Efficacy and safety of erbium-doped yttrium aluminium garnet fractional resurfacing laser for treatment of facial acne scars.

PubMed

Nirmal, Balakrishnan; Pai, Sathish B; Sripathi, Handattu; Rao, Raghavendra; Prabhu, Smitha; Kudur, Mohan H; Nayak, Sudhir U K

2013-01-01

Treatment of acne scars with ablative fractional laser resurfacing has given good improvement. But, data on Indian skin are limited. A study comparing qualitative, quantitative, and subjective assessments is also lacking. Our aim was to assess the improvement of facial acne scars with Erbium-doped Yttrium Aluminium Garnet (Er:YAG) 2940 nm fractional laser resurfacing and its adverse effects in 25 patients at a tertiary care teaching hospital. All 25 patients received four treatment sessions with Er:YAG fractional laser at 1-month interval. The laser parameters were kept constant for each of the four sittings in all patients. Qualitative and quantitative assessments were done using Goodman and Barron grading. Subjective assessment in percentage of improvement was also documented 1 month after each session. Photographs were taken before each treatment session and 1 month after the final session. Two unbiased dermatologists performed independent clinical assessments by comparing the photographs. The kappa statistics was used to monitor the agreement between the dermatologists and patients. Most patients (96%) showed atleast fair improvement. Rolling and superficial box scars showed higher significant improvement when compared with ice pick and deep box scars. Patient's satisfaction of improvement was higher when compared to physician's observations. No serious adverse effects were noted with exacerbation of acne lesions forming the majority. Ablative fractional photothermolysis is both effective and safe treatment for atrophic acne scars in Indian skin.Precise evaluation of acne scar treatment can be done by taking consistent digital photographs.

Radiative Performance of Rare Earth Garnet Thin Film Selective Emitters

NASA Technical Reports Server (NTRS)

Lowe, Roland A.; Chubb, Donald L.; Good, Brian S.

1994-01-01

In this paper we present the first emitter efficiency results for the thin film 40 percent Er-1.5 percent Ho YAG (Yttrium Aluminum Garnet, Y3Al5O12) and 25 percent Ho YAG selective emitter at 1500 K with a platinum substrate. Spectral emittance and emissive power measurements were made (1.2 less than lambda less than 3.2 microns). Emitter efficiency and power density are significantly improved with the addition of multiple rare earth dopants. Predicted efficiency results are presented for an optimized (equal power density in the Er, (4)I(sub 15/2)-(4)I(sub 13/2) at 1.5 microns, and Ho, (5)I(sub 7)-(5)I(sub 8) at 2.0 micron emission bands) Er-Ho YAG thin film selective emitter.

Rare earth garnet selective emitter

NASA Technical Reports Server (NTRS)

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approximately equal to 0.74, ((4)l(sub 15/2)) - ( (4)l(sub13/2)), for Er-YAG and epsilon(sub lambda) approximately equal to 0.65, ((5)l(sub 7))-((5)l(sub 8)) for Ho-YAG) at excellent candidates for high efficiency selective emitters in the thermophotovoltaics (TPV) systems operating at moderate temperatures (1200-1500K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. This paper presents normal spectral emittance, epsilon(sub lambda), measurements of holmium (Ho), and erbium (Er) doped YAG thin film selective emitters at 1500 K, and compares those results with the theoretical spectral emittance.

A systematic review of comparative studies of CO2 and erbium:YAG lasers in resurfacing facial rhytides (wrinkles).

PubMed

Chen, Kee-Hsin; Tam, Ka-Wai; Chen, I-Fan; Huang, Shihping Kevin; Tzeng, Pei-Chuan; Wang, Hsian-Jenn; Chen, Chiehfeng Cliff

2017-08-01

Laser resurfacing is used to minimize wrinkles, solar scars and sequelae of acne. Purpose of the systematic review was to compare resurfacing outcomes of CO 2 laser and erbium: yttrium aluminium garnet (erb:YAG) laser therapies. Medline, Cochrane Library, EMBASE and Google Scholar databases were searched until 9 April 2015 using the following terms: laser, carbon dioxide/CO 2 , facial wrinkles, rhytides and erbium-doped yttrium aluminium garnet/erbium:YAG/Er:YAG. Two-armed controlled split faced studies that compared CO 2 laser and erbium:YAG laser in patients with mild-to-moderate facial wrinkles or rhytides were included. The pooled data in this study and findings of other studies support the greater efficacy with the CO 2 laser in improving facial wrinkles, but the erb:YAG laser was associated with a better complication profile compared with the CO 2 laser. Except one case of hypopigmentation, other complications (i.e., erythema, hyperpigmentation and crusting) and their rates were reported by studies examining both lasers. In general, the CO 2 laser appeared to be more efficacious then the erb:YAG laser in treating facial wrinkles. Both lasers treatments were well tolerated.

Rare Earth Garnet Selective Emitter

NASA Technical Reports Server (NTRS)

Lowe, Roland A.; Chubb, Donald L.; Farmer, Serene C.; Good, Brian S.

1994-01-01

Thin film Ho-YAG and Er-YAG emitters with a platinum substrate exhibit high spectral emittance in the emission band (epsilon(sub lambda) approx. = 0.75, sup 4)|(sub 15/2) - (sup 4)|(sub 13/2),for Er-YAG and epsilon(sub lambda) approx. = 0.65, (sup 5)|(sub 7) - (sup 5)|(sub 8) for Ho-YAG) at 1500 K. In addition, low out-of-band spectral emittance, epsilon(sub lambda) less than 0.2, suggest these materials would be excellent candidates for high efficiency selective emitters in thermophotovoltaic (TPV) systems operating at moderate temperatures (1200-1500 K). Spectral emittance measurements of the thin films were made (1.2 less than lambda less than 3.0 microns) and compared to the theoretical emittances calculated using measured values of the spectral extinction coefficient. In this paper we present the results for a new class of rare earth ion selective emitters. These emitters are thin sections (less than 1 mm) of yttrium aluminum garnet (YAG) single crystal with a rare earth substitutional impurity. Selective emitters in the near IR are of special interest for thermophotovoltaic (TPV) energy conversion. The most promising solid selective emitters for use in a TPV system are rare earth oxides. Early spectral emittance work on rare earth oxides showed strong emission bands in the infrared (0.9 - 3 microns). However, the emittance outside the emission band was also significant and the efficiency of these emitters was low. Recent improvements in efficiency have been made with emitters fabricated from fine (5 - 10 microns) rare earth oxide fibers similar to the Welsbach mantle used in gas lanterns. However, the rare earth garnet emitters are more rugged than the mantle type emitters. A thin film selective emitter on a low emissivity substrate such as gold, platinum etc., is rugged and easily adapted to a wide variety of thermal sources. The garnet structure and its many subgroups have been successfully used as hosts for rare earth ions, introduced as substitutional

Long-term remission of folliculitis decalvans after treatment with the long-pulsed Nd:YAG laser.

PubMed

Meesters, Arne A; Van der Veen, J P Wietze; Wolkerstorfer, Albert

2014-04-01

Folliculitis decalvans (FD) is a rare inflammatory scalp disorder presenting with tufted folliculitis, follicular papules and pustules, progressing to cicatricial alopecia. Current treatments mainly consist of antibiotic and immunomodulatory therapies and are often disappointing. FD has previously shown to respond to treatment with neodymium:yttrium aluminium garnet (Nd:YAG) laser in one case. We present a case of recalcitrant FD, successfully treated with a long-pulsed Nd:YAG laser.

Clinical and Histopathologic Assessment of Facial Melasma After Low-Fluence Q-Switched Neodymium-Doped Yttrium Aluminium Garnet Laser.

PubMed

Hofbauer Parra, Camila Anna; Careta, Mariana Figueroa; Valente, Neusa Yuriko Sakai; de Sanches Osório, Nuno Eduardo Guimaraes; Torezan, Luis Antonio Ribeiro

2016-04-01

Melasma is a frequent and difficult to treat skin disorder. Results of laser therapy are inconsistent. To determine the safety and efficacy of low-fluence Q-switched neodymium-doped yttrium aluminum garnet (QS Nd:YAG) laser for melasma treatment and assess recurrence rates and histopathologic findings before and after treatment. Twenty patients were treated with 10 weekly sessions of low-fluence 1064-nm QS Nd:YAG laser at 1-week intervals. The modified Melasma Area and Severity Index (mMASI) score was evaluated at baseline; 1 week; and 1, 3, and 6 months after treatment. Epidermal melanin quantification was performed on 10 biopsy samples and compared before and after treatment. All patients showed improvement by mMASI scores, range (21%-75%) compared with that at baseline. No permanent side effects occurred. The recurrence rate was 81%. By histopathology, a slight, nonsignificant (p = .305) decrease in melanin deposition was seen in all layers of the epidermis 1 week after the laser treatments ended. The results confirm the safety and effectiveness of low-fluence QS Nd:YAG laser for treating melasma; however, the high recurrence suggests poor long-term results when the laser is used as a monotherapy.

Kinetic characteristics of the luminescence decay for industrial yttrium-gadolinium-aluminium garnet based phosphors

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Stepanov, S. A.; Valiev, D. T.; Vishnyakova, E. A.; Abdullin, H. A.; Marhabaeva, A. A.; Tulegenova, A. T.

2016-02-01

The spectral and decay kinetic characteristics of pulse cathodoluminescence and photoluminescence of phosphors based on yttrium-gadolinium-aluminum garnet were investigated using pulsed optical time resolved spectroscopy.

Sealing ability of three root-end filling materials prepared using an erbium: Yttrium aluminium garnet laser and endosonic tip evaluated by confocal laser scanning microscopy

PubMed Central

Nanjappa, A Salin; Ponnappa, KC; Nanjamma, KK; Ponappa, MC; Girish, Sabari; Nitin, Anita

2015-01-01

Aims: (1) To compare the sealing ability of mineral trioxide aggregate (MTA), Biodentine, and Chitra-calcium phosphate cement (CPC) when used as root-end filling, evaluated under confocal laser scanning microscope using Rhodamine B dye. (2) To evaluate effect of ultrasonic retroprep tip and an erbium:yttrium aluminium garnet (Er:YAG) laser on the integrity of three different root-end filling materials. Materials and Methods: The root canals of 80 extracted teeth were instrumented and obturated with gutta-percha. The apical 3 mm of each tooth was resected and 3 mm root-end preparation was made using ultrasonic tip (n = 30) and Er:YAG laser (n = 30). MTA, Biodentine, and Chitra-CPC were used to restore 10 teeth each. The samples were coated with varnish and after drying, they were immersed in Rhodamine B dye for 24 h. The teeth were then rinsed, sectioned longitudinally, and observed under confocal laser scanning microscope. Statistical Analysis Used: Data were analyzed using one-way analysis of variance (ANOVA) and a post-hoc Tukey's test at P < 0.05 (R software version 3.1.0). Results: Comparison of microleakage showed maximum peak value of 0.45 mm for Biodentine, 0.85 mm for MTA, and 1.05 mm for Chitra-CPC. The amount of dye penetration was found to be lesser in root ends prepared using Er:YAG laser when compared with ultrasonics, the difference was found to be statistically significant (P < 0.05). Conclusions: Root-end cavities prepared with Er:YAG laser and restored with Biodentine showed superior sealing ability compared to those prepared with ultrasonics. PMID:26180420

Evaluation of critical distances for energy transfer between Pr{sup 3+} and Ce{sup 3+} in yttrium aluminium garnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zeng, Peng; Wei, Xiantao; Yin, Min

A series of Pr{sup 3+}/Ce{sup 3+} doped yttrium aluminium garnet (Y{sub 3}Al{sub 5}O{sub 12} or simply YAG) phosphors were synthesized to investigate the energy transfer between Pr{sup 3+} and Ce{sup 3+} for their potential application in a white light-emitting diode and quantum information storage and processing. The excitation and emission spectra of YAG:Pr{sup 3+}/Ce{sup 3+} were measured and analyzed, and it revealed that the reabsorption between Pr{sup 3+} and Ce{sup 3+} was so weak that it can be ignored, and the energy transfer from Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{submore » 2}) did occur. By analyzing the excitation and the emission spectra, the energy transfer from Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{sub 2}) was examined in detail with an original strategy deduced from fluorescence dynamics and the Dexter energy transfer theory, and the critical distances of energy transfer were derived to be 7.9 Å and 4.0 Å for Pr{sup 3+} (5d) to Ce{sup 3+} (5d) and Ce{sup 3+} (5d) to Pr{sup 3+} ({sup 1}D{sub 2}), respectively. The energy transfer rates of the two processes of various concentrations were discussed and evaluated. Furthermore, for the purpose of sensing a single Pr{sup 3+} state with a Ce{sup 3+} ion, the optimal distance of Ce{sup 3+} from Pr{sup 3+} was evaluated as 5.60 Å, where the probability of success reaches its maximum value of 78.66%, and meanwhile the probabilities were evaluated for a series of Y{sup 3+} sites in a YAG lattice. These results will be of valuable reference for achievement of the optimal energy transfer efficiency in Pr{sup 3+}/Ce{sup 3+} doped YAG and other similar systems.« less

Results of fractional ablative facial skin resurfacing with the erbium:yttrium-aluminium-garnet laser 1 week and 2 months after one single treatment in 30 patients.

PubMed

Trelles, Mario A; Mordon, Serge; Velez, Mariano; Urdiales, Fernando; Levy, Jean Luc

2009-03-01

The erbium:yttrium-aluminium-garnet (Er:YAG) laser has recently been used in the fractional resurfacing of photo-aged skin. Our study evaluated the results after one single session of fractional resurfacing with Er:YAG. Thirty women participated in the study, with an average age of 46 years, skin types from II to IV, and wrinkle grades I to III. The 2,940 nm Er:YAG system used (Pixel, Alma Laser, Israel) had variable pulse durations (1 ms to 2 ms) and energy densities (800 mJ/cm(2) to 1,400 mJ/cm(2)) which, together with the number of passes (four to eight), were selected as a function of wrinkle severity. All patients received only one treatment. Postoperative side effects were evaluated. The number of wrinkles was documented with clinical photography and was scored. Histological assessment was carried out on two patients before and 2 months after treatment. All patients completed the study. Of the patients, 93% reported good or very good improvement of the degree of their wrinkles, with a satisfaction index of 83%. Pain was not a problem during treatment, and there were no side effects except for in one phototype IV patient, who had hyperpigmentation. Histology 2 months after the single treatment demonstrated younger morphology of both the epidermis and dermis, with improvement of the pretreatment typical elastotic appearance. At the parameters used in our study, only one treatment session of Er:YAG laser could achieve effective skin rejuvenation, with effects recognized in both the dermis and, more importantly, the epidermis. This regimen offers an interesting alternative to the conventional approach of multi-session fractional resurfacing.

Determinants of holmium:yttrium-aluminum-garnet laser time and energy during ureteroscopic laser lithotripsy.

PubMed

Molina, Wilson R; Marchini, Giovanni S; Pompeo, Alexandre; Sehrt, David; Kim, Fernando J; Monga, Manoj

2014-04-01

To evaluate the association of preoperative noncontrast computed tomography stone characteristics, laser settings, and stone composition with cumulative holmium:yttrium-aluminum-garnet (Ho:YAG) laser time/energy. We retrospectively reviewed patients who underwent semirigid/flexible ureteroscopy and Ho:YAG laser lithotripsy (200 or 365 μm laser fiber; 0.8-1.0 J energy; and 8-10 Hz rate) at 2 tertiary care centers (April 2010-May 2012). Studied parameters were as follows: patient's characteristics; stone characteristics (location, burden, hardness, and composition); total laser time and energy; and surgical outcomes. One hundred patients met our inclusion criteria. Mean stone size was 1.01 ± 0.42 cm and volume 0.33 ± 0.04 cm(3). Mean stone radiodensity was 990 ± 296 HU, and Hounsfield units density 13.8 ± 6.0 HU/mm. All patients were considered stone free. Stone size and volume had a significant positive correlation with laser energy (R = 0.516, P <.001; R = 0.621, P <.001) and laser time (R = 0.477, P <.001; R = 0.567, P <.001). When controlling for stone size, only the correlation between HU and laser time was significant (R = 0.262, P = .011). In the multivariate analysis, with exception of stone composition (P = .103), all parameters significantly increased laser energy (R(2) = 0.524). Multivariate analysis revealed a positive significant association of laser time with stone volume (P <.001) and Hounsfield units density (P <.001; R(2) = 0.512). In multivariate analysis for laser energy, only calcium phosphate stones required less energy to fragment compared with uric acid stones. No significant differences were found in the multivariate laser time model. Ho:YAG laser cumulative energy and total time are significantly affected by stone dimensions, hardness location, fiber size, and power. Kidney location, laser fiber size, and laser power have more influence on the final laser energy than on the total laser time. Calcium phosphate stones require less laser

Ablation of porcine ligamentum flavum with Ho:YAG, q-switched Ho:YAG, and quadrupled Nd:YAG lasers.

PubMed

Johnson, Matt R; Codd, Patrick J; Hill, Westin M; Boettcher, Tara

2015-12-01

Ligamentum flavum (LF) is a tough, rubbery connective tissue providing a portion of the ligamentous stability to the spinal column, and in its hypertrophied state forms a significant compressive pathology in degenerative spinal stenosis. The interaction of lasers and this biological tissue have not been thoroughly studied. Technological advances improving endoscopic surgical access to the spinal canal makes selective removal of LF using small, flexible tools such as laser-coupled fiber optics increasingly attractive for treatment of debilitating spinal stenosis. Testing was performed to assess the effect of Ho:YAG, Q-switched Ho:YAG, and frequency quadrupled Nd:YAG lasers on samples of porcine LF. The objective was to evaluate the suitability of these lasers for surgical removal of LF. LF was resected from porcine spine within 2 hours of sacrifice and stored in saline until immediately prior to laser irradiation, which occurred within an additional 2 hours. The optical absorbance of a sample was measured over the spectral band from 190 to 2,360 nm both before and after dehydration. For the experiments using the Ho:YAG (λ = 2,080 nm, tp  = 140 µs, FWHM) and Q-Switched Ho:YAG (λ = 2,080 nm, tp  = 260 ns, FWHM) lasers, energy was delivered to the LF through a laser-fiber optic with 600 µm core and NA = 0.39. For the experiment using the frequency quadrupled Nd:YAG laser (λ = 266 nm, tp  = 5 ns FWHM), rather than applying the laser energy through a laser-fiber, the energy was focused through an aperture and lens directly onto the LF. Five experiments were conducted to evaluate the effect of the given lasers on LF. First, using the Ho:YAG laser, the single-pulse laser-hole depth versus laser fluence was measured with the laser-fiber in direct contact with the LF (1 g force) and with a standoff distance of 1 mm between the laser-fiber face and the LF. Second, with the LF remaining in situ and the spine bisected

Growth of high quality yttrium iron garnet films using standard pulsed laser deposition technique

NASA Astrophysics Data System (ADS)

Zaki, Aliaa M.; Blythe, Harry J.; Heald, Steve M.; Fox, A. Mark; Gehring, Gillian A.

2018-05-01

Thin films with properties comparable to bulk single crystals were grown by pulsed laser deposition using a substrate temperature of only 500 °C. This was achieved by a careful choice of both the oxygen pressure in the deposition chamber and the temperature of the air anneal. The best films were grown on gadolinium gallium garnet substrates but we also report data for films grown on the diamagnetic substrate yttrium aluminium garnet. The films were analysed using X-ray diffraction, near edge X-ray absorption and magnetometry. Our best films had a magnetisation of 143 emu/cm3 and a coercive field of ∼1 Oe.

The contact neodymium-yttrium aluminum garnet laser. A new approach to arthroscopic laser surgery.

PubMed

O'Brien, S J; Miller, D V

1990-03-01

Arthroscopic treatment of meniscal lesions has been modified as technological advances have occurred. However, alternatives to conventional arthroscopic cutting tools, including electrocautery and CO2 lasers, have thus far met with limited success. The recent development of a sapphire tip has enabled the use of the neodymium-yttrium aluminum garnet (Nd-YAG) laser in a contact mode in a saline medium. This study compares the biology of the Nd-YAG laser to that of electrocautery and scalpel techniques with respect to its effects on articular cartilage and the meniscus. The contact Nd-YAG laser has advantages over both scalpel and electrocautery with regard to its effects on articular cartilage. It also has significant biologic advantages over electrocautery for meniscal lesions. Although in its infancy in the clinical setting, the contact Nd-YAG laser represents the possible beginning of a new era for application of laser energy in arthroscopy.

Hinged Capsulotomy--Does it Decrease Floaters After Yttrium Aluminum Garnet Laser Capsulotomy?

PubMed

Alipour, Fatemeh; Jabbarvand, Mahmoud; Hashemian, Hesam; Hosseini, Simindokht; Khodaparast, Mehdi

2015-01-01

The objective was to compare conventional circular yttrium aluminum garnet (YAG) laser capsulotomy with hinged capsulotomy to manage posterior capsular opacification (PCO). This prospective, randomized clinical trial enrolled pseudophakic patients with visually significant posterior capsule opacification. Patients were randomized to undergo posterior YAG laser capsulotomy with either conventional circular technique or a new technique with an inferior hinge. At 1-month postoperatively, patients were asked if they had any annoying floaters and the responses were compared between groups. P < 0.05 was considered statistically significant. A total of 83 patients were enrolled. Forty-three patients underwent hinged posterior YAG capsulotomy and 40 patients underwent routine circular capsulotomy. At 1-month postoperatively, there was a statistically significant decrease in annoying floaters in the group that underwent circular capsulotomy (P = 0.02). There was no statistically significant association in the total energy delivered (P = 0.4) or the number of spots (P = 0.2) and patient perception of annoying floaters. Hinged YAG capsulotomy was effective at decreasing the rate of floaters in patients with PCO.

Long-pulsed neodymium:yttrium-aluminum-garnet laser treatment for hypertrophic port-wine stains on the lips.

PubMed

Kono, Taro; Frederick Groff, William; Chan, Henry H; Sakurai, Hiroyuki; Yamaki, Takashi

2009-03-01

Pulsed dye laser (PDL) treatment of hypertrophic port-wine stains (PWSs) on the lips has demonstrated poor efficacy and a potential risk of dyspigmentation. PDL-resistant hypertrophic PWS may require treatment with deeper penetrating lasers such as a 1064-nm neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. The objective of this clinical study was to evaluate the efficacy and safety of a Nd:YAG laser for the treatment of hypertrophic PWSs on the lips. Ten patients (four were male and six were female) with hypertrophic PWSs on the lips were recruited in this study. Eight patients showed good to excellent improvement without complications. In conclusion, the Nd:YAG laser is safe and effective for treating hypertrophic PWSs on the lips.

Luminescent down shifting effect of Ce-doped yttrium aluminum garnet thin films on solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Guojian; Lou, Chaogang; Kang, Jian

2015-12-21

Ce-doped yttrium aluminum garnet (YAG:Ce) thin films as luminescent down shifting (LDS) materials are introduced into the module of crystalline silicon solar cells. The films are deposited by RF magnetron sputtering on the lower surface of the quartz glass. They convert ultraviolet and blue light into yellow light. Experiments show that the introduction of YAG:Ce films improves the conversion efficiency from 18.45% of the cells to 19.27% of the module. The increasing efficiency is attributed to LDS effect of YAG:Ce films and the reduced reflection of short wavelength photons. Two intentionally selected samples with similar reflectivities are used to evaluatemore » roughly the effect of LDS alone on the solar cells, which leads to a relative increase by 2.68% in the conversion efficiency.« less

Comparative evaluation of photoablative efficacy of erbium: yttrium-aluminium-garnet and diode laser for the treatment of gingival hyperpigmentation. A randomized split-mouth clinical trial.

PubMed

Giannelli, Marco; Formigli, Lucia; Bani, Daniele

2014-04-01

The use of lasers in periodontology is a matter of debate, mainly because of the lack of consensual therapeutic protocols. In this randomized, split-mouth trial, the clinical efficacy of two different photoablative dental lasers, erbium:yttrium-aluminum-garnet (Er:YAG) and diode, for the treatment of gingival hyperpigmentation is compared. Twenty-one patients requiring treatment for mild-to-severe gingival hyperpigmentation were enrolled. Maxillary or mandibular left or right quadrants were randomly subjected to photoablative deepithelialization with either Er:YAG or diode laser. Masked clinical assessments of each laser quadrant were made at admission and days 7, 30, and 180 postoperatively by an independent observer. Histologic examination was performed before and soon after treatment and 6 months after irradiation. Patients also compiled a subjective evaluation questionnaire. Both diode and Er:YAG lasers gave excellent results in gingival hyperpigmentation. However, Er:YAG laser induced deeper gingival tissue injury than diode laser, as judged by bleeding at surgery, delayed healing, and histopathologic analysis. The use of diode laser showed additional advantages compared to Er:YAG in terms of less postoperative discomfort and pain. This study highlights the efficacy of diode laser for photoablative deepithelialization of hyperpigmented gingiva. It is suggested that this laser can represent an effective and safe therapeutic option for gingival photoablation.

Erbium Distribution in Single Crystal YAG Fibers Grown by Laser-Heated Pedestal Growth Technique

DTIC Science & Technology

2015-08-28

single crystal YAG fibers grown by laser - heated pedestal growth technique Single crystal (SC) yttrium aluminum garnet (YAG, Y3Al5O12) as a host...inserted into a SC YAG tube. This rod-in-tube was used as a preform in our laser -heated pedestal growth (LHPG) apparatus to grow a fiber with a radial...fibers grown by laser -heated pedestal growth technique Report Title Single crystal (SC) yttrium aluminum garnet (YAG, Y3Al5O12) as a host material has

Hinged Capsulotomy – Does it Decrease Floaters After Yttrium Aluminum Garnet Laser Capsulotomy?

PubMed Central

Alipour, Fatemeh; Jabbarvand, Mahmoud; Hashemian, Hesam; Hosseini, Simindokht; Khodaparast, Mehdi

2015-01-01

Objectives: The objective was to compare conventional circular yttrium aluminum garnet (YAG) laser capsulotomy with hinged capsulotomy to manage posterior capsular opacification (PCO). Materials and Methods: This prospective, randomized clinical trial enrolled pseudophakic patients with visually significant posterior capsule opacification. Patients were randomized to undergo posterior YAG laser capsulotomy with either conventional circular technique or a new technique with an inferior hinge. At 1-month postoperatively, patients were asked if they had any annoying floaters and the responses were compared between groups. P < 0.05 was considered statistically significant. Results: A total of 83 patients were enrolled. Forty-three patients underwent hinged posterior YAG capsulotomy and 40 patients underwent routine circular capsulotomy. At 1-month postoperatively, there was a statistically significant decrease in annoying floaters in the group that underwent circular capsulotomy (P = 0.02). There was no statistically significant association in the total energy delivered (P = 0.4) or the number of spots (P = 0.2) and patient perception of annoying floaters. Conclusion: Hinged YAG capsulotomy was effective at decreasing the rate of floaters in patients with PCO. PMID:26180476

Water flow on erbium:yttrium-aluminum-garnet laser irradiation: effects on dental tissues.

PubMed

Colucci, Vivian; do Amaral, Flávia Lucisano Botelho; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka; Corona, Silmara Aparecida Milori

2009-09-01

Since lasers were introduced in dentistry, there has been considerable advancement in technology. Several wavelengths have been investigated as substitutes for high-speed air turbine. Owing to its high absorbability in water and hydroxyapatite, the erbium:yttrium-aluminum-garnet (Er:YAG) laser has been of great interest among dental practitioners and scientists. In spite of its great potential for hard tissue ablation, Er:YAG laser effectiveness and safety is directly related to an adequate setting of the working patterns. It is assumed that the ablation rate is influenced by certain conditions, such as water content of the target tissue, and laser parameters. It has been shown that Er:YAG irradiation with water coolant attenuates temperature rise and, hence, minimizes the risk of thermally induced pulp injury. It also increases ablation efficiency and enhances adhesion to the lased dental tissue. The aim of this review was to obtain insights into the ablation process and to discuss the effects of water flow on dental tissue ablation using Er:YAG laser.

Coupling Ocean Models and Satellite Derived Optical Fields to Estimate LIDAR Penetration and Detection Performance

DTIC Science & Technology

2012-01-01

34Laser oscillations in nd-doped yttrium aluminum , yttrium gallium and gadolinium garnets ," Applied Physics Letters (10): 182. doi:10.1063/1.1753928...Aluminium Garnet ) Nd:YAG lasers, and inherent of this material is its fundamental 1064nm frequency that is frequency doubled to 532 nm to penetrate

120-W 2-µm thulium:yttrium-aluminium-garnet vapoenucleation of the prostate: 12-month follow-up.

PubMed

Netsch, Christopher; Pohlmann, Laura; Herrmann, Thomas R W; Gross, Andreas J; Bach, Thorsten

2012-07-01

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Thulium VapoEnucleation of the prostate (ThuVEP) has been introduced as a minimally invasive treatment modality of benign prostate obstruction (BPO). This study reports the largest series of patients with symptomatic BPO undergoing ThuVEP. Efficacy of this procedure was confirmed by prostate volume and PSA measurements at 12-month follow up, which have not been reported after ThuVEP so far. To evaluate the safety and efficacy of 120-W 2-µm thulium:yttrium-aluminium-garnet (YAG) vapoenucleation of the prostate (ThuVEP) for patients with symptomatic benign prostatic obstruction. In total, 207 consecutive patients undergoing ThuVEP at our institution were evaluated prospectively. ThuVEP was carried out using the 120-W 2-µm continuous-wave Tm:YAG laser. The enucleated tissue was then morcellated within the bladder. Patient demographic, perioperative and 12-month follow-up data were analysed. The complications were assessed. Mean preoperative prostate volume was 57.8 ± 31.5 mL. Total operation duration averaged 64.9 ± 29.9 min, and the enucleation time was 36.5 ± 20.1 min. The mean catheter time was 2.2 ± 0.6 days. Thirteen (6.28%) patients required a second-look operation in the immediate postoperative course (failed morcellation n= 1, clot retention n= 4, residual tissue at the apex of the prostate n= 8). Four patients needed blood transfusions (1.93%) postoperatively. In all, 147 (71%) patients were available for review at the 12-month follow-up mark. Quality of life (4.4 ± 1.3 vs 1.2 ± 1.1), international prostate symptom score (21.9 ± 7.2 vs 5.1 ± 4), maximum urinary flow rate (9.4 ± 3.8 vs 23.5 ± 10.9 mL/s), postvoiding residual urine (159.2 ± 153.2 vs 26.7 ± 38.3 mL), prostate-specific antigen (5.0 ± 5.2 vs 0.6 ± 0.5 ng/mL) and prostate volume (57.8 ± 31.5 vs 10.7 ± 4.4 mL) changed significantly (P= 0.000). Median prostate

Holmium:YAG surgical lasers.

PubMed

1995-03-01

"Holmium:YAG (Ho:YAG)" is the shorthand name for a family of solid-state lasers that use the doping element holmium in a laser crystal (e.g., YAG [yttrium-aluminum-garnet]) and that emit energy at approximately 2.1 microns. This wavelength is relatively new to medicine and has been used in laser surgery for only about the last six years. Like the carbon dioxide (CO2) laser when it was first used clinically, the Ho:YAG laser is poised for rapid and wide-spread use. Ho:YAG lasers, like CO2 lasers, offer precise cutting with minimal damage to adjacent tissue; however, unlike CO2 lasers, they also offer fiberoptic delivery (which is ideal for endoscopic use) and the ability to treat tissue in a liquid-filled environment (e.g., saline, blood). The initial specialty for which the Ho:YAG laser was used was arthroscopic surgery, especially diskectomy. Today, it is effectively used in many surgical specialties, including general surgery, urology, laparoscopy, neurosurgery, lithotripsy, angioplasty, orthopedic surgery (which includes procedures such as meniscectomy, bone sculpting [may also be performed in plastic surgery], and some experimental surgery, such as cartilage shrinking to tighten loose joints), and dentistry. Because of its broad range of potential applications, it has been called the "Swiss Army Knife" of lasers. High-powered Ho:YAG lasers, which enable surgeons to work more quickly and cut more smoothly, have been made available only within the last three years (units offering > 20 W) to 18 months (units offering > 60 W). Because of this rapid increase, high-powered units are still relatively expensive, and it is not yet clear whether maximum power outputs will continue to increase or whether the cost of higher-power units will begin to come down. Although low-power and high-power Ho:YAG lasers can be used for the same procedures, their different ranges of possible clinical techniques make them better suited to different applications: low-power units are

Combined vitamin C sonophoresis and neodymium-doped yttrium aluminum garnet (NdYAG) laser for facial hyperpigmentation: An outcome observation study in Asian patients.

PubMed

Chen, Yu-Tsung; Chang, Chang-Cheng; Hsu, Cherng-Ru; Shen, Jen-Hsiang; Shih, Chao-Jen; Lin, Bor-Shyh

2016-01-01

The neodymium-doped yttrium aluminum garnet (NdYAG) laser therapy has been a popular technique for facial rejuvenation but certain adverse effects like post-inflammatory hyperpigmentation are issues of concern to Asian patients. To assess the outcome following combined treatment with vitamin C sonophoresis and NdYAG laser, in selected cases of facial hyperpigmentation. Twenty three women with dyschromia or melasma who had undergone five sessions of Q-switched NdYAG laser therapy followed by transdermal delivery of vitamin C via sonophoresis were selected after a retrospective review of case records. The objective and subjective clinical outcomes and the side effects, including erythema, scaling, pruritus, dryness and post-inflammatory hyperpigmentation were evaluated. In both objective or subjective outcomes, 91.3% (21/23) of the patients showed an excellent or better outcome, while 8.7% (2/23) showed no change. A majority of the patients (73.9%, 17/23) experienced no post-inflammatory hyperpigmentation or had slight post-inflammatory hyperpigmentation which quickly resolved within 1 week. Only one (4.3%) patient had extreme post-inflammatory hyperpigmentation which lasted for over a month. This was a retrospective study without a control group; a comparative study with a control group (patients treated with the laser alone, without vitamin C sonopheresis) is needed to determine the difference in the outcome. The use of vitamin C sonophoresis along with NdYAG laser may reduce the incidence of adverse effects in Asian patients. Patients experienced obvious improvement in hyperpigmentation and had lower chances of experiencing extreme or severe post-inflammatory hyperpigmentation.

Effects of neodymium-yttrium-aluminum garnet (Nd:YAG) pulsed high-intensity laser therapy on full thickness wound healing in an experimental animal model.

PubMed

Hong, Seung Eun; Hong, Mi Ki; Kang, So Ra; Young Park, Bo

2016-12-01

Wound healing can be aided by the use of low- and medium-intensity lasers. The use of pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) high-intensity laser therapy (HILT) with a 1064-nm wavelength laser provides deeper and more efficient penetration into tissue as it is being less absorbed by chromophores in tissue, e.g., hemoglobin, melanin, and water, thereby enhancing the wound-healing process. In this study, we examined the effect of HILT on wound healing with a Q-switched pulsed Nd:YAG laser in an animal model. Sixty SKH1 hairless male mice (seven weeks old) were randomly divided into four groups according to the amount of laser fluence: control, group 1 (0.8 J/cm 2 ), group 2 (1.6 J/cm 2 ), and group 3 (2.0 J/cm 2 ). Laser treatment was provided to groups 1, 2, and 3 with a 1064-nm Q-switched Nd:YAG laser. Histological analysis was performed with hematoxylin and eosin staining, Masson's Trichrome staining, and Ki-67 staining. Statistically significant increases in the accumulation of collagen fibers, thickness of granulation tissue, and numbers of fibroblasts were observed in group 2 (treated with 1.6 J/cm 2 ) as compared with the control (no laser treatment), group 1 (treated with 0.8 J/cm 2 ), and group 3 (treated with 2.0 J/cm 2 ). Nd:YAG HILT stimulated fibroblast proliferation and increased extracellular matrix production. We expect that this therapy could accelerate the wound-healing process.

Holmium: yttrium aluminum garnet laser-assisted endoscopic sinus surgery: laboratory experience.

PubMed

Shapshay, S M; Rebeiz, E E; Bohigian, R K; Hybels, R L; Aretz, H T; Pankratov, M M

1991-02-01

Endoscopic sinus surgery has gained wide acceptance since its introduction into the United States. Complex sinus anatomy and troublesome bleeding have been associated with complications, which vary in severity from synechia to blindness and leakage of cerebrospinal fluid. Endoscopic sinus surgery using a holmium: yttrium aluminum garnet pulsed solid-state laser oscillating at 2.1 microns with fiberoptic delivery was performed in the laboratory, and the results were compared with those of conventional endoscopic sinus surgery. Three beagle dogs, six human cadaver heads, and one calf head were used in the in vivo and in vitro studies to evaluate the bone ablation, tissue coagulation, and hemostatic properties of the holmium: yttrium aluminum garnet laser. Modified endoscopic telescopes for sinus surgery, a newly developed handpiece for fiberoptic delivery, and other surgical instruments were used. The results indicate that the holmium: yttrium aluminum garnet laser and new delivery instrumentation provide good hemostasis and controlled soft-tissue ablation and bone removal. The access to all sinuses in the human cadaver model was very good. The canine in vivo study showed delayed but complete healing on the laser-treated side. Clinical evaluation of the holmium: yttrium aluminum garnet laser is warranted to increase the precision and safety of endoscopic sinus surgery.

The use of lasers for periodontal debridement: marketing tool or proven therapy?

PubMed

Chanthaboury, Rachel; Irinakis, Tassos

2005-10-01

The use of lasers in dentistry has recently received much attention, in both clinical practice and research; their unique properties produce favourable clinical results in some cases and encourage patient acceptance. Various types of lasers have been investigated as an adjunct to periodontal therapy; these include carbon dioxide (CO₂), diode, neodymium:yttrium-aluminium-garnet (Nd:YAG) and erbium:yttrium-aluminium-garnet (Er:YAG) lasers.However, adverse results have been associated with each type, including thermal damage to root surfaces, increases in pulpal temperature and the production of toxic by-products. The Er:YAG laser has produced the most promising results, as it can ablate effectively with minimal adverse effects. More research is needed to determine the ideal settings and methods for using the laser safely and effectively in clinical practice.

Study of structural and optical properties of YAG and Nd:YAG single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostić, S.; Lazarević, Z.Ž., E-mail: lzorica@yahoo.com; Radojević, V.

2015-03-15

Highlights: • Transparent YAG and pale pink Nd:YAG single crystals were produced by the Czochralski technique. • Growth mechanisms and shape of the liquid/solid interface and incorporation of Nd{sup 3+} were studied. • The structure of the crystals was investigated by X-ray diffraction, Raman and IR spectroscopy. • The 15 Raman and 17 IR modes were observed. • The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. - Abstract: Yttrium aluminum garnet (YAG, Y{sub 3}Al{sub 5}O{sub 12}) and yttrium aluminum garnet doped with neodymium (Nd:YAG) single crystals were grown by the Czochralski technique. Themore » critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the transparent YAG and pale pink Nd:YAG single crystals were produced. The obtained crystals were studied by X-ray diffraction, Raman and IR spectroscopy. The crystal structure was confirmed by XRD. The 15 Raman and 17 IR modes were observed. The Raman and IR spectroscopy results are in accordance with X-ray diffraction analysis. The obtained YAG and Nd:YAG single crystals were without core and of good optical quality. The absence of a core was confirmed by viewing polished crystal slices. Also, it is important to emphasize that the obtained Nd:YAG single crystal has a concentration of 0.8 wt.% Nd{sup 3+} that is characteristic for laser materials.« less

Treatment Outcomes of Long-Pulsed Nd: YAG Laser for Two Different Subtypes of Rosacea

PubMed Central

Say, Ekin Mese; Gökdemir, Gonca

2015-01-01

Background: A variety of lasers have been used for the treatment of rosacea. However, treatment of this condition with long-pulsed neodymium-doped yttrium aluminium garnet laser has not been reported yet. Objective: To assess the efficacy and safety of long-pulsed neodymium-doped yttrium aluminium garnet laser in two different subtypes (erythematotelangiectatic and papulopustular) of rosacea. Methods: A total of 66 patients were enrolled in the study. All of the patients were treated with long-pulsed neodymium-doped yttrium aluminium garnet laser with 3- to 4-week intervals. Rosacea severity score was assessed by using photographs. Improvement in severity was defined as the percentage reduction in severity scores from baseline to the end of treatment. Patients were also asked about their own opinions of improvement at the end of the treatment. Side effects were also documented. Results: Good to excellent improvement was achieved in up to 50 percent of the patients in the erythematotelangiectatic and papulopustular groups. Percent improvement of global severity was significantly greater in the erythematotelangiectatic patients than in the papulopustular patients. The majority of patients from both groups noted a significant improvement of the lesions. Hypopigmented atrophic scars were seen in two patients. Conclusion: The long-pulsed neodymium-doped yttrium aluminium garnet laser is a safe and effective treatment for vascular and inflammatory lesions of rosacea. PMID:26430486

Picosecond 532-nm neodymium-doped yttrium aluminium garnet laser-a novel and promising modality for the treatment of café-au-lait macules.

PubMed

Artzi, Ofir; Mehrabi, Joseph N; Koren, Amir; Niv, Roni; Lapidoth, Moshe; Levi, Assi

2018-05-01

Café-au-lait macules (CALMs) present as benign hyperpigmented, well-circumscribed spots on the skin for which many patients seek treatment for aesthetic reasons. The objective of this study is to report our experience in treating CALMs using a picosecond 532-nm neodymium-doped yttrium aluminium garnet (PS 532 nm) laser. This is a retrospective case series of 16 patients with CALMs who were treated by a PS 532-nm laser (1-4 treatments, 4-8 weeks apart). Response as seen on clinical photographs was assessed by two independent dermatologists and graded on a scale of 0 (exacerbation) to 5 (95-100% improvement). Patient satisfaction and tolerance were documented at final visit. The results of 15 patients demonstrated significant improvement (average 3.43), and their satisfaction and tolerance levels were high. One patient had no response whatsoever to treatment. The PS 532-nm laser is a promising novel modality for the treatment of CALMs.

Refractory open-angle glaucoma after neodymium-yttrium-aluminum-garnet laser lysis of vitreous floaters.

PubMed

Cowan, Lisa A; Khine, Kay T; Chopra, Vikas; Fazio, Doreen T; Francis, Brian A

2015-01-01

To illustrate 3 cases of chronic open-angle glaucoma secondary to the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser vitreolysis procedure for symptomatic vitreous floaters. Observational case series. Location of the study was the Doheny Eye Institute. Three eyes of 2 patients who developed chronic open-angle glaucoma after Nd:YAG vitreolysis for symptomatic floaters presenting with very high intraocular pressure (IOP >40 mm Hg) were selected. The time from the laser treatment to the onset of elevated pressure ranges from 1 week to 8 months. There was no associated inflammation, steroid use, or other identifiable cause of chronic IOP elevation. All eyes were treated initially with glaucoma medication, followed by selective laser trabeculoplasty (SLT) and eventually glaucoma surgery (Trabectome) in 2 eyes for disease management. In all eyes, intraocular pressures were eventually stabilized within a normal pressure range from 18 to 38 months following Nd:YAG vitreolysis. At the latest follow-up post surgery, all eyes had intraocular pressures of 22 mm Hg or less with or without medications. Secondary open-angle glaucoma is a complication of Nd:YAG vitreolysis for symptomatic floaters that may present with an increase in intraocular pressure immediately, or many months after the surgery. Furthermore this complication may be permanent and require chronic medical therapy or glaucoma surgery. Copyright © 2015 Elsevier Inc. All rights reserved.

Optical Characterizations of Surface Polished Polycrystalline YAG (Yttrium Aluminum Garnet) Fibers (Postprint)

DTIC Science & Technology

2017-06-02

Ho:YAG fiber. 0 0.5 1 1.5 20 0.01 0.02 0.03 0.04 0.05 0.06 Input Power (W) O ut pu t P ow er (W ) Fresnel+Fresnel HR+Fresnel HR+70% R HR+90% R...1 2 3 4 5 6 7 8 9 10 11 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Input Power (W) O ut pu t P ow er (W ) y = 0.07*x - 0.011 50% duty cycle CW linear...1979). [4] Aggarwal, R. L ., Ripin, D. J., Ochoa, J. R. and Fan, T. Y., “Measurement of thermos-optic properties of Y3Al5O12, Lu3Al5O12, YAlO3

Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser.

PubMed

Yu, Haohai; Wang, Shuxian; Han, Shuo; Wu, Kui; Su, Liangbi; Zhang, Huaijin; Wang, Zhengping; Xu, Jun; Wang, Jiyang

2014-03-15

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

Microtensile bond strength of composite resin to human enamel prepared using erbium: Yttrium aluminum garnet laser.

PubMed

Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Palma-Dibb, Regina Guenka

2007-02-01

The Erbium: Yttrium Aluminum Garnet (YAG) laser used for preparation of cavity can alter the substrate and it could influence the bond strength of enamel. The aim of this in vitro study was to evaluate the influence of Er:YAG laser's energy using microtensile bond test. Three groups were obtained (cavity preparation) and each group was divided into two subgroups (adhesive system). After that the adhesive protocol was performed, sections with a cross-sectional area of 0.8 mm2 (+/-0.2 mm2) were obtained. The specimens were mounted in a universal testing machine (0.5 mm/min). Statistical analysis showed a decrease in bond strength for lased groups (p < 0.01) and when the total-etching adhesive system was used the laser 300 mJ subgroup showed higher bond strength compared to the laser 250 mJ (p < 0.01). It was concluded that the cavities prepared using laser appear less receptive to adhesive procedures than conventional bur-cut cavities. Copyright 2006 Wiley Periodicals, Inc.

Advances in bone surgery: the Er:YAG laser in oral surgery and implant dentistry

PubMed Central

Stübinger, Stefan

2010-01-01

The erbium-doped yttrium aluminium garnet (Er:YAG) laser has emerged as a possible alternative to conventional methods of bone ablation because of its wavelength of 2.94 μm, which coincides with the absorption peak of water. Over the last decades in several experimental and clinical studies, the widespread initial assumption that light amplification for stimulated emission of radiation (laser) osteotomy inevitably provokes profound tissue damage and delayed wound healing has been refuted. In addition, the supposed disadvantage of prolonged osteotomy times could be overcome by modern short-pulsed Er:YAG laser systems. Currently, the limiting factors for a routine application of lasers for bone ablation are mainly technical drawbacks such as missing depth control and a difficult and safe guidance of the laser beam. This article gives a short overview of the development process and current possibilities of noncontact Er:YAG laser osteotomy in oral and implant surgery. PMID:23662082

Morphology and magnetic characterisation of aluminium substituted yttrium-iron garnet nanoparticles prepared using sol gel technique.

PubMed

Yahya, Noorhana; Al Habashi, Ramadan Masoud; Koziol, Krzysztof; Borkowski, Rafal Dunin; Akhtar, Majid Niaz; Kashif, Muhammad; Hashim, Mansor

2011-03-01

Aluminum substituted yttrium iron garnet nano particles with compositional variation of Y(3.0-x) A1(x)Fe5O12, where x = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 were prepared using sol gel technique. The X-ray diffraction results showed that the best garnet phase appeared when the sintering temperature was 800 degrees C. Nano-crystalline particles with high purity and sizes ranging from 20 to 100 nm were obtained. It was found that the aluminum substitution had resulted in a sharp fall of the d-spacing when x = 2, which we speculated is due to the preference of the aluminum atoms to the smaller tetrahedron and octahedron sites instead of the much larger dodecahedron site. High resolution transmission electron microscope (HRTEM) and electron diffraction (ED) patterns showed single crystal nanoparticles were obtained from this method. The magnetic measurement gave moderate values of initial permeability; the highest value of 5.3 was shown by sample Y3Fe5O12 at more than 100 MHz which was attributed to the morphology of the microstructure which appeared to be homogeneous. This had resulted in an easy movement of domain walls. The substitution of aluminum for yttrium is speculated to cause a cubic to rhombodedral structural change and had weakened the super-exchange interactions thus a fall of real permeability was observed. This might have created a strain in the sub-lattices and had subsequently caused a shift of resonance frequencies to more than 1.8 GHz when x > 0.5.

Update on lasers in urology 2014: current assessment on holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripter settings and laser fibers.

PubMed

Kronenberg, Peter; Traxer, Olivier

2015-04-01

The purpose of the study was to review the existing literature on holmium:yttrium-aluminum-garnet laser lithotripsy regarding lithotripter settings and laser fibers. An online search of current and past peer-reviewed literature on holmium laser lithotripsy was performed on several databases, including PubMed, SciElo, and Google Scholar. Relevant studies and original articles about lithotripter settings and laser fibers were examined, and the most important information is summarized and presented here. We examine how the choice of lithotripter settings and laser fibers influences the performance of holmium laser lithotripsy. Traditional laser lithotripter settings are analyzed, including pulse energy, pulse frequency, and power levels, as well as newly developed long-pulse modes. The impact of these settings on ablation volume, fragment size, and retropulsion is also examined. Advantages of small- and large-diameter laser fibers are discussed, and controversies are highlighted. Additionally, the influence of the laser fiber is examined, specifically the fiber tip preparation and the lithotripter settings' influence on tip degradation. Many technical factors influence the performance of holmium laser lithotripsy. Knowing and understanding these controllable parameters allows the urologist to perform a laser lithotripsy procedure safely, efficiently, and with few complications.

Gadolinium Scandium Gallium Garnet (GSGG) as a Solid-State Laser Host

DTIC Science & Technology

1987-07-01

o*SATI CODSi1.SBEC EM (otne nrvrs fnceayad dniy nb)k ubr ~~~~~~~~ Gadolinium Scandium Gallium Garnet (GSGG)asaSldtteLerHt 17. ABSTRACT 6.SUJCTTEM...certain other garnet materials for replacement. It also addresses the solid-state laser host material Gadolinium Scandium Gal- lium Garnet (GSGG) and its...by neodymium-doped yttrium aluminum garnet (Nd:YAG) or other mate- rials for most applications. In the years after the invention of the ruby laser, in

Yttrium aluminium garnet under pressure: Structural, elastic, and vibrational properties from ab initio studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Monteseguro, V.; Rodríguez-Hernández, P.; Muñoz, A., E-mail: amunoz@ull.es

The structural, elastic, and vibrational properties of yttrium aluminum garnet Y{sub 3}Al{sub 5}O{sub 12} are studied under high pressure by ab initio calculations in the framework of the density functional theory. The calculated ground state properties are in good agreement with the available experimental data. Pressure dependences of bond length and bulk moduli of the constituent polyhedra are reported. The evolution of the elastic constants and the major elastic properties, Young and shear modulus, Poisson's ratios, and Zener anisotropy ratio, are described. The mechanical stability is analyzed, on the light of “Born generalized stability criteria,” showing that the garnet ismore » mechanically unstable above 116 GPa. Symmetries, frequencies, and pressure coefficients of the Raman-active modes are discussed on the basis of the calculated total and partial phonon density of states, which reflect the dynamical contribution of each atom. The relations between the phonon modes of Y{sub 3}Al{sub 5}O{sub 12} and the internal and external molecular modes of the different polyhedra are discussed. Infrared-active modes, as well as the silent modes, and their pressure dependence are also investigated. No dynamical instabilities were found below 116 GPa.« less

Ce and La single- and double-substitutional defects in yttrium aluminum garnet: first-principles study.

PubMed

Muñoz-García, Ana Belén; Seijo, Luis

2011-02-10

The atomistic structure, energetics, and electronic structure of single-substitutional Ce and La defects and double-substitutional Ce-La defects in Ce,La-codoped yttrium aluminum garnet (YAG) Y(3)Al(5)O(12) have been studied by means of first-principles periodic boundary conditions density functional theory calculations. Single substitution of Y by Ce or by La produces atomistic expansions around the impurities, which are significantly smaller than the ionic radii mismatches and the overall lattice distortions are found to be confined within their second coordination spheres. In double-substitutional defects, the impurities tend to be as close as possible. La-codoping Ce:YAG provokes an anisotropic expansion around Ce defects. The Ce impurity introduces 4f occupied states in the 5.0 eV computed gap of YAG, peaking 0.25 eV above the top of the valence band, and empty 4f, 5d, and 6s states starting at 3.8 eV in the gap and spreading over the conduction band. La-codoping produces very small effects on the electronic structure of Ce:YAG, the most visible one being the decrease in covalent bonding with one of the oxygen atoms, which shifts 0.05 Å away from Ce and gets 0.04 Å closer to La in the most stable Ce-La double-substitutional defect.

Temperature dependence of the 1.06-microm stimulated emission cross section of neodymium in YAG and in GSGG.

PubMed

Rapaport, Alexandra; Zhao, Shengzhi; Xiao, Guohua; Howard, Andrew; Bass, Michael

2002-11-20

A linear temperature dependence between -70 degrees C and +70 degrees C is reported for the peak stimulated emission cross section of Nd3+ ions in both yttrium aluminum garnet (YAG) and gadolinium scandium gallium garnet (GSGG).

Comparison of Micro-Leakage from Resin-Modified Glass Ionomer Restorations in Cavities Prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) Laser and Conventional Method in Primary Teeth

PubMed Central

Bahrololoomi, Zahra; Razavi, Forooghosadat; Soleymani, Ali Asghar

2014-01-01

Introduction: In recent years, significant developments have been taking place in caries removal and cavity preparation using laser in dentistry. As laser use is considered for cavity preparation, it is necessary to determine the quality of restoration margins. Glass ionomer cements have great applications for conservative restoration in the pediatric field. The purpose of this in vitro study was to compare resin-modified glass ionomer restorations micro-leakage in cavities prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) laser irradiation and conventional method in primary teeth. Methods: This was an in vitro experimental study. Forty primary canine teeth were divided into 2 groups: group 1 represented cavities prepared by the no. 008 diamond bur, group 2 represented cavities prepared by Er:YAG laser. After cavity preparation, samples were restored by resin-modified glass ionomer. The teeth were thermocycled for 700 cycles, placed in 2% methylene blue for 24h and sectioned in the buccolingual direction. The degree of dye penetration was scored by 3 examiners. Data was analyzed using Mann-Whitney Test. Results: There was no statistical difference in micro-leakage between the two modes of cavity preparation (P=0.862) Conclusion: Since preparing conservative cavities is very important in pediatric dentistry, it is possible to use Er:YAG laser because of its novel and portable technology. However, further investigations of other restorative materials and other laser powers are required. PMID:25653819

Do We Really Need to Wear Proper Eye Protection When Using Holmium:YAG Laser During Endourologic Procedures? Results from an Ex Vivo Animal Model on Pig Eyes.

PubMed

Villa, Luca; Cloutier, Jonathan; Compérat, Eva; Kronemberg, Peter; Charlotte, Frederic; Berthe, Laurent; Rouchausse, Yann; Salonia, Andrea; Montorsi, Francesco; Traxer, Olivier

2016-03-01

We sought to evaluate the effect of holmium:yttrium-aluminum-garnet (Ho:YAG) laser exposure on ex vivo pig eyes and to test the protective action of different glasses in preventing eye lesions in case of accident. We pointed the tip of a Ho:YAG laser fiber from different distances (0, 3, 5, 8, 10, and 20 cm, respectively) toward the center of the pupil of the pig eye. The Ho:YAG laser was activated for 1 or 5 seconds at three different settings (0.5 J-20 Hz, 1 J-10 Hz, and 2 J-10 Hz, respectively). The experiment was repeated using laser safety glasses and eyeglasses. A total of 78 pig eyes were used. The effects of the Ho:YAG laser on pig eyes were assessed by histopathology. Comparable laser emission experiments were performed on thermal paper at different distances using different pulse energies. Ho:YAG laser-induced corneal lesions were observed in unprotected eyes, ranging from superficial burning lesions to full-thickness necrotic areas, and were directly related to pulse energy and time of exposure and inversely related to the distance from the eye. When the laser was placed 5 cm or more, no corneal damage was observed regardless of the laser setting and the time of exposure. Similar distance/energy level relationships were observed on thermal paper. No damage was observed to the lens or the retina in any of the Ho-YAG laser-treated eyes or in any of the eyes protected by laser safety and eyeglasses. Ho:YAG lasers can cause damage when set to high energy, but only to the cornea, from close distances (0-5 cm) and in the absence of eye protection. Eyeglasses are equally effective in preventing laser damage as laser safety glasses.

Fractional versus ablative erbium:yttrium-aluminum-garnet laser resurfacing for facial rejuvenation: an objective evaluation.

PubMed

El-Domyati, Moetaz; Abd-El-Raheem, Talal; Abdel-Wahab, Hossam; Medhat, Walid; Hosam, Wael; El-Fakahany, Hasan; Al Anwer, Mustafa

2013-01-01

Laser is one of the main tools for skin resurfacing. Erbium:yttrium-aluminum-garnet (Er:YAG) was the second ablative laser, after carbon dioxide, emitting wavelength of 2940 nm. Fractional laser resurfacing has been developed to overcome the drawbacks of ablative lasers. We aimed to objectively evaluate the histopathological and immunohistochemical effects of Er:YAG 2940-nm laser for facial rejuvenation (multiple sessions of fractional vs single session of ablative Er:YAG laser). Facial resurfacing with single-session ablative Er:YAG laser was performed on 6 volunteers. Another 6 were resurfaced using fractional Er:YAG laser (4 sessions). Histopathological (hematoxylin-eosin, orcein, Masson trichrome, and picrosirius red stains) and immunohistochemical assessment for skin biopsy specimens were done before laser resurfacing and after 1 and 6 months. Histometry for epidermal thickness and quantitative assessment for neocollagen formation; collagen I, III, and VII; elastin; and tropoelastin were done for all skin biopsy specimens. Both lasers resulted in increased epidermal thickness. Dermal collagen showed increased neocollagen formation with increased concentration of collagen types I, III, and VII. Dermal elastic tissue studies revealed decreased elastin whereas tropoelastin concentration increased after laser resurfacing. Neither laser showed significant difference between their effects clinically and on dermal collagen. Changes in epidermal thickness, elastin, and tropoelastin were significantly more marked after ablative laser. The small number of patients is a limitation, yet the results show significant improvement. Multiple sessions of fractional laser have comparable effects to a single session of ablative Er:YAG laser on dermal collagen but ablative laser has more effect on elastic tissue and epidermis. Copyright © 2012 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Stone Attenuation Values Measured by Average Hounsfield Units and Stone Volume as Predictors of Total Laser Energy Required During Ureteroscopic Lithotripsy Using Holmium:Yttrium-Aluminum-Garnet Lasers.

PubMed

Ofude, Mitsuo; Shima, Takashi; Yotsuyanagi, Satoshi; Ikeda, Daisuke

2017-04-01

To evaluate the predictors of the total laser energy (TLE) required during ureteroscopic lithotripsy (URS) using the holmium:yttrium-aluminum-garnet (Ho:YAG) laser for a single ureteral stone. We retrospectively analyzed the data of 93 URS procedures performed for a single ureteral stone in our institution from November 2011 to September 2015. We evaluated the association between TLE and preoperative clinical data, such as age, sex, body mass index, and noncontrast computed tomographic findings, including stone laterality, location, maximum diameter, volume, stone attenuation values measured using average Hounsfield units (HUs), and presence of secondary signs (severe hydronephrosis, tissue rim sign, and perinephric stranding). The mean maximum stone diameter, volume, and average HUs were 9.2 ± 3.8 mm, 283.2 ± 341.4 mm 3 , and 863 ± 297, respectively. The mean TLE and operative time were 2.93 ± 3.27 kJ and 59.1 ± 28.1 minutes, respectively. Maximum stone diameter, volume, average HUs, severe hydronephrosis, and tissue rim sign were significantly correlated with TLE (Spearman's rho analysis). Stepwise multiple linear regression analysis defining stone volume, average HUs, severe hydronephrosis, and tissue rim sign as explanatory variables showed that stone volume and average HUs were significant predictors of TLE (standardized coefficients of 0.565 and 0.320, respectively; adjusted R 2  = 0.55, F = 54.7, P <.001). Stone attenuation values measured by average HUs and stone volume were strong predictors of TLE during URS using Ho:YAG laser procedures. Copyright © 2016 Elsevier Inc. All rights reserved.

Chromium Recharging Processes in the Y3Al5O12: Mg, Cr Single Crystal under the Reducing and Oxidizing Annealing Influence

DTIC Science & Technology

2001-01-01

approximately 0.2% of total number of chromium ions occupied tetrahedral sites forming phototropic centers in the YAG: Mg, Cr crystal. Keywords: yttrium...aluminium garnet, Cr doping, thermal treatment, phototropic centers, optical characterization, electron paramagnetic resonance. 1. INTRODUCTION An...of garnet structure while the main part of chromium occupies octahedral sites in three-valence state. 10-12 The dependence of amount of phototropic

Lack of adjunctive benefit of Er:YAG laser in non-surgical periodontal treatment: a randomized split-mouth clinical trial.

PubMed

Rotundo, Roberto; Nieri, Michele; Cairo, Francesco; Franceschi, Debora; Mervelt, Jana; Bonaccini, Daniele; Esposito, Marco; Pini-Prato, Giovanpaolo

2010-06-01

This split-mouth, randomized, clinical trial aimed to evaluate the efficacy of erbium-doped:yttrium-aluminium-garnet (Er:YAG) laser application in non-surgical periodontal treatment. A total of 27 patients underwent four modalities of non-surgical therapy: supragingival debridement; scaling and root planing (SRP)+Er:YAG laser; Er:YAG laser; and SRP. Each strategy was randomly assigned and performed in one of the four quadrants. Clinical outcomes were evaluated at 3 and 6 months. Subjective benefits of patients have been evaluated by means of questionnaires. Six months after therapy, Er:YAG laser showed no statistical difference in clinical attachment gain with respect to supragingival scaling [0.15 mm (95% CI -0.16; 0.46)], while SRP showed a greater attachment gain than the supragingival scaling [0.37 mm (95% CI 0.05; 0.68)]. No difference resulted between Er:YAG laser+SRP and SRP alone [0.05 mm (95% CI -0.25; 0.36)]. The adjunctive use of Er:YAG laser to conventional SRP did not reveal a more effective result than SRP alone. Furthermore, the sites treated with Er:YAG laser showed similar results of the sites treated with supragingival scaling.

Erbium:Yttrium Aluminum Garnet Laser-Activated Sodium Hypochlorite Irrigation: A Promising Procedure for Minimally Invasive Endodontics.

PubMed

Cheng, Xiaogang; Tian, Tiantian; Tian, Yu; Xiang, Doudou; Qiu, Jun; Liu, Xiaohua; Yu, Qing

2017-12-01

This study was to evaluate the potential of Erbium:Yttrium Aluminum Garnet laser-activated sodium hypochlorite irrigation (Er:YAG + NaOCl) for minimally invasive endodontics (MIE). Er:YAG laser irradiation can dramatically enhance the penetration of NaOCl, which may be a promising protocol for MIE. Extracted human teeth were contaminated with Enterococcus faecalis for 4 weeks. The infected canals were then shaped to different apical terminal working widths (ATWW, 15#/0.04, 20#/0.04, 25#/0.04, 30#/0.04, and 40#/0.04) and treated with either Er:YAG + NaOCl (0.3 W, 20 sec) or NaOCl alone. Then, the ATWW were fixed at 15#/0.04, and the canals were treated with Er:YAG + NaOCl at 0.3 W for 40 and 60 sec, or at 0.5 and 1.0 W for 20 sec. Finally, bacterial reductions were evaluated using the cell count method. Er:YAG + NaOCl showed a higher disinfection efficacy at each ATWW compared with NaOCl alone (p < 0.001). The maximum bacterial reduction was 99.9% for the 40#/Er:YAG + NaOCl group and 93.6% for the 40#/NaOCl group. To achieve similar disinfection efficacy, the Er:YAG + NaOCl group needed a smaller ATWW than the NaOCl group. At a fixed ATWW, increasing the output power of the Er:YAG laser was more effective than increasing the radiation time to improve the disinfection efficacy of Er:YAG + NaOCl. The 15#/Er:YAG + NaOCl group reached the maximum bacterial reduction of 99.2% when the Er:YAG laser was activated at 1.0 W for 20 sec. The 15#/Er:YAG + NaOCl with the Er:YAG laser irradiation at 1.0 W for 20 sec may be considered a promising procedure for MIE.

Dense nanocrystalline yttrium iron garnet films formed at room temperature by aerosol deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Scooter D., E-mail: scooter.johnson@nrl.navy.mil; Glaser, Evan R.; Cheng, Shu-Fan

Highlights: • We deposit yttrium iron garnet films at room temperature using aerosol deposition. • Films are 96% of theoretical density for yttrium iron garnet. • We report magnetic and structural properties post-deposition and post-annealing. • Low-temperature annealing decreases the FMR linewidth. • We discuss features of the FMR spectra at each anneal temperature. - Abstract: We have employed aerosol deposition to form polycrystalline yttrium iron garnet (YIG) films on sapphire at room temperature that are 90–96% dense. We characterize the structural and dynamic magnetic properties of the dense films using scanning electron microscopy, X-ray diffraction, and ferromagnetic resonance techniques.more » We find that the as-deposited films are pure single-phase YIG formed of compact polycrystallites ∼20 nm in size. The ferromagnetic resonance mode occurs at 2829 G with a linewidth of 308 G. We perform a series of successive anneals up to 1000 °C on a film to explore heat treatment on the ferromagnetic resonance linewidth. We find the narrowest linewidth of 98 G occurs after a 750 °C anneal.« less

A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel.

PubMed

Cernavin, I

1995-04-01

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 microns, energy density 4160 J/cm2) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 microns), energy density 50,000 J/cm2), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.

Injection-seeded operation of a Q-switched Cr,Tm,Ho:YAG laser

NASA Technical Reports Server (NTRS)

Henderson, Sammy W.; Hale, Charley P.; Magee, James R.

1991-01-01

Single-frequency Tm,Ho:YAG lasers operating near 2 microns are attractive sources for several applications including eye-safe laser radar (lidar) and pumping of AgGaSe2 parametric oscillators for efficient generation of longer wavelengths. As part of a program to develop a coherent lidar system using Tm,Ho:YAG lasers, a diode laser-pumped tunable CW single-longitudinal-mode (SLM) Cr:Tm:Ho:YAG laser and a flashlamp-pumped single-transverse-mode Q-switched Cr,Tm,Ho:YAG laser were developed. The CW laser was used to injection-seed the flashlamp-pumped laser, resulting in SLM Q-switched output. Operational characteristics of the CW and Q-switched lasers and injection-seeding results are reported.

Effect of neodymium:yttrium-aluminum-garnet laser and fluoride on the acid demineralization of enamel.

PubMed

Braga, Sheila Regina Maia; de Oliveira, Elisabeth; Sobral, Maria Angela Pita

2017-02-01

The aim of the present study was to evaluate the protective effect of the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser and acidic phosphate fluoride (APF) on enamel erosion caused by hydrochloric acid. Fifty human enamel specimens were distributed according to the following treatments (n = 10): untreated (control), APF (1.23%) 4 min, Nd:YAG laser (100 mJ, 1 W, 10 Hz, 141.5 J/cm 2 ), APF + Nd:YAG laser, and Nd:YAG laser + APF. For 14 days the specimens were submitted to erosive challenge: 5 min in 3 mL hydrochloric acid (0.01 M, pH 2.2), rinsed with distilled water, and stored in artificial saliva for 3 h. This cycle was repeated four times per day. The calcium (Ca) loss was determined in demineralizing solution by atomic emission spectroscopy, and superficial roughness (Ra) was measured before and after the erosive challenge. The mean Ca loss was (mg/L, ± standard deviation): control 12.74 ± 3.33, APF 1.71 ± 0.11, laser 1.64 ± 0.08, APF + laser 1.38 ± 0.08, and laser + APF 1.48 ± 0.07. Kruskal-Wallis test showed a significant difference between the control and other groups. APF + laser showed minor loss of Ca. After the erosive challenge, the APF + laser group showed Ra alteration. A significant reduction in tooth dissolution was observed after fluoride application combined with Nd:YAG irradiation. © 2015 Wiley Publishing Asia Pty Ltd.

Optical Properties of Nd Doped Rare Earth Vanadates (Preprint)

DTIC Science & Technology

2010-07-01

Rare earth orthovanadates are being used as substitute for traditional solid state laser hosts such as yttrium aluminium garnet (YAG). While the most...common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and gadolinium vanadate are being used for their... gadolinium vanadate are being used for their special properties in certain applications. We report new measurements of the refractive indices and thermo

Internal photopumping of Nd3+ (2H9/2, 4F5/2) states in yttrium aluminum garnet by excitation transfer from oxygen deficiency centers and Fe3+ continuum emission

NASA Astrophysics Data System (ADS)

Hewitt, J. D.; Spinka, T. M.; Senin, A. A.; Eden, J. G.

2011-07-01

Photoexcitation of Nd3+ (2H9/2, 4F5/2) states by the broad (˜70 nm FWHM), near-infrared continuum provided by Fe3+ has been observed at 300 K in bulk yttrium aluminum garnet (YAG) crystals doped with trace concentrations (<50 ppm) of Fe, Cr, and Eu. Irradiation of YAG at 248 nm with a KrF laser, which excites the oxygen deficiency center (ODC) in YAG having peak absorption at ˜240 nm, culminates in ODC→Fe3+ excitation transfer and subsequent Fe3+ emission. This internal optical pumping mechanism for rare earth ions is unencumbered by the requirement for donor-acceptor proximity that constrains conventional Förster-Dexter excitation transfer in co-doped crystals.

Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

PubMed

Maeda, Y

1994-01-10

Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

Fractional erbium-doped yttrium aluminum garnet laser-assisted drug delivery of hydroquinone in the treatment of melasma

PubMed Central

Badawi, Ashraf M; Osman, Mai Abdelraouf

2018-01-01

Background Melasma is a difficult-to-treat hyperpigmentary disorder. Ablative fractional laser (AFL)-assisted delivery of topically applied drugs to varied targets in the skin has been an area of ongoing study and research. Objective The objective of this study was to evaluate the efficacy and safety of fractional erbium-doped yttrium aluminum garnet (Er:YAG) laser as an assisted drug delivery for enhancing topical hydroquinone (HQ) permeation into the skin of melasma patients. Patients and methods Thirty female patients with bilateral melasma were randomly treated in a split-face controlled manner with a fractional Er:YAG laser followed by 4% HQ cream on one side and 4% HQ cream alone on the other side. All patients received six laser sessions with a 2-week interval. The efficacy of treatments was determined through photographs, dermoscopic photomicrographs and Melasma Area Severity Index (MASI) score, all performed at baseline and at 12 weeks of starting therapy. The patient’s level of satisfaction was also recorded. Results Er:YAG laser + HQ showed significantly better results (p<0.005) with regard to decrease in the degree of pigmentation as assessed on the 4-point scale than HQ alone. There was a significant decrease in MASI scores on Er:YAG laser + HQ side vs HQ side. Minor reversible side effects were observed on both sides. Conclusion AFL-assisted delivery of HQ is a safe and effective method for the treatment of melasma. PMID:29379308

Critical review of lasers in benign prostatic hyperplasia (BPH).

PubMed

Gravas, Stavros; Bachmann, Alexander; Reich, Oliver; Roehrborn, Claus G; Gilling, Peter J; De La Rosette, Jean

2011-04-01

• Laser treatment of benign prostatic hyperplasia has challenged transurethral resection of the prostate (TURP) due to advances in laser technology, better understanding of tissue-laser interactions and growing clinical experience. • Various lasers have been introduced including neodymium: yttrium aluminium garnet (YAG), holmium (Ho):YAG, potassium titanyl phosphate:YAG, thulium(Tm) and diode laser. Based on the different wave-length dependent laser-prostatic tissue interactions, the main techniques are coagulation, vaporization, resection and enucleation. • The present review aims to help urologists to distinguish and to critically evaluate the role of different laser methods in the treatment by using an evidence-based approach. It also details further evidence for use in specific patient groups (in retention, on anticoagulation) and addresses the issues of cost and learning curve. • Coagulation-based techniques have been abandoned; holmium ablation/resection of the prostate has been superseded by the enucleation technique Ho-laser enucleation of the prostate (HoLEP). The short-term efficacy of the emerging laser treatments such as diode and Tm prostatectomy has been suggested by low quality studies. HoLEP and photoselective vaporization of the prostate (PVP) represent valid clinical alternatives to TURP. HoLEP is the most rigorously analysed laser technique with durable efficacy for any prostate size and low early and late morbidity. PVP has grown in acceptance and popularity but long-term results from high quality studies are pending. © 2010 THE AUTHORS; BJU INTERNATIONAL © 2010 BJU INTERNATIONAL.

Does ErbiumiYttrium-Aluminum-Garnet Laser to Enamel improve the Performance of Etch-and-rinse and Universal Adhesives?

PubMed

De Jesus Tavarez, Rudys R; Rodrigues, Lorrany Lc; Diniz, Ana C; Lage, Lucas M; Torres, Carlos Rg; Bandeca, Matheus C; Firoozmand, Leily M

2018-03-01

This study aims to evaluate the effect of erbium: Yttrium-aluminum-garnet (Er:YAG) laser irradiation on the enamel microshear bond strength (μSBS), followed by the utilization of etch-and-rinse and universal adhesive systems. A total of 32 molars were sectioned in the mesiodistal direction producing 64 samples that were randomized into two groups (n = 32): single bond 2 (SB2) (etch-and-rinse system; 3M), SB universal (SBU) (universal etching system; The SB2 and SBU groups were then divided into two subgroups (n = 16): (i) enamel was irradiated with an Er:YAG laser (λ = 2.94 μm, 60 mJ, 10 Hz), and (ii) enamel served as a control. The samples were restored with TPH3 (Dentsply), stored in artificial saliva for 24 hours, and subjected to a micro-shear test. Kruskal-Wallis (p < 0.05) and Mann-Whitney U tests indicated no significant differences in uSBS between the groups, and the fractures were predominately at the resin-enamel interface. The previous irradiation of enamel with Er:YAG laser does not interfere with the performance of simplified two-step etch-and-rinse and universal adhesive systems. The increasing use of Er:YAG laser is important to evaluate the influence of this irradiation on the adhesion of restorative materials. Thus, to obtain the longevity of the restorative procedures, it is necessary to know the result of the association of the present adhesive systems to the irradiated substrate.

Processing and characterization of polycrystalline YAG (Yttrium Aluminum Garnet) core-clad fibers

NASA Astrophysics Data System (ADS)

Kim, Hyun Jun; Fair, Geoff E.; Potticary, Santeri A.; O'Malley, Matthew J.; Usechak, Nicholas G.

2014-06-01

Polycrystalline YAG fiber has recently attracted considerable attention for the role it could play as a fiber-laser gain media. This primarily due to its large surface-to-volume ratio, high stimulated Brillouin scattering threshold, and its high thermal conductivity; all of which are superior to that of silica-glass fibers. As a consequence, techniques which enable the fabrication of poly- and single-crystalline YAG fibers have recently been the focus of a number of efforts. In this work we have endeavored to reduce the scattering loss of polycrystalline-YAG-core fibers while simultaneously demonstrating optical gain by enhancing our processing techniques using feedback from mechanical testing and through the development of a technique to encase doped YAG-core fibers with un-doped YAG claddings. To this end we have recently fabricated fibers with both core and claddings made up of polycrystalline YAG and subsequently confirmed that they indeed guide light. In this paper, the processes leading to the fabrication of these fibers will be discussed along with their characterization.

Aging Effects on the Structural and Magnetic Properties of Terbium-Aluminium Co-doping of Yttrium Iron Garnet Films Prepared Using the Sol-Gel Method

NASA Astrophysics Data System (ADS)

Aldbea, Ftema W.; Yusrianto, Efil; Ibrahim, N. B.

2018-06-01

The terbium-aluminium co-doped yttrium iron garnet (Tb0.2Y2.8Al1Fe4O12) nanoparticles films, prepared via a sol-gel method, were aged variously for 2 days, 3 days, 4 days and 5 days. The films were deposited on quartz substrates using a spin coating technique then annealed at 900°C in air for 2 h. The microstructural and magnetic properties of the films were measured using an x-ray diffractometer (XRD), a field emission scanning electron microscope and a vibrating sample magnetometer. The XRD results showed that all the resultant films were a single phase regardless of aging time. A change in the lattice parameter's behavior was observed at the longer aging times. At an aging time of 5 days, the films became highly agglomerated and exhibited the greatest thickness value of 458.9 nm. The saturation magnetization, M s, of the films decreased from 31 kA/m to 6 kA/m as the aging time was increased from 2 days to 5 days, due to the increasing Fe-O bond length resulting from larger grain sizes. The increase in aging time to 5 days caused a reduction in the coercivity, H c, of films due to the multi-domain formation.

Environmentally benign processing of YAG transparent wafers

NASA Astrophysics Data System (ADS)

Yang, Yan; Wu, Yiquan

2015-12-01

Transparent yttrium aluminum garnet (YAG) wafers were successfully produced via aqueous tape casting and vacuum sintering techniques using a new environmentally friendly binder, a copolymer of isobutylene and maleic anhydride with the commercial name ISOBAM (noted as ISOBAM). Aqueous YAG slurries were mixed by ball-milling, which was followed by de-gassing and tape casting of wafers. The final YAG green tapes were homogenous and flexible, and could be bent freely without cracking. After the drying and sintering processes, transparent YAG wafers were achieved. The microstructures of both the green tape and vacuum-sintered YAG ceramic were observed by scanning electronic microscopy (SEM). Phase compositions were examined by X-ray diffraction (XRD). Optical transmittance was measured in UV-VIS regions with the result that the transmittance is 82.6% at a wavelength of 800 nm.

Adverse events resulting from lasers used in urology.

PubMed

Althunayan, Abdulaziz M; Elkoushy, Mohamed A; Elhilali, Mostafa M; Andonian, Sero

2014-02-01

To collate world reports of adverse events (AEs) resulting from lasers used in urology. The Manufacturer and User Facility Device Experience (MAUDE) database of the United States Food and Drug Administration (FDA) was searched using the term "Laser for gastro-urology use." In addition, the Rockwell Laser Industries (RLI) Laser Accident Database was searched for the following types of lasers: neodymium-doped yttrium aluminum garnet (Nd:YAG), holmium:yttrium aluminum garnet (Ho:YAG), potassium titanyl phosphate (KTP), diode and thulium:YAG (Tm:YAG). Both databases were last accessed on October 1, 2012. Overall, there were 433 AEs; 166 in MAUDE database (1992-2012) and 267 in RLI database (1964-2005). Most of the AEs (198/433 or 46%) resulted from generator failure or fiber tip breaking. Whereas there were 20 (4.6%) AEs harming medical operators, there were 159 (37%) AEs harming nonmedical operators using Nd:YAG, KTP, and diode lasers. Eye injuries ranging from mild corneal abrasions to total vision loss were reported in 164 AEs with the use of Nd:YAG, KTP, and diode lasers. Overall, there were 36 (8.3%) AEs resulting in patient harm, including 7 (1.6%) mortalities, 3 deaths from ureteral perforation using the Ho:YAG laser, and 4 deaths from air emboli using the Nd:YAG laser. Other reported patient injuries included bladder perforation resulting in urinary diversion in a patient, in addition to minor skin burns, internal burns, and bleeding in others. There were no AEs reported with the use of Tm:YAG laser. Most of the AEs reported relate to equipment failure. There were no eye injuries reported with the use of Ho:YAG lasers. Caution must be exercised when using lasers in urology, including wearing appropriate eye protection when using Nd:YAG, KTP, and diode lasers.

Treatment of café-au-lait macules with a high-fluenced 1064-nm Q-switched neodymium:yttrium aluminum garnet laser.

PubMed

Kim, Jiehoon; Hur, Hoon; Kim, Yu Ri; Cho, Sung Bin

2018-02-01

Café-au-lait macules (CALMs) are light to dark brown macules or patches of increased melanin concentration found along the dermoepidermal junction. Although many attempts to treat CALMs using various kinds of laser/light-based devices have been reported, CALMs remain refractory thereto with high recurrence rates. In this case series, we describe four patients with idiopathic CALMs that were effectively and safely treated with a non-ablative, high-fluenced, Q-switched (QS), 1064-nm neodymium:yttrium aluminum garnet (Nd:YAG) laser. The typical laser parameters for treating CALMs, including a spot size of 7-7.5 mm, a fluence of 2.4-2.5 J/cm 2 , and one to two passes until the appearance of mild erythema, but not petechiae, were utilized in this study over 12-24 treatment sessions at 2-week intervals. We suggest that high-fluenced QS 1064-nm Nd:YAG laser treatment can be used as an effective and alternative treatment modality for CALMs with minimal risk of side effects.

Magnetocrystalline anisotropy of Fe2 + ion in silicon- or germanium-substituted yttrium iron garnet at zero temperature

NASA Astrophysics Data System (ADS)

Rudowicz, Czeslaw

1982-01-01

The present work reports the theoretical considerations of the magnetocrystalline anisotropy of ferrous ions induced by tetravalent dopants in yttrium iron garnet. Using the spin Hamiltonian developed earlier by us and the molecular field (h) approximation we derive the cubic anisotropy constants K1 and K2 at zero temperature. We adopt the Alben's et al. model of twelve inequivalent Fe2+ sites in silicon-substituted yttrium iron garnet. Results are given for h = 400, 300, 200 and the spin Hamiltonian parameters with the trigonal Δ = 300, 400, 500, 600, 700 and the nontrigonal crystal field parameter Γ = 200, 300 cm-1. The agreement with the experimental K1 and K2 is quite good. The discussion reveals that the properties of the far and near sites in the two-center model can now be theoretically explained. The theoretical ratios of K1(far) to K1(near) agree well with experiment. Thus our results speak in favor of the orbital singlet rather than the doublet model assumed previously for Fe2+ in silicon- or germanium-substituted yttrium iron garnets.

Experimental application of pulsed Ho:YAG laser-induced liquid jet as a novel rigid neuroendoscopic dissection device.

PubMed

Ohki, Tomohiro; Nakagawa, Atsuhiro; Hirano, Takayuki; Hashimoto, Tokitada; Menezes, Viren; Jokura, Hidefumi; Uenohara, Hiroshi; Sato, Yasuhiko; Saito, Tsutomu; Shirane, Reizo; Tominaga, Teiji; Takayama, Kazuyoshi

2004-01-01

Although water jet technology has been considered as a feasible neuroendoscopic dissection methodology because of its ability to perform selective tissue dissection without thermal damage, problems associated with continuous use of water and the ensuing fountain-effect-with catapulting of the tissue-could make water jets unsuitable for endoscopic use, in terms of safety and ease of handling. Therefore, the authors experimented with minimization of water usage during the application of a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ), while assuring the dissection quality and the controllability of a conventional water jet dissection device. We have developed the LILJ generator for use as a rigid neuroendoscope, discerned its mechanical behavior, and evaluated its dissection ability using the cadaveric rabbit ventricular wall. The LILJ generator is incorporated into the tip of a stainless steel tube (length: 22 cm; internal diameter: 1.0 mm; external diameter: 1.4 mm), so that the device can be inserted into a commercial, rigid neuroendoscope. Briefly, the LILJ is generated by irradiating an internally supplied water column within the stainless steel tube using the pulsed Ho:YAG laser (wave length: 2.1 microm, pulse duration time: 350 microseconds) and is then ejected through the metal nozzle (internal diameter: 100 microm). The Ho:YAG laser pulse energy is conveyed through optical quartz fiber (core diameter: 400 microm), while cold water (5 degrees C) is internally supplied at a rate of 40 ml/hour. The relationship between laser energy (range: 40-433 mJ/pulse), standoff distance (defined as the distance between the tip of the optical fiber and the nozzle end; range: 10-30 mm), and the velocity, shape, pressure, and average volume of the ejected jet were analyzed by means of high-speed camera, PVDF needle hydrophone, and digital scale. The quality of the dissection plane, the preservation of blood vessels, and the penetration depth

A Comparative Histological Study of Bone Healing in Rat Calvarial Defect Using the Erbium-Doped Yttrium Aluminum Garnet Laser and Rotary Instruments

NASA Astrophysics Data System (ADS)

Jung, Mi-Kyung; Kim, Su-Gwan; Oh, Ji-Su; Jin, Seung-Chan; Lee, Sook-Young; Jang, Eun-Sook; Piao, Zheng-Gang; Lim, Sung-Chul; Jeong, Mi-Ae

2012-01-01

Erbium-doped yttrium aluminum garnet (Er:YAG) lasers have been used in dentistry for cutting bone and removal of caries. The purpose of this study was to evaluate the bone healing in a skull defect prepared in rats using various instruments including Er:YAG laser. The 7 mm calvarial defects were created in 45 rats and 45 rats were divided into three groups (n = 15): a high-speed rotation engine with carbide round bur (2-mm diameter), a low-speed rotation engine with carbide round bur (2-mm diameter), and an Er:YAG laser. Specimens obtained after 3 days or 4 or 8 weeks were submitted for histological analysis. Three days after surgery, no bone formation had occurred in any of the groups. Four weeks after surgery, 90 ±8.16% new bone formation was observed in the high-speed group, and 8 weeks after surgery, 100 ±0% new bone formation was observed in the low- and high-speed groups. There were significant differences among the periods after surgery, but no significant differences were observed among final results with in different device groups.

Optimization of Sm3+ fluorescence in Sm-doped yttrium aluminum garnet: Application to pressure calibration in diamond-anvil cell at high temperature

NASA Astrophysics Data System (ADS)

Sanchez-Valle, Carmen; Daniel, Isabelle; Reynard, Bruno; Abraham, Robert; Goutaudier, Christelle

2002-10-01

Sm3+ concentration in Sm-doped yttrium aluminum garnet (Sm3+):YAG has been optimized for fluorescence yield and synthesis procedure for the production of strain-free small grain-size powder established. Concentration of 0.5 wt % Sm3+ displays an optimal fluorescence signal, three to five times stronger than the generally proposed concentration (4 wt %). The fluorescence of the samples has been studied as a function of temperature (300-873 K) and pressure (0-15 GPa). A comparison with standard pressure scales shows that the pressure evolution of Sm3+:YAG fluorescence is insensitive to the doping rate, and that temperature has only a limited effect on the pressure scale established at 300 K. The present results indicate that pressure can be determined from the Y1 line of 0.5 wt % Sm-doped YAG, with temperature correction for pi at room pressure and constant pressure shift, within the 300-873 K and 10-4-15 GPa pressure-temperature range, through the linear relation: P (GPa)=0.127 x([pi0-0.018 xDelta]T)-[pi] where pi0 corresponds to the Y1 frequency value at ambient conditions (16 185 cm-1).

Directly diode-pumped high-energy Ho:YAG oscillator.

PubMed

Lamrini, Samir; Koopmann, Philipp; Schäfer, Michael; Scholle, Karsten; Fuhrberg, Peter

2012-02-15

We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Q-switched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a wavelength of 2.09 μm were obtained. The corresponding pulse duration at the highest pump power was 100 ns, leading to a maximum peak power above 300 kW. Different pulse repetition rates and output coupling transmissions of the Ho:YAG resonator were studied. In addition, intracavity laser-induced damage threshold measurements are discussed.

Beneficial Effect of Low Fluence 1,064 nm Q-Switched Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Senile Lentigo

PubMed Central

Nam, Jae-Hui; Kim, Han-Saem; Lee, Ga-Young

2017-01-01

Background Low fluence 1,064 nm Q-switched (QS) Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser treatment, also known as laser toning, is widely used for pigmentary disorders. There has been no reliable evaluation of the effect of low fluence 1,064 nm QS Nd:YAG laser for senile lentigo. Objective To investigate the beneficial effect of low fluence 1,064 nm QS Nd:YAG laser in the treatment of senile lentigo on the face. Methods A retrospective review was conducted on patients treated only with repetitive low fluence 1,064 nm QS Nd:YAG laser. Among them, 12 patients with multiple senile lentigines before treatment were included. All side effects were recorded to assess the safety of the modality. Results Mean age was 56.1±7.8 years old and male-to-female ratio was 1:11. Mean treatment fluence was 1.62±0.16 J/cm2 and mean total treatment session was 8.8±2.6. Mean interval period between each session was 28.0±11.4 days and mean treatment session to reach marked and near total improvement was 8.7±2.8. At the final visit, seven of 12 (58.3%) patients reached marked and near total improvement, and three of 12 (25.0%) reached moderate improvement. No side effects occurred. Conclusion Repetitive low fluence 1,064 nm QS Nd:YAG laser treatment may be an effective and safe optional modality for senile lentigo. PMID:28761290

Quantification of holmium:YAG optical tip degradation

NASA Astrophysics Data System (ADS)

Mues, Adam C.; Teichman, Joel M. H.; Knudsen, Bodo E.

2009-02-01

The holmium:yttrium aluminum garnet (YAG) laser is the gold standard laser for intracorporeal lithotripsy. Optical fibers are utilized to transmit laser energy to the surface of a stone for fragmentation. During lithotripsy, fiber tip degradation (burn back) can occur. The exact mechanism for tip degradation and related factors are not completely understood, and have not been investigated. This characteristic is important because fiber burn back may affect diminish fragmentation efficiency, increase operative time, and increase cost due to the need for fiber replacement. We hypothesize that fiber tip degradation (burn back) varies amongst different commercially available holmium:YAG laser fibers.

Dispersion characteristic of photoluminescence decay times of phosphor YAG: Ce, Gd

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Ju, Yangyang; Stepanov, S. A.; Soschin, N. M.

2017-05-01

The dispersion of the characteristic decay times of gadolinium co-doped yttrium aluminum garnet doped with cerium phosphors were studied. In the present work, an ultraviolet semiconductor laser (λem=375 nm, τ = 1 ns) was used as excitation source for measuring kinetics characteristics of phosphor groups based on YAG with different content of cerium.

High-spin europium and gadolinium centers in yttrium-aluminum garnet

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Potapov, A. P.; Asatryan, G. R.; Uspenskaya, Yu. A.; Petrosyan, A. G.; Fokin, A. V.

2016-08-01

Electron-spin resonance spectra of Eu2+ and Gd3+ centers substituting Y3+ ions in single-crystal yttrium-aluminum garnet have been studied and the parameters of their rhombic spin Hamiltonian have been determined. The fine-structure parameters of the above ions have been calculated in the superposition model disregarding changes in the angular coordinates of the ligand environment of the impurity defect thus demonstrating the necessity of taking these changes into account.

Neodymium-yttrium aluminum garnet laser versus pulsed dye laser in erythemato-telangiectatic rosacea: comparison of clinical efficacy and effect on cutaneous substance (P) expression.

PubMed

Salem, Samar Abdallah M; Abdel Fattah, Nermeen S A; Tantawy, Samah M A; El-Badawy, Nafissa M A; Abd El-Aziz, Yasser A

2013-09-01

Different laser systems are reported to be effective in treatment of telangiectasia and erythema, but comparative studies on 1064-nm neodymium-yttrium aluminum garnet (Nd-YAG) laser and pulsed dye laser (PDL) in treatment of erythemato-telangiectatic rosacea are lacking. Substance (P) is implicated in rosacea pathogenesis. To compare the effect of Nd-YAG laser and PDL on erythemato-telangiectatic rosacea, both clinically and immunohistochemically on cutaneous substance (P) expression. This split-face comparative study included 15 patients with erythemato-telangiectatic rosacea treated on the right side with Nd-YAG laser and on the left side with PDL: three sessions, 4 weeks apart. Evaluation of the patients was done using erythema and telangiectasia grading scores, patient's self-assessment, physicians' clinical assessment of the patient, and immunohistochemical assessment of substance (P). One month after the three laser sessions, excellent response was achieved in 73.3% of patients after Nd-YAG and in 53.3% of patients after PDL with significantly lower substance (P) concentration after Nd-YAG laser than after PDL. Positive correlations were found between the decrease in erythema and telangiectasia grading scores and the decrease in substance (P) concentration. The use of Nd-YAG laser and PDL appears to be safe and effective measures in treatment of erythemato-telangiectatic rosacea. Both types of laser decrease the concentration of substance (P) in the skin. This effect is more pronounced with Nd-YAG laser. © 2013 Wiley Periodicals, Inc.

The possibility of clinical application of the solid state lasers: Nd:YAG, Ho:YAG, and Er:YAG in otolaryngology - head and neck surgery

NASA Astrophysics Data System (ADS)

Tomaszewska, M.; Kukwa, A.; Tulibacki, M.; Wójtowicz, P.; Olędzka, I.; Jeżewska, E.

2007-02-01

The purpose of this study was to summarize our experiences in clinical application of Nd:YAG, Ho:YAG and Er:YAG in otolaryngology- head and neck surgery. Choosing the laser type and parameters for the particular procedures was based on our previous research on tissue effects of those lasers. During the period of 1993-2006 we performed 3988 surgical procedures with the Nd:YAG laser. Over 87% of those were made for the nasal cavity pathologies as polyps, hyperplasia of inferior nasal turbinate, granulation tissue, postoperative adhesions, vascular malformations, under the local anesthesia conditions. In our experience Nd:YAG laser gives the possibility of good clinical control and low risk of side effects for disorders of high recurrence and frequent interventions necessity, as nasal polyps or respiratory papillomatosis. Nd:YAG assisted uvulopalatoplasty gives an interesting alternative for surgical procedures for snoring and slight/mild OSA-recognized patients. Due to its good hemostatic properties, it is a perfect tool for removal of the chemodectoma from meddle ear. During the period of 1995-2006 we performed 229 surgical procedures with the Ho:YAG laser, mostly for larynx pathologies (adhesion and scar tissue removal). In our experience Ho:YAG laser can serve as a precise laser knife for both soft and bony tissue. The ER:YAG laser still remain under clinical trial. Since 2001 year we performed 24 procedures of removing stone deposits from salivary glands. We believe it may become a promising method to cope with sialolithiasis which allows for glandule function preservation. All of the laser types mentioned above, can be easily coupled with endoscopes, what makes them available for all of the head and necklocalized disorders.

Comparative study of optical and scintillation properties of Tm3+:YAG, and Tm3+:LuAG single crystals

NASA Astrophysics Data System (ADS)

Fujimoto, Yutaka; Sugiyama, Makoto; Yanagida, Takayuki; Wakahara, Shingo; Suzuki, Shotaro; Kurosawa, Shunsuke; Chani, Valery; Yoshikawa, Akira

2013-09-01

The optical and scintillation properties of Tm3+-doped yttrium aluminum garnet Y3Al5O12 (YAG) and Tm3+-doped lutetium aluminum garnet Lu3Al5O12 (LuAG) are compared. The Tm3+-doped single crystals were grown by the micro-pulling down (μ-PD) technique. Both crystals demonstrated some emission peaks originated from 4f-4f forbidden transition of Tm3+ under 241Am alpha-ray excitation. The scintillation decay time of Tm3+-doped YAG was similar to that of LuAG. When irradiated by the gamma-rays from a 137Cs source, the relative scintillation light yields of Tm:YAG was 90% greater than that of Tm:LuAG.

Scanning-SQUID investigation of spin-orbit torque acting on yttrium iron garnet devices

NASA Astrophysics Data System (ADS)

Rosenberg, Aaron J.; Jermain, Colin L.; Aradhya, Sriharsha V.; Brangham, Jack T.; Nowack, Katja C.; Kirtley, John R.; Yang, Fengyuan; Ralph, Daniel C.; Moler, Kathryn A.

Successful manipulation of electrically insulating magnets, such as yttrium iron garnet, by by current-driven spin-orbit torques could provide a highly efficient platform for spintronic memory. Compared to devices fabricated using magnetic metals, magnetic insulators have the advantage of the ultra-low magnetic damping and the elimination of shunting currents in the magnet that reduce the torque efficiency. Here, we apply current in the spin Hall metal β-Ta to manipulate the magnetic orientation of micron-sized, electrically-insulating yttrium iron garnet devices. We do not observe spin-torque switching even for applied currents well above the critical current expected in a macrospin switching model. This suggests either inefficient transfer of spin torque at our Ta/YIG interface or a breakdown of the macrospin approximation. This work is supported by FAME, one of six centers of STARnet sponsored by MARCO and DARPA. The SQUID microscope and sensors were developed with support from the NSF-sponsored Center NSF-NSEC 0830228, and from NSF IMR-MIP 0957616.

Neodymium:yttrium-aluminum-garnet laser fusion of endarterectomy flaps.

PubMed

Humphrey, P W; Slocum, M M; Loy, T S; Silver, D

1995-07-01

This study evaluated the efficacy of neodymium:yttrium-aluminum-garnet laser welding of flaps in canine arteries and in securing the distal flap during human carotid endarterectomy. Endarterectomy flaps were created in both common carotid and both common femoral arteries in 12 dogs. The flaps were repaired with either the neodymium:yttrium-aluminum-garnet laser or with 6-0 polypropylene sutures. The arteries were removed after duplex scanning at either 7 or 28 days. Eighteen high carotid endarterectomy flaps in 16 patients have been subsequently secured with the laser welding technique. Laser repairs (125 +/- 19 joule) of the canine arteries were completed more quickly than suture repairs (mean 25 seconds vs 135 seconds, respectively; p < 0.04). Duplex ultrasonography revealed no discernable differences between the two groups of arteries. Arteries studied at 7 days revealed three microscopic flaps (two suture, one laser), more subintimal fibroblastic proliferation in suture than laser-repaired carotid arteries (3: 1, p = 0.0530), and similar amounts of inflammation in suture- and laser-repaired arteries. Arteries studied at 28 days revealed one microscopic intimal flap (suture-repaired); equal fibroblastic and inflammatory responses in suture- and laser-repaired vessels; and no evidence of laser thermal injury. Eighteen carotid endarterectomy flaps have been successfully fused with no immediate or long-term complications in 16 patients (follow-up of 0 to 24 months). Laser fusion appears to be a safe and effective method for securing distal carotid endarterectomy flaps.

Growth and luminescent properties of Yb:YAG and Ca co-doped Yb:YAG ultrafast scintillation crystals

NASA Astrophysics Data System (ADS)

Zhu, Maodong; Qi, Hongji; Pan, Mingyan; Hou, Qing; Jiang, Benxue; Jin, Yaxue; Han, Hetong; Song, Zhaohui; Zhang, Hui

2018-05-01

In this work, Yb-doped Y3Al5O12 [yttrium aluminum garnet (YAG)] crystals and Ca co-doped Yb:YAG crystals were grown by the Czochralski (CZ) method. The chemical formulas of the two crystals are (Yb0.1Y0.9)3Al5O12 and (Ca0.001Yb0.1Y0.899)3Al5O12, respectively. The structural, optical and luminescent properties of the Yb:YAG and Ca, Yb:YAG crystals were investigated by X-ray rocking curve, X-ray diffraction, Raman spectra, UV-Visble-NIR absorption spectra and X-ray fluorescence. X-ray fluorescence spectrum with two emission peaks at 330 nm and 490 nm were observed in the two kinds of crystals, which would increase slightly after the annealing. Comparing to the Yb:YAG crystal, Ca co-doped Yb:YAG crystal behaved the better luminescent intensity without changing the crystal structure and vibrational modes. This indicates that by doping Ca2+ in Yb:YAG crystal may be an appropriate way to enhance the luminescent property of the scintillation crystal.

Radiative and Nonradiative Transitions of the Rare-Earth Ions Tm(3+) and Ho(3+) in Y3AI5O12 and LiYF4

NASA Technical Reports Server (NTRS)

Walsh, Brian M.; Armagan, Guzin; Dibartolo, Baldassare; Modlin, Edward A.

1995-01-01

The optical spectra of rare earth ions in solids arise primarily from electric and magnetic dipole transitions between stark split multiplets of the 4f(sup N) electronic configuration. Electric dipole transitions are parity forbidden between levels of the 4f(sup N) configuration, while those of magnetic dipole origin are allowed. It is known from experiment, however, that the significant contributions to the intensities of most transitions are electric dipole in nature. Judd and Ofelt developed the theory of forced electric dipole transitions of rare-earth ions. This study is devoted to determining electric dipole transition probabilities and branching ratios for Tm(3+) and Ho(3+) ions in Yttrium Aluminum Garnet (YAG) and Yttrium Lithium Fluoride (YLF) using the theory of Judd and Ofelt. The radiative rates determined from the Judd-Ofelt analysis are used with measured lifetimes to find nonradiative rates of relaxation.

Mixed garnet laser for a water vapour DIAL

NASA Astrophysics Data System (ADS)

Treichel, Rainer; Strohmaier, Stephan; Nikolov, Susanne; Eichler, Hans-Joachim; Murphy, Eamonn

2017-11-01

For the water vapour DIAL "WALES" the wavelength regions around 935 nm, 942 nm and 944 nm have been identified as the most suitable wavelength ranges. These wavelengths can be obtained using opticalparametric-oscillators (OPOs), stimulated Raman shifters and the Ti-Sapphire laser but none of these systems could deliver all the needed parameters like beam quality, efficiency, pulse length and energy yet. Also these systems are comparably big and heavy making them less suitable for a satellite based application. A fourth possibility to achieve these wavelength ranges is to shift the quasi-3-level laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing aluminium and yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals or special pump lasers are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. In a first phase such mixed garnet crystals had been grown and characterised. The outcome was the selection of the gadolinium-scandium garnet for the most suitable laser crystal. During a second phase the complete laser system with output energy about 18 mJ in single 20 ns pulses and up to 8 mJ in free running mode with a combined pulse width of 250 μs at 942 nm have been demonstrated. The results of the first laser operation and the achieved performance parameter are reported.

New application of the long-pulsed Nd-YAG laser as an ablative resurfacing tool for skin rejuvenation: a 7-year study.

PubMed

Alshami, Mohammad Ali

2013-09-01

Carbon dioxide (CO2 ) and erbium-yttrium aluminum garnet (Er-YAG) lasers are the gold standards in ablative skin resurfacing. Neodymium-doped yttrium aluminum garnet (Nd-YAG) laser is considered a nonablative skin resurfacing laser whose usage is limited due to its high cost. To assess the efficacy and safety of Nd-YAG as an ablative resurfacing laser and to compare the results with those previously published for CO2 and Erbium-YAG lasers. A total of 296 patients (251 female and 45 male) with Fitzpatrick skin types III-IV and dermatological conditions amenable to ablative skin resurfacing participated in this study. Nd-YAG laser parameters assessed were wavelength (1064 nm), pulse duration (5 ms), fluence (10 J/cm(2) ), and spot size (8-10 mm). Efficacy of Nd-YAG laser was assessed by comparing pre- and posttreatment photographs. An improvement of 30-80% was observed in treated patients. The degree of improvement correlated positively with the number of laser sessions. The most common side effect was hyperpigmentation. Other side effects were less common and mild in intensity compared with published results for gold standard ablative lasers. Not only was the Nd-YAG laser found to be as effective as Er-YAG and CO2 lasers, but treated patients also had shorter recovery and treatment times, and at lower cost. © 2013 Wiley Periodicals, Inc.

Shear Bond Strength of Composite and Ceromer Superstructures to Direct Laser Sintered and Ni-Cr-Based Infrastructures Treated with KTP, Nd:YAG, and Er:YAG Lasers: An Experimental Study.

PubMed

Gorler, Oguzhan; Hubbezoglu, Ihsan; Ulgey, Melih; Zan, Recai; Guner, Kubra

2018-04-01

The aim of this study was to examine the shear bond strength (SBS) of ceromer and nanohybrid composite to direct laser sintered (DLS) Cr-Co and Ni-Cr-based metal infrastructures treated with erbium-doped yttrium aluminum garnet (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), and potassium titanyl phosphate (KTP) laser modalities in in vitro settings. Experimental specimens had four sets (n = 32) including two DLS infrastructures with ceromer and nanohybrid composite superstructures and two Ni-Cr-based infrastructures with ceromer and nanohybrid composite superstructures. Of each infrastructure set, the specimens randomized into four treatment modalities (n = 8): no treatment (controls) and Er:YAG, Nd:YAG, and KTP lasers. The infrastructures were prepared in the final dimensions of 7 × 3 mm. Ceromer and nanohybrid composite was applied to the infrastructures after their surface treatments according to randomization. The SBS of specimens was measured to test the efficacy of surface treatments. Representative scanning electron microscopy (SEM) images after laser treatments were obtained. Overall, in current experimental settings, Nd:YAG, KTP, and Er:YAG lasers, in order of efficacy, are effective to improve the bonding of ceromer and nanohybrid composite to the DLS and Ni-Cr-based infrastructures (p < 0.05). Nd:YAG laser is more effective in the DLS/ceromer infrastructures (p < 0.05). KTP laser, as second more effective preparation, is more effective in the DLS/ceromer infrastructures (p < 0.05). SEM findings presented moderate accordance with these findings. The results of this study supported the bonding of ceromer and nanohybrid composite superstructures to the DLS and Ni-Cr-based infrastructures suggesting that laser modalities, in order of success, Nd:YAG, KTP, and Er:YAG, are effective to increase bonding of these structures.

Transmyocardial revascularization on canine with Ho:YAG laser - an experimental study

NASA Astrophysics Data System (ADS)

Bao, Xiaoqing; Zhu, Jing; Zhang, Hui-Guo

2005-07-01

Background and Objective: To evaluate the efficiency of transmyocardial revascularization with Ho:YAG laser and find out adequate physical parameters of the laser. Materials and Methods: 10 dogs were studied. All the samples were divided into two groups: the laser group (5 dogs) and the control group (5 dogs). Acute myocardial ischemia was induced in all the samples, and transmyocardial laser revascularization (TMLR) was only done in the laser group. We compared the difference of improvement in myocardial perfusion between the two groups with single photon emission computed tomograph (SPECT) and observed the patency of the laser channels and heat injures in the tissue adjacent to the channels with light- and electro-scope. Results: After 4 weeks, the recovery of myocardial perfusion was significantly faster in the laser group than in the control group through SPECT (P<0.05). Most of the laser channels drilled with Ho:YAG laser were filled with fibrin. There were amount of microvessels and erythrocytes inside and around the channels. Only slight heat injures were seen in the tissue adjacent to the channels. Only 20-30 watts were needed in TMLR. Conclusions: Transmyocardial revascularization with Ho:YAG laser limits infarct expansion and reduces myocardial ischemia efficiently. TMLR with Ho:YAG laser can become a new technique to treat ischemic heart disease.

Higher Temperature Thermal Barrier Coatings with the Combined Use of Yttrium Aluminum Garnet and the Solution Precursor Plasma Spray Process

NASA Astrophysics Data System (ADS)

Gell, Maurice; Wang, Jiwen; Kumar, Rishi; Roth, Jeffery; Jiang, Chen; Jordan, Eric H.

2018-04-01

Gas-turbine engines are widely used in transportation, energy and defense industries. The increasing demand for more efficient gas turbines requires higher turbine operating temperatures. For more than 40 years, yttria-stabilized zirconia (YSZ) has been the dominant thermal barrier coating (TBC) due to its outstanding material properties. However, the practical use of YSZ-based TBCs is limited to approximately 1200 °C. Developing new, higher temperature TBCs has proven challenging to satisfy the multiple property requirements of a durable TBC. In this study, an advanced TBC has been developed by using the solution precursor plasma spray (SPPS) process that generates unique engineered microstructures with the higher temperature yttrium aluminum garnet (YAG) to produce a TBC that can meet and exceed the major performance standards of state-of-the-art air plasma sprayed YSZ, including: phase stability, sintering resistance, CMAS resistance, thermal cycle durability, thermal conductivity and erosion resistance. The temperature improvement for hot section gas turbine materials (superalloys & TBCs) has been at the rate of about 50 °C per decade over the last 50 years. In contrast, SPPS YAG TBCs offer the near-term potential of a > 200 °C improvement in temperature capability.

Synthesis of YAG nanopowder by the co-precipitation method: Influence of pH and study of the reaction mechanisms

NASA Astrophysics Data System (ADS)

Marlot, Caroline; Barraud, Elodie; Le Gallet, Sophie; Eichhorn, Marc; Bernard, Frédéric

2012-07-01

YAG nanopowders with an average grain size of 30 nm have been successfully synthesized by the co-precipitation method using nitrates with precipitant of ammonium hydrogen carbonate. The influence of precipitation conditions such as pH, aging time and calcination temperature on the formation of secondary phases has been studied. The accurate control of pH value at every stage of precipitation process is crucial to avoid the presence of YAM (Yttrium Aluminium Monoclinic, Y4Al2O9) and yttrium oxide (Y2O3) after calcination. The reaction mechanisms have been investigated using different techniques such as infrared spectroscopy, x-ray diffraction and thermal analyses. The YAG phase is formed around 1050 °C passing through an intermediate phase called YAP (Yttrium Aluminium Perovskite, YAlO3). Local chemical heterogeneities are responsible for the deviation of the Y:Al ratio and the formation of YAP during heat treatment.

Long-pulsed 1064-nm neodymium:yttrium-aluminum-garnet laser treatment for refractory warts on hands and feet.

PubMed

Kimura, Utako; Takeuchi, Kaori; Kinoshita, Ayako; Takamori, Kenji; Suga, Yasushi

2014-03-01

Common warts (verruca vulgaris) are the most commonly seen benign cutaneous tumors. However, warts in the hands and feet regions often respond poorly to treatment, some are resistant to more than 6 months of treatment with currently available modalities, including cryotherapy, being defined as refractory warts. We investigated the usefulness of long-pulsed neodymium:yttrium-aluminum-garnet (LP-Nd:YAG) treatment for refractory warts. The clinical trial was conducted on 20 subjects (11 male, nine female) with a total of 34 lesions (periungual/subungual areas, plantar areas, fingers and/or toes). All the subjects suffered from refractory warts despite conventional treatments for more than 6 months. The patients were administrated up to six sessions of treatment, at intervals of 4 weeks between sessions, with an LP-Nd:YAG at a spot size of 5 mm, pulse duration of 15 msec and fluence of 150-185 J/cm(2) . Evaluation of the treatment results at 24 weeks after the initial treatment showed complete clearance of the refractory warts in 56% of the patients. Histological evaluation showed separation of the dermis and epidermis at the basement membrane with coagulated necrosis of the wart tissue in the lower epidermis, as well as coagulation and destruction of the blood vessels in the papillary dermis following the laser irradiation. No scarring, post-hyperpigmentary changes or serious adverse events were documented. Our preliminary results show that LP-Nd:YAG treatments are safe and effective for refractory warts of hands and feet, causing minimal discomfort, and is a viable treatment alternative. © 2014 Japanese Dermatological Association.

Holmium: YAG laser-induced liquid jet knife: possible novel method for dissection.

PubMed

Nakagawa, Atsuhiro; Hirano, Takayuki; Komatsu, Makoto; Sato, Mariko; Uenohara, Hiroshi; Ohyama, Hideki; Kusaka, Yasuko; Shirane, Reizo; Takayama, Kazuyoshi; Yoshimoto, Takashi

2002-01-01

Making surgical incisions in vessel-rich organs without causing bleeding is difficult. Thus, it is necessary to develop new devices for this purpose, especially for surgery involving small vessels as in neurosurgery, where damage against even small cerebral vessels result in severe neurological deficits. A laser-induced liquid jet was generated by irradiating pulsed Holmium Yttrium-Aluminum-Garnet (Ho: YAG) laser (beams of 350 microseconds pulse width) within a copper tube (internal diameter, 1 mm) with pure water (150 ml /hour). Ho: YAG laser beams were irradiated through an optical fiber (core diameter, 0.4 mm). The influence of the input of laser energy, structure of the nozzle, and the stand-off distance between the optical fiber tip and nozzle exit on the jet velocity was measured by a high-speed video camera to evaluate controllability of jet. The effect on artificial organs made of 10 and 30%(w/v) gelatin, each of which represent features of soft tissue and blood vessels. Jet velocity increased in proportion to gain in laser energy input, and maximum penetration depth into 10%(w/v) gelatin was 35 mm by single exposure at 350 mJ/pulse without impairing a vessel model. Shapes of nozzle also modified jet velocity with optimal nozzle/tube area ratio of 0.25. The laser-induced liquid jet has excellent potential as a new tool for removing soft tissue without damaging vital structures. Copyright 2002 Wiley-Liss, Inc.

Q-switched Nd: YAG laser versus trichloroacetic acid peeling in the treatment of melasma among Egyptian patients.

PubMed

Moubasher, Alaa E A; Youssef, Eman M K; Abou-Taleb, Doaa A E

2014-08-01

Melasma is a common disorder of facial hyperpigmentation that is often resistant to treatment. To evaluate the efficacy of trichloroacetic acid (TCA) peeling in comparison with double frequency Q-switched neodymium-doped:yttrium aluminum garnet (QS-Nd:YAG) laser in the treatment of melasma. Sixty-five adult Egyptian female patients with melasma were enrolled in this study. Wood light was used for determination of the histological type of melasma. The patients were divided into 4 groups according to treatment modalities: peeling with different concentrations of TCA and double frequency QS-Nd:YAG laser. Trichloroacetic acid peeling was performed every 2 weeks up to 8 sessions, whereas laser treatment was performed every month up to 6 sessions. Melasma area and severity index (MASI) score was used before and after treatment for evaluation. Improvement percentage of MASI score was significantly higher among patients treated with TCA 25% (p < .001). Epidermal type of melasma was significantly improved compared with the dermal type (p = .0029). Q-switched neodymium-doped:yttrium aluminum garnet laser showed the highest incidence of postinflammatory hyperpigmentation (53.3%). Trichloroacetic acid peeling is effective in the treatment of melasma, TCA 25% was the most effective concentration. Q-switched neodymium-doped:yttrium aluminum garnet laser is not recommended in the treatment of melasma because it was associated with the highest incidence of complications.

Comparison of hair removal efficacy and side effect of neodymium:Yttrium-aluminum-garnet laser and intense pulsed light systems (18-month follow-up).

PubMed

Szima, Georgina Zita; Janka, Eszter Anna; Kovács, Anikó; Bortély, Blanka; Bodnár, Edina; Sawhney, Irina; Szabó, Éva; Remenyik, Éva

2017-06-01

Photothermal destruction of hair shaft melanin with intense pulsed light (IPL) and neodymium:yttrium-aluminum-garnet (Nd:YAG) laser has become an effective treatment of hair removal. Our aim was to compare efficacy, satisfactory levels, safety, and side effects of Nd:YAG and IPL in hair reduction. This was a prospective randomized intrapatient, right-left, assessor-blinded comparison of Nd:YAG vs IPL. There were 38 volunteers recruited. Seven sessions were performed. Hair count, efficacy, and side effects were compared before and after each treatment and 6 months after the last treatment. In respect of 12 volunteers, we have examined the reduction in hair after 18 months. Initially, there was no significant difference between the numbers of hair follicles. There was significant hair reduction after each treatment on the Nd:YAG-treated side. The hair reduction became significant after the third treatment with IPL. Comparison of the efficacy of the two devices on each visits showed no significant difference. There was statistically lower pain score on the IPL-treated side and statistically higher erythema, burning sensation, and edema on the Nd:YAG-treated side. Statistically lower side effect score was observed on the IPL-treated side. Eight months after the last treatment, there was significant hair reduction both on the Nd:YAG and on the IPL-treated side, and there was no difference between the efficacy. The patient satisfaction scores were higher with the IPL. Unwanted hair can be reduced by both systems safely and effectively; however, IPL has less side effects and higher satisfaction scores. © 2017 Wiley Periodicals, Inc.

Magneto-optical properties of cerium substituted yttrium iron garnet films with reduced thermal budget for monolithic photonic integrated circuits.

PubMed

Goto, Taichi; Onbaşlı, Mehmet C; Ross, C A

2012-12-17

Thin films of polycrystalline cerium substituted yttrium iron garnet (CeYIG) were grown on an yttrium iron garnet (YIG) seed layer on Si and Si-on-insulator substrates by pulsed laser deposition, and their optical and magneto-optical properties in the near-IR region were measured. A YIG seed layer of ~30 nm thick processed by rapid thermal anneal at 800°C provided a virtual substrate to promote crystallization of the CeYIG. The effect of the thermal budget of the YIG/CeYIG growth process on the film structure, magnetic and magnetooptical properties was determined.

Epitaxial Garnets and Hexagonal Ferrites.

DTIC Science & Technology

1982-04-20

goenv.o -,y la)ers were YIG (yttrium iron garnet ) films grown by liquid phase epitaxy w:* ( LPE ) on gadolinium gallium garnet (GGG) substrates. Magnetic...containing three epitaxial layers. In addition to the MSW work oil garnets , LPE of lithium ferrite and hexagonal fertites was studied. A substituted lead...of a stripline. The other layers are epitaxial films , generally YIG (yttrium iron garnet ) with magnetic properties adjusted by suitable modifications

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 um thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 um spatially-resonant, antenna.

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

DOE PAGES

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho; ...

2017-12-22

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 um thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 um spatially-resonant, antenna.

Preparation and morphology, magnetic properties of yttrium iron garnet nanodot arrays on Gd3Ga5O12 substrate

NASA Astrophysics Data System (ADS)

Xu, Zhiwang; Zheng, Hui; Han, Mangui

2017-07-01

In this work, yttrium iron garnet nanodot array has been deposited on Gd3Ga5O12 substrate by pulsed laser deposition through an ultrathin alumina mask. The morphology and magnetic properties of YIG nanodot array have been investigated. Scanning electron microscopy displays the prepared nanodot array has a sharp distribution in diameter centered at 330 nm with standard deviation of 20 nm. X-ray diffraction θ-2θ and pole figure analysis show the yttrium iron garnet nanodot array has oriented growth. Moreover, typical hysteresis loops and ferromagnetic resonance spectra display larger coercivity and multi-resonance peaks which are ascribed to this unique structure.

Hypopigmentation Induced by Frequent Low-Fluence, Large-Spot-Size QS Nd:YAG Laser Treatments.

PubMed

Wong, Yisheng; Lee, Siong See Joyce; Goh, Chee Leok

2015-12-01

The Q-switched 1064-nm neodymium-doped yttrium aluminum garnet (QS 1064-nm Nd:YAG) laser is increasingly used for nonablative skin rejuvenation or "laser toning" for melasma. Multiple and frequent low-fluence, large-spot-size treatments are used to achieve laser toning, and these treatments are associated with the development of macular hypopigmentation as a complication. We present a case series of three patients who developed guttate hypomelanotic macules on the face after receiving laser toning treatment with QS 1064-nm Nd:YAG.

Low Thermal Conductivity Yttrium Aluminum Garnet Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray: Part II—Planar Pore Formation and CMAS Resistance

NASA Astrophysics Data System (ADS)

Kumar, Rishi; Jiang, Chen; Wang, Jiwen; Cietek, Drew; Roth, Jeffery; Gell, Maurice; Jordan, Eric H.

2018-06-01

Low thermal conductivity in yttrium aluminum garnet (YAG)-based thermal barrier coatings (TBCs) made by solution precursor plasma spray (SPPS) can be achieved by creating planar arrays of porosity called inter-pass boundaries (IPBs) as shown in Part I. In the current work, the mechanism of IPBs formation is studied through analysis of precursor entrainment and collection of single/raster step deposition patterns. It is concluded that the IPBs are formed by trapping precursor that under/over penetrates the plasma jet. CMAS interaction tests on SPPS YAG TBCs with heavy IPBs show an improvement of 123X and 15X over APS YSZ and SPPS YAG-light IPBs TBCs, respectively. It is demonstrated that the exceptional coating performance is because of the engineered heavy IPBs which branch out from the vertical cracks and run parallel to the surface. The CMAS melt gets drawn in the IPBs due to the capillary forces, leading to a shallow infiltration depth. The IPBs have a porosity of 70%, thus act as reservoirs for CMAS. Based on the favorable results, an alternate CMAS mitigation strategy is proposed that solely relies on microstructural features instead of the conventional approach where a vigorous reaction between CMAS-TBCs is desirable to form secondary phases.

The Effect of Neodymium: Yttrium Aluminum Garnet and Fractional Carbon Dioxide Lasers on Alopecia Areata: A Prospective Controlled Clinical Trial.

PubMed

Yalici-Armagan, Basak; Elcin, Gonca

2016-04-01

Effective treatment options for alopecia areata (AA) are missing. Whether lasers might be effective is a topic of debate. We aimed to evaluate whether neodymium: yttrium aluminum garnet (Nd:YAG) or fractional carbon dioxide lasers might stimulate the development of new hair. Thirty-two patients who had long-standing and treatment refractory diseases were recruited for the study. Three different patches on the scalp were selected, 1 of which served as control. The mean outcome measure was the hair count, which was calculated with the digital phototrichogram. Response was defined as at least 25% increase in the mean hair count at the treated patch compared with the control patch. At the end of the study, there was no statistically significant difference in the mean hair count for the 3 patches. In 7 of 32 patients (22%), an increase in the mean hair count was observed on the whole scalp including the control patch, which resulted in an improved Severity of Alopecia Tool (SALT) score. We have observed that Nd:YAG or fractional carbon dioxide lasers did not increase the mean hair count on the treated AA patches when compared with the control patch. However, an SALT score improvement in 22% of the patients suggested spontaneous remission.

Comparison of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet laser for treatment of cosmetic tattoos containing titanium and iron in an animal model.

PubMed

Wang, Chia-Chen; Huang, Chuen-Lin; Yang, An-Hang; Chen, Chih-Kang; Lee, Shao-Chen; Leu, Fur-Jiang

2010-11-01

Cosmetic tattoos contain titanium and ferric oxide and darken through reduction after Q-switched laser irradiation. The optimal treatment for removing these pigments remains unknown. To compare the effects of two Q-switched lasers and a short-pulse erbium-doped yttrium aluminum garnet (SP Er:YAG) laser to remove cosmetic tattoos in an animal model. Rats were tattooed using white, flesh-colored, and brown inks (4 bands of each color) on their backs. For each color, one band was left untreated, and one each was treated with a Q-switched neodymium-doped YAG laser, a Q-switched alexandrite laser, and a SP Er:YAG laser every 3 weeks until the pigments were clear. The two Q-switched lasers were equally effective; all three pigments darkened initially and then resolved gradually. Up to 20, 18, and 10 sessions were required to remove white, flesh-colored, and brown tattoos, respectively. Only six sessions were required with the SP Er:YAG laser. Minimal scarring was observed with all lasers. Skin biopsies confirmed pigment granule fragmentation after Q-switched laser treatment and a decrease in the amount of pigment after SP Er:YAG laser treatment. The SP Er:YAG laser was superior to the Q-switched lasers for removing cosmetic tattoos. © 2010 by the American Society for Dermatologic Surgery, Inc.

A spatio-spectral polarization analysis of 1 µm-pumped bulk supercontinuum in a cubic crystal (YAG)

NASA Astrophysics Data System (ADS)

Choudhuri, Aradhana; Chatterjee, Gourab; Zheng, Jiaan; Hartl, Ingmar; Ruehl, Axel; Dwayne Miller, R. J.

2018-06-01

We present the first systematic study of the spatio-spectral polarization properties of a supercontinuum generated in a cubic crystal, yttrium-aluminum garnet (YAG), including a full spectral analysis of the white light core and surrounding ring structure. We observe no depolarization of the supercontinuum, and no spatial dependence of polarization ratios for any wavelength. We discuss the discrepancy of YAG's polarization behavior in the context of well-established results in literature reporting self-induced depolarization in other cubic crystals.

Excitation of the three principal spin waves in yttrium iron garnet using a wavelength-specific multi-element antenna

NASA Astrophysics Data System (ADS)

Bang, Wonbae; Jungfleisch, Matthias B.; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Hoffmann, Axel; Ketterson, John B.

2018-05-01

We report systematic measurements of the dispersion of long wavelength spin waves for the magnetic field along the three principal directions (supporting the forward volume, backward volume and Damon-Eshbach modes) of a 3.05 μm thick yttrium iron garnet film on a lattice-matched (111) gadolinium gallium garnet substrate obtained using a lithographically patterned, multi-element, 50 μm spatially-resonant, antenna.

Development and performance characteristics of flash lamp pumped Yb:YAG, Cr:Tm:Ho:YAG, Er:Tm:Ho:YLF laser sources and investigation of their potential biological applications

NASA Astrophysics Data System (ADS)

Karadimitriou, N.; Klinkenberg, B.; Papadopoulos, D. N.; Serafetinides, A. A.

2007-07-01

Laser ablation for the formation of apodized patterns on intraocular lenses, as an alternative of the conventional injection molding, has been proved to be a very promising new technique. For the precise lenses ablation, the use of suitable laser wavelength and pulse duration, resulting in a small optical penetration depth in the lens and in confinement of the energy deposition in a small volume, as well as the reduced thermal damage to the surrounding tissue, is essential. Mid-infrared laser wavelengths, at which the organic biological simulators absorption coefficient is large, meet well the above conditions. Towards the complete understanding of the intraocular lens ablation procedure and therefore the choice of the optimum laser beam characteristics for the most accurate, efficient and safe surgical application, the comparative study of various mid-infrared laser sources is of great interest. In this work we investigate the potential of the development of three different mid-infrared laser sources, namely the Yb:YAG, the Cr:Tm:Ho:YAG and the Er:Tm:Ho:YLF laser, operating at 1029 nm, 2060 nm and 2080 nm respectively and their ability in forming patterns on biomaterials. Pumping was achieved with conventional Xe flash lamps in a double elliptical pump chamber. A properly designed Pulse-Forming- Network capable of delivering energy up to 800 J, in variable lamp illumination durations is used. Several hundreds of mJoules were achieved from the Yb:YAG laser oscillator and several Joules from the Ho:YAG and Ho:YLF laser oscillators. Free running and Q-switched laser operation studies and preliminary experiments on laser and biomaterials (biopolymers and animal tissues) interactions will be reported.

Comparison of diode laser and Er:YAG lasers in the treatment of ankyloglossia.

PubMed

Aras, Mutan Hamdi; Göregen, Mustafa; Güngörmüş, Metin; Akgül, Hayati Murat

2010-04-01

The purpose of this study was to compare the tolerance of lingual frenectomy with regard to a local anesthesia requirement and comparison of postsurgical discomfort experienced by patients operated on with both diode and erbium:yttrium-aluminium-garnet (Er:YAG) lasers. Ankyloglossia, commonly known as tongue-tie, is a congenital oral anomaly characterized by a short lingual frenulum. A short lingual frenulum may contribute to feeding, speech, and mechanical tongue problems. Sixteen referred patients with tongue mobility complaints were included in this study. A GaAlAs laser device with a continuous wavelength of 808 nm was used in the diode group. Frenulums were incised by applying 2 W of laser power. The Er:YAG laser device with a continuous wavelength of 2940 nm was used in the Er:YAG group. Frenulums were incised by applying 1 W of laser power. The acceptability of the lingual frenectomy without local anesthesia and the degree of the postsurgical discomfort were evaluated. Although the majority of patients (six) could be operated on without local anesthesia in the Er:YAG group, all patients could not be operated on without local anesthetic agent in the diode group. There were no differences between the two groups with regard to pain, chewing, and speaking on the first or seventh day after surgery, whereas patients had more pain in the Er:YAG group than in the diode group the first 3 h after surgery. The results indicate that only the Er:YAG laser can be used for lingual frenectomy without local anesthesia, and there was no difference between the two groups regarding the degree of the postsurgical discomfort except in the first 3 h. In conclusion, these results indicate that the Er:YAG laser is more advantageous than the diode laser in minor soft-tissue surgery because it can be performed without local anesthesia and with only topical anesthesia.

Using transurethral Ho:YAG-laser resection to treat urethral stricture and bladder neck contracture

NASA Astrophysics Data System (ADS)

Bo, Juanjie; Dai, Shengguo; Huang, Xuyuan; Zhu, Jing; Zhang, Huiguo; Shi, Hongmin

2005-07-01

Objective: Ho:YAG laser had been used to treat the common diseases of urinary system such as bladder cancer and benign prostatic hyperplasia in our hospital. This study is to assess the efficacy and safety of transurethral Ho:YAG-laser resection to treat the urethral stricture and bladder neck contracture. Methods: From May 1997 to August 2004, 26 cases of urethral stricture and 33 cases of bladder neck contracture were treated by transurethral Ho:YAG-laser resection. These patients were followed up at regular intervals after operation. The uroflow rate of these patients was detected before and one-month after operation. The blood loss and the energy consumption of holmium-laser during the operation as well as the complications and curative effect after operation were observed. Results: The therapeutic effects were considered successful, with less bleeding and no severe complications. The Qmax of one month postoperation increased obviously than that of preoperation. Of the 59 cases, restenosis appeared in 11 cases (19%) with the symptoms of dysuria and weak urinary stream in 3-24 months respectively. Conclusions: The Ho:YAG-laser demonstrated good effect to treat the obstructive diseases of lower urinary tract such as urethral stricture and bladder neck contracture. It was safe, minimal invasive and easy to operate.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism.

PubMed

Puri, Neerja

2015-01-01

Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum - garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser.

Erbium-yttrium-aluminum-garnet laser irradiation ameliorates skin permeation and follicular delivery of antialopecia drugs.

PubMed

Lee, Woan-Ruoh; Shen, Shing-Chuan; Aljuffali, Ibrahim A; Li, Yi-Ching; Fang, Jia-You

2014-11-01

Alopecia usually cannot be cured because of the available drug therapy being unsatisfactory. To improve the efficiency of treatment, erbium-yttrium-aluminum-garnet (Er-YAG) laser treatment was conducted to facilitate skin permeation of antialopecia drugs such as minoxidil (MXD), diphencyprone (DPCP), and peptide. In vitro and in vivo percutaneous absorption experiments were carried out by using nude mouse skin and porcine skin as permeation barriers. Fluorescence and confocal microscopies were used to visualize distribution of permeants within the skin. Laser ablation at a depth of 6 and 10 μm enhanced MXD skin accumulation twofold to ninefold depending on the skin barriers selected. DPCP absorption showed less enhancement by laser irradiation as compared with MXD. An ablation depth of 10 μm could increase the peptide flux from zero to 4.99 and 0.33 μg cm(-2) h(-1) for nude mouse skin and porcine skin, respectively. The laser treatment also promoted drug uptake in the hair follicles, with DPCP demonstrating the greatest enhancement (sixfold compared with the control). The imaging of skin examined by microscopies provided evidence of follicular and intercellular delivery assisted by the Er-YAG laser. Besides the ablative effect of removing the stratum corneum, the laser may interact with sebum to break up the barrier function, increasing the skin delivery of antialopecia drugs. The minimally invasive, well-controlled approach of laser-mediated drug permeation offers a potential way to treat alopecia. This study's findings provide the basis for the first report on laser-assisted delivery of antialopecia drugs. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting

PubMed Central

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

AIM To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting METHODS A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. RESULTS In both groups, the BCVA improved significantly (P<0.001 for the modified round pattern group, P=0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased (P<0.001 for both) and the ACA significantly increased (P=0.001 for the modified round pattern group and P=0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. CONCLUSION Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO. PMID:29487812

Comparison of two Nd:YAG laser posterior capsulotomy: cruciate pattern vs circular pattern with vitreous strand cutting.

PubMed

Kim, Jin-Soo; Choi, Jung Yeol; Kwon, Ji-Won; Wee, Won Ryang; Han, Young Keun

2018-01-01

To investigate the effects and safety of neodymium: yttrium-aluminium-garnet (Nd:YAG) laser posterior capsulotomy with vitreous strand cutting. A total of 40 eyes of 37 patients with symptomatic posterior capsular opacity (PCO) were included in this prospective randomized study and were randomly subjected to either cruciate pattern or round pattern Nd:YAG posterior capsulotomy with vitreous strand cutting (modified round pattern). The best corrected visual acuity (BCVA), intraocular pressure (IOP), refractive error, endothelial cell count (ECC), anterior segment parameters, including anterior chamber depth (ACD) and anterior chamber angle (ACA) were measured before and 1mo after the laser posterior capsulotomy. In both groups, the BCVA improved significantly ( P <0.001 for the modified round pattern group, P =0.001 for the cruciate pattern group); the IOP and ECC did not significantly change. The ACD significantly decreased ( P <0.001 for both) and the ACA significantly increased ( P =0.001 for the modified round pattern group and P =0.034 for the cruciate group). The extent of changes in these parameters was not significantly different between the groups. Modified round pattern Nd:YAG laser posterior capsulotomy is an effective and safe method for the treatment of PCO. This method significantly changes the ACD and ACA, but the change in refraction is not significant. Modified round pattern Nd:YAG laser posterior capsulotomy can be considered a good alternative procedure in patients with symptomatic PCO.

Passive Q-switching of microchip lasers based on Ho:YAG ceramics.

PubMed

Lan, R; Loiko, P; Mateos, X; Wang, Y; Li, J; Pan, Y; Choi, S Y; Kim, M H; Rotermund, F; Yasukevich, A; Yumashev, K; Griebner, U; Petrov, V

2016-06-20

A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr²⁺:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm², respectively. When using Cr²⁺:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz.

Minimally invasive scoliosis treatment with a Ho:YAG laser

NASA Astrophysics Data System (ADS)

Rumpf, Christian G.; Lang, Robert D.; Goetz, Marcus H.

2000-11-01

Today most surgical treatment of spinal deformations is concentrated on invasive mechanical techniques with long operation times and major effects on the patient's mobility. The proposed minimally invasive technique using laser light for tissue ablation offers a possibility of gentle scoliosis treatment. It is thought that an early removal of the epiphysial growth zone on the convex side over several vertebrae results in a straightening of the spine. In a first evaluation, four different laser systems including argon ion, Nd:YAG (Q-switched), Nd:YAG (cw), and Ho:YAG laser were compared with respect to thermal damage to adjacent tissue, ablation rates, efficiency and laser handling. For in-vivo investigation, fresh lamb spine was used. Comparison showed that the Ho:YAG laser is the most appropriate laser for the given goal, providing efficient photoablation with moderate thermal effects on the adjacent tissue. In a second step the proposed minimally invasive operation technique was performed in in-vivo experiments on young foxhounds using 3D- thoracoscopic operation techniques. During these operations temperature mapping was done using fiber-optic fluorescent probes. After 12 months of normal growth the animals were sacrificed and x-ray as well as MRI was performed on the spine. First results show a positive effect of scoliotic growth in two cases. Being able to produce a scoliosis by hemiepiphysiodesis on the vertebra, It is thought that this technique is successful for a straightening of the spine on patients with scoliosis.

Acute effects of pulsed-laser irradiation on the arterial wall

NASA Astrophysics Data System (ADS)

Nakamura, Fumitaka; Kvasnicka, Jan; Lu, Hanjiang; Geschwind, Herbert J.; Levame, Micheline; Bousbaa, Hassan; Lange, Francoise

1992-08-01

Pulsed laser coronary angioplasty with an excimer or a holmium-yttrium-aluminum-garnet (Ho:YAG) laser may become an alternative treatment for patients with coronary artery disease. However, little is known about its acute consequences on the normal arterial wall. This study was designed to examine the acute histologic consequences of these two pulsed lasers on the arterial wall of normal iliac arteries in rabbits. Irradiation with each laser was performed in 15 normal iliac sites on eight male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mJ/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 micrometers , 3/5 Hz, 400 mJ/pulse, and 250 microsecond(s) ec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The sites irradiated with excimer or Ho:YAG laser had the same kinds of histologic features, consisting of exfoliation of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with Ho:YAG laser (p < 0.05). Laser irradiation with excimer or Ho:YAG laser of normal arteries results in localized mechanical vascular injury.

Combined effects of long-pulsed neodymium-yttrium-aluminum-garnet laser, diprospan and 5-fluorouracil in the treatment of keloid scars.

PubMed

Chen, Xiao-E; Liu, Juan; Bin Jameel, Afzaal Ahmed; Valeska, Maya; Zhang, Jia-An; Xu, Yang; Liu, Xing-Wu; Zhou, Hong; Luo, Dan; Zhou, Bing-Rong

2017-06-01

Keloids are benign tumors that originate from scar tissues, but they usually overgrow beyond the original wounds. In a three-month single-center clinical trial, 69 patients were randomly divided into three groups. Patients in group 1 were treated with intralesional injection of diprospan (2 mg betamethasone disodium phosphate and 5 mg betamethasone dipropionate in 1 ml) with one-month intervals for three months. Patients in groups 2 and 3 were injected with a combination of 0.5 ml 5-fluorouracil (5-FU; 25 mg/ml) and diprospan as above for three months also. Prior to each injection, the keloids of patients in group 3 were additionally irradiated by a 1,064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a single pulse at an energy density of 90-100 J/cm 2 and a pulse width of 12 msec. Clinical responses were evaluated by patient self-assessment and overall assessment by an observer according to the clinical signs of erythema, pruritus and pliability. A total of sixty-two patients completed the tests of the present study. At 2 and 3 months, the patients in all treatment groups showed an acceptable improvement in nearly all measurements. At the end of the study, the erythema and toughness score was significantly reduced and itch reduction was significantly greater in the diprospan + 5-FU + Nd:YAG group when compared to those in the other groups (P<0.05 for all indexes). The acceptable responses (good to excellent improvements) reported by blinded observers were as follows: 12% in the diprospan group, 48% in the diprospan + 5-FU group and 69% in the diprospan + 5-FU + Nd:YAG group. All of the results indicated that the combination of diprospan + 5-FU + Nd:YAG was the most efficacious therapy for keloid scars.

Combined effects of long-pulsed neodymium-yttrium-aluminum-garnet laser, diprospan and 5-fluorouracil in the treatment of keloid scars

PubMed Central

Chen, Xiao-E; Liu, Juan; Bin Jameel, Afzaal Ahmed; Valeska, Maya; Zhang, Jia-An; Xu, Yang; Liu, Xing-Wu; Zhou, Hong; Luo, Dan; Zhou, Bing-Rong

2017-01-01

Keloids are benign tumors that originate from scar tissues, but they usually overgrow beyond the original wounds. In a three-month single-center clinical trial, 69 patients were randomly divided into three groups. Patients in group 1 were treated with intralesional injection of diprospan (2 mg betamethasone disodium phosphate and 5 mg betamethasone dipropionate in 1 ml) with one-month intervals for three months. Patients in groups 2 and 3 were injected with a combination of 0.5 ml 5-fluorouracil (5-FU; 25 mg/ml) and diprospan as above for three months also. Prior to each injection, the keloids of patients in group 3 were additionally irradiated by a 1,064-nm neodymium-yttrium-aluminum-garnet (Nd:YAG) laser with a single pulse at an energy density of 90–100 J/cm2 and a pulse width of 12 msec. Clinical responses were evaluated by patient self-assessment and overall assessment by an observer according to the clinical signs of erythema, pruritus and pliability. A total of sixty-two patients completed the tests of the present study. At 2 and 3 months, the patients in all treatment groups showed an acceptable improvement in nearly all measurements. At the end of the study, the erythema and toughness score was significantly reduced and itch reduction was significantly greater in the diprospan + 5-FU + Nd:YAG group when compared to those in the other groups (P<0.05 for all indexes). The acceptable responses (good to excellent improvements) reported by blinded observers were as follows: 12% in the diprospan group, 48% in the diprospan + 5-FU group and 69% in the diprospan + 5-FU + Nd:YAG group. All of the results indicated that the combination of diprospan + 5-FU + Nd:YAG was the most efficacious therapy for keloid scars. PMID:28588688

Use of a microsecond Er:YAG laser in laryngeal surgery reduces collateral thermal injury in comparison to superpulsed CO2 laser.

PubMed

Böttcher, Arne; Jowett, Nathan; Kucher, Stanislav; Reimer, Rudolph; Schumacher, Udo; Knecht, Rainald; Wöllmer, Wolfgang; Münscher, Adrian; Dalchow, Carsten V

2014-05-01

Despite causing significant thermocoagulative insult, use of the carbon dioxide (CO2) laser is considered gold standard in surgery for early stage larynx carcinoma. Limited attention has been paid to the use of the erbium:yttrium-aluminium-garnet (Er:YAG) laser in laryngeal surgery as a means to reduce thermal tissue injury. The objective of this study is to compare the extent of thermal injury and precision of vocal fold incisions made using microsecond Er:YAG and superpulsed CO2 lasers. In the optics laboratory ex vivo porcine vocal folds were incised using Er:YAG and CO2 lasers. Lateral epithelial and subepithelial thermal damage zones and cutting gap widths were histologically determined. Environmental scanning electron microscopy (ESEM) images were examined for signs of carbonization. Temperature rise during Er:YAG laser incisions was determined using infrared thermography (IRT). In comparison to the CO2 laser, Er:YAG laser incisions showed significantly decreased epithelial (236.44 μm) and subepithelial (72.91 μm) damage zones (p < 0.001). Cutting gaps were significantly narrower for CO2 (878.72 μm) compared to Er:YAG (1090.78 μm; p = 0.027) laser. ESEM revealed intact collagen fibres along Er:YAG laser cutting edges without obvious carbonization, in comparison to diffuse carbonization and tissue melting seen for CO2 laser incisions. IRT demonstrated absolute temperature rise below 70 °C for Er:YAG laser incisions. This study has demonstrated significantly reduced lateral thermal damage zones with wider basal cutting gaps for vocal fold incisions made using Er:YAG laser in comparison to those made using CO2 laser.

Complex study on photoluminescence properties of YAG:Ce,Gd phosphors

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Ju, Yangyang; Stepanov, S. A.; Soschin, N. M.

2017-05-01

Luminescence characteristics of gadolinium co-doped yttrium aluminium garnet doped with cerium phosphors were studied. In this work, powder X-ray diffraction (XRD) spectra, elemental composition analyses, excitation and emission spectra, conversion efficiency of emission phosphor, corresponding (CIE) chromaticity colour coordinates and pulsed photoluminescence decay kinetic curves were investigated, all the measurements were performed at room temperature. The properties of the phosphors were studied by comparing the composition of the phosphors and their luminescent properties.

Er:YAG Laser Versus Cold Knife Excision in the Treatment of Nondysplastic Oral Lesions: A Randomized Comparative Study for the Postoperative Period.

PubMed

Broccoletti, Roberto; Cafaro, Adriana; Gambino, Alessio; Romagnoli, Ercole; Arduino, Paolo Giacomo

2015-12-01

The aim of this prospective study was to estimate the effects of Erbium substituted: Yttrium Aluminium Garnet (Er:YAG) laser, compared with traditional scalpel, on the early postoperative sequelae of nondysplastic oral lesion removal. There is limited evidence that laser surgery could exhibit advantages over scalpel in oral mucosal surgery. The investigators studied a cohort of 344 patients; 394 lesions were randomized and treated. Outcome statistically evaluated variables were: age, gender, the site and size of investigated lesions, visual analogue score (VAS) of pain, the Oral Health Impact Profile questionnaire (OHIP-14) and the Quality of Life test (QOL), and number of analgesics taken in the 1st week after surgery. Significant differences were found if considering the surgical time, VAS, and QOL and OHIP-14 questionnaires; regarding those data, the Er:YAG laser appeared to be faster and less painful than traditional scalpel (p < 0.05). For bigger lesions, patients statistically took more painkillers if they had undergone traditional surgery. Considering the site of the treated lesions, Er:YAG laser was less painful, especially in the gingiva and palate (p < 0.05). This is the first randomized controlled surgical trial reported for the management of nondysplastic oral lesions with the use of an Er:YAG laser. With many limitations, the present report identifies significant difference in the immediate postoperative surgical period between the two treatments, meaning that the Er:YAG laser seemed to be less painful, and better accepted by patients, than traditional scalpel.

Epitaxial Garnets and Hexagonal Ferrites.

DTIC Science & Technology

1980-02-28

shaped LPE garnet samples with 31.5um film thickness. We were informed that initial evalu- ation showed acceptably low insertion loss and that the material...frequencies above 25 GHz. c. Furnish up to eight (8) liquid phase epitaxy yttrium iron garnet films to RADC/EEA for testing and evaluation. These tasks...a "Method for Controlling Resonance Frequency of Yttrium Iron Garnet Films ." A patent, "Epitaxial Growth of M-type Hexagonal Ferrite Films on Spinel

Spin waves in micro-structured yttrium iron garnet nanometer-thick films

DOE PAGES

Jungfleisch, Matthias B.; Zhang, Wei; Jiang, Wanjun; ...

2015-03-24

Here, we investigated the spin-wave propagation in a micro-structured yttrium iron garnet waveguide of 40 nm thickness. Utilizing spatially-resolved Brillouin light scattering microscopy, an exponential decay of the spinwave amplitude of 10 μm was observed. This leads to an estimated Gilbert damping constant of α = (8.79 ± 0.73) x 10 $-$4, which is larger than damping values obtained through ferromagnetic resonance measurements in unstructured films. Furthermore, we compared the theoretically calculated spatial interference of waveguide modes to the spin-wave pattern observed experimentally by means of Brillouin light scattering spectroscopy.

High-frequency magnetodielectric response in yttrium iron garnet at room temperature

NASA Astrophysics Data System (ADS)

Zhu, Jie; Liu, Yuan; Jia, Longfei; Zhang, Baoshan; Yang, Yi; Tang, Dongming

2018-05-01

Magnetic and dielectric properties of Yttrium Iron Garnet are measured over a frequency ranging from 0.5 GHz to 10 GHz with a magnetic field applied parallel to the propagation direction of the microwave. At the same time, the magnetodielectric phenomena are detected quantitatively. The maximum amplitude of the magnetodielectric coefficient is acquired at the ferromagnetic resonance frequency, and the value is up to 1.2% with the magnetic field of 1500 Oe applied. The phenomena have been explained by the Faraday's electromagnetic induction of the precession of the magnetic moments in the electromagnetic field at the ferromagnetic resonance frequency.

Multiple minimally invasive Erbium:YAG laser mini-peels for skin rejuvenation: An objective assessment

PubMed Central

El-Domyati, Moetaz; El-Ammawi, Tarek S.; Medhat, Walid; Moawad, Osama; Mahoney, Mỹ G.; Uitto, Jouni

2012-01-01

Summary Background As the demand for minimally invasive rejuvenation is increasing, micro-peel resurfacing using Erbium:Yttrium Aluminium Garnet (Er:YAG ) laser 2940 nm has been reported for the treatment of photoaged skin without ablation of the epidermis. However, little is known about the efficacy and underlying histologic changes associated with this type of treatment. Aims The purpose of this study is to evaluate the clinical effect and objectively quantify the histological changes in response to multiple sessions of Er:YAG laser 2940 nm mini-peels. Patients and methods Six female volunteers of Fitzpatrick skin type III-IV and Glogau’s class I-III wrinkles were subjected to six microresurfacing peels at 2-week intervals using Er:YAG 2940 nm laser at sub-ablative fluences of 2 - 3 J/cm2 to treat periorbital rhytides. Quantitative evaluation of collagen types I, III and VII, newly synthesized collagen, total elastin and tropoelastin was performed by histochemistry and immunohistochemistry coupled with computerized morphometric analysis at base line, end of treatment, and three months post treatment. Results Compared to the base line, evaluation of volunteers revealed obvious clinical improvement in response to Er:YAG mini-peels. Collagen types I, III, and VII, as well as newly synthesized collagen, together with tropoelastin showed a statistically significant increase in response to treatment, while the mean level of total elastin was significantly decreased in response to treatment. However, this was followed by regression of improvement at 3 months post treatment, but was still better than baseline. Conclusions The present study revealed that multiple Er:YAG mini-peels is a promising treatment option for photoaging as it reverses the signs of photoaged skin with little downtime and side effects. However, to maintain the short term improvement achieved after treatment, continued Er:YAG 2940 nm laser mini-peels is required. PMID:22672276

Comparative study of induced changes in effective lens position and refraction after Nd:YAG laser capsulotomy according to intraocular lens design.

PubMed

Monteiro, Tiago; Soares, Andreia; Leite, Ricardo Dourado; Franqueira, Nuno; Faria-Correia, Fernando; Vaz, Fernando

2018-01-01

To evaluate and compare the changes in refraction and effective intraocular lens (IOL) position between a plate-haptic IOL and a c-loop single-piece IOL after neodymium-doped yttrium aluminium garnet (YAG) laser posterior capsulotomy. In a prospective study, anterior chamber depth and subjective refraction were measured in 110 pseudophakic eyes from 110 patients, before and 1 month after YAG laser capsulotomy. Patients were divided into 2 groups according to the IOL design: group 1 (plate-haptic acrylic hydrophilic AT LISA tri 839MP ® ) and group 2 (c-loop acrylic hydrophobic single-piece AcrySof ® SA60AT). Lens position was obtained through optical coherence biometry (Biograph WaveLight OB820 ® ). YAG laser capsulotomy was performed 37.8±9.8 months after surgery in group 1 and 40.6±8.6 months in group 2 ( p =0.125). Significant changes were found in the lens effective position after treatment in the 2 groups. The YAG posterior capsulotomy led to a change of anterior chamber depth in group 1 from 4.03±0.32 mm to 3.86±0.34 mm ( p =0.02) and in group 2 from 4.03±0.37 mm to 4.14±0.45 mm ( p =0.025). After YAG laser posterior capsulotomy, no significant changes were observed in mean spherical equivalent, sphere or cylinder for both groups ( p >0.05). YAG laser posterior capsulotomy can induce a significant change in the IOL position according to the IOL type; however, the refractive change after treatment is clinically insignificant.

15 mJ single-frequency Ho:YAG laser resonantly pumped by a 1.9 µm laser diode

NASA Astrophysics Data System (ADS)

Na, Q. X.; Gao, C. Q.; Wang, Q.; Zhang, Y. X.; Gao, M. W.; Ye, Q.; Li, Y.

2016-09-01

A 2.09 µm injection-seeded single-frequency Ho:YAG laser resonantly pumped by a 1.91 µm laser diode is demonstrated for the first time. The seed laser is a continuous wave (CW) Ho:YAG non-planar ring oscillator. 15.15 mJ single-frequency output energy is obtained from the injection-seeded Q-switched Ho:YAG laser, with a pulse repetition rate of 200 Hz and a pulse width of 109 ns. The half-width of the pulse spectrum is measured to be 4.19 MHz by using the heterodyne technique. The fluctuation of the center frequency of the single-frequency pulses is 1.52 MHz (root mean square (RMS)) in 1 h.

Heat treatment of transparent Yb:YAG and YAG ceramics and its influence on laser performance

NASA Astrophysics Data System (ADS)

Fujioka, Kana; Mochida, Tetsuo; Fujimoto, Yasushi; Tokita, Shigeki; Kawanaka, Junji; Maruyama, Momoko; Sugiyama, Akira; Miyanaga, Noriaki

2018-05-01

Composite transparent ceramic materials are promising for improving the performance of high-average-power lasers. A combination of room-temperature bonding via surface treatment by a fast atom beam and diffusion bonding via heating, which effectively controls the ion diffusion distance near the interface, makes the laser materials suitable for a variety of oscillator/amplifier. During the heat treatment of yttrium aluminum garnet (YAG) ceramics, the Si ions in the solid solution of the sintering aid incorporated within the grains were seen to segregate at the grain boundary, resulting in an increase of scattering sites. The number density and size of the scattering sites strongly depended on the post-heating temperature rather than the heating time. Specifically, heating at 1300 °C did not affect the transmittance of the YAG ceramic, whereas both the size and number of scattering sites substantially increased with a heat treatment at 1400 °C. The laser oscillation experiment using cryogenically-cooled Yb:YAG ceramics exhibited heating temperature dependence of the slope efficiency owing to the increasing scattering loss.

Harmonic technology versus neodymium-doped yttrium aluminium garnet laser and electrocautery for lung metastasectomy: an experimental study.

PubMed

Fiorelli, Alfonso; Accardo, Marina; Carelli, Emanuele; Del Prete, Assunta; Messina, Gaetana; Reginelli, Alfonso; Berritto, Daniela; Papale, Ferdinando; Armenia, Emilia; Chiodini, Paolo; Grassi, Roberto; Santini, Mario

2016-07-01

We compared the efficacy of non-anatomical lung resections with that of three other techniques: monopolar electrocautery; neodymium-doped yttrium aluminium garnet laser and harmonic technology. We hypothesized that the thermal damage with harmonic technology could be reduced because of the lower temperatures generated by harmonic technology compared with that of other devices. Initial studies were performed in 13 isolated pig lungs for each group. A 1.5-cm capsule was inserted within the lung to mimic a tumour and a total of 25 non-anatomical resections were performed with each device. The damage of the resected lung surface and of the tumour border were evaluated according to the colour (ranging from 0-pink colour to 4-black colour), histological (ranging from Score 0-no changes to Score 3-presence of necrotic tissue) and radiological (ranging from Score 0-isointense T2 signal at magnetic resonance imaging to Score 3-hyperintense T2 signal) criteria. A total of seven non-anatomical resections with harmonic technology were also performed in two live pigs to assess if ex vivo results could be reproducible in live pigs with particular attention to haemostatic and air-tightness properties. In the ex vivo lung, there was a statistical significant difference between depth of thermal damage (P < 0.0001) in electrocautery (1.3 [1.2-1.4]), laser (0.9 [0.6-0.9]) and harmonic (0.4 [0.3-0.5]) groups. Electrocautery had a higher depth of thermal damage compared with that of the laser (P = 0.01) and harmonic groups (P = 0.0005). The harmonic group had a less depth of thermal damage than that of the laser group (P = 0.01). Also, histological damages of tumour borders (P < 0.001) and resected lung surface (P < 0.001), radiological damage of tumour borders (P < 0.001) and resected lung surface (P < 0.001) and colour changes (P < 0.001) were statistically different between three study groups. Resections of in vivo pig lungs showed no bleeding; 2 of 7 cases of low air leaks were

The influence of erbium:yttrium-aluminum-garnet laser ablation with variable pulse width on morphology and microleakage of composite restorations.

PubMed

Navarro, Ricardo Scarparo; Gouw-Soares, Sheila; Cassoni, Alessandra; Haypek, Patricia; Zezell, Denise Maria; de Paula Eduardo, Carlos

2010-11-01

The objective of this study was to evaluate the influence of various pulse widths with different energy parameters of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mum) on the morphology and microleakage of cavities restored with composite resin. Identically sized class V cavities were prepared on the buccal surfaces of 54 bovine teeth by high-speed drill (n = 6, control, group 1) and prepared by Er:YAG laser (Fidelis 320A, Fotona, Slovenia) with irradiation parameters of 350 mJ/ 4 Hz or 400 mJ/2 Hz and pulse width: group 2, very short pulse (VSP); group 3, short pulse (SP); group 4, long pulse (LP); group 5, very long pulse (VLP). All cavities were filled with composite resin (Z-250-3 M), stored at 37 degrees C in distilled water, polished after 24 h, and thermally stressed (700 cycles/5-55 degrees C). The teeth were impermeabilized, immersed in 50% silver nitrate solution for 8 h, sectioned longitudinally, and exposed to Photoflood light for 10 min to reveal the stain. The leakage was evaluated under stereomicroscope by three different examiners, in a double-blind fashion, and scored (0-3). The results were analyzed by Kruskal-Wallis test (P > 0.05) and showed that there was no significant differences between the groups tested. Under scanning electron microscopy (SEM) the morphology of the cavities prepared by laser showed irregular enamel margins and dentin internal walls, and a more conservative pattern than that of conventional cavities. The different power settings and pulse widths of Er:YAG laser in cavity preparation had no influence on microleakage of composite resin restorations.

Neutron scattering study of yttrium iron garnet

NASA Astrophysics Data System (ADS)

Shamoto, Shin-ichi; Ito, Takashi U.; Onishi, Hiroaki; Yamauchi, Hiroki; Inamura, Yasuhiro; Matsuura, Masato; Akatsu, Mitsuhiro; Kodama, Katsuaki; Nakao, Akiko; Moyoshi, Taketo; Munakata, Koji; Ohhara, Takashi; Nakamura, Mitsutaka; Ohira-Kawamura, Seiko; Nemoto, Yuichi; Shibata, Kaoru

2018-02-01

The nuclear and magnetic structure and full magnon dispersions of yttrium iron garnet Y3Fe5O12 have been studied using neutron scattering. The refined nuclear structure is distorted to a trigonal space group of R 3 ¯ . The highest-energy dispersion extends up to 86 meV. The observed dispersions are reproduced by a simple model with three nearest-neighbor-exchange integrals between 16 a (octahedral) and 24 d (tetrahedral) sites, Ja a, Ja d, and Jd d, which are estimated to be 0.00 ±0.05 , -2.90 ±0.07 , and -0.35 ±0.08 meV, respectively. The lowest-energy dispersion below 14 meV exhibits a quadratic dispersion as expected from ferromagnetic magnons. The imaginary part of q -integrated dynamical spin susceptibility χ″(E ) exhibits a square-root energy dependence at low energies. The magnon density of state is estimated from χ″(E ) obtained on an absolute scale. The value is consistent with the single chirality mode for the magnon branch expected theoretically.

Morphological and ultrastructural comparative analysis of bone tissue after Er:YAG laser and surgical drill osteotomy.

PubMed

Panduric, Dragana Gabric; Juric, Ivona Bago; Music, Svetozar; Molčanov, Krešimir; Sušic, Mato; Anic, Ivica

2014-07-01

The purpose of this study was to analyze morphological, chemical, and crystallographic changes of bone tissue after osteotomy performed with an erbium:yttrium-aluminium-garnet (Er:YAG) laser and a low speed pilot drill. Bone blocks were prepared from porcine ribs, and on each block, two tunnel preparations were performed using the Er:YAG laser (pulse energy: 1000 mJ, pulse duration: 300 μs, pulse repetition rate: 20 Hz) or the low-speed surgical pilot drill. The morphological changes of the cortical and the spongious surface of the tunnel preparations were analyzed under the field emission scanning electron microscopy (FE-SEM) at low and high resolution. The distribution and the level of chemical elements in the treated surfaces were evaluated by qualitative and semiquantitative energy dispersive x-ray analysis (SEM-EDX). Diffraction x-ray analysis was used to detect any differences and thermally induced modifications of hydroxyapatite crystals. FE-SEM revealed sharp edges of the Er:YAG preparations, with empty intertrabecular spaces and no signs of carbonization. In the drill group, the surface of the preparations was smooth, completely covered with smear layer and microcracks, and with hairy-like irregularities on the edges. SEM-EDX analysis did not reveal any differences in the number of specific chemical elements between the laser and the drill group. There were no thermally induced modifications of hydroxyapatite crystal structure in the bone tissue in either group. The Er:YAG laser ablation did not cause any chemical or crystallographic changes of the bone tissue. Compared with the drill, Er:YAG laser created well-defined edges of the preparations, and cortical bone had no smear layer.

Electrical properties of epitaxial yttrium iron garnet ultrathin films at high temperatures

NASA Astrophysics Data System (ADS)

Thiery, N.; Naletov, V. V.; Vila, L.; Marty, A.; Brenac, A.; Jacquot, J.-F.; de Loubens, G.; Viret, M.; Anane, A.; Cros, V.; Ben Youssef, J.; Beaulieu, N.; Demidov, V. E.; Divinskiy, B.; Demokritov, S. O.; Klein, O.

2018-02-01

We report a study on the electrical properties of 19-nm-thick yttrium iron garnet (YIG) films grown by liquid phase epitaxy on gadolinium gallium garnet single crystal. The electrical conductivity and Hall coefficient are measured in the high-temperature range [300,400] K using a Van der Pauw four-point probe technique. We find that the electrical resistivity decreases exponentially with increasing temperature following an activated behavior corresponding to a band gap of Eg≈2 eV. It drops to values about 5 ×103Ω cm at T =400 K, thus indicating that epitaxial YIG ultrathin films behave as large gap semiconductors. We also infer the Hall mobility, which is found to be positive (p type) at 5 cm2V-1sec-1 and almost independent of temperature. We discuss the consequence for nonlocal spin transport experiments performed on YIG at room temperature and demonstrate the existence of electrical offset voltages to be disentangled from pure spin effects.

Treatment of hyperplastic inferior nasal turbinates by means of a Ho:YAG laser

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Leunig, Andreas; Janda, P.; Rosler, P.; Grevers, G.; Baumgartner, Reinhold

1999-06-01

Although the successful use of the Ho:YAG laser in nasal turbinate surgery had been reported no clinical study had been performed to assess the clinical outcome in longterm. By means of a pulsed Ho:YAG laser emitting at λ=2080nm (1J/pulse, 3-8 Hz) 57 patients suffering from nasal obstruction due to allergic rhinitis and vasomotoric rhinitis were treated under local anesthesia. The study was conducted by standardized questionnaire, photo documentation, allergy test, mucocilliar test, rhinomanometry, radiology and histology. Within 2 weeks after laser treatment a significant improvement of nasal airflow correlating to the extent of the ablated turbinate tissue could be determined. This effect lasted up until 1 year post treatment resulting in an improved quality of life in more than 80 percent of the patients. Side effects like nasal dryness and pain were rare (<4%), no immediate complications were observed. The total treatment time takes 3-8 min and nasal packing was not necessary after the laser procedure. In conclusion Ho:YAG laser treatment can be performed as an outpatient procedure under local anesthesia with excellent ablation of soft tissue in a short treatment time with promising results.

Comparative Study of Diode Laser Versus Neodymium-Yttrium Aluminum: Garnet Laser Versus Intense Pulsed Light for the Treatment of Hirsutism

PubMed Central

Puri, Neerja

2015-01-01

Introduction: Lasers are widely used for the treatment of hirsutism. But the choice of the right laser for the right skin type is very important. Before starting with laser therapy, it is important to assess the skin type, the fluence, the pulse duration and the type of laser to be used. Aims: To compare the efficacy and side effects of Diode laser, Neodymium-yttrium aluminum — garnet (Nd: YAG) laser and intense pulsed light (IPL) on 30 female patients of hirsutism. Materials and Methods: Thirty female patients with hirsutism were selected for a randomised controlled study. The patients were divided into three groups of 10 patients each. In group I patients diode laser was used, in group II patients long pulsed Nd: YAG laser was used and in group III, IPL was used. The patients were evaluated and result graded according to a 4-point scale as excellent, >75% reduction; good, 50-75% reduction; fair; 25-50% reduction; and poor, <25% reduction in hair density. Results: It was seen that the percentage of hair reduction after two sessions of treatment was maximum (40%) in the diode laser group, followed by 35% hair reduction in the Nd: Yag laser group and 10% hair reduction in the IPL group. The percentage of hair reduction after four sessions of treatment was maximum (64%) in the diode laser group, followed by 62% hair reduction in the Nd: Yag laser group and 48% hair reduction in the IPL group. The percentage of hair reduction after eight sessions of treatment was maximum (92%) in the diode laser group, followed by 90% hair reduction in the Nd: YAG group and 70% hair reduction in the IPL group. Conclusions: To conclude for the Indian skin with dark hairs, the diode laser still stands the test of time. But, since the diode laser has a narrow margin of safety, proper pre and post-procedure cooling is recommended. Although, the side effects of Nd: YAG laser are less as compared to the diode laser, it is less efficacious as compared to the diode laser. PMID:26157309

Genotoxic effects of 1064-nm Nd:YAG and 532-nm KTP lasers on fibroblast cell cultures.

PubMed

Senturk, N; Bedir, A; Bilgici, B; Aydin, F; Okuyucu, A; Ozmen, Z C; Turanli, A Y

2010-07-01

Several different laser types are used in cutaneous surgery. The neodymium:yttrium-aluminium-garnet (Nd:YAG) and frequency-doubled Nd:YAG (KTP, potassium titanyl phosphate) lasers are widely used in dermatology. To investigate the possible genotoxic effects on fibroblasts of irradiation with a 1064-nm Nd:YAG laser and a 532-nm KTP laser. Fibroblast cell cultures were exposed to each of the lasers, using 10-mm spot size at 60 ms pulse duration with 10, 20, 40 J/cm(2) and 3, 6, 12 J/cm(2) fluences, respectively. Fibroblasts in passages 1-6 were used. During laser irradiation, 96-well microplate cultures were kept on a cooling block and transported on ice and in the dark, and processed immediately for single-cell gel electrophoresis (SCGE) assay (also known as a comet assay). DNA damage was determined by computerized assessment of comet assay. There was increasing damage with increasing numbers of passages. For the Nd:YAG laser, the greatest damage occurred on passages 5 and 6, whereas the greatest damage appeared at passages 3 and 4 for KTP and returned to baseline at passages 5 and 6. Damage also increased with each dose increment for both wavelengths. At the highest dose for both wavelengths (Nd:YAG 40 J/cm(2) and KTP 12 J/cm(2)), damage was higher with the Nd:YAG laser. Different patterns of cellular damage were seen for different cell-culture passages, treatment doses, and laser wavelengths. These dose ranges are generally used for the treatment of vascular and pigmented lesions and for rejuvenation purposes. As replicative ageing or cell senescence is one of the critical factors determining the extent of cell damage induced by laser therapy, these results may have important implications for clinical practice.

Mechanical properties and molecular structure analysis of subsurface dentin after Er:YAG laser irradiation.

PubMed

He, Zhengdi; Chen, Lingling; Hu, Xuejuan; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Ruan, Shuangchen

2017-10-01

The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS). The dentin 5-50µm depth beneath the lased surface was determined as testing area. Two-way analysis of variance (ANOVA) were used to compare the mechanical values between lased and untreated subsurface dentin (P = 0.05). A laser affected subsurface dentin layer after Er:YAG laser treatment is present. The laser irradiation is considered to decrease the mechanical properties in the superficial subsurface layer (<15µm deep). There was no significant difference in nanohardness and Young's modulus between lased subsurface dentin and untreated dentin (p > 0.05) under the depth of 15µm. However, the dentin at 5µm and 10µm depth beneath the lased surface exhibited significantly lower (~ 47.8% and ~ 33.6% respectively) hardness (p < 0.05). Er:YAG laser irradiation affected both mineral and organic components in subsurface dentin layer, a higher degree of crystallinity and reduced organic compounds occurred in the lased subsurface dentin. Under the tested laser parameters, Er:YAG laser irradiation causes lower mechanical values and reduction of organic components in subsurface dentin, which has deleterious effects on resin adhesion to this area. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Surface Thermometry of Energetic Materials by Laser-Induced Fluorescence

DTIC Science & Technology

1989-09-01

at 34 yttrium- aluminum -garnet (Dy:YAG). The simplified energy diagram of Dy:YAG is shown in Fig. 1. Absorbed laser light (at 355 nrm) can 5 excite the...the thermometric technique on a surface similar to that of an energetic material, a thermal-setting plastic supplied by Buehler, Ltd., was employed...temperature over the temperature range of interest. The rare-earth ion dysprosium (Dy) doped into a yttrium- aluminum -garnet (YAG) crystal was I determined

Evaluation of six holmium:YAG optical fibers for ureteroscopy: What's new in 2009?

NASA Astrophysics Data System (ADS)

Knudsen, Bodo E.; Teichman, Joel M. H.

2010-02-01

The holmium:yttrium aluminum garnet (YAG) laser is the gold standard laser for intracorporeal lithotripsy.1 Optical fibers are utilized to transmit laser energy to the surface of a stone for fragmentation via a predominant photothermal mechanism.2 Previous work has demonstrated that performance characteristics of holmium:YAG optical fibers used for laser lithotripsy varies. Performance may difference not only between fibers made by different manufacturers but also between individual fibers produced by the same manufacturer.3,4 Fiber failure with bending, such as during lower pole ureterorenoscopy, can lead to catastrophic endoscope damage resulting in costly repair. Manufacturers continue to develop new holmium:YAG optical fibers. In this study we evaluate a series of newly commercially available fibers using a previously designed testing protocol. This study was designed to determine the performance and threshold for failure of six newly available holmium:YAG laser fibers from Cook Medical and Fibertech Gmbh. We hypothesize that fiber performance will continue to vary amongst different holmium:YAG optical fibers.

Microhardness and morphological changes induced by Nd:Yag laser on dental enamel: an in vitro study.

PubMed

Bedini, Rossella; Manzon, Licia; Fratto, Giovanni; Pecci, Raffaella

2010-01-01

The aim of this work was a scanning electron microscopy (SEM) evaluation of the hardness and morphological changes of enamel irradiated by neodymium: yttrium aluminium garnet (Nd:YAG) laser with different energy levels. Twenty-eight human teeth samples were divided into 4 groups: control, where enamel surface was not lased, and 3 test treated with 3 different levels of energy power 0.6, 1.2 and 2.4 Watt, respectively. In each group, 5 samples underwent Vickers micro-hardness test and 2 samples were processed for SEM. No significant differences between treated and non treated samples were found by micro-hardness test. However, by SEM, test samples showed a rougher enamel surface than control. Specifically, the 0.6 Watt treated samples showed vertical scratches and glass-like areas, while in the other 2 groups enamel surface was covered by craters and cracks. These findings suggest that enamel should be lased at a low energy level to preserve its integrity and reduce demineralization, and thus for dental caries prevention purposes; while high energy level creates a retentive surface suitable for sealant or composite anchorage.

Comparative study of induced changes in effective lens position and refraction after Nd:YAG laser capsulotomy according to intraocular lens design

PubMed Central

Monteiro, Tiago; Soares, Andreia; Leite, Ricardo Dourado; Franqueira, Nuno; Faria-Correia, Fernando; Vaz, Fernando

2018-01-01

Purpose To evaluate and compare the changes in refraction and effective intraocular lens (IOL) position between a plate-haptic IOL and a c-loop single-piece IOL after neodymium-doped yttrium aluminium garnet (YAG) laser posterior capsulotomy. Methods In a prospective study, anterior chamber depth and subjective refraction were measured in 110 pseudophakic eyes from 110 patients, before and 1 month after YAG laser capsulotomy. Patients were divided into 2 groups according to the IOL design: group 1 (plate-haptic acrylic hydrophilic AT LISA tri 839MP®) and group 2 (c-loop acrylic hydrophobic single-piece AcrySof® SA60AT). Lens position was obtained through optical coherence biometry (Biograph WaveLight OB820®). Results YAG laser capsulotomy was performed 37.8±9.8 months after surgery in group 1 and 40.6±8.6 months in group 2 (p=0.125). Significant changes were found in the lens effective position after treatment in the 2 groups. The YAG posterior capsulotomy led to a change of anterior chamber depth in group 1 from 4.03±0.32 mm to 3.86±0.34 mm (p=0.02) and in group 2 from 4.03±0.37 mm to 4.14±0.45 mm (p=0.025). After YAG laser posterior capsulotomy, no significant changes were observed in mean spherical equivalent, sphere or cylinder for both groups (p>0.05). Conclusion YAG laser posterior capsulotomy can induce a significant change in the IOL position according to the IOL type; however, the refractive change after treatment is clinically insignificant. PMID:29593378

Study on growth techniques and macro defects of large-size Nd:YAG laser crystal

NASA Astrophysics Data System (ADS)

Quan, Jiliang; Yang, Xin; Yang, Mingming; Ma, Decai; Huang, Jinqiang; Zhu, Yunzhong; Wang, Biao

2018-02-01

Large-size neodymium-doped yttrium aluminum garnet (Nd:YAG) single crystals were grown by the Czochralski method. The extinction ratio and wavefront distortion of the crystal were tested to determine the optical homogeneity. Moreover, under different growth conditions, the macro defects of inclusion, striations, and cracking in the as-grown Nd:YAG crystals were analyzed. Specifically, the inclusion defects were characterized using scanning electron microscopy and energy dispersive spectroscopy. The stresses of growth striations and cracking were studied via a parallel plane polariscope. These results demonstrate that improper growth parameters and temperature fields can enhance defects significantly. Thus, by adjusting the growth parameters and optimizing the thermal environment, high-optical-quality Nd:YAG crystals with a diameter of 80 mm and a total length of 400 mm have been obtained successfully.

New laser treatment approaches for benign prostatic hyperplasia.

PubMed

Fried, Nathaniel M

2007-01-01

The recent introduction of higher power 100 W holmium:yttrium-aluminum-garnet (Ho:YAG) and 80 W potassium titanyl phosphate lasers for rapid incision and vaporization of the prostate has resulted in renewed interest in the use of lasers for treatment of benign prostatic hyperplasia (BPH). Although long-term studies are still lacking, short-term results demonstrate that these procedures are at least as safe and effective in relieving BPH symptoms as transurethral resection of the prostate and may provide reduced morbidity. Other laser techniques, such as interstitial laser coagulation and contact laser vaporization of the prostate, have lost popularity due to complications with increased catheterization time, irritative symptoms, and infection rates. Although Ho:YAG laser enucleation of the prostate is more difficult to learn and a slower procedure than potassium titanyl phosphate laser vaporization, the Ho:YAG laser is currently the most proven laser technique for BPH treatment. This article reviews the latest developments in laser treatment of BPH over the past 2 years and provides a view toward the future of lasers in the treatment of BPH.

Laser intervention on trabeculo-Descemet's membrane after resistant viscocanalostomy: Selective 532 nm gonioreconditioning or conventional 1064 nm neodymium-doped yttrium aluminum garnet laser goniopuncture?

PubMed Central

Sabur, Huri; Baykara, Mehmet; Can, Basak

2016-01-01

Purpose: To compare the results of conventional 1064 nm neodymium-doped yttrium-aluminum garnet laser goniopuncture (Nd:YAG-GP) and selective 532 nm Nd:YAG laser (selective laser trabeculoplasty [SLT]) gonioreconditioning (GR) on trabeculo-Descemet's membrane in eyes resistant to viscocanalostomy surgery. Methods: Thirty-eight eyes of 35 patients who underwent laser procedure after successful viscocanalostomy surgery were included in the study. When postoperative intraocular pressure (IOP) was above the individual target, the eyes were scheduled for laser procedure. Nineteen eyes underwent 532 nm SLT-GR (Group 1), and the remaining 19 eyes underwent conventional 1064 nm Nd:YAG-GP (Group 2). IOPs before and after laser (1 week, 1 month, 3 months, 6 months, 1 year, and last visit), follow-up periods, number of glaucoma medications, and complications were recorded for both groups. Results: Mean times from surgery to laser procedures were 17.3 ± 9.6 months in Group 1 and 13.0 ± 11.4 months in Group 2. Mean IOPs before laser procedures were 21.2 ± 1.7 mmHg in Group 1 and 22.8 ± 1.9 mmHg in Group 2 (P = 0.454). Postlaser IOP measurements of Group 1 were 12.1 ± 3.4 mmHg and 13.8 ± 1.7 mmHg in the 1st week and last visit, respectively; in Group 2, these measurements were 13.6 ± 3.7 mmHg and 14.9 ± 4.8 mmHg, respectively. There were statistically significant differences (P < 0.001) in IOP reduction at all visits in both groups; the results of the two groups were similar (P > 0.05). Mean follow-up was 16.6 ± 6.4 months after SLT-GR and 18.9 ± 11.2 months after Nd:YAG-GP. Conclusions: While conventional Nd:YAG-GP and SLT-GR, a novel procedure, are both effective choices in eyes resistant to viscocanalostomy, there are fewer complications with SLT-GR. SLT-GR can be an alternative to conventional Nd:YAG-GP. PMID:27688277

Development of flashlamp-pumped Q-switched Ho:Tm:Cr:YAG lasers for mid-infrared LIDAR application

NASA Technical Reports Server (NTRS)

Choi, Young S.; Kim, Kyong H.; Whitney, Donald A.; Hess, Robert V.; Barnes, Norman P.; Bair, Clayton H.; Brockman, Philip

1989-01-01

A flashlamp-pumped 2.1 micron Ho:Tm:Cr:YAG laser was studied for both normal mode and Q-switched operations under a wide variety of experimental conditions in order to optimize performance. Laser output energy, slope efficiency, threshold and pulselength were determined as a function of operating temperature, output mirror reflectivity, input electrical energy and Q-switch opening time. The measured normal-mode laser thresholds of a Ho(3+) (0.45 atomic percent):Tm(3+) (2.5 atomic percent):Cr(3+) (0.8 atomic percent):YAG crystal ranged form 26 to 50 J between 120 and 200 K with slope efficiencies up to 0.36 percent with a 60 percent reflective output mirror. Under Q-switched operation the slope efficiency was 90 percent of the normal-mode result. Development of solid state lasers with Ho(3+), Tm(3+) and/or Er(3+) doped crystals has been pursued by NASA for eye-dafe mid-infrared LIDAR (light detection and ranging) application. As a part of the project, the authors have been working on evaluating Ho(3+):Tm(3+):Cr(3+):YAG crystals for normal-mode and Q-switched 2.1 micron laser operations in order to determine an optimum Tm(3+) concentration under flashlamp pumping conditions. Lasing properties of the Ho(3+) in the mid-infrared region have been studied by many research groups since the early 1960's. However, the technology of those lasers is still premature for lidar application. In order to overcome the inefficiency related to narrow absorption bands of the Ho(3+), Tm(3+) and Er(3+), the erbium has been replaced by chromium. The improvement in flashlamp-pumped Ho(3+) laser efficiency has been demonstrated recently by several research groups by utilizing the broad absorption spectrum of Cr(3+) which covers the flashlamp's emission spectrum. Efficient energy transfer to the Tm(3+) and then the Ho(3+) occurs subsequently. It is known that high Tm(3+) concentration and low Ho(3+) concentration are preferred to achieve a quantum efficiency approaching two and to avoid

[Evaluation of root canal isthmus debridement efficacy of Er:YAG laser in combination with sodium hypochlorite].

PubMed

Zhou, Meng-Qi; Wang, Hao-Ming; Xiao, Jia-Qi; Hong, Jin

2016-10-01

To histologically evaluate the efficacy of sodium hypochlorite (NaClO) in combination with Er:YAG (erbium-doped yttrium aluminium garnet) laser in dissolving necrotic tissue and cleaning root canals as well as canal isthmuses. After scanned by cone-beam CT (CBCT), 50 well-prepared premolars with root canal isthmuses were selected and randomly assigned into 5 groups. They were subsequently subjected to different regimens as followed: group A-irrigated with 1% NaClO for 1 minute, group B- irradiated by Er:YAG laser at 0.5 W combined with 1% NaClO irrigation for 1 minute, group C- irradiated by Er:YAG laser at 1.0 W combined with 1% NaClO irrigation for 1 minute, group D- irradiated by Er:YAG laser at 2.0 W combined with 1% NaClO irrigation for 1 minute,group E- negative control. After histological preparation and staining, the cross-sections were evaluated for percentage of tissue removal from root canals and isthmuses. The cleanliness values were calculated using SPSS 13.0 software package. The mean percentage of root canals in group A, B, C and D was 95.24%, 96.53%、97.63% and 98.22%, respectively, and the mean percentage of isthmuses was 16.50%, 51.48%, 52.56% and 53.83%, respectively. The mean percentage of root canal and isthmus cleanliness values were significantly higher in group B, C and D (P<0.05) than that in group A. There was no significant differences of root canal and isthmus cleanliness among group B, C and D. Er:YAG laser combined with 1% NaClO irrigation may be used effectively in root canal and root canal isthmus cleanliness as a new method.

Evaluation of crystalline changes and resistance to demineralization of the surface of human dental enamel treated with Er:YAG laser and fluoride using x-ray diffraction analysis and Vickers microhardness

NASA Astrophysics Data System (ADS)

Behroozibakhsh, Marjan; Shahabi, Sima; Ghavami-Lahiji, Mehrsima; Sadeghian, Safura; Sadat Faal Nazari, Neda

2018-06-01

This study aimed to investigate the changes in crystalline structure and resistance to demineralization of human dental surface enamel treated with erbium-doped yttrium aluminium garnet laser (Er:YAG) laser and fluoride. The enamel surfaces were divided into four groups according to the treatment process including, (L): irradiated with Er:YAG; (F): treated with acidulated phosphate fluoride gel (LF): Pre-irradiated surfaces with Er:YAG subjected to acidulated phosphate fluoride gel and (FL): laser irradiation was performed on the fluoridated enamel surface. Before and after the treatment procedure, the samples were evaluated using X-ray diffraction, scanning electron microscope (SEM) and the Vickers microhardness test. The surface microhardness values also were measured after a pH-cycling regime and acid challenge. The a-axis of all lased groups was contracted after treatment procedure. Measurement of the area under the peaks showed the highest crysallinity in the FL group. The hardness values of all laser treated samples significantly reduced after treatment procedure compared to the F group (p  ⩽  0.001). The morphological observations showed remarkable changes on the lased enamel surfaces including cracks, craters and exposed prisms. These findings suggest, irradiation of the Er:YAG laser accompanying with fluoride application can induce some beneficial crystalline changes regarding the acid-resistance properties of enamel, however, the craters and cracks produced by laser irradiation can promote enamel demineralization and consequently the positive effects of the Er:YAG laser will be eliminated.

High-efficiency cavity-dumped micro-chip Yb:YAG laser

NASA Astrophysics Data System (ADS)

Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

2014-09-01

High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

Adjunctive clinical effect of a water-cooled Nd:YAG laser in a periodontal maintenance care programme: a randomized controlled trial.

PubMed

Slot, Dagmar E; Timmerman, Mark F; Versteeg, Paula A; van der Velden, Ubele; van der Weijden, Fridus A

2012-12-01

Various laser systems are currently available for intra-oral use. Neodymium:Yttrium-Aluminium Garnet lasers(Nd:YAG) have been approved by the US Food and Drug Administration for soft tissue treatment in the oral cavity. The aim of this study was to test whether the use of a water-cooled Nd:YAG laser during a maintenance care programme as an adjunct to supragingival and subgingival debridement (scaling and root planing, SRP) with hand and ultrasonic instruments results in clinical improvement compared with SRP alone. This study was an examiner-blind, randomized and controlled clinical trial using a split-mouth design. Thirty subjects were selected, originally diagnosed with moderate to severe generalized periodontitis, following a periodontal maintenance care programme (PMC). Immediately after SRP in two randomly assigned contra-lateral quadrants, all pockets ≥5 mm were additionally treated with a Nd:YAG laser (1064 nm, 4W, 250-μsec pulse). Clinical assessments [probing pocket depth PPD, bleeding on pocket probing (BOPP)] were performed pre-treatment and at 6 months. Based on these assessments, the periodontal inflamed surface area (PISA) was calculated. At 6 months, the clinical parameters had significantly improved for both regimens. No statistically significant differences between treatment modalities were observed for PPD and BOPP scores at any time. PISA scores supported these findings. In residual pockets ≥5 mm, treated in a PMC, the adjunctive use of an Nd:YAG laser does not provide a clinically significant additional advantage. © 2012 John Wiley & Sons A/S.

Urologic laser types and instrumentation.

PubMed

Natalin, Ricardo A; Phillips, Courtney K; Clayman, Ralph V; Landman, Jaime

2008-11-01

Though the primary role of lasers in urology has always been in the treatment of urolithiasis, there are several other indications for their use. There are many different types of lasers currently available, each with unique properties conducive to treating certain disorders. As such, it is critical that today's urologist understands each laser's characteristics in order to optimize patient selection and treatment. The lasers which are primarily used in urologic applications include the carbon dioxide (CO2) laser; the Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG); the Potassium Titanyl Phosphate (KTP) laser and the Holmium:YAG (Ho:YAG) laser. This review focuses on the unique characteristics of each of these lasers as well as the instrumentation needed utilize and deploy these tools in the urinary tract.

A Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser

NASA Astrophysics Data System (ADS)

Wang, Y. P.; Dai, T. Y.; Wu, J.; Ju, Y. L.; Yao, B. Q.

2018-06-01

We report the acousto-optically Q-switched Ho:YAG laser with double anti-misalignment corner cubes pumped by a diode-pumped Tm:YLF laser. In the continuous-wave operation of Ho:YAG laser, the maximum s-polarized output power of 3.2 W at 2090.3 nm was obtained under the absorbed pump power of 12.9 W by rotating the fast axis of quarter-wave plate to change the output transmission of laser cavity. The corresponding optical-to-optical conversion efficiency was 24.8% and the slope efficiency was 55.7%. When one of the corner cubes was rotated to 11.8° around vertical direction or 6.7° around horizontal direction, the laser could still operate stably. For the Q-switched operation, the pulse energy of Ho:YAG laser was 9.9 mJ with a pulse width of 53 ns at the repetition rate of 100 Hz, resulting in a peak power of 186.8 kW. The beam quality factor M2 of Ho:YAG laser was 1.3.

Revising the magnetic structure and dynamics of Yttrium Iron Garnet

NASA Astrophysics Data System (ADS)

Princep, Andrew; Boothroyd, Andrew; Ewings, Russell; Ward, Simon; Dubs, Carsten

Yttrium iron garnet (YIG) is the `miracle material' of microwave magnetics. Since its synthesis by Geller and Gilleo in 1957, it is widely acknowledged to have contributed more to the understanding of electronic spin-wave and magnon dynamics than any other substance. Its astonishingly narrow excitation linewidth allows magnon propagation to be observed over centimetre distances, making it both a superior model system for the experimental study of fundamental aspects of microwave magnetic dynamics and an ideal platform for the development of microwave magnetic technologies. Our experiments on a large, pristine single crystal at the ISIS facility using both diffraction and time-of-flight spectroscopy have provided new results on both the magnetic structure and the excitation spectrum, which revise nearly 60 years of scientific research and will be essential insights for the fledgling scientific field of Magnonics. EPSRC, UK.

Resonantly pumped high efficiency Ho:YAG laser.

PubMed

Shen, Ying-Jie; Yao, Bao-Quan; Duan, Xiao-Ming; Dai, Tong-Yu; Ju, You-Lun; Wang, Yue-Zhu

2012-11-20

High-efficient CW and Q-switched Ho:YAG lasers resonantly dual-end-pumped by two diode-pumped Tm:YLF lasers at 1908 nm were investigated. A maximum slope efficiency of 74.8% in CW operation as well as a maximum output power of 58.7 W at 83.2 W incident pump power was achieved, which corresponded to an optical-to-optical conversion efficiency of 70.6%. The maximum pulse energy of 2.94 mJ was achieved, with a 31 ns FWHM pulse width and a peak power of approximately 94.7 kW.

High-energy directly diode-pumped Q-switched 1617 nm Er:YAG laser at room temperature.

PubMed

Wang, Mingjian; Zhu, Liang; Chen, Weibiao; Fan, Dianyuan

2012-09-01

We describe high-energy Erbium-doped yttrium aluminum garnet (Er:YAG) lasers operating at 1617 nm, resonantly pumped using 1532 nm fiber-coupled laser diodes. A maximum continuous wave output power of 4.3 W at 1617 nm was achieved with an output coupler of 20% transmission under incident pump power of 29.7 W, resulting in an optical conversion of 14% with respect to the incident pump power. In Q-switched operation, the pulse energy of 11.8 mJ at 100 Hz pulse repetition frequency and 81 ns pulse duration was obtained. This energy is the highest pulse energy reported for a directly diode-pumped Q-switched Er:YAG laser operating at 1617 nm.

Application of Atomic Fluorescence to Measurement of Combustion Temperature in Solid Propellants.

DTIC Science & Technology

1986-12-04

into a cytal (yttrium- aluminum -garnet) is shown to be an ideal seed, the fluoresce. f which is stimulated by the ultra-violet output of a Nd:YAG...been successfully employed in atmospheric flames for making thermometric measurements. However, because of the amorphous nature of energetic materials...be determined. R. 6 A .6 An example of this type of behavior is found in trivalent dysprosium, doped at 3% in yttrium- aluminum -garnet (Dy+3 :YAG

Containment-enhanced Ho:YAG photofragmentation of soft tissues

NASA Astrophysics Data System (ADS)

Christens-Barry, William A.; Guarnieri, Michael; Carson, Benjamin S.

1998-01-01

Laser surgery of soft tissue can exploit the power of brief, intense pulses of light to cause localized disruption of tissue with minimal effect upon surrounding tissue. In particular, studies of Ho:YAG laser surgery have shown that the effects of cavitation upon tissues and bone depend upon the physical composition of structures in the vicinity of the surgical site. For photofragmentation of occluding structures within catheters and other implant devices, it is possible to exploit the particular geometry of the catheter to amplify the effects of photofragmentation beyond those seen in bulk tissue. A Ho:YAG laser was used to photofragment occlusive material (tissue and tissue analogs) contained in glass capillary tubing and catheter tubing of the kind used in ventricular shunt implants for the management of hydrocephalus. Occluded catheters obtained from patient explants were also employed. Selection of operational parameters used in photoablation and photofragmentation of soft tissue must consider the physical composition and geometry of the treatment site. In the present case, containment of the soft tissue within relatively inelastic catheters dramatically alters the extent of photofragmentation relative to bulk (unconstrained) material. Our results indicate that the disruptive effect of cavitation bubbles is increased in catheters, due to the rapid displacement of material by cavitation bubbles comparable in size to the inner diameter of the catheter. The cylindrical geometry of the catheter lumen may additionally influence the propagation of acoustic shock waves that result from the collapse of the condensing cavitation bubbles.

Comparison of a long-pulse Nd:YAG laser and a combined 585/1,064-nm laser for the treatment of acne scars: a randomized split-face clinical study.

PubMed

Min, Seong U K; Choi, Yu Sung; Lee, Dong Hun; Yoon, Mi Young; Suh, Dae Hun

2009-11-01

Nonablative laser is gaining popularity because of the low risk of complications, especially in patients with darker skin. To compare the efficacy and safety of a long-pulse neodymium-doped yttrium aluminium garnet (Nd:YAG) laser and a combined 585/1,064-nm laser for the treatment of acne scars. Nineteen patients with mild to moderate atrophic acne scars received four long-pulse Nd:YAG laser or combined 585/1,064-nm laser treatment sessions at fortnightly intervals. Treatments were administered randomly in a split-face manner. Acne scars showed mild to moderate improvement, with significant Echelle d'évaluation clinique des cicatrices d'acné (ECCA) score reductions, after both treatments. Although intermodality differences were not significant, combined 585/1,064-nm laser was more effective for deep boxcar scars. In patients with combined 585/1,064-nm laser-treated sides that improved more than long-pulse Nd:YAG laser-treated sides, ECCA scores were significantly lower for combined 585/1,064-nm laser treatment. Histologic evaluations revealed significantly greater collagen deposition, although there was no significant difference between the two modalities. Patient satisfaction scores concurred with physicians' evaluations. Both lasers ameliorated acne scarring with minimal downtime. In light of this finding, optimal outcomes might be achieved when laser treatment types are chosen after considering individual scar type and response.

Impact of pulse duration on Ho:YAG laser lithotripsy: fragmentation and dusting performance.

PubMed

Bader, Markus J; Pongratz, Thomas; Khoder, Wael; Stief, Christian G; Herrmann, Thomas; Nagele, Udo; Sroka, Ronald

2015-04-01

In vitro investigations of Ho:YAG laser-induced stone fragmentation were performed to identify potential impacts of different pulse durations on stone fragmentation characteristics. A Ho:YAG laser system (Swiss LaserClast, EMS S.A., Nyon, Switzerland) with selectable long or short pulse mode was tested with regard to its fragmentation and laser hardware compatibility properties. The pulse duration is depending on the specific laser parameters. Fragmentation tests (hand-held, hands-free, single-pulse-induced crater) on artificial BEGO stones were performed under reproducible experimental conditions (fibre sizes: 365 and 200 µm; laser settings: 10 W through combinations of 0.5, 1, 2 J/pulse and 20, 10, 5 Hz, respectively). Differences in fragmentation rates between the two pulse duration regimes were detected with statistical significance for defined settings. Hand-held and motivated Ho:YAG laser-assisted fragmentation of BEGO stones showed no significant difference between short pulse mode and long pulse mode, neither in fragmentation rates nor in number of fragments and fragment sizes. Similarly, the results of the hands-free fragmentation tests (with and without anti-repulsion device) showed no statistical differences between long pulse and short pulse modes. The study showed that fragmentation rates for long and short pulse durations at identical power settings remain at a comparable level. Longer holmium laser pulse duration reduces stone pushback. Therefore, longer laser pulses may result in better clinical outcome of laser lithotripsy and more convenient handling during clinical use without compromising fragmentation effectiveness.

Clinical development of holmium:YAG laser prostatectomy

NASA Astrophysics Data System (ADS)

Kabalin, John N.

1996-05-01

Holmium:YAG (Ho:YAG) laser vaporization and resection of the prostate offers advantages in immediate tissue removal compared to the Neodymium:YAG (Nd:YAG) laser. Ongoing development of appropriate operative techniques and Ho:YAG laser delivery systems suitable for endoscopic prostate surgery, including side-firing optical delivery fibers, have facilitated this approach. We performed Ho:YAG laser prostatectomy in 20 human subjects, including 2 men treated immediately prior to radical prostatectomy to assess Ho:YAG laser effects in the prostate. A total of 18 men were treated in an initial clinical trial of Ho:YAG prostatectomy. Estimated excess hyperplastic prostate tissue averaged 24 g (range 5 - 50 g). A mean of 129 kj Ho:YAG laser energy was delivered, combined with a mean of 11 kj Nd:YAG energy to provide supplemental coagulation for hemostasis. We have observed no significant perioperative or late complications. No significant intraoperative changes in hematocrit or serum electrolytes were documented. In addition to providing acute removal of obstructing prostate tissue, Ho:YAG laser resection allowed tissue specimen to be obtained for histologic examination. A total of 16 of 18 patients (90%) underwent successful removal of their urinary catheter and voiding trial within 24 hours following surgery. Immediate improvement in voiding, comparable to classic transurethral electrocautery resection of the prostate (TURP), was reported by all patients. Ho:YAG laser resection of the prostate appears to be a viable surgical technique associated with minimal morbidity and immediate improvement in voiding.

Thermal effects of Ho: YAG laser lithotripsy: real-time evaluation in an in vitro model.

PubMed

Hein, Simon; Petzold, Ralf; Schoenthaler, Martin; Wetterauer, Ulrich; Miernik, Arkadiusz

2018-04-24

To evaluate the thermal effect of Ho:YAG laser lithotripsy in a standardized in vitro model via real-time temperature measurement. Our model comprised a 20 ml test tube simulating the renal pelvis that was immersed in a 37 °C water bath. Two different laser fibers [FlexiFib (15-45 W), RigiFib 1000 (45-100 W), LISA laser products OHG, Katlenburg-Lindau, Germany] were placed in the test tube. An Ho:YAG 100 W laser was used in all experiments (LISA). Each experiment involved 120 s of continuous laser application, and was repeated five times. Different laser settings (high vs. low frequency, high vs. low energy, and long vs. short pulse duration), irrigation rates (0 up to 100 ml/min, realized by several pumps), and human calcium oxalate stone samples were analyzed. Temperature data were acquired by a real-time data logger with thermocouples (PICO Technology, Cambridgeshire, UK). Real-time measurements were assessed using MatLab ® . Laser application with no irrigation results in a rapid increase in temperature up to ∆28 K, rising to 68 °C at 100 W. Low irrigation rates yield significantly higher temperature outcomes. Higher irrigation rates result immediately in a lower temperature rise. High irrigation rates of 100 ml/min result in a temperature rise of 5 K at the highest laser power setting (100 W). Ho:YAG laser lithotripsy might be safe provided that there is sufficient irrigation. However, high power and low irrigation resulted in potentially tissue-damaging temperatures. Laser devices should, therefore, always be applied in conjunction with continuous, closely monitored irrigation whenever performing Ho:YAG laser lithotripsy.

The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces.

PubMed

Kinney, J H; Haupt, D L; Balooch, M; White, J M; Bell, W L; Marshall, S J; Marshall, G W

1996-06-01

Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.

Soft tissue effects of the THC:YAG laser on canine vocal cords.

PubMed

Kay, S L; Oz, M C; Haber, M; Blitzer, A; Treat, M R; Trokel, S L

1992-09-01

Recently, a laser based on a thulium-holmium-chromium (THC) doped Yttrium-aluminum-garnet (YAG) rod has been developed that produces light of 2.15 microns wavelength and can be transmitted through a low OH- silica fiberoptic cable. This wavelength falls on one of the peaks of the energy absorption spectrum of water. Thus, the THC:YAG laser eliminates the disadvantage of a cumbersome delivery system found in the CO2 laser while still providing precise cutting and minimal tissue injury inherent in lasers emitting light absorbed by water. We evaluated the soft tissue effects of this laser on canine vocal cords. Ablative lesions were produced by the THC:YAG laser and histologically examined on postoperative days 1, 7, and 28. Results indicate that the depth of tissue penetration is easily controlled and the healing response to tissue injury is comparable to that of the CO2 laser. The THC:YAG laser should prove to be a superior laser for use in otorhinolaryngology, especially when adapted to a flexible endoscope.

Er:YAG laser in the treatment of periodontal sites with recurring chronic inflammation: a 12-month randomized, controlled clinical trial.

PubMed

Krohn-Dale, Ivar; Bøe, Olav E; Enersen, Morten; Leknes, Knut N

2012-08-01

The objective of this randomized, controlled clinical trial was to compare the clinical and microbiological effects of pocket debridement using erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser with conventional debridement in maintenance patients. Fifteen patients, all smokers, having at least four teeth with residual probing depth (PD) ≥ 5 mm were recruited. Two pockets in two jaw quadrants were randomly assigned to subgingival debridement using an Er:YAG laser (test) or ultrasonic scaler/curette (control) at 3-month intervals. Relative attachment level (RAL), PD, bleeding on probing and dental plaque were recorded at baseline and at 6 and 12 months. Microbiological subgingival samples were taken at the same time points and analysed using a checkerboard DNA-DNA hybridization technique. A significant decrease in PD took place in both treatments from baseline to 12 months (p < 0.01). In the control, the mean initial PD decreased from 5.4 to 4.0 mm at 12 months. For the test, a similar decrease occurred. No significant between-treatment differences were shown at any time point. The mean RAL showed no overall significant inter- or intra-treatment differences (p > 0.05). No significant between-treatment differences were observed in subgingival microbiological composition or total pathogens. The results failed to support that an Er:YAG laser may be superior to conventional debridement in the treatment of smokers with recurring chronic inflammation. This appears to be the first time that repeated Er-YAG laser instrumentation has been compared with mechanical instrumentation of periodontal sites with recurring chronic inflammation over a clinically relevant time period. © 2012 John Wiley & Sons A/S.

High-resolution structural characterization and magnetic properties of epitaxial Ce-doped yttrium iron garnet thin films

NASA Astrophysics Data System (ADS)

Li, Zhong; Vikram Singh, Amit; Rastogi, Ankur; Gazquez, Jaume; Borisevich, Albina Y.; Mishra, Rohan; Gupta, Arunava

2017-07-01

Thin films of magnetic garnet materials, e.g. yttrium iron garnet (Y3Fe5O12, YIG), are useful for a variety of applications including microwave integrated circuits and spintronics. Substitution of rare earth ions, such as cerium, is known to enhance the magneto-optic Kerr effect (MOKE) as compared to pure YIG. Thin films of Ce0.75Y2.25Fe5O12 (Ce:YIG) have been grown using the pulsed laser deposition (PLD) technique and their crystal structure examined using high resolution scanning transmission electron microscopy. Homogeneous substitution of Ce in YIG, without oxidation to form a separate CeO2 phase, can be realized in a narrow process window with resulting enhancement of the MOKE signal. The thermally generated signal due to spin Seebeck effect for the optimally doped Ce:YIG films has also been investigated.

Magneto-optical study of holmium iron garnet Ho3Fe5O12

NASA Astrophysics Data System (ADS)

Kalashnikova, A. M.; Pavlov, V. V.; Kimel, A. V.; Kirilyuk, A.; Rasing, Th.; Pisarev, R. V.

2012-09-01

Bulk holmium iron garnet Ho3Fe5O12 is a cubic ferrimagnet with Curie temperature TC = 567 K and magnetization compensation point in the range 130-140 K. The magneto-optical data are presented for a holmium iron garnet Ho3Fe5O12 film, ˜10 μm thick, epitaxially grown on a (111)-type gadolinium-gallium garnet Gd3Ga5O12 substrate. A specific feature of this structure is that the parameters of the bulk material, from which the film was grown, closely match the substrate ones. The temperature and field dependences of Faraday rotation as well as the temperature dependence of the domain structure in zero field were investigated. The compensation point of the structure was found to be Tcomp = 127 K. It was shown that the temperature dependence of the characteristic size of domain structure diverges at this point. Based on the obtained results we established that the magnetic anisotropy of the material is determined by both uniaxial and cubic contributions, each characterized by different temperature dependence. A complex shape of hysteresis loops and sharp changes of the domain pattern with temperature indicate the presence of collinear-noncollinear phase transitions. Study of the optical second harmonic generation was carried out using 100 fs laser pulses with central photon energy E = 1.55 eV. The electric dipole contribution (both crystallographic and magnetic) to the second harmonic generation was observed with high reliability despite a small mismatch of the film and substrate parameters.

Microstructure development and photoluminescence of annealed nanosized Ce:YAG/Al2O3 and Ce:YAG/Cr:Al2O3 powder composites

NASA Astrophysics Data System (ADS)

Peter, Samuel; Kuyanov, Paul; Isik Goktas, Nebile; LaPierre, Ray; Kitai, Adrian

2018-03-01

In an effort to control aggregation and sintering of phosphor nanoparticles at elevated annealing temperatures, glycothermally synthesized cerium-doped yttrium aluminum garnet (Ce:YAG) nanoparticles were annealed in a matrix of aluminum oxide between 1000 °C and 1200 °C. Scanning electron microscopy images showed that glycothermal synthesis yields ∼100 nm particles, and that the alumina matrix was able to control grain growth of Ce:YAG at annealing temperatures up to 1200 °C. Analysis by x-ray diffraction and Fourier transform infrared spectroscopy showed an increase in the degree of crystallinity at increasing temperatures as well as the evolution of alumina phases. Photoluminescence of the composite product showed the expected broad Ce:YAG spectrum, with characteristic chromium R lines present due to the formation of corundum at 1200 °C with trace chromium content. The same procedure was performed to synthesize a Ce:YAG/Cr:Al2O3 nanocomposite, yielding photoluminescence of both the expected Ce:YAG and Cr:Al2O3 peaks as well as clear evidence of energy transfer between Ce and Cr centers in YAG. The luminescence of these composites was used to determine their CIE colour co-ordinates. It was found that the colour profile of the resulting emission may be tuned by adjusting the Cr content and annealing conditions of the composite materials.

Phase Diagram for Magnon Condensate in Yttrium Iron Garnet Film

PubMed Central

Li, Fuxiang; Saslow, Wayne M.; Pokrovsky, Valery L.

2013-01-01

Recently, magnons, which are quasiparticles describing the collective motion of spins, were found to undergo Bose-Einstein condensation (BEC) at room temperature in films of Yttrium Iron Garnet (YIG). Unlike other quasiparticle BEC systems, this system has a spectrum with two degenerate minima, which makes it possible for the system to have two condensates in momentum space. Recent Brillouin Light Scattering studies for a microwave-pumped YIG film of thickness d = 5 μm and field H = 1 kOe find a low-contrast interference pattern at the characteristic wavevector Q of the magnon energy minimum. In this report, we show that this modulation pattern can be quantitatively explained as due to unequal but coherent Bose-Einstein condensation of magnons into the two energy minima. Our theory predicts a transition from a high-contrast symmetric state to a low-contrast non-symmetric state on varying the d and H, and a new type of collective oscillation. PMID:23455849

Modulatory effects by neodymium-doped yttrium aluminum garnet laser on fibroblast attachment to single rooted tooth surfaces following ultrasonic scaling and root planning: An in vitro study

PubMed Central

Negi, Shanta; Krishnamurthy, Malathi; Ganji, Kiran Kumar; Pendor, Sunil

2015-01-01

Context: One of the most important goals of periodontal therapy is connective tissue reattachment to previously diseased root surfaces. In the recent years, laser therapy has been considered as an important tool in improving the treatment of periodontal disease. Aims: To evaluate the neodymium-doped yttrium aluminum garnet (Nd: YAG) lasers effects on root surfaces affected by periodontal disease and compare this treatment with scaling and root planning (SRP) in terms of fibroblast attachment. Materials and Methods: A sample of 30 single-rooted human teeth extracted because of advanced periodontal disease was used in this study. Sixty specimens obtained by longitudinal sectioning were randomly divided in three groups. Group A control (untreated); Group B SRP; Group C laser (Nd: YAG) and ultrasonic scaling. All specimens were incubated with fibroblast suspension and then fixed and observed under scanning electron microscope. Results: With a median of 8, the control group (Group A) exhibited the least number of total fibroblasts among all the three groups. The laser and scaling - treated group (Group C) showed the highest number of fibroblasts (median = 49, mean ± standard deviation [SD] = 48.28 ± 17.18), followed by SRP only (Group B, median = 22, mean ± SD = 22.24 ± 8.67). Conclusions: Nd: YAG laser irradiation at specific energy densities can be used as a useful tool to condition the root surfaces, enhancing fibroblast attachment. Hence aiding in re-establishment of the connective tissue attachment to the root surfaces of previously diseased teeth. PMID:25810589

Microbiological effects and recolonization patterns after adjunctive subgingival debridement with Er:YAG laser.

PubMed

Sanz-Sánchez, Ignacio; Ortiz-Vigón, Alberto; Herrera, David; Sanz, Mariano

2016-07-01

The objective of this study was to assess the microbiological effects and recolonization patterns after non-surgical periodontal treatment protocol based on the adjunctive use of erbium-doped yttrium aluminium garnet (Er:YAG) laser. Patients diagnosed with chronic periodontitis were randomly assigned to two different treatment protocols: test, full-mouth subgingival ultrasonic instrumentation followed by Er-YAG laser application 1 week later to sites with initial probing pocket depth ≥4.5 mm; and control, full-mouth ultrasonic subgingival instrumentation within 1 week. Clinical (at sampled sites) and microbiological (culture-based) parameters were recorded at baseline and 3 and 12 months. Microbiological variables included total counts, frequency of detection, proportions and counts of target species. Results from 19 test and 21 control patients were compared. Minor changes were observed for total colony-forming units, with no differences between groups. For the frequency of detection, a limited and similar impact in both groups was observed for the most prevalent (over 80 %) periodontal pathogens (Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum). For proportions, reductions in P. gingivalis occurred at 3 months, both in the test and control groups (from 16.3 to 10 % and 16 to 14.8 %, respectively), although these differences were not statistically significant. At 12 months, the test group showed a statistically significant greater reduction in probing depth for the sampled sites. The adjunctive use of Er:YAG laser when compared with conventional ultrasonic debridement did not provide a microbiological added benefit. Even though some clinical benefits with the adjunctive laser application were identified when comparing both treatment protocols, there were no differences in microbiological outcomes or in the bacterial recolonization patterns.

Periodontal and peri-implant wound healing following laser therapy.

PubMed

Aoki, Akira; Mizutani, Koji; Schwarz, Frank; Sculean, Anton; Yukna, Raymond A; Takasaki, Aristeo A; Romanos, Georgios E; Taniguchi, Yoichi; Sasaki, Katia M; Zeredo, Jorge L; Koshy, Geena; Coluzzi, Donald J; White, Joel M; Abiko, Yoshimitsu; Ishikawa, Isao; Izumi, Yuichi

2015-06-01

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO2 , neodymium-doped yttrium-aluminium-garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft-tissue management. With development of the erbium-doped yttrium-aluminium-garnet (Er:YAG) and erbium, chromium-doped yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft-tissue management to hard-tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri-implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti-inflammatory agents, phototherapy using lasers and light-emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low- and high-level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri-implant diseases. This article discusses the outcomes of laser therapy in soft-tissue management, periodontal

Magnetophotonic crystals based on yttrium-iron-garnet infiltrated opals: Magnetization-induced second-harmonic generation

NASA Astrophysics Data System (ADS)

Murzina, T. V.; Kim, E. M.; Kapra, R. V.; Moshnina, I. V.; Aktsipetrov, O. A.; Kurdyukov, D. A.; Kaplan, S. F.; Golubev, V. G.; Bader, M. A.; Marowsky, G.

2006-01-01

Three-dimensional magnetophotonic crystals (MPCs) based on artificial opals infiltrated by yttrium iron garnet (YIG) are fabricated and their structural, optical, and nonlinear optical properties are studied. The formation of the crystalline YIG inside the opal matrix is checked by x-ray analysis. Two templates are used for the infiltration by YIG: bare opals and those covered by a thin platinum film. Optical second-harmonic generation (SHG) technique is used to study the magnetization-induced nonlinear-optical properties of the composed MPCs. A high nonlinear magneto-optical Kerr effect in the SHG intensity is observed at the edge of the photonic band gap of the MPCs.

Pulsed laser deposition of epitaxial yttrium iron garnet films with low Gilbert damping and bulk-like magnetization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onbasli, M. C., E-mail: onbasli@mit.edu; Kim, D. H.; Ross, C. A.

2014-10-01

Yttrium iron garnet (YIG, Y {sub 3}Fe{sub 5}O{sub 12}) films have been epitaxially grown on Gadolinium Gallium Garnet (GGG, Gd{sub 3}Ga{sub 5}O{sub 12}) substrates with (100) orientation using pulsed laser deposition. The films were single-phase, epitaxial with the GGG substrate, and the root-mean-square surface roughness varied between 0.14 nm and 0.2 nm. Films with thicknesses ranging from 17 to 200 nm exhibited low coercivity (<2 Oe), near-bulk room temperature saturation moments (∼135 emu cm{sup −3}), in-plane easy axis, and damping parameters as low as 2.2 × 10{sup −4}. These high quality YIG thin films are useful in the investigation ofmore » the origins of novel magnetic phenomena and magnetization dynamics.« less

Ho:YAG Single Crystal Fiber: Fabrication and Optical Characterization

DTIC Science & Technology

2014-06-16

between the 5I8 and 5I7 energy levels. The results verified the absorption peaks suitable for in- band direct pumping at 1908 nm and 1932 nm with the...Efficient high-power Ho:YAG laser directly in- band pumped by a GaSb -based laser diode stack at 1.9 μm,” Appl. Phys. B 106(2), 315–319 (2012). 21. M...characterized for its optical absorption and emission properties involving transitions between the 5I8 and 5I7 energy levels. The results verified

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos

PubMed Central

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Background: Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. Aim: The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. Materials and Methods: This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4–6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm2. The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. Results: After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Conclusion: Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals. PMID:26677271

Efficacy of the Q-switched Neodymium: Yttrium Aluminum Garnet Laser in the Treatment of Blue-black Amateur and Professional Tattoos.

PubMed

Lakshmi, Chembolli; Krishnaswamy, Gayathri

2015-01-01

Q-switched neodymium: yttrium aluminum garnet (Nd: YAG) laser at a wavelength of 1064 nm primarily targets dermal melanin and black tattoo ink. Recent studies have shown that this laser is effective in treating black tattoos. There are few studies conducted in India for the same. The aim was to assess the effectiveness of Q-switched Nd: YAG laser (QSNYL) in the treatment of blue-black tattoos following 3 treatment sessions. This study, a prospective interventional study included a total of 12 blue-black tattoos. Following informed consent for the procedure, as well as for photographs, a questionnaire was administered, and improvement perceived by the patient was recorded. In addition, global assessment score (GAS) by a blinded physician was also recorded. Photographs were taken at baseline and at every follow-up. Each patient underwent three treatment sessions with 1064 nm QSNYL at 4-6 weekly intervals. Fluences ranged from 1.8 to 9 J/cm(2). The follow-up was done monthly for 4 months from the first treatment session. The response was assessed by patient assessment (PA) and GAS by comparing photographs. After three treatment sessions, although no patient achieved clearance, most patients showed good response with few adverse effects. An average of 64.1% (GAS) and 54.2% (PA) improvement was observed in 12 tattoos. Tattoos more than 10-year-old showed quicker clearing than those less than 10-year-old. Amateur tattoos also showed a better response in comparison to professional tattoos. Totally, 1064 nm QSNYL is safe and effective for lightening blue-black tattoos in pigmented Indian skin. All patients achieved near complete clearance following the continuation of treatment (an average of six sessions) although this was spaced at longer intervals.

Femtosecond laser inscribed cladding waveguides in Nd:YAG ceramics: fabrication, fluorescence imaging and laser performance.

PubMed

Liu, Hongliang; Jia, Yuechen; Vázquez de Aldana, Javier Rodríguez; Jaque, Daniel; Chen, Feng

2012-08-13

We report on the fabrication of depressed cladding waveguide lasers in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) ceramics microstructured by femtosecond laser pulses. Full control over the confined light spatial distribution is demonstrated by the fabrication of high contrast waveguides with hexagonal, circular and trapezoidal configurations. The confocal fluorescence measurements of the waveguides reveal that the original luminescence features of Nd3+ ions are well-preserved in the waveguide regions. Under optical pump at 808 nm, cladding waveguides showed continuous wave efficient laser oscillation. The maximum output power obtained at 1064.5 nm is ~181 mW with a slope efficiency as high as 44%, which suggests that the fabricated Nd:YAG ceramic waveguides are promising candidates for efficient integrated laser sources.

Efficacy and safety of Ho:YAG laser lithotripsy for ureteroscopic removal of proximal and distal ureteral calculi.

PubMed

Khoder, Wael Y; Bader, Markus; Sroka, Ronald; Stief, Christian; Waidelich, Raphaela

2014-08-08

Laser lithotripsy is an established endourological modality. Ho:YAG laser have broadened the indications for ureteroscopic stone managements to include larger stone sizes throughout the whole upper urinary tract. Aim of current work is to assess efficacy and safety of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral calculi in different locations. 88 patients were treated with ureteroscopic Ho:YAG laser lithotripsy in our institute. Study endpoint was the number of treatments until the patient was stone-free. Patients were classified according to the location of their stones as Group I (distal ureteric stones, 51 patients) and group II (proximal ureteral stones, 37). Group I patients have larger stones as Group II (10.70 mm vs. 8.24 mm, respectively, P = 0.020). Overall stone free rate for both groups was 95.8%. The mean number of procedures for proximal calculi was 1.1 ± 0.1 (1-3) and for distal calculi was 1.0 ± 0.0. The initial treatment was more successful in patients with distal ureteral calculi (100% vs. 82.40%, respectively, P = 0.008). No significant difference in the stone free rate was noticed after the second laser procedure for stones smaller versus larger than 10 mm (100% versus 94.1%, P = 0.13). Overall complication rate was 7.9% (Clavien II und IIIb). Overall and grade-adjusted complication rates were not dependent on the stone location. No laser induced complications were noticed. The use of the Ho:YAG laser appears to be an adequate tool to disintegrate ureteral calculi independent of primary location. Combination of the semirigid and flexible ureteroscopes as well as the appropriate endourologic tools could likely improve the stone clearance rates for proximal calculi regardless of stone-size.

Efficacy and safety of Ho:YAG Laser Lithotripsy for ureteroscopic removal of proximal and distal ureteral calculi

PubMed Central

2014-01-01

Background Laser lithotripsy is an established endourological modality. Ho:YAG laser have broadened the indications for ureteroscopic stone managements to include larger stone sizes throughout the whole upper urinary tract. Aim of current work is to assess efficacy and safety of Ho:YAG laser lithotripsy during retrograde ureteroscopic management of ureteral calculi in different locations. Methods 88 patients were treated with ureteroscopic Ho:YAG laser lithotripsy in our institute. Study endpoint was the number of treatments until the patient was stone-free. Patients were classified according to the location of their stones as Group I (distal ureteric stones, 51 patients) and group II (proximal ureteral stones, 37). Group I patients have larger stones as Group II (10.70 mm vs. 8.24 mm, respectively, P = 0.020). Results Overall stone free rate for both groups was 95.8%. The mean number of procedures for proximal calculi was 1.1 ± 0.1 (1–3) and for distal calculi was 1.0 ± 0.0. The initial treatment was more successful in patients with distal ureteral calculi (100% vs. 82.40%, respectively, P = 0.008). No significant difference in the stone free rate was noticed after the second laser procedure for stones smaller versus larger than 10 mm (100% versus 94.1%, P = 0.13). Overall complication rate was 7.9% (Clavien II und IIIb). Overall and grade-adjusted complication rates were not dependant on the stone location. No laser induced complications were noticed. Conclusions The use of the Ho:YAG laser appears to be an adequate tool to disintegrate ureteral calculi independent of primary location. Combination of the semirigid and flexible ureteroscopes as well as the appropriate endourologic tools could likely improve the stone clearance rates for proximal calculi regardless of stone-size. PMID:25107528

Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses

NASA Astrophysics Data System (ADS)

Dubs, Carsten; Surzhenko, Oleksii; Linke, Ralf; Danilewsky, Andreas; Brückner, Uwe; Dellith, Jan

2017-05-01

Using a liquid phase epitaxy (LPE) technique (1 1 1) yttrium iron garnet (YIG) films with thicknesses of  ≈100 nm and surface roughnesses as low as 0.3 nm have been grown on (1 1 1) gadolinium gallium garnet (GGG) substrates as a basic material for spin-wave propagation experiments in microstructured waveguides. The continuously strained films exhibit nearly perfect crystallinity without significant mosaicity and with effective lattice misfits of Δ {{a}\\bot}/{{a}s}≈ {{10}-4} and below. The film/substrate interface is extremely sharp without broad interdiffusion layer formation. All LPE films exhibit a nearly bulk-like saturation magnetization of (1800+/- 20 ) Gs and an ‘easy cone’ anisotropy type with extremely small in-plane coercive fields  <0.2 Oe. There is a rather weak in-plane magnetic anisotropy with a pronounced six-fold symmetry observed for the saturation field  <1.5 Oe. No significant out-of-plane anisotropy is observed, but a weak dependence of the effective magnetization on the lattice misfit is detected. The narrowest ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is the lowest value reported so far for YIG films of 100 nm thicknesses and below. The Gilbert damping coefficient for investigated LPE films is estimated to be close to 1× {{10}-4} .

Spin wave propagation in perpendicularly magnetized nm-thick yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Chen, Jilei; Heimbach, Florian; Liu, Tao; Yu, Haiming; Liu, Chuanpu; Chang, Houchen; Stückler, Tobias; Hu, Junfeng; Zeng, Lang; Zhang, Youguang; Liao, Zhimin; Yu, Dapeng; Zhao, Weisheng; Wu, Mingzhong

2018-03-01

Magnonics offers a new way for information transport that uses spin waves (SWs) and is free of charge currents. Unlike Damon-Eshbach SWs, the magneto-static forward volume SWs offer the reciprocity configuration suitable for SW logic devices with low power consumption. Here, we study forward volume SW propagation in yttrium iron garnet (YIG) thin films with an ultra-low damping constant α = 8 ×10-5 . We design different integrated microwave antenna with different k-vector excitation distributions on YIG thin films. Using a vector network analyzer, we measured SW transmission with the films magnetized in perpendicular orientation. Based on the experimental results, we extract the group velocity as well as the dispersion relation of SWs and directly compare the power efficiency of SW propagation in YIG using coplanar waveguide and micro stripline for SW excitation and detection.

Flux-gate magnetic field sensor based on yttrium iron garnet films for magnetocardiography investigations

NASA Astrophysics Data System (ADS)

Vetoshko, P. M.; Gusev, N. A.; Chepurnova, D. A.; Samoilova, E. V.; Syvorotka, I. I.; Syvorotka, I. M.; Zvezdin, A. K.; Korotaeva, A. A.; Belotelov, V. I.

2016-08-01

A new type of f lux-gate vector magnetometer based on epitaxial yttrium iron garnet films has been developed and constructed for magnetocardiography (MCG) investigations. The magnetic field sensor can operate at room temperature and measure MCG signals at a distance of about 1 mm from the thoracic cage. The high sensitivity of the sensor, better than 100 fT/Hz1/2, is demonstrated by the results of MCG measurements on rats. The main MCG pattern details and R-peak on a level of 10 pT are observed without temporal averaging, which allows heart rate anomalies to be studied. The proposed magnetic sensors can be effectively used in MCG investigations.

Finite temperature magnon spectra in yttrium iron garnet from a mean field approach in a tight-binding model

NASA Astrophysics Data System (ADS)

Shen, Ka

2018-04-01

We study magnon spectra at finite temperature in yttrium iron garnet using a tight-binding model with nearest-neighbor exchange interaction. The spin reduction due to thermal magnon excitation is taken into account via the mean field approximation to the local spin and is found to be different at two sets of iron atoms. The resulting temperature dependence of the spin wave gap shows good agreement with experiment. We find that only two magnon modes are relevant to the ferromagnetic resonance.

Neodymium: yttrium-aluminum-garnet long impulse laser for the elimination of superfluous hair: experiences and considerations from 3 years of activity.

PubMed

Ferraro, G A; Perrotta, A; Rossano, F; D'Andrea, F

2004-01-01

This study examined the results obtained with a modern apparatus for laser hair removal (neodymium: yttrium-aluminum-garnet [Nd:YAG] laser at long impulses with a wave-length of 1,064 nm; Q-switched laser) over a follow-up period of 3 years. A large heterogeneous group of 480 patients was taken into consideration. These patients were treated according to a standard protocol with monthly checkups and a personalized protocol at deferred appointments. The results, discovered by means of the most objective procedure possible, were retrieved and put into a graph showing two different curves for the repopulation of hair. In their clinical travels, the authors observed an average variable regrowth of 40% to 65%, allowing them to affirm that laser hair removal using Nd:YAG at long impulses is decisively efficient in obtaining long-term results. The use of a protocol (denominated "prolonged monthly checkup") with laser sessions at ever-decreasing periods permits, among other things, more outstanding and advantageous results for the patient. Thanks to more efficiently synchronized phases of the biologic hair cycle, this shortens and moves the telegenic phases closer and also renders the anagenic phases (those in which the selective photoermolysis on the pilipheric follicle proves to be efficient) more efficient. Personalization of the treatment relative to the monthly health checkup sessions is of fundamental importance to the scope of obtaining the best results in terms of cost-benefit rate, provided submassimal fluxes are (i.e., those well-tolerated by the patient) used. All this allows hair removal that is not definitive, but which becomes progressively permanent (i.e., characterized by ever-growing periods of lack of hair sustained by sporadic maintenance laser sessions based on the individual's necessity).

Mixed garnet laser crystals for water vapour DIAL transmitter

NASA Astrophysics Data System (ADS)

Treichel, Rainer; Czeranowsky, Christoph; Ileri, Bilge; Petermann, Klaus; Huber, Günter

2017-11-01

There are more or less well established technologies such as the optical-parametric-oscillator (OPO), the Raman-laser, and the Ti-Sapphire laser, which are able to emit laser light in the region of the water vapour absorption lines. For WALES the regions of about 935 nm, 942 nm, and 944 nm have been identified as the most suitable wavelength ranges. However, each of these laser designs is highly sophisticated. Current baseline for WALES is the Ti-Sapphire laser. A fourth possibility to achieve these wavelength ranges is to shift the groundstate laser lines (938 nm and 946 nm) of the Nd:YAG laser by replacing Aluminium and Yttrium by other rare earth elements. Changes of the host lattice characteristics lead to a shift of the upper and lower laser levels. These modified crystals are summarized under the name of "Mixed Garnet" crystals. Only the Mixed Garnet lasers can be pumped directly with diode laser and use a direct approach to generate the required laser pulses without frequency conversion. Therefore no additional non-linear crystals are needed and a higher electric to optical efficiency is expected as well as single frequency operation using spectral tuning elements like etalons. Such lasers have the great potential to fulfil the requirements and to become the preferred transmitter concept for WALES as well as for follow up missions. Within a ESA study several crystal compositions have been grown, spectrally characterised and analysed. Absorbed space radiation energy in the crystal lattice causes colour centres, which can reabsorb the pump and laser wavelength and consequently reduce the laser gain considerably. Co-dopants such as Chromium and Cerium are able to suppress the colour centres and are candidates for effective radiation hardening. The results of the crystal tuning, the co-doping with different radiation hardeners and the radiation tests will be presented. There applicability for a space based water vapour DIAL transmitter will be discussed.

Potential applications of Erbium:YAG laser in periodontics.

PubMed

Ishikawa, Isao; Aoki, Akira; Takasaki, Aristeo Atsushi

2004-08-01

Since lasers were introduced for the treatment of oral diseases, there has been considerable advancement in technology. As a result, numerous laser systems are currently available for oral use. Neodymium:Yttrium-Aluminum:Garnet (Nd:YAG), carbon dioxide (CO(2)) laser and the semiconductor Diode lasers have already been approved by the US Food and Drug Administration for soft tissue treatment in oral cavity. The Erbium:YAG (Er:YAG) laser was approved in 1997 for hard tissue treatment in dentistry and recent studies have reported positive results. This suggests that the Er:YAG laser system is a promising apparatus, which will be able to revolutionize and improve dental practice, in particular periodontal treatment. In this mini-review, we would like to describe the positive characteristics of the Er:YAG laser which indicate its potential as a new treatment modality in periodontics. Recent findings are summarized briefly to evaluate the potential of the Er:YAG laser for clinical application in periodontics. The Er:YAG laser possesses suitable characteristics for oral soft and hard tissue ablation. Recently, it has been applied for effective elimination of granulation tissue, gingival melanin pigmentation and gingival discoloration. Contouring and cutting of bone with minimal damage and even or faster healing can also be performed with this laser. In addition, irradiation with the Er:YAG laser has a bactericidal effect with reduction of lipopolysaccharide, high ability of plaque and calculus removal, with the effect limited to a very thin layer of the surface and is effective for implant maintenance. The Er:YAG laser seems to be an effective tool for periodontal therapy, however, further clinical and basic investigations are required to confirm its clinical application. Copyright Blackwell Munksgaard, 2004

Microbiologic results after non-surgical erbium-doped:yttrium, aluminum, and garnet laser or air-abrasive treatment of peri-implantitis: a randomized clinical trial.

PubMed

Persson, G Rutger; Roos-Jansåker, Ann-Marie; Lindahl, Christel; Renvert, Stefan

2011-09-01

The purpose of this study is to assess clinical and microbiologic effects of the non-surgical treatment of peri-implantitis lesions using either an erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser or an air-abrasive subgingival polishing method. In a 6-month clinical trial, 42 patients with peri-implantitis were treated at one time with an Er:YAG laser or an air-abrasive device. Routine clinical methods were used to monitor clinical conditions. Baseline and 6-month intraoral radiographs were assessed with a software program. The checkerboard DNA-DNA hybridization method was used to assess 74 bacterial species from the site with the deepest probing depth (PD) at the implant. Non-parametric tests were applied to microbiology data. PD reductions (mean ± SD) were 0.9 ± 0.8 mm and 0.8 ± 0.5 mm in the laser and air-abrasive groups, respectively (not significant). No baseline differences in bacterial counts between groups were found. In the air-abrasive group, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus anaerobius were found at lower counts at 1 month after therapy (P <0.001) and with lower counts in the laser group for Fusobacterium nucleatum naviforme (P = 0.002), and Fusobacterium nucleatum nucleatum (P = 0.002). Both treatments failed to reduce bacterial counts at 6 months. Porphyromonas gingivalis counts were higher in cases with progressive peri-implantitis (P <0.001). At 1 month, P. aeruginosa, S. aureus, and S. anaerobius were reduced in the air-abrasive group, and Fusobacterium spp. were reduced in the laser group. Six-month data demonstrated that both methods failed to reduce bacterial counts. Clinical improvements were limited.

Indocyanine green-augmented diode laser therapy vs. long-pulsed Nd:YAG (1064 nm) laser treatment of telangiectatic leg veins: a randomized controlled trial.

PubMed

Klein, A; Buschmann, M; Babilas, P; Landthaler, M; Bäumler, W

2013-08-01

Telangiectatic leg veins (TLV) represent a common cosmetic problem. Near infrared lasers have been widely used in treatment because of their deeper penetration into the dermis, but with varying degrees of success, particularly because of different vessel diameters. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may present an alternative treatment option. This trial evaluates the efficacy of ICG+DL in the treatment of TLV and compares the safety and efficacy of therapy with the standard treatment, the long-pulsed neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. In a prospective randomized controlled clinical trial, 29 study participants with TLV were treated with a Nd:YAG laser (λem = 1064 nm, 160-240 J cm(-2) , 65-ms pulse duration, 5-mm spot size) and ICG+DL (λem = 810 nm, 60-110 J cm(-2) , 48-87-ms pulse duration, 6-mm spot size; total ICG dose 4 mg kg(-1) ) in a side-by-side comparison in one single treatment setting that included histological examination in four participants. Two blinded investigators and the participants assessed clearance rate, cosmetic appearance and adverse events up to 3 months after treatment. According to both the investigators' and participants' assessment, clearance rates were significantly better after ICG+DL therapy than after Nd:YAG laser treatment (P < 0·05). On a 10-point scale indicating pain during treatment, participants rated ICG+DL therapy to be more painful (6·1 ± 2·0) than Nd:YAG laser (5·4 ± 2·0). ICG+DL therapy represents a new and promising treatment modality for TLV, with high clearance rates and a very good cosmetic outcome after one single treatment session. © 2013 British Association of Dermatologists.

Synthesis of crystalline Ce-activated garnet phosphor powders and technique to characterize their scintillation light yield

NASA Astrophysics Data System (ADS)

Gordienko, E.; Fedorov, A.; Radiuk, E.; Mechinsky, V.; Dosovitskiy, G.; Vashchenkova, E.; Kuznetsova, D.; Retivov, V.; Dosovitskiy, A.; Korjik, M.; Sandu, R.

2018-04-01

This work reports on a process of preparation of garnet phosphor powders and a technique for light yield evaluation of strongly light scattering samples. Powders of scintillation compounds could be used as individual materials or as samples for express tests of scintillation properties. However, estimation of their light yield (LY) is complicated by strong light scattering of this kind of materials. Ce3+-activated yttrium-aluminum and gallium-gadolinium-aluminum garnet phosphor powders, Y3Al5O12 (YAG:Ce) and Gd3Ga3Al2O12 (GGAG:Ce), were obtained using a modified coprecipitation technique. Ga tends to residue in mother liquor in ammonia media, but the modification allows to avoid the loss of components. We propose an approach for sample preparation and LY measurement setup with alpha particles excitation, allowing to decrease light scattering influence and to estimate a light yield of powder samples. This approach is used to evaluate the obtained powders.

Combination of CO2 and Q-switched Nd:YAG lasers is more effective than Q-switched Nd:YAG laser alone for eyebrow tattoo removal.

PubMed

Radmanesh, Mohammad; Rafiei, Zohreh

2015-04-01

The eyebrow tattoo removal using Q-switched lasers is usually prolonged. Other modalities may be required to enhance the efficacy and shorten the treatment course. To compare the efficacy of Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser alone versus combination of Q-switched Nd:YAG and Ultrapulse CO2 lasers for eyebrow tattoo removal after a single session. After local anesthesia, the right eyebrow of 20 patients was treated with Ultrapulse CO2 laser with the parameters of 4 J/cm(2) and 3.2 J/cm(2) for the first and the second passes. Both eyebrows were then treated with 1064-nm and 532-nm Q-switched Nd:YAG laser. The spot size and pulse duration were 3 mm and 5 nanoseconds for both wavelengths, and the fluence was 7 J/cm(2) for 1064 nm and 3 J/cm (2) for 532 nm. The side treated with combination of Q-switched Nd:YAG and CO2 lasers improved 75-100% in 6 of 20 patients versus only 1 of 20 in the side treated with Q-switched Nd:YAG alone. Similarly, the right side in 13 of 20 patients showed more than 50% improvement with combination therapy versus the left side (the monotherapy side), where only 6 of 20 cases showed more than 50% improvement. The Mann-Whitney test was 2.85 for the right side and 1.95 for the left side (P value = 0.007). Using Ultra pulse CO2 laser enhances the efficacy of Q-switched Nd:YAG laser in eyebrow tattoo removal.

Tunable Microwave Transversal Filters and Dispersive Delay Lines Based on Oblique Incidence Reflection of Magnetostatic Wave Propagating in Epitaxial Garnets.

DTIC Science & Technology

1986-09-30

surface. Ferromagnetic resonance measurements on Ion implanted garnet films (2.18, 2.19) have confirmed that the principal effects of ion implantation...Yttrium Iro Garnet (Y 3FesO1 2 ) films used in the experiments were grown or one Inch polished [111] oriented Gadolinium Gallium Garnet (GGG) wafers, by...Yttrium Iron Garnet ) films grown on 0.5mm thick substrate of GGG (Gadolinium Gallium Garnet ). Samples were angle lapped to optimize coupling into and

Real-time ultrasonography as a monitoring technique for interstitial Nd:YAG laser treatment of voluminous hemangiomas and vascular malformations

NASA Astrophysics Data System (ADS)

Werner, Jochen A.; Gottschlich, Stefan; Lippert, Burkard M.; Folz, Benedikt J.

1998-01-01

Voluminous vascular anomalies of the head and neck region are still treated with conventional surgery although Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser therapy is an effective treatment method. One hundred thirty give patients with voluminous hemangiomas and vascular malformations were treated with interstitial Nd:YAG laser therapy, partly complemented by a non-contact mode Nd:YAG laser light application. The vascular tumors had a diameter of more than 3 cm in two or all three dimensions. Treatment was carried out under ultrasound and manual control. Nearly 60% of the patients showed a complete clinical regression of the vascular tumor, a third of the patients had a partial regression and were satisfied with the treatment outcome. Four patients were treated unsuccessfully with the laser and three of them subsequently underwent conventional surgery. Only 10 patients showed cosmetic and functional deficits. These results on the interstitial Nd:YAG laser therapy of voluminous hemangiomas and vascular malformations in a large patient group demonstrated the high effectiveness of this novel and innovative therapy modality.

Nonreciprocity of spin waves in magnonic crystals created by surface acoustic waves in structures with yttrium iron garnet

NASA Astrophysics Data System (ADS)

Kryshtal, R. G.; Medved, A. V.

2015-12-01

Experimental results of investigations of nonreciprocity for surface magnetostatic spin waves (SMSW) in the magnonic crystal created by surface acoustic waves (SAW) in yttrium iron garnet films on a gallium gadolinium garnet substrate as without metallization and with aluminum films with different electrical conductivities (thicknesses) are presented. In structures without metallization, the frequency of magnonic gaps is dependent on mutual directions of propagation of the SAW and SMSW, showing nonreciprocal properties for SMSW in SAW - magnonic crystals even with the symmetrical dispersion characteristic. In metalized SAW - magnonic crystals the shift of the magnonic band gaps frequencies at the inversion of the biasing magnetic field was observed. The frequencies of magnonic band gaps as functions of SAW frequency are presented. Measured dependencies, showing the decrease of magnonic gaps frequency and the expansion of the magnonic band gap width with the decreasing of the metal film conductivity are given. Such nonreciprocal properties of the SAW - magnonic crystals are promising for signal processing in the GHz range.

Ho:YAG laser arthroscopy of the knee

NASA Astrophysics Data System (ADS)

Sisto, Domenick J.; Blazina, Martin E.; Hirsh, Linda C.

1994-09-01

The HO:YAG laser is a near-contact laser with a capacity to ablate or cut tissues. The ablation function allows the surgeon to remove meniscal tissue, lyse and resect adhesions, melt loose bodies, and dissolve inflamed synovium. The cutting function of the laser is utilized to perform a lateral release or resect torn menisci. The laser can also be utilized to drill holes in Grade IV chondromalacic lesions to initiate a healing response. The laser has been embraced by orthopaedic surgeons because of its shape and versatility. The tip is only 2 mm wide and can be delivered into the tight posterior compartments of the knee with no damaging contact with the articular surfaces. The laser coagulates as it works and bleeding is minimized. The laser can function both as a cutting and ablating tool. The laser can also drill holes into subchondral bone to, hopefully, initiate a healing response.

A dual-end-pumped Ho:YAG laser with a high energy output

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, X M; Cui, Zh; Dai, T Y

2015-08-31

We report a high energy output from a Ho:YAG oscillator resonantly double-end pumped by Tm:YLF lasers at room temperature. The maximum pulse energy of 52.5 mJ was achieved at a pulse repetition rate of 100Hz and a pulse duration of 35.2 ns, corresponding to a peak power of approximately 1.5 MW. The output wavelength was 2090.7 nm with beam quality factor M{sup 2} ∼ 1.2. (lasers)

Swift heavy ion-beam induced amorphization and recrystallization of yttrium iron garnet.

PubMed

Costantini, Jean-Marc; Miro, Sandrine; Beuneu, François; Toulemonde, Marcel

2015-12-16

Pure and (Ca and Si)-substituted yttrium iron garnet (Y3Fe5O12 or YIG) epitaxial layers and amorphous films on gadolinium gallium garnet (Gd3Ga5O12, or GGG) single crystal substrates were irradiated by 50 MeV (32)Si and 50 MeV (or 60 MeV) (63)Cu ions for electronic stopping powers larger than the threshold value (~4 MeV μm(-1)) for amorphous track formation in YIG crystals. Conductivity data of crystalline samples in a broad ion fluence range (10(11)-10(16) cm(-2)) are modeled with a set of rate equations corresponding to the amorphization and recrystallization induced in ion tracks by electronic excitations. The data for amorphous layers confirm that a recrystallization process takes place above ~10(14) cm(-2). Cross sections for both processes deduced from this analysis are discussed in comparison to previous determinations with reference to the inelastic thermal-spike model of track formation. Micro-Raman spectroscopy was also used to follow the related structural modifications. Raman spectra show the progressive vanishing and randomization of crystal phonon modes in relation to the ion-induced damage. For crystalline samples irradiated at high fluences (⩾10(14) cm(-2)), only two prominent broad bands remain like for amorphous films, thereby reflecting the phonon density of states of the disordered solid, regardless of samples and irradiation conditions. The main band peaked at ~660 cm(-1) is assigned to vibration modes of randomized bonds in tetrahedral (FeO4) units.

Lithotripsy of gallstones by means of a quality-switched giant-pulse neodymium:yttrium-aluminum-garnet laser. Basic in vitro studies using a highly flexible fiber system.

PubMed

Hochberger, J; Gruber, E; Wirtz, P; Dürr, U; Kolb, A; Zanger, U; Hahn, E G; Ell, C

1991-11-01

The quality-switched neodymium:yttrium-aluminum-garnet laser represents a new instrument for athermal fragmentation of gallstones by transformation of optical energy into mechanical energy in the form of shock waves via local plasma formation. A highly flexible 300-micron fiber transmission system was used in basic investigations to determine the influence of varying pulse repetition rates (5-30 Hz) and pulse energies (15 and 20 mJ) on shock wave intensity and stone fragmentation in vitro for 105 biliary calculi of known size and chemical composition. After performance of 1200 shock wave pressure measurements using polyvinylidenefluoride hydrophones, stone fragmentation was analyzed by determination of fragment removal rates (volume of fragments removed per fragmentation time), ablation rates (mean volume removed per laser pulse), and median fragment sizes for each laser setting. With the quality-switched neodymium:yttrium-aluminum-garnet laser system, all concrements could be reliably disintegrated into small fragments (median diameter, 0.7-1.7 mm). Compared with pure cholesterol stones, a significantly higher fragment removal rate was achieved in cholesterol stones containing 30% calcium phosphate (P = 0.039), in cholesterol stones containing 20% pigment (P = 0.015), and in pure pigment stones (P = 0.007). Fragment removal rates, local shock wave pressures, and median grain sizes were significantly higher at a pulse energy of 20 mJ than with 15 mJ. Shock wave pressures showed a distinct dependence on pulse repetition rates at 20 mJ, yet not at 15 mJ. Because there is no evident hazard of thermal damage to tissue using the quality-switched neodymium:yttrium-aluminum-garnet laser, it appears to be a promising device for nonsurgical biliary stone therapy.

Epitaxial Garnet Investigation; Technical Report, Foreign Travel

DTIC Science & Technology

1988-10-25

Pure yttrium iron garnet (YIG) films are grown on GGG substrates by * liquid phase epitaxy ( LPE ) in production lots. In addition, one or two...epitaxial garnet films for Philips Dr. Krumme * Dr. Doormann 3-6-87 Thomson - CSF Research Center, Orsay, France Dr. J. P. Castera Dr. P. L. Meunier all...research physicists who grow, characterize, Dr. J. Y. Beguin or use epitaxial garnet films for Thomson CSF. Dr. J. L. Rolland Dr. P. Friez The

Single crystal Ce doped scintillator material with garnet structure sensitive to gamma ray and neutron radiation

NASA Astrophysics Data System (ADS)

Solodovnikov, D.; Weber, M. H.; Haven, D. T.; Lynn, K. G.

2012-08-01

A mixed garnet scintillator host material is obtained from the melt—Yttrium Gadolinium Gallium Aluminum Garnet (YGGAG). In addition to the high thermal and chemical stability and radiation hardness found in garnet crystals, it offers sensitivity to neutrons due to the presence of Gd atoms, has lower melting temperature than yttrium aluminum garnet, and similar crystallization behavior suitable for growth of large volume crystals. Crystals of YGGAG doped with Ce of 10×10×10 mm3 have already demonstrated energy resolution of 10% at 662 keV.

36 W Q-switched Ho:YAG laser at 2097 nm pumped by a Tm fiber laser: evaluation of different Ho3+ doping concentrations

NASA Astrophysics Data System (ADS)

Antipov, O. L.; Eranov, I. D.; Kositsyn, R. I.

2017-01-01

A laser oscillator based on Ho:YAG crystal pumped by a Tm fiber laser with an acousto-optical Q-switch was optimized for maximum output power and pulse-to-pulse stability. Stable operation at 2097 nm in Q-switched mode is demonstrated, with pulse repetition rates from 10 to 30 kHz, and output power of 36 W (at 55 W of pump power at 1908 nm) in the good quality beam. The influence of Ho ion up-conversion and thermal lensing on the oscillation efficiency is discussed.

Propagation of magnetostatic spin waves in an yttrium iron garnet film for out-of-plane magnetic fields

NASA Astrophysics Data System (ADS)

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; Tsai, C. C.; Ketterson, John B.

2018-06-01

We have observed the propagation of spin waves across a thin yttrium iron garnet film on (1 1 1) gadolinium gallium garnet for magnetic fields inclined with respect to the film plane. Two principle planes were studied: that for H in the plane defined by the wave vector k and the plane normal, n, with limiting forms corresponding to the Backward Volume and Forward Volume modes, and that for H in the plane perpendicular to k, with limiting forms corresponding to the Damon-Eshbach and Forward Volume modes. By exciting the wave at one edge of the film and observing the field dependence of the phase of the received signal at the opposing edge we determined the frequency vs. wavevector relation, ω = ω (k), of various propagating modes in the film. Avoided crossings are observed in the Damon-Eshbach and Forward Volume regimes when the propagating mode intersects the higher, exchange split, volume modes, leading to an extinction of the propagating mode; analysis of the resulting behavior allows a determination of the exchange parameter. The experimental results are compared with theoretical simulations.

Negative permittivity and permeability spectra of Cu/yttrium iron garnet hybrid granular composite materials in the microwave frequency range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsutaoka, Takanori, E-mail: tsutaok@hiroshima-u.ac.jp; Fukuyama, Koki; Kinoshita, Hideaki

2013-12-23

The relative complex permittivity and permeability spectra of the coagulated copper and yttrium iron garnet (Cu/YIG) hybrid granular composite materials have been studied in the microwave range. The insulator to metal transition was observed at the percolation threshold of Cu particle content (φ{sub Cu} = 16.0 vol. %) in the electrical conductivity. In the percolation threshold, the low frequency plasmonic state caused by the metallic Cu particle networks was observed. The percolated Cu/YIG granular composites show simultaneous negative permittivity and permeability spectra under external magnetic fields.

Urological applications of Ho/Nd:Yag laser

NASA Astrophysics Data System (ADS)

Grifoni, Riccardo; Pierangeli, Tiziana; Gioacchini, Andrea; Muraro, Giovanni B.

2001-10-01

The introduction of Ho:Yag laser has brought many advantages in urology. By this work we want show you our experience with this technology. Between April 1998 and May 2000 we treated 137 patients. Of these 28 had urinary lithiasis (18 bladder and 10 ureteral stones 3 in the upper, 2 in the middle and 5 in the distal tract), 40 were affected by enlargement of prostatic gland: 32 had B.P.H., 8 P.C.; 36 had T.C.C. and 33 strictures of urethra (27) or bladder neck (6). For ureteral lithiasis we used 200 micrometer fiber, energy of 0.5 - 1.4 J with 10 Hz of frequency. In case of bladder stones a 550 or 1000 micrometer using a power of 80 W. The prostatic gland were resected by a 550 micrometer fiber, 2.2 - 2.8 J, 25 - 30 Hz and 70 -80 W. The superficial bladder tumors were removed by 1.4 J with 10 - 15 Hz and 10 - 14 W. In the large tumors we completed the procedure by Nd:YAG at the base of the tumor. Urethra and bladder neck strictures were treated by 1.2 - 1.8 J and 10 - 30 Hz. We successful treated 26 patients with urinary lithiasis obtained the complete vaporization of the stones, 2 had endoscopic ancillary procedures. Out of 32 patients with B.P.H. 41% had the complete resection of the gland the others the resection of the 3d lobe. We removed 114 superficial bladder tumors and only 4 patients had a local recurrence. Of the patients with the strictures 4 had more than one treatment and about 87% had good result. From our experience the use of Holmium:Yag laser has been very efficacy to treat different urological diseases, also in patients with important comorbid disorders and its use reduce the stay in hospital and so the costs.

Efficacy and safety of fractional Q-switched 1064-nm neodymium-doped yttrium aluminum garnet laser in the treatment of melasma in Chinese patients.

PubMed

Yue, Baishuang; Yang, Qianli; Xu, Jinhua; Lu, Zhong

2016-11-01

Melasma is an acquired disorder of symmetrical hyperpigmentation commonly seen in patients with Fitzpatrick skin types III and IV. Various novel therapeutic modalities have emerged to treat melasma. The large-spot low-fluence QS Nd:YAG laser has been widely used in Asia; however, the modality needs to be optimized because of the high recurrence rate. The objective of this study is to explore the clinical efficacy and safety of fractional-mode (Pixel) Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) 1064-nm laser for treatment of melasma in Chinese patients. Twenty-seven patients were enrolled and completed all the treatment sessions and the 12-week follow-up. All were treated using the fractional-mode Pixel QS Nd:YAG (1064 nm) laser for eight sessions at a 2-3-week interval. Clinical photographs were taken using the Visia skin analysis imaging system. Two blinded assessors evaluated melasma area and severity index (MASI) scores before and 4 weeks after the final session. Melanin index (MI) and erythema index (EI) was measured before each treatment visit and after the final treatment. The degree of pigmentation and erythema was assessed using a tristimulus color analyzer. Physicians' global assessment (PGA) and patients' self-assessment were taken as the subjective assessments. Wilcoxon signed-rank test was performed to evaluate clinical response. Recurrence rate were also evaluated. Mean MASI scores decreased from 12.84 ± 6.89 to 7.29 ± 4.15 after treatment (p = 0.000). Seventy percent of patients got moderate to good improvements after all the treatment. Mean MI decreased significantly from 56.52 ± 23.35 to 32.75 ± 12.91 (p = 0.000). L value increased from 59.21 ± 2.22 before treatment to 61.60 ± 2.40 (p = 0.000) after therapy. The mean score of PGA was 3.76 ± 0.71, indicating a "moderate" clearance of the lesion. In patients' self-evaluations, 70 % of the patients rated the result as "good" to

Effect of ammonium carbonate to metal ions molar ratio on synthesis and sintering of Nd:YAG nanopowders

NASA Astrophysics Data System (ADS)

Liu, Qiang; Chen, Cong; Dai, Jiawei; Hu, Zewang; Chen, Haohong; Li, Jiang

2018-06-01

Using the nanopowders synthesized by a reverse co-precipitation method, neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated by vacuum sintering method. The influence of ammonium carbonate to metal ions (NH4HCO3/M3+) molar ratio (R value) on the properties of Nd:YAG precursors and powders, as well as the densification, microstructure, and transmittance of the resultant ceramics was systematically investigated. The results show that the precursors have similar compositions and the calcined powders have pure Y3Al5O12 (YAG) phase. However, the R value is closely related to the morphologies of the precursors and powders. It is found that the powder with R = 3.0 has strongest agglomeration and the powders with R = 3.2-4.0 show better dispersity. Using these powders as starting materials, the corresponding ceramics were sintered at 1720 °C for 20 h in vacuum. As a result, the ceramic with R = 3.2 obtains the best transmittance of about 72% at the wavelength of 1064 nm. The grain growth exponent and activation energy of the Nd:YAG ceramics fabricated from the powder with R = 3.2 were also studied.

Microtensile bond strength analysis of adhesive systems to Er:YAG and Er,Cr:YSGG laser-treated dentin.

PubMed

Ramos, Thaysa Monteiro; Ramos-Oliveira, Thayanne Monteiro; Moretto, Simone Gonçalves; de Freitas, Patricia Moreira; Esteves-Oliveira, Marcella; de Paula Eduardo, Carlos

2014-03-01

The aim of this in vitro study was to evaluate the effect of different surface treatments (control, diamond bur, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser) on sound dentin surface morphology and on microtensile bond strength (μTBS). Sixteen dentin fragments were randomly divided into four groups (n = 4), and different surface treatments were analyzed by scanning electron microscopy. Ninety-six third molars were randomly divided into eight groups (n = 12) according to type of surface treatment and adhesive system: G1 = Control + Clearfil SE Bond (SE); G2 = Control + Single Bond (SB); G3 = diamond bur (DB) + SE; G4 = DB + SB, G5 = Er:YAG laser (2.94 μm, 60 mJ, 2 Hz, 0.12 W, 19.3 J/cm(2)) + SE; G6 = Er:YAG + SB, G7 = Er,Cr:YSGG laser (2.78 μm, 50 mJ, 30 Hz, 1.5 W, 4.5 J/cm(2)) + SE; and G8 = Er,Cr:YSGG + SB. Composite blocks were bonded to the samples, and after 24-h storage in distilled/deionized water (37 °C), stick-shaped samples were obtained and submitted to μTBS test. Bond strength values (in megapascal) were analyzed by two-way ANOVA and Tukey tests (α = 0.05). G1 (54.69 ± 7.8 MPa) showed the highest mean, which was statistically significantly higher than all the other groups (p < 0.05). For all treatments, SE showed higher bond strength than SB, except only for Er,Cr:YSGG treatment, in which the systems did not differ statistically from each other. Based on the irradiation parameters considered in this study, it can be concluded that Er:YAG and Er,Cr:YSGG irradiation presented lower values than the control group; however, their association with self-etching adhesive does not have a significantly negative effect on sound dentin (μTBS values of >20 MPa).

Emittance Theory for Thin Film Selective Emitter

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

1994-01-01

Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

Nonlinear spin conductance of yttrium iron garnet thin films driven by large spin-orbit torque

NASA Astrophysics Data System (ADS)

Thiery, N.; Draveny, A.; Naletov, V. V.; Vila, L.; Attané, J. P.; Beigné, C.; de Loubens, G.; Viret, M.; Beaulieu, N.; Ben Youssef, J.; Demidov, V. E.; Demokritov, S. O.; Slavin, A. N.; Tiberkevich, V. S.; Anane, A.; Bortolotti, P.; Cros, V.; Klein, O.

2018-02-01

We report high power spin transfer studies in open magnetic geometries by measuring the spin conductance between two nearby Pt wires deposited on top of an epitaxial yttrium iron garnet thin film. Spin transport is provided by propagating spin waves that are generated and detected by direct and inverse spin Hall effects. We observe a crossover in spin conductance from a linear transport dominated by exchange magnons (low current regime) to a nonlinear transport dominated by magnetostatic magnons (high current regime). The latter are low-damping magnetic excitations, located near the spectral bottom of the magnon manifold, with a sensitivity to the applied magnetic field. This picture is supported by microfocus Brillouin light-scattering spectroscopy. Our findings could be used for the development of controllable spin conductors by variation of relatively weak magnetic fields.

Thermal Conductivity of a Nanoscale Yttrium Iron Garnet Thin-Film Prepared by the Sol-Gel Process

PubMed Central

2017-01-01

The thermal conductivity of a nanoscale yttrium iron garnet (Y3Fe5O12, YIG) thin-film prepared by a sol-gel method was evaluated using the ultrafast pump-probe technique in the present study. The thermoreflectance change on the surface of a 250 nm thick YIG film, induced by the irradiation of femtosecond laser pulses, was measured, and curve fitting of a numerical solution for the transient heat conduction equation to the experimental data was performed using the finite difference method in order to extract the thermal property. Results show that the film’s thermal conductivity is 22–83% higher than the properties of bulk YIG materials prepared by different fabrication techniques, reflecting the microstructural characteristics and quality of the film. PMID:28858249

Spin valve effect of the interfacial spin accumulation in yttrium iron garnet/platinum bilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Lichuan; Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716; Zhang, Dainan

2014-09-29

We report the spin valve effect in yttrium iron garnet/platinum (YIG/Pt) bilayers. The spin Hall effect (SHE) generates spin accumulation at the YIG/Pt interface and can be opened/closed by magnetization switching in the electrical insulator YIG. The interfacial spin accumulation was measured in both YIG/Pt and YIG/Cu/Pt structures using a planar Hall configuration. The spin valve effect remained, even after a 2 nm thick Cu layer was inserted between the YIG and Pt layers, which aimed to exclude the induced magnetization at the YIG/Pt interface. The transverse Hall voltage and switching field were dependent on the applied charge current density. Themore » origin of this behavior can be explained by the SHE induced torque exerted on the domain wall, caused by the transfer of the spin angular momentum from the spin-polarized current to the YIG magnetic moment.« less

Temperature-dependent relaxation of dipole-exchange magnons in yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Mihalceanu, Laura; Vasyuchka, Vitaliy I.; Bozhko, Dmytro A.; Langner, Thomas; Nechiporuk, Alexey Yu.; Romanyuk, Vladyslav F.; Hillebrands, Burkard; Serga, Alexander A.

2018-06-01

Low-energy consumption enabled by charge-free information transport, which is free from Joule heating, and the ability to process phase-encoded data through the use of nanometer-sized interference devices operating at GHz and THz frequencies are just a few benefits of spin-wave-based technologies. Moreover, when approaching cryogenic temperatures, quantum phenomena in spin-wave systems pave the path towards quantum information processing. In view of these applications, the lifetime of magnons—spin-wave quanta—is of high relevance for the fields of magnonics, magnon spintronics, and quantum computing. Here, the relaxation behavior of parametrically excited magnons having wave numbers from zero up to 6 ×105rad cm-1 was experimentally investigated in the temperature range from 20 to 340 K in single-crystal yttrium iron garnet (YIG) films of different thickness epitaxially grown on gallium gadolinium garnet (GGG) substrates as well as in a bulk YIG crystal—the magnonic materials featuring the lowest magnetic damping thus far known. Due to magnon-magnon interactions, the relaxation rate of the parametric magnons increases with an increase of their wave numbers. In the thinner samples, this increase is less pronounced, which can be associated with a stronger quantization of their magnon spectra. For the YIG films, we have found a significant increase in the magnon relaxation rate below 150 K—up to eight times the reference value at 340 K—in the entire range of probed wave numbers, which is in direct opposition to that in ultrapure YIG crystals. This increase is related to rare-earth impurities contaminating the YIG samples with a slight contribution caused by the coupling of spin waves to the spin system of the paramagnetic GGG substrate at the lowest temperatures.

Rare earth activated yttrium aluminate phosphors with modulated luminescence.

PubMed

Muresan, L E; Popovici, E J; Perhaita, I; Indrea, E; Oro, J; Casan Pastor, N

2016-06-01

Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , (2) F7/2 ). The emission intensity of Ce(3+) is enhanced in the presence of the Tb(3+) ions and is decreased in the presence of Eu(3+) ions due to some radiative or non-radiative processes that take place between activator ions. By varying the rare earth ions, the emission colour can be modulated from green to white and red. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Single Crystal Faceplate Evaluation

DTIC Science & Technology

1993-10-25

conventional powder phosphor. The utility of garnets is amplified by the high state of the art of liquid phase epitaxy ( LPE ). Liquid phase epitaxy of...7]. Much the research at Allied-Signal, Inc. in garnet layer growth has been involved with the kinetics of crystallization of garnet from LPE melts...acceptable resolution and light output characteristics. Single crystal faceplates being evaluated are composed of yttrium aluminum garnet (YAG) with an

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers

PubMed Central

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; Tang, Chi; Lin, Zhisheng; Zhang, Shufeng; Lake, Roger; Shi, Jing

2016-01-01

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin–orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon. The transmitted signal scales linearly with the driving current without a threshold and follows the power-law Tn with n ranging from 1.5 to 2.5. Our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics. PMID:26932316

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers.

PubMed

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; Tang, Chi; Lin, Zhisheng; Zhang, Shufeng; Lake, Roger; Shi, Jing

2016-03-02

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin-orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon. The transmitted signal scales linearly with the driving current without a threshold and follows the power-law T(n) with n ranging from 1.5 to 2.5. Our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics.

Effects of an erbium, chromium: yttrium, scandium, gallium, garnet laser on mucocutanous soft tissues.

PubMed

Rizoiu, I M; Eversole, L R; Kimmel, A I

1996-10-01

Lasers are effective tools for soft tissue surgery. The erbium, chromium: yttrium, scandium, gallium, garnet laser is a new system that incorporates an air-water spray. This study evaluates the cutting margins of this laser and compares healing with laser and conventional scalpel and punch biopsy-induced wounds. New Zealand white rabbits were divided into serial sacrifice groups; the tissues were grossly and microscopically analyzed after laser and convential steel surgical wounding. Wound margins were found to show minimal edge coagulation artifact and were 20 to 40 mm in width. Laser wounds showed minimal to no hemorrhage and re-epithelialization and collagenization were found to occur by day 7 in both laser and conventional groups. The new laser system is an effective soft tissue surgical device; wound healing is comparable to that associated with surgical steel wounds. The minimal edge artifact observed with this laser system should allow for the procurement of diagnostic biopsy specimens.

Observation of magnon-mediated current drag in Pt/yttrium iron garnet/Pt(Ta) trilayers

DOE PAGES

Li, Junxue; Xu, Yadong; Aldosary, Mohammed; ...

2016-03-02

Pure spin current, a flow of spin angular momentum without flow of any accompanying net charge, is generated in two common ways. One makes use of the spin Hall effect in normal metals (NM) with strong spin–orbit coupling, such as Pt or Ta. The other utilizes the collective motion of magnetic moments or spin waves with the quasi-particle excitations called magnons. A popular material for the latter is yttrium iron garnet, a magnetic insulator (MI). Here we demonstrate in NM/MI/NM trilayers that these two types of spin currents are interconvertible across the interfaces, predicated as the magnon-mediated current drag phenomenon.more » The transmitted signal scales linearly with the driving current without a threshold and follows the power-law T n with n ranging from 1.5 to 2.5. Lastly, our results indicate that the NM/MI/NM trilayer structure can serve as a scalable pure spin current valve device which is an essential ingredient in spintronics.« less

Heat capacity of rare-earth cuprates, orthovanadates, and aluminum garnets, gallium garnets, and iron garnets

NASA Astrophysics Data System (ADS)

Denisova, L. T.; Kargin, Yu. F.; Denisov, V. M.

2015-08-01

The correlation between the heat capacities of rare-earth cuprates, orthovanadates, and garnets with ionic radius R 3+ has been analyzed. It has been shown that the values of C {/p 0} change consistently depending on the radius R 3+ within the corresponding tetrads (La-Nd, Pm-Gd, Gd-Ho, Eu-Lu).

Experiments and theory for a Tm:Ho:YAG laser end pumped by a Cr:GSAG laser

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Choi, Young S.; Hess, Robert V.; Blair, Clayton H.; Brockman, Philip; Barnes, Norman P.

1991-01-01

A Cr:GSAG-laser-pumped Tm:Ho:YAG laser has been fabricated and tested. A maximum output energy of 14 mJ with a slope efficiency of 33.6 percent was obtained using a 98-percent reflective output coupler. A comprehensive rate equation model has been developed to describe laser performance. Details of the experimental measurements and model are presented.

Yttrium geothermometry: an approach to determine the oldest garnet growth recrystallization conditions from micaschists (Yunquera Unit, Betic Cordilleras, southern Spain

NASA Astrophysics Data System (ADS)

Esteban, J. J.; Cuevas, J.; Tubía, J. M.; Gil Ibarguchi, J. I.

2012-04-01

The garnet-xenotime geothermometry is nowadays been using as a tool to identify low-grade relic garnets and even to calculate garnet growth temperatures in metapelites that have undergone a polymetamorphic evolution (Pyle and Spear, 2000; Borghi et al., 2006). A prograde metamorphic evolution, under continuously increasing temperature, can induce garnet and accompanying phase's composition homogenization by intra-crystalline diffusion, leading to flat zoning profiles. Consequently, the application of conventional geothermobarometers on those mineral assemblages does establish minimum P-T conditions. Therefore, the less susceptible elements to diffusion processes, like trace elements, should be taken into account in order to reconstruct their metamorphic evolution. We studied a polymetamorphic micaschist recovered from the Yunquera Unit, one of the tectonic slices of the Internal Zone of the Betic Cordilleras (southern Spain) (Dürr, 1963). The Yunquera unit evidences three stages of recrystallization at different P-T conditions. According to conventional geothermobarometry (Esteban et al., 2005) the metamorphic peak, M2, is estimated at 1200-1300 MPa and 560-695 °C and the decompression path, M3, at 600 MPa and 700 °C. The lack of mineral paragenesis in apparent chemical equilibrium during M1, does not allow determining accurately its recrystallization conditions. Xenotime, identified by scanning electron microprobe, appears as matrix mineral and therefore the entire garnets are assumed to be in chemical equilibrium with it. Yttrium profiles of two garnets show a mean bell-shape compositional variation that differs significatively from the discontinuous profiles shown by Ca, Mg and Fe. This difference accounts for different diffusion rates for those elements and agree with the original Y-zoning preservation. A third Y-profile shows an oscillatory compositional variation. The internal part of garnets, bounded by sharp inclusion trails, are characterized by sawed

Use of the holmium:YAG laser in urology.

PubMed

Johnson, D E; Cromeens, D M; Price, R E

1992-01-01

The tissue effects of a holmium:YAG (Ho:YAG) laser operating at a wavelength of 2.1 mu with a maximum power of 15 watts (W) and 10 different energy-pulse settings was systematically evaluated on kidney, bladder, prostate, ureteral, and vasal tissue in the dog. In addition, various urologic surgical procedures (partial nephrectomy, transurethral laser incision of the prostate, and laser-assisted vasovasostomy) were performed in the dog, and a laparoscopic pelvic lymph node dissection was carried out in a pig. Although the Ho:YAG laser has a strong affinity for water, precise tissue ablation was achieved in both the contact and non-contact mode when used endoscopically in a fluid medium to ablate prostatic and vesical tissue. Using the usual parameters for tissue destruction (blanching without charring), the depth of thermal injury in the bladder and ureter was kept superficial. In performing partial nephrectomies, a 2-fold reduction in the zone of coagulative necrosis was demonstrated compared to the use of the continuous wave Neodymium:YAG laser (Nd:YAG). When used through the laparoscope, the Ho:YAG laser provided precise cutting and, combined with electrocautery, allowed the dissection to proceed quickly and smoothly. Hemostatic control was adequate in all surgical procedures. Although the results of these investigations are preliminary, our initial experience with the Ho:YAG laser has been favorable and warrants further investigations.

Solid-state synthesis of YAG powders through microwave coupling of oxide/carbon particulate mixtures

DOE PAGES

Wildfire, Christina; Sabolsky, Edward M.; Spencer, Michael J.; ...

2017-06-14

The rapid synthesis of yttrium aluminum garnet (Y 3Al 15O 12, YAG) powder was investigated through the use of microwave irradiation of the oxide precursor system. For this investigation, an external hybrid heating source was not used. Instead, the rapid heating of the precursor materials (yttria and alumina powders, which are typically transparent to 2.45 GHz microwaves) was initiated by mixing an intrinsic absorbing material (carbon) into the original oxide precursors. The effect of the carbon characteristics, such as carbon source, concentration, particle size, and agglomerate microstructure were evaluated on the efficiency of coupling and resultant oxide reaction. The microwavemore » power was varied to optimize the YAG conversion and eliminate intermediate phase formation. Interactions between the conductive carbon particles and the dielectric oxides within the microwave exposure produced local arching and micro-plasma formation within the powder bed, resulting in the rapid formation of the refractory YAG composition. This optimal conduction led to temperatures of 1000°C that could be achieved in less than 5 min resulting in the formation of > 90 vol% YAG. The understanding of a conductor/dielectric particulate system here, provided insight into possible application of similar systems where microwave irradiation could be used for enhanced solid-state formation, local melting events, and gas phase reactions with a composite powder media.« less

Comparison of the efficacy of different types of lasers for the treatment of peri-implantitis: a systematic review.

PubMed

Natto, Zuhair S; Aladmawy, Majdi; Levi, Paul A; Wang, Hom-Lay

2015-01-01

To evaluate the efficacy of various types of lasers (neodymium-doped yttrium-aluminum-garnet [Nd:YAG], carbon dioxide [CO2], diode, erbium/chromium-doped yttrium-scandium-gallium-garnet [Er,Cr:YSGG], and erbium-doped yttrium-aluminum-garnet [Er:YAG]) in the treatment of peri-implantitis and their use in surgical and nonsurgical procedures. Human studies for the treatment of peri-implantitis with laser therapy, published between 2002 and January 2014, were collected utilizing the electronic databases PubMed, Ovid, MEDLINE, Cochrane, and Google Scholar. Two reviewers conducted the study selection, data collection, and validity assessment. Eight hundred twelve studies were selected in the initial title search; 13 studies were then chosen for this review. No human studies evaluated the effect of the Nd:YAG laser on peri-implantitis. The CO2 laser is reported to be safe and able to enhance bone regeneration. The diode laser (980 nm) seems to be effective in its bactericidal effect without changing the implant surface pattern. The Er,Cr:YSGG laser was reported to obtain bone regeneration around a failing implant in one case, while the Er:YAG laser exhibits a strong bactericidal effect against periodontopathic bacteria at a low energy level. Although lasers have shown promising results in reducing clinical signs of peri-implantitis, because of the limited sample sizes and short follow-up periods, no firm conclusion can be drawn at this moment. Hence, there is a need for more well-designed, longitudinal, randomized controlled clinical trials.

A randomized, split-face clinical trial of low-fluence Q-switched neodymium-doped yttrium aluminum garnet (1,064 nm) laser versus low-fluence Q-switched alexandrite laser (755 nm) for the treatment of facial melasma.

PubMed

Fabi, Sabrina G; Friedmann, Daniel P; Niwa Massaki, Ane B; Goldman, Mitchel P

2014-09-01

Melasma is distressing for patients and challenging for physicians to treat. Clinical data from controlled comparative studies is lacking to support the efficacy, longevity, and safety of laser treatments for melasma. Compare the efficacy and safety of low fluence Q-switched neodymium-doped yttrium aluminum garnet (1,064 nm) laser (Nd:YAG) versus low-fluence Q-switched alexandrite laser (755 nm) (QSAL) for the treatment of facial melasma. Twenty male and female subjects with moderate to severe mixed-type melasma on both sides of the face were randomized to six, weekly treatments with the low-fluence Q-switched Nd:YAG laser on one side and the low-fluence QSAL to the other side. Two independent investigators conducted Modified Melasma Area and Severity Index (MMASI) evaluations and subjects completed self-assessment questionnaires at baseline, after three treatments and each follow-up visit 2, 12, and 24 weeks after the last treatment. Standardized digital photographs were taken at baseline and at each subsequent follow-up visit. One male and fifteen females, mean age of 43.4 (range 32-64) years, completed the 29-week study. Both laser treated sides showed a significant improvement in MMASI evaluations after two treatments (22% improvement on the QS-Nd:YAG, 17% QSAL) and each follow-up visit 2 (36% QS-Nd:YAG; 44% QSAL), 12 (27% QS-Nd:YAG; and 24% QSAL), and 24 weeks (27% QS-Nd:YAG; and 19% QSAL) after the last treatment, but no significant difference was seen between study groups at any visit. There was also no significant difference in subject evaluation of improvement between both treatment sides at any visit. Both laser treated sides were tolerated well, and no serious adverse events were noted. Only one subject was taken out of the study due to development of post-inflammatory hyperpigmentation bilaterally. Both low-fluence Q-switched Nd:YAG and low-fluence QSAL were equally effective at improving moderate to severe mixed-type facial melasma. This was a

Dependence of calculus retropulsion dynamics on fiber size and radiant exposure during Ho:YAG lithotripsy.

PubMed

Lee, Ho; Ryan, Robert T; Kim, Jeehyun; Choi, Bernard; Arakeri, Navanit V; Teichman, Joel M H; Welch, A J

2004-08-01

During pulsed laser lithotripsy, the calculus is subject to a strong recoil momentum which moves the calculus away from laser delivery and prolongs the operation. This study was designed to quantify the recoil momentum during Ho:YAG laser lithotripsy. The correlation among crater shape, debris trajectory, laser-induced bubble and recoil momentum was investigated. Calculus phantoms made from plaster of Paris were ablated with free running Ho:YAG lasers. The dynamics of recoil action of a calculus phantom was monitored by a high-speed video camera and the laser ablation craters were examined with Optical Coherent Tomography (OCT). Higher radiant exposure resulted in larger ablation volume (mass) which increased the recoil momentum. Smaller fibers produced narrow craters with a steep contoured geometry and decreased recoil momentum compared to larger fibers. In the presence of water, recoil motion of the phantom deviated from that of phantom in air. Under certain conditions, we observed the phantom rocking towards the fiber after the laser pulse. The shape of the crater is one of the major contributing factors to the diminished recoil momentum of smaller fibers. The re-entrance flow of water induced by the bubble collapse is considered to be the cause of the rocking of the phantom.

Nd:YAG laser for epithelial ingrowth after laser in situ keratomileusis.

PubMed

Mohammed, Osama Ali; Mounir, Amr; Hassan, Amin Aboali; Alsmman, Alahmady Hamad; Mostafa, Engy Mohamed

2018-05-04

To evaluate the efficacy of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser for treatment of epithelial ingrowth after laser in situ keratomileusis (LASIK). Fifty-eight patients with epithelial ingrowth presented to Sohag refractive center, Sohag, Egypt, between January 2015 and March 2017. Only 41 patients (18 females and 23 males, mean age: 33.4 years) involving 41 eyes were indicated for treatment by Nd:YAG laser as the rest of the eyes were only under observation. Patients with epithelial ingrowth were recognized at a mean of 6 months after primary LASIK procedure (range: 2-16 months). Four eyes had undergone previous LASIK enhancements. Four eyes had the epithelial ingrowth removed by flap lift and scrapping. The mean intensity of the spots used was 0.8 mJ with variable number of shots depending on the size and density of the epithelial ingrowth area. Twenty-eight eyes showed complete regression after one session, while the rest necessitated 2-3 sessions for complete resolution. Mean follow-up period was 8 months (range 5-12 months). Epithelial ingrowth was treated successfully in all 41 eyes. The uncorrected visual acuities were 20/20, and there was no evidence of recurrent epithelial ingrowth after 6 months with no complications reported. YAG laser is a simple, effective outpatient procedure for the management of epithelial ingrowth after LASIK.

Role of the Ho:Yag laser in the treatment of superficial bladder cancer in the elderly

NASA Astrophysics Data System (ADS)

Muraro, Giovanni B.; Grifoni, Riccardo

2002-10-01

Introduction. A considerable confusion exists in literature regarding the comparison between the employ of the laser and TUR for the treatment of Superficial Bladder Cancer (SBC) in terms of tumour recurrences (number, progression of stage and grade, place and time of them) and the economic costs. For this reason we have analysed the two procedures by a retrospective study to evaluate if the laser treatment had same advantages on the TUR which is still now considered the gold standard treatment. Materials and Methods. We examined two groups of 50 elderly patients with DBC, high incidence of comorbilities and anaesthesiological risk, who were treated by TUR or Ho. Yag laser. We considered for teh resected tumours: stage, grade, size, multiplicity, history. Of the recurrences were analysed: number, place, time of appearance, grade and stage. Besides the time of surgical procedure, the complication rate, the catheterization time and the hospital stay were evaluated. Results. There was not a clear difference between laser and TUR about the recurrences for: number (30% and 36%), progressoin of stage and grade, place and time of appearance. An important results it was that at parity of surgical time in the laser group we had: 50% less of complications, 75% of the patients removed the catheter within 24hs with a postoperative stay of 24-48 hs instead of 4% and 40% in the TUR group. Conclusions. We conclude that the use of the Ho: YAG laser is actually the most advantageous method to treat the elderly with comorbilities and affect by little relapsing and low grade SBC for the low complication rate, reduction of the catheritization time, the hospital stay and the economic costs. These results point out that the Ho:Yag laser is an interesting technology to treat the elderly with comorbilities and this characteristic is still more important if we consider that for the ageing of the population we are moving towards an increase of the elderly urological pathology.

Carbon dioxide laser versus erbium:YAG laser in treatment of epidermal verrucous nevus: a comparative randomized clinical study.

PubMed

Osman, Mai Abdel Raouf; Kassab, Ahmed Nazmi

2017-08-01

A verrucous epidermal nevus (VEN) is a skin disorder that has been treated using different treatment modalities with varying results. Ablative lasers such as carbon dioxide laser (CO 2 ) and erbium:yttrium-aluminum-garnet (Er:YAG) laser have been considered as the gold standard for the treatment of epidermal nevi. To evaluate and compare the efficacy, postoperative wound healing and side effects of pulsed CO 2 laser and Er:YAG laser for the treatment of verrucous epidermal nevi. Twenty patients with localized VEN were randomly divided into two groups. Group 1 was administered CO 2 laser and group 2 underwent Er:YAG laser treatment. A blinded physician evaluated the photographs and dermoscopic photomicrographs for the efficacy and possible side effects. All patients received one treatment session and were followed up over a 6-month period. Both lasers induced noticeable clinical improvement, but there were no significant differences between two lasers in treatment response, patient satisfaction, duration of erythema and side effects. The average time to re-epithelialization was 13.5 days with CO 2 and 7.9 days with Er:YAG laser (p< .0005). No scarring was observed in Er:YAG laser group and no lesional recurrence was detected in CO 2 laser group since treatment. Apart from re-epithelialization, both lasers showed equivalent outcomes with respect to treatment response, patient satisfaction, side effects and complications.

Skin Pretreatment With Conventional Non-Fractional Ablative Lasers Promote the Transdermal Delivery of Tranexamic Acid.

PubMed

Hsiao, Chien-Yu; Sung, Hsin-Ching; Hu, Sindy; Huang, Chun-Hsun

2016-07-01

Laser pretreatment of skin can be used to enable drugs used in dermatology to penetrate the skin to the depth necessary for their effect to take place. To compare the permeation of tranexamic acid after conventional non-fractionated ablative Er:YAG and CO2 laser pretreatment in a laser-aided transdermal delivery system. An erbium-doped yttrium aluminium garnet (Er:YAG) and a CO2 laser were used to pretreat dorsal porcine skin. Scanning electron microscopy was used to examine disruption of the skin surface. Confocal laser scanning microscopy was used to determine the depth of penetration of a reporter molecule (fluorescein isothiocyanate) into the skin. A Franz diffusion assembly was used to examine fluency-related increases in transdermal delivery of transexamic acid. Transdermal delivery of tranexamic acid increased as Er:YAG laser fluency increased. Transdermal delivery was higher when CO2 laser pretreatment was used than when Er:YAG laser pretreatment was used, but a "ceiling effect" was present and increasing the wattage did not cause a further increase in delivery. CO2 laser pretreatment also caused more extensive and deeper skin disruption than Er:YAG laser pretreatment. For conventional, non-fractionated ablative laser pretreatment, the Er:YAG laser would be an optimal choice to enhance transdermal penetration of transexamic acid.

CIE colorimetric system fails to calculate the chroma of a Nd:YAG crystal under the fluorescent illuminant F7

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Qinghan; Bu, Xianhui; Feng, Pingyun

2002-06-01

The rare earth element neodymium doped yttrium aluminum garnet (Nd:YAG) is a laser crystal widely used for producing laser in the infrared range. Neodymium causes many characteristic absorption peaks in the transmittance spectrum of the Nd:YAG crystal in the visible range. The crystal appears pink under daylight and incandescent light, and colorless under fluorescent light. The colorimetric calculation results of chroma under the CIE standard fluorescent illuminant F7 do not agree with the color appearance under fluorescent light. The calculated chroma values should be near zero to agree with a colorless appearance, but it is actually 11.79 in the CIELAB color space. This failure of the colorimetric calculation is caused by the color matching functions of the CIE colorimetric observers. The color matching functions do not agree with the spectral sensitivity curves of the human eye, especially the x(λ) function does not matches the spectral sensitivity curve of the long wavelength cone photoreceptors.

In vitro analysis of laser meniscectomy.

PubMed

Vangsness, C T; Akl, Y; Nelson, S J; Liaw, L H; Smith, C F; Marshall, G J

1995-01-01

Partial meniscectomies were performed on 32 fresh human meniscal autopsy specimens. The following laser systems were tested: carbon dioxide (CO2), neodymium:yttrium aluminum garnet (Nd:YAG), potassium titanyl phosphate (KTP), holmium:YAG (Ho:YAG), and excimer. Meniscectomies with these lasers were compared with scalpel, mechanical, and electrocautery meniscectomies. Lasers were applied to specimens in and out of normal saline. Routine hematoxylin and eosin and sirius red sections were prepared for each specimen, and the depths of thermal changes were analyzed. Scanning electron microscopy was used to visualize the meniscectomy interface. Among these specimens, the scalpel and mechanical meniscectomies showed the least extension of cellular changes (range, 10-15 nm). The excimer laser caused the least tissue changes of the lasers tested. Tissue changes were less extensive with the pulsed CO2 laser than with the holmium:YAG, neodymium:YAG, and KTP lasers. Scanning electron microscopy showed that use of the scalpel meniscectomy resulted in the smoothest meniscectomy edge, followed by use of the excimer, CO2, holmium:YAG, neodymium:YAG, and KTP lasers. The most surface disruption occurred with electrocautery. Meniscectomies under saline required more energy and took longer in each case, with the holmium:YAG, neodymium:YAG, and CO2 laser cutting the best. Saline meniscectomies showed less thermal change. The CO2 and KTP lasers cut best in air.

Effect of Annealing Time of YAG:Ce3+ Phosphor on White Light Chromaticity Values

NASA Astrophysics Data System (ADS)

Abd, Husnen R.; Hassan, Z.; Ahmed, Naser M.; Almessiere, Munirah Abdullah; Omar, A. F.; Alsultany, Forat H.; Sabah, Fayroz A.; Osman, Ummu Shuhada

2018-02-01

Yttrium and aluminium nitrate phosphors doped with cerium nitrate and mixed with urea (fuel) are prepared by using microwave-induced combustion synthesis according to the formula Y(3-0.06)Al5O12:0.06Ce3+ (YAG:Ce3+) to produce white light emitting diodes by conversion from blue indium gallium nitride-light emitting diode chips. The sintering time with fixed temperature (1050°C) for phosphor powder was optimized and found to be 5 h. The crystallinity, structure, chemical composition, luminescent properties with varying currents densities and chromaticity were characterized by x-ray diffraction, field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, photoluminescence emission, electroluminescence and standard CIE 1931 chromaticity diagram, respectively. The energy levels of Ce3+ in YAG were discussed based on its absorption and excitation spectra. The results show that the obtained YAG:Ce3+ phosphor sintered for 5 h has good crystallinity with pure phase, low agglomerate with spherical shaped particles and strong yellow emission, offering cool-white LED with tuneable correlated color temperature and a good color rendering index compared to those prepared by sintering for 2 h and as-prepared phosphor powders.

High-efficiency control of spin-wave propagation in ultra-thin yttrium iron garnet by the spin-orbit torque

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evelt, M.; Demidov, V. E., E-mail: demidov@uni-muenster.de; Bessonov, V.

2016-04-25

We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by themore » nonlinear scattering of the coherent spin waves from current-induced excitations.« less

Postoperative discomfort after Nd:YAG laser and conventional frenectomy: comparison of both genders.

PubMed

Akpınar, A; Toker, H; Lektemur Alpan, A; Çalışır, M

2016-03-01

Evidence has suggested that males and females experience and report feeling pain differently. The aim of this study was to determine the postoperative perception levels of both females and males after neodymium-doped yttrium aluminum garnet (Nd:YAG) laser frenectomy and conventional frenectomy, and to compare the perceptions between genders. Eighty-nine patients requiring frenectomy were randomly assigned to have treatment with either the conventional frenectomy or with the Nd:YAG laser. Postoperative discomfort (pain, chewing, talking) was recorded using a visual analog scale (VAS) on the operation day and postoperative days 1, 3, 7 and 10. According to the female VAS scores of the pain, chewing and speaking discomfort were statistically higher in the conventional group than those of the laser group on the operation day, and on the first and third postoperative days. Pain discomfort in males was statistically higher in the conventional group than those of the laser group on the operation day. Speaking discomfort in males was statistically higher in the conventional group than those of the laser group on the operation day and the first postoperative day. The present study indicated that Nd:YAG laser treatment used for frenectomies provides better postoperative comfort for each gender, especially in females in terms of pain, chewing and speaking than the conventional procedure up to the seventh postoperative day. According to our results, Nd:YAG laser may provide a safe, bloodless, painless surgery and an impressive alternative for frenectomy operations. © 2015 Australian Dental Association.

Generation of coherent spin-wave modes in yttrium iron garnet microdiscs by spin–orbit torque

PubMed Central

Collet, M.; de Milly, X.; d'Allivy Kelly, O.; Naletov, V. V.; Bernard, R.; Bortolotti, P.; Ben Youssef, J.; Demidov, V. E.; Demokritov, S. O.; Prieto, J. L.; Muñoz, M.; Cros, V.; Anane, A.; de Loubens, G.; Klein, O.

2016-01-01

In recent years, spin–orbit effects have been widely used to produce and detect spin currents in spintronic devices. The peculiar symmetry of the spin Hall effect allows creation of a spin accumulation at the interface between a metal with strong spin–orbit interaction and a magnetic insulator, which can lead to a net pure spin current flowing from the metal into the insulator. This spin current applies a torque on the magnetization, which can eventually be driven into steady motion. Tailoring this experiment on extended films has proven to be elusive, probably due to mode competition. This requires the reduction of both the thickness and lateral size to reach full damping compensation. Here we show clear evidence of coherent spin–orbit torque-induced auto-oscillation in micron-sized yttrium iron garnet discs of thickness 20 nm. Our results emphasize the key role of quasi-degenerate spin-wave modes, which increase the threshold current. PMID:26815737

Large Screen Display Technology Survey.

DTIC Science & Technology

1984-07-01

gadolinium gallium garnet ). The film is etched to form small light sensitive cells. The area between the cells is covered with a metal film to block the light...Failures MTTR - Mean-Time-To-Repair Nd:YAG - Noedymium: Yttrium Aluminum Garnet Nematic - A term used to describe one of the states of certain liquid...valve within a display, projection or optical processing system. It uses garnet films grown on non-magnetic substrates (Figure 10). The garnet films can

Fractionated Er:YAG laser versus fully ablative Er:YAG laser for scar revision: Results of a split scar, double blinded, prospective trial.

PubMed

Tidwell, W James; Owen, Cindy E; Kulp-Shorten, Carol; Maity, Abhishek; McCall, Michael; Brown, Timothy S

2016-11-01

Ablative laser resurfacing is a common treatment for post-surgical scars. Fractional ablative laser resurfacing has been an emerging treatment option that is replacing fully ablative lasers in many applications. Data comparing fractionated and fully ablative lasers in treating post-operative scars are lacking. Twenty patients were enrolled in a split scar study following excisions from dermatologic surgery. Wounds had to be older than 8 weeks but less than 1 year. The scars were randomly divided into two halves. One half of the scar was treated with fully ablative erbium-doped yttrium aluminum garnet (Er:YAG) and the other was treated with fractionated Er:YAG. The scars were treated at monthly intervals for 3 months, then followed up at months 1 and 2 after the last treatment. POSAS was used to evaluate the scars by a panel of dermatologists blinded to the lasers in conjunction with the patients, who were also blinded. Physicians and patients both observed a superior outcome of 32.5% (P = 0.019) and 58.1% (P = 0.001), respectively, using the POSAS. There was no trend in difference in pain reported by the patient between the two lasers. Patients overwhelmingly preferred the fractionated Er:YAG laser (94%) to the fully ablative laser when asked at the end of the study. Although this study is limited by a short follow-up period, it shows a statistically significant superior outcome in fractionated Er:YAG over fully ablative Er:YAG for scar revision. It also adds quantitative values to the assessment of scar appearance when treated with fractionated lasers compared to fully ablative lasers. It was also found that the fractionated Er:YAG had increased patient satisfaction, but there was no difference in reported pain scores. These data are useful when counseling patients undergoing laser surgery. Lasers Surg. Med. 48:837-843, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Color centers inside crystallic active media

NASA Astrophysics Data System (ADS)

Mierczyk, Zygmunt; Kaczmarek, Slawomir M.; Kopczynski, Krzysztof

1995-03-01

This paper presents research results on color centers induced by radiation of a xenon lamp in non doped crystals of yttrium aluminum garnet Y3Al5O12 (YAG), strontium- lanthanum aluminate SrLaAlO4 (SLAO), strontium-lanthanum gallate SrLaGa3O7 (SLGO), and in doped crystals: Nd:YAG, Cr, Tm, Ho:YAG (CTH:YAG), Nd:SLAO and Nd:SLGO. In all these investigated crystals under the influence of intensive exposure by xenon lamp radiation additional bands connected with centers O-2, O2 and centers F came up near the short-wave absorption edge. In the case of doped crystals the observed processes are much more complicated. In crystals CTH:YAG the greatest perturbations in relation to basic state are present at the short-wave absorption edge, as well as on areas of absorption bands of ions Cr+3 and Tm+3 conditioning the sensibilization process of ions Ho+3. These spectral structure disturbances essentially influence the efficiency of this process, as proven during generating investigations. In the case of SrLaGa3O7:Nd+3 under the influence of exposure substantial changes of absorption spectrum occurred on spectral areas 346 divided by 368 nm, 429 divided by 441 nm and 450 divided by 490 nm. Those changes have an irreversible character. They disappear not before the plate is being held at oxidizing atmosphere. Investigations of laser rods Nd:SLGO, CTH:YAG, and Nd:YAG in a free generation demonstrated that the color centers of these crystals are induced by pomp radiation from the spectral area up to 450 nm.

Effect of laser peripheral iridotomy using argon and neodymium-YAG lasers on corneal endothelial cell density: 7-year longitudinal evaluation.

PubMed

Ono, Takashi; Iida, Masaharu; Sakisaka, Toshihiro; Minami, Keiichiro; Miyata, Kazunori

2018-03-01

To evaluate the changes in corneal endothelial cell density (ECD) over a 7-year period after laser peripheral iridotomy (LPI) using argon and neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers. Retrospective case series. Eyes that underwent prophylactic LPI using argon and Nd:YAG lasers were followed up for 7 years. Central corneal endothelial cells were observed by use of noncontact specular microscopy preoperatively and at 1 and 7 years postoperatively. Changes in ECD and the associations between preoperative ECD and the total energy of the Nd:YAG laser were evaluated. Fifty-one eyes of 51 patients were followed up for 7 years. The ECD significantly decreased after LPI (P < 0.049), and the reduction rate at 1 year after the surgery (1.69 ± 4.80%, 95% CI: 0.34%-3.04%) was significantly higher than the annual reduction rates after 1 year (0.17 ± 0.85%/y, P = 0.036, 95% CI: -0.07% to 0.41%). No association was found between the preoperative ECD and the total laser energy. Long-term evaluation indicated that the reduction in ECD after argon-Nd:YAG laser LPI was present but small during the initial year and was negligible after 1 year.

Synchronization of 1064 and 1319 nm Pulses Emitted from Actively Mode-Locked Nd:YAG Lasers and Its Application to 589 nm Sum-Frequency Generation

NASA Astrophysics Data System (ADS)

Saito, Norihito; Akagawa, Kazuyuki; Hayano, Yutaka; Saito, Yoshihiko; Takami, Hideki; Iye, Masanori; Wada, Satoshi

2005-11-01

Sum-frequency generation was carried out by mixing 1064 and 1319 nm pulses emitted from actively mode-locked neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers for efficient 589 nm light generation. A radio frequency of approximately 75 MHz was split into two and fed to acousto-optic mode lockers of two lasers for mode-locked operation. The synchronization of the pulses was achieved by controlling the phase difference between the radio frequencies. The maximum output power at 589 nm reached 260 mW, which corresponded to an energy conversion efficiency of more than 13%. The output power was 3.8-fold that in continuous-wave operation.

Evaluation of erbium:YAG and holmium:YAG laser radiation and dental hard tissue

NASA Astrophysics Data System (ADS)

Attrill, David Cameron

Lasers have become increasingly established in medicine as effective alternatives or adjuncts to conventional techniques. In dentistry, several clinical laser systems have been developed and marketed, but their applications have been limited to soft tissue surgery. To date, no laser has been capable of effectively cutting or modifying the highly mineralised dental tissues of enamel and dentine. The aim of this study was to evaluate two new laser systems for use in dentistry through a series of in vitro experiments. Both generic erbium and holmium lasers have theoretically superior operating characteristics over currently established lasers for applications with dental hard tissues. The two lasers investigated in this study were pulsed Er:YAG (lambda=2.94) a.m. and Cr-Tm-Ho:YAG (lambda=2.1mu.m). Both operated with a macropulse duration of approximately 200lambdas, at pulse repetition rates of 2-8Hz and mean pulse energies up to 230mJ. Radiation was focused using CaF[2] lenses (f=50-120mm). The lasers could be operated with or without the addition of a surface water film at the interaction site. Tissue removal efficiency was expressed as a latent heat of ablation (LHA, kJ/cm[3]) using a modification of the technique described by Charlton et al. (1990). The mean LHA's for the Er:YAG laser were 6.24kJ/cm[3] and 22.99kJ/cm[3] with dentine and enamel respectively without water, and 10.07kJ/cm[3] and 18.73kJ/cm[3] for dentine and enamel with water. The Cr-Tm-Ho:YAG laser was unable to effectively remove enamel at the fluences and pulse energies available; the mean LHA's for the Cr-Tm- Ho:YAG laser with dentine were 82.79kJ/cm3 and 57.57kJ/cm3 with and without water respectively. The Cr-Tm-Ho;YAG was approximately 8-9 times less efficient for tissue removal than the Er:YAG system. Er:YAG tissue removal with water was characterised by clean "surgical" cuts, comparable in histological appearance to those obtained using conventional instrumentation. Some thermal disruption

Protective Effect of Adhesive Systems associated with Neodymium-doped Yttrium Aluminum Garnet Laser on Enamel Erosive/Abrasive Wear.

PubMed

Crastechini, Erica; Borges, Alessandra B; Becker, Klaus; Attin, Thomas; Torres, Carlos Rg

2017-10-01

This study evaluated the efficacy of self-etching adhesive systems associated or not associated with the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser on the protection against enamel erosive/abrasive wear. Bovine enamel specimens were demineralized with 0.3% citric acid (5 minutes). The samples were randomly assigned to eight groups (n = 20): SB - Single Bond Universal (3M/ESPE); SB+L - Single Bond Universal + laser (80 mJ/10 Hz); FB - Futurabond U (Voco); FB+L -Futurabond U + laser; GEN - G-aenial bond (GC); GEN+L -G-aenial bond + laser; L - laser irradiation; and C - no treatment. The laser was applied before light curing. The samples were subjected to erosive/abrasive challenges (0.3% citric acid - 2 minutes and tooth brushing four times daily for 5 days). Enamel surface loss was recovered profilometrically by comparison of baseline and final profiles. The adhesive layer thickness, retention percentage of the protective layer, and microhardness of cured adhesive were measured. Data were analyzed using one-way analysis of variance and Tukey's test (5%). There were significant differences for all parameters (p = 0.0001). Mean values ± SD and results of the Tukey's test were: Surface wear: GEN - 4.88 (±1.09)a, L - 5.04 ± 0.99)a, FB - 5.32 (±0.93)ab, GEN + L - 5.46 (±1.27)abc, SB + L - 5.78 (±1.12)abc, FB + L - 6.23 (±1.25)bc, SB - 6.35 (±1.11)c, and C - 6.46 (±0.61)c; layer thickness: GEN - 15.2 (±8.63)c, FB - 5.06 (±1.96)a, GEN + L - 13.96 (±7.07)bc, SB + L - 4.24 (±2.68)a, FB + L - 9.03 (±13.02)abc, and SB - 7.49 (±2.80)ab; retention: GEN - 68.89 (±20.62)c, FB - 54.53 (±24.80)abc, GEN + L - 59.90 (±19.79)abc, SB + L - 63.37 (±19.30)bc, FB + L - 42.23 (±17.68) a, and SB - 47.78 (±18.29)ab; microhardness: GEN - 9.27 (±1.75)c; FB - 6.99 (±0.89)b; GEN + L - 6.22 (±0.87)ab; SB + L - 15.48 (±2.51)d; FB + L - 10.67 (±1.58)c; SB - 5.00 (±1.60)a. The application of Futurabond U and G-aenial bond on enamel surface, as well as the Nd:YAG

Transmission of Er:YAG laser through different dental ceramics.

PubMed

Sari, Tugrul; Tuncel, Ilkin; Usumez, Aslihan; Gutknecht, Norbert

2014-01-01

The aim of this study was to determine the erbium-doped yttrium aluminum garnet (Er:YAG) laser transmission ratio through different dental ceramics with different thicknesses. Laser debonding procedure of adhesively luted all-ceramic restorations is based on the transmission of laser energy through the ceramic and the ablation of resin cement, because of the transmitted laser energy. Five different dental ceramics were evaluated in this study: sintered zirconium-oxide core ceramic, monolithic zirconium-oxide ceramic, feldspathic ceramic, leucite-reinforced glass ceramic, and lithium disilicate-reinforced glass ceramic. Two ceramic discs with different thicknesses (0.5 and 1 mm) were fabricated for each group. Ceramic discs were placed between the sensor membrane of the laser power meter and the tip of the contact handpiece of an Er:YAG laser device with the aid of a custom- made acrylic holder. The transmission ratio of Er:YAG laser energy (500 mJ, 2 Hz, 1 W, 1000 μs) through different ceramic discs was measured with the power meter. Ten measurements were made for each group and the results were analyzed with two way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests. The highest transmission ratio was determined for lithium disilicate-reinforced ceramic with 0.5 mm thickness (88%) and the lowest was determined for feldspathic ceramic with 1 mm thickness (44%). The differences among the different ceramics and between the different thicknesses were significant (p<0.05). Ceramic type and thickness should be taken into consideration to adjust the laser irradiation parameters during laser debonding of adhesively luted all-ceramic restorations.

A comparative investigation of bone surface after cutting with mechanical tools and Er:YAG laser.

PubMed

Baek, Kyung-Won; Deibel, Waldemar; Marinov, Dilyan; Griessen, Mathias; Dard, Michel; Bruno, Alfredo; Zeilhofer, Hans-Florian; Cattin, Philippe; Juergens, Philipp

2015-07-01

Despite of the long history of medical application, laser ablation of bone tissue became successful only recently. Laser bone cutting is proven to have higher accuracy and to increase bone healing compared to conventional mechanical bone cutting. But the reason of subsequent better healing is not biologically explained yet. In this study we present our experience with an integrated miniaturized laser system mounted on a surgical lightweight robotic arm. An Erbium-doped Yttrium Aluminium Garnet (Er:YAG) laser and a piezoelectric (PZE) osteotome were used for comparison. In six grown up female Göttingen minipigs, comparative surgical interventions were done on the edentulous mandibular ridge. Our laser system was used to create different shapes of bone defects on the left side of the mandible. On the contralateral side, similar bone defects were created by PZE osteotome. Small bone samples were harvested to compare the immediate post-operative cut surface. The analysis of the cut surface of the laser osteotomy and conventional mechanical osteotomy revealed an essential difference. The scanning electron microscopy (SEM) analysis showed biologically open cut surfaces from the laser osteotomy. The samples from PZE osteotomy showed a flattened tissue structure over the cut surface, resembling the "smear layer" from tooth preparation. We concluded that our new finding with the mechanical osteotomy suggests a biological explanation to the expected difference in subsequent bone healing. Our hypothesis is that the difference of surface characteristic yields to different bleeding pattern and subsequently results in different bone healing. The analyses of bone healing will support our hypothesis. © 2015 Wiley Periodicals, Inc.

Phase separation, crystallization and polyamorphism in the Y2O3 Al2O3 system

NASA Astrophysics Data System (ADS)

Skinner, Lawrie B.; Barnes, Adrian C.; Salmon, Philip S.; Crichton, Wilson A.

2008-05-01

A detailed study of glass formation from aerodynamically levitated liquids in the (Y2O3)x(Al2O3)1-x system for the composition range 0.21<=x<=0.41 was undertaken by using pyrometric, optical imaging and x-ray diffraction methods. Homogeneous and clear single-phase glasses were produced over the composition range 0.27 \\lesssim x \\lesssim 0.33 . For Y2O3-rich compositions (0.33 \\lesssim x \\le 0.375 ), cloudy materials were produced which contain inclusions of crystalline yttrium aluminium garnet (YAG) of diameter up to 40 µm in a glassy matrix. For Y2O3-poor compositions around x = 0.24, cloudy materials were also produced, but it was not possible to deduce whether this resulted from (i) sub-micron inclusions of a nano-crystalline or glassy material in a glassy matrix or (ii) a glass formed by spinodal decomposition. For x = 0.21, however, the sample cloudiness results from crystallization into at least two phases comprising yttrium aluminium perovskite and alumina. The associated pyrometric cooling curve shows slow recalescence events with a continuous and slow evolution of excess heat which contrasts with the sharp recalescence events observed for the crystallization of YAG at compositions near x = 0.375. The materials that are the most likely candidates for demonstrating homogeneous nucleation of a second liquid phase occur around x = 0.25, which corresponds to the limit for formation of a continuous random network of corner-shared AlO4 tetrahedra.

Comparative in vitro study of tissue welding using a 808 nm diode laser and a Ho:YAG laser.

PubMed

Ott, B; Züger, B J; Erni, D; Banic, A; Schaffner, T; Weber, H P; Frenz, M

2001-01-01

In vitro porcine arteries and veins have been welded end-to-end using either a 808 nm diode laser combined with an indocyanine green enhanced albumin solder, or with a continuous-wave (cw) Ho:YAG laser without biological solder. The vascular stumps were approached to each other over a coronary dilatation catheter in order to obtain a precise alignment and good coaptation. Standard histology revealed for both welding techniques lateral tissue damage between 2 and 3 mm caused by laser-induced heat. Good solder attachment to the tissue was observed by the use of a scanning electron microscope. The vessels soldered with the 808 nm diode laser using albumin solder showed considerably higher tensile strength (1 N compared to 0.3 N) than vessels welded exclusively by Ho:YAG laser radiation. In contrast, leaking pressure (350 +/- 200 mmHg) and bursting pressure (457 +/- 200 mmHg) were found to be independent of the welding technique used. This study demonstrates that fast (total welding time about 2-5 min), stable and tight microvascular anastomosis can be achieved with the use of a dye-enhanced albumin laser soldering technique and an ancillary coronary dilatation catheter.

Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study

NASA Astrophysics Data System (ADS)

Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

2017-11-01

Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18 J/cm2 in the mesentery model and from 36 to 31 J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions.

Fracture Resistance of Endodontically Retreated Roots After Retreatment Using Self-Adjusting File, Passive Ultrasonic Irrigation, Photon-Induced Photoacoustic Streaming, or Laser.

PubMed

Kamalak, Aliye; Uzun, Ismail; Arslan, Hakan; Keleş, Ali; Doğanay, Ezgi; Keskin, Cangül; Akçay, Merve

2016-10-01

Additional cleaning techniques and devices are required to remove maximum amount of residual filling material, which might limit disinfection of root canal system during retreatment. This study aimed to compare fracture resistance of roots when self-adjusting file (SAF), photon-induced photoacoustic streaming (PIPS), passive ultrasonic irrigation (PUI), erbium-doped yttrium aluminum garnet (Er:YAG), or neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers are applied following the use of retreatment files in endodontics. A total of 117 human mandibular canine teeth of similar dimensions were selected and divided into nine groups (n = 13). Aside from control, instrumented, and only-prepared groups, 91 teeth were remaining, of which 13 were assigned to the only-filling group and final 78 to retreatment, thus R-Endo file, R-Endo+SAF, R-Endo+PUI, R-Endo+Er:YAG laser, R-Endo+Nd:YAG laser, and R-Endo+PIPS. The fracture strengths of the retreatment groups were lower than control, instrumented, and only-filling groups (p < 0.05). There was no difference between the R-Endo group and additional retreatment procedure groups (p > 0.05). Further cleaning methods using SAF, PIPS, Er:YAG laser, Nd:YAG laser, or PUI did not decrease the fracture resistance when compared with the R-Endo group.

Treatment of actinic cheilitis with the Er:YAG laser.

PubMed

Armenores, Paul; James, Craig L; Walker, Patrick C; Huilgol, Shyamala C

2010-10-01

Actinic cheilitis is a common condition with the potential to develop into squamous cell carcinoma. Current treatments have varying cure rates and complications. The role of the erbium:yttrium-aluminum-garnet (Er:YAG) laser in the treatment of actinic cheilitis has not been widely published, despite offering theoretical advantages over current treatment modalities. To evaluate the outcome of a series of patients treated with the Er:YAG laser for actinic cheilitis. This was a retrospective, interventional, nonrandomized, sequential case series set in a tertiary referral, dermatologic surgery unit. Ninety-nine consecutive patients with actinic cheilitis treated with the Er:YAG laser between January 2001 and June 2008 underwent a case note review, of which 77 went on to a structured telephone interview. The main outcome measures were a subjective improvement in lip symptoms related to actinic cheilitis and objective improvement in the lips at routine follow-up. Mean time to interview follow-up was 65.7 months. Of those interviewed, 92.2% believed there had been an improvement in the cosmetic appearance of their lips; one hundred percent believed the function of their lips had improved or remained unchanged; and 84.8% remained completely disease free at the time of follow-up. The majority of patients (93.5%) were satisfied with the laser treatment. Scarring as a direct result of the laser occurred in 5.1% of patients. Retrospective nature of data collection; inability to interview all patients who underwent treatment. The Er:YAG laser is a successful modality for the treatment of actinic cheilitis with good functional and cosmetic results and only a small risk of long-term scarring. It should be considered as a first-line treatment for the disease. Copyright © 2009 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

Tissue effects of Ho:YAG laser with varying fluences and pulse widths

NASA Astrophysics Data System (ADS)

Vari, Sandor G.; van der Veen, Maurits J.; Pergadia, Vani R.; Shi, Wei-Qiang; Duffy, J. T.; Weiss, Andrew B.; Fishbein, Michael C.; Grundfest, Warren S.

1994-02-01

We investigated the effect of varying fluence and pulse width on the ablation rate and consequent thermal damage of the Ho:YAG (2.130 micrometers ) laser. The rate of ablation on fresh bovine knee joint tissues, fibrous cartilage, hyaline cartilage, and bone in saline was determined after varying the fluence (160 - 640 J/cm2) and pulse width (150, 250, 450 microsecond(s) ec, FWHM) at a repetition rate of 2 Hz. A 400/440 micrometers fiber was used. The ablation rate increased linearly with the fluence. In fibrocartilage, different pulse durations generated significant changes in the ablation rates, but showed minor effects on hyaline cartilage and bone. The heat of ablation for all three tissue types decreased after lengthening the pulse.

Reflection and Transmission Coefficient of Yttrium Iron Garnet Filled Polyvinylidene Fluoride Composite Using Rectangular Waveguide at Microwave Frequencies

PubMed Central

Soleimani, Hassan; Abbas, Zulkifly; Yahya, Noorhana; Shameli, Kamyar; Soleimani, Hojjatollah; Shabanzadeh, Parvaneh

2012-01-01

The sol-gel method was carried out to synthesize nanosized Yttrium Iron Garnet (YIG). The nanomaterials with ferrite structure were heat-treated at different temperatures from 500 to 1000 °C. The phase identification, morphology and functional groups of the prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The YIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by a solution casting method. The magnitudes of reflection and transmission coefficients of PVDF/YIG containing 6, 10 and 13% YIG, respectively, were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequencies. The results indicate that the presence of YIG in polymer composites causes an increase in reflection coefficient and decrease in transmission coefficient of the polymer. PMID:22942718

Biokinetics of yttrium and comparison with its geochemical twin holmium

DOE PAGES

Leggett, Rich

2017-06-01

The transition metal yttrium (Y, atomic number 39) is chemically similar to elements in the lanthanide family (atomic numbers 57-71, lanthanum through lutetium) and is always present with the lanthanides in rare earth ores. Yttrium and the lanthanide holmium are particularly close chemical and physical analogues and are referred to as geochemical twins because they typically show little fractionation in geological material. Extensive measurements on rocks, soils, and meteorites indicate that the Y/Ho mass concentration ratio rarely falls far from the “chondritic” or “solar system” ratio of ~26. Our paper presents a new biokinetic model for yttrium in adult humansmore » and examines whether yttrium and holmium may be biological as well as geochemical twins. Collected data on yttrium and holmium in plants and human tissues do not allow precise derivations of Y/Ho concentration ratios but with occasional exceptions yield ratios that are reasonably consistent with chondritic values. Predictions of the time-dependent behavior of yttrium in adult humans based on the yttrium model presented here closely approximate predictions of the behavior of holmium based on a previously developed model for holmium. We know that yttrium and holmium are close biological analogues, but the available comparative data are too limited and imprecise to reveal whether there are any significant differences in their biological behavior.« less

Is There Segregation of Rare Earth Ions in Garnet Optical Ceramics?

NASA Astrophysics Data System (ADS)

Boulon, Georges; Epicier, T.; Zhao, W.; Guzik, M.; Pan, Y.; Jiang, B.

Research on advanced optical materials for a large variety of applications is always increasing. As an example, we can note high progress in solid-state laser sources like laser-diode (LD) - pumped solid-state lasers (DPSSL) including developments of new materials and high-power laser diode led to high-power and tuneable solid-state lasers. A wide variety of materials has been studied to develop more efficient and high power microchip lasers [1]. In end-pumping schemes, in particular, materials with a short absorption length for the LD pump beam are strongly anticipated for highly efficient operations because of the excellent match between the mode and pump beam profiles. High Nd3+ concentrations were so considered such as NdP5O14, LiNdP4O12 (LNP), and NdAl3(BO3)O4. However, crystal growths of these compositions are not so easy. Cubic crystals are much more researched. When looking at the literature for actual applications, we see immediately the importance of cubic garnet crystals for which dodecahedral (Y3+), octahedral (Al3+) and tetrahedral (Al3+) sites are considered as a reservoir for many activators like: Ce3+, Nd3+, Er3+, Tm3+, Ho3+, Yb3+ rare earth ions in dodecahedral symmetry sites and transition metal ions like Cr3+ in the octahedral symmetry sites or Cr4+ in the tetrahedral symmetry sites. Among garnet crystals, Y3Al5O12 (YAG) host is the most used, commercially produced by the Czochralski method. However, in the case of the most used Nd3+: YAG laser crystal, the Nd3+ concentration that affects the performance in laser applications, is strongly limited to 0.2-1.4 Nd3+ at. % as a result of the segregation distribution coefficient [1].

Ho3+-doped strontium-aluminium-bismuth-borate glasses for green light emission.

PubMed

Rajesh, D; Dhamodhara Naidu, M; Ratnakaram, Y C; Balakrishna, A

2014-11-01

Strontium-aluminium-bismuth-borate glasses (SAlBiB) doped with different concentrations of Ho(3+) were prepared using conventional melt quenching technique and their structural and optical properties investigated. X-ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd-Ofelt (J-O) theory was applied to evaluate J-O intensity parameters, Ω(λ) (λ = 2, 4 and 6). Using J-O intensity parameters, radiative properties such as spontaneous transition probabilities (A(R)), branching ratios (β(R)) and radiative lifetimes (τ(R)) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, (5)S2 ((5)F4)→(5)I(8) was observed. Emission peak positions (λ(P)), effective bandwidths (Δλ(eff)) and stimulated emission cross-sections (σ(p)) were calculated for the observed emission transitions, (5)F3 →(5)I(8), (5)S2((5)F4)→(5)I(8) and (5)F5 →(5)I(8) of Ho(3+) in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho(3+) has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of Er:YAG Laser and Sandblasting in Recycling of Ceramic Brackets.

PubMed

Yassaei, Soghra; Aghili, Hossein; Hosseinzadeh Firouzabadi, Azadeh; Meshkani, Hamidreza

2017-01-01

Introduction: This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting. Methods: Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores. Results: The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent. Conclusion: According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice.

Effect of Er:YAG Laser and Sandblasting in Recycling of Ceramic Brackets

PubMed Central

Yassaei, Soghra; Aghili, Hossein; Hosseinzadeh Firouzabadi, Azadeh; Meshkani, Hamidreza

2017-01-01

Introduction: This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting. Methods: Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores. Results: The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent. Conclusion: According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice. PMID:28912939

Advances in laser technology and fibre-optic delivery systems in lithotripsy.

PubMed

Fried, Nathaniel M; Irby, Pierce B

2018-06-08

The flashlamp-pumped, solid-state holmium:yttrium-aluminium-garnet (YAG) laser has been the laser of choice for use in ureteroscopic lithotripsy for the past 20 years. However, although the holmium laser works well on all stone compositions and is cost-effective, this technology still has several fundamental limitations. Newer laser technologies, including the frequency-doubled, double-pulse YAG (FREDDY), erbium:YAG, femtosecond, and thulium fibre lasers, have all been explored as potential alternatives to the holmium:YAG laser for lithotripsy. Each of these laser technologies is associated with technical advantages and disadvantages, and the search continues for the next generation of laser lithotripsy systems that can provide rapid, safe, and efficient stone ablation. New fibre-optic approaches for safer and more efficient delivery of the laser energy inside the urinary tract include the use of smaller-core fibres and fibres that are tapered, spherical, detachable or hollow steel, or have muzzle brake distal fibre-optic tips. These specialty fibres might provide advantages, including improved flexibility for maximal ureteroscope deflection, reduced cross section for increased saline irrigation rates through the working channel of the ureteroscope, reduced stone retropulsion for improved stone ablation efficiency, and reduced fibre degradation and burnback for longer fibre life.

Stress-induced waveguides in Nd:YAG by simultaneous double-beam irradiation with femtosecond pulses

NASA Astrophysics Data System (ADS)

Castillo, Gabriel R.; Romero, Carolina; Lifante, Ginés; Jaque, Daniel; Chen, Feng; Varela, Óscar; García-García, Enrique; Méndez, Cruz; Camacho-López, Santiago; Vázquez de Aldana, Javier R.

2016-01-01

We report on the fabrication of stress-induced waveguides in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) by simultaneous double-beam irradiation with femtosecond laser pulses. An interferometer was used to generate two femtosecond laser beams that, focused with certain lateral separation inside the crystal, produced two parallel damage tracks with a single scan. The propagation of the mechanical waves simultaneously created in both focal spots produced a highly symmetrical stress field that is clearly revealed in micro-luminescence maps. The optical properties of the double-beam waveguides are studied and compared to those of single-beam irradiation, showing relevant differences. The creation of more symmetric stress patterns and a slight reduction of propagation losses are explained in terms of the fact that simultaneous inscription allows for a drastic reduction in the magnitude of "incubation" effects related to the existence of pre-damaged states.

Efficacy of percutaneous treatment of biliary tract calculi using the holmium:YAG laser.

PubMed

Hazey, J W; McCreary, M; Guy, G; Melvin, W S

2007-07-01

Few Western studies have focused on percutaneous techniques using percutaneous transhepatic choledochoscopy (PTHC) and holmium:yttrium-aluminum-garnet (YAG) laser to ablate biliary calculi in patients unable or unwilling to undergo endoscopic or surgical removal of the calculi. The authors report the efficacy of the holmium:YAG laser in clearing complex biliary calculi using percutaneous access techniques. This study retrospectively reviewed 13 non-Asian patients with complex secondary biliary calculi treated percutaneously using holmium:YAG laser. Percutaneous access was accomplished via left, right, or bilateral hepatic ducts and upsized for passage of a 7-Fr video choledochoscope. Lithotripsy was performed under choledochoscopic vision using a holmium:YAG laser with 200- or 365-microm fibers generating 0.6 to 1.0 joules at 8 to 15 Hz. Patients underwent treatment until stone clearance was confirmed by PTHC. Downsizing and subsequent removal of percutaneous catheters completed the treatment course. Seven men and six women with an average age of 69 years underwent treatment. All the patients had their biliary tract stones cleared successfully. Of the 13 patients, 3 were treated solely as outpatients. The average length of percutaneous access was 108 days. At this writing, one patient still has a catheter in place. The average number of holmium:YAG laser treatments required for stone clearance was 1.6, with no patients requiring more than 3 treatments. Of the 13 patients, 8 underwent a single holmium:YAG laser treatment to clear their calculi. Prior unsuccessful attempts at endoscopic removal of the calculi had been experienced by 7 of the 13 patients. Five patients underwent percutaneous access and subsequent stone removal as their sole therapy for biliary stones. Five patients were cleared of their calculi after percutaneous laser ablation of large stones and percutaneous basket retrieval of the remaining stone fragments. There was one complication of pain

FIBERTOM Nd:YAG laser in treatment of post-inflammatory structures of lower airways

NASA Astrophysics Data System (ADS)

Pirozynski, Michal; Polubiec-Kownacka, Malgorzata; Strojecki, Krzysztof; Blachnio, Antoni; Pawlak, Wieslaw; Krusiewicz, Jan

1996-03-01

Introduction of the first laser by Maiman in 1960 led to a rapid increase in the biological application of this device. The first application of laser energy in the treatment of airway pathology was by Strong et al. In 1981 Toty et al described the first use of a neodymium:yttrium-aluminum garnet (Nd:YAG) laser for resection of a bronchial tumor. Subglottic and tracheal stenosis have been treated endoscopically for many years with electrocautery, cryosurgery, by mechanical dilatation, and more recently since the mid 1970s with the carbon-dioxide laser. Early series demonstrated a moderate success rate in about 60% of the cases. Recently a new modification of the Nd:YAG laser was made available by Dornier (formerly MBB - Germany). The FIBERTOMTM is a unique method of controlling the temperature at the tip of the light guide allowing precise, direct contact cutting. Eleven patients (age 35.1 plus or minus 20.7 years) with post inflammatory airway stenoses were treated. Thirty-six procedures were carried out. An immediate dilatation of the narrowed airway was produced in 86%. Endoscopic control carried out 52 weeks after the initial procedure confirmed restoration of the airway lumen in 82%. Clinical improvement was seen in all.

Comparison of holmium:YAG and thulium fiber laser lithotripsy: ablation thresholds, ablation rates, and retropulsion effects.

PubMed

Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

2011-07-01

The holmium:YAG (Ho:YAG) laser lithotriptor is capable of operating at high pulse energies, but efficient operation is limited to low pulse rates (∼10 Hz) during lithotripsy. On the contrary, the thulium fiber laser (TFL) is limited to low pulse energies, but can operate efficiently at high pulse rates (up to 1000 Hz). This study compares stone ablation threshold, ablation rate, and retropulsion for the two different Ho:YAG and TFL operation modes. The TFL (λ = 1908 nm) was operated with pulse energies of 5 to 35 mJ, 500-μs pulse duration, and pulse rates of 10 to 400 Hz. The Ho:YAG laser (λ = 2120 nm) was operated with pulse energies of 30 to 550 mJ, 350-μs pulse duration, and a pulse rate of 10 Hz. Laser energy was delivered through 200- and 270-μm-core optical fibers in contact mode with human calcium oxalate monohydrate (COM) stones for ablation studies and plaster-of-Paris stone phantoms for retropulsion studies. The COM stone ablation threshold for Ho:YAG and TFL measured 82.6 and 20.8 J∕cm(2), respectively. Stone retropulsion with the Ho:YAG laser linearly increased with pulse energy. Retropulsion with TFL was minimal at pulse rates less than 150 Hz, then rapidly increased at higher pulse rates. For minimal stone retropulsion, Ho:YAG operation at pulse energies less than 175 mJ at 10 Hz and TFL operation at 35 mJ at 100 Hz is recommended, with both lasers producing comparable ablation rates. Further development of a TFL operating with both high pulse energies of 100 to 200 mJ and high pulse rates of 100 to 150 Hz may also provide an alternative to the Ho:YAG laser for higher ablation rates, when retropulsion is not a primary concern.

Nd:YAG laser combined with gold nanorods for potential application in port-wine stains: an in vivo study.

PubMed

Xing, Linzhuang; Chen, Bin; Li, Dong; Wu, Wenjuan; Wang, Guoxiang

2017-11-01

Neodymium:yttrium aluminum garnet (Nd:YAG) lasers exhibit considerable potential for treating deeply buried port-wine stains. However, the application of Nd:YAG laser is limited by its weak absorption to blood. This in vivo study tested the efficacy and safety of utilizing thiol-terminated methoxypolyethylene glycol-modified gold nanorods (PEG-GNRs) to enhance the absorption of Nd:YAG laser to blood. Mouse mesentery and dorsal skinfold chamber (DSC) model were prepared to analyze the thermal responses of a single venule without anatomic structures, as well as blood vessels in the complex structure of the skin, to laser light. After the injection of 0.44 mg of PEG-GNRs, the required threshold density of laser energy for blood coagulation and complete vasoconstriction decreased from 24 to 18  J/cm2 in the mesentery model and from 36 to 31  J/cm2 in the DSC model. The laser pulse required for blood coagulation and complete vasoconstriction decreased by 67.75% and 62.25% on average in the mesentery model and by 67.55% and 54.45% on average in the DSC model. Histological and histochemical results confirmed that PEG-GNRs are nontoxic in the entire mouse life span. Therefore, combining PEG-GNRs with Nd:YAG laser may be effective and safe for inducing an obvious thermal response of blood vessels under low energy density and minimal pulse conditions. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Long-term results in low-fluence 1064-nm Q-Switched Nd:YAG laser for melasma: Is it effective?

PubMed

Gokalp, Hilal; Akkaya, Ayse Deniz; Oram, Yasemin

2016-12-01

This study assessed the safety and clinical efficacy of a low-fluence 1064-nm Q-switched neodymium-doped:yttrium aluminum garnet (QS-Nd:YAG) laser in the treatment of patients with melasma. The study evaluated 34 melasma patients treated at a single institution using a 1064-nm QS-Nd:YAG laser. The laser parameters were 6 mm spot size and 2.5 J/cm 2 fluence with multiple passes for 6-10 (median 8) sessions at 2-week intervals. Outcomes were evaluated using photography, the modified Melasma Area and Severity Index (mMASI) score, and patient satisfaction interviews after the last treatment and 1 year after the last treatment. After the low-fluence 1064-nm QS-Nd:YAG laser treatments, the mean mMASI score decreased from 6.7 ± 3.3 to 3.2 ± 1.6 (P < 0.01). After treatment completion, 20 of 34 patients (58.8%) rated themselves as having at least a 50% reduction in melasma severity. One year after the last treatment, recurrence was observed in 20 patients (58.8%) and the mean mMASI score increased from 3.2 ± 1.6 to 5.8 ± 1.9 in all patients. The recurrence of low-fluence 1064-nm QS-Nd:YAG laser rates in melasma was high when the long-term results were considered. This result may be attributed to certain patient and treatment-related factors. © 2016 Wiley Periodicals, Inc.

Commentary: Is There Clinical Benefit From Using a Diode or Neodymium:Yttrium-Aluminum-Garnet Laser in the Treatment of Periodontitis?

PubMed

Cobb, Charles M

2016-10-01

Despite a quarter of a century of laser research, there is a persistent debate regarding the efficacy of dental lasers in the treatment of periodontitis or periodontal maintenance therapy. There are many claims and much hyperbole surrounding the use of lasers, either as a monotherapy or adjunctive to scaling and root planing, to treat periodontitis. There is little evidence that using a diode or neodymium:yttrium-aluminum-garnet laser adds clinical value over and above conventional non-surgical or surgical periodontal treatment. There is a significant need for better designed human clinical trials. Data from such trials should be analyzed according to initial probing depth and characteristics of the treated sites, such as non-molar, molar flat surfaces, and molar furcations, and evaluated for long-term post-treatment results.

Current role of lasers in the treatment of benign prostatic hyperplasia (BPH).

PubMed

Kuntz, Rainer M

2006-06-01

Evaluate the current role of lasers in the treatment of benign prostatic hyperplasia (BPH). The results of a MEDLINE search for randomised trials and case series of the last 5 yr and published review articles were analysed for the safety and efficacy of neodymium:yttrium aluminum garnet (Nd:YAG), potassium-titanyl-phosphate (KTP), and holmium (Ho):YAG laser prostatectomy. The analysis includes 12 reports on randomised clinical trials, 2 comparative studies, 10 review articles, and a total of >5000 patients. Laser treatment of BPH has evolved from coagulation to enucleation. Blood loss is significantly reduced compared with transurethral resection and open prostatectomy. Visual laser ablation of the prostate and interstitial laser coagulation cause coagulative necrosis with secondary ablation. Long postoperative catheterisation, unpredictable outcomes, and high reoperation rates have restricted the use of these techniques. Ablative/vaporising techniques have become popular again with the marketing of new high-powered 80-W KTP and 100-W Ho lasers. Vaporisation immediately removes obstructing tissue. Short-term results are promising, but large series, long-term results, and randomised trials are lacking. Holmium laser enucleation (HoLEP) allows whole lobes of the prostate to be removed, mimicking the action of the index finger in open prostatectomy. Prostates of all sizes can be operated on. It is at least as safe and effective as transurethral resection of the prostate and open prostatectomy, with significantly lower morbidity. It is the only laser procedure that provides a specimen for histologic evaluation. HoLEP appears to be a size-independent new "gold standard" in the surgical treatment of BPH.

"One-shot" CO2 versus Er:YAG laser stapedotomy: is the outcome the same?

PubMed

Marchese, Maria Raffaella; Scorpecci, Alessandro; Cianfrone, Francesca; Paludetti, Gaetano

2011-03-01

To assess and compare the functional results obtained by means of multiple-shot Erbium: yttrium-aluminum-garnet (Er:YAG) laser to those obtained using "one-shot" CO(2) laser stapedotomy in patients affected by otosclerosis. A retrospective case review was performed. Of the total number of 123 patients (114 ears) who underwent primary small-fenestra stapedotomy from January 2006 to September 2008, seven patients who received multiple-shot laser CO(2) stapedotomy were excluded from the study. The remaining 116 patients (104 ears) were sorted, and "one-shot" CO(2) laser stapedotomy (group A) was performed in 35/104 and Er:YAG laser stapedotomy (group B) in 69/104. After surgery, air conduction-pure tone average (AC-PTA) and air-bone gap (ABG) improved significantly in both groups, whereas sensorineural hearing loss (SNHL) and bone conduction (BC)-PTA did not change in both the groups. In group A, the postoperative ABG was significantly better (12.63 vs. 14.86 dB). Moreover, after "one-shot" stapedotomy, the AC-PTA significantly improved in all tested frequencies. On the contrary, in group B the AC-PTA improved significantly only in two frequencies (0.5 and 1 kHz). Consistent with previous reports, our findings confirm that laser stapedotomy is a safe and effective surgery, regardless of the technique. Based on our functional results, the "one-shot" CO(2) laser technique seems to be associated with a significantly better postoperative ABG if compared to Er:YAG laser stapedotomy.

Crystallography, Spectroscopic Analysis, and Lasing Properties of Nd(3+) :Y3Sc2Al3O12

DTIC Science & Technology

1989-12-01

aluminum garnet (GSAG), are formed from more stable constitu- ent oxides than gallium-containing materials, 2. Experimental Results and such as gadolinium ...the which an assessment can be made regarding aluminum -based systems, such as YAG, YSAG, Nd:YSAG as a laser material. or gadolinium scandium...Structure oxidation state variation or oxygen vacancies, and this problem is greatly reduced in alumi- Yttrium scandium aluminum garnet be- nate systems

Recycling stainless steel orthodontic brackets with Er:YAG laser - An environmental scanning electron microscope and shear bond strength study.

PubMed

Chacko, Prince K; Kodoth, Jithesh; John, Jacob; Kumar, Kishore

2013-07-01

TO DETERMINE THE EFFICIENCY OF ERBIUM: Yttrium aluminum garnet (Er:YAG) laser with Environmental Scanning Electron Microscope (ESEM) and shear bond strength analysis as a method of recycling stainless steel orthodontic brackets and compare with other methods of recycling. Eighty samples of extracted premolar teeth bonded to SS brackets were tested for rebonded shear bond strength after recycling by four methods and compared with a control group of 20 samples. These 80 samples were randomized into four groups which were recycled by four methods, namely, sandblasting, thermal method, adhesive grinding by tungsten carbide bur, and Er: YAG laser method. After recycling, ESEM and shear bond strength analysis were used to analyze the efficiency of the recycling methods. ER: YAG laser group was found to be having the greatest bond strength among the recycled brackets (8.33±2.51 followed by the sandblasting at 6.12±1.12 MPa, thermal and electropolishing at 4.44±0.95 MPa, and lastly the adhesive grinding method at 3.08±1.07 MPa. The shear bond strength of Er: YAG laser group was found to be having no statistically significant difference with that of the control group (P>0.05 and had statistical signifance with sandblasting, thermal and electropolishing and adhesive grinding groups at P>0.001. ESEM analysis showed complete removal of adhesive from the brackets recycled with Er: YAG laser which mimicked that of the control group. ER: YAG laser (2940 nm) was found to be the most efficient method for recycling, followed by the sandblasting, thermal, and the tungsten carbide methods, which had the least shear bond strength value and is not fit for clinical usage.

Sensitivity of magnetic properties to chemical pressure in lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li

NASA Astrophysics Data System (ADS)

Mukherjee, P.; Sackville Hamilton, A. C.; Glass, H. F. J.; Dutton, S. E.

2017-10-01

A systematic study of the structural and magnetic properties of three-dimensionally frustrated lanthanide garnets Ln 3 A 2 X 3O12, Ln  =  Gd, Tb, Dy, Ho, A  =  Ga, Sc, In, Te, X  =  Ga, Al, Li is presented. Garnets with Ln  =  Gd show magnetic behaviour consistent with isotropic Gd3+ spins; no magnetic ordering is observed for T  ⩾  0.4 K. Magnetic ordering features are seen for garnets with Ln  =  Tb, Dy, Ho in the temperature range 0.4  <  T  <  2.5 K, however the nature of the magnetic ordering varies for the different Ln as well as for different combinations of A and X. The magnetic behaviour can be explained by tuning of the magnetic interactions and changes in the single-ion anisotropy. The change in magnetic entropy is evaluated from isothermal magnetisation measurements to characterise the magnetocaloric effect in these materials. Among the Gd garnets, the maximum change in magnetic entropy per mole (15.45 J K-1 molGd-1 ) is observed for Gd3Sc2Ga3O12 at 2 K, in a field of 9 T. The performance of Dy3Ga5O12 as a magnetocaloric material surpasses the other garnets with Ln  =  Tb, Dy, Ho.

HO:LULF and HO:LULF Laser Materials

NASA Technical Reports Server (NTRS)

Barnes, Norman P. (Inventor); Morrison, Clyde A. (Inventor); Filer, Elizabeth D. (Inventor); Jani, Mahendra G. (Inventor); Murray, Keith E. (Inventor); Lockard, George E. (Inventor)

1998-01-01

A laser host material LULF (LuLiF4) is doped with holmium (Ho) and thulium (Tm) to produce a new laser material that is capable of laser light production in the vicinity of 2 microns. The material provides an advantage in efficiency over conventional Ho lasers because the LULF host material allows for decreased threshold and upconversion over such hosts as YAG and YLF. The addition of Tm allows for pumping by commonly available GaAlAs laser diodes. For use with flashlamp pumping, erbium (Er) may be added as an additional dopant. For further upconversion reduction, the Tm can be eliminated and the Ho can be directly pumped.

Investigation of the unidirectional spin heat conveyer effect in a 200 nm thin Yttrium Iron Garnet film

NASA Astrophysics Data System (ADS)

Wid, Olga; Bauer, Jan; Müller, Alexander; Breitenstein, Otwin; Parkin, Stuart S. P.; Schmidt, Georg

2016-06-01

We have investigated the unidirectional spin wave heat conveyer effect in sub-micron thick yttrium iron garnet (YIG) films using lock-in thermography (LIT). Although the effect is small in thin layers this technique allows us to observe asymmetric heat transport by magnons which leads to asymmetric temperature profiles differing by several mK on both sides of the exciting antenna, respectively. Comparison of Damon-Eshbach and backward volume modes shows that the unidirectional heat flow is indeed due to non-reciprocal spin-waves. Because of the finite linewidth, small asymmetries can still be observed when only the uniform mode of ferromagnetic resonance is excited. The latter is of extreme importance for example when measuring the inverse spin-Hall effect because the temperature differences can result in thermovoltages at the contacts. Because of the non-reciprocity these thermovoltages reverse their sign with a reversal of the magnetic field which is typically deemed the signature of the inverse spin-Hall voltage.

Effect of Er:YAG laser irradiation on bonding property of zirconia ceramics to resin cement.

PubMed

Lin, Yihua; Song, Xiaomeng; Chen, Yaming; Zhu, Qingping; Zhang, Wei

2013-12-01

This study aimed to investigate whether or not an erbium: yttrium-aluminum-garnet (Er:YAG) laser could improve the bonding property of zirconia ceramics to resin cement. Surface treatments can improve the bonding properties of dental ceramics. However, little is known about the effect of Er:YAG laser irradiated on zirconia ceramics. Specimens of zirconia ceramic pieces were made, and randomly divided into 11 groups according to surface treatments, including one control group (no treatment), one air abrasion group, and nine Er:YAG laser groups. The laser groups were subdivided by applying different energy intensities (100, 200, or 300 mJ) and irradiation times (5, 10, or 15 sec). After surface treatments, ceramic pieces had their surface morphology observed, and their surface roughness was measured. All specimens were bonded to resin cement. Shear bond strength was measured after the bonded specimens were stored in water for 24 h, and additionally aged by thermocycling. Statistical analyses were performed using one way analysis of variance (ANOVA) and Tukey's test for shear bond strength, and Dunnett's t test for surface roughness, with α=0.05. Er:YAG laser irradiation changed the morphological characteristics of zirconia ceramics. Higher energy intensities (200, 300 mJ) could roughen the ceramics, but also caused surface cracks. There were no significant differences in the bond strength between the control group and the laser groups treated with different energy intensities or irradiation times. Air abrasion with alumina particles induced highest surface roughness and shear bond strength. Er:YAG laser irradiation cannot improve the bonding property of zirconia ceramics to resin cement. Enhancing irradiation intensities and extending irradiation time have no benefit on the bond of the ceramics, and might cause material defect.

Forward volume and surface magnetostatic modes in an yttrium iron garnet film for out-of-plane magnetic fields: Theory and experiment

NASA Astrophysics Data System (ADS)

Lim, Jinho; Bang, Wonbae; Trossman, Jonathan; Amanov, Dovran; Ketterson, John B.

2018-05-01

We present experimental and theoretical results on the propagation of magnetostatic spin waves in a film of yttrium iron garnet (YIG) for out-of-plane magnetic fields for which propagation in opposite directions is nonreciprocal in the presence of a metal layer. The plane studied is defined by the film normal n and n × k where k is the wave vector of the mode. Spin waves in this setting are classified as forward volume waves or surface waves and display non-reciprocity in the presence of an adjacent metal layer except for when H//n. The measurements are carried out in a transmission geometry, and a microwave mixer is used to measure the change of phase, and with it the evolution of wavevector, of the arriving spin wave with external magnetic field.

Clinical evaluation of LAUP with Ho:YAG laser and CO2 laser for 420 cases of obstructive sleep apnea syndrome

NASA Astrophysics Data System (ADS)

Qi, Xing-Guo; Xie, Xiang; Yan, Rui-Hong; Xue, Peng

1998-11-01

A total of 420 cases of OSAS patients underwent laser- assisted uvlopalatoplasty (LAUP) with CO2 and Ho:YAG laser, the follow-up period range 1-12 months in 360 cases. According to our overall response rate, total improvements in 60 percent of patients, significant improvement in 100 percent of patients. Except minor bleeding, no serious complications were observed, so LAUP should be considered as an alternative to UPPP.

Laser treatment of cutaneous angiokeratomas: A systematic review.

PubMed

Nguyen, Jannett; Chapman, Lance W; Korta, Dorota Z; Zachary, Christopher B

2017-11-01

Angiokeratomas can present therapeutic challenges, especially in cases of extensive lesions, where traditional surgical methods carry high risks of scarring and hemorrhage. Argon, pulsed dye (PDL), neodymium-doped yttrium aluminum garnet (Nd:YAG), copper vapor, potassium titanyl phosphate, carbon dioxide, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers have emerged as alternative options. To review the use and efficacy of lasers in treating angiokeratomas. A PubMed search identified randomized clinical trials, cohort studies, case series, and case reports involving laser treatment of cutaneous angiokeratomas. Twenty-five studies were included. Quality ratings were assigned using the Oxford Centre for Evidence-Based Medicine scheme. Several laser modalities are effective in treating multiple variants of angiokeratomas. Vascular lasers like PDL, Nd:YAG, and argon are the most studied and of these, PDL offers the safest side effect profile. Nd:YAG may be more effective for hyperkeratotic angiokeratomas. Combination treatment with multiple laser modalities has also demonstrated some success. Lasers are a promising treatment option for angiokeratomas, but current use is limited by the lack of treatment guidelines. There are limited high quality studies comparing laser treatments to each other and to non-laser options. Additional studies are needed to establish guidelines and to optimize laser parameters. © 2017 Wiley Periodicals, Inc.

Effect of Various Laser Wavelengths on Temperature Changes During Periimplantitis Treatment: An in vitro Study.

PubMed

Monzavi, Abbas; Fekrazad, Reza; Chinipardaz, Zahra; Shahabi, Sima; Behruzi, Roohollah; Chiniforush, Nasim

2018-06-01

This study aimed to investigate and compare temperature change during implant decontamination with different laser types (carbon dioxide [Co2]/diode/neodymium-doped yttrium aluminum garnet [Nd:YAG]/erbium-doped yttrium aluminum garnet [Er:YAG]/antimicrobial photodynamic therapy [aPDT]). Sixty implants were inserted into a bone block cut from a sheep's mandible. A 3 × 8 mm vertical lesion was made at the buccal of each implant. The bone block was placed into a 37°C water bath to simulate the in vivo oral condition. A K-type thermocouple was placed in contact with the implant to register temperature changes at 3 points (apical/middle/coronal). In the entire laser irradiations, the mean of temperature changes remains below 10°C. The apical temperature rise was higher than the coronal and middle regions (P < 0.05), and the apical temperature took longer time to reach the initial temperature (37°C) (P < 0.001). Temperature changes over 10°C occurred at the apical point of the implants with the Co2, Nd:YAG, and diode laser irradiations; however, only the Co2 laser reached the statistical significance in this regard (P < 0.05). Our findings indicate the promising results of Er:YAG laser and aPDT in implant decontamination. Precaution should be taken in the application of Nd:YAG, diode, and especially Co2 lasers.

Structure-substitution limit correlation study on Cr{sup 3+} substituted polycrystalline yttrium iron garnet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modi, K. B.; Saija, K. G.; Sharma, P. U.

2016-05-06

Polycrystalline samples of Cr{sup 3+} - substituted yttrium iron garnet (Y{sub 3}Fe{sub 5}O{sub 12}) system with general chemical formula, Y{sub 3}Fe{sub 5-x}Cr{sub x}O{sub 12}, x = 0.0, 0.2, 0.4 and 0.6 were synthesized by double sintering ceramic technique and characterized by X-ray powder diffractometry. The Rietveld fitted X-ray diffraction patterns analysis revealed mono phase formation for x = 0.0 - 0.4 compositions while x = 0.6 composition possesses mixed phase character. The observed substitution limit has been discussed in the light of ionic size of substituent, electrostatic energy, electronic configuration and synthesis parameters. These observations strongly suggest that the electronicmore » configuration of Cr{sup 3+}, which is favorable to the formation of d2sp3 (octahedral) type bonds, must be important. In the case of Cr{sup 3+}, the substitution does not appear to proceed well for x much greater than 0.5, this limitation probably is a consequence of the strong preference of a smaller ion Cr{sup 3+}, for a larger octahedral site which quickly leads to a condition not comparable with the requirement of the structure. The distribution of cations, mean ionic radii and theoretical lattice constant values have been determined.« less

Low-cost Engineering of Laser Rods and Slabs with Liquid Phase Epitaxy

DTIC Science & Technology

2011-09-01

SUPPLEMENTARY NOTES 14. ABSTRACT We investigated the use of a liquid phase epitaxial ( LPE ) coating to improve the performance of a rod or slab laser. A...single crystal erbium-doped yttrium aluminum garnet (Er:YAG) rod coated with undoped YAG, and an uncoated sample were procured, then compared on the...the whispering gallery modes, which otherwise would deplete the gain in ~50% of the rod volume. We also investigated LPE growth on a ceramic sample

Yttrium Iron Garnet Thin Films with Very Low Damping Obtained by Recrystallization of Amorphous Material

PubMed Central

Hauser, Christoph; Richter, Tim; Homonnay, Nico; Eisenschmidt, Christian; Qaid, Mohammad; Deniz, Hakan; Hesse, Dietrich; Sawicki, Maciej; Ebbinghaus, Stefan G.; Schmidt, Georg

2016-01-01

We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG) by annealing in oxygen atmosphere. Our findings show that well below the melting temperature the material transforms into a fully epitaxial layer with exceptional quality, both structural and magnetic. In ferromagnetic resonance (FMR) ultra low damping and extremely narrow linewidth can be observed. For a 56 nm thick layer a damping constant of α = (6.15 ± 1.50) · 10−5 is found and the linewidth at 9.6 GHz is as small as 1.30 ± 0.05 Oe which are the lowest values for PLD grown thin films reported so far. Even for a 20 nm thick layer a damping constant of α = (7.35 ± 1.40) · 10−5 is found which is the lowest value for ultrathin films published so far. The FMR linewidth in this case is 3.49 ± 0.10 Oe at 9.6 GHz. Our results not only present a method of depositing thin film YIG of unprecedented quality but also open up new options for the fabrication of thin film complex oxides or even other crystalline materials. PMID:26860816

Observation of electromagnetically induced transparency and absorption in Yttrium Iron Garnet loaded split ring resonator

NASA Astrophysics Data System (ADS)

Tay, Z. J.; Soh, W. T.; Ong, C. K.

2018-04-01

In this paper, we propose a new method of controlling microwave transmission from Electromagnetically Induced Absorption (EIA) to Electromagnetically Induced Transparency (EIT). EIA describes the state where the system strongly absorbs microwaves, whereas EIT describes the state in which the system is transparent to microwaves. Control is achieved via coupling of the 3 GHz photon mode of a metamaterial Split Ring Resonator (SRR) to the spin wave magnon modes of a Yttrium Iron Garnet (YIG) bulk. The system is described by a 2-body interaction matrix with an additional fitting parameter τ which takes into account the fact that the microstrip feed line could excite the SRR as well as the YIG. The parameter τ reveals the effect of geometry and shielding on the coupling behaviour and gives rise to unique physics. In low τ (τ ⩽ 2) configurations, only EIT is reported. However, in high τ (τ ≈ 10) configurations, EIA is reported. Furthermore, we report that the system can be easily changed from a low τ to high τ configuration by shielding the SRR from the microstrip with a thin metal piece. Varying the τ parameter through shielding is thus proposed as a new method of controlling the microwave transmission at the coupling region.

Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

NASA Astrophysics Data System (ADS)

Maendl, Stefan; Grundler, Dirk

2018-05-01

We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

A case report of progressive obstruction of Ex-PRESS miniature glaucoma shunt after transient flat anterior chamber and treatment using Nd:YAG laser.

PubMed

Tanito, Masaki; Sano, Ichiya; Ohira, Akihiro

2015-01-08

We report a case of Ex-PRESS miniature glaucoma shunt obstruction resulting from progressive iris synechial formation after transient anterior chamber shallowing. A 68-year-old woman with pseudoexfoliation glaucoma in her right eye underwent filtration surgery with implantation of the Ex-PPESS shunt (model P-50, Alcon Japan, Tokyo, Japan) in combination with intra-surgical 0.04% mitomycin C use. After the anterior chamber injection of viscoelastic material and 100% sulfur hexafluoride gas for treatment of early postoperative over filtration, the intraocular pressure (IOP) was controlled between 9 and 12 mmHg. On postoperative day 121, gonioscopy showed that synechial formation around the shunt obstructed the axial port leaving the relief port opened. On postoperative day 274, the intraocular pressure increased to 40 mmHg and synechiae obstructed both the axial and relief ports. Dispersion of iris tissue by neodymium:yttrium-aluminium-garnet (Nd:YAG) laser (2 mJ, one shot to each port) opened both ports and immediately lowered the IOP, leaving peripheral anterior synechiae around the shunt. Up to postoperative day 400, the IOP was controlled between 13 and 15 mmHg, and the cystic bleb was maintained. The synechiae formed gradually extends around the shunt's shaft and can result in later external obstruction of the relief port. The current case requires further follow-up since synechiae remaining around the shaft can cause future obstruction. We emphasize the fact that, if the iris synechiae to the shunt once formed, it can progress and obstruct the shunt ports later.

Demonstration of Clean Particle Seeding for Particle Image Velocimetry in a Closed Circuit Supersonic Wind Tunnel

DTIC Science & Technology

2007-03-01

plane in space. Many such lasers are used for PIV, including: Copper vapor, Argon ion, Helium-Neon, Yttrium Aluminum Garnet (YAG) and Neodymium doped ...velocimetry to measure the velocities of nanoparticles in nanofluids .” Optics Express. Vol 14, No 17: 7559-7566 (2006) 15. Poggie, J., Erbland, P.J., Smits

Computational discovery of lanthanide doped and Co-doped Y{sub 3}Al{sub 5}O{sub 12} for optoelectronic applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhary, Kamal; Chernatynskiy, Aleksandr; Phillpot, Simon R.

2015-09-14

We systematically elucidate the optoelectronic properties of rare-earth doped and Ce co-doped yttrium aluminum garnet (YAG) using hybrid exchange-correlation functional based density functional theory. The predicted optical transitions agree with the experimental observations for single doped Ce:YAG, Pr:YAG, and co-doped Er,Ce:YAG. We find that co-doping of Ce-doped YAG with any lanthanide except Eu and Lu lowers the transition energies; we attribute this behavior to the lanthanide-induced change in bonding environment of the dopant atoms. Furthermore, we find infrared transitions only in case of the Er, Tb, and Tm co-doped Ce:YAG and suggest Tm,Ce:YAG and Tb,Ce:YAG as possible functional materials formore » efficient spectral up-conversion devices.« less

Laser lipolysis with pulsed 1064 nm Nd:YAG laser for the treatment of gynecomastia.

PubMed

Rho, Yong Kwan; Kim, Beom Joon; Kim, Myeung Nam; Kang, Kweon Soo; Han, Hee Jin

2009-12-01

Lipolysis using laser is currently widely used for reducing localized fat. A 1064 nm neodynium-doped yttrium aluminum garnet (Nd:YAG) laser lipolysis was investigated in this study to evaluate its efficacy and safety in the treatment of gynecomastia. Five male patients diagnosed with gynecomastia were enrolled in this study, which was designed as a controlled split-breast trial. One breast of each patient was subjected to laser lipolysis and was then compared with a contralateral breast. Photographs and clinical assessments were obtained before the lipolysis, and at the fourth and eighth weeks thereafter. Computed tomography (CT) scan and ultrasound (US) imaging were used to evaluate the changes in the breasts' thicknesses. The mean chest circumference was found to have been significantly reduced 8 weeks after the laser lipolysis. The clinical outcomes of the laser lipolysis were considered favorable by both the patients and clinicians. The CT and US scans showed that the thicknesses of the treated right breasts reduced more than those of the left breasts were 8 weeks after the laser lipolysis. The side effects (pain, edema, and ecchymosis) were minimal and disappeared shortly after they first manifested. Limitations The limitations of this study are that it employed small treatment groups and short-term follow-up. This study demonstrated that gynecomastia can be treated effectively and safely through 1064 nm Nd:YAG laser lipolysis.

The effect of yttrium and thorium on the oxidation behavior of Ni-Cr-Al alloys

NASA Technical Reports Server (NTRS)

Kumar, A.; Nasrallah, M.; Douglass, D. L.

1974-01-01

The effect of quaternary additions of 0.5% Y, 0.5 and 1.0% Th to a base alloy of Ni-10CR-5Al on the oxidation behavior and mechanism was studied during oxidation in air over the range of 1000 to 1200 C. The presence of yttrium decreased the oxidation kinetics slightly, whereas, the addition of thorium caused a slight increase. Oxide scale adherence was markedly improved by the addition of the quaternary elements. Although a number of oxides formed on yttrium containing alloys, quantitative X-ray diffraction clearly showed that the rate-controlling step was the diffusion of aluminum through short circuit paths in a thin layer of alumina that formed parabolically with time. Although the scale adherence of the yttrium containing alloy was considerably better than the base alloys, spalling did occur that was attributed to the formation of the voluminous YAG particles which grew in a mushroom-like manner, lifting the protective scale off the subrate locally. The YAG particles formed primarily at grain boundaries in the substrate in which the yttrium originally existed as YNi9.

Formation of hierarchical macro porous YAlO:Ce multifunctional nanophosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayanthi Rajan, K., E-mail: k.jayanthirajan@gmail.com, E-mail: manorama@iict.res.in; Manorama, Sunkara V., E-mail: k.jayanthirajan@gmail.com, E-mail: manorama@iict.res.in

2016-03-21

Hierarchically macro-porous lumino-magnetic yttrium aluminium oxide (YAlO:- YAT: tetragonal; YAG: garnet; YAM: monoclinic) ceramic nanophosphors doped with trivalent cerium (Ce) ions have been synthesized by a novel and versatile self assembly route without the need of any external templates. X-ray diffraction and X-ray photoelectron spectroscopy studies confirm the presence of dopant and its valence state. Room temperature ferromagnetism in undoped and YAlO:Ce suggest an intrinsic nature of ferromagnetism dependent on host lattice imperfection along with yellow photoluminescence emission explicitly arising due to Ce doping established the non-interfering character of the two phenomena. Such a porous morphology has the potential ofmore » the biocarriers and could be engineered to make it suitable for spintronic applications by incorporation of dielectric into the pores and in conjunction with blue light emitting devices which could be used to obtain white light.« less

Spin Seebeck effect and ballistic transport of quasi-acoustic magnons in room-temperature yttrium iron garnet films

NASA Astrophysics Data System (ADS)

Noack, Timo B.; Musiienko-Shmarova, Halyna Yu; Langner, Thomas; Heussner, Frank; Lauer, Viktor; Heinz, Björn; Bozhko, Dmytro A.; Vasyuchka, Vitaliy I.; Pomyalov, Anna; L’vov, Victor S.; Hillebrands, Burkard; Serga, Alexander A.

2018-06-01

We studied the transient behavior of the spin current generated by the longitudinal spin Seebeck effect (LSSE) in a set of platinum-coated yttrium iron garnet (YIG) films of different thicknesses. The LSSE was induced by means of pulsed microwave heating of the Pt layer and the spin currents were measured electrically using the inverse spin Hall effect in the same layer. We demonstrate that the time evolution of the LSSE is determined by the evolution of the thermal gradient triggering the flux of thermal magnons in the vicinity of the YIG/Pt interface. These magnons move ballistically within the YIG film with a constant group velocity, while their number decays exponentially within an effective propagation length. The ballistic flight of the magnons with energies above 20 K is a result of their almost linear dispersion law, similar to that of acoustic phonons. By fitting the time-dependent LSSE signal for different film thicknesses varying by almost an order of magnitude, we found that the effective propagation length is practically independent of the YIG film thickness. We consider this fact as strong support of a ballistic transport scenario—the ballistic propagation of quasi-acoustic magnons in room temperature YIG.

Nd:YAG laser associated to different materials on seal of dentinal tubuli for dowel and post preparation

NASA Astrophysics Data System (ADS)

Aun, Carlos E.; de Campos Ferraz, Jussara; Silva Kfouri, Luciana

1998-04-01

Previous researches have discussed the importance of sealing the internal surface of the root canal after preparing it for posts or dowels, avoiding tubuli contamination by the oral environment. The purpose of this study was to investigate the effects of Neodymium-Yttrium-Aluminum-Garnet laser irradiation, associated or not with another materials, on the root inner walls after post space preparation. Forty single rooted endodontically treated teeth had theirs filings partially removed for prosthetics restoration, divided into 8 groups which received a coat of the following materials: group A: Copalite vanish; group B: Copalite vanish and laser; group C: Scothbond Multi-Purpose; group D: Scothbond Multi-Purpose and laser; group E: methylcianoacrilate; group F: methylcianocrilate and laser; group G: laser only; group H: control. The roots were placed in methylene blue dye and transversally cutted, then submitted to the analysis in the profile projector. So far we could observe that the Nd:Yag laser was able to enhance the sealing properties of the Scothbond Multi-Purpose.

Vapor emissions resulting from Nd:YAG laser interaction with tooth structure.

PubMed

Gelskey, S C; White, J M; Gelskey, D E; Kremers, W

1998-11-01

The Neodymium:yttrium aluminum garnet (Nd:YAG) dental laser has been cleared by the United States Food and Drug Administration (FDA) for marketing in intraoral soft tissue treatment. The efficacy and safety of the Nd:YAG laser in the treatment of hard dental tissue as well as the effects of dental irradiation on the pulp and periodontium have been investigated. Odors resulting from laser irradiation have been reported, but the nature and toxicity of associated decomposition vapors is unknown and the health consequences of their inhalation have not yet been studied. The purpose of this in vitro study was to identify vapors emitted during interaction of the Nd:YAG laser with carious human enamel and dentin and sound enamel and dentin coated with organic ink. Vapor emissions were collected from prepared sections of extracted human teeth receiving laser irradiation of 100 mJ and 10 Hz for a duration of 1, 10, or 60 s. Emissions were collected by means of charcoal absorption tubes, and subsequently analyzed using a Gas Chromatograph equipped with Mass Selective (GC/MS) and Flame Ionization Detectors to identify the chemical constituents of the vapors. No compounds were identified in Nd:YAG laser-treated caries, enamel and dentin. No volatile vapors were identified from samples of tooth materials exposed to the laser for 1 or 10 s. Camphor was positively identified in the test sample which consisted of India ink-coated dentin and the reference sample of India ink-coated glass beads, both exposed to the laser for 60 s. 2,5-norbornadiene was tentatively identified in these samples. The Threshold Limit Value (TLV) of camphor is 2 ppm with a Lethal Dose Level (LDLo) of 50 mg/kg (human oral), while the TLV and LDLo of 2,5-norbornadiene is unknown. Occupational and public health safety measures are discussed in this article. Further research is needed to quantify the compounds produced and to determine their toxicity to patients and to dental care providers.

Morphological alterations of periodontal pocket epithelium following Nd:YAG laser irradiation.

PubMed

Ting, Chun-Chan; Fukuda, Mitsuo; Watanabe, Tomohisa; Sanaoka, Atsushi; Mitani, Akio; Noguchi, Toshihide

2014-12-01

The purpose of this in vivo study was to examine morphologic alterations in the periodontal pocket epithelium with presence or absence of clinical inflammation following the use of the Neodymium: Yttrium-Aluminum-Garnet (Nd:YAG) laser irradiation. Subgingival Nd:YAG laser irradiation has been proposed as an alternative technique for treatment of chronic periodontitis. Several published studies have reported the clinical outcomes of such treatment. Twenty patients, diagnosed with moderate chronic periodontitis, were selected for the study. A total of 32 sites was identified and divided into a control (n=18) and laser-treated test groups (n=14). Probing depth (PD) and bleeding on probing (BOP) were recorded for all sites. Test sites were irradiated with an Nd:YAG laser using parameters of 2 W, 200 mJ pulse energy, and 10 pps delivered through a 320 μm diameter tip. Total laser treatment time ranged from 1 to 2 min. Following treatment, all specimens were harvested via biopsy and processed for scanning electron microscopy (SEM) and histologic examination. Control group specimens, depending upon initial PD, exhibited either a relatively smooth and intact epithelium with little desquamation (PD≤3 mm), or increasing degrees of epithelial desquamation and leukocytic infiltration at a PD of ≥4 mm. In the laser-treated test group, the specimens with PD≤3 mm that were BOP negative (-) exhibited a thin layer of epithelium that was disrupted. In the specimens with initial PD of ≥4 mm, complete removal of the epithelium whose extent and degree were increasing, was observed in the inflamed portion, while epithelium remained in the uninflamed portion. The SEM and histologic findings demonstrated the feasibility of ablating pocket epithelium with an Nd:YAG laser irradiation using parameters of 2 W of power (200 mJ, 10 pps). Furthermore, the presence or absence of clinical inflammation appeared to have an impact on the degree of laser

Further characterization of photothermal breakdown products of uric acid stones following holmium:YAG laser lithotripsy

NASA Astrophysics Data System (ADS)

Glickman, Randolph D.; Weintraub, Susan T.; Kumar, Neeru; Corbin, Nicole S.; Lesani, Omid; Teichman, Joel M. H.

2000-06-01

Previously we found that Ho:YAG laser (2120 nm) lithotripsy of uric acid stones produced cyanide, a known thermal breakdown product of uric acid. We now report that alloxan, another thermal breakdown product, is also likely produced. Uric acid stones (approximately 98% pure) of human origin were placed in distilled water and subjected to one of the following experimental treatments: unexposed control, exposed to Ho:YAG laser, Nd:YAG laser, or mechanically crushed. Samples were then processed for HPLC analysis with UV detection. Peaks were identified by comparison to authentic standards. All samples contained uric acid, with retention time (RT) about 6 min. All of the laser-exposed samples contained a peak that eluted at 2.5 min, identical to the RT of authentic alloxan. Ho:YAG laser irradiation, however, produced a larger presumed alloxan peak than did the Nd:YAG laser. The peak at 2.5 min, as well as unidentified later-eluting peaks, were present in the laser-exposed, but not the unexposed or mechanically crushed, samples. These results confirm the thermal nature of lithotripsy performed with long-pulse IR lasers.

Induction of melasma by 1064-nm Q-switched neodymium:yttrium-aluminum-garnet laser therapy for acquired bilateral nevus of Ota-like macules (Hori nevus): A study on related factors in the Chinese population.

PubMed

Wang, Ben; Xie, Hong-Fu; Tan, Jun; Xie, Hong-Ju; Xu, Lin-Yong; Ding, Rong; Liu, Fang-Fen; Chen, Xiang; Jian, Dan; Li, Ji

2016-06-01

Laser treatment has emerged as a common treatment modality for acquired bilateral nevus of Ota-like macules (ABNOM). To identify the ratio of melasma induction and exacerbation before and after laser therapy for ABNOM and to observe the risk factors related to the induction and exacerbation of melasma by laser therapy, we analyzed related factors of 1268 adult Chinese patients who underwent 1064-nm Q-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (QNYL) treatment using case series and case-control studies. Overall, 24.0% of the ABNOM patients had mixed melasma. Among the ABNOM patients without melasma, after laser therapy the development of melasma was more frequently noted in patients older than 35 years (P < 0.0001), as well in patients whose ABNOM was less than 10 cm(2) (P = 0.027), ABNOM were light (similar to yellow-brown) in color (P = 0.021) and skin types were closer to type IV (P < 0.0001). New melasma lesions also appeared most frequently in the zygomatic region (P < 0.0001). Among the ABNOM patients with melasma, 89.5% experienced worsening of their melasma, irrespective of their related factors above. We concluded that the risk of inducing melasma is great after 1064-nm QNYL treatment in ABNOM patients, and particularly in the patients with both ABNOM and melasma. ABNOM patients should be treated as early as possible and before the age of 35 years. © 2016 Japanese Dermatological Association.

Nonlocal magnon spin transport in yttrium iron garnet with tantalum and platinum spin injection/detection electrodes

NASA Astrophysics Data System (ADS)

Liu, J.; Cornelissen, L. J.; Shan, J.; van Wees, B. J.; Kuschel, T.

2018-06-01

We study the magnon spin transport in the magnetic insulator yttrium iron garnet (YIG) in a nonlocal experiment and compare the magnon spin excitation and detection for the heavy metal paramagnetic electrodes platinum (Pt|YIG|Pt) and tantalum (Ta|YIG|Ta). The electrical injection and detection processes rely on the (inverse) spin Hall effect in the heavy metals and the conversion between the electron spin and magnon spin at the heavy metal|YIG interface. Pt and Ta possess opposite signs of the spin Hall angle. Furthermore, their heterostructures with YIG have different interface properties, i.e. spin mixing conductances. By varying the distance between injector and detector, the magnon spin transport is studied. Using a circuit model based on the diffusion-relaxation transport theory, a similar magnon relaxation length of  ∼10 μm was extracted from both Pt and Ta devices. By changing the injector and detector material from Pt to Ta, the influence of interface properties on the magnon spin transport has been observed. For Ta devices on YIG the spin mixing conductance is reduced compared with Pt devices, which is quantitatively consistent when comparing the dependence of the nonlocal signal on the injector-detector distance with the prediction from the circuit model.

Investigation of irradiation by different nonablative lasers on primary cultured skin fibroblasts.

PubMed

Weng, Y; Dang, Y; Ye, X; Liu, N; Zhang, Z; Ren, Q

2011-08-01

A variety of lasers with different wavelengths and biological effects are widely used for nonablative skin rejuvenation, but the underlying mechanisms have not been fully investigated. To investigate the effects of irradiation by different nonablative lasers on collagen synthesis and the antioxidant status of cultured fibroblasts to identify a possible mechanism for laser photorejuvenation. Cultured skin fibroblasts were irradiated with three different lasers: 532 nm potassium-titanyl phosphate (KTP), 1064 nm Q-switched neodymium:yttrium-aluminium-garnet (Nd:Yag) and 1064 nm long-pulse Nd:YAG, and production of collagen and changes in lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were assayed. Irradiation by all three lasers led to a marked increase in collagen production. Two major antioxidant enzymes, SOD and GSH, were significantly increased, whereas MDA was markedly reduced after laser irradiation. No change in LDH activity was found between nonirradiated and irradiated fibroblasts. This study indicates that the increased collagen synthesis by fibroblasts after laser treatment may be partly due to improved antioxidant capacity, which reduces oxidative stress and thus stimulates new collagen production. © The Author(s). CED © 2011 British Association of Dermatologists.

Long-term changes in subfoveal choroidal thickness and central macula thickness after Nd:YAG laser capsulotomy.

PubMed

Yilmaz, Tolga; Yilmaz, Ahu

2017-08-01

To evaluate changes in central macula thickness (CMT), subfoveal choroid thickness (SCT), and intraocular pressure (IOP) before and after neodymium:yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy. 42 eyes of 42 patients who underwent Nd:YAG laser capsulotomy were included in this prospective study. CMT, SCT, and IOP were evaluated preoperatively and at postoperative week 1 and postoperative months 1, 3, 6, and 12. CMT was 238.1 ± 27.6 μm (mean ± SD) preoperatively, then 239.7 ± 29.8, 241.3 ± 28.7, 242.7 ± 27.2, 238.8 ± 23.7, and 238.3 ± 21.7 μm at postoperative week 1 and months 1, 3, 6, and 12, respectively. SCT was 263.3 ± 21.6 μm preoperatively, and 265.5 ± 24.8, 266.2 ± 25.7, 267.1 ± 26.3, 269.1 ± 24.2, and 269.9 ± 21.4 μm at postoperative week 1 and months 1, 3, 6, and 12, respectively. There were no significant differences between preoperative and postoperative results for CMT, SCT, or IOP (all p > 0.05). Although there were slight changes in choroid thickness in the long term, treatment of posterior capsule opacification with a low-energy Nd:YAG laser is a safe procedure that increases visual acuity without creating a significant increase in IOP, CMT, and SCT.

Effect of Nd:YAG Laser Irradiation on the Number of Open Dentinal Tubules and Their Diameter with and without Smear of Graphite: An in Vitro Study

PubMed Central

Maleki-pour, Mohammad Reza; Birang, Reza; Khoshayand, Maryam; Naghsh, Narges

2015-01-01

Introduction: Dentin hypersensitivity (DH) is characterized by tooth pain arising from exposure of dental roots. In this study the efficiency of neodymium yttrium-aluminum-garnet (Nd:YAG) laser in association with graphite on dentinal surface changes as the alternative to the treatment of DH was evaluated. Methods: Sixteen noncarious human third molars were collected and sectioned into 5 parts from cementoenamel junction (CEJ) to the furcation area. The prepared samples were randomly assigned into five groups (Gs) of each 16: Control (G1), treated by Nd:YAG laser at 0.5 W (G2), irradiation of Nd:YAG with a 0.25 W output power(G3), smeared with graphite and then using Nd:YAG laser at output powers of 0.5 W (G4) and 0.25 W (G5). For all groups the parameters were 15 Hz, 60 s, at two stages and with a right angle irradiation. The number and diameter of dentinal tubules (DT) were compared and analyzed by SPSS software, One way ANOVA and Post hoc LSD tests. Results:The number of open dentinal tubules varied significantly between all groups except among G1 with G3 and G2 with G5. Multiple comparison tests also exhibited significant differences regarding the diameter of tubules between the groups two by two except among G2 with G5. Conclusion: Nd:YAG laser used at 0.25 W and 0.5 W with application of graphite smear was able to reduce the number and diameter of dentinal tubules. PMID:25699166

High Energy Solid State and Free Electron Laser Systems in Tactical Aviation

DTIC Science & Technology

2005-06-01

specifically neodymium and ytterbium doped yttrium aluminum garnet (Nd:YAG and Yb:YAG) have been shown to produce pump absorption efficiencies (i.e...Search Radar Dish Aluminum Alloy 2.71 10.0 0.91 321 932 300 22.1 SAM nosecone Ceramic* 3.0 1.0 0.9 1600 3300 250 12.1 T-72 Tank Armor Steel...development at Lawrence Livermore National Laboratory, is the solid-state heat capacity laser, which is an array of diode- pumped neodymium-doped gadolinium

Measurements of long-wavelength spin waves for the magnetic field in the Damon-Eshbach, backward-volume and forward-volume geometries of an yttrium iron garnet film

DOE PAGES

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan; ...

2018-03-23

In this paper, we report systematic measurements of the dispersion of long wavelength spin waves for a wide range of wave vectors for the magnetic field along the three principal directions defining the forward volume, backward volume and Damon-Eshbach modes of a 9.72 μm thick film of an yttrium iron garnet obtained using lithographically patterned, multi-element, spatially resonant, antennas. Overall good agreement is found between the experimental data for the backward volume and Damon-Eshbach modes and the magnetostatic theory of Damon and Eshbach. Also, good agreement is found between the experimental data for the forward volume mode and the theorymore » of Damon and van de Vaart.« less

Measurements of long-wavelength spin waves for the magnetic field in the Damon-Eshbach, backward-volume and forward-volume geometries of an yttrium iron garnet film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bang, Wonbae; Lim, Jinho; Trossman, Jonathan

In this paper, we report systematic measurements of the dispersion of long wavelength spin waves for a wide range of wave vectors for the magnetic field along the three principal directions defining the forward volume, backward volume and Damon-Eshbach modes of a 9.72 μm thick film of an yttrium iron garnet obtained using lithographically patterned, multi-element, spatially resonant, antennas. Overall good agreement is found between the experimental data for the backward volume and Damon-Eshbach modes and the magnetostatic theory of Damon and Eshbach. Also, good agreement is found between the experimental data for the forward volume mode and the theorymore » of Damon and van de Vaart.« less

Evaluation of Nd:YAG laser on partial oxygen saturation of pulpal blood in anterior hypersensitive teeth.

PubMed

Birang, Reza; Kaviani, Naser; Mohammadpour, Mehdi; Abed, Ahmad Moghareh; Gutknecht, Norbert; Mir, Maziar

2008-07-01

Dentine hypersensitivity has of long been known to be a common clinical problem in dental practices. Lasers have recently come to play a prominent role in the treatment of this disorder. They might, however, cause dental pulp damage. This study was conducted to evaluate the effect of Nd:yttrium-aluminum-garnet (YAG) laser on partial oxygen saturation of pulpal blood in sensitive anterior teeth. In this clinical trial, 65 hypersensitive teeth were selected and randomly allocated to two groups. The study group involved Nd:YAG laser treatment, while no treatment was employed for the control group. Using a pulse oximetry system, evaluations were preformed of the partial oxygen saturation in the pulpal blood before, immediately after, 1 week after, and 1 month after the treatment. The results were analyzed using the SPSS software and repeated-measures analysis of variance and paired-samples t tests. The mean partial oxygen saturation of the blood was found to be 85.4% in the study group, which was not significantly different from that of the control group. No significant differences were observed in the control group between the means obtained from pretreatment and post-treatment intervals (P > 0.05). The Post-treatment partial oxygen saturation mean rose to 89.3% (P = 0.001) and remained constant throughout the following week after it. However, no significant differences were found between the pretreatment partial oxygen saturation mean and the same measurement 1 month after treatment (P = 0.702). Nd:YAG laser therapy for dentine desensitization of anterior teeth caused no persistent changes in the partial oxygen saturation of pulpal blood. It may, therefore, be concluded that the diffusion of heat induced by the Nd:YAG laser into the pulp within the limit of the desensitization parameters cause no irreversible damages in the dental pulp.

Wideband and high-gain frequency stabilization of a 100-W injection-locked Nd:YAG laser for second-generation gravitational wave detectors.

PubMed

Ohmae, Noriaki; Moriwaki, Shigenori; Mio, Norikatsu

2010-07-01

Second-generation gravitational wave detectors require a highly stable laser with an output power greater than 100 W to attain their target sensitivity. We have developed a frequency stabilization system for a 100-W injection-locked Nd:YAG (yttrium aluminum garnet) laser. By placing an external wideband electro-optic modulator used as a fast-frequency actuator in the optical path of the slave output, we can circumvent a phase delay in the frequency control loop originating from the pole of an injection-locked slave cavity. Thus, we have developed an electro-optic modulator made of a MgO-doped stoichiometric LiNbO(3) crystal. Using this modulator, we achieve a frequency control bandwidth of 800 kHz and a control gain of 180 dB at 1 kHz. These values satisfy the requirement for a laser frequency control loop in second-generation gravitational wave detectors.

Revised calibration of the Sm:SrB{sub 4}O{sub 7} pressure sensor using the Sm-doped yttrium-aluminum garnet primary pressure scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rashchenko, Sergey V., E-mail: rashchenko@igm.nsc.ru; Litasov, Konstantin D.; Novosibirsk State University, 630090 Novosibirsk

2015-04-14

The pressure-induced shift of Sm:SrB{sub 4}O{sub 7} fluorescence was calibrated in a quasi-hydrostatic helium medium up to 60 GPa using the recent Sm-doped yttrium-aluminum garnet primary pressure scale as a reference. The resulting calibration can be written as P = −2836/14.3 [(1 + Δλ/685.51){sup −14.3 }− 1]. Previous calibrations based on the internally inconsistent primary scales are revised, and, after appropriate correction, found to agree with the proposed one. The calibration extended to 120 GPa was also performed using corrected previous data and can be written as P = 4.20 Δλ (1 + 0.020 Δλ)/(1 + 0.036 Δλ)

Wear performance of garnet aluminium composites at high contact pressure

NASA Astrophysics Data System (ADS)

Sharma, Anju; Arora, Rama; Kumar, Suresh; Singh, Gurmel; Pandey, O. P.

2016-05-01

To satisfy the needs of the engineering sector, researchers and material scientists in this area adopted the development of composites with tailor made properties to enhance efficiency and cost savings in the manufacturing sector. The technology of the mineral industry is shaping the supply and demand of minerals derived materials. The composites are best classified as high performance materials have high strength-to-weight ratios, and require controlled manufacturing environments for optimum performance. Natural mineral garnet was used as the reinforcement of composite because of satisfactory mechanical properties as well as an attractive ecological alternative to others ceramics. For this purpose, samples have been prepared with different sizesof the garnet reinforcement using the mechanical stirring method to achieve the homogeneously dispersed strengthening phase. A systematic study of the effect of high contact pressure on the sliding wear behaviour of garnet reinforced LM13 alloy composites is presented in this paper. The SEM analysis of the worn samples and debris reveals the clues about the wear mechanism. The drastic improvement in the wear resistance of the composites at high contact pressure shows the high potential of the material to be used in engineering applications.

Comparative evaluation of antimicrobial effects of Er:YAG, diode, and CO₂ lasers on titanium discs: an experimental study.

PubMed

Tosun, Emre; Tasar, Ferda; Strauss, Robert; Kıvanc, Dolunay Gulmez; Ungor, Cem

2012-05-01

This study examined carbon dioxide (CO(2); 10,600 nm), diode (808 nm), and erbium (Er):yttrium-aluminum-garnet (YAG; 2,940 nm) laser applications on Staphylococcus aureus contaminated, sandblasted, large-grit, acid-etched surface titanium discs and performed a comparative evaluation of the obtained bactericidal effects and the applicability of these effects in clinical practice. This study was carried out in 5 main groups: Er:YAG laser in very short pulse (VSP) emission mode, Er:YAG laser in short pulse (SP) emission mode, diode laser with a 320-nm fiber optic diode laser with an R24-B handpiece, and CO(2) laser. After laser irradiation, dilutions were spread on sheep blood agar plates and, after an incubation period of 24 hours, colony-forming units were counted and compared with the control group, and the bactericidal activity was assessed in relation to the colony counts. The CO(2) laser eliminated 100% of the bacteria at 6 W, 20 Hz, and a 10-ms exposure time/pulse with a 10-second application period (0.8-mm spot size). The continuous-wave diode laser eliminated 97% of the bacteria at 1 W using a 10-second application with a 320-μm optic fiber, 100% of the bacteria were killed with a 1-W, 10-second continuous-wave application with an R14-B handpiece. The Er:YAG laser eliminated 100% of the bacteria at 90 mJ and 10 Hz using a 10-second application in a superpulse mode (300-ms exposure time/pulse). The Er:YAG laser also eliminated 99% to 100% of the bacteria in VSP mode at 90 mJ and 10 Hz with a 10-second application. The results of this study show that a complete, or near complete, elimination of surface bacteria on titanium surfaces can be accomplished in vitro using a CO(2), diode, or Er:YAG laser as long as appropriate parameters are used. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. All rights reserved.

Magnetic and fluorescence properties of cerium-doped yttrium gadolinium aluminum iron garnet crystals

NASA Astrophysics Data System (ADS)

Aoki, Daichi; Shima, Mutsuhiro

2014-11-01

Magnetic and fluorescence properties of chemically synthesized Ce:Gd-YAIG (Ce0.05GdxY2.95-xAl5-yFeyO12) nanocrystals have been investigated. The structural characterization by X-ray diffraction (XRD) shows that a garnet phase has been identified in samples with 0 ≤ x ≤ 2.95 and 0 ≤ y ≤ 3.0. When y = 0, only garnet peaks are observed for 0 ≤ x ≤ 2.5, while both garnet and perovskite phases are present for x > 2.5. It is found from XRD Rietveld analyses that the site occupancy of Fe3+ at the tetrahedral and octahedral sites in the garnet is independent of the amount of Y3+ substituted by Ce3+ and Gd3+ at the dodecahedral sites. The saturation magnetization for the sample with x = 0 and y = 3.0 is 4.35 emu/g, while that with x = 2.5 and y = 3.0 is 87.5 emu/g. When the Fe3+ composition y is varied from 0 to 3.0 at x = 2.5, the intensity of fluorescence at the emission wavelength ˜570 nm significantly decreases presumably due to absorption by Fe3+ that is increased in the crystal.

Comparative study on morphologic changes and cell attachment of periodontitis-affected root surfaces following conditioning with CO2 and Er:YAG laser irradiations.

PubMed

Belal, Mahmoud Helmy; Watanabe, Hisashi

2014-10-01

Clinical application of lasers in periodontal therapy has continued to expand in last decades; however there are still some controversies. The present study aimed to compare the conditioning effects of the carbon dioxide (CO2) or erbium-doped: yttrium, aluminum and garnet (Er:YAG) laser on periodontally diseased root surfaces following scaling and root planing (SRP) in terms of the alteration of morphologies as well as the attachment of periodontal ligament cells. Forty-five periodontally affected root specimens were prepared and randomly assigned into three groups: I control (untreated diseased), II. SRP+CO2 laser (pulsed, noncontact mode), and III. SRP+Er:YAG laser (slight contact mode). After treatment, five specimens in each group were used for surface topographic examination. The remaining 10 specimens in each group were incubated with human periodontal ligament cell suspension. All the specimens were finally evaluated by scanning electron microscopy. The control specimens showed the lowest number of cultured cells, mostly in oval shape, with no tightly attached cells. The CO2 lased specimens showed a significant increase in the number of attached cells compared with controls, but demonstrated some major thermal alterations on the surfaces. The Er:YAG lased specimens showed the significantly highest number of attached cells, mostly in flat form, and did not show distinct thermal damage. The present study suggests that compared with the CO2 laser, the Er:YAG laser may constitute a more useful conditioning tool for enhancing periodontal cell attachment to periodontally diseased root surfaces, with fewer undesirable thermal side effects.

Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

PubMed

Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei

2015-02-01

This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

Performance of Er:YAG laser ablation of hard bone under different irrigation water cooling conditions

NASA Astrophysics Data System (ADS)

Beltrán Bernal, Lina M.; Shayeganrad, Gholamreza; Kosa, Gabor; Zelechowski, Marek; Rauter, Georg; Friederich, Niklaus; Cattin, Philippe C.; Zam, Azhar

2018-02-01

The biological applicability of the Erbium-doped Yttrium Aluminum Garnet (Er:YAG) laser in surgical processes is so far limited to hard dental tissues. Using the Er:YAG laser for bone ablation is being studied since it has shown good performance for ablating dental hard tissues at the wavelength 2.94 μm, which coincides with the absorption peak of water, one of the main components of hard tissue, like teeth and bone. To obtain a decent performance of the laser in the cutting process, we aim at examining the influence of sequenced water jet irrigation on both, the ablation rate and the prevention of carbonization while performing laser ablation of bone with fixed laser parameters. An Er:YAG laser at 2.94 μm wavelength, 940 mJ energy per pulse, 400 μs pulse width, and 10 Hz repetition rate is used for the ablation of a porcine femur bone under different pulsed water jet irrigation conditions. We used micro-computed tomography (micro-CT) scans to determine the geometry of the ablated areas. In addition, scanning electron microscopy (SEM) is used for qualitative observations for the presence of carbonization and micro-fractures on the ablated surfaces. We evaluate the performance of the laser ablation process for the different water jet conditions in terms of the ablation rate, quantified by the ablated volume per second and the ablation efficiency, calculated as the ablated volume per pulse energy. We provide an optimized system for laser ablation which delivers the appropriate amount of water to the bone and consequently, the bone is ablated in the most efficient way possible without carbonization.

Effect of annealing temperature on surface morphology and ultralow ferromagnetic resonance linewidth of yttrium iron garnet thin film grown by rf sputtering

NASA Astrophysics Data System (ADS)

Cao Van, Phuoc; Surabhi, Srivathsava; Dongquoc, Viet; Kuchi, Rambabu; Yoon, Soon-Gil; Jeong, Jong-Ryul

2018-03-01

We report high-quality yttrium-iron-garnet (YIG; Y3Fe5O12) ultrathin films grown on {111} gadolinium-gallium-garnet (GGG; Gd3Ga5O12) substrates using RF sputtering deposition on an off-stoichiometric target and optimized thermal treatments. We measured a narrow peak-to-peak ferromagnetic resonance linewidth (ΔH) whose minimum value was 1.9 Oe at 9.43 GHz for a 60-nm-thick YIG film. This value is comparable to the most recently published value for a YIG thin film grown by pulsed laser deposition. The temperature dependence of the ΔH was investigated systematically, the optimal annealing condition for our growing condition was 875 °C. Structural analysis revealed that surface roughness and crystallinity played an important role in the observed ΔH broadening. Furthermore, the thickness dependence of the ΔH, which indicated that 60 nm thickness was optimal to obtain narrow ΔH YIG films, was also investigated. The thickness dependence of ΔH was understood on the basis of contributions of surface-associated magnon scattering and magnetic inhomogeneities to the ΔH broadening. Other techniques such as transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were used to study the crystalline structure of the YIG films. The high quality of the films in terms of their magnetic properties was expressed through a very low coercivity and high saturation magnetization measured using a vibration sample magnetometer.

Comparative Study of the Shear Bond Strength of Flowable Composite in Permanent Teeth Treated with Conventional Bur and Contact or Non-Contact Er:YAG Laser

PubMed Central

Parhami, Parisa; Pourhashemi, Seyed Jalal; Ghandehari, Mehdi; Mighani, Ghasem; Chiniforush, Nasim

2014-01-01

Introduction: The aim of this study was to evaluate and compare the in vitro effect of the Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser with different radiation distances and high-speed rotary treatment on the shear bond strength of flowable composite to enamel of human permanent posterior teeth. Methods: freshly extracted human molar teeth with no caries or other surface defects were used in this study (n=45). The teeth were randomly divided into 3 groups. Group 1: treated with non-contact Er:YAG Laser and etched with Er:YAG laser, Group 2: treated with contact Er:YAG Laser and etched with Er:YAG laser, Group 3 (control): treated with diamond fissure bur and etched with acid phosphoric 37%. Then the adhesive was applied on the surafces of the teeth and polymerized using a curing light appliance. Resin cylinders were fabricated from flowable composite. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. Results: The amount of Shear Bond Strength (SBS) in the 3 treatment groups was not the same (P<0.05).The group in which enamel surfaces were treated with diamond fissure bur and etched with acid (conrtol group) had the highest mean shear bond strength (19.92±4.76) and the group in which the enamel surfaces were treated with contact Er:YAG laser and etched with Er:YAG laser had the lowest mean shear bond strength (10.89±2.89). Mann-whitney test with adjusted P-value detected significant difference in shear bond strength between the control group and the other 2 groups (P < 0.05). Conclusion: It was concluded that both contact and non-contact Er:YAG laser treatment reduced shear bond strength of flowable resin composite to enamel in comparison with conventional treatment with high speed rotary. Different Er:YAG laser distance irradiations did not influence the shear bond strength of flowable composite to enamel. PMID:25653813

Efficacy of Nd:YAG and GaAlAs lasers in comparison to 2% fluoride gel for the treatment of dentinal hypersensitivity.

PubMed

Soares, Marília De Lima; Porciúncula, Geane Bandeira; Lucena, Mara Ilka Holanda Medeiros De; Gueiros, Luiz Alcino Monteiro; Leão, Jair Carneiro; Carvalho, Alessandra De Albuquerque Tavares

2016-01-01

Lasers demonstrate excellent therapeutic action and are often employed in dentistry for the treatment of diverse clinical conditions. The aim of this study was to compare the efficacy of neodymium-doped yttrium-aluminum-garnet (Nd:YAG) laser, gallium-aluminum-arsenide (GaAlAs) laser, and 2% neutral fluoride gel in the treatment of dentinal hypersensitivity. Twenty-three patients were evaluated, involving a total of 48 quadrants with at least 1 tooth with dentinal hypersensitivity (89 teeth total). Pain intensity was recorded on a visual analog scale at the time of clinical examination (baseline), immediately after treatment, and 1 week posttreatment. Teeth were treated with 60 seconds of 2% neutral fluoride gel application or 60 seconds of laser treatment-Nd:YAG laser at a distance of 0.5 cm (unfocused; 1 W and 10 Hz for 60 seconds, perpendicular to the cervical surfaces) or GaAlAs laser in contact (40 mW; 4 J/cm²; spot: 0.028 cm²; 15 seconds per point on 4 points [mesial, medial, distal, and apical])-as well as sham treatments so that patients remained blind to their treatment group. All treatments provided adequate pain reduction immediately posttreatment, but laser treatments resulted in significantly greater reductions in pain intensity.

Fragmentation targeted at preferred discontinuities: A new concept in endolithotripsy with Holmium laser:YAG.

PubMed

Sánchez-Martín, F M; Emiliani, E; Pueyo-Morer, E; Angerri-Feu, O; Sanguedolce, F; Millán, F; Villavicencio, H

2018-04-17

There are currently 3holmium laser, YAG (Ho:YAG) endolithotripsy procedures that are considered basic (fragmentation, pulverisation, "pop-corn" technique). We present the technique of fragmentation targeted at preferred discontinuities (FTPD), a new concept of endolithotripsy by Ho:YAG laser. The FTPD technique is based on the selective application of energy (targeting a specific preselected point) to an area that is visually prone to the formation of a fracture line or preferred discontinuity (conditioned by the anisotropy of the urolithiasis). The ideal energy regimen (setting) is a high range of working energy (2-3J) with a very low frequency range (5-8Hz) and short pulse width. Between January 2015 to February 2017, the FTPD technique was used in 37 procedures (7 NLP, 16 RIRS, 12 URS, 2 cystolithotomies), with a Ho:YAG laser (Lumenis Pulse 120H ® , Tel-Aviv, Israel). Maximum power used: 24W (3J/8Hz) with fibres of 365μ and 273μ (URS, RIRS), and 32W (4J/8Hz) with fibres of 550μ (NLP, cystolithotomy). Strategic improvement was achieved in all cases using the TFPD technique to continue the endolithotripsy or remove fragments. No complications were recorded after the use of this method. FTPD can be considered a complementary option in combination with the basic methods of fragmentation and pulverisation. In our experience, it constitutes significant progress in optimising the performance of Ho:YAG laser endolithotripsy. Copyright © 2018 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

The effects of the Er:YAG laser on trabecular bone micro-architecture: Comparison with conventional dental drilling by micro-computed tomographic and histological techniques

PubMed Central

Zeitouni, Jihad; Clough, Bret; Zeitouni, Suzanne; Saleem, Mohammed; Al Aisami, Kenan; Gregory, Carl

2017-01-01

Background: The use of lasers has become increasingly common in the field of medicine and dentistry, and there is a growing need for a deeper understanding of the procedure and its effects on tissue. The aim of this study was to compare the erbium-doped yttrium aluminium garnet (Er:YAG) laser and conventional drilling techniques, by observing the effects on trabecular bone microarchitecture and the extent of thermal and mechanical damage. Methods: Ovine femoral heads were employed to mimic maxillofacial trabecular bone, and cylindrical osteotomies were generated to mimic implant bed preparation. Various laser parameters were tested, as well as a conventional dental drilling technique. The specimens were then subjected to micro-computed tomographic (μCT) histomorphometic analysis and histology. Results: Herein, we demonstrate that mCT measurements of trabecular porosity provide quantitative evidence that laser-mediated cutting preserves the trabecular architecture and reduces thermal and mechanical damage at the margins of the cut. We confirmed these observations with histological studies. In contrast with laser-mediated cutting, conventional drilling resulted in trabecular collapse, reduction of porosity at the margin of the cut and histological signs of thermal damage. Conclusions: This study has demonstrated, for the first time, that mCT and quantification of porosity at the margin of the cut provides a quantitative insight into damage caused by bone cutting techniques. We further show that with laser-mediated cutting, the marrow remains exposed to the margins of the cut, facilitating cellular infiltration and likely accelerating healing. However, with drilling, trabecular collapse and thermal damage is likely to delay healing by restricting the passage of cells to the site of injury and causing localized cell death. PMID:29416849

Evaluation of Mineral Content and Photon Interaction Parameters of Dental Enamel After Phosphoric Acid and Er:YAG Laser Treatment.

PubMed

Simsek, Huseyin; Gurbuz, Taskın; Buyuk, Suleyman Kutalmış; Ozdemir, Yuksel

2017-05-01

The purpose of this study was to evaluate the effects of laser and acid etching on the mineral content and photon interaction parameters of dental enamel in human teeth. The composition of dental enamel may vary, especially at the surface, depending on the reactions that occur during dental treatment. Forty maxillary premolars were divided randomly into 2 groups of 20 teeth. In the first group, half of teeth crowns were etched by using 37% phosphoric acid; in the second group, half of teeth crowns were etched by using an erbium:yttrium-aluminum-garnet (Er:YAG) laser. The remaining half crowns in each group were used as untreated controls. We characterized the calcium (Ca), phosphorus (P), magnesium (Mg), sodium (Na), and potassium (K) contents in each specimen by using wavelength dispersive X-ray fluorescence spectrometry. The total atomic cross-section ([Formula: see text]), effective atomic number ([Formula: see text]), and electron density (N e ) of the tooth samples were determined at photon energies of 22.1, 25, 59.5, and 88 keV by using a narrow beam transmission method. Data were analyzed statistically by using the Mann-Whitney U test. The mineral contents after Er:YAG laser and phosphoric acid etching did not differ significantly (p > 0.05), and no significant variation in [Formula: see text], [Formula: see text], or N e was observed. Therefore, we conclude that the Er:YAG laser and phosphoric acid systems used in this study did not affect mineral composition or photon interaction parameters of dental enamel.

Morphological and Histological Effects of Radiofrequency and Laser (KTP and Nd:YAG) Treatment of the Inferior Turbinates in Animals.

PubMed

Somogyvári, Krisztina; Móricz, Péter; Gerlinger, Imre; Kereskai, László; Szanyi, István; Takács, Ildikó

2017-02-01

The aim of this study was to evaluate the short and medium-term effects of radiofrequency (RF) and potassium titanyl phosphate (KTP) and neodymium-yttrium-aluminum garnet (Nd:YAG) laser treatment on the inferior turbinate mucosa in a porcine model. Following randomization, the inferior turbinates were treated either with RF submucosally or with the KTP or the Nd:YAG laser on the surface under videoendoscopic control. Tissue samples were taken at the end of postoperative weeks 1 and 6, and were evaluated macroscopically and histopathologically. Scanning electron microscopy was implemented to demonstrate the morphological changes in the respiratory epithelium. Six weeks following the RF procedure, the mucosa was intact in all cases, and the volume of the inferior turbinates was reduced in the majority of the cases. Although a volume reduction occurred in both laser groups, more complications associated with the healing procedure were noted. With hematoxylin and eosin and periodic acid-Schiff staining, intact epithelium, and submucosal glands remained after the RF procedures at the end of postoperative week 6. Following the KTP-laser intervention, necrotizing sialometaplasia and cartilage destruction occurred, and squamous metaplasia was also apparent in the Nd:YAG group. In both laser groups, dilated glands with excess mucus were seen. The scanning electron microscopic findings demonstrated that cilia were present in all cases. In conclusion, the medium-term macroscopic results were similar in all 3 groups, but the postoperative complications were less following the RF procedure. RF procedure is minimally invasive due to the submucosal intervention that leads to a painless, function preserving recovery.

Composition engineering of single crystalline films based on the multicomponent garnet compounds

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Bilski, Paweł; Twardak, Anna; Voznyak, Taras; Sidletskiy, Oleg; Gerasimov, Yaroslav; Gryniov, Boris; Fedorov, Alexandr

2016-11-01

The paper demonstrates our last achievement in development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped multicomponent garnets using the Liquid Phase Epitaxy (LPE) method. We report in this work the optimized content and excellent scintillation properties of SCF of Lu3-xGdxAl5-yGayO12, Lu3-xTbxAl5-yGayO12 and TbxGdxAl5-yGayO12 garnet compounds grown by the LPE method from PbOsbnd B2O3 based melt-solution onto Gd3Al2.5Ga2.5O12 and YAG substrates. We also show that the Tb1.5Gd1.5Al2.5Ga2.5O12:Ce SCF possess the highest light yield (LY) in comparison with all ever grown garnet SCF scintillators. Namely, the LY of these SCF exceeds by 3.8 and 1.85 times the LY values of the best samples of YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCF samples of the mentioned compounds show low thermoluminescence in the above room temperature range and relatively fast scintillation decay time t1/e in the 180-200 ns range.

Laboratory investigation of the efficacy of holmium:YAG laser irradiation in removing intracanal debris

NASA Astrophysics Data System (ADS)

Nuebler-Moritz, Michael; Gutknecht, Norbert; Sailer, Hermann F.; Hering, Peter; Prettl, Wilhelm

1997-05-01

Current endodontic therapy involves debridement and disinfection of the root canal by means of mechanical instrumentation and chemical irrigation. However, several studies have shown that these techniques fail to achieve complete cleansing. Recently, lasers have been suggested for use within root canals. This study was conducted to determine the efficacy of Holmium:YAG laser irradiation in removing intracanal debris and smear layer. Root canal surfaces of freshly-extracted human teeth were exposed to pulsed Ho:YAG laser radiation. Subsequently, laser induced structural changes were investigated using scanning electron microscopy. Temperature measurements during irradiation were performed by means of thermocouples. The result of this survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment modalities. However, limitations exist with regard to circumscribed and well-quantified irradiation of root canal surfaces, due to the lack of perpendicular delivery of the laser beam. Additional studies will be required to develop suitable optical transmission systems, in order to achieve complete cleansing and to avoid damage to the periradicular tissues, respectively.

Palliative treatment of malignant stenoses of the lower airways with the FIBERTOM Nd:YAG laser

NASA Astrophysics Data System (ADS)

Pirozynski, Michal; Polubiec-Kownacka, Malgorzata; Strojecki, Krzysztof; Blachnio, Antoni; Pawlak, Wieslaw; Krusiewicz, Jan

1996-03-01

Neodymium yttrium aluminum garnet (Nd:YAG) laser, with its infrared wavelength of 1064 nm, is at present the most useful modality in treatment of lower airways obstruction of the lower airways by malignant and benign lesions. In fact that was the first indication for a successful restoration of a narrowed airway by Toty et al. The therapeutical effects of this laser are based on thermal action. The exposed tissue undergoes a progressive transformation by a localized increase in the temperature from warming, protein coagulation, to evaporation of water and vaporization of the tissue. This study represents the initial experience with the use of the FIBERTOMTM Nd:YAG laser in removal of obstructing malignant and non- malignant lesions of the lower airways. Twenty-six patients (mean age 55.7 plus or minus 17.4 years) were included in the study. The main indications for laser therapy were in 16 patients exophytic cancerous lesions of the trachea and main bronchi, benign tumors of the major airways in 6, and in 4 cancerous lesions of the lobar bronchi. Squamous cell lung cancer and adenocarcinoma were diagnosed most often. The degree of obstruction ranged from 70% to 99%. Complete recanalization was achieved in 19 of the 26 patients, in only one patient recanalization was not achieved. The major complication was fever -- seen in 17 (65.4%) patients and cough (19.2%). Long term observation identified 18 patients alive after 52 weeks following laser therapy.

Effect of pulse duration on photomechanical response of soft tissue during Ho:YAG laser ablation

NASA Astrophysics Data System (ADS)

Jansen, E. Duco; Motamedi, Massoud; Pfefer, T. Joshua; Asshauer, Thomas; Frenz, Martin; Delacretaz, Guy P.; Abela, George S.; Welch, Ashley J.

1995-05-01

Mechanical injury during pulsed holmium laser ablation of tissue is caused by rapid bubble expansion and collapse or by laser-induced pressure waves. In this study the effect of pulse duration on the photomechanical response of soft tissue during holmium:YAG laser ablation has been investigated. The dynamics of laser-induced bubble formation was documented in water and in transparent polyacrylamide tissue phantoms with a water concentration of 84%. Holmium:YAG laser radiation ((lambda) equals 2.12 micrometers ) was delivered in water or tissue phantoms via an optical fiber (200 or 400 micrometers ). The laser was operated in either the Q- switched mode ((tau) p equals 500 ns, Qp equals 14 +/- 1 mJ, 200 micrometers fiber, Ho equals 446 mJ/mm2) or the free-running mode ((tau) p equals 100 - 1100 microsecond(s) , Qp equals 200 +/- 5 mJ, 400 micrometers fiber, Ho equals 1592 mJ/mm2). Bubble formation was documented using a fast flash photography setup while simultaneously a PVDP needle hydrophone (40 ns risetime), recorded pressures. The effect of the pulse duration on the photomechanical response of soft biological tissue was evaluated by delivering 5 pulses of 800 mJ to the intimal side of porcine aorta in vitro, followed by histologic evaluation. It was observed that, as the pulse duration was increased the bubble shape changed from almost spherical for Q-switched pulses to a more elongated, cylindrical shape for the longer pulse durations. The bubble expansion velocity was larger for shorter pulse durations. A thermo- elastic expansion wave was measured only during Q-switched pulse delivery. All pulses that induced bubble formation generated pressure waves upon collapse of the bubble in water as well as in the gel. The amplitude of the pressure wave depended strongly on the size and geometry of the laser-induced bubble. The important findings of this study were (1) the magnitude of collapse pressure wave decreased as laser pulse duration increased, and (2

Q-Switched 660-nm Versus 532-nm Nd: YAG Laser for the Treatment for Facial Lentigines in Asian Patients: A Prospective, Randomized, Double-Blinded, Split-Face Comparison Pilot Study.

PubMed

Noh, Tai Kyung; Chung, Bo Young; Yeo, Un Cheol; Chang, SeoYoun; Lee, Mi Woo; Chang, Sung Eun

2015-12-01

Q-switched (QS) 532-nm lasers are widely used to treat solar lentigines. To compare the efficacy and safety of 660-nm and 532-nm QS neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers in the treatment for lentigines in Asians. The halves of each face (randomly chosen) of 8 Korean Fitzpatrick Skin Type III-IV women with facial solar lentigines were treated with either 660-nm or 532-nm lasers. Pigmentation was measured objectively using a profilometric skin analysis tool and subjectively using the pigmentation area and severity index (PSI) score, global assessment of the aesthetic improvement scale (GAIS), and a patient satisfaction score at Weeks 4 and 8. Seven patients completed the study. No significant differences were found in the PSI, GAIS, patient satisfaction score, and melanin average score between the lasers. The melanin average level was significantly reduced by the 660-nm laser but not the 532-nm laser at Week 8 compared with the baseline. Both 660-nm and 532-nm QS Nd:YAG lasers effectively reduce pigmentation for up to 8 weeks with high patient satisfaction. The new 660-nm laser therefore increases the treatment options for lentigines in Asian skin.

Co2/Erbium:YAG/Dye laser combination: an effective and successful treatment for angiofibromas in tuberous sclerosis.

PubMed

Fioramonti, Paolo; De Santo, Liliana; Ruggieri, Martina; Carella, Sara; Federico, Lo Torto; Onesti, Maria Giuseppina; Scuderi, Nicolò

2014-02-01

Tuberous sclerosis, an autosomal dominant neurocutaneous syndrome seen in approximately 1 in 6,000 people worldwide, is characterized by the appearance of hamartomas in multiple organs. The classic clinical triad consists of angiofibromas, epilepsy, and developmental delay. Dermatologic disorder is one of the main characteristics. Angiofibromas, a common form of presentation, causes significant cosmetic and medical problems. The current treatment for skin lesions is laser therapy. The carbon dioxide (CO2) laser has been used satisfactorily in treating these lesions, but several studies have demonstrated a high percentage of recurrences. Erbium:yttrium-aluminum-garnet (YAG) laser treatment has been used to resurface skin abnormalities in patients with dermatologic conditions. The dye laser as an alternative uses the principles of selective photothermolysis and is very effective in treating the vascular component of tuberous sclerosis. The use of all these lasers to treat skin lesions in patients affected by tuberous sclerosis has never been described in the literature. A retrospective study, conducted from 2007 to May 2013, investigated 13 patients who had tuberous sclerosis treated with an erbium:YAG/CO2/dye laser combination. All the patients showed great improvement of their skin lesions. The results were evident immediately after the first treatment. No patient experienced complications or recurrence. The combined use of the erbium:YAG/Dye/CO2 laser is a safe and effective treatment for skin lesions in patients affected by tuberous sclerosis. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Strong excitation of surface and bulk spin waves in yttrium iron garnet placed in a split ring resonator

NASA Astrophysics Data System (ADS)

Tay, Z. J.; Soh, W. T.; Ong, C. K.

2018-02-01

This paper presents an experimental study of the inverse spin Hall effect (ISHE) in a bilayer consisting of a yttrium iron garnet (YIG) and platinum (Pt) loaded on a metamaterial split ring resonator (SRR). The system is excited by a microstrip feed line which generates both surface and bulk spin waves in the YIG. The spin waves subsequently undergo spin pumping from the YIG film to an adjacent Pt layer, and is converted into a charge current via the ISHE. It is found that the presence of the SRR causes a significant enhancement of the mangetic field near the resonance frequency of the SRR, resulting in a significant increase in the ISHE signal. Furthermore, the type of spin wave generated in the system can be controlled by changing the external applied magnetic field angle (θH ). When the external applied magnetic field is near parallel to the microstrip line (θH = 0 ), magnetostatic surface spin waves are predominantly excited. On the other hand, when the external applied magnetic field is perpendicular to the microstrip line (θH = π/2 ), backward volume magnetostatic spin waves are predominantly excited. Hence, it can be seen that the SRR structure is a promising method of achieving spin-charge conversion, which has many advantages over a coaxial probe.

Retreatment using a dual mode of low-fluence Q-switched and long-pulse Nd:YAG laser in patients with melasma aggravation after previous therapy.

PubMed

Choi, Chun Pil; Yim, Seon Mi; Seo, Soo Hong; Ahn, Hyo Hyun; Kye, Young Chul; Choi, Jae Eun

2015-06-01

Aggravated melasma after treatment is vulnerable to stimulation, can easily deteriorate, and may be distressing without proper management. To retrospectively assess the effectiveness and safety of combination therapy using low-fluence Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (QSNY) and long-pulse Nd:YAG laser (LPNY) (dual toning) in patients with rebound melasma. A total of 30 patients with aggravated melasma after previous therapy who were treated with dual toning were enrolled. A total of 10 sessions were conducted at 1-week intervals, followed by maintenance treatment. The results were evaluated using the modified Melasma Area and Severity Index (mMASI) and the physician's global assessment (PGA) before and 2 months after completing the 10 treatment sessions. The baseline mMASI was 10.48 ± 3.64, which significantly decreased to 3.22 ± 1.45 2 months after completing the 10 treatment sessions (p < 0.001). Twenty-four patients (80%) had PGA grade 4 (76-100% improvement) and 6 patients (20%) had PGA grade 3 (51-75% improvement). Dual toning may be a safe and effective salvage treatment for patients with aggravated melasma after previous treatment. LPNY may stabilize melasma activity to prevent rebound hyperpigmentation via dermal remodeling.

Comparison of a novel high-power blue diode laser (λ=442 nm) with Ho:YAG (λ=2100 nm), Tm fiber (λ=1940 nm), and KTP (λ=532 nm) lasers for soft tissue ablation

NASA Astrophysics Data System (ADS)

Vinnichenko, Victoriya; Kovalenko, Anastasiya; Arkhipova, Valeriya; Yaroslavsky, Ilya; Altshuler, Gregory; Gapontsev, Valentin

2018-02-01

Three lasers were directly compared, including the Ho:YAG laser (λ = 2100 nm), Tm fiber laser (λ = 1940 nm) operating in 3 different modes (CW, regular pulse, and super pulse), and blue diode laser (λ = 442 nm) for vaporization and coagulation efficiency for treating blood-rich soft tissues, ex vivo, in a porcine kidney model at quasi-contact cutting in water. In addition, experimental results were compared with published data on performance of KTP laser (λ = 532 nm) at similar experimental settings (Power = 60 W and cutting speed = 2 mm/s). Tm fiber laser in pulsed mode and blue laser produced highest vaporization rates of 3.7 and 3.4 mm3/s, respectively. Tm fiber laser (in both CW and pulsed modes) also produced the largest coagulation zone among the laser sources tested. A carbonization zone was observed for Tm fiber laser in CW and pulsed modes, as well as for the blue diode laser. Tm fiber laser in super-pulse mode and Ho:YAG laser both resulted in irregular coagulation zones without carbonization. Comparison with known data for KTP laser revealed that tissue effects of the blue laser are similar to that of the KTP laser. These results suggest that the combination of the two lasers (Tm fiber and blue diode) in one system may achieve high cutting efficiency and optimal coagulation for hemostasis during surgical treatment. Ex vivo testing of the combined system revealed feasibility of this approach. The combination of the CW Tm fiber laser (120W) and the blue diode laser (60W) emitting through a combination tip were compared with CW 120 W Tm fiber laser alone and 120 W Ho:YAG laser. Vaporization rates measured 34, 28, and 6 mm3/s, and coagulation zones measured 0.6, 1.3, and 1.7 mm, respectively. A carbonization zone was only observed with CW Tm fiber laser. The vaporization rate of combined CW Tm fiber laser / blue diode laser was comparable to published data for KTP laser for equivalent total power. Thus, high-power blue diode laser, Tm fiber laser, and

Optimization of sintering conditions for cerium-doped yttrium aluminum garnet

NASA Astrophysics Data System (ADS)

Cranston, Robert Wesley McEachern

YAG:Ce phosphors have become widely used as blue/yellow light converters in camera projectors, white light emitting diodes (WLEDs) and general lighting applications. Many studies have been published on the production, characterization, and analysis of this optical ceramic but few have been done on determining optimal synthesis conditions. In this work, YAG:Ce phosphors were synthesized through solid state mixing and sintering. The synthesized powders and the highest quality commercially available powders were pressed and sintered to high densities and their photoluminescence (PL) intensity measured. The optimization process involved the sintering temperature, sintering time, annealing temperature and the level of Ce concentration. In addition to the PL intensity, samples were also characterized using particle size analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The PL data was compared with data produced from a YAG:Ce phosphor sample provided by Christie Digital. The peak intensities of the samples were converted to a relative percentage of this industry product. The highest value for the intensity of the commercial powder was measured for a Ce concentration of 0.3 mole% with a sintering temperature of 1540°C and a sintering dwell time of 7 hours. The optimal processing parameters for the in-house synthesized powder were slightly different from those of commercial powders. The optimal Ce concentration was 0.4 mole% Ce, sintering temperature was 1560°C and sintering dwell time was 10 hours. These optimal conditions produced a relative intensity of 94.20% and 95.28% for the in-house and commercial powders respectively. Polishing of these samples resulted in an increase of 5% in the PL intensity.

Moderate high power 1 to 20μs and kHz Ho:YAG thin disk laser pulses for laser lithotripsy

NASA Astrophysics Data System (ADS)

Renz, Günther

2015-02-01

An acousto-optically or self-oscillation pulsed thin disk Ho:YAG laser system at 2.1 μm with an average power in the 10 W range will be presented for laser lithotripsy. In the case of cw operation the thin disk Ho:YAG is either pumped with InP diode stacks or with a thulium fiber laser which leads to a laser output power of 20 W at an optical-to-optical efficiency of 30%. For the gain switched mode of operation a modulated Tm-fiber laser is used to produce self-oscillation pulses. A favored pulse lengths for uric acid stone ablation is known to be at a few μs pulse duration which can be delivered by the thin disk laser technology. In the state of the art laser lithotripter, stone material is typically ablated with 250 to 750 μs pulses at 5 to 10 Hz and with pulse energies up to a few Joule. The ablation mechanism is performed in this case by vaporization into stone dust and fragmentation. With the thin disk laser technology, 1 to 20 μs-laser pulses with a repetition rate of a few kHz and with pulse energies in the mJ-range are available. The ablation mechanism is in this case due to a local heating of the stone material with a decomposition of the crystalline structure into calcium carbonate powder which can be handled by the human body. As a joint process to this thermal effect, imploding water vapor bubbles between the fiber end and the stone material produce sporadic shock waves which help clear out the stone dust and biological material.

Environmental Acceptable Medium Caliber Ammunition Percussion Primers

DTIC Science & Technology

2008-05-01

the nanoparticles extremely hydrophobic. The alternative treatment of the solution was the addition of ammonium dihydrogen phosphate (ADP) to serve as...Ultrafine Aluminum Nanoparticles," LA-UR-04-2921. 49 ACRONYM LIST ADP Ammonium Dihydrogen Phosphate Al Aluminum ARDEC Armament Research Development and...Nitrocellulose Nd:Yag Neodymium -doped yttrium aluminum garnet NSWC-IH Naval Surface Warfare Center- Indian Head PAD Propellant actuated device PETN

Microleakage of Self-Etch Adhesive System in Class V Cavities Prepared by Using Er:YAG Laser with Different Pulse Modes.

PubMed

Phanombualert, Jutipond; Chimtim, Pijitta; Heebthamai, Thitirat; Weera-Archakul, Wilawan

2015-09-01

In vitro studies evaluated cementum surface morphology and microleakage of three different energy density parameters of Erbium: Yttrium Aluminum Garnet (Er:YAG) laser compared with diamond bur preparation on class V cavities with self-etch adhesive system and composite resin restoration. Standard class V cavities were prepared at cervical area below the cementoenamel junction (CEJ) in 80 extracted premolars, by using a diamond bur on the buccal surface. All teeth were randomly allocated into four groups: Group 1, diamond bur; Group 2, Er:YAG 50 mJ/15 Hz, 3.77 J/cm(2); Group 3, Er:YAG 75 mJ/15 Hz, 5.65 J/cm(2); and Group 4, Er:YAG 100 mJ/15 Hz, 7.53 J/cm(2). Five cavities from each group were evaluated by scanning electron microscopy (SEM). The 15 remaining cavities from each group were restored with self-etch adhesive and nano-hybrid composite. After thermocycling, all sample teeth were immersed in 0.2% methylene blue dye and sectioned buccolingually. Statistics were analyzed using the one way ANOVA and Mann-Whitney U tests with Bonferroni correction. The morphology showed micro-irregularities in the cementum surface of the laser group with the absence of a smear layer. The microstructure characteristics were increased surface roughness followed by increasing laser energy transmission. The Er:YAG laser groups were statistically significant, with less microleakage than the diamond bur group (p<0.05). There was statistically significant difference between the occlusal and gingival microleakage in all the groups (p<0.05). When the laser groups were compared, the lowest microleakage was achieved with energy density at 3.77 J/cm(2) on the occlusal and gingival cementum margin, which showed less microleakage than at energy densities of 5.65 and 7.53 J/cm(2) with Er:YAG laser. These observations indicate that the micro-irregularities of the cementum surface could facilitate the formation of a hybridization zone with a self-etch adhesive system

Mid-Infrared Laser Orbital Septal Tightening

PubMed Central

Chu, Eugene A.; Li, Michael; Lazarow, Frances B.; Wong, Brian J. F.

2014-01-01

IMPORTANCE Blepharoplasty is one of the most commonly performed facial aesthetic surgeries. While myriad techniques exist to improve the appearance of the lower eyelids, there is no clear consensus on the optimal management of the orbital septum. OBJECTIVES To evaluate the safety and feasibility of the use of the holmium:yttrium aluminum garnet (Ho:YAG) laser for orbital septal tightening, and to determine whether modest use of this laser would provide some degree of clinical efficacy. DESIGN, SETTING, AND PARTICIPANTS Direct laser irradiation of ex vivo bovine tissue was used to determine appropriate laser dosimetry using infrared thermal imaging and optical coherence tomography before conducting a pilot clinical study in 5 patients. Laser irradiation of the lower eyelid orbital septum was performed through a transconjunctival approach. Standardized preoperative and postoperative photographs were taken for each patient and evaluated by 6 unbiased aesthetic surgeons. EXPOSURE Use of the Ho:YAG laser for orbital septal tightening. MAIN OUTCOME AND MEASURE To determine appropriate laser dosimetry, infrared thermal imaging and optical coherence tomography were used to monitor temperature and tissue shape changes of ex vivo bovine tissue that was subjected to direct laser irradiation. For the clinical study, preoperative and postoperative photographs were evaluated by 6 surgeons on a 10-point Likert scale. RESULTS Optical coherence tomography demonstrated that laser irradiation of bovine tissue to a temperature range of 60°C to 80°C resulted in an increase in thickness of up to 2-fold. There were no complications or adverse cosmetic outcomes in the patient study. Patient satisfaction with the results of surgery averaged 7 on a 10-point Likert scale. For 3 patients, 3 (50%) of the evaluators believed there was a mild improvement in appearance of the lower eyelids after surgery. The remaining patients were thought to have no significant changes. CONCLUSIONS AND

High-fluence 1064-nm Q-Switched Nd:YAG laser: Safe and effective treatment of café-au-lait macules in Asian patients.

PubMed

Baek, Jin Ok; Park, Il-Joong; Lee, Kyung Real; Ryu, Ha Ryeong; Kim, Jeongsoo; Lee, Seulki; Kim, Yu Ri; Hur, Hoon

2018-06-01

Café-au-lait macules (CALMs) are benign cutaneous hyperpigmentary disorders. Usually, laser therapies for cosmetic concerns result in more severe side effects in the people of Asian descent than that of Caucasians. Unfortunately, there is no gold standard for the laser treatment of CALMs in skin of people of Asian descent. To investigate the efficacy and safety of a high-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) laser treatment of CALMs in Asian patients. The medical records of 35 Korean patients (age range: 1 to 40 years old, mean age: 18.5 years) diagnosed with isolated CALMs were reviewed retrospectively. The patients were treated with a 1064-nm Q-switched Nd:YAG laser. The parameters were a spot size of 7 mm, a fluence of 2.2-2.4 J/cm 2 with a slow single sliding-stacking pass, and a pulse rate of 10 Hz with a 1-week interval for 20-50 sessions. At the week of the final treatment, all treated CALMs showed considerable pigmentation removal without any permanent side effects, such as scaring, mottled hypopigmentation and postinflammatory hyperpigmentation (PIH). All treated CALMs showed more than 50% clinical improvement. No recurrence was observed in any of the patients after 12 months of follow-up. A high-fluence 1064-nm Q-switched Nd:YAG laser treatment of CALMs in Asian patients is a safe and effective method without side effects and recurrence. © 2018 Wiley Periodicals, Inc.

Comparison of Er:YAG laser and surgical drill for osteotomy in oral surgery: an experimental study.

PubMed

Gabrić Pandurić, Dragana; Bago, Ivona; Katanec, Davor; Zabkar, Janez; Miletić, Ivana; Anić, Ivica

2012-11-01

High-energy lasers have been proposed as an alternative to the conventional surgical drill in oral and maxillofacial surgery. The aims of this study were to compare thermal changes of the bone surface, procedure time, and volume of the removed bone after drilling with an erbium (Er):yttrium-aluminum-garnet (YAG) laser versus a low-speed surgical drill. The bone sections were observed under light microscopy and examined histologically. Thirty bone blocks were prepared from porcine ribs. On each block 2 holes (tunnel preparations) were performed using a low-speed, 1.0-mm-wide, surgical pilot drill and an Er:YAG laser (pulse energy, 1,000 mJ; pulse duration, 300 μs; frequency, 20 Hz). The temperature induced by the preparation techniques was measured using an infrared camera. The removed bone volume was calculated by a modified mathematical algorithm. The time required for the preparation was measured with a digital stopwatch and a time-measurement instrument integrated within the computer program. The cortical and spongiose surfaces of the specimens were examined microscopically and histologically under a light microscope with a high-resolution camera. The Er:YAG laser removed significantly more bone tissue than the drill (P < .01) in a significantly shorter time (P < .01). The temperature was statistically lower during the laser preparation (P < .01). Cavities prepared with the laser were regular with clear sharp edges and knifelike cuts. In the drill group, the preparations exhibited irregular edges full of bone fragments and fiberlike debris. Histologic examination of the laser sides showed a 30-μm-thick altered sublayer. The tissue in the drill group was covered with a smear layer without any alterations. The Er:YAG laser produced preparations with regular and sharp edges, without bone fragments and debris, in a shorter time, and with less generated heat. Thermal alterations in the treated surface were minimal. Copyright © 2012 American Association of Oral and

Combined external-beam PIXE and /μ-Raman characterisation of garnets used in Merovingian jewellery

NASA Astrophysics Data System (ADS)

Calligaro, T.; Colinart, S.; Poirot, J.-P.; Sudres, C.

2002-04-01

Red garnets were the dominant gemstones used for jewels in Europe during the Early Middle Ages. We have studied over 350 garnets set on 12 jewels unearthed in the royal necropolis of the Saint-Denis Basilica, close to Paris. This famous collection of "cloisonné" style artefacts dates from the Merovingian period (late fifth century AD to early seventh century AD). The archaeological issue addressed is the identification of the geographical origin of these garnets, in view to establish the gem trading routes during the Dark Ages. External beam PIXE was used to determine the major constituents (Mg, Al, Si, Ca, Mn, Fe), specifying the garnet type (composition in various mineralogical end-members, e.g. almandine, pyrope, spessartite, …), and the trace element content (Cr, Y). Three sorts of garnets were identified. Ten jewels are adorned with almandine garnets (Fe-rich). One jewel has intermediate almandine-pyrope garnets ("rhodolite"). The last and most recent jewel is inlaid with pyrope (Mg-rich) garnets. Trace element content and slight differences in major composition allowed to distinguish five different sources: two sources for pyrope garnets (with and without chromium), and two sources for almandine garnets (distinctive calcium, magnesium and yttrium contents). A preliminary comparison with literature data suggested that almandine garnets may have been mined from India while the "rhodolite" garnets may have been imported from Sri Lanka. The sources of pyrope garnets could be the Bohemian deposits (Czech republic). In addition, μ-Raman spectrometry was used to identify most of the mineral inclusions (apatite, zircon, ilmenite, monazite, calcite, quartz) present in almandine garnets. Even if two specific types of inclusions were not identified, due to the lack of corresponding reference spectra in our database, the Raman spectra collected provided an interesting inclusion fingerprint.

CW laser damage testing of RAR nano-textured fused silica and YAG

NASA Astrophysics Data System (ADS)

MacLeod, Bruce D.; Hobbs, Douglas S.; Manni, Anthony D.; Sabatino, Ernest; Bernot, David M.; DeFrances, Sage; Randi, Joseph A.; Thomas, Jeffrey

2017-11-01

A study of the continuous wave (CW) laser induced damage threshold (LiDT) of fused silica and yttrium aluminum garnet (YAG) optics was conducted to further illustrate the enhanced survivability within high power laser systems of an anti-reflection (AR) treatment consisting of randomly distributed surface relief nanostructures (RAR). A series of three CW LiDT tests using the 1070nm wavelength, 16 KW fiber laser test bed at Penn State Electro-Optic Center (PSEOC) were designed and completed, with improvements in the testing protocol, areal coverage, and maximum exposure intensities implemented between test cycles. Initial results for accumulated power, stationary site exposures of RAR nano-textured optics showed no damage and low surface temperatures similar to the control optics with no AR treatment. In contrast, optics with thin-film AR coatings showed high surface temperatures consistent with absorption by the film layers. Surface discriminating absorption measurements made using the Photothermal Common-path Interferometry (PCI) method, showed zero added surface absorption for the RAR nanotextured optics, and absorption levels in the 2-5 part per million range for thin-film AR coated optics. In addition, the surface absorption of thin-film AR coatings was also found to have localized absorption spikes that are likely pre-cursors for damage. Subsequent CW LiDT testing protocol included raster scanning an increased intensity focused beam over the test optic surface where it was found that thin-film AR coated optics damaged at intensities in the 2 to 5 MW/cm2 range with surface temperatures over 250C during the long-duration exposures. Significantly, none of the 10 RAR nano-textured fused silica optics tested could be damaged up to the maximum system intensity of 15.5 MW/cm2, and surface temperatures remained low. YAG optics tested during the final cycle exhibited a similar result with RAR nano-textured surfaces surviving intensities over 3 times higher than thin

Influence of doping on thermal diffusivity of single crystals used in photonics: measurements based on thermal wave methods.

PubMed

Bodzenta, Jerzy; Kaźmierczak-Bałata, Anna; Wokulska, Krystyna B; Kucytowski, Jacek; Łukasiewicz, Tadeusz; Hofman, Władysław

2009-03-01

Three crystals used in solid-state lasers, namely, yttrium aluminum garnet (YAG), yttrium orthovanadate (YVO(4)), and gadolinium calcium oxoborate (GdCOB), were investigated to determine the influence of dopants on their thermal diffusivity. The thermal diffusivity was measured by thermal wave method with a signal detection based on mirage effect. The YAG crystals were doped with Yb or V, the YVO(4) with Nd or Ca and Tm, and the GdCOB crystals contained Nd or Yb. In all cases, the doping caused a decrease in thermal diffusivity. The analysis of complementary measurements of ultrasound velocity changes caused by dopants leads to the conclusion that impurities create phonon scattering centers. This additional scattering reduces the phonon mean free path and accordingly results in the decrease of the thermal diffusivity of the crystal. The influence of doping on lattice parameters was investigated, additionally.

Economic considerations related to choice of intraocular lens (IOL) and posterior capsule opacification frequency - a comparison of three different IOLs.

PubMed

Cullin, Felix; Busch, Tobias; Lundström, Mats

2014-03-01

To evaluate the posterior capsule opacification (PCO) rates in three different modern standard intraocular lenses (IOL) and analyse the related cost. Retrospective study of medical records from 1527 patients who underwent uneventful cataract surgery by phacoemulsification with posterior chamber implantation of either AcrySof SN60 (n = 375), Akreos Adapt (n = 350) or Tecnis Acryl IOL (n = 801). All surgeries were performed by the same surgeon using the same surgical technique and equipment. Primary end-point was neodymium:yttrium-aluminium-garnet (Nd:YAG) capsulotomy for visual impairment secondary to PCO. Cost of IOL material and Nd:YAG capsulotomy for PCO was then evaluated and compared between the IOLs. Mean follow-up was 41.5 months, and the only statistically significant variable of developing PCO was IOL type and individual follow-up time. Nd:YAG capsulotomy was performed in 7.47% in the AcrySof group, 17.71% in the Akreos group and 3.75% in the Tecnis group. Average cost for Nd:YAG capsulotomy per surgery was €18.75 in the AcrySof SN60 group, €44.25 in the Akreos Adapt group and €9.25 in the Tecnis Acryl group. The combined cost of cataract surgery and PCO treatment was €9.81 higher in for the Akreos Adapt group than the other two combined. This retrospective study shows that the risk of PCO and Nd:YAG capsulotomy is significantly higher in hydrophilic Akreos IOL compared with both AcrySof and Tecnis hydrophobic IOLs. The increased risk of PCO in the hydrophilic IOL is related to higher total average costs for cataract surgery. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

Development of 2024 AA-Yttrium composites by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Vidyasagar, CH S.; Karunakar, D. B.

2018-04-01

The method of fabrication of MMNCs is quite a challenge, which includes advanced processing techniques like Spark Plasma Sintering (SPS), etc. The objective of the present work is to fabricate aluminium based MMNCs with the addition of small amounts of yttrium using Spark Plasma Sintering and to evaluate their mechanical and microstructure properties. Samples of 2024 AA with yttrium ranging from 0.1% to 0.5 wt% are fabricated by Spark Plasma Sintering (SPS). Hardness of the samples is determined using Vickers hardness testing machine. The metallurgical characterization of the samples is evaluated by Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FE-SEM). Unreinforced 2024 AA sample is also fabricated as a benchmark to compare its properties with those of the composite developed. It is found that the yttrium addition increases the above mentioned properties by altering the precipitation kinetics and intermetallic formation to some extent and then decreases gradually when yttrium wt% increases beyond 0.3 wt%. High density (˂ 99.75) is achieved in the samples and highest hardness achieved is 114 Hv, fabricated by spark plasma sintering and uniform distribution of yttrium is observed.

Photoluminescence Characteristics of Yag:Ce, Gd Based Phosphors with Different Prehistories

NASA Astrophysics Data System (ADS)

Lisitsyn, V. M.; Soshchin, N. P.; Yang yang, Yu; Stepanov, S. A.; Lisitsyna, L. A.; Tulegenova, A. T.; Abdullin, Kh. A.

2017-09-01

Luminescence characteristics of yttrium-aluminum garnet based phosphor samples differed by their elemental composition and prehistory of synthesis are studied. The morphology, structure, and elemental composition of phosphor samples, their excitation and emission spectra, efficiency of phosphor conversion of chip emission, and kinetics of luminescence decay are measured. The emission characteristics of phosphors are compared with their structural properties and elemental composition.

Holmium:YAG laser lithotripsy: A dominant photothermal ablative mechanism with chemical decomposition of urinary calculi.

PubMed

Chan, K F; Vassar, G J; Pfefer, T J; Teichman, J M; Glickman, R D; Weintraub, S T; Welch, A J

1999-01-01

Evidence is presented that the fragmentation process of long-pulse Holmium:YAG (Ho:YAG) lithotripsy is governed by photothermal decomposition of the calculi rather than photomechanical or photoacoustical mechanisms as is widely thought. The clinical Ho:YAG laser lithotriptor (2.12 microm, 250 micros) operates in the free-running mode, producing pulse durations much longer than the time required for a sound wave to propagate beyond the optical penetration depth of this wavelength in water. Hence, it is unlikely that shock waves are produced during bubble formation. In addition, the vapor bubble induced by this laser is not spherical. Thus the magnitude of the pressure wave produced at cavitation collapse does not contribute significantly to lithotripsy. A fast-flash photography setup was used to capture the dynamics of urinary calculus fragmentation at various delay times following the onset of the Ho:YAG laser pulse. These images were concurrently correlated with pressure measurements obtained with a piezoelectric polyvinylidene-fluoride needle-hydrophone. Stone mass-loss measurements for ablation of urinary calculi (1) in air (dehydrated and hydrated) and in water, and (2) at pre-cooled and at room temperatures were compared. Chemical and composition analyses were performed on the ablation products of several types of Ho:YAG laser irradiated urinary calculi, including calcium oxalate monohydrate (COM), calcium hydrogen phosphate dihydrate (CHPD), magnesium ammonium phosphate hexahydrate (MAPH), cystine, and uric acid calculi. When the optical fiber was placed perpendicularly in contact with the surface of the target, fast-flash photography provided visual evidence that ablation occurred approximately 50 micros after the initiation of the Ho:YAG laser pulse (250-350 micros duration; 375-400 mJ per pulse), long before the collapse of the cavitation bubble. The measured peak acoustical pressure upon cavitation collapse was negligible (< 2 bars), indicating that

Synthesis, analysis and processing of novel materials in the yttrium oxide-aluminum oxide system

NASA Astrophysics Data System (ADS)

Marchal, Julien Claudius

In the current work, liquid feed flame spray pyrolysis (LF-FSP) was used to create three novel nanopowders in the Y2O3-Al 2O3 system: alpha-Al2O3, YAG (garnet Y3Al5O12) and hexagonal Y3Al 5O12. For example, LF-FSP combustion of metalloorganic yttrium and aluminum precursors in a 3/5 ratio forms hexagonal Y3Al5O 12, a newly discovered crystalline phase detailed in this work. The resulting 15-35 nm average particle size, single crystal nanopowders were characterized by TGA-DTA, XRD, HR-TEM, electron diffraction and FTIR. The data was used to establish a model for the crystal structure of this new phase (hexagonal, with crystal parameter of a = 0.736 nm, c = 1.052) consisting of a superlattice of substituted hexagonal YAlO3. YAG has been extensively investigated for its applications as scintillators, phosphors and as a laser host. Fully dispersible, unaggregated single crystal YAG nanopowders with average particle sizes of 35-50 nm were obtained from hexagonal Y3Al5O12 after annealing at 850°C-1200°C (for 2h-8d). The resulting YAG nanopowder was processed into green bodies using cold isostatic pressing after adding binders. 99%+ dense monoliths were obtained after sintering at 1400°C in vacuum (6-8 h), while maintaining grain sizes < 500 nm. The ability to sinter while keeping sub-micron grains differs from present techniques (where translucency is obtained through exaggerated grain growth to 5-10 microns) reported in the literature for sintering polycrystalline YAG, and is the first step for improving polycrystalline YAG laser host optical properties. LF-FSP processing of transition Al2O3 nanopowders converts them to single crystal alpha-Al2O3 nanopowders, previously thought impossible to obtain. The alpha-Al2O 3 nanopowders thus obtained, consist of unaggregated 30-40 nm single particles. These nanopowders were characterized by XRD, HR-TEM, SEM, DLS, FTIR. Green bodies of alpha-Al2O3 nanopowders were sintered to 99% density without sintering aids at 1400°C (6

Scintillation properties of the Ce-doped multicomponent garnet epitaxial films

NASA Astrophysics Data System (ADS)

Prusa, P.; Kucera, M.; Mares, J. A.; Hanus, M.; Beitlerova, A.; Onderisinova, Z.; Nikl, M.

2013-10-01

(Lu,Y,Gd)3(Al,Ga)5O12:Ce garnet scintillator single crystalline films were grown onto LuAG, YAG and GGG substrates by liquid phase epitaxy method. Absorption, radioluminescence spectra and photoluminescence excitation, emission spectra, and decay kinetics were measured. Photoelectron yield, its dependence on amplifier shaping time and energy resolution were determined to evaluate scintillation performance. Most of the samples exhibited strong UV emission caused by trapped excitons and/or Gd3+ 4f-4f transition. However, emission spectrum of the best performing Gd2YAl5O12:Ce is dominated by the Ce3+ fast 5d-4f luminescence. This sample has outperformed photoelectron yield of all the garnet films studied so far.

Weldability of Advanced High Strength Steels using Ytterbium:Yttrium Aluminium Garnet high power laser for Tailor-Welded Blank applications

NASA Astrophysics Data System (ADS)

Sharma, Rajashekhar Shivaram

Use of a high power Yb:YAG laser is investigated for joining advanced high strength steel materials for use in tailor-welded blank (TWB) applications. TWB's are materials of different chemistry, coating or thicknesses that are joined before metal forming and other operations such as trimming, assembly and painting are carried out. TWB is becoming an important design tool in the automotive industry for reducing weight, improving fuel economy and passenger safety, while reducing the overall costs for the customer. Three advanced high strength steels, TRIP780, DP980 and USIBOR, which have many unique properties that are conducive to achieving these objectives, along with mild steel, are used in this work. The objective of this work is to ensure that high quality welds can be obtained using Yb:YAG lasers which are also becoming popular for metal joining operations, since they produce high quality laser beams that suffer minimal distortion when transported via fiber optic cables. Various power levels and speeds for the laser beam were used during the investigation. Argon gas was consistently used for shielding purposes during the welding process. After the samples were welded, metallographic examination of the fusion and heat-affected zones using optical and scanning electron microscopes were carried out to determine the microstructures as well as weld defects. Optical and scanning electron microscopes were also used to examine the top of welds as well as fracture surfaces. Additionally, cross-weld microhardness evaluations, tensile tests using Instron tester, limited fatigue tests as well as formability evaluations using OSU plane strain evaluation were carried out. The examinations included a 2-factor full factorial design of experiments to determine the impact of coatings on the surface roughness on the top of the welds. Tensile strengths of DP980, TRIP780 and mild steel materials as well as DP980 welded to TRIP780 and mild steel in the rolling direction as well as

Efficacy of ablative fractional laser-assisted photodynamic therapy for the treatment of actinic cheilitis: 12-month follow-up results of a prospective, randomized, comparative trial.

PubMed

Choi, S H; Kim, K H; Song, K-H

2015-07-01

Early identification and treatment of actinic cheilitis (AC) is recommended. Although photodynamic therapy (PDT) is an attractive therapeutic option for AC, PDT for AC does not result in the same satisfactory outcomes as in actinic keratosis (AK). The aim of our study was to compare efficacy, recurrence rate, cosmetic outcome and safety between erbium:yttrium-aluminium-garnet ablative fractional laser-assisted methyl aminolaevulinate-PDT (Er:YAG AFL MAL-PDT) and standard MAL-PDT. Thirty-three patients with histologically confirmed AC randomly received either one session of Er:YAG AFL MAL-PDT or two sessions of MAL-PDT. In the MAL-PDT group, the second session of MAL-PDT was administered 7 days later. Patients were followed up at 1 week and 3 and 12 months, and biopsies were taken from all patients at 3 and 12 months after the last treatment session. At the final 12-month follow-up, cosmetic outcomes were assessed. Adverse events were assessed at week 1 of the treatment phase and every subsequent follow-up visit. In the per-protocol (PP) population, Er:YAG AFL MAL-PDT was significantly more effective (92% complete response rate) than MAL-PDT (59%; P = 0.040) at the 3-month follow-up, and differences in efficacy remained significant at the 12-month follow-up (85% in Er:YAG AFL MAL-PDT and 29% in MAL-PDT). The recurrence rate was significantly lower for Er:YAG AFL MAL-PDT (8%) than for MAL-PDT (50%) group at 12 months (P = 0.029). No significant difference in cosmetic outcome or safety was observed between Er:YAG AFL MAL-PDT and MAL-PDT. Ablative fractional laser pretreatment has significant benefit for the treatment of AC with PDT. © 2014 British Association of Dermatologists.

Evaluation of different types of enamel conditioning before application of a fissure sealant.

PubMed

Ciucchi, Philip; Neuhaus, Klaus W; Emerich, Marta; Peutzfeldt, Anne; Lussi, Adrian

2015-01-01

The aim of the study was to compare fissure sealant quality after mechanical conditioning of erbium-doped yttrium aluminium garnet (Er:YAG) laser or air abrasion prior to chemical conditioning of phosphoric acid etching or of a self-etch adhesive. Twenty-five permanent molars were initially divided into three groups: control group (n = 5), phosphoric acid etching; test group 1 (n = 10), air abrasion; and test group 2, (n = 10) Er:YAG laser. After mechanical conditioning, the test group teeth were sectioned buccolingually and the occlusal surface of one half tooth (equal to one sample) was acid etched, while a self-etch adhesive was applied on the other half. The fissure system of each sample was sealed, thermo-cycled and immersed in 5% methylene dye for 24 h. Each sample was sectioned buccolingually, and one slice was analysed microscopically. Using specialized software microleakage, unfilled margin, sealant failure and unfilled area proportions were calculated. A nonparametric ANOVA model was applied to compare the Er:YAG treatment with that of air abrasion and the self-etch adhesive with phosphoric acid (α = 0.05). Test groups were compared to the control group using Wilcoxon rank sum tests (α = 0.05). The control group displayed significantly lower microleakage but higher unfilled area proportions than the Er:YAG laser + self-etch adhesive group and displayed significantly higher unfilled margin and unfilled area proportions than the air-abrasion + self-etch adhesive group. There was no statistically significant difference in the quality of sealants applied in fissures treated with either Er:YAG laser or air abrasion prior to phosphoric acid etching, nor in the quality of sealants applied in fissures treated with either self-etch adhesive or phosphoric acid following Er:YAG or air-abrasion treatment.

Treatment of patients with OSAS using Nd-YAG laser

NASA Astrophysics Data System (ADS)

Kukwa, Andrzej; Tulibacki, Marek P.; Zajac, Andrzej; Dudziec, Katarzyna

2000-06-01

The authors present their clinical experience regarding the possibilities of application of Nd:YAG and Ho:YAG lasers for the treatment of disorders in the are of the upper respiratory tract. The patients with symptoms of Obstructive Sleep Aphnoe Syndrom need a various operations techniques. Lasers techniques makes it possible to perform a number of procedures in local anesthesia which considerably improves the economic effectiveness of the treatment. The surgeries performed using laser beam enabled very good effect of treatment.

Assessment of microleakage of class V restored by resin composite and resin-modified glass ionomer and pit and fissure resin-based sealants following Er:YAG laser conditioning and acid etching: in vitro study

PubMed Central

Luong, Emilie; Shayegan, Amir

2018-01-01

Aim The aim of this study was to make a comparison between microleakage of conventionally restored class V cavities using acid etchant and the ones conditioned by erbium-doped yttrium aluminum garnet (Er:YAG) laser, and also to assess and compare the effectiveness of enamel surface treatments of occlusal pits and fissures by acid etching and conditioned by Er:YAG laser-etch. Materials and methods Seventy-two extracted third molars were used in this study. The samples were divided into two major groups: class V cavities and pit and fissure sealants. Each subgroup was divided into conventional acid etching, Er:YAG laser conditioning and conventional acid etching, and combination with Er:YAG laser conditioning (n=12). The teeth were placed in 2% methylene blue dye solution, were sectioned, and were evaluated according to the dye penetration criteria. Two samples per subgroup were chosen for scanning electron microscopic (SEM) analysis. Results There was a significant difference between occlusal and cervical margin groups. Laser conventional composite cementum group showed more microleakage values compared to other groups. There was no significant difference between occlusal margin groups. However, there was a significant difference between cervical margin groups in terms of microleakage. In sealant groups, there was a significant difference between laser and conventional with/without laser treatment groups in terms of microleakage. Conclusion Based on the results reported in this study, it can be concluded that the application of the Er:YAG laser beneath the resin composite, the resin-modified glass ionomers (GIs), and the fissure sealant placement may be an alternative enamel and dentin etching method to acid etching. PMID:29881311

High energy resolution with transparent ceramic garnet scintillators

NASA Astrophysics Data System (ADS)

Cherepy, N. J.; Seeley, Z. M.; Payne, S. A.; Beck, P. R.; Swanberg, E. L.; Hunter, S.; Ahle, L.; Fisher, S. E.; Melcher, C.; Wei, H.; Stefanik, T.; Chung, Y.-S.; Kindem, J.

2014-09-01

Breakthrough energy resolution, R(662keV) < 4%, has been achieved with an oxide scintillator, Cerium-doped Gadolinium Yttrium Gallium Aluminum Garnet, or GYGAG(Ce). Transparent ceramic GYGAG(Ce), has a peak emission wavelength of 550 nm that is better matched to Silicon photodetectors than to standard PMTs. We are therefore developing a spectrometer based on pixelated GYGAG(Ce) on a Silicon photodiode array that can provide R(662 keV) = 3.6%. In comparison, with large 1-2 in3 size GYGAG(Ce) ceramics we obtain R(662 keV) = 4.6% with PMT readout. We find that ceramic GYGAG(Ce) of a given stoichiometric chemical composition can exhibit very different scintillation properties, depending on sintering conditions and post-anneal treatments. Among the characteristics of transparent ceramic garnet scintillators that can be controlled by fabrication conditions are: scintillation decay components and their amplitudes, intensity and duration of afterglow, thermoluminescence glow curve peak positions and amplitudes, integrated light yield, light yield non-proportionality - as measured in the Scintillator Light Yield Non-Proportionality Characterization Instrument (SLYNCI), and energy resolution for gamma spectroscopy. Garnet samples exhibiting a significant fraction of Cerium dopant in the tetravalent valence also exhibit: faster overall scintillation decay, very low afterglow, high light yield, but poor light yield proportionality and degraded energy resolution.

A compound crystal with film scintillator for electron detection

NASA Astrophysics Data System (ADS)

McKinney, George; McDonnald, Warren; Tzolov, Marian

2015-03-01

Yttrium Aluminum Garnets (YAG) and Yttrium Aluminum Perovskite (YAP) are widely used as electron detectors. This application requires a top conducting layer which hinders their application at low electron energies. We have developed a layer of zinc tungstate which delivers conductivity large enough to prevent charging while still being an efficient scintillator. For better coupling between the two systems we have studied their optical properties. Ce doping is an essential element in YAP and YAG in order for them to be efficient scintillators. We have studied the Ce content and we show that higher Ce content leads to reabsorption in the YAP scintillators. These details were revealed by using photoluminescence emission and excitation spectroscopy. The absorption spectrum for the YAG scintillators coincides with the excitation for the main emission lines. The optical studies of the zinc tungstate films and a single crystal have shown that the films are more efficient light emitters. We have integrated the zinc tungstate films with YAG scintillators and we will report on the performance of this compound scintillator. It is expected that it will perform well at low and high electron energies, which makes it a very cost effective platform for electron detectors.

Stress induced modulation of magnetic domain diffraction of single crystalline yttrium iron garnet

NASA Astrophysics Data System (ADS)

Mito, Shinichiro; Yoshihara, Yuki; Takagi, Hiroyuki; Inoue, Mitsuteru

2018-05-01

Stress induced modulation of the diffraction angle and efficiency of the light reflected from a stripe-domain magnetic garnet was demonstrated. The spacing of the magnetic domain was changed using the inverse magnetostriction effect. The sample structure was a piezo actuator/Al reflection layer/magnetic garnet substrate. A diffraction angle between the 0th and 1st ordered light was changed from 9.12 deg. to 10.20 deg. This result indicates that the domain spacing was changed from 3.3 μm to 3.0 μm. The change of the diffraction angle was irreversible for the voltage. However, reversible, linear and continuous change of the diffraction efficiency was observed. These results could be applicable for a voltage-driven optical solid state light deflector with low power consumption and high switching speed.

Characterisation of debris from laser and mechanical cutting of bone.

PubMed

Rachmanis, Nikolaos; McGuinness, Garrett B; McGeough, Joseph A

2014-07-01

Laser cutting of bones has been proposed as a technology in orthopaedic surgery. In this short study, the laser-bone interaction was examined using a pulsed erbium-doped yttrium aluminium garnet laser and compared to a conventional cutting technique. Microscopic analysis revealed the nature of waste debris and showed higher proportions of finer particles for conventional sagittal sawing compared to laser cutting. © IMechE 2014.

Fractional laser skin resurfacing.

PubMed

Alexiades-Armenakas, Macrene R; Dover, Jeffrey S; Arndt, Kenneth A

2012-11-01

Laser skin resurfacing (LSR) has evolved over the past 2 decades from traditional ablative to fractional nonablative and fractional ablative resurfacing. Traditional ablative LSR was highly effective in reducing rhytides, photoaging, and acne scarring but was associated with significant side effects and complications. In contrast, nonablative LSR was very safe but failed to deliver consistent clinical improvement. Fractional LSR has achieved the middle ground; it combined the efficacy of traditional LSR with the safety of nonablative modalities. The first fractional laser was a nonablative erbium-doped yttrium aluminum garnet (Er:YAG) laser that produced microscopic columns of thermal injury in the epidermis and upper dermis. Heralding an entirely new concept of laser energy delivery, it delivered the laser beam in microarrays. It resulted in microscopic columns of treated tissue and intervening areas of untreated skin, which yielded rapid reepithelialization. Fractional delivery was quickly applied to ablative wavelengths such as carbon dioxide, Er:YAG, and yttrium scandium gallium garnet (2,790 nm), providing more significant clinical outcomes. Adjustable laser parameters, including power, pitch, dwell time, and spot density, allowed for precise determination of percent surface area, affected penetration depth, and clinical recovery time and efficacy. Fractional LSR has been a significant advance to the laser field, striking the balance between safety and efficacy.

Electric field tuning of magnetism in heterostructure of yttrium iron garnet film/lead magnesium niobate-lead zirconate titanate ceramic

NASA Astrophysics Data System (ADS)

Lian, Jianyun; Ponchel, Freddy; Tiercelin, Nicolas; Chen, Ying; Rémiens, Denis; Lasri, Tuami; Wang, Genshui; Pernod, Philippe; Zhang, Wenbin; Dong, Xianlin

2018-04-01

In this paper, the converse magnetoelectric (CME) effect by electric field tuning of magnetization in an original heterostructure composed of a polycrystalline yttrium iron garnet (YIG) film and a lead magnesium niobate-lead zirconate titanate (PMN-PZT) ceramic is presented. The magnetic performances of the YIG films with different thicknesses under a DC electric field applied to the PMN-PZT ceramics and a bias magnetic field are investigated. All the magnetization-electric field curves are found to be in good agreement with the butterfly like strain curve of the PMN-PZT ceramic. Both the sharp deformation of about 2.5‰ of PMN-PZT and the easy magnetization switching of YIG are proposed to be the reasons for the strongest CME interaction in the composite at the small electric coercive field of PMN-PZT (4.1 kV/cm) and the small magnetic coercive field of YIG (20 Oe) where the magnetic susceptibility reaches its maximum value. A remarkable CME coefficient of 3.1 × 10-7 s/m is obtained in the system with a 600 nm-thick YIG film. This heterostructure combining multiferroics and partially magnetized ferrite concepts is able to operate under a small or even in the absence of an external bias magnetic field and is more compact and power efficient than the traditional magnetoelectric devices.

Development of Scintillators in Nuclear Medicine.

PubMed

Khoshakhlagh, Mohammad; Islamian, Jalil Pirayesh; Abedi, Seyed Mohammad; Mahmoudian, Babak

2015-01-01

High-quality image is necessary for accurate diagnosis in nuclear medicine. There are many factors in creating a good image and detector is the most important one. In recent years, several detectors are studied to get a better picture. The aim of this paper is comparison of some type of these detectors such as thallium activated sodium iodide bismuth germinate cesium activated yttrium aluminum garnet (YAG: Ce) YAP: Ce "lutetium aluminum garnet activated by cerium" CRY018 "CRY019" lanthanum bromide and cadmium zinc telluride. We studied different properties of these crystals including density, energy resolution and decay times that are more important factors affecting the image quality.

Influence of Er:YAG and Ti:sapphire laser irradiation on the microtensile bond strength of several adhesives to dentin.

PubMed

Portillo, M; Lorenzo, M C; Moreno, P; García, A; Montero, J; Ceballos, L; Fuentes, M V; Albaladejo, A

2015-02-01

The aim of the present study was to evaluate the influence of erbium:yttrium-aluminum-garnet (Er:YAG) and Ti:sapphire laser irradiation on the microtensile bond strength (MTBS) of three different adhesive systems to dentin. Flat dentin surfaces from 27 molars were divided into three groups according to laser irradiation: control, Er:YAG (2,940 nm, 100 μs, 2.7 W, 9 Hz) and Ti:sapphire laser (795 nm, 120 fs, 1 W, 1 kHz). Each group was divided into three subgroups according to the adhesive system used: two-step total-etching adhesive (Adper Scotchbond 1 XT, from now on XT), two-step self-etching adhesive (Clearfil SE Bond, from now on CSE), and all-in-one self-etching adhesive (Optibond All-in-One, from now on OAO). After 24 h of water storage, beams of section at 1 mm(2) were longitudinally cut from the samples. Each beam underwent traction test in an Instron machine. Fifteen polished dentin specimens were used for the surface morphology analysis by scanning electron microscopy (SEM). Failure modes of representative debonded microbars were SEM-assessed. Data were analyzed by ANOVA, chi-square test, and multiple linear regression (p < 0.05). In the control group, XT obtained higher MTBS than that of laser groups that performed equally. CSE showed higher MTBS without laser than that with laser groups, where Er:YAG attained higher MTBS than ultrashort laser. When OAO was used, MTBS values were equal in the three treatments. CSE obtained the highest MTBS regardless of the surface treatment applied. The Er:YAG and ultrashort laser irradiation reduce the bonding effectiveness when a two-step total-etching adhesive or a two-step self-etching adhesive are used and do not affect their effectiveness when an all-in-one self-etching adhesive is applied.

Ablative non-fractional lasers for atrophic facial acne scars: a new modality of erbium:YAG laser resurfacing in Asians.

PubMed

Lee, Sang Ju; Kang, Jin Moon; Chung, Won Soon; Kim, Young Koo; Kim, Hei Sung

2014-03-01

Atrophic facial scars which commonly occur after inflammatory acne vulgaris can be extremely disturbing to patients both physically and psychologically. Treatment with fractional laser devices has become increasingly popular, but there has been disappointment in terms of effectiveness. The objective of this study was to assess the safety and efficacy of ablative full-face resurfacing on atrophic acne scars in the Korean population. A total of 22 patients, aged 25-44 years, underwent a new modality of resurfacing combining both short-pulsed and dual-mode erbium:yttrium-aluminum garnet (Er:YAG) laser. The patients had Fitzpatrick skin types ranging from III to V. Photographs were taken before and up to 6 months after treatment. Results were evaluated for the degree of clinical improvement and any adverse events. Degree of improvement was graded using a four-point scale: poor (1) = <25%, fair (2) = 25-50%, good (3) = 51-75%, and excellent (4) = >75%. Based on the blinded photo assessments by two independent reviewers, clinically and statistically significant mean improvement of 3.41 was observed (one-sample Wilcoxon signed rank test, P < 0.001). Complete wound healing occurred between 6 and 9 days. Erythema occurred in all patients and lasted longer than 3 months in two patients (9.1%). Postinflammatory hyperpigmentation occurred in ten patients (45.5%) and lasted longer than 3 months in one patient (4.5%). One patient experienced mild hypopigmentation (4.5%). Mild to moderate acne flare-up occurred in five patients (22.7%). No other adverse effects were observed. A new modality of Er:YAG laser resurfacing combining short-pulsed and dual-mode Er:YAG laser is a safe and very effective treatment modality for atrophic facial acne scars in Asians with darker skin tones.

Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

PubMed

Maeda, Y

1994-08-10

An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

Semiconductor Laser Diode Arrays by MOCVD (Metalorganic Chemical Vapor Deposition)

DTIC Science & Technology

1987-09-01

laser diode arrays are intended to be used as an optical pump for solid state yttrium aluminum garnet (YAG) lasers. In particular, linear uniform...corresponds to about . , 8080A. Such thin layer structures, while difficult to grow by such conventional growth methods as liquid phase epitaxy ( LPE ...lower yet than for DH lasers grown by LPE . , - Conventional self-aligned stripe laser This structure is formed by growing (on an n-type GaAs substrate

Power Systems and Energy Storage Modeling for Directed Energy Weapons

DTIC Science & Technology

2014-06-01

neodymium or ytterbium doped yttrium aluminum garnet (YAG) crystal.6 The Maritime Laser Demonstration (MLD) features several 15 kW slab lasers combined...The laser substrate is similar to a fiber optic cable that is doped with a rare earth element (typically neodymium or ytterbium); many fibers can be...but with different elements. A typical construction consists of a sheet of Lithium- cobalt -oxide and a sheet of carbon separated by an insulator

A preclinical study testing "Focused multiple laser beams," a new concept of irradiation with the 1064-nm Nd:YAG laser for skin rejuvenation.

PubMed

Horiguchi, Masatoshi; Miyata, Nariaki; Mizuno, Hiroshi

2017-04-01

In order to avoid epidermal heat damage, we developed a novel irradiation method termed "Focused multiple laser beams (FMLB)," which allows long-pulse neodymium:yttrium aluminum garnet (Nd:YAG) laser beams to be irradiated from several directions in a concentric fashion followed by focusing into the dermis without epidermal damage. This study aimed to assess whether FMLB achieves the desired dermal improvement without epidermal damage. The dorsal skin of New Zealand White rabbits was irradiated with FMLB. Macroscopic and histological analyses were performed after 1 hour and 1, 2, 3 and 4 weeks. Real-time PCR analysis of type I and III collagen expression was performed at two and four weeks. Control groups exhibited skin ulcers which were healed with scar formation whereas FMLB groups remained intact macroscopically. Histologically, FMLB group showed increase in dermal thickness at four weeks while the epidermis remained intact. Real-time PCR demonstrated that both type I and III collagen increased at two weeks but decreased at four weeks. FMLB can deliver the target laser energy to the dermis without significantly affecting the epidermis.

Kyanite-garnet gneisses of the Kåfjord Nappe - North Norwegian Caledonides: P-T conditions and monazite Th-U-Pb dating

NASA Astrophysics Data System (ADS)

Ziemniak, Grzegorz; Kośmińska, Karolina; Majka, Jarosław; Janák, Marian; Manecki, Maciej

2016-04-01

The Kåfjord Nappe is the part of the Skibotn Nappe Complex traditionally ascribed to the Upper Allochthon of the North Norwegian Caledonides. Pressure-temperature (P-T) conditions and metamorphic age of the Kåfjord Nappe are not well constrained, geochronological data are limited to a single Rb-Sr age of c. 440 Ma (Dangla et al. 1978). Metamorphic evolution of kyanite-garnet gneisses of the Kåfjord Nappe is presented here. The kyanite-garnet gneisses are associated with a few meters thick amphibolite lenses. The gneisses mainly consist of quartz, plagioclase, biotite, muscovite, garnet, kyanite, and rutile. Retrograde minerals are represented by sillimanite and chlorite. Garnet occurs as two textural types. Garnet-I forms euhedral porphyroblasts with multiple small inclusions. Profiles through garnet-I show chemical zonation in all components. The composition varies from Alm64-68Prp11-16Grs13-18Sps2-8 in the core to Alm68-70Prp17-18Grs10-13Sps1-3 in the rim. Garnet-II is subhedral to anhedral, its core is inclusion-rich, whereas rim contains only single inclusions. Chemical composition of garnet-II is similar to that of the garnet-I rim. P-T conditions have been estimated using the garnet-biotite-muscovite-plagioclase (GBPM) geothermobarometer (Holdaway, 2001; Wu, 2014). Calculated peak P-T metamorphic conditions are 610-625 °C and 7.6-8.2 kbar corresponding to the amphibolite facies conditions. Phase equilibrium modelling in the NCKFMMnASH system yields peak metamorphic conditions of c. 620 °C at 8 kbar. Growth conditions of garnet-I core modelled in the NCKFMMnASH system are c. 570 °C at 9.7 kbar. Chemical Th-U-total Pb monazite dating has been performed. Preliminary dating results from the kyanite-garnet gneiss of the Kåfjord Nappe yield an array of dates from 468 Ma to 404 Ma. There is a correlation between an increase of yttrium content and decrease of monazite single dates. Compositional maps confirm an increase of yttrium towards the rim of the

Effect of Nd: YAG laser on the apical seal after root-end resection and MTA retrofill: a bacterial leakage study.

PubMed

Birang, Reza; Kiani, Sepideh; Shokraneh, Ali; Hasheminia, Seyed Mohsen

2015-02-01

Laser irradiation has been investigated in terms of preventing leakage in retrofilled root canals. The aim of the present study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the bacterial leakage of mineral trioxide aggregate (MTA)-retrofilled roots. In this ex vivo experimental study, 90 single-rooted incisor teeth were filled with gutta-percha and AH26 sealer. The apical 3 mm of all the roots were resected and 3-mm retrocavities were prepared by an ultrasonic device. The specimens were randomly divided into two experimental (n = 25), one positive control (n = 10), and two negative control (n = 10) groups. In the laser + MTA group, the cavity walls were irradiated by Nd: YAG laser prior to MTA placement. In the MTA group, MTA was placed without laser irradiation. The root surfaces were covered with two layers of nail varnish except for the apical 2 mm. The specimens were then embedded in a bacterial leakage test system and examined daily for 90 days. Contamination periods were recorded. Data were analyzed by Kaplan-Meier and Mann-Whitney U tests (α = 0.05). Five teeth with and five teeth without laser irradiation underwent scanning electron microscopic evaluation. The specimens in the laser + MTA group were contaminated earlier than those in the MTA group (p < 0.05). Comparison of survival times between the two groups showed significant differences (p < 0.05). Nd: YAG laser irradiation can decrease the sealing capacity of MTA in comparison to the apical seal achieved by MTA without laser irradiation. Further studies are recommended to provide a better seal for the MTA-retrofilled teeth after laser irradiation.

Threshold Damage of In vivo Porcine Skin at 2000 nm Laser Irradiation

DTIC Science & Technology

2006-01-01

surgery. J Clin Laser Med Surg 1992; 10:211-216. 8. Shapshay SM, Rebeiz EE, Pankratov MM. Holmium: Yttrium Aluminium Garnet laser-assisted endoscopic...laser-assisted endoscopic sinus surgery: laboratory experience. Laryngoscope 1991 ; 101:142-149. 10. Min K, Leu H, Zweifel K. Quantitative determination...JTF. Choice of clip levels for beam width measurements using knife-edge techniques. IEEE J. Quantum Electron. 1991 ; 27:1098-1104 19. Finney DJ

Scintillating Screens Based on the Single Crystalline Films of Multicomponent Garnets: New Achievements and Possibilities

NASA Astrophysics Data System (ADS)

Zorenko, Yuriy; Gorbenko, Vitalii; Zorenko, Tetiana; Paprocki, Kazimierz; Nikl, Martin; Mares, Jiri A.; Bilski, Pawel; Twardak, Anna; Sidletskiy, Oleg; Gerasymov, Iaroslav; Grinyov, Boris; Fedorov, Alexandr

2016-04-01

The paper is dedicated to development of the novel scintillating screens based on single crystalline films (SCF) of Ce doped Lu3 - xTbxAl5 - yGayO12 multicomponent garnets at x = 2 - 3 and y = 0 - 2.5 onto Y3Al5O12 (YAG) and Gd3Al2.5Ga2.5O12 (GAGG) substrates using the liquid phase epitaxy (LPE) method. We report the optimized content and high scintillation figure of merit of SCF of these garnets grown by the LPE method with using PbO based flux. Namely, the Tb3Al2.5Ga2.5O12:Ce SCFs possess the highest values of light yield (LY) compared to all earlier investigated SCF samples, with their LY exceeding by 2.35 and 1.15 times the LY values for YAG:Ce and LuAG:Ce SCF scintillators, respectively. The SCFs of the mentioned compounds show very lower thermoluminescence in the above room temperature range and relatively fast scintillation decay.

A pilot study to determine medical laser generated air contaminant emission rates for a simulated surgical procedure.

PubMed

Lippert, Julia F; Lacey, Steven E; Lopez, Ramon; Franke, John; Conroy, Lorraine; Breskey, John; Esmen, Nurtan; Liu, Li

2014-01-01

The U.S. Occupational Safety and Health Administration (OSHA) estimates that half a million health-care workers are exposed to laser surgical smoke each year. The purpose of this study was to establish a methodology to (1) estimate emission rates of laser-generated air contaminants (LGACs) using an emission chamber, and to (2) perform a screening study to differentiate the effects of three laser operational parameters. An emission chamber was designed, fabricated, and assessed for performance to estimate the emission rates of gases and particles associated with LGACs during a simulated surgical procedure. Two medical lasers (Holmium Yttrium Aluminum Garnet [Ho:YAG] and carbon dioxide [CO2]) were set to a range of plausible medical laser operational parameters in a simulated surgery to pyrolyze porcine skin generating plume in the emission chamber. Power, pulse repetition frequency (PRF), and beam diameter were evaluated to determine the effect of each operational parameter on emission rate using a fractional factorial design. The plume was sampled for particulate matter and seven gas phase combustion byproduct contaminants (benzene, ethylbenzene, toluene, formaldehyde, hydrogen cyanide, carbon dioxide, and carbon monoxide): the gas phase emission results are presented here. Most of the measured concentrations of gas phase contaminants were below their limit of detection (LOD), but detectable measurements enabled us to determine laser operation parameter influence on CO2 emissions. Confined to the experimental conditions of this screening study, results indicated that beam diameter was statistically significantly influential and power was marginally statistically significant to emission rates of CO2 when using the Ho:YAG laser but not with the carbon dioxide laser; PRF was not influential vis-a-vis emission rates of these gas phase contaminants.

Preliminary panoramic study of river calm muscle using neodymium:yttrium-aluminum-garnet (Nd: YAG) laser-induced breakdown spectroscopy (LIBS)

NASA Astrophysics Data System (ADS)

Idris, N.; Lahna, K.; Usmawanda, T. N.; Herman; Ramli, M.; Hedwig, R.; Marpaung, A. M.; Kurniawan, K. H.

2018-04-01

A wide coverage spectral investigation on the muscle of river calm sample has been carried out using laser-induced breakdown spectroscopy for examining the overall profile of the emission spectra from the produced plasma. The basic apparatus of LIBS system used is a Nd-YAG laser and wide coverage optical multichannel analyzer (OMA) system. The river clam samples used is collected from Panga River in Aceh Jaya Regency, Aceh, Indonesia up streaming in a mountain of Gunong Ujeun, which is used as a location of the intensive traditional mining activity. Assuming that heavy metal accumulated in the clam muscle, LIBS experiments were carried out on the muscle of the calm. The sample used was fresh muscle sliced and attached to a copper plate. Plasma was generated by focusing the laser beam on the sample surface under air surrounding gas at 1 atmosphere. It is found that there are only major elements of host organic, namely C, H, O, N and the minor element of salts can be detected from fresh the clam sample when using a high pulse laser energy under air surrounding at high pressure of 1 atmosphere. There is no emission lines from any metal can be detected. Several experimental parameters were explored to study the panoramic dynamic of the emission spectra. It is found that the lower energy and the lower pressure is better for obtaining better emission spectra showing the possibility for determination of the analyte.

Acute and chronic response of articular cartilage to Ho:YAG laser irradiation

NASA Astrophysics Data System (ADS)

Trauner, Kenneth B.; Nishioka, Norman S.; Flotte, Thomas J.; Patel, Dinesh K.

1992-06-01

A Ho:YAG laser system operating at a wavelength of 2.1 microns has recently been introduced for use in arthroscopic surgery. The acceptability of this new tool will be determined not only by its ability to resect tissue, but also by its long term effects on articular surfaces. In order to investigate these issues further, we performed two studies to evaluate the acute and chronic effects of the laser on cartilaginous tissue. We evaluated the acute, in vitro effects of 2.1 micron laser irradiation on articular and fibrocartilage. This included the measurement of ablation efficiency, ablation threshold and thermal damage in both meniscus and articular cartilage. To document the chronic effects on articular cartilage in vivo, we next performed a ten week healing study. Eight sheep weighing 30 - 40 kg underwent bilateral arthrotomy procedures. Multiple full thickness and partial thickness defects were created. Animals were sacrificed at 0, 2, 4, and 10 weeks. The healing study demonstrated: (1) no healing of full or partial thickness defects at 10 weeks with hyaline cartilage; (2) fibrocartilaginous granulation tissue filling full thickness defects at two and four weeks, but no longer evident at ten weeks; (3) chondrocyte necrosis extending to greater than 900 microns distal to ablation craters at four weeks with no evidence of repair at later dates; and (4) chondrocyte hyperplasia at the borders of the damage zone at two weeks but no longer evident at later sacrifice dates.

Computational modelling of Er(3+): Garnet laser materials

NASA Technical Reports Server (NTRS)

Spangler, Lee H.

1994-01-01

The Er(3+) ion has attracted a lot of interest for four reasons: (1) Its (4)I(sub 13/2) yields (4)I(sub 15/2) transition lases in the eyesafe region near 1.5 micron; (2) the (4)I(sub 13/2) transition lases near 2.8 micron, an important wavelength for surgical purposes; (3) it displays surprisingly efficient upconversion with lasing observed at 1.7, 1.2, 0.85, 0.56, 0.55, and 0.47 micron following 1.5 micron pumping; and (4) it has absorption bands at 0.96 and 0.81 micron and thus can be diode pumped. However, properties desirable for upconversion reduce the efficiency of 1.5 and 3 micron laser operation and vice versa. Since all of the processes are influenced by the host via the crystal field induced stark splittings in the Er levels, this project undertook modelling of the host influence on the Er lasinng behavior. While growth and measurement of all ten Er(3+) doped garnets is the surest way of identifying hosts which maximize upconversion (or conversly, 1.5 and 3 micron performance), it is also expensive - costing approximately $10,000/material or approximately $100,000 for the materials computationally investigated here. The calculations were performed using a quantum mechanical point charge model developed by Clyde Morrison at Harry Diamond Laboratories. The programs were used to fit the Er:YAG experimental energy levels so that the crystal field parameters, B(sub nm) could be extracted. From these radial factors, rho (sub n) were determined for Er(3+) in garnets. These, in combination with crystal field components, Anm, available from X-ray data, were used to predict energy levels for Er in the other nine garnet hosts. The levels in Er:YAG were fit with an rms error of 12.2/cm over a 22,000/cm range. Predicted levels for two other garnets for which literature values were available had rms errors of less than 17/cm , showing the calculations to be reliable. Based on resonances between pairs of calculated stark levels, the model predicts GSGG as the best host

Evaluation of surface topography of zirconia ceramic after Er:YAG laser etching.

PubMed

Turp, Volkan; Akgungor, Gokhan; Sen, Deniz; Tuncelli, Betul

2014-10-01

The aim of this study is to evaluate the effect of Erbium: yttrium-aluminum-garnet (Er:YAG) laser with different pulse lengths on the surface roughness of zirconia ceramic and airborne particle abrasion. Er:YAG laser treatment is expected to be an alternative surface treatment method for zirconia ceramics; however, the parameters and success of the application are not clear. One hundred and forty zirconia discs (diameter, 10 mm; thickness, 1.2 mm) were prepared by a computer-aided design and computer-aided manufacturing (CAD/CAM) system according to the manufacturer's instructions. Specimens were divided into 14 groups (n=10). One group was left as polished control, one group was air-particle abraded with Al2O3 particles. For the laser treatment groups, laser irradiation was applied at three different pulse energy levels (100, 200, and 300 mJ) and for each energy level at four different pulse lengths; 50, 100, 300, and 600 μs. Surface roughness was evaluated with an optical profilometer and specimens were evaluated with scanning electron microscopy (SEM). Data was analyzed with one way ANOVA and Tukey multiple comparison tests (α=0.05). For the 100 and 200 mJ laser etching groups, 50 and 100 μs laser duration resulted in significantly higher surface roughness compared with air-particle abrasion (p<0.05). The difference among Ra values of 300 μs, 600 μs, and air-particle abrasion groups were not statistically significant (p>0.05). For the 300 mJ laser etching groups; there was no statistically significant difference among the Ra values of 50 μs, 100 μs, 300 μs, 600 μs, and air-particle abrasion groups (p>0.05). In order to increase surface roughness and promote better bonding to resin luting agents, Er:YAG laser etching may be an alternative to air-particle abrasion for zirconia ceramics. However, high levels of pulse energy and longer pulse length may have an adverse effect on micromechanical locking properties, because of a

Management of a Recurrent Pyogenic Granuloma of the Hard Palate with Diode Laser: A Case Report.

PubMed

Hasanoglu Erbasar, Güzin Neda; Senguven, Burcu; Gultekin, Sibel Elif; Cetiner, Sedat

2016-01-01

Pyogenic granuloma (PG) is a prevalent inflammatory hyperplasia of skin and oral mucosa which is often caused by constant low-grade local irritation, traumatic injury or hormonal factors. In many cases, gingival irritation and inflammation due to poor oral hygiene are precipitating factors. Oral PG occurs predominantly on the gingiva, but it is also encountered on the lips, tongue, buccal mucosa and rarely on the hard palate. Although surgical excision is the first choice of treatment, many other treatment modalities could be counted such as cryosurgery, sodium tetradecyl sulfate sclerotherapy, intralesional steroids, flash lamp pulsed dye laser, neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, carbon dioxide (CO2) laser, erbium-doped yttrium aluminum garnet (Er:YAG) lasers and diode laser have been suggested. After surgical excision recurrence occurs up to 16% of these lesions. It is believed that recurrence ensues as a result of incomplete excision, failure to eliminate etiologic factors or repeated trauma. A 50-year-old female was referred to the Department of Oral Surgery, Gazi University, School of Dentistry, complaining of a swelling and growth on the right side of the hard palate for four months. Patient reported a similar growth in the same area about two years earlier, which had turned out to be a PG by histopathology. The treatment plan included surgical excision of the lesion using diode laser. The patient reported no pain after the surgery. She was discharged with a prescription of chlorhexidine mouthwash and necessary post-operative instructions. At 7 days follow up visit, immediate recurrence of the lesion was observed, and it was excised by diode laser with 2 mm margins at its clinical periphery, to a depth up to the periosteum, by the same operator. No recurrence or scarring was observed in 14 months follow-up. Although diode laser is a secure and efficient technique for the treatment of intraoral PG, in order to minimize its recurrence, the

Application of reflectance confocal microscopy to evaluate skin damage after irradiation with an yttrium-scandium-gallium-garnet (YSGG) laser.

PubMed

Yue, Xueping; Wang, Hongwei; Li, Qing; Li, Linfeng

2017-02-01

The objective of this study was to observe the characteristics of the skin after irradiation with a 2790-nm yttrium-scandium-gallium-garnet (YSGG) laser using reflectance confocal microscopy (RCM). A 2790-nm YSGG laser was used to irradiate fresh foreskin (four doses, at spot density 3) in vitro. The characteristics of microscopic ablative columns (MAC), thermal coagulation zone (TCZ), and microscopic treatment zones (MTZ) were observed immediately after irradiation using digital microscope and RCM. The characteristics of MAC, TCZ, and MTZ with variations in pulse energy were comparatively analyzed. After irradiation, MAC, TCZ, and MTZ characteristics and undamaged skin between MTZs can be observed by RCM. The depth and width of MTZ obviously increased with the increase in pulse energy. At 80, 120, and 160 mJ/microbeam (MB), the MTZ actual area and proportion were about two times that of the theoretical value and three times at 200 mJ/MB. With increases in depth, the single MAC gradually decreased in a fingertip-shaped model, with TCZ slowly increasing, and MTZ slightly decreasing in a columnar shape. RCM was able to determine the characteristics of thermal injury on the skin after the 2790-nm YSGG laser irradiation with different pulse energies. Pulse energy higher than 200 mJ/MB may have much larger thermal injury and side effect. RCM could be used in the clinic in future.

Radiotherapeutic bandage based on electrospun polyacrylonitrile containing holmium-166 iron garnet nanoparticles for the treatment of skin cancer.

PubMed

Munaweera, Imalka; Levesque-Bishop, Daniel; Shi, Yi; Di Pasqua, Anthony J; Balkus, Kenneth J

2014-12-24

Radiation therapy is used as a primary treatment for inoperable tumors and in patients that cannot or will not undergo surgery. Radioactive holmium-166 ((166)Ho) is a viable candidate for use against skin cancer. Nonradioactive holmium-165 ((165)Ho) iron garnet nanoparticles have been incorporated into a bandage, which, after neutron-activation to (166)Ho, can be applied to a tumor lesion. The (165)Ho iron garnet nanoparticles ((165)HoIG) were synthesized and introduced into polyacrylonitrile (PAN) polymer solutions. The polymer solutions were then electrospun to produce flexible nonwoven bandages, which are stable to neutron-activation. The fiber mats were characterized using scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and inductively coupled plasma mass spectrometry. The bandages are stable after neutron-activation at a thermal neutron-flux of approximately 3.5 × 10(12) neutrons/cm(2)·s for at least 4 h and 100 °C. Different amounts of radioactivity can be produced by changing the amount of the (165)HoIG nanoparticles inside the bandage and the duration of neutron-activation, which is important for different stages of skin cancer. Furthermore, the radioactive bandage can be easily manipulated to irradiate only the tumor site by cutting the bandage into specific shapes and sizes that cover the tumor prior to neutron-activation. Thus, exposure of healthy cells to high energy β-particles can be avoided. Moreover, there is no leakage of radioactive material after neutron activation, which is critical for safe handling by healthcare professionals treating skin cancer patients.

Low pulse energy Nd:YAG laser irradiation exerts a biostimulative effect on different cells of the oral microenvironment: "an in vitro study".

PubMed

Chellini, Flaminia; Sassoli, Chiara; Nosi, Daniele; Deledda, Cristiana; Tonelli, Paolo; Zecchi-Orlandini, Sandra; Formigli, Lucia; Giannelli, Marco

2010-08-01

Dental lasers represent a promising therapeutic tool in the treatment of periodontal and peri-implant diseases. However, their clinical application remains still limited. Here, we investigated the potential biostimulatory effect of low pulse energy neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation on different cells representative of the oral microenvironment and elucidated the underlying molecular mechanisms. Saos-2 osteoblasts, H-end endothelial cells, and NIH/3T3 fibroblasts pre-treated or not with photosensitizing dye methylene blue (MB), were irradiated with low pulse energy (20 mJ) and high repetition rate (50-70 Hz) Nd:YAG laser, and evaluated for cell viability and proliferation as well as for the expression of specific differentiation markers by confocal immunofluorescence and real-time RT-PCR. Changes in intracellular Ca(2+) levels after laser exposure were also evaluated in living osteoblasts. Nd:YAG laser irradiation did not affect cell viability in all the tested cell types, even when combined with pre-treatment with MB, and efficiently stimulated cell growth in the non-sensitized osteoblasts. Moreover, a significant induction in the expression of osteopontin, ALP, and Runx2 in osteoblasts, type I collagen in fibroblasts, and vinculin in endothelial cells could be observed in the irradiated cells. Pre-treatment with MB negatively affected cell differentiation in the unstimulated and laser-stimulated cells. Notably, laser irradiation also caused an increase in the intracellular Ca(2+) in osteoblasts through the activation of TRPC1 ion channels. Moreover, the pharmacologic or genetic inhibition of these channels strongly attenuated laser-induced osteopontin expression, suggesting a role for the laser-mediated Ca(2+) influx in regulating osteoblast differentiation. Low pulse energy and high repetition rate Nd:YAG laser irradiation may exert a biostimulative effect on different cells representative of the oral microenvironment, particularly

Short-term clinical and microbiologic effects of pocket debridement with an Er:YAG laser during periodontal maintenance.

PubMed

Tomasi, Cristiano; Schander, Kerstin; Dahlén, Gunnar; Wennström, Jan L

2006-01-01

The erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser is considered a useful tool for subgingival debridement because the laser treatment creates minimal damage to the root surface and has potential antimicrobial effects. The aim of this randomized controlled clinical trial was to evaluate clinical and microbiologic effects of pocket debridement using an Er:YAG laser in patients during periodontal maintenance. Twenty patients at a recall visit for maintenance were consecutively recruited if presenting at least four teeth with residual probing depth (PD) > or = 5 mm. Two pockets in each of two jaw quadrants were randomly assigned to subgingival debridement using 1) an Er:YAG laser (test) or 2) an ultrasonic scaler (control). The laser beam was set at 160 mJ with a pulse frequency of 10 Hz. Clinical variables were recorded at baseline, 1 month, and 4 months after treatment. Primary clinical outcome variables were changes in PD and clinical attachment level (CAL). Microbiologic analysis of subgingival samples was performed at baseline, 2 days, and 30 days after treatment using a checkerboard DNA-DNA hybridization technique against 12 periodontal disease-associated species. The mean initial PD was 6.0 mm (SD: 1.2) in the test group and 5.8 mm (SD: 0.9) in the control group. At 1 month post-treatment, the PD reduction was significantly greater for test than control sites (0.9 versus 0.5 mm; P <0.05). The CAL gain also was significantly greater (0.5 versus 0.06 mm; P <0.01). At the 4-month examination, no significant differences were detected in PD reduction (1.1 versus 1.0 mm) or CAL gain (0.6 versus 0.4 mm). Both treatments resulted in reduction of the subgingival microflora. No significant differences in microbiologic composition were identified between the treatment groups at various time intervals. Degree of treatment discomfort scored significantly lower for the test than the control treatment modality. The results of the trial failed to demonstrate any

On the Samarium Substitution Effects in Y3-x Sm x Al5O12 (x = 0.1-3.0)

NASA Astrophysics Data System (ADS)

Skaudzius, Ramunas; Sakirzanovas, Simas; Kareiva, Aivaras

2018-04-01

Yttrium aluminium garnet substituted by samarium Y3-x Sm x Al5O12, (YSmAG, x = 0.1, 0.15, 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5 and 3.0) was prepared by an aqueous sol-gel processing using etane-1,2-diol as complexing agent. The end products obtained at 1000°C in air were characterized by x-ray diffraction analysis, infrared spectroscopy (FT-IR) and scanning electron microscopy. It was demonstrated, however, that the total substitution of yttrium by samarium does not proceed in the YSmAG. The single cubic garnet phase was formed only at a low concentration of samarium (x = 0.1, 0.15, 0.25, 0.5, 0.75, 1.0). With further substitutional levels, if the amount of samarium was x = 1.5, 2.0, 2.5 and 3, respectively, the formation a of minor amount of side perovskite samarium aluminate SmAlO3 (SmAP) phase was observed. Surprisingly, when yttrium was totally replaced by the samarium (x = 3.0) the main synthesis product was SmAP. The possible formation of Sm3Al5O12 (SmAG) garnet was also investigated for the first time by variation of the temperature in the range of 780-835°C.

A continuous-wave and passively Q-switched Nd:LaGGG laser at 937 nm

NASA Astrophysics Data System (ADS)

Li, Z.-Y.; Ying, H.-Y.; Yang, H.; He, J.-L.

2013-10-01

A diode-end-pumped continuous-wave (CW) and passively Q-switched Nd:LaGGG (GGG: gadolinium gallium garnet) laser at about 937 nm was demonstrated for the first time. The maximum CW output power of 540 mW was obtained with the optical-optical conversion efficiency of 3.2% and the slope efficiency of 4.4%. A V3+:YAG (yttrium aluminum garnet) saturable absorber with the initial transmission of 97% was used for the passive Q-switching regime. The shortest pulse width was achieved as 500 ns with the pulse repetition rate of 96 kHz. The corresponding single-pulse energy and pulse peak power were determined as 1.56 μJ and 3.12 W, respectively.

Development of Scintillators in Nuclear Medicine

PubMed Central

Khoshakhlagh, Mohammad; Islamian, Jalil Pirayesh; Abedi, Seyed Mohammad; Mahmoudian, Babak

2015-01-01

High-quality image is necessary for accurate diagnosis in nuclear medicine. There are many factors in creating a good image and detector is the most important one. In recent years, several detectors are studied to get a better picture. The aim of this paper is comparison of some type of these detectors such as thallium activated sodium iodide bismuth germinate cesium activated yttrium aluminum garnet (YAG: Ce) YAP: Ce “lutetium aluminum garnet activated by cerium” CRY018 “CRY019” lanthanum bromide and cadmium zinc telluride. We studied different properties of these crystals including density, energy resolution and decay times that are more important factors affecting the image quality. PMID:26420984

Low-power holmium:YAG laser urethrotomy for treatment of urethral strictures: functional outcome and quality of life.

PubMed

Kamp, Stefan; Knoll, Thomas; Osman, Mahmoud M; Köhrmann, Kai Uwe; Michel, Maurice S; Alken, Peter

2006-01-01

To evaluate the efficacy of endourethrotomy with the holmium:YAG laser as a minimally invasive treatment for urethral stricture. Between January 2002 and January 2004, 32 male patients with symptomatic urethral strictures (8 bulbar, 9 penile, 9 combined) were treated with Ho:YAG-laser urethrotomy in our department. The stricture was iatrogenic in 60% (N = 18), inflammatory in 16.6% (N = 5), traumatic in 13.3% (N = 4), and idiopathic in 7% (N = 3). The stricture was incised under vision at the 12 o'clock location or the site of maximum scar tissue or narrowing in asymmetric strictures. Laser energy was set on 1200 to 1400 mJ with a frequency of 10 to 13 Hz. Postoperatively, drainage of the bladder was performed for 4 days using a 18F silicone catheter. Triamcinolone was instilled intraurethrally after removal of the catheter in all patients. Patients were followed up by mailed questionnaire, including International Prostate Symptom Score and quality of life. Retrograde endoscopic Ho:YAG laser urethrotomy could be performed in all 32 patients. Most patients (22; 68.7%) did not need any reintervention. Ten patients developed recurrent strictures that were treated by another laser urethrotomy in 4 patients (12.5%), while 6 patients (18.7%) needed open urethroplasty with buccal mucosa. Including 2 patients treated with repeat laser urethrotomy, 24 patients (75%) were considered successful after a mean follow-up of 27 months (range 13-38 months). No intraoperative complications were encountered, although in 5% of patients, a urinary-tract infection was diagnosed postoperatively. No gross hematuria occurred. The Ho:YAG laser urethrotomy is a safe and effective minimally invasive therapeutic modality for urethral stricture with results comparable to those of conventional urethrotomy. Further data from long-time follow-up are necessary to compare the success rate with that of conventional urethrotomy and urethroplasty. Nevertheless, the Ho:YAG laser urethrotomy might at

Charge-coupled Substituted Garnets (Y3-xCa0.5xM0.5x)Fe5O12 (M = Ce, Th): Structure and Stability as Crystalline Nuclear Waste Forms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Xiaofeng; Kukkadapu, Ravi K.; Lanzirotti, Anthony

2015-04-20

The garnet structure has been proposed as a potential crystalline nuclear waste form for accommodation of actinide elements, especially uranium (U). In this study, yttrium iron garnet (YIG) as a model garnet host was studied for the incorporation of U analogs, cerium (Ce), and thorium (Th), incorporated by a charge-coupled substitution with calci-um (Ca) for yttrium (Y) in YIG, namely 2Y3+ = Ca2+ + M4+, where M4+ = Ce4+ or Th4+. Single phase garnets Y3-xCa0.5xM0.5xFe5O12, synthesized by the citrate-nitrate combustion method, were obtained up to x = 0.7. Ce was confirmed to be tetravalent by X-ray absorption spectroscopy and X-raymore » photoelectron spectroscopy. X-ray diffraction and 57Fe-Mössbauer spectroscopy indicated that the samples are single phase, M4+ and Ca2+ cations are restricted to the c-site, the nature of M4+ has only a minor effect on the structure, and the local environments of both the tetrahedral and octahedral Fe3+ are systematically affected by the extent of substitution, especially on the tetrahedral sublattice. The charge coupled substitution has advantages in incorporating Ce/Th and in stabilizing the substituted phases, compared to a single substitution strategy. Enthalpies of formation of garnets were obtained by high temperature oxide melt solution calorimetry, and the enthalpies of substitution of Ce and Th were determined. The thermodynamic analysis demonstrates that the substituted garnets are entropically rather than energetically stabilized. This suggests that such garnets may form and persist in repositories at high temperature but might decompose near room temperature. These structural and thermodynamic findings shed light on possible incorporation of U in this garnet system.« less

Charge-coupled substituted garnets (Y 3–x Ca 0.5x M 0.5x )Fe₅O₁₂ (M = Ce, Th): Structure and stability as crystalline nuclear waste forms

DOE PAGES

Guo, Xiaofeng; Kukkadapu, Ravi K.; Lanzirotti, Antonio; ...

2015-04-20

The garnet structure has been proposed as a potential crystalline nuclear waste form for accommodation of actinide elements, especially uranium (U). In this study, yttrium iron garnet (YIG) as a model garnet host was studied for the incorporation of U analogs, cerium (Ce) and thorium (Th), incorporated by a charge-coupled substitution with calcium (Ca) for yttrium (Y) in YIG, namely, 2Y³⁺ = Ca²⁺ + M⁴⁺, where M⁴⁺ = Ce⁴⁺ or Th⁴⁺. Single-phase garnets Y 3–xCa 0.5xM 0.5xFe₅O₁₂ (x = 0.1–0.7) were synthesized by the citrate–nitrate combustion method. Ce was confirmed to be tetravalent by X-ray absorption spectroscopy and X-ray photoelectronmore » spectroscopy. X-ray diffraction and ⁵⁷Fe–Mössbauer spectroscopy indicated that M⁴⁺ and Ca²⁺ cations are restricted to the c site, and the local environments of both the tetrahedral and the octahedral Fe³⁺ are systematically affected by the extent of substitution. The charge-coupled substitution has advantages in incorporating Ce/Th and in stabilizing the substituted phases compared to a single substitution strategy. Enthalpies of formation of garnets were obtained by high-temperature oxide melt solution calorimetry, and the enthalpies of substitution of Ce and Th were determined. The thermodynamic analysis demonstrates that the substituted garnets are entropically rather than energetically stabilized. This suggests that such garnets may form and persist in repositories at high temperature but might decompose near room temperature.« less

Atomistic simulation of trace element incorporation into garnets - comparison with experimental garnet-melt partitioning data

NASA Astrophysics Data System (ADS)

van Westrenen, W.; Allan, N. L.; Blundy, J. D.; Purton, J. A.; Wood, B. J.

2000-05-01

We have studied the energetics of trace element incorporation into pure almandine (Alm), grossular (Gros), pyrope (Py) and spessartine (Spes) garnets (X 3Al 2Si 3O 12, with X = Fe, Ca, Mg, Mn respectively), by means of computer simulations of perfect and defective lattices in the static limit. The simulations use a consistent set of interatomic potentials to describe the non-Coulombic interactions between the ions, and take explicit account of lattice relaxation associated with trace element incorporation. The calculated relaxation (strain) energies Urel are compared to those obtained using the Brice (1975) model of lattice relaxation, and the results compared to experimental garnet-melt trace element partitioning data interpreted using the same model. Simulated Urel associated with a wide range of homovalent (Ni, Mg, Co, Fe, Mn, Ca, Eu, Sr, Ba) and charge-compensated heterovalent (Sc, Lu, Yb, Ho, Gd, Eu, Nd, La, Li, Na, K, Rb) substitutions onto the garnet X-sites show a near-parabolic dependence on trace element radius, in agreement with the Brice model. From application of the Brice model we derived apparent X-site Young's moduli EX(1+, 2+, 3+) and the 'ideal' ionic radii r0(1+, 2+, 3+), corresponding to the minima in plots of Urel vs. radius. For both homovalent and heterovalent substitutions r0 increases in the order Py-Alm-Spes-Gros, consistent with crystallographic data on the size of garnet X-sites and with the results of garnet-melt partitioning studies. Each end-member also shows a marked increase in both the apparent EX and r0 with increasing trace element charge ( Zc). The increase in EX is consistent with values obtained by fitting to the Brice model of experimental garnet-melt partitioning data. However, the increase in r0 with increasing Zc is contrary to experimental observation. To estimate the influence of melt on the energetics of trace element incorporation, solution energies ( Usol) were calculated for appropriate exchange reactions between

Sintering and microstructure of silicon carbide ceramic with Y3Al5O12 added by sol-gel method*

PubMed Central

Guo, Xing-zhong; Yang, Hui

2005-01-01

Silicon carbide (SiC) ceramic with YAG (Y3Al5O12) additive added by sol-gel method was liquid-phase sintered at different sintering temperatures, and the sintering mechanism and microstructural characteristics of resulting silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental distribution of surface (EDS). YAG (yttrium aluminum garnet) phase formed before the sintering and its uniform distribution in the SiC/YAG composite powder decreased the sintering temperature and improved the densification of SiC ceramic. The suitable sintering temperature was 1860 °C with the specimen sintered at this temperature having superior sintering and mechanical properties, smaller crystal size and fewer microstructure defects. Three characteristics of improved toughness of SiC ceramic with YAG added by sol-gel method were microstructural densification, main-crack deflection and crystal ‘bridging’. PMID:15682507

Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid.

PubMed

Hosseini, Mohammad Hashem; Sobouti, Farhad; Etemadi, Ardavan; Chiniforush, Nasim; Shariati, Mahsa

2015-02-01

Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns and bridges. The present study evaluated the shear bond strength of metal orthodontic brackets to the feldspathic porcelain surfaces following conditioning by different powers of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and hydrofluoric acid as a conventional method. Seventy-two glazed porcelain samples were prepared and randomly attributed to six equal groups of 12. In the conventional hydrofluoric (HF) group, the specimens were etched by 9.6% hydrofluoric acid for 4 min. In laser groups, samples were conditioned by 0.75-, 1-, 1.25-, 1.5-, and 2-W Nd:YAG laser for 10 s. Metal brackets were bonded to porcelain samples and after being stored in distilled water for 24 h, they were subjected to thermocycling for 500 cycles. The debonding was carried out by a Zwick testing machine. The data were statistically analyzed by ANOVA and Tamhane multiple comparisons tests. The mean ± SD of the shear bond strength in the laser group 0.75, 1, 1.25, 1.5, and 2 W and HF group was 2.2 ± 0.9, 4.2 ± 1.1, 4.9 ± 2.4, 7 ± 1.7, 9.6 ± 2.7, and 9.4 ± 2.5, respectively. Together with the increased power of laser, the mean shear bond strength was increased continuously and no significant differences were found between the HF group and the laser groups with power of 1.5 or 2 W. Also, there was no significant difference between all test groups in ARI scores. There was no significant difference between bond strength of laser groups with power of 1.5 and 2 W and HF-etched group. So, Nd:YAG laser with appropriate parameters can be used as an alternative method for porcelain etching.

Magnetooptics of single and microresonator iron-garnet films at low temperatures

NASA Astrophysics Data System (ADS)

Shaposhnikov, A. N.; Prokopov, A. R.; Berzhansky, V. N.; Mikhailova, T. V.; Karavainikov, A. V.; Kharchenko, M. F.; Belotelov, V. I.; Lukienko, I. M.; Miloslavskaya, O. V.; Kharchenko, Yu. M.

2016-02-01

We have investigated the low-temperature behavior of the optical and magneto-optical properties of (Bi, Gd, Al)-substituted yttrium iron-garnet films that are either single or microresonator, i.e. sandwiched between two dielectric Bragg mirrors. It was shown that the magneto-optical properties of the microresonators with a magnetic film core are mainly determined by the properties of the constituent magnetic films. Special attention was paid to the compositions possessing magnetic compensation temperatures. The phenomenon of the temperature hysteresis was found and discussed for several samples. This testifies the fact that the magnetic moment reorientation in a magnetic field occurs by the full cycle of the first-order phase transitions "collinear phase - non-collinear phase - collinear phase". The Faraday hysteresis curves at around magnetic compensation temperatures are demonstrated to be very informative concerning composition of a sample. In particular, the hysteresis curves measured for the magnetic films on the garnet substrates showed bursts that indicates formation of a transition layer.

Microshear Bond Strength of OptiBond All-in-One Self-adhesive Agent to Er:YAG Laser Treated Enamel After Thermocycling and Water Storage.

PubMed

Kasraei, Shahin; Yarmohammadi, Ebrahim; Ghazizadeh, Mohammad Vahid

2016-01-01

Introduction: This study aimed to compare the microshear bond strength of composite to enamel treated with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser using a self-etch one step bonding agent. Methods: Seventy-six enamel surfaces were prepared from 38 sound human third molar teeth. Specimens were randomly divided into four groups of 18. The enamel surface in half the specimens was irradiated with Er:YAG laser. One extra specimen from each group was evaluated under a scanning electron microscope (SEM). Composite micro-cylinders were bonded to the specimen surfaces using OptiBond All-In-One (OB) adhesive agent and stored in distilled water for 24 hours. Half the specimens were thermocycled (2000 cycles) and stored in distilled water at 37°C for three months (TW). The microshear bond strength of composite to enamel was measured using a universal testing machine at a crosshead speed of 1 mm/min. The fractured surfaces were evaluated under a stereomicroscope at ×40 magnification to determine the mode of failure. Data were analyzed using repeated measures analysis of variance (ANOVA) and t test. Results: The mean values (±standard deviation) were 17.96 ± 2.92 MPa in OB group, 22.29 ± 4.25 MPa in laser + OB group, 18.11 ± 3.52 MPa in laser + OB + TW group and 9.42 ± 2.47 MPa in OB + TW group. Repeated measures ANOVA showed that laser irradiation increased the microshear bond strength ( P < 0.001). Bond strength decreased when the samples were thermocycled and stored for three months ( P < 0.001). The interaction effect of water storage and laser treatment on bond strength was significant ( P < 0.05). Conclusion: Enamel surface preparation with Er:YAG laser is recommended to enhance the durability of the bond of self-etch bonding systems to enamel.

Microshear Bond Strength of OptiBond All-in-One Self-adhesive Agent to Er:YAG Laser Treated Enamel After Thermocycling and Water Storage

PubMed Central

Kasraei, Shahin; Yarmohammadi, Ebrahim; Ghazizadeh, Mohammad Vahid

2016-01-01

Introduction: This study aimed to compare the microshear bond strength of composite to enamel treated with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser using a self-etch one step bonding agent. Methods: Seventy-six enamel surfaces were prepared from 38 sound human third molar teeth. Specimens were randomly divided into four groups of 18. The enamel surface in half the specimens was irradiated with Er:YAG laser. One extra specimen from each group was evaluated under a scanning electron microscope (SEM). Composite micro-cylinders were bonded to the specimen surfaces using OptiBond All-In-One (OB) adhesive agent and stored in distilled water for 24 hours. Half the specimens were thermocycled (2000 cycles) and stored in distilled water at 37°C for three months (TW). The microshear bond strength of composite to enamel was measured using a universal testing machine at a crosshead speed of 1 mm/min. The fractured surfaces were evaluated under a stereomicroscope at ×40 magnification to determine the mode of failure. Data were analyzed using repeated measures analysis of variance (ANOVA) and t test. Results: The mean values (±standard deviation) were 17.96 ± 2.92 MPa in OB group, 22.29 ± 4.25 MPa in laser + OB group, 18.11 ± 3.52 MPa in laser + OB + TW group and 9.42 ± 2.47 MPa in OB + TW group. Repeated measures ANOVA showed that laser irradiation increased the microshear bond strength (P < 0.001). Bond strength decreased when the samples were thermocycled and stored for three months (P < 0.001). The interaction effect of water storage and laser treatment on bond strength was significant (P < 0.05). Conclusion: Enamel surface preparation with Er:YAG laser is recommended to enhance the durability of the bond of self-etch bonding systems to enamel. PMID:28144434

Manufacturing issues and optical properties of rare-earth (Y, Lu, Sc, Nd) aluminate garnets composite transparent ceramics

NASA Astrophysics Data System (ADS)

Bonnet, Loïck; Boulesteix, Rémy; Maître, Alexandre; Sallé, Christian; Couderc, Vincent; Brenier, Alain

2015-12-01

In this work, a comparative study of reactive sintering and optical properties of three laser composite transparent ceramics doped with neodymium: Nd:YAG/Nd:YS1AG, Nd:YAG/Nd:LuAG and Nd:YS1AG/Nd:LuAG has been achieved. Samples were manufactured thanks to pressureless co-sintering under vacuum of bilayer powder compacts. The reaction sequence from primary oxides to final garnet phases has been investigated. Similar dilatometric behavior was observed during reactive-sintering for each composition. Differential shrinkage can be thus accommodated to some extent. Second, this work has shown that the intermediate zone at composites interface is composed of single-phased garnet solid-solution with continuous evolution from one side to the other. The thickness of the interdiffusion zone was found to be limited to about 100 μm in all cases and appeared to be well described by classical diffusion laws of Fick and Whipple-Le Claire. The analyses of spectroscopic properties of transparent ceramics composites have finally shown that composite ceramics should be suitable to produce dual wavelength emission for terahertz generation.

US-guided application of Nd:YAG laser in porcine pancreatic tissue: an ex vivo study and numerical simulation.

PubMed

Di Matteo, Francesco; Martino, Margareth; Rea, Roberta; Pandolfi, Monica; Panzera, Francesco; Stigliano, Egidio; Schena, Emiliano; Saccomandi, Paola; Silvestri, Sergio; Pacella, Claudio Maurizio; Breschi, Luca; Perrone, Giuseppe; Coppola, Roberto; Costamagna, Guido

2013-11-01

Laser ablation (LA) with a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is a minimally invasive approach able to achieve a high rate of complete tissue necrosis. In a previous study we described the feasibility of EUS-guided Nd:YAG pancreas LA performed in vivo in a porcine model. To establish the best laser setting of Nd:YAG lasers for pancreatic tissue ablation. A secondary aim was to investigate the prediction capability of a mathematical model on ablation volume. Ex vivo animal study. Hospital animal laboratory. Explanted pancreatic glands from 60 healthy farm pigs. Laser output powers (OP) of 1.5, 3, 6, 10, 15, and 20 W were supplied. Ten trials for each OP were performed under US guidance on ex vivo healthy porcine pancreatic tissue. Ablation volume (Va) and central carbonization volume (Vc) were measured on histologic specimens as the sum of the lesion areas multiplied by the thickness of each slide. The theoretical model of the laser-tissue interaction was based on the Pennes equation. A circumscribed ablation zone was observed in all histologic specimens. Va values grow with the increase of the OP up to 10 W and reach a plateau between 10 and 20 W. The trend of Vc values rises constantly until 20 W. The theoretical model shows a good agreement with experimental Va and Vc for OP between 1.5 and 10 W. Ex vivo study. Volumes recorded suggest that the best laser OP could be the lowest one to obtain similar Va with smaller Vc in order to avoid the risk of thermal injury to the surrounding tissue. The good agreement between the two models demonstrates the prediction capability of the theoretical model on laser-induced ablation volume in an ex vivo animal model and supports its potential use for estimating the ablation size at different laser OPs. Copyright © 2013 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

The influence of dentin demineralization on morphological features of cavities using Er:YAG laser.

PubMed

Melo, Mary A S; Lima, Juliana P M; Passos, Vanara F; Rodrigues, Lidiany K A

2015-01-01

The purpose of this study was to evaluate the influence of erbium-doped: yttrium-aluminum-garnet (Er:YAG) laser parameters and different degrees of demineralization on morphological features, diameter, and depth of prepared cavities. Minimally invasive dentin caries removal has been recommended. Ablation of deep caries lesions using Er:YAG laser should preserve remaining demineralized dentin; however, the influence of the degree of mineralization of this substrate had not been entirely described. A randomized, factorial design was used to study the effects of two factors. Laser parameter was tested at two levels (250 mJ/4 Hz vs. 200 mJ/2 Hz) and degree of demineralization was tested at four levels (control, two-four-eight cycles). Twelve slabs of human dentin were divided into four groups according to the number of cycles induced by pH-cycling: G1, zero cycles; G2, two cycles, G3, four cycles, and G4, eight cycles. An Er:YAG laser was used at an output energy of 250 mJ/4 Hz and 200 mJ/2 Hz for all groups, for 10 sec at 12 mm distance focus/object. Circumference and depth of the cavities were measured on scanning electron microscopy (SEM) images using image analysis software. The mean values were subjected to two way analysis of variance (ANOVA) and Tukey tests. When using 250 mJ/4 Hz, the mean values of circumferential area increased significantly in relation to control (503.54 μm(2)) with increasing demineralization level (eight cycles) (555.45 μm(2)). Regardless of the demineralization level, there was also significant statistical difference in the studied measurements of the cavities when 250 mJ/4 Hz and 200 mJ/2 Hz were used. SEM also showed that laser cavity preparations left no smear layer, and the dentinal tubules were clear. The circumferential area and depth measurements were affected by laser parameter and demineralization level (eight cycles). Energy level output represents a relevant factor for increased circumferential area and depth measurements

Nanometer-Thick Yttrium Iron Garnet Film Development and Spintronics-Related Study

NASA Astrophysics Data System (ADS)

Chang, Houchen

In the last decade, there has been a considerable interest in using yttrium iron garnet (Y3Fe5O12, YIG) materials for magnetic insulator-based spintronics studies. This interest derives from the fact that YIG materials have very low intrinsic damping. The development of YIG-based spintronics demands YIG films that have a thickness in the nanometer (nm) range and at the same time exhibit low damping similar to single-crystal YIG bulk materials. This dissertation reports comprehensive experimental studies on nm-thick YIG films by magnetron sputtering techniques. Optimization of sputtering control parameters and post-deposition annealing processes are discussed in detail. The feasibility of low-damping YIG nm-thick film growth via sputtering is demonstrated. A 22.3-nm-thick YIG film, for example, shows a Gilbert damping constant of less than 1.0 x 10-4. The demonstration is of great technological significance because sputtering is a thin film growth technique most widely used in industry. The spin Seebeck effect (SSE) refers to the generation of spin voltage in a ferromagnet (FM) due to a temperature gradient. The spin voltage can produce a pure spin current into a normal metal (NM) that is in contact with the FM. Various theoretical models have been proposed to interpret the SSE, although a complete understanding of the effect has not been realized yet. In this dissertation the study of the role of damping on the SSE in YIG thin films is conducted for the first time. With the thin film development method mentioned in the last paragraph, a series of YIG thin films showing very similar structural and static magnetic properties but rather different Gilbert damping values were prepared. A Pt capping layer was grown on each YIG film to probe the strength of the SSE. The experimental data show that the YIG films with a smaller intrinsic Gilbert damping shows a stronger SSE. The majority of the previous studies on YIG spintronics utilized YIG films that were grown on single

Issues in nanocomposite ceramic engineering: focus on processing and properties of alumina-based composites.

PubMed

Palmero, Paola; Kern, Frank; Sommer, Frank; Lombardi, Mariangela; Gadow, Rainer; Montanaro, Laura

2014-12-30

Ceramic nanocomposites, containing at least one phase in the nanometric dimension, have received special interest in recent years. They have, in fact, demonstrated increased performance, reliability and lifetime with respect to monolithic ceramics. However, a successful approach to the production of tailored composite nanostructures requires the development of innovative concepts at each step of manufacturing, from the synthesis of composite nanopowders, to their processing and sintering.This review aims to deepen understanding of some of the critical issues associated with the manufacturing of nanocomposite ceramics, focusing on alumina-based composite systems. Two case studies are presented and briefly discussed. The former illustrates the benefits, in terms of sintered microstructure and related mechanical properties, resulting from the application of an engineering approach to a laboratory-scale protocol for the elaboration of nanocomposites in the system alumina-ZrO2-YAG (yttrium aluminium garnet). The latter illustrates the manufacturing of alumina-based composites for large-scale applications such as cutting tools, carried out by an injection molding process. The need for an engineering approach to be applied in all processing steps is demonstrated also in this second case study, where a tailored manufacturing process is required to obtain the desired results.

Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

PubMed

Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

2011-02-01

In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells.

Parametric amplification of 100 fs mid-infrared pulses in ZnGeP₂ driven by a Ho:YAG chirped-pulse amplifier.

PubMed

Kanai, Tsuneto; Malevich, Pavel; Kangaparambil, Sarayoo Sasidharan; Ishida, Kakuta; Mizui, Makoto; Yamanouchi, Kaoru; Hoogland, Heinar; Holzwarth, Ronald; Pugzlys, Audrius; Baltuska, Andrius

2017-02-15

We report on the parametric generation of 100 fs sub-6-cycle 40 μJ pulses with the center wavelength at 5.2 μm using a 1 ps 2.1 μm pump laser and a dispersion management scheme based on bulk material. Our optically synchronized amplifier chain consists of a Ho:YAG chirped-pulse amplifier and white-light-seeded optical parametric amplifiers providing simultaneous passive carrier-envelope phase locking of three ultrashort longwave pulses at the pump, signal, and idler wavelengths corresponding, respectively, to 2.1, 3.5, and 5.2 μm. We also demonstrate bandwidth enhancement and efficient control over nonlinear spectral phase in the regime of cascaded χ² nonlinearity in ZnGeP₂.

Periodic grain-boundary formation in a poly-Si thin film crystallized by linearly polarized Nd:YAG pulse laser with an oblique incident angle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaki, Hirokazu; Horita, Susumu

2005-01-01

We investigated the periodic grain-boundary formation in the polycrystalline silicon film crystallized by a linearly polarized Nd:YAG (where YAG is yttrium aluminum garnet) pulse laser with an oblique incident angle {theta}{sub i}=25 deg. , compared with the normal incident angle {theta}{sub i}=0. The alignment of the grain boundary was uncontrollable and fluctuated in the case of the oblique incident and large irradiation pulse number while that in the case of the normal incident was performed stably. It was found that the main cause for its low controllability was the nonphase matching between the periodic surface corrugation of the crystallized siliconmore » film and the periodic temperature profile induced by the laser irradiation. Also, it was found that, in the case of {theta}{sub i}=25 deg. , the dominant periodic width of the grain boundary depended on the pulse number N. That is, it was around {lambda}/(1+sin {theta}{sub i}) for small N{approx_equal}10 and {lambda}/(1-sin {theta}{sub i}) for large N{approx_equal}100 at the laser wavelength of {lambda}=532 nm. In order to explain this dependence, we proposed a model to take into account the periodic corrugation height proportional to the molten volume of the silicon film, the impediment in interference between the incident beam and diffracted beam on the irradiated surface due to the corrugation height, and the reduction of the liquid surface roughness during melting-crystallization process due to liquid-silicon viscosity.« less

Unexpected structural and magnetic depth dependence of YIG thin films

NASA Astrophysics Data System (ADS)

Cooper, J. F. K.; Kinane, C. J.; Langridge, S.; Ali, M.; Hickey, B. J.; Niizeki, T.; Uchida, K.; Saitoh, E.; Ambaye, H.; Glavic, A.

2017-09-01

We report measurements on yttrium iron garnet (YIG) thin films grown on both gadolinium gallium garnet (GGG) and yttrium aluminum garnet (YAG) substrates, with and without thin Pt top layers. We provide three principal results: the observation of an interfacial region at the Pt/YIG interface, we place a limit on the induced magnetism of the Pt layer, and confirm the existence of an interfacial layer at the GGG/YIG interface. Polarized neutron reflectometry (PNR) was used to give depth dependence of both the structure and magnetism of these structures. We find that a thin film of YIG on GGG is best described by three distinct layers: an interfacial layer near the GGG, around 5 nm thick and nonmagnetic, a magnetic "bulk" phase, and a nonmagnetic and compositionally distinct thin layer near the surface. We theorize that the bottom layer, which is independent of the film thickness, is caused by Gd diffusion. The top layer is likely to be extremely important in inverse spin Hall effect measurements, and is most likely Y2O3 or very similar. Magnetic sensitivity in the PNR to any induced moment in the Pt is increased by the existence of the Y2O3 layer; any moment is found to be less than 0.02 μB/atom .

Damage thresholds of silica fibers in holmium:YAG laser energy delivery for medical applications

NASA Astrophysics Data System (ADS)

Marolda, Matthew D.; Perrault, Donald F., Jr.; Pankratov, Michail M.; Shapshay, Stanley M.

1993-07-01

Pulsed Holmium:YAG (Ho:YAG) laser has been approved for some clinical applications and is under investigation for others. There is little published evidence on the durability or damage parameters for the fibers used in delivering energy from pulsed Ho:YAG laser. This study makes an initial attempt to investigate the damage threshold of different silica fibers under various conditions. Three types of fibers supplied by different manufacturers underwent laboratory testing. The overall finding of the study is that a new `perfect' fiber sustains no damage when fired without a target in air or in saline at energies up to 1.5 J/pulse and repetition rate up to 10 Hz. This study suggests that one may need to chose a fiber according to the clinical procedure to be performed: in cases where only soft tissue is to be manipulated - - any fiber may fare well, in cases where bone or calcified tissue is to be lased -- one may need fiber with aluminized or other hard coating. We also conclude that only professional refinishing with the removal of all exposed core-cladding material can insure trouble free performance.

Research progress on laser crystals in China

NASA Astrophysics Data System (ADS)

Yingxia, Z.

1985-01-01

Current Chinese research on laser crystals is now quite extensive and involves more than 30 research teams with nearly 1,000 technicians and workers actively engaged in the study of more than 20 types of laser cyrstals. Neodymium-doped yttrium aluminum garnet (Nd:YAG) and ruby (Cr:Al2O3) lasers have been manufactured and are widely employed. There are several new and promising crystals now under study which will find applications, and both basic and exploratory research have given rise to new developments.

LASERS IN MEDICINE: Two-photon excitation of aluminium phthalocyanines

NASA Astrophysics Data System (ADS)

Meshalkin, Yu P.; Alfimov, E. E.; Vasil'ev, N. E.; Denisov, A. N.; Makukha, V. K.; Ogirenko, A. P.

1999-12-01

A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined.

Enhancement of light absorption by blood to Nd:YAG laser using PEG-modified gold nanorods.

PubMed

Xing, Linzhuang; Li, Dong; Chen, Bin; Dai, Yuze; Wu, Wenjuan; Wang, Guoxiang

2016-10-01

On the basis of the principle of selective photothermolysis, laser therapy has been the most effective treatment strategy for Port-wine stains (PWSs) caused by the expansion of dermal capillaries. Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser at 1064 nm wavelength has great potential for deeply buried PWS, although its application is limited because of its weak absorption by blood. The purpose of this study is to investigate the effect of PEG-modified gold nanorods (NRs) on the blood absorption enhancement for Nd:YAG laser. PEG-modified gold nanorods (NRs) were synthesized via the seeded growth method. Then, the effect of PEG-modified gold NRs on blood light absorbance was investigated through adding different concentration of PEG-modified gold NRs to 1 ml of blood at room temperature. Finally, the optical properties of whole mice blood with or without PEG-modified gold NRs under slow heating were investigated. The average length and width of PEG-modified gold NRs are 79.5 ± 10.5 and 13.5 ± 0.9 nm, respectively, with the aspect ratio of 5.89, and a strong absorption peak exists at ∼1050 nm in the near-infrared range. A linear correlation between the blood absorbance at 1064 nm and the amount of PEG-modified gold NRs was obtained. The absorbance at 1064 nm increased 17.6, 33.0, 48.3, and 65.4 times when 0.4, 0.8, 1.2, and 1.6 mg of PEG-modified gold NRs was added to 1 ml of blood at room temperature, respectively. After adding 0.8 mg of PEG-modified gold NRs to 1 ml of blood, blood absorbance at 1064 nm at different temperatures increased by an average of 24.0 times. After intravenously injecting PEG-modified gold NRs (0.87 mg/ml) into Sprague-Dawley mice, the blood absorbance at 1064 nm increased from 0.014 to 0.5. Our findings suggest that PEG-modified gold NRs injection is an efficient way to enhance light absorption by blood to Nd:YAG laser. Lasers Surg. Med. 48:790-803, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley

Pulmonary Laser Metastasectomy by 1318-nm Neodymium-Doped Yttrium-Aluminum Garnet Laser: A Retrospective Study About Laser Metastasectomy of the Lung.

PubMed

Porrello, Calogero; Gullo, Roberto; Vaglica, Antonino; Scerrino, Gregorio; Salamone, Giuseppe; Licari, Leo; Raspanti, Cristina; Gulotta, Eliana; Gulotta, Gaspare; Cocorullo, Gianfranco

2018-04-01

The lungs are among the first organ affected by remote metastases from many primary tumors. The surgical resection of isolated pulmonary metastases represents an important and effective element of therapy. This is a retrospective study about our entire experience with pulmonary resection for metastatic cancer using 1318-nm neodymium-doped yttrium-aluminum garnet laser. In this single-institution study, we retrospectively analyzed a group of 209 patients previously treated for primary malignant solid tumors. We excluded 103 patients. The number and location of lesions in the lungs was determined using chest computed tomography and positron emission tomography-computed tomography. Disseminated malignancy was excluded. All pulmonary laser resections are performed via an anteroaxillary muscle-sparing thoracotomy. All lesions were routinely removed by laser with a small (5-10 mm) margin of the healthy lung. Patients received systematic lymph node sampling with intraoperative smear cytology of sampled lymph nodes. Mortality at 2 years from the first surgery is around 20% (10% annually). This value increases to 45% in the third year. The estimated median survival for patients who underwent the first surgery is reported to be approximately 42 months. Our results show that laser resection of lung metastases can achieve good result, in terms of radical resection and survival, as conventional surgical metastasectomy. The great advantage is the possibility of limiting the damage to the lung. Stapler resection of a high number of metastases would mutilate the lung.

The study of laser pulse width on efficiency of Ho:YAG laser lithotripsy

NASA Astrophysics Data System (ADS)

Zhang, Jian J.; Rutherford, Jonathan; Solomon, Metasebya; Cheng, Brian; Xuan, Jason R.; Gong, Jason; Yu, Honggang; Xia, Michael; Yang, Xirong; Hasenberg, Thomas; Curran, Sean

2017-02-01

When treating ureteral calculi, retropulsion can be reduced by using a longer pulse width without compromising fragmentation efficiency (from the studies by David S. Finley et al. and Hyun Wook Kang et al.). In this study, a lab build Ho:YAG laser was used as the laser pulse source, with pulse energy from 0.2J up to 3.0 J, and electrical pump pulse width from 150 us up to 1000 us. The fiber used in the investigation is a 365 μm core diameter fiber, SureFlexTM, Model S-LLF365. Plaster of Paris calculus phantoms were ablated at different energy levels (0.2, 0.5, 1, 2, 3J) and with different number of pulses (1, 3, 10) using different electrical pump pulse width (333, 667, 1000 μs). The dynamics of the recoil action of a calculus phantom was monitored using a high-speed camera with frame rate up to 1 million frame per second (Photron Fastcam SA5); and the laser-induced craters were evaluated with a 3-D digital microscope (Keyence VHX-900F). A design of experiment software (DesignExpert-10, Minneapolis, MN, USA) is used in this study for the best fit of surface response on volume of dusting and retropulsion amplitude. The numerical formulas for the response surfaces of dusting speed and retropulsion amplitude are generated. More detailed investigation on the optimal conditions for dusting of other kinds of stone samples and the fiber size effect will be conducted as a future study.

Shear bond strength and SEM morphology evaluation of different dental adhesives to enamel prepared with ER:YAG laser.

PubMed

Pires, Patrícia T; Ferreira, João C; Oliveira, Sofia A; Azevedo, Alvaro F; Dias, Walter R; Melo, Paulo R

2013-01-01

Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching. Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values. One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I - 37% phosphoric acid (PA)+ ExciTE(®); Group II - ExciTE(®); Group III - AdheSE(®) self-etching; Group IV - FuturaBond(®) no-rinse. NR; Group V - Xeno(®) V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min. One-way ANOVA and post-hoc tests (P < 0.05). For the morphology evaluation, specimens were immersed in Ethylenediamine tetraacetic acid (EDTA) and the etching pattern analyzed under Scanning Electron Microscope (SEM). Mean bond strengths were Group I - 47.17 ± 1.61 MPa (type I etching pattern); Group II - 32.56 ± 1.64 MPa, Group III - 29.10 ± 1.34 MPa, Group IV - 23.32 ± 1.53 MPa (type III etching pattern); Group V - 24.43 MPa ± 1.55 (type II etching pattern). Different adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE(®) and ExciTE(®) without condition with PA. FuturaBond(®) NR and Xeno(®) V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used.

Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

PubMed

Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

2015-12-01

The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P < 0.05). In groups 3 and 4 at start and group 2 at start and 1 h after laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

YAG laser peripheral iridotomy for the prevention of pigment dispersion glaucoma a prospective, randomized, controlled trial.

PubMed

Scott, Andrew; Kotecha, Aachal; Bunce, Catey; Balidis, Miltos; Garway-Heath, David F; Miller, Michael H; Wormald, Richard

2011-03-01

To test the hypothesis that neodymium:yttrium-aluminum-garnet (Nd:YAG) laser peripheral iridotomy (LPI) significantly reduces the incidence of conversion from pigment dispersion syndrome (PDS) with ocular hypertension (OHT) to pigmentary glaucoma (PG). Prospective, randomized, controlled 3-year trial. One hundred sixteen eyes of 116 patients with PDS and OHT. Patients were assigned randomly either to Nd:YAG LPI or to a control group (no laser). The primary outcome measure was conversion to PG within 3 years, based on full-threshold visual field (VF) analysis using the Ocular Hypertension Treatment Study criteria. Secondary outcome measures were whether eyes required topical antiglaucoma medications during the study period and the time to conversion or medication. Fifty-seven patients were randomized to undergo laser treatment and 59 were randomized to no laser (controls). Age, gender, spherical equivalent refraction, and intraocular pressure at baseline were similar between groups. Outcome data were available for 105 (90%) of recruited subjects, 52 in the laser treatment group and 53 in the no laser treatment group. Patients were followed up for a median of 35.9 months (range, 10-36 months) in the laser arm and 35.9 months (range, 1-36 months) in the control arm. Eight eyes (15%) in the laser group and 3 eyes (6%) in the control group converted to glaucoma in the study period. The proportion of eyes started on medical treatment was similar in the 2 groups: 8 eyes (15%) in the laser group and 9 eyes (17%) in the control group. Survival analyses showed no evidence of any difference in time to VF progression or commencement of topical therapy between the 2 groups. Cataract extraction was performed on 1 patient in the laser group and in 1 patient in the control group during the study period (laser eye at 18 months; control eye at 34 months). This study suggests that there was no benefit of Nd:YAG LPI in preventing progression from PDS with OHT to PG within 3 years of

Comparative evaluation of surface topography of tooth prepared using erbium, chromium: Yttrium, scandium, gallium, garnet laser and bur and its clinical implications.

PubMed

Verma, Mahesh; Kumari, Pooja; Gupta, Rekha; Gill, Shubhra; Gupta, Ankur

2015-01-01

Erbium, chromium: Yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser has been successfully used in the ablation of dental hard and soft tissues. It has been reported that this system is also useful for preparing tooth surfaces and etching, but no consensus exist in the literature regarding the advantage of lasers over conventional tooth preparation technique. Labial surfaces of 25 extracted human maxillary central incisors were divided into two halves. Right half was prepared with diamond bur and left half with Er, Cr; YSGG laser and a reduction of 0.3-0.5 mm was carried out. Topography of prepared surfaces of five teeth were examined under scanning electron microscope (SEM). The remaining samples were divided into 4 groups of 10 specimens each based on the surface treatment received: One group was acid etched and other was nonetched. Composite resin cylinders were bonded on prepared surfaces and shear bond strength was assessed using a universal testing machine. The SEM observation revealed that the laser prepared surfaces were clean, highly irregular and devoid of a smear layer. Bur prepared surfaces were relatively smooth but covered with smear layer. Highest bond strength was shown by laser prepared acid etched group, followed by bur prepared the acid etched group. The bur prepared nonacid etched group showed least bond strength. Er, Cr: YSGG laser can be used for preparing tooth and bond strength value achieved by laser preparation alone without surface treatment procedure lies in the range of clinical acceptability.

Scintillation properties of Pr 3+-doped lutetium and yttrium aluminum garnets: Comparison with Ce 3+-doped ones

NASA Astrophysics Data System (ADS)

Mares, Jiri A.; Nikl, Martin; Beitlerova, Alena; Blazek, Karel; Horodysky, Petr; Nejezchleb, Karel; D'Ambrosio, Carmelo

2011-12-01

Scintillation properties of Pr 3+-doped LuAG and YAG crystals were investigated and compared with those of Ce 3+-doped ones. The highest L.Y.'s were observed with the longest shaping time 10 μs. They can reach up to ˜16,000 ph/MeV or ˜23,500 ph/MeV for LuAG:Pr and LuAG:Ce, respectively. Energy resolutions (FWHM) are a bit better with LuAG:Pr than those of LuAG:Ce, e.g. at 662 keV FWHM are around 6% and between 8-12%, respectively. There were observed no large changes in proportionality of Pr 3+- or Ce 3+-doped LuAG or YAG crystals but the best proportionality has YAP:Ce crystal. Pr 3+- or Ce 3+-doped LuAG crystals exhibit slow decay components in the time range 1.5-3.5 μs while those of YAG ones have shorter decay components between 0.3-1.7 μs.

Melanogenesis inhibition in mice using a low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser: a pilot study.

PubMed

Nam, Jae-Hui; Min, Joon Hong; Kim, Wang-Kyun; Yim, Sunmin; Kim, Won-Serk

2017-07-01

A low-fluence 1064-nm Q-switched neodymium-doped yttrium aluminum garnet laser, or laser toning, has yielded favorable outcomes in various benign pigmented disorders. However, the exact mechanism of action of laser toning has not been fully elucidated. We sought to determine the inhibitory effect of laser toning on melanogenesis and to assess how laser passes influence the outcomes. To produce perceptible pigmentation, nine HRM-2 melanin-possessing hairless mice were treated with ultraviolet (UV) B radiation on the dorsal skin. This was followed by zero, two, four, or six passes of laser toning twice in 2 weeks on each designated quadrant. The spectrophotometric values and pigmentation-related protein expressions were measured. Pigment changes were found in the mice skin using the Fontana-Masson stain for histopathological analysis. Four- and six-pass laser toning significantly improved the lightness compared to that in the unirradiated control (p < 0.002). The Fontana-Masson stain showed that melanin was considerably decreased in laser-irradiated skin. As the number of laser passes increased, the expression of tyrosinase decreased (p < 0.008). The following parameters also decreased in proportion to the number of laser passes: MITF, TRP-1, TRP-2, p-ERK, and p-Akt. In contrast, TGF-β increased in proportion to the number of laser passes. However, the changes in these six proteins were not statistically significant. Our study demonstrates that laser toning improves skin pigmentation with increased number of passes in a dose-dependent manner. This effect is mediated by tyrosinase inhibition.

Investigation of 2.1-micron lasing properties of Ho:Tm:Cr:YAG crystals under flash-lamp pumping at various operating conditions

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Choi, Young S.; Barnes, Norman P.; Hess, Robert V.; Bair, Clayton H.; Brockman, Philip

1993-01-01

Flash-lamp-pumped normal-mode and Q-switched 2.1-micron laser operations of Ho:Tm:Cr:YAG crystals have been evaluated under a wide variety of experimental conditions in order to determine an optimum lasing condition and to characterize the laser outputs. Q-switched laser-output energies equal to, or in some cases exceeding the normal-mode laser energies, were obtained in the form of a strong single spike through an optimization of the opening time of a lithium niobate Q switch. The increase of the normal-mode laser slope efficiency was observed with the increase of the Tm concentration from 2.5 to 4.5 at. pct at operating temperatures from 120 K to near room temperature. Laser transitions were observed only at 2.098 and 2.091 microns under various conditions. The 2.091-micron laser transition appeared to be dominant at high-temperature operations with low-reflective-output couplers.

The effect of an erbium, chromium: yttrium-scandium-gallium-garnet laser on the microleakage and bond strength of silorane and micro-hybrid composite restorations

PubMed Central

Korkmaz, Fatih Mehmet; Baygin, Ozgul; Tuzuner, Tamer; Bagis, Bora; Arslan, Ipek

2013-01-01

Objective: The aim of this in vitro study was to compare the microleakage and bond strength of Class V silorane-based and universal micro-hybrid composite restorations prepared either with diamond bur or with an erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr:YSGG) laser. Materials and Methods: A total of 160 molar teeth were used for microleakage assessment and shear bond strength (SBS) test. The specimens were prepared using either diamond bur or 3 W-, 4 W- and 5 W-20 Hz Er, Cr:YSGG laser irradiation. All specimens were subjected to thermocycling (500 times at 5 ± 2°C to 55 ± 2°C, dwell time 15 s and transfer time 10 s). Microleakage was assessed using a 0.5% basic-fuchsin solution. The bond strengths were determined using a microtensile tester at a crosshead speed of 0.5 mm/min. The Kruskal Wallis test was used for the analysis of microleakage and a one-way analysis of variance test was used to analyze the SBS (P < 0.05). Results: No statistically significant differences were found (P > 0.05) between Er, Cr:YSGG laser and bur preparation methods regarding microleakage and bond strength values. Conclusion: Irradiation with Er, Cr:YSGG laser was confirmed to be as effective as conventional methods for preparing cavities before adhesive restorations. PMID:24966726

Evaluation of microtensile and tensile bond strength tests determining effects of erbium, chromium: yttrium-scandium-gallium-garnet laser pulse frequency on resin-enamel bonding.

PubMed

Yildirim, T; Ayar, M K; Yesilyurt, C; Kilic, S

2016-01-01

The aim of the present study was to compare two different bond strength test methods (tensile and microtensile) in investing the influence of erbium, chromium: yttrium-scandium-gallium-garnet (Er, Cr: YSGG) laser pulse frequency on resin-enamel bonding. One-hundred and twenty-five bovine incisors were used in the present study. Two test methods were used: Tensile bond strength (TBS; n = 20) and micro-TBS (μTBS; n = 5). Those two groups were further split into three subgroups according to Er, Cr: YSGG laser frequency (20, 35, and 50 Hz). Following adhesive procedures, microhybrid composite was placed in a custom-made bonding jig for TBS testing and incrementally for μTBS testing. TBS and μTBS tests were carried out using a universal testing machine and a microtensile tester, respectively. Analysis of TBS results showed that means were not significantly different. For μTBS, the Laser-50 Hz group showed the highest bond strength (P < 0.05), and increasing frequency significantly increased bond strength (P < 0.05). Comparing the two tests, the μTBS results showed higher means and lower standard deviations. It was demonstrated that increasing μTBS pulse frequency significantly improved immediate bond strength while TBS showed no significant effect. It can, therefore, be concluded that test method may play a significant role in determining optimum laser parameters for resin bonding.

Prevention of pharyngocutaneous fistulas by means of laser-weld techniques.

PubMed

Shohet, J A; Reinisch, L; Ossoff, R H

1995-07-01

Although much has been written on methods of dealing with pharyngocutaneous fistulas once they have formed, there are few reports of methods of preventing fistula formation from occurring. We examined the use of laser-weld techniques with the neodymium:yttrium aluminum garnet (Nd:YAG) and diode lasers to seal pharyngotomy closures. Laser-weld techniques have been used successfully in many other tissues, but reports documenting use in the upper aerodigestive tract are minimal. Indocyanine-green dye-enhanced collagen and fibrinogen were studied as laser solder materials for the diode laser. Twenty-nine experimental animals were studied. Neither the Nd:YAG nor the diode laser was successful in preventing fistula formation. Tensiometric studies documented significant strength of the laser welds ex vivo, but this finding was not clinically significant.

Ceramic Laser Materials

PubMed Central

Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

2012-01-01

Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

Growth and anisotropic thermal properties of biaxial Ho:YAlO3 crystal

NASA Astrophysics Data System (ADS)

Dong, Qin; Zhao, Guangjun; Chen, Jianyu; Ding, Yuchong; Zhao, Chengchun

2010-07-01

Ho:YAlO3 (YAP) crystal with large size and good optical quality has been grown by the Czochralski method. Thermal properties of the as-grown Ho:YAP crystal have been investigated by measuring the temperature-dependent, anisotropic thermal expansion, specific heat, thermal diffusion, and thermal conductivity. The results show that Ho:YAP crystal possesses a large anisotropic thermal expansion and good thermal conductivity. The calculated average thermal expansion coefficients along a, b, and c axis are αa=9.18×10-6/K, αb=1.94×10-6/K, and αc=7.61×10-6/K from 293.15 to 770.15 K. The thermal conductivities along a, b, and c axis are up to 11.6, 9.9, and 12.3 W m-1 K-1 at 298.15 K. Compared with Ho: Y3Al5O12 (YAG), Ho:YAP crystal has a larger thermal conductivity along a axis from 298.15 to 568.15 K.

Effects of local structure of Ce3+ ions on luminescent properties of Y3Al5O12:Ce nanoparticles

PubMed Central

He, Xiaowu; Liu, Xiaofang; Li, Rongfeng; Yang, Bai; Yu, Kaili; Zeng, Min; Yu, Ronghai

2016-01-01

Ce3+-doped yttrium aluminum garnet (YAG:Ce) nanocrystals were successfully synthesized via a facile sol-gel method. Multiple characterization techniques were employed to study the structure, morphology, composition and photoluminescence properties of YAG:Ce nanophosphors. The YAG:Ce0.0055 sintered at 1030 °C exhibited a typical 5d1-4f1 emission band with the maximum peak located at 525 nm, and owned a short fluorescence lifetime τ1 (~28 ns) and a long fluorescence lifetime τ2 (~94 ns). Calcination temperature and Ce3+ doping concentration have significant effects on the photoluminescence properties of the YAG:Ce nanophosphors. The emission intensity was enhanced as the calcination temperature increased from 830 to 1030 °C, but decreased dramatically with the increase of Ce3+ doping concentration from 0.55 to 5.50 at.% due to the concentration quenching. By optimizing the synthesized condition, the strongest photoluminescence emission intensity was achieved at 1030 °C with Ce3+ concentration of 0.55 at.%. PMID:26935980

Removal of Dental Implants Using the Erbium,Chromium:Yttrium-Scandium-Gallium-Garnet Laser and the Conventional Trephine Bur: An in Vitro Comparative Study.

PubMed

Hajji, Mohammad; Franzen, Rene; Grümer, Stefan; Modabber, Ali; Nasher, Riman; Prescher, Andreas; Gutknecht, Norbert

2016-02-01

The purpose of this study was to compare the conventional trephine bur and the Erbium,chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser in removing implants in terms of the volume of removed bone, duration of the procedure, and morphological changes on the bone surface. Three human mandibles were utilized, and four implants were inserted in each mandible using a drilling handpiece and burs. The implants were divided into two groups (n = 6) in which two implants from each mandible were removed using a trephine bur running at 1200 rounds per minute (rpm) with water irrigation. The remaining implants (n = 6) were removed with Er,Cr:YSGG laser (power 6 W, frequency 20 Hz, pulse duration 50 μs, water 60, air 30). The volume of bone loss was calculated by filling the holes with mercury and measuring its volume. The preparation time was measured with a digital stopwatch and the postoperative bone surfaces were examined under a scanning electron microscope (SEM). The laser group exhibited a smaller amount of bone loss than the trephine bur group, whereas the latter required a shorter time of preparation. SEM revealed empty trabecular spaces with no signs of carbonization and well-defined edges in the laser group, whereas the trephine group displayed a surface covered with a smear layer and microcracks. The Er,Cr:YSGG laser provides superior results over the trephine bur in terms of bone preservation, thermal damage, and cutting efficiency.

Development of polarization-controlled multi-pass Thomson scattering system in the GAMMA 10 tandem mirror

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshikawa, M.; Morimoto, M.; Shima, Y.

2012-10-15

In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TSmore » system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.« less

Transmyocardial laser revascularization in the acute ischaemic heart: no improvement of acute myocardial perfusion or prevention of myocardial infarction.

PubMed

Eckstein, F S; Scheule, A M; Vogel, U; Schmid, S T; Miller, S; Jurmann, M J; Ziemer, G

1999-05-01

Transmyocardial laser revascularization (TMLR) has been used to provide enhanced myocardial perfusion in patients not suitable for coronary revascularization or angioplasty. This study investigates the acute changes in myocardial perfusion after TMLR with a Holmium:Yttrium-Aluminium-Garnet (YAG) laser with a thermal imaging camera in a model of acute ischaemia, and confirms its midterm effects by post-mortem investigation of magnetic resonance imaging and histopathological examination. Acute myocardial ischaemia was induced by occlusion of the dominant diagonal branch in ten sheep. Perfusion measurements were undertaken first in the unaffected myocardium, then after temporary occlusion of the coronary to obtain a control measurement for ischaemic myocardium. Myocardial perfusion was then evaluated during reperfusion after release of coronary occlusion. Then the coronary was permanently occluded and 20.5+/-2 channels were drilled with the Holmium:YAG laser and perfusion was measured again. The other four sheep served as control with untreated ischaemia. All animals were sacrificed after 28 days following administration of gadolinium i.v. to serve as contrast medium for magnetic resonance tomography. The hearts were subjected to magnetic resonance tomography and histopathological examination. Intraoperative perfusion measurements revealed a decreased perfusion after temporary occlusion and an increased perfusion in reperfused myocardium. After TMLR, no improvement of myocardial perfusion above the ischaemic level could be shown. Magnetic resonance images could neither confirm patent laser channels nor viable myocardium within ischaemic areas. On histology no patent endocardial laser channel could be detected. The transmural features were myocardial infarct with scar tissue. In the presented sheep model with acute ischaemia, TMLR with a Holmium:YAG laser did not provide acute improvement of myocardial perfusion as assessed by a thermal imaging camera. This would

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2000-01-01

The state of the global industrial garnet industry in 1999 is discussed. Industrial garnet mined in the U.S., which accounts for approximately one-third of the world's total, is usually a solid-solution of almandine and pyrope. The U.S. is the largest consumer of industrial garnet, using an estimated 47,800 st in 1999 as an abrasive and as a filtration medium in the petroleum industry, filtration plants, aircraft and motor vehicle manufacture, shipbuilding, wood furniture finishing operations, electronic component manufacture, ceramics manufacture, and glass production. Prices for crude concentrates ranged from approximately $50 to $110/st and refined garnet from $50 to $215/st in 1999, depending on type, source, quantity purchased, quality, and application.

Holmium laser lithotripsy (HoLL) of ureteral calculi

NASA Astrophysics Data System (ADS)

Kuntz, Rainer M.; Lehrich, Karin; Fayad, Amr

2001-05-01

The effectiveness and side effects of ureteroscopic HoLL of ureteral stones should be evaluated. In 63 patients (17 female, 46 males) a total of 75 stones of 3-20 mm diameter were treated with ureteroscopic HoLL. 18.7 percent of stones were located in the proximal third, 24.0 percent in the middle third and 57.3 percent in the distal third of the ureter. HoLL was performed with small diameter semirigid and flexible ureteroscopes, 220 or 365 nm flexible laser fibers and a holmium:YAG laser at a power of 5-15 W (0.5-1.0 J, 10- 15 Hz). 47 of 63 patients (74.6 percent) were immediately free of stones, and 8 others (12.6 percent) lost their residual fragments spontaneously within two weeks. Another 2 patients received additional chmolitholysis for uric acid stone fragments, i.e. 90.5 percent of patients were stone free by one sitting of ureterscopic HoLL. Of the remaining 6 patients (9.5 percent) who still had residual calculi 4 weeks after HoLL, 2 asymptomatic patients refused any additional treatment, 2 patients preferred treatment with ESWL, and 2 patients had a successful second HoLL, thereby raising the success rate of ureteroscopic HoLL to 93.7 percent. 2 patients showed contrast medium extravasation on retrograde ureterograms, due to guide wire perforation. No ureteral stricture occurred. In conclusion, transurethral ureteroscopic HoLL proved to be a safe and successful minimal invasive treatment of ureteral calculi.

High-pulse-energy 3.9-μm lasers in Ho:BYF

NASA Astrophysics Data System (ADS)

Stutz, Russell; Miller, Harold C.; Dinndorf, Kenneth M.; Cassanho, Arlete; Jenssen, Hans P.

2004-07-01

Experimental results describing pulsed lasers operating near 3.9 μm on the Ho3+ (5I5-5I6) transition in highly-doped (> 10 at. %) barium yttrium fluoride (BaY2F8 or BYF) will be presented. The 5I5 manifolds in Ho:BYF were pumped using a flashlamp excited, free-running Cr:LiSAF laser tuned to the Ho3+ absorption peak near 889nm. Ho3+ concentrations of 10%, 20%, 30% and 40% in BYF were lased in a simple end-pumped resonator. Some similar data was also obtained in 10% and 20% Ho:YLF. The highest 3.9 μm pulse energy obtained in the comparative study was 55 mJ (at ~10% optical-to-optical efficiency) using the 30% Ho:BYF crystal. A dual end-pumped laser in 30% Ho:BYF was also demonstrated, providing a pulse energy of 90 mJ in a near diffraction limited beam (M2 ~ 1.2). Emission decay data was taken to shed light on the observed dependence of laser efficiency on holmium concentration and excitation density. The lifetimes of both lasing levels (5I5 and 5I6) deviate rather significantly from their low-concentration values. Plausible energy transfer processes that may be responsible for the observed trends in the laser and emission data will also be discussed.

Implant Bed Preparation with an Erbium, Chromium Doped Yttrium Scandium Gallium Garnet (Er,Cr: YSGG) Laser Using Stereolithographic Surgical Guide

PubMed Central

Seymen, Gülin; Turgut, Zeynep; Berk, Gizem; Bodur, Ayşen

2013-01-01

Background: Implant bed preparation with laser is taken into consideration owing to the increased interest in use of lasers in hard tissue surgery. The purpose of this study is to determine the deviations in the position and inclination between the planned and prepared implant beds with Erbium, Chromium doped Yttrium Scandium Gallium Garnet (Er,Cr:YSGG) laser using stereolithographic (SLA) surgical guides. Methods: After 3-dimensional (3D) imaging of six sheep lower jaws, computed tomography (CT) images were transformed into 3D models. Locations of implant beds were determined on these models. Two implant beds in each half jaw were prepared with an Er,Cr:YSGG laser system and a conventional drilling method using a total of 12 SLA surgical guides. A new CT was taken to analyze the deviation values between planned and prepared implant beds. Finally, a software program was used to superimpose the images on 3D models, then the laser and conventional drilling groups were compared. Results: Differences of mean angular deviations between the planned and prepared implant beds were 5.17±4.91° in the laser group and 2.02±1.94° in the conventional drilling group.The mean coronal deviation values were found to be 0.48±0.25 mm and 0.23±0.14 mm in the laser group and conventional drilling group, respectively. While the mean deviation at the apex between the planned and prepared implant beds were 0.70±0.26 mm and 0.26±0.08 ,the mean vertical deviations were 0.06±0.15 mm and 0.02±0.05 mm for the laser group and the conventional drilling group, respectively. Conclusion: It is possible to prepare an implant bed properly with the aid of Er,Cr:YSGGlaser by using SLA surgical guide. PMID:25606303

Non-local detection of spin dynamics via spin rectification effect in yttrium iron garnet/SiO{sub 2}/NiFe trilayers near simultaneous ferromagnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soh, Wee Tee, E-mail: a0046479@u.nus.edu; Ong, C. K.; Peng, Bin

2015-08-15

The spin rectification effect (SRE), a phenomenon that generates dc voltages from ac microwave fields incident onto a conducting ferromagnet, has attracted widespread attention due to its high sensitivity to ferromagnetic resonance (FMR) as well as its relevance to spintronics. Here, we report the non-local detection of yttrium iron garnet (YIG) spin dynamics by measuring SRE voltages from an adjacent conducting NiFe layer up to 200 nm thick. In particular, we detect, within the NiFe layer, SRE voltages stemming from magnetostatic surface spin waves (MSSWs) of the adjacent bulk YIG which are excited by a shorted coaxial probe. These non-localmore » SRE voltages within the NiFe layer that originates from YIG MSSWs are present even in 200 nm-thick NiFe films with a 50 nm thick SiO{sub 2} spacer between NiFe and YIG, thus strongly ruling out the mechanism of spin-pumping induced inverse spin Hall effect in NiFe as the source of these voltages. This long-range influence of YIG dynamics is suggested to be mediated by dynamic fields generated from YIG spin precession near YIG/NiFe interface, which interacts with NiFe spins near the simultaneous resonance of both spins, to generate a non-local SRE voltage within the NiFe layer.« less

Optical and scintillation properties of Nd-doped complex garnet

NASA Astrophysics Data System (ADS)

Yanagida, Takayuki; Sato, Hiroki

2014-12-01

Nd 1% doped complex garnet scintillators were prepared by Furukawa and their optical and scintillation properties were investigated on a comparison with previously reported Nd-doped YAG. Chemical compositions of newly developed complex garnets were Lu2Y1Al5O12, Lu2Y1Ga3Al2O12, Lu2Gd1Al5O12, Lu2Gd1Ga3Al2O12, Gd1Y2Al5O12, Gd1Y2Ga3Al2O12, and Gd3Ga3Al2O12. They all showed 50-80% transmittance from ultraviolet to near infrared wavelengths with several absorption bands due to Gd3+ or Nd3+ 4f-4f transition. In X-ray induced radioluminescence spectra, all samples exhibited intense lines at 310 nm due to Gd3+ or 400 nm due to Nd3+ depending on their chemical composition. Among them, the highest scintillation light yield was achieved by Lu2Y1Al5O12. Typical scintillation decay times of them resulted 1.5-3 μs. Thermally stimulated glow curve after 1 Gy exposure and X-ray induced afterglow were also investigated.

Chemical properties of Garnets from Garnet Ridge, Navajo volcanic field in the Colorado Plateau

NASA Astrophysics Data System (ADS)

Koga, I.; Ogasawara, Y.

2012-12-01

Significant amounts of garnet crystals have derived from kimberlitic diatremes at Garnet Ridge in northern Arizona. These garnets are chemically diverse and their origins have been still controversial. The diatremes at Garnet Ridge were dated at 30Ma (Smith et al., 2004). Coesite-bearing lawsonite eclogite reported by Usui et al., (2003) is important evidence for subduction of the Fallaron Plate below the Colorado plateau. This study characterized various kinds of garnets with several origins by petrographical observations and electron microprobe analyses (JXA-8900 WDS mode and JXA-733 EDS mode). On the basis of the chemical compositions and other features, the garnets were classified into the following 8 groups (A to H). Inclusions and exsolved phases were identified by laser Raman spectroscopy. (A) Garnet crystals (5-8 mm) with purple color are called ''Navajo Ruby''. A significant amount of Cr2O3 is a typical feature (up to ~5.9 wt. %). These garnet were rich in pyrope (66-78 mol. %). Olivine, Cpx, and exsolved lamellae of rutile were contained. (B) Reddish brown garnets were Pyp-rich (60-75 mol. %), and contained a minor amount of Cr2O3 (less than ~1 wt. %). The inclusions were rod-shaped rutile , Cpx, Opx, zircon, olivine and exsolved lamellae of apatite. (C) Garnet megacrysts (8-12 cm) were plotted near the center of Prp-Alm-Grs triangle (Pyp30-35 Alm28-33 Grs29-35). Exsolved apatite lamellae were confirmed. (D) Some of reddish brown garnets were plotted on same area as the Type-C. (E) Garnets in eclogite have Alm-rich composition (Pyp6-22 Alm52-65 Grs16-42). They clearly showed prograde chemical zonation; MgO: 1.4 to 5.4 wt. %, CaO: 14.0 to 5.6 wt. % both from core to rim. (F) Garnets in altered or metasomatized eclogite had a wide range of chemical composition (Pyp7-38 Alm52-69 Grs4-31) with similar prograde zonation. The cores were plotted near the rim of Type-E garnet. (G) Garnets in unidentified rock (strongly altered) had Alm-rich composition near Alm

Relaxation of the environment of Gd3+ and Eu2+ impurity ions in the Y3Al5O12 garnet

NASA Astrophysics Data System (ADS)

Vazhenin, V. A.; Artyomov, M. Yu.; Potapov, A. P.; Chernyshev, V. A.; Fokin, A. V.; Serdtsev, A. V.

2017-05-01

The second-rank spin Hamiltonian parameters of Gd3+ and Eu2+ orthorhombic centers in crystals of the yttrium aluminum garnet Y3Al5O12 have been analyzed within the framework of the superposition model for the zero-field splitting of the ground state. It has been shown that the description of the experimental data in this model is possible only under the assumption of relaxation of the ligand environment of the paramagnetic impurity.

Numerical Response Surfaces of Volume of Ablation and Retropulsion Amplitude by Settings of Ho:YAG Laser Lithotripter

PubMed Central

Rutherford, Jonathan; Solomon, Metasebya; Cheng, Brian; Xuan, Jason R.; Gong, Jason; Yu, Honggang; Xia, Michael L. D.; Yang, Xirong; Hasenberg, Thomas; Curran, Sean

2018-01-01

Objectives Although laser lithotripsy is now the preferred treatment option for urolithiasis due to shorter operation time and a better stone-free rate, the optimal laser settings for URS (ureteroscopic lithotripsy) for less operation time remain unclear. The aim of this study was to look for quantitative responses of calculus ablation and retropulsion by performing operator-independent experiments to determine the best fit versus the pulse energy, pulse width, and the number of pulses. Methods A lab-built Ho:YAG laser was used as the laser pulse source, with a pulse energy from 0.2 J up to 3.0 J and a pulse width of 150 μs up to 1000 μs. The retropulsion was monitored using a high-speed camera, and the laser-induced craters were evaluated with a 3-D digital microscope. The best fit to the experimental data is done by a design of experiment software. Results The numerical formulas for the response surfaces of ablation speed and retropulsion amplitude are generated. Conclusions The longer the pulse, the less the ablation or retropulsion, while the longer pulse makes the ablation decrease faster than the retropulsion. The best quadratic fit of the response surface for the volume of ablation varied nonlinearly with pulse duration and pulse number. PMID:29707187

Rare Earth Laser Engineering Program. Part II.

DTIC Science & Technology

YTTRIUM ALUMINUM GARNET , NEAR INFRARED RADIATION, CONCENTRATION(CHEMISTRY), YTTRIUM COMPOUNDS, ALUMINUM COMPOUNDS, OXIDES, RELAXATION, RATES...VANADATES, DOPING, LANTHANUM, ERBIUM, HOLMIUM, GADOLINIUM COMPOUNDS, GARNET , TRANSPORT PROPERTIES, OSCILLATORS, LANTHANUM COMPOUNDS, FLUORIDES.

Canted ferrimagnetism in Ca2+Sc3+ substituted yttrium-iron-garnet

NASA Astrophysics Data System (ADS)

Pardavi-Horváth, M.; Thavendrarajah, A.; Wigen, P. E.; DeGasperis, P.

1988-11-01

The temperature dependence of the magnetization of Y3-y-zCayLuzFe5-xScxO12 (0.6≤x≤1.2, 0≤y≤0.3, 0≤z≤0.9) epitaxial garnet films was measured from 4.2 K up to the Curie temperature. For x=0.7 and T≥50 K, 4πMs is enhanced by about 10% compared to the magnetization of Sc0.7 YIG. At T<50 K, a reduction of the magnetization, increasing with increasing substitution, was observed for all the measured samples. Agreement between the experimental results and molecular field models was obtained by taking into account the canting of the unsubstituted sublattice, the presence of charge compensating Fe4+ ions, a low-temperature ordering of Fe3+ ions with less than two magnetic nearest neighbors, and assuming a lattice parameter-dependent exchange interaction ratio with d(Jdd/Jad)/da =28 nm.-1 For x=1.2 and T<10 K the magnetization can be influenced by cooling through the Curie point in a magnetic field.

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2006-01-01

In 2005, US production of crude garnet concentrate for industrial use was 28.4 kt valued at $3.05 million. Refined garnet material sold or used was 30.4 kt valued at $10 million. For the year, the US was one of the world's leading consumers of industrial garnet. Domestic values for crude concentrates for different applications ranged from about $53 to $120/t. In the short term, excess production capacity, combined with suppliers that vary in quality, grain size and mineral type, will keep prices down.

Optical properties and Faraday effect of ceramic terbium gallium garnet for a room temperature Faraday rotator.

PubMed

Yoshida, Hidetsugu; Tsubakimoto, Koji; Fujimoto, Yasushi; Mikami, Katsuhiro; Fujita, Hisanori; Miyanaga, Noriaki; Nozawa, Hoshiteru; Yagi, Hideki; Yanagitani, Takagimi; Nagata, Yutaka; Kinoshita, Hiroo

2011-08-01

The optical properties, Faraday effect and Verdet constant of ceramic terbium gallium garnet (TGG) have been measured at 1064 nm, and were found to be similar to those of single crystal TGG at room temperature. Observed optical characteristics, laser induced bulk-damage threshold and optical scattering properties of ceramic TGG were compared with those of single crystal TGG. Ceramic TGG is a promising Faraday material for high-average-power YAG lasers, Yb fiber lasers and high-peak power glass lasers for inertial fusion energy drivers.

A Q-switched Ho:YAG laser assisted nanosecond time-resolved T-jump transient mid-IR absorbance spectroscopy with high sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Deyong; Li, Yunliang; Li, Hao

2015-05-15

Knowledge of dynamical structure of protein is an important clue to understand its biological function in vivo. Temperature-jump (T-jump) time-resolved transient mid-IR absorbance spectroscopy is a powerful tool in elucidating the protein dynamical structures and the folding/unfolding kinetics of proteins in solution. A home-built setup of T-jump time-resolved transient mid-IR absorbance spectroscopy with high sensitivity is developed, which is composed of a Q-switched Cr, Tm, Ho:YAG laser with an output wavelength at 2.09 μm as the T-jump heating source, and a continuous working CO laser tunable from 1580 to 1980 cm{sup −1} as the IR probe. The results demonstrate thatmore » this system has a sensitivity of 1 × 10{sup −4} ΔOD for a single wavelength detection, and 2 × 10{sup −4} ΔOD for spectral detection in amide I′ region, as well as a temporal resolution of 20 ns. Moreover, the data quality coming from the CO laser is comparable to the one using the commercial quantum cascade laser.« less

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2012-01-01

Garnet has been used as a gemstone since the Bronze Age. However, garnet's angular fractures, relatively high hardness and specific gravity, chemical inertness, and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2011-01-01

Garnet has been used as a gemstone since the Bronze Age. However, garnet's angular fractures, relatively high hardness and specific gravity, chemical inertness and nontoxicity make it ideal for many industrial applications. It is also free of crystalline silica and can be recycled.

Damage induced in garnets by heavy ion irradiations: a study by optical spectroscopies

NASA Astrophysics Data System (ADS)

Costantini, Jean-Marc; Miro, Sandrine; Lelong, Gérald; Guillaumet, Maxime; Toulemonde, Marcel

2018-02-01

The damage induced by heavy-ion irradiation has been studied in yttrium iron garnet (Y3Fe5O12 or YIG) films, doped with Ca, Tb and Tm, grown by liquid-phase epitaxy on gadolinium gallium garnet (Gd3Ga5O12 or GGG) substrates. Irradiations of doped-YIG epitaxial films and GGG substrates with 36-MeV 183W and 12-MeV 197Au ions were applied for fluences between 1 × 1013 and 3 × 1015 cm-2 near room temperature. The radiation damage was monitored by micro-Raman spectroscopy and UV-visible optical absorption spectroscopy. Raman spectra revealed that amorphisation was achieved in YIG for both ions, whereas a high lattice disorder was induced in GGG without reaching amorphisation for the Au ion irradiation. Raman spectra also showed that a major damage of the tetrahedral sites was induced in GGG, as previously found for YIG. It is concluded that with such ions reaching the stopping power threshold of track formation in YIG and GGG the observed rate of amorphisation may result from a combination of electronic and nuclear energy losses as calculated using the unified thermal spike model.

Shear bond strength and SEM morphology evaluation of different dental adhesives to enamel prepared with ER:YAG laser

PubMed Central

Pires, Patrícia T.; Ferreira, João C.; Oliveira, Sofia A.; Azevedo, Álvaro F.; Dias, Walter R.; Melo, Paulo R.

2013-01-01

Context: Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching. Aims: Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values. Subjects and Methods: One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I – 37% phosphoric acid (PA)+ ExciTE®; Group II – ExciTE®; Group III – AdheSE® self-etching; Group IV – FuturaBond® no-rinse. NR; Group V – Xeno® V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min. Statistical Analysis Used: One-way ANOVA and post-hoc tests (P < 0.05). For the morphology evaluation, specimens were immersed in Ethylenediamine tetraacetic acid (EDTA) and the etching pattern analyzed under Scanning Electron Microscope (SEM). Results: Mean bond strengths were Group I – 47.17 ± 1.61 MPa (type I etching pattern); Group II – 32.56 ± 1.64 MPa, Group III – 29.10 ± 1.34 MPa, Group IV – 23.32 ± 1.53 MPa (type III etching pattern); Group V – 24.43 MPa ± 1.55 (type II etching pattern). Conclusions: Different adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE® and ExciTE® without condition with PA. FuturaBond® NR and Xeno® V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used. PMID:23853447

Holmium:YAG Laser Ablation for the Management of Lower Urinary Tract Foreign Bodies Following Incontinence Surgery: A Case Series and Systematic Review.

PubMed

Chan, Garson; Mamut, Adiel; Martin, Paul; Welk, Blayne

2016-11-01

The objective of this study was to determine the outcomes associated with the endoscopic removal of foreign bodies (such as mesh or permanent suture) in the lower urinary tract after female stress incontinence surgery with the Holmium:YAG (Ho:YAG) laser, and to systematically review the literature on this topic. A retrospective chart review of 18 consecutive women found to have mesh or suture exposure was performed. All patients underwent Ho:YAG laser ablation. A systematic review was performed to identify literature addressing the endoscopic management of mesh/suture exposure after stress incontinence surgery. Between November 2011 and February 2016, 18 women underwent Ho:YAG laser ablation of exposed mesh or suture. Presenting symptoms included lower urinary tract symptoms, pelvic pain, incontinence, or recurrent urinary tract infections. Thirteen women had a previous synthetic midurethral sling and five had a prior retropubic suspension. The median age was 58 years (interquartile range [IQR] 50-60) and median follow-up was 2 years (IQR 1-2). Four patients (22%) had residual mesh after the first procedure, requiring a repeat endoscopic procedure. Only one patient had a small amount of asymptomatic residual mesh on cystoscopy after the final procedure. Only minor postoperative complications were observed. Eight patients had stress incontinence and four underwent operative treatment for this. In our systematic review, we identified 16 case series, which described a total of 158 patients. Women most commonly presented with voiding symptoms or incontinence. Based on the synthesis of these data, repeat procedures were necessary in 16% and vesicovaginal fistula occurred in 2%. Recurrent/persistent stress incontinence was present in 20%, and of these patients, 3/4 underwent a new stress incontinence procedure. Both our case series and the systematic review of the literature demonstrated that endoscopic treatment of lower urinary tract foreign bodies after stress

Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

1991-01-01

Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

1999-01-01

Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet, and magnesium oxide.

Large energy pulse generation modulated by graphene epitaxially grown on silicon carbide.

PubMed

Yu, Haohai; Chen, Xiufang; Zhang, Huaijin; Xu, Xiangang; Hu, Xiaobo; Wang, Zhengping; Wang, Jiyang; Zhuang, Shidong; Jiang, Minhua

2010-12-28

Graphene grown by thermal decomposition of a two-inch 6H silicon carbide (SiC) wafers surface was used to modulate a large energy pulse laser. Because of its saturable absorbing properties, graphene was used as a passive Q-switcher, and because of its high refractive index the SiC substrate was used as an output coupler. Together they formed a setup where the passively Q-switched neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal laser was realized with the pulse energy of 159.2 nJ. Our results illustrate the feasibility of using graphene as an inexpensive Q-switcher for solid-state lasers and its promising applications in integrated optics.

Laser balancing system for high material removal rates

NASA Technical Reports Server (NTRS)

Jones, M. G.; Georgalas, G.; Ortiz, A. L.

1984-01-01

A laser technique to remove material in excess of 10 mg/sec from a spinning rotor is described. This material removal rate is 20 times greater than previously reported for a surface speed of 30 m/sec. Material removal enhancement was achieved by steering a focused laser beam with moving optics to increase the time of laser energy interaction with a particular location on the circumferential surface of a spinning rotor. A neodymium:yttrium aluminum garnet (Nd:YAG) pulse laser was used in this work to evaluate material removal for carbon steel, 347 stainless steel, Inconal 718, and titanium 6-4. This technique is applicable to dynamic laser balancing.

Synthesis and Luminescence Characteristics of Cr 3+ doped Y 3Al 5O 12 Phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Brenda A.; Dabestani, Reza T.; Lewis, Linda A.

2015-10-01

Luminescence performance of yttrium aluminum garnet (Y 3Al 5O 12) phosphors as a function of Cr 3+ concentration has been investigated via two different wet-chemical synthesis techniques, direct- (DP) and hydrothermal-precipitation (HP). Using either of these methods, the red-emitting phosphor [Y 3Al 5-xCr xO 12 (YAG: Cr 3+)] showed similar photoluminescence (PL) intensities once the dopant concentration was optimized. Specifically, the YAG: Cr 3+ PL emission intensity reached a maximum at Cr3+ concentrations of x = 0.02 (0.4 at.%) and x = 0.13 (2.6 at.%) for DP and HP processed samples, respectively. The results indicated the strong influence of themore » processing method on the optimized YAG: Cr 3+ performance, where a more effective energy transfer rate between a pair of Cr3+ activators at low concentration levels was observed by using the DP synthesis technique. Development of a highly efficient phosphor, using a facile synthesis approach, could significantly benefit consumer and industrial applications by improving the operational efficiency of a wide range of practical devices.« less

Superresolution Microscopy of Single Rare-Earth Emitters in YAG and H 3 Centers in Diamond

NASA Astrophysics Data System (ADS)

Kolesov, R.; Lasse, S.; Rothfuchs, C.; Wieck, A. D.; Xia, K.; Kornher, T.; Wrachtrup, J.

2018-01-01

We demonstrate superresolution imaging of single rare-earth emitting centers, namely, trivalent cerium, in yttrium aluminum garnet crystals by means of stimulated emission depletion (STED) microscopy. The achieved all-optical resolution is ≈50 nm . Similar results were obtained on H 3 color centers in diamond. In both cases, STED resolution is improving slower than the conventional inverse square-root dependence on the depletion beam intensity. In the proposed model of this effect, the anomalous behavior is caused by excited state absorption and the interaction of the emitter with nonfluorescing crystal defects in its local surrounding.

The role of trace element partitioning between garnet, zircon and orthopyroxene on the interpretation of zircon U-Pb ages: an example from high-grade basement in Calabria (Southern Italy)

NASA Astrophysics Data System (ADS)

Fornelli, A.; Langone, A.; Micheletti, F.; Pascazio, A.; Piccarreta, G.

2014-03-01

The recognition of the coeval growth of zircon, orthopyroxene and garnet domains formed during the same metamorphic cycle has been attempted with detailed microanalyses coupled with textural analyses. A coronitic garnet-bearing granulite from the lower crust of Calabria has been considered. U-Pb zircon data and zircon, garnet and orthopyroxene chemistries, at different textural sites, on a thin section of the considered granulite have been used to test possible equilibrium and better constrain the geological significance of the U-Pb ages related to zircon separates from other rocks of the same structural level. The garnet is very rich in REE and is characterised by a decrease in HREE from core to outer core and an increase in the margin. Zircons show core-overgrowth structures showing different chemistries, likely reflecting episodic metamorphic new growth. Zircon grains in matrix, corona around garnet and within the inner rim of garnet, are decidedly poorer in HREE up to Ho than garnet interior. Orthopyroxene in matrix and corona is homogeneously poor in REE. Thus, the outer core of garnet and the analysed zircon grains grew or equilibrated in a REE depleted system due to the former growth of garnet core. Zircon ages ranging from 357 to 333 Ma have been determined in the matrix, whereas ages 327-320 Ma and around 300 Ma have been determined, respectively, on cores and overgrowths of zircons from matrix, corona and inner rim of garnet. The calculated DREEzrn/grt and DREEopx/grt are largely different from the equilibrium values of literature due to strong depletion up to Ho in zircon and orthopyroxene with respect to garnet. On the other hand, the literature data show large variability. In the case study, (1) the D zrn/grt values define positive and linear trends from Gd to Lu as many examples from literature do and the values from Er to Lu approach the experimental results at about 900 °C in the combination zircon dated from 339 to 305 Ma with garnet outer core

Industrial garnet

USGS Publications Warehouse

Olson, D.W.

2010-01-01

In 2009, U.S. production of crude garnet concentrate for industrial use was estimated to be 56.5 kt (62,300 st), valued at about $8.85 million. This was a 10-percent decrease in quantity compared with 2008 production. Refined garnet material sold or used was 28 kt (31,000 st) valued at $7.96 million.

Short-term clinical results of knee arthroscopy utilizing the 1.44-um Nd:YAG laser

NASA Astrophysics Data System (ADS)

Maes, Kirk E.; Cummings, Robert S.; Mooar, Pekka A.; Sherk, Henry H.

1994-09-01

Two orthopedic surgeons performed 27 knee arthroscopies on 26 patients using the 1.44 micrometers Nd:YAG. Mean patient age was 52.6 years. Six patients had their entire procedure done using the Nd:YAG alone and 20 had their procedures done using both the laser and a conventional arthroscopic side-shaver. Three patients had an additional knee procedure done immediately following their arthroscopy. The mean operative procedure time was 47.25 minutes (SD equals 14.75). The mean energy setting used was 2.2 Joules/Pulse (SD equals 0.89), mean frequency 16.6 Hz (SD equals 6.4), and mean total energy delivered was 9418.7 Joules (SD equals 6032.5). There were 15 patients with a minimum follow-up of at least 4 weeks (mean 8.26 weeks). The final results showed 35% returned to normal baseline, 43% improved from pre-op condition, and 21% were the same as pre-op. None of the patients were worse. The 1.44 micrometers Nd:YAG has a water absorption coefficient nearly identical to the 2.1 micrometers Ho:YAG, which is currently a popular arthroscopic tool. We conclude that the 1.44 micrometers Nd:YAG is an effective alternative for arthroscopic procedures of the knee.

Molecular field coefficients and cation distribution of substituted yttrium iron garnets

NASA Astrophysics Data System (ADS)

Röschmann, P.; Hansen, P.

1981-10-01

The saturation magnetization Ms(T) of Ga, Al, Sc, and CaVBi substituted Y3Fe5O12 (YIG) single crystals and of polycrystalline Ca/Ge and Ca/Ti substituted YIG has been investigated for 4.2 K ⩽T⩽TC. The samples were repeatedly annealed and quenched at different equilibrium temperatures 773 K⩽Te ⩽1523 K. The attained site exchange of Fe and the substituents between the a and d sites resulted in considerable changes of Ms(T). From a fit of the Néel molecular field theory to the Ms(T) data the dependence of the magnetic moments at T = 0 K and of the molecular field coefficients on the amount of nonmagnetic substitutions on the a and d sites were determined. It turned out that ion-specific sets of equations are required accounting for the ''particular ion effect'' of different cation species. The cation distributions inferred from the magnetic data have been analyzed along with a thermodynamic equilibrium model. The derived site stabilizing energies for the mixed Fe-Ga and Fe-Al garnets agree well with recently reported data. New results are presented for the site stabilizing energies in Ca/Ge:YIG and for the substituents Sc and Ti with octahedral site preference.

12 mJ Yb:YAG/Cr:YAG microchip laser

NASA Astrophysics Data System (ADS)

Guo, Xiaoyang; Tokita, Shigeki; Kawanaka, Junji

2018-02-01

By cryogenically cooling the Yb:YAG/Cr:YAG medium, one can break through the damage limit of Yb:YAG/Cr:YAG passively Q-switched microchip lasers at room temperature and thus achieve a shorter minimum pulse duration. In the proof of principle experiment we carried out, a 160.6 ps pulse duration was obtained. To the best of our knowledge, this is the first realization of sub-200 ps pulse operation for an Yb:YAG/Cr:YAG microchip laser

Chapter L: U.S. Industrial Garnet

USGS Publications Warehouse

Evans, James G.; Moyle, Phillip R.

2006-01-01

The United States presently consumes about 16 percent of global production of industrial garnet for use in abrasive airblasting, abrasive coatings, filtration media, waterjet cutting, and grinding. As of 2005, domestic garnet production has decreased from a high of 74,000 t in 1998, and imports have increased to the extent that as much as 60 percent of the garnet used in the United States in 2003 was imported, mainly from India, China, and Australia; Canada joined the list of suppliers in 2005. The principal type of garnet used is almandite (almandine), because of its specific gravity and hardness; andradite is also extensively used, although it is not as hard or dense as almandite. Most industrial-grade garnet is obtained from gneiss, amphibolite, schist, skarn, and igneous rocks and from alluvium derived from weathering and erosion of these rocks. Garnet mines and occurrences are located in 21 States, but the only presently active (2006) mines are in northern Idaho (garnet placers; one mine), southeastern Montana (garnet placers; one mine), and eastern New York (unweathered bedrock; two mines). In Idaho, garnet is mined from Tertiary and (or) Quaternary sedimentary deposits adjacent to garnetiferous metapelites that are correlated with the Wallace Formation of the Proterozoic Belt Supergroup. In New York, garnet is mined from crystalline rocks of the Adirondack Mountains that are part of the Proterozoic Grenville province, and from the southern Taconic Range that is part of the northern Appalachian Mountains. In Montana, sources of garnet in placers include amphibolite, mica schist, and gneiss of Archean age and younger granite. Two mines that were active in the recent past in southwestern Montana produced garnet from gold dredge tailings and saprolite. In this report, we review the history of garnet mining and production and describe some garnet occurrences in most of the Eastern States along the Appalachian Mountains and in some of the Western States where

Cost savings associated with the use of the Ho:YAG laser in knee arthroscopy: a comparative retrospective review of 140 conventional and laser-assisted procedures

NASA Astrophysics Data System (ADS)

Johnson, Michael D.

1994-09-01

The impact of using the 2.1 micrometers Ho:YAG laser in orthopaedic surgery has not been fully investigated, especially as to what affect it may have on an employee's return to work and normal activities. In this retrospective review of 140 patients who underwent arthroscopic surgery at our facility, there were found to be significant decreases in time on crutches and time off from work when laser-assisted knee arthroscopies were compared to procedures where conventional mechanical or motorized instruments were used. The patients who had laser-assisted knee arthroscopies discontinued use of crutches 5 days earlier than the conventional group and returned to work 10 days earlier than their counterparts who had undergone conventional arthroscopic surgery. The ability to return to work more quickly translates into significant cost savings for employers who otherwise would have to replace the worker with temporary help, pay overtime, or face lost productivity due to an employee's absence following arthroscopic knee surgery.

Timing capabilities of garnet crystals for detection of high energy charged particles

NASA Astrophysics Data System (ADS)

Lucchini, M. T.; Gundacker, S.; Lecoq, P.; Benaglia, A.; Nikl, M.; Kamada, K.; Yoshikawa, A.; Auffray, E.

2017-04-01

Particle detectors at future collider experiments will operate at high collision rates and thus will have to face high pile up and a harsh radiation environment. Precision timing capabilities can help in the reconstruction of physics events by mitigating pile up effects. In this context, radiation tolerant, scintillating crystals coupled to silicon photomultipliers (SiPMs) can provide a flexible and compact option for the implementation of a precision timing layer inside large particle detectors. In this paper, we compare the timing performance of aluminum garnet crystals (YAG: Ce, LuAG: Ce, GAGG: Ce) and the improvements of their time resolution by means of codoping with Mg2+ ions. The crystals were read out using SiPMs from Hamamatsu glued to the rear end of the scintillator and their timing performance was evaluated by measuring the coincidence time resolution (CTR) of 150 GeV charged pions traversing a pair of crystals. The influence of crystal properties, such as density, light yield and decay kinetics on the timing performance is discussed. The best single detector time resolutions are in the range of 23-30 ps (sigma) and only achieved by codoping the garnet crystals with divalent ions, such as Mg2+. The much faster scintillation decay in the co-doped samples as compared to non co-doped garnets explains the higher timing performance. Samples of LSO: Ce, Ca and LYSO:Ce crystals have also been used as reference time device and showed a time resolution at the level of 17 ps, in agreement with previous results.

Durability of resin cement bond to aluminium oxide and zirconia ceramics after air abrasion and laser treatment.

PubMed

Foxton, Richard M; Cavalcanti, Andrea N; Nakajima, Masatoshi; Pilecki, Peter; Sherriff, Martyn; Melo, Luciana; Watson, Timothy F

2011-02-01

The erbium laser has been introduced for cutting enamel and dentin and may have an application in the surface modification of high-strength aluminum oxide and zirconia ceramics. The aim of this study was to evaluate the durability of the bond of conventional dual-cured resin cements to Procera Al(2)O(3) and zirconium oxide ceramics after surface treatment with air abrasion and erbium laser. One hundred twenty Al(2)O(3) and 120 zirconia specimens measuring 3 × 3 × 0.7 mm(3) were divided equally into three groups, and their surfaces treated as follows: either untreated (controls), air abraded with Al(2)O(3) particles, or erbium-laser-treated at a power setting of 200 mJ. The surface of each specimen was then primed and bonded with one of two dual-cured resin cements (either SCP-100 Ceramic Primer and NAC-100 or Monobond S and Variolink II) using a 1-mm thick Tygon tube mold with a 0.75-mm internal bore diameter. After 24 hours and 6 months of water storage at 37°C, a microshear bond strength test was performed at a crosshead speed of 1 mm/min. Surface morphology was examined using a confocal microscope, and failure modes were observed using an optical microscope. The data were analyzed using the Kaplan-Meier nonparametric survival analysis. In the case of zirconia, air abrasion and Erbium:yttrium-aluminum-garnet (Er:YAG) laser treatment of the ceramic surface resulted in a significant reduction in the bond strengths of both resin cements after 6 months water storage; however, when the zirconia surface was left untreated, the SCP-100/NAC-100 group did not significantly reduce in bond strength. In the case of alumina, no treatment, air abrasion and Er:YAG laser treatment of the surface led to no significant reduction in the bond strengths of the three SCP-100/NAC-100 groups after 6 months water storage, whereas all three Monobond S/Variolink II groups showed a significant reduction. Er:YAG laser treatment of the zirconia surface did not result in a durable resin

Long-term efficacy of microbiology-driven periodontal laser-assisted therapy.

PubMed

Martelli, F S; Fanti, E; Rosati, C; Martelli, M; Bacci, G; Martelli, M L; Medico, E

2016-03-01

Periodontitis represents a highly prevalent health problem, causing severe functional impairment, reduced quality of life and increased risk of systemic disorders, including respiratory, cardiovascular and osteoarticular diseases, diabetes and fertility problems. It is a typical example of a multifactorial disease, where a polymicrobial infection inducing chronic inflammation of periodontal tissues is favoured by environmental factors, life style and genetic background. Since periodontal pathogens can colonise poorly vascularised niches, antiseptics and antibiotics are typically associated with local treatments to manage the defects, with unstable outcomes especially in early-onset cases. Here, the results of a retrospective study are reported, evaluating the efficacy of a protocol (Periodontal Biological Laser-Assisted Therapy, Perioblast™) by which microbial profiling of periodontal pockets is used to determine the extent and duration of local neodymium-doped yttrium aluminium garnet (Nd:YAG) laser irradiation plus conventional treatment. The protocol was applied multicentrically on 2683 patients, and found to produce a significant and enduring improvement of all clinical and bacteriological parameters, even in aggressive cases. Microbiome sequencing of selected pockets revealed major population shifts after treatment, as well as strains potentially associated with periodontitis in the absence of known pathogens. This study, conducted for the first time on such a large series, clearly demonstrates long-term efficacy of microbiology-driven non-invasive treatment of periodontal disease.