Fluoride Release of Fresh and Aged Glass Ionomer Cements after Recharging with High-Fluoride Dentifrice

Objective. This study aimed to evaluate F release from GICs before and after recharging with F-dentifrices and after aging process. Methods. Fifteen specimens of GICs (conventional, resin modified, and high viscosity) and composite resin were stored individually in a polystyrene tube containing 2 ml of deionized water (DW), with water replacement every 24 hours. After 15 days, the specimens were treated with a dentifrice suspension (1 : 3 by volume) containing 0 μg F/g (n = 5), 1,100 μg F/g (n = 5), or 5,000 μg F/g (n = 5). After 3 min, the specimens were rinsed and replaced in new tubes with 2 ml of DW. This procedure was performed 2x/day for 2 days. The readings were taken on days 1, 5, 10, and 15 before and after the treatments. A second experiment was performed, using the same specimens of the previous study that were submitted to an aging process (specimens were kept in 2 ml of DW, remaining at 37°C for 36 weeks). Readings using specific electrode for F detection were taken on days 1, 5, 10, and 15 after treatment of the samples as described above. Data were analyzed by ANOVA and Tukey’s test with α fixed at 5%. Results. It was observed that the highest release of F for all the GICs occurred on the first day after the treatments, especially when using a high-fluoride dentifrice, with decreasing release over time. Also, although aged GICs still recharge with F treatments, the amount of F released was lower than fresh materials. Conclusion. GICs present a high F recharge and release capacity, especially in the first 24 hours and after the treatment with a high-fluoride dentifrice, even after material aging.

Total Temperature Measurement of Gas at Microtube Outlet

This paper describes experimental results on the total temperature measurement of gas at the microtube exit. In order to measure the total temperature at the microtube outlet, two total temperature measuring devices with different structures were fabricated. One is six plastic baffle plates embedded inside with a thermally insulated exterior foamed polystyrene tube. The other is two glass fiber thimbles embedded inside it. The gas velocity was reduced by the plastic plates and the glass fiber thimbles, and the kinetic energy was converted into thermal energy. The fundamental premise of the total temperature measurement is the Joule Thomson effect present in real gases, which for a positive of the Joule Thomson coefficient involves the decrease in temperature when the gas experiences isenthalpic expansion. A PEEK microtube whose nominal inner diameter and outer diameter were 500 μmm and 1.6 mm, was used for assessing exact measurement of total temperature in the temperature measuring tube, since the thermal conductivity of the PEEK tube is very low. The measured total temperatures were compared with those obtained theoretically with the Joule Thomson coefficient and given thermodynamics properties.

Total Temperature Measurement of Micro Gas Jet

Total temperature of the nitrogen micro-gas jet from a micro-tube outlet was measured for various flow rates. A thermally insulated tube of foamed polystyrene with six baffles where the gas velocity reduces and the kinetic energy is converted into the thermal energy, was attached to the outlet of the micro-tube. The gas temperature was measured by thermocouples at locations of baffles. The inner diameter of a micro-tube used is 519μm and the tube length is 56.3 mm. The inner diameter of the polystyrene tube is 22 mm. The baffles are equally spaced and the interval of the baffles tested are 5, 10, 20 and 30 mm to investigate the effect of the interval of the baffle on the reduction of the gas velocity. Measured total temperatures are compared with the theoretically obtained total temperatures for a perfect adiabatic micro-tube. The measured total temperatures are slightly higher than the theoretically obtained total temperatures.

Capacitive Tilt Sensor Using Metallic Ball

A new capacitive type of tilt sensor using metallic ball is proposed primarily to get over the contact problem in measurement of tilt angle. Its structure and fabrication process are simpler than other previous sensors. Capacitive sensing type has many advantages such as simplicity, non-contact measurement of angle, long-throw linear displacement, and sub-micron plate spacing comparing to other types. The dimension of this prototype sensor is 20mm × 20mm and the diameter of the polystyrene tube is 5mm and the thickness of the tube is 0.15mm. The test result shows the linear relationship between tilt angles and capacitances.

Laser-excited immunofluorometric assay of prolactin, with use of antibodies coupled to lanthanide-labeled diethylenetriaminepentaacetic acid.

We describe an immunofluorometric assay for prolactin based on lanthanide labeling of a monoclonal antibody and measuring time-resolved fluorescence. In this "sandwich"-type assay, the label (Eu3+) was bound to the second antibody by means of a simple, rapid method involving the anhydride of diethylenetriaminepentaacetic acid. To measure the photoluminescence of europium (or other lanthanides), we have developed a time-resolved fluorometer with a nitrogen laser as the pulsed excitation source. During the assay, the solid-phase antibody immobilized inside a polystyrene tube is incubated with the plasma sample and the second antibody in a one-step procedure. Results for 67 human plasmas correlated well (r = 0.98) with those by an immunoradiometric method.

Development and evaluation of a new solid-phase direct immunoenzyme assay for prostatic acid phosphatase.

In this assay we used polystyrene-tube-attached rabbit antibodies against prostatic acid phosphatase (PAP) that had been purified to homogeneity from human prostate. The amount of immunoreactive acid phosphatase was determined directly by its enzymic activity in the solid-phase-bound immune complex. The detection limit was 0.05 U/L (0.13 microgram/L), the CVs between 4.3 and 10.8%. Investigating the organ specificity of PAP, we found that some cross-reacting acid phosphatase activity could be so measured in human kidney, leukocytes, and platelets, all of which probably contribute to the circulating "prostatic" acid phosphatase that normally is present in serum. Diurnal and day-to-day variations in serum PAP activity were as much as 100% in healthy subjects. Individuals without prostatic diseases (n = 92) had values for serum PAP activity up to 0.36 U/L (0.94 microgram/L), in an age-independent distribution; patients with benign prostatic hyperplasia (n = 62) showed values up to 0.48 U/L (1.25 micrograms/L). With PAP activity of 0.38 U/L or 1.0 microgram/L (90th percentile of the prostatic group) as the upper limit of "normality," overall sensitivity (stages A-D) for detection of prostatic cancer in 33 essentially untreated patients was 65%. Examples for the followup of therapy of prostatic cancer by measurement of serum PAP with this assay are described.

Polystyrene tube immunoradiometric assay for human alpha1-fetoprotein, and its use for mass screening.

We describe a two-site immunoradiometric assay for human alpha1-fetoprotein, with use of antibody-coated polystyrene tubes as solid phase. The sensitivity, precision, and simplicity of this system make it eminently suitable for mass-screening purposes. We currently use it for neonatal detection of hereditary tyrosinemia in the Province of Quebec; measurements are made on blood spotted and dried on paper. This system could be well suited for other mass surveys, such as prenatal screenings for fetal abnormalities.