Comparison between gutta-percha and Resilon removal using two different techniques in endodontic retreatment

This study compared the remaining filling material and working time when removing gutta-percha/AH 26 and Resilon/Epiphany from root filled extracted teeth. The root fillings were removed using chloroform and two different rotary systems (K3 and Liberator files). The amount of residual filling material on the canal walls was imaged and measured using image analyzer software. The group filled with Resilon/Epiphany and retreated with K3 files demonstrated the least residual filling material on the walls (p < 0.05). There was no statistically significant difference between the guttapercha/AH26 and Resilon/Epiphany groups when the Liberator files were used (p > 0.05). In the groups filled with Resilon/Epiphany, the filling was removed faster than groups filled with gutta-percha/AH 26 (p < 0.05). K3 rotary system was faster than Liberator to remove both gutta-percha and Resilon (p < 0.05). Resilon/ Epiphany was effectively removed with K3 or Liberator rotary files.

Interstitial oxygen mobility in superconducting samples of Bi2Sr2CaCu2O8+y

Since high-temperature superconductors were discovered, several studies have been made on their physical properties, attempting to associate them to the origin of superconductivity. Obviously, the oxygen atoms interstitially dissolved in the matrix have an important role in superconductivity, since they move easily in the lattice. In addition, they contribute to hole creation in the CuO2 planes. Anelastic spectroscopy ( internal friction) measurements are sensitive tools for the study of defects in solids, in particular for oxygen mobility. In this paper, Bi2Sr2CaCu2O8+y samples with several different amounts of interstitial oxygen were analysed by means of anelastic spectroscopy measurements. The measurements were performed by using a torsion pendulum operating at a frequency of about 40 Hz. Complex relaxation structures were observed and attributed to the shift of the oxygen interstitial atoms in BiO chains.

Comparison of different clean-up procedures for the determination of N-methylcarbamate insecticides in vegetable matrices by high-performance liquid chromatography with UV detection

Several clean-up procedures which included the use of glass chromatography columns (silica gel, alumina, Florisil, silanized Celite-charcoal), Sep-Pak cartridges and standard solutions were compared for the determination of the following N-methylcarbamate (NMC) insecticides: aldicarb, carbaryl, carbofuran, methomyl and propoxur. According to recovery results of the compounds after elution in a glass column, the most efficient systems employed 4.6% deactivated alumina and a silanized Celite-charcoal (4:1) as adsorbents, using dichloromethane-methanol (99:1) and toluene-acetonitrile (75:25) mixtures, respectively, as binary eluents. The recoveries of the compounds studied varied from 84 to 120%. Comparable recoveries (75-100%) for Sep-Pak cartridges in normal phase (NH2, CN) and reversed phase (C-8) were observed. Different temperatures were tested during the concentration step in a rotary evaporator, and we verified a strong influence of this parameter on the stability of some compounds, such as carbofuran and carbaryl. Recovery studies employing the best clean up procedures were performed at the Brazilian agricultural level in potato and carrot samples; Validation methodology of the US Food and Drug Administration was adapted for the N-methylcarbamate analysis. Their recoveries ranged between 79 and 93% with coefficients of variation of 2.3-8%. (C) 1998 Elsevier B.V. B.V.

Internal friction and frequency measurements in molybdenum containing oxygen and nitrogen

We have measured internal friction and frequency as a function of temperature in molybdenum containing oxygen and nitrogen in solid solution. These measurements were performed by a torsion pendulum operating in the temperature range of 300 K to 700 K with oscillation frequency about 1.0 Hz. The results showed the complex relaxation process identifying the stress induced ordering of oxygen and nitrogen atom around the molybdenum atoms of the metallic matrix.

Identification, content, and distribution of type VI collagen in bovine tendons

Tendon composition changes according to differentiation, mechanical load, and aging. In this study, we attempted to identify, localize, and quantify type VI collagen in bovine tendons. Type VI collagen was identified by the electrophoretic behavior of the alpha chains and Western blotting, and by rotary shadowing. Type VI collagen was extracted from powdered tendon with three sequential 24-h extractions with 4 M guanidine-HCl. The amount of type VI collagen was determined by enzyme-linked immunosorbent assay for purely tensional areas and for the compressive fibrocartilage regions of the deep flexor tendon of the digits, for the corresponding fetal and calf tendons, and for the extensor digital tendon. The distal fibrocartilaginous region of the adult tendon was richer in type VI collagen than the tensional area, reaching as much as 3.3 mg/g (0.33%) of the wet weight. Calf tendons showed an accumulation of type VI at the fibrocartilage site. Immunocytochemistry demonstrated that type VI collagen was evenly distributed in the tensional areas of tendons but was highly concentrated around the fibrochondrocytes in the fibrocartilages. The results demonstrate that tendons are variable with regard to the presence and distribution of type VI collagen. The early accumulation of type VI collagen in the region of calf tendon that will become fibrocartilage in the adult suggests that it is a good marker of fibrocartilage differentiation. Furthermore, the distribution of type VI collagen in tendon fibrocartilage indicates that it organizes the pericellular environment and may represent a survival factor for these cells.

Oxygen mobility in SmBa2Cu3O7-delta measured by anelastic spectroscopy

Anelastic spectroscopy has been performed on a sample of superconducting oxide SmBa2Cu3O7-delta (SBCO) using a torsion pendulum operating with frequency around 10 Hz. A thermally activated relaxation peak is observed near 500 K with the activation enthalpy of 1.55 +/- 0.03 eV and the pre-exponential factor of approximately 10(-15) s, which is attributed to the mobility of non-stoichiometric oxygen by jumps in positions O1 and O5 of the lattice. (c) 2006 Elsevier B.V. All rights reserved.

POPULATIONAL STUDY OF CHROMOSOME POLYMORPHISM IN ZONOTRICHIA-CAPENSIS (EMBERIZIDAE, PASSERIFORMES, AVES)

The karyotypes of 328 specimens of Zonotrichia capensis from four regions, three in the state of Parana and one in the state of São Paulo (Brazil), were studied. This species presents a chromosomal polymorphism due to pericentric inversion, involving the 3rd and 5th chromosome pairs. Chromosome 3 exists in the 3st and 3sm conditions and chromosome 5, in 5st and 5m conditions. Mitotic metaphase spreads were obtained from bone-marrow material of colchicine-treated animals.At all collection sites the frequency of chromosome 5m was considerably lower than that of the inverted chromosome 3sm.The present work tried to establish a correlation between the frequencies of the 3rd and 5th chromosome pairs with the climatical and geographical parameters at the collecting regions.Data show that the frequency of chromosome 5m is higher in regions with low temperature and high altitude.

DUPLICATION OF THE SHORT ARM OF THE X-CHROMOSOME IN MOTHER AND DAUGHTER

An 11-year-old girl with short stature, mental retardation, and mild dysmorphic features was found to have an inverted duplication of most of the short arm of the X chromosome [dic inv dup(X)(qter --> p22.3 = p22.3 --> cen:)]. Her mother, who is also short and retarded, carries the same duplication. Fluorescence in situ hybridization with an X chromosome library, and with X centromere-specific alpha satellite and telomere probes, was useful in characterizing the duplication. In most females with structurally abnormal X chromosomes, the abnormal chromosome is inactivated. Although the duplicated X was consistently late replicating in the mother, X chromosome inactivation studies in the proband indicated that in 11 % of her lymphocytes the duplicated X was active.

Cytotoxic effects of cleansing solutions recommended for chemical lavage of pulp exposures

Purpose: To evaluate the in vitro cytotoxic effects of three cleansing solutions used for chemical lavage of pulp exposures. Materials and Methods: the immortalized odontoblast cell line (MDPC-23) was plated (30,000 cells/cm(2)) and incubated for 72 hrs in 24-well dishes. After counting the cell number under inverted light microscopy, 20 mul of the experimental and control solutions were added to 980 mul of fresh culture medium. Then, hydrogen peroxide (3%, H2O2), sodium hypochlorite (6%, NaOCl) or calcium hydroxide-saline solution (5g of Ca(OH)(2) in 10 mi of sterile distilled water) were added to wells for experimental Groups 1, 2 and 3, respectively. The positive and negative control groups received Syntac Sprint bonding agent (SS) and phosphate buffered saline (PBS), respectively. Following incubation for 120 min the cell number was counted again, the cell morphology was evaluated by scanning electron microscopy (SEM) and the cell metabolism was determined by the methyltetrazolium (MTT) assay. The scores obtained from cell counting and MTT assay were analyzed with an ANOVA followed by Fisher's PLSD tests. Results: H2O2 NaOCl solutions, and SS bonding agent were more cytotoxic than Ca(OH)2 or PBS. In the groups with H2O2 Or SS, only a few cells remained attached to the bottom of wells. The difference between these two groups was not statistically significant. H2O2, NaOCl and SS depressed the mitochondrial enzyme response by 97.7%, 97.3%, and 95.0%, respectively. on the other hand, Ca(OH)2 depressed the metabolic activity of cells by only 5%. While H2O2, NaOCl and SS caused extreme changes on the cell morphology, neither Ca(OH)2 nor PBS promoted dramatic changes in the cell morphology.

Using transient and steady state considerations to investigate the mechanism of loss of stability of a dynamical system

This work presents the complete set of features for solutions of a particular non-ideal mechanical system near the fundamental and near to a secondary resonance region. The system comprises a pendulum with a horizontally moving suspension point. Its motion is the result of a non-ideal rotating power source (limited power supply), acting oil the Suspension point through a crank mechanism. Main emphasis is given to the loss of stability, which occurs by a sequence of events, including intermittence and crisis, when the system reaches a chaotic attractor. The system also undergoes a boundary-crisis, which presents a different aspect in the bifurcation diagram due to the non-ideal supposition. (c) 2004 Published by Elsevier B.V.

Influence of interstitial elements on internal friction measurements in Nb and Nb-Zr alloys

Internal friction and frequency measurements as a function of temperature have been carried out in Nb and Nb-Zr policrystalline samples, using a torsion pendulum in the temperature range between 300K and 700K the heating rate was 1K/min and the pressure was kept better than 5x10(-3) mbar. Metals with bce lattice containing solute atoms dissolved interstitially often show anelastic behaviour due to a process know as stress-induced ordering responsible for the appearance of Snoek peaks. In the Nb sample it has been identified two constituent peaks corresponding to the interstitial-matrix interactions (Nb-O and Nb-N), but for the Nb-Zr samples with interstitial solute concentrations very close to those measured for the unalloyed Nb, it was not observed any mechanical relaxation peaks due to the presence of oxygen and nitrogen in solid solution.

High-speed cavity preparation techniques with different water flows

Statement of problem. Cavity and tooth preparations generate heat because the use of rotary cutting instruments on dental tissues creates friction. Dental pulps cannot survive temperature increases greater than 5.5degreesC.Purpose. This study evaluated the efficiency of 3 different water flows for 2 different tooth preparation techniques to determine which are safe for use.Material and methods. Thermocouples were placed in the pulpal chambers of 30 bovine teeth, and 1 of 2 tooth preparation techniques was used: a low-load intermittent tooth preparation technique or a high-load tooth preparation technique without intervals. Water flows of 0, 30, and 45 mL/min were associated with each technique, for a total of 6 different groups. The results were analyzed with a 2-factor analysis of variance (P<.05).Results. Temperature increases with the high-load technique were 16.40&DEG;C without cooling (group 1), 11.68&DEG;C with 30 mL/min air-water spray cooling (group III), and 9.96&DEG;C with 45 mL/min cooling (group V). With the low-load tooth preparation technique, a 9.54&DEG;C increase resulted with no cooling (group II), a 1.56&DEG;C increase with 30 mL/min air-water spray cooling (group TV), and a 0.04&DEG;C decrease with 45 mL/min cooling (group VI). The low-load technique was associated with more ideal temperature changes.Conclusion. The results of this study confirm the necessity of using a low-load technique and water coolants during cavity and tooth preparation procedures.

Anatomy of the oral cavity of hylid larvae from the genera Aplastodiscus, Bokermannohyla, and Hypsiboas (Amphibia, anura): Description and systematic implications

Internal larval oral anatomy was used to explore morphological diversity and its contribution to the systematics of the genera Aplastodiscus, Bokerinannohyla, and Hypsiboas, belonging to the tribe Cophomantini. Internal oral morphology was examined for tadpoles of 12 species. All species have a large pair of infralabial papillae on the buccal floor and other papillae on the prelingual region. In Aplastodiscus and Bokerinannohyla, the large infralabial papillae have digitiform secondary projections. The number and arrangement of the buccal floor papillae varies among species, but they are more numerous in Aplastodiscus and Bokerinannohyla. The arrangement of the postnarial papillae is variable, but in Aplastodiscus and Bokerinannohyla, they show a definite, inverted V-shape pattern. The lateral ridge papillae are more complex in larvae of Bokertnannohyla with long digitiform secondary projections. Tadpoles of only Aplastodiscus albofrenatus, Aplastodiscus eugenioi, and Bokerinannohyla luctuosa have papillae on the buccal roof arena and larvae of all species have lateral roof papillae except Hypsiboas albomarginatus and Hypsiboas cinerascens. Larvae of Aplastodiscus, Bokermannohyla, and Hypsiboas presumably share the presence of vacuities anterior to the internal nares; although this character state is clearly synapomorphic within hylids, it is still uncertain whether it is exclusive of these three genera or whether it is present in the other genera of the tribe Cophomantini (Hyloscirtus and Myersiohyla). The inclusion of internal oral anatomy characters, such as the narial vacuities, in systematic studies is certainly valuable because it will provide additional information toward the understanding of phylogenetic relationships.

Anelastic relaxation processes due oxygen in Nb-3.1 at.% Ti alloys

In the last 50 years several studies have been made to understand the relaxation mechanisms of the heavy interstitial atoms present in transition metals and their alloys. Internal friction measurements have been carried out in a Nb-Ti alloy containing 3.1 at.% of Ti produced by the Materials Department of Chemical Engineering Faculty of Lorena (Brazil), with several quantities of oxygen in solid solution using a torsion pendulum. These measurements have been performed by a torsion pendulum in the temperature range from 300 to 700 K with an oscillation frequency between 0.5 and 10 Hz. The experimental results show complex internal friction spectra that have been resolved, into a series of Debye peaks corresponding to different interactions. For each relaxation process it was possible to obtain the height and temperature of the peak, the activation energy and the relaxation time of the process. (C) 2003 Elsevier B.V. All rights reserved.

Electrical percolation during gelation of lithium doped siloxane-poly(oxyethylene) hybrids

Gelation mechanisms of lithium-doped Siloxane-Poly(oxyethylene) (PEO) hybrids containing polymer of two different molecular weight (500 and 1900 g/mol) were investigated through the evolution of the electrical properties during the solgel transition. The results of electrical measurements, performed by in-situ complex impedance spectroscopy, were correlated with the coordination and the dynamical properties of the lithium ions during the process as shown by Li-7 NMR measurements. For both hybrids sols, a decrease of the conductivity is observed at the initial gelation stage, due to the existence of an inverted percolation process consisting of the progressive separation of solvent molecules containing conducting species in isolated islands during the solid network formation. An increase of conductivity occurs at more advanced stages of gelation and aging, attributed to the increasing connectivity between PEO chains promoted by the formation of crosslinks of siloxane particles at their extremities, favoring hopping motions of lithium ions along the chains.