Thermal decomposition of solid state compounds of lanthanide and yttrium benzoates in CO2 atmosphere

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Synthesis, characterization and thermal behaviour of solid 2-methoxycinnamylidenepyruvate of some bivalent metal ions in CO2 and N2 atmospheres

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ultrasonographic analysis of senile cataractous lens of dogs and its correlation to phacoemulsification

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of varying amounts of thermal cycling on bond strength and permanent deformation of two resilient denture liners

Statement of problem. Two problems found in prostheses with resilient liners are bond failure to the acrylic resin base and increased permanent deformation due to material aging.Purpose. This in vitro study evaluated the effect of varying amounts of thermal cycling on bond strength and permanent deformation of 2 resilient denture liners bonded to an acrylic resin base.Material and methods. Plasticized acrylic resin (PermaSoft) or silicone (Softliner) resilient lining materials were processed to a heat-polymerized acrylic resin (QC-20). One hundred rectangular specimens (10 X 10-mm(2) cross-sectional area) and 100 cylindrically-shaped specimens (12.7-mm diameter X 19.0-mm height) for each liner/resin combination were used for the tensile and deformation tests, respectively. Specimen shape and liner thickness were standardized. Specimens were divided into 9 test groups (n=10) and were thermal cycled for 200, 500, 1000, 1500, 2000, 2500, 3000, 3500, and 4000 cycles. Control specimens (n=10) were stored for 24 hours in water at 37degreesC. Mean bond strength, expressed as stress at failure (MPa), was determined with a tensile test using a universal testing machine at a crosshead speed of 5 mm/min. Analysis of failure mode, expressed as a percent (%), was recorded as either cohesive, adhesive, or both, after observation. Permanent deformation, expressed as a percent (%), was determined using ADA specification no. 18. Data from both tests were examined with a 2-way analysis of variance and a Tukey test (alpha=.05).Results. For the tensile test, Softliner specimens submitted to different thermal cycling regimens demonstrated no significantly different bond strength values from the control; however, there was a significant difference between the PermaSoft control group (0.47 +/- 0.09 MPa [mean +/- SD]) and the 500 cycle group (0.46 +/- 0.07 MPa) compared to the 4000 cycle group (0.70 +/- 0.20 MPa) (P<.05). With regard to failure type, the Softliner groups presented adhesive failure (100%) regardless of specimen treatment. PermaSoft groups presented adhesive (53%), cohesive (12%), or a combined mode of failure (35%). For the deformation test, there was no significant difference among the Softliner specimens. However, a significant difference was observed between control and PermaSoft specimens after 1500 or more cycles (1.88% +/- 0.24%) (P<.05).Conclusions. This in vitro study indicated that bond strength and permanent deformation of the 2 resilient denture liners tested varied according to their chemical composition.

Effect of thermocycling on bond strength and elasticity of 4 long-term soft denture liners

Statement of problem. Two problems found in prostheses with soft liners are bond failure to the acrylic resin base and loss of elasticity due to material aging.Purpose. This in vitro study evaluated the effect of thermocycling on the bond strength and elasticity of 4 long-term soft denture liners to acrylic resin bases.Material and methods. Four soft lining materials (Molloplast-B, Flexor, Permasoft, and Pro Tech) and 2 acrylic resins (Classico, and Lucitone 199) were processed for testing according to manufacturers' instructions. Twenty rectangular specimens (10 X 10-mm(2) cross-sectional area) and twenty cylinder specimens (12.7-mm diameter X 19.0-mm height) for each liner/resin combination were used for the tensile and deformation tests, respectively. Specimen shape and liner thickness were standardized. Samples were divided into a test group that was thermocycled 3000 times and a control group that was stored for 24 hours in water at 37degreesC. Mean bond strength, expressed in megapascals (Wa), was determined in the tensile test with the use of a universal testing machine at a crosshead speed of 5 mm/min. Elasticity, expressed as percent of permanent deformation, was calculated with an instrument for measuring permanent deformation described in ADA/ANSI specification 18. Data from both tests were examined with 1-way analysis of variance and a Tukey test, with calculation of a Scheffe interval at a 95% confidence level.Results. In the tensile test under control conditions, Molloplast-B (1.51 +/- 0.28 MPa [mean SD]) and Pro Tech (1.44 +/- 0.27 MPa) liners had higher bond strength values than the others (P < .05). With regard to the permanent deformation test, the lowest values were observed for Molloplast-B (0.48% +/- 0.19%) and Flexor (0.44% +/- 0.14%) (P < .05). Under thermocycling conditions, the highest bond strength occurred with Molloplast-B (1.37 +/- 0.24 MPa) (P < .05) With regard to the deformation test, Flexor (0.46% +/- 0.13%) and Molloplast-B (0.44% +/- 0.17%) liners had lower deformation values than the others (P < .05).Conclusion. The results of this in vitro study indicated that bond strength and permanent deformity values of the 4 soft denture liners tested varied according to their chemical composition. These tests are not completely valid for application to dental restorations because the forces they encounter are more closely related to shear and tear. However, the above protocol serves as a good method of investigation to evaluate differences between thermocycled and control groups.

Role of inflammatory mediators in priming, activation, and deformability of bovine neutrophils

Objective-To determine the capacity of inflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8), platelet-activating factor (PAF), lipopolysaccharide (LPS), and leukotoxin to prime, activate, or alter deformability of adult bovine neutrophils.Sample Population-Blood collected from 5 healthy adult Holstein cows.Procedure-Isolated neutrophils or whole brood was incubated with TNF-alpha, IL-8, PAF, LPS, or leukotoxin, and neutrophil chemiluminescence, degranulation, deformability, shape change, CD11b expression, and size distribution was measured.Results-incubation with TNF-alpha, IL-8; PAF, and IFS primed neutrophils for oxygen radical release but caused minimal oxygen radical release by themselves. None of the inflammatory mediators induced degranulation. Incubation with TNF-alpha and PAF resulted in a decrease in neutrophil deformability and induced shape change in neutrophils. incubation with PAF consistently resulted in an increase in neutrophil size as measured by use of flow cytometry. Only IL-8 caused an increase in expression of CD11b by neutrophils.Conclusions and Clinical Relevance-Inflammatory mediators tested had minimal effects on neutrophil oxygen radical production or degranulation but did prime neutrophils for oxygen radical production. Incubation with PAF and TNF-alpha caused a decrease in neutrophil deformability and altered neutrophil shape and size. Results of our study indicate that PAF- and TNF-alpha-induced changes in neutrophil deformability and size may cause integrin- and setectin-independent trapping of neutrophils in the lungs of cattle with pneumonic pasteurellosis.

Light and scanning electron microscopic study of the palatine mucosa of nine-banded armadillo (Dasypus novemcinctus)

The three-dimensional structure of the lamina propria of the hard and soft palatine mucosa of the nine-banded armadillo was observed by scanning electron microscopy. Sodium hydroxide cell maceration method was applied to demonstrate the architecture of the connective tissue papillae. The palatine mucosa of the armadillo had a triangular shape and measured appr. 6.5 cm length. The hard palate showed 9 transverse palatine plicae while the soft palate was smooth. In the 10% NaOH treated specimens, the lamina propria of the hard palatine mucosa showed numerous connective tissue papillae with a general finger-like shape. These structures were composed by a meshwork of collagen fibers arranged in several directions. on the other hand, the connective tissue papillae of the soft palate mucosa were scattered and small. Numerous openings of glandular ducts with circular or elliptical shape were located in the interplicae area and in the soft palate.

Solid-state compounds of 2-chlorobenzylidenepyruvate with some bivalent metal ions - Synthesis, characterization and thermal behaviour

Solid-state M-2-Cl-BP, where M stands for Mn, Fe, Co, Ni, Cu, Zn and Pb and 2-Cl-BP is 2-chlorobenzylidenepyruvate, have been synthesized. Thermogravimetry and derivative thermogravimetry (TG/DTG), simultaneous thermogravimetry and differential thermal analysis (TG-DTA), 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 information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds.

Polar Multiplicities and Euler obstruction of the stable types in weighted homogeneous map germs from C-n to C-3 n >= 3

In this article we show that for corank 1, quasi-homogeneous and finitely determined map germs f : (C-n, 0)-> (C-3, 0), n >= 3 one can obtain formulae for the polar multiplicities defined on the following stable types of f, f(Delta(f) and f(Sigma(n-2,1)(f), in terms of the weights and degrees of f. As a consequence we show how to compute the Euler obstruction of such stable types, also in terms of the weights and degrees of f.

Unusual interactions binding iron tetrasulfonated phthalocyanine and poly(allylamine hydrochloride) in layer-by-layer films

Molecular-level interactions are found to bind iron tetrasulfonated phthalocyanine (FeTsPc) and the polyelectrolyte poly(allylamine hydrochloride) (PAH) in electroactive layer-by-layer (LBL) films. These interactions have been identified by comparing Fourier transform infrared (FTIR) and Raman spectroscopy data from bulk samples of FeTsPc and PAH with those from FeTsPc/PAH LBL films. of particular importance were the SO3- -NH3 interactions that we believe to bind PAH and FeTsPc and the interactions between unprotonated amine groups of PAH and the coordinating metal of the phthalocyanine. The multilayer formation was monitored via UV-vis spectroscopy by measuring the increase in the Q band of FeTsPc at 676 nm. Film thickness estimated with profilometry was ca. I I Angstrom per bilayer for films adsorbed on glass. Reflection absorption infrared spectroscopy (RAIRS) revealed an anisotropy in the LBL film adsorbed on gold with FeTsPc molecules oriented perpendicularly to the substrate plane. Cyclic voltammograms showed reproducible pairs of oxidation-reduction peaks at 1.07 and 0.81 V, respectively, for a 50-bilayer PAH/FeTsPc film at 50 mV/s (vs Ag/Ag+). The peak shape and current dependence on the scan rate suggest that the process is a diffusion controlled charge transport. In the presence of dopamine, the electroactivity of FeTsPc/PAH LBL films vanishes due to a passivation effect. Dopamine activity is not detected either because the interaction between Fe atoms and NH2 groups prevents dopamine molecules from coordinating with the Fe atoms.

MULLER CELLS AND DIABETIC-RETINOPATHY

Muller cells provide nutrition for neural cells. We studied the structure and ultrastructure of Muller cells in the retina of thirty 3-month old Wistar rats; divided equally into 3 groups: normal rats, alloxan diabetic rats and treated alloxan diabetic rats. 1 and 12 months after induction of diabetes. We observed that the Muller cell nuclei under light microscope examination had hexagonal shape and higher density than the other nuclei. Differences between groups could be observed only by electron microscopy. In the diabetic rats, Muller cells presented dispersion of nuclear chromatin and electrondense nuclear granulations, with the presence of increased glycogen, dense bodies and lysosomes in the cytoplasm. The alterations were more frequent in the perivascular region and at 12 months. The treated diabetic rats exhibited some alterations we observed in diabetic rats. but these alterations were less intense. We conclude that, despite the treatment, the diabetic retinopathy continues to evolve.

Morphological and luminescent studies on nanosized Er, Yb-Yttrium oxide up-converter prepared from different precursors

In this paper, we report luminescent and morphological studies with yttrium oxide samples doped with ytterbium and erbium. The samples were prepared by the combustion method and also from different precursors: oxalate, basic carbonate and polymeric resin. All powders were identified Lis being an yttrium oxide with a C-form structure, independent of the employed precursor. From mean crystallite size measurements, it was verified that oxides prepared through the polymeric precursor and combustion methods lead to the smallest crystallite size. Particle shape and size were investigated by SEM and TEM, and showed that both the oxalate precursor and the combustion methods do not provide oxide materials of suitable shape or size, on the other hand. The basic carbonate and polymeric precursors resulted in spherically shaped particles with an average diameter of 90 and 15 run. respectively, Upon 980 run diode laser excitation, green and red emission lines were detected for all samples and were assigned to the H-2(11/2) S-4(3/2) -> I-4(15/2) and (4)Fg(9/2) -> 4I(15/12) transitions, respectively. Such transitions are characteristic for Er3+ and result from energy transfer from Yb3+ energy levels, F-2(7/2) -> F-2(5/2). A relationship between the decrease in the mean crystallite size and the enhancement in red emission was also established as well as the influence of the presence of a high percentage of Yb-3 Both factors promote ET from Yb3+ (F-2(5/2)) to Er3+ (I-4(11/2)). (c) 2004 Elsevier B.V. All rights reserved.

Synthesis, characterization and thermal behaviour of solid 4-methoxybenzoates of heavier trivalent lanthanides

Solid-state Ln-4-MeO-Bz compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration, phase transition, coordination mode, structure, thermal behaviour and thermal decomposition of the isolated compounds. The phase transition observed in the some compounds has been reported for the first time. (C) 2006 Elsevier B.V. All rights reserved.

Effect of the bath pH on the electrodeposition of nanocrystalline Pd-Co alloys and their magnetic properties

The effect of the bath pH on the electrodeposition of nanocrystalline Pd-Co alloys and on their magnetic properties was studied. The pH practically did not affect the alloy composition. Conversely, the pH showed a significant influence on the shape and size of crystallites. Two different crystallites morphology were observed depending on the bath pH. A crystallite size ranging from 18.2 to 30 nm was obtained from X-ray diffractometry (XRD) patterns using the Scherrer's method. Also from the XRD patterns the lattice strain percentage was calculated and correlated with the residual stress, which probably originated during the film electrodeposition on the substrate. Some alloy magnetic properties showed small variations. In contrast, high and unexpected coercivities were obtained reaching a maximum of 1.69 kOe at pH 5.5. The high coercivity values were attributed to the presence of residual stress at the film-substrate interface, which increased as the bath pH and crystallite size decrease, both of them contributing simultaneously to increase in coercivity. (C) 2006 Elsevier B.V. All rights reserved.

Histochemical study of the extensor digitorum longus and soleus muscles in alcoholic rats

The extensor digitorum longus (EDL) and soleus (SOL) muscle fibres from albino rats submitted to experimental chronic alcoholism were evaluated in accordance with their metabolic and morphometric profiles. Twenty-seven male animals aged 4 months and weighing approximately 400 g were used. The animals were divided into three groups: control, isocaloric and alcoholic and sacrifices were carried out after 5, 10 and 15 months. The muscles were dissected, removed, cross-sectioned in a cryostat and submitted to the NADH (nicotinamide adenine dinucleotide) reaction. The SO (slow-twitch-oxidative), FG (fast-twitch-glycolytic) and FOG (fast-twitch-oxidative-glycolytic) muscle fibre types exhibited a polygonal, triangular or rounded shape and did not present noteworthy modifications in either muscles during the study. The cross-sectional areas of the fibres from the studied muscles did not present significant differences during the observations. Fibre area behaved similarly in the alcoholic animals up to the 10th month, i.e. it was decreased, as also observed in the other groups. At 15 months, however, all fibres were increased, with a predominance of FG fibres in the SOL muscle. Changes in fibre population were observed mainly in the SOL muscle of alcoholic animals: SO fibres were initially increased in number but decreased after the 10th month, and the opposite was observed for the population of FG fibres. FOG fibres increased linearly in number throughout the experiment. The statistical analysis showed nevertheless that the fibre population and cross-sectional area changes were not significant. In the alcoholic animals quantitative variations of muscle fibres were more evident in the SOL muscle, suggesting that the SOL muscle is more sensitive to the toxic action of ethanol. The results concerning the increased fibre diameter in alcoholic animals would be associated with muscle oedema induced directly or indirectly by the ethanol.