OPTICALLY PUMPED (CD3OH)-C-13 - FAR-INFRARED LASER LINES AND ASSIGNMENT

Fourier transform and IR optoacoustic absorption data of (CD3OH)-C-13 were used to search for new FIR laser lines. We have used a waveguide CO2 laser of 300 MHz tunability as the optical pumping source. We report the observation and characterization of 13 new lines. Three of these lines are associated with absorbing transitions appertaining to the weak (CD3)-C-13 asymmetric bending mode.

Assignment and frequency measurement of rotational transitions of (CD3OH)-C-13 by intracavity laser Stark spectroscopy

We present the results of an intracavity Stark spectroscopy experiment on the fundamental state of (CD3OH)-C-13. We use an optically pumped hybrid waveguide FIR laser, CH2F2 as active molecule, and (CD3OH)-C-13 as absorbent molecule. No Brewster window is needed to separate the lasing gas from the absorbing deuterated methanol. An absorption line is assigned as E(l) symmetry (n, K, J): (1,4,18) --> (1,5,18) and its frequency is measured as 63.08631 cm(-1) with a precision of a few parts in 10(7); two more absorptions are reported and a tentative assignment for one of them.

Investigation of (CH3OH)-C-13 methanol: new laser lines and assignments

We have reinvestigated (CH3OH)-C-13 as a source of far-infrared (FIR) laser emission using a CO2 laser as a pumping source. Thirty new FIR laser lines in the range 36.5 mum to 202.6 mum were observed and characterized. Five of them have wavelengths between 36.5 and 75 mum and have sufficient intensity to be used in LMR spectroscopy. Using Fourier-transform spectroscopic data in the infrared (IR) and FIR regions we have determined the assignment for 10 FIR laser transitions and predict nine frequencies for laser lines which have yet to be observed.

Low power laser radiation at 685 nm stimulates stem-cell proliferation rate in Dugesia tigrina during regeneration

Today's scientific interest in tissue engineering for organ transplantations and regeneration from stem cells, allied with recent observations on biostimulation of tissues and cells by laser radiation, stands as a strong motivation for the present work, in which we examine the effects of the low power laser radiation onto planarians under regenerative process. To investigate those effects, a number of 60 amputated worms were divided in three study groups: a control group and two other groups submitted to daily 1 and 3 min long laser treatment sections at similar to 910 W/m(2) power density. A 685 nm diode laser with 35 mW optical power was used. Samples were sent to histological analysis at the 4th, the 7th and the 15th (lays after amputation. A remarkable increase in stem cells counts for the fourth day of regeneration was observed when the regenerating worms was stimulated by the laser radiation. Our findings encourage further research works on the influence of optical radiation onto stem cells and tissue regeneration. (c) 2005 Elsevier B.V. All rights reserved.

Pulpal temperature increases with Er : YAG laser and high-speed handpieces

Statement of problem. During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis.Purpose. The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser.Material and methods. Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark oil the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degreesC). Analysis was performed on the following groups (n = 10): Group 1, high-speed handpiece without water cooling, Group 11, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 mum at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha = .05).Results. The average temperature rises were: 11.64degreesC (+/-4.35) for Group 1, 0.96degreesC (+/-0.71) for Group 11, and 2.69degreesC (+/-1.12) for Group III. There were no statistical differences between Groups 11 and III, both 11 and III differed from Group I significantly (P = .000 and P = .002, respectively).Conclusion. The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.

Study of microleakage at class V cavities prepared by Er : YAG laser using rewetting surface treatment

Objective: This study was conducted to analyze microleakage in Class V cavity preparation, using rewetting (or not) just after burr or Er:YAG laser preparation of enamel and dentin walls in permanent teeth. Background Data: Several studies reported microleakage around composite restorations when cavity preparation was done or treated by Er:YAG laser. As the hybridized laser is removed when this laser is used to cut dental hard tissue, there is a need for new materials or techniques to minimize gaps and microleakage. Results: Primer solution showed significant effect in enamel and dentin, at the level of 5%, when Er:YAG laser was used as a cutting tool. Using primer solution after phosphoric acid in preparations with the laser, microleakage was similar in degree to when cavities were prepared with the burr. Conclusion: Re-wetting surface just after Er:YAG irradiation and chemical treatment with phosphoric acid using HEMA aqueous solution seems to improve the quality of bioattachment between the adhesive system and enamel/dentin, showing similarities between restoration behaviors independently of the cutting tool, whether burr or laser.

The applicability of hematoxylin-eosin staining plus fluorescence or confocal laser scanning microscopy to the study of elastic fibers in cartilages

This study focuses on the use of hemotoxylin-eosin staining plus fluorescence microscopy for the investigation of elastic fibers in some elastic cartilages. We have observed that elastic fibers are consistently imaged by the proposed procedure and the resolution attained is similar to that obtained with the classical Weigert's fuchsin-resorcin. The results also demonstrate that elastin autofluorescence gives little or no contribution to the final fluorescence and that the use of the confocal laser scanning microscope adds to the resolution, permits the use of thicker sections and reveals of minute structural features. We conclude that this is a relevant tool in elastin research.

Validity and reproducibility of a laser fluorescence system for detecting the activity of white-spot lesions on free smooth surfaces in vivo

The aim of the study was to determine the reproducibility and validity of DIAGNOdent in detecting active and arrested caries lesions on free smooth surfaces. Volunteers were selected from state schools of Piracicaba, São Paulo, Brazil. Overall, 220 lesions were clinically examined. Two specially trained ('calibrated') examiners performed both clinical and laser evaluations independently, and after a 1-week interval, the examinations were repeated, the intra-examiner agreement for the laser evaluation was substantial (kappa(ex1) = 0.79, kappa(ex2) = 0.71). There was almost perfect agreement between the two examiners for the clinical examination (kappa(ex1) = 0.95, kappa(ex2) = 0.85). The inter-examiner agreement showed substantial reproducibility (kappa = 0.77) for the laser examination and almost perfect agreement (kappa = 0.85) for the clinical evaluation. The validation criterion was the clinical examination of white spots, recorded as active or arrested. The sensitivity was 0.72 and the specificity was 0.73, which indicates that the DIAGNOdent was a good auxiliary method for detecting incipient caries lesions on free smooth surfaces. The utilization of both methods can improve the efficacy of caries diagnosis. Copyright (C) 2002 S. Karger AG, Basel.