Preparation and thermal decomposition of solid-state cinnamates of lighter trivalent lanthanides

Some new compounds of cinnamic acid with lighter trivalent lanthanides were prepared in the solid state. The compounds have general formula ML3·H2O, where L is cinnamate (C6H5-CH=CH-COO-) and M is La, Ce, Pr, Nd or Sm. Thermogravimetry, derivative thermogravimetry, differential scanning calorimetry, infrared absorption spectra and X-ray diffraction powder patterns were used to characterize and to study the thermal stability and thermal decomposition of these compounds.

Solid-state NMR, ionic conductivity, and thermal studies of lithium-doped siloxane-poly(propylene glycol) organic-inorganic nanocomposites

Hybrid organic-inorganic ionic conductors, also called ormolytes (organically modified electrolytes), were obtained by dissolution of LiClO 4 in siloxane-poly(propylene glycol) matrixes. The dynamic features of these nanocomposites were studied and correlated to their electrical properties. Solid-state nuclear magnetic resonance (NMR) spectroscopy was used to probe the effects of the temperature and nanocomposite composition on the dynamic behaviors of both the ionic species ( 7Li) and the polymer chains ( 13C). NMR, dc ionic conductivity, and DSC results demonstrate that the Li + mobility is strongly assisted by the segmental motion of the polymer chain above its glass transition temperature. The ac ionic conductivity in such composites is explained by use of the random free energy barrier (RFEB) model, which is agreement with their disordered and heterogenous structures. These solid ormolytes are transparent and flexible, and they exhibit good ionic conductivity at room temperature (up to 10 -4 S/cm). Consequently, they are very promising candidates for use in several applications such as batteries, sensors, and electrochromic and photoelectro-chemical devices.

Solid state production of thermostable pectinases from thermophilic Thermoascus aurantiacus

Pectin lyase (Pl) and polygalacturonase (Pg) production by Thermoascus aurantiacus 179-5 was carried out by means of solid-state determination using orange bagasse and wheat bran as a carbon sources. Pg and Pl had optimum activity at pH 5.0 and 10.5 respectively. Maximal activity of the enzymes were determined at 65 °C. Pg was stable in the acidic to neutral pH range and at 60 °C for 1 h. whereas Pl was stable at acidic pH and at 60 °C for 5 h. © 2002 Elsevier Science Ltd. All rights reserved.

A thermal behaviour study of solid-state cinnamates of the latter trivalent lanthanides and yttrium(III)

Some new compounds of cinnamic acid with the latter trivalent lanthanides and yttrium(III) were synthesized in the solid state. The compounds have the general formula LnL3, where Ln represents trivalent Eu to Lu or Y ions and L is the cinnamate anion (C6H5-CH=CH-COO-). Thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), infrared absorption spectra and X-ray diffraction powder patterns were used to characterize and to study the thermal behaviour of these compounds. © 2002 Elsevier Science B.V. All rights reserved.

Progress on holographic techniques to study photo-chemical reactions in solid state

In this paper it is presented recent developments in the heterodyne detection holographic techniques for studding photosensitive materials. The actual state of the technique allows simultaneous and independent measurement of the refractive index and of the absorption coefficient changes in photosensitive materials and their use to self-stabilize the fringe pattern. The modeling of the measured signal together with the fringe stabilization allow the long term-fitting of the optical properties and the study the photosensitive materials close to the saturation.

Synthesis, characterization and thermal behaviour of solid-state compounds of 4-methoxybenzoate with some bivalent transition metal ions

Solid-state M-4-MeO-Bz compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to have information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds. © 2005 Akadémiai Kiadó, Budapest.

Mechanochemical synthesis of Bi4Ti3O12

Our efforts were directed to the preparation of bismuth titanate - Bi 4e;Ti3O12 (BIT) by mechanically assisted synthesis. The mechanical activation was applied to prepare bismuth titanate, Bi4e;Ti3O12, from bismuth oxide, Bi 2O3, and titanium oxide, TiO2 (in an anatase crystal form). Mechanochemical synthesis was performed in a planetary ball mill in air atmosphere. Bismuth titanate ceramics was obtained by sintering at 1000° C The formation of Bi4e;Ti3O12 in the sintered samples was confirmed by X-ray diffraction analysis. Scanning electron microscopy, SEM, was used to study the particle size and powder morphology. The obtained results indicate that Bi4e;Ti3O12 from the powder synthesized by high-energy ball milling exhibits good sinterability, showing advantage of the mechanochemical process over conventional solid-state reaction.

Production of cellulolytic and hemicellulolytic enzymes from Aureobasidium pulluans on solid state fermentation

This article investigates a strain of the yeast Aureobasidium pullulans for cellulase and hemicellulase production in solid state fermentation. Among the substrates analyzed, the wheat bran culture presented the highest enzymatic production (1.05 U/mL endoglucanase, 1.3 U/mL β-glucosidase, and 5.0 U/mL xylanase). Avicelase activity was not detected. The optimum pH and temperature for xylanase, endoglucanase and β-glucosidase were 5.0 and 50, 4.5 and 60, 4.0 and 75°C, respectively. These enzymes remained stable between a wide range of pH. The β-glucosidase was the most thermostable enzyme, remaining 100% active when incubated at 75°C for 1 h. © 2007 Humana Press Inc.

Production of pectate lyase by penicillium viridicatum RFC3 in solid-state and submerged fermentation

Pectate lyase (PL) was produced by the filamentous fungus Penicillium viridicatum RFC3 in solid-state cultures of a mixture of orange bagasse and wheat bran (1 : 1 w/w), or orange bagasse, wheat bran and sugarcane bagasse (1 : 1 : 0.5 w/w), and in a submerged liquid culture with orange bagasse and wheat bran (3%) as the carbon source. PL production was highest (1,500U mL -1 or 300Ug -1 of substrate) in solid-state fermentation (SSF) on wheat bran and orange bagasse at 96 hours. PL production in submerged fermentation (SmF) was influenced by the initial pH of the medium. With the initial pH adjusted to 4.5, 5.0, and 5.5, the peak activity was observed after 72, 48, and 24 hours of fermentation, respectively, when the pH of the medium reached the value 5.0. PL from SSF and SmF were loaded on Sephadex-G75 columns and six activity peaks were obtained from crude enzyme fromSSF and designated PL I, II, III, IV, V, andVI, while five peaks were obtained fromcrude enzyme fromSmF and labeled PL I', II', III', IV', and VII'. Crude enzyme and fraction III from each fermentative process were tested further. The optimum pH for crude PL from either process was 5.5, while that for PL III was 8.0. The maximum activity of enzymes from SSF was observed at 35°C, but crude enzyme was more thermotolerant than PL III, maintaining its maximum activity up to 45°C. Crude enzyme from SmF and PL III' showed thermophilic profiles of activity, with maximum activity at 60 and 55°C, respectively. In the absence of substrate, the crude enzyme from SSF was stable over the pH range 3.0-10.0 and PL III was most stable in the pH range 4.0-7.0. Crude enzyme from SmF retained 70%-80% of its maximum activity in the acid-neutral pH range (4.0-7.0), but PIII showed high stability at alkaline pH (7.5-9.5). PL from SSF was more thermolabile than that from SmF. The latter maintained 60% of its initial activity after 1 h at 55°C. The differing behavior of the enzymes with respect to pH and temperature suggests that they are different isozymes. Copyright © 2010 Viviani Ferreira et al.

Impedance spectroscopy study of solid-state dye-sensitized solar cells with varying Spiro-OMeTAD concentration

This work reports on the changes of performance of solid-state cells dye-sensitized solar cells with the variation of concentration of spiro-OMeTAD between 5% and 25% in the fabrication of the cell. Variations of charge recombination and capacitance correlate with the improvement of current-potential characteristics at increasing spiro-OMeTAD content, which is explained by reduction of transport resistance for hole transport, the increase of charge separation in the dye molecules, and importantly, with the increase of the β-factor in the recombination resistance, that causes a reduction of the diode ideality factor. © 2010 Materials Research Society.

Chemical stability and electrical properties of Nb doped BaCe 0.9Y 0.1O 3-δ as a high temperature proton conducting electrolyte for IT-SOFC

BaCe 0.9-xNb xY 0.1O 3-δ (where x=0, 0.01, 0.03 and 0.05) powders were synthesized by solid-state reaction to investigate the influence of Nb concentration on chemical stability and electrical properties of the sintered samples. The dense electrolyte pellets were formed from the powders after being uniaxially pressed and sintered at 1550 °C. The electrical conductivities determined by impedance measurements in temperature range of 550-750 °C in different atmospheres (dry argon and wet hydrogen) showed a decreasing trend with an increase of Nb content. For all samples higher conductivities were observed in the wet hydrogen than in dry argon atmosphere. The chemical stability was enhanced with increasing of Nb concentration. It was found that BaCe 0.87Nb 0.03Y 0.1O 3-δ is the optimal composition that satisfies the opposite demands for electrical conductivity and chemical stability, reaching 0.8×10 -2 S cm -1 in wet hydrogen at 650 °C compared to 1.01×10 -2 S cm -1 for undoped electrolyte. © 2012 Elsevier Ltd and Techna Group S.r.l.

Correlation between photoluminescence and structural defects in Ca 1+x Cu 3 - X Ti 4 O 12 systems

Ca1+xCu3-xTi4O12 powders were synthesized by a conventional solid-state reaction. X-ray diffraction (XRD) was performed to verify the formation of cubic CaCu3Ti4O 12 (CCTO) and orthorhombic CaTiO3 (CTO) phases at long range. Rietveld refinements indicate that excess Ca atoms added to the Ca 1-xCu3-xTi4O12 (x = 1.0) composition segregated in a CaTiO3 secondary phase suggesting that solubility limit of Ca atoms in the CaCu3Ti4O12 lattice was reached for this system. The FE-SEM images show that the Ca 1+xCu3-xTi4O12 (0 < x < 3) powders are composed of several agglomerated particles with irregular morphology. X-ray absorption near-edge structure spectroscopy (XANES) spectra indicated [TiO5Vo z]-[TiO6] complex clusters in the CaCu3Ti4O12 structure which can be associated with oxygen vacancies (Vo z = V o x, Vo •, and Vo ••) whereas in the CaTiO3 powder, this analysis indicated [TiO6]-[TiO6] complex clusters in the structure. Ultraviolet-visible (UV-vis) spectra and photoluminescence (PL) measurements for the analyzed systems revealed structural defects such as oxygen vacancies, distortions, and/or strains in CaCu3Ti4O12 and CaTiO3 lattices, respectively. © 2012 The American Ceramic Society.

Synthesis, characterization and thermal behavior of solid state compounds of heavy trivalent lanthanide succinates

Solid-state Ln-L compounds, where Ln stands for heavy trivalent lanthanides or yttrium(III) (Tb-Lu, Y) and L is succinate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-DTA coupled to FTIR, elemental analysis, X-ray powder diffractometry and complexometry were used to characterize and study the thermal behavior of these compounds. For the terbium to thulium and yttrium compounds, the dehydration, as well the thermal decomposition of the anhydrous compound occurs in two consecutive steps, while ytterbium and lutetium the dehydration occurs in a single step. The results also led to information about the ligand's denticity, thermal stability and thermal decomposition of these compounds. © 2013 Elsevier B.V.

Comparing submerged and solid-state fermentation of agro-industrial residues for the production and characterization of lipase by Trichoderma harzianum

Lipase production by Trichoderma harzianum was evaluated in submerged fermentation (SF) and solid-state fermentation (SSF) using a variety of agro-industrial residues. Cultures in SF showed the highest activity (1.4 U/mL) in medium containing 0.5 % (w/v) yeast extract, 1 % (v/v) olive oil and 2.5 C:N ratio. This paper is the first to report lipase production by T. harzianum in SSF. A 1:2 mixture of castor oil cake and sugarcane bagasse supplemented with 1 % (v/w) olive oil showed the best results among the cultures in SSF (4 U/g ds). Lipolytic activity was stable in a slightly acidic to neutral pH, maintaining 50 % activity after 30 min at 50 C. Eighty percent of the activity remained after 1 h in 25 % (v/v) methanol, ethanol, isopropanol or acetone. Activity was observed with vegetable oils (olive, soybean, corn and sunflower) and long-chain triacylglycerols (triolein), confirming the presence of a true lipase. The results of this study are promising because they demonstrate an enzyme with interesting properties for application in catalysis produced by fermentation at low cost. © 2012 Springer-Verlag and the University of Milan.

Synthesis, characterization and thermal behaviour of solid-state compounds of folates with some bivalent transition metals ions

Solid-state M-L compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG-DSC coupled to FTIR, elemental analysis and high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS FAAS) were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the composition, dehydration, thermal stability and thermal decomposition. © 2013 Akadémiai Kiadó, Budapest, Hungary.