THE EFFECT OF LACTIC ACID AND ARTIFICIAL SALIVA SOLUTION IMMERSION TO THE RELEASE OF CALCIUM IONS ON BIOACTIVE RESIN

Background: Bioactive resin can release calcium ions when contact with solution media, even in acid condition. In the oral cavity, pH may change into acid condition due to the metabolic results of Streptococcus mutans. The bacteria metabolize carbohydrates into organic acids, one of which is lactic acid. Purpose: Analyze the effect of lactic acid solution and artificial saliva on the number of the release of calcium ions of bioactive resin. Methods: Forty-two specimens (diameter 15 mm x thickness 1 mm; n= 7/group fabricated with Activa™ Bioactive Restorative (Pulpdent). The specimens that meet the criteria were divided into 6 groups. The specimen was immersed for 1 and 7 days in the incubator at 37oC. The number of calcium ion release is measured using titration method. Results: Two Way Anova test and Post Hoc Bonferonni test showed there were significant differences among all group for lactic acid 1 day (4.040 ± 0.360) µg, artificial saliva 1 day (0.640 ± 0.338) µg, distilled water 1 day (1.040 ± 0.504) µg, lactic acid 7 days (5.400 ± 0.312), artificial saliva 7 days (1.640 ± 0.215) µg, distilled water 7 days (3.520± 0.356 µg). Conclusion: There was an influence of lactic acid and artificial saliva on the number of calcium ion releases of bioactive resin. Immersion of bioactive resin in the lactic acid solution increase the calcium ion releases and artificial saliva decrease the calcium ion release compared to distilled water. Keywords: artificial saliva, bioactive resin, calcium ion release, lactic acid

The study and analysis of the prognosis criteria for a safe local anesthesia in patients with arterial hypertension

Relevance. To develop the algorithm for a safe and effective local anesthesia in dental outpatients with arterial hypertension.Materials and methods. The study was conducted in the laboratory of functional and clinical studies of Moscow State University of Medicine and Dentistry. Electric pulp testing (µA) was performed and pulp microcirculation (PU) was assessed in the intact teeth of patients with hypertension before and 5, 10, 15, 30 and 60 minutes after the administration of local anesthesia. We used 4% articaine solutions without a vasoconstrictor and with its minimal concentration 1:200 000 and 1:400 000, and 3% mepivacaine solution. The safety of the administered local anesthetic was assessed by the continuous hemodynamic monitoring.Results. 4% articaine solution without epinephrine had a shallow anesthetic effect in the maxilla and anterior mandible. 1:400 000 and 1:200 000 vasoconstrictor concentrations in 4% articaine solution increase the depth and duration of the anesthesia from 20 to 30 minutes respectively. Changes in the pulp sensibility but not in blood microcirculation were demonstrated by the functional parameters of the intact dental pulp in patients with hypertension after the administration of 3% mepivacaine solution at the mandibular foramen. The continuous hemodynamic monitoring data showed no changes in arterial blood pressure, heart rate, oxygen saturation on administration of either of the studied local anesthetic solutions or techniques.Conclusion. The analysis of the prognosis criteria for a safe local anesthesia allowed us to ground the choice of anesthetic in dental outpatients with arterial hypertension.

Inverted energy gap law for the nonradiative decay in fluorescent floppy molecules: larger fluorescence quantum yields for smaller energy gaps

The non-radiative decay of substituted dicyano-distyrylbenzenes in solution increase with the Franck–Condon energy, being opposite to the conventional energy gap law.

Effect of surface active agent on bubble-electrospun polyacrylonitrile nanofibers

Sodium dodecyl benzene sulfonates were used as a surfactant to obtain polyacrylonitrile nanofibers by a modified bubble-electrospinning using a copper cone-shaped air nozzle. The properties of the electrospun solutions were investigated using viscosity meter, conductivity meter and rheometer, and the effects of sodium dodecyl benzene sulfonates concentration on the morphology, mechanical property and production of polyacrylonitrile nanofibers were studied. The results showed the addition of sodium dodecyl benzene sulfonates could effectively decrease the viscosity of the solution, increase the electric conductivity of the solution, and promote the generation of bubbles, which resulted in enhancing tensile strength and decreasing the production of nanofibers.

XEOL spectroscopy of lanthanides in aqueous solution

As part of an ongoing study of the electronic interactions between solute and solvent molecules, a method for X-ray excited optical luminescence (XEOL) analysis of aqueous solutions was developed at the double-crystal monochromator beamline (DCM) of the Canadian Synchrotron Radiation Facility (CSRF). It was tested using a series of solutions containing lanthanide ions. The samples were contained in a sample holder for liquids with a 3 μm Mylar window separating them from the vacuum (≤3 × 10−6 torr, 1 torr = 133.3224 Pa) in the solid state absorption chamber of the DCM beamline. Terbium, samarium, and dysprosium have 4 intense and narrow luminescence peaks between 450 and 700 nm, well separated from the luminescence peak of the Mylar window between 300 and 425 nm. The intensity of the rare earth (RE3+) luminescence peaks was lower for the solutions than for solid RECl3·6H2O. In part, this was caused by the lower RE3+ concentration in the solutions than in the solid. In addition, the solvent (water) acts as a quencher. The disorder and the molecular motion in the solution increase the availability of nonradiative de-excitation pathways. A high concentration of SO42− in the solution enhanced the luminescence intensity, probably by inhibiting some nonradiative de-excitation pathways. This study has shown that it is in principle possible to investigate the luminescence of aqueous solutions with XEOL spectroscopy. Furthermore, it is possible to use this technique as a quantitative analytical tool for concentrated luminescent solutions and to study the shielding effects of anions in the solution that increase the luminescence intensity.

Effect of Blend Ratio on Morphology and Swelling Properties of PVA/Chitosan Nanofibers

PVA/chitosan nanofibers have been prepared by electrospinning method. A novel nanofibers mat was prepared in a various blend ratio of PVA to chitosan. The structure of PVA/chitosan nanofibers was examined by FTIR and SEM. The results showed that PVA/chitosan nanofibers were successfully formed. The result of FTIR indicates that PVA and chitosan exist in PVA/chitosan Nanofibers. SEM observation showed that the fiber has several hundred nanometers with a smooth surface. It also observed that fibers diameters decreased by increase percentage of chitosan, this occurs because of the conductivity of electrospun solution increase and the viscosity decrease. Reduction of fiber diameter followed by a decrease in pore size, this is a very important property of a membrane having a small pore size with high porosity. PVA/chitosan nanofibers have pH sensitive of swelling properties and better-swelling properties in acid conditions.

Solving of Partial Differential Equations by Numerical Manifold Method with Partially Overlapping Covers

Governing equations of 1D high-order numerical manifold method with partially overlapping covers have been deduced by the general method of weighted residuals. By using the proposed method, a highly oscillatory differential equation has been solved. In addition, a posteriori error method is adopted for evaluating the accuracy of the algorithm. Meanwhile, several factors affect the accuracy are also discussed. The results indicate that accuracy of solution increase with the decrease of overlapping ratio and the order of cover function. When higher order cover function such as 6th is used, higher accuracy will matched even for second derivative of unknowns. This paper attempts to enrich the theory and practical field of the NMM.

Morphology and Microstructure of Aggregates and Gelation Behaviour of Poly(3-hexylthiophene) in Xylene Solution

In this work, we investigate the morphology and microstructure of the aggregates, and the gelation behaviour of Poly(3-hexylthiophene) (P3HT) conjugated polymer in xylene solution as functions of P3HT concentration and aging time by the means of ageing time test, wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), UV-visible absorption (UV-vis) and photoluminescence (PL) spectra. The result reveals that the gelation time of P3HT/xylene solution decreases markedly with increasing P3HT concentration. The photophysical properties of the P3HT aggregates in P3HT/xylene solution increase as P3HT concentration and ageing time are raised. It indicates that the well soluble P3HT polymer chains in xylene solution present microphase separation and self-assemble into stiff sheetlike structure, which associates by rodlike nanowhiskers of P3HT polymers during aging. Upon prolonged aging, the sheetlike structure of P3HT aggregates to from the three-dimension network that improves the electronic particle mobility in the organic solar cell.