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Abstract

The synthesis of pigments from the system Ce1−xO2–MxO (M = Cu, Co) was achieved via a polymeric precursors method, Pechini method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of decomposition temperatures due to different exothermal events, which were identified as H2O elimination, organic compounds degradation, and phase formation. X-Ray diffraction patterns show the presence of pure cubic CeO2 phase for the samples with low Cu and Co loading. A decrease of the specific surface area with increasing copper and cobalt content was observed. The UV–visible diffuse reflectance technique was employed to study the optical properties in the 200–800 nm range. Colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The powders presented a variety of colors from yellow for pure CeO2, to brown for the ones loaded with copper and gray for the ones with cobalt.

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Abstract  

The color efficiency of ceramic glaze blue pigments obtained by the Pechini method was presented in this work. The fired pigments and enameled samples were characterized by thermogravimetry (TG) and differential thermal analysis (DTA), XRD, UV-VIS-NIR spectroscopy and CIE-L*a*b* color-measurements. The pigments obtained by the Pechini method present a better solubility in the molten glazes than the pigments obtained by the mechanical mixture of the precursor oxides.

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Abstract  

Norfloxacin (NFX) is a synthetic antibacterial drug. The development of extended release tablets improves the patients’ comfort and compliance, resulting in lower discontinuation of the therapy; with consequently decrease in bacterial resistance. In the present work, the thermal behavior of NFX was investigated using TG and DSC techniques. Isothermal and non-isothermal methods were employed to determine kinetic data of decomposition process. Compatibility studies between NFX and pharmaceutical excipients, including three hydrophilic polymers were carried out in order to develop a new formulation of NFX to obtain extended release tablets with an approved quality.

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A new OPLC method has been established for separation and quantitative determination of three alditols (d -xylitol, l -arabitol, and d -glucitol) and four aldoses (d -xylose, l -arabinose, d -glucose, and l -rhamnose). The aldoses are present in hemicellulose hydrolyzates used as substrates in the production of d -xylitol from d -xylose by yeast, and all seven sugars could be found in the final fermented broth. The separation was performed in approximately sixteen minutes, on aluminum foil-backed silica gel OPLC-HPTLC plates with overrunning elution. Acetonitrile-acetic acid-water, 63 + 33 + 5 ( v/v ), was used as mobile phase. The upper limits of linearity were in the range 140–600 ng and detection limits were 15–50 ng per spot. The method has been used successfully to screen fermentation samples for aldoses and alditols.

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Abstract  

Pb1–xLaxTiO3 (PLT) nanocrystalline powders were obtained by polymeric precursor method. The samples were analyzed by differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques to characterize properly the distinct thermal events occurring during synthesis. The X-ray diffraction patterns show a tetragonal structure for the samples with x=0.10 and 0.15. An increase of the lanthanum concentration to x=0.20 led to a highly symmetric structure, cubic on average. The powders obtained at the end of the synthesis had an average particle size of 30 to 70 nm.

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Abstract  

Al2CoO4–PbCrO4 and Al2CoO4–Pb2CrO5 crystalline powders in different proportions were obtained by the polymeric precursor method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of overlapping decomposition reactions due to different exothermal events, which were identified as H2O and NOx elimination and polymer pyrolysis. The X-ray diffraction patterns of the xAl2CoO4–(1 − x)PbCrO4 and xAl2CoO4–(1 − x)Pb2CrO5 mixed compounds, with x = 1, 0.75, 0.5, 0.25 and 0, were obtained in the crystalline form with their respective phases, and proved consistent with the nominal compositions. The synthesis of these two systems yielded nine different colors and shades.

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Journal of Thermal Analysis and Calorimetry
Authors: C. Xavier, C. Costa, S. Crispim, M. Bernardi, M. Maurera, M. Conceiçăo, E. Longo, and A. Souza

Abstract  

The pigments used in ceramic applications are of nature predominantly inorganic and they should be thermally stable, insoluble in glazing, resistant to the chemical and physical agents' attacks. This work aimed at the synthesis by the polymeric precursor method of ZrO2-based inorganic pigments, doped with Fe, Ni, Co, Cr and Cu cations. The fired pigments were characterized by thermogravimetry (TG), differential thermal analysis (DTA) and X-ray diffraction (XRD). Among the metals used to zirconium-doping, the best result was achieved with the cations Cu, which presented the monophase pigment, even as 20 mol% of dopant. Up to the temperature of 1000C the pigments presented a good thermal stability.

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Abstract

Zinc oxide is a widely used white inorganic pigment. Transition metal ions are used as chromophores and originate the ceramic pigments group. In this context, ZnO particles doped with Co, Fe, and V were synthesized by the polymeric precursors method, Pechini method. Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to accurately characterize the distinct thermal events occurring during synthesis. The TG and DSC results revealed a series of decomposition temperatures due to different exothermal events, which were identified as H2O elimination, organic compounds degradation and phase formation. The samples were structurally characterized by X-Ray diffractometry revealing the formation of single phase, corresponding to the crystalline matrix of ZnO. The samples were optically characterized by diffuse reflectance measurements and colorimetric coordinates L*, a*, b* were calculated for the pigment powders. The pigment powders presented a variety of colors ranging from white (ZnO), green (Zn0.97Co0.03O), yellow (Zn0.97Fe0.03O), and beige (Zn0.97V0.03O).

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Little is known of how changes in plant function may influence adaptive traits amongst animals further up the food chain. We addressed the hypothesis that shifts in plant functional traits are associated with the adaptive function of animal species which have an indirect trophic link. We compared community characteristics and functional traits of two trophically detached biotic groups (vascular plants and carabid beetles) along a primary succession on terrain at the Cedec glacier in the Alps, where deglaciation events following post-Little Ice Age climate warmings are marked by moraine ridges. Morphofunctional traits were recorded: canopy height (CH), leaf dry matter content (LDMC), leaf dry weight (LDW) and specific leaf area (SLA) (for plants) and the number of brachypterous, autumn-breeding and predator species, and average body length (for carabid beetles). We found that vegetation cover and plant species richness gradually increased throughout early succession, with an abrupt increase between 40 and 150 years after deglaciation. At the early stages of the succession plant traits were typical of ruderal species (high SLA, low CH, LDW) whilst a shift in traits towards stress-tolerance (low SLA) occurred >150 years. Carabid communities and traits changed alongside changes in plant species richness and cover, with late successional vegetation hosting larger, more diverse, less mobile carabid species with longer larval development. Thus, ruderal plant strategies are the main contributors during vegetation development, determining vegetation quantity, and probably have the greatest impact on changes in carabid assemblages by regulating resource availability. Plants then require greater stress-tolerance to survive in stable vegetation, which supports high carabid diversity. This suggests that different plant strategies may affect ground beetle communities via contrasting mechanisms: both quantities (biomass, species richness) and qualities (functional traits, adaptive strategies) should be taken into account during studies of plant-animal interactions within ecosystems.

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Abstract  

The synthesis and the characterization of Al2O3-based nanocrystalline inorganic pigments are reported. The pigments were synthesized by the polymeric precursor (Pechini method) using Cr2O3 as chromophore. XRD results only evidenced the corundum phase. The average particle size was about 34 nm. The samples were also characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG), and CIE-L*a*b* calorimetry. The pigments obtained in this work presented different colors, ranging from green to rose.

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