Thermoanalytical study of acetylacetonate-modified titanium(IV) isopropoxide as a precursor for TiO<Subscript>2</Subscript> films

Thermal decomposition of dried TiO₂ gel, obtained by hydrolysing acetylacetonate-modified titanium(IV) isopropoxide, was monitored by simultaneous TG/DTA/EGA-FTIR measurements in dynamic air up to 900&deg;C. XRD and FTIR were employed to identify the solid reaction products. Thermal degradation of the TiO₂ gel consists of five distinct mass loss steps, the total mass loss being 43.8&percnt;. EGA by FTIR revealed the release of H₂O below 120&deg;C; followed by acetone, isopropyl acetate and 1-propanol around 200-300&deg;C, and finally CO and CO₂ up to 550&deg;C. Highly exothermic reaction at 410-550&deg;C is caused by the combustion of carbon residues. Crystalline TiO₂-anatase is formed around 500&deg;C and TiO₂-rutile close to 800&deg;C.     

The effects of cashew gum as anti-hypertensive agent

The effects of cashew gum over heart samples of spontaneously hypertensive rats (SHR) were studied by Thermal Analysis and Micrographs. During the experiment, ten rats received daily by gavage 500 mg/kg of cashew gum (CG groups) and the other ten rats received only fresh water (Control groups). After 17 weeks of experiment, blood pressure in CG groups was approximately 8% lower and after 24 weeks it was 20% lower than Control groups. At seven months of experiment ten rats (five of each group: Control 7 and CG 7) and at nine months of experiment the other rats (Control 9 and CG 9) were sacrificed. Pieces of left ventricle were studied by thermogravimetry (TG), differential thermal analysis (DTA) and microscopy. The myocardial appearance of CG groups showed the presence of greater number of cardiomyocytes and more capillaries among the cells. The myocardium of Control groups showed more areas with diffuse interstitial fibrosis and hypertrophied cardiomyocytes. TG curves depict two steps for all samples. CG 7 and CG 9 presented the least amount of residues (6.0 ± 0.5) in the heart. DTA curves depict two endothermic events (Tpeak1: 85 °C; Tpeak2: 298 °C). The results suggest that cashew gum contributes to improve cardiovascular health of SHR and to postpone the aging process of their hearts.     

Formation of sol-gel nanostructured mullite by additions of fluoride ion

Summary The subject of this study was to investigate the effect of fluoride ions addition on the temperature of sol gel mullite formation based on the hypotheses that the presence of fluoride ions can decrease the temperature of mullite formation (in respect to common 980&deg;C, in sol-gel processing). Polymeric sols were prepared by mixing TEOS and aluminum nitrate nanohydrate and by adding fluoride ions (from 2 to 5 mass&percnt;). DTA, TG, XRD and SEM were used for characterisation of mullite gel and crystalline mullite. The experimental results confirmed that the addition of fluoride ions decrease the temperature of mullite formation up to 890&deg;C for the fluorine concentration of 3.5 mass&percnt;. Experimental results showed that the temperature of mullite formation is not a simple function of the fluoride ion content. The mechanism of fluorine effect was discussed in terms of the gelling process, gel structure and the phase separation before the mullite formation.     

DSC study of glycerol-extracted muscle fibers in intermediate states of ATP hydrolysis

Summary The heat capacity of contractile proteins actin and myosin was studied in psoas muscle of rabbit in strongly and weakly binding state of myosin to actin as a function of temperature by DSC. Deconvolution of the unfolding scans makes possible to characterize the structural domains of the macromolecules. We tried to approach the unfolding process in different intermediate state of ATP hydrolysis. The thermal transitions were calorimetrically irreversible, therefore the two-state irreversible model that describes fairly well the denaturation of different proteins was used for evaluation of the denaturation processes in muscle fibers in strongly (rigor, ADP) and weakly binding states (ATP&middot;V_i, ADP&middot;AlF₄) of myosin to actin. Deconvolution resulted in four transitions, the first three transition temperatures were almost independent of the intermediate states of muscle, the last transition temperature was shifted to higher temperature, when the buffer solution was manipulated. The mean values in strongly binding states were T_m1=52.9&plusmn;0.7&deg;C, T_m2=57.9&plusmn;0.7&deg;C, T_m3=63.7&plusmn;1.0&deg;C and T_m4=67.8&plusmn;0.7&deg;C, but the last transition increased to higher temperature depending on the P_i analogue.     

Determination of the <Superscript>240</Superscript>Pu/<Superscript>239</Superscript>Pu atom ratio in global fallout at two locations in the Northern Hemisphere

Summary Extensive soil and sediment sampling was conducted along the Colorado Front Range and the plains east of the Front Range at locations believed to only be exposed to global fallout. The average ²⁴⁰Pu/²³⁹Pu atom ratio in the samples collected in Colorado was determined to be 0.165±0.008. A limited number of samples were collected at various locations in the Arctic at approximately 70° N latitude. Analyses of these samples predict that the ²⁴⁰Pu/²³⁹Pu atom ratio in environmental samples collected at 70° N latitude at locations only containing fallout is 0.183±0.009. These results provide data that help to precisely define the ²⁴⁰Pu/²³⁹Pu atom ratios representative of global fallout at the two locations studied.     

Effect of Fe dopant on the physico-chemical and catalytic properties of vanadyl pyrophosphate catalysts

Summary 1&percnt; of Fe-doped and undoped vanadyl pyrophosphate catalysts were prepared via dihydrate method. The catalysts have been characterised by XRD, ICP, BET and SEM. The undoped catalyst was found to be more active and selective (77.6&percnt; selectivity at about 60 &percnt; conversion at 703 K).     

Simultaneous determination of paeoniflorin from total glucosides of paeony in Sprague–Dawley rats and spontaneously hypertensive rats by high‐performance liquid chromatography–tandem mass spectrometry: in vivo and in vitro studies

Paeoniflorin is a well‐known monoterpene glucoside in the herbal drug that exhibits a number of biological activities. The pharmacokinetic characteristics of paeoniflorin from total glucosides of paeony in spontaneously hypertensive rats (SHR) are still unclear. It is essential to investigate the in vivo and in vitro pharmacokinetic differences of paeoniflorin from total glucosides of paeony in Sprague–Dawley (SD) and SHR. The in vivo pharmacokinetic data were analyzed using DAS 2.0 software and the in vitro metabolic characteristics were measured using rat hepatic microsomes. The concentration of paeoniflorin in biological samples was determined using high‐performance liquid chromatography–electrospray ionization tandem mass spectrometry method, which showed good precision and stability. The plasma concentration–time profiles of paeoniflorin following oral administration of total glucosides of paeony showed a single peak and there were significant differences in the mean values of AUC_(0–t), AUC_(0–∞), CL_z/F and T_max between SD and SHR (p < 0.05). The metabolic rate of paeoniflorin from total glucosides of paeony was slower in SHR than in SD rats (p < 0.05). The results might be useful in further applications of paeoniflorin and total glucosides of paeony. Copyright © 2016 John Wiley & Sons, Ltd.     

Eine Apparatur zur Bestimmung von Dampf-Flüssigkeits-Gleichgewichten unter erhöhtem Druck

An apparatus for determination of vapor-liquid-equilibria at elevated pressure is described. For the measurements the static method with mechanical mixing of the phases is used. The apparatus has a working range of +15 to +100°C and 5 to 100 bar. For sampling capillaries and a specially constructed valve are used, whereby gaseous and liquid samples can be lead directly into the carrier-gas stream of a gaschromatograph. The equipment was tested by measurement of equilibrium-data of the binary system Ethane/Propane at +30°C. A consistency test of these experimental data showed agreement with theory within the mean errors of the equipment, which are ±0,05 bar for pressure, ±0,04°C for temperature and ±0,002 for concentration in the molefraction-scale.

     

The ion exchange characteristics of antimonic acid

Two antimonic acid samples were prepared and designated as hydrolyzed (H-SbA) and refluxed (R-SbA) antimonic acids. Their structure and ion exchange behavior towards Na⁺ as a simple ion is investigated. R-SbA samples showed higher degree of crystallinity and slightly higher ion exchange capacity than the other sample although it had slightly lower water content. Thermal treatment of both samples showed an increase in their ion exchange capacity on heating up to 200 °C. On further heating up to 400 °C the capacity is appreciably decreased. Equilibria measurements of both samples in dilute solutions showed almost an ideal ion exchange behavior. The obtained data are discussed in detail.     

Curie temperature in Fe(Ni)Nb based mechanically alloyed materials

Summary A conventional thermogravimeter has been adapted with a small magnet to detect the Curie temperature, T_C. The measurements were performed in several Fe(Ni)NbB alloys developed in a nanocrystalline form by mechanical alloying. The B addition favors a slight diminution (10-20&deg;C), and the Ni addition the existence of three transitions related with bccFe, fcc(Fe-Ni) abd fccNi-rich environments. Furthermore, complementary analysis were performed by means of differential thermal analysis, scanning electron microscopy with energy dispersive X-ray microanalysis and by induced coupled plasma. Small contamination was found. A mass increase (about 1 mass&percnt;) was detected by thermogravimetry related to oxidation. Analysis allows us to state the inhomogeneity of the alloys obtained after 80 h of milling.     

Effect of hydrothermal treatment on properties of Ni-Al layered double hydroxides and related mixed oxides

The Ni-Al layered double hydroxides (LDHs) with Ni/Al molar ratio of 2, 3, and 4 were prepared by coprecipitation and treated under hydrothermal conditions at 180 °C for times up to 20 h. Thermal decomposition of the prepared samples was studied using thermal analysis and high-temperature X-ray diffraction. Hydrothermal treatment increased significantly the crystallite size of coprecipitated samples. The characteristic LDH diffraction lines disappeared completely at ca. 350 °C and a gradual crystallization of NiO-like mixed oxide was observed at higher temperatures. Hydrothermal treatment improved thermal stability of the Ni2Al and Ni3Al LDHs but only a slight effect of hydrothermal treatment was observed with the Ni4Al sample. The Rietveld refinement of powder XRD patterns of calcination products obtained at 450 °C showed a formation of Al-containing NiO-like oxide and a presence of a considerable amount of Al-rich amorphous component. Hydrothermal aging of the LDHs resulted in decreasing content of the amorphous component and enhanced substitution of Al cations into NiO-like structure. The hydrothermally treated samples also exhibited a worse reducibility of Ni²⁺ components. The NiAl₂O₄ spinel and NiO still containing a marked part of Al in the cationic sublattice were detected in the samples calcined at 900 °C. The Ni2Al LDHs hydrothermally treated for various times and related mixed oxides obtained at 450 °C showed an increase in pore size with increasing time of hydrothermal aging. The hydrothermal treatment of LDH precursor considerably improved the catalytic activity of Ni2Al mixed oxides in N₂O decomposition, which can be explained by suppressing internal diffusion effect in catalysts grains.     

Method development for the determination of cadmium in fertilizer samples using high-resolution continuum source graphite furnace atomic absorption spectrometry and slurry sampling

The determination of cadmium (Cd) in fertilizers is of major interest, as this element can cause growth problems in plants, and also affect animals and humans. High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with charge-coupled device (CCD) array detection overcomes several of the limitations encountered with conventional line source AAS, especially the problem of accurate background measurement and correction. In this work an analytical method has been developed to determine Cd in fertilizer samples by HR-CS GF AAS using slurry sampling. Both a mixture of 10 μg Pd + 6 μg Mg in solution and 400 μg of iridium as permanent modifier have been investigated and aqueous standards were used for calibration. Pyrolysis and atomization temperatures were 600 °C and 1600 °C for the Pd-Mg modifier, and 500 °C and 1600 °C for Ir, respectively. The results obtained for Cd in the certified reference material NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer) of 16.7 ± 1.3 μg g⁻¹ and 16.4 ± 0.75 μg g⁻¹ for the Pd-Mg and Ir modifier, respectively, were statistically not different from the certified value of 16.9 ± 0.2 μg g⁻¹ on a 95% confidence level; however, the results obtained with the Ir modifier were significantly lower than those for the Pd-Mg modifier for most of the samples. The characteristic mass was 1.0 pg for the Pd-Mg modifier and 1.1 pg Cd for the Ir modifier, and the correlation coefficients (R²) of the calibration were > 0.99. The instrumental limits of detection were 7.5 and 7.9 ng g⁻¹, and the limits of quantification were 25 and 27 ng g⁻¹ for Pd-Mg and Ir, respectively, based on a sample mass of 5 mg. The cadmium concentration in the investigated samples was between 0.07 and 5.5 μg g⁻¹ Cd, and hence below the maximum value of 20 μg g⁻¹ Cd permitted by Brazilian legislation.     

Effect of External Pressure and Solvent on the Equilibrium Constant of the Diels-Alder Reaction of 9-Chloroanthracene with Tetracyanoethylene

The effect of external pressure and solvent on the equilibrium constant of the Diels-Alder reaction of tetracyanoethylene with 9-chloroanthracene at 25°C was studied. The molar reaction volume is strongly solvent-dependent, cm³/mol: -11.3±1.0 in o-xylene, -14.9±1.0 in toluene, -20.6±1.5 in 1,2-dichloroethane, -22.6±1.5 in ethyl acetate, and -24.2±1.5 in acetonitrile.