WorldWideScience

Sample records for laser-assisted laser ablation

  1. Laser-assisted electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glenn, D.F.

    1995-05-01

    The effect of laser irradiation on electrodeposition processes has been investigated. These studies demonstrated that the addition of laser irradiation to an electroplating process can dramatically enhance plating rates and current efficiencies, as well as improve the morphology of the resultant electrodeposit. During the course of these investigations, the mechanism for the laser enhancement of electrodeposition processes was determined. Experimental evidence was obtained to show that laser irradiation of the substrate results in increased metal ion concentrations at the surface of the electrode due to a laser-induced Soret effect. The laser-induced Soret effect has important implications for laser-assisted electrochemical processing. The increase in the surface concentration of ions allows efficient electrodeposition from dilute solutions. As such, laser- assisted electrodeposition may develop into an environmentally conscious manufacturing process by reducing waste and limiting worker exposure to toxic chemicals.

  2. Impact of different vehicles for laser-assisted drug permeation via skin: full-surface versus fractional ablation.

    Science.gov (United States)

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

    2014-02-01

    This study aimed to assess impact of different vehicles for laser-assisted skin drug delivery. We also tried to uncover the mechanisms by which different vehicles affect laser-aided skin permeation. Full-surface ablative (conventional) and fractional lasers were used to irradiate nude mouse skin. Imiquimod and 5-aminolevulinic acid (ALA) were used as lipophilic and hydrophilic permeants. Vehicles employed included water with 40% polyethylene glycol 400 (PEG 400), propylene glycol (PG), and ethanol. Lipid nanoparticles were also utilized as carriers. In vitro permeation profiles showed improvement in imiquimod flux with conventional laser (2.5 J/cm2) producing a 12-, 9-, and 5-fold increase when loading imiquimod in 40% PEG400, PG, and ethanol, respectively, as compared with intact skin. Nanoparticulate delivery by laser produced a 6-fold enhancement in permeation. Fractional laser produced less enhancement of imiquimod delivery than conventional laser. Laser exposure increased follicular imiquimod accumulation from 0.80 to 5.81 μg/cm2. ALA permeation from aqueous buffer, PEG 400, and PG with conventional laser treatment was 641-, 445-, and 104-fold superior to passive control. In vivo skin deposition of topically applied ALA examined by confocal microscopy indicated the same trend as the in vitro experiment, with aqueous buffer showing the greatest proporphyllin IX signaling. Diffusion of cosolvent molecules into ablated skin and drug partitioning from vehicle to skin are two predominant factors controlling laser-assisted delivery. In contrast to conventional laser, lateral drug diffusion was anticipated for fractional laser. Our results suggest that different drug delivery vehicles substantially influence drug penetration enhanced by lasers.

  3. Ultrasound guided ablative-laser assisted photodynamic therapy of basal cell carcinoma (US-aL-PDT).

    Science.gov (United States)

    Smucler, Roman; Kriz, Martin; Lippert, Jan; Vlk, Marek

    2012-04-01

    With proper noninvasive ultrasound measurement of tumor depth, case selection for laser pre-ablation followed by PDT is possible. This combination of methods provides a less invasive approach to the treatment of BCC. Basal cell carcinoma (BCC) primarily affects the face, and, therefore, radical excision is problematic because of the possibility of poor aesthetic outcomes. Photodynamic therapy (PDT) offers an advantage in aesthetic outcomes, but topical PDT is only effective for tumors with a depth up to 2 mm. Seventy-five histologically verified BCCs from 67 patients were selected and divided into three therapeutic groups based on the tumor depth, which was determined by 20 MHz skin ultrasound. The three groups were: A/PDT), B/ 2-3 mm (Er:YAG laser ablation+PDT), and C/>3 mm (diode laser ablation+PDT). The treatment consisted of laser ablation (or no ablation) followed by the application of methyl-aminolevulinate (MAL) and a 3-h treatment period using an occlusive bandage. Subsequently, illumination with 630 nm (MAL-PDT) was performed. MAL-PDT was repeated 1-3 weeks after the first treatment. A clinical evaluation was performed after 6 months. A 100% clearance rate (CR) in the group with the deepest tumors was observed. In addition, a 94.7% CR occurred in the group with tumors 2-3 mm in depth, and an 81.2% CR was observed in the group with superficial tumors. With proper ultrasound case selection and laser ablation before MAL-PDT, the depth of a BCC lesion is not a limiting factor for PDT, and aesthetic outcomes are very good. Therefore, ultrasound-guided ablative laser-assisted PDT of BCC can be the method of choice, particularly in aesthetically challenging cases.

  4. Ablative Fractional Laser Resurfacing With Laser-Assisted Delivery of 5-Fluorouracil for the Treatment of Cicatricial Ectropion and Periocular Scarring.

    Science.gov (United States)

    Lee, Bradford W; Levitt, Alexandra E; Erickson, Benjamin P; Ko, Audrey C; Nikpoor, Neda; Ezuddin, Nisreen; Lee, Wendy W

    2017-06-27

    Cicatricial ectropion and periocular scarring can cause significant functional and cosmetic deficits. Surgical treatments can be associated with recicatrization, donor site morbidity, and textural and pigmentary abnormalities. This case series reports on efficacy and safety of a novel nonsurgical approach to treating cicatricial ectropion using ablative fractional laser resurfacing and laser-assisted delivery of 5-fluorouracil. A retrospective review was conducted of all patients at a single institution who received ≥3 rounds of ablative fractional laser resurfacing with laser-assisted delivery of 5-fluorouracil. Six patients with cicatricial ectropion and periocular scarring secondary to reconstructive surgery, traumatic lacerations, and facial burns were included. Aesthetic and functional improvement were evaluated via fluorescein staining, tear breakup time, external photography, questionnaires gauging dry eye symptoms, and scar appearance. All patients showed functional improvement based on fluorescein staining (mean improvement 6.0 ± 1.4; p = 0.0007) and other indicators of dry eye. All 4 patients with lagophthalmos improved and 2 showed complete resolution. All patients demonstrated significant cosmetic improvement based on a validated scar assessment questionnaire (mean improvement 37.5 ± 18.9; p = 0.004), and 5 of 6 patients reported improved satisfaction with scar appearance (mean improvement 19.3 ± 12.8; p = 0.014). There were no adverse effects reported. Ablative fractional laser resurfacing with laser-assisted delivery of 5-fluorouracil appears to be a safe and effective modality for treating the functional and aesthetic abnormalities associated with periocular scarring, yielding results that are difficult to attain through surgery alone. Optimal management of cicatricial ectropion and periocular scarring often requires multimodality treatment, and ablative fractional laser resurfacing with laser-assisted delivery of 5-fluorouracil may be

  5. Skin pre-ablation and laser assisted microjet injection for deep tissue penetration.

    Science.gov (United States)

    Jang, Hun-Jae; Yeo, Seonggu; Yoh, Jack J

    2017-04-01

    For conventional needless injection, there still remain many unresolved issues such as the potential for cross-contamination, poor reliability of targeted delivery dose, and significantly painstaking procedures. As an alternative, the use of microjets generated with Er:YAG laser for delivering small doses with controlled penetration depths has been reported. In this study, a new system with two stages is evaluated for effective transdermal drug delivery. First, the skin is pre-ablated to eliminate the hard outer layer and second, laser-driven microjet penetrates the relatively weaker and freshly exposed epidermis. Each stage of operation shares a single Er:YAG laser that is suitable for skin ablation as well as for the generation of a microjet. In this study, pig skin is selected for quantification of the injection depth based on the two-stage procedure, namely pre-ablation and microjet injection. The three types of pre-ablation devised here consists of bulk ablation, fractional ablation, and fractional-rotational ablation. The number of laser pulses are 12, 18, and 24 for each ablation type. For fractional-rotational ablation, the fractional beams are rotated by 11.25° at each pulse. The drug permeation in the skin is evaluated using tissue marking dyes. The depth of penetration is quantified by a cross sectional view of the single spot injections. Multi-spot injections are also carried out to control the dose and spread of the drug. The benefits of a pre-ablation procedure prior to the actual microjet injection to the penetration is verified. The four possible combinations of injection are (a) microjet only; (b) bulk ablation and microjet injection; (c) fractional ablation and microjet injection; and (d) fractional-rotational ablation and microjet injection. Accordingly, the total depth increases with injection time for all cases. In particular, the total depth of penetration attained via fractional pre-ablation increased by 8 ∼ 11% and that of fractional

  6. Gold nanoshell/polysaccharide nanofilm for controlled laser-assisted tissue thermal ablation.

    Science.gov (United States)

    Redolfi Riva, Eugenio; Desii, Andrea; Sinibaldi, Edoardo; Ciofani, Gianni; Piazza, Vincenzo; Mazzolai, Barbara; Mattoli, Virgilio

    2014-06-24

    We report on the fabrication and characterization of a freestanding ultrathin, mucoadhesive gold nanoshell/polysaccharide multilayer nanocomposite (thermonanofilm, TNF), that can be used for controlled photothermal ablation of tissues through irradiation with near-infrared radiation (NIR) laser. The aim of this work is to provide a new strategy to precisely control particle concentration during photothermalization of cancerous lesions, since unpredictable and aspecific biodistributions still remains the central issue of inorganic nanoparticle-assisted photothermal ablation. Gold nanoshell encapsulation in polysaccharide matrix is achieved by drop casting deposition method combined with spin-assisted layer-by-layer (LbL) assembly. Submicrometric thickness of films ensures tissue adhesion. Basic laser-induced heating functionality has been demonstrated by in vitro TNF-mediated thermal ablation of human neuroblastoma cancer cells, evidenced by irreversible damage to cell membranes and nuclei. Ex vivo localized vaporization and carbonization of animal muscular tissue is also demonstrated by applying TNF onto tissue surface. Thermal distribution in the tissue reaches a steady state in a few seconds, with significant increases in temperature (ΔT > 50) occurring across an 1 mm span, ensuring control of local photothermalization and providing more safety and predictability with respect to traditional laser surgery. A steady-state model of tissue thermalization mediated by TNFs is also introduced, predicting the temperature distribution being known the absorbance of TNFs, the laser power, and the tissue thermal conductivity, thus providing useful guidelines in the development of TNFs. Thermonanofilms can find applications for local photothermal treatment of cancerous lesions and wherever high precision and control of heat treatment is required.

  7. Laser-assisted fabrication and size distribution modification of colloidal gold nanostructures by nanosecond laser ablation in different liquids

    Science.gov (United States)

    Nikov, R. G.; Nedyalkov, N. N.; Atanasov, P. A.; Karashanova, D. B.

    2017-07-01

    This study presents results on pulsed laser ablation of gold target immersed in different liquids. In the experiments chloroform, toluene and ethanol are used as liquid media for the laser ablation. Two different wavelengths: the fundamental (1064 nm) and second harmonic (532 nm) of a Nd:YAG laser, are utilized to produce various colloids. The optical properties of the colloids were evaluated by optical transmittance measurements in the UV-Vis spectral range. The morphology of the colloidal nanoparticles created and the evaluation of their size distribution are investigated by transmission electron microscopy. The selected area electron diffraction is employed for chemical phase identification of the created nanostructures. Ablation in chloroform resulted in formation of spherical and spheroidal gold nanoparticles with the similar mean size at both laser wavelengths used—11.5 nm at 1064 and 9.3 nm at 532 nm. Nanoparticles with smaller mean size (below 5 nm) in the case of ablation in toluene were observed. Spherical nanoparticles with mean diameter of 7.7 nm produced by 1064 nm and thin elongated nanostructures with thickness of about 5 nm using 532 nm are observed in the case of ablation in ethanol. An additional laser irradiation of the colloids demonstrated the changing of the optical properties and size distribution of the nanostructures produced by ablation in ethanol and chloroform. The irradiation of toluene-based colloid does not induce observable change of the colloid properties.

  8. Laser assisted graffiti paints removing

    Science.gov (United States)

    Novikov, B. Y.; Chikalev, Y. V.; Shakhno, E. A.

    2011-02-01

    It's hard to imagine a modern city view without some drawings and inscriptions, usually called "graffiti". Traditional cleaning methods do not suit modern requirements. Investigation of possibilities of laser assisted paints removing is described in this article. The conditions for removing different paints from different surfaces were defined.

  9. Laser Assisted Microsurgical Anastomosis.

    Science.gov (United States)

    1983-09-22

    our axoral transport platophysiological and ultravascular findings indicat to be inferior ll. to laser epineurial repair, conventional microsurgical...ventral motoneurons . Experimental Neurology, 21:41-51, 1968. 21. Marinacci, AA: Diagnosis of "all median hand". 22. Marinacci, AA: The problem of unusual

  10. Non-ablative fractional laser assists cutaneous delivery of small- and macro-molecules with minimal bacterial infection risk.

    Science.gov (United States)

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Aljuffali, Ibrahim A; Lin, Yin-Ku; Huang, Chang-Wei; Fang, Jia-You

    2016-09-20

    Use of the ablative laser has been approved to enhance topical drug penetration. Investigation into the usefulness of the non-ablative laser for assisting drug delivery is very limited. In this study, we explored the safety and efficacy of the non-ablative fractional erbium:glass (Er:glass) laser as an enhancement approach to promote drug permeation. Both pig and nude mouse skins were employed as transport barriers. We histologically examined the skin structure after laser exposure. The permeants of 5-aminolevulinic acid (ALA), imiquimod, tretinoin, peptide, dextrans and quantum dots (QD) were used to evaluate in vitro and in vivo skin passage. The fractional laser selectively created an array of photothermal dots deep into the dermis with the preservation of the stratum corneum and epidermis. The barrier function of the skin could be recovered 8-60h post-irradiation depending on the laser spot densities. The application of the laser caused no local infection of Staphylococcus aureus and Pseudomonas aeruginosa. Compared to intact skin, ALA flux was enhanced up to 1200-fold after laser exposure. The penetration enhancement level by the laser was decreased following the increase of permeant lipophilicity. The skin accumulation of tretinoin, an extremely lipophilic drug, showed only a 2-fold elevation by laser irradiation. The laser promoted peptide penetration 10-fold compared to the control skin. Skin delivery of dextrans with a molecular weight (MW) of at least 40kDa could be achieved with the Er:glass laser. QD with a diameter of 20nm penetrated into the skin with the assistance of the non-ablative laser. The confocal microscopic images indicated the perpendicular and lateral diffusions of dextrans and nanoparticles via laser-created microscopic thermal zones. Controlled Er:glass laser irradiation offers a valid enhancement strategy to topically administer the permeants with a wide MW and lipophilicity range. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Fractional non-ablative laser-assisted drug delivery leads to improvement in male and female pattern hair loss.

    Science.gov (United States)

    Bertin, Ana Carina Junqueira; Vilarinho, Adriana; Junqueira, Ana Lúcia Ariano

    2018-02-16

    Androgenetic alopecia, also known as male and female pattern hair loss, is a very prevalent condition; however, approved therapeutic options are limited. Fractionated laser has been proposed to assist in penetration of topical medications to the cutaneous tissue. We present four cases of androgenetic alopecia that underwent treatment with a non-ablative erbium glass fractional laser followed by the application of topical finasteride 0,05% and growth factors including basic fibroblast growth factor, insulin-like growth factor, vascular endothelial growth factor, and copper peptide 1%. During all laser treatment sessions, eight passes were performed, at 7 mJ, 3-9% of coverage and density of 120 mzt/cm 2 . A positive response was observed in all of the four patients. Photographs taken 2 weeks after the last session showed improvement in hair regrowth and density. No significant side effects were observed.

  12. Ablative Fractional Laser-Assisted Topical Fluorouracil for the Treatment of Superficial Basal Cell Carcinoma and Squamous Cell Carcinoma In Situ: A Follow-Up Study.

    Science.gov (United States)

    Hsu, Sarah H; Gan, Stephanie D; Nguyen, Bichchau T; Konnikov, Nellie; Liang, Christine A

    2016-09-01

    The authors previously reported the safety and short-term efficacy of ablative fractional laser (AFXL)-assisted delivery of topical fluorouracil in the treatment of superficial basal cell carcinoma (sBCC) and squamous cell carcinoma in situ (SCCis). This follow-up study was conducted to assess whether tumor clearance was sustained in this cohort of patients at >9 months post-treatment. Thirty primary sBCC or SCCis treatment, 20 patients presented for this follow-up study and underwent shave biopsy to confirm histologic clearance. Mean follow-up time was 15 months. Considering those who had persistent tumor at 4 to 8 weeks post-treatment and those who presented for follow-up at >9 months post-treatment, overall treatment success was 79% (95% confidence interval: 67%-96%), with 92% (11/12) for SCCis and 67% (8/12) for sBCC. Neither the tumor location nor size significantly impacted treatment outcome (p = .96 and 0.87, respectively). Ablative fractional laser-assisted topical fluorouracil is a reasonable noninvasive treatment option for primary SCCis and sBCC, especially for lesions located in areas where self-application is not possible, or when clinician-administered therapy is preferred.

  13. Femtosecond laser-assisted in situ keratomileusis multifocal ablation profile using a mini-monovision approach for presbyopic patients with hyperopia

    Directory of Open Access Journals (Sweden)

    Vastardis I

    2016-07-01

    Full Text Available Iraklis Vastardis,1 Brigitte Pajic-Eggspühler,1 Jörg Müller,1,2 Zeljka Cvejic,2 Bojan Pajic,1–4 1Swiss Eye Research Foundation, Orasis Eye Clinic, Aargau, Reinach, Switzerland; 2Faculty of Physics, University of Novi Sad, Novi Sad, Serbia; 3Department of Ophthalmology, Geneva University Hospitals, Geneva, Switzerland; 4Medical Faculty, Military Medical Academy, University of Defence, Belgrade, Serbia Purpose: To report the visual outcomes of the femtosecond laser-assisted multifocal aspheric corneal ablation profile using a mini-monovision approach and to evaluate if corneal multifocality was effective, and to report the relative benefits of this approach.Patients and methods: Bilateral femtosecond laser-assisted in situ keratomileusis using a multifocal aspheric corneal ablation profile was performed on 19 hyperopic patients (38 eyes. They were divided into two groups based on eye dominance: dominant eye (DE group targeting emmetropia and the nondominant eye (NDE group targeting -0.5 D slight myopia. The uncorrected distance visual acuity (UDVA, uncorrected intermediate visual acuity (UIVA, uncorrected near visual acuity (UNVA, and retreatment rates were reported from baseline to 6 months.Results: The UNVA, UIVA, and UDVA improved significantly in both groups (Kruskal–Wallis test, DE and NDE: P<0.00001, P<0.000005, and P=0.00001, respectively. Corrected distance visual acuity (CDVA baseline was better in both groups in comparison to UDVA at 6 months (Wilcoxon test, DE: P<0.001, 95% confidence interval (CI of the median 0.0–0.0 LogMAR and 0.1000–0.1218 LogMAR and NDE: P=0.010, 95% CI of the median 0.0–0.0 LogMAR and 0.00–0.10 LogMAR. There was a significant loss of lines between CDVA baseline and UDVA at 6 months in both groups (DE group: 68% of eyes lost one line or more; NDE group: 58% of eyes lost one line or more. The corrected near visual acuity baseline compared to UNVA at 6 months was not statistically important

  14. Preprosthetic Laser Assisted Mandibular Vestibuloplasty

    Directory of Open Access Journals (Sweden)

    Kacarska M.

    2016-11-01

    Full Text Available A prosthetic treatment of the edentulous mandible can be very challenging. In cases with inadequate buccal depth, a necessary deepening of the oral vestibule can be achieved by surgically detaching the soft tissue attachments. A preprosthetic vestibuloplasty is usually done surgically by scalpel. With the permanent advancement of laser technology, a laser vestibuloplasty has become a preferred surgical procedure. The aim of this report was to present individuality of a mandible vestibuloplasty performed with Er.YAG laser.

  15. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

    Directory of Open Access Journals (Sweden)

    Carlo Cagini

    2015-01-01

    Full Text Available The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

  16. Laser-assisted photoelectric effect from surfaces.

    Science.gov (United States)

    Miaja-Avila, L; Lei, C; Aeschlimann, M; Gland, J L; Murnane, M M; Kapteyn, H C; Saathoff, G

    2006-09-15

    We report the first observation of the laser-assisted photoelectric effect from a solid surface. By illuminating a Pt(111) sample simultaneously with ultrashort 1.6 eV and 42 eV pulses, we observe sidebands in the extreme ultraviolet photoemission spectrum. The magnitude of these sidebands as a function of time delay between the laser and extreme ultraviolet pulses represents a cross-correlation measurement of the extreme ultraviolet pulse. This effect promises to be useful to extend extreme ultraviolet pulse duration measurements to higher photon energies, as well as opening up femtosecond-to-attosecond time-scale electron dynamics in solid and surface-adsorbate systems.

  17. Laser assisted robotic surgery in cornea transplantation

    Science.gov (United States)

    Rossi, Francesca; Micheletti, Filippo; Magni, Giada; Pini, Roberto; Menabuoni, Luca; Leoni, Fabio; Magnani, Bernardo

    2017-03-01

    Robotic surgery is a reality in several surgical fields, such as in gastrointestinal surgery. In ophthalmic surgery the required high spatial precision is limiting the application of robotic system, and even if several attempts have been designed in the last 10 years, only some application in retinal surgery were tested in animal models. The combination of photonics and robotics can really open new frontiers in minimally invasive surgery, improving the precision, reducing tremor, amplifying scale of motion, and automating the procedure. In this manuscript we present the preliminary results in developing a vision guided robotic platform for laser-assisted anterior eye surgery. The robotic console is composed by a robotic arm equipped with an "end effector" designed to deliver laser light to the anterior corneal surface. The main intended application is for laser welding of corneal tissue in laser assisted penetrating keratoplasty and endothelial keratoplasty. The console is equipped with an integrated vision system. The experiment originates from a clear medical demand in order to improve the efficacy of different surgical procedures: when the prototype will be optimized, other surgical areas will be included in its application, such as neurosurgery, urology and spinal surgery.

  18. Laser-Assisted Photoelectric Effect from Liquids.

    Science.gov (United States)

    Arrell, C A; Ojeda, J; Mewes, L; Grilj, J; Frassetto, F; Poletto, L; van Mourik, F; Chergui, M

    2016-09-30

    The laser-assisted photoelectric effect from liquid surfaces is reported for the first time. Photoelectrons generated by 35.6 eV radiation from a liquid microjet of water under vacuum are dressed with a ℏω=1.55  eV laser field. The subsequent redistribution of the photoelectron energies consists in the appearance of sidebands shifted by energies equivalent to ℏω, 2ℏω, and 3ℏω. The response has been modeled to the third order and combined with energy-resolved measurements. This result opens the possibility to investigate the dynamics at surfaces of liquid solutions and provide information about the electron emission process from a liquid.

  19. Laser-Assisted Micro-Pulsejet Thruster

    Science.gov (United States)

    Horisawa, Hideyuki; Eto, Sou

    2010-10-01

    A fundamental study of a laser-assisted micro-pulsejet thruster was conducted for a candidate of next-generation air-breathing micro-thruster systems. CFD analyses were conducted to evaluate internal phenomena, thrust performances, and influence of exhaust orifice for propellants of hydrogen-air mixture. Experimental investigations were also conducted to evaluate influence of exhaust orifices and the optimum configuration of the micro-combustion chamber. From the results, it was shown that the exhaust orifice was more effective for the improvement of thrust performance. Moreover, influence of combustor geometry on thrust performance for the improvement was confirmed. In our simulation and experimental results, the efficiency from ideal chemical energy, which is expected to be released from an ideal hydrogen-air mixture, into kinetic energy was a few percents. There are still some ways to recover this amount of loss with optimum combustor geometries and higher laser energies, and potential achieving much higher thrust performances.

  20. Laser-assisted machining of silicon nitride; Chikka keiso no laser assist kako

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, K.; Fukui, Y. [Kyushu National Industrial Research Institute, Saga (Japan)

    1996-03-01

    The laser-assisted machining developed for difficult-to-machine metal materials was applied to ceramics to study its effectiveness. In the laser-assisted machining, the tip of a tool pressed on a ceramic specimen was heated locally by laser beam while feeding the specimen at a constant speed. In experiment, the continuous excitation multi-mode YAG laser equipment of 300W in maximum capacity was used at 50-150W in output and 1mm/s in feed rate. The surface of silicon nitride specimens was observed under irradiation of laser beam to study the thermal effect of laser beam irradiation on specimens. As an experimental result, as silicon nitride specimens were irradiated with laser beam over 150W, the possibility of highly efficient machining by cutting which is impossible previously was confirmed through formation of an oxidizing deformed layer. How wide the oxidizing deformed layer extends, and how much such deformed layer can be removed by machining tool remain to be studied in the future. 3 refs., 6 figs., 1 tab.

  1. Reversible Femtosecond Laser-Assisted Myopia Correction: A Non-Human Primate Study of Lenticule Re-Implantation after Refractive Lenticule Extraction: e67058

    National Research Council Canada - National Science Library

    Andri K Riau; Romesh I Angunawela; Shyam S Chaurasia; Wing S Lee; Donald T Tan; Jodhbir S Mehta

    2013-01-01

      LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap...

  2. Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction

    National Research Council Canada - National Science Library

    Riau, Andri K; Angunawela, Romesh I; Chaurasia, Shyam S; Lee, Wing S; Tan, Donald T; Mehta, Jodhbir S

    2013-01-01

    LASIK (laser-assisted in situ keratomileusis) is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap...

  3. Fractional laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Erlendsson, Andrés M; Doukas, Apostolos G; Farinelli, William A

    2016-01-01

    BACKGROUND AND OBJECTIVE: Ablative fractional laser (AFXL) is rapidly evolving as one of the foremost techniques for cutaneous drug delivery. While AFXL has effectively improved topical drug-induced clearance rates of actinic keratosis, treatment of basal cell carcinomas (BCCs) has been challenging...... deposition and delivery kinetics; (iii) biodistribution and diffusion pattern, estimated by mathematical simulation. METHODS: Franz diffusion chambers (FCs) were used to evaluate the PVP-technique, comparing passive (AFXL) and active (AFXL + PVP) channel filling. A fractional CO2-laser generated superficial...... intradermal biodistribution and diffusion at a depth of 1,000 µm. RESULTS: Active filling with application of PVP increased the number of filled laser channels. At a depth of 1,000 µm, filling increased from 44% (AFXL) to 94% with one PVP cycle (AFXL + PVP; P

  4. Fractional laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth Hjardem; Lerche, C.M.; Erlendsson, A M

    2016-01-01

    BACKGROUND AND OBJECTIVE: Ablative fractional laser (AFXL) facilitates delivery of topical methotrexate (MTX). This study investigates impact of laser-channel depth on topical MTX-delivery. MATERIALS AND METHODS: MTX (1% [w/v]) diffused for 21 hours through AFXL-exposed porcine skin in in vitro......-thickness skin, biodistribution profiles at specific skin levels, and transdermal permeation. Fluorescence microscopy was used to visualize UVC-activated MTX-fluorescence (254 nm) and semi-quantify MTX distribution in skin. RESULTS: AFXL increased topical MTX-delivery (P ...-concentration in full-thickness skin was 0.07 mg/cm(2) , increasing sixfold (MAZ-E), ninefold (MAZ-DS), and 11-fold (MAZ-DM) after AFXL (P skin layers (P skin layers (MAZ-E: 1.85 mg/cm(3) at 500 μm skin...

  5. Laser assisted hybrid additive manufacturing of thermoelectric modules

    Science.gov (United States)

    Zhang, Tao; Tewolde, Mahder; Longtin, Jon P.; Hwang, David J.

    2017-02-01

    Thermoelectric generators (TEGs) are an attractive means to produce electricity, particular from waste heat applications. However, TEGs are almost exclusively manufactured as flat, rigid modules of limited size and shape, and therefore an appropriate mounting for intimate contact of TEGs modules onto arbitrary surfaces represents a significant challenge. In this study, we introduce laser assisted additive manufacturing method to produce multi-layered thermoelectric generator device directly on flat and non-flat surfaces for waste heat recovery. The laser assisted processing spans from laser scribing of thermal sprayed thin films, curing of dispensed thermoelectric inks and selective laser sintering to functionalize thermoelectric materials.

  6. Review: Femtosecond Laser Assisted Cataract Surgery (FLACS): An ...

    African Journals Online (AJOL)

    Age-related cataract is one of the most important causes of visual impairment, and cataract surgery is one of the commonest surgeries performed worldwide. Femtosecond laser assisted cataract surgery (FLACS) is a new and promising technology in the arena of cataract operations. Femtosecond lasers (FSL) are used in ...

  7. Laser-assisted growth of carbon nanotubes - A review

    NARCIS (Netherlands)

    Burgt, Y. van de

    2014-01-01

    Laser-assisted chemical vapor deposition (LACVD) is an attractive maskless process for growing locally carbon nanotubes at selected places on substrates that may contain temperature-sensitive components. This review gives a comprehensive overview of the reported research with respect to laser

  8. The impact of treatment density and molecular weight for fractional laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haak, Christina S; Bhayana, Brijesh; Farinelli, William A

    2012-01-01

    Ablative fractional lasers (AFXL) facilitate uptake of topically applied drugs by creating narrow open micro-channels into the skin, but there is limited information on optimal laser settings for delivery of specific molecules. The objective of this study was to investigate the impact of laser...... treatment density (% of skin occupied by channels) and molecular weight (MW) for fractional CO(2) laser-assisted drug delivery. AFXL substantially increased intra- and transcutaneous delivery of polyethylene glycols (PEGs) in a MW range from 240 to 4300 Da (Nuclear Magnetic Resonance, p...

  9. Laser-assisted H^{-} charge exchange injection in magnetic fields

    Directory of Open Access Journals (Sweden)

    T. Gorlov

    2010-05-01

    Full Text Available The use of stripping foils for charge exchange injection can cause a number of operational problems in high intensity hadron accelerators. A recently proposed three-step method of laser-assisted injection is capable of overcoming these problems. This paper presents advances in the physical model of laser-assisted charge exchange injection of H^{-} beams and covers a wide field of atomic physics. The model allows the calculation of the evolution of an H^{0} beam taking into account spontaneous emission, field ionization, and external electromagnetic fields. Some new data on the hydrogen atom related to the problem are calculated. The numerical calculations in the model use realistic descriptions of laser field and injection beam. Generally, the model can be used for design and optimization of a laser-assisted injection cell within an accelerator lattice. Example calculations of laser-assisted injection for an intermediate experiment at SNS in Oak Ridge and for the PS2 accelerator at CERN are presented. Two different schemes, distinctively characterized by various magnetic fields at the excitation point, are discussed. It was shown that the emittance growth of an injected beam can be drastically decreased by moving the excitation point into a strong magnetic field.

  10. Technical improvements in diode-laser-assisted skin welding

    Science.gov (United States)

    Chiarugi, C.; Martini, L.; Borgognoni, L.; Reali, Umberto M.; Gori, F.; Pini, Roberto; Toncelli, F.

    1996-01-01

    We performed diode-laser assisted skin welding on Wistar rats by using a sodium hyaluronate gel mixed with Indocyanine Cadio-green (ICG) as photoenhancing chromophore. Laser treatment was accomplished with a 'side' irradiation technique, taking advantage of the fact that diode laser radiation at 810 nm is well transmitted by tissue on distances of some millimeters. Clinical and histological results were compared with those of conventionally sutured wounds.

  11. Kinetics of laser-assisted carbon nanotube growth

    NARCIS (Netherlands)

    Burgt, Y. van de; Bellouard, Y.; Mandamparambil, R.

    2014-01-01

    Laser-assisted chemical vapour deposition (CVD) growth is an attractive mask-less process for growing locally aligned carbon nanotubes (CNTs) in selected places on temperature sensitive substrates. The nature of the localized process results in fast carbon nanotube growth with high experimental

  12. Optical process model for laser-assisted tape winding

    NARCIS (Netherlands)

    Baran, Ismet; Akkerman, Remko; Reichardt, J.M.; Drechsler, K.

    2016-01-01

    The present work is part of the EU-funded ambliFibre project in which a model-based on-line monitoring solution is being developed for the laser assisted tape winding (LATW) process of tubular fibre reinforced thermoplastic composite parts. Within this framework, an optical process simulation tool

  13. Laser Assisted Free-Free Transition in Electron - Atom Collision

    Science.gov (United States)

    Sinha, C.; Bhatia, A. K.

    2011-01-01

    Free-free transition is studied for electron-Hydrogen atom system in ground state at very low incident energies in presence of an external homogeneous, monochromatic and linearly polarized laser field. The incident electron is considered to be dressed by the laser in a non perturbative manner by choosing the Volkov solutions in both the channels. The space part of the scattering wave function for the electron is solved numerically by taking into account the effect of electron exchange, short range as well as of the long range interactions. Laser assisted differential as well as elastic total cross sections are calculated for single photon absorption/emission in the soft photon limit, the laser intensity being much less than the atomic field intensity. A strong suppression is noted in the laser assisted cross sections as compared to the field free situations. Significant difference is noted in the singlet and the triplet cross sections.

  14. Comprehension of chip formation in laser assisted machining

    OpenAIRE

    GERMAIN, Guénaël; Dal Santo, Philippe; Lebrun, Jean-Lou

    2011-01-01

    International audience; Laser Assisted Machining (LAM) improves the machinability of materials by locally heating the workpiece just prior to cutting. Experimental investigations have confirmed that the cutting force can be decreased, by as much as 40%, for various materials. In order to understand the effect of the laser on chip formation and on the temperature fields in the different deformation zones, thermo-mechanical simulations were undertaken. A thermo-mechanical model for chip formati...

  15. Clinical results of 123 femtosecond laser-assisted penetrating keratoplasties.

    Science.gov (United States)

    Birnbaum, Florian; Wiggermann, Antonia; Maier, Philip C; Böhringer, Daniel; Reinhard, Thomas

    2013-01-01

    Postoperative astigmatism following penetrating keratoplasty is a major problem after corneal transplantation. The main goal of new trephination techniques such as femtosecond laser or excimer-laser trephination is to improve refractive and visual outcomes. The femtosecond laser technique makes profiled corneal trephinations such as the top hat or mushroom profile possible. We present the postoperative outcome of femtosecond laser-assisted penetrating keratoplasties. We performed 123 femtosecond laser-assisted penetrating keratoplasties in 119 patients. The main outcome measures were intraoperative specifics, astigmatism, and irregularity in Orbscan corneal topography, as well as the occurrence of immune reactions and side-effects. All sutures have been removed in 49 of these 123 eyes. Their mean follow-up was 13.9 ± 4.5 months. Time to complete suture removal (n = 49) was 12.0 ± 3.7 months in the mushroom group and 9.8 ± 2.1 months in the top hat group. Mean astigmatism in Orbscan topography was 6.4 ± 3.0 diopters in the mushroom and 5.8 ± 4.6 diopters in the top hat group (all sutures out). Femtosecond laser-assisted penetrating keratoplasty is a safe surgical technique. Due to the steps in profiled trephinations, the wound area is larger and theoretically the wound healing is, thus, faster and more stable. Complete suture removal is possible at an earlier time point compared to conventional penetrating keratoplasty. However, refractive results are not superior to those following conventional trephination.

  16. Laser-assisted machining of difficult-to-machine materials

    Energy Technology Data Exchange (ETDEWEB)

    Incropera, F.P.; Rozzi, J.C.; Pfefferkorn, F.E.; Lei, S.; Shin, Y.C.

    1999-07-01

    Laser-assisted machining (LAM) is a hybrid process for which a difficult-to-machine material, such as a ceramic or super alloy, is irradiated by a laser source prior to material removal by a cutting tool. The process has the potential to significantly increase material removal rates, as well as to improve the geometry and properties of the finished work piece. Features and limitations of theoretical and experimental procedures for determining the transient thermal response of a work piece during LAM are described, and representative results are presented for laser-assisted turning of sintered silicon nitride. Significant physical trends are revealed by the calculations, as are guidelines for the selection of appropriate operating conditions.

  17. Pulsed laser-assisted machining of Inconel 718 superalloy

    Science.gov (United States)

    Azhdari Tadavani, Soheila; Shoja Razavi, Reza; Vafaei, Reza

    2017-01-01

    Nickel-based superalloys including Inconel 718(IN718) are widely used in aerospace industries due to their superior high temperature strength, toughness, and corrosion resistance. These alloys are difficult to machine mainly because of their low thermal conductivity and high work hardening rate, which cause steep temperature gradient and high cutting forces at the tool edge. The application of laser assisted machining is the subject of many new researches since shear forces; surface coarsening and tool wear are reduced. The aim of this investigation was to evaluate laser assisted machining behavior of a 718 Inconel superalloy from the view point of machining specific energy, surface roughness, tool wear and chip appearance. Experimental apparatuses used included optical and scanning electron microscopy, spark emission spectroscopy, and EDS analysis. The results indicated that increasing the temperature to about 540 °C just ahead of primary shear zone, can result in 35% reduction of machining specific energy, in comparison with conventional machining. Furthermore, surface coarsening and tool wear were reduced by 22% and 23% respectively. Flank wear was the main deteriorating factor on cutting tools during laser assisted machining. SEM micrographs indicated that increase in temperature has no noticeable effect on finished workpiece surface. Analysis of variance obtained from regression analysis indicated that frequency of laser beam has the most influential effect on temperature. The optimum conditions for laser assisted machining of 718 superalloy is suggested as follows: 80 Hz frequency, 400 W power, 24 m/min cutting speed, and 0.052 mm/rev feed rate along with 540 °C temperature, 2.51 J/mm2 machining specific energy and 130 N cutting force.

  18. Optic pit maculopathy after laser-assisted in situ keratomileusis.

    Science.gov (United States)

    Rodriguez-Coleman, Hanna; Schiff, William M; Hwang, John C; Speaker, Mark G

    2007-02-01

    Optic disc pit is an embryological malformation of the optic nerve that occurs in less than one in 10,000 people. It is 10%-15% bilateral, and 25% to 70% of patients develop a neurosensory macular detachment within the 2nd to 4th decade. We report a case of unilateral optic disc pit maculopathy 2 months after laser-assisted in situ keratomileusis (LASIK) revision.

  19. Clinical effect of femtosecond laser assisted penetrating corneal transplantation operation

    Directory of Open Access Journals (Sweden)

    Hong-Jian Zhou

    2014-10-01

    Full Text Available AIM: To observe the clinical effect of femtosecond laser assisted penetrating keratoplasty. METHODS: Twenty-four cases(24 eyeswith corneal lesions were performed with femtosecond laser assisted penetrating keratoplasty. Preoperative and postoperative endothelial cell density and visual quality were compared.RESULTS: One week after operation, corneal grafts were clear in 21 eyes(87.5%, mild cloudy in 3 eyes(12.5%; visual acuity ≥0.5 in 18 eyes(75.0%, 0.2~0.4 in 6 eyes(25.0%. After 3mo the mean corneal astigmatism was 2.16±0.21D(range 2.25~3.09D. Compared to conventional penetrating keratoplasty which mean corneal astigmatism was average 3.67±0.38D after operation, there was significant difference between two groups(PPCONCLUSION: Femtosecond laser assisted penetrating corneal transplantation operation can improve patient's visual quality. And compared to traditional penetrating keratoplasty astigmatism decreased significantly, incision can be made in individual shape more precisely and neatly.

  20. Laser-assisted manufacturing of thermal energy devices

    Science.gov (United States)

    Zhang, Tao; Tewolde, Mahder; Kim, Ki-Hoon; Seo, Dong-Min; Longtin, Jon P.; Hwang, David J.

    2016-03-01

    In this study, we will present recent progress in the laser-assisted manufacturing of thermal energy devices that require suppressed thermal transport characteristics yet maintaining other functionalities such as electronic transport or mechanical strength. Examples of such devices to be demonstrated include thermoelectric generator or insulating materials. To this end, it will be shown that an additive manufacturing approaches can be facilitated and improved by unique processing capabilities of lasers in composite level. In order to tailor thermal characteristics in thermal devices, we will mainly investigate the potential of laser heating, curing, selective removal and sintering processes of material systems in the composite level.

  1. Laser-assisted control of molecular orientation at high temperatures

    Science.gov (United States)

    Zhdanov, Dmitry V.; Zadkov, Victor N.

    2008-01-01

    A method of laser-assisted field-free dynamic molecular orientation employing a short, moderately intense three-color phase-locked laser pulse is proposed. Numerical simulations show that it provides an exceedingly effective control of orientation in molecular gases even at room temperatures. The underlying mechanism is based on the specific laser-induced orientation-dependent selective excitation of molecules and subsequent self-transformation of the induced geometrical orientation into a dynamical one. It is shown that this mechanism is significantly more powerful than the widely investigated kick mechanism.

  2. Femtosecond-laser-assisted Descemet's stripping endothelial keratoplasty.

    Science.gov (United States)

    Cheng, Yanny Y Y; Pels, Elisabeth; Nuijts, Rudy M M A

    2007-01-01

    To our knowledge, we describe the first patient with pseudophakic bullous keratoplasty treated with femtosecond-laser-assisted endothelial keratoplasty. A 5.5 mm corneoscleral tunnel incision was made; after Descemet's membrane was stripped, an 8.0 mm posterior lamellar corneal disk prepared with a femtosecond laser was inserted into the anterior chamber against the recipient cornea without the use of corneal sutures. Four months postoperatively, the posterior corneal disk was clear and the induced astigmatism was 2.1 diopters, demonstrating a functional corneal endothelial layer. The femtosecond laser offers a new surgical approach for minimally invasive endothelial keratoplasty in corneal endothelial disorders.

  3. Laser-assisted electron diffraction for femtosecond molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Yuya; Kanya, Reika [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yamanouchi, Kaoru, E-mail: kaoru@chem.s.u-tokyo.ac.jp [Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); NANOQUINE, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2014-02-14

    We report the observation of laser-assisted electron diffraction (LAED) through the collision of 1 keV electrons with gas-phase CCl{sub 4} molecules in a femtosecond near-infrared laser field. In the angular distribution of the scattered electrons with the energy shifts of ±ℏω, we observed clear diffraction patterns which reflect the geometrical structure of the molecules at the moment of laser irradiation. Our results demonstrate that ultrafast nuclear dynamics of molecules can be probed by LAED with the high temporal (<10 fs) and spatial (∼0.01 Å) resolutions.

  4. Effects in laser-assisted stapedotomy

    NARCIS (Netherlands)

    Kamalski, D.M.A.

    2014-01-01

    In patients with otosclerosis, the stapes fixates in the oval window, resulting in a conductive hearing loss. A stapedotomy can be performed to restore hearing. During this surgery a small hole is created in the footplate of the stapes, by a micropick instrument or laser. Making a fenestration is

  5. Fractional laser-assisted delivery of methyl aminolevulinate

    DEFF Research Database (Denmark)

    Haak, Christina S; Farinelli, William A; Tam, Joshua

    2012-01-01

    Pretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth of intrade......Pretreatment of skin with ablative fractional lasers (AFXL) enhances the uptake of topical photosensitizers used in photodynamic therapy (PDT). Distribution of photosensitizer into skin layers may depend on depth of laser channels and incubation time. This study evaluates whether depth...

  6. Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites

    Science.gov (United States)

    Quadrini, Fabrizio; Squeo, Erica Anna; Prosperi, Claudia

    2010-01-01

    A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force) were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a strong interpenetration of adjacent layers was observed.

  7. Diode Laser Assisted Filament Winding of Thermoplastic Matrix Composites

    Directory of Open Access Journals (Sweden)

    Claudia Prosperi

    2010-01-01

    Full Text Available A new consolidation method for the laser-assisted filament winding of thermoplastic prepregs is discussed: for the first time a diode laser is used, as well as long glass fiber reinforced polypropylene prepregs. A consolidation apparatus was built by means of a CNC motion table, a stepper motor and a simple tensioner. Preliminary tests were performed in a hoop winding configuration: only the winding speed was changed, and all the other process parameters (laser power, distance from the laser focus, consolidation force were kept constant. Small wound rings with an internal diameter of 25 mm were produced and compression tests were carried out to evaluate the composite agglomeration in dependence of the winding speed. At lower winding speeds, a stronginterpenetration of adjacent layers was observed.

  8. Study of a fiber laser assisted friction stir welding process

    Science.gov (United States)

    Casalino, G.; Campanelli, S.; Ludovico, A. D.; Contuzzi, N.; Angelastro, A.

    2012-03-01

    Friction stir welding is a relatively new joining technique. This technique, which is considered a derivative of the more common friction welding method, was developed mainly for aluminum and its alloys. In recent years, this method has been used to join various other alloys. FSW has many advantages, including the following: the welding procedure is relatively simple with no consumables or filler metal; joint edge preparation is not needed; oxide removal prior to welding is unnecessary; high joint strength has been achieved in aluminum and magnesium alloys; FSW can be used with alloys that cannot be fusion welded due to crack sensitivity. The drawbacks of FSW include the need for powerful fixtures to clamp the workpiece to the welding table, the high force needed to move the welding tool forward, the relatively high wear rate of the welding tool, and weld speeds in FSW are slower, which can lead to longer process times. To overcome these drawbacks, a fiber laser-assisted friction stir welding system was designed (FLAFSW). The system combined a conventional commercial friction machine and a fiber pumped laser system. The scope is to investigate the influence of the laser assistance on the weld quality. A number of different aluminum plates, which are still mentioned to be difficult to be joint as intermetallic phases appear during melting welding techniques, were used. The evaluation of quality was performed through analysis of appearance, mechanical and microstructure characterization of the weld.

  9. Laser Assisted Machining : Current Status and Future Scope

    Science.gov (United States)

    Brandt, M.; Sun, S.

    Laser -assisted machining (LAM) is a hybrid cutting process in which a laser beam is used to heat and soften the workpiece locally in front of the cutting tool. The temperature rise at the shear zone reduces the yield strength and work hardening of the workpiece, which makes the plastic deformation of difficult-to-machine materials (engineering ceramics , hard metals , and metal matrix composites) easier during machining. Its process benefits include a reduction in the cutting forces/specific cutting energy, longer tool life, better surface integrity , and high productivity. This chapter summarizes the up-to-date progress of LAM of ceramics , metals , and metal matrix composites. It covers the analysis of temperature distribution around the cutting region, material removal mechanisms, tool wear mechanisms, and the improvement in machined surface integrity of various engineering materials by the assistance of laser beam.

  10. Low threshold buried-heterostructure quantum well lasers by excimer laser assisted disordering

    Energy Technology Data Exchange (ETDEWEB)

    Epler, J.E.; Thornton, R.L.; Mosby, W.J.; Paoli, T.L.

    1988-10-17

    Laser assisted disordering based upon a direct-write Ar/sup +/ laser beam has been established as a fabrication technique for high quality optoelectronic devices. In this letter, we report a new form of laser assisted disordering in which an excimer laser beam, photolithographically patterned, is used to define the incorporation of Si impurity into GaAs-AlGaAs heterostructure crystals. During a subsequent thermal anneal the diffusing Si induces layer disordering to a depth of approx.1 ..mu..m. The excimer laser assisted disordering process is characterized as a function of the energy density of the laser beam. Also, this technique is used to fabricate high quality buried-heterostructure lasers. With a reflective rear facet, the typical cw threshold current is 4 mA and the maximum power output is 27 mW. The devices exhibit single fundamental mode operation with subsidiary longitudinal side modes suppressed by 34 dB.

  11. Laser-assisted nanomaterial deposition, nanomanufacturing, in situ monitoring and associated apparatus

    Science.gov (United States)

    Mao, Samuel S; Grigoropoulos, Costas P; Hwang, David J; Minor, Andrew M

    2013-11-12

    Laser-assisted apparatus and methods for performing nanoscale material processing, including nanodeposition of materials, can be controlled very precisely to yield both simple and complex structures with sizes less than 100 nm. Optical or thermal energy in the near field of a photon (laser) pulse is used to fabricate submicron and nanometer structures on a substrate. A wide variety of laser material processing techniques can be adapted for use including, subtractive (e.g., ablation, machining or chemical etching), additive (e.g., chemical vapor deposition, selective self-assembly), and modification (e.g., phase transformation, doping) processes. Additionally, the apparatus can be integrated into imaging instruments, such as SEM and TEM, to allow for real-time imaging of the material processing.

  12. Bioceramic 3D Implants Produced by Laser Assisted Additive Manufacturing

    Science.gov (United States)

    Lusquiños, Fernando; del Val, Jesús; Arias-González, Felipe; Comesaña, Rafael; Quintero, Félix; Riveiro, Antonio; Boutinguiza, Mohamed; Jones, Julian R.; Hill, Robert G.; Pou, Juan

    Cranial defect restoration requires a suitable implant capable to fulfill protective and aesthetic functions, such as polymeric and metallic implants. Nevertheless, the former materials cannot provide osteointegration of the implant within the host bone nor implant resorption, which is also required in pediatricorthopedics for normal patient growth. Resorbable and osteoconductivebioceramics are employed, such as silicate bioactive glasses. Nevertheless, manufacturing based on conventional casting in graphite moulds is not effective for warped shape implants suitable for patient tailored treatments. In this work, we analyze the application of rapid prototyping based on laser cladding to manufacture bioactive glass implants for low load bearing bone restoration. This laser-assisted additive technique is capable to produce three-dimensional geometries tailored to patient, with reduced fabrication time and implant composition modification. The obtained samples were characterized; the relationships between the processing conditions and the measured features were studied, in addition to the biological behavior analysis.

  13. Laser assisted machining: a state of art review

    Science.gov (United States)

    Punugupati, Gurabvaiah; Kandi, Kishore Kumar; Bose, P. S. C.; Rao, C. S. P.

    2016-09-01

    Difficult-to-cut materials have increasing demand in aerospace and automobile industries due to their high yield stress, high strength to weight ratio, high toughness, high wear resistance, high creep, high corrosion resistivity, ability to retain high strength at high temperature, etc. The machinability of these advanced materials, using conventional methods of machining is typical due to the high temperature and pressure at the cutting zone and tool and properties such as low thermal conductivity, high cutting forces and cutting temperatures makes the materials difficult to machine. Laser assisted machining (LAM) is a new and innovative technique for machining the difficult-to-cut materials. This paper deals with a review on the advances in lasers, tools and the mechanism of machining using LAM and their effects.

  14. Laser-assisted subepithelial keratectomy (LASEK) versus laser-assisted in-situ keratomileusis (LASIK) for correcting myopia.

    Science.gov (United States)

    Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S

    2017-02-15

    Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review. To assess the effects of LASEK versus LASIK for correcting myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials. We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were

  15. Fractional CO(2) laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A

    2010-01-01

    Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug.......Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

  16. Comparison of laser-assisted damage in soft tissue using bi-directional and forward-firing optical fiber

    Science.gov (United States)

    Kim, Changhwan; Sohn, Ik-Bu; Park, Hoyong; Lee, Yong Joong; Lee, Ho

    2014-03-01

    Laser-assisted endoscopic surgery is made possible by employing optical devices such as fiber optics and hollow wave-guides. In some applications of laser-assisted endoscopic surgery, it is necessary to change the direction of the light emission. Our group reported a new fabrication method for bi-directional firing fibers. The conical surface of the fiber tip made the bi-directional emission of the laser light at the distal end of the fiber. In this study, we employed the bi-directional firing fiber for laser-assisted coagulation of soft tissue. The developed fiber and the normal forward-firing fiber are used for the endoscopic delivery system of a continuous IR laser into an in vitro porcine liver. The ablation and coagulation pattern were compared for two distinctive fiber systems. Regardless of the laser's parameters, the bi-directional firing fiber produced a cavity and coagulation zone with more or less a circular shape, while the forward fiber produced an elongated cavity and coagulation region. The bi-directional firing fiber produced wider and shorter coagulation and cavity zones compared to that of the forward-firing fiber. We expect the bi-directional firing fiber to be an excellent optical delivery system for endoscopic laser-hyperthermia when used against various tumors in the liver, breast and thyroid.

  17. Thermal and thermo-mechanical simulation of laser assisted machining

    Science.gov (United States)

    Germain, G.; Dal Santo, P.; Lebrun, J. L.; Bellett, D.; Robert, P.

    2007-04-01

    Laser Assisted Machining (LAM) improves the machinability of materials by locally heating the workpiece just prior to cutting. The heat input is provided by a high power laser focused several millimeters in front of the cutting tool. Experimental investigations have confirmed that the cutting force can be decreased, by as much as 40%, for various materials (tool steel, titanium alloys and nickel alloys). The laser heat input is essentially superficial and results in non-uniform temperature profiles within the depth of the workpiece. The temperature field in the cutting zone is therefore influenced by many parameters. In order to understand the effect of the laser on chip formation and on the temperature fields in the different deformation zones, thermo-mechanical simulation were undertaken. A thermo-mechanical model for chip formation with and without the laser was also undertaken for different cutting parameters. Experimental tests for the orthogonal cutting of 42CrMo4 steel were used to validate the simulation via the prediction of the cutting force with and without the laser. The thermo-mechanical model then allowed us to highlight the differences in the temperature fields in the cutting zone with and without the laser. In particular, it was shown that for LAM the auto-heating of the material in the primary shear zone is less important and that the friction between the tool and chip also generates less heat. The temperature fields allow us to explain the reduction in the cutting force and the resulting residual stress fields in the workpiece.

  18. Fractional CO(2) laser-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Sakamoto, Fernanda H; Farinelli, William A

    2010-01-01

    Ablative fractional resurfacing (AFR) creates vertical channels that might assist the delivery of topically applied drugs into skin. The purpose of this study was to evaluate drug delivery by CO(2) laser AFR using methyl 5-aminolevulinate (MAL), a porphyrin precursor, as a test drug....

  19. Numerical modeling of laser assisted tape winding process

    Science.gov (United States)

    Zaami, Amin; Baran, Ismet; Akkerman, Remko

    2017-10-01

    Laser assisted tape winding (LATW) has become more and more popular way of producing new thermoplastic products such as ultra-deep sea water riser, gas tanks, structural parts for aerospace applications. Predicting the temperature in LATW has been a source of great interest since the temperature at nip-point plays a key role for mechanical interface performance. Modeling the LATW process includes several challenges such as the interaction of optics and heat transfer. In the current study, numerical modeling of the optical behavior of laser radiation on circular surfaces is investigated based on a ray tracing and non-specular reflection model. The non-specular reflection is implemented considering the anisotropic reflective behavior of the fiber-reinforced thermoplastic tape using a bidirectional reflectance distribution function (BRDF). The proposed model in the present paper includes a three-dimensional circular geometry, in which the effects of reflection from different ranges of the circular surface as well as effect of process parameters on temperature distribution are studied. The heat transfer model is constructed using a fully implicit method. The effect of process parameters on the nip-point temperature is examined. Furthermore, several laser distributions including Gaussian and linear are examined which has not been considered in literature up to now.

  20. Thermal Aspects of Ductile Mode Micro Laser Assisted Machining

    Science.gov (United States)

    Virkar, Saurabh R.; Patten, John A.

    2011-01-01

    This paper presents the simulation work performed to study an innovative process called micro-Laser Assisted Machining (μ-LAM). μ-LAM is being used for machining hard and brittle semiconductor and ceramic materials such as Silicon Carbide. Numerical simulations were carried out using the commercial software AdvantEdge Version 5.4. The cutting tool is modeled as a single point diamond tip. The workpiece material (4H-SiC) is heated locally during the actual machining process by a laser beam, which passes through the diamond tool tip. The workpiece is heated beyond the thermal softening point in order to study the effect of increased temperature on the machining process. The initial work started with an approximate thermal softening curve to ensure that thermal effects can be incorporated in the simulation model. A new thermal softening curve was developed based upon experimental data and implemented in the material model. A thermal boundary was provided on the workpiece top surface to simulate the effect of laser heating. In all three cases the chip formation was observed and the changes in cutting and thrust forces were evaluated. The simulation results indicate a significant decrease in machining forces if Silicon Carbide is heated and thermally softened thus demonstrating the benefits of the μ-LAM process.

  1. Early Experience in Femtosecond Laser-Assisted Cataract Surgery

    Directory of Open Access Journals (Sweden)

    Bilgehan Sezgin Asena

    2015-05-01

    Full Text Available Objectives: To analyze the early experience and intraoperative complications of femtosecond laser-assisted cataract and refractive lens exchange (RLE surgery. Materials and Methods: The initial 50 eyes of 29 patients who underwent cataract or RLE surgery between March 2013 and May 2013 were included in this study. All patients underwent anterior capsulotomy, lens fragmentation, and corneal incisions with the femtosecond laser (LenSx®, Alcon Inc.. The operation was completed by phacoemulsification and implantation of an intraocular lens. Intraoperative complications were evaluated from patient charts and video reviews retrospectively. Results: The mean age of the patients included was 63.8±11.7 years. No suction break or anterior capsule tear occurred in any case. Small anterior capsular tags occurred in 11 eyes (22%. The capsulotomy buttons were free-floating in 7 eyes (14%, while capsulorrhexis was partially completed with microadhesions in 40 eyes (60% and uncompleted in 3 eyes (6%. One eye (2% had a posterior capsule rupture secondary to increase in the intracapsular pressure. Corneal incisions either were not preferred to be used in 8 eyes (16% or could not be completed in 4 eyes (8%. Miosis occurred in 20 eyes (40%. No vision lost or dropped nuclei were observed. Conclusion: The use of femtosecond lasers in cataract and RLE surgery is safe. There had been no vision lost secondary to complications. (Turk J Ophthalmol 2015; 45: 97-101

  2. Surgical adhesives for laser-assisted wound closure

    Science.gov (United States)

    Hodges, Diane E.; McNally-Heintzelman, Karen M.; Welch, Ashley J.

    2001-10-01

    Solid protein solder-doped polymer membranes were developed for laser-assisted tissue repair. Biodegradable polymer membranes of controlled porosity were fabricated with poly(L-lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) (PEG), and salt particles, using a solvent-casting and particulate-leaching technique. The membranes provided a porous scaffold that readily absorbed the traditional protein solder composed of serum albumin, indocyanine green dye, and de-ionized water. In vitro investigations were conducted to assess the influence of various processing parameters on the strength of tissue repairs formed using the new membranes. These parameters included PLGA copolymer and PLGA/PEG blend ratios, membrane pore size, initial albumin weight fraction, and laser irradiance used to denature the solder. Altering the PLGA copolymer ratio had little effect on repair strength, however such variations are known to influence the degradation rate of the membranes. The repair strength increased with increased membrane pore size and bovine serum albumin concentration. The addition of PEG during the membrane casting stage increased the flexibility of the membranes but not necessarily the repair strength. Typically, the repair strength increased with increasing irradiance from 12 to 18 W/cm2. The new solder-doped polymer membranes provided all of the benefits associated with solid protein solders including high repair strength and improved edge coaptation. In addition, the flexible, moldable nature of the new membranes offers the capability of tailoring the membranes to a wide range of clinically relevant geometries.

  3. Femtosecond laser-assisted lamellar keratoplasty: early results.

    Science.gov (United States)

    Mosca, Luigi; Fasciani, Romina; Tamburelli, Ciro; Buzzonetti, Luca; Guccione, Laura; Mandarà, Erika; Balestrazzi, Emilio

    2008-07-01

    To evaluate the outcomes and safety of lamellar keratoplasty (LK) assisted by a femtosecond laser. Twenty-one eyes of 21 patients affected by different corneal pathologies (5 posttraumatic corneal scar, 3 postkeratitis corneal leucoma, and 13 keratoconus) underwent LK procedures by using a femtosecond laser. The mean thinnest corneal thickness, evaluated with ultrasound corneal pachymetry and with confocal microscopy, was 434.19 +/- 62.60 (SD) microm (range, 333-548 microm). Mean preoperative uncorrected visual acuity was 0.09 +/- 0.28 SD and mean preoperative best spectacle-corrected visual acuity was 0.28 +/- 0.15 SD. A femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The donor corneal lamella diameters were 0.20-mm larger and thicker than the recipient to restore a physiologic corneal thickness and shape: mean donor diameter was 8.34 +/- 0.28 mm (range, 8.2-8.7 mm) and mean thickness was 352 +/- 40.27 microm (range, 220-400 microm). Mean follow-up was 20.86 +/- 5.76 months (range, 12-30 months). Early postoperative evaluation showed a clear graft in all cases. A normal corneal pattern topography and a physiologic thickness (mean corneal pachymetry, 542.48 +/- 33.20 microm) and transparency were restored. Twelve months after surgery, the mean postoperative uncorrected visual acuity was 0.45 +/- 0.34 SD, and the mean best spectacle-corrected visual acuity was 0.63 +/- 0.16 SD. Although the numbers in our study are small, our early results indicate that femtosecond laser-assisted lamellar keratoplasty shows promise as a safe and effective surgical choice in the treatment of various corneal pathologies.

  4. Resident surgeon efficiency in femtosecond laser-assisted cataract surgery

    Directory of Open Access Journals (Sweden)

    Pittner AC

    2017-01-01

    Full Text Available Andrew C Pittner,1 Brian R Sullivan2 1Department of Ophthalmology, Stritch School of Medicine, Loyola University Chicago, Maywood, 2Edward Hines Jr VA Hospital, Ophthalmology Section, Hines, IL, USA Purpose: Comparison of resident surgeon performance efficiencies in femtosecond laser-assisted cataract surgery (FLACS versus conventional phacoemulsification.Patients and methods: A retrospective cohort study was conducted on consecutive patients undergoing phacoemulsification cataract surgery performed by senior ophthalmology residents under the supervision of 1 attending physician during a 9-month period in a large Veterans Affairs medical center. Medical records were reviewed for demographic information, preoperative nucleus grade, femtosecond laser pretreatment, operative procedure times, total operating room times, and surgical complications. Review of digital video records provided quantitative interval measurements of core steps of the procedures, including completion of incisions, anterior capsulotomy, nucleus removal, cortical removal, and intraocular lens implantation.Results: Total room time, operation time, and corneal incision completion time were found to be significantly longer in the femtosecond laser group versus the traditional phacoemulsification group (each P<0.05. Mean duration for manual completion of anterior capsulotomy was shorter in the laser group (P<0.001. There were no statistically significant differences in the individual steps of nucleus removal, cortical removal, or intraocular lens placement. Surgical complication rates were not significantly different between the groups.Conclusion: In early cases, resident completion of femtosecond cataract surgery is generally less efficient when trainees have more experience with traditional phacoemulsification. FLACS was found to have a significant advantage in completion of capsulotomy, but subsequent surgical steps were not shorter or longer. Resident learning curve for the

  5. Preliminary results of femtosecond laser-assisted descemet stripping endothelial keratoplasty.

    NARCIS (Netherlands)

    Cheng, Y.Y.; Hendrikse, F.; Pels, E.; Wijdh, R.J.; Cleynenbreugel, H. van; Eggink, C.A.; Rij, G. van; Rijneveld, W.J.; Nuijts, R.M.

    2008-01-01

    OBJECTIVE: To evaluate the preliminary visual results of femtosecond laser-assisted Descemet stripping endothelial keratoplasty (FS-DSEK). METHODS: We prospectively analyzed results of 20 consecutive patients with Fuchs endothelial dystrophy or aphakic/pseudophakic bullous keratopathy who underwent

  6. [Clinical results of femtosecond laser assisted lamellar keratoplasty].

    Science.gov (United States)

    Li, Shaowei; Ning, Jianhua; Liu, Chang; Guo, Zuofeng; Lyn, Fangqi; Chen, Tiehong

    2015-06-01

    To report the clinical results of femtosecond laser assisted lamellar keratoplasty (FS-LK). Retrospective study. Twenty eyes of 17 patients who were treated with FS-LK were enrolled in this study. The preoperative visions were from 0.02 to 0.4. During the operation, the grafts were prepared with a depth of 400-600 µm according to the character of the affections. During the follow-up period, the visions of 18 eyes (90%) were better than preoperative ones. One of them was equal to 0.8. The best corrected visual acuities of 18 eyes (90%) were better than or equal to 0.5, one of which was 1.0. The astigmatisms of 15 eyes were under 3.00 diopters at one year after operation. During the operation of two cases, the paracentral cut occurred. Two patients experienced corneal opacity, and two cases had high astigmatisms after operation. Only one eye experienced immune rejection at one year after operation. The FS-LK appears to be a good alternative surgical method for patients with corneal diseases because of the great manipuility and excellent postoperative results, but more research is needed.

  7. Thin-flap laser-assisted in situ keratomileusis.

    Science.gov (United States)

    Slade, Steven G

    2008-07-01

    Concerns regarding the increasing incidence of corneal ectasia following laser in situ keratomileusis procedures, together with increased understanding of the biomechanics of the cornea, has resulted in many refractive surgeons returning to surface ablation techniques such as photorefractive keratectomy. Even if surface ablation techniques offer a higher degree of safety than LASIK, they are associated with more pain and a slower visual recovery in the immediate postoperative period. This highlights the need for alternative procedures that offer the combined advantages of laser in situ keratomileusis and photorefractive keratectomy. Sub-Bowman's keratomileusis is a new procedure that provides the biomechanical stability and associated safety of photorefractive keratectomy with the visual results and reduced pain experience of laser in situ keratomileusis. This technique involves the use of the femtosecond laser to create a customized corneal flap of between 90 and 110 mum with a diameter based on the requirements of the individual patient and the type of excimer laser being used. This review outlines the rationale for sub-Bowman's keratomileusis and describes the efficacy, tolerability and safety of the procedure compared with photorefractive keratectomy.

  8. Femtosecond laser-assisted laser in situ keratomileusis versus photorefractive keratectomy: Effect on ocular surface condition.

    Science.gov (United States)

    Sauvageot, Paola; Julio, Gemma; Alvarez de Toledo, Juan; Charoenrook, Victor; Barraquer, Rafael I

    2017-02-01

    To compare ocular surface characteristics in eyes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Centro de Oftalmologia Barraquer, Barcelona, Spain. Prospective comparative observational study. Patients with myopia who had femtosecond laser-assisted LASIK or PRK were included. Tear osmolarity, the Ocular Surface Disease Index questionnaire, Schirmer I, corneal sensitivity, tear breakup time (TBUT), and corneal fluorescein staining were evaluated preoperatively and 3, 6, and 12 months postoperatively. The Wilcoxon signed-rank test was used for temporal intragroup analysis, and the Mann-Whitney U test was used for intergroup comparisons. The study comprised 44 patients (44 eyes) with myopia. Comparison of the parameters between the femtosecond laser-assisted LASIK group (22 eyes) and the PRK group (22 eyes) showed a similar temporal progression postoperatively. Compared with the preoperative evaluation, corneal sensitivity decreased after 3 months (P = .002 and P = .02, respectively) and 6 months (P = .03 and P = .04, respectively). The TBUT reached the highest mean value after 12 months (P = .01 and P = .04, respectively), and tear osmolarity was slightly increased after 1 year, although the mean values remained within the normal range (P = .01 and P = .04, respectively). The only difference between the 2 groups was lower corneal sensitivity in the femtosecond laser-assisted LASIK group after 3 months (P = .02). The ocular surface condition could be considered clinically unaltered after 1 year in both groups. Femtosecond laser-assisted LASIK and PRK techniques seemed to be safe for the ocular surface condition and to have a similar effect on it. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  9. Study on laser-assisted drug delivery with optical coherence tomography

    Science.gov (United States)

    Tsai, Wen-Guei; Tsai, Ting-Yen; Yang, Chih-Hsun; Tsai, Meng-Tsan

    2017-04-01

    The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. Nail plate divided into three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO2 laser that produces arrays of microthermal ablation zones (MAZs) to facilitate drug delivery in the nails. Moreover, optical coherence tomography (OCT) is implemented for real-time monitoring of the laser-skin tissue interaction, sparing the patient from invasive surgical sampling procedure. Observations of drug diffusion through the induced MAZ array are achieved by evaluating the time-dependent OCT intensity variance. Subsequently, nails are treated with cream and liquid topical drugs to investigate the feasibility and diffusion efficacy of laser-assisted drug delivery. Our results show that fractional CO2 laser improves the efficacy of topical drug delivery in the nail plate, and that OCT could potentially be used for in vivo monitoring of the depth of laser penetration as well as real-time observations of drug delivery.

  10. Study of the influences of laser parameters on laser assisted machining processes

    OpenAIRE

    Tagliaferri, Flaviana; Leopardi, Giacomo; Semmler, Ulrich; Kuhl, Michael; Palumbo, Biagio

    2013-01-01

    Hybrid machining processes using additional energy sources such as laser assisted machining (LAM) have increased considerably during the last years. The benefits of LAM for reducing tool wear and cutting forces are well known, especially for superalloys. However, optimal machining results depend on both the laser parameters and the cutting process parameters. It is difficult to find optimal LAM settings due to the complexity of the influencing parameters and their mutual interactions. The aim...

  11. Evaluation of Laser-Assisted Trans-Nail Drug Delivery with Optical Coherence Tomography

    Directory of Open Access Journals (Sweden)

    Meng-Tsan Tsai

    2016-12-01

    Full Text Available The nail provides a functional protection to the fingertips and surrounding tissue from external injuries. The nail plate consists of three layers including dorsal, intermediate, and ventral layers. The dorsal layer consists of compact, hard keratins, limiting topical drug delivery through the nail. In this study, we investigate the application of fractional CO2 laser that produces arrays of microthermal ablation zones (MAZs to facilitate drug delivery in the nails. We utilized optical coherence tomography (OCT for real-time monitoring of the laser–skin tissue interaction, sparing the patient from an invasive surgical sampling procedure. The time-dependent OCT intensity variance was used to observe drug diffusion through an induced MAZ array. Subsequently, nails were treated with cream and liquid topical drugs to investigate the feasibility and diffusion efficacy of laser-assisted drug delivery. Our results show that fractional CO2 laser improves the effectiveness of topical drug delivery in the nail plate and that OCT could potentially be used for in vivo monitoring of the depth of laser penetration as well as real-time observations of drug delivery.

  12. Laser-assisted cavity preparation and adhesion to erbium-lased tooth structure: part 1. Laser-assisted cavity preparation.

    Science.gov (United States)

    De Moor, Roeland Jozef Gentil; Delmé, Katleen Ilse Maria

    2009-12-01

    The use of the ruby laser (693.4 nm) was first described in 1960, and it was applied for hard tissue ablation in 1964. Different wavelengths [Nd:YAG (1.065 microm), CO2 (9.6 microm), Ho:YAG (2.12 microm)] were consequently explored. Due to massive thermal side effects, these wavelengths caused increased temperature in dental pulp, as well as microcracks and carbonization. The use of this laser for dental hard tissue preparation was eventually abandoned. At the end of the 1980s, excimer lasers (ultraviolet) and the erbium laser (infrared) were developed, with the advantages of improved temperature control and smaller penetration depths. With the development of smaller devices and improved knowledge of how to limit damage to the surrounding tissues, new ablation techniques were established in the 1990s. There is still contradiction in the current literature, however, in that different wavelengths are advocated for hard tissue removal, and heterogeneity in laser parameters and power densities remain. In this review, the effects of the wavelengths presently used for cavity preparation are evaluated. We conclude that erbium lasers (Er:YAG and Er,Cr:YSGG) are most efficient and, with the right parameters, the thermal side effects are small. There is a substantial need for "gold standards", although this is difficult to establish in practice owing to different laser parameters (including pulse repetition rate, amount of cooling, energy delivered per pulse, and types of pulses) and target specificity (tissue interaction with sound or decayed enamel or dentin, and the extent of (de)mineralization) which influence tissue interaction.

  13. Laser and optical system for laser assisted hydrogen ion beam stripping at SNS

    Science.gov (United States)

    Liu, Y.; Rakhman, A.; Menshov, A.; Webster, A.; Gorlov, T.; Aleksandrov, A.; Cousineau, S.

    2017-03-01

    Recently, a high-efficiency laser assisted hydrogen ion (H-) beam stripping was successfully carried out in the Spallation Neutron Source (SNS) accelerator. The experiment was not only an important step toward foil-less H- stripping for charge exchange injection, it also set up a first example of using megawatt ultraviolet (UV) laser source in an operational high power proton accelerator facility. This paper reports in detail the design, installation, and commissioning result of a macro-pulsed multi-megawatt UV laser system and laser beam transport line for the laser stripping experiment.

  14. Early clinical research on the femtosecond laser assisted penetrating keratoplasty

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2014-12-01

    Full Text Available AIM: To evaluate the therapeutic effects and safety of femtosecond laser assisted penetrating keratoplasty(FS-PKP.METHODS: In the retrospective case series study, 46 cases(48 eyeswith FS- PKP holds were analyzed. Preoperative best corrected visual acuity(BCVAwas 2.35±1.01(with a standard logarithmic eye chart. Opacities were all from epithelium to endothelium, including keratoconus, keratolukoma and corneal scarring etc. The full-thickness corneal donor-recipient grafts in different diameter and incision kerfangle were made by femtosecond laser in keratoplasty. The patients were treated according to the conventional penetrating keratoplasty after surgery. Evaluation indexes included preoperative and postoperative 1,6,10mo uncorrected visual acuity(UCVA, BCVA, corneal astigmatism(CAand surgical complications. Forty-three cases(44 eyeswith traditional PKP were as control group. The data of two groups were analyzed by mean comparison of two groups and Chi-square test in SPSS 18.0. RESULTS: All the operations were completed successfully, postoperative visual acuity of all patients had different degrees of increase. Comparison with the postoperative UCVA of traditional PKP surgery, UCVA was 3.48±0.43 and 2.97±1.14 at 1mo after operation, respectively, with statistically significant difference(P=0.009. The UCVA was 3.86±0.25 and 3.74±0.73 at 3mo after operation, respectively; the UCVA was 4.04±0.23 and 3.98±0.29 at 6mo after operation, respectively, with no statistically significant difference(P=0.146, P=0.56. In FS-PKP group, BCVA was better than traditional PKP surgery group, with statistically significant difference(P=0.002. While there had no statistically significant difference between two groups of BCVA at 6, 10mo after operation(P6mo=0.132, P10mo=0.47. The incidence of complication of FS-PKP surgery, such as postoperative astigmatism, postoperative intraocular pressure and postoperative incision dehiscence were significantly lower than

  15. Fundamentals of laser-assisted fabrication of inorganic and organic films

    DEFF Research Database (Denmark)

    Schou, Jørgen

    2008-01-01

    The standard method for producing films by laser-assisted methods, Pulsed Laser Deposition (PLD) will be reviewed. The films considered are usually inorganic films, but also films of organic materials have been produced. Also the deposition of organic films by MAPLE (Matrix Assisted Pulsed Laser ...

  16. The Evaluation of Surface Integrity During Machining of Inconel 718 with Various Laser Assistance Strategies

    Directory of Open Access Journals (Sweden)

    Wojciechowski Szymon

    2017-01-01

    Full Text Available The paper is focused on the evaluation of surface integrity formed during turning of Inconel 718 with the application of various laser assistance strategies. The primary objective of the work was to determine the relations between the applied machining strategy and the obtained surface integrity, in order to select the effective cutting conditions allowing the obtainment of high surface quality. The carried out experiment included the machining of Inconel 718 in the conventional turning conditions, as well as during the continuous laser assisted machining and sequential laser assistance. The surface integrity was evaluated by the measurements of machined surface topographies, microstructures and the microhardness. Results revealed that surface integrity of Inconel 718 is strongly affected by the selected machining strategy. The significant improvement of the surface roughness formed during machining of Inconel 718, can be reached by the application of simultaneous laser heating and cutting (LAM.

  17. Laser ablation principles and applications

    CERN Document Server

    1994-01-01

    Laser Ablation provides a broad picture of the current understanding of laser ablation and its many applications, from the views of key contributors to the field. Discussed are in detail the electronic processes in laser ablation of semiconductors and insulators, the post-ionization of laser-desorbed biomolecules, Fourier-transform mass spectroscopy, the interaction of laser radiation with organic polymers, laser ablation and optical surface damage, laser desorption/ablation with laser detection, and laser ablation of superconducting thin films.

  18. Mechanical and microstructural evaluation of laser assisted cold sprayed bioceramic coatings: potential use for biomedical applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available Coatings of commercial pure titanium (CP)-Ti and HAP bio-ceramic were synthesised on Ti-6Al-4V substrate using laser assisted cold spray (LACS) deposition technique. The LACS system comprised of 4.4 kW Nd:YAG laser system, AT-12000HPHV 5000PSI (35...

  19. Miniaturized reaction chamber for optimized laser-assisted carbon nanotube growth

    NARCIS (Netherlands)

    Burgt, Y. van de; Loon, W. van; Mandamparambil, R.; Bellouard, Y.

    2014-01-01

    The localized growth of carbon nanotube structures has potential in many applications such as interconnects, field emitters and sensors. Using a laser to locally heat the substrate offers a highly versatile process compatible with a broad range of substrates and devices. However, for laser-assisted

  20. Laser-assisted lip repositioning surgery: Novel approach to treat gummy smile

    Directory of Open Access Journals (Sweden)

    Sana Farista

    2017-01-01

    Full Text Available Excessive gingival display (EGD resulting in a “gummy smile” is a major esthetic concern with ramifications in an individual's personal and social life. Numerous treatment modalities have been used for the correction of EGD. The present case report describes the successful treatment of a young woman with an excess gingival display caused by a hyperactive upper lip and a mild vertical maxillary excess that was treated with a laser-assisted lip repositioning surgical technique accompanied by gingival recontouring. The procedure was accomplished by laser-assisted removal, through scraping a strip of mucosa from the maxillary buccal vestibule and suturing the mucosa of the lip to the mucogingival junction. This technique resulted in shortened vestibule and restricted the muscle pull of the elevator muscles of the lip, thereby reducing gingival display when the patient smiles. Laser-assisted lip repositioning surgery can be a viable, minimally invasive alternative to orthognathic surgery.

  1. Microstructure-sensitive flow stress modeling for force prediction in laser assisted milling of Inconel 718

    Directory of Open Access Journals (Sweden)

    Pan Zhipeng

    2017-01-01

    Full Text Available Inconel 718 is a typical hard-to-machine material that requires thermally enhanced machining technology such as laser-assisted milling. Based upon finite element analysis, this study simulates the forces in the laser-assisted milling process of Inconel 718 considering the effects of grain growth due to γ' and γ" phases. The γ" phase is unstable and becomes the δ phase, which is likely to precipitate at a temperature over 750 °C. The temperature around the center of spot in the experiments is 850 °C, so the phase transformation and grain growth happen throughout the milling process. In the analysis, this study includes the microstructure evolution while accounting for the effects of dynamic recrystallization and grain growth through the Avrami model. The grain growth reduces the yield stress and flow stress, which improves the machinability. In finite element analysis (FEA, several boundary conditions of temperature varying with time are defined to simulate the movement of laser spot, and the constitutive model is described by Johnson-Cook equation. In experiments, this study collects three sets of cutting forces and finds that the predicted values are in close agreements with measurements especially in feed direction, in which the smallest error is around 5%. In another three simulations, this study also examines the effect of laser preheating on the cutting forces by comparison with a traditional milling process without laser assist. When the laser is off, the forces increase in all cases, which prove the softening effect of laser-assisted milling. In addition, when the axial depth of milling increases, the laser has a more significant influence, especially in axial direction, in which the force with laser is more than 18% smaller than the one without laser. Overall, this study validates the influence of laser-assisted milling on Inconel 718 by predicting the cutting forces in FEA.

  2. Comparison of Long-Term Outcomes of Femtosecond Laser-Assisted Keratoplasty with Conventional Keratoplasty.

    Science.gov (United States)

    Daniel, Moritz C; Böhringer, Daniel; Maier, Philip; Eberwein, Philipp; Birnbaum, Florian; Reinhard, Thomas

    2016-03-01

    Astigmatism is a significant problem in penetrating keratoplasty. Lower astigmatism and better visual outcomes had been expected from laser-assisted penetrating keratoplasty, that is, from the top-hat, mushroom, or zig-zag cutting profiles. We report the long-term outcomes of 141 femtosecond laser-assisted penetrating keratoplasties retrospectively. We compare these outcomes with those of penetrating keratoplasty using the guided trephine system (GTS). In all, 141 femtosecond laser-assisted penetrating keratoplasties had been performed in 119 patients. The results were compared with those of conventional keratoplasty (n = 1254; visual and refractive outcomes, graft rejections, and graft failure). Follow-up averaged 33 months. In eyes with keratoconus, the time to achieve a visual acuity of 10/20 (Snellen) was shorter in the mushroom than in the GTS group. However, there was no relevant long-term difference. Graft astigmatism was higher in the laser groups [keratometric astigmatism at the end of follow-up: -4.5 ± 4 (GTS), -5.8 ± 3.3 (top-hat), -5.9 ± 3.2 D (mushroom); P keratoplasty resulted in lower rates of rejection than GTS keratoplasty (31%). There is no significant difference in the refractive and visual outcomes after femtosecond laser-assisted penetrating keratoplasty compared with GTS keratoplasty. The benefits from the use of the femtosecond laser may be limited and should be weighed against an increased risk of immune reactions, higher surgical complexity, and higher costs.

  3. Laser-assisted cell printing: principle, physical parameters versus cell fate and perspectives in tissue engineering.

    Science.gov (United States)

    Guillemot, Fabien; Souquet, Agnès; Catros, Sylvain; Guillotin, Bertrand

    2010-04-01

    We describe the physical parameters involved in laser-assisted cell printing and present evidence that this technology is coming of age. Finally we discuss how this high-throughput, high-resolution technique may help in reproducing local cell microenvironments, and thereby create functional tissue-engineered 3D constructs.

  4. Efficacy and safety of femtosecond laser-assisted corneal endothelial keratoplasty: a randomized multicenter clinical trial.

    NARCIS (Netherlands)

    Cheng, Y.Y.; Schouten, J.S.A.G.; Tahzib, N.G.; Wijdh, R.J.; Pels, E.; Cleynenbreugel, H. van; Eggink, C.A.; Rijneveld, W.J.; Nuijts, R.M.

    2009-01-01

    BACKGROUND: To evaluate the efficacy and safety of femtosecond laser-assisted endothelial keratoplasty (FLEK) versus penetrating keratoplasty (PK) in patients with corneal endothelial disease. METHODS: A randomized multicenter clinical trial of 80 eyes of 80 patients with corneal endothelial disease

  5. Efficacy and Safety of Femtosecond Laser-Assisted Corneal Endothelial Keratoplasty : A Randomized Multicenter Clinical Trial

    NARCIS (Netherlands)

    Cheng, Yanny Y. Y.; Schouten, Jan S. A. G.; Tahzib, Nayyirih G.; Wijdh, Robert-Jan; Pels, Elisabeth; van Cleynenbreugel, Hugo; Eggink, Catharina A.; Rijneveld, Wilhelmina J.; Nuijts, Rudy M. M. A.

    2009-01-01

    Background. To evaluate the efficacy and safety of femtosecond laser-assisted endothelial keratoplasty (FLEK) versus penetrating keratoplasty (PK) in patients with corneal endothelial disease. Methods. A randomized multicenter clinical trial of 80 eyes of 80 patients with corneal endothelial disease

  6. Preliminary results of femtosecond laser-assisted descemet stripping endothelial keratoplasty

    NARCIS (Netherlands)

    Cheng, Yanny Y. Y.; Hendrikse, Fred; Pels, Elisabeth; Wijdh, Robert-Jan; van Cleynenbreugel, Hugo; Eggink, Cathariena A.; van Rij, Gabriel; Rijneveld, Wilhelmina J.; Nuijts, Rudy M. M. A.

    2008-01-01

    Objective: To evaluate the preliminary visual results of femtosecond laser-assisted descemet stripping endothelial keratoplasty (FS-DSEK). keratoplasty (FS-DSEK). Methods: We prospectively analyzed results of 20 consecutive patients with Fuchs endothelial dystrophy or aphakic/pseudophakic bullous

  7. Long-term outcomes of laser-assisted uvulopalatoplasty in 168 patients with snoring

    NARCIS (Netherlands)

    Iyngkaran, T.; Kanagalingam, J.; Rajeswaran, R.; Georgalas, C.; Kotecha, B.

    2006-01-01

    Laser-assisted uvulopalatoplasty (LAUP) is an established treatment for snoring. Our institution has been using a modification of the Kamami technique since 1995. Between January 1995 and December 2001, 469 patients underwent LAUP for snoring. A telephone survey of these patients and their partners

  8. Laser assisted cold spraying of aluminium alloy powder on stainless steel substrate

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2012-12-01

    Full Text Available International Conference on Information Warfare and Security, Denver, USA 25-26 March 2013 LASER ASSISTED COLD SPRAYING OF ALUMINIUM ALLOY POWDER ON STAINLESS STEEL SUBSTRATE M. Tlotleng1, 2; E.O. Olakanmi2; C. Meacock; Sisa Pityana1, 3; E.T. Akinlabi2...

  9. A report of laser-assisted modified Widman flap for periodontal regeneration: Clinical and radiographic evaluation.

    Science.gov (United States)

    Salaria, Sanjeev Kumar; Madaan, Veenu; Bala, Deepak

    2010-04-01

    Periodontitis is a relatively common disease. Various therapies have been recommended for its treatment which includes nonsurgical, antimicrobial, and surgical therapy. In recent years lasers have been used for all the three above-mentioned purposes. Lasers have been applied for hard and soft tissue debridement, contouring as well as the bacterial load reduction in the pocket. Here we present a case report of chronic periodontitis treated with the help of a new technique, laser-assisted modified Widman flap (LAMWF). The surgical procedure followed with a 980 nm diode laser has been described. The present case report resulted in significant pocket depth reduction, attachment gain, and radiographic evidence of bone fill. The laser-assisted modified Widman flap provided excellent results without complications and high patient as well as clinician satisfaction.

  10. A report of laser-assisted modified Widman flap for periodontal regeneration: Clinical and radiographic evaluation

    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar Salaria

    2010-01-01

    Full Text Available Periodontitis is a relatively common disease. Various therapies have been recommended for its treatment which includes nonsurgical, antimicrobial, and surgical therapy. In recent years lasers have been used for all the three above-mentioned purposes. Lasers have been applied for hard and soft tissue debridement, contouring as well as the bacterial load reduction in the pocket. Here we present a case report of chronic periodontitis treated with the help of a new technique, laser-assisted modified Widman flap (LAMWF. The surgical procedure followed with a 980 nm diode laser has been described. The present case report resulted in significant pocket depth reduction, attachment gain, and radiographic evidence of bone fill. The laser-assisted modified Widman flap provided excellent results without complications and high patient as well as clinician satisfaction.

  11. Characteristics of laser assisted machining for silicon nitride ceramic according to machining parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Do; Lee, Su Jin [Korea Maritime University, Busan (Korea, Republic of); Suh, Jeong [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2011-04-15

    This paper describes the Laser Assisted Machining (LAM) that cuts and removes softened parts by locally heating the ceramic with laser. Silicon nitride ceramics can be machined with general machining tools as well, because YSiAlON, which was made up ceramics, is soften at about 1,000 .deg. C. In particular, the laser, which concentrates on highly dense energy, can locally heat materials and very effectively control the temperature of the heated part of specimen. Therefore, this paper intends to propose an efficient machining method of ceramic by deducing the machining governing factors of laser assisted machining and understanding its mechanism. While laser power is the machining factor that controls the temperature, the CBN cutting tool could cut the material more easily as the material gets deteriorated from the temperature increase by increasing the laser power, but excessive oxidation can negatively affect the quality of the material surface after machining. As the feed rate and cutting depth increase, the cutting force increases and tool lifespan decreases, but surface oxidation also decreases. In this experiment, the material can be cut to 3 mm of cutting depth. And based on the results of the experiment, the laser assisted machining mechanism is clarified.

  12. Prospective evaluation of CO2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C.

    Science.gov (United States)

    Cutolo, Carlo Alberto; Bagnis, Alessandro; Scotto, Riccardo; Bonzano, Chiara; Traverso, Carlo Enrico

    2018-01-01

    Our purpose was to evaluate the clinical safety and efficacy of CO2 laser-assisted sclerectomy surgery (CLASS) with Mitomycin C (MMC) in open angle glaucoma (OAG). This was a prospective, uncontrolled, interventional case series. All subjects underwent CLASS procedure by a single surgeon. After the dissection of a partial thickness scleral flap, topical MMC 0.2 mg/ml was applied to the sclera and the conjunctiva for 3 min. The CO2 laser with a beam-manipulating system was used to ablate the scleral tissue and expose the Schlemm's canal area. Primary outcomes: intraocular pressure (IOP) change, number of IOP-lowering medicaments change. Adverse events were evaluated as secondary outcomes. Twenty-one eyes of 21 patients underwent the CLASS procedure. Thirteen were primary OAG (62%), two normal pressure glaucoma (10%), three exfoliative glaucoma (14%) and three others secondary OAG. With a mean (SD) follow-up of 15.3 (5.9) months, the IOP changed from 25.4 (6.7) mmHg at baseline to 10.9 (3.4) mmHg al the last visit. Mean reduction of IOP was -14.5 mmHg (95% CI, -17.7 to -11.2, P maculopathy successfully treated with placement of additional transconjunctival scleral flap sutures. The CLASS procedure with MMC is clinically safe and effective maintaining a large reduction in IOP and in the number of IOP-lowering medications with a mean follow-up of 15 months. Iris adhesion at the filtrating area warrants further evaluation and possibly reflects the surgeon's learning curve.

  13. Comparison of the external physical damages between laser-assisted and mechanical immobilized human sperm using scanning electronic microscopy.

    Science.gov (United States)

    Chan, David Y L; Li, Tin Chiu

    2017-01-01

    We aim to visualize the external physical damages and distinct external phenotypic effects between mechanical and laser-assisted immobilized human spermatozoa using scanning electronic microscopy (SEM). Human spermatozoa were immobilized mechanically or with laser assistance for SEM examination and the membrane integrities were checked on both types of immobilized spermatozoa. We found evidence of external damages at SEM level on mechanically kinked sperm, but not on laser-assisted immobilized sperm. Although no external damage was found on laser-assist immobilized sperm, there were two distinct types of morphological changes when spermatozoa were stricken by infra-red laser. Coiled tails were immediately formed when Laser pulse was applied to the sperm end piece area, whereas laser applied to the sperm principal piece area resulted in a sharp bend of sperm tails. Sperm immobilized by laser did not exhibit any morphological change if the laser did not hit within the on-screen central target zone or if the laser hit the sperm mid piece or head. Our modified membrane integrity assay revealed that the external membrane of more than half of the laser-assisted immobilized sperm remained intact. In conclusion, mechanical immobilization produced membrane damages whilst laser-assisted immobilization did not result in any external membrane damages besides morphological changes at SEM level.

  14. Laser-assisted machining process simulation for precision mould/die manufacturing

    OpenAIRE

    Zeng Quanren; Qin Yi

    2015-01-01

    Laser-assisted machining (LAM) is a kind of thermally assisted manufacturing process which preheats workpiece material with a highly-localized laser beam and then is followed by a conventional machining operation. It could greatly improve the machinability and gives better machining quality, especially suitable for hard-to-cut materials such as superalloys, tool steels. For manufacturing the high-precision moulds/dies that could fabricate micro and precision components, the thermal assistance...

  15. Tool life of diamond inserts after laser assisted turning of cemented carbides

    Directory of Open Access Journals (Sweden)

    Kieruj Piotr

    2017-01-01

    Full Text Available The paper presents results and discussion on parameters influence on tool life when turning laser cladded cemented carbides under laser assisted machining (LAM conditions. The layers are known as Technolase 30S. This material is widely recognized as hard-to-cut. The experimental investigation was carried out with diamond inserts. The laser power density, feed rate and laser scanning speed were analysed. Flank wear (VBc indicator was measured and cutting tool life was calculated. It was proved that Technolase 30S can be machined with LAM technology. The laser enhanced turning is more efficient than conventional turning and grinding.

  16. Use and Evaluation of a Cooling Aid in Laser-Assisted Dental Surgery: An Innovative Study.

    Science.gov (United States)

    Bernardi, Sara; Mummolo, Stefano; Zeka, Keti; Pajewski, Leonardo; Continenza, Maria Adelaide; Marzo, Giuseppe

    2016-06-01

    The aim of this study was to evaluate the beneficial effect of NeoHeal during laser-assisted oral surgery. Laser-assisted surgery is a less invasive technique than conventional surgery using a blade; however, the heat produced by the laser can damage tissue proximal to the treated area. We hypothesized the hydrogel NeoHeal could be applied during oral surgery and have similar benefits as those already described for dermatological surgery. In our randomized controlled trial, we first selected 30 patients who were to undergo laser surgical intervention using a diode laser. Both at the end of intervention and at follow-up, each patient filled out a questionnaire comprising two questions. The answers to the questions were statistically analyzed with regard to frequency of each response, and validated by the Wilcoxon test with a p value <0.05 being considered significant. The use of NeoHeal significantly reduced the pain experienced by patients both during the intervention and at the 7-day follow-up. NeoHeal clearly reduces surgery-related pain experienced by patients. The results show positive feedback from the patients, demonstrating how the hydrogel pads are necessary, useful, and effective as a cooling aid in laser-assisted dental surgery.

  17. Process energy analysis for aluminium alloy and stainless steel in laser-assisted jet electrochemical machining

    Energy Technology Data Exchange (ETDEWEB)

    Pajak, P.; De Silva, A.; Harrison, D. [Glasgow Caledonian University (United Kingdom). School of Engineering, Science, and Design; McGeough, J. [Edinburgh Univ. (United Kingdom). School of Engineering and Electronics

    2006-07-01

    Laser-assisted jet electrochemical machining (LAJECM) is a hybrid process that combines a relatively low-power laser beam (typically 375 mW) with an electrolyte jet to facilitate metal removal. The main purpose of the laser is to enhance the localization effect of electrochemical dissolution from the workpiece, thus giving better precision and efficiency. The laser thermally activates the material surface where it impinges, thereby increasing the electrochemical current density in that localized zone. This paper reports recent investigations of LAJECM process energy distribution and explains the influence of laser assistance on dissolution removal rates using theoretical as well as experimental analysis. It was found that laser assistance increases energy in the LAJECM process by up to 45 per cent compared with jet electrochemical machining (JECM). The process energy has also been related to volumetric removal rate, and the specific energy required for machining with given variables has been calculated. It has been proved that LAJECM is more effective then JECM as the calculated specific energy was lower by up to 30 per cent. [Author].

  18. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching.

    Science.gov (United States)

    Ghanbarzadeh, Majid; Ahrari, Farzaneh; Akbari, Majid; Hamzei, Haniye

    2015-07-01

    There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (phome bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching.

  19. Laser-assisted deposition of thin C60 films

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Fæster, Søren

    . However, organic materials are usually not well suited for direct laser irradiation, since the organic molecules may suffer from fragmentation by the laser light. We have, therefore, explored the possible fragmentation of organic molecules by attempting to produce thin films of C60 which is a strongly...... bound carbon molecule with a well-defined mass (M = 720 amu) and therefore a good, organic test molecule. C60 fullerene thin films of average thickness of more than 100 nm was produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target...

  20. Laser-assisted printing of alginate long tubes and annular constructs.

    Science.gov (United States)

    Yan, Jingyuan; Huang, Yong; Chrisey, Douglas B

    2013-03-01

    Laser-assisted printing such as laser-induced forward transfer has been well studied to pattern or fabricate two-dimensional constructs. In particular, laser printing has found increasing biomedical applications as an orifice-free cell and organ printing approach, especially for highly viscous biomaterials and biological materials. Unfortunately, there have been very few studies on the efficacy of three-dimensional printing performance of laser printing. This study has investigated the feasibility of laser tube printing and the effects of sodium alginate concentration and operating conditions such as the laser fluence and laser spot size on the printing quality during laser-assisted printing of alginate annular constructs (short tubes) with a nominal diameter of 3 mm. It is found that highly viscous materials such as alginate can be printed into well-defined long tubes and annular constructs. The tube wall thickness and tube outer diameter decrease with the sodium alginate concentration, while they first increase, then decrease and finally increase again with the laser fluence. The sodium alginate concentration dominates if the laser fluence is low, and the laser fluence dominates if the sodium alginate concentration is low.

  1. Circular dichroism in laser-assisted proton-hydrogen collisions

    Science.gov (United States)

    Niederhausen, Thomas; Feuerstein, Bernold; Thumm, Uwe

    2004-08-01

    We investigate the effects of a strong laser field on the dynamics of electron capture and emission in ion-atom collisions within a reduced dimensionality model of the scattering system in which the motion of the active electron and the laser electric field vector are confined to the scattering plane. We examine the probabilities for electron capture and ionization as a function of the laser intensity, the projectile impact parameter b , and the laser phase ϕ that determines the orientation of the laser electric field with respect to the internuclear axis at the time of closest approach between target and projectile. Our results for the b -dependent ionization and capture probabilities show a strong dependence on both ϕ and the helicity of the circularly polarized laser light. For intensities above 5×1012W/cm2 our model predicts a noticeable circular dichroism in the capture probability for slow proton-hydrogen collisions, which persists after averaging over ϕ . Capture and electron emission probabilities defer significantly from results for laser-unassisted collisions. Furthermore, we find evidence for a charge-resonance-enhanced ionization mechanism that may enable the measurement of the absolute laser phase ϕ .

  2. CdS thin films prepared by laser assisted chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, L.V.; Mendivil, M.I.; Garcia Guillen, G.; Aguilar Martinez, J.A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); CIIDIT – Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Avellaneda, D.; Castillo, G.A.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); CIIDIT – Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2015-05-01

    Highlights: • CdS thin films by conventional CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • Improved dark conductivity and good photocurrent response for the LACBD CdS. - Abstract: In this work, we report the preparation and characterization of CdS thin films by laser assisted chemical bath deposition (LACBD). CdS thin films were prepared from a chemical bath containing cadmium chloride, triethanolamine, ammonium hydroxide and thiourea under various deposition conditions. The thin films were deposited by in situ irradiation of the bath using a continuous laser of wavelength 532 nm, varying the power density. The thin films obtained during deposition of 10, 20 and 30 min were analyzed. The changes in morphology, structure, composition, optical and electrical properties of the CdS thin films due to in situ irradiation of the bath were analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The thin films obtained by LACBD were nanocrystalline, photoconductive and presented interesting morphologies. The results showed that LACBD is an effective synthesis technique to obtain nanocrystalline CdS thin films having good optoelectronic properties.

  3. Surface roughness analysis after laser assisted machining of hard to cut materials

    Science.gov (United States)

    Przestacki, D.; Jankowiak, M.

    2014-03-01

    Metal matrix composites and Si3N4 ceramics are very attractive materials for various industry applications due to extremely high hardness and abrasive wear resistance. However because of these features they are problematic for the conventional turning process. The machining on a classic lathe still requires special polycrystalline diamond (PCD) or cubic boron nitride (CBN) cutting inserts which are very expensive. In the paper an experimental surface roughness analysis of laser assisted machining (LAM) for two tapes of hard-to-cut materials was presented. In LAM, the surface of work piece is heated directly by a laser beam in order to facilitate, the decohesion of material. Surface analysis concentrates on the influence of laser assisted machining on the surface quality of the silicon nitride ceramic Si3N4 and metal matrix composite (MMC). The effect of the laser assisted machining was compared to the conventional machining. The machining parameters influence on surface roughness parameters was also investigated. The 3D surface topographies were measured using optical surface profiler. The analysis of power spectrum density (PSD) roughness profile were analyzed.

  4. Antimony sulfide thin films prepared by laser assisted chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shaji, S., E-mail: sshajis@yahoo.com [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); Garcia, L.V. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); Loredo, S.L. [Centro de Investigación en Materiales Avanzados (CIMAV), Unidad Monterrey, PIIT, Apodaca, Nuevo León (Mexico); Krishnan, B. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Av. Pedro de Alba s/n, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, 66455 (Mexico); CIIDIT—Universidad Autónoma de Nuevo León, Apodaca, Nuevo León (Mexico); and others

    2017-01-30

    Highlights: • Antimony sulfide thin films were prepared by normal CBD and laser assisted CBD. • Characterized these films using XRD, XPS, AFM, optical and electrical measurements. • Accelerated growth was observed in the laser assisted CBD process. • These films were photoconductive. - Abstract: Antimony sulfide (Sb{sub 2}S{sub 3}) thin films were prepared by laser assisted chemical bath deposition (LACBD) technique. These thin films were deposited on glass substrates from a chemical bath containing antimony chloride, acetone and sodium thiosulfate under various conditions of normal chemical bath deposition (CBD) as well as in-situ irradiation of the chemical bath using a continuous laser of 532 nm wavelength. Structure, composition, morphology, optical and electrical properties of the Sb{sub 2}S{sub 3} thin films produced by normal CBD and LACBD were analyzed by X-Ray diffraction (XRD), Raman Spectroscopy, Atomic force microscopy (AFM), X-Ray photoelectron spectroscopy (XPS), UV–vis spectroscopy and Photoconductivity. The results showed that LACBD is an effective synthesis technique to obtain Sb{sub 2}S{sub 3} thin films for optoelectronic applications.

  5. Laser assisted die bending: a new application of high power diode lasers

    Science.gov (United States)

    Schuöcker, D.; Schumi, T.; Spitzer, O.; Bammer, F.; Schuöcker, G.; Sperrer, G.

    2015-02-01

    Nowadays high power lasers are mainly used for cutting of sheet metals, for welding, hardening and rapid prototyping. In the forming of sheet metals as bending or deep drawing lasers are not used. Nevertheless a few years ago a new application of high power lasers has been invented, where bending of materials that break at room temperature becomes possible by heating them along the bending edge with high power lasers thus allowing their treatment without cracks and rupture. For this purpose a large number of diode lasers are arranged in the bottom tool of a bending machine (a V-shaped die) which heat up the initially flat sheet metal during the bending process what is performed by pressing it into the die with a knife shaped upper tool where due to the laser heating the material is softened and thus cracks are avoided. For the technical realization of the new process of laser assisted die bending, modules equipped with numerous laser diodes and a total beam power of 2,5 kW are used. The light emitted by these modules enters a tool with a length of 15cm and is deflected towards the workpiece. By using ten of these modules with adjacent dies and by integrating those in a bending press a bending edge of sheet metals with a length of 1500mm can be realized. Such a bending press with laser assistance also needs energization with a power of practically 50kW, a respective water flow, a heat exchanger system and also a control for all functions of this system. Special measures have also been developed to avoid radiating of those tools that are not covered by a workpiece in the case of bending edges shorter than the full length of the bending tools whereas individual short circuiting of diode modules can be performed. Specific measures to ensure a safe operation without any harm to the operational person have been realized. Exploitation of the bending process has been carried out for titanium, where material thicknesses up to 3mm have been bent successfully.

  6. System technology for laser-assisted milling with tool integrated optics

    Science.gov (United States)

    Hermani, Jan-Patrick; Emonts, Michael; Brecher, Christian

    2013-02-01

    High strength metal alloys and ceramics offer a huge potential for increased efficiency (e. g. in engine components for aerospace or components for gas turbines). However, mass application is still hampered by cost- and time-consuming end-machining due to long processing times and high tool wear. Laser-induced heating shortly before machining can reduce the material strength and improve machinability significantly. The Fraunhofer IPT has developed and successfully realized a new approach for laser-assisted milling with spindle and tool integrated, co-rotating optics. The novel optical system inside the tool consists of one deflection prism to position the laser spot in front of the cutting insert and one focusing lens. Using a fiber laser with high beam quality the laser spot diameter can be precisely adjusted to the chip size. A high dynamic adaption of the laser power signal according to the engagement condition of the cutting tool was realized in order not to irradiate already machined work piece material. During the tool engagement the laser power is controlled in proportion to the current material removal rate, which has to be calculated continuously. The needed geometric values are generated by a CAD/CAM program and converted into a laser power signal by a real-time controller. The developed milling tool with integrated optics and the algorithm for laser power control enable a multi-axis laser-assisted machining of complex parts.

  7. Fundamentals of laser-assisted micro- and nanotechnologies

    CERN Document Server

    Konov, Vitaly

    2014-01-01

    This book covers the state of the art of laser micro- and nanotechnology. The physical fundamentals of different processes and the application are presented. The book deals with different materials like phase change and memory alloys, thin films, polymers etc. New phenomena and mechanisms of laser-matter interaction in nano-domains are explained. This book is helpful for students, postgraduates, engineers and researches working not only in the field of laser microtechnology but also in high-tech industry, like photonics, microelectronics, information technology.

  8. Excimer laser assisted chemical machining of SiC ceramic

    Science.gov (United States)

    Hibi, Yuko; Enomoto, Yuji; Kikuchi, Kaoru; Shikata, Nobuo; Ogiso, Hisato

    1995-02-01

    A highly effective method of machining ceramic has been newly developed using a krypton fluoride (KrF) excimer laser with a 248 nm wavelength. The laser was irradiated on SiC in water to form a soft hydrous oxide layer by photochemical reaction. The softened layer was then cut with a diamond tool to form a mirror surface finish. The optimum conditions were found for both high machining rate and better surface integrity of SiC.

  9. Power Laser Ablation Symposia

    CERN Document Server

    Phipps, Claude

    2007-01-01

    Laser ablation describes the interaction of intense optical fields with matter, in which atoms are selectively driven off by thermal or nonthermal mechanisms. The field of laser ablation physics is advancing so rapidly that its principal results are seen only in specialized journals and conferences. This is the first book that combines the most recent results in this rapidly advancing field with authoritative treatment of laser ablation and its applications, including the physics of high-power laser-matter interaction. Many practical applications exist, ranging from inertial confinement fusion to propulsion of aerostats for pollution monitoring to laser ignition of hypersonic engines to laser cleaning nanoscale contaminants in high-volume computer hard drive manufacture to direct observation of the electronic or dissociative states in atoms and molecules, to studying the properties of materials during 200kbar shocks developed in 200fs. Selecting topics which are representative of such a broad field is difficu...

  10. Microstructural and mechanical evaluation of laser-assisted cold sprayed bio-ceramic coatings: potential use for biomedical applications

    CSIR Research Space (South Africa)

    Tlotleng, Monnamme

    2014-02-01

    Full Text Available Journal of Thermal Spray Technology Microstructural and Mechanical Evaluation of Laser-Assisted Cold Sprayed Bio- ceramic Coatings: Potential Use for Biomedical Applications  Monnamme Tlotleng  Esther Akinlabi  Mukul Shukla  Sisa Pityana...

  11. Quality of vision after femtosecond laser-assisted descemet stripping endothelial keratoplasty and penetrating keratoplasty: a randomized, multicenter clinical trial

    NARCIS (Netherlands)

    Cheng, Y.Y.; Berg, T.J. van den; Schouten, J.S.A.G.; Pels, E.; Wijdh, R.J.; Cleynenbreugel, H. van; Eggink, C.A.; Rijneveld, W.J.; Nuijts, R.M.

    2011-01-01

    PURPOSE: To compare the quality of vision (straylight and contrast sensitivity) after femtosecond laser-assisted Descemet stripping endothelial keratoplasty (FS DSEK) and penetrating keratoplasty (PK). DESIGN: Prospective, randomized clinical trial. METHODS: setting: Multicenter (5 ophthalmic

  12. Quality of Vision After Femtosecond Laser-Assisted Descemet Stripping Endothelial Keratoplasty and Penetrating Keratoplasty : A Randomized, Multicenter Clinical Trial

    NARCIS (Netherlands)

    Cheng, Yanny Y. Y.; van den Berg, Tom J. T. P.; Schouten, Jan S.; Pels, Elisabeth; Wijdh, Robert-Jan; van Cleynenbreugel, Hugo; Eggink, Catharina A.; Rijneveld, Wilhelmina J.; Nuijts, Rudy M. M. A.

    2011-01-01

    PURPOSE: To compare the quality of vision (straylight and contrast sensitivity) after femtosecond laser-assisted Descemet stripping endothelial keratoplasty (FS DSEK) and penetrating keratoplasty (PK). DESIGN: Prospective, randomized clinical trial. METHODS: SETTING: Multicenter (5 ophthalmic

  13. Laser-Assisted Sheet Metal Working of High Strength Steels in Serial Production

    OpenAIRE

    Brecher, Christian; Emonts, Michael; Eckert, Markus

    2011-01-01

    Within the sheet metal working industry the demand for thinner sheet materials with very high strength is growing due to the increasing need to save energy and a responsible use of natural resources. The high strength and the low ductility restricts using state of art technology to sheer, bend, emboss or deep draw parts with the needed complexity and quality. The Fraunhofer IPT developed a combination of laser-assisted preheating and conventional punching to a new hybrid technology which allo...

  14. Opportunities for laser-assisted drug delivery in the treatment of cutaneous disorders

    DEFF Research Database (Denmark)

    Wenande, Emily; Erlendsson, Andrés Már; Haedersdal, Merete

    2017-01-01

    lesions, scars, cutaneous infections, and vitiligo as well as for topical anesthetic and aesthetic procedures. Substantiated by randomized controlled clinical trials, strong evidence is available for LADD's usefulness for photodynamic therapy (PDT), for which improved efficacy using laser......-assisted photosensitizer treatment is established for actinic keratosis compared with conventional PDT. Over time, the modality has undergone increasing refinement and offers the potential advantages of reduced treatment durations, shortened incubation times, and the replacement of cumbersome, patient-dependent treatment...

  15. ZnO micro/nanocrystals grown by Laser Assisted Flow Deposition

    OpenAIRE

    Rodrigues,J.; Fernandes, A. J. S.; Mata, D.; Holz, T.; Carvalho, R. G.; Allah, R. Fath; Ben, T; Gonzalez, D; Silva, R F; da Cunha, A.F.; Correia, M. R.; Alves,L.C.; Lorenz, K; Neves, A.J.; Costa, F. M.

    2014-01-01

    Laser assisted flow deposition (LAFD) is a very high yield method based on a vapor-solid mechanism, allowing the production of ZnO crystals in a very short time. The LAFD was used in the growth of different morphologies (nanoparticles, tetrapods and microrods) of ZnO micro/nanocrystals and their microstructural characterization confirms the excellent crystallinity of the wurtzite structure. The optical properties of the as-grown ZnO crystals investigated by low temperature photoluminescence (...

  16. Visual outcome and histological findings following femtosecond laser-assisted versus microkeratome-assisted DSAEK.

    Science.gov (United States)

    Heinzelmann, S; Maier, P; Böhringer, D; Auw-Hädrich, C; Reinhard, T

    2013-08-01

    The aim of this study was to compare the visual outcome of femtosecond laser-assisted Descemet stripping automated endothelial keratoplasty (DSAEK) to microkeratome-assisted DSAEK as well as to contrast precut versus surgeon-cut grafts. Histologic characterization of failed DSAEK grafts was performed in order to correlate ultrastructural changes with graft failures. In this case control study, 47 cases of DSAEK were investigated in terms of visual acuity, keratometric astigmatism, spherical equivalent, endothelial cell count, and postoperative complications. We formed three groups: the femtosecondlaser-assisted DSAEK with precut grafts, the microkeratome-assisted DSAEK with precut and with surgeon-cut grafts. Mean follow-up was 6 months. In the case of graft failure, penetrating keratoplasty was performed, and the excised corneal buttons were investigated by light and electron microscopy. Microkeratome-assisted DSAEK lead to better visual outcome than femtosecond laser-assisted DSAEK. Keratometric astigmatism, spherical equivalent and endothelial cell count did not differ significantly between both methods. Precut and surgeon-cut grafts in microkeratome-assisted DSAEK did not show any significant difference regarding all upraised parameters. No definite histological correlate for graft failure following femtosecond laser-assisted DSAEK was found. Femtosecond laser-assisted DSAEK is not the method of choice, and needs further technical improvement. However, failed femtosecondlaser-assisted DSAEK grafts did not show significant histological changes related to the technique to explain reduced visual acuity. In microkeratome-assisted DSAEK, the preparation time point of the graft does not seem to influence the visual and optical outcome.

  17. Histologic, ultrastructural, and immunofluorescent evaluation of human laser-assisted in situ keratomileusis corneal wounds.

    Science.gov (United States)

    Dawson, Daniel G; Kramer, Theresa R; Grossniklaus, Hans E; Waring, George O; Edelhauser, Henry F

    2005-06-01

    To evaluate human corneas after laser-assisted in situ keratomileusis at different postoperative intervals. Thirty-eight postmortem corneas from 20 patients with postoperative intervals from 2 months to 6.5 years after laser-assisted in situ keratomileusis surgery were collected from eye banks. The corneas were trisected and processed for conventional histologic analysis, transmission electron microscopy, and immunofluorescence. Light microscopy and transmission electron microscopy showed focal undulations in Bowman layer, focal epithelial hypertrophic modifications, and a variably thick (range, 0.4-16.4-mum) lamellar stromal interface scar in all specimens. The flap wound margin, which was adjacent to the epithelium, healed by producing an approximately 8-mum-thick hypercellular fibrotic stromal scar, whereas the central and paracentral wound regions healed differently because a thinner (approximately 5-mum) hypocellular primitive stromal scar was present in all the corneas examined. Immunofluorescence identified increased type 3 collagen and myofibroblasts in the hypercellular fibrotic scar regions and decreased or absent levels of all corneal stromal components other than type 1 collagen in the hypocellular primitive scar regions. After laser-assisted in situ keratomileusis surgery, the keratocyte-mediated production of a variably thick lamellar corneal stromal scar occurs, resulting in 2 regional types of scarring. The hypercellular fibrotic scar at the wound margin is usually visible clinically and functions to hold the flap in place, while the more central hypocellular primitive scar is not visible clinically and allows easy lifting of the flap postoperatively.

  18. Translational medicine in the field of ablative fractional laser (AFXL)-assisted drug delivery

    DEFF Research Database (Denmark)

    Haedersdal, Merete; Erlendsson, Andrés M; Paasch, Uwe

    2016-01-01

    Ablative fractional lasers enhance uptake of topical therapeutics and the concept of fractional laser-assisted drug delivery has now been taken into clinical practice. Objectives We systematically reviewed preclinical data and clinical evidence for fractional lasers to enhance drug uptake and imp...

  19. Circular Dichroism in Laser-Assisted Ion-Atom Collisions

    Science.gov (United States)

    Feuerstein, Bernold; Thumm, Uwe

    2003-05-01

    We investigate theoretically the effects of a strong laser field on the dynamics of ion-atom collisions. The time-dependent Schrödinger equation is solved on a numerical grid for a reduced dimensionality model of the scattering system. The single active electron system is confined to the two dimensions of the scattering plane, which also includes the laser electric field vector. This allows the study of the influence of the laser intensity and polarization (linear, circular, elliptic) on the collision dynamics (capture and ionization probabilities) The projectile follows a classical trajectory with impact parameter b. We found a strong circular dirchroism in the capture probability P(b) for slow proton-hydrogen collisions. First results will be presented and discussed. Supported in part by NSF (grant PHY-0071035) and Division of Chemical Sciences, Office of Basic Energy Scienes, Office of Energy Research, US DOE.

  20. Laser assisted high entropy alloy coating on aluminum: Microstructural evolution

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B., E-mail: Narendra.Dahotre@unt.edu [Department of Materials Science and Engineering, University of North Texas, 1150 Union Circle, 305310 Denton, Texas 76203-5017 (United States)

    2014-09-14

    High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

  1. IR-laser assisted additive freeform optics manufacturing.

    Science.gov (United States)

    Hong, Zhihan; Liang, Rongguang

    2017-08-02

    Computer-controlled additive manufacturing (AM) processes, also known as three-dimensional (3D) printing, create 3D objects by the successive adding of a material or materials. While there have been tremendous developments in AM, the 3D printing of optics is lagging due to the limits in materials and tight requirements for optical applicaitons. We propose a new precision additive freeform optics manufacturing (AFOM) method using an pulsed infrared (IR) laser. Compared to ultraviolet (UV) curable materials, thermally curable optical silicones have a number of advantages, such as strong UV stability, non-yellowing, and high transmission, making it particularly suitable for optical applications. Pulsed IR laser radiation offers a distinct advantage in processing optical silicones, as the high peak intensity achieved in the focal region allows for curing the material quickly, while the brief duration of the laser-material interaction creates a negligible heat-affected zone.

  2. UV laser-assisted wire stripping and micro-machining

    Science.gov (United States)

    Martyniuk, Jerry

    1994-02-01

    Results are reported for the use of a 266 nm frequency quadrupled Nd:YAG ultraviolet laser in the areas of wire stripping of small coaxial type transmission lines and for micro-machining of various materials including copper, glass, polyimide and DuPont TEFLONTM. This new laser is typically run with a 2 KHz repetition rate, 40 ns FWHM pulse and a fluence of about 50 joules/cm2 which makes it possible to micro-machine metals, polymers, glasses and ceramics. The high fluence of this laser allows shielding structures such as Al-MylarTM, Al-KaptonTM or the plated copper used in small coaxial cables to be precisely cut. Cut rates are reported for the above materials as well as results and photos of wire stripping and micro- machining.

  3. Spectral caustics in laser assisted Breit–Wheeler process

    Directory of Open Access Journals (Sweden)

    T. Nousch

    2016-04-01

    Full Text Available Electron–positron pair production by the Breit–Wheeler process embedded in a strong laser pulse is analyzed. The transverse momentum spectrum displays prominent peaks which are interpreted as caustics, the positions of which are accessible by the stationary phases. Examples are given for the superposition of an XFEL beam with an optical high-intensity laser beam. Such a configuration is available, e.g., at LCLS at present and at European XFEL in near future. It requires a counter propagating probe photon beam with high energy which can be generated by synchronized inverse Compton backscattering.

  4. Topography-guided customized laser-assisted subepithelial keratectomy for the treatment of postkeratoplasty astigmatism.

    Science.gov (United States)

    Rajan, Madhavan S; O'Brart, David P S; Patel, Parul; Falcon, Mike G; Marshall, John

    2006-06-01

    To assess topography-assisted corneal wavefront excimer laser surface ablation for the correction of ametropia and irregular astigmatism after keratoplasty. Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom. In this pilot study, 15 patients (16 eyes) who were intolerant of spectacle and contact lens correction due to astigmatic anisometropia after keratoplasty (15 penetrating and 1 lamellar) had topography-assisted customized excimer laser treatments. Corneal topographic data using a Keratron Scout, Placido disk system allowed for preoperative analysis of wavefront anomalies of the anterior corneal surface from which a customized excimer laser correction of both lower-order aberrations (LOAs) and higher-order aberrations (HOAs) was prepared (ORK software) for treatment with a Schwind Esiris flying-spot laser. All eyes had laser-assisted subepithelial keratectomy (LASEK) using 15% alcohol with a 20-second to 30-second application. Four eyes received an application of mitomycin-C (MMC) 0.2 mg/mL for 1 minute after stromal ablation. The mean preoperative spherical equivalent (SE) was -3.50 diopters (D) +/- 3.97 (SD) (range +1.625 to -9.25 D). The preoperative cylindrical error was -7.2 D (range -2.75 to -13.5 D). The programmed laser correction was -3.14 D (range +1.62 to -9 D) with a maximum attempted cylindrical correction of -7 D. Adherent LASEK epithelial flaps along suture lines and the graft-host junction were noted in 9 eyes (56%), although it was possible to obtain and replace a partial flap. A follow-up of 18 months was achieved in all eyes. At the final follow-up visit, the mean postoperative SE was -1.08 +/- 1.85 D (range +3 to -4.78 D) (P<.01, F<.01). Ten eyes (62.5%) were within +/-1 D of the intended correction. The mean postoperative cylindrical error was -2.72 D (range -0.5 to -6.5 D) (P<.001), with vector analysis demonstrating a mean 6.23 D correction. Analysis of HOAs using a 6.0 mm pupil size demonstrated a significant

  5. An experimental investigation of pulsed laser-assisted machining of AISI 52100 steel

    Science.gov (United States)

    Panjehpour, Afshin; Soleymani Yazdi, Mohammad R.; Shoja-Razavi, Reza

    2014-11-01

    Grinding and hard turning are widely used for machining of hardened bearing steel parts. Laser-assisted machining (LAM) has emerged as an efficient alternative to grinding and hard turning for hardened steel parts. In most cases, continuous-wave lasers were used as a heat source to cause localized heating prior to material removal by a cutting tool. In this study, an experimental investigation of pulsed laser-assisted machining of AISI 52100 bearing steel was conducted. The effects of process parameters (i.e., laser mean power, pulse frequency, pulse energy, cutting speed and feed rate) on state variables (i.e., material removal temperature, specific cutting energy, surface roughness, microstructure, tool wear and chip formation) were investigated. At laser mean power of 425 W with frequency of 120 Hz and cutting speed of 70 m/min, the benefit of LAM was shown by 25% decrease in specific cutting energy and 18% improvement in surface roughness, as compared to those of the conventional machining. It was shown that at constant laser power, the increase of laser pulse energy causes the rapid increase in tool wear rate. Pulsed laser allowed efficient control of surface temperature and heat penetration in material removal region. Examination of the machined subsurface microstructure and microhardness profiles showed no change under LAM and conventional machining. Continuous chips with more uniform plastic deformation were produced in LAM.

  6. Laser assisted fabrication of random rough surfaces for optoelectronics

    Energy Technology Data Exchange (ETDEWEB)

    Brissonneau, V., E-mail: vincent.brissonneau@im2np.fr [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Escoubas, L. [Institut Materiaux Microelectronique Nanosciences de Provence, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France); Flory, F. [Institut Materiaux Microelectronique Nanosciences de Provence, Ecole Centrale Marseille, Marseille (France); Berginc, G. [Thales Optronique SA, Avenue Gay-Lussac, 78995 Elancourt (France); Maire, G.; Giovannini, H. [Institut Fresnel, Aix Marseille Universite, Avenue Escadrille Normandie Niemen, 13397 Marseille (France)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Random rough surfaces are photofabricated using an argon ion laser. Black-Right-Pointing-Pointer Speckle and surface correlation function are linked. Black-Right-Pointing-Pointer Exposure beam is modified allowing tuning the correlation. Black-Right-Pointing-Pointer Theoretical examples are presented. Black-Right-Pointing-Pointer Experimental results are compared with theoretical expectation. - Abstract: Optical surface structuring shows great interest for antireflective or scattering properties. Generally, fabricated surface structures are periodical but random surfaces that offer new degrees of freedom and possibilities by the control of their statistical properties. We propose an experimental method to create random rough surfaces on silicon by laser processing followed by etching. A photoresist is spin coated onto a silicon substrate and then exposed to the scattering of a modified laser beam. The beam modification is performed by using a micromirror matrix allowing laser beam shaping. An example of tuning is presented. An image composed of two white circles with a black background is displayed and the theoretical shape of the correlation is calculated. Experimental surfaces are elaborated and the correlation function calculated from height mapping. We finally compared the experimental and theoretical correlation functions.

  7. Laser-assisted oral surgery in general practice

    Science.gov (United States)

    McCauley, Mark C.

    1995-04-01

    This presentation will demonstrate and discuss any surgical applications of the Argon dental laser. This presentation will also increase the awareness and basic understanding of the physical principals of the Argon laser. The wavelength of the Argon laser is specifically absorbed by red pigments such a hemoglobin which is abundant in oral soft tissue. The result is a sharp clean incision with minimal thermal damage to adjacent healthy tissue. Preprosthetic procedures such as full arch vestibuloplasty, labial and lingual frenectomy, and epulis fissuratum removal will be demonstrated. Other soft tissue management procedures such as minor periodontal pocket elimination surgery (gingivectomy), removal of hyperplastic granulation tissue from around poorly maintained implants, and the removal of granulation and/or cystic tissue from the apex of teeth undergoing endodontic (apicoec-tomy) surgery will also be demonstrated and discussed. Provided basic oral surgery protocol is followed, surgical procedures utilizing the Argon laser can be accomplished with minimal bleeding, minimal trauma and with minimal post-operative discomfort.

  8. Laser-assisted hair transplantation: histologic comparison between holmium:YAG and CO2 lasers

    Science.gov (United States)

    Chu, Eugene A.; Rabinov, C. Rose; Wong, Brian J.; Krugman, Mark E.

    1999-06-01

    The histological effects of flash-scanned CO2 (λ=10.6μm) and pulsed Holmium:YAG (Ho:YAG, λ=2.12μm) lasers were evaluated in human scalp following the creation of hair transplant recipient channels. Ho:YAG laser irradiation created larger zones of thermal injury adjacent to the laser channels than irradiation with the CO2 laser device. When the two lasers created recipient sites of nearly equal depth, the Holmium:YAG laser caused a larger region of lateral thermal damage (589.30μm) than the CO2 laser (118.07μm). In addition, Holmium:YAG irradiated specimens exhibited fractures or discontinuities beyond the region of clear thermal injury. This shearing effect is consistent with the photoacoustic mechanism of ablation associated with pulsed mid-IR laser irradiation. In contrast, channels created with the CO2 exhibited minimal epithelial disruption and significantly less lateral thermal damage. While the Holmium:YAG laser is a useful tool for ablation soft tissue with minimal char in select applications (sinus surgery, arthroscopic surgery), this study suggests that the use of the CO2 laser for the creation of transplantation recipient channels result in significantly less lateral thermal injury for the laser parameters employed.

  9. Laser-assisted guiding of electric discharges around objects

    Science.gov (United States)

    Clerici, Matteo; Hu, Yi; Lassonde, Philippe; Milián, Carles; Couairon, Arnaud; Christodoulides, Demetrios N.; Chen, Zhigang; Razzari, Luca; Vidal, François; Légaré, François; Faccio, Daniele; Morandotti, Roberto

    2015-01-01

    Electric breakdown in air occurs for electric fields exceeding 34 kV/cm and results in a large current surge that propagates along unpredictable trajectories. Guiding such currents across specific paths in a controllable manner could allow protection against lightning strikes and high-voltage capacitor discharges. Such capabilities can be used for delivering charge to specific targets, for electronic jamming, or for applications associated with electric welding and machining. We show that judiciously shaped laser radiation can be effectively used to manipulate the discharge along a complex path and to produce electric discharges that unfold along a predefined trajectory. Remarkably, such laser-induced arcing can even circumvent an object that completely occludes the line of sight. PMID:26601188

  10. Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

    Science.gov (United States)

    Venkatesan, K.; Ramanujam, R.; Kuppan, P.

    2016-04-01

    This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth.

  11. Femtosecond laser refractive surgery: small-incision lenticule extraction vs. femtosecond laser-assisted LASIK.

    Science.gov (United States)

    Lee, Jimmy K; Chuck, Roy S; Park, Choul Yong

    2015-07-01

    Small-incision lenticule extraction (SMILE) is a novel technique devised to correct refractive errors. SMILE circumvents excimer laser photoablation of cornea, as the stromal lenticule cut by femtosecond laser is removed manually. Smaller incisions and preservation of anterior corneal biomechanical strength have been suggested as some of the advantages of SMILE over femtosecond laser-assisted LASIK (FS-LASIK). In this review, we compared previous published results of SMILE and FS-LASIK. The advantage, efficacy and safety of SMILE are compared with FS-LASIK. SMILE achieved similar efficacy, predictability and safety as FS-LASIK. Greater preservations of corneal biomechanical strength and corneal nerves were observed in SMILE when compared with LASIK or PRK. Additionally, the incidence of postoperative dry eye syndrome was found to be less problematic in SMILE than in FS-LASIK. SMILE is a promising new surgery for refractive error correction. Prospective and retrospective studies of SMILE have shown that results of SMILE are similar to FS-LASIK. With advances in femtosecond laser technology, SMILE may gain greater acceptance in the future.

  12. Laser ablation of concrete.

    Energy Technology Data Exchange (ETDEWEB)

    Savina, M.

    1998-10-05

    Laser ablation is effective both as an analytical tool and as a means of removing surface coatings. The elemental composition of surfaces can be determined by either mass spectrometry or atomic emission spectroscopy of the atomized effluent. Paint can be removed from aircraft without damage to the underlying aluminum substrate, and environmentally damaged buildings and sculptures can be restored by ablating away deposited grime. A recent application of laser ablation is the removal of radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on concrete samples using a high power pulsed Nd:YAG laser with fiber optic beam delivery. The laser-surface interaction was studied on various model systems consisting of Type I Portland cement with varying amounts of either fine silica or sand in an effort to understand the effect of substrate composition on ablation rates and mechanisms. A sample of non-contaminated concrete from a nuclear power plant was also studied. In addition, cement and concrete samples were doped with non-radioactive isotopes of elements representative of cooling waterspills, such as cesium and strontium, and analyzed by laser-resorption mass spectrometry to determine the contamination pathways. These samples were also ablated at high power to determine the efficiency with which surface contaminants are removed and captured. The results show that the neat cement matrix melts and vaporizes when little or no sand or aggregate is present. Surface flows of liquid material are readily apparent on the ablated surface and the captured aerosol takes the form of glassy beads up to a few tens of microns in diameter. The presence of sand and aggregate particles causes the material to disaggregate on ablation, with intact particles on the millimeter size scale leaving the surface. Laser resorption mass spectrometric analysis showed that cesium and potassium have similar chemical environments in the

  13. Laser-assisted metal deposition from liquid-phase precursors on polymers

    Science.gov (United States)

    Kordás, K.; Békési, J.; Vajtai, R.; Nánai, L.; Leppävuori, S.; Uusimäki, A.; Bali, K.; George, Thomas F.; Galbács, G.; Ignácz, F.; Moilanen, P.

    2001-03-01

    In this work, a short review is presented for results utilizing the technique of laser-assisted metallization of dielectrics. Experimental efforts and results related to the metal (palladium (Pd), copper (Cu) and silver (Ag)) deposition on polymeric materials (polyimide (PI), mylar) are reported. These polymers and metals are chosen due to their growing importance in the rapidly-developing microelectronics packaging industry. The method of laser-induced chemical liquid-phase deposition (LCLD) offers many advantages compared to other techniques such as laser-induced forward transfer (LIFT), pulsed-laser deposition (PLD) and laser-assisted chemical vapor-phase deposition (LCVD). The LCLD is time and cost effective because vacuum tools and special pre-treatments are not required. The consumed chemicals used in precursors are non-harmful and easy to handle due to the liquid phase. For the optimal physical and chemical properties of deposits, the laser and solution parameters are varied. XeCl and KrF excimer and Ar + lasers are employed for executing the palladium, Ag and/or Cu formation on the polymer substrates. Chemical and physical analyses of the formed metal patterns are performed by EDX, XRD, FESEM, SEM, resistance and adhesion measurements.

  14. Laser-assisted growth of carbon nanotubes on laser-patterned substrates and inside sealed micro-channels

    NARCIS (Netherlands)

    Burgt, Y. van de; Bellouard, Y.

    2014-01-01

    Carbon nanotube assemblies can be used for specific applications such as sensors and filters. We present a method and proof-of-concept to directly grow vertically-aligned carbon nanotube structures within sealed enclosures by means of a feedback-controlled laser-assisted chemical vapor deposition

  15. Femtosecond laser assisted antibacterial activity of ZnO nanoparticles

    Science.gov (United States)

    Luna Palacios, Yryx Yanet; Alvarez, Crysthal; Cuando-Espitia, Natanael; Halaney, David L.; Camacho-Lopez, Santiago; Aguilar, Guillermo

    2017-07-01

    Bacterial infection of cranial implants remains a major cause of implant failure, and often requires surgical intervention to remove and replace the fouled implant. Novel transparent implants may allow for mitigation of infection using optical therapies, without the need for invasive surgeries. In this study, we investigate a combined treatment with ZnO nanoparticles and femtosecond laser pulses to inhibit the growth of Escherichia coli (E. Coli) in vitro. The combined effect has shown a substantial reduction in the number of CFU/mL after incubation compared with no treatment.

  16. Femtosecond laser-assisted cataract surgery and implantable miniature telescope

    Directory of Open Access Journals (Sweden)

    Randal Pham

    2017-09-01

    Conclusions and importance: To our knowledge and confirmed by the manufacturer of the implantable miniature telescope this is the first case ever reported of a patient who has undergone femtosecond laser cataract surgery with corneal astigmatism correction and implantation of the implantable miniature telescope. This is also the first case report of the preoperative use of microperimetry and visual electrophysiology to evaluate a patient's postoperative potential visual acuity. The success of the procedure illustrated the importance of meticulous preoperative planning, the combined use of state-of-the-art technologies and the seamless teamwork in order to achieve the best clinical outcome for patients who undergo implantation of the implantable miniature telescope.

  17. Femtosecond laser-assisted decagonal deep anterior lamellar keratoplasty.

    Science.gov (United States)

    Espandar, Ladan; Mandell, Jonathan B; Niknam, Sasan

    2016-04-01

    To assess the use of a new polygonal trephination pattern for deep anterior lamellar keratoplasty (DALK) assisted by femtosecond laser. Prospective, nonrandomized clinical study. Twenty-four eyes underwent decagonal DALK. All except 1 had advanced keratoconus. A laser was used to create decagonal cuts on both donor and recipient corneas. All patients were assessed for uncorrected visual acuity, best spectacle-corrected visual acuity (BCVA), and keratometry by Pentacam pre- and postoperatively. All eyes were treated successfully without intraoperative complications. All patients were followed for 18 months. Mean ± SD of postoperative BCVA was 0.26 ± 0.16 (logarithm of minimal angle of resolution), and there was a significant improvement in BCVA after 6 months. At 18 months, mean ± SD postoperative average K was 44.48 ± 0.87 D, which was significantly lower than preoperative average K (58.42 ± 12.1). Postoperative astigmatism at 18 months (mean ± SD: 1.82 ± 0.67) was significantly lower than that at 6 months (mean ± SD: 3.27 ± 0.81) (p = 0.001). Use of the decagonal trephination profile was effective to perform DALK. This study showed promising visual and refractive results. Longer follow-up, larger pool of patients, and comparative studies are necessary to determine advantages and optimal surgical settings of this technique. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  18. Laser-assisted manufacturing of super-insulation materials

    Science.gov (United States)

    Wang, Zhen; Zhang, Tao; Park, Byung Kyu; Lee, Woo Il; Hwang, David

    2017-02-01

    Being lightweight materials with good mechanical and thermal properties, hollow glass micro-particles (HGMPs) have been widely studied for multiple applications. In this study, it is shown that by using reduced binder fraction diluted in solvent, enables minimal contacts among the HGMPs assisted by a natural capillary trend, as confirmed by optical and electron microscope imaging. Such material architecture fabricated in a composite level proves to have enhanced thermal insulation performance through quantitative thermal conductivity measurement. Mechanical strength has also been evaluated in terms of particle-binder bonding by tensile test via in-situ microscope inspection. Effect of laser treatment was examined for further improvement of thermal and mechanical properties by selective binder removal and efficient redistribution of remaining binder components. The fabricated composite materials have potential applications to building insulation materials for their scalable manufacturing nature, improved thermal insulation performance and reasonable mechanical strength. Further studies are needed to understand mechanical and thermal properties of the resulting composites, and key fabrication mechanisms involved with laser treatment of complex multi-component and multi-phase systems.

  19. Laser-assisted immobilization of colloid silver nanoparticles on polyethyleneterephthalate

    Science.gov (United States)

    Siegel, Jakub; Lyutakov, Oleksiy; Polívková, Markéta; Staszek, Marek; Hubáček, Tomáš; Švorčík, Václav

    2017-10-01

    Immobilization of nanoobjects on the surface of underlying material belongs to current issues of material science. Such altered materials exhibits completely exceptional properties exploitable in a broad spectrum of industrially important applications ranging from catalysts up to health-care industry. Here we present unique approach for immobilization of electrochemically synthesized silver nanoparticles on polyethyleneterephthalate (PET) foil whose essence lies in physical incorporation of particles into thin polymer surface layer induced by polarized excimer laser light. Changes in chemical composition and surface structure of polymer after particle immobilization were recorded by wide range of analytical techniques such as ARXPS, EDX, RBS, AAS, Raman, ICP-MS, DLS, UV-vis, SEM, TEM, and AFM. Thorough analysis of both nanoparticles entering the immobilization step as well as modified PET surface allowed revealing the mechanism of immobilization process itself. Silver nanoparticles were physically embedded into a thin surface layer of polymer reaching several nanometers beneath the surface rather than chemically bonded to PET macromolecules. Laser-implanted nanoparticles open up new possibilities especially in the development of the next generation cell-conform antimicrobial coatings of polymeric materials, namely due to the considerable immobilization strength which is strong enough to prevent particle release into the surrounding environment.

  20. Laser Assisted Additively Manufactured Transition Metal Coating on Aluminum

    Science.gov (United States)

    Vora, Hitesh D.; Rajamure, Ravi Shanker; Roy, Anurag; Srinivasan, S. G.; Sundararajan, G.; Banerjee, Rajarshi; Dahotre, Narendra B.

    2016-07-01

    Various physical and chemical properties of surface and subsurface regions of Al can be improved by the formation of transition metal intermetallic phases (Al x TM y ) via coating of the transition metal (TM). The lower equilibrium solid solubility of TM in Al (engineering via a laser-aided additive manufacturing approach can effectively synthesize TM intermetallic coatings on the surface of Al. The focus of the present work included the development of process control to achieve thermodynamic and kinetic conditions necessary for desirable physical, microstructural and compositional attributes. A multiphysics finite element model was developed to predict the temperature profile, cooling rate, melt depth, dilution of W in Al matrix and corresponding micro-hardness in the coating, and the interface between the coating and the base material and the base material.

  1. Experimental and theoretical evaluation of the laser-assisted machining of silicon nitride

    Science.gov (United States)

    Rozzi, Jay Christopher

    This study focused on the experimental and theoretical evaluation of the laser assisted machining (LAM) of silicon nitride ceramics. A laser assisted machining facility was constructed whose main components consist of a COsb2 laser and a CNC lathe. Surface temperature histories were first measured and compared to a transient, three-dimensional numerical simulation for a rotating silicon nitride workpiece heated by a translating laser for ranges of the workpiece rotational and laser-translation speeds, as well as the laser beam diameter and power. Excellent agreement was obtained between the experimental and predicted temperature histories. Laser assisted machining experiments on silicon nitride ceramic workpieces were completed for a wide range of operating conditions. Data for cutting forces and surface temperature histories illustrated that the lower bound for the avoidance of cutting tool and/or workpiece fracture for LAM is defined by the YSiAlON glass transition temperature (920-970sp°C). As temperatures near the cutting tool increase to values above the glass transition temperature range, the glassy phase softened, facilitating plastic deformation and, correspondingly, the production of semi-continuous or continuous chips. The silicon nitride machined workpiece surface roughness (Rsb{a}=0.39\\ mum) for LAM at the nominal operating condition was nearly equivalent to a value associated with the grinding of silicon nitride using a diamond wheel (Rsb{a}=0.2\\ mum). By examining the machined surfaces and chips, it was shown that LAM does not produce detectable sub-surface cracking or significant silicon nitride microstructure alteration, respectively. A transient, three-dimensional numerical heat transfer model of laser assisted machining was constructed, which includes a preheat phase and material removal, with the associated changes in the workplace geometry. Excellent agreement was obtained between the measured and predicted temperature histories. The strong

  2. Heat transfer model of semi-transparent ceramics undergoing laser-assisted machining

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferkorn, F.E. [University of Wisconsin-Madison (United States). Department of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, IN (United States). College of Engineering; Yung C. Shin [Purdue University, West Lafayette, IN (United States). School of Mechanical Engineering

    2005-05-01

    A three-dimensional, unsteady heat transfer model has been developed for predicting the temperature field in partially-stabilized zirconia (PSZ) undergoing laser-assisted machining. The semi-transparent PSZ is treated as optically thick within a spectral band from approximately 0.5 to 8 {mu}m. After comparing the diffusion approximation and the discrete ordinates method for predicting internal radiative transfer, suitability of the diffusion approximation is established from a comparison of model predictions with surface temperature measurements. The temperature predictions are in good agreement with measured values during machining. Parametric calculations reveal that laser power and feedrate have the greatest effect on machining temperatures. (author)

  3. Endoscopic laser-assisted dacryocistorhinostomy DCR with the placement of a customised silicone and Teflon bicanalicular stent Endoscopic laser-assisted dacryocystorhinostomy (DCR).

    Science.gov (United States)

    D'Ecclesia, A; Cocchi, R F; Giordano, F; Mazzilli, E; Longo, C; Laborante, A

    We present our experience in endoscopic laser assisted dacryocystorhinostomy (DCR) analyzing the results obtained with a new technique that involves placing bicanalicolar silicone stent more Teflon tube, in combination with paraseptal silastic sheet. In our study 49 of 57 patients (85%) at a mean follow up of at least 12 months have not reported epiphora or more episodes of acute dacryocystitis. 49 out of the 57 patients (85%) in our group reported no additional epiphora or episodes of acute dacryocystitis. Endoscopic DCR is currently the gold standard for sac and post-sac stenosis given the minimal invasiveness of the procedure and the long-term results that appear comparable to those obtained with extrinsic DCR. The principal problem is cicatricial stenosis that can occlude the stoma over time.

  4. Meniscus and discus lesions of triangular fibrocartilage complex (TFCC): treatment by laser-assisted wrist arthroscopy.

    Science.gov (United States)

    Infanger, Manfred; Grimm, Daniela

    2009-04-01

    Meniscus and disc lesions in the triangular fibrocartilage complex (TFCC) are generally caused by falling accidents with pronated, hyperextended wrists, or by distraction injuries that pull the ulnar side of the wrist out of place. Characteristic clinical signs are swelling and pain in the distal radioulnar joint (DRUJ) and a 'clicking' noise in the meniscus lesion. If untreated, loss of mobility and grip strength as well as progressive arthritic changes ensue. We investigated in this study the laser-assisted arthroscopic debridement of the central TFCC and meniscus to compare the advantages and disadvantages of such treatment to conventional arthroscopic debridement. Seventy-two patients underwent laser-assisted arthroscopic debridement of traumatic TFCC tears (meniscus and disc). Patients with TFCC tears that were associated with fractures, significant bone or neurovascular pathology or DRUJ instability were excluded from the study. The mean age was 32.4 years; 28 female and 51 male patients were included in the study. The mean follow up was 25.6 months. First of all, we evaluated the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. We then applied the range of motion of the hand (ROM) as second variable during statistical analysis to identify outcome. There were no complications after surgery. No instabilities or dislocations of the DRUJ were noted. The postoperative DASH score indicated that the laser-assisted arthroscopic repair of traumatic peripheral TFCC tears resulted in a very good functional outcome. All patients with isolated meniscus homologue tears were without pain after the operation. At final follow up, the ROM was equal to or greater than that of the contralateral side. We have demonstrated that the TFCC laser debridement technique is easy and safe to perform. The outcome was excellent with less pain and good ROM. In particular, the laser technique enabled a good intra-articular haemostasis and allowed an exact tear debridement.

  5. Laser-assisted vitrification of large equine embryos.

    Science.gov (United States)

    Scherzer, J; Davis, C; Hurley, D J

    2011-12-01

    The major difficulty in providing the benefits of embryo cryopreservation for equine agriculture is the mismatch between the optimal embryo age for collection from the mare (7-8 days after ovulation was detected) and the optimal age for freezing under current methods (6.5 days after ovulation). To overcome this limitation, we tested a method to enhance penetration of cryopreservative across the capsule and trophoblast of day 7 and 8 embryos combined with rapid freezing by vitrification. Six small embryos (laser system used to create a small opening in the embryonic capsule and trophectoderm. All embryos were vitrified using a CryoLeaf freezing support. After recovery from freezing and embryo transfer, three of four small untreated embryos (300 μm in diameter, 44%) resulted in a vesicle as detected by ultrasonography approximately one week after transfer. However, only one recipient mare was still pregnant on day 23, and she delivered a live foal. Further investigation is required to determine why most of the embryos in this experiment were lost between day 13 and day 23 of gestation. © 2011 Blackwell Verlag GmbH.

  6. [The treatment of otosclerosis using laser assisted stapedotomy with mini incision in external auditory meatus].

    Science.gov (United States)

    Hao, Xinping; Chen, Shubin; Yu, Zilong; Liang, Fenghe; Li, Yongxin

    2016-03-01

    To investigate the feasibility of the treatment of otosclerosis using laser stapedotomy with mini incision in the external auditory meatus. Thirteen patients(15 ears) with otosclerosis evidence on clinic history. They were all operated using the laser assisted stapedotomy by mini incision in external auditory meatus because of the wide straight canal. Laser resection the tendo musculistapedius and anterior and postrior arch, breaking the articulatioincudostapedia, removing the stapes superstructure, making a hole of 6mm diameter in the rear of stapes footplate by laser drilling, implanting the corresponding length Piston artificial ossicle. All the surgeries were successful and the operation time was about one hour. There was only one patient manifested vertigo and nausea after the operation. But the symptoms improved three days later after the expectant treatment. All the incisions were healed in the externals. There was significant difference between the preoperative and postoperative PTA. The air conduct improved in every frequent and the bone conduct improved in 1 kHz, 2 kHz and 4 kHz. Laser assisted stapedotomy by mini incision in the external auditory meatus in patients having wide straight canal with otosclerosis can shorten the operation time, minimize the tissue damage, fasten the healing of the incision and reduce the complications postoperatively. In addition, the mini incision is beauty and easy to nurse.

  7. Laser-assisted correction of eye cornea refraction with ring-shaped laser beam

    Science.gov (United States)

    Baum, Olga; Yuzhakov, Aleksey; Omelchenko, Alexander; Bolshunov, Andrey; Siplivy, Vladimir; Sobol, Emil

    2017-07-01

    A new method for non-ablative correction of cornea shape is based on thermo-mechanical effect of laser radiation with ring-shaped laser beam. The results obtained demonstrated that the new method for correction of eye refraction yields a significant alteration in the eye refraction and the ring-shaped laser beam with various ring diameters for correction of the eye refraction allows obtaining controllable alterations of the eye refraction with axial symmetry without any pathological changes in central part of cornea.

  8. Significance of the Resonance Condition for Controlling the Seam Position in Laser-assisted TIG Welding

    Science.gov (United States)

    Emde, B.; Huse, M.; Hermsdorf, J.; Kaierle, S.; Wesling, V.; Overmeyer, L.; Kozakov, R.; Uhrlandt, D.

    As an energy-preserving variant of laser hybrid welding, laser-assisted arc welding uses laser powers of less than 1 kW. Recent studies have shown that the electrical conductivity of a TIG welding arc changes within the arc in case of a resonant interaction between laser radiation and argon atoms. This paper presents investigations on how to control the position of the arc root on the workpiece by means of the resonant interaction. Furthermore, the influence on the welding result is demonstrated. The welding tests were carried out on a cooled copper plate and steel samples with resonant and non-resonant laser radiation. Moreover, an analysis of the weld seam is presented.

  9. High efficiency laser-assisted H- charge exchange for microsecond duration beams

    Science.gov (United States)

    Cousineau, Sarah; Rakhman, Abdurahim; Kay, Martin; Aleksandrov, Alexander; Danilov, Viatcheslav; Gorlov, Timofey; Liu, Yun; Long, Cary; Menshov, Alexander; Plum, Michael; Shishlo, Andrei; Webster, Andrew; Johnson, David

    2017-12-01

    Laser-assisted stripping is a novel approach to H- charge exchange that overcomes long-standing limitations associated with the traditional, foil-based method of producing high-intensity, time-structured beams of protons. This paper reports on the first successful demonstration of the laser stripping technique for microsecond duration beams. The experiment represents a factor of 1000 increase in the stripped pulse duration compared with the previous proof-of-principle demonstration. The central theme of the experiment is the implementation of methods to reduce the required average laser power such that high efficiency stripping can be accomplished for microsecond duration beams using conventional laser technology. The experiment was performed on the Spallation Neutron Source 1 GeV H- beam using a 1 MW peak power UV laser and resulted in ˜95 % stripping efficiency.

  10. Clinical outcomes using standard phacoemulsification and femtosecond laser-assisted surgery with toric intraocular lenses

    Directory of Open Access Journals (Sweden)

    Espaillat A

    2016-03-01

    Full Text Available Arnaldo Espaillat,1 Obniel Pérez,1 Richard Potvin2 1Espaillat-Cabral Eye Institute, Santo Domingo, Dominican Republic; 2Science in Vision, Akron, NY, USA Purpose: To compare the 1-month and 1-year results of toric intraocular lens (IOL implantation with standard (manual phacoemulsification vs femtosecond laser-assisted surgery.Patients and methods: Refractive data, visual acuity data, and ocular aberration measured with a wavefront aberrometer were collected for two groups of patients from one site. The first group had standard phacoemulsification, while the second group had femtosecond laser-assisted surgery, and both groups were implanted with toric IOLs, either monofocal or multifocal. Differences in visual acuity, refractive outcomes, and higher order aberrations – total, corneal, and internal – were evaluated at 1 month and 1 year postoperatively.Results: Toric IOLs were implanted in 62 eyes using standard phacoemulsification and 53 eyes using femtosecond laser-assisted surgery. Uncorrected visual acuity and best-spectacle-corrected visual acuity at 1 month and 1 year were not statistically significantly different between the groups (P>0.05 nor was the mean cylinder or mean spherical equivalent refraction (P>0.12. Total ocular higher order aberrations were significantly different between the groups (P<0.05, but absolute differences appeared to be the same. Internal vertical coma was significantly lower in the femto group at 1 year (P=0.03. Differences in aberrations did not correlate with corrected or uncorrected visual acuity.Conclusion: Patients who underwent uncomplicated lens surgery with toric IOLs in both the groups had comparable refractive outcomes in terms of visual acuity and residual refraction at 1 year. The femto group had significantly lower internal vertical coma at 1 year. Keywords: FLACS, LenSx, cataracts, refraction, astigmatism, visual acuity, toric IOL, femtosecond laser

  11. One-year follow-up of femtosecond laser-assisted penetrating keratoplasty

    Directory of Open Access Journals (Sweden)

    Tan JCH

    2013-02-01

    Full Text Available Johnson Choon-Hwai Tan, Wee-Jin HengNational Healthcare Group Eye Institute, Tan Tock Seng Hospital, SingaporeBackground: The purpose of this report is to describe the initial outcomes of femtosecond laser-assisted penetrating keratoplasty.Methods: This retrospective surgical case series consisted of 10 eyes from 10 patients undergoing penetrating keratoplasty at a tertiary center. Femtosecond laser was used to perform a zig-square incision on the donor cornea with matched dimensions on the recipient cornea. Outcomes measured included: unaided visual acuity and best spectacle-corrected visual acuity preoperatively and at one, 3, 6, and 12 months postoperatively; manifest refractive and topographic astigmatism at 3, 6, and 12 months postoperatively; and endothelial cell density loss, calculated at the end of the one-year follow-up period.Results: At one-year follow-up, there was an improvement in unaided visual acuity from a mean preoperative logMAR of 1.67 to 0.44, and best spectacle-corrected visual acuity from a mean preoperative logMAR of 1.33 to 0.13. By postoperative month 3, mean manifest refractive and topographic astigmatism was 2.31 ± 1.41 D and 2.59 ± 1.57 D, respectively. The mean reduction in endothelial cell density was 20.7% after one year of follow-up.Conclusion: Femtosecond laser-assisted penetrating keratoplasty provided a good visual outcome and early visual rehabilitation due to precise graft-host alignment and reduced astigmatism in the early postoperative months.Keywords: penetrating keratoplasty, femtosecond laser-assisted keratoplasty

  12. Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

    Directory of Open Access Journals (Sweden)

    Yan Lu

    2014-08-01

    Full Text Available AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK for keratoconus and post-LASIKkeratectasia.METHODS:In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany. Of the 9 patients, 7 had keratoconus and 2 had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas.The outcome measures were the uncorrected visual acuity (UCVA, best-corrected visual acuity (BCVA, corneal thickness, astigmatism, endothelial density count (EDC, and corneal power.RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation. Postoperatively, there was one case of stromal rejection, one of loosened sutures, and one of wound dehiscence. A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly, and astigmatism improved slightly. There was no statistically significant decrease in EDC.CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.

  13. Analysis of plasma characteristics and conductive mechanism of laser assisted pulsed arc welding

    Science.gov (United States)

    Liu, Shuangyu; Chen, Shixian; Wang, Qinghua; Li, Yanqing; Zhang, Hong; Ding, Hongtao

    2017-05-01

    This study aims to investigate the arc plasma shape and the spectral characteristics during the laser assisted pulsed arc welding process. The arc plasma shape was synchronously observed using a high speed camera, and the emission spectrum of plasma was obtained by spectrometer. The well-known Boltzmann plot method and Stark broadening were used to calculate the electron temperature and density respectively. The conductive mechanism of arc ignition in laser assisted arc hybrid welding was investigated, and it was found that the plasma current moved to the arc anode under the action of electric field. Thus, a significant parabolic channel was formed between the keyhole and the wire tip. This channel became the main method of energy transformation between the arc and the molten pool. The calculation results of plasma resistivity show that the laser plasma has low resistivity as the starting point of conductive channel formation. When the laser pulse duration increases, the intensity of the plasma radiation spectrum and the plasma electron density will increase, and the electron temperature will decrease.

  14. Laser-assisted machining process simulation for precision mould/die manufacturing

    Directory of Open Access Journals (Sweden)

    Zeng Quanren

    2015-01-01

    Full Text Available Laser-assisted machining (LAM is a kind of thermally assisted manufacturing process which preheats workpiece material with a highly-localized laser beam and then is followed by a conventional machining operation. It could greatly improve the machinability and gives better machining quality, especially suitable for hard-to-cut materials such as superalloys, tool steels. For manufacturing the high-precision moulds/dies that could fabricate micro and precision components, the thermal assistance at the local cutting zone, will help to lower the cutting force and consequently improve the internal surface quality of the machined moulds/dies. In this paper, a numerical study of the laser-assisted cutting of plastic mould steel NAK80 is reported. The simulation of LAM of NAK80 is realized by combining two procedures: simulation of moving laser heat source applied on the local surface of workpiece which causes the corresponding temperature field arise and material soften, and simulation of the subsequent cutting processes. This research will offer the die/mould manufacturers a more efficient planning tool for the fabrication of the micro, precision dies/moulds of high surface quality, and hence, for forming the high-quality micro components as well as for longer die/mould life.

  15. A novel robotic platform for laser-assisted transurethral surgery of the prostate.

    Science.gov (United States)

    Russo, S; Dario, P; Menciassi, A

    2015-02-01

    Benign prostatic hyperplasia (BPH) is the most common pathology afflicting ageing men. The gold standard for the surgical treatment of BPH is transurethral resection of the prostate. The laser-assisted transurethral surgical treatment of BPH is recently emerging as a valid clinical alternative. Despite this, there are still some issues that hinder the outcome of laser surgery, e.g., distal dexterity is strongly reduced by the current endoscopic instrumentation and contact between laser and prostatic tissue cannot be monitored and optimized. This paper presents a novel robotic platform for laser-assisted transurethral surgery of BPH. The system, designed to be compatible with the traditional endoscopic instrumentation, is composed of a catheter-like robot provided with a fiber optic-based sensing system and a cable-driven actuation mechanism. The sensing system allows contact monitoring between the laser and the hypertrophic tissue. The actuation mechanism allows steering of the laser fiber inside the prostatic urethra of the patient, when contact must be reached. The design of the proposed robotic platform along with its preliminary testing and evaluation is presented in this paper. The actuation mechanism is tested in in vitro experiments to prove laser steering performances according to the clinical requirements. The sensing system is calibrated in experiments aimed to evaluate the capability of discriminating the contact forces, between the laser tip and the prostatic tissue, from the pulling forces exerted on the cables, during laser steering. These results have been validated demonstrating the robot's capability of detecting sub-Newton contact forces even in combination with actuation.

  16. Laser-assisted chemical vapor deposition setup for fast synthesis of graphene patterns

    Science.gov (United States)

    Zhang, Chentao; Zhang, Jianhuan; Lin, Kun; Huang, Yuanqing

    2017-05-01

    An automatic setup based on the laser-assisted chemical vapor deposition method has been developed for the rapid synthesis of graphene patterns. The key components of this setup include a laser beam control and focusing unit, a laser spot monitoring unit, and a vacuum and flow control unit. A laser beam with precision control of laser power is focused on the surface of a nickel foil substrate by the laser beam control and focusing unit for localized heating. A rapid heating and cooling process at the localized region is induced by the relative movement between the focalized laser spot and the nickel foil substrate, which causes the decomposing of gaseous hydrocarbon and the out-diffusing of excess carbon atoms to form graphene patterns on the laser scanning path. All the fabrication parameters that affect the quality and number of graphene layers, such as laser power, laser spot size, laser scanning speed, pressure of vacuum chamber, and flow rates of gases, can be precisely controlled and monitored during the preparation of graphene patterns. A simulation of temperature distribution was carried out via the finite element method, providing a scientific guidance for the regulation of temperature distribution during experiments. A multi-layer graphene ribbon with few defects was synthesized to verify its performance of the rapid growth of high-quality graphene patterns. Furthermore, this setup has potential applications in other laser-based graphene synthesis and processing.

  17. Diode laser-assisted transcanalicular dacryocystorhinostomy: the effect of age on the results

    Directory of Open Access Journals (Sweden)

    Fahrettin Akay

    2015-06-01

    Full Text Available ABSTRACT Purpose: The aim of this study was to explore the effect of age on the success of transcanalicular diode laser-assisted dacryocystorhinostomy (TCDCR. Methods: Seventy patients (70 eyes who underwent transcanalicular diode laser-assisted dacryocystorhinostomy for the treatment of nasolacrimal duct obstruction as a primary surgery were included in this retrospective, nonrandomized study. The patients were divided into two groups according to age. Mean ages were 21.3 ± 3.3 in group 1 and 60.3 ± 7.3 in group 2. The records of the 3-, 6-, and 12-month follow-up examinations were evaluated, and the anatomical and functional outcomes were noted. Functional success was defined as the absence of epiphora as indicated by the patient. Anatomical success was determined as patency of the neo-ostium with irrigation. Results: At the 3-month follow-up, 67% cases in group 1 showed anatomical success and 52% showed functional success; in group 2, the rates were 100% and 92%, respectively. Functional and anatomical success rates were the same for both the 6- and 12-month visits; 46% in group 1 and 76% in group 2. The results in group 2 were significantly better at all three follow-up visits (p<0.05. Conclusions: This study clearly showed that the older patients experienced better transcanalicular diode laser-assisted dacryocystorhinostomy results than the younger patients. The diminished inflammatory response in the older population may be a possible contributing factor to these results.

  18. Femtosecond laser-assisted sutureless anterior lamellar keratoplasty for superficial corneal opacities.

    Science.gov (United States)

    Jabbarvand, Mahmoud; Hashemian, Hesam; Khodaparast, Mehdi; Ghadimi, Hadi; Khalilipour, Elias

    2014-11-01

    To evaluate the visual and refractive outcomes, endothelial cell count (ECC), ocular surface changes, corneal aberrations, and biomechanical profile changes after femtosecond laser-assisted anterior lamellar keratoplasty surgery for superficial corneal scars. Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Prospective case series. Patients with superficial corneal scars had femtosecond laser-assisted anterior lamellar keratoplasty. Visual and refractive results, ECC, ocular surface changes, corneal aberrations, and biomechanical profiles were assessed preoperatively and for 1 year postoperatively. Nineteen eyes (19 patients) were evaluated. A significant decline occurred in refractive astigmatism and corneal astigmatism after 1 year. There was a nonsignificant reduction in corneal hysteresis and the corneal resistance factor from preoperatively to 1 year postoperatively. The corneal-compensated intraocular pressure (IOP) and Goldmann-correlated IOP increased during the follow-up; the increase was not significant. A statistically insignificant reduction in the root mean square for trefoil and spherical aberrations occurred between 1 month and 1 year postoperatively (P=.1 and P=.4, respectively). The decreases in primary coma and total higher-order aberrations approached significance (P=.08 and P=.07, respectively). There were no significant changes in the central corneal thickness, ECC, or ocular surface parameters. No intraoperative complications occurred. Femtosecond laser-assisted anterior lamellar keratoplasty was an efficient and safe procedure for improving the quality of vision in patients with anterior corneal pathology, and the results remained stable during the 1-year follow-up. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  19. Laser-Assisted Sheet Metal Working of High Strength Steels in Serial Production

    Science.gov (United States)

    Brecher, Christian; Emonts, Michael; Eckert, Markus

    Within the sheet metal working industry the demand for thinner sheet materials with very high strength is growing due to the increasing need to save energy and a responsible use of natural resources. The high strength and the low ductility restricts using state of art technology to sheer, bend, emboss or deep draw parts with the needed complexity and quality. The Fraunhofer IPT developed a combination of laser-assisted preheating and conventional punching to a new hybrid technology which allows to shear, bend, emboss and draw high strength materials with a high quality and complexity in a serial production.

  20. A Novel Approach to Brachycephalic Syndrome. 2. Laser-Assisted Turbinectomy (LATE).

    Science.gov (United States)

    Oechtering, Gerhard U; Pohl, Sabine; Schlueter, Claudia; Schuenemann, Riccarda

    2016-02-01

    To introduce a new surgical procedure based on interventional, laser-assisted removal of obstructing turbinate tissue to improve endonasal airway patency in brachycephalic dogs and to confirm the short and long term results using computed tomography (CT) and rhinoscopy. Prospective clinical study. Brachycephalic dogs (n = 158; 70 Pugs, 77 French Bulldogs, 11 English Bulldogs) referred for treatment of severe respiratory distress because of brachycephalic syndrome. Computed tomography and anterior and posterior rhinoscopy were performed to evaluate endonasal obstruction. Laser-assisted turbinectomy (LATE) using a diode laser was performed as part of a multilevel surgery. Nasal conchae that were causing airway obstruction were removed. The obstructing parts of the conchae were safely and efficiently removed by LATE, shaping a patent nasal airway in all dogs. The newly developed surgical procedure involved 3 steps: turbinectomy of the (1) concha nasalis ventralis; (2) rostral aberrantly growing turbinates (RAT); and (3) caudal aberrantly growing turbinates (CAT). Complications of the procedure included transient intraoperative hemorrhage in 51 of 158 dogs (32.3%); however, a temporary tamponade was necessary in only 2/158 dogs (1.3%). After 6 months, regrowth of turbinates required resection of possibly re-obstructing tissue in 25/158 dogs (15.8%; 1 Pug and 24 French Bulldogs). LATE is an effective method for creating a patent nasal airway in brachycephalic dogs with intranasal obstruction. © Copyright 2016 by The American College of Veterinary Surgeons.

  1. Fractional CO2 laser assisted delivery of topical anesthetics: A randomized controlled pilot study

    NARCIS (Netherlands)

    Meesters, Arne A.; Bakker, Myrna M.; de Rie, Menno A.; Wolkerstorfer, Albert

    2016-01-01

    Many dermatological procedures are performed under local anesthesia. Topical anesthesia requires prolonged occlusion and is often insufficient. Infiltration anesthesia is associated with discomfort. Pretreatment with an ablative fractional laser (AFXL) may enhance penetration of topical drugs,

  2. Multi-scale graphene patterns on arbitrary substrates via laser-assisted transfer-printing process

    KAUST Repository

    Park, J. B.

    2012-01-01

    A laser-assisted transfer-printing process is developed for multi-scale graphene patterns on arbitrary substrates using femtosecond laser scanning on a graphene/metal substrate and transfer techniques without using multi-step patterning processes. The short pulse nature of a femtosecond laser on a graphene/copper sheet enables fabrication of high-resolution graphene patterns. Thanks to the scale up, fast, direct writing, multi-scale with high resolution, and reliable process characteristics, it can be an alternative pathway to the multi-step photolithography methods for printing arbitrary graphene patterns on desired substrates. We also demonstrate transparent strain devices without expensive photomasks and multi-step patterning process. © 2012 American Institute of Physics.

  3. Femtosecond laser-assisted cataract surgery after penetrating keratoplasty: a case report.

    Science.gov (United States)

    Cao, Danmin; Wang, Shiming; Wang, Yong

    2017-06-24

    Cataract surgery after penetratingkeratoplasty (PKP) is often challenging due to changes in the integrity of the cornea caused by PKP. For example, corneal endothelial cell (CEC) loss and corneal edema commonly occur after traditional phacoemulsification cataract surgery in patients that previously had successful PKP. Recent studies have reported that femtosecond laser-assisted cataract surgery (FLACS) significantly reduces the need for ultrasound energy minimizing mechanical damage to the cornea and results in a reduction of CEC loss and corneal edema. We report a case in which FLACS was used in a patient with previous PKP. This case supports the suggestion that the use of the femtosecond laser improves the surgical outcome of cataract surgery after PKP. This improvement may be result of the precise incision, controlled capsulorhexis, and reduced lens fragmentation experienced with the femtosecond laser which helps to reduce potential complications of cataract surgery after PKP.

  4. Laser-assisted gingivectomy in pediatric patients: A novel alternative treatment

    Directory of Open Access Journals (Sweden)

    G Gontiya

    2011-01-01

    Full Text Available Gingival enlargement is quite a common pathology in pediatric patients and may be inflammatory, noninflammatory, or a combination of both. Idiopathic gingival fibromatosis, although rare, is a slowly progressive benign enlargement that affects the marginal gingiva, attached gingival, and interdental papilla. The fibromatosis may potentially cover the exposed tooth surfaces, causing esthetic and functional problems. The treatment of gingival fibromatosis is essential because it causes difficulties with mastication, speech problems, mispositioning of teeth, esthetic effects, and psychological difficulties for the patient. Traditional gingivectomy procedures have been a challenge for dentists who confront issues of patient cooperation and discomfort. In the last decade, laser procedures in oral cavity had shown many optimum effects in both hard and soft tissue procedures. Laser soft-tissue surgery has been shown to be well accepted by children. The following case report describes a laser-assisted gingivectomy procedure performed on a 13-year-old female.

  5. Laser-assisted welding of transparent polymers for microchemical engineering and life science

    Science.gov (United States)

    Pfleging, Wilhelm; Baldus, Oliver; Bruns, M.; Baldini, Alessandro; Bemporad, Edoardo

    2005-04-01

    In this contribution experimental studies on the laser-assisted welding of transparent polymers with diode laser (wavelength 940 nm) are presented to discuss their potential for the fabrication of micro-devices for micro-chemical engineering and life science. Micro-channel devices such as capillary electrophoresis chips, heat exchangers or static mixers for liquids and gases consist of different micro-patterned sheets with structural details in the range of a few μm. In micro-chemical engineering, in general the sheets of micro-devices are made of metals. In our approaches the use of transparent and micro-patterned polymers such as polyvinylidene fluoride (PVDF) is investigated. For the development of micro-devices in life science the use of sheets made of transparent polymers such as polymethylmethacrylate (PMMA) is presented, e.g., in capillary electrophoresis chips. Devices are built up by stacks of micro-patterned sheets which have to be joined. These sheets are patterned by micro-milling, CO2-laser cutting or hot embossing. Laser-assisted polymer welding of transparent and opaque materials is well established. But the welding of only transparent components is still a challenge in micro-system technology, especially if micro-structures are included. For this purpose very thin absorbing layers with a thickness of about 5nm to 20nm are used in order to establish a welding process between transparent and micro-patterned polymers. The strength of the bonding is characterized by tensile tests as function of absorbing layer thickness, temperature, laser scan velocity and laser scan overlap. The topography is investigated with atomic force microscopy and low voltage scanning electron microscopy.

  6. "Blow-torch phenomenon" during laser assisted excision of a thyroglossal cyst at the base of the tongue

    Directory of Open Access Journals (Sweden)

    Anitha G Bhat

    2012-01-01

    Full Text Available We report a case of blow-torch phenomenon encountered during diode laser assisted excision of a thyroglossal cyst in a child. This is first such case report from India and highlights an unusual complication which anesthesiologists need to be aware of due to the increasing use of operative laser.

  7. Corneal biomechanical properties after laser-assisted in situ keratomileusis and photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Hwang ES

    2017-10-01

    Full Text Available Eileen S Hwang,1 Brian C Stagg,1 Russell Swan,1 Carlton R Fenzl,1 Molly McFadden,2 Valliammai Muthappan,1 Luis Santiago-Caban,1 Mark D Mifflin,1 Majid Moshirfar1,3 1Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, 2Department of Internal Medicine, University of Utah, Salt Lake City, 3HDR Research Center, Hoopes Vision, Draper, UT, USA Background: The purpose of this study was to evaluate the effects of laser-assisted in situ keratomileusis (LASIK and photorefractive keratectomy (PRK on corneal biomechanical properties.Methods: We used the ocular response analyzer to measure corneal hysteresis (CH and corneal resistance factor (CRF before and after refractive surgery.Results: In all, 230 eyes underwent LASIK and 115 eyes underwent PRK without mitomycin C (MMC. Both procedures decreased CH and CRF from baseline. When MMC was used after PRK in 20 eyes, it resulted in lower corneal biomechanical properties at 3 months when compared to the other procedures, but all three procedures had similar values at 12 months.Conclusion: Significant but similar decreases in corneal biomechanical properties after LASIK, PRK without MMC, and PRK with MMC were noted. Keywords: corneal biomechanics, photorefractive keratectomy, laser-assisted in situ keratomileusis, corneal hysteresis, corneal resistance factor, mitomycin C

  8. Comparison of femtosecond laser-assisted descemetic and predescemetic lamellar keratoplasty for keratoconus

    Directory of Open Access Journals (Sweden)

    Yan Lu

    2017-01-01

    Full Text Available Purpose: The purpose of this study is to compare the outcomes following femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK with 75% of stromal dissection (predescemetic group and femtosecond laser-assisted DALK using big-bubble technique with total stromal resection (descemetic group for the treatment of keratoconus. Subjects and Methods: Twenty eyes of 17 patients with keratoconus were studied. There were 10 eyes of 9 patients in predescemetic group and 10 eyes of 8 patients in descemetic group. The postoperative best-corrected visual acuity (BCVA, manifest refraction, keratometry, endothelial cell density (ECD, and central corneal thickness (CCT were analyzed. Results: All surgeries were performed uneventfully. At 1 year after surgery, the BCVA, corneal astigmatism, keratometry, CCT, and ECD between two groups were not statistically significant (all P > 0.05. However, the mean manifest refraction was −9.43 ± 7.44 diopter (D and −1.03 ± 1.13D in predescemetic and descemetic groups, respectively, which was statistically significant between two groups (P < 0.05. Conclusions: The results of BCVA and corneal astigmatism, keratometry, ECD, and CCT were comparable between two groups. However, the mean postoperative manifest refraction was lower in descemetic group.

  9. Femtosecond Laser-Assisted Intrastromal Relaxing Incisions After Penetrating Keratoplasty: Effect of Incision Depth.

    Science.gov (United States)

    Wetterstrand, Olli; Holopainen, Juha M; Krootila, Kari

    2015-07-01

    To correlate the efficacy of femtosecond laser-assisted intrastromal relaxing incisions after penetrating keratoplasty with the posterior depth of corneal incisions. Twenty eyes of 20 patients were treated for regular postoperative penetrating keratoplasty astigmatism. Sutures had been removed and refraction had stabilized. Ultrasound pachymetry was used to calculate incisional depth. Femtosecond laser-assisted paired arcuate incisions were made inside the graft stroma, leaving 90 µm of intact anterior cornea including epithelium. The intact posterior corneal margin was 10% of the measured corneal thickness for 10 patients (10% group) and 125 µm for the remaining 10 patients (125-µm group). Follow-up visits consisted of biomicroscopy, intraocular pressure measurement, fundus examination, and topographic evaluation using anterior segment optical coherence tomography at 1 and 3 months. Postoperative corneal thickness and the depth of incisions were measured with optical coherence tomography. Corrected distance visual acuity improved from 0.5 to 0.3 logMAR (Snellen: 20/63 to 20/40, P astigmatism (P incisions is correlated with the posterior depth of the incisions. The deeper incisions were more effective. Copyright 2015, SLACK Incorporated.

  10. Pulsed laser ablation of copper

    Science.gov (United States)

    Jordan, R.; Cole, D.; Lunney, J. G.; Mackay, K.; Givord, D.

    1995-02-01

    The laser ablation of copper with a 532 nm, 6 ns laser has been investigated in the regime normally used for pulsed laser deposition. The ablation depth per pulse and the flux and energy distribution of the ions in the plume were measured and compared to the deposition rate as measured by a quartz microbalance. These measurements were compared with an analytic model of ablation via a laser sustained plasma. It is shown that self-sputtering of the growing film is significant.

  11. Influence of pulse width in laser assisted texturing on moly-chrome films

    Science.gov (United States)

    Ezhilmaran, V.; Vijayaraghavan, L.; Vasa, N. J.; Krishnan, Sivarama

    2018-02-01

    Continuous micro-channels were formed on the surface of the automotive piston rings using two different lasers, namely nanosecond and femtosecond pulsed laser. Tribology measurements were conducted to compare the friction properties of the samples fabricated with the laser pulse width of nanosecond and femtosecond order. The femtosecond laser ablation comparatively minimized the re-deposition layer, heat affected zone around the micro-channel compared to the nanosecond laser ablation. Owing to the localized material ablation, the compressive residual stress was not altered with femtosecond laser processing. The friction test was conducted using reciprocating type friction measurement setup for the loads ranging from 10 to 130 N. The friction coefficients of all the textured samples were reduced compared to the non-textured samples. Furthermore, it is observed that the average friction coefficient was low with the femtosecond laser textured samples compared to that of the nanosecond laser textured samples of the same dimensions. The results show that the thermally induced defects while using the nanosecond laser ablation might have influenced the tribological properties.

  12. Evaporation mechanisms of MgO in laser assisted atom probe tomography

    KAUST Repository

    Mazumder, Baishakhi

    2011-05-01

    In this paper the field evaporation properties of bulk MgO and sandwiched MgO layers in Fe are compared using laser assisted Atom Probe Tomography. The comparison of flight time spectra gives an estimate of the evaporation times as a function of the wavelength and the laser energy. It is shown that the evaporation takes place in two steps on two different time scales in MgO. It is also shown that as long as the MgO layer is buried in Fe, the evaporation is dominated by the photon absorption in Fe layer at the tip apex. Eventually the evaporation process of MgO is discussed based on the difference between the bulk materials and the multilayer samples. © 2010 Elsevier B.V.

  13. Femtosecond laser-assisted intrastromal corneal ring segment implantation for high astigmatism correction after penetrating keratoplasty.

    Science.gov (United States)

    Lisa, Carlos; García-Fernández, Miriam; Madrid-Costa, David; Torquetti, Leonardo; Merayo-Lloves, Jesús; Alfonso, José Fernando

    2013-11-01

    To assess the visual and refractive outcomes of femtosecond laser-assisted implantation of Ferrara-type intrastromal corneal ring segments (ICRS) in post-penetrating keratoplasty (PKP) eyes. Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. Cohort study. Patients with previous PKP had ICRS implantation after femtosecond laser tunnel creation. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities and residual refractive errors were recorded before and 6 months after ICRS implantation. The power vector method was used to analyze refractive errors preoperatively and postoperatively. This study enrolled 32 eyes of 30 patients. The mean UDVA (Snellen decimal) changed from 0.16 ± 0.15 (SD) preoperatively to 0.43 ± 0.28 postoperatively (Pastigmatism components were significantly reduced after ICRS implantation (Pastigmatism correction in post-PKP eyes. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Laser-assisted bending of Titanium Grade-2 sheets: Experimental analysis and numerical simulation

    Science.gov (United States)

    Gisario, Annamaria; Mehrpouya, Mehrshad; Venettacci, Simone; Barletta, Massimiliano

    2017-05-01

    External force laser-assisted bending of Titanium Grade-2 flat sheets to achieve sharp bending angles (>140°) with small fillet radii is herein investigated. In particular, the influence of the operational parameters, laser power, scan speed, number of passes, on bending angles and fillet radii of the metal substrates is analysed. The experimental results show that shaping of the substrates can be performed with great reliability, being springback largely minimised in broad operational ranges. Exploratory Data Analysis (EDA) allows the design of first approximation technological models and, in turn, the development of 3d processing maps. Based on the experimental findings, numerical modelling of the bending process by the Finite Element Method (FEM) through ABAQUS/Explicit software is also developed. The numerical model is found to match with great accuracy the experimental results, being it also extremely flexible and responsive to the change of the operational parameters.

  15. Deposition mechanism and microstructure of laser-assisted cold-sprayed (LACS) Al-12 wt.%Si coatings: effects of laser power

    CSIR Research Space (South Africa)

    Olakanmi, EO

    2013-06-01

    Full Text Available Surface treatment is one of the most costly processes for treating metallic components against corrosion. Laser-assisted cold spray (LACS) has an opportunity to decrease those costs particularly in transportation systems, chemical industries...

  16. En-face OCT microleakage investigation after laser-assisted dental hard tissue treatment

    Science.gov (United States)

    Todea, Carmen; Balabuc, Cosmin; Sinescu, Cosmin; Negrutiu, Meda; Filip, Laura; Bradu, Adrian; Podoleanu, Adrian Gh.

    2008-09-01

    Purpose: To investigate using en-face Optical Coherence Tomography (OCT) the microleakage after Er:YAG laser cavity preparation. Material and Methods: Thirty single- and multi-rooted freshly extracted human teeth divided into two study groups, group I (laser) and group II (control), were used in this study. In group I, Class V cavities were prepared using laser on the buccal surface of each tooth. The laser device used was an Er:YAG laser (2940 nm, VSP, 250-320 mJ, 10-20 Hz). In group II, cavities were prepared conventionally and acid etched on the oral surface of the same tooth. All cavities were filled with composite resin. The cavity microleakage was investigated using en-face Optical Coherence Tomography prototype, based on transverse scanning and operating at 1300 nm. Results: The investigation demonstrated qualitatively the reduction of microleakage in cavities prepared with Er:YAG laser as compared to the control group, in which cavities were prepared conventionally. Conclusion: The en-face OCT method provided a superior non-invasive and real time investigation method, thus reducing the occurrence of secondary caries by early detection. Moreover, based on the results of this investigation, it may be concluded that Er:YAG laser-assisted cavity preparation leads to reduction of microleakage.

  17. Three-dimensional thermal analysis for laser assisted machining of ceramics using FEA

    Science.gov (United States)

    Wu, Xuefeng; Zhang, Hongzhi; Wang, Yang

    2009-05-01

    Laser-assisted machining (LAM) is an effective method machining difficult-to-machine materials such as ceramics which uses a high power laser to focally heat a workpiece prior to material removal with a traditional cutting tool. To understand the thermal process of laser heating and predict the operation parameters for experiment system, a transient, three-dimensional heat transfer model for LAM of silicon nitride is developed using Finite Element Method. The model is based on temperature-dependent thermophysical properties and considering convective heat transfer and radiation exchange. A method of locally refining mesh according to machining sequence is used to reduce calculating time. The effects of the operating parameters, such as laser power, laser beam diameter, laser preheat time, cutting depth, feed rate and rotational speed on the average temperature of cutting region and the temperature of laser incidence are investigated. The thermal stresses induced from the high temperature gradient are also investigated. The maximum normal thermal stress failure criterion is used to predict the possibility of cracking on silicon nitride material owing to thermal stress. The method of selecting optimizing operation parameters is presented.

  18. Treatment of postoperative keratoplasty astigmatism using femtosecond laser-assisted intrastromal relaxing incisions.

    Science.gov (United States)

    Wetterstrand, Olli; Holopainen, Juha M; Krootila, Kari

    2013-06-01

    To investigate the effectiveness of femtosecond laser-assisted intrastromal relaxing incisions for astigmatism management and establish laser treatment parameters. Sixteen eyes of 16 patients had regular astigmatism after penetrating keratoplasty. All sutures had been removed and the refraction was stabilized. Paired arcuate intrastromal incisions were made 180° apart within the graft stroma with a femtosecond laser preserving the epithelium. Follow-up examinations were performed at 1 week, 2 weeks, 1 month, and 3 months. The logMAR corrected distance visual acuity (CDVA) improved from 0.50 ± 0.29 to 0.32 ± 0.23 (Snellen 20/63 to 20/40). Refractive and topographic anterior cylinders decreased from 6.8 ± 2.2 diopters (D) to 3.7 ± 1.7 D and from 9.5 ± 4.8 D to 4.4 ± 2.1 D, respectively. Stabilization of topographic cylinder was observed 1 month postoperatively. The worse the preoperative CDVA was and the higher the preoperative values for the refractive and topographic cylinders were, the higher the surgically induced changes were. Anterior side cut angles at 90° and 120° produced similar results. A bulge of incision occurred in one eye requiring compression sutures. Significant improvement in CDVA and refractive and topographic cylinders indicated a good effect of femtosecond laser-assisted intrastromal relaxing incisions in reducing astigmatism. No advantage between 90° and 120° anterior side cut angles was found. No infections were recorded and no patient expressed discomfort. Copyright 2013, SLACK Incorporated.

  19. Eye-Tracker-Guided Non-Mechanical Excimer Laser Assisted Penetrating Keratoplasty

    Directory of Open Access Journals (Sweden)

    Achim Langenbucher

    2013-03-01

    Full Text Available Purpose: The purpose of the study was to implement a new eye tracking mask which could be used to guide the laser beam in automated non-mechanical excimer laser assisted penetrating keratoplasty. Materials and methods: A new trephination mask design with an elevated surface geometry has been proposed with a step formation between conical and flat interfaces. Two recipient masks of 7.5/8.0 mm have been manufactured and tested. The masks have outer diameter of 12.5 mm, step formation at 10.5 mm, and slope of conical surfaces 15°. Its functionality has been tested in different lateral positions and tilts on a planar surface, and pig eye experiments. After successful validation on porcine eyes, new masks have been produced and tested on two patients. Results: The build-in eye tracking software of the MEL 70 was always able to capture the masks. It has been shown that the unwanted pigmentation/pattern induced by the laser pulses on the mask surface does not influence the eye-tracking efficiency. The masks could be tracked within the 18 × 14 mm lateral displacement and up to 12° tilt. Two patient cases are demonstrated. No complications were observed during the surgery, although it needs some attention for aligning the mask horizontally before trephination. Stability of eye tracking masks is emphasized by inducing on purpose movements of the patient head. Conclusion: Eye-tracking-guided penetrating keratoplasty was successfully applied in clinical practice, which enables robust tracking criteria within an extended range. It facilitates the automated trephination procedure of excimer laser-assisted penetrating keratoplasty.

  20. Intacs for keratoconus and post-LASIK ectasia: mechanical versus femtosecond laser-assisted channel creation.

    Science.gov (United States)

    Carrasquillo, Karen G; Rand, Janet; Talamo, Jonathan H

    2007-09-01

    To evaluate the efficacy of intracorneal ring segments to treat keratoconus and post-laser in situ keratomileusis (LASIK) keratectasia implanted by using either mechanical dissection or a femtosecond laser. Thirty-three eyes of 29 patients had intracorneal ring segments implanted by using mechanical dissection (17 eyes) or a femtosecond laser (16 eyes). Mean follow-up was 10.3 months. Parameters assessed before and after surgery included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refractive spherical equivalent (MRSE), refractive cylinder (RC), best contact lens-corrected visual acuity (BCLVA), and contact lens tolerance. Statistically significant changes occurred for all parameters when we analyzed all 33 eyes as 1 group. Mean UCVA LogMar values improved from 1.0 +/- 0.3 (20/200) to 0.6 +/- 0.4 (20/80) (P surgery (P mechanical dissection and femtosecond laser-assisted techniques. However, although statistical power was adequate to detect changes in clinical parameters as a result of surgery, it was not sufficient to conclusively show such differences between surgical techniques. For mild to moderate cases of keratoconus and post-LASIK keratectasia, the use of a femtosecond laser for Intacs channel creation seems as effective as mechanical dissection. Future studies are warranted to further evaluate channel creation by a femtosecond laser.

  1. Long-term results of femtosecond laser-assisted sutureless anterior lamellar keratoplasty.

    Science.gov (United States)

    Shousha, Mohamed Abou; Yoo, Sonia H; Kymionis, George D; Ide, Takeshi; Feuer, William; Karp, Carol L; O'Brien, Terrence P; Culbertson, William W; Alfonso, Eduardo

    2011-02-01

    To evaluate the long-term results of femtosecond laser-assisted anterior lamellar keratoplasty (FALK) for anterior corneal pathologies. Retrospective, noncomparative, interventional case series. Thirteen consecutive patients who underwent FALK for anterior corneal pathologies. Femtosecond laser-assisted sutureless anterior lamellar keratoplasty. Best spectacle-corrected visual acuity (BSCVA), manifest refraction, need for adjunctive surgery, and complications. Follow-up ranged from 12 to 69 months (mean = 31 months). The BSCVA was significantly improved over preoperative values at the 12-, 18-, 24-, and 36-month visits. A BSCVA greater than 20/30 was achieved in 54% of patients at the 12-month visit when all 13 patients were available for follow-up, in 50% and 33% of patients at the 18- and 24-month visits, respectively, when 12 patients were available, and in 60% and 50% of patients at the 36- and 48-month visits when 5 and 2 patients were available, respectively. The BSCVA of the eye that completed the 60- and 70-month visits was 20/50. Patients achieved a mean gain of 5 lines of BSCVA at the 6-, 12-, 18-, and 24-month visits, 4 lines at the 36-month visit, 5 lines at the 48-month visit, and 6 lines at the 60- and 72-month visits. Two patients lost a mean of 1.5 lines of BSCVA because surface haze developed after photorefractive keratectomy (PRK) and granular dystrophy recurred in the graft. At a mean of 5 weeks postoperatively, 83.3% of patients achieved BSCVA within 2 lines of that recorded at the 24-month visit. At the 12-month visit, mean spherical equivalent and refractive astigmatism were -0.4 diopters (D) and 2.2 D, respectively, with no significant shift from preoperative values or values recorded in different follow-up visits. Adjunctive surgeries included phototherapeutic keratectomy, PRK, cataract extraction, and epithelial ingrowth debridement. Complications included residual corneal pathology, mild interface haze, anisometropia, recurrence of

  2. Laser-assisted inkjet printing of highly viscous fluids with sub-nozzle resolution

    Science.gov (United States)

    Delrot, Paul; Modestino, Miguel A.; Psaltis, Demetri; Moser, Christophe

    2016-04-01

    Drop-on-demand inkjet printing is mostly based on thermal and piezo-actuation, allowing for densely packed nozzles in inkjet printers. However, the droplet diameter is typically defined by the nozzle diameter, thus limiting the range of viscosity that can be jetted to 10-100 mPa.s to prevent nozzle clogging. Here, we present a laser-assisted system for the delivery of micro-droplets of highly viscous fluids with sub-nozzle resolution. Highly focused supersonic jets have recently been demonstrated by focusing a nanosecond pulse of light into a micro-capillary filled with dyed water, hence generating a cavitation bubble. The consequent pressure wave impact on the concave free surface of the liquid generated flow-focused micro-jets. We implemented this technique for the production of low velocity micro-droplets with photopolymer inks of increasing viscosity (0.6-148 mPa.s) into a 300 μm-wide glass capillary using low laser energies (3-70 μJ). Time-resolved imaging provided details on the droplet generation. Single micro-droplets of diameter 70-80 μm were produced on demand with inks of viscosity 0.6-9 mPa.s with good controllability and reproducibility, thus enabling to print two-dimensional patterns with a precision of 13 μm. Furthermore, the primary droplet produced with the most viscous fluid was about 66% of the capillary diameter. Preliminary results also showed that the process is linearly scalable to narrower capillaries (100-200 μm), thus paving the way for a compact laser-assisted inkjet printer. A possible application of the device would be additive manufacturing as the printed patterns could be consequently cured.

  3. A predictive thermal dynamic model for parameter generation in the laser assisted direct write process

    Science.gov (United States)

    Shang, Shuo; Fearon, Eamonn; Wellburn, Dan; Sato, Taku; Edwardson, Stuart; Dearden, G.; Watkins, K. G.

    2011-11-01

    The laser assisted direct write (LADW) method can be used to generate electrical circuitry on a substrate by depositing metallic ink and curing the ink thermally by a laser. Laser curing has emerged over recent years as a novel yet efficient alternative to oven curing. This method can be used in situ, over complicated 3D contours of large parts (e.g. aircraft wings) and selectively cure over heat sensitive substrates, with little or no thermal damage. In previous studies, empirical methods have been used to generate processing windows for this technique, relating to the several interdependent processing parameters on which the curing quality and efficiency strongly depend. Incorrect parameters can result in a track that is cured in some areas and uncured in others, or in damaged substrates. This paper addresses the strong need for a quantitative model which can systematically output the processing conditions for a given combination of ink, substrate and laser source; transforming the LADW technique from a purely empirical approach, to a simple, repeatable, mathematically sound, efficient and predictable process. The method comprises a novel and generic finite element model (FEM) that for the first time predicts the evolution of the thermal profile of the ink track during laser curing and thus generates a parametric map which indicates the most suitable combination of parameters for process optimization. Experimental data are compared with simulation results to verify the accuracy of the model.

  4. Granulation tissue exhibits differences in alpha-smooth muscle actin expression after laser-assisted skin closure (LASC)

    Science.gov (United States)

    Mordon, Serge R.; Capon, Alexandre; Fleurisse, Laurence; Creusy, Collette

    2001-05-01

    Laser assisted skin closure (LASC) has been shown to accelerate wound healing and to reduce scarring. However, the mechanisms involved during the cutaneous wound repair after LASC remain unclear. This study aimed to evaluate the inflammation process and the wound repair fibroplasia, particularly the involvement of granulation tissue fibroblasts (myofibroblasts).

  5. Evaluation of microstructure and micro-hardness of 410L SS coatings fabricated using laser assisted cold spraying: process development

    CSIR Research Space (South Africa)

    Mathebula, TE

    2014-11-01

    Full Text Available , contaminating and erosive environments which accelerate the degradation of these components. Surface coatings are generally used to protect and prolong the lifetime of the parts. Laser Assisted Cold Spray (LACS) is a relatively new surface coating process which...

  6. A meta-analysis of aneurysm formation in laser assisted vascular anastomosis (LAVA)

    Science.gov (United States)

    Chen, Chen; Peng, Fei; Xu, Dahai; Cheng, Qinghua

    2009-08-01

    Laser assisted vascular anastomosis (LAVA) is looked as a particularly promising non-suture method in future. However, aneurysm formation is one of the main reasons delay the clinical application of LAVA. Some scientists investigated the incidence of aneurysms in animal model. To systematically analyze the literature on reported incidence of aneurysm formation in LAVA therapy, we performed a meta-analysis comparing LAVA with conventional suture anastomosis (CSA) in animal model. Data were systematically retrieved and selected from PUBMED. In total, 23 studies were retrieved. 18 studies were excluded, and 5 studies involving 647 animals were included. Analysis suggested no statistically significant difference between LAVA and CSA (OR 1.24, 95%CI 0.66-2.32, P=0.51). Result of meta analysis shows that the technology of LAVA is very close to clinical application.

  7. Comparing the intraoperative complication rate of femtosecond laser-assisted cataract surgery to traditional phacoemulsification

    Directory of Open Access Journals (Sweden)

    Ming Chen

    2015-02-01

    Full Text Available AIM: To compare the complication rate of femtosecond laser-assisted cataract surgery (FLACS and traditional phacoemulsification for the first 18mo of FLACS use at a private surgical center in Hawaii. METHODS: A retrospective chart review was conducted from January 2012 to June 2013. The first 273 consecutive eyes receiving FLACS and 553 eyes receiving traditional phacoemulsification were examined. All surgeries were performed at a single surgical center in Hawaii. The presence of intraoperative complications was used as the main outcome measure. Approval was obtained from the institutional review board of the University of Hawaii. RESULTS: The overall complication rate for FLACS was 1.8%, while that of the traditional procedure was 5.8% (PCONCLUSION: FLACS is comparable in safety, if not safer, than traditional cataract surgery when performed by qualified cataract surgeons on carefully selected patients.

  8. Outcomes of femtosecond laser-assisted cataract surgery performed by surgeons-in-training.

    Science.gov (United States)

    Brunin, Greg; Khan, Khurrum; Biggerstaff, Kristin S; Wang, Li; Koch, Douglas D; Khandelwal, Sumitra S

    2017-04-01

    To compare intraoperative factors and post-operative outcomes of femtosecond laser-assisted cataract surgery (FLACS) and manual cataract surgery performed by resident surgeons. All cases of FLACS performed by resident surgeons during the 2013-2014 academic year were compared to a control group of manual cataract surgery cases with regards to pre-operative patient data, operative complications, cumulative dissipated energy (CDE), postoperative corrected distance visual acuity (CDVA), refractive prediction error (RPE), and corneal edema. There were no significant preoperative differences in the FLACS (n = 57) and manual (n = 68) groups. Operative complication rates were similar in cases with sufficient data and follow-up with a higher rate of posterior capsule tear in the manual group. CDE (percent-seconds) was lower in the FLACS group (FLACS: 14.5 ± 7.5; manual: 21.6 ± 11.5; p < 0.01). CDVA (LogMAR) was comparable at 1 month postoperatively (FLACS: 0.004 ± 0.08; manual: 0.024 ± 0.11; p = 0.24) and 1 year postoperatively (FLACS: 0.013 ± 0.06; manual: 0.032 ± 0.09; p = 0.37). No difference in RPE was found at 1 month postoperatively (FLACS: 0.38 ± 0.24 D; manual: 0.41 ± 0.49 D; p = 0.66) and 1 year postoperatively (FLACS: 0.49 ± 0.63 D; manual: 0.34 ± 0.26 D; p = 0.31). Femtosecond laser-assisted cataract surgery is safe and effective compared to manual cataract surgery when performed by resident surgeons. Both 1-month and 1-year outcomes show no difference in refractive predictive error in FLACS compared to manual cataract surgery in surgeons in training.

  9. Long-term results in obstructive sleep apnea syndrome (OSAS after laser-assisted uvulopalatoplasty (LAUP.

    Directory of Open Access Journals (Sweden)

    Önder Göktas

    Full Text Available Obstructive sleep apnea syndrome (OSAS is a serious disease. The etiology of and optimum therapy options for this disorder have been much discussed and have been the subject of many publications. One much discussed therapy option is laser-assisted uvulopalatoplasty (LAUP. Despite conflicting opinions and guidelines which recommend that it should not be used, it remains in use. Patients who had previously undergone this procedure were invited for follow-up appointments, at which they were asked to complete a questionnaire, underwent an ENT examination and underwent sleep laboratory analysis using a portable sleep lab device. The average time since LAUP treatment was 11 years. The cohort comprised 25 patients. The average preoperative apnea-hypopnea-index (AHI score was 25.25/h; the average postoperative AHI score 23.62/h. Closer examination of our data enabled us to identify 10 responders (40% and 15 non-responders (60%. 12% (3/25 of non-responders experienced either no reduction in their AHI score or an increase compared to their preoperative AHI score of less than 5/h. In the remaining 48% (12/25, AHI increased by more than 5/h compared to the preoperative figure. Our questionnaire showed that 40% (10/25 of patients suffered from dry mouth and 20% (5/25 from foreign body sensation. The data led us to conclude that laser-assisted uvulopalatoplasty can indeed result in a reduction in AHI score comparable to other mucosal resection methods. Also in common with these methods, the efficacy of the therapy reduces with time and the procedure carries a high risk of bringing about an increase in the patient's AHI score.

  10. Laser-Assisted Simultaneous Transfer and Patterning of Vertically Aligned Carbon Nanotube Arrays on Polymer Substrates for Flexible Devices

    KAUST Repository

    In, Jung Bin

    2012-09-25

    We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications. © 2012 American Chemical Society.

  11. Numerical modeling and experimental investigation of laser-assisted machining of silicon nitride ceramics

    Science.gov (United States)

    Shen, Xinwei

    Laser-assisted machining (LAM) is a promising non-conventional machining technique for advanced ceramics. However, the fundamental machining mechanism which governs the LAM process is not well understood so far. Hence, the main objective of this study is to explore the machining mechanism and provide guidance for future LAM operations. In this study, laser-assisted milling (LAMill) of silicon nitride ceramics is focused. Experimental experience reveals that workpiece temperature in LAM of silicon nitride ceramics determines the surface quality of the machined workpiece. Thus, in order to know the thermal features of the workpiece in LAM, the laser-silicon nitride interaction mechanism is investigated via heating experiments. The trends of temperature affected by the key parameters (laser power, laser beam diameter, feed rate, and preheat time) are obtained through a parametric study. Experimental results show that high operating temperature leads to low cutting force, good surface finish, small edge chipping, and low residual stress. The temperature range for brittle-to-ductile transition should be avoided due to the rapid increase of fracture toughness. In order to know the temperature distribution at the cutting zone in the workpiece, a transient three-dimensional thermal model is developed using finite element analysis (FEA) and validated through experiments. Heat generation associated with machining is considered and demonstrated to have little impact on LAM. The model indicates that laser power is one critical parameter for successful operation of LAM. Feed and cutting speed can indirectly affect the operating temperatures. Furthermore, a machining model is established with the distinct element method (or discrete element method, DEM) to simulate the dynamic process of LAM. In the microstructural modeling of a beta-type silicon nitride ceramic, clusters are used to simulate the rod-like grains of the silicon nitride ceramic and parallel bonds act as the

  12. Central corneal sensitivity after small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a meta-analysis of comparative studies

    National Research Council Canada - National Science Library

    He, Miao; Huang, Wenyong; Zhong, Xingwu

    2015-01-01

    ...) versus femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia. Eligible studies were identified by systematically searching PubMed, the Cochrane Library, Embase and the Chinese Biomedicine Database...

  13. Diode laser assisted minimal invasive sphenoidotomy for endoscopic transphenoidal pituitary surgery: our technique and results.

    Science.gov (United States)

    Lee, Jih-Chin; Lai, Wen-Sen; Ju, Da-Tong; Chu, Yueng-Hsiang; Yang, Jinn-Moon

    2015-03-01

    During endoscopic sinus surgery (ESS), intra-operative bleeding can significantly compromise visualization of the surgical field. The diode laser that provides good hemostatic and vaporization effects and excellent photocoagulation has been successfully applied in endoscopic surgery with several advantages. The current retrospective study demonstrates the feasibility of diode laser-combined endoscopic sinus surgery on sphenoidotomy. The patients who went through endoscopic transphenoidal pituitary surgery were enrolled. During the operation, the quality of the surgical field was assessed and graded by the operating surgeon using the scale proposed by Boezaart. The mean operation time was 37.80 ± 10.90 minutes. The mean score on the quality of surgical field was 1.95. A positive correlation between the lower surgical field quality score and the shorter surgical time was found with statistical significance (P < 0.0001). No infections, hemorrhages, or other complications occurred intra- or post-operatively. The diode laser-assisted sphenoidotomy is a reliable and safe approach of pituitary gland surgery with minimal invasiveness. It is found that application of diode laser significantly improved quality of surgical field and shortened operation time. © 2015 Wiley Periodicals, Inc.

  14. Attosecond delays in laser-assisted photodetachment from closed-shell negative ions

    Science.gov (United States)

    Lindroth, Eva; Dahlström, Jan Marcus

    2017-07-01

    We study laser-assisted photodetachment time delays by attosecond pulse trains from the closed-shell negative ions F- and Cl-. We investigate the separability of the delay into two contributions: (i) the Wigner-like delay associated with one-photon ionization by the attosecond pulse train and (ii) the delay associated with the exchange of an additional laser photon in the presence of the potential of the remaining target. Based on the asymptotic form of the wave packet, the latter term is expected to be negligible because the ion is neutralized, leading to a vanishing laser-ion interaction with increasing electron-atom separation. While this asymptotic behavior is verified at high photoelectron energies, we also quantify sharp deviations at low photoelectron energies. Further, these low-energy delays are clearly different for the two studied anions, indicating a breakdown of the universality of laser-ion-induced delays. The fact that the short-range potential can induce a delay of as much as 50 as can have implications for the interpretation of delay measurements also in other systems that lack long-range potential.

  15. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  16. Nd:YAG Pulsed Laser Assisted Machining of AMS 5708 Waspaloy Alloy

    Science.gov (United States)

    Sharifi, Zahra; Shoja-Razavi, Reza; Vafaei, Reza; Hashemi, Sayed Hamid

    2018-01-01

    Due to very high strenght, low thermal conductivity, and high work hardening rate, the machinability of nickel-based superalloys is poor at room temperature. Laser-assisted machining (LAM) can provide a better aspect of machining such alloys. Since the wavelength of Nd:YAG laser is about 1/10th of that of CO2 laser, absorption and heating efficiency of Nd:YAG laser is much higher on metals and especially superalloys. Transmission of Nd:YAG laser through fiber optics to the heating point on the workpiece is a simple task during machining. This makes the LAM process more convenient and practical than the CM process. In this study a model is introduced for LAM of waspaloy, and its machinability is evaluated in terms of ease of material removal. Also, a temperature generation model is introduced for the Nd:YAG laser beam. Furthemore, wear behavior of an uncoated tungsten carbide and the formed chips were compared during the LAM and the CM of waspolay. To study the wear mechanism, the worn cutting tool was studied via scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). The formed chips were also evaluated via SEM and optical microscopy. Based on the results, the optimum LAM conditions were obtained at a cutting speed of 24 m/min and a feed rate of 0.06 mm/rev when a 400 W laser mean power and 80 Hz frequency are applied. Under these conditions, the temperature ahead of the cutting tool edge on the surface of workpiece was estimated to be 524°C. In comparison with CM, a significant improvement in tool wear and a better chip morphology were achieved through LAM, and also specific cutting energy and surface roughness were reduced by 25 and 20%, respectively.

  17. Effect of double-pulse-laser polarization and time delay on laser-assisted etching of fused silica

    Science.gov (United States)

    Chu, Dongkai; Sun, Xiaoyan; Dong, Xinran; Yin, Kai; Luo, Zhi; Chen, Guowei; Duan, Ji-An; Hu, Youwang; Zhao, Xinyu

    2017-11-01

    High-aspect-ratio microchannels were fabricated by femtosecond-double-pulse-laser-assisted polarization-selective etching. The etching rate and uniformity of the microchannels were mainly determined by the double-pulse polarization and time delay. We found that when the two sub-pulses had a different polarization (one linear, the other circular), the microchannel etching rate increased by a factor of 10 compared to when both sub-pulses were linearly polarized. The maximum etching rate was obtained when the polarization combination was circular for the first sub-pulse and vertical for the second one. In this case, the etching rate was independent from the time delay. Laser confocal microscopy images showed that when the polarization was circular, the area modified by the laser was larger than when the polarization was linear, explaining the higher etching rate value obtained after irradiation with circularly polarized laser light.

  18. Field enhancement induced laser ablation

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kjelstrup-Hansen, Jakob

    . The accompanying field enhancement substantially lowers the ablation threshold of the polymer film and thus creates local ablation spots and corresponding topographic modifications of the polymer film. Such modifications are quantified straightforwardly via scanning electron and atomic force microscopy. Thickness......Sub-diffraction spatially resolved, quantitative mapping of strongly localized field intensity enhancement on gold nanostructures via laser ablation of polymer thin films is reported. Illumination using a femtosecond laser scanning microscope excites surface plasmons in the nanostructures...

  19. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

    Science.gov (United States)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

    2013-12-18

    Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  20. Corneal biomechanical changes in eyes with small incision lenticule extraction and laser assisted in situ keratomileusis.

    Science.gov (United States)

    Osman, Ihab Mohamed; Helaly, Hany Ahmed; Abdalla, Moones; Shousha, Mohsen Abou

    2016-07-26

    Evaluating the corneal biomechanical changes using the Ocular Response Analyzer and the Corvis ST in eyes with incision lenticule extraction (SMILE) and laser assisted in situ keratomileusis (LASIK). This is a retrospective study that included 50 eyes equally divided into two groups. The first group included eyes that underwent SMILE procedure using VisuMax® 500 kHz laser system (Carl Zeiss Meditec, Jena, Germany) and the second group included eyes that underwent LASIK procedure using the EX500 Allegretto excimer laser platform (Wavelight GmbH, Erlangen, Germany). The Ocular Response Analyzer (ORA) and the Corvis ST (CST) measured the corneal biomechanical changes before and after the procedures. The ORA showed significant decrease of corneal hysteresis (CH) and corneal resistance factor (CRF) in both groups postoperatively. The percentage of change of CH and CRF were found to be significantly higher in group II. There was no significant difference in the IOP with the ORA and the CST pre and postoperatively in either group. Using CST, the deformation amplitude and HC peak distances increased significantly in both groups. It was also noted that the mean percentage of change of the deformation amplitude was nearly five times higher in group II than group I. Both LASIK and SMILE substantially decreased the corneal biomechanical properties with greater reduction in the LASIK group.

  1. Clinical assessment of diode laser-assisted endoscopic intrasphenoidal vidian neurectomy in the treatment of refractory rhinitis.

    Science.gov (United States)

    Lai, Wen-Sen; Cheng, Sheng-Yao; Lin, Yuan-Yung; Yang, Pei-Lin; Lin, Hung-Che; Cheng, Li-Hsiang; Yang, Jinn-Moon; Lee, Jih-Chin

    2017-12-01

    For chronic rhinitis that is refractory to medical therapy, surgical intervention such as endoscopic vidian neurectomy (VN) can be used to control the intractable symptoms. Lasers can contribute to minimizing the invasiveness of ENT surgery. The aim of this retrospective study is to compare in patients who underwent diode laser-assisted versus traditional VN in terms of operative time, surgical field, quality of life, and postoperative complications. All patients had refractory rhinitis with a poor treatment response to a 6-month trial of corticosteroid nasal sprays and underwent endoscopic VN between November 2006 and September 2015. They were non-randomly allocated into either a cold instrument group or a diode laser-assisted group. Vidian nerve was excised with a 940-nm continuous wave diode laser through a 600-μm silica optical fiber, utilizing a contact mode with the power set at 5 W. A visual analog scale (VAS) was used to grade the severity of the rhinitis symptoms for quality of life assessment before the surgery and 6 months after. Of the 118 patients enrolled in the study, 75 patients underwent cold instrument VN and 43 patients underwent diode laser-assisted VN. Patients in the laser-assisted group had a significantly lower surgical field score and a lower postoperative bleeding rate than those in the cold instrument group. Changes in the VAS were significant in preoperative and postoperative nasal symptoms in each group. The application of diode lasers for vidian nerve transection showed a better surgical field and a lower incidence of postoperative hemorrhage. Recent advancements in laser application and endoscopic technique has made VN safer and more effective. We recommend this surgical approach as a reliable and effective treatment for patients with refractory rhinitis.

  2. Laser-assisted fabrication of electronic circuits using the ADDIMID process

    Science.gov (United States)

    Esser, Gerd; Jahrsdoerfer, Bernd; Urmoneit, Uwe

    2001-06-01

    A novel laser-assisted technology for the additive fabrication of microelectronic circuits on three-dimensional polymer substrates (Molded Interconnect Devices, 3-D MID) has been developed. Advantages of the ADDIMID-approach are: a very short process chain, no etchants, no coatings (important on 3D substrates), industry-proven laser technology (diode-pumped Nd:YAG) and high writing velocity (greater than 600 mm/s). An essential component of the process is a special composite substrate material. The material consists of a polymer matrix containing finely dispersed microcapsules. The microcapsules are fabricated by coating micron-scaled copper powder with nano-scaled SiO2. The SiO2 coating provides electrical insulation of the copper particles and promotes adhesion to the polymer matrix. The microcapsules are mixed with a thermoplastic base material to form a granulate. Polymer substrates are produced by injection-molding. A laser direct-write process with galvanometric beam deflection is used to generate the circuit pattern. The laser uncovers the microcapsules and removes the SiO2 coating. Metallic copper is exposed in the processed surface regions. The exposed copper acts as catalytic nucleation site. The circuitry is then formed by chemical copper-plating. This paper presents experimental investigations on direct writing with a CO2- and a diode-pumped Nd:YAG-laser. Effects of variations in focus position, writing velocity, and pulse frequency are described and specified with regard to their impact on the quality of the circuit patterns. A phenomenological model of the laser direct-write process is outlined.

  3. Potential surface alteration effects of laser-assisted periodontal surgery on existing dental restorations.

    Science.gov (United States)

    Kilinc, Evren; Rothrock, James; Migliorati, Erica; Drukteinis, Saulius; Roshkind, David M; Bradley, Paul

    2012-05-01

    Laser-assisted gingivectomies are performed in proximity to teeth, existing restorations, and implants. In case of accidental exposures, a detrimental surface defect may cause failure. Surface interactions should be evaluated for safety margin determination of certain laser-material combinations. The purpose of this in vitro study was to assess the microscopic and visible effects of CO2, Nd:YAG, and 810-nm diode laser irradiations on various dental materials and tooth tissue. Study samples were fabricated (10 x 7.5 mm irradiation surface area, 1 mm thickness) from eight material groups (amalgam, base metal, gold, palladium-silver, composite, ceramic, titanium, and extracted tooth slices). Laser irradiations were performed with CO2, Nd:YAG, and 810-nm diode lasers using the manufacturer's recommended settings for gingivectomy at a 45-degree angle for 30 seconds. Irradiated surfaces were evaluated under SEM at 200x and 1,000x magnifications. Standardized photographs were obtained using a camera mount system (10x high-definition macro lens). The SEM images and photographs were correlated to determine surface interactions. Nd:YAG detrimentally affected all metallic materials and tooth structures. CO2 altered amalgam, gold, and palladium-silver slightly, whereas composite, ceramic, and tooth surfaces were detrimentally altered. The 810-nm diode altered amalgam, gold, titanium, palladium-silver, and composite but only gold and palladium-silver surfaces were barely traceable. Within the limitations of this in vitro study, surface effects were all instant; therefore, even a short accidental exposure may be destructive in some laser-material combinations. During gingivectomies, CO2 near tooth-colored restorations and Nd:YAG near metallic restorations and implants should be used carefully. The 810-nm diode was found to be safer due to its reversible alterations in only some materials. Further in vivo studies are necessary to clinically apply the outcomes of this study.

  4. The Big-Bubble Full Femtosecond Laser-Assisted Technique in Deep Anterior Lamellar Keratoplasty.

    Science.gov (United States)

    Buzzonetti, Luca; Petrocelli, Gianni; Valente, Paola; Iarossi, Giancarlo; Ardia, Roberta; Petroni, Sergio; Parrilla, Rosa

    2015-12-01

    To describe the big-bubble full femtosecond laser-assisted (BBFF) technique, which could be helpful in standardizing the big-bubble technique in deep anterior lamellar keratoplasty (DALK). Ten eyes of 10 consecutive patients affected by keratoconus underwent the BBFF technique using the 150-kHz IntraLase femtosecond laser (Intra-Lase FS Laser; Abbott Medical Optics, Inc., Santa Ana, CA). A 9-mm diameter metal mask with a single fissure 0.7 mm wide oriented at the 12-o'clock position was positioned into the cone, over the laser glass. The laser performed a ring lamellar cut (internal diameter = 3 mm; external diameter = 8 mm) 100 µm above the thinnest point, with the photodisruption effectively occurring only in the corneal stroma corresponding to the fissure to create a deep stromal channel; subsequently, an anterior side cut created an arcuate incision, from the corneal surface to the deep stromal channel on the mask's opening site. The mask was removed and the laser performed a full lamellar cut 200 µm above the thinnest point to create a lamella. After the removal of the lamella, the air needle was inserted into the stromal channel and air was injected to achieve a big bubble. The big bubble was achieved in 9 eyes (all type 1 bubbles) and all procedures were completed as DALK. Preliminary results suggest that the BBFF technique could help in standardizing the big-bubble technique in DALK, reducing the "learning curve" for surgeons who approach this technique and the risks of intraoperative complications. Copyright 2015, SLACK Incorporated.

  5. Precise femtosecond laser ablation of dental hard tissue: preliminary investigation on adequate laser parameters

    Science.gov (United States)

    Hikov, Todor; Pecheva, Emilia; Montgomery, Paul; Antoni, Frederic; Leong-Hoi, Audrey; Petrov, Todor

    2017-01-01

    This work aims at evaluating the possibility of introducing state-of-the-art commercial femtosecond laser system in restorative dentistry by maintaining well-known benefits of lasers for caries removal, but also in overcoming disadvantages such as thermal damage of irradiated substrate. Femtosecond ablation of dental hard tissue is investigated by changing the irradiation parameters (pulsed laser energy, scanning speed and pulse repetition rate), assessed for enamel and dentin. The femtosecond laser system used in this work may be suitable for cavity preparation in dentin and enamel, due to the expected effective ablation and low temperature increase when using ultra short laser pulses. If adequate laser parameters are selected, this system seems to be promising for promoting a laser-assisted, minimally invasive approach in restorative dentistry.

  6. Spatiotemporal closure of fractional laser-ablated channels imaged by optical coherence tomography and reflectance confocal microscopy

    NARCIS (Netherlands)

    Banzhaf, Christina A.; Wind, Bas S.; Mogensen, Mette; Meesters, Arne A.; Paasch, Uwe; Wolkerstorfer, Albert; Haedersdal, Merete

    2016-01-01

    Optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) offer high-resolution optical imaging of the skin, which may provide benefit in the context of laser-assisted drug delivery. We aimed to characterize postoperative healing of ablative fractional laser (AFXL)-induced

  7. Laser-assisted electron scattering in strong-field ionization of dense water vapor by ultrashort laser pulses

    Science.gov (United States)

    Wilke, M.; Al-Obaidi, R.; Moguilevski, A.; Kothe, A.; Engel, N.; Metje, J.; Kiyan, I. Yu; Aziz, E. F.

    2014-08-01

    We report on strong-field ionization of dense water gas in a short infrared laser pulse. By employing a unique combination of photoelectron spectroscopy with a liquid micro-jet technique, we observe how the character of electron emission at high kinetic energies changes with the increase of the medium density. This change is associated with the process of laser-assisted electron scattering (LAES) on neighboring particles, which becomes a dominant mechanism of hot electron emission at higher medium densities. The manifestation of this mechanism is found to require densities that are orders of magnitude lower than those considered for heating the laser-generated plasmas via the LAES process. The experimental results are supported by simulations of the LAES yield with the use of the Kroll-Watson theory.

  8. Femtosecond laser assisted design of sutureless intrastromal graft as an alternative to partial thickness keratoplasty

    Science.gov (United States)

    Rossi, Francesca; Durkee, Heather; Pini, Roberto; Canovetti, Annalisa; Malandrini, Alex; Lenzetti, Ivo; Rubino, Pierangela; Leaci, Rosachiara; Neri, Alberto; Scaroni, Patrizia; Menabuoni, Luca; Macaluso, Claudio

    2014-02-01

    Minimally invasive laser assisted surgery in ophthalmology is continuously developing in order to find new surgical approaches, preserve patient tissue and improve surgical results in terms of cut precision, restoration of visual acuity, and invasiveness. In order to achieve these goals, the current approach in corneal transplant is lamellar keratoplasty, where only the anterior or posterior part of the patient's cornea is substituted depending on the lesion or pathology. In this work, we present a novel alternative approach: a case study of intrastromal sutureless transplant, where a portion of the anterior stroma of a donor cornea was inserted into the stroma of the recipient cornea, aiming to restore the correct thickness of the patient's cornea. The patient cornea was paracentrally thin, as the result of a trophic ulcer due to ocular pemphigoid. A discoid corneal graft from the anterior stroma of a donor eye was prepared: a femtosecond laser cut with a trapezoidal profile (thickness was 300 μm, minor and major basis were 3.00 and 3.50 mm, respectively). In the recipient eye, an intrastromal cut was also performed with the femtosecond laser using a specifically designed mask; the cut position was 275 μm in depth. The graft was loaded into an injector and inserted as an intrastromal presbyopic implant. The postoperative analysis evidenced a clear and stable graft that selectively restored corneal thickness in the thinned area. Intrastromal corneal transplant surgery is a minimally invasive alternative to anterior or posterior lamellar keratoplasty in select cases. We believe that Sutureless Intrastromal Laser Keratoplasty (SILK) could open up new avenues in the field of corneal transplantation by fully utilizing the potential and precision of existing lasers.

  9. Laser-assisted scanning probe alloying nanolithography (LASPAN) and its application in gold-silicon system

    Science.gov (United States)

    Peng, Luohan

    Nanoscale science and technology demand novel approaches and new knowledge to further advance. Nanoscale fabrication has been widely employed in both modern science and engineering. Micro/nano lithography is the most common technique to deposit nanostructures. Fundamental research is also being conducted to investigate structural, physical and chemical properties of the nanostructures. This research contributes fundamental understanding in surface science through development of a new methodology. Doing so, experimental approaches combined with energy analysis were carried out. A delicate hardware system was designed and constructed to realize the nanometer scale lithography. We developed a complete process, namely laser-assisted scanning probe alloying nanolithography (LASPAN), to fabricate well-defined nanostructures in gold-silicon (Au-Si) system. As a result, four aspects of nanostructures were made through different experimental trials. A non-equilibrium phase (AuSi3) was discovered, along with a non-equilibrium phase diagram. Energy dissipation and mechanism of nanocrystalization in the process have been extensively discussed. The mechanical energy input and laser radiation induced thermal energy input were estimated. An energy model was derived to represent the whole process of LASPAN.

  10. Retinal and choroidal thickness after femtosecond laser-assisted and standard phacoemulsification

    Directory of Open Access Journals (Sweden)

    Asena BS

    2017-08-01

    Full Text Available Bilgehan Sezgin Asena,1 Eyyup Karahan,2 Mahmut Kaskaloglu1 1Department of Ophthalmlolgy, Kaskaloglu Eye Hospital, 2Department of Ophthalmlolgy, Batigoz Eye Hospital, Izmir, Turkey Purpose: The purpose of this study was to compare the short-term changes in retina and choroidal tissue after femtosecond laser-assisted cataract surgery (FLACS and standard phacoemulsification (PE surgery.Methods: In all, 25 eyes undergoing FLACS and 27 eyes undergoing PE surgery were included in this nonrandomized, retrospective, cross-sectional study. Central retinal thickness (CRT and choroidal thickness (CT were measured pre- and postoperatively (at day 1, 1 week later, and after 1 month with spectral domain optical coherence tomography (OCT in all patients and were compared. For group comparisons, chi-square test and independent t-test were used. Postoperative values were compared to the baseline using a paired t-test. The magnitude of the change from baseline to the peak was analyzed by multiple regression models in an attempt to explain possible influence variables. Results: Pre and postoperative CRT measurements were similar in both groups. The mean subfoveal CT at day 1, after 1 week, and 1 month were significantly higher than baseline CT measurements in the PE group. Conclusion: FLACS might have an advantage in regard to postoperative choroidal changes. Keywords: femtosecond laser, cataract, visual acuity, central retinal thickness, choroidal thickness, optical coherence tomography

  11. Femtosecond laser-assisted keratoplasty in failed penetrating keratoplasty and globe trauma.

    Science.gov (United States)

    Rush, Sloan W; Fraunfelder, Frederick W; Mathers, William D; Chamberlain, Winston D

    2011-12-01

    To demonstrate feasibility and present postoperative outcomes for femtosecond laser-assisted keratoplasty (FLAK) in the setting of previous failed conventional penetrating keratoplasty (PK) and previous open-globe trauma with corneal laceration. In this retrospective case series, data were collected for 12 consecutive patients at the Casey Eye Institute (Oregon Health and Science University, Portland, OR) with the primary diagnosis of either failed PK or open-globe trauma with corneal laceration that underwent zigzag incision FLAK. Outcome measures included topographic astigmatism, best spectacle-corrected visual acuity, uncorrected visual acuity, pinhole visual acuity, intraocular pressure, and timing of selective suture removal (or adjustment) over various follow-up intervals up to 18 months postoperatively. Mean follow-up was 10.42 months. Mean postoperative topographic astigmatism ranged between 3.56 and 6.81 diopters (D). Mean best spectacle-corrected visual acuity (BSCVA) in logarithm of minimal angle of resolution (logMAR) equivalents ranged between 0.18 and 0.61 as compared with 1.28 for preoperative BSCVA (P = 0.0064). Thirty-three percent (4 of 12) of patients had significantly increased intraocular pressure develop during the first year of follow-up that required glaucoma therapy. No adverse events or complications occurred as a result of either the femtosecond laser procedure itself or during the transportation of the patient from the laser suite to the operating room. FLAK is a feasible transplantation technique in the setting of previous failed PK and open-globe trauma with corneal laceration. Significant globe pressure associated with laser applanation did not cause rupture of old corneal wounds among our case series. Postoperative astigmatism is within previous reported limits in the literature under varying suturing techniques. Development of ocular hypertension within 1 year of follow-up was comparable with historically reported rates for PK in

  12. Femtosecond laser-assisted keratoplasty combined with cataract extraction in a patient with keratoconus and oculocutaneous albinism

    Directory of Open Access Journals (Sweden)

    Dorottya Pásztor

    2016-01-01

    Full Text Available In this study, we present a case of a 58-year-old male patient with oculocutaneous albinism, keratoconus, total cataract, and glaucoma originating from father-daughter incest. He underwent femtosecond laser-assisted keratoplasty with “open-sky” cataract extraction and posterior chamber intraocular lens implantation. One week after surgery his uncorrected visual acuity improved from hand motion to 20/200. Six months later corneal K values were 49.1 D in the flat and 50.0 D in the steep meridian. The graft had a central corneal thickness of 488 µm and was well fitted. The patient's quality of life improved substantially due to the surgery. To the best of our knowledge, this is the first report on the association of albinism with advanced keratoconus, total cataract, and glaucoma. Moreover, no previous report on femtosecond laser-assisted keratoplasty using VisuMax femtosecond laser system with “open-sky” cataract extraction is available in the literature. The VisuMax femtosecond laser-assisted keratoplasty ensures fast patient rehabilitation in such challenging cases.

  13. Influence of instrument conditions on the evaporation behavior of uranium dioxide with UV laser-assisted atom probe tomography

    Science.gov (United States)

    Valderrama, B.; Henderson, H. B.; Gan, J.; Manuel, M. V.

    2015-04-01

    Atom probe tomography (APT) provides the ability to detect subnanometer chemical variations spatially, with high accuracy. However, it is known that compositional accuracy can be affected by experimental conditions. A study of the effect of laser energy, specimen base temperature, and detection rate is performed on the evaporation behavior of uranium dioxide (UO2). In laser-assisted mode, tip geometry and standing voltage also contribute to the evaporation behavior. In this investigation, it was determined that modifying the detection rate and temperature did not affect the evaporation behavior as significantly as laser energy. It was also determined that three laser evaporation regimes are present in UO2. Very low laser energy produces a behavior similar to DC-field evaporation, moderate laser energy produces the desired laser-assisted field evaporation characteristic and high laser energy induces thermal effects, negatively altering the evaporation behavior. The need for UO2 to be analyzed under moderate laser energies to produce accurate stoichiometry distinguishes it from other oxides. The following experimental conditions providing the best combination of mass resolving power, accurate stoichiometry, and uniform evaporation behavior: 50 K, 10 pJ laser energy, a detection rate of 0.003 atoms per pulse, and a 100 kHz repetition rate.

  14. Patterning of Endothelial Cells and Mesenchymal Stem Cells by Laser-Assisted Bioprinting to Study Cell Migration

    Science.gov (United States)

    Medina, Manuela; Rémy, Murielle; Thébaud, Noélie Brunehilde; Bareille, Reine; Chassande, Olivier; Amédée, Joëlle; Catros, Sylvain

    2016-01-01

    Tissue engineering of large organs is currently limited by the lack of potent vascularization in vitro. Tissue-engineered bone grafts can be prevascularized in vitro using endothelial cells (ECs). The microvascular network architecture could be controlled by printing ECs following a specific pattern. Using laser-assisted bioprinting, we investigated the effect of distance between printed cell islets and the influence of coprinted mesenchymal cells on migration. When printed alone, ECs spread out evenly on the collagen hydrogel, regardless of the distance between cell islets. However, when printed in coculture with mesenchymal cells by laser-assisted bioprinting, they remained in the printed area. Therefore, the presence of mesenchymal cell is mandatory in order to create a pattern that will be conserved over time. This work describes an interesting approach to study cell migration that could be reproduced to study the effect of trophic factors. PMID:27833916

  15. [Preliminary evaluation of the femtosecond laser-assisted cataract surgery in 300 cases].

    Science.gov (United States)

    Wang, Yong; Bao, Xianyi; Zhou, Yanli; Xu, Rong; Peng, Tingting; Sun, Ming; Cao, Danmin; He, Ling

    2015-09-01

    To evaluate the clinical outcome of the femtosecond laser-assisted cataract surgery (FLACS) in our first 300 cases. In this retrospective study, the study group comprised 300 cases (300 eyes) in which FLACS was done. The control group comprised 300 cases (300 eyes) in which phacoemulsification was performed. The steps of the FLACS included capsulotomy, lens fragmentation, corneal incisions, and creation of incisions within the peripheral cornea to aid the correction of pre-existing astigmatism. After the FLACS, 2.2-mm coaxial micro-incision phacoemulsification and implantation of an intraocular lens were operated. The preoperative best corrected visual acuity (BCVA) and postoperative uncorrected visual acuity (UCVA), the cumulative dissipated energy (CDE) of the phacoemulsification, and the parameters of the FLACS, including the docking time, the suction time and the laser time, were recorded. The complications of the FLACS were analyzed. The FLACS was successfully completed in 99.33% of the cases. The docking time was (24.6 ± 16.8) sec, the suction time was (101.27 ± 20.09) sec, and the laser time was (23.3 ± 5.5) sec. The most common complications of the FLACS included suction break (7/300, 2.33%), subconjunctival hemorrhage (58/300, 19.33%), pupillary constriction (47/300, 15.67%), incision at a wrong site (13/300, 4.33%), anterior capsular tag (17/300, 5.67%), decentration of the capsulorhexis (11/300, 3.67%), failure to split the lens nucleus (5/300, 1.67%), and posterior capsular ruptures (1/300, 0.33%). The CDE was 5.52 ± 5.18 in the FLACS group and 8.37 ± 7.91 in the traditional phaco group (P 0.05). Compared with the conventional phacoemulsification surgery, the FLACS can achieve less CDE and better early postoperative visual acuity. Long-term effects remain to be investigated.

  16. Holmium laser assisted ′anatomical′ enucleation of adenoma of benign hyperplasia of prostate

    Directory of Open Access Journals (Sweden)

    Shivadeo S Bapat

    2006-01-01

    Full Text Available Aims: To present our technique of Holmium Laser assisted "ANATOMICAL" enucleation of the benign prostatic adenoma (HoLEP in 219 patients. Procedure is based on the principle of digital enucleation of the adenoma from its surgical capsule, but performed entirely by perurethral endoscopic technique assisted by Holmium Laser. Materials and Methods: From March 2001 to November 2004, 219 patients under went HoLEP. After the initial cuts from bladder neck to verumontanum at 5 and 7 o′clock position, capsule is identified. The beak of the resectoscope sheath was inserted in the plane between the capsule and the adenoma and the adenoma was physically pushed away towards the urethra from the capsule. Laser was used to coagulate the bleeders, to cut the mucosal attachments and tough stromal tissue. Procedure was repeated for median and two lateral lobes. There was minimal bleeding and fluid absorption. Complications were few. Results: In 206 cases successful enucleation of the adenoma was carried out. First 13 cases formed part of the learning curve and were completed by standard transurethral resection of prostate (TURP. IPSS score dropped from average of 23 to 8 and peak flow improved from 20. No patient had postoperative urinary incontinence or stricture. Conclusions: HoLEP is an effective alternative to TURP. Ultimate end results replicate the end results of open enucleation of BPH without its morbidity and have all the advantages of endoscopic surgery. It offers distinct advantages over standard TURP as the incidence of blood transfusion and fluid absorption are greatly minimized.

  17. Laser assisted synthesis of carbon nanoparticles with controlled viscosities for printing applications

    OpenAIRE

    Bagga, Komal; McCann, Ronan; Wang, M.; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot

    2015-01-01

    High-quality carbon nanoparticles with controlled viscosity and high aqueous stability were prepared by liquid-phase laser ablation of a graphite target in deionized water. The size distribution was found to vary from 5 nm to 50 nm with mean size of 18 nm, in the absence of any reducing chemical reagents. Efficient generation of short chain polyynes was recorded for high laser repetition rates. Homogeneous and stable nanoparticle suspensions with viscosities ranging from 0.89 to 12 mPa.s were...

  18. In situ printing of mesenchymal stromal cells, by laser-assisted bioprinting, for in vivo bone regeneration applications

    OpenAIRE

    Virginie Keriquel; Hugo Oliveira; Murielle Rémy; Sophia Ziane; Samantha Delmond; Benoit Rousseau; Sylvie Rey; Sylvain Catros; Joelle Amédée; Fabien Guillemot; Jean-Christophe Fricain

    2017-01-01

    Bioprinting has emerged as a novel technological approach with the potential to address unsolved questions in the field of tissue engineering. We have recently shown that Laser Assisted Bioprinting (LAB), due to its unprecedented cell printing resolution and precision, is an attractive tool for the in situ printing of a bone substitute. Here, we show that LAB can be used for the in situ printing of mesenchymal stromal cells, associated with collagen and nano-hydroxyapatite, in order to favor ...

  19. Suction loss during femtosecond laser-assisted small-incision lenticule extraction: Incidence and analysis of risk factors.

    Science.gov (United States)

    Osman, Ihab M; Awad, Ramy; Shi, Wei; Abou Shousha, Mohamed

    2016-02-01

    To determine the incidence of and analyze risk factors for suction loss during femtosecond laser-assisted small incision lenticule extraction in the management of myopia or myopic astigmatism. Roayah Vision Correction Center, Alexandria, Egypt. Retrospective comparative case-control study. All eyes that had femtosecond laser-assisted small-incision lenticule extraction for the correction of myopia and myopic astigmatism performed between August 2010 and April 2014 were included. Eyes that developed suction loss were identified. Their characteristics, including demographic data (age and sex), eye laterality, manifest refraction, flat keratometry (K) reading, steep K reading, K astigmatism, optical zone, central corneal thickness, and corneal cap diameter and thickness, were compared with those in randomly selected control eyes to determine the risk factors for developing suction loss. Of the 3376 eyes that had femtosecond laser-assisted small-incision lenticule extraction during the study, 70 (2.1%) developed loss of suction. The incidence decreased with surgical experience (5.06% in 2010, 3.59% in 2011, 3.41% in 2012, 2.32% in 2013, and 1.84% in 2014), suggesting a learning curve. A multivariate logistic regression model showed that eyes with a larger cap diameter were significantly more likely to develop suction loss (P = .023; odds ratio, 9.60). Surgical experience significantly decreased the risk for suction loss during femtosecond laser-assisted small incision lenticule extraction for the correction of myopia or myopic astigmatism but did not eliminate it. A larger cap diameter significantly increased the risk for developing the suction loss. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  20. Safety and efficacy of femtosecond laser-assisted arcuate keratotomy to treat irregular astigmatism after penetrating keratoplasty.

    Science.gov (United States)

    Fadlallah, Ali; Mehanna, Chadi; Saragoussi, Jean-Jacques; Chelala, Elias; Amari, Belkacem; Legeais, Jean-Marc

    2015-06-01

    To determine the refractive efficacy, predictability, stability, and complication rate of Intralase femtosecond laser-assisted astigmatic keratotomy (AK) for irregular astigmatism after penetrating keratoplasty (PKP). Ophthalmology Department, Hôtel-Dieu, Paris, France. Retrospective case series. Femtosecond laser-assisted AK was performed to treat high irregular astigmatism (>5.0 diopters [D]) after PKP. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction, vector analysis, and complications were evaluated. The study evaluated 62 eyes of 57 patients over a mean follow-up of 28 months ± 3.5 (SD). Preoperatively, the mean CDVA was 0.51 ± 0.26 logMAR and the mean UDVA was 0.98 ± 0.24 logMAR; 6 months postoperatively, the mean CDVA and UDVA improved to 0.40 ± 0.22 logMAR and 0.60 ± 0.2 logMAR, respectively (both P astigmatism was 7.1 ± 1.72 D; 6 months postoperatively, the mean refractive astigmatism was 2.6 ± 2.4 D (P astigmatism remained stable up to the end of follow-up. The efficacy index was 0.81 at 6 months and 0.67 at 2 years. There were 2 cases of microperforation, 3 cases of infectious keratitis, 3 graft rejection episodes, and 1 case of endophthalmitis. Overcorrection occurred in 12 eyes. Femtosecond laser-assisted AK was effective in reducing irregular astigmatism after PKP. Predictability of astigmatism correction is variable over time with a decrease in the efficacy index 2 years postoperatively. Refinement of the treatment nomogram for femtosecond laser-assisted AK for high astigmatism after PKP remains a major issue. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  1. Preparation of nanowire specimens for laser-assisted atom probe tomography.

    Science.gov (United States)

    Blumtritt, H; Isheim, D; Senz, S; Seidman, D N; Moutanabbir, O

    2014-10-31

    The availability of reliable and well-engineered commercial instruments and data analysis software has led to development in recent years of robust and ergonomic atom-probe tomographs. Indeed, atom-probe tomography (APT) is now being applied to a broader range of materials classes that involve highly important scientific and technological problems in materials science and engineering. Dual-beam focused-ion beam microscopy and its application to the fabrication of APT microtip specimens have dramatically improved the ability to probe a variety of systems. However, the sample preparation is still challenging especially for emerging nanomaterials such as epitaxial nanowires which typically grow vertically on a substrate through metal-catalyzed vapor phase epitaxy. The size, morphology, density, and sensitivity to radiation damage are the most influential parameters in the preparation of nanowire specimens for APT. In this paper, we describe a step-by-step process methodology to allow a precisely controlled, damage-free transfer of individual, short silicon nanowires onto atom probe microposts. Starting with a dense array of tiny nanowires and using focused ion beam, we employed a sequence of protective layers and markers to identify the nanowire to be transferred and probed while protecting it against Ga ions during lift-off processing and tip sharpening. Based on this approach, high-quality three-dimensional atom-by-atom maps of single aluminum-catalyzed silicon nanowires are obtained using a highly focused ultraviolet laser-assisted local electrode atom probe tomograph.

  2. In vivo confocal microscopic evaluation of corneal wound healing after femtosecond laser-assisted keratoplasty.

    Science.gov (United States)

    Shtein, Roni M; Kelley, Kurt H; Musch, David C; Sugar, Alan; Mian, Shahzad I

    2012-01-01

    To evaluate corneal wound healing after femtosecond laser-assisted keratoplasty (FLAK) using in vivo confocal microscopy (IVCM). Prospective, interventional, consecutive case series of 17 eyes after mushroom-shaped FLAK. IVCM was performed preoperatively and at 1, 3, 6, and 12 months postoperatively to assess wound healing. Mean keratocyte activation grade increased from preoperative levels to 1 month postoperatively in both the central (0.41 ± 0.62 to 1.73 ± 1.03) and peripheral (0.47 ± 0.52 to 1.57 ± 1.09) cornea, then gradually decreased through 12 months. Dendritic cells increased from preoperatively to 1 month postoperatively in both the central (0.71 ± 0.83 to 1.33 ± 0.98) and peripheral (0.79 ± 0.70 to 1.42 ± 0.90) cornea, then gradually decreased until 6 months postoperatively. Stromal reinnervation was 1 month postoperatively in 8 patients (50%). By 12 months, sub-epithelial nerves were observed centrally in 5 patients (45.5%). IVCM after FLAK shows an initial increase in keratocyte activation and dendritic cells that decrease over time. Corneal reinnervation is seen as early as 1 month postoperatively. Copyright 2012, SLACK Incorporated.

  3. Efficacy and safety of femtosecond laser-assisted corneal endothelial keratoplasty: a randomized multicenter clinical trial.

    Science.gov (United States)

    Cheng, Yanny Y Y; Schouten, Jan S A G; Tahzib, Nayyirih G; Wijdh, Robert-Jan; Pels, Elisabeth; van Cleynenbreugel, Hugo; Eggink, Catharina A; Rijneveld, Wilhelmina J; Nuijts, Rudy M M A

    2009-12-15

    To evaluate the efficacy and safety of femtosecond laser-assisted endothelial keratoplasty (FLEK) versus penetrating keratoplasty (PK) in patients with corneal endothelial disease. A randomized multicenter clinical trial of 80 eyes of 80 patients with corneal endothelial disease were randomized to FLEK or PK. Clinical outcomes (astigmatism and visual acuity) and incidence of postoperative complications were compared between the two groups. At 12 months, the percentage of eyes with a refractive astigmatism less than or equal to 3 diopters was higher in the FLEK group in comparison with the PK group (86.2% vs. 51.3%, P=0.004). The mean postoperative best corrected visual acuity was 20/70+/-2 lines in the FLEK group and 20/44+/-2 lines in the PK group (Pastigmatism and results in an absence of wound healing related problems in patients with endothelial disease. However, visual acuity is lower as compared with conventional PK, and the high level of endothelial cell loss warrants a modification of the insertion technique of the endothelial graft.

  4. Intraoperative videokeratography in penetrating keratoplasty and excimer laser-assisted lamellar keratoplasty for keratoconus.

    Science.gov (United States)

    Spadea, Leopoldo; Fiasca, Arianna; Federici, Simone

    2010-09-01

    To evaluate the usefulness of intraoperative computerized corneal topographic data in excimer laser-assisted lamellar keratoplasty (ELLK) and penetrating keratoplasty (PK). Prospective, comparative, interventional case series. Intra- and postoperative videokeratography (Keratron Scout) evaluation was performed on 30 eyes of 30 consecutive patients affected by keratoconus (16 men and 14 women; mean age 32.63±8.02 years) submitted to ELLK (15 eyes) using 16 interrupted 10-0 nylon stitches or to PK (15 eyes) using a 12-bite 10-0 nylon double-running continuous suture. In the ELLK group, the mean intraoperative keratometric astigmatism was 12.06±4.86 diopters (D), which changed to 5.19±2.51 D after topography-guided intraoperative suture adjustment. In the PK group, intraoperative keratometric astigmatism was 10.18±3.88 D, which changed to 3.49±0.41 D. After 24 months (sutures out), the mean videokeratographic keratometric astigmatism was 3.35±1.96 D in the ELLK group and 3.37±0.92 D in the PK group. The Alpins method of vector analysis showed some significant changes especially in the ELLK group. In keratoplasty surgery, videokeratography is useful for suture adjustment. In the PK group, using a double-running suture technique, the postoperative astigmatism (after all sutures were removed) was similar to the astigmatism measured intraoperatively by videokeratography. Copyright 2010, SLACK Incorporated.

  5. Inside the brachycephalic nose: conchal regrowth and mucosal contact points after laser-assisted turbinectomy.

    Science.gov (United States)

    Schuenemann, Riccarda; Oechtering, Gerhard

    2014-01-01

    This prospective observational study analyzed conchal regrowth after laser-assisted turbinectomy (LATE) in brachycephalic dogs and the mucosal contact of regrown conchae. Eighty brachycephalic dogs (41 pugs, 39 French bulldogs [FBs]) that underwent LATE because of obstructing conchae were evaluated by endoscopy 7 days and 6 mo after surgery. At 6 mo, 96% of FBs' and 65% of pugs' nasal cavities showed regrowth of turbinates. FBs showed higher growth grades than pugs. Revision surgery because of reobstructing regrowth was required in the nasal cavities of 17% of FBs and 3% of pugs. The mean number of contact points reduced from 3.0 in FB and 1.7 in pugs before surgery to 1.2 in FB and 0.2 in pugs after conchal regrowth. Recollapse of nares after surgery significantly influenced the frequency of reoccurrence of contact points. LATE was proven to be an effective treatment of intranasal obstruction caused by mucosal contact between conchae. Conchal regrowth commonly occurs after surgical removal, but the new conchae cause less obstruction due to a significant reduction in number of contact points. Revision surgery because of reobstruction is rarely necessary. The important physiologic functions of conchae make nonobstructing regrowth desirable.

  6. Sentinel Lymph Node Detection Using Laser-Assisted Indocyanine Green Dye Lymphangiography in Patients with Melanoma

    Directory of Open Access Journals (Sweden)

    Vikalp Jain

    2013-01-01

    Full Text Available Introduction. Sentinel lymph node (SLN biopsy is a vital component of staging and management of multiple cancers. The current gold standard utilizes technetium 99 (tech99 and a blue dye to detect regional nodes. While the success rate is typically over 90%, these two methods can be inconclusive or inconvenient for both patient and surgeon. We evaluated a new technique using laser-assisted ICG dye lymphangiography to identify SLN. Methods. In this retrospective analysis, we identified patients with melanoma who were candidates for SLN biopsy. In addition to tech99 and methylene blue, patients received a dermal injection of indocyanine green (ICG. The infrared signal was detected with the SPY machine (Novadaq, and nodes positive by any method were excised. Results. A total of 15 patients were evaluated, with 40 SLNs removed. Four patients were found to have nodal metastases on final pathology. 100% of these 4 nodes were identified by ICG, while only 75% (3/4 were positive for tech99 and/or methylene blue. Furthermore, none of the nodes missed by ICG (4/40 had malignant cells. Conclusion. ICG dye lymphangiography is a reasonable alternative for locating SLNs in patients with melanoma. Prospective studies are needed to better ascertain the full functionality of this technique.

  7. Observation on ultrastructure and histopathology of cornea following femtosecond laser-assisted deep lamellar keratoplasty for acute corneal alkaline burns

    Directory of Open Access Journals (Sweden)

    Wen-Jing Li

    2016-04-01

    Full Text Available AIM: To demonstrate the changes in ultrastructure and histopathology of the cornea in acute corneal alkaline burns after femtosecond laser-assisted deep lamellar keratoplasty. METHODS: The New Zealand white rabbits treated with alkaline corneal burn were randomized into two groups, Group A (16 eyes with femtosecond laser-assisted deep lamellar keratoplasty 24h after burn and Group B (16 eyes without keratoplasty as controls. All eyes were evaluated with transmission electron microscopy (TEM at 1, 2, 3, and 4wk follow-up, then all corneas were tested by hematoxylin and eosin staining histology. RESULTS: The corneal grafts in Group A were transparent, while those in Group B showed corneal stromal edema and loosely arranged collagen fibers. One week after treatment, TEM revealed the intercellular desmosomes in the epithelial layers and intact non-dissolving nuclei in Group A. At week 4, the center of the corneas in Group A was transparent with regularly arranged collagen fibers and fibroblasts in the stroma. In Group B, squamous cells were observed on the corneal surface and some epithelial cells were detached. CONCLUSION: Femtosecond laser-assisted deep lamellar keratoplasty can suppress inflammatory responses, prevent toxic substance-induced injury to the corneal endothelium and inner tissues with quicker recovery and better visual outcomes.

  8. Laser Ablation for Medical Applications

    Science.gov (United States)

    Hayashi, Ken-Ichi

    Medical applications of laser are measurement, laser surgery, in-situ monitoring, and processing of medical devices. In this paper, author briefly reviews the trends of medical applications, describes some new applications, and then discuss about the future trends and problems of medical applications. At present, the domestic market of laser equipment for medical applications is nearly 1/10 of that for industrial applications, which has registered significant growth continuously. Laser surgery as a minimum invasive surgery under arthroscope is expected to decrease the pain of patients. Precise processing such as cutting and welding is suitable for manufacturing medical devices. Pulsed laser deposition has been successfully applied to the thin film coating. The corneal refractive surgery by ArF excimer laser has been widely accepted for its highly safe operation. Laser ablation for retinal implant in the visual prosthesis is one of the promising applications of laser ablation in medicine. New applications with femtosecond laser are expected in the near future.

  9. Rainbow glare after laser-assisted in situ keratomileusis: a review of literature

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2016-11-01

    Full Text Available Majid Moshirfar,1,2 Jordan D Desautels,3 Tyler S Quist,4 David F Skanchy,5 Mark T Williams,6 Ryan T Wallace7 1Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, 2HDR Research Center, Hoopes Vision, Draper, UT, 3Tufts University School of Medicine, Boston, MA, 4University of Utah School of Medicine, Salt Lake City, UT, 5McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 6University of California, San Francisco School of Medicine, San Francisco, CA, 7Brigham Young University, Provo, UT, USA Abstract: This article reviews the current literature pertaining to rainbow glare (RG, including incidence rate, clinical presentation, etiology, prognosis, and management. RG is a rare optical complication of femtosecond laser-assisted in situ keratomileusis that results in patients seeing an array of spectral bands surrounding point sources of light under mesopic and scotopic conditions. The mechanism is thought to be a consequence of the formation of a transmissive diffraction grating on the posterior surface of the corneal flap created by the FS laser. RG has a good prognosis and is usually self-limiting. Persistent RG with concomitant residual refractive error may warrant lifting the flap and photoablating the posterior surface of the flap. Patients with persistent RG and no residual refractive error should be considered candidates for phototherapeutic keratectomy on the posterior flap surface. Keywords: rainbow glare, femtosecond, LASIK, keratomileusis, phototherapeutic keratectomy

  10. Temperature evolution on human teeth root surface after diode laser assisted endodontic treatment.

    Science.gov (United States)

    Gutknecht, Norbert; Franzen, Rene; Meister, Jörg; Vanweersch, Leon; Mir, Maziar

    2005-09-01

    The thermal rise threshold of an 810-nm semi-conductor diode laser on the root surface when used in root canals in vitro for laser assisted root canal treatment is investigated in this study. A total of 50 human single-rooted extracted teeth were included. For this study, the canals were enlarged up to an apical size of ISO#50 file. Laser irradiation was performed with six different settings. Specimens were irradiated at 0.6-1 W output power at the distal end of the fiber and about 1-1.5 W output power in the continuous mode (CW) as two groups. In the third group, 0.6-1 W output power, 10 ms pulse length (PL) and 10 ms interval duration (ID) were selected. In three other groups 1-1.5 W output power were used with different PL and ID as following: PL 10 and ID 10 ms, PL 10 and ID 20 ms and PL 20 and ID 20 ms. The total irradiation time was from 5 to 20 s per canal with a 200 mum in diameter and 25 mm long tip. After laser treatment, the temperature changes at the outer root surface were registered by means of NiCr-Ni measuring sensors and a T 202 thermometer. The safe temperature threshold for applying this diode laser in root canal is considered as 7 degrees C increase. To avoid increasing the temperature changes at the outer root surface related to this threshold, following total irradiation times were found: 0.6-1 W output power (10 ms PL/10 ms ID): 20 s (s), 1-1.5 W output power (10 ms/10 ms and 20 ms/20 ms): 15 s, 0.6-1 W output power CW and 1-1.5 W output power (20 ms PL/10 ms ID): 10 s and 1-1.5 W output power CW: 5 s. In the first three groups, 5 s irradiation and 5 s rest period avoided a temperature increase above the threshold of 7 degrees C).

  11. Opaque bubble layer incidence in Femtosecond laser-assisted LASIK: comparison among different flap design parameters.

    Science.gov (United States)

    Mastropasqua, Leonardo; Calienno, Roberta; Lanzini, Manuela; Salgari, Niccolò; De Vecchi, Sergio; Mastropasqua, Rodolfo; Nubile, Mario

    2017-06-01

    The purpose of this study was to evaluate the incidence of opaque bubble layer (OBL) in femtosecond laser-assisted in situ keratomileusis (LASIK) flaps created with the support of Visumax Carl Zeiss femtosecond laser, planned with different flap diameters (7.90, 8.0, and 8.20 mm) and the same laser energy and power settings. Incidence of intraoperative OBL in flaps of consecutive 108 patients (216 eyes) subjected to bilateral femtosecond-assisted LASIK was considered. Flap creation was performed with the same laser design parameters (spot distance and energy offset) and different presetting diameters of 7.90 mm (72 eyes, group 1), 8 mm (72 eyes, group 2), and 8.20 mm (72 eyes, group 3). The incidence of OBL was considered and its extension was reported measuring involvement of different four corneal flap quadrants in which was theoretically divided the entire flap area; based on these data, OBL presence was classified as none (no evidence of OBL), minimal (minimal presence in not more that one quadrants corneal flap), mild (OBL presence in almost two or three quadrants without tendency to invade central cornea), and moderate (OBL presence in almost three quadrants with tendency to invade central cornea). In group 1, the incidence of OBL was of 23.6 % (17 eyes) with a mild/moderate presence; in group 2, incidence was 20.8 % (15 eyes) with mild presence. Group 3 presented a reduced OBL incidence (4.1 %, 3 eye) with a minimal presence. No statistically significant difference was found between group 1 and 2 (p = 0.8414).We found statistically significant differences between group 1 and group 3 (p = 0.0012) and between groups 2 and 3 (p = 0.0044). A significant reduction and extension of OBL incidence were evident when LASIK flap settings diameter was increased, and flap edge was closer to the contact glass border; this is probably consequent to a more effective gas dispersion outside of corneal flap.

  12. Laser-assisted penetrating keratoplasty: 1-year results in patients using a laser-welded anvil-profiled graft.

    Science.gov (United States)

    Canovetti, Annalisa; Malandrini, Alex; Lenzetti, Ivo; Rossi, Francesca; Pini, Roberto; Menabuoni, Luca

    2014-10-01

    To describe a new laser-assisted penetrating keratoplasty technique combining a femtosecond anvil-like trephination pattern with the laser welding procedure. Cohort prospective study with 1 year of follow-up (June 2011 through January 2013). This study was performed at Misericordia e Dolce Public Hospital, Prato, Italy. Twenty-four eyes of 22 patients underwent penetrating keratoplasty: 4 had granular dystrophy, 12 had keratoconus in its final stages, 3 had post-herpetic leukoma, and 5 had corneal scars. A femtosecond laser was used to create anvil-profiled cuts in donor and recipient corneas. Diode laser welding was performed, supporting standard suturing. All patients were evaluated for corrected distance visual acuity, pachymetry, manifest astigmatism, and endothelial cell density after 1, 3, 6, and 12 months. Mean ± standard deviation postoperative corrected visual acuity was 0.48 ± 0.23 logarithm of the minimal angle of resolution (logMAR), 0.30 ± 0.18 logMAR, 0.18 ± 0.13 logMAR, and 0.13 ± 0.16 logMAR at 1, 3, 6, and 12 months, respectively. At the same follow-up times, mean pachymetry was 537 ± 57 μm, 533 ± 74 μm, 528 ± 72 μm, and 529 ± 58 μm, respectively; and mean endothelial cell density was 1945 ± 371 cells/mm(2), 1881 ± 410 cells/mm(2), 1781 ± 401 cells/mm(2), and 1730 ± 376 cells/mm(2), respectively. Mean manifest and topographic postoperative astigmatism were: 3.6 ± 2.5 diopters (D) and 4.65 ± 2.57 D at 1 month, 2.93 ± 2.34 D and 4.79 ± 2.85 D at 3 months, 2.82 ± 1.75 D and 3.44 ± 2.28 D at 6 months, and 2.08 ± 1.25 D and 2.73 ± 2.01 D at 12 months, respectively. All surgical operations were successful and without intraoperative complications. The use of the anvil trephination profile was effective for performing laser-assisted penetrating keratoplasty. The large donor-recipient interface enables the laser welding procedure and good preservation of the recipient's endothelial cell pool. Copyright © 2014 Elsevier Inc. All

  13. Comparison of femtosecond laser-assisted deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus.

    Science.gov (United States)

    Chen, Yueqin; Hu, Dan-Ning; Xia, Yuan; Yang, Liping; Xue, Chunyan; Huang, Zhenping

    2015-10-27

    To compare outcomes of femtosecond laser-assisted deep anterior lamellar keratoplasty (FSL-DALK) and penetrating keratoplasty (FSL-PK) for the treatment of keratoconus. Twenty eight eyes underwent FSL-DALK (consisted of 12 eyes in the FSL-DALKa subgroup without baring the Descemet's membrane and 16 eyes in the FSL-DALKb subgroup baring the Descemet's membrane using big-bubble technique) were compared with 12 eyes that underwent FSL-PK for keratoconus. These patients underwent an ophthalmic examination preoperatively and 3, 6, 9, and 12 months postoperatively. The postoperative BCVA in the FSL-PK group, and the FSL-DALKb subgroup were significantly better than that in the FSL-DALKa subgroup (P  0.05). There were no significant differences in the mean spherical equivalent (SE) and astigmatism between the FSL-DALK and the FSL-PK groups, nor between the subgroups of FSL-DALK during the follow-up period (P > 0.05). At the last follow-up, the mean endothelial cell loss in the FSL-DALK group (9.12 %) was significantly less than that in the FSL-PK group (20.79 %) (P < 0.001), while there was no difference between the FSL-DALKa (9.15 %) and the FSL-DALKb (9.10 %) subgroups (P = 0.15). The FSL-DALK group seemed to have fewer graft rejections (1/28 cases) than the FSL-PK group (2/12 cases), although Kaplan-Meier curve showed no significant difference between the two groups (P = 0.144). In this retrospective study, the results suggested that FSL-DALKb gives better visual outcome, and FSL-DALKb is a better option for keratoconus whose endothelium is not compromised. However, larger and prospective studies are further required.

  14. Comparison of femtosecond laser-assisted keratoplasty versus conventional penetrating keratoplasty.

    Science.gov (United States)

    Chamberlain, Winston D; Rush, Sloan W; Mathers, William D; Cabezas, Mauricio; Fraunfelder, Frederick W

    2011-03-01

    To compare postoperative outcomes for femtosecond laser-assisted keratoplasty (FLAK) with conventional penetrating keratoplasty (PK). Retrospective, comparative surgical series. Fifty consecutive patients who underwent FLAK and 50 case-controlled patients that had PK at the Casey Eye Institute (Oregon Health & Science University, Portland, OR). Data was collected for 50 consecutive cases that underwent zigzag incision FLAK and was compared with 50 subjects that had conventional blade trephine incision PK with similar age, diagnosis and concurrent ocular morbidities over a 2-year follow-up period. Topographic astigmatism, best spectacle-corrected visual acuity, uncorrected visual acuity, pinhole visual acuity, and the timing of selective suture removal (or adjustment) over various follow-up intervals up to 2 years postoperatively. Significantly lower topographic astigmatism was achieved in the FLAK group over the PK group in the 4- to 6-month follow-up period (P = 0.0324), which correlated well with significant earlier selective suture removal that occurred in that same group over both the 2- to 3-month (P = 0.0025) and 4- to 6-month (P = 0.0236) follow-up periods. This difference in astigmatism was no longer present at any other follow-up period up to 24 months postoperatively. The subset analysis of patients with keratoconus or post-LASIK ectasia did not show any difference in either astigmatism or visual acuity at any time. Compared with PKP, FLAK had significant improvement in astigmatism before but not after the 6 month postoperative follow-up period. Earlier suture removal was noted in the FLAK group. No significant improvement in best spectacle-corrected visual acuity was noted at any time point. There were no complications or difficulties with trephination in the FLAK procedure across a wide range of corneal pathologies. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  15. The nonocclusive laser-assisted coronary anastomotic connector in an off-pump porcine bypass model.

    Science.gov (United States)

    Stecher, David; van Slochteren, Frebus J; Hoefer, Imo E; Pasterkamp, Gerard; Tulleken, Cornelis A F; van Herwerden, Lex A; Buijsrogge, Marc P

    2014-04-01

    To facilitate minimally invasive coronary artery bypass grafting, a simplified alternative for hand-sutured anastomoses must be developed. We assessed the feasibility and anastomotic healing of the ameliorated Excimer laser-assisted nonocclusive anastomosis coronary prototype connector in an acute rabbit study (study 1) and in a long-term porcine off-pump coronary bypass study (study 2). Eighteen anastomoses were constructed on the abdominal aorta of the rabbit. In the porcine model, 15 left internal thoracic artery to left anterior descending coronary artery bypasses were evaluated intraoperatively and at 4 hours, 4 and 10 days, 2, 3, and 5 weeks, and 6 months (each n = 2 anastomoses). The anastomoses were examined by angiography, flow measurements, fractional flow reserve, coronary flow reserve, histologic features, and scanning electron microscopy. In study 1, all 18 anastomoses were patent and resisted supraphysiologic pressures (n = 12, 300 mm Hg). In study 2, the connector enabled nonocclusive and fast (7.7 ± 2.2 minutes, mean ± standard deviation) anastomosis construction. All but 1 of 15 anastomoses (owing to a technical error) were fully patent (FitzGibbon grade A) at follow-up. Histologic examination and scanning electron microscopy demonstrated complete endothelialization of the anastomoses at 10 days. At 6 months, no flow-limiting but streamline-covering intimal hyperplasia was shown (fractional flow reserve, 0.93 ± 0.07 mean ± standard deviation). The new nonocclusive coronary connector is easy to use, and the long-term results suggest favorable healing and remodeling in the porcine model. After downsizing, this anastomotic device, with its emphasis on zero ischemia and simplified prebounding of vessel walls, has intrinsic potential for minimally invasive off-pump coronary artery bypass surgery. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  16. Tailored surface-enhanced Raman nanopillar arrays fabricated by laser-assisted replication for biomolecular detection using organic semiconductor lasers.

    Science.gov (United States)

    Liu, Xin; Lebedkin, Sergei; Besser, Heino; Pfleging, Wilhelm; Prinz, Stephan; Wissmann, Markus; Schwab, Patrick M; Nazarenko, Irina; Guttmann, Markus; Kappes, Manfred M; Lemmer, Uli

    2015-01-27

    Organic semiconductor distributed feedback (DFB) lasers are of interest as external or chip-integrated excitation sources in the visible spectral range for miniaturized Raman-on-chip biomolecular detection systems. However, the inherently limited excitation power of such lasers as well as oftentimes low analyte concentrations requires efficient Raman detection schemes. We present an approach using surface-enhanced Raman scattering (SERS) substrates, which has the potential to significantly improve the sensitivity of on-chip Raman detection systems. Instead of lithographically fabricated Au/Ag-coated periodic nanostructures on Si/SiO2 wafers, which can provide large SERS enhancements but are expensive and time-consuming to fabricate, we use low-cost and large-area SERS substrates made via laser-assisted nanoreplication. These substrates comprise gold-coated cyclic olefin copolymer (COC) nanopillar arrays, which show an estimated SERS enhancement factor of up to ∼ 10(7). The effect of the nanopillar diameter (60-260 nm) and interpillar spacing (10-190 nm) on the local electromagnetic field enhancement is studied by finite-difference-time-domain (FDTD) modeling. The favorable SERS detection capability of this setup is verified by using rhodamine 6G and adenosine as analytes and an organic semiconductor DFB laser with an emission wavelength of 631.4 nm as the external fiber-coupled excitation source.

  17. Laser ablation studies of nanocomposites

    Directory of Open Access Journals (Sweden)

    Oleg V. Mkrtychev

    2015-03-01

    Full Text Available The first experimental measurements of the threshold energy density values for the laser ablation of glass nanocomposites with nanodimensional coatings have been carried out under the action of the YAG–Nd laser power pulse radiation. The coatings in question were of different compositions and had been created by the sol–gel technology. The procedure for determining the laser ablation threshold energy density values was worked out on the base of the breakdown probability level of 0.5. The statistical processing of the measurement data over all the samples allowed obtaining the dependence of the ablation destruction threshold energy parameters on the coating physical and chemical properties such as the sample transmission in the visible region of the spectrum, coating thickness, the chemical composition of the film-forming solution, and on the pulse duration of laser radiation.

  18. Femtosecond laser ablation of dentin

    Science.gov (United States)

    Alves, S.; Oliveira, V.; Vilar, R.

    2012-06-01

    The surface morphology, structure and composition of human dentin treated with a femtosecond infrared laser (pulse duration 500 fs, wavelength 1030 nm, fluences ranging from 1 to 3 J cm-2) was studied by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The average dentin ablation threshold under these conditions was 0.6 ± 0.2 J cm-2 and the ablation rate achieved in the range 1 to 2 µm/pulse for an average fluence of 3 J cm-2. The ablation surfaces present an irregular and rugged appearance, with no significant traces of melting, deformation, cracking or carbonization. The smear layer was entirely removed by the laser treatment. For fluences only slightly higher than the ablation threshold the morphology of the laser-treated surfaces was very similar to the dentin fracture surfaces and the dentinal tubules remained open. For higher fluences, the surface was more porous and the dentin structure was partially concealed by ablation debris and a few resolidified droplets. Independently on the laser processing parameters and laser processing method used no sub-superficial cracking was observed. The dentin constitution and chemical composition was not significantly modified by the laser treatment in the processing parameter range used. In particular, the organic matter is not preferentially removed from the surface and no traces of high temperature phosphates, such as the β-tricalcium phosphate, were observed. The achieved results are compatible with an electrostatic ablation mechanism. In conclusion, the high beam quality and short pulse duration of the ultrafast laser used should allow the accurate preparation of cavities, with negligible damage of the underlying material.

  19. LASIK ablation centration: an objective digitized assessment and comparison between two generations of an excimer laser.

    Science.gov (United States)

    Kanellopoulos, Anastasios John; Asimellis, George

    2015-03-01

    To objectively define the effective centration of myopic femtosecond laser-assisted LASIK ablation pattern, evaluate the difference between achieved versus planned excimer laser ablation centration, and compare these results from two different generations of an excimer laser system. The study retrospectively evaluated 280 eyes subjected to myopic LASIK. Digital image analysis was performed on Scheimpflug sagittal curvature maps (difference of preoperative to postoperative). Centration was assessed via proprietary software digital analysis of the coordinate displacement between the achieved ablation geometric center and the planned ablation center, which was the corneal vertex. Results from two different excimer laser generations (Eye-Q 400 [140 eyes] and EX500 [140 eyes]; Alcon/WaveLight, Fort Worth, TX) were compared. Radial displacement was on average 360 ± 220 µm (range: 0 to 1,030 µm) in the Eye-Q 400 laser group and 120 ± 110 µm (range: 0 to 580 µm) in the EX500 laser group (P laser group and 4% in the EX500 laser group. Displacement of ablation pattern may depend on the laser platform used. The improvement in the efficiency of centration indicates that newer generation excimer lasers with faster eye tracking and active centration control appear to achieve a significantly more accurate centration of myopic ablation patterns. The authors propose this novel, objective technique for laser refractive surgeon evaluation may point out significant outcome measures not currently used in standard metrics of refractive laser efficiency. Copyright 2015, SLACK Incorporated.

  20. Electrically stimulated osteogenesis on Ti-PPy/PLGA constructs prepared by laser-assisted processes.

    Science.gov (United States)

    Paun, Irina Alexandra; Stokker-Cheregi, Flavian; Luculescu, Catalin Romeo; Acasandrei, Adriana Maria; Ion, Valentin; Zamfirescu, Marian; Mustaciosu, Cosmin Catalin; Mihailescu, Mona; Dinescu, Maria

    2015-10-01

    This work describes a versatile laser-based protocol for fabricating micro-patterned, electrically conductive titanium-polypyrrole/poly(lactic-co-glycolic)acid (Ti-PPy/PLGA) constructs for electrically stimulated (ES) osteogenesis. Ti supports were patterned using fs laser ablation in order to create high spatial resolution microstructures meant to provide mechanical resistance and physical cues for cell growth. Matrix Assisted Pulsed Laser Evaporation (MAPLE) was used to coat the patterned Ti supports with PPy/PLGA layers acting as biocompatible surfaces having chemical and electrical properties suitable for cell differentiation and mineralization. In vitro biological assays on osteoblast-like MG63 cells showed that the constructs maintained cell viability without cytotoxicity. At 24 h after cell seeding, electrical stimulation with currents of 200 μA was applied for 4 h. This treatment was shown to promote earlier onset of osteogenesis. More specifically, the alkaline phosphatase activity of the stimulated cultures reached the maximum before that of the non-stimulated ones, i.e. controls, indicating faster cell differentiation. Moreover, mineralization was found to occur at an earlier stage in the stimulated cultures, as compared to the controls, starting with Day 6 of cell culture. At later stages, calcium levels in the stimulated cultures were higher than those in control samples by about 70%, with Ca/P ratios similar to those of natural bone. In all, the laser-based protocol emerges as an efficient alternative to existing fabrication technologies. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source.

    Science.gov (United States)

    Venkatesan, K

    2017-07-01

    Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60-150 m/min, feed rates of 0.05-0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

  2. The study on force, surface integrity, tool life and chip on laser assisted machining of inconel 718 using Nd:YAG laser source

    Directory of Open Access Journals (Sweden)

    K. Venkatesan

    2017-07-01

    Full Text Available Inconel 718, a high-temperature alloy, is a promising material for high-performance aerospace gas turbine engines components. However, the machining of the alloy is difficult owing to immense shear strength, rapid work hardening rate during turning, and less thermal conductivity. Hence, like ceramics and composites, the machining of this alloy is considered as difficult-to-turn materials. Laser assisted turning method has become a promising solution in recent years to lessen cutting stress when materials that are considered difficult-to-turn, such as Inconel 718 is employed. This study investigated the influence of input variables of laser assisted machining on the machinability aspect of the Inconel 718. The comparison of machining characteristics has been carried out to analyze the process benefits with the variation of laser machining variables. The laser assisted machining variables are cutting speeds of 60–150 m/min, feed rates of 0.05–0.125 mm/rev with a laser power between 1200 W and 1300 W. The various output characteristics such as force, roughness, tool life and geometrical characteristic of chip are investigated and compared with conventional machining without application of laser power. From experimental results, at a laser power of 1200 W, laser assisted turning outperforms conventional machining by 2.10 times lessening in cutting force, 46% reduction in surface roughness as well as 66% improvement in tool life when compared that of conventional machining. Compared to conventional machining, with the application of laser, the cutting speed of carbide tool has increased to a cutting condition of 150 m/min, 0.125 mm/rev. Microstructural analysis shows that no damage of the subsurface of the workpiece.

  3. Corneal biomechanical effects: small-incision lenticule extraction versus femtosecond laser-assisted laser in situ keratomileusis.

    Science.gov (United States)

    Wu, Di; Wang, Yan; Zhang, Lin; Wei, Shengsheng; Tang, Xin

    2014-06-01

    To compare the biomechanical properties of the cornea after small-incision lenticule extraction (lenticule extraction group) with those after femtosecond laser-assisted laser in situ keratomileusis (femtosecond LASIK group). Tianjin Eye Hospital & Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Medical University, Tianjin, China. Prospective comparative case series. Corneal hysteresis (CH), the corneal resistance factor (CRF), and 37 other biomechanical waveform parameters were quantitatively assessed with the Ocular Response Analyzer preoperatively and 1 week and 1, 3, and 6 months postoperatively. Each group comprised 40 eyes. The decrease in CH and the CRF was statistically significant 1 week postoperatively compared with preoperatively in both groups (Pcorneal thickness were statistically significant in the lenticule extraction group (r = 0.388 to 0.950, Pbiomechanical waveform parameters differed significantly between preoperative values and postoperative values (Pbiomechanical changes in the cornea. However, changes in the cornea's viscoelastic properties were less after lenticule extraction than after LASIK. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014. Published by Elsevier Inc.

  4. Effect of laser-assisted zona thinning, during assisted reproduction, on pregnancy outcome in women with endometriosis: randomized controlled trial.

    Science.gov (United States)

    Nada, Adel Mohamed; El-Noury, Amr; Al-Inany, Hesham; Bibars, Mamdouh; Taha, Tamer; Salama, Sameh; Hassan, Fatma; Zein, Eman

    2018-02-01

    To compare the ICSI-ET outcomes in patients with endometriosis with or without laser-assisted zona pellucida thinning. Randomized controlled trial. The study was conducted in the Obstetrics & Gynecology Department, Cairo University hospital, and two private IVF centers in Cairo & Beni-Suif from July 2015 to January 2017 upon infertile and known endometriosis patients who planned to do ICSI-ET. Before randomization, all patients received the same ovarian stimulation preparation, oocyte retrieval procedures, and the same intracytoplasmic sperm injection procedures. After randomization, laser-assisted hatching was performed only for embryos of 158 patients, while the other group (n = 150) no laser-assisted hatching was made. The verification of pregnancy was achieved by the serum hCG concentration 14 days after the embryo transfer, and the clinical pregnancy was confirmed 2 weeks later by the presence of gestational sac with pulsating fetal pole on vaginal ultrasonography. The main outcome measures were the clinical pregnancy rate and the clinical implantation rate. Both groups were comparable with regard their baseline characteristics, baseline hormonal profile, the ovarian stimulation characteristics, and the ovulation characteristics. The mean number of embryos developed per patient and the mean transferred number of embryos per patient were comparable between groups (p value > 0.05). The implantation rate was significantly higher (p value 0.002) in the study group than the control group with an odds ratio of 1.86 (CI 95% 1.24-2.80) and NNT 13.81 (CI 95% 8.35-39.94). The clinical pregnancy rate, was significantly (p value 0.022) higher in the study group than in the control group with an odds ratio of 1.79 (CI 95% 1.05-3.06) and NNT 9.57 (CI 95% 5.03-98.99). That laser-assisted hatching by thinning of the zona pellucida may be a suitable method to improve the ICSI-ET outcomes, in term of the implantation and the pregnancy rates, in cases of endometriosis. Pan

  5. Clinical study of two kinds of bandage contact lenses after laser-assisted subepithelial keratectomy

    Directory of Open Access Journals (Sweden)

    Wan-Ting Zhang

    2016-07-01

    Full Text Available AIM: To investigate the clinical safety and effectiveness of the two kind of bandage contact lenses: Senofilcon A(Johnson & Johnson Acuvue Oasysand Balafilcon A(Bausch& Lomb pure visionafter laser-assisted subepithelial keratectomy(LASEK. METHODS: Thirty-eight patients(76 eyeswho had undergone the LASEK were divided into two groups. One group of patients wore Balafilcon A, the other group of patients fitted with Senofilcon A. The lenses were worn continuously for 7d. This was a seven-day experience and the patients scored for the symptom of the eyes(sore eyes, foreign body sensation and tearingon the third day and the seventh day. Both of the two groups of patients taken off the soft contact lens on the seventh day and let their vision and corneal staining checked.RESULTS: The symptoms of eye sore and tearing of the two groups patients were different. The patients who wore the Senofilcon A were better. The pain of eyes were also different at 3 and 7d after surgeries(Z=-4.146, P=0.000; Z=-2.814, P=0.005. The difference on tearing between the two groups at 3 and 7d after surgeries were significant(Z=-2.309, P=0.021; Z=-3.276, P=0.001. There was no difference on sensation of dryness between the two groups at 3 and 7d after surgeries(Z=-0.447, P=0.655; Z=-0.966, P=0.334. After the lenses were taken off, the visual acuity of patients wearing Senofilcon A was better(t=3.800, P=0.001; corneal staining showed limited spots in 1-2 quadrants with significant difference(Z=-2.384,P=0.017. CONCLUSION: The Senofilcon A(Johnson & Johnson Acuvue Oasysand Balafilcon A(Bausch& Lomb pure visionbandage contact lenses are safe and effective after LASEK, and the former is better than the latter in epithelial regeneration.

  6. Outcomes of different laser types in laser-assisted stapedotomy: a systematic review

    NARCIS (Netherlands)

    Kamalski, D.M.A.; Wegner, I.; Tange, R.A.; Vincent, R.; Stegeman, I.; van der Heijden, G.J.M.; Grolman, W.

    2014-01-01

    OBJECTIVE: To assess hearing results and complications following primary stapedotomy in otosclerosis patients, comparing different laser types. DATA SOURCES: Pubmed, Embase, The Cochrane Library, CINAHL, and Scopus. STUDY SELECTION: A systematic bibliographic search was conducted to identify all

  7. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    of a variety of skin conditions, primarily chronically photodamaged skin, but also acne and burn scars. In addition, it is anticipated that AFR can be utilized in the laser-assisted delivery of topical drugs. Clinical efficacy coupled with minimal downtime has driven the development of various fractional...

  8. Effects of Femtosecond Laser-Assisted Cataract Pretreatment on Pupil Diameter: A Comparison Between Three Laser Platforms.

    Science.gov (United States)

    Diakonis, Vasilios F; Yesilirmak, Nilufer; Sayed-Ahmed, Ibrahim O; Warren, Daniel P; Kounis, George A; Davis, Zachary; Cabot, Florence; Yoo, Sonia H; O'Brien, Terrence P; Donaldson, Kendall E

    2016-02-01

    To assess pupil diameter before and after femtosecond laser-assisted cataract surgery (FLACS) pretreatment and compare the outcomes of three laser platforms. This prospective observational case series included consecutive patients scheduled to undergo cataract extraction using FLACS between August 2013 and February 2015. All eyes received FLACS pretreatment using three laser platforms: LenSx (Alcon Laboratories, Inc., Fort Worth, TX), Catalys (Abbott Medical Optics Inc., Santa Ana, CA), and Victus (Bausch & Lomb, Inc., Rochester, NY). The same protocol for preoperative medical mydriasis was used for all patients, and pupil diameter was assessed immediately before and 3 minutes after FLACS using a surgical ruler. A total of 198 eyes of 161 patients were included in the study. Mean pupillary miosis was 1.42 ± 1.26 mm for the LenSx, 0.66 ± 0.89 mm for the Catalys, and 0.14 ± 0.34 mm for the Victus groups. Furthermore, 8 of the 198 eyes (4.0%) demonstrated a pupil diameter of less than 5 mm after FLACS and 48 eyes (24.24%) demonstrated a pupil diameter of 6 mm or less. There was a statistically significant decrease in pupil diameter for all groups individually (P miosis, followed by Catalys, and finally Victus. A correlation between the pupil diameter before FLACS and degree of FLACS-induced miosis was demonstrated (P miosis. FLACS pretreatment seems to induce significant pupillary miosis with all laser platforms assessed in this study. The decrease in pupil diameter after FLACS reached clinical significance for cataract extraction (< 5 mm) in 4.0% of cases, whereas 20.2% of eyes demonstrated small pupil diameter (≤ 6 mm) after FLACS pretreatment. Copyright 2016, SLACK Incorporated.

  9. Learning curve of femtosecond laser-assisted cataract surgery: Experience of surgeons new to femtosecond laser platform

    Directory of Open Access Journals (Sweden)

    Josephine Susai Christy

    2017-01-01

    Full Text Available Purpose: The purpose of this study is to assess the learning curve in the initial 100 cases of cataract surgery performed using femtosecond laser-assisted cataract surgery (FLACS by experienced cataract surgeons without prior experience in femtosecond laser platform. Methods: This study was conducted at tertiary care eye hospital, South India. This was a prospective interventional study. The first 100 consecutive eyes undergoing FLACS were studied to understand docking time, number of docking attempts, problems encountered during docking, and complications attributable to docking. Phacoemulsification performed after femtosecond laser was also studied for complications, need for additional instrumentation, and total time required for surgery. Comparison was also made between two operating surgeons. Results: Successful docking was recorded in 70% eyes at the first attempt. Mean time taken for successful docking was 9.3 ± 6.4 min (median = 6 min, interquartile range (IQR = 5–10 min, range = 4–35 min. When surgeries were divided into quartiles, docking time reduced significantly from 16.2 ± 7.9 min in the first quartile to 6.2 ± 2.7 min in the fourth quartile (P < 0.001. Phacoemulsification postdocking required 12.9 ± 6.2 min (median = 10 min, IQR = 9–17.5 min. Six eyes showed anterior capsular tags, one had radial extension of capsulorhexis, and two eyes showed pupillary miosis after femtosecond laser application. At 6 weeks, 79% eyes attained uncorrected vision of 20/20, and all eyes had best-corrected vision of 20/20. Conclusion: Approximately 25–30 cases were required before obtaining reproducible results with FLACS, irrespective of cataract surgical experience, suggesting that training programs must offer a minimum 25 surgeries. Very few complications occurred during the learning curve, making it patient friendly.

  10. A Diode-Laser-System for Laser-Assisted Bending of Brittle Materials

    Directory of Open Access Journals (Sweden)

    F. Bammer

    2011-01-01

    Full Text Available We developed a small and compact system of diode lasers, which can be inserted into the lower tools of a bending press. The parts of the system allow easy plug and play operation and can be installed for any bending length. The diode laser, which is based on 200 W laser bars on microchannel cooler, allows the heating of sheet metals in the forming zone shortly before and during the bending process. There is no unnecessary heating of other parts of the bending equipment, no wear of the tool, and, if properly done, no damage of the surface of the metal. The power per bending length is 16 kW/m.

  11. Endometrial ablation

    Science.gov (United States)

    Hysteroscopy - endometrial ablation; Laser thermal ablation; Endometrial ablation - radiofrequency; Endometrial ablation - thermal balloon ablation; Rollerball ablation; Hydrothermal ablation; Novasure ...

  12. Fractional ablative erbium YAG laser

    DEFF Research Database (Denmark)

    Taudorf, Elisabeth H; Haak, Christina S; Erlendsson, Andrés M

    2014-01-01

    BACKGROUND AND OBJECTIVES: Treatment of a variety of skin disorders with ablative fractional lasers (AFXL) is driving the development of portable AFXLs. This study measures micropore dimensions produced by a small 2,940 nm AFXL using a variety of stacked pulses, and determines a model correlating...

  13. Femtosecond laser-assisted lamellar keratoplasty Transplante lamelar auxiliado pelo laser de fentosegundo

    Directory of Open Access Journals (Sweden)

    Hunson Kaz Soong

    2008-08-01

    Full Text Available Lamellar keratoplasty consists of transplanting partial-thickness donor cornea onto a complementary recipient bed. Manual lamellar dissection is technically very difficult, time-consuming, and imprecise. Also, the manually-dissected lamellar interface often has topographical irregularities that may optically degrade the best-corrected visual acuity. The femtosecond clinical laser (IntraLase FS LaserTM, Irvine, CA is a recent innovation that can be programmed to produce bladeless, precise lamellar cuts at any depth with accompanying trephination cuts for both anterior and posterior lamellar transplantion. Posterior laser cuts may be used to assist in deep lamellar endothelial keratoplasty or Descemet's stripping automated endothelial keratoplasty.A ceratoplastia lamelar consiste em transplante de espessura parcial da córnea doadora em um leito receptor complementar. A dissecção lamelar manual é técnica de difícil realização, imprecisa e que demanda tempo. Além disso, a interface lamelar freqüentemente apresenta irregularidade topográfica que pode comprometer a acuidade visual final. O laser clínico "femtosecond" (IntraLase FS LaserTM, Irvine, CA é uma recente inovação que pode ser utilizado para produzir cortes lamelares precisos em qualquer profundidade da córnea, acompanhados de cortes verticais tanto para transplantes lamelares anteriores como posteriores sem a utilização de lâminas. Os cortes posteriores podem ser utilizados para a realização de ceratoplastia endotelial lamelar profunda ou ceratoplastia endotelial com remoção da membrana de Descemet.

  14. Laser-assisted surgery of the upper aero-digestive tract: a clarification of nomenclature. A consensus statement of the European Laryngological Society

    NARCIS (Netherlands)

    Remacle, Marc; Arens, Christoph; Eldin, Mostafa Badr; Campos, Guillermo; Estomba, Carlos Chiesa; Dulguerov, Pavel; Fiz, Ivana; Hantzakos, Anastasios; Keghian, Jerôme; Mora, Francesco; Matar, Nayla; Peretti, Giorgio; Piazza, Cesare; Postma, Gregory N.; Prasad, Vyas; Sjogren, Elisabeth; Dikkers, Frederik G.

    2017-01-01

    Acronyms and abbreviations are frequently used in otorhinolaryngology and other medical specialties. CO2 laser-assisted transoral surgery of the pharynx, the larynx and the upper airway is a family of commonly performed surgical procedures termed transoral laser microsurgery (TLM). The abbreviation

  15. Laser assisted synthesis of carbon nanoparticles with controlled viscosities for printing applications.

    Science.gov (United States)

    Bagga, K; McCann, R; Wang, M; Stalcup, A; Vázquez, M; Brabazon, D

    2015-06-01

    High-quality carbon nanoparticles with controlled viscosity and high aqueous stability were prepared by liquid-phase laser ablation of a graphite target in deionized water. The size distribution was found to vary from 5nm to 50nm with mean size of 18nm, in the absence of any reducing chemical reagents. Efficient generation of short chain polyynes was recorded for high laser repetition rates. Homogeneous and stable nanoparticle suspensions with viscosities ranging from 0.89 to 12mPa.s were obtained by suspending the nanoparticles in different solvent mixtures such as glycerol-water and isopropanol-water. Optical properties were investigated by absorption and photoluminescence spectroscopy. Raman spectroscopy confirmed graphitic-like structure of nanoparticles and the surface chemistry was revealed by Fourier-transform infrared spectroscopy demonstrating sufficient electrostatic stabilization to avoid particle coagulation or flocculation. This paper present an exciting alternative method to engineer carbon nanoparticles and their potential use as a ligand-free nano-ink for ink jet printing (jetting) applications. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Care for the Critically Injured Burn Patient Modulation of Burn Scars Through Laser Assisted Delivery of Stem Cells

    Science.gov (United States)

    2016-10-01

    improvement (at both high and low laser energy settings) this was less noticeable than burns treated with Autologous BM-MSC in PEGylated gels. Photographs...measurement when Erbium:YAG laser is used at the high setting. A similar effect can be seen with CO2 laser . This is most likely is due to greater...hypertrophic third degree burn scars in Red Duroc pigs using ablative fractional CO2 or Erbium:YAG lasers . Epidermal and superficial dermal

  17. Evaluation of a transparent perfluorodecalin-infused patch as an adjunct to laser-assisted tattoo removal: A pivotal trial.

    Science.gov (United States)

    Biesman, Brian S; Costner, Cara

    2017-04-01

    Laser-assisted treatment of tattoos is well recognized to produce opaque epidermal whitening that prevents multiple sequential passes during a single treatment session. The amount of epidermal whitening produced in association with the procedure can be minimized by topical application of perfluorodecalin (PFD), which is an optical clearing agent. This pivotal trial assessed the ability of a transparent PFD-infused patch used in conjunction with a Q-switched nanosecond laser in the treatment of tattoos to permit multiple laser passes during a single 5 minute treatment session in comparison to the number of passes that could be completed using conventional treatment of the tattoo with the laser alone. Thirty subjects (mean age 37 years; 14 males) with predominantly dark blue or black tattoos were enrolled in a split-tattoo trial. One half of each tattoo was treated conventionally, whereas the other half was treated through the PFD patch. Treatments were performed using a nanosecond Q-switched 755-nm Alexandrite laser. The number of treatments performed in a 5-minute time period was quantified for each side of the tattoo (primary effectiveness outcome). Patient-reported pain scores and adverse events (AEs) were also evaluated. Significantly more laser passes could be made on average using the PFD patch compared with treatment using the laser alone (3.7 passes vs. 1.4 passes; P tattoos. The proportions of subjects with transient edema and erythema were lower in the PFD patch treatment group (36.7% vs. 63.3% and 33.3% vs. 70.0%, respectively); all AEs were transient and resolved quickly. No patient in either group exhibited dyschromia (hypo- or hyperpigmentation) in the treatment area at the 1-month post treatment visit. Additionally, when surveyed at the 1-month follow-up visit, all subjects (30/30) preferred to continue laser-assisted tattoo removal with the PFD patch. An average of 3.7 laser passes were made in a defined 5-minute treatment session when using the

  18. Vitreoretinal surgery for bilateral macular holes after laser-assisted in situ keratomileusis for the correction of myopia: a case report

    Directory of Open Access Journals (Sweden)

    García-Fernández Miriam

    2012-11-01

    Full Text Available Abstract Introduction Laser-assisted in situ keratomileusis surgery may induce postoperative changes in the vitreomacular interface due to the mechanical stretch of the vitreous produced by the suction ring and the shock waves generated by the excimer laser and, subsequently, may provoke macular hole formation. Case presentation A 53-year-old Spanish woman who had undergone a laser-assisted in situ keratomileusis for the correction of myopia in her right and left eye (10 years ago was referred to our department with a complaint of decreased visual acuity in both eyes. A fundoscopy and optical coherence tomography examination revealed a bilateral full-thickness macular hole. A 23-gauge sutureless pars plana vitrectomy was performed in both eyes, and 1 month after surgery her visual acuity improved and the hole closed. Conclusion The development of a bilateral full-thickness macular hole after laser-assisted in situ keratomileusis has been reported once. This case study enhances our understanding of the vitreoretinal pathology induced by laser-assisted in situ keratomileusis, showing the importance of a rigorous follow-up, because complications may occur even a decade later. In this case study we must also consider the contribution of the underlying myopia to the development of the bilateral macular holes.

  19. Investigation of excimer laser ablation of iron

    Science.gov (United States)

    Jordan, R.; Lunney, J. G.

    1998-05-01

    The excimer ablation of iron at 248 nm has been investigated by measuring the ablation depth and average ion energy as a function of laser fluence. Measurements have also been made of the laser transmission through the ablated vapour above the target. The absolute spectral intensity of the emission from the ablation plasma has been measured in both the vacuum ultraviolet and the visible. All results were compared with a simple numerical model describing the main physical processes involved in laser ablation of metal targets.

  20. A procedure for calibration and validation of FE modelling of laser-assisted metal to polymer direct joining

    Science.gov (United States)

    Lambiase, F.; Genna, S.; Kant, R.

    2018-01-01

    The quality of the joints produced by means of Laser-Assisted Metal to Polymer direct joining (LAMP) is strongly influenced by the temperature field produced during the laser treatment. The main phenomena including the adhesion of the plastic to the metal sheet and the development of bubbles (on the plastic surface) depend on the temperature reached by the polymer at the interface. Such a temperature should be higher than the softening temperature, but lower than the degradation temperature of the polymer. However, the temperature distribution is difficult to be measured by experimental tests since the most polymers (which are transparent to the laser radiation) are often opaque to the infrared wavelength. Thus, infrared analysis involving pyrometers and infrared camera is not suitable for this purpose. On the other hand, thermocouples are difficult to be placed at the interface without influencing the temperature conditions. In this paper, an integrated approach involving both experimental measurements and a Finite Element (FE) model were used to perform such an analysis. LAMP of Polycarbonate and AISI304 stainless steel was performed by means of high power diode laser and the main process parameters i.e. laser power and scanning speed were varied. Comparing the experimental measurements and the FE model prediction of the thermal field, a good correspondence was achieved proving the suitability of the developed model and the proposed calibration procedure to be ready used for process design and optimization.

  1. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-06-01

    Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

  2. Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction.

    Directory of Open Access Journals (Sweden)

    Andri K Riau

    Full Text Available LASIK (laser-assisted in situ keratomileusis is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap. Correction of refractive error is achieved by the resulting change in the curvature of the cornea and is limited by central corneal thickness, as a thin residual stromal bed may result in biomechanical instability of the cornea. A recently developed alternative to LASIK called Refractive Lenticule Extraction (ReLEx utilizes solely a femtosecond laser (FSL to incise an intrastromal refractive lenticule (RL, which results in reshaping the corneal curvature and correcting the myopia and/or astigmatism. As the RL is extracted intact in the ReLEx, we hypothesized that it could be cryopreserved and re-implanted at a later date to restore corneal stromal volume, in the event of keratectasia, making ReLEx a potentially reversible procedure, unlike LASIK. In this study, we re-implanted cryopreserved RLs in a non-human primate model of ReLEx. Mild intrastromal haze, noted during the first 2 weeks after re-implantation, subsided after 8 weeks. Refractive parameters including corneal thickness, anterior curvature and refractive error indices were restored to near pre-operative values after the re-implantation. Immunohistochemistry revealed no myofibroblast formation or abnormal collagen type I expression after 8 weeks, and a significant attenuation of fibronectin and tenascin expression from week 8 to 16 after re-implantation. In addition, keratocyte re-population could be found along the implanted RL interfaces. Our findings suggest that RL cryopreservation and re-implantation after ReLEx appears feasible, suggesting the possibility of potential reversibility of the procedure, and possible future uses of RLs in treating other corneal disorders and refractive errors.

  3. Precise ablation of dental hard tissues with ultra-short pulsed lasers. Preliminary exploratory investigation on adequate laser parameters.

    Science.gov (United States)

    Bello-Silva, Marina Stella; Wehner, Martin; Eduardo, Carlos de Paula; Lampert, Friedrich; Poprawe, Reinhart; Hermans, Martin; Esteves-Oliveira, Marcella

    2013-01-01

    This study aimed to evaluate the possibility of introducing ultra-short pulsed lasers (USPL) in restorative dentistry by maintaining the well-known benefits of lasers for caries removal, but also overcoming disadvantages, such as thermal damage of irradiated substrate. USPL ablation of dental hard tissues was investigated in two phases. Phase 1--different wavelengths (355, 532, 1,045, and 1,064 nm), pulse durations (picoseconds and femtoseconds) and irradiation parameters (scanning speed, output power, and pulse repetition rate) were assessed for enamel and dentin. Ablation rate was determined, and the temperature increase measured in real time. Phase 2--the most favorable laser parameters were evaluated to correlate temperature increase to ablation rate and ablation efficiency. The influence of cooling methods (air, air-water spray) on ablation process was further analyzed. All parameters tested provided precise and selective tissue ablation. For all lasers, faster scanning speeds resulted in better interaction and reduced temperature increase. The most adequate results were observed for the 1064-nm ps-laser and the 1045-nm fs-laser. Forced cooling caused moderate changes in temperature increase, but reduced ablation, being considered unnecessary during irradiation with USPL. For dentin, the correlation between temperature increase and ablation efficiency was satisfactory for both pulse durations, while for enamel, the best correlation was observed for fs-laser, independently of the power used. USPL may be suitable for cavity preparation in dentin and enamel, since effective ablation and low temperature increase were observed. If adequate laser parameters are selected, this technique seems to be promising for promoting the laser-assisted, minimally invasive approach.

  4. Ex vivo proof-of-concept of end-to-end scaffold-enhanced laser-assisted vascular anastomosis of porcine arteries

    NARCIS (Netherlands)

    Pabittei, Dara R.; Heger, Michal; van Tuijl, Sjoerd; Simonet, Marc; de Boon, Wadim; van der Wal, Allard C.; Balm, Ron; de Mol, Bas A.

    2015-01-01

    The low welding strength of laser-assisted vascular anastomosis (LAVA) has hampered the clinical application of LAVA as an alternative to suture anastomosis. To improve welding strength, LAVA in combination with solder and polymeric scaffolds (ssLAVA) has been optimized in vitro. Currently, ssLAVA

  5. In situ printing of mesenchymal stromal cells, by laser-assisted bioprinting, for in vivo bone regeneration applications.

    Science.gov (United States)

    Keriquel, Virginie; Oliveira, Hugo; Rémy, Murielle; Ziane, Sophia; Delmond, Samantha; Rousseau, Benoit; Rey, Sylvie; Catros, Sylvain; Amédée, Joelle; Guillemot, Fabien; Fricain, Jean-Christophe

    2017-05-11

    Bioprinting has emerged as a novel technological approach with the potential to address unsolved questions in the field of tissue engineering. We have recently shown that Laser Assisted Bioprinting (LAB), due to its unprecedented cell printing resolution and precision, is an attractive tool for the in situ printing of a bone substitute. Here, we show that LAB can be used for the in situ printing of mesenchymal stromal cells, associated with collagen and nano-hydroxyapatite, in order to favor bone regeneration, in a calvaria defect model in mice. Also, by testing different cell printing geometries, we show that different cellular arrangements impact on bone tissue regeneration. This work opens new avenues on the development of novel strategies, using in situ bioprinting, for the building of tissues, from the ground up.

  6. Studies on laser-assisted Penning ionization by the optogalvanic effect in Ne/Eu hollow cathode discharge.

    Science.gov (United States)

    Saini, V K; Kumar, P; Dixit, S K; Nakhe, S V

    2015-02-01

    Laser-assisted Penning ionization (LAPI) is detected in a Ne/Eu hollow cathode (HC) discharge lamp using the pulsed optogalvanic (OG) method. In the Ne/Eu discharge, doubly ionized europium excited energy levels Eu[4f(7)(P(7/2,5/2)6)] lie within the thermal limit (∼kT) from the laser-excited neon's energy level [2p(5)(P3/202)3p or 2p(8) (in Paschen notation)] lying at 149,848  cm(-1). Therefore, Penning ionization (PI) of europium atoms likely to occur into its highly excited ionic states is investigated. To probe the PI of europium, the temporal profiles of its counterpart neon OG signal are studied as a function of discharge current for the transitions (1s(4)→2p(8)) and (1s(2)→2p(2)), corresponding to 650.65 and 659.89 nm wavelengths, respectively. It is observed that PI of europium alters the overall discharge characteristics significantly and, hence, modifies the temporal profile of the OG signals accordingly. The quasi-resonant ionizing energy transfer collisions between laser-excited Ne 2p(8) atoms and electronically excited europium P(9/2)10 atoms are used to explain the LAPI mechanism. Such LAPI studies carried out in HC discharge could be useful for the discharge of a metal-vapor laser with appropriate Penning mixtures.

  7. Formation of plano-convex micro-lens array in fused silica glass using CO2 laser assisted reshaping technique

    CERN Document Server

    Sohn, Ik-Bu; Yoo, Dongyoon; Noh, Young-Chul; Ahsan, Md Shamim; Sung, Jae-Hee; Lee, Seong-Ku

    2016-01-01

    We report on fabricating high-fill-factor plano-convex spherical and square micro-lens arrays on fused silica glass surface using CO2 laser assisted reshaping technique. Initially, periodic micro-pillars have been encoded on the glass surface by means of a femtosecond laser beam. Afterwards, the micro-pillars are polished several times by irradiating a CO2 laser beam on top of the micro-pillars. Consequently, spherical micro-lens array with micro-lens size of 50 um x 50 um and square micro-lens array with micro-lens size of 100 um x 100 um are formed on fused silica glass surface. We also study the intensity distribution of light passed through the spherical micro-lens array engraved glass sample. The simulation result shows that, the focal length of the spherical micro-lens array is 35 um. Furthermore, we investigate the optical properties of the micro-lens array engraved glass samples. The proposed CO2 laser based reshaping technique is simple and fast that shows promises in fabrication arrays of smooth mic...

  8. Femtosecond Laser Ablation: Fundamentals and Applications

    Science.gov (United States)

    Harilal, Sivanandan S.; Freeman, Justin R.; Diwakar, Prasoon K.; Hassanein, Ahmed

    Traditionally nanosecond laser pulses have been used for Laser-induced Breakdown Spectroscopy (LIBS) for quantitative and qualitative analysis of the samples. Laser produced plasmas using nanosecond laser pulses have been studied extensively since 1960s. With the advent of short and ultrashort laser pulses, there has been a growing interest in the applications of femtosecond and picosecond lasers for analysis of materials using LIBS and LA-ICP-MS. The fundamentals of laser ablation process using ultrashort laser pulses are not still fully understood. Pulse duration of femtosecond laser pulse is shorter than electron-to-ion energy transfer time and heat conduction time in the sample lattice. This results in different laser ablation and heat dissipation mechanisms as compared to nanosecond laser ablation. In this chapter, the focus will be on understanding the basics of femtosecond laser ablation processes including laser target interaction, ablation efficiency, ablation threshold, laser plasma interactions, and plume hydrodynamics. Analytical figures of merit will be discussed in contrast to nanosecond LIBS.

  9. Spectrophotometric analysis of the effectiveness of a novel in-office laser-assisted tooth bleaching method using Er,Cr:YSGG laser.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Strakas, Dimitrios; Tolidis, Kosmas; Tsitrou, Effrosyni; Koumpia, Effimia; Koliniotou-Koumpia, Eugenia

    2017-11-01

    The purpose of this in vitro study was to compare the effectiveness of a novel Er,Cr:YSGG laser-assisted in-office tooth bleaching method with a conventional method by spectrophotometric analysis of the tooth color change. Furthermore, the influence of the application time of the bleaching gel on the effectiveness of the methods and the maintenance of the results 7 days and 1 month after the treatments were also evaluated. Twenty-four bovine incisors were stained and randomly distributed into four groups. Group 1 specimens received an in-office bleaching treatment with 35% H2O2 for 2 × 15 min. Group 2 specimens received the same treatment but with extended application time (2 × 20 min). In Group 3, the same in-office bleaching procedure (2 × 15 min) was carried out as that in Group 1, using Er,Cr:YSGG laser irradiation for 2 × 15 s on each specimen to catalyze the reaction of H2O2 breakdown. Group 4 specimens received the same bleaching treatment as Group 3 but with extended application time (2 × 20 min). Er,Cr:YSGG laser-assisted tooth bleaching treatment is more effective than the conventional treatment regarding color change of the teeth. Application time of the bleaching agent may influence the effectiveness of the methods. The color change of the tested treatments decreases after 7 days and 1 month. The clinical relevance of this study is that this novel laser-assisted bleaching treatment may be more advantageous in color change and application time compared to the conventional bleaching treatment.

  10. Laser-induced back-ablation of aluminum thin films using picosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK, A B

    1999-05-26

    Experiments were performed to understand laser-induced back-ablation of Al film targets with picosecond laser pulses. Al films deposited on the back surface of BK-7 substrates are ablated by picosecond laser pulses propagating into the Al film through the substrate. The ablated Al plume is transversely probed by a time-delayed, two-color sub-picoseond (500 fs) pulse, and this probe is then used to produce self-referencing interferograms and shadowgraphs of the Al plume in flight. Optical emission from the Al target due to LIBA is directed into a time-integrated grating spectrometer, and a time-integrating CCD camera records images of the Al plume emission. Ablated Al plumes are also redeposited on to receiving substrates. A post-experimental study of the Al target and recollected deposit characteristics was also done using optical microscopy, interferometry, and profilometry. In this high laser intensity regime, laser-induced substrate ionization and damage strongly limits transmitted laser fluence through the substrate above a threshold fluence. The threshold fluence for this ionization-based transmission limit in the substrate is dependent on the duration of the incident pulse. The substrate ionization can be used as a dynamic control of both transmitted spatial pulse profile and ablated Al plume shape. The efficiency of laser energy transfer between the laser pulse incident on the Al film and the ablated Al plume is estimated to be of order 5% and is a weak function of laser pulsewidth. The Al plume is highly directed. Low plume divergence ({theta}{sub divergence} < 5{sup o}) shows the ablated plume temperature to be very low at long time delays ( T << 0.5 eV at delays of 255 ns). Spectroscopic observations and calculations indicate that, in early time (t < 100 ps), the Al film region near the substrate/metal interface is at temperatures of order 0.5 eV. Interferograms of Al plumes produced with 0.1 {micro}m films show these plumes to be of high neutral atom

  11. Optimization of Suture-Free Laser-Assisted Vessel Repair by Solder-Doped Electrospun Poly(ε-caprolactone) Scaffold

    Science.gov (United States)

    Pabittei, Dara R.; Heger, Michal; Beek, Johan F.; van Tuijl, Sjoerd; Simonet, Marc; van der Wal, Allard C.; de Mol, Bas A.

    2010-01-01

    Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484 ± 111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR. PMID:20835847

  12. A novel approach to brachycephalic syndrome. 3. Isolated laser-assisted turbinectomy of caudal aberrant turbinates (CAT LATE).

    Science.gov (United States)

    Schuenemann, Riccarda; Pohl, Sabine; Oechtering, Gerhard U

    2017-01-01

    To describe isolated laser-assisted turbinectomy of caudal aberrant turbinates (CAT LATE) as a new minimally invasive surgical procedure for the treatment of brachycephalic dogs with obstructing caudal aberrant turbinates (CAT). Prospective clinical study. Brachycephalic dogs (24 Pugs, 1 English Bulldog) with CAT but adequate air spaces between the lamellae of the nonobstructing ventral nasal concha. A rhinoscopically guided diode laser fiber introduced from anterior was used to dissect CAT within the nasopharyngeal meatus, while leaving the intranasal turbinates intact. Small grasping forceps were used to extract the dissected CAT from anterior or to push it through the nasopharyngeal meatus for extraction from posterior. Isolated CAT LATE was successfully performed on 32 CAT in 25 dogs. Intranasally applied xylometazoline helped shrink the ventral concha, making the approach and extraction easier. Minor bleeding was the only complication observed. It is possible to remove CAT with endoscopically applied diode-laser energy while leaving the nonobstructing ventral nasal concha intact. © 2017 The American College of Veterinary Surgeons.

  13. Objective Evaluation of Planned Versus Achieved Stromal Thickness Reduction in Myopic Femtosecond Laser-assisted LASIK.

    Science.gov (United States)

    Kanellopoulos, Anastasios John; Georgiadou, Stella; Asimellis, George

    2015-09-01

    To evaluate corneal stromal thickness reduction and compare to attempted and achieved ablation depth in a consecutive case series study of myopic LASIK. Stromal thickness reduction was retrospectively evaluated in 205 consecutive eyes of 205 patients undergoing myopic and myopic astigmatic LASIK. Anterior segment optical coherence tomography was performed preoperatively and 3 months postoperatively. Epithelial thickness remodeling was also accounted for to achieve objective stromal thickness reduction. The derived maximum stromal thickness reduction was then compared to the programmed (planned) maximum ablation depth. Deviation of planned versus achieved maximum stromal thickness changes was correlated with residual refractive error. The 3-month stromal reduction was 86.01 ± 28.28 µm, compared to the average programmed maximum ablation depth of 88.48 ± 26.05 µm. The attempted versus achieved thickness outliers correlated with deviations in achieved refractive correction. Actual objective stromal thickness reduction following myopic LASIK correlates well with the attempted versus achieved refractive change. Copyright 2015, SLACK Incorporated.

  14. Corneal Clarity and Visual Outcomes after Small-Incision Lenticule Extraction and Comparison to Femtosecond Laser-Assisted In Situ Keratomileusis.

    Science.gov (United States)

    Lazaridis, Apostolos; Droutsas, Konstantinos; Sekundo, Walter; Petrak, Michael; Schulze, Stephan

    2017-01-01

    Purpose. To evaluate corneal clarity and visual outcomes after small-incision lenticule extraction (SMILE) and compare them to femtosecond laser-assisted in situ keratomileusis (FS-LASIK). Materials and Methods. Fifty-eight myopic eyes of 33 patients who underwent SMILE were compared to 58 eyes of 33 patients treated with FS-LASIK. All procedures were performed using VisuMax® femtosecond laser and MEL 80® excimer laser (Carl Zeiss Meditec AG, Germany). Pentacam™ (Oculus, Germany) was used for pre- and 3-month postoperative corneal densitometry (CD) analysis. CD was evaluated at 3 optically relevant, concentric radial zones (0-2 mm, 2-6 mm, and 0-6 mm annulus) around the corneal apex and at 3 different anatomical corneal layers (anterior, central, and posterior). Associations of postoperative CD values with the lenticule thickness and ablation depth were examined. Preoperative and postoperative corrected distance visual acuity (CDVA) values were also compared. Results. After SMILE, the total CD (all corneal layers) at 0-6 mm annulus showed no significant change compared to preoperative values (P = 0.259). After FS-LASIK, the total CD was significantly reduced (P = 0.033). Three-month postoperative CD showed no significant differences between the 2 groups for all examined annuli (0-2 mm: P = 0.569; 2-6 mm: P = 0.055; and 0-6 mm: P = 0.686). Total CD after SMILE at 0-6 mm annulus displayed a weak negative association with the lenticule thickness (P = 0.079, R2 = 0.0532) and after FS-LASIK displayed a weak negative association with the ablation depth (P = 0.731, R2 = 0.0015). Postoperative CDVA was similar for both groups (P = 0.517). Conclusion. Quantification of corneal clarity using the Scheimpflug CD showed similar results before and 3 months after SMILE. Compared to FS-LASIK, no significant differences of corneal clarity and CDVA were found 3 months postoperatively.

  15. Applications of laser ablation to microengineering

    Science.gov (United States)

    Gower, Malcolm C.; Rizvi, Nadeem H.

    2000-08-01

    Applications of pulsed laser ablation to the manufacture of micro- electro-mechanical systems (MEMS) and micro-opto-electro-mechanical systems (MOEMS) devices are presented. Laser ablative processes used to manufacture a variety of microsystems technology (MST) components in the computer peripheral, sensing and biomedical industries are described together with a view of some future developments.

  16. Experimental and numerical investigation on laser-assisted bending of pre-loaded metal plate

    Science.gov (United States)

    Nowak, Zdzisław; Nowak, Marcin; Widłaszewski, Jacek; Kurp, Piotr

    2018-01-01

    The laser forming technique has an important disadvantage, which is the limitation of plastic deformation generated by a single laser beam pass. To increase the plastic deformation it is possible to apply external forces in the laser forming process. In this paper, we investigate the influence of external pre-loads on the laser bending of steel plate. The pre-loads investigated generate bending towards the laser beam. The thermal, elastic-plastic analysis is performed using the commercial nonlinear finite element analysis package ABAQUS. The focus of the paper is to identify how this pattern of the pre-load influence the final bend angle of the plate.

  17. Effects of topical ketorolac tromethamine 0.45% on intraoperative miosis and prostaglandin E2 release during femtosecond laser-assisted cataract surgery.

    Science.gov (United States)

    Jun, Jong Hwa; Yoo, Young-Sik; Lim, Sung A; Joo, Choun-Ki

    2017-04-01

    To determine the effects of topical 0.45% ketorolac tromethamine on intraoperative miosis and prostaglandin E2 (PGE2) release during femtosecond laser-assisted cataract surgery. Seoul St. Mary's Hospital, Seoul, Korea. Prospective case series. The study comprised the following 3 groups: conventional cataract surgery without topical NSAIDs (conventional group); femtosecond laser-assisted cataract surgery with preoperative topical ketorolac tromethamine 0.45% (femtosecond NSAID group), and femtosecond laser-assisted cataract surgery without topical NSAIDs (femtosecond no-NSAID group). To measure the aqueous humor PGE2 concentration, a 100 μL aqueous humor sample was collected from the anterior chamber after femtosecond laser pretreatment. The PGE2 concentration was measured using an enzyme immunoassay. Topical ketorolac tromethamine 0.45% led to a significant reduction in intraoperative miosis in the femtosecond NSAID group compared with the femtosecond no-NSAID group (P  .05, conventional versus femtosecond NSAID). Preoperative topical ketorolac tromethamine 0.45% reduced miosis induced by femtosecond laser pretreatment and inhibited aqueous humor PGE2 elevation. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  18. Statistically Guided Development of Laser-Assisted Cold Spray for Microstructural Control of Ti-6Al-4V

    Science.gov (United States)

    Birt, Aaron M.; Champagne, Victor K.; Sisson, Richard D.; Apelian, Diran

    2017-04-01

    Laser-assisted cold spray (LACS) was used to deposit Ti-6Al-4V powders onto Ti-6Al-4V substrates using nitrogen as a carrier gas. An L25 orthogonal array was created with three parameters independent of particle velocity considered thus to be the independent thermal parameters (ITPs) of LACS: powder feed rate, raster speed, and laser power. A signal-to-noise analysis of the influence of the ITPs on porosity, microhardness, and expected thickness was performed revealing that optimum parameter selection is highly dependent on the targeted property, with the ITPs having the largest influence on porosity. Additional bulk trials (>2.5 mm thick) were deposited using parameters of interest from the orthogonal study. These scaled trials demonstrate that it is possible to produce deposits of Ti-6Al-4V via LACS using nitrogen as a carrier gas with porosity less than 1 pct, which is comparable with values described in literature for more expensive helium-based cold spray of Ti-6Al-4V. Additionally, variation of the ITPs indicates that secondary phases and morphologies can be produced and controlled through the thermomechanical treatment caused in situ to LACS.

  19. The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel.

    Science.gov (United States)

    Ahrari, Farzaneh; Akbari, Majid; Mohammadpour, Sakineh; Forghani, Maryam

    2015-12-30

    This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. There were significant differences in the color change between T2 and T3 (ΔE T2-T3) and T2 and T4 (ΔE T2-T4) stages among the study groups (poffice bleaching (group 1) as compared to the other groups (Poffice bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth.

  20. Laser-assisted subepithelial keratectomy (LASEK) versus photorefractive keratectomy (PRK) for correction of myopia.

    Science.gov (United States)

    Li, Shi-Ming; Zhan, Siyan; Li, Si-Yuan; Peng, Xiao-Xia; Hu, Jing; Law, Hua Andrew; Wang, Ning-Li

    2016-02-22

    Myopia (near-sightedness or short-sightedness) is a condition in which the refractive power of the eye is greater than required. The most frequent complaint of people with myopia is blurred distance vision, which can be eliminated by conventional optical aids such as spectacles or contact lenses, or by refractive surgery procedures such as photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). PRK uses laser to remove the corneal stroma. Similar to PRK, LASEK first creates an epithelial flap and then replaces it after ablating the corneal stroma. The relative benefits and harms of LASEK and PRK, as shown in different trials, warrant a systematic review. The objective of this review is to compare LASEK versus PRK for correction of myopia by evaluating their efficacy and safety in terms of postoperative uncorrected visual acuity, residual refractive error, and associated complications. We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2015 Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2015), EMBASE (January 1980 to December 2015), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to December 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 December 2015. We used the Science Citation Index and searched the reference lists of the included trials to identify relevant trials for this review. We included in this review randomized controlled trials (RCTs) comparing LASEK versus PRK for correction of myopia. Trial participants were 18 years of age or older and had no co

  1. Laser-assisted electron capture and emission in slow proton-hydrogen collisions.

    Science.gov (United States)

    Niederhausen, Thomas; Feuerstein, Bernold; Thumm, Uwe

    2004-03-01

    We investigate the effects of a strong laser field on the dynamics of ion-atom collisions by solving the time-dependent Schrödinger equation (TDSE) on a numerical grid for a 2D (reduced dimensionality) and a full 3D model of the scattering system. In the 2D model the electron system is confined to the two dimensions of the scattering plane, which also includes the laser electric field vector. This allows us to study the influence of the laser intensity and polarization (linear, circular, elliptic) on the capture and ionization probabilities for a large number of collision and laser parameters. After intergrating over impact parameters of the classical projectile trajectory and after averagering over the relative phase between the laser electric field and the collision, we find for intensities above 10^13 W/cm^2 noticeable laser electric field effects and circular dichroism in the capture probability.

  2. Laser-assisted formation of micropores and nanobubbles in sclera promote stable normalization of intraocular pressure

    Science.gov (United States)

    Baum, Olga; Wachsmann-Hogiu, Sebastian; Milner, Thomas; Sobol, Emil

    2017-06-01

    Pores in sclera enhance uveoscleral water outflow and can normalize intraocular pressure in glaucomatous eyes. The aims of this study are to demonstrate laser-induced formation of pores with a dendritic structure and to answer the questions: How is a pore system stable and can laser treatment provide a long-lasting pressure stabilization effect? Effect of 1.56 µm laser radiation on porcine eye sclera was studied using atomic force microscopy and super resolution structured irradiation microscopy with fluorescent markers. Results suggest that the pores with a complex spatial configuration can arise as a result of laser irradiation and that laser-generated stable gas nanobubbles coated with calcium ions allow pore stabilization in the sclera. Our results support a laser based approach for treatment of glaucoma.

  3. Laser Assisted Crystallization of Ferromagnetic Amorphous Ribbons: A Multimodal Characterization and Thermal Model Study

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana K.; Devaraj, Arun; Bowden, Mark E.; Santhanakrishnan, S.; Smith, Casey; Ramanujan, Raju; Thevuthasan, Suntharampillai; Banerjee, Rajarshi; Dahotre, Narendra B.

    2013-11-14

    This paper focuses on laser-based de-vitrification of amorphous soft magnetic Fe-Si-B ribbons and its consequent influence on the magnetic properties. Laser processing resulted in a finer scale of crystallites due to rapid heating and cooling during laser annealing compared to conventional furnace annealing process. A significant increase in saturation magnetization is observed for laser-annealed ribbons compared to both as-received and furnace annealed samples coupled with an increase in coercivity compared to as received sample. The combined effect of thermal histories and stresses developed during laser annealing results in the formation of nano-crystalline phase along the laser track. The phase evolution is traced with the aid of micro-XRD and TEM analysis. The solute partitioning and compositional variation within the phases are obtained by Local Electrode Atom probe analysis. The evolution of microstructure is rationalized using a Finite Element based heat transfer multi-physics model.

  4. Laser assisted crystallization of ferromagnetic amorphous ribbons: A multimodal characterization and thermal model study

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Santhanakrishnan, S.; Smith, Casey; Banerjee, Rajarshi; Dahotre, Narendra B. [Laboratory of Laser Materials Processing and Synthesis Department of Materials Science and Engineering University of North Texas, Denton, Texas 76207 (United States); Devaraj, Arun; Bowden, Mark; Thevuthasan, Suntharampillai [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Ramanujan, R. V. [Schhol of Materials Science and Engineering Nanyang Technological University, Singapore 639798 (Singapore)

    2013-11-14

    This paper focuses on laser-based de-vitrification of amorphous soft magnetic Fe-Si-B ribbons and its consequent influence on the magnetic properties. Laser processing resulted in a finer scale of crystallites due to rapid heating and cooling during laser annealing compared to conventional furnace annealing process. A significant increase in saturation magnetization is observed for laser-annealed ribbons compared to both as-received and furnace annealed samples coupled with an increase in coercivity compared to the as received samples. The combined effect of thermal histories and stresses developed during laser annealing results in the formation of nano-crystalline phase along the laser track. The phase evolution is studied by micro-XRD and TEM analysis. Solute partitioning and compositional variation within the phases are obtained by Local Electrode Atom probe analysis. The evolution of microstructure is rationalized using a Finite Element based heat transfer multi-physics model.

  5. Corneal biomechanical properties after femtosecond laser assisted LASIK with the corneal visualization Scheimpflug technology and ocular response analyzer

    Directory of Open Access Journals (Sweden)

    Jing Li

    2017-02-01

    Full Text Available AIM: To investigate the changes of corneal biomechanical properties before and after femtosecond laser assisted LASIK(FS-LASIKusing Corneal Visualisation Scheimpflug Technology(Corvis STand Ocular Response Analyzer(ORA, and the correlation with other myopic parameters. METHODS:Sixty three patients(63 eyeswho had myopic femtosecond laser assisted LASIK(FS-LASIKwere enrolled in the study. The right eye of each patient was analyzed in this study. The corneal biomechanical parameters pre-operative and 1mo post-operative was measured with the Corvis ST(Oculus, Wetzlar, Germanyand ORA(Reichert, Buffalo, New York, USA. Comparison of the biomechanical property values before and after surgery was peformed using Paired t-test or Mann-Whitney U. Pearson or Spearman correlations were used to evaluate the relationship between parameters.RESULTS: The postoperative 1st A-time, Vin, 2nd A length, Vout, HC time and Radius demonstrate significant decreases comparing with preoperative values(P=0.00, P=0.00, P=0.00, P=0.00, P=0.00, P=0.00 respectively. The postoperative 2nd A-time, DA and PD significantly increases(P=0.00, P=0.00, P=0.00, however, the 1st A length had no significant difference after surgery. The CH and CRF were significantly lower after FS-LASIK(P=0.00, P=0.00. A statistically significant correlation coefficient was found between preoperative central corneal thickness(CCTwith postoperative-preoperative changes of 1st A-time, 2nd A-time, DA and Radius respectively(P=0.01, P=0.04, P=0.03, P=0.01. CONCLUSION:There were significantly changes of corneal biomechanical properties after FS-LASIK surgery. The changes of corneal biomechanical properties after FS-LASIK can be reflected by some parameters of Corvis ST and ORA. The mainly influence of corneal biomechanical alteration was possibly correlation with corneal thickness.

  6. System and method for laser assisted sample transfer to solution for chemical analysis

    Science.gov (United States)

    Van Berkel, Gary J; Kertesz, Vilmos

    2014-01-28

    A system and method for laser desorption of an analyte from a specimen and capturing of the analyte in a suspended solvent to form a testing solution are described. The method can include providing a specimen supported by a desorption region of a specimen stage and desorbing an analyte from a target site of the specimen with a laser beam centered at a radiation wavelength (.lamda.). The desorption region is transparent to the radiation wavelength (.lamda.) and the sampling probe and a laser source emitting the laser beam are on opposite sides of a primary surface of the specimen stage. The system can also be arranged where the laser source and the sampling probe are on the same side of a primary surface of the specimen stage. The testing solution can then be analyzed using an analytical instrument or undergo further processing.

  7. Diagnostics of laser ablated plasma plumes

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2004-01-01

    The effect of an ambient gas on the expansion dynamics of laser ablated plasmas has been studied for two systems by exploiting different diagnostic techniques. First, the dynamics of a MgB2 laser produced plasma plume in an Ar atmosphere has been investigated by space-and time-resolved optical...... of the laser ablated plasma plume propagation in a background gas. (C) 2003 Elsevier B.V All rights reserved....

  8. Transient, three-dimensional heat transfer model for the laser assisted machining of silicon nitride: 1. Comparison of predictions with measured surface temperature histories

    Energy Technology Data Exchange (ETDEWEB)

    Rozzi, J.C.; Pfefferkorn, F.E.; Shin, Y.C. [Purdue University, (United States). Laser Assisted Materials Processing Laboratory, School of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, (United States). Aerospace and Mechanical Engineering Department

    2000-04-01

    Laser assisted machining (LAM), in which the material is locally heated by an intense laser source prior to material removal, provides an alternative machining process with the potential to yield higher material removal rates, as well as improved control of workpiece properties and geometry, for difficult-to-machine materials such as structural ceramics. To assess the feasibility of the LAM process and to obtain an improved understanding of governing physical phenomena, experiments have been performed to determine the thermal response of a rotating silicon nitride workpiece undergoing heating by a translating CO{sub 2} laser and material removal by a cutting tool. Using a focused laser pyrometer, surface temperature histories were measured to determine the effect of the rotational and translational speeds, the depth of cut, the laser-tool lead distance, and the laser beam diameter and power on thermal conditions. The measurements are in excellent agreement with predictions based on a transient, three-dimensional numerical solution of the heating and material removal processes. The temperature distribution within the unmachined workpiece is most strongly influenced by the laser power and laser-tool lead distance, as well as by the laser/tool translational velocity. A minimum allowable operating temperature in the material removal region corresponds to the YSiAlON glass transition temperature, below which tool fracture may occur. In a companion paper, the numerical model is used to further elucidate thermal conditions associated with laser assisted machining. (author)

  9. Laser-assisted cataract surgery and other emerging technologies for cataract removal

    Directory of Open Access Journals (Sweden)

    Aasuri Murali

    1999-01-01

    Full Text Available As we near the end of this century, refractive cataract surgery has become a reality through concerted contributions from ultrasonic phacoemulsification, foldable intraocular lens (IOL implantation technology and keratorefractive surgery. As we enter the new millennium, our sights are set on realizing another dream: accommodative IOL surgery. Towards achieving this goal, many advances have been made in both techniques and technology of cataract removal. Lasers in particular have been under investigation for cataract removal for nearly two decades. The technology has now reached a stage where cataract can indeed be removed entirely with laser alone. Neodymium:YAG and erbium:YAG are the laser sources currently utilized by manufacturers of laser phaco systems. Initial clinical experience reported in the literature has served to highlight the capabilities of lasers and the need for further refinement. Despite the excitement associated with the availability of this alluring new technology for cataract removal, it is necessary to develop more effective laser systems and innovative surgical techniques that optimize its capabilities if laser phaco surgery is to be a genuine improvement over current techniques.

  10. NSAID Pretreatment Inhibits Prostaglandin Release in Femtosecond Laser-Assisted Cataract Surgery.

    Science.gov (United States)

    Schultz, Tim; Joachim, Stephanie C; Szuler, Marek; Stellbogen, Mathias; Dick, H Burkhard

    2015-12-01

    To investigate whether short-term nonsteroidal anti-inflammatory drug (NSAID) pretreatment on the day of surgery inhibits prostaglandin release. Previous studies detected elevated prostaglandin levels after femtosecond laser treatment and identified them as a potential mediator for laser-induced miosis. Patients underwent either image-guided femtosecond laser cataract surgery or conventional cataract surgery (n = 75). Half of the eyes per group received topical NSAID treatment on the day of surgery. Aqueous humor was collected from all patients. ELISA measurements were performed to detect aqueous humor prostaglandin levels. Femtosecond laser cataract surgery led to higher prostaglandin levels than conventional cataract surgery (P = .007). In both groups, NSAID pretreatment led to reduced prostaglandin release. In the femtosecond laser group, patients pretreated with NSAIDs had significantly lower prostaglandin values (65.3 ± 13.2 pg/mL) than patients not pretreated with NSAIDs (294.4 ± 66.5 pg/mL) (P = .0009). The short-term NSAID treatment prevented prostaglandin release in patients treated with image-guided femtosecond laser. Therefore, it has potential to limit intraoperative laser-induced miosis. Copyright 2015, SLACK Incorporated.

  11. Comparative Evaluation of Different Modes of Laser Assisted Endodontics in Primary Teeth: An In vitro Study.

    Science.gov (United States)

    Attiguppe, Prabhakar Ramasetty; Tewani, Krupa Kishore; Naik, Saraswathi V; Yavagal, Chandrashekar M; Nadig, Basappa

    2017-04-01

    The presence of bacteria in root canals has been considered to be responsible for endodontic treatment failure, even in case of primary teeth. The use of lasers can be a valuable addition in removing bacterial load in areas where traditional methods may fail to succeed. Methods like direct laser irradiation of canals, Laser Activated Irrigation (LAI) with sodium hypochlorite (NaOCl) and Photodynamic Therapy (PDT) seem to be a promising alternative for disinfection. This study was designed to compare the efficacy of latest advancements in disinfection techniques using diode laser namely direct laser irradiation, photodynamic therapy and laser activated irrigation using sodium hypochlorite. Sixty freshly extracted primary teeth either single or multi-rooted teeth with two third of their root length intact were collected. Instrumentation was completed to size 30 H-file. Teeth were randomly divided into Group 1- Direct Laser- irradiation, Group 2 - Photodynamic therapy; Group 3- Laser activated irrigation with 2.5% NaOCl. The tooth specimens were inoculated with Enterococcus faecalis. The bacterial colonies were counted preoperatively. Laser irradiation was performed for all groups in accordance to the groups each tooth belonged to. Postoperatively the bacterial colonies were counted. One-way Analysis was applied to compare bacterial count at baseline and post-test between three groups. Tukey's post-hoc test was applied for pairwise comparison between groups. Paired t-test was applied to compare the mean baseline bacterial count with post-test mean bacterial count. The results obtained with all the three groups postoperatively were highly significant (p-value<0.001). Statistically significant difference between results of Group 1 and Group 2 and also between Group 1 and Group 3 was found (p-value≤ 0.001). However, no statistical difference between Group 2 and Group 3 was found (p-value- 0.96). Disinfection strategies using diode laser by techniques gives promising

  12. Pulsed laser-assisted focused electron-beam-induced etching of titanium with XeF2: enhanced reaction rate and precursor transport.

    Science.gov (United States)

    Noh, J H; Fowlkes, J D; Timilsina, R; Stanford, M G; Lewis, B B; Rack, P D

    2015-02-25

    In order to enhance the etch rate of electron-beam-induced etching, we introduce a laser-assisted focused electron-beam-induced etching (LA-FEBIE) process which is a versatile, direct write nanofabrication method that allows nanoscale patterning and editing. The results demonstrate that the titanium electron stimulated etch rate via the XeF2 precursor can be enhanced up to a factor of 6 times with an intermittent pulsed laser assist. The evolution of the etching process is correlated to in situ stage current measurements and scanning electron micrographs as a function of time. The increased etch rate is attributed to photothermally enhanced Ti-F reaction and TiF4 desorption and in some regimes enhanced XeF2 surface diffusion to the reaction zone.

  13. Laser-assisted subepithelial keratectomy and photorefractive keratectomy for post-penetrating keratoplasty myopia and astigmatism in adults.

    Science.gov (United States)

    Huang, Paul Y C; Huang, Peter T; Astle, William F; Ingram, April D; Hèbert, Ania; Huang, John; Ruddell, Stacy

    2011-02-01

    To evaluate whether laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) achieve effective targeted correction and the extent of post-treatment corneal haze after corneal transplantation. Nonhospital surgical facility, Calgary, Alberta, Canada. Evidence-based manuscript. This study evaluated visual acuity, refractive error correction, and potential complications after LASEK or PRK to eliminate refractive error differences after penetrating keratoplasty in adults. A Nidek EC-5000 or Technolas 217 excimer laser was used in all treatments. At last follow-up (mean 20.50 months post laser), the mean spherical equivalent (SE) decreased from -2.71 diopters (D) ± 4.17 (SD) to -0.54 ± 3.28 D in the LASEK group and from -4.87 ± 3.90 D to -1.82 ± 3.34 D in the PRK group. The mean preoperative uncorrected distance visual acuity (UDVA) was 1.63 ± 0.53 and 1.45 ± 0.64, respectively, and the mean postoperative UDVA, 0.83 ± 0.54 and 0.90 ± 0.55, respectively. The improvement in SE and UDVA was statistically significant in both groups (P < .01). The mean haze (0 to 3 scale) at the last follow-up was 0.46 ± 0.708 in the LASEK group and 0.58 ± 0.776 in the PRK group. The UDVA improved and refractive errors were effectively reduced after LASEK or PRK in eyes with previous PKP. There was no significant difference in the change in SE, UDVA, or corrected distance visual acuity between LASEK and PRK. Some patients had evidence of corneal haze, although the difference between the groups was not significant. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Laser-assisted in situ keratomileusis for correction of astigmatism and increasing contact lens tolerance after penetrating keratoplasty.

    Science.gov (United States)

    Park, Chang-Hyun; Kim, Su-Young; Kim, Man-Soo

    2014-10-01

    To determine effectiveness of laser-assisted in situ keratomileusis (LASIK) in the treatment of astigmatism following penetrating keratoplasty (PK). We performed a retrospective review of medical records of patients who underwent LASIK following PK and had over 1 year of follow-up data. Twenty-six patients (26 pairs of eyes) underwent LASIK following PK. Mean age of the patients at the time of LASIK was 40.7 years (range, 26 to 72 years). Following LASIK, the mean cylinder was reduced by 2.4 diopters and mean reduction of cylinder after LASIK was 65.4% from the preoperative values at the last follow-up visit. Uncorrected visual acuity became 20 / 50 or better in 69.2% of the eyes after LASIK. Best-corrected visual acuity became 20 / 50 or better in 73.1% of the eyes after LASIK. All of them were intolerable to contact lenses before LASIK. After LASIK, 6 pairs (23.1%) did not need to use contact lenses and 18 pairs (69.2%) were tolerable to using contact lenses or spectacles. There were no significant endothelial cell density changes 12 months after LASIK (p = 0.239). LASIK is effective in the treatment of astigmatism following PK and increases contact lens and spectacle tolerance.

  15. Endothelial cell loss and refractive predictability in femtosecond laser-assisted cataract surgery compared with conventional cataract surgery

    DEFF Research Database (Denmark)

    Krarup, Therese; Holm, Lars Morten; la Cour, Morten

    2014-01-01

    PURPOSE: To investigate the amount of endothelial cell loss (ECL) and refractive predictability by femtosecond laser-assisted cataract surgery (FLACS) compared to conventional phacoemulsification cataract surgery (CPS). METHODS: Forty-seven patients had one eye operated by FLACS...... and the contralateral eye operated by CPS (stop and chop technique). Both eyes had intraocular aspheric lenses implanted. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), central corneal endothelial cell count and hexagonality with a non-contact specular microscope were assessed...... ± 0.42) by CPS (p = 0.56). Mean CDVA was 0.89 (0.3; 1.25) by FLACS and 0.93 (0.4; 1.25) by CPS at 3 months postoperatively (p = 0.36). Within both groups, 70% gained a CDVA of 6/6. Mean surgery time was 9.3 min (SD ± 1.9) by FLACS and 8.0 min (SD ± 1.9) by CPS, (p = 0.0018). Mean phaco energy was 3...

  16. Laser ablation in analytical chemistry - A review

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Richard E.; Mao, Xianglei; Liu, Haichen; Gonzalez, Jhanis; Mao, Samuel S.

    2001-10-10

    Laser ablation is becoming a dominant technology for direct solid sampling in analytical chemistry. Laser ablation refers to the process in which an intense burst of energy delivered by a short laser pulse is used to sample (remove a portion of) a material. The advantages of laser ablation chemical analysis include direct characterization of solids, no chemical procedures for dissolution, reduced risk of contamination or sample loss, analysis of very small samples not separable for solution analysis, and determination of spatial distributions of elemental composition. This review describes recent research to understand and utilize laser ablation for direct solid sampling, with emphasis on sample introduction to an inductively coupled plasma (ICP). Current research related to contemporary experimental systems, calibration and optimization, and fractionation is discussed, with a summary of applications in several areas.

  17. IR laser ablation of dental enamel

    Science.gov (United States)

    Fried, Daniel

    2000-03-01

    An overview of the basic mechanisms of IR laser ablation of dental enamel is presented. Enamel is a highly structured tissue consisting of an heterogeneous distribution of water, mineral, protein and lipid. Absorption bands of water and carbonated hydroxyapatite can be selectively targeted from 2.7 to 11-micrometer via several laser wavelengths. Mechanistic differences in the nature of ablation and the varying surface morphology produced can be explained by the microstructure of the tissue. Suggested criteria for the choice of the optimum laser parameters for clinical use, the influence of plasma shielding and the role of exogenous water on the mechanism of ablation are discussed.

  18. 445-nm diode laser-assisted debonding of self-ligating ceramic brackets.

    Science.gov (United States)

    Stein, Steffen; Kleye, Alexander; Schauseil, Michael; Hellak, Andreas; Korbmacher-Steiner, Heike; Braun, Andreas

    2017-10-26

    This study determined the influence of irradiation on aesthetic ceramic brackets with a novel 445-nm diode laser prior to debonding on the bracket failure mode. Thirty ceramic brackets (In-Ovation® C, GAC) were standard-bonded to the oral and buccal planed and polished enamel surfaces of 15 caries-free human 3rd molars. Prior to study-blinded debonding, the brackets in the laser group were irradiated with the diode laser (SIROLaser Blue®, Sirona), while the irradiation was simulated within the conventional group. To determine the degree of enamel fractures and the adhesive remnant index (ARI) before debonding (T0), after debonding (T1) and after removal of the remaining composite using a rotating fraise (red ring, Comet) (T2), micrographs of the enamel surface at 10-fold and 20-fold magnifications were taken. Additionally, the enamel surface was investigated using seven randomly chosen samples from each group at every time point by SEM at 200-fold and 500-fold magnifications. In the laser group, the ARI-score was statistically significantly reduced (pdiode laser prior to debonding of ceramic brackets significantly changes bonding failure in terms of less remaining adhesive. This is of clinical importance as the risk of enamel fractures and chair time can be reduced.

  19. Audit of transoral laser-assisted microsurgical resection of early laryngeal cancer.

    Science.gov (United States)

    Amir, I; Vernham, G A

    2015-04-01

    This study aimed to report our current practice of transoral laser microsurgery for early glottic cancer against the standards outlined by the ENT UK Head and Neck Group and assess the oncological outcome. A retrospective review of case notes of patients diagnosed with early glottic cancer (tumour stages Tis, T1 and T2) who underwent transoral laser microsurgery as a primary curative treatment. The minimum follow-up period was two years. Thirty-one patients had transoral laser microsurgery for early glottic cancer during the study period. Eighty-four per cent of cases were discussed by a multidisciplinary team prior to transoral laser microsurgery. Complete circumferential excision was achieved in 77 per cent of cases. Sixty-five per cent of specimens were subjected to histological analysis; they complied with standard pathology reporting for margins. Within 12 months of transoral laser microsurgery, there were 10 residual cases and 2 recurrences. Kaplan-Meier survival analysis gave disease-free survival rates of 96.8 per cent at 18 months and 93.5 per cent at 24 months. The laryngectomy-free survival rate was 96.8 per cent at two years. The findings of this audit are encouraging and have highlighted areas for further discussions, recommendations, training and education.

  20. Field measurements suggest the mechanism of laser-assisted water condensation.

    Science.gov (United States)

    Henin, S; Petit, Y; Rohwetter, P; Stelmaszczyk, K; Hao, Z Q; Nakaema, W M; Vogel, A; Pohl, T; Schneider, F; Kasparian, J; Weber, K; Wöste, L; Wolf, J-P

    2011-08-30

    Because of the potential impact on agriculture and other key human activities, efforts have been dedicated to the local control of precipitation. The most common approach consists of dispersing small particles of dry ice, silver iodide, or other salts in the atmosphere. Here we show, using field experiments conducted under various atmospheric conditions, that laser filaments can induce water condensation and fast droplet growth up to several μm in diameter in the atmosphere as soon as the relative humidity exceeds 70%. We propose that this effect relies mainly on photochemical formation of p.p.m.-range concentrations of hygroscopic HNO(3), allowing efficient binary HNO(3)-H(2)O condensation in the laser filaments. Thermodynamic, as well as kinetic, numerical modelling based on this scenario semiquantitatively reproduces the experimental results, suggesting that particle stabilization by HNO(3) has a substantial role in the laser-induced condensation.

  1. Diode laser-assisted endoscopic dacryocystorhinostomy: a comparison of three different combinations of adjunctive procedures.

    Science.gov (United States)

    Dogan, Remzi; Meric, Aysenur; Ozsütcü, Mustafa; Yenigun, Alper

    2013-08-01

    Chronic dacryocystitis is a frequently encountered condition which can be corrected by dacryocystorhinostomy. Today, the diode laser is increasingly put to use in such corrective operations. This study aims to answer the questions of which adjunctive procedures and which combinations of such procedures are necessary and effective in securing more successful outcomes in diode laser dacryocystorhinostomy. This prospective randomized study included eighty patients (13 male, 67 female) who underwent dacryocystorhinostomy in our hospital during the 2 year period of January 2009-January 2011. The patients were selected consecutively and were randomly allocated to three groups. Group 1 (30): diode laser + mitomycin C + silicone intubation; Group 2 (27): diode laser + silicone intubation; Group 3 (23): diode laser + mitomycin C. All patients were evaluated postoperatively on day 1, week 1, and on the 1st, 3rd, 6th, 12th, 18th, and 24th months. The postoperative evaluation consisted of preoperative and postoperative ostium measurements, recording postoperative complications, and calculating and comparing success rates and operative times. The mean ages of the patients were 63.4 for Group 1, 60.7 for Group 2, and 61.8 for Group 3. No statistically significant difference was found among the groups regarding pre- and postoperative ostium measurements. The success rates were 84.3, 80, and 76.9 % for Groups 1, 2, and 3, respectively. Complications noted in Group 1 were restenosis (3), premature silicone tube loss (1), development of granulation tissue (3), synechia (2), infection (2), and hemorrhage (3). Those for Group 2 were restenosis (5), premature tube loss (2), granulation (8), synechia (6), infection (3), and hemorrhage (4). Group 3 had 6 cases with stenosis, 5 with granulation, 3 with infection, 6 with synechia, and 5 with hemorrhage. The operative times of the groups were 25.5, 15.3, and 18.1 min, respectively, for Group 1, 2, and 3. All three groups had statistically

  2. A physical model of laser-assisted blocking of blood flow: I. Rectangular radiation pulses

    CSIR Research Space (South Africa)

    Zheltov, GI

    2007-03-01

    Full Text Available A method for the calculation of blocking of blood flow upon treatment of vessel pathologies by laser irradiation at a wavelength of 530 nm are considered. The model is based on the assumption that blood-vessel occlusion is a consequence of preceding...

  3. Safety, efficacy and efficiency of laser-assisted IVF in subfertile mutant mouse strains

    Science.gov (United States)

    Li, Ming-Wen; Kinchen, Kristy L; Vallelunga, Jadine M; Young, Diana L; Wright, Kaleb D K; Gorano, Lisa N; Wasson, Katherine; Lloyd, K C Kent

    2013-01-01

    In the present report we studied the safety, efficacy and efficiency of using an infrared laser to facilitate IVF by assessing fertilization, development and birth rates after laser-zona drilling (LZD) in 30 subfertile genetically modified (GM) mouse lines. We determined that LZD increased the fertilization rate four to ten times that of regular IVF, thus facilitating the derivation of 26 of 30 (86.7%) GM mouse lines. Cryopreserved two-cell stage embryos derived by LZD-assisted IVF were recovered and developed to blastocysts in vitro at the same rate as frozen–thawed embryos derived by regular IVF. Surprisingly after surgical transfer to pseudopregnant recipients the birth rate of embryos derived by LZD-assisted IVF was significantly lower than that of embryos derived by regular IVF. However this result could be completely mitigated by the addition of 0.25 M sucrose to the culture medium during LZD which caused the oocyte to shrink in volume relative to the perivitelline space. By increasing the distance from the laser target site on the zona pellucida, we hypothesize that the hyperosmotic effect of sucrose reduced the potential for laser-induced cytotoxic thermal damage to the underlying oocytes. With appropriate preparation and cautious application, our results indicate that LZD-assisted IVF is a safe, efficacious and efficient assisted reproductive technology for deriving mutant mouse lines with male factor infertility and subfertility caused by sperm–zona penetration defects. PMID:23315689

  4. Fractional laser-assisted topical delivery leads to enhanced, accelerated and deeper cutaneous 5-fluorouracil uptake

    DEFF Research Database (Denmark)

    Wenande, Emily; Olesen, Uffe H; Nielsen, Mette M B

    2017-01-01

    diffusion cells at 4 and 24 hours (n =55). HPLC quantified 5-FU in full-thickness skin, specific skin depths of 100μm-1500μm, and transcutaneous receiver-compartments. Qualitative matrix-assisted laser-desorption/ionization mass-spectrometry imaging (MALDI-MSI) visualized 5-FU in selected samples. RESULTS...

  5. Laser assisted modification of poled silver-doped nanocomposite soda-lime glass

    Directory of Open Access Journals (Sweden)

    Drevinskas Rokas

    2013-11-01

    Full Text Available Thermal poling assisted homogenization of polydisperse Ag nanoparticles embedded in the soda-lime glass is demonstrated. The homogenization leads to the narrowing of the localized surface plasmon resonance. The subsequent irradiation with linearly polarized ultrashort laser pulses induces spectrally defined and four times larger dichroism than in non-poled sample.

  6. Laser-assisted microstructuring for Ti:sapphire channel-waveguide fabrication

    NARCIS (Netherlands)

    Crunteanu, A.; Pollnau, Markus; Jänchen, G.; Hibert, C.; Hoffmann, P.; Salathé, R.P.; Eason, R.W.; Shepherd, D.P.

    2003-01-01

    We report on the fabrication of Ti:sapphire channel waveguides. Such channel waveguides are of interest, e.g., as low-threshold tunable lasers. We investigated several structuring methods including ion beam implantation followed by wet chemical etching strip loading by polyimide spin coating and

  7. Laser assisted periodontal treatment: from bactericidal effect to local modification of the host response

    Science.gov (United States)

    Ciurescu, Codruţa.; Teslaru, Silvia; Zetu, Liviu; Ciurescu, Daniel

    2016-03-01

    The aim of the present short-term study is to investigate efficiency of laser therapy as adjunct to conventional periodontal therapy in patients with chronic periodontitis. Methods. The study protocol included 44 patients (20 males, 24 females; age 45-60) with moderate and advanced chronic periodontitis, recruited in Private Clinic Krondent (Brasov, Romania). The patients were randomly assigned in two groups, one group (test-sites group, 22 patients) treated by ultrasonic scaling and root planning followed by laser therapy (940 nm diode laser and 2780 nm Er:Cr:YAG laser) and second group (control-sites group, 22 patients) treated only by ultrasonic scaling and root planning. All patients were submitted to initial evaluation, recording of bleeding on probing (BOP) and probing of pockets depth (PPD), oral hygiene instruction and motivation. Indices BOP and PPD for the assessed periodontal sites were also recorded at 8 weeks, 16 weeks and 24 weeks after treatment. Results. Periodontal inflammatory parameters PPD (PPD>=4mm) were significantly lower in test-sites group as compared with control-sites group at 2 months (82% vs. 90%), 4 months (42% vs. 62%), and 6 months (11% vs. 30%).Periodontal parameters BOP were lower among patients in control-sites group and test-sites group at 2 months (38% vs. 32%), and significantly lower in test-sites group at 4 months (42% vs.26%), and 6 months (44% vs. 24%). Conclusions. The additional use of laser therapy increases significantly the efficiency of periodontal treatment comparing with conventional periodontal therapy.

  8. Femtosecond laser ablation of dentin and enamel: relationship between laser fluence and ablation efficiency.

    Science.gov (United States)

    Chen, Hu; Liu, Jing; Li, Hong; Ge, Wenqi; Sun, Yuchun; Wang, Yong; Lü, Peijun

    2015-02-01

    The objective was to study the relationship between laser fluence and ablation efficiency of a femtosecond laser with a Gaussian-shaped pulse used to ablate dentin and enamel for prosthodontic tooth preparation. A diode-pumped thin-disk femtosecond laser with wavelength of 1025 nm and pulse width of 400 fs was used for the ablation of dentin and enamel. The laser spot was guided in a line on the dentin and enamel surfaces to form a groove-shaped ablation zone under a series of laser pulse energies. The width and volume of the ablated line were measured under a three-dimensional confocal microscope to calculate the ablation efficiency. Ablation efficiency for dentin reached a maximum value of 0.020 mm3∕J when the laser fluence was set at 6.51 J∕cm2. For enamel, the maximum ablation efficiency was 0.009 mm3∕J at a fluence of 7.59 J∕cm2.Ablation efficiency of the femtosecond laser on dentin and enamel is closely related to the laser fluence and may reach a maximum when the laser fluence is set to an appropriate value. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

  9. Evolution of size distribution and structure of Si and SiO2 nanoparticles: laser-assisted formation and fragmentation

    Science.gov (United States)

    Eidelman, K.; Gudkov, D.; Segbefia, O.; Ageev, E.; Krivonosov, A.; Matuhina, A.

    2017-11-01

    In this work, Si and SiO2, nanoparticles (NPs) was prepared by pulsed laser ablation (PLA) in distilled water. The radiation of a ytterbium fiber laser (repetition rate f = 50 kHz, wavelength λ = 1064 nm and pulse duration τ = 8 ns and 100 ns) at different laser intensities was utilized to ablate the Si target (99.999%, cubic, 7×7 mm2) under liquid layer to synthesize and to fragment the silicon colloidal NPs. Studies of morphology and size distribution of silica NPs were conducted using Transmission Electron Microscopy (TEM). The NPs of crystalline and amorphous phases were founded. Most of the NPs in the nano colloids were found to have dimensions less than 100 nm, and a few of them were between 100 nm and 700 nm. Dependence of average NP size on the number of laser passes was revealed. The average size of the nanoparticles obtained by TEM was confirmed by dynamic light scattering (DLS) measurements.

  10. Laser Assisted Soldering: Effects of Hydration on Solder-Tissue Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Chan, E.K.; Welch, A.J. [The University of Texas, Biomedical Engineering Laser Laboratory, Austin, Texas (United States); Brown, D.T. [North Carolina State University, Department of Biochemistry, Raleigh, North Carolina (United States); Kovach, I.S. [Massachusetts General Hospital, Department of Orthopedics, Boston, Massachusetts (United States)

    1998-10-01

    Wound stabilization is critical in early wound healing. Other than superficial skin wounds, most tissue repair is exposed to a hydrated environment postoperatively. To simulate the stability of laser-soldered tissue in a wet environment, we studied the effects of hydration on laser soldered rat dermis and baboon articular cartilage. In this {ital in vitro} study, we used a solder composed of human serum albumin, sodium hyaluronate, and Indocyanine Green. A 2 {mu}L solder droplet was deposited on each tissue specimen and then the solder was irradiated with a scanning laser beam (808 nm and 27thinspW/cm{sup 2}). After photocoagulation, each tissue specimen was cut into two halves dividing the solder. One half was reserved as control while the other half was soaked in saline for a designated period before fixation (1 h, 1, 2, and 7 days). All tissue specimens were prepared for scanning electron microscopy (SEM). SEM examinations revealed nonuniform coagulation across the solder thickness for most of the specimens, likely a result of the temperature gradient generated by laser heating. Closer to the laser beam, the uppermost region of the solder formed a dense coagulum. The solder aggregated into small globules in the region anterior to the solder-tissue interface. All cartilage specimens soaked in saline suffered coagulum detachment from tissue surface. We noted a high concentration of the protein globules in the detached coagulum. These globules were likely responsible for solder detachment from the cartilage surface. Solder adhered better to the dermis than to cartilage. The dermal layer of the skin, composed of collagen matrix, provided a better entrapment of the solder than the smooth surface of articular cartilage. Insufficient laser heating of solder formed protein globules. Unstable solder-tissue fusion was likely a result of these globules being detached from tissue substrate when the specimen was submerged in a hydrated environment. The solder-tissue bonding

  11. Femto-lasik: The recent innovation in laser assisted refractive surgery.

    Science.gov (United States)

    Bashir, Zubair Shahid; Ali, Muhammad Hassaan; Anwar, Ayesha; Ayub, Muhammad Hammad; Butt, Nadeem Hafeez

    2017-04-01

    Femtosecond laser has been introduced in refractive surgery to create a thin-hinged corneal flap without using any blade. The current review was planned to analyse and compare femtosecond-assisted laser in-situ keratomileusis (LASIK), the latest refractive procedure, with conventional techniques in refractive surgery. The analysis showed that femtosecond-assisted LASIK yielded more predictable corneal flaps, lesser ocular aberrations, better uncorrected visual acuity, lesser variations in intraocular pressure (IOP) and fewer chances of developing dry eyes. Transient light sensitivity, diffuse lamellar keratitis, opaque bubble layer, corneal haze and rainbow glare are some of the demerits of femtosecond-assisted LASIK, but these can be prevented with certain precautions. The early visual rehabilitation and preservation of corneal anatomy are added benefits in the long run. Though it is expensive currently, the competition in market is expected to cut down the cost soon.

  12. Laser-Assisted Reduction of Highly Conductive Circuits Based on Copper Nitrate for Flexible Printed Sensors

    Science.gov (United States)

    Bai, Shi; Zhang, Shigang; Zhou, Weiping; Ma, Delong; Ma, Ying; Joshi, Pooran; Hu, Anming

    2017-10-01

    Stretchable electronic sensing devices are defining the path toward wearable electronics. High-performance flexible strain sensors attached on clothing or human skin are required for potential applications in the entertainment, health monitoring, and medical care sectors. In this work, conducting copper electrodes were fabricated on polydimethylsiloxane as sensitive stretchable microsensors by integrating laser direct writing and transfer printing approaches. The copper electrode was reduced from copper salt using laser writing rather than the general approach of printing with pre-synthesized copper or copper oxide nanoparticles. An electrical resistivity of 96 μΩ cm was achieved on 40-μm-thick Cu electrodes on flexible substrates. The motion sensing functionality successfully demonstrated a high sensitivity and mechanical robustness. This in situ fabrication method leads to a path toward electronic devices on flexible substrates.[Figure not available: see fulltext.

  13. Er:YAG Laser Assisted Treatment of Central Odontogenic Fibroma of the Mandible

    Directory of Open Access Journals (Sweden)

    Luis Silva Monteiro

    2015-01-01

    Full Text Available Central odontogenic fibroma is a very rare benign odontogenic tumour characterized by a fibrous mature stroma with variable strands or islands of inactive-looking odontogenic epithelium. Our aim is to report a case of a central odontogenic fibroma and describe the clinical usefulness of Er:YAG laser for the surgical treatment of this tumour. A 74-year-old woman presented with an expansive lesion located in a mandible with multilocular and mixed radiographic appearance. A conservative excision using Er:YAG laser was performed. Complete removal was obtained. There were no postoperative complications. The histopatologic features were consistent with the diagnosis of central odontogenic fibroma of rich-epithelium type. No recurrence was observed during follow-up.

  14. Joining of Aluminium Alloy and Steel by Laser Assisted Reactive Wetting

    Science.gov (United States)

    Liedl, Gerhard; Vázquez, Rodrigo Gómez; Murzin, Serguei P.

    2017-12-01

    Compounds of dissimilar materials, like aluminium and steel offer an interesting opportunity for the automotive industry to reduce the weight of a car body. Thermal joining of aluminium and steel leads to the formation of brittle intermetallic compounds, which negatively affects the properties of the welded joint. Amongst others, growth of such intermetallic compounds depends on maximum temperature and on the time at certain temperatures. Laser welding with its narrow well seam and its fast heating and cooling cycles provides an excellent opportunity to obtain an ultrathin diffusion zone. Joining of sheet metal DC01 with aluminium alloy AW6016 has been chosen for research. The performed experimental studies showed that by a variation of the beam power and scanning speed it is possible to obtain an ultrathin diffusion zone with narrow intermetallic interlayers. With the aim of supporting further investigation of laser welding of the respective and other dissimilar pairings a multi-physical simulation model has been developed.

  15. Intra- and intercycle interference of electron emission in laser assisted XUV atomic ionization

    CERN Document Server

    Gramajo, Ana Alicia; Garibotti, Carlos Roberto; Arbó, Diego

    2016-01-01

    We study the ionization of atomic hydrogen in the direction of polarization due to a linearly polarized XUV pulse in the presence a strong field IR. We describe the photoelectron spectra as an interference problem in the time domain. Electron trajectories steming from different optical laser cycles give rise to intercycle interference energy peaks known as sidebands. These sidebands are modulated by a grosser structure coming from the intracycle interference of the two electron trajectories born during the same optical cycle. We make use of a simple semiclassical model which offers the possibility to establish a connection between emission times and the photoelectron kinetic energy. We compare the semiclassical predictions with the continuum-distorted wave strong field approximation and the ab initio solution of the time dependent Schr\\"odinger equation. We analyze such interference pattern as a function of the time delay between the IR and XUV pulse and also as a function of the laser intensity.

  16. Proof-of-principle demonstration of high efficiency laser-assisted H^{-} beam conversion to protons

    Directory of Open Access Journals (Sweden)

    V. Danilov

    2007-05-01

    Full Text Available Thin carbon foils are used as strippers for charge exchange injection into high intensity proton rings. However, the stripping foils become radioactive and produce uncontrolled beam loss, which is one of the main factors limiting beam power in high intensity proton rings. Recently, we presented a scheme for laser stripping an H^{-} beam for the Spallation Neutron Source (SNS ring. First, H^{-} atoms are converted to H^{0} by a magnetic field, then H^{0} atoms are excited from the ground state to the upper levels by a laser, and the excited states are converted to protons by a magnetic field. In this paper we report on the proof-of-principle demonstration of this scheme to give high efficiency (around 90% conversion of H^{-} beam into protons at SNS in Oak Ridge. The experimental setup is described, and comparison of the experimental data with simulations is presented.

  17. Q-switched alexandrite laser-assisted treatment of melasma: 2-year follow-up monitoring.

    Science.gov (United States)

    Rusciani, Antonio; Motta, Angela; Rusciani, Luigi; Alfano, Carmine

    2005-01-01

    Melasma is a common disorder of hyperpigmentation involving sun exposed face and neck areas. Three clinical patterns of melasma are recognized: the centrofacial, the malar, and the mandibular ones. Several factors have been implicated in the pathogenesis of this disorder including pregnancy, oral contraceptive therapy, sun exposure, genetic factors, cosmetics, and race. This condition is most frequently observed in women and affects all racial groups; however, it is commonly found in darker-complexioned individuals (skin types IV through VI) and in Asian women who live and work under strong sunlight exposure for long periods. Melasma is very difficult to treat and often resistant to therapy. Treatment of melasma includes various hypopigmenting agents, chemical peeling, and laser surgery with unsatisfactory results. We report 3 cases of facial melasma successfully treated with a Q-switched Alexandrite laser.

  18. Laser-assisted dealloying for direct-write patterning of plasmonic nanostructures

    Science.gov (United States)

    Li, Jingting; Zhao, Fusheng; Shih, Wei-Chuan

    2017-02-01

    Recently, nanoporous gold (NPG) has attracted significant interest due to its unique properties such as large specific surface area, bi-continuous nanostructure, high electrical conductivity and the applicability of thiol-gold surface chemistry. Patterned NPG disks showcase tunable pore and ligament sizes ranging from nanometers to microns. The nanoporous structure and sub-wavelength nanoparticle shape contribute to its unique LSPR properties. NPG disk not only features large specific surface area, but high-density plasmonic field enhancement known as "hot-spots". Hence, NPG disks have found many applications in nanoplasmonic sensor development. In our recent studies, we have shown that NPG disks array chip can be utilized for high-sensitivity detection by various enhanced spectroscopic modalities, as photothermal agents, and for disease biomarker detection. To date, patterned NPG disks have been exclusively fabricated by colloidal nanosphere lithography. Starting with pattern transfer into alloy disks, dealloying subsequently turns the alloy disks into NPG disks. In this paper, we present another NPG patterning method by localized laser heating, during which dealloying occurs at the laser focal spots due to elevated temperature. This approach has enabled us to pattern NPG entity with various sizes and shapes. We have investigated fabrication parameters such as laser power, irradiation duration, and solution environment. We have also characterized the plasmonic resonance of the patterned NPG disks by extinction spectroscopy. The noncontact nature of this technique is well suited for the processing of substrates immersed in an aqueous environment. Further, this technique shares the same advantages as maskless laser direct writing.

  19. Laser-assisted surface modification of Ti-implant in air and water environment

    Science.gov (United States)

    Trtica, M.; Stasic, J.; Batani, D.; Benocci, R.; Narayanan, V.; Ciganovic, J.

    2018-01-01

    A study of the surface modification of titanium CP grade 2 implant/target with high intensity picosecond (Nd:YAG) laser, operating at 1064 nm wavelength and pulse duration of 40 ps, in gaseous (air) and liquid (water) medium, is presented. The exposure of Ti to a laser pulse energy of 17 mJ in both media - gaseous and liquid, induced specific surface features and phenomena: (i) enhancement of the implant surface roughness (higher in water). In this context, the damage depth is more prominent in water (as high as ∼40 μm) vs. air (∼14 μm). Also, the appearance of laser induced periodic surface structures (LIPSS) is recorded in both media, at periphery area, while in water they are registered at lower pulse count; (ii) variation of chemical surface content depending on the applied medium. Thus, in the central irradiation region, the oxygen was absent in air while its concentration was relatively high (6.44 wt%) in case of water; (iii) possibility of direct collection of synthesized titanium based nanoparticles in water environment, and (iv) formation of the plasma above the sample in both mediums, more volumetrically confined in water. These investigations showed that surface structuring and observed phenomena are in strong correlation with the medium used. The liquid - water seems like the medium of choice in regard to titanium implant biocompatibility and bio-activity (the water is a favorable medium for build-up of the oxide layer which affects bioactivity). The process of laser interaction with titanium implant targets was accompanied by the formation of plasma plume, which provides the additional sterilizing effect facilitating contaminant-free conditions.

  20. Laser assisted nuclear decay spectroscopy: A new method for studying neutron-deficient francium

    CERN Document Server

    Lynch, Kara Marie

    2015-01-01

    Radioactive decay studies of rare isotopes produced at radioactive ion beam facilities have often been hindered by the presence of isobaric and isomeric contamination. The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN uses laser radiation to stepwise excite and ionize an atomic beam in a particular isomeric state. Deflection of this selectively ionized beam of exotic nuclei, from the remaining neutral contaminants, allows ultra-sensitive detection of rare isotopes and nuclear structure measurements in background-free conditions.\

  1. Femtosecond laser assisted 3-dimensional freeform fabrication of metal microstructures in fused silica (Conference Presentation)

    Science.gov (United States)

    Ebrahim, Fatmah; Charvet, Raphaël.; Dénéréaz, Cyril; Mortensen, Andreas; Bellouard, Yves

    2017-03-01

    Femtosecond laser exposure of fused silica combined with chemical etching has opened up new opportunities for three-dimensional freeform processing of micro-structures that can form complex micro-devices of silica, integrating optical, mechanical and/or fluidic functionalities. Here, we demontrate an expansion of this process with an additional fabrication step that enables the integration of three-dimensional embedded metallic structures out of useful engineering metals such as silver, gold, copper as well as some of their alloys. This additional step is an adaptation of the pressure infiltration for the insertion of high conductivity, high melting point metals and alloys into topologically complex, femtosecond laser-machined cavities in fused silica. This produces truly 3-dimensional microstructures, including microcoils and needles, within the bulk of glass substrates. Combining this added capability with the existing possibilities of femtosecond laser micromachining (i.e. direct written waveguides, microchannels, resonators, etc.) opens up a host of potential applications for the contactless fabrication of highly integrated monolithic devices that include conductive element of all kind. We present preliminary results from this new fabrication process, including prototype devices that incorporate 3D electrodes with aspect ratios of 1:100 and a feature size resolution down to 2μm. We demonstrate the generation of high electric field gradients (of the order of 1013 Vm-2) in these devices due to the 3-dimensional topology of fabricated microstructures.

  2. Laser-assisted ultrafast photoassociation in HeH{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Bo Y.; Shin, Seokmin [School of Chemistry (BK21), Seoul National University, Seoul 151-747 (Korea, Republic of); Santamaria, Jesus [Departamento de Química Física I, Universidad Complutense, 28040 Madrid (Spain); Sola, Ignacio R., E-mail: isola@ucm.es [Departamento de Química Física I, Universidad Complutense, 28040 Madrid (Spain)

    2014-10-17

    Highlights: • We study numerically photoassociation assisted by femtosecond pulses in HeH{sup 2+}. • The bond can be formed in a hot collision with the electron initially in H or He{sup +}. • We predict Rabi oscillations of the yield as a function of the pulse amplitude. • We predict weak dependence of the yield on the initial nuclear momentum uncertainty. - Abstract: In this work we report control on the photoassociation of a proton and a Helium cation, or an alpha particle and an Hydrogen atom, to form HeH{sup 2+} assisted by strong femtosecond laser pulses. The results follow from the numerical solution of the time-dependent Schrödinger equation using soft-core Coulomb potentials in a (1+1)D model (one dimension for the electronic motion plus one dimension for the nuclear motion) and for a nuclear Hamiltonian describing the dynamics in four electronic states. We study the dependence of the photoassociation yield on the initial nuclear wave function for a hot collision (impact kinetic energy of the order of a eV) and on the laser parameters. We predict high sensitivity on the synchronization of the laser with the collision time and Rabi oscillations for the yield as a function of the pulse amplitude and duration, while the ionization and inelastic scattering can be minimized with pulses of 50 fs or shorter.

  3. Laser assisted irrigation and hand irrigation for root canal decontamination: a comparison

    Science.gov (United States)

    Olivi, M.; Stefanucci, M.; Todea, C.

    2014-01-01

    Aim: to compare the bactericidal efficiency of conventional method and LAI for root canal decontamination. Material and method: 22 human single root teeth, extracted for periodontal problems, mechanically prepared up to ISO 25 at the working lenght were divided in 2 groups: after sterilization, the teeth were infected with enterococcus faecalis and incubated for 4 weeks. Group A: 10 teeth were irrigated with conventional hand technique (CI): 3ml of 5% NaClO were used for two times of 30s each and after washing with sterile bi-distilled water for 20s, a final irrigation was performed with 3ml of 17% EDTA. Group B: 10 teeth were irrigated with 3ml of NaClO and activated by erbium laser, two cycles of 30s; also the final irrigation with 3ml of 17% EDTA was activated by erbium laser. In both the groups a resting time of 30s was used between the two sessions to allow the reaction rate of NaClO. The Erbium laser 2940 nm (LightWalker AT, Fotona; Lublijana, Slovenia) was used with 50microsecond pulse duration, at 15Hz, 20mJ, with a 600micron PIPS tip. Two samples were used as positive and negative control.

  4. Intrapulpal Temperature Increases Caused by 445-nm Diode Laser-Assisted Debonding of Self-Ligating Ceramic Brackets During Simulated Pulpal Fluid Circulation.

    Science.gov (United States)

    Stein, Steffen; Wenzler, Johannes; Hellak, Andreas; Schauseil, Michael; Korbmacher-Steiner, Heike; Braun, Andreas

    2018-01-03

    This study investigated temperature increases in dental pulp resulting from laser-assisted debonding of ceramic brackets using a 445-nm diode laser. Eighteen ceramic brackets were bonded in standardized manner to 18 caries-free human third molars. Pulpal fluid circulation was simulated by pumping distilled water at 37°C through the pulp chamber. The brackets were irradiated with a 445-nm diode laser. Temperatures were measured using a thermal camera at points P1 (center of the pulp) and P2 (in the hard dental tissue) at the baseline (T0), at the start and end of laser application (T1 and T2), and the maximum during the sequence (Tmax). Significant differences in the temperatures measured at P1 and P2 were observed among T0, T1, T2, and Tmax. Significant increases in temperature were noted at points P1 and P2, between T1 and T2, T1 and Tmax, and T2 and Tmax. The maximum P2 values were significantly higher than at P1. The maximum temperature increase measured in the pulp was 2.23°C, lower than the critical threshold of 5.5°C. On the basis of the laser settings used, there is no risk to the vitality of dental pulp during laser-assisted debonding of ceramic brackets with a 445-nm diode laser.

  5. Thermoelectric properties of gradient polymer composites with nano-inclusions fabricated by laser assisted sintering

    Science.gov (United States)

    Shishkovsky, I. V.; Scherbakov, V. I.; Saraeva, I. N.; Ionin, A. A.

    2017-03-01

    Selective laser sintering (SLS) was used to prepare porous gradient polymer nanocomposites consisting of a polyetheretherketone (PEEK) matrix doped with alternating layers of Ni and Cu nanoparticles. Optimal regimes of such 3D-fabrication were determined. The functional graded (FG) structure of sintered parts was observed by optical and scanning electron microscopy and EDX microanalysis. Temperature dependence of electro-physical properties was studied for alternating ferromagnetic/non-magnetic layers (up to 10 layers) into 3D-graded samples derived from Ni-PEEK-Cu powders. Temperature dependences for the real part of the dielectric permeability and loss tangent were found to have a hysteresis character.

  6. Physical Model of Laser-Assisted Blocking of Blood Flow: II. Pulse Modulation of Radiation

    CSIR Research Space (South Africa)

    Zheltov, GI

    2007-03-01

    Full Text Available This study is a continuation of our preceding inves- tigation [1], where we considered the mechanism of blocking blood flow under laser irradiation and assumed that the experimentally observed contraction of blood vessels [2] is a consequence... of the blood vessel due to the vaporization phase transition and formation of gas–vapor bubbles. As an alternative, we will consider below a possible way to reduce this risk by using irra- diation with a regular series (train) of short pulses. The total...

  7. Ultrafast laser-assisted spatially targeted optoporation into cortical axons and retinal cells in the eye

    Science.gov (United States)

    Batabyal, Subrata; Kim, Young-Tae; Mohanty, Samarendra

    2017-06-01

    Visualization and assessment of the cellular structure and function require localized delivery of the molecules into specific cells in restricted spatial regions of the tissue and may necessitate subcellular delivery and localization. Earlier, we have shown ultrafast near-infrared laser beam-assisted optoporation of actin-staining molecules into cortical neurons with single-cell resolution and high efficiency. However, diffusion of optoporated molecules in soma degrades toward the growth cone, leading to difficulties in visualization of the actin network in the growth cone in cases of long axons. Here, we demonstrate optoporation of impermeable molecules to functional cortical neurons by precise laser subaxotomy near the growth cone, leading to visualization of the actin network in the growth cone. Further, we demonstrate patterned delivery of impermeable molecules into targeted retinal cells in the rat eye. The development of optoporation as a minimally invasive approach to reliably deliver exogenous molecules into targeted axons and soma of retinal neurons in vivo will enable enhanced visualization of the structure and function of the retina.

  8. Analysis and Simulation of Generating Terahertz Surface Waves in Laser-Assisted Field Emission

    Science.gov (United States)

    Hagmann, Mark; Kumar, Gagan; Pandey, Shashank; Nahata, Ajay

    2011-03-01

    When the radiation from two lasers is focused on a field emission diode the electric field from the radiation is superimposed on the applied DC field, and the nonlinear dependence of the emitted current on the electric field causes the current to oscillate at the difference frequency for the two lasers. Finite Difference-Time Domain simulations and analytical solutions for a paraboloidal model of the field emission tip show that the current oscillations create a transverse-magnetic (TM) surface wave on the tip. The analytical solution for the TM fields in paraboloidal coordinates consists of products of regular and irregular Coulomb wave functions. The width of the tip is much smaller than the skin depth so interior and exterior solutions are required and a summation of the products is required to satisfy the boundary conditions at the surface of the tip. The simulations are consistent with the analytical solution and show that there is a quasi-stationary region near the apex, a transition region where the surface waves are formed, and the far-field where the waves propagate outward on the tip.

  9. Laser-assisted ignition and combustion characteristics of consolidated aluminum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Saceleanu, Florin; Wen, John Z., E-mail: john.wen@uwaterloo.ca [University of Waterloo, Department of Mechanical and Mechatronics Engineering (Canada); Idir, Mahmoud; Chaumeix, Nabiha [Institut de Combustion, Aérothermique, Réactivité et Environnement, UPR3021 du CNRS-INSIS (France)

    2016-11-15

    Aluminum (Al) nanoparticles have drawn much attention due to their high energy density and tunable ignition properties. In comparison with their micronscale counterpart, Al nanoparticles possess large specific surface area and low apparent activation energy of combustion, which reduce ignition delay significantly. In this paper, ignition and subsequently burning of consolidated Al nanoparticle pellets are performed via a continuous wave (CW) argon laser in a closed spherical chamber filled with oxygen. Pellets are fabricated using two types of nanoparticle sizes of 40–60 and 60–80 nm, respectively. A photodiode is used to measure the ignition delay, while a digital camera captures the location of the flame front. It is found that for the 40–60-nm nanoparticle pellets, ignition delay reduces with increasing the oxygen pressure or using the higher laser power. Analysis of the flame propagation rate suggests that oxygen diffusion is an important mechanism during burning of these porous nanoparticle pellets. The combustion characteristics of the Al pellets are compared to a simplified model of the diffusion-controlled oxidation mechanism. While experimental measurements of pellets of 40–60 nm Al particles agree with the computed diffusion-limiting mechanism, a shifted behavior is observed from the pellets of 60–80 nm Al particles, largely due to the inhomogeneity of their porous structures.

  10. Results of Femtosecond Laser-Assisted Descemet Stripping Automated Endothelial Keratoplasty

    Directory of Open Access Journals (Sweden)

    Mohamed H. Hosny

    2017-01-01

    Full Text Available Purpose. To evaluate femtosecond laser in DSAEK surgery as an improvement to manual DSAEK. Settings. Department of Ophthalmology, Cairo University. Design. A retrospective observational clinical study. Methods. 20 eyes with SBK and Fuchs’ dystrophy underwent a Femto-assisted DSAEK by laser cutting of two matching posterior stromal discs in the recipient and donor corneas and then fitting the donor disc in the posterior corneal defect of the recipient using Busin’s glide or Terry forceps. Results. Corneal thickness decreased significantly from a mean of 900-micron preoperative values (900.7 m to 562 m postoperatively. Evidence of side healing was documented by OCT. One patient had a double AC, one patient had an air interface entrapment “Double Bubble,” one patient had a fungal infection and was treated by a therapeutic penetrating keratoplasty, and one patient had a CMO. Conclusion. Femtolaser-assisted DSAEK may be superior to manual techniques as it offers better centration, thinner graft/host complex, earlier corneal detergecense, and stronger healing. This study was registered at Researchregistry.com with a UID: researchregistry2274.

  11. Laser systems for ablative fractional resurfacing

    DEFF Research Database (Denmark)

    Paasch, Uwe; Haedersdal, Merete

    2011-01-01

    Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment of a var......Ablative fractional resurfacing (AFR) creates microscopic vertical ablated channels that are surrounded by a thin layer of coagulated tissue, constituting the microscopic treatment zones (MTZs). AFR induces epidermal and dermal remodeling, which raises new possibilities for the treatment...... ablative laser systems. Fractionated CO(2) (10,600-nm), erbium yttrium aluminum garnet, 2940-nm and yttrium scandium gallium garnet, 2790-nm lasers are available. In this article, we present an overview of AFR technology, devices and histopathology, and we summarize the current clinical possibilities...

  12. Femtosecond laser-assisted keratoplasty in a child with corneal opacity:case report

    Directory of Open Access Journals (Sweden)

    E. Yu. Markova

    2014-07-01

    Full Text Available Corneal opacities are the fourth cause of blindness world-wide. Over the past two centuries, various corneal transplantation (i.e., keratoplasty methods have been developed and improved. Nowadays, femtolaserssisted keratoplasty is one of most promising techniques. Femtosecond laser have several advantages that provide additional surgical benefits. Among them, no thermal injury, the ability to cut deeply on a single plane and to perform various corneal profiles should be mentioned. In children, corneal disorders are of special importance while femtosecondassisted keraatoplasty case reports are rare. Here, we describe femtosecond laserssisted penetrating keratoplasty in a girl with a rough central corneal opacity.

  13. Incubation behavior of silicon nanowire growth investigated by laser-assisted rapid heating

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Sang-gil; Kim, Eunpa; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Allen, Frances I.; Minor, Andrew M. [Department of Materials Science and Engineering, University of California, Berkeley, California 94720-1740 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Hwang, David J. [Department of Mechanical Engineering, Stony Brook University, Stony Brook, New York 11794 (United States)

    2016-08-15

    We investigate the early stage of silicon nanowire growth by the vapor-liquid-solid mechanism using laser-localized heating combined with ex-situ chemical mapping analysis by energy-filtered transmission electron microscopy. By achieving fast heating and cooling times, we can precisely determine the nucleation times for nanowire growth. We find that the silicon nanowire nucleation process occurs on a time scale of ∼10 ms, i.e., orders of magnitude faster than the times reported in investigations using furnace processes. The rate-limiting step for silicon nanowire growth at temperatures in the vicinity of the eutectic temperature is found to be the gas reaction and/or the silicon crystal growth process, whereas at higher temperatures it is the rate of silicon diffusion through the molten catalyst that dictates the nucleation kinetics.

  14. Femtosecond laser-assisted keratoplasty in a child with corneal opacity:case report

    Directory of Open Access Journals (Sweden)

    E. Yu. Markova

    2014-01-01

    Full Text Available Corneal opacities are the fourth cause of blindness world-wide. Over the past two centuries, various corneal transplantation (i.e., keratoplasty methods have been developed and improved. Nowadays, femtolaserssisted keratoplasty is one of most promising techniques. Femtosecond laser have several advantages that provide additional surgical benefits. Among them, no thermal injury, the ability to cut deeply on a single plane and to perform various corneal profiles should be mentioned. In children, corneal disorders are of special importance while femtosecondassisted keraatoplasty case reports are rare. Here, we describe femtosecond laserssisted penetrating keratoplasty in a girl with a rough central corneal opacity.

  15. Micro-PIV quantification of capillary blood flow redistribution caused by laser-assisted vascular occlusion

    Science.gov (United States)

    Kurochkin, Maxim A.; Stiukhina, Elena S.; Fedosov, Ivan V.; Postnov, Dmitry E.; Tuchin, Valery V.

    2016-04-01

    We propose μPIV-based technique for quantitative assessment of blood flow redistribution in microcirculatory networks. Our approach is based on per-segment averaging of measured quantities so we can avoid most of problems that are typical for point-wise measurements. The key point of our technique is the digital processing algorithms of recorded data that include: capillary network axial line construction; interrogation regions centering; blood flow velocity local estimate using PIV approach; blood flow velocity calculation by means of averaging over entire vessel segment; the calculation of blood volume flow rate map. We illustrate the application of developed technique with in vivo measurements and blood flow velocity map reconstruction for chorioallantoic membrane (CAM) of chicken embryo, in which the local vascular occlusion was produced using continuous wave laser light irradiation..

  16. Ar+ and CuBr laser-assisted chemical bleaching of teeth: estimation of whiteness degree

    Science.gov (United States)

    Dimitrov, S.; Todorovska, Roumyana; Gizbrecht, Alexander I.; Raychev, L.; Petrov, Lyubomir P.

    2003-11-01

    In this work the results of adaptation of impartial methods for color determination aimed at developing of techniques for estimation of human teeth whiteness degree, sufficiently handy for common use in clinical practice are presented. For approbation and by the way of illustration of the techniques, standards of teeth colors were used as well as model and naturally discolored human teeth treated by two bleaching chemical compositions activated by three light sources each: Ar+ and CuBr lasers, and a standard halogen photopolymerization lamp. Typical reflection and fluorescence spectra of some samples are presented; the samples colors were estimated by a standard computer processing in RGB and B coordinates. The results of the applied spectral and colorimetric techniques are in a good agreement with those of the standard computer processing of the corresponding digital photographs and complies with the visually estimated degree of the teeth whiteness judged according to the standard reference scale commonly used in the aesthetic dentistry.

  17. New experimental setup for boron isotopes separation by laser assisted retardation of condensation method

    Energy Technology Data Exchange (ETDEWEB)

    Lyakhov, K. A.; Lee, H. J. [Institute for Nuclear Science and Technology, Jeju (Korea, Republic of)

    2013-05-15

    Proposed static model corresponds to the two-cycle iterative scheme for boron isotopes separation. This rather simple model helps to understand combined action of all important parameters and relations between them on boron isotopes separation by SILARC method. These parameters include carrier gas choice, molar fraction at what BCl{sub 3} gas is dissolved in carrier gas, laser intensity, providing minimum of energy expenses and the largest output, optimal gas pressure and temperature in backing and downstream chambers, optimal irradiation cell and skimmer chamber dimensions, optimal nozzle throughput. It was suggested a method for finding optimal values of these parameters based on global minimum or energy spent on production of unit of isotope, which is analog of Separative Work Unit (SWU). It was shown that the most optimal carrier gas, corresponding to this minimum, among other considered-N{sub 2},NO{sub 2},SF{sub 6}, is Ar. Restriction on the maximal irradiation chamber length, caused by dimerization rate, is also considered. Two types of industrial scale irradiation cells are compared. The first one has the only large throughput slit nozzle, while the second one has numerous small nozzles arranged in parallel arrays for better overlap with laser beam. It is shown that the last one outperforms the former one significantly. We calculated that our experimental setup, provided argon is used as a carrier gas, can yield ∼50mg/hr of boron-10. It is interesting to compare this production rate with traditional method of industrial boron isotopes separation by low temperature distillation, Ref. In this method production rate is practically the same, but energy expenses per separated isotope are substantially smaller: ∼1 eV/atom instead of ∼10{sup 3} eV/atom as for SILARC method. The largest fraction of energy expenses in our SILARC-based method comes from compressor operation.

  18. Laser-Assisted Indocyanine Green Angiography Aids in the Reconstruction of Gustilo Grade IIIB Open Lower-Limb Fractures.

    Science.gov (United States)

    Koshimune, Seijiro; Shinaoka, Akira; Ota, Tomoyuki; Onoda, Satoshi; Kimata, Yoshihiro

    2017-02-01

    Background The treatment of trauma to the lower extremities often carries a high risk of complications. To the best of our knowledge, no study has been published regarding the treatment of open lower-limb fractures using laser-assisted indocyanine green angiography (LA-ICG). Here we retrospectively evaluated LA-ICG-based therapeutic interventions and reported the use of LA-ICG and its results in this application. Patients and Methods Between January 2011 and December 2015, a total of 23 cases with Gustilo grade IIIB open lower-limb fractures were investigated. LA-ICG was used to demonstrate the presence of necrotic tissue and determine the range of debridement. We compared 13 patients treated using LA-ICG from 2013 to 2015 with 10 patients treated without LA-ICG from 2010 to 2013. We reviewed tissue necrosis and other outcomes of these patients. Results The tissue necrosis rate in the LA-ICG-used group was significantly lower than that in the LA-ICG-free group. There were also significant differences in the average number of instances of tissue necrosis per patient, debridements, and deep-site infections. There was no flap loss. Conclusion By using LA-ICG, not only plastic surgeons but also clinicians in all associated departments including orthopedics can perform early reliable debridement and share in trauma treatment planning. We will continue to accumulate similar cases and hope to further improve LA-ICG techniques. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  19. Femtosecond Laser-Assisted LASIK With and Without the Adjuvant Use of Mitomycin C to Correct Hyperopia.

    Science.gov (United States)

    Garcia-Gonzalez, Montserrat; Iglesias-Iglesias, MariLuz; Drake Rodriguez-Casanova, Pilar; Gros-Otero, Juan; Teus, Miguel A

    2018-01-01

    To compare the visual and refractive results of femtosecond laser-assisted LASIK (FS-LASIK) with and without the adjuvant use of mitomycin C (MMC) to correct hyperopia. A total of 152 consecutive hyperopic eyes were included in this retrospective, observational cohort study, comparing 76 eyes treated with FS-LASIK + MMC with 76 age- and refraction-matched eyes treated with FS-LASIK without MMC. Visual and refractive results were evaluated 1 day, 1 week, and 1, 3, 6, and 15 months postoperatively. Preoperative mean spherical equivalent was +3.27 diopters (D) versus +3.50 D in the MMC and no MMC groups, respectively (P > .05). Three months postoperatively, uncorrected distance visual acuity was significantly better in the MMC group (0.93 ± 0.2) than in the no MMC group (0.87 ± 0.2) (P = .01). The residual spherical equivalent was significantly lower in the MMC group (+0.18 ± 0.40 D) than in the no MMC group (+0.42 ± 0.50 D) (P = .01). Fifteen months postoperatively, including re-treated eyes, no significant differences were found in uncorrected distance visual acuity, corrected distance visual acuity, and residual refraction. Slightly better outcomes were found in the MMC group in terms of efficacy, safety, and predictability; however, these small differences were not statistically significant. The incidence of re-treatments during the 15-month follow-up was significantly lower in the MMC group than in the no MMC group (6.6% vs 10.5%, respectively) (P = .01). FS-LASIK with or without the intraoperative use of MMC is safe and effective to correct hyperopia. However, slightly better refractive outcomes and a lower incidence of re-treatments were observed when intraoperative MMC was used, at least in a 15-month follow-up. [J Refract Surg. 2018;34(1):23-28.]. Copyright 2018, SLACK Incorporated.

  20. A powerful method for transcriptional profiling of specific cell types in eukaryotes: laser-assisted microdissection and RNA sequencing.

    Directory of Open Access Journals (Sweden)

    Marc W Schmid

    Full Text Available The acquisition of distinct cell fates is central to the development of multicellular organisms and is largely mediated by gene expression patterns specific to individual cells and tissues. A spatially and temporally resolved analysis of gene expression facilitates the elucidation of transcriptional networks linked to cellular identity and function. We present an approach that allows cell type-specific transcriptional profiling of distinct target cells, which are rare and difficult to access, with unprecedented sensitivity and resolution. We combined laser-assisted microdissection (LAM, linear amplification starting from <1 ng of total RNA, and RNA-sequencing (RNA-Seq. As a model we used the central cell of the Arabidopsis thaliana female gametophyte, one of the female gametes harbored in the reproductive organs of the flower. We estimated the number of expressed genes to be more than twice the number reported previously in a study using LAM and ATH1 microarrays, and identified several classes of genes that were systematically underrepresented in the transcriptome measured with the ATH1 microarray. Among them are many genes that are likely to be important for developmental processes and specific cellular functions. In addition, we identified several intergenic regions, which are likely to be transcribed, and describe a considerable fraction of reads mapping to introns and regions flanking annotated loci, which may represent alternative transcript isoforms. Finally, we performed a de novo assembly of the transcriptome and show that the method is suitable for studying individual cell types of organisms lacking reference sequence information, demonstrating that this approach can be applied to most eukaryotic organisms.

  1. Combined femtosecond laser-assisted intracorneal ring segment implantation and corneal collagen cross-linking for correction of keratoconus

    Directory of Open Access Journals (Sweden)

    Ibrahim O

    2016-03-01

    Full Text Available Osama Ibrahim,1 Ahmed Elmassry,1 Amr Said,1,2 Moones Abdalla,2 Hazem El Hennawi,1 Ihab Osman1 1Department of Ophthalmology, Alexandria University, Alexandria, Egypt; 2Roayah Vision Correction Center, Alexandria, Egypt Purpose: To assess the safety, predictability, and effectiveness of Keraring intrastromal corneal ring segments (ICRS insertion assisted by femtosecond laser and corneal collagen cross-linking (CXL for keratoconus correction. Patients and methods: In this prospective, noncomparative, and interventional case series, 160 eyes of 100 adult keratoconus patients with poor best-corrected visual acuity (BCVA (less than 0.7 and intolerance to contact lens wear were included. Patients underwent femtosecond laser-assisted placement of ICRS and CXL. All patients were examined for a complete ophthalmological test: uncorrected visual acuity (UCVA, BCVA, spherical equivalent, keratometry (K1-flat and K2-steep, pachymetry, and Scheimpflug imaging with the Pentacam at 1 week and at 1, 3, and 6 months postoperatively. Results: At 6 months, a significant difference was observed (P<0.001 in mean UCVA and BCVA from 0.92±0.677 and 0.42±0.600 logMAR preoperatively to 0.20±0.568 and 0.119±0.619 logMAR, respectively. Mean spherical equivalent refractions were significantly lower (P<0.001 at 6 months. Mean keratometry (K also significantly reduced (P<0.001 from 50.93±5.53 D (K1-flat and 55.37±5.76 D (K2-steep to 47.32±4.61 and 51.08±5.38 D, respectively. In terms of pachymetry, no significant difference was observed preoperatively versus postoperatively (P=1.000. Conclusion: Keraring ICRS insertion assisted by femtosecond laser and corneal CXL provided significant improvement in visual acuity, spherical equivalent, and keratometry, which suggests that it may be effective, safe, and predictable for keratoconus correction. Keywords: keratometry, pachymetry, keratectesia, Pentacam, irregular astigmatism

  2. Ruby laser-assisted depilation: The mode of action and potential ways of improved outcome

    Science.gov (United States)

    Topping, Adam Partington

    Aim - To improve efficacy and lessen side effects resulting from normal mode ruby laser (NMRL)-assisted depilation via a greater understanding of its mode of action and the development of novel methods of reducing associated epidermal damage. Employing a thermal imaging camera and ex vivo hair-bearing skin, the targets for the NMRL (pulse duration 900 musec and spot size 7 mm) were defined, the temperatures reached and the heat dissipation rates determined. Production of heat was confined to the hair follicles, with the peak temperatures reached varying considerably between hairs within the same treatment area and also between individuals. Histological assessment for a known indicator of cellular damage (p53 expression) identified the sites and extent of damage, which correlated with the peak temperatures measured. An energy meter was used to detect the penetration of NMRL light through ex vivo skin, which was found to be deeper than previously theorised. The black-haired mouse (C57B1/10) was assessed both macroscopically and histologically and found to be an acceptable animal model of NMRL depilation and associated epidermal damage. Attempts to reduce the epidermal damage by simply stopping the light reaching the epidermis using a chromophore block were assessed. Chromophore did indeed reduce the amount of epidermal damage detected in laser-irradiated ex vivo human skin, whereas in contrast it increased the wounding seen in the much thinner skin of the mouse. Nevertheless the mouse model showed that this technique did not affect the depilation efficacy. An alternative method of reducing epidermal damage using induction of the cells' intrinsic protective mechanisms (heat shock proteins, HSP) was assessed using cultured keratinocytes and the mouse model. Primarily, the sub-lethal temperature optimum for HSP expression in human keratinocytes was determined, then an in vitro model of NMRL-associated epidermal damage was established and the heat pre-treatment assessed

  3. Pseudophakic astigmatism reduction with femtosecond laser-assisted corneal arcuate incisions: a pilot study

    Directory of Open Access Journals (Sweden)

    Blehm C

    2017-01-01

    Full Text Available Clayton Blehm,1 Richard Potvin2 1Gainesville Eye Associates, Gainesville, GA, 2Science in Vision, Akron, NY, USA Purpose: The aim of this study was to assess the effectiveness of the Verion-LenSx guided arcuate incision technique to reduce refractive astigmatism in a pseudophakic population. Patients and methods: A prospective single-arm study was conducted in which one or both eyes of subjects required reduction of 1.0–2.0 D of refractive astigmatism after previous cataract surgery or refractive lens exchange. The surgeon used the refractive cylinder in the eye and the Woodcock astigmatism nomogram for preoperative planning, while the LenSx femtosecond laser with the Verion Image Guided System was used to create all arcuate incisions. The primary outcome measure was the uncorrected monocular distance visual acuity (UCVA. Secondary outcome measures included the change in corneal astigmatism, the change in refractive astigmatism, the best-corrected visual acuity and spectacle independence at distance from preoperative stage to 1 month and 2 months postoperatively. Results: Twenty-eight eyes of 18 subjects were treated. The best-corrected visual acuity at the 2-month postoperative (PO stage was not statistically significantly different from the preoperative visual acuity (0.02 logarithm of the minimum angle of resolution [logMAR] in both cases, P>0.05. Uncorrected visual acuity was statistically significantly better at the 2-month PO stage relative to the preoperative value (0.14 versus 0.34 logMAR, P<0.01. The mean change in refractive cylinder from the preoperative stage to the 2-month PO stage was 1.0 D. At the 2-month PO stage, two-thirds of the subjects (12/18 reported that they did not use glasses for distance vision and that their spectacle use for distance vision at 2 months was “lower” or “much lower” than the preoperative stage; in 71% of eyes (20/28, the residual refractive cylinder was ≤0.50 D. Vector changes in

  4. Laser-Assisted Atom Probe Tomography of Deformed Minerals: A Zircon Case Study.

    Science.gov (United States)

    La Fontaine, Alexandre; Piazolo, Sandra; Trimby, Patrick; Yang, Limei; Cairney, Julie M

    2017-04-01

    The application of atom probe tomography to the study of minerals is a rapidly growing area. Picosecond-pulsed, ultraviolet laser (UV-355 nm) assisted atom probe tomography has been used to analyze trace element mobility within dislocations and low-angle boundaries in plastically deformed specimens of the nonconductive mineral zircon (ZrSiO4), a key material to date the earth's geological events. Here we discuss important experimental aspects inherent in the atom probe tomography investigation of this important mineral, providing insights into the challenges in atom probe tomography characterization of minerals as a whole. We studied the influence of atom probe tomography analysis parameters on features of the mass spectra, such as the thermal tail, as well as the overall data quality. Three zircon samples with different uranium and lead content were analyzed, and particular attention was paid to ion identification in the mass spectra and detection limits of the key trace elements, lead and uranium. We also discuss the correlative use of electron backscattered diffraction in a scanning electron microscope to map the deformation in the zircon grains, and the combined use of transmission Kikuchi diffraction and focused ion beam sample preparation to assist preparation of the final atom probe tip.

  5. Electrical transport properties of MoO{sub 3} thin films prepared by laser assisted evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Carreno, L.D.; Pardo, A.; Zuluaga, M.; Torres, J.; Alfonso, J.E. [Group of Materials with Technological Applications, GMAT, Physics Department, Universidad Nacional de Colombia, Bogota (Colombia); Cortes-Bracho, O.L. [Group of Materials with Technological Applications, GMAT, Physics Department, Universidad Nacional de Colombia, Bogota (Colombia); Electronic Engineering Department, Universidad Nacional de Colombia, Bogota (Colombia)

    2007-07-01

    In the present paper the growth of MoO{sub 3} thin films on common glass substrates are described. The films were prepared by evaporation of a MoO{sub 3} target with a CO{sub 2} laser (10.6 {mu}m), operating in the continuous wave mode. The effect of substrate temperature on the crystallographic structure and electrical properties of MoO{sub 3} thin films was studied. The chemical composition of the different species formed on the films surface was obtained by X-ray photoelectron spectroscopy (XPS) and the crystalline structure was studied with X-ray diffraction (XRD). The electrical conductivity of the films was determined using the standard four-points method. Conductivity of the films varied from de 10{sup -9} to 10{sup -5} ({omega}cm){sup -1} in the 300-600 K temperature range. Arrhenius-type plots for the electrical conductivity indicate the presence of at least two different conduction mechanisms. The I-V characteristic curve shows an ohmic behavior only in the 4.5-60 V range. Outside this interval the I-V curve has a behavior described by a power law. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Contact Pattern Analysis: Simulation of a Laser-Assisted Thermographic Approach

    Science.gov (United States)

    Prekel, H.; Stroebel, G.; Lipinski, R.; Goch, G.

    2016-08-01

    The contact pattern, defined as the area where gear teeth come into contact during their meshing, is a crucial quality feature of gears. If the size and location of the contact pattern are wrong, the gear meshing properties can be significantly affected (e.g., lifetime, noise). Despite several disadvantages, the so-called "paste method" is established as a method to analyse contact patterns. Here, a new measuring approach is examined using the Finite Elements Method (FEM). It is based on the heating-up of one tooth flank with a powerful laser, a subsequent partial transfer of the heat to a meshing tooth of the second gear wheel and finally capturing the heat distribution on that flank as an infrared image shortly afterwards. The thermal image should correspond to the contact pattern of that individual combination of teeth. A numerical analysis shows that at medium- and large-sized gears the achievable temperature increase will be high enough to be detected with modern infrared cameras.

  7. Blood pressure change during phacoemulsification and femtosecond laser-assisted cataract surgery

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    Hung-Yuan Lin

    2016-11-01

    Full Text Available AIM: To evaluate blood pressure (BP changes during phacoemulsification (PC and femtosecond laser (FSL-assisted cataract surgery. METHODS: A retrospective chart review was performed for all patients who received traditional phacoemulsification surgery (PC group and FSL-assisted cataract surgery (FS group from July 2013 to December 2014. Totally 206 eyes from 133 patients receiving the two types of procedures were included. Patient characteristics (age, gender, and hypertension history, pre- and post-operative BPs were collected. RESULTS: The pro-operative systolic and diastolic BPs (mm Hg were 124.89±20.48 vs 126.98±16.85, and 71.88±9.81 vs 73.56±10.03, in PC and FS groups, respectively. While the post-operative systolic and diastolic BPs (mm Hg were 130.13±22.59 vs 134.77±17.52, and 73.41±11.62 vs 78.89±12.2, in PC and FS groups, respectively. Paired-sample t-tests showed obvious systolic and diastolic BP elevations in FS group after surgery (P=0.001 and 0.007 and no reliability in PC group (P=0.094 and 0.359. A linear regression model revealed systolic and diastolic BP elevations, which were related to longer surgical times for FS group (P=0.008 and 0.021. Age, gender, and hypertension history were not correlated with blood pressure elevation in either group. CONCLUSION: BP increases but at a limited level after FSL-assisted cataract surgery compared to traditional phacoemulsificationKEYWORDS: cataract surgery; blood pressure; femtosecond-assisted cataract surgery; phacoemulsification

  8. Laser-assisted strategy for reflux abolition in a modified CHIVA approach

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    Sergio Gianesini

    2015-06-01

    Full Text Available The aim of this study was to assess feasibility and efficacy of an endovenous laser (EL assisted saphenous-sparing strategy in chronic venous disease (CVD. Fourteen CVD patients (C2,3,4s Ep As Pr1,2,3 underwent a saphenofemoral junction (SFJ treatment by EL just from below the superficial epigastric vein downward for a limited tract, together with a flush ligation of the incompetent tributaries of the great saphenous vein (GSV along the leg. The following GSV parameters were assessed 15 cm below the SFJ: reflux time, caliber, peak systolic velocity (PSV, end diastolic velocity (EDV, resistance index (RI. Venous clinical severity score and the Clinical, Etiological, Anatomical, and Pathophysio logical (CEAP classification clinical classes were assessed. At 1 year follow up 3 cases were considered failures because of a GSV thrombosis, even if they presented a GSV recanalization with a laminar flow within at the 2 years follow-up. Eleven procedures succeeded because neither minor nor major peri-procedural complications were reported, apart 2 cases of self-healing bruising. In these last 11 cases the procedure led to a GSV reflux suppression (from 3.1±0.4 s to a retrograde laminar draining flow, to a GSV caliber reduction (from 9.4±0.5 to 3.1±0.2 cm, P<0.001, to a PSV reduction (from 50.2±4.6 to 18.4±3.5 cm/s, P<0.001, to a RI reduction (from 0.9±0.2 to 0.51±0.2, P<0.005 and to an oscillatory flow suppression (EDV from -8.9±1.6 to 6.2±2.3 cm/s, P<0.001. Both CEAP and venous clinical severity score improved from 3 to 1 (P<0.001 and from 7±2 to 2±1 (P<0.05, respectively. The GSV flow reappeared below the shrunk tract draining into the re-entry perforator. Sapheno-femoral reflux suppression can be obtained by just a GSV segmental closure. An almost 80% of success rate of the present investigation paves the way for an even wider diffusion of endovenous techniques, moreover erasing the surgical requirements for those who would like to perform

  9. Effect of laser energy, substrate film thickness and bioink viscosity on viability of endothelial cells printed by Laser-Assisted Bioprinting

    Science.gov (United States)

    Catros, Sylvain; Guillotin, Bertrand; Bačáková, Markéta; Fricain, Jean-Christophe; Guillemot, Fabien

    2011-04-01

    Biofabrication of three dimensional tissues by Laser-Assisted Bioprinting (LAB) implies to develop specific strategies for assembling the extracellular matrix (ECM) and cells. Possible strategies consist in (i) printing cells onto or in the depth of ECM layer and/or (ii) printing bioinks containing both cells and ECM-like printable biomaterial. The aim of this article was to evaluate combinatorial effects of laser pulse energy, ECM thickness and viscosity of the bioink on cell viability. A LAB workstation was used to print Ea.hy926 endothelial cells onto a quartz substrate covered with a film of ECM mimicking Matrigel™. Hence, effect of laser energy, Matrigel™ film thickness and bioink viscosity was addressed for different experimental conditions (8-24 μJ, 20-100 μm and 40-110 mPa s, respectively). Cell viability was assessed by live/dead assay performed 24 h post-printing. Results show that increasing the laser energy tends to augment the cell mortality while increasing the thickness of the Matrigel™ film and the viscosity of the bioink support cell viability. Hence, critical printing parameters influencing high cell viability have been related to the cell landing conditions and more specifically to the intensity of the cell impacts occurring at the air-ECM interface and at the ECM-glass interface.

  10. Performance Improvement of Microcrystalline p-SiC/i-Si/n-Si Thin Film Solar Cells by Using Laser-Assisted Plasma Enhanced Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Hsin-Ying Lee

    2014-01-01

    Full Text Available The microcrystalline p-SiC/i-Si/n-Si thin film solar cells treated with hydrogen plasma were fabricated at low temperature using a CO2 laser-assisted plasma enhanced chemical vapor deposition (LAPECVD system. According to the micro-Raman results, the i-Si films shifted from 482 cm−1 to 512 cm−1 as the assisting laser power increased from 0 W to 80 W, which indicated a gradual transformation from amorphous to crystalline Si. From X-ray diffraction (XRD results, the microcrystalline i-Si films with (111, (220, and (311 diffraction were obtained. Compared with the Si-based thin film solar cells deposited without laser assistance, the short-circuit current density and the power conversion efficiency of the solar cells with assisting laser power of 80 W were improved from 14.38 mA/cm2 to 18.16 mA/cm2 and from 6.89% to 8.58%, respectively.

  11. Outcomes study between femtosecond laser-assisted cataract surgery and conventional phacoemulsification surgery using an active fluidics system

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    Hida WT

    2017-09-01

    Full Text Available Wilson Takashi Hida,1–4 Patrick Frenzel Tzelikis,1–3 César Vilar,1,2 Mario Augusto Pereira Dias Chaves,1,2,5 Antônio Francisco Pimenta Motta,1–3 Pedro Carlos Carricondo,1–3 Bruna Vieira Ventura,1,2,4,6 Renato Ambrosio Junior,1–3 Walton Nosé,1,2,4 Milton Ruiz Alves1–3 1Department of Cataract of Brasília Ophthalmology Hospital (HOB, Brasília, Federal District, 2Renato Ambrosio Research Center (CEORA, Brasília, Federal District, 3Department of Ophthalmology of São Paulo University School of Medicine, (FM-USP, São Paulo, 4Department of Ophthalmology of São Paulo Federal University (UNIFESP School of Medicine, São Paulo, 5ProVisão Hospital, João Pessoa, Paraíba, 6Pernanbuco Eye Hospital (HOPE, Recife, Pernambuco, Brazil Purpose: The purpose of this study was to compare intraoperative parameters between femtosecond laser-assisted cataract surgery (FLACS and conventional phacoemulsification using Centurion® Vision System with Active Fluidics. Setting: This study was performed at Brasília Ophthalmologic Hospital, Brasília, Federal District, Brazil. Patients and methods: This was a prospective randomized comparative study. Patients with the diagnosis of cataract and surgical extraction programmed were divided into two groups: conventional phacoemulsification and FLACS. Intraoperative data were collected and submitted for statistical analysis. Results: A total of 400 eyes were enrolled, 200 in each group. There were no surgical complications. Groups were statistically equivalent in age and nucleus density. Cumulative dissipated energy and torsional time were significantly reduced in the FLACS group. Conventional surgery had less fluid usage, total case time and aspiration (ASP time. Conclusion: FLACS with Active Fluidics System can reduce the ultrasound energy use during cataract surgery, in spite of increasing case time, fluid usage and ASP time. Keywords: FLACS, ultrasound, aspiration

  12. Application of Corvis ST to evaluate the effect of femtosecond laser-assisted cataract surgery on corneal biomechanics

    Science.gov (United States)

    Wei, Yinjuan; Xu, Lingxiao; Song, Hui

    2017-01-01

    The aim of the present study was to evaluate the effects of femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification on corneal biomechanics using corneal visualization Scheimpflug technology. The medical records of 50 eyes from 50 patients who received phacoemulsification and intraocular lens implantation because of age-related factors between June 2014 and September 2014 were retrospectively analyzed. FLACS was used in 12 eyes (FLACS group), and conventional phacoemulsification in 38 eyes (PHACO group). The evaluation of corneal biomechanical parameters included the first/second applanation time (A-time1/A-time2), the first/second applanation length (A-length1/A-length2), corneal velocity during the first/second applanation moment (Vin/Vout), highest concavity time, highest concavity-radius (HC-radius), peak distance (PD), deformation amplitude (DA), central corneal thickness (CCT), and intraocular pressure (IOP). The differences in A-length1/A-length2, IOP, CCT, PD, and DA were significant in the PHACO group between those before, 1 week after, and 1 month after surgery. No significant differences in corneal biomechanical parameters were found between those at 1 month after surgery and before surgery. There were significant differences in IOP and CCT in the FLACS group between those before, 1 week after, and 1 month after surgery. There were no significant differences in the other corneal biomechanical parameters. No significant differences were found in corneal biomechanical parameters between those 1 month after surgery and before surgery. There were significant differences in A-length1/A-length2, CCT, PD, and DA between the two groups at 1 week after surgery. There were no significant differences in corneal biomechanical parameters between the two groups at 1 month after surgery. In conclusion, the effect of FLACS on corneal biomechanics is smaller than that of phacoemulsification. The corneal biomechanical parameters are restored to

  13. Application of Corvis ST to evaluate the effect of femtosecond laser-assisted cataract surgery on corneal biomechanics.

    Science.gov (United States)

    Wei, Yinjuan; Xu, Lingxiao; Song, Hui

    2017-08-01

    The aim of the present study was to evaluate the effects of femtosecond laser-assisted cataract surgery (FLACS) and phacoemulsification on corneal biomechanics using corneal visualization Scheimpflug technology. The medical records of 50 eyes from 50 patients who received phacoemulsification and intraocular lens implantation because of age-related factors between June 2014 and September 2014 were retrospectively analyzed. FLACS was used in 12 eyes (FLACS group), and conventional phacoemulsification in 38 eyes (PHACO group). The evaluation of corneal biomechanical parameters included the first/second applanation time (A-time1/A-time2), the first/second applanation length (A-length1/A-length2), corneal velocity during the first/second applanation moment (Vin/Vout), highest concavity time, highest concavity-radius (HC-radius), peak distance (PD), deformation amplitude (DA), central corneal thickness (CCT), and intraocular pressure (IOP). The differences in A-length1/A-length2, IOP, CCT, PD, and DA were significant in the PHACO group between those before, 1 week after, and 1 month after surgery. No significant differences in corneal biomechanical parameters were found between those at 1 month after surgery and before surgery. There were significant differences in IOP and CCT in the FLACS group between those before, 1 week after, and 1 month after surgery. There were no significant differences in the other corneal biomechanical parameters. No significant differences were found in corneal biomechanical parameters between those 1 month after surgery and before surgery. There were significant differences in A-length1/A-length2, CCT, PD, and DA between the two groups at 1 week after surgery. There were no significant differences in corneal biomechanical parameters between the two groups at 1 month after surgery. In conclusion, the effect of FLACS on corneal biomechanics is smaller than that of phacoemulsification. The corneal biomechanical parameters are restored to

  14. Predictability and stability of laser-assisted subepithelial keratectomy with mitomycin C for the correction of high myopia.

    Science.gov (United States)

    Iu, Lawrence P L; Fan, Michelle C Y; Chen, Ivan N; Lai, Jimmy S M

    2017-06-01

    The purpose of this study was to evaluate the predictability and stability of laser-assisted subepithelial keratectomy (LASEK) with mitomycin C (MMC) in correction of high myopia (≤-6.0 diopters [D]) as compared to low-to-moderate myopia (>-6.0 D).This is a retrospective, comparative, cohort study which included 43 eyes of 43 consecutive patients who underwent LASEK with MMC in a private hospital in Hong Kong by a single surgeon. Twenty-five eyes had high myopia (mean spherical equivalent [SE] = -8.53 ± 1.82 D) and 18 eyes had low-to-moderate myopia (mean SE = -3.99 ± 1.37 D) before surgery.In terms of refractive predictability, mean SE was significantly better in eyes with preoperative low-to-moderate myopia than high myopia at 6 months (0.04 ± 0.23 vs 0.31 ± 0.52 D, P = .035). In terms of refractive stability, between 1 and 3 months, both groups had mean absolute change of SE of around 0.25 D. Between 3 and 6 months, preoperative low-to-moderate myopia group had significantly less absolute change of SE compared to high myopia group (0.07 vs 0.23 D, P = .003). More eyes with preoperative high myopia changed SE by more than 0.25 D than those with low-to-moderate myopia between 3 and 6 months (32.0% vs 5.6%, P = .057).In conclusion, LASEK with MMC is more unpredictable and unstable in correction of high myopia than low-to-moderate myopia. The refractive outcome of most low-to-moderate myopia correction stabilizes at 3 months. Stability is not achieved until after 6 months in high myopia correction.

  15. Investigations of the potential functions of weakly bound diatomic molecules and laser-assisted excitive Penning ionization

    Energy Technology Data Exchange (ETDEWEB)

    Goble, J.H. Jr.

    1982-05-01

    Three variations on the Dunham series expansion function of the potential of a diatomic molecule are compared. The differences among these expansions lie in the choice of the expansion variable, lambda. The functional form of these variables are lambda/sub s/ = l-r/sub e//r for the Simon-Parr-Finlan version, lambda/sub T/ - 1-(r/sub e//r)/sup p/ for that of Thakkar, and lambda/sub H/ = 1-exp(-rho(r/r/sub e/-1) for that of Huffaker. A wide selection of molecular systems are examined. It is found that, for potentials in excess of thirty kcal/mole, the Huffaker expansion provides the best description of the three, extrapolating at large internuclear separation to a value within 10% of the true dissociation energy. For potentials that result from the interaction of excited states, all series expansions show poor behavior away from the equilibrium internuclear separation of the molecule. The series representation of the potentials of weakly bound molecules are examined in more detail. The ground states of BeAr/sup +/, HeNe/sup +/, NaAr, and Ar/sub 2/ and the excited states of HeNe+, NaNe, and NaAr are best described by the Thakkar expansion. Finally, the observation of laser-assisted excitive Penning ionization in a flowing afterglow is reported. The reaction Ar(/sup 3/P/sub 2/) + Ca + h nu ..-->.. Ar + Ca/sup +/(5p /sup 2/P/sub J/) + e/sup -/ occurs when the photon energy, h nu, is approximately equal to the energy difference between the metastable argon and one of the fine structure levels of the ion's doublet. By monitoring the cascade fluorescence of the above reaction and comparing it to the flourescence from the field-free process Ar(/sup 3/P/sub 2/) + Ca ..-->.. Ar + Ca/sup +/(4p /sup 2/P/sub J/) + e/sup -/ a surprisingly large cross section of 6.7 x 10/sup 3/ A/sup 2/ is estimated.

  16. Analysis of High-Power Diode Laser Heating Effects on HY-80 Steel for Laser Assisted Friction Stir Welding Applications

    Energy Technology Data Exchange (ETDEWEB)

    Wiechec, Maxwell; Baker, Brad; McNelley, Terry; Matthews, Manyalibo; Rubenchik, Alexander; Rotter, Mark; Beach, Ray; Wu, Sheldon

    2017-01-01

    In this research, several conditions of high power diode laser heated HY-80 steel were characterized to determine the viability of using such lasers as a preheating source before friction stir welding in order to reduce frictional forces thereby reducing tool wear and increasing welding speeds. Differences in microstructures within heat affected zones were identified at specific laser powers and traverse speeds. Vickers hardness values were recorded and analyzed to validate the formation of additional martensite in diode laser heated regions of HY-80 steel. Conditions that produced little to no additional martensite were identified and relationships among high power diode laser power, traverse speed, and martensite formation were determined. The development of heat affected zones, change in grain structure, and creation of additional martensite in HY-80 can be prevented through the optimization of laser amperage and transverse speed.

  17. A study on the edge chipping according to spindle speed and inclination angle of workpiece in laser-assisted milling of silicon nitride

    Science.gov (United States)

    Woo, Wan-Sik; Lee, Choon-Man

    2018-02-01

    Ceramics are difficult to machine due to their high hardness and brittleness. As an effective method for machining ceramics, laser-assisted machining (LAM) has been studied by many researchers. In particular, many studies of methods to improve the machinability of silicon nitride using LAM have been performed. However, there is little research on the effect of the inclination angle of the workpiece, because varying the angle increases the difficulty of controlling the laser preheating and tool path. This paper investigates the effect of preheating temperature, spindle speed and inclination angle of the workpiece on edge chipping of silicon nitride in an effort to obtain an enhanced surface finish using laser-assisted milling (LAMill). The machining conditions were determined by considering the parameters that can reduce edge chipping using related theory. Experimental results showed a reduction in edge chipping based on increases in preheating temperature, spindle speed and inclination angle of the workpiece. Also, by increasing the spindle speed and the inclination angle of the workpiece, surface roughness was decreased due to reduction in the cutting force. The energy efficiency of LAMill by comparing the specific cutting energy according to the machining conditions is analyzed.

  18. Pulsed laser ablation of LaSrCoO

    NARCIS (Netherlands)

    Span, E.A.F.; Roesthuis, Frank J.G.; Blank, David H.A.; Rogalla, Horst

    1999-01-01

    The ablation process of La0.5Sr0.5CoO3 by a spatial uniform 248 nm excimer laser beam has been characterized. Ablation rates, changes in the target surface morphology and composition have been studied as a function of the laser fluence. The dependence of the ablation rate on the laser fluence has

  19. Topical 0.1% Bromfenac Sodium for Intraoperative Miosis Prevention and Prostaglandin E2 Inhibition in Femtosecond Laser-Assisted Cataract Surgery.

    Science.gov (United States)

    Chen, Hui; Lin, Haotian; Chen, Wan; Zhang, Bo; Xiang, Wu; Li, Jing; Chen, Weirong

    2017-04-01

    The purpose of this study was to evaluate the effect of topical 0.1% bromfenac sodium, a nonsteroidal anti-inflammatory drug (NSAID), on intraoperative pupil dilation maintenance and prostaglandin E2 (PGE2) inhibition during femtosecond laser-assisted cataract surgery. Sixty patients (30 each in study and control groups) were included in this study. The patients received 0.1% bromfenac ophthalmic solution or control placebo twice a day for 3 days before surgery. Pupil size was measured at the initiation of femtosecond laser pretreatment and phacoemulsification. Aqueous humor was collected at the beginning of routine cataract surgery. PGE2 levels were measured with an enzyme-linked immunoassay. Laser flare photometry was measured preoperatively and at 1 day postoperatively. Compared with untreated patients, the change in pupil size and postoperative day 1 aqueous flare were significantly reduced throughout the operation in the patients treated with 0.1% bromfenac (P miosis, and reducing PGE2 levels.

  20. Comparison of the corneal biomechanical effects after small-incision lenticule extraction and Q value guided femtosecond laser-assisted laser in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Jun Zhang

    2016-04-01

    Full Text Available AIM:By comparing the changes of biomechanical properties of the cornea after small-incision lenticule extraction(SMILEand those after Q value guided femtosecond laser-assisted laser in situ keratomileusis(FSLASIK, to study the stability of biomechanical properties of the cornea after these two kinds of surgery and provide objective data for clinical operation.METHODS: Prospective comparative cases. One hundred and two cases(200 eyeswith myopia and myopic astigmatism were divided into 2 groups, 51 cases(100 eyesfor SMILE, and 51 cases(100 eyesfor Q value guided FS-LASIK. Corneal hysteresis(CHand the corneal resistance factor(CRFwere quantitatively assessed with the Ocular Response Analyzer(ORApreoperatively and 1d, 2wk, 1 and 3mo postoperatively.RESULTS: The decrease in CH and the CRF were statistically significant in both groups(PP>0.05. There were no statistically significant differences between the biomechanical changes in the two groups at any time(P>0.05.CONCLUSION: Both SMILE and Q value guided FS-LASIK can cause biomechanical decreases in the cornea. After 1d postoperatively, the decreases are nearly stable. There are no significant differences between the effect of SMILE and Q value guided FS-LASIK on the biomechanical properties of the cornea.

  1. Comparison of wavefront aberration changes in the anterior corneal surface after laser-assisted subepithelial keratectomy and laser in situ keratomileusis: preliminary study.

    Science.gov (United States)

    Buzzonetti, Luca; Iarossi, Giancarlo; Valente, Paola; Volpi, Marzia; Petrocelli, Gianni; Scullica, Luigi

    2004-09-01

    To compare changes in anterior corneal wavefront aberrations after myopic laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK). Institute of Ophthalmology, Catholic University, Rome, Italy. This prospective study included 36 eyes of 25 myopic patients: 18 eyes of 12 patients had LASEK and 18 eyes of 13 patients, LASIK. The topography data (CSO EyeMap, version 6.2) were used to calculate corneal aberrations with 3.0 mm and 7.0 mm pupils before and 3 months after surgery. Total corneal aberrations increased similarly after LASEK and LASIK with the 7.0 mm pupil but did not change with the 3.0 mm pupil. Coma-like and spherical-like aberrations changed similarly after both procedures, but spherical-like aberrations increased after LASEK with the 3.0 mm pupil (P.05, independent t test), in individual eyes with an achieved correction less than 7.50 diopters (D), spherical-like aberrations increased more after LASEK than after LASIK. In this preliminary study, myopic LASEK and LASIK changed total and higher-order corneal aberrations. In both procedures, changes in spherical-like aberrations were dependent on the achieved correction. However, in individual eyes, spherical-like aberrations increased more after LASEK than after LASIK for low-moderate achieved correction, suggesting that these procedures may induce the same optical changes in the anterior corneal surface in different ways.

  2. Laser ablation threshold of cultural heritage metals

    Science.gov (United States)

    Lorusso, A.; Nassisi, V.; Buccolieri, A.; Buccolieri, G.; Castellano, A.; Leo, L. S.; di Giulio, M.; Torrisi, L.; Caridi, F.; Borrielli, A.

    The present work has the purpose to evaluate experimentally the ablation threshold fluences of copper, silver, and their alloys in order to induce a safety laser cleaning of the metal artifacts avoiding damages to the bulkE We used two different pulsed lasers: a KrF excimer laser operating at 248 nm, 23 ns pulse duration and a Nd:YAG laser operating at 532 nm (second harmonic), 3 ns pulse. Preliminary experimental results about the laser cleaning of bronze coins will be reported. The laser cleaning consists on the reduction of the chlorine concentration from the surface of the coins. The laser cleaning, carried out by the KrF laser, provides a safe way of removing the chlorine concentration as the Energy Dispersive X-Ray Fluorescence analyses will demonstrate.

  3. Laser Ablation for Small Hepatocellular Carcinoma

    Directory of Open Access Journals (Sweden)

    Claudio Maurizio Pacella

    2011-01-01

    Full Text Available Hepatocellular carcinoma (HCC is one of the most common malignancies worldwide and is increasingly detected at small size (<5 cm owing to surveillance programmes in high-risk patients. For these cases, curative therapies such as resection, liver transplantation, or percutaneous ablation have been proposed. When surgical options are precluded, image-guided tumor ablation is recommended as the most appropriate therapeutic choice in terms of tumor local control, safety, and improvement in survival. Laser ablation (LA represents one of currently available loco-ablative techniques: light is delivered via flexible quartz fibers of diameter from 300 to 600 μm inserted into tumor lesion through either fine needles (21g Chiba needles or large-bore catheters. The thermal destruction of tissue is achieved through conversion of absorbed light (usually infrared into heat. A range of different imaging modalities have been used to guide percutaneous laser ablation, but ultrasound and magnetic resonance imaging are most widely employed, according to local experience and resource availability. Available clinical data suggest that LA is highly effective in terms of tumoricidal capability with an excellent safety profile; the best results in terms of long-term survival are obtained in early HCC so that LA can be proposed not only in unresectable cases but, not differently from radiofrequency ablation, also as the first-line treatment.

  4. Diode Laser Assisted Excision and Low Level Laser Therapy in the Management of Mucus Extravasation Cysts: A Case Series

    Science.gov (United States)

    Ahad, Abdul; Tandon, Shruti; Lamba, Arundeep Kaur; Faraz, Farrukh; Anand, Parimal; Aleem, Abdul

    2017-01-01

    Introduction: Mucus extravasation cyst is a commonly occurring lesion in oral cavity that may result from traumatic severance of a salivary gland duct with subsequent extravasation of mucus into fibrous connective tissue. After a conventional excision or marsupialization, recurrence is not uncommon. Diode laser offers an effective modality for management of such lesions. Case Reports: Four patients were referred with painless fluctuant swellings on labial and buccal mucosa. After recording history and clinical examination, provisional diagnosis of mucocele was made. All the lesions were excised with a diode laser and biopsy was performed. Surgical wounds were treated with low-level laser therapy (LLLT). Results: Uneventful healing was observed in all 4 cases. Significant reduction in postoperative discomfort was recorded after application of LLLT. Histopathological findings were suggestive of mucus extravasation cysts. Conclusion: Diode laser appears to be a good alternative to conventional modalities for the management of mucus extravasation cysts. PMID:29123637

  5. Lidocaine/tetracaine peel in topical anesthesia prior to laser-assisted hair removal: Phase-II and Phase-III study results.

    Science.gov (United States)

    Alster, Tina; Garden, Jerome; Fitzpatrick, Richard; Rendon, Marta; Sarkany, Marlis; Adelglass, Jeffrey

    2014-04-01

    Patient comfort is essential during dermatologic procedures. To evaluate anesthetic efficacy in laser-assisted hair removal of a self-occluding topical anesthetic (lidocaine 70 mg/g and tetracaine 70 mg/g, "LT peel"), which air-dries and can be peeled off 30 min post-application. Studies A (Phase-II) and B (Phase-III) were randomized, double-blind, placebo-controlled and paired. Applications of LT peel and placebo were concurrent: in Study A, 60 subjects were randomized to 30, 45, or 60-min groups, and in Study B, 50 subjects had 30-min applications. After drug removal, the investigator assessed for erythema, edema, and blanching. Efficacy evaluations followed the procedure: subject's pain [Visual Analog Scale (VAS), no to worst pain (0 - 100)], subject's/investigator's impression of anesthetic adequacy, and investigator's pain ratings. Adverse events (AEs) were recorded. VAS scores were significantly lower (p peel: mean scores were 26.7 for LT Peel vs. 44.3 for placebo (Study A total population, similar between application times) and 23 vs. 31.7 (Study B), respectively. For both studies, subject's/investigator's ratings favored LT peel (p peel. After a 30-min application, LT peel was effective and well-tolerated in providing anesthesia for laser-assisted hair removal.

  6. Bending diamonds by femtosecond laser ablation

    DEFF Research Database (Denmark)

    Balling, Peter; Esberg, Jakob; Kirsebom, Kim

    2009-01-01

    We present a new method based on femtosecond laser ablation for the fabrication of statically bent diamond crystals. Using this method, curvature radii of 1 m can easily be achieved, and the curvature obtained is very uniform. Since diamond is extremely tolerant to high radiation doses, partly due...

  7. Temperature Development on the External Root Surface During Laser-Assisted Endodontic Treatment Applying a Microchopped Mode of a 980 nm Diode Laser.

    Science.gov (United States)

    Beer, Franziska; Farmakis, Eleftherios Terry R; Kopic, Josip; Kurzmann, Christoph; Moritz, Andreas

    2017-04-01

    The aim of this article was to investigate the temperature increase of the external root surface during laser-assisted endodontic treatment using a diode laser (980 nm) in a microchopped mode. Ten freshly extracted, human maxillary incisors with mature apices were collected, prepared to size F4 at working length (ProTaper; Dentsply Maillefer, Ballaigues, Switzerland), mounted to a holder, and irradiated (using spiral movements in coronal direction) with a diode laser (GENTLEray 980 Classic Plus; KaVo, Biberach, Germany) with a 200 μm fiber in four different treatment groups: Group 1 (control group) was irradiated in six cycles of 5-sec irradiation/20-sec pause with 2.5 W in the pulse mode. Groups 2 to 4 were irradiated at six cycles of 5-sec irradiation/20-sec pause in the microchopped mode (Group 2-1.6 W; Group 3-2.0 W; Group 4-2.5 W). The applied mode was 25 ms on/25 ms off. Within the on period, the laser delivered an intermittent sequence of energy complexes and the maximum output was equal to the nominated output of the device (12 W). Canals were kept moist by sterile saline irrigation in between irradiations, and temperature changes were continuously measured using a thermal imaging camera. Recordings were analyzed by a mixed model (analysis of variance [ANOVA] for repeated measurements). The highest mean of temperature rise, 1.94°C ± 1.07°C, was measured in Group 4, followed by Group 3 (1.74°C ± 1.22°C) and Group 2 (1.58°C ± 1.18°C). The lowest increase occurred in Group 1 (1.06°C ± 1.20°C). There was a significant difference (p = 0.041) between the groups. Significant differences were found between Groups 1 and 4 (p = 0.007) and 1 and 2 (p = 0.035). In addition, a marginally significant difference between Groups 1 and 2 (p = 0.052) was noted. There was no significant difference between Groups 2, 3, and 4. Despite the low mean values reported, the highest temperature increase (+5.7°C) was

  8. Spatiotemporal closure of fractional laser-ablated channels imaged by optical coherence tomography and reflectance confocal microscopy

    DEFF Research Database (Denmark)

    Banzhaf, Christina A.; Wind, Bas S.; Mogensen, Mette

    2016-01-01

    laser (AFXL)-induced channels and dynamics in their spatiotemporal closure using in vivo OCT and RCM techniques. Study design/Materials and Methods The inner forearm of healthy subjects (n = 6) was exposed to 10,600 nm fractional CO2 laser using 5 and 25% densities, 120 μm beam diameter, 5, 15, and 25 m......Background and Objective Optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) offer high-resolution optical imaging of the skin, which may provide benefit in the context of laser-assisted drug delivery. We aimed to characterize postoperative healing of ablative fractional......, indicating tissue fluid. By OCT the median percentage of open channels was evaluated at several time points within the first 24 hours and laser channels were found to gradually close, depending on the used energy level. Thus, at 5 mJ/microbeam, 87% (range 73-100%) of channels were open one hour after laser...

  9. Early changes in ocular surface and tear inflammatory mediators after small-incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis.

    Directory of Open Access Journals (Sweden)

    Shaohui Gao

    Full Text Available To characterize the early ocular-surface changes or tear inflammatory-mediators levels following small-incision lenticule extraction (ReLEx smile and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK.Forty-seven myopic subjects were recruited for this prospective study. Fifteen underwent ReLEx smile and thirty-two underwent FS-LASIK. Corneal fluorescein (FL staining, tear break-up time (TBUT, Schirmer I test (SIT, ocular surface disease index (OSDI and central corneal sensitivity were evaluated in all participants. Tears were collected and analyzed for interleukin-6 (IL-6, tumor necrosis factor-α (TNF-α, nerve growth factor (NGF and intercellular adhesion molecule-1 (ICAM-1 levels using multiplex magnetic beads. All measurements were preformed preoperatively and 1 day, 1 week, 1 month and 3 months postoperatively.FL scores in ReLEx smile group were lower than those of FS-LASIK group 1 week postoperatively (P = 0.010. Compared to the FS-LASIK group, longer TBUT were observed in ReLEx smile group 1 month (P = 0.029 and 3 months (P = 0.045 postoperatively. No significant differences were found in tear secretion for the two groups (P>0.05. OSDI scores were higher in FS-LASIK group 1 month after surgery (P = 0.020. Higher central corneal sensitivity was observed in ReLEx smile group 1 week, 1 month and 3 months (P0.05. Moreover, IL-6 and NGF levels correlated with ocular surface changes after ReLEx smile or FS-LASIK.In the early postoperative period, ReLEx smile results in milder ocular surface changes than FS-LASIK. Furthermore, the tear inflammatory mediators IL-6 and NGF may play a crucial role in the ocular surface healing process following ReLEx smile and FS-LASIK.

  10. Long-term safety and efficacy follow-up of prophylactic higher fluence collagen cross-linking in high myopic laser-assisted in situ keratomileusis

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-07-01

    Full Text Available Anastasios John KanellopoulosLaservision.gr Institute, Athens, Greece, and New York University Medical School, New York, NY, USABackground: The purpose of this study was to evaluate the safety and efficacy of ultraviolet A irradiation cross-linking on completion for cases of high myopic laser-assisted in situ keratomileusis (LASIK.Methods: Forty-three consecutive LASIK cases treated with femtosecond laser flap and the WaveLight excimer platform were evaluated perioperatively for uncorrected visual acuity, best corrected spectacle visual acuity, refraction, keratometry, topography, total and flap pachymetry, corneal optical coherence tomography, and endothelial cell count. All eyes at the completion of LASIK had cross-linking through the repositioned flap, with higher fluence (10 mW/cm2 ultraviolet light of an average 370 µm wavelength and 10 mW/cm2 fluence applied for 3 minutes following an earlier single instillation of 0.1% riboflavin within the flap interface. Mean follow-up duration was 3.5 (range 1.0–4.5 years.Results: Mean uncorrected visual acuity changed from 0.2 to 1.2, best corrected spectacle visual acuity from 1.1 to 1.2, spherical equivalent from -7.5 diopters (D to -0.2 D, keratometry from 44.5 D to 38 D, flap pachymetry from 105 µm to, total pachymetry from 525 to 405, and endothelial cell count from 2750 to 2800. None of the cases developed signs of ectasia or significant regression during follow-up.Conclusion: Prophylactic collagen cross-linking for high-risk LASIK cases appears to be a safe and effective adjunctive treatment for refractive regression and potential ectasia. This application may be viewed as prophylactic customization of the biomechanical behavior of corneal collagen.Keywords: prophylactic collagen cross-linking, laser-assisted in situ keratomileusis, high-risk, post-LASIK ectasia

  11. Randomised, single-masked non-inferiority trial of femtosecond laser-assisted versus manual phacoemulsification cataract surgery for adults with visually significant cataract: the FACT trial protocol.

    Science.gov (United States)

    Day, Alexander C; Burr, Jennifer M; Bunce, Catey; Doré, Caroline J; Sylvestre, Yvonne; Wormald, Richard P L; Round, Jeff; McCudden, Victoria; Rubin, Gary; Wilkins, Mark R

    2015-11-27

    Cataract is one of the leading causes of low vision in the westernised world, and cataract surgery is one of the most commonly performed operations. Laser platforms for cataract surgery are now available, the anticipated advantages of which are broad and may include better visual outcomes through greater precision and reproducibility, and improved safety. FACT is a randomised single masked non-inferiority trial to establish whether laser-assisted cataract surgery is as good as or better than standard manual phacoemulsification. 808 patients aged 18 years and over with visually significant cataract will be randomised to manual phacoemulsification cataract surgery (standard care) or laser-assisted cataract surgery (intervention arm). Outcomes will be measured at 3 and 12 months after surgery. The primary clinical outcome is uncorrected distance visual acuity (UDVA, logMAR) at 3 months in the study eye recorded by an observer masked to the trial group. Secondary outcomes include UDVA at 12 months, corrected distance visual acuity at 3 and 12 months, complications, endothelial cell loss, patient-reported outcome measures and a health economic analysis conforming to National Institute for Health and Care Excellence standards. Research Ethics Committee Approval was obtained on 6 February 2015, ref: 14/LO/1937. Current protocol: v2.0 (08/04/2015). Study findings will be published in peer-reviewed journals. 77602616. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  12. Multi-criteria optimization in CO2 laser ablation of multimode polymer waveguides

    Science.gov (United States)

    Tamrin, K. F.; Zakariyah, S. S.; Sheikh, N. A.

    2015-12-01

    High interconnection density associated with current electronics products poses certain challenges in designing circuit boards. Methods, including laser-assisted microvia drilling and surface mount technologies for example, are being used to minimize the impacts of the problems. However, the bottleneck is significantly pronounced at bit data rates above 10 Gbit/s where losses, especially those due to crosstalk, become high. One solution is optical interconnections (OI) based on polymer waveguides. Laser ablation of the optical waveguides is viewed as a very compatible technique with ultraviolet laser sources, such as excimer and UV Nd:YAG lasers, being used due to their photochemical nature and minimal thermal effect when they interact with optical materials. In this paper, the authors demonstrate the application of grey relational analysis to determine the optimized processing parameters concerning fabrication of multimode optical polymer waveguides by using infra-red 10.6 μm CO2 laser micromachining to etch acrylate-based photopolymer (Truemode™). CO2 laser micromachining offers a low cost and high speed fabrication route needed for high volume productions as the wavelength of CO2 lasers can couple well with a variety of polymer substrates. Based on the highest grey relational grade, the optimized processing parameters are determined at laser power of 3 W and scanning speed of 100 mm/s.

  13. Fundamental studies of pulsed laser ablation

    CERN Document Server

    Claeyssens, F

    2001-01-01

    dopant) have resulted in a coherent view of the resulting plume, which exhibits a multi-component structure correlated with different regimes of ablation, which are attributed to ejection from ZnO and ablation from a Zn melt. OES measurements show that the emitting Zn component within the plume accelerates during expansion in vacuum - an observation attributable to the presence of hot, fast electrons in the plume. The same acceleration behaviour is observed in the case of Al atomic emissions resulting from ablation of an Al target in vacuum. Deposition conditions, substrate temperature and background gas pressure were all varied in a quest for optimally aligned, high quality ZnO thin films. Initial ab initio calculations were performed also, to aid in understanding the stability of these c-axis aligned films. The pulsed ultraviolet (lambda = 193, 248 nm) laser ablation of graphite, polycrystalline diamond and ZnO targets has been investigated. Characteristics of the resulting plumes of ablated material have b...

  14. Subcellular analysis by laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A; Shrestha, Bindesh

    2014-12-02

    In various embodiments, a method of laser ablation electrospray ionization mass spectrometry (LAESI-MS) may generally comprise micro-dissecting a cell comprising at least one of a cell wall and a cell membrane to expose at least one subcellular component therein, ablating the at least one subcellular component by an infrared laser pulse to form an ablation plume, intercepting the ablation plume by an electrospray plume to form ions, and detecting the ions by mass spectrometry.

  15. Plume dynamics and shielding by the ablation plume during Er:YAG laser ablation.

    Science.gov (United States)

    Nahen, Kester; Vogel, Alfred

    2002-04-01

    Free-running Er:YAG lasers are used for precise tissue ablation in various clinical applications. The ablated material is ejected into the direction perpendicular to the tissue surface. We investigated the influence of shielding by the ablation plume on the energy deposition into an irradiated sample because it influences the ablation dynamics and the amount of material ablated. The investigations were performed using an Er:YAG laser with a pulse duration of 200 micros for the ablation of gelatin with different water contents, skin, and water. Laser flash photography combined with a dark field Schlieren technique was used to visualize gaseous and particulate ablation products, and to measure the distance traveled by the ablating laser beam through the ablation plume at various times after the beginning of the laser pulse. The temporal evolution of the transmission through the ablation plume was probed using a second free running Er:YAG laser beam directed parallel to the sample's surface. The ablation dynamics was found to consist of a vaporization phase followed by material ejection. The observation of droplet ejection during water ablation provided evidence that a phase explosion is the driving mechanism for material ejection. The laser light transmission was only slightly reduced by the vapor plume, but decreased by 25%-50% when the ejected material passed the probe beam. At radiant exposures approximately 10 times above the ablation threshold, the laser energy deposited into the sample amounted to only 61% of the incident energy for gelatin samples with 90% water content and to 86% for skin samples. For free-running Er:YAG laser pulses shielding must therefore be considered in modeling the ablation dynamics and determining the dosage for clinical applications.

  16. Support for High Power Laser Ablation 2010

    Science.gov (United States)

    2010-04-16

    Spaces from the Ministry of Education, Culture, Sport , Science and Technology, Japan. 27 [24] An Analytical Model of Ablation in Gas Flow Leonid...Targets at 0.1-10 TW/cm2 John L. Remo Dept. of Astronomy and Dept. of Earth and Planetary Sciences, Harvard University, 20 Oxford St. and Harvard...modeling of planetary cores and high velocity impact. [43] Laser and Z-pinch Simulation of High Energy Density Planetary Interactions John L. Remo

  17. Modelling of dental laser ablation

    OpenAIRE

    Vila Verde, A.

    2005-01-01

    Tese de Doutoramento Ciências O objectivo final do trabalho descrito nesta tese consiste na determinação dos melhores parâmetros de funcionamento de lasers de modo a ser possível escavar túneis compridos e estreitos através do esmalte e da dentina, um dos procedimentos necessários para se proceder a um tratamento minimamente invasivo da cárie dentária. Primeiramente é apresentada uma revisão da literatura onde são identificadas as gamas de valores dos parâmetros de funcionamento do laser p...

  18. Solar cell contact formation using laser ablation

    Science.gov (United States)

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  19. Pulsed laser ablation of solids basics, theory and applications

    CERN Document Server

    Stafe, Mihai; Puscas, Niculae N

    2014-01-01

    The book introduces ‘the state of the art' of pulsed laser ablation and its applications. It is based on recent theoretical and experimental studies. The book reaches from the basics to advanced topics of pulsed laser ablation. Theoretical and experimental fundamental phenomena involved in pulsed laser ablation are discussed with respect to material properties, laser wavelength, fluence and intensity regime of the light absorbed linearly or non-linearly in the target material. The energy absorbed by the electrons leads to atom/molecule excitation, ionization and/or direct chemical bond breaking and is also transferred to the lattice leading to material heating and phase transitions. Experimental  non-invasive optical methods for analyzing these phenomena in real time are described. Theoretical models for pulsed laser ablation and phase transitions induced by laser beams and laser-vapour/plasma interaction during the plume expansion above the target are also presented. Calculations of the ablation speed and...

  20. Early changes in ocular surface and tear inflammatory mediators after small-incision lenticule extraction and femtosecond laser-assisted laser in situ keratomileusis.

    Science.gov (United States)

    Gao, Shaohui; Li, Saiqun; Liu, Liangping; Wang, Yong; Ding, Hui; Li, Lili; Zhong, Xingwu

    2014-01-01

    To characterize the early ocular-surface changes or tear inflammatory-mediators levels following small-incision lenticule extraction (ReLEx smile) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Forty-seven myopic subjects were recruited for this prospective study. Fifteen underwent ReLEx smile and thirty-two underwent FS-LASIK. Corneal fluorescein (FL) staining, tear break-up time (TBUT), Schirmer I test (SIT), ocular surface disease index (OSDI) and central corneal sensitivity were evaluated in all participants. Tears were collected and analyzed for interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nerve growth factor (NGF) and intercellular adhesion molecule-1 (ICAM-1) levels using multiplex magnetic beads. All measurements were preformed preoperatively and 1 day, 1 week, 1 month and 3 months postoperatively. FL scores in ReLEx smile group were lower than those of FS-LASIK group 1 week postoperatively (P = 0.010). Compared to the FS-LASIK group, longer TBUT were observed in ReLEx smile group 1 month (P = 0.029) and 3 months (P = 0.045) postoperatively. No significant differences were found in tear secretion for the two groups (P>0.05). OSDI scores were higher in FS-LASIK group 1 month after surgery (P = 0.020). Higher central corneal sensitivity was observed in ReLEx smile group 1 week, 1 month and 3 months (Ptears was observed in ReLEx smile group postoperatively (PTears TNF-α and ICAM-1 concentrations were not significantly different between the two groups at any follow-up time (P>0.05). Moreover, IL-6 and NGF levels correlated with ocular surface changes after ReLEx smile or FS-LASIK. In the early postoperative period, ReLEx smile results in milder ocular surface changes than FS-LASIK. Furthermore, the tear inflammatory mediators IL-6 and NGF may play a crucial role in the ocular surface healing process following ReLEx smile and FS-LASIK.

  1. [Comparison of the effects of different side-cut angles on corneal biomechanical properties after femtosecond laser assisted-laser in situ keratomileusis].

    Science.gov (United States)

    Li, H; Wang, Y; Dou, R; Wang, L; Xu, L L; Li, X J; Zhang, J M

    2017-01-11

    Objective: To evaluate the effects of side-cut angles on corneal biomechanical properties after femtosecond laser assisted-laser in situ keratomileusis (FS-LASIK). Methods: In this clinical control study, 97 right eyes of 97 patients with myopia and myopic astigmatism undergoing FS-LASIK surgery were included randomly. Two types of side-cut angles were designed for the flap, 90° in 48 eyes and 130° in 49 eyes. The values of corneal resistance factor (CRF), cornea hysteresis (CH) and 37 biomechanical waveform parameters were measured using the ocular response analyzer preoperatively and at 1 and 3 months postoperatively. The comparison between the two groups at different follow-up time points was made with one-way analysis of variance, and the comparison among different follow-up time points in each group was performed with the repeated measures analysis of variance. Results: The mean CRF, CH, p area, h, dive1, dive2, w11 and w21 in both groups showed significant reduction at 1 month postoperatively (group 90°: CRF 10.49 vs. 6.85, CH 10.02 vs. 7.55, p1 area 3 537.54 vs. 1 918.07, h1 404.74 vs. 283.25, dive1 350.63 vs. 243.33, w11 10.50 vs. 7.58. group 130°: CRF 10.14 vs. 6.38, CH 9.93 vs. 7.13, p1 area 3 498.93 vs. 2 038.74, h1 411.93 vs. 304.49, dive1 352.51 vs. 265.12, w11 10.55 vs. 7.78. PCorneal biomechanical properties significantly decrease after FS-LASIK, and different side-cut angles have some effect on corneal biomechanical properties after FS-LASIK. The corneal deformation is more stable after flap creation with an obtuse side-cut angle making the cornea under stress. Combined with waveform parameters of the ocular response analyzer, more subtle changes of corneal biomechanical properties can be found. (Chin J Ophthalmol, 2017, 53:23-32).

  2. Evaluation of a novel laser-assisted coronary anastomotic connector - the Trinity Clip - in a porcine off-pump bypass model.

    Science.gov (United States)

    Stecher, David; Bronkers, Glenn; Noest, Jappe O T; Tulleken, Cornelis A F; Hoefer, Imo E; van Herwerden, Lex A; Pasterkamp, Gerard; Buijsrogge, Marc P

    2014-11-24

    To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.

  3. CT Guided Laser Ablation of Osteoid Osteoma

    Directory of Open Access Journals (Sweden)

    Manohar Kachare

    2015-10-01

    Full Text Available To present our experience of Computed Tomography (CT guided laser ablation of radiologically proven osteoid osteoma in the inter trochantric region of the femur. A19 year old female presented with severe pain in left upper thigh region since 6-7 months, which was exaggerated during nights and was relived on taking oral Non Steroid Anti Inflammatory Drugs (NSAIDs. On CT scan hypodense lesion with surrounding dense sclerosis noted in intertrochanteric region in left femur. Magnetic Resonance Imaging (MRI revealed small focal predominantly cortical, oval lytic lesion in the intertrochanteric region which appeared hypointense on T1 Weighted Image (T1WI and hyperintense on T2 Weighted Image (T2WI and Short Tau Inversion Recovery (STIR image. Diffuse extensive sclerosis and hyperostosis of bone was noted surrounding the lesion appearing hypointense on T1W and T2W images. Under local anesthesia the laser fibre was inserted in the nidus under CT guidance through bone biopsy needle and 1800 joules energy delivered in the lesion continuous mode. Complete relief of pain noted after 24 hours after the treatment. CT guided LASER ablation is a safe, simple and effective method of treatment for osteoid osteoma.

  4. Ablative CO2 lasers for skin tightening: traditional versus fractional.

    Science.gov (United States)

    Ortiz, Arisa E; Goldman, Mitchel P; Fitzpatrick, Richard E

    2014-12-01

    With patients more resistant to invasive treatments and those that result in significant downtime, there has been a rise in using lasers to improve skin laxity and induce tissue tightening as an alternative to surgery. Traditional and fractional ablative resurfacing induces skin tightening through precise dermal heating and a wound-healing effect. The purpose of this review was to discuss the mechanism of action of using ablative lasers to induce skin tightening and compare traditional versus fractional technologies. A review of the literature was performed. The authors discuss traditional and fractional ablative lasers for achieving skin tightening. Neocollagenesis and dermal remodeling seen after ablative resurfacing contributes to the clinical improvement seen in tissue tightening. Fractional photothermolysis may enhance tissue tightening effects of ablative lasers because of its ability to ablate deeper into the reticular dermis without significant risk for scarring.

  5. Shielding by the ablation plume during Er:YAG laser ablation

    Science.gov (United States)

    Nahen, Kester; Vogel, Alfred

    2001-07-01

    Free running Er:YAG lasers are used for a precise tissue ablation in various clinical application as, for example, laser skin resurfacing. The ablated material is ejected from the tissue surface in the direction of the incident laser beam. We investigated the influence of the shielding by the ablation plume on the energy deposition into the irradiated sample because it influences the ablation dynamics and the amount of ablated material. The shielding was investigated for gelatin with different water content, skin and water. Laser flash photography combined with a dark field Schlieren technique was used to visualize the gaseous and liquid ablation products. The distance traveled by the ablating laser beam through the ablation plume was evaluated from the photographs for various times after the beginning of the laser pulse. The temporal evolution of the transmission through the ablation plume was probed using a second free running Er:YAG laser beam directed parallel to the sample surface. The ablation dynamics shows two phases: Vaporization and material ejection. The photographic observations give evidence for a phase explosion to be the driving mechanism for the material ejection. The photographic observations give evidence for a phase explosion to be the driving mechanism for the material ejection. The transmission is only slightly reduced by the vapor plume, but it decreases by 25-50% when the ejected material passes the probe beam. The laser energy deposited into the sample amounts to only 61% of the incident energy for gelatin samples with 90% water content and 86% for skin samples. The shielding must therefore be considered in modeling the ablation dynamics and determining the dosage for clinical applications.

  6. Mechanism study of skin tissue ablation by nanosecond laser pulses

    Science.gov (United States)

    Fang, Qiyin

    Understanding the fundamental mechanisms in laser tissue ablation is essential to improve clinical laser applications by reducing collateral damage and laser pulse energy requirement. The motive of this dissertation is to study skin tissue ablation by nanosecond laser pulses in a wide spectral region from near-infrared to ultraviolet for a clear understanding of the mechanism that can be used to improve future design of the pulsed lasers for dermatology and plastic surgery. Multiple laser and optical configurations have been constructed to generate 9 to 12ns laser pulses with similar profiles at 1064. 532, 266 and 213nm for this study of skin tissue ablation. Through measurements of ablation depth as a function cf laser pulse energy, the 589nm spectral line in the secondary radiation from ablated skin tissue samples was identified as the signature of the occurrence of ablation. Subsequently, this spectral signature has been used to investigate the probabilistic process of the ablation near the threshold at the four wavelengths. Measurements of the ablation probability were conducted as a function of the electrical field strength of the laser pulse and the ablation thresholds in a wide spectral range from 1064nm to 213nm were determined. Histology analysis and an optical transmission method were applied in assessing of the ablation depth per pulse to study the ablation process at irradiance levels higher than threshold. Because more than 70% of the wet weight of the skin tissue is water, optical breakdown and backscattering in water was also investigated along with a nonlinear refraction index measurement using a z-scan technique. Preliminary studies on ablation of a gelatin based tissue phantom are also reported. The current theoretical models describing ablation of soft tissue ablation by short laser pulses were critically reviewed. Since none of the existing models was found capable of explaining the experimental results, a new plasma-mediated model was developed

  7. Treatment of ulcers with ablative fractional lasers.

    Science.gov (United States)

    Morton, Laurel M; Dover, Jeffrey S; Phillips, Tania J; Krakowski, Andrew C; Uebelhoer, Nathan S

    2015-03-01

    Chronic, nonhealing ulcers are a frustrating therapeutic challenge and investigation of innovative therapies continues to be an important research pursuit. One unique and newly applied intervention is the use of ablative fractional lasers. This technology has recently been employed for the treatment of hypertrophic, disfiguring and function-limiting scars, and was first shown to induce healing of chronic wounds in patients with persistent ulcers and erosions within traumatic scars. Recent reports suggest it may be applicable for other types of chronic wounds as well. The mechanism of action for this modality remains to be elucidated but possible factors include laser-induced collagen remodeling, photomicrodebridement and disruption of biofilms, and induction of a proper wound healing cascade. ©2015 Frontline Medical Communications.

  8. Comparison of intraocular pressure during the application of a liquid patient interface (FEMTO LDV Z8) for femtosecond laser-assisted cataract surgery using two different vacuum levels.

    Science.gov (United States)

    Ebner, Martina; Mariacher, Siegfried; Januschowski, Kai; Boden, Katrin; Seuthe, Anna-Maria; Szurman, Peter; Boden, Karl Thomas

    2017-08-01

    To evaluate intraocular pressure (IOP) using the application of a novel liquid patient interface for femtosecond laser-assisted cataract surgery with the FEMTO LDV Z8. IOP was evaluated in enucleated porcine eyes prior, during and after the application of the Femto LDV Z8 liquid patient interface (Ziemer Ophthalmic Systems, Switzerland) using intracameral cannulation (n=20), intravitreal cannulation (n=20), rebound tonometry (n=20) and indentation tonometry (n=20). Pressure was assessed prior vacuum, during vacuum (30 s, 1 min, 2 min, 3 min) and after releasing the vacuum (1 min and 2 min). Two groups with different predefined vacuum levels (350 mbar, 420 mbar) were investigated. Mean intracameral pressure (±SD) increased during vacuum application from 20 mm Hg to 52.00 mm Hg (±6.35mm Hg; p=0.005) and 45.18 mmHg (±4.34 mm Hg; p=0.005) for the 420 mbar and the 350 mbar vacuum levels, respectively. Mean intravitreal pressure increased from 20 mm Hg to 25.60 mm Hg (±9.85 mm Hg; p=0.058) and 28.10 mm Hg (±2.54 mm Hg; p=0.059) for the 420 mbar and the 350 mbar vacuum levels, respectively. Pressure values from indentation and rebound tonometry were in between intracameral and intravitreal values. Mean intracameral IOP was 18.1% higher (p=0.019) in the 420 mbar group compared with the 350 mbar group. During vacuum application of the liquid patient interface of the Femto LDV Z8 for femtosecond laser-assisted cataract surgery, IOP values were higher in the anterior chamber compared with the intravitreal pressure measurements. The higher predefined vacuum level (350 mbar vs 420 mbar) resulted in significant higher intracameral IOP. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  9. Rate of ectasia and incidence of irregular topography in patients with unidentified preoperative risk factors undergoing femtosecond laser-assisted LASIK

    Directory of Open Access Journals (Sweden)

    Moshirfar M

    2013-12-01

    Full Text Available Majid Moshirfar,1 Jared G Smedley,2 Valliammai Muthappan,1 Allison Jarsted,3 Erik M Ostler1 1John A Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 2College of Human Medicine, Michigan State University, Lansing, MI, USA; 3Department of Ophthalmology, State University of New York Upstate Medical University, Syracuse, NY, USA Purpose: To report the rate of postoperative ectasia after laser-assisted in situ keratomileusis (LASIK with femtosecond laser-assisted flap creation, in a population of patients with no identified preoperative risk factors. Methods: A retrospective case review of 1,992 eyes (1,364 patients treated between March 2007 and January 2009 was conducted, with a follow up of over 4 years. After identifying cases of ectasia, all the patient charts were examined retrospectively for preoperative findings suggestive of forme fruste keratoconus (FFKC. Results: Five eyes of four patients with post-LASIK ectasia were identified. All eyes passed preoperative screening and received bilateral LASIK. One of the five patients developed ectasia in both eyes. Three patients retrospectively revealed preoperative topography suggestive of FFKC, while one patient had no identifiable preoperative risk factors. Upon review of all the charts, a total 69 eyes, including four of the five eyes with ectasia, were retrospectively found to have topographies suggestive of FFKC. Conclusion: We identified four cases of post-LASIK ectasia that had risk factors for FFKC on reexamination of the chart and one case of post-LASIK ectasia with no identifiable preoperative risk factors. The most conservative screening recommendations would not have precluded this patient from LASIK. The rate of purely iatrogenic post-LASIK ectasia at our center was 0.05% (1/1,992, and the total rate of post-LASIK ectasia for our entire study was 0.25% (1/398. The rate of eyes with unrecognized preoperative FFKC that developed post-LASIK ectasia was 5.8% (1/17. Keywords

  10. Experience in using the excimer laser-assisted nonocclusive anastomosis nonocclusive bypass technique for high-flow revascularization: Mannheim-Helsinki series of 64 patients.

    Science.gov (United States)

    Vajkoczy, Peter; Korja, Miikka; Czabanka, Marcus; Schneider, Ulf C; Reinert, Michael; Lehecka, Martin; Schmiedek, Peter; Hernesniemi, Juha; Kivipelto, Leena

    2012-01-01

    The excimer laser-assisted nonocclusive anastomosis (ELANA) technique enables large-caliber bypass revascularization without temporary occlusion of the parent artery. To present the surgical experience of 2 bypass centers using ELANA in the treatment of complex intracranial lesions. Between July 2002 and December 2007, 64 consecutive patients (37 in Germany and 27 in Finland) were selected for high-flow bypass surgery with ELANA. Modified Rankin Scale, a bypass success rate, and the success rate of the laser arteriotomy were assessed. In 66 surgeries for 64 intent-to-treat patients, 58 ELANA procedures were completed successfully. A favorable outcome (postoperative modified Rankin Scale score less than or equal to preoperative modified Rankin Scale) at 3 months was achieved in 43 of 56 patients (77%) with anterior circulation lesions (37 of the 43 patients had aneurysms, 4 had ischemia, and 2 received a bypass before tumor removal) and only in 2 of 8 patients (25%) with posterior circulation aneurysms. Perioperative (< 7 days) mortality for anterior and posterior circulation aneurysms was 6% and 50%, respectively. At the 3-month follow-up, 12% and 63% of patients with anterior and posterior circulation aneurysms, respectively, were dead. The success rate of the laser arteriotomy was 70%. Another 14% were retrieved manually after a nearly complete laser arteriotomy. The ELANA procedure requires a meticulous and careful operative technique. Morbidity and especially mortality rates, usually unrelated to ELANA, are comparable to those of contemporary series of conventional high-flow revascularization operations. This underscores the overall complexity of treating neurovascular pathologies by high-flow bypasses.

  11. Femtosecond ultraviolet laser ablation of silver and comparison with nanosecond ablation

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Doggett, B.; Budtz-Jørgensen, C.

    2013-01-01

    ablation are similar; both show a singly peaked time-of-flight distribution. The angular distribution of ion emission and the deposition are well described by the adiabatic and isentropic model of plume expansion, though distributions for femtosecond ablation are significantly narrower. In this laser......The ablation plume dynamics arising from ablation of silver with a 500 fs, 248 nm laser at ~2 J cm-2 has been studied using angle-resolved Langmuir ion probe and thin film deposition techniques. For the same laser fluence, the time-of-flight ion signals from femtosecond and nanosecond laser...... fluence regime, the energy efficiency of mass ablation is higher for femtosecond pulses than for nanosecond pulses, but the ion production efficiency is lower....

  12. Laser Ablation for Cancer: Past, Present and Future

    Science.gov (United States)

    Schena, Emiliano; Saccomandi, Paola; Fong, Yuman

    2017-01-01

    Laser ablation (LA) is gaining acceptance for the treatment of tumors as an alternative to surgical resection. This paper reviews the use of lasers for ablative and surgical applications. Also reviewed are solutions aimed at improving LA outcomes: hyperthermal treatment planning tools and thermometric techniques during LA, used to guide the surgeon in the choice and adjustment of the optimal laser settings, and the potential use of nanoparticles to allow biologic selectivity of ablative treatments. Promising technical solutions and a better knowledge of laser-tissue interaction should allow LA to be used in a safe and effective manner as a cancer treatment. PMID:28613248

  13. Effects of 445-nm Diode Laser-Assisted Debonding of Self-Ligating Ceramic Brackets on Shear Bond Strength.

    Science.gov (United States)

    Stein, Steffen; Hellak, Andreas; Schauseil, Michael; Korbmacher-Steiner, Heike; Braun, Andreas

    2018-01-01

    The aim of this study was to measure the effect of irradiation with a novel 445-nm diode laser on the shear bond strength (SBS) of ceramic brackets before debonding. Thirty ceramic brackets (In-Ovation® C, GAC) were bonded in standard manner to the planed and polished buccal enamel surfaces of 30 caries-free human third molars. Each tooth was randomly allocated to the laser or control group, with 15 samples per group. The brackets in the laser group were irradiated with the diode laser (SIROLaser Blue®; Sirona) on three sides of the bracket bases for 5 sec each (lateral-coronal-lateral, a total of 15 sec) immediately before debonding. SBS values were measured for the laser group and control group. To assess the adhesive remnant index (ARI) and the degree of enamel fractures, micrographs of the enamel surface were taken with 10-fold magnification after debonding. The SBS values were significantly lower statistically in the laser group in comparison with the control group (p diode laser before debonding significantly reduces the SBS values. This is of clinical importance, as it means that the risk of damage to the teeth, bracket fractures, and the overall treatment time can be reduced.

  14. Transient, three-dimensional heat transfer model for the laser assisted machining of silicon nitride: 2. Assessment of parametric effects

    Energy Technology Data Exchange (ETDEWEB)

    Rozzi, J.C.; Shin, Y.C. [Purdue University, (United States). Laser Assisted Materials Processing Laboratory, School of Mechanical Engineering; Incropera, F.P. [University of Notre Dame, (United States). Aerospace and Mechanical Engineering Department

    2000-04-01

    In a companion paper experimental validation was provided for a transient, three-dimensional heat transfer model of the LAM of a silicon nitride workpiece. In this paper, the model is used to elucidate the influence of operating parameters on thermal conditions within the workpiece. Calculations reveal that thermal energy generation in the primary shear zone has a significant influence on the workpiece temperature distribution, while the effects of heat transfer at the tool flank interface may be neglected. Although temperatures at the material removal plane were only moderately influenced by an increase in the workpiece rotational speed, a reduction in total laser energy deposition due to increased laser/tool translational velocity or decreased laser power may preclude the attainment of a minimum material removal temperature corresponding to the softening temperature range of the YSiAlON glassy phase. Due to the comparatively small influence on radial temperature gradients within the material removal plane, the minimum material removal temperature decreased only slightly with increasing depth of cut. However, the amount of laser energy deposition on the unmachined workpiece increased significantly with increasing laser-tool lead distance, yielding an attendant increase in the material removal temperature. For a fixed laser-tool lead, energy deposition at the unmachined workpiece surface increased with decreasing laser beam diameter and increasing power. (author)

  15. Corneal Backscatter Analysis by In Vivo Confocal Microscopy: Fellow Eye Comparison of Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK

    Directory of Open Access Journals (Sweden)

    Alper Agca

    2014-01-01

    Full Text Available Purpose. To evaluate and compare corneal backscatter from anterior stroma between small incision lenticule extraction (SMILE and femtosecond laser-assisted LASIK (femto-LASIK. Methods. A cohort of 60 eyes of 30 patients was randomized to receive SMILE in one eye and femto-LASIK in the fellow eye. In vivo confocal microscopy was performed at 1 week and 1, 3, and 6 months after surgery. The main outcome measurements were maximum backscattered intensity and the depth from which it was measured, the backscattered light intensity 30 μm below Bowman’s membrane at the flap interface and 150 μm below the superficial epithelium, and the number of refractive particles at the flap interface. Results. The mean backscattered light intensity (LI at all measured depths and the maximum backscattered LI were higher in the SMILE group than the femto-LASIK group at all postoperative visits. LI differences at 1 week and 1- and 3-month visits were statistically significant (P<0,05. LI differences at 6 months were not statistically significant. There was no difference in the number of refractive particles at the flap interface between the groups at any visit. Conclusions. SMILE results in increased backscattered LI in the anterior stroma when compared with femto-LASIK were evaluated.

  16. UV laser ablation of parylene films from gold substrates

    Energy Technology Data Exchange (ETDEWEB)

    O. R. Musaev, P. Scott, J. M. Wrobel, and M. B. Kruger

    2009-11-19

    Parylene films, coating gold substrates, were removed by laser ablation using 248 nm light from an excimer laser. Each sample was processed by a different number of pulses in one of three different environments: air at atmospheric pressure, nitrogen at atmospheric pressure, and vacuum. The laser-induced craters were analyzed by optical microscopy and x-ray photoelectron spectroscopy. Multi-pulse ablation thresholds of gold and parylene were estimated.

  17. [Research on cells ablation characters by laser plasma].

    Science.gov (United States)

    Han, Jing-hua; Zhang, Xin-gang; Cai, Xiao-tang; Duan, Tao; Feng, Guo-ying; Yang, Li-ming; Zhang, Ya-jun; Wang, Shao-peng; Li, Shi-wen

    2012-08-01

    The study on the mechanism of laser ablated cells is of importance to laser surgery and killing harmful cells. Three radiation modes were researched on the ablation characteristics of onion epidermal cells under: laser direct irradiation, focused irradiation and the laser plasma radiation. Based on the thermodynamic properties of the laser irradiation, the cell temperature rise and phase change have been analyzed. The experiments show that the cells damage under direct irradiation is not obvious at all, but the focused irradiation can cause cells to split and moisture removal. The removal shape is circular with larger area and rough fracture edges. The theoretical analysis found out that the laser plasma effects play a key role in the laser ablation. The thermal effects, radiation ionization and shock waves can increase the deposition of laser pulses energy and impact peeling of the cells, which will greatly increase the scope and efficiency of cell killing and is suitable for the cell destruction.

  18. Fractional Ablative Laser Followed by Transdermal Acoustic Pressure Wave Device to Enhance the Drug Delivery of Aminolevulinic Acid: In Vivo Fluorescence Microscopy Study.

    Science.gov (United States)

    Waibel, Jill S; Rudnick, Ashley; Nousari, Carlos; Bhanusali, Dhaval G

    2016-01-01

    Topical drug delivery is the foundation of all dermatological therapy. Laser-assisted drug delivery (LAD) using fractional ablative laser is an evolving modality that may allow for a greater precise depth of penetration by existing topical medications, as well as more efficient transcutaneous delivery of large drug molecules. Additional studies need to be performed using energy-driven methods that may enhance drug delivery in a synergistic manner. Processes such as iontophoresis, electroporation, sonophoresis, and the use of photomechanical waves aid in penetration. This study evaluated in vivo if there is increased efficacy of fractional CO2 ablative laser with immediate acoustic pressure wave device. Five patients were treated and biopsied at 4 treatment sites: 1) topically applied aminolevulinic acid (ALA) alone; 2) fractional ablative CO2 laser and topical ALA alone; 3) fractional ablative CO2 laser and transdermal acoustic pressure wave device delivery system; and 4) topical ALA with transdermal delivery system. The comparison of the difference in the magnitude of diffusion with both lateral spread of ALA and depth diffusion of ALA was measured by fluorescence microscopy. For fractional ablative CO2 laser, ALA, and transdermal acoustic pressure wave device, the protoporphyrin IX lateral fluorescence was 0.024 mm on average vs 0.0084 mm for fractional ablative CO2 laser and ALA alone. The diffusion for the acoustic pressure wave device was an order of magnitude greater. We found that our combined approach of fractional ablative CO2 laser paired with the transdermal acoustic pressure wave device increased the depth of penetration of ALA.

  19. Outcomes of ablative fractional laser scar treatment.

    Science.gov (United States)

    Kim, Deok-Woo; Hwang, Na-Hyun; Yoon, Eul-Sik; Dhong, Eun-Sang; Park, Seung-Ha

    2015-04-01

    Ablative fractional laser (AFL) systems are commonly used to treat various scars, and recent reports have indicated that early scar treatment with fractional lasers has good aesthetic results. Some scars respond dramatically to AFL treatment, incurring high levels of patient satisfaction; however, other scars respond poorly or became worse after treatment. This study was designed to clarify prognostic factors that predict AFL scar treatment outcomes. A total of 108 patients were included in this study. The fractional laser treatments were repeated every 4 weeks until the scar site was acceptable and no additional improvement was expected or the patient discontinued the treatment. The scar improvements were defined as changes in the Manchester scar scale (MSS) from before to after laser treatment. A digital camera was used to acquire digital photographs of the scars under the same light source, the same background, exposure, and white balance. This study developed a modification of the MSS for image analysis in which colour assessment was based on L*a*b* colour co-ordinates of the digital images. The mean MSS values prior to and after laser treatments were 11.6 ± 3.6 and 9.5 ± 2.9, respectively (p treatment improved the qualities of each scar, and the improvements were evident in colour and contour. Scar elevation, pigmentation, high vascularity, early onset of treatment, and the number of treatment sessions were directly related to scar improvement after AFL therapy (p treatments were effective methods for scar treatment. Clinicians can use these prognostic factors to determine treatment plans and to estimate scar improvement after AFL treatment.

  20. Nanocomposited coatings produced by laser-assisted process to prevent silicone hydogels from protein fouling and bacterial contamination

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Guobang; Chen, Yi; Zhang, Jin, E-mail: jzhang@eng.uwo.ca

    2016-01-01

    Graphical abstract: Nanocomposited-coating was deposited on silicone hydrogel by using the matrix-assisted pulsed laser evaporation (MAPLE) process. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel, and can inhibit the bacterial growth efficiently. - Highlights: • We developed a nanocomposited coating to prevent silicone hydrogel from biofouling. • Matrix-assisted pulsed laser evaporation can deposit inorganic–organic nanomaterials. • The designed nanocomposited coating reduces protein absorption by over 50%. • The designed nanocomposited coating shows significant antimicrobial efficiency. - Abstract: Zinc oxide (ZnO) nanoparticles incorporating with polyethylene glycol (PEG) were deposited together on the surface of silicone hydrogel through matrix-assisted pulsed laser evaporation (MAPLE). In this process, frozen nanocomposites (ZnO–PEG) in isopropanol were irradiated under a pulsed Nd:YAG laser at 532 nm for 1 h. Our results indicate that the MAPLE process is able to maintain the chemical backbone of polymer and prevent the nanocomposite coating from contamination. The ZnO–PEG nanocomposited coating reduces over 50% protein absorption on silicone hydrogel. The cytotoxicity study shows that the ZnO–PEG nanocomposites deposited on silicone hydrogels do not impose the toxic effect on mouse NIH/3T3 cells. In addition, MAPLE-deposited ZnO–PEG nanocomposites can inhibit the bacterial growth significantly.

  1. Formation of tribological structures by laser ablation

    Science.gov (United States)

    Schilling, Niels; Paschke, Mike; Hendow, Sami T.; Klotzbach, Udo

    2012-03-01

    Many technical applications can benefit from the use of tribological structures in minimizing abrasive material wear and energy consumption without the integration of additional materials in a working assembly. Especially in lubricated friction systems, the tribological character can be significantly improved through the addition of oriented and repetitive microstructure. In this study, experimental tests are discussed for a small range of structure dimensions to verify the effect of optimizing the tribological contact performance. A nanosecond pulsed fiber laser is used to create various test structures with different sizes and form. The quality of the fabricated surface pattern, particularly form correctness, feathering and material modification effects of the ablated area is characterized and optimized. The influence of pulse duration, pulse energy and pulse delay using normal pulsing is presented and compared to various burst modes.

  2. Comparison of the change in posterior corneal elevation and corneal biomechanical parameters after small incision lenticule extraction and femtosecond laser-assisted LASIK for high myopia correction.

    Science.gov (United States)

    Wang, Bingjie; Zhang, Zhenyong; Naidu, Rajeev K; Chu, Renyuan; Dai, Jinhui; Qu, Xiaomei; Yu, Zhiqiang; Zhou, Hao

    2016-06-01

    To compare posterior corneal elevation (PCE) changes and corneal biomechanical changes post fematosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) procedures using the Pentacam system and the Ocular Response Analyzer (ORA). Retrospective observational case series study. 106 patients with bilateral myopia who underwent either FS-LASIK (56 patients) or SMILE (50 patients) were reviewed, only the right eye was used in the analysis. Inclusion criteria include a spherical equivalent of -6.00DS and completion of 12 months follow up. The main outcome evaluated was change in PCE at 3 months, 6 months and 12 months post-operation using the Pentacam system. Corneal biomechanical parameters were evaluated at 6 and 12 months with the ORA. PCE change at 3 and 6 months were not significantly different between the two procedures (p=0.064, p=0.109 respectively). At 12 months, PCE change was greater in FS-LASIK than SMILE (p=0.048). One-way ANOVA showed that for either procedure, the change in PCE did not differ at 3, 6 or 12 months post operation. CH and CRF values were reduced after both procedures, with FS-LASIK demonstrating a greater reduction in CRF than SMILE at 6 and 12 months (p=0.037 and p=0.001). Both CH and CRF reduction correlated with PCE increase at 6 and 12 months. FS-LASIK demonstrated a greater increase in PCE than SMILE only at 12 months, as well as a greater reduction of CRF than SMILE. There were no significant differences in PCE change over time within either group. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  3. Comparison of corneal hysteresis and corneal resistance factor after small incision lenticule extraction and femtosecond laser-assisted LASIK: a prospective fellow eye study.

    Science.gov (United States)

    Agca, Alper; Ozgurhan, Engin Bilge; Demirok, Ahmet; Bozkurt, Ercument; Celik, Ugur; Ozkaya, Abdullah; Cankaya, Ilker; Yilmaz, Omer Faruk

    2014-04-01

    To compare corneal hysteresis (CH) and corneal resistance factor (CRF) between eyes treated with small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (femto-LASIK). Beyoğlu Eye Training and Research Hospital. Prospective comparative case series. Sixty eyes from 30 patients with bilateral myopia or myopic astigmatism were studied. Inclusion criteria were spherical equivalent of subjective manifest refraction (SE) <10diopters (D) and a difference ≤0.50D between the SEs of both eyes. One eye of each patient was treated with SMILE, and the fellow eye underwent femto-LASIK. Randomization was performed using a sealed envelope system. The main outcome measures were CH and CRF measured preoperatively and postoperatively (1 and 6 months). Preoperative SE was similar in both groups (p=0.852). CH and CRF values were reduced postoperatively in both groups compared to their corresponding preoperative values (p<0.001). At the 6-month follow-up visit, the mean CH values in the SMILE and femto-LASIK groups were 8.95±1.47 and 9.02±1.27, respectively (p=0.852), and the mean CRF values were 7.77±1.37 and 8.07±1.26, respectively (p=0.380). CH and CRF decreased after SMILE. There were no differences between SMILE and femto-LASIK treatments in postoperative CH or CRF values. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  4. Epithelial remodeling after femtosecond laser-assisted high myopic LASIK: comparison of stand-alone with LASIK combined with prophylactic high-fluence cross-linking.

    Science.gov (United States)

    Kanellopoulos, Anastasios J; Asimellis, George

    2014-05-01

    The aim of this study was to evaluate the possible topographic epithelial profile thickness changes (remodeling) after high myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence cross-linking (CXL) in comparison with standard femtosecond LASIK. Preoperative and 6-month postoperative 3-dimensional epithelial thickness distribution maps were investigated through clinical spectral domain anterior-segment optical coherence tomography in 2 groups of femtosecond laser-assisted myopic LASIK cases. Group A represented 67 eyes treated additionally with concurrent prophylactic CXL (LASIK-Xtra); group B represented 72 eyes subjected to stand-alone femtosecond LASIK. Optical coherence tomography measurements of the epithelial thickness over the center 2-mm-diameter disk, mid-peripheral 5-mm rim, and overall (the entire 6-mm-diameter disc area) were investigated. The comparison of matched myopic correction subgroups indicated statistically significant differences in the epithelial thickness increase specifically between high myopia subgroups. For example, in group A (LASIK-Xtra), the mid-peripheral epithelial thickness increase was +3.79 and +3.95 μm for the "-8.00 to -9.00 diopter" and "-7.00 to -8.00 diopter" subgroups, which compare with increased thickness in group B (stand-alone LASIK), of +9.75 μm (P = 0.032) and +7.14 μm (P = 0.041), respectively, for the same subgroups. Application of prophylactic CXL concurrently with high myopic LASIK operation results in a statistically significant reduced epithelial increase in comparison with stand-alone LASIK. This comparison is observed between matched high myopic correction subgroups. This difference may correlate with higher regression rates and/or may depict increased biomechanical instability in stand-alone LASIK.

  5. Treatment of elderly patients with advanced lipedema: a combination of laser-assisted liposuction, medial thigh lift, and lower partial abdominoplasty

    Directory of Open Access Journals (Sweden)

    Wollina U

    2014-01-01

    Full Text Available Uwe Wollina,1 Birgit Heinig,2 Andreas Nowak31Department of Dermatology and Allergology, 2Centre of Physical Therapy and Rehabilitative Medicine, 3Department of Anaesthesiology and Intensive Medical Care, Emergency Medicine and Pain Management, Academic Teaching Hospital Dresden-Friedrichstadt, Dresden, GermanyBackground: Lipedema is a rare female disorder with a characteristic distribution of adipose tissue hypertrophy on the extremities, with pain and bruising. In advanced stages, reduction of adipose tissue is the only available effective treatment. In elderly patients with advanced lipedema, correction of increased skin laxity has to be considered for an optimal outcome.Methods: We report on a tailored combined approach to improve advanced lipedema in elderly females with multiple comorbidities. Microcannular laser-assisted liposuction of the upper legs and knees is performed under tumescent anesthesia. Medial thigh lift and partial lower abdominoplasty with minimal undermining are used to correct skin laxity and prevent intertrigo. Postsurgical care with nonelastic flat knitted compression garments and manual lymph drainage are used.Results: We report on three women aged 55–77 years with advanced lipedema of the legs and multiple comorbidities. Using this step-by-step approach, a short operation time and early mobilization were possible. Minor adverse effects were temporary methemoglobinemia after tumescent anesthesia and postsurgical pain. No severe adverse effects were seen. Patient satisfaction was high.Conclusion: A tailored approach may be useful in advanced lipedema and is applicable even in elderly patients with multiple comorbidities.Keywords: lipedema, tumescent anesthesia, liposuction, subdermal diode laser, medial thigh lift, lower abdominoplasty

  6. Histological difference between pulsed wave laser and continuous wave laser in endovenous laser ablation.

    Science.gov (United States)

    Kansaku, Rei; Sakakibara, Naoki; Amano, Atsushi; Endo, Hisako; Shimabukuro, Takashi; Sueishi, Michiaki

    2015-07-01

    Endovenous laser ablation to saphenous veins has been popular as a minimally invasive treatment for chronic venous insufficiency. However, adverse effects after endovenous laser ablation using continuous wave laser still remain. Pulsed wave with enough short pulse duration and sufficiently long thermal relaxation time may avoid the excess energy delivery, which leads to the perforation of the vein wall. (1) Free radiation: Laser is radiated in blood for 10 s. (2) Endovenous laser ablation: Veins were filled with blood and placed in saline. Endovenous laser ablations were performed. (1) There were clots on the fiber tips with continuous wave laser while no clots with pulsed wave laser. (2) In 980-nm continuous wave, four of 15 specimens had ulcers and 11 of 15 had perforation. In 1470-nm continuous wave with 120 J/cm of linear endovenous energy density, two of three presented ulcers and one of three showed perforation. In 1470-nm continuous wave with 60 J/cm of linear endovenous energy density, two of four had ulcers and two of four had perforation. In 1320-nm pulsed wave, there were neither ulcers nor perforation in the specimens. While endovenous laser ablation using continuous wave results in perforation in many cases, pulsed wave does not lead to perforation. © The Author(s) 2014.

  7. In situ Diagnostics During Carbon Nanotube Production by Laser Ablation

    Science.gov (United States)

    Arepalli, Sivaram

    1999-01-01

    The preliminary results of spectral analysis of the reaction zone during the carbon nanotube production by laser ablation method indicate synergetic dependence on dual laser setup. The emission spectra recorded from different regions of the laser ablated plume at different delay times from the laser pulses are used to map the temperatures of C2 and C3. These are compared with Laser Induced Fluorescence (LIF) spectra also obtained during production to model the growth mechanism of carbon nanotubes. Experiments conducted to correlate the spectral features with nanotube yields as a function of different production parameters will be discussed.

  8. Excimer laser-assisted recanalisation of femoral arterial stenosis or occlusion caused by the use of Angio-Seal

    Energy Technology Data Exchange (ETDEWEB)

    Steinkamp, H.J.; Werk, M.; Beck, A.; Teichgraeber, U.; Haufe, M.; Felix, R. [Dept. of Radiology, Humboldt Univ. Berlin (Germany)

    2001-08-01

    The aim of this study was to demonstrate the effect of excimer laser and balloon angioplasty of femoral artery stenosis and occlusion after use of a haemostatic puncture closure device. A haemostatic puncture closure device (Angio-Seal) was used in 6000 patients after diagnostic or therapeutic artery catheterisation. In 34 of those patients symptoms of peripheral artery disease occurred. Sixteen of those 34 cases were transferred to our clinic for excimer laser angioplasty. All 16 patients presented with symptoms of acute peripheral artery disease within 1-14 days: superficial femoral artery (SFA) occlusions (4 cases); superficial femoral artery stenosis (3 cases); high-grade stenosis of the common femoral artery (CFA; 3 cases); high-grade stenosis of CFA; SFA and profund femoral artery (PFA; 3 cases); and occlusions of CFA, SFA and PFA (3 cases). Before any procedure was performed, informed consent was given by the patient, which included the use of the Angio-Seal closure device. Every patient who had to undergo recanalisation procedures gave additional informed consent which especially included the usage of the excimer laser for recanalisation. A measurement of the walking distance, ankle-brachial systolic pressure index (ABI) and diagnostic angiography was performed in 13 cases before and immediate after as well as 3 and 6 months after therapeutic percutaneous transluminal laser angioplasty followed by balloon angioplasty (PTLA/PTA). In 3 patients the risks of PTLA/PTA was considered too high; those patients underwent surgical repair. Angiographic and clinical improvement was achieved in 13 of 13 patients. The mean walking distance increased from 81 to >400 m. The average ankle-brachial systolic pressure index (ABI) increased from 0.47 to 0.84. One patient developed a dissection of the SFA, and in 1 case a peripheral embolisation was seen. The PTLA/PTA technique is a successful therapeutic option for patients with femoral artery occlusion or high-grade stenosis

  9. Laser-Assisted Field Evaporation and Three-Dimensional Atom-by-Atom Mapping of Diamond Isotopic Homojunctions.

    Science.gov (United States)

    Mukherjee, Samik; Watanabe, Hideyuki; Isheim, Dieter; Seidman, David N; Moutanabbir, Oussama

    2016-02-10

    It addition to its high evaporation field, diamond is also known for its limited photoabsorption, strong covalent bonding, and wide bandgap. These characteristics have been thought for long to also complicate the field evaporation of diamond and make its control hardly achievable on the atomistic-level. Herein, we demonstrate that the unique behavior of nanoscale diamond and its interaction with pulsed laser lead to a controlled field evaporation thus enabling three-dimensional atom-by-atom mapping of diamond (12)C/(13)C homojunctions. We also show that one key element in this process is to operate the pulsed laser at high energy without letting the dc bias increase out of bounds for diamond nanotip to withstand. Herein, the role of the dc bias in evaporation of diamond is essentially to generate free charge carriers within the nanotip via impact ionization. The mobile free charges screen the internal electric field, eventually creating a hole rich surface where the pulsed laser is effectively absorbed leading to an increase in the nanotip surface temperature. The effect of this temperature on the uncertainty in the time-of-flight of an ion, the diffusion of atoms on the surface of the nanotip, is also discussed. In addition to paving the way toward a precise manipulation of isotopes in diamond-based nanoscale and quantum structures, this result also elucidates some of the basic properties of dielectric nanostructures under high electric field.

  10. Excimer laser assisted very fast exfoliation and reduction of graphite oxide at room temperature under air ambient for Supercapacitors electrode

    Science.gov (United States)

    Malek Hosseini, S. M. B.; Baizaee, S. M.; Naderi, Hamid Reza; Dare Kordi, Ali

    2018-01-01

    Excimer laser was used for reduction and exfoliation of graphite oxide (GO) at room temperature under air ambient. The prepared excimer laser reduced graphite oxide (XLRGO) is characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), nitrogen adsorption/desorption (BET method), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and UV-vis absorption techniques for surface, structural functional groups and band gap analysis. Electrochemical properties are investigated using cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and continues cyclic voltammetry (CCV) in 0.5 M Na2SO4 as electrolyte. Electrochemical investigations revealed that XLRGO electrode has enhanced supercapacitive performance including specific capacitance of 299 F/g at a scan rate of 2 mV/s. Furthermore, CCV measurement showed that XLRGO electrode kept 97.8% of its initial capacitance/capacity after 4000 cycles. The obtained results from electrochemical investigations confirm that the reduction of GO by using an excimer laser produces high-quality graphene for supercapacitor applications without the need for additional operations.

  11. Laser tattoo removal with preceding ablative fractional treatment

    Science.gov (United States)

    Cencič, Boris; Možina, Janez; Jezeršek, Matija

    2013-06-01

    A combined laser tattoo removal treatment, first the ablative fractional resurfacing (AFR) with an Er:YAG laser and then the q-switched (QSW) Nd:YAG laser treatment, was studied. Experiments show that significantly higher fluences can be used for the same tissue damage levels.

  12. Effects of corneal irregular astigmatism on visual acuity after conventional and femtosecond laser-assisted Descemet's stripping automated endothelial keratoplasty.

    Science.gov (United States)

    Tomida, Daisuke; Yamaguchi, Takefumi; Ogawa, Akiko; Hirayama, Yumiko; Shimazaki-Den, Seika; Satake, Yoshiyuki; Shimazaki, Jun

    2015-07-01

    To compare short-term outcomes of Descemet's stripping automated endothelial keratoplasty (DSAEK) using a graft prepared with either a femtosecond laser or a microkeratome. Thirty-eight patients underwent DSAEK with grafts prepared with either a femtosecond laser (f-DSAEK; 21 eyes) or a microkeratome (m-DSAEK; 17 eyes). Visual acuity, endothelial cell density, regular astigmatism and irregular astigmatism were compared between the two groups preoperatively and at 1, 3, and 6 months post-operatively. Fourier analysis was conducted to calculate astigmatism of the anterior and posterior surfaces, and total cornea, using anterior segment optical coherence tomography (AS-OCT). Visual acuity (logMAR) improved from 1.20 ± 0.60 to 0.43 ± 0.25 after m-DSAEK (P astigmatism of the total cornea and the posterior surface was significantly larger after f-DSAEK than after m-DSAEK, although there was no significant difference in irregular astigmatism of the anterior surface at 6 months. Postoperative visual acuity was significantly correlated with the postoperative irregular astigmatism of the total cornea (r = 0.6657 and P astigmatism caused by posterior surface irregularities.

  13. Laser ablation for the synthesis of carbon nanotubes

    Science.gov (United States)

    Holloway, Brian C. (Inventor); Eklund, Peter C. (Inventor); Smith, Michael W. (Inventor); Jordan, Kevin C. (Inventor); Shinn, Michelle (Inventor)

    2012-01-01

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  14. Laser ablation for the synthesis of carbon nanotubes

    Science.gov (United States)

    Holloway, Brian C; Eklund, Peter C; Smith, Michael W; Jordan, Kevin C; Shinn, Michelle

    2012-11-27

    Single walled carbon nanotubes are produced in a novel apparatus by the laser-induced ablation of moving carbon target. The laser used is of high average power and ultra-fast pulsing. According to various preferred embodiments, the laser produces and output above about 50 watts/cm.sup.2 at a repetition rate above about 15 MHz and exhibits a pulse duration below about 10 picoseconds. The carbon, carbon/catalyst target and the laser beam are moved relative to one another and a focused flow of "side pumped", preheated inert gas is introduced near the point of ablation to minimize or eliminate interference by the ablated plume by removal of the plume and introduction of new target area for incidence with the laser beam. When the target is moved relative to the laser beam, rotational or translational movement may be imparted thereto, but rotation of the target is preferred.

  15. Laser-Assisted Periodontal Management of Drug-Induced Gingival Overgrowth under General Anesthesia: A Viable Option

    Directory of Open Access Journals (Sweden)

    Tupili Muralikrishna

    2013-01-01

    Full Text Available Gingival overgrowth/hyperplasia can be attributed to several causes, but drug-induced gingival overgrowth/hyperplasia arises secondarily to prolonged use of antihypertensive drugs, anticonvulsants and immunosuppressants. The management is complex in nature considering the multitude of factors involved such as substitution of drug strict plaque control along with excision of the tissue to be performed under local anesthesia as outpatient. In the recent times, the patient’s psychological fear of the treatment with the use of surgical blade and multiple visits has developed the concept of single visit treatment under general anesthesia incorporating a laser as viable option. The present case highlights the new method of management of gingival overgrowth.

  16. Synchrotron radiation photoionization mass spectrometry of laser ablated species

    OpenAIRE

    Alvarez Ruiz, Jesus; Casu, A.; Coreno, M.; De Simone, M.; Hoyos Campos, L.M.; Juarez-Reyes, A.M.; Kivimäki, A.; Orlando, S.; Sanz, M.; Spezzani, C.; Stankiewicz, M; Trucchi, D. M.

    2010-01-01

    The present paper describes an experimental apparatus suitable to create and study free clusters by combining laser ablation and synchrotron radiation. First tests on sulfur samples, S, showed the production, through laser ablation, of neutral Sn clusters (n = 1–8). These clusters were ionized using synchrotron radiation at photon energies from 160 eV to 175 eV, across the S 2p core edge. The feasibility of such combined ablation–synchrotron radiation experiments is demonstrated, opening new ...

  17. Preparation of antibacterial textile using laser ablation method

    Science.gov (United States)

    Shahidi, Sheila; Rashidian, M.; Dorranian, D.

    2018-02-01

    A facile in situ laser ablation synthesis of Copper nanoparticles on cotton fabric is reported in this paper. This synthetic method is a laser ablation based fabrication of Cu nanoparticles on cotton fabric for improved performance and antibacterial activity. The treated cotton fabric was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, UV-Visible spectroscopic techniques and antibacterial counting test. Very good antibacterial behavior of treated fabrics achieved. This fabric can be used as medical and industrial textiles.

  18. Laser-assisted synthesis, and structural and thermal properties of ZnS nanoparticles stabilised in polyvinylpyrrolidone

    Energy Technology Data Exchange (ETDEWEB)

    Onwudiwe, Damian C. [Chemical Resource Beneficiation (CRB) Research Focus Area, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Krüger, Tjaart P.J. [Department of Physics, University of Pretoria, Private Bag X20, Hatfield 0028 (South Africa); Jordaan, Anine [Laboratory for Electron Microscopy, CRB Research Focus Area, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa); Strydom, Christien A., E-mail: christien.strydom@nwu.ac.za [Chemical Resource Beneficiation (CRB) Research Focus Area, North-West University, Private Bag X6001, Potchefstroom 2520 (South Africa)

    2014-12-01

    Graphical abstract: - Highlights: • Zinc sulphide (ZnS) nanoparticles were synthesised by laser irradiation. • The structural and morphological properties of the prepared samples were analysed. • Larger particles were obtained by using Na{sub 2}S instead of TAA as the sulphur source. • Phonon softening and line broadening of the peaks were observed. • Size reduction occurred in the samples obtained from both sources. - Abstract: Zinc sulphide (ZnS) nanoparticles have been synthesised by a green approach involving laser irradiation of an aqueous solution of zinc acetate (Znac{sub 2}) and sodium sulphide (Na{sub 2}S·9H{sub 2}O) or thioacetamide (TAA) in polyvinylpyrrolidone (PVP). The structural and morphological properties of the prepared samples were analysed using a transmission electron microscope, TEM, a high resolution transmission electron microscope, HRTEM, X-ray diffraction, and Raman spectroscopy. The thermal properties were studied using a simultaneous thermal analyser (SDTA). Better dispersed and larger particles were obtained by using sodium sulphide (Na{sub 2}S) instead of TAA as the sulphur source. X-ray diffraction (XRD) analyses and Raman measurement show that the particles have a cubic structure, which is usually a low temperature phase of ZnS. There were phonon softening and line broadening of the peaks which are attributed to the phonon confinement effect. The average crystallite size of the ZnS nanoparticles estimated from the XRD showed a reduction in size from 13.62 to 10.42 nm for samples obtained from Na{sub 2}S, and 9.13 to 8.16 nm for samples obtained from TAA, with an increase in the time of irradiation. The thermal stability of PVP was increased due to the incorporation of the ZnS nanoparticles in the matrices. The absorption spectra showed that the nanoparticles exhibit quantum confinement effects.

  19. Racing performance following prosthetic laryngoplasty using a polyurethane prosthesis combined with a laser-assisted ventriculocordectomy for treatment of recurrent laryngeal neuropathy in 78 Thoroughbred racehorses.

    Science.gov (United States)

    Raffetto, J A; Wearn, J G; Fischer, A T

    2015-01-01

    Recurrent laryngeal neuropathy (RLN) causes airway obstruction and adversely affects racing performance in Thoroughbred racehorses. Prosthetic laryngoplasty (PL) is the preferred treatment of RLN as it returns variables of airway mechanics to baseline. A number of materials have been evaluated as prostheses; however, the application of Lycra has not been rigorously investigated. To evaluate the efficacy of PL using a Lycra prosthesis, in combination with transendoscopic, laser-assisted ventriculocordectomy, to restore racing performance in Thoroughbred racehorses with RLN. Retrospective case series. Medical records, preoperative and post operative racing performance indices from 78 Thoroughbred racehorses that underwent surgical treatment for RLN were evaluated. Medical records, preoperative and post operative racing performance indices were evaluated. Case history, postoperative complications and PL failure were recorded. Racing performance was analysed using Beyer Speed Figures (BSF), earnings and a performance index (PI), with comparisons made between the 3 races before and after surgery. Factors associated with return to racing and racing performance were analysed. Eighty-two per cent (46/56) of horses that raced prior to surgery and 75% (15/20) of horses that had not raced prior to surgery competed in at least one race post operatively. Horses had a lower BSF and PI in the final race before surgery. Following surgery, PI and BSF values were restored to preoperative values in 73% and 78% of horses respectively. Surgical failure rate and immediate post operative complication rate were lower than, or comparable with,other reported prosthesis materials. Thoroughbred racehorses with RLN have a good prognosis for racing successfully after PL using a Lycra prosthesis. The described surgical technique is associated with a low post operative complication rate and an increase in indicators of racing performance (PI and BSF) post operatively. Lycra offers an attractive

  20. Tailoring through Technology: A Retrospective Review of a Single Surgeon's Experience with Implant-Based Breast Reconstruction before and after Implementation of Laser-Assisted Indocyanine Green Angiography.

    Science.gov (United States)

    Harless, Christin A; Jacobson, Steven R

    2016-05-01

    Reported complication rates of implant-based breast reconstruction in the literature exceed 50%, with mastectomy skin flap necrosis reported to occur in up to 25% of cases. Laser-assisted indocyanine green angiography (LA-ICGA) technology allows the surgeon to optimize preservation of the mastectomy skin flap while avoiding skin necrosis. The purpose of this study was to determine if outcomes of breast reconstruction are beneficially affected by using LA-ICGA. A total 269 consecutive women (467 breast reconstructions) undergoing implant-based breast reconstruction from 2008 to 2013 were examined. The complication rates of those who underwent reconstruction prior to the implementation of LA-ICGA were compared with those who were reconstructed after implementation of LA-ICGA. A total of 254 consecutive breast reconstructions were performed prior to implementation of LA-ICGA, and 213 breasts were reconstructed with the use of LA-ICGA. After implementation of LA-ICGA System, the rate of mastectomy skin flap necrosis decreased by 86% (6.7% versus 0.9%, p = 0.02). The overall complication rate prior to LA-ICGA was 13.8% compared with 6.6% with the use of LA-ICGA (p = 0.01). After LA-ICGA was incorporated, the percentage of patients undergoing single-stage reconstruction increased from 12% to 32% (p = <0.001). Implementation of LA-ICGA provides the surgeon with an objective assessment of mastectomy flap perfusion resulting in a trend toward overall reduction in complications as well as an 86% decrease in the rate of subsequent skin necrosis. The objective assessment of mastectomy flap perfusion allows the surgeon to tailor breast reconstruction intraoperatively, in real-time, adjusting for the individual patient's mastectomy flap perfusion. © 2016 Wiley Periodicals, Inc.

  1. Development of laser ablation plasma by anisotropic self-radiation

    Directory of Open Access Journals (Sweden)

    Ohnishi Naofumi

    2013-11-01

    Full Text Available We have proposed a method for reproducing an accurate solution of low-density ablation plasma by properly treating anisotropic radiation. Monte-Carlo method is employed for estimating Eddington tensor with limited number of photon samples in each fluid time step. Radiation field from ablation plasma is significantly affected by the anisotropic Eddington tensor. Electron temperature around the ablation surface changes with the radiation field and is responsible for the observed emission. An accurate prediction of the light emission from the laser ablation plasma requires a careful estimation of the anisotropic radiation field.

  2. Nanofabrication with Pulsed Lasers

    Directory of Open Access Journals (Sweden)

    Kabashin AV

    2010-01-01

    Full Text Available Abstract An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3, is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.

  3. Ex vivo proof-of-concept of end-to-end scaffold-enhanced laser-assisted vascular anastomosis of porcine arteries.

    Science.gov (United States)

    Pabittei, Dara R; Heger, Michal; van Tuijl, Sjoerd; Simonet, Marc; de Boon, Wadim; van der Wal, Allard C; Balm, Ron; de Mol, Bas A

    2015-07-01

    The low welding strength of laser-assisted vascular anastomosis (LAVA) has hampered the clinical application of LAVA as an alternative to suture anastomosis. To improve welding strength, LAVA in combination with solder and polymeric scaffolds (ssLAVA) has been optimized in vitro. Currently, ssLAVA requires proof-of-concept in a physiologically representative ex vivo model before advancing to in vivo studies. This study therefore investigated the feasibility of ex vivo ssLAVA in medium-sized porcine arteries. Scaffolds composed of poly(ε-caprolactone) (PCL) or poly(lactic-co-glycolic acid) (PLGA) were impregnated with semisolid solder and placed over coapted aortic segments. ssLAVA was performed with a 670-nm diode laser. In the first substudy, the optimum number of laser spots was determined by bursting pressure analysis. The second substudy investigated the resilience of the welds in a Langendorf-type pulsatile pressure setup, monitoring the number of failed vessels. The type of failure (cohesive vs adhesive) was confirmed by electron microscopy, and thermal damage was assessed histologically. The third substudy compared breaking strength of aortic repairs made with PLGA and semisolid genipin solder (ssLAVR) to repairs made with BioGlue. ssLAVA with 11 lasing spots and PLGA scaffold yielded the highest bursting pressure (923 ± 56 mm Hg vs 703 ± 96 mm Hg with PCL ssLAVA; P = .0002) and exhibited the fewest failures (20% vs 70% for PCL ssLAVA; P = .0218). The two failed PLGA ssLAVA arteries leaked at 19 and 22 hours, whereas the seven failed PCL ssLAVA arteries burst between 12 and 23 hours. PLGA anastomoses broke adhesively, whereas PCL welds failed cohesively. Both modalities exhibited full-thickness thermal damage. Repairs with PLGA scaffold yielded higher breaking strength than BioGlue repairs (323 ± 28 N/cm(2) vs 25 ± 4 N/cm(2), respectively; P = .0003). PLGA ssLAVA yields greater anastomotic strength and fewer anastomotic failures than PCL ssLAVA. Aortic

  4. Research of cornea section's shape ablated by 193-nm ArF laser spots

    Science.gov (United States)

    Zhu, Zhiqiang; Yu, Yinshan; Deng, Guoqing

    2005-11-01

    The ablation theory of cornea and biology effect by 193-nm ArF excimer laser are introduced. The ablation tracks model is put forward to make laser spots scan around cornea by many steps and many areas to change cornea curvature. The corneal average ablation curve is calculated by software so as to explain the feasibility of the ablation tracks model. By analyzing the actual ablation shapes of many arbitrary cornea sections, the optimal ablation method for deciding the random position of every laser spot in every ablation track is obtained. Experiments combining the ablation model with the device testify the energy stability of laser spots and the accuracy of rectifying anisometropia.

  5. Mechanisms of Carbon Nanotube Production by Laser Ablation Process

    Science.gov (United States)

    Scott, Carl D.; Arepalli, Sivaram; Nikolaev, Pavel; Smalley, Richard E.; Nocholson, Leonard S. (Technical Monitor)

    2000-01-01

    We will present possible mechanisms for nanotube production by laser oven process. Spectral emission of excited species during laser ablation of a composite graphite target is compared with that of laser irradiated C60 vapor. The similarities in the transient and spectral data suggest that fullerenes are intermediate precursors for nanotube formation. The confinement of the ablation products by means of a 25-mm diameter tube placed upstream of the target seems to improve the production and purity of nanotubes. Repeated laser pulses vaporize the amorphous/graphitic carbon and possibly catalyst particles, and dissociate fullerenes yielding additional feedstock for SWNT growth.

  6. Laser Mediated Cell Ablation During Post-Implantation Mouse Development

    Science.gov (United States)

    Angelo, Jesse R.; Tremblay, Kimberly D.

    2014-01-01

    Background Laser mediated cell ablation is a powerful tool that has been used to understand cell fate in a variety of externally developing organisms but has not been used during mammalian post-implantation development. Results We describe a method pairing laser ablation with murine embryo culture and establish parameters that can be used to precisely ablate cells in the selected field with minimal disruption to adjacent cells or the underlying cell matrix. Ablation of a large domain of endoderm, followed by ~1 day of culture results in a phenotypically normal embryo and gut tube, indicating that laser ablation is compatible with normal development. We next focused on one of the three precursor populations that have been shown to produce the liver bud. Ablations of a single progenitor domain results in a unilateral delay in the liver bud while the contralateral side is unaffected. Conclusions We demonstrate that laser ablation is a specific and useful technique for studying cell fate in the mouse embryo. This method represents a powerful advance in developmental studies in the mouse and can be used to provide information on the specification of organs, differentiation, cell migration and vital tissue interactions during development. PMID:23873840

  7. Clinical outcomes of small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a Meta-analysis

    Directory of Open Access Journals (Sweden)

    Huan Yan

    2017-09-01

    Full Text Available AIM: To evaluate the possible differences in visual quality between small incision lenticule extraction (SMILE and femtosecond laser in situ keratomileusis (FS-LASIK for myopia. METHODS: A Meta-analysis was performed. Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK. The PubMed, EMBASE, Cochrane, Web of Science and Chinese databases (i.e. WANFANG and CNKI were searched in Nov. of 2016 using RevMan 5.1 version software. The differences in visual acuity, aberration and biomechanical effects within six months postoperatively were showed. Twenty-seven studies including 4223 eyes were included. RESULTS: No significant differences were observed between SMILE and FS-LASIK in terms of the proportion of eyes that lost one or more lines of corrected distance visual acuity after surgery (P=0.14, the proportion of eyes achieving an uncorrected distance visual acuity of 20/20 or better (P=0.43, the final refractive spherical equivalent (P=0.89, the refractive spherical equivalent within ±1.00 diopter of the target values (P=0.80, vertical coma (P=0.45 and horizontal coma (P=0.06. Compared with the FS-LASIK group, total higher-order aberration (P<0.001 and spherical aberration (P<0.001 were higher and the decrease in corneal hysteresis (P=0.0005 and corneal resistance factor (P=0.02 were lower in the SMILE group. CONCLUSION: SMILE and FS-LASIK are comparable in efficacy, safety and predictability for correcting myopia. However, the aberration in the SMILE group is superior to that in the FS-LASIK group, and the loss of biomechanical effects may occur less frequently after SMILE than after FS-LASIK.

  8. Transient Newton rings in dielectrics upon fs laser ablation

    CERN Document Server

    Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Solis, Javier

    2014-01-01

    We report the appearance of transient Newton rings in dielectrics (sapphire and lead-oxide glass) during ablation with single fs laser pulses. Employing femtosecond microscopy with 800 nm excitation and 400 nm illumination, we observe a characteristic ring pattern that dynamically changes for increasing delay times between pump and probe pulse. Such transient Newton rings have been previously observed in metals and semiconductors at fluences above the ablation threshold and were related to optical interference of the probe beam reflected at the front surface of the ablating layer and at the interface of the non-ablating substrate. Yet, it had been generally assumed that this phenomenon cannot be (and has not been) observed in dielectrics due to the different ablation mechanism and optical properties of dielectrics. The fact that we are able to observe them has important consequences for the comprehension of the ablation mechanisms in dielectrics and provides a new method for investigating these mechanisms in ...

  9. Laser ablation for protein crystal nucleation and seeding.

    Science.gov (United States)

    Yoshikawa, Hiroshi Y; Murai, Ryota; Adachi, Hiroaki; Sugiyama, Shigeru; Maruyama, Mihoko; Takahashi, Yoshinori; Takano, Kazufumi; Matsumura, Hiroyoshi; Inoue, Tsuyoshi; Murakami, Satoshi; Masuhara, Hiroshi; Mori, Yusuke

    2014-04-07

    With the recent development in pulsed lasers with ultrashort pulse widths or wavelengths, spatially precise, low-damage processing by femtosecond or deep-UV laser ablation has shown promise for the production of protein single crystals suitable for X-ray crystallography. Femtosecond laser processing of supersaturated solutions can shorten the protein nucleation period or can induce nucleation at low supersaturation, which improves the crystal quality of various proteins including membrane proteins and supra-complexes. In addition to nucleation, processing of protein crystals by femtosecond or deep-UV laser ablation can produce single crystalline micro- or macro-seeds without deterioration of crystal quality. This tutorial review gives an overview of the successful application of laser ablation techniques to nucleation and seeding for the production of protein single crystals, and also describes the advantages from a physico-chemical perspective.

  10. Excimer laser ablation of polyimide: a 14-year IBM perspective

    Science.gov (United States)

    Brannon, James H.; Wassick, Thomas A.

    1997-05-01

    IBM introduced the first commercial high-end mainframe computer system incorporating laser ablation technology in 1991. This milestone was the culmination of nearly a decade of scientific, engineering, and manufacturing effort. Extensive research and development on 308 nm laser ablation of polyimide lead to the first IBM prototype ablation tool in 1987 for the production of via-holes in thin film packaging structures. This prototype, similar to step and repeat photolithography systems, evolved into full-scale manufacturing tools which utilize sophisticated beam shaping, beam homogenizing, and projection optics. But the maturity of this technology belies the fact that the scientific understanding of the laser ablation process is still far from complete. This paper briefly reviews the engineering and scientific accomplishments, both within and external to IBM, that lead to the commercial utilization of the laser ablation process. Current technical tissues are discussed, in addition to alternative IBM applications of polyimide ablation. The paper concludes by discussing the relative merits of excimer vs. solid-state lasers, and how each may impact future manufacturing technology.

  11. Ventajas de la cicatrización cutánea asistida por láser (LASH Advantages of laser assisted scar healing (LASH

    Directory of Open Access Journals (Sweden)

    S. Mordon

    2011-12-01

    Full Text Available La fase final de toda cirugía es la sutura y su cicatriz correspondiente y, frecuentemente, ésta es la única secuela visible de una intervención. La técnica LASH (cicatrización cutánea asistida por láser, estimula los mecanismos de reparación de la piel por efecto térmico, condicionando la calidad de la cicatrización. Estudios experimentales en ratones comparando los resultados obtenidos en heridas quirúrgicas radiadas con laser diodo 810 nm tras ser suturadas, con los obtenidos en igual tipo de heridas suturadas de manera convencional, han demostrado que se consiguen cicatrices mucho menos visibles cuando se practica el tratamiento con láser. La histología confirma, comparativamente, una notable aceleración del proceso cicatricial con modificación del TGFβ (Transforming Growth Factor-Beta directamente implicado en la reparación tisular, en los animales en los que la sutura fue asistida por láser. Igualmente, el análisis tensiométrico demostró mayor resistencia a la acción de estiramiento mecánico en estas heridas. Estudios clínicos en pacientes sometidos a dermolipectomia, reducción mamaria y estiramiento facial, demuestran que al tratar con LASH una parte o una de las líneas de sutura, los análisis realizados tanto por los pacientes como por cirujanos independientes a los 8 días, 3 meses y un año, evidencian resultados más favorables para la técnica láser, Las dosis eficaces determinadas para las fluencias láser están entre 80 y 120 J/cm². La técnica LASH es simple de efectuar, reproducible, rápida y ofrece una clara evidencia de que es posible reducir considerablemente la cicatriz, logrando que ésta sea de mejor calidad y más estética.Suture is the final stage of surgery and as a consequence, a scar is frequently the only visible effect after an operation. LASH technique (Laser Assisted Scar Healing produces thermal effects to stimulate mechanisms for tissue repair that will determine the quality of

  12. A retrospective analysis of the postoperative use of loteprednol etabonate gel 0.5% following laser-assisted in situ keratomileusis or photorefractive keratectomy surgery

    Directory of Open Access Journals (Sweden)

    Salinger CL

    2015-11-01

    Full Text Available Clifford L Salinger,1 Michael Gordon,2 Mitchell A Jackson,3 Theodore Perl,4 Eric Donnenfeld5 1VIP Laser Eye Center, Palm Beach Gardens, FL, 2Gordon Weiss Schanzlin Vision Institute, San Diego, CA, 3Jacksoneye, Lake Villa, IL, 4Corneal Associates of New Jersey, Fairfield, NJ, 5Ophthalmic Consultants of Long Island, Garden City, NY, USA Background: While loteprednol etabonate ophthalmic gel 0.5% (LE gel is approved for treatment of postoperative ocular inflammation and pain, there have been no reported studies in patients undergoing laser-assisted in situ keratomileusis (LASIK or photorefractive keratectomy (PRK.Methods: This was a retrospective chart review conducted at five refractive surgical centers in the USA. Data were collected from primary LASIK or PRK surgery cases in which LE gel was used postoperatively as the clinician’s routine standard of care and in which patients were followed-up for up to 6 months. Data extracted from charts included patient demographics, surgical details, LE gel dosing regimen, pre- and postsurgical refractive characteristics, intraocular pressure (IOP measurements, and visual acuity. Primary outcomes included postoperative IOP elevations, adverse events, and early discontinuations.Results: Data were collected on 189 LASIK eyes (96 patients and 209 PRK eyes (108 patients. Mean (standard deviation [SD] years of age at surgery was 36.0 (11.7 and 33.9 (11.3 in LASIK and PRK patients. LE gel was prescribed most often four times daily during the first postoperative week, regardless of procedure; the most common treatment duration was 7–14 days in LASIK and ≥30 days in PRK patients. No unusual corneal findings or healing abnormalities were reported. Mean postoperative uncorrected distance visual acuity was 20/24 in LASIK and 20/30 in PRK eyes. Mild/trace corneal haze was reported in 20% of PRK patients; two PRK patients with moderate/severe corneal haze were switched to another corticosteroid. Mean postoperative

  13. Laser ablation in the management of obstructive uropathy in neonates.

    Science.gov (United States)

    Pagano, Matthew J; van Batavia, Jason P; Casale, Pasquale

    2015-05-01

    Endoscopic management of posterior urethral valves and congenital ureteroceles is the current standard to relieve the obstruction. While the most commonly used techniques involve cystoscopic incision with cold knife or electrosurgery, an alternative is to ablate the obstructive tissue with laser energy. With increasing prenatal diagnoses, there has been an increasing shift in the timing of intervention toward earlier periods. The literature contains only two reports of laser ablation in neonates for these disease entities. A case series was conducted by retrospectively reviewing our surgical database for all consecutive infants laser ablation was used as the exclusive modality of endoscopic management during the study period. All patients were followed with voiding cystourethrogram and renal/bladder ultrasounds postoperatively. Seventeen neonates underwent retrograde transurethral laser ablation procedures at a median age of 7 days (range 3-27). There were nine cases of urethral valve ablation (seven posterior, two anterior) and eight ureterocele ablations. Median operative time was 23 minutes (range 18-33). There were no intraoperative complications or reoperative procedures required for any case. All patients voided after postoperative catheter removal, and no patient had evidence of residual valve tissue or urethral stricture at mean follow-up of 10.1 months. All patients with ureterocele demonstrated partial or complete decompression of the ureterocele and improvement in hydroureteronephrosis at 3 months. Ho:YAG laser ablation appears safe, effective, and efficient for the management of urethral valves and ureteroceles in the neonatal period. With a continuing trend toward early definitive intervention for these conditions, laser ablation remains an important alternative to electrosurgery in this population.

  14. Observation of fs-laser spallative ablation using soft X-ray laser probe

    Science.gov (United States)

    Nishikino, Masaharu; Hasegawa, Noboru; Tomita, Takuro; Minami, Yasuo; Eyama, Takashi; Kakimoto, Naoya; Izutsu, Rui; Baba, Motoyoshi; Kawachi, Tetsuya; Suemoto, Tohru

    2017-03-01

    The initial stages of femtosecond laser ablation of gold were observed by single-shot soft X-ray laser interferometer and reflectometer. The ablation front surface and the spallation shell dome structure were observed from the results of the soft X-ray interferogram, reflective image, and shadowgraph. The formation and evolution of soft X-ray Newton's rings (NRs) were found by reflective imaging at the early stages of the ablation dynamics. The soft X-ray NRs are caused by the interference between the bulk ablated surface and nanometer-scale thin spallation layer. The spallation layer was kept at the late timing of the ablation dynamics, and the height of that reached over 100 μm. The temporal evolution of the bulk ablated surface was observed in the ablation dynamics. From these results, we have succeeded in obtaining the temporal evolution of the ablation front exfoliated from the gold surface.

  15. Laser fiber migration into the pelvic cavity: A rare complication of endovenous laser ablation.

    Science.gov (United States)

    Lun, Yu; Shen, Shikai; Wu, Xiaoyu; Jiang, Han; Xin, Shijie; Zhang, Jian

    2015-10-01

    Endovenous laser ablation is an established alternative to surgery with stripping for the treatment of varicose veins. Ecchymoses and pain are frequently reported side effects of endovenous laser ablation. Device-related complications are rare but serious. We describe here an exceptional complication, necessitating an additional surgical procedure to remove a segment of laser fiber that had migrated into the pelvic cavity. Fortunately, severe damage had not occurred. This case highlights the importance of checking the completeness of the guidewire, catheter, and laser fiber after endovenous laser ablation. © The Author(s) 2014.

  16. Wavelength scaling of silicon laser ablation in picosecond regime

    Science.gov (United States)

    Sikora, A.; Grojo, D.; Sentis, M.

    2017-07-01

    Single pulse laser ablation of silicon has been investigated at 343, 515, and 1030 nm using a laser pulse duration of 50 ps. In this large spectral range, ablation thresholds of silicon vary from 0.01 to 0.83 J/cm2, confirming a strong dependence on the wavelength. By solving the free-carrier density rate equation at threshold conditions, we show that band-to-band linear absorption dominates energy deposition at 343 and 515 nm, whereas at 1030 nm, the energy leading to ablation is primarily absorbed by the generated free-carriers. This allows us to determine the relevant criteria to derive a simple model predicting the wavelength dependence of the ablation threshold in this regime. We obtain an excellent agreement between experimental measurements and calculations by simply considering an averaged energy density required in the absorption depth for surface ablation and accounting for the laser-induced variations of the important thermophysical parameters. On the basis of this analysis, we discuss the optimal wavelength and fluence conditions for maximum removal rate, ablation efficiency, and accuracy. Despite the difference in mechanisms at the different wavelengths, we find that the maximal efficiency remains at around 7 times the ablation threshold fluence for all investigated wavelengths. This work provides guidelines for high-quality and efficient micromachining of silicon in the scarcely explored picosecond regime, while new picosecond sources offer numerous advantages for real throughput industrial applications.

  17. Endovenous laser ablation therapy in children: applications and outcomes.

    Science.gov (United States)

    Patel, Premal A; Barnacle, Alex M; Stuart, Sam; Amaral, Joao G; John, Philip R

    2017-09-01

    Endovenous laser ablation is well recognized as the first-line treatment for superficial venous reflux with varicose veins in adults. It is not widely reported and is not an established practice in pediatric patients. To illustrate a variety of pediatric venous conditions in which endovenous laser ablation can be utilized and to demonstrate its feasibility and safety in children. We conducted a retrospective review of endovenous laser ablation procedures performed between January 2007 and July 2014 at two large pediatric institutions. We included 35 patients (17 males) who underwent endovenous laser ablation to 43 veins. Median age at first treatment was 14 years (range: 3-18 years). Median weight was 56 kg (range: 19-97 kg). Underlying diagnoses were common venous malformation (15), Klippel-Trenaunay syndrome (8), superficial venous reflux with varicose veins (5), verrucous hemangioma-related phlebectasia (4), venous varix (2) and arteriovenous fistula (1). The most common aim of treatment was to facilitate sclerotherapy. Thirty-four patients had treatment in the lower limbs and one patient in an upper limb. Ten of the veins treated with endovenous laser ablation had an additional procedure performed to close the vein. Complications attributable to endovenous laser ablation occurred in two patients (6%). One patient experienced post-procedural pain and one patient developed a temporary sensory nerve injury. Median clinical follow-up was 13 months (range: 28 days-5.7 years). The aim of the treatment was achieved in 29 of the 35 (83%) patients. Endovenous laser ablation is technically feasible and safe in children. It can be used in the management of a range of pediatric venous diseases with good outcomes.

  18. Fs-laser ablation of teeth is temperature limited and provides information about the ablated components.

    Science.gov (United States)

    de Menezes, Rebeca Ferraz; Harvey, Catherine Malinda; de Martínez Gerbi, Marleny Elizabeth Márquez; Smith, Zachary J; Smith, Dan; Ivaldi, Juan C; Phillips, Alton; Chan, James W; Wachsmann-Hogiu, Sebastian

    2017-10-01

    The goal of this work is to investigate the thermal effects of femtosecond laser (fs-laser) ablation for the removal of carious dental tissue. Additional studies identify different tooth tissues through femtosecond laser induced breakdown spectroscopy (fsLIBS) for the development of a feedback loop that could be utilized during ablation in a clinical setting. Scanning Election Microscope (SEM) images reveal that minimal morphological damages are incurred at repetition rates below the carbonization threshold of each tooth tissue. Thermal studies measure the temperature distribution and temperature decay during laser ablation and after laser cessation, and demonstrate that repetition rates at or below 10kHz with a laser fluence of 40 J/cm(2) would inflict minimal thermal damage on the surrounding nerve tissues and provide acceptable clinical removal rates. Spectral analysis of the different tooth tissues is also conducted and differences between the visible wavelength fsLIBS spectra are evident, though more robust classification studies are needed for clinical translation. These results have initiated a set of precautionary recommendations that would enable the clinician to utilize femtosecond laser ablation for the removal of carious lesions while ensuring that the solidity and utility of the tooth remain intact. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Laser ablation deposition measurements from silver and nickel

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Ellegaard, Ole; Schou, Jørgen

    1996-01-01

    The deposition rate for laser ablated metals has been studied in a standard geometry for fluences up to 20 J/cm(2). The rate for silver and nickel is a few percent of a monolayer per pulse at the laser wavelengths 532 nm and 355 nm. The rate for nickel is significantly higher than that for silver...

  20. Explosive onset of continuous wave laser tissue ablation

    NARCIS (Netherlands)

    Verdaasdonk, R. M.; Borst, C.; van Gemert, M. J.

    1990-01-01

    The phenomena at the onset of and during tissue ablation using continuous wave lasers were studied. Aortic and myocardial bovine tissues were exposed in air and in water to Nd-YAG (10 to 60 W) and argon (3.5 W) laser light. The transmitted light was measured, the surface of the tissue was filmed and

  1. UV solid state laser ablation of intraocular lenses

    Science.gov (United States)

    Apostolopoulos, A.; Lagiou, D. P.; Evangelatos, Ch.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.

    2013-06-01

    Commercially available intraocular lenses (IOLs) are manufactured from silicone and acrylic, both rigid (e.g. PMMA) and foldable (hydrophobic or hydrophilic acrylic biomaterials), behaving different mechanical and optical properties. Recently, the use of apodizing technology to design new diffractive-refractive multifocals improved the refractive outcome of these intraocular lenses, providing good distant and near vision. There is also a major ongoing effort to refine laser refractive surgery to correct other defects besides conventional refractive errors. Using phakic IOLs to treat high myopia potentially provides better predictability and optical quality than corneal-based refractive surgery. The aim of this work was to investigate the effect of laser ablation on IOL surface shaping, by drilling circular arrays of holes, with a homemade motorized rotation stage, and scattered holes on the polymer surface. In material science, the most popular lasers used for polymer machining are the UV lasers, and, therefore, we tried in this work the 3rd and the 5th harmonic of a Q-switched Nd:YAG laser (λ=355 nm and λ=213 nm respectively). The morphology of the ablated IOL surface was examined with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variations in surface height and, finally, the ablation rates were also mathematically simulated for depicting the possible laser ablation mechanism(s). The experimental results and the theoretical modelling of UV laser interaction with polymeric IOLs are discussed in relation with the physical (optical, mechanical and thermal) properties of the material, in addition to laser radiation parameters (laser energy fluence, number of pulses). The qualitative aspects of laser ablation at λ=213 nm reveal a

  2. CT-guided laser probe for ablation of brain tumors

    Directory of Open Access Journals (Sweden)

    Abdolhadi Daneshi

    2010-01-01

    Full Text Available   Abstract  In this study, 22 patients (15-75 years old were selected and transferred to CT scan for tumor ablation. For ablations, after prep and drep under the local anesthesia and mild sedation in proper position, small incision made and special needle inserted and guided by proper direction to the core of the tumor. Then, laser probe inserted through the needle and laser energy delivered. Although we have not a good prognosis in metastatic tumors but post-operative follow up and brain CT scan established the effect of laser on resection and evaporation and diminution of mass effect in tumor lesions.

  3. Near-field mapping by laser ablation of PMMA coatings

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana

    The optical near-field of lithography-defined gold nanostructures, arranged into regular arrays on a gold film, is characterized via ablation of a polymer coating by laser illumination. The method utilizes femto-second laser pulses from a laser scanning microscope which induces electrical field....... The obtained experimental results for different polymer coating thicknesses and nanostructure geometries are in good agreement with theoretical calculations of the near field distribution for corresponding enhancement mechanisms. The developed method and its tunable experimental parameters show...... that the different stages in the ablation process can be controlled and characterized making the technique suitable for characterizing optical near-fields of metal nanostructures....

  4. Plasma mediated ablation of biological tissues with ultrashort laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Oraevsky, A.A. [Lawrence Livermore National Lab., CA (United States)]|[Rice Univ., Houston, TX (United States). Dept. of Electrical Engineering; DaSilva, L.B.; Feit, M.D. [Lawrence Livermore National Lab., CA (United States)] [and others

    1995-03-08

    Plasma mediated ablation of collagen gels and porcine cornea was studied at various laser pulse durations in the range from 350 fs to 1 ns at 1,053 nm wavelength. A time resolved stress detection technique was employed to measure transient stress profiles and amplitudes. Optical microscopy was used to characterize ablation craters qualitatively, while a wide band acoustic transducer helped to quantify tissue mechanical response and the ablation threshold. The ablation threshold was measured as a function of laser pulse duration and linear absorption coefficient. For nanosecond pulses the ablation threshold was found to have a strong dependence on the linear absorption coefficient of the material. As the pulse length decreased into the subpicosecond regime the ablation threshold became insensitive to the linear absorption coefficient. The ablation efficiency was found to be insensitive to both the laser pulse duration and the linear absorption coefficient. High quality ablation craters with no thermal or mechanical damage to surrounding material were obtained with 350 fs laser pulses. The mechanism of optical breakdown at the tissue surface was theoretically investigated. In the nanosecond regime, optical breakdown proceeds as an electron collisional avalanche ionization initiated by thermal seed electrons. These seed electrons are created by heating of the tissue by linear absorption. In the ultrashort pulse range, optical breakdown is initiated by the multiphoton ionization of the irradiated medium (6 photons in case of tissue irradiated at 1,053 nm wavelength), and becomes less sensitive to the linear absorption coefficient. The energy deposition profile is insensitive to both the laser pulse duration and the linear absorption coefficient.

  5. Assisted laser ablation: silver/gold nanostructures coated with silica

    Science.gov (United States)

    González-Castillo, J. R.; Rodríguez-González, Eugenio; Jiménez-Villar, Ernesto; Cesar, Carlos Lenz; Andrade-Arvizu, Jacob Antonio

    2017-11-01

    The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO3 and HAuCl4 aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag+ and Au3+ concentration, as well as the Ag+/Au3+ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

  6. Assisted laser ablation: silver/gold nanostructures coated with silica

    Science.gov (United States)

    González-Castillo, J. R.; Rodríguez-González, Eugenio; Jiménez-Villar, Ernesto; Cesar, Carlos Lenz; Andrade-Arvizu, Jacob Antonio

    2017-09-01

    The synthesis processes of metallic nanoparticles have seen a growing interest in recent years, mainly by the potential applications of the phenomenon of localized surface plasmon resonance associated with metallic nanoparticles. This paper shows a fast method to synthesize silver, gold and silver/gold alloy nanoparticles coated with a porous silica shell by the assisted laser ablation method in three steps. The method involves a redox chemical reaction where the reducing agent is supplied in nanometric form by laser ablation. In the first step, a silicon target immersed in water is ablated for several minutes. Later, AgNO3 and HAuCl4 aliquots are added to the solution. The redox reaction between the silver and gold ions and products resulting from ablation process can produce silver, gold or silver/gold alloy nanoparticles coated with a porous silica shell. The influence of the laser pulse energy, ablation time, Ag+ and Au3+ concentration, as well as the Ag+/Au3+ ratio, on optical and structural properties of the nanostructures was investigated. This work represents a step forward in the study of reaction mechanisms that take place during the synthesis of nanoscale materials by the assisted laser ablation technique.

  7. Spatiotemporal closure of fractional laser-ablated channels imaged by optical coherence tomography and reflectance confocal microscopy.

    Science.gov (United States)

    Banzhaf, Christina A; Wind, Bas S; Mogensen, Mette; Meesters, Arne A; Paasch, Uwe; Wolkerstorfer, Albert; Haedersdal, Merete

    2016-02-01

    Optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) offer high-resolution optical imaging of the skin, which may provide benefit in the context of laser-assisted drug delivery. We aimed to characterize postoperative healing of ablative fractional laser (AFXL)-induced channels and dynamics in their spatiotemporal closure using in vivo OCT and RCM techniques. The inner forearm of healthy subjects (n = 6) was exposed to 10,600 nm fractional CO2 laser using 5 and 25% densities, 120 μm beam diameter, 5, 15, and 25 mJ/microbeam. Treatment sites were scanned with OCT to evaluate closure of AFXL-channels and RCM to evaluate subsequent re-epithelialization. OCT and RCM identified laser channels in epidermis and upper dermis as black, ablated tissue defects surrounded by characteristic hyper-and hyporeflective zones. OCT imaged individual laser channels of the entire laser grid, and RCM imaged epidermal cellular and structural changes around a single laser channel to the depth of the dermoepidermal junction (DEJ) and upper papillary dermis. OCT images visualized a heterogeneous material in the lower part of open laser channels, indicating tissue fluid. By OCT the median percentage of open channels was evaluated at several time points within the first 24 hours and laser channels were found to gradually close, depending on the used energy level. Thus, at 5 mJ/microbeam, 87% (range 73-100%) of channels were open one hour after laser exposure, which declined to 27% (range 20-100%) and 20% (range 7-93%) at 12 and 24 hours after laser exposure, respectively. At 25 mJ/microbeam, 100% (range 100-100%) of channels were open 1 hour after laser exposure while 53% (range 33-100%) and 40% (range 0-100%) remained open at 12 and 24 hours after exposure. Median depth and width of open channels decreased over time depending of applied energy. RCM verified initial re-epithelialization from day 2 for all energy levels used. Morphology of ablation defects by OCT and

  8. A prospective comparison of phakic collamer lenses and wavefront-optimized laser-assisted in situ keratomileusis for correction of myopia

    Directory of Open Access Journals (Sweden)

    Parkhurst GD

    2016-06-01

    Full Text Available Gregory D Parkhurst1,2 1Refractive Surgery Center, Carl R Darnall Army Medical Center, Fort Hood, 2Parkhurst NuVision, San Antonio, TX, USA Purpose: The aim of this study was to evaluate and compare night vision and low-luminance contrast sensitivity (CS in patients undergoing implantation of phakic collamer lenses or wavefront-optimized laser-assisted in situ keratomileusis (LASIK.Patients and methods: This is a nonrandomized, prospective study, in which 48 military personnel were recruited. Rabin Super Vision Test was used to compare the visual acuity and CS of Visian implantable collamer lens (ICL and LASIK groups under normal and low light conditions, using a filter for simulated vision through night vision goggles.Results: Preoperative mean spherical equivalent was –6.10 D in the ICL group and –6.04 D in the LASIK group (P=0.863. Three months postoperatively, super vision acuity (SVa, super vision acuity with (low-luminance goggles (SVaG, super vision contrast (SVc, and super vision contrast with (low luminance goggles (SVcG significantly improved in the ICL and LASIK groups (P<0.001. Mean improvement in SVaG at 3 months postoperatively was statistically significantly greater in the ICL group than in the LASIK group (mean change [logarithm of the minimum angle of resolution, LogMAR]: ICL =-0.134, LASIK =-0.085; P=0.032. Mean improvements in SVc and SVcG were also statistically significantly greater in the ICL group than in the LASIK group (SVc mean change [logarithm of the CS, LogCS]: ICL =0.356, LASIK =0.209; P=0.018 and SVcG mean change [LogCS]: ICL =0.390, LASIK =0.259; P=0.024. Mean improvement in SVa at 3 months was comparable in both groups (P=0.154.Conclusion: Simulated night vision improved with both ICL implantation and wavefront-optimized LASIK, but improvements were significantly greater with ICLs. These differences may be important in a military setting and may also affect satisfaction with civilian vision correction

  9. Subcellular distribution of daunorubicin in P-glycoprotein-positive and -negative drug-resistant cell lines using laser-assisted confocal microscopy.

    Science.gov (United States)

    Gervasoni, J E; Fields, S Z; Krishna, S; Baker, M A; Rosado, M; Thuraisamy, K; Hindenburg, A A; Taub, R N

    1991-09-15

    Four well defined multidrug-resistant cell lines and their drug-sensitive counterparts were examined for intracellular distribution of daunorubicin (DNR) by laser-assisted confocal fluorescence microscopy: P-glycoprotein-negative HL-60/AR cells, and P-glycoprotein-positive P388/ADR, KBV-1, and MCF-7/ADR cells. Both drug sensitive cell lines (HL-60/S, P388/S, KB3-1, and MCF-7/S) and drug-resistant cell lines (HL-60/AR, P388/ADR, KBV-1, and MCF-7/ADR) exposed to DNR showed a similar rapid distribution of drug from the plasma membrane to the perinuclear region within the first 2 min. From 2-10 min, the drug sensitive HL-60/S, P388/S, and MCF-7/S cells redistributed drug to the nucleus and to the cytoplasm in a diffuse pattern. In contrast, drug-resistant HL-60/AR, P388/ADR, and MCF-7/ADR redistributed DNR from the perinuclear region into vesicles distinct from nuclear structures, thereby assuming a "punctate" pattern. This latter redistribution could be inhibited by glucose deprivation (indicating energy dependence), or by lowering the temperature of the medium below 18 degrees C. The differences in distribution between sensitive and resistant cells did not appear to be a function of intracellular DNR content, nor the result of drug cytotoxicity. Drug-sensitive KB3-1 and -resistant KBV-1 cells did not fully follow this pattern in that they demonstrated an intracellular DNR distribution intermediate between HL-60/S and HL-60/AR cells with both "punctate" and nuclear/cytoplasmic uptake sometimes in the same cell. These data indicate that the intracellular distribution of DNR is an important determinant of drug resistance regardless of the overexpression of P-glycoprotein. The intracellular movement of drug requires the presence of glucose and a temperature above 18 degrees C, implicating energy-dependent processes and vesicle fusion in the distribution process. This intracellular transport of DNR away from the nucleus in multidrug-resistant cells may protect putative

  10. Small Incision Lenticule Extraction (SMILE versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK for Myopia: A Systematic Review and Meta-Analysis.

    Directory of Open Access Journals (Sweden)

    Zeren Shen

    Full Text Available The goal of this study was to compare small incision lenticule extraction (SMILE with femtosecond laser-assisted in situ keratomileusis (FS-LASIK for treating myopia.The CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA, uncorrected visual acuity (UCVA of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI, tear breakup time (TBUT and Schirmer's 1 test (S1T as dry eye parameters, along with corneal sensitivity.The overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16, UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16, logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87, postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97 or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70 within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006 and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P < 0.00001 at six months postoperatively.In conclusion, both FS-LASIK and SMILE are safe

  11. Femtosecond laser ablation of diamond-like carbon films

    Energy Technology Data Exchange (ETDEWEB)

    Dumitru, Gabriel; Romano, Valerio; Weber, Heinz P.; Pimenov, Sergei; Kononenko, Taras; Sentis, Marc; Hermann, Joerg; Bruneau, Sebastien

    2004-01-30

    Diamond-like carbon (DLC) coatings were deposited on Si substrates using a hot filament diode discharge and they were irradiated with ultrashort laser pulses (800 nm, 150 fs, <4 J/cm{sup 2}). The laser-treated films were examined using optical microscopy, Raman spectroscopy, SEM, AFM and white-light interferometery. Damage threshold of 0.16 J/cm{sup 2} and ablation rates below 110 nm/pulse were determined. Changes in the structure of the laser-irradiated films were showed by means of Raman investigations. The laser-treated samples were etched and the depths of modified material layers were determined. Ablation experiments with longer laser pulses (1064 nm, 100 ns, <3 J/cm{sup 2}) were also performed and the irradiated DLC films were afterwards analyzed using the same procedures. Dissimilarities in the structure changes induced by fs-and ns-laser irradiation were observed and comments are given.

  12. Photoactive dye-enhanced tissue ablation for endoscopic laser prostatectomy.

    Science.gov (United States)

    Ahn, Minwoo; Hau, Nguyen Trung; Van Phuc, Nguyen; Oh, Junghwan; Kang, Hyun Wook

    2014-11-01

    Laser light has been widely used as a surgical tool to treat benign prostate hyperplasia (BPH) over 20 years. Recently, application of high laser power up to 200 W was often reported to swiftly remove a large amount of prostatic tissue. The purpose of this study was to validate the feasibility of photoactive dye injection to enhance light absorption and eventually to facilitate tissue vaporization with low laser power. Chicken breast tissue was selected as a target tissue due to minimal optical absorption at the visible wavelength. Four biocompatible photoactive dyes, including amaranth (AR), black dye (BD), hemoglobin powder (HP), and endoscopic marker (EM), were selected and tested in vitro with a customized 532 nm laser system with radiant exposure ranging from 0.9 to 3.9 J/cm(2) . Light absorbance and ablation threshold were measured with UV-Vis spectrometer and Probit analysis, respectively, and compared to feature the function of the injected dyes. Ablation performance with dye-injection was evaluated in light of radiant exposure, dye concentration, and number of injection. Higher light absorption by injected dyes led to lower ablation threshold as well as more efficient tissue removal in the order of AR, BD, HP, and EM. Regardless of the injected dyes, ablation efficiency principally increased with radiant exposure, dye concentration, and number of injection. Among the dyes, AR created the highest ablation rate of 44.2 ± 0.2 µm/pulse due to higher absorbance and lower ablation threshold. High aspect ratios up to 7.1 ± 0.4 entailed saturation behavior in the tissue ablation injected with AR and BD, possibly resulting from plume shielding and increased scattering due to coagulation. Preliminary tests on canine prostate with a hydraulic injection system demonstrated that 80 W with dye injection yielded comparable ablation efficiency to 120 W with no injection, indicating 33% reduced laser power with almost equivalent performance. Due to

  13. Noninvasive delivery of siRNA and plasmid DNA into skin by fractional ablation: erbium:YAG laser versus CO₂ laser.

    Science.gov (United States)

    Lee, Woan-Ruoh; Shen, Shing-Chuan; Chen, Wei-Yu; Aljuffali, Ibrahim A; Suen, Shih-Yun; Fang, Jia-You

    2014-04-01

    The present study was conducted to evaluate the impacts of fractional erbium (Er):YAG and CO2 lasers on skin permeation of small interfering (si)RNA and plasmid (p)DNA vectors. In vitro skin delivery was determined with a Franz diffusion cell. In vivo absorption was investigated by observing fluorescence and confocal microscopic imaging. Fractional laser-mediated ablation of the skin resulted in significant enhancement of dextran and siRNA penetration. Respective fluxes of dextran (10 kDa) and siRNA, which had similar molecular size, with Er:YAG laser irradiation at 5 J/cm(2) were 56- and 11-fold superior to that of intact skin. The respective permeation extents of dextran and siRNA by the CO2 laser at 4 mJ/400 spots were 42- and 12-fold greater than that of untreated skin. Fluorescence and confocal images showed increased fluorescence intensities and penetration depths of siRNA and pDNA delivery. According to an examination of the follicular permeant amount and fluorescence microscopy, hair follicles were important deposition areas for fractional laser-assisted delivery, with the Er:YAG modality revealing higher follicular siRNA selectivity than the CO2 modality. This is the first report of siRNA and pDNA penetrating the skin with a sufficient amount and depth with the assistance of fractional lasers. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Ablation from metals induced by visible and UV laser irradiation

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Schou, Jørgen; Thestrup Nielsen, Birgitte

    1996-01-01

    The deposition rate of laser-ablated silver has been determined for fluences between 0.5 and 15 J/cm2 at the wavelengths 532 and 355 nm for a beam spot area of around 0.01 cm2. The ablated metal was collected on a quartz crystal microbalance. The rate at 5 J/cm2 was about 4 × 1013 Ag/cm2 per puls...

  15. Impact of liquid environment on femtosecond laser ablation

    Science.gov (United States)

    Kanitz, A.; Hoppius, J. S.; Fiebrandt, M.; Awakowicz, P.; Esen, C.; Ostendorf, A.; Gurevich, E. L.

    2017-11-01

    The ablation rate by femtosecond laser processing of iron in different liquids is investigated for fluences up to 5 J/cm^2. The resulting fluence dependency is modeled by an approach derived from the two-temperature model. In our experiments, the liquid environment strongly affects the effective penetration depth, e.g, the ablation rate in water is almost ten times higher than in toluene. This effect is discussed and introduced phenomenologically into the model. Additional reflectivity measurements and plasma imaging provide improved insight into the ablation process.

  16. Influence of laser ablation parameters on trueness of imaging

    Energy Technology Data Exchange (ETDEWEB)

    Vaculovič, T.; Warchilová, T. [Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); CEITEC, Masaryk University, Kamenice 5, Brno 62500 (Czech Republic); Čadková, Z.; Száková, J.; Tlustoš, P. [Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcka 129, Praha 16521 (Czech Republic); Otruba, V. [Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); Kanický, V., E-mail: viktork@chemi.muni.cz [Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, Brno 61137 (Czech Republic); CEITEC, Masaryk University, Kamenice 5, Brno 62500 (Czech Republic)

    2015-10-01

    Highlights: • Laser ablation conditions vs. quality of LA-ICP-MS imaging (resolution, detection). • Increase in laser spot size improves detection limit, while deteriorates resolution. • Decrease in scan speed improves resolution but prolongs time of analysis. • Compromise spot size and scan speed meet required quality of imaging. • Metal-enriched/depleted zones in tapeworm sections were resolved by LA-ICP-MS. - Abstract: Influence of laser ablation conditions on limit of detection, spatial resolution and time of analysis was studied for laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) applied to elemental mapping. Laser repetition rate and laser fluence were investigated in tapeworm thin section to attain optimum ablation rate, yielding appropriately low detection limit which complies with elemental contents in the tissue. Effect of combinations of laser spot size and scan speed on relative broadening (Δw{sub rel}) of image of the ablated pattern (line) was investigated with the aim to quantify the trueness of imaging. Ink lines printed on paper were employed for the study of influence of spot size and scan speed on limit of detection, relative broadening of elemental image and duration of elemental mapping. An uneven distribution of copper in a printed line (coffee stain effect) was observed. The Δw{sub rel} is strongly reduced (down to 2%) at low scan speed (10 μm s{sup −1}) and laser spot diameter of 10 μm but resulting in unacceptably long time of mapping (up to 3000 min). Finally, tapeworm thin-section elemental maps (4 mm × 5 mm) were obtained at the laser spot diameter of 65 μm and the scan speed of 65 μm s{sup −1} within 100 min. A dissimilar lateral distribution of Pb was observed in comparison with that of Cu or Zn due to different pathways of element uptake.

  17. Effect analysis of material properties of picosecond laser ablation for ABS/PVC

    Science.gov (United States)

    Tsai, Y. H.; Ho, C. Y.; Chiou, Y. J.

    2017-06-01

    This paper analytically investigates the picosecond laser ablation of ABS/PVC. Laser-pulsed ablation is a wellestablished tool for polymer. However the ablation mechanism of laser processing for polymer has not been thoroughly understood yet. This study utilized a thermal transport model to analyze the relationship between the ablation rate and laser fluences. This model considered the energy balance at the decomposition interface and Arrhenius law as the ablation mechanisms. The calculated variation of the ablation rate with the logarithm of the laser fluence agrees with the measured data. It is also validated in this work that the variation of the ablation rate with the logarithm of the laser fluence obeys Beer's law for low laser fluences. The effects of material properties and processing parameters on the ablation depth per pulse are also discussed for picosecond laser processing of ABS/PVC.

  18. Two-Dimensional Fluorescence Spectroscopy for Measuring Uranium Isotopes in Femtosecond Laser Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C.; Brumfield, Brian E.; Harilal, Sivanandan S.; Hartig, Kyle C.; Jovanovic, Igor

    2017-05-30

    We present the first two-dimensional fluorescence spectroscopy measurements of uranium isotopes in femtosecond laser ablation plasmas. A new method of signal normalization is presented to reduce noise in absorption-based measurements of laser ablation.

  19. Aggregation effect on absorbance spectrum of laser ablated gold nanoparticles

    Science.gov (United States)

    Isnaeni; Irmaniar; Herbani, Y.

    2017-04-01

    Plasmon of gold nanoparticles is one of the hot topics nowadays due to various possible applications. The application is determined by plasmon peak in absorbance spectrum. We have fabricated gold nanoparticles using laser ablation technique and studied the influence of CTAB (Cetyl trimethylammonium bromide) effect on the optical characterization of fabricated gold nanoparticles. We ablated a gold plate using NdYAG pulsed laser at 1064 nm wavelength, 10 Hz pulse frequency at low energy density. We found there are two distinctive plasmon peaks, i.e., primary and secondary peaks, where the secondary peak is the main interests of this work. Our simulation results have revealed that the secondary plasmon peak is affected by random aggregation of gold nanoparticles. Our research leads to good techniques on fabrication of colloidal gold nanoparticles in aqueous solution using laser ablation technique.

  20. Infrared Laser Ablation with Vacuum Capture for Fingermark Sampling

    Science.gov (United States)

    Donnarumma, Fabrizio; Camp, Eden E.; Cao, Fan; Murray, Kermit K.

    2017-09-01

    Infrared laser ablation coupled to vacuum capture was employed to collect material from fingermarks deposited on surfaces of different porosity and roughness. Laser ablation at 3 μm was performed in reflection mode with subsequent capture of the ejecta with a filter connected to vacuum. Ablation and capture of standards from fingermarks was demonstrated on glass, plastic, aluminum, and cardboard surfaces. Using matrix assisted laser desorption ionization (MALDI), it was possible to detect caffeine after spiking with amounts as low as 1 ng. MALDI detection of condom lubricants and detection of antibacterial peptides from an antiseptic cream was demonstrated. Detection of explosives from fingermarks left on plastic surfaces as well as from direct deposition on the same surface using gas chromatography mass spectrometry (GC-MS) was shown. [Figure not available: see fulltext.

  1. Ablative Laser Propulsion Using Multi-Layered Material Systems

    Science.gov (United States)

    Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

    2002-01-01

    Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

  2. Direct coupling of a laser ablation cell to an AMS

    Energy Technology Data Exchange (ETDEWEB)

    Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Muensterer, C. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Laboratory for Inorganic Chemistry, ETH Zurich, 8093 Zurich (Switzerland); Hattendorf, B. [Laboratory for Inorganic Chemistry, ETH Zurich, 8093 Zurich (Switzerland); Christl, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Guenther, D. [Laboratory for Inorganic Chemistry, ETH Zurich, 8093 Zurich (Switzerland); Synal, H.-A. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland)

    2013-01-15

    In rare cases, cleaned samples can be directly inserted into a negative ion source of an AMS and still meet the requirements for long-term and stable measurements. We present the coupling of a laser ablation system to the gas ion source of an AMS system (MICADAS, ETH Zurich) for direct and continuous CO{sub 2} introduction. Solid carbonate samples like stalagmites or corals are suitable sample materials, which can be ablated and decomposed continuously using a pulsed laser focused onto the surface of a solid sample, which is placed in an airtight ablation cell. CO{sub 2} formed during the ablation of a CaCO{sub 3} sample is continually flushed with He into the gas ion source. The production rate of CO{sub 2} can be adjusted via the laser pulse repetition rate (1-20 Hz), the crater diameter (1-150 {mu}m) and the energy density applied (0.2-3 mJ/pulse) of the laser (frequency quintupled Nd:YAG at 213 nm with 5 ns pulse duration). In our first test, measurements of one sample with known age were replicated within one sigma. Blanks showed 5% contamination of modern carbon of yet unknown origin. In order to develop LA-AMS into a routine sampling tool the ablation cell geometry and settings of the gas ion source have to be further optimized.

  3. Aerospace Laser Ignition/Ablation Variable High Precision Thruster

    Science.gov (United States)

    Campbell, Jonathan W. (Inventor); Edwards, David L. (Inventor); Campbell, Jason J. (Inventor)

    2015-01-01

    A laser ignition/ablation propulsion system that captures the advantages of both liquid and solid propulsion. A reel system is used to move a propellant tape containing a plurality of propellant material targets through an ignition chamber. When a propellant target is in the ignition chamber, a laser beam from a laser positioned above the ignition chamber strikes the propellant target, igniting the propellant material and resulting in a thrust impulse. The propellant tape is advanced, carrying another propellant target into the ignition chamber. The propellant tape and ignition chamber are designed to ensure that each ignition event is isolated from the remaining propellant targets. Thrust and specific impulse may by precisely controlled by varying the synchronized propellant tape/laser speed. The laser ignition/ablation propulsion system may be scaled for use in small and large applications.

  4. Enthalpy model for heating, melting, and vaporization in laser ablation

    Directory of Open Access Journals (Sweden)

    Vasilios Alexiades

    2010-09-01

    Full Text Available Laser ablation is used in a growing number of applications in various areas including medicine, archaeology, chemistry, environmental and materials sciences. In this work the heat transfer and phase change phenomena during nanosecond laser ablation of a copper (Cu target in a helium (He background gas at atmospheric pressure are presented. An enthalpy model is outlined, which accounts for heating, melting, and vaporization of the target. As far as we know, this is the first model that connects the thermodynamics and underlying kinetics of this challenging phase change problem in a self-consistent way.

  5. Long-pulsed dye laser versus long-pulsed dye laser-assisted photodynamic therapy for acne vulgaris: A randomized controlled trial

    DEFF Research Database (Denmark)

    Haedersdal, M.; Togsverd, K.; Wiegell, S.R.

    2008-01-01

    Background: Long-pulsed dye laser (LPDL)-assisted photodynamic therapy has been suggested to be superior to laser alone for acne vulgaris but no evidence is available. Objective: To evaluate the efficacy and safety of LPDL alone versus LPDL in photodynamic therapy with methylaminolevulinic acid (...

  6. Formation and characterization of nanoparticles via laser ablation in solution

    Science.gov (United States)

    Golightly, Justin Samuel

    The work presented in this thesis encompassed laser ablation of various transition metals within a liquid environment. Through an improved understanding of the ablation process, control over the properties of the resultant nanoparticles can be obtained, and thusly nanoparticles can be tailored with specific properties. Creation of nanoparticles via laser ablation in solution is a relatively youngtechnique for nanoparticle synthesis, and the work presented should prove useful in guiding further exploration in ablation processes in liquids for nanomaterial production. When a laser is focused onto a target under a liquid environment, the target material and its surrounding liquid are vaporized. The concoction of vapor is ejected normal to the surface as a bubble. The bubble has a temperature reaching the boiling point of the metal, and has a gradient to the boiling point of the solvent. The bubble expands until it reaches a critical volume, and then subsequently collapses. It is within this bubble that nanoparticle formation occurs. As the bubble expands, the vapor cools and nanoparticle growth transpires. During the bubble collapse, pressures reaching GigaPascals have been reported, and a secondary nanoparticle formation occurs as a result of these high pressures. Chapter 1 delves a little more into the nanoparticle formation mechanisms, as well as an introduction to the analytical techniques used for characterization. Ablation of titanium took place in isopropanol, ethanol, water, and n-hexane, under various fluences, with a 532 nm Nd:YAG operating at 10 Hz. It was found that a myriad of nanoparticles could be made with vastly different compositions that were both solvent and fluence dependent. Nanoparticles were made that incorporated carbon and oxygen from the solvent, showing how solvent choice is an important factor in nanoparticle creation. Chapter 3 discusses the results of the titanium work in great detail and demonstrates carbide production with ablation in

  7. Comparative shock wave analysis during corneal ablation with an excimer laser, picosecond laser, and femtosecond laser

    Science.gov (United States)

    Krueger, Ronald R.; Juhasz, Tibor

    1995-05-01

    With the event of topographic steep central islands following excimer laser surgery and the potential damage to the corneal endothelium, shock waves are playing an increasingly important role in laser refractive surgery. With this in mind, we performed a comparative shock wave analysis in corneal tissue using an excimer laser, picosecond laser, and femtosecond laser. We used a Lambda Physik excimer laser at 308 nm wavelength, a Nd:YLF picosecond laser at 1053 nm wavelength and a synchronously pumped linear cavity femtosecond laser at 630 nm wavelength. The pulse widths of the corresponding lasers were 8 ns, 18 ps, 150 fs, respectively. The energy density of irradiation was 2.5 to 8 times the threshold level being 2 J/cm2 (excimer laser), 86 J/cm2 (picosecond laser) and 10.3 J/cm2 (femtosecond laser). Shock wave dynamics were analyzed using time-resolved photography on a nanosecond time scale using the picosecond laser in corneal tissue, water and air. Shock wave dynamics using the femtosecond laser were studied in water only while the excimer laser induced shock wave during corneal ablation was studied in air only. We found the dynamics of shock waves to be similar in water and corneal tissue indicating that water is a good model to investigate shock wave effects in the cornea. The magnitude of the shock wave velocity and pressure decays over time to that of a sound wave. The distance over which it decays is 3 mm in air with the excimer laser and 600 - 700 micrometers in air with the picosecond laser. In water, the picosecond laser shock wave decays over a distance of 150 micrometers compared to the femtosecond laser shock wave which decays over a distance of 30 micrometers . Overall the excimer laser shock wave propagates 5 times further than that of the picosecond laser and the picosecond laser shock wave propagates 5 times further than that of the femtosecond laser. In this preliminary comparison, the time and distance for shock wave decay appears to be directly

  8. Production of nanoparticles from natural hydroxylapatite by laser ablation

    Directory of Open Access Journals (Sweden)

    Boutinguiza Mohamed

    2011-01-01

    Full Text Available Abstract Laser ablation of solids in liquids technique has been used to obtain colloidal nanoparticles from biological hydroxylapatite using pulsed as well as a continuous wave (CW laser. Transmission electron microscopy (TEM measurements revealed the formation of spherical particles with size distribution ranging from few nanometers to hundred nanometers and irregular submicronic particles. High resolution TEM showed that particles obtained by the use of pulsed laser were crystalline, while those obtained by the use of CW laser were amorphous. The shape and size of particles are consistent with the explosive ejection as formation mechanism.

  9. Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

    Science.gov (United States)

    Peña-Díaz, M.; Ponce, L.; Arronte, M.; Flores, T.

    2007-04-01

    Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

  10. Emission spectroscopy analysis during Nopal cladodes dethorning by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Diaz, M; Ponce, L; Arronte, M; Flores, T [Laboratorio TecnologIa Laser, CICATA-IPN, Unidad Altamira, Carretera Tampico-Puerto Ind. Altamira, 89600, TAMPS (Mexico)

    2007-04-15

    Optical emission spectroscopy of the pulsed laser ablation of spines and glochids from Opuntia (Nopal) cladodes was performed. Nopal cladodes were irradiated with Nd:YAG free-running laser pulses on their body, glochids and spines. Emission spectroscopy analyses in the 350-1000 nm region of the laser induced plasma were made. Plasma plume evolution characterization, theoretical calculations of plasma plume temperature and experiments varying the processing atmosphere showed that the process is dominated by a thermally activated combustion reaction which increases the dethorning process efficiency. Therefore, appropriate laser pulse energy for minimal damage of cladodes body and in the area beneath glochids and spines can be obtained.

  11. Erosion of nanostructured tungsten by laser ablation, sputtering and arcing

    Directory of Open Access Journals (Sweden)

    Dogyun Hwangbo

    2017-08-01

    Full Text Available Mass loss of nanostructured tungsten, which was formed by helium plasma irradiation, due to laser ablation, sputtering, and arcing was investigated. Below the helium sputtering energy threshold (200eV. Reduction in sputtering on nanostructured surface was observed. Arcing was initiated using laser pulses, and the erosion rate by arcing was measured. The erosion rate increased with arc current, while the erosion per Coulomb was not affected by arc current.

  12. Angular distributions and total yield of laser ablated silver

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Nordskov, A.; Schou, Jørgen

    1997-01-01

    The angular distribution of laser ablated silver has been measured in situ with a newly constructed setup with an array of microbalances. The distribution is strongly peaked in the forward direction corresponding to cospθ, where p varies between 5 and 9 for laser fluences from 2 to 7 J/cm2 at 355...... nm for a beam spot of 0.015 cm2. The total deposited yield is of the order 1015 Ag-atoms per pulse....

  13. Aluminum nanoparticles production by laser ablation in liquids

    Science.gov (United States)

    Damian, V.; Udrea, C.; Bojan, M.; Luculescu, C.; Armaselu, A.; Apostol, I.

    2011-05-01

    Aluminium nanoparticles were produced by pulsed laser ablation of a sample of pure aluminium situated in distilled water. This technique provides the possibility to generate a large variety of nanoparticles that are free of both surfaceactive substances and counter-ions The sample was irradiated by the focused output of the third harmonics of pulsed nanosecond Nd : YAG laser operating at 10 Hz frequency. The typical thickness of the liquid above the target was 10 mm. In order to select the most efficient material removal conditions the irradiation print on the ablated surface was analyzed as a function of the irradiation parameters (incident laser fluence, irradiation pulses number or irradiation time) with optical microscopy and white light interferometry. The presence of the ablated aluminium nanoparticles in the liquid was evidenced by SEM. For SEM measurement, one drop of solution containing Al nanoparticles was placed on a gold coated silicon substrate and dried. The minimum diameter of nanoparticles estimated by SEM was under 100 nm. The SEM results show also clusters of spherical particles together with well-defined singles. In order to improve the quantity of the ablated material the irradiation cell was mounted on a computer-driven X-Y stage and translated during laser exposure.

  14. Absorption Enhanced Liquid Ablation with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sterling, Enrique

    2004-01-01

    ... that strongly absorbs radiation in the 8-11 m wavelength interval. A TEA CO2 laser (λ = 10.6 m), 300 ns pulse width and 8 J pulse energy, was used for ablation of water diluted NaBF4 contained in a conical aluminum nozzle...

  15. Femtosecond laser ablation of gold interdigitated electrodes for electronic tongues

    Science.gov (United States)

    Manzoli, Alexandra; de Almeida, Gustavo F. B.; Filho, José A.; Mattoso, Luiz H. C.; Riul, Antonio; Mendonca, Cleber R.; Correa, Daniel S.

    2015-06-01

    Electronic tongue (e-tongue) sensors based on impedance spectroscopy have emerged as a potential technology to evaluate the quality and chemical composition of food, beverages, and pharmaceuticals. E-tongues usually employ transducers based on metal interdigitated electrodes (IDEs) coated with a thin layer of an active material, which is capable of interacting chemically with several types of analytes. IDEs are usually produced by photolithographic methods, which are time-consuming and costly, therefore, new fabrication technologies are required to make it more affordable. Here, we employed femtosecond laser ablation with pulse duration of 50 fs to microfabricate gold IDEs having finger width from 2.3 μm up to 3.2 μm. The parameters used in the laser ablation technique, such as light intensity, scan speed and beam spot size have been optimized to achieve uniform IDEs, which were characterized by optical and scanning electron microscopy. The electrical properties of gold IDEs fabricated by laser ablation were evaluated by impedance spectroscopy, and compared to those produced by conventional photolithography. The results show that femtosecond laser ablation is a promising alternative to conventional photolithography for fabricating metal IDEs for e-tongue systems.

  16. Formation of Fibrosis After Nonablative and Ablative Fractional Laser Therapy

    NARCIS (Netherlands)

    Wind, Bas S.; Meesters, Arne A.; Kroon, Marije W.; Beek, Johan F.; van der Veen, J. P. Wietze; van der Wal, Allard C.; Bos, Jan D.; Wolkerstorfer, Albert

    2012-01-01

    BACKGROUND Fractional laser therapy (FLT) has become a widely accepted modality for skin rejuvenation and has also been used in various other skin diseases. OBJECTIVE To observe long-term histologic effects of nonablative and ablative FLT in the treatment of pigment disorders. METHODS A randomized

  17. Superhydrophobic/superoleophilic magnetic elastomers by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Milionis, Athanasios, E-mail: am2vy@virginia.edu [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Fragouli, Despina; Brandi, Fernando; Liakos, Ioannis; Barroso, Suset [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy); Athanassiou, Athanassia, E-mail: athanassia.athanassiou@iit.it [Smart Materials-Nanophysics, Istituto Italiano di Tecnologia (IIT), Via Morego 30, 16163 Genova (Italy)

    2015-10-01

    Highlights: • We report the development of magnetic nanocomposite sheets. • Laser irradiation of the nanocomposites induces chemical and structural changes to the surface. • The laser-patterned surfaces exhibit superhydrophobicity and superoleophilicity. • The particle contribution in altering the surface and bulk properties of the material is studied. - Abstract: We report the development of magnetic nanocomposite sheets with superhydrophobic and supeoleophilic surfaces generated by laser ablation. Polydimethylsiloxane elastomer free-standing films, loaded homogeneously with 2% wt. carbon coated iron nanoparticles, were ablated by UV (248 nm), nanosecond laser pulses. The laser irradiation induces chemical and structural changes (both in micro- and nano-scale) to the surfaces of the nanocomposites rendering them superhydrophobic. The use of nanoparticles increases the UV light absorption efficiency of the nanocomposite samples, and thus facilitates the ablation process, since the number of pulses and the laser fluence required are greatly reduced compared to the bare polymer. Additionally the magnetic nanoparticles enhance significantly the superhydrophobic and oleophilic properties of the PDMS sheets, and provide to PDMS magnetic properties making possible its actuation by a weak external magnetic field. These nanocomposite elastomers can be considered for applications requiring magnetic MEMS for the controlled separation of liquids.

  18. Pulsed laser deposition: metal versus oxide ablation

    NARCIS (Netherlands)

    Doeswijk, L.M.; Rijnders, Augustinus J.H.M.; Blank, David H.A.

    2004-01-01

    We present experimental results of pulsed laser interaction with metal (Ni, Fe, Nb) and oxide (TiO2, SrTiO3, BaTiO3) targets. The influence of the laser fluence and the number of laser pulses on the resulting target morphology are discussed. Although different responses for metal and oxide targets

  19. Laser ablation of the protein lysozyme

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Amoruso, Salvatore

    to a substrate as intact molecules by the violent laser impact ( up to 50 mJ/pulse) has not yet been understood. One issue is that up to 150 ng/pulse is removed by the laser, and much of the material is ejected from the target in relatively large chunks. We have explored as well the excitation mechanics by laser...

  20. Laser-Assisted Synthesis of Mn0.50Zn0.50Fe2O4 Nanomaterial: Characterization and In Vitro Inhibition Activity towards Bacillus subtilis Biofilm

    Directory of Open Access Journals (Sweden)

    Shaukat Ali Shahid

    2015-01-01

    Full Text Available There is growing interest in the development of novel nanomaterials with potential antimicrobial activity and lesser toxicity. In the current research work, Mn0.5Zn0.5Fe2O4 nanoparticles were synthesized via a novel coprecipitation cum laser ablation technique yielding fine spinal structured material. The synthesized nanomaterial was structurally characterized by X-ray diffraction technique which confirmed the formation and the crystalline nature of Mn0.50Zn0.50Fe2O4 nanomaterial. The crystallite size determined by Debye-Scherrer’s formula was found to be ~12 nm. The formation of nanoparticles was evidenced by scanning electron microscopy. Energy dispersive X-ray analysis (EDXA was performed for elemental analysis. The synthesized nanomaterial was interestingly found to be an effective antimicrobial agent and inhibited the growth of Bacillus subtilis biofilm formation. The 5 µg of Mn0.5Zn0.5Fe2O4 nanomaterial dissolved in 1 mL of DMSO showed excellent biofilm inhibitory activity 91.23% ± 1.87 against Bacillus subtilis.

  1. Programmable Laser-Assisted Surface Microfabrication on a Poly(Vinyl Alcohol)-Coated Glass Chip with Self-Changing Cell Adhesivity for Heterotypic Cell Patterning.

    Science.gov (United States)

    Li, Yi-Chen; Lin, Meng-Wei; Yen, Meng-Hua; Fan, Sabrina Mai-Yi; Wu, June-Tai; Young, Tai-Horng; Cheng, Ji-Yen; Lin, Sung-Jan

    2015-10-14

    Organs are composed of heterotypic cells with patterned architecture that enables intercellular interaction to perform specific functions. In tissue engineering, the ability to pattern heterotypic cells into desired arrangement will allow us to model complex tissues in vitro and to create tissue equivalents for regeneration. This study was aimed at developing a method for fast heterotypic cell patterning with controllable topological manipulation on a glass chip. We found that poly(vinyl alcohol)-coated glass showed a biphasic change in adhesivity to cells in vitro: low adhesivity in the first 24 h and higher adhesivity at later hours due to increased serum protein adsorption. Combining programmable CO2 laser ablation to remove poly(vinyl alcohol) and glass, we were able to create arrays of adhesive microwells of adjustable patterns. We tested whether controllable patterns of epithelial-mesenchymal interaction could be created. When skin dermal papilla cells and fibroblasts were seeded respectively 24 h apart, we were able to pattern these two cells into aggregates of dermal papilla cells in arrays of microwells in a background of fibroblasts sheet. Seeded later, keratinocytes attached to these mesenchymal cells. Keratinocytes contacting dermal papilla cells started to differentiate toward a hair follicle fate, demonstrating patternable epithelial-mesenchymal interaction. This method allows fast adjustable heterotypic cell patterning and surface topology control and can be applied to the investigation of heterotypic cellular interaction and creation of tissue equivalent in vitro.

  2. Ablation of Liquids for Laser Propulsion with TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr, Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 micro-m, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  3. Ablation of Liquids for Laser Propulsion With TEA CO2 Laser

    National Research Council Canada - National Science Library

    Sinko, John; Kodgis, Lisa; Porter, Simon; Sterling, Enrique; Lin, Jun; Pakhomov, Andrew V; Larson, C. W; Mead, Jr., Franklin B

    2005-01-01

    .... A Transversely Excited at Atmospheric pressure (TEA) CO2 laser operated at 10.6 um, 300 ns pulse width, and 9 J pulse energy was used to ablate liquids contained in various aluminum and glass vessels...

  4. Numerical analysis of laser ablation and damage in glass with multiple picosecond laser pulses.

    Science.gov (United States)

    Sun, Mingying; Eppelt, Urs; Russ, Simone; Hartmann, Claudia; Siebert, Christof; Zhu, Jianqiang; Schulz, Wolfgang

    2013-04-08

    This study presents a novel numerical model for laser ablation and laser damage in glass including beam propagation and nonlinear absorption of multiple incident ultrashort laser pulses. The laser ablation and damage in the glass cutting process with a picosecond pulsed laser was studied. The numerical results were in good agreement with our experimental observations, thereby revealing the damage mechanism induced by laser ablation. Beam propagation effects such as interference, diffraction and refraction, play a major role in the evolution of the crater structure and the damage region. There are three different damage regions, a thin layer and two different kinds of spikes. Moreover, the electronic damage mechanism was verified and distinguished from heat modification using the experimental results with different pulse spatial overlaps.

  5. Percutaneous laser ablation of unresectable primary and metastatic adrenocortical carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Pacella, Claudio M. [Regina Apostolorum Hospital, Department of Diagnostic Imaging and Interventional Radiology, Via San Francesco 50, Albano Laziale, Rome 00041 (Italy)], E-mail: claudiomaurizio.pacella@fastwebnet.it; Stasi, Roberto; Bizzarri, Giancarlo; Pacella, Sara; Graziano, Filomena Maria; Guglielmi, Rinaldo; Papini, Enrico [Regina Apostolorum Hospital, Department of Diagnostic Imaging and Interventional Radiology, Via San Francesco 50, Albano Laziale, Rome 00041 (Italy)

    2008-04-15

    Purpose: To evaluate the feasibility, safety, and clinical benefits of percutaneous laser ablation (PLA) in patients with unresectable primary and metastatic adrenocortical carcinoma (ACC). Patients and methods: Four patients with hepatic metastases from ACC and a Cushing's syndrome underwent ultrasound-guided PLA. In one case the procedure was performed also on the primary tumor. Results: After three sessions of PLA, the primary tumor of 15 cm was ablated by 75%. After 1-4 (median 1) sessions of PLA, five liver metastases ranging from 2 to 5 cm were completely ablated, while the sixth tumor of 12 cm was ablated by 75%. There were no major complications. Treatment resulted in an improvement of performance status and a reduction of the daily dosage of mitotane in all patients. The three patients with liver metastases presented a marked decrease of 24-h urine cortisol levels, an improved control of hypertension and a mean weight loss of 2.8 kg. After a median follow-up after PLA of 27.0 months (range, 9-48 months), two patients have died of tumor progression, while two other patients remain alive and free of disease. Conclusions: Percutaneous laser ablation is a feasible, safe and well tolerated procedure for the palliative treatment of unresectable primary and metastatic ACC. Further study is required to evaluate the impact of PLA on survival.

  6. A rare complication of endovenous laser ablation: intravascular laser catheter breakage.

    Science.gov (United States)

    Bozoglan, Orhan; Mese, Bulent; Inci, Mehmet Fatih; Eroglu, Erdinc

    2013-03-18

    During endovenous laser ablation, which is performed as an alternative to surgery for the treatment of superficial venous insufficiency of lower extremity and associated varicose veins, it was realised that the distal end of the catheter protecting the fibre sheared off; the retained catheter fragment in the saphenous vein was removed by a mini incision. Herein, we aim to present a rare complication of endovenous laser ablation.

  7. Laser cellulite treatment and laser-assisted lipoplasty of the thighs and buttocks: Combined modalities for single stage contouring of the lower body.

    Science.gov (United States)

    Petti, Christine; Stoneburner, Jacqueline; McLaughlin, Laura

    2016-01-01

    Cellulite and lipodystrophy are often found together, especially in areas of the buttocks and thighs, causing skin surface irregularities. Each of these conditions is currently treated independently as two separate surgical procedures. In our practice, we developed a novel combined approach for the simultaneous treatment of cellulite and lipodystrophy, as a single stage procedure in the same anatomic area. For the treatment of cellulite, we used the Nd:YAG laser at a wavelength of 1,440-nm, along with an innovative 1,000-micron directional side-firing fiber optic laser system. For the treatment of lipodystrophy, the Nd:YAG laser with a 1,440 nm wavelength, along with a fiber optic laser system was used. The objective of this study is to determine the efficacy and safety of a combined approach for the simultaneous treatment of cellulite and lipodystrophy. In 2012, 16 subjects with noticeable cellulite, Grade II and Grade III, accompanied by mild-to-moderate lipodystrophy of the lower body received single treatments of the Nd:YAG laser at a wavelength of 1,440-nm along with the 1,000-micron side-firing fiber optic laser system for simultaneous treatments of both cellulite and lipodystrophy. Patients were assessed at baseline and 3-6 months post-treatment by a modified Nurnberger-Muller scale utilized to quantify the cellulite severity. Additionally, patient satisfaction and a global aesthetic improvement scale were used to measure the improvement in lipodystrophy. Blinded reviewers identified the correct baseline photographs 97% of the time when presented with a set of photographs. The median modified Nurnberger-Muller scale score at baseline was 4.75 ± 1.2 and the average improvement was 2.0 ± 1.2. Global aesthetic improvement scores ranged from 1 to 3 with an average of 1.58 indicating a much-improved overall appearance. Satisfaction was high for both physicians and patients with scores corresponding to extremely satisfied/satisfied. Precise, effective

  8. Charging and plasma effects under ultrashort pulsed laser ablation

    Science.gov (United States)

    Bulgakova, N. M.; Bulgakov, A. V.; Zhukov, V. P.; Marine, W.; Vorobyev, A. Y.; Guo, Chunlei

    2008-05-01

    Based on experiments and a theoretical analysis, we raise questions on two fundamental mechanisms of femtosecond laser desorption/ablation of solids, namely Coulomb explosion (CE) and plasma etching. The effects of laser-induced ionization and surface charging are analyzed which can be responsible for ultrafast ions observed in time-of-flight mass-spectra under ultrashort laser irradiation of solids. The importance of surface charging in formation of velocity distributions of desorbed/ablated species has been revealed for conditions when the CE mechanism is inhibited. The influence of ambient plasma formation on the dynamics of heating of metallic targets by femtosecond laser pulses is studied based on 2D modeling of laser-induced target heating and dynamics of the ambient plasma. The calculations show an intriguing picture of the laser-induced ambient gas motion. We propose a model of laser-induced breakdown of an ambient gas in a region in front of the irradiated target and analyze plasma-chemical processes which can affect laser processing of surfaces in the presence of air or highly reactive media.

  9. Clinical effects of non-ablative and ablative fractional lasers on various hair disorders: a case series of 17 patients.

    Science.gov (United States)

    Cho, Suhyun; Choi, Min Ju; Zheng, Zhenlong; Goo, Boncheol; Kim, Do-Young; Cho, Sung Bin

    2013-04-01

    Both ablative and non-ablative fractional lasers have been applied to various uncommon hair disorders. The purpose of this study was to demonstrate the clinical effects of fractional laser therapy on the course of primary follicular and perifollicular pathologies and subsequent hair regrowth. A retrospective review of 17 patients with uncommon hair disorders - including ophiasis, autosomal recessive woolly hair/hypotrichosis, various secondary cicatricial alopecias, pubic hypotrichosis, frontal fibrosing alopecia, and perifolliculitis abscedens et suffodiens - was conducted. All patients had been treated with non-ablative and/or ablative fractional laser therapies. The mean clinical improvement score in these 17 patients was 2.2, while the mean patient satisfaction score was 2.5. Of the 17 subjects, 12 (70.6%) demonstrated a clinical response to non-ablative and/or ablative fractional laser treatments, including individuals with ophiasis, autosomal recessive woolly hair/hypotrichosis, secondary cicatricial alopecia (scleroderma and pressure-induced alopecia), frontal fibrosing alopecia, and perifolliculitis abscedens et suffodiens. Conversely, patients with long-standing ophiasis, surgical scar-induced secondary cicatricial alopecia, and pubic hypotrichosis did not respond to fractional laser therapy. Our findings demonstrate that the use of non-ablative and/or ablative fractional lasers promoted hair growth in certain cases of uncommon hair disorders without any remarkable side effects.

  10. Near-field mapping by laser ablation of PMMA coatings

    DEFF Research Database (Denmark)

    Fiutowski, Jacek; Maibohm, Christian; Kostiucenko, Oksana

    The optical near-field of lithography-defined gold nanostructures, arranged into regular arrays on a gold film, is characterized via ablation of a polymer coating by laser illumination. The method utilizes femto-second laser pulses from a laser scanning microscope which induces electrical field...... enhancements on and around the gold nanostructures. At the positions of the enhancements, the ablation threshold of the polymer coating is significantly lowered creating subdiffractional topographic modifications on the surface which are quantified via scanning electron microscopy and atomic force microscopy....... The obtained experimental results for different polymer coating thicknesses and nanostructure geometries are in good agreement with theoretical calculations of the near field distribution for corresponding enhancement mechanisms. The developed method and its tunable experimental parameters show...

  11. Saphenous ablation: what are the choices, laser or RF energy.

    Science.gov (United States)

    Morrison, Nick

    2005-03-01

    Endovenous ablation has been reported to be safe and effective in eliminating the proximal portion of the great saphenous vein from the venous circulation, with faster recovery and better cosmetic results than surgical stripping. However, the definition of a successful outcome in the literature has not been uniform. As in a successful stripping procedure, complete elimination of at least the proximal portion of the great saphenous vein should also be the standard for these endovenous ablation procedures. Our experience with over 1,400 endovenous ablation procedures, of which 1,150 were radiofrequency and over 250 were laser procedures, has allowed evaluation and comparison of these two techniques. And while we have not seen as high success rates as in published reports (especially with laser ablation), we have still concluded that both radiofrequency and laser techniques to destroy the saphenous vein are safe and effective. Patient acceptance is overwhelmingly better than stripping. Physicians performing these techniques should embrace a commitment to addressing all sites of venous insufficiency in a patient, not just the proximal great saphenous vein. Without this level of commitment, one will be left with poor results and a dissatisfied patient.

  12. Laser ablation of titanium in liquid in external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

    2015-09-01

    Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.

  13. Laser ablation of silver and gold in liquid ammonia

    Science.gov (United States)

    Šmejkal, Petr; Pfleger, Jiří; Vlčková, Blanka

    2010-10-01

    Laser ablation of a silver (Ag) and/or gold (Au) target was performed in liquid ammonia (l-NH3) at 233 K using nanosecond laser pulses of 1064, 532 and 355 nm wavelengths. An “in situ” monitoring of the ablation process by UV/vis/NIR spectroscopy has shown the evolution of the surface plasmon extinction band of silver or gold nanoparticles and thus confirmed their formation. While sols of Au nanoparticles in l-NH3 are quite stable in air, those of Ag nanoparticles undergo oxidation to Ag(I) complexes with NH3 ligands. On the other hand, formation of solvated electrons, namely of the (e-)NH3 solvates, has not been unequivocally confirmed under the conditions of our laser ablation/nanoparticle fragmentation experiment, since only very weak vis/NIR spectral features of these solvates were observed with a low reproducibility. Reference experiments have shown that the well-known chemical production of these solvates is hindered by the presence of Ag and Au plates. Ag and Au targets can thus possibly act as electron scavengers in our ablation experiments.

  14. Infrared laser ablation atmospheric pressure photoionization mass spectrometry.

    Science.gov (United States)

    Vaikkinen, Anu; Shrestha, Bindesh; Kauppila, Tiina J; Vertes, Akos; Kostiainen, Risto

    2012-02-07

    In this paper we introduce laser ablation atmospheric pressure photoionization (LAAPPI), a novel atmospheric pressure ion source for mass spectrometry. In LAAPPI the analytes are ablated from water-rich solid samples or from aqueous solutions with an infrared (IR) laser running at 2.94 μm wavelength. Approximately 12 mm above the sample surface, the ablation plume is intercepted with an orthogonal hot solvent (e.g., toluene or anisole) jet, which is generated by a heated nebulizer microchip and directed toward the mass spectrometer inlet. The ablated analytes are desolvated and ionized in the gas-phase by atmospheric pressure photoionization using a 10 eV vacuum ultraviolet krypton discharge lamp. The effect of operational parameters and spray solvent on the performance of LAAPPI is studied. LAAPPI offers ~300 μm lateral resolution comparable to, e.g., matrix-assisted laser desorption ionization. In addition to polar compounds, LAAPPI efficiently ionizes neutral and nonpolar compounds. The bioanalytical application of the method is demonstrated by the direct LAAPPI analysis of rat brain tissue sections and sour orange (Citrus aurantium) leaves. © 2012 American Chemical Society

  15. Thermal Ablation of Colorectal Lung Metastases: Retrospective Comparison Among Laser-Induced Thermotherapy, Radiofrequency Ablation, and Microwave Ablation.

    Science.gov (United States)

    Vogl, Thomas J; Eckert, Romina; Naguib, Nagy N N; Beeres, Martin; Gruber-Rouh, Tatjana; Nour-Eldin, Nour-Eldin A

    2016-12-01

    The purpose of this study is to retrospectively evaluate local tumor control, time to tumor progression, and survival rates among patients with lung metastatic colorectal cancer who have undergone ablation therapy performed using laser-induced thermotherapy (LITT), radiofrequency ablation (RFA), or microwave ablation (MWA). Data for this retrospective study were collected from 231 CT-guided ablation sessions performed for 109 patients (71 men and 38 women; mean [± SD] age, 68.6 ± 11.2 years; range, 34-94 years) from May 2000 to May 2014. Twenty-one patients underwent LITT (31 ablations), 41 patients underwent RFA (75 ablations), and 47 patients underwent MWA (125 ablations). CT scans were acquired 24 hours after each therapy session and at follow-up visits occurring at 3, 6, 12, 18, and 24 months after ablation. Survival rates were calculated from the time of the first ablation session, with the use of Kaplan-Meier and log-rank tests. Changes in the volume of the ablated lesions were measured using the Kruskal-Wallis method. Local tumor control was achieved in 17 of 25 lesions (68.0%) treated with LITT, 45 of 65 lesions (69.2%) treated with RFA, and 91 of 103 lesions (88.3%) treated with MWA. Statistically significant differences were noted when MWA was compared with LITT at 18 months after ablation (p = 0.01) and when MWA was compared with RFA at 6 months (p = 0.004) and 18 months (p = 0.01) after ablation. The overall median time to local tumor progression was 7.6 months. The median time to local tumor progression was 10.4 months for lesions treated with LITT, 7.2 months for lesions treated with RFA, and 7.5 months for lesions treated with MWA, with no statistically significant difference noted. New pulmonary metastases developed in 47.6% of patients treated with LITT, in 51.2% of patients treated with RFA, and in 53.2% of patients treated with MWA. According to the Kaplan-Meier test, median survival was 22.1 months for patients who underwent LITT, 24.2 months

  16. Langmuir probe study of plasma expansion in pulsed laser ablation

    DEFF Research Database (Denmark)

    Hansen, T.N.; Schou, Jørgen; Lunney, J.G.

    1999-01-01

    Langmuir probes were used to monitor the asymptotic expansion of the plasma produced by the laser ablation of a silver target in a vacuum. The measured angular and temporal distributions of the ion flux and electron temperature were found to be in good agreement with the self-similar isentropic a...... and adiabatic solution of the gas dynamics equations describing the expansion. The value of the adiabati