Aluminum Garnet (aluminum + garnet)

Distribution by Scientific Domains

Kinds of Aluminum Garnet

  • yttrium aluminum garnet

  • Terms modified by Aluminum Garnet

  • aluminum garnet laser

  • Selected Abstracts

    Low-Fluence Q-Switched Neodymium-Doped Yttrium Aluminum Garnet Laser for Melasma with Pre- or Post-Treatment Triple Combination Cream

    BACKGROUND Topical triple combination (TC) treatment is considered the primary approach to melasma. Recently, collimated low-fluence 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser treatment has attracted attention as an alternative approach. OBJECTIVES To compare the clinical efficacy and adverse effects of low-fluence Q-switched Nd:YAG laser when performed before and after treatment with topical TC using a split-face crossover design. METHODS Thirteen patients with melasma received topical treatment with TC cream or 1,064-nm Q-switched Nd:YAG laser treatment on opposite sides of the face for 8 weeks, and then treatments were reversed for 8 weeks. Responses were evaluated using the Melasma Area and Severity Index scoring system, spectrophotometry measurements, and a subjective self-assessment method. RESULTS After 16 weeks, better results were seen in subjective assessments when laser treatment was used after 8 weeks of topical TC treatment than before usage of TC. There were no significant adverse effects with the laser treatments. CONCLUSIONS Laser treatment after topical TC cream was found to be safer and more effective than the post-treatment use of topical agents. The authors have indicated no significant interest with commercial supporters. [source]

    Treatment of Melasma Using Variable Square Pulse Er: YAG Laser Resurfacing

    BACKGROUND Treatment of melasma remains a challenge. Laser treatments show limited efficacy, with a high rate of recurrence and side effects. Recently, variable-pulsed erbium:yttrium aluminum garnet (Er:YAG) lasers have shown favorable results in skin resurfacing, with minimal downtime and adverse effects. OBJECTIVE To determine the efficacy and side effects of variable square pulsed (VSP) Er:YAG laser resurfacing for treatment of epidermal type melasma. METHODS Twenty Thai women with epidermal-type melasma were treated with two passes of VSP Er:YAG laser resurfacing using a 7-mm spot size, pulse duration of 300 ,s, and a fluence of 0.4 J/cm2. Two treatments were given 1 month apart. Visual analog scale (VAS), Melasma Area and Severity Index (MASI) score and melanin index (MI) were measured at baseline and 1, 2, and 4 months after treatment. RESULTS There was a significant improvement in VAS from baseline at 1-, 2-, and 4-month follow-up visits (p<.001). Significant improvement in MASI score at the 2-month visit from baseline (p=.004) was also observed. The average MI measured using melanin reflectance spectrometry measurements corresponded to MASI score rating. CONCLUSIONS VSP Er:YAG laser resurfacing effectively but temporarily improved epidermal-type melasma. Recurrence was observed after the treatment was discontinued. [source]

    Fluorescence-controlled Er:YAG laser for caries removal in permanent teeth: a randomized clinical trial

    Henrik Dommisch
    The aim of this randomized clinical study was to compare the efficacy of a fluorescence-controlled erbium-loaded yttrium aluminum garnet (Er:YAG) laser with conventional bur treatment for caries therapy in adults. Twenty-six patients with 102 carious lesions were treated using either the Er:YAG laser, at threshold levels of 7, 8, 9, and 10 [U], or rotary burs. Both techniques were applied to each lesion at separate locations. After treatment, dentine samples were obtained using a carbide bur. The viable counts of Streptococcus mutans (SM) and lactobacilli (LB) [expressed as colony-forming units (log10 CFUs)], treatment time, pain, vibration, and sound intensity were determined. The median numbers of CFUs for SM and LB were not statistically different between laser and bur treatment at threshold levels 7 and 8 [U]. At threshold levels 9 and 10 [U], the median number of CFUs for LB [1.11 (range: 0.00,2.04)] were significantly higher following laser treatment than following bur treatment [0.30 (range: 0.00,0.60)]. The results indicate that treatment with a fluorescence-controlled Er:YAG laser at threshold levels of 7 and 8 removed caries to a level similar to that achieved using conventional bur treatment, with clinically irrelevant amounts of remaining bacteria. Although more time consuming, laser treatment provided higher patient comfort than bur treatment. [source]

    Modifying the Output Characteristics of an Organic Light-Emitting Device by Refractive-Index Modulation,

    T. Höfler
    Abstract In order to modify the output characteristics of organic light-emitting devices (OLEDs), the optical properties of an active layer within the device are patterned without introducing any thickness modulation. For this purpose a new conjugated copolymer, which serves as a hole-transporting material and at the same time can be index patterned using UV techniques, is synthesized. Poly(VC- co -VBT) (VC: N -vinylcarbazole; VBT: 4-vinylbenzyl thiocyanate) is prepared by free-radical copolymerization of VC and VBT. The material contains photoreactive thiocyanate groups that enable altering of the material's refractive index under UV illumination. This copolymer is employed as a patternable hole-transporting layer in multilayer OLEDs. Refractive-index gratings in poly(VC- co -VBT) are inscribed using a holographic setup based upon a Lloyd mirror configuration. The fourth harmonic of a Nd:YAG (YAG: yttrium aluminum garnet) laser (266,nm) serves as the UV source. In this way 1D photonic structures are integrated in an OLED containing AlQ3 (tris(8-hydroxyquinoline) aluminum) as the emitting species. It is assured that only a periodical change of the refractive index (,n,=,0.006 at ,,=,540,nm) is generated in the active material but no surface-relief gratings are generated. The patterned devices show more forward-directed out-coupling behavior than unstructured devices (increase in luminosity by a factor of five for a perpendicular viewing direction). This effect is most likely due to Bragg scattering. For these multilayer structures, optimum outcoupling was observed for grating periods ,,,,390,nm. [source]

    Lasers for facial rejuvenation: a review

    Evangelia Papadavid MD
    Background Different types of laser are used for resurfacing and collagen remodeling in cutaneous laser surgery. Methods A systematic review was performed of the different types of laser currently employed for skin rejuvenation. These systems are either ablative [high-energy pulsed or scanned carbon dioxide (CO2) laser emitting at a wavelength of 10,600 nm, single- or variable-pulse or dual ablative/coagulative mode erbium:yttrium aluminum garnet (Er:YAG) laser emitting at a wavelength of 2940 nm, or systems combining both 10,600 nm and 2940 nm wavelengths] or nonablative [Q-switched neodymium:yttrium aluminum garnet (Nd:YAG) laser emitting at a wavelength of 1064 nm, Nd:YAG laser emitting at a wavelength of 1320 nm, or diode laser emitting at a wavelength of 1450 nm]. Different protocols, patient selection, treatment techniques, and complications are discussed for each system. Results New-generation CO2 resurfacing lasers have been successful in the treatment of photodamaged skin and scarring, with a postoperative morbidity dependent on the depth of thermal damage. Because of its minimal penetration, the pulsed Er:YAG laser, usually used in the treatment of more superficial rhytides, produces less postoperative morbidity. Novel ablative systems have been developed and a further understanding of laser,tissue interaction has led to the design of nonablative systems for the treatment of rhytides, scarring, and photodamaged skin, the efficacy and profile of which remain to be evaluated in the long term. Conclusions There are several effective techniques for scar revision and the treatment of aged skin, but all have their drawbacks due to a lack of precise depth control and unwanted damage to the lower layers of the dermis. The Er:YAG laser is the treatment of choice for fine lines and superficial scars, whereas the CO2 laser is better for deeper rhytides and scars. In the future, a combination of lasers may be used for facial rejuvenation. [source]


    MS Author, Thomas J. Hilton DMD
    The use of Er:YAG (erbium : yttrium aluminum garnet and Er,Cr:YAG (erbium, chromium : yttrium scandium gallium garnet) lasers for tooth preparation has received much attention in recent years. Several advantages have been attributed to these devices, including a reduced need for local anesthesia for tooth preparation, less vibration to the patient, and more conservative cavity preparation. Another purported advantage has been the contention that adhesion to tooth structure is enhanced compared with other means of cavity preparation, even to the point of eliminating the need for conditioning and/or etching prior to adhesive system application. As the use of bonded, esthetic restorations has increased, it is important to know if this purported bonding advantage is valid. This Critical Appraisal examines evidence in the peer-reviewed scientific literature that contradicts this contention, and discusses concerns regarding the use of lasers in cavity preparation. [source]

    Low-Temperature Synthesis of Nanocrystalline Yttrium Aluminum Garnet Powder Using Triethanolamine

    Yangqiao Liu
    Nanocrystalline yttrium aluminum garnet (YAG, Y3Al5O12) was synthesized by pyrolysis of complex compounds of aluminum and yttrium with triethanolamine [(HOCH2CH2)3N, (TEA)]. Loose and porous precursor was obtained on complete dehydration of the metal ion,triethanolamine complexes. Pure YAG powder was obtained by calcination of the precursor at 950°C. The precursor was characterized by simultaneous thermogravimetry, differential scanning calorimetry, and mass spectra analyses (TG,DSC,MS). The heat-treated powders were characterized by X-ray diffractometry (XRD), specific surface area measurements, and transmission electron microscopy (TEM). The average crystallite size as determined from X-ray line broadening and transmission electron microscopy studies was ,40 nm. The effects of the calcination temperature and the ratio of triethanolamine to mixed metal ions were also studied. [source]

    Influence of Moisture on Ultra-High-Temperature Tensile Creep Behavior of in Situ Single-Crystal Oxide Ceramic Alumina/Yttrium Aluminum Garnet Eutectic Composite

    Yoshihisa Harada
    Tensile creep tests were conducted for an in situ single-crystal alumina/yttrium aluminum garnet (Al2O3/Y3Al5O12 (YAG)) binary system eutectic composite at temperatures between 1773 and 1873 K in air and in a moist environment having a water-vapor pressure range of 0.06,0.6 MPa, under a constant tensile stress range of 100,160 MPa. The Al2O3/YAG eutectic composite exhibited a stress exponent of 8,13, indicative of tensile creep behavior characterized by a dislocation back-stress mechanism. Water-vapor pressures ,0.4 MPa led to a significant acceleration of creep rates as a result of enhanced dislocation mobility in the Al2O3 and YAG phases. [source]

    Stepwise-Graded Si3N4,SiC Ceramics with Improved Wear Properties

    Scott C. Thompson
    The processing of stepwise graded Si3N4/SiC ceramics by pressureless co-sintering is described. Here, SiC (high elastic modulus, high thermal expansion coefficient) forms the substrate and Si3N4 (low elastic modulus, low thermal expansion coefficient) forms the top contact surface, with a stepwise gradient in composition existing between the two over a depth of ,1.7 mm. The resulting Si3N4 contact surface is fine-grained and dense, and it contains only 2 vol% yttrium aluminum garnet (YAG) additive. This graded ceramic shows resistance to cone-crack formation under Hertzian indentation, which is attributed to a combined effect of the elastic-modulus gradient and the compressive thermal-expansion-mismatch residual stress present at the contact surface. The presence of the residual stress is corroborated and quantified using Vickers indentation tests. The graded ceramic also possesses wear properties that are significantly improved compared with dense, monolithic Si3N4 containing 2 vol% YAG additive. The improved wear resistance is attributed solely to the large compressive stress present at the contact surface. A modification of the simple wear model by Lawn and co-workers is used to rationalize the wear results. Results from this work clearly show that the introduction of surface compressive residual stresses can significantly improve the wear resistance of polycrystalline ceramics, which may have important implications for the design of contact-damage-resistant ceramics. [source]

    Synthesis and Optical Properties of Rare-Earth,Aluminum Oxide Glasses

    J. K. Richard Weber
    Single-phase glasses containing 37.5 mol% Y2O3, 7 mol% La2O3, and 1 mol% Pr, Ho, Nd, Er, Sm, Tm, Eu, or Yb oxide substituted for part of the Y2O3 were synthesized by containerless melting. The spectral transmission and absorption cross sections of the glasses were determined at wavelengths from 360 to 3300 nm. The electronic transitions were broadened compared with results obtained in a crystalline yttrium aluminum garnet (YAG) host. The infrared transmission of the host glass extended to 6000 nm. The optical and physicochemical properties of these glasses are well suited for optical device applications. [source]

    Coarsening of Lamellar Microstructures in Directionally Solidified Yttrium Aluminate/Alumina Eutectic Fiber

    Deok-Yong Park
    Coarsening of the fine lamellar structure of a directionally solidified Y3Al5O12 (yttrium aluminum garnet, YAG)/Al2O3 eutectic fiber at elevated temperatures was investigated. The fibers were grown continuously by an edge-defined film-fed growth (EFG) technique. To study the thermal stability of the lamellar structure, the fibers were heat-treated in air at 1360°,1460°C for up to 200 h. X-ray diffractometry and scanning electron microscopy were used to characterize the microstructures of the fibers. Image analysis was used to measure the length of the interface line between Y3Al5O12 and Al2O3 phases. The kinetics of coarsening and the rate-controlling mechanisms were investigated. Also, the Graham and Kraft model for describing the coarsening behavior of the lamellar Al-CuAl2 eutectic alloy was used to explain the coarsening behavior of Y3Al5O12/Al2O3 eutectic fiber. [source]

    Microtensile bond strength of different adhesive systems in dentin irradiated with Er:YAG laser

    L.M.G. Sierpinsky
    Abstract The objective this study was to evaluate in vitro the bond strength of two etch-and-rise and one self-etching adhesive system after dentin irradiation with Er:YAG (erbium: yttrium aluminum garnet) laser using microtensile test. The results revealed that the groups treated with laser Er:YAG presented less tensile bond strength, independently to the adhesive system used. The prompt L-pop adhesive presented less microtensile bond strength compared to the other adhesives evaluated. There was no difference between single bond and excite groups. The adhesive failures were predominant in all the experimental groups. The Er:YAG laser influenced negatively bond strength values of adhesive systems tested in dental substrate. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]

    Fractional 1320 nm Nd : YAG laser in the treatment of acne vulgaris: a pilot study

    Hui Deng
    Thirty-five patients with moderate to severe acne were treated with a fractional 1320 nm neodymium : yttrium aluminum garnet (Nd : YAG) laser. These patients received six treatment sessions at a 2-week interval. Inflammatory and non-inflammatory lesions were counted before and after treatment. Fractional 1320 nm Nd : YAG laser therapy was well tolerated, resulting in the reduction of inflammatory lesions by 57% (P<0.05) and the reduction of non-inflammatory lesions by 35% (P<0.05). A significant reduction in the skin sebum level by 30% (P<0.05) was also noted after treatment. [source]