristics form the basis for computer simulations and 3D numerical analysis using the FVP method. Good agreement between simulation and experiment indicates that the proposed viscosity model reproduces well the rheological behavior during melting.

Summary: Blends of M-LLDPE and CAB were prepared in an internal laboratory mixer with 5, 10, 20, 30, 40 and 50 wt.‐% of CAB. Structure and properties of the blends were studied by means of tensile tests, DSC, SEM, extraction with a selective solvent, Raman spectroscopy and XRD. Blends prepared with 5 and 10 wt.‐% of CAB displayed the best mechanical properties. SEM and extraction with a selective solvent followed by Raman spectroscopy showed good interfacial adhesion between CAB and M‐LLDPE. No significant change on the melting temperatures (Tm) of the M‐LLDPE/CAB blends could be observed when compared with the Tm obtained for pure M‐LLDPE. XRD demonstrated that the addition of CAB has no influence on the lattice constants of M‐LLDPE, but the introduction of CAB increased the amorphous region, confirming that the miscibility occurs on the amorphous region of the polyethylene.SEM image of the cryofracture surface of CAB-20%.

Dopamine oxidation by iron oxide (Fe2O3) was studied in the presence and absence of sodium thiosulfate in aqueous medium around pH7 by UV-Vis spectroscopy. The pHchanges from 6 to 8 indicate that the dopamine oxidation process has occurred producing an anionic semiquinone radical which appears after ca. 100 hours presenting bands at 309 and 337 nm. It forms a stable compound with Fe(III) released by the iron oxide. The complex [CTA][Fe(SQ)2(CAT)], where SQ=semiquinone, CAT=catecholate, and CTA=cetyltrimethylammonium cation, was isolated by precipitation with cetyltrimethylammonium bromide and was characterized through EPR, Ramanand IR spectroscopies. The EPR spectrum presented two intense bands, one with g=2.003 assigned to o-semiquinone and the other with g=4.274 characteristic for high spin Fe(III) approaching an octahedral symmetry. The most intense Ramanresonance band occurs at 1360 cm−1assigned to ν(C1–C2) and at 1575 cm−1to ν(C–C)ring of the o-semiquinone. The O2dissolved in solution is mainly responsible for the dopamine oxidation when sodium thiosulfate is present. A thermal decomposition mechanism based on the thermogravimetric curves (TG) was proposed. These results suggest that iron can participate in the degenerative process of the dopaminergic nigral neurons. Its role seems to be its coordination with the dopamine oxidation products as o-semiquinone and catecholate which could damage neurons giving rise to parkinsonism.

Summary. The complexes [ CTA][Mn(II)( SQ) 3] were isolated in the solid state and purified. SQ is the o-semiquinone of L-dopa or dopamine and CTA is the cetyltrimethylammonium cation. These complexes were characterized by Raman, infrared, EPR and thermogravimetry (TG) techniques. The EPR spectra of the solids presented an intense signal characteristic of the o-semiquinone radical anion with g=2.0062 and g=2.0063 for L-dopa and dopamine, respectively. Six characteristic lines around the organic radical signal confirm the presence of the Mn 2+ ion. The most intense Raman bands were observed at $\bar{\nu}$ for dopamine and at 1356 cm -1 for L-dopa and assigned to a C–O stretching with major C 1–C 2 character. The absence of an intense Raman band at ca. $\bar{\nu}=1480\,{\rm cm}^{-1}$ , characterizes the ligands as an o-semiquinone radical anion. Broad bands in the $\bar{\nu}=400-750\,{\rm cm}^{-1}$ region can be assigned to deformations associated with the five-member ring chelate including the manganese ion, the oxygens, and the C 1–C 2 bonds. The more intense IR bands for the dopamine and the L-dopa-derived ligands at $\bar{\nu}=1233\ {\rm and} \ 1229\, {\rm cm}^{-1}$ are assigned to $\bar{\nu}$ CO. Mass loss mechanisms for the two complexes, based on the TG results, were proposed and confirm the formula proposed.

The near-infrared spectra (NIR) of polyamide 6 (PA 6), poly(vinyl chloride) (PVC), and polychlorotrifluoroethylene (PCTFE) were measured. The tentative assignment of the overtone and combination frequencies was made with curve fitting calculations and local mode theory. Anharmonicity correction and mechanical frequency were determined from a Birge–Sponer plot. Tentative assignments of stretch overtone frequencies of CH2, NH, and CO functional groups of PA 6 and CH2, and CH functional groups of PVC were made. Anharmonicity corrections of 55, 61, and 20 cm⁻¹ were obtained for CH2, NH, and CO stretch modes of PA 6, respectively, and of 60 and 66 cm⁻¹ for CH2 and CH stretch modes of PVC, respectively. The local mode model seems to be adequate to interpret the origin of the bands observed in NIR spectra of PA 6 and PVC. Anharmonicity corrections of 33, 19, and 16 cm⁻¹ were obtained, respectively, for CF, asymmetrical CF2, and symmetrical CF2 stretch of PCTFE functional groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 199–208, 2002

The kinetics of thermal degradation of polyurethanes (PUR) has been studied by means of high-resolution and constant heating rate thermogravimetry (TG), under nitrogen and synthetic air atmospheres. The high-resolution TG provided a way to increase resolution with decreasing the time of data acquisition. In this mode, the heating rate is dynamically varied to maximize resolution. A method to calculate the kinetic parameters from this technique was used. The TG curves showed two or three decomposition steps, depending on the atmosphere employed. The parameters calculated for the PUR decomposition were the activation energy, reaction order, and preexponential factor. A method to estimate the polymer lifetime was also used. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 910–919, 2001

Living Aspergillus niger cells were entrapped in polyacrylamide gels and employed in both replacement batch and continuous column bioreactors to produce citric acid from sucrose. With the replacement batch bioreactor, increase of citric acid was observed under conditions of higher aeration and of wider surface of immobilized cells. With the continuous bioreactor, the maximum citric acid yield was 39.1 mg/h per 40 g gels. The biocatalyst activity or half-life was 105 days.

Proton nuclear magnetic resonance (NMR) spectra of crotamine, a myotoxic protein from a Brazilian rattlesnake (Crotalus durissus terrificus), have been analyzed. All the aromatic proton resonances have been assigned to amino acid types, and those from Tyr-1, Phe-12, and Phe-25 to the individual residues. ThepH dependence of the chemical shifts of the aromatic proton resonances indicates that Tyr-1 and one of the two histidines (His-5 or His-10) are in close proximity. A conformational transition takes place at acidicpH, together with immobilization of Met-28 and His-5 or His-10. Two sets of proton resonances have been observed for He-17 and His-5 or His-10, which suggests the presence of two structural states for the crotamine molecule in solution.

The Raman and Infrared spectra of solid state (TiCl4 ·POCl3)2 complex have been measured. The assignment for the observed data have been made on an assumption of the C2 h molecular symmetry. The coordination effects have been discussed based on the observed frequencies.

Living Aspergillus terreus cells were entrapped in polyacrylamide gels and employed in both replacement batch and continuous column reactors to produce itaconic acid from glucose.