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Laser Techniques (laser + techniques)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Medical Sciences	50%

Selected Abstracts

Review of Photorejuvenation: Devices, Cosmeceuticals, or Both?

DERMATOLOGIC SURGERY, Issue 2005
Cameron K. Rokhsar MD
Background:. Both the public and the medical profession have placed a lot of attention on reversal of signs of aging and photodamage, resulting in numerous cosmeceutical products and nonablative laser techniques designed to achieve these results. Objective:. The purpose of this report is to briefly review both the cosmeceutical products and nonablative laser techniques that appear to be most promising based on published studies. After this review, recommendations for potential enhancement of benefits by combining cosmeceuticals and laser treatments will be explored. Results. Pulsed dye lasers targeting microvessels, intense pulsed light targeting both melanin and microvessels, and midinfrared lasers targeting dermal water and collagen all appear to have some ability to improve skin texture, color, and wrinkling. Retinoids, vitamin C, alpha-hydroxy acids, and topical growth factors may also stimulate repair mechanisms that result in similar improvements in photodamaged skin. Conclusion:. Although supported only by theoretic considerations and anecdotal reports, it seems logical that the concurrent use of appropriate cosmeceuticals with nonablative laser photorejuvenation should result in enhanced benefits. [source]

The smear layer in endodontics , a review

INTERNATIONAL ENDODONTIC JOURNAL, Issue 1 2010
D. R. Violich
Abstract Root canal instrumentation produces a layer of organic and inorganic material called the smear layer that may also contain bacteria and their by-products. It can prevent the penetration of intracanal medicaments into dentinal tubules and influence the adaptation of filling materials to canal walls. This article provides an overview of the smear layer, focusing on its relevance to endodontics. The PubMed database was used initially; the reference list for smear layer featured 1277 articles, and for both smear layer dentine and smear layer root canal revealed 1455 publications. Smear layer endodontics disclosed 408 papers. A forward search was undertaken on selected articles and using some author names. Potentially relevant material was also sought in contemporary endodontic texts, whilst older books revealed historic information and primary research not found electronically, such that this paper does not represent a ,classical' review. Data obtained suggests that smear layer removal should enhance canal disinfection. Current methods of smear removal include chemical, ultrasonic and laser techniques , none of which are totally effective throughout the length of all canals or are universally accepted. If smear is to be removed, the method of choice seems to be the alternate use of ethylenediaminetetraacetic acid and sodium hypochlorite solutions. Conflict remains regarding the removal of the smear layer before filling root canals, with investigations required to determine the role of the smear layer in the outcomes of root canal treatment. [source]

Potential and limitations of laser technology in restoration of metallic objects of art and cultural heritage

MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 3 2008
U. Klotzbach
Abstract Potential applications of laser techniques, such as precision cutting, micro welding, and ablation of stains, are presented. Concerning laser beam ablation, we explain the mechanism, and then discuss potential applications (cleaning of gilded or solid metal surfaces, cleaning of verdigris) and limits (thinning of verdigris, removing rust from verdigris). This research has been performed within the frame of a joint project sponsored by Deutsche Bundesstiftung Umwelt (DBU, German Foundation for the Environment) as well as in immediate co-operation with restorers. The presentation of these results is to propose laser technology as a promising option to be taken into account in planning and doing restoratory work. [source]

Planar Droplet Sizing for the Characterization of Droplet Clusters in an Industrial Gun-Type Burner

PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 3 2003
Laurent Zimmer
Abstract An important problem in spray combustion deals with the existence of dense regions of droplets, called clusters. To understand their formation mechanism, the droplet dynamics and fuel concentration profile are investigated by means of planar laser techniques in an industrial gun-type burner. The simultaneous measurement of elastic Mie scattering and Laser Induced Fluorescence (LIF) allows the instantaneous measurement of the Sauter Mean Diameter (SMD), after proper calibration. Using two different CCDs to get the two signals requires a detailed calibration of the CCD response before getting absolute diameters. Pixels are binned 6 by 6 to obtain the final SMD map, this is a compromise between spatial accuracy and noise. Velocity field is measured on both sets of images using standard Particle Image Velocimetry (PIV) algorithms. The comparison of cross-correlation technique with PDA results shows that the velocity measured on the LIF images are close to the velocity based on D30, whereas the Mie scattering results are similar to D20. On Mie scattering images, regions of high interfacial area forming clusters can be detected. A special tracking scheme is used to characterize their dynamics in terms of velocity and diameters by ensuring that the same volume of fluid is tracked. It is shown that the clusters have a velocity similar to the velocity of droplets with the same diameter as the mean SMD of the cluster. It is also shown that an increase of pressure tends to trigger the appearance of such a group of droplets, due to a smaller diameter of the droplets caused by the increase of pressure discharge. Uncertainties for the different techniques used are discussed. [source]