Conversion Degree of Indirect Resin Composites and Effect of Thermocycling on Their Physical Properties

Purpose: This study evaluated the degree of conversion (DC) of four indirect resin composites (IRCs) with various compositions processed in different polymerization units and investigated the effect of thermal aging on the flexural strength and Vicker's microhardness.Materials and Methods: Specimens were prepared from four IRC materials, namely Gr 1: Resilab (Wilcos); Gr2: Sinfony (3M ESPE); Gr3: VITA VMLC (VITA Zahnfabrik); Gr4: VITA Zeta (VITA Zahnfabrik) using special molds for flexural strength test (N = 80, n = 10 per group) (25 x 2 x 2 mm(3), ISO 4049), for Vicker's microhardness test (N = 80, n = 10 per group) (5 x 4 mm(2)) and for DC (N = 10) using FT-Raman Spectroscopy. For both flexural strength and microhardness tests, half of the specimens were randomly stored in distilled water at 37 degrees C for 24 hours (Groups 1 to 4), and the other half (Groups 5 to 8) were subjected to thermocycling (5000 cycles, 5 to 55 +/- 1 degrees C, dwell time: 30 seconds). Flexural strength was measured in a universal testing machine (crosshead speed: 0.8 mm/min). Microhardness test was performed at 50 g. The data were analyzed using one-way and two-way ANOVA and Tukey's test (alpha = 0.05). The correlation between flexural strength and microhardness was evaluated with Pearson's correlation test (alpha = 0.05).Results: A significant effect for the type of IRC and thermocycling was found (p = 0.001, p = 0.001) on the flexural strength results, but thermocycling did not significantly affect the microhardness results (p = 0.078). The interaction factors were significant for both flexural strength and microhardness parameters (p = 0.001 and 0.002, respectively). Thermocycling decreased the flexural strength of the three IRCs tested significantly (p < 0.05), except for VITA Zeta (106.3 +/- 9.1 to 97.2 +/- 14 MPa) (p > 0.05) when compared with nonthermocycled groups. Microhardness results of only Sinfony were significantly affected by thermocycling (25.1 +/- 2.1 to 31 +/- 3.3 Kg/mm(2)). DC values ranged between 63% and 81%, and were not significantly different between the IRCs (p > 0.05). While a positive correlation was found between flexural strength and microhardness without (r = 0.309) and with thermocycling (r = 0.100) for VITA VMLC, negative correlations were found for Resilab under the same conditions (r = -0.190 and -0.305, respectively) (Pearson's correlation coefficient).Conclusion: Although all four IRCs presented nonsignificant DC values, flexural strength and microhardness values varied between materials with and without thermocycling.

Indirect constraints on the triple gauge boson couplings from Z -> b(b)over-bar partial width: An update

We update the indirect bounds on anomalous triple gauge couplings coming from the non-universal one-loop contributions to the Z --> width. These bounds, which are independent of the Higgs boson mass, are in agreement with the standard model predictions for the gauge boson self-couplings since the present value of R-b agrees fairly well with the theoretical estimates. Moreover, these indirect constraints on Delta g(1)(Z) and g(5)(Z) are most stringent than the present direct bounds on these quantities, while the indirect limit on lambda(Z) is weaker than the available experimental data.

Cobalt phthalocyanine as a biomimetic catalyst in the amperometric quantification of dipyrone using FIA

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

High-Performance Liquid Chromatographic Quantification of Flavonoids in Eriocaulaceae Species and Their Antimicrobial Activity

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

The role of matrix effects on the quantification of abscisic acid and its metabolites in the leaves of Bauhinia variegata L. using liquid chromatography combined with tandem mass spectrometry

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

Indirect method for quantifying the content of photosynthetic pigments in genotypes of dwarf elephant grass

O objetivo deste ensaio foi determinar equações que indiretamente associem os valores obtidos no medidor de clorofila SPAD-502 aos teores de clorofila e carotenóides de genótipos de capim-elefante anão. Folhas de genótipos de capim-elefante anão foram utilizadas e, depois de coletadas, foram transportadas em caixas de isopor, protegidas da luz, até o laboratório de Fisiologia Vegetal da UENF. Posteriormente, os discos foliares de área conhecida foram extraídos. Com o auxílio do medidor portátil de clorofila (MPC) SPAD-502, foi obtida a média de 5 leituras/disco foliar e utilizaram-se 6 discos para cada intervalo, distribuídos de acordo com a seguinte escala de valores do MPC: 0-10; 10-20; 20-30; 30-40; 40-50; 50-60. O medidor de clorofila SPAD-502 possibilitou uma rápida e eficaz estimativa do conteúdo de clorofila total, clorofila-a e clorofila-b em genótipos de capim-elefante anão.

Ultrastructural analysis of in vitro direct and indirect organogenesis

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

Techniques of digital image analysis for histological quantification of melanin

A análise morfométrica da melanina tecidual pode subsidiar quantitativamente a pesquisa em discromias. Os autores demonstram três técnicas de análise de imagem digital que permitem a identificação dos pixels equivalentes à melanina na epiderme pela coloração de Fontana-Masson, possibilitando o cálculo da sua porcentagem nas diferentes camadas da epiderme, e discutem os principais elementos relacionados à análise e a necessidade de rigorosa padronização do processo.

Indirect cathodic-stripping voltammetric determination of ceftazidime as a mercury salt

At accumulation potentials close to +0.1 V at a hanging mercury drop electrode, ceftazidime is accumulated at pH 9.5, probably in a hydrolysed or otherwise chemically altered form, in an anodic process to give an adsorbed mercury salt. The accumulation of this mercury salt allows the indirect cathodic-stripping voltammetric determination of ceftazidime using the reduction peak of the mercury salt at -0.70 V. The high sensitivity of the method coupled with high sample dilution allows ceftazidime to be determined in milk samples at the 28 mu g ml(-1) level without prior separation. In order to determine lower levels of ceftazidime in milk (ca. 10 ng ml(-1)) a separation process would be required. (C) 1998 Elsevier B.V. B.V. All rights reserved.

QUANTIFICATION OF IMMUNOGLOBULIN-A IN CHORIOAMNIOTIC MEMBRANE OF PATIENTS WITH PREMATURE RUPTURE OF MEMBRANES

Objective: the proposal was to study the presence of immunoglobulin A (IgA) in the chorioamniotic membrane of healthy postpartum women with premature rupture of the chorioamniotic membrane (FROM). Method: A single radial immunodiffusion technique was used to quantify the IgA in the chorioamniotic membrane tissues. Results: the level of IgA was approximately 10 times higher in patients whose membranes had been ruptured for > 10 h (24.58 mg/dl). These results were compared with those of a previously published study where the mean of amount of IgA was 2.52 mg/dl in membranes of patients with rupture < 10 h. Our results show that IgA began to rise after 10-15 h following rupture. Conclusion: Although more studies need to be performed our data indicate that the increasing IgA in our patients after 10 h of latency probably represents the beginning of an ascending colonization of bacteria which could be the source of future infection.

Immunodiagnosis of swine cysticercosis by indirect ELISA employing a heterologous antigen from Taenia crassiceps metacestode

C. Larralde et al. (1990, Arch. Pathol. Lab. Med., 114:926-928) demonstrated that heterologous antigen from the laboratory-adapted murine Taenia crassiceps metacestode may substitute those from Taenia solium in the immunodiagnosis of human cysticercosis by the indirect enzyme-linked immunosorbent assay (IE). ?This antigen is easily obtained at a laboratory level and solves the problem of T. solium cysticerci collection from naturally or experimentally infected swine. In this study an IE employing a heterologous antigen from the T. crassiceps metacestode was evaluated for the immunodiagnosis of swine cysticercosis. Sera from 300 swine free of T. solium cysticerci by post-mortem examination were employed to determine two IE cut- off values: 1) Mean ELISA values + 2 standard deviations (2 sigma cut-off) and 2) - Mean ELISA values + 3 standard deviations (3 sigma cut-off). The specificity of IE was 97% with the 2 sigma cut-off and 100% with the 3 sigma cut-off. When applied to ten sera from swine infected by cysticerci of T. solium by post-mortem examination, the sensitivity of IE was 100% independent of the cut off.

Indirect polarographic and cathodic stripping voltammetric determination of cefaclor as an alkaline degradation product

Cefaclor is not reducible at a mercury electrode, but it can be determined polarographically and by cathodic stripping voltammetry as its initial alkaline degradation product which is obtained in high yield by hydrolysis of cefaclor in Britton-Robinson (B-R) buffer pH 10 at 50 degrees C for 30 min (reduction peak at pH 10, -0.70 V). Differential pulse polarographic calibration graphs are linear up to at least 1 x 10(-4) mol l(-1). Recoveries of 93% of the cefaclor (n = 3) were obtained from urine spiked with 38.6 mu g ml(-1) using this polarographic method with 1 ml urine made up to 10 ml with pH 10 buffer. Using cathodic stripping voltammetry and accumulating at a hanging mercury drop electrode at -0.2 V for 30 s, linear calibration graphs were obtained from 0.35 to 40 mu g ml(-1) cefaclor in B-R buffer pH 10. A relative standard deviation of 4.2% (eta = 5) was obtained, and the limit of detection was calculated to be 2.9 ng ml(-1). Direct determination of cefaclor in human urine (1 ml of urine was made up to 10 ml with pH 10 buffer) spiked to 0.39 mu g ml(-1) was made (recovery 98.6%). (C) 1999 Elsevier B.V. B.V. All rights reserved.