WorldWideScience

Sample records for low-power laser irradiation

  1. Low power laser irradiation does not affect the generation of signals in a sensory receptor

    Energy Technology Data Exchange (ETDEWEB)

    Lundeberg, T.; Zhou, J.

    1989-01-01

    The effect of low power Helium-Neon (He-Ne) and Gallium-Arsenide (Ga-As) laser on the slowly adapting crustacean stretch receptor was studied. The results showed that low power laser irradiation did not affect the membrane potential of the stretch receptor. These results are discussed in relation to the use of low power laser irradiation on the skin overlaying acupuncture points in treatment of pain syndrome.

  2. Manipulating the mitochondria activity in human hepatic cell line Huh7 by low-power laser irradiation

    Science.gov (United States)

    Lynnyk, Anna; Lunova, Mariia; Jirsa, Milan; Egorova, Daria; Kulikov, Andrei; Kubinová, Šárka; Lunov, Oleg; Dejneka, Alexandr

    2018-01-01

    Low-power laser irradiation of red light has been recognized as a promising tool across a vast variety of biomedical applications. However, deep understanding of the molecular mechanisms behind laser-induced cellular effects remains a significant challenge. Here, we investigated mechanisms involved in the death process in human hepatic cell line Huh7 at a laser irradiation. We decoupled distinct cell death pathways targeted by laser irradiations of different powers. Our data demonstrate that high dose laser irradiation exhibited the highest levels of total reactive oxygen species production, leading to cyclophilin D-related necrosis via the mitochondrial permeability transition. On the contrary, low dose laser irradiation resulted in the nuclear accumulation of superoxide and apoptosis execution. Our findings offer a novel insight into laser-induced cellular responses, and reveal distinct cell death pathways triggered by laser irradiation. The observed link between mitochondria depolarization and triggering ROS could be a fundamental phenomenon in laser-induced cellular responses. PMID:29541521

  3. Biochemical and topological analysis of bovine sperm cells induced by low power laser irradiation

    Science.gov (United States)

    Dreyer, T. R.; Siqueira, A. F. P.; Magrini, T. D.; Fiorito, P. A.; Assumpção, M. E. O. A.; Nichi, M.; Martinho, H. S.; Milazzotto, M. P.

    2011-07-01

    Low-level laser irradiation (LLLI) increases ATP production and energy supply to the cell which could increase sperm motility, acrossomal reaction and consequently the fertilizing potential. The aim of this study was to characterize the biochemical and topological changes induced by low power laser irradiation on bull sperm cells. Post-thawing sperm were irradiated with a 633nm laser with fluence rates of 30, 150 and 300mJ.cm-2 (power of 5mW for 1, 5 and 10minutes, respectively); 45, 230, and 450mJ.cm-2 (7.5mW for 1, 5 and 10 minutes); and 60, 300 and 600mJ.cm-2 (10mW for 1, 5 and 10 minutes). Biochemical and metabolical changes were analyzed by FTIR and flow cytometry; oxygen reactive species production was assessed by TBARS and the morphological changes were evaluated by AFM. Motility had no difference among times or powers of irradiation. Increasing in ROS generation was observed with power of 5mW compared to 7.5 and 10mW, and with 10min of irradiation in comparison with 5 and 1min of irradiation. This higher ROS generation was related to an increase in acrossomal and plasma membrane damage. FTIR results showed that the amount of lipids was inversely proportional to the quantity of ROS generated. AFM images showed morphological differences in plasma/acrossomal membrane, mainly on the equatorial region. We conclude that LLLI is an effective method to induce changes on sperm cell metabolism but more studies are necessary to establish an optimal dose to increase the fertility potential of these cells.

  4. Action of low-power laser irradiation on the proliferation of human gingival fibroblasts in vitro

    Science.gov (United States)

    Almeida-Lopes, Luciana; Jaeger, Marcia M. M.; Brugnera, Aldo, Jr.; Rigau, Josepa

    1998-04-01

    The low level power laser has been used in dental treatments aiming to improve tissue healing. An in vitro study was performed to analyze the laser influence on gingival fibroblast. A human gingival fibroblast culture (LMF) was produced in DME medium with 10% bovine fetal serum (BFS) cells (LMF) were allocated in Petri plates and cultured in different SFB concentrations (0%, 5% e 10%). After 48 hours the plates were divided in 9 groups: 3 control: 3 irradiated by 635 nm laser; and 3 irradiated by 780 nm laser. The cultured cells received 4 applications, in 12 hours intervals, with energy dosage of 2 joules for each plate, by means of a punctual technique. The growth curves showed that the growth levels were lower in low BFS concentrations. The irradiation with laser accelerated the growth rate in all groups. Additionally, the number of cells developed in low BFS concentration (5%) and irradiated was similar to the number of control cells developed in ideal conditions (10% BFS). There was no statistically significant differences between the effects of the two types of laser studied.

  5. Effect of low-power red light laser irradiation on the viability of human skin fibroblast

    Energy Technology Data Exchange (ETDEWEB)

    Bednarska, K.; Rozga, B.; Leyko, W.; Bryszewska, M. [Institute of Biophysics, University of Lodz (Poland); Kolodziejczyk, K.; Szosland, D. [Diabetological Clinic, Medical Academy of Lodz (Poland)

    1998-10-01

    Human skin fibroblast monolayers (S-126 cell line) were exposed to laser radiation (wavelength 670 nm, power density 40 mW/cm{sup 2}). The energy densities were 2 J/cm{sup 2} and 12 J/cm{sup 2}, respectively, and the irradiation was carried out at a temperature of 22 C. For fibroblast viability evaluation, the colorimetric assay (conversion of thiazolyl blue to formazan) was used. The experiments were carried out at 37 C, in the presence of 5% CO{sub 2}, and at different time periods of incubation after irradiation (2, 4, 8 h and 1, 2, 3, 4, 5 days). The results indicated that there was a certain stimulating effect on the long-term proliferation of skin fibroblasts and that the stimulation proceeded in two stages, the first one 2 h and the second one 3 days post-irradiation. (orig.) With 4 figs., 2 tabs., 13 refs.

  6. Low-power laser irradiation did not stimulate breast cancer cells following ionizing radiation

    Science.gov (United States)

    Silva, C. R.; Camargo, C. F. M.; Cabral, F. V.; Ribeiro, M. S.

    2016-03-01

    Cancer has become a public health problem worldwide. Radiotherapy may be a treatment to a number of types of cancer, frequently using gamma-radiation with sources such as 137Cs and 60Co, with varying doses, dose rates, and exposure times to obtain a better as a stimulant for cell proliferation and tissue healing process. However, its effects on cancer cells are not yet well elucidated. The purpose of this work was to evaluate the effects of the LPL on breast cancer cultures after ionizing radiation. The breast cancer-MDA-MB-231 cells were gamma irradiated by a 60Co source, with dose of 2.5 Gy. After 24h, cells were submitted to LPL irradiation using a red laser emitting at λ= 660 nm, with output power of 40 mW and exposure time of 30 s and 60 s. The plates were uniformly irradiated, with energy of 1.2 J and 2.4 J, respectively. Cell viability was analyzed using the exclusion method with trypan blue. Our results show that breast cancer cells submitted to LPL after ionizing radiation remained 95 % viable. No statistically significant differences were observed between laser and control untreated cells, (P > 0.05). These findings suggest that LPL did not influenced cancer cells viability.

  7. Low power continuous wave-laser seed irradiation effect on Moringa oleifera germination, seedling growth and biochemical attributes.

    Science.gov (United States)

    Urva; Shafique, Hina; Jamil, Yasir; Haq, Zia Ul; Mujahid, Tamveel; Khan, Aman Ullah; Iqbal, Munawar; Abbas, Mazhar

    2017-05-01

    Recently, laser application in agriculture has gained much attention since plant characteristics were improved significantly in response of pre-sowing seed treatment. Pre-sowing laser seed treatment effects on germination, seedling growth and mineral profile were studied in Moringa olifera. M. olifera healthy seeds were exposed to 25, 50, 75mJ low power continuous wave laser light and grown under greenhouse conditions. The seedling growth and biochemical attributes were evaluated from 10-day-old seedlings. The germination parameters (percentage, mean germination time), vigor index, seedling growth (root length, seedling length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight) enhanced considerably. The laser energy levels used for seed irradiation showed variable effects on germination, seedling growth and mineral profile. The mineral contents were recorded to be higher in seedling raised from laser treated seeds, which were higher in roots versus shoots and leaves. The effect of laser treatment on seedling fat, nitrogen and protein content was insignificant and at higher energy level both nitrogen and protein contents decreased versus control. Results revealed that M. olifera germination, seedling growth and mineral contents were enhanced and optimum laser energy level has more acceleratory effect since at three laser energy levels the responses were significantly different. Overall the laser energy levels effect on germination and seedling growth was found in following order; 75mJ>50mJ>25mJ, where as in case of fat, protein and nitrogen contents the trend was as; 25mJ>50mJ and 75mJ. However, this technique could possibly be used to improve the M. olifera germination, seedling growth, and minerals contents where germination is low due to unfavorable conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Low-power laser irradiation improves histomorphometrical parameters and bone matrix organization during tibia wound healing in rats.

    Science.gov (United States)

    Garavello-Freitas, I; Baranauskas, V; Joazeiro, P P; Padovani, C R; Dal Pai-Silva, M; da Cruz-Höfling, Maria Alice

    2003-01-01

    The influence of daily energy doses of 0.03, 0.3 and 0.9 J of He-Ne laser irradiation on the repair of surgically produced tibia damage was investigated in Wistar rats. Laser treatment was initiated 24 h after the trauma and continued daily for 7 or 14 days in two groups of nine rats (n=3 per laser dose and period). Two control groups (n=9 each) with injured tibiae were used. The course of healing was monitored using morphometrical analysis of the trabecular area. The organization of collagen fibers in the bone matrix and the histology of the tissue were evaluated using Picrosirius-polarization method and Masson's trichrome. After 7 days, there was a significant increase in the area of neoformed trabeculae in tibiae irradiated with 0.3 and 0.9 J compared to the controls. At a daily dose of 0.9 J (15 min of irradiation per day) the 7-day group showed a significant increase in trabecular bone growth compared to the 14-day group. However, the laser irradiation at the daily dose of 0.3 J produced no significant decrease in the trabecular area of the 14-day group compared to the 7-day group, but there was significant increase in the trabecular area of the 15-day controls compared to the 8-day controls. Irradiation increased the number of hypertrophic osteoclasts compared to non-irradiated injured tibiae (controls) on days 8 and 15. The Picrosirius-polarization method revealed bands of parallel collagen fibers (parallel-fibered bone) at the repair site of 14-day-irradiated tibiae, regardless of the dose. This organization improved when compared to 7-day-irradiated tibiae and control tibiae. These results show that low-level laser therapy stimulated the growth of the trabecular area and the concomitant invasion of osteoclasts during the first week, and hastened the organization of matrix collagen (parallel alignment of the fibers) in a second phase not seen in control, non-irradiated tibiae at the same period. The active osteoclasts that invaded the regenerating site were

  9. Histometric evaluation of the healing of the dental alveolus in rats after irradiation with a low-powered GaA1As laser

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Lamano-Carvalho, Tereza L.; Brentegani, Luis G.

    1999-05-01

    The aim of the present work was to evaluate histometrically the effect of the irradiation with semiconductor diode GaAlAs 790 nm low-powered laser in the chronology of alveolar repair of rats. Lasers of low intensity possesses an eminently analgesic, anti-inflammatory and bioestimulant effect, producing an increase of the local micro-circulation and in the speed of healing. Groups of five animals had their upper right incisors extracted under anesthesia and the mucous sutured; three groups received 1.5 J/cm2 of irradiation immediately after the extraction with laser for sweeping on the operated area. After that, the animals were sacrificed in the periods of 7, 14 and 21 days after the dental extraction. The material was decalcified and processed for inclusion in paraffin. Longitudinal sections of 7 micrometers in the alveolus were made and stained with HE. The histometric analysis was performed with the Merz grid, and 2000 points were counted in each cervical, middle and apical thirds of the alveolus, assessing the percentage of the bone tissue. The result shows that low-powered intensity laser produced acceleration in osseous formation (10%) in some periods.

  10. Benefits of low-power lasers on oral soft tissue

    Science.gov (United States)

    Eduardo, Carlos d. P.; Cecchini, Silvia C. M.; Cecchini, Renata C.

    1996-04-01

    The last five years have represented a great advance in relation to laser development. Countries like Japan, United States, French, England, Israel and others, have been working on the association of researches and clinical applications, in the field of laser. Low power lasers like He-Ne laser, emitting at 632,8 nm and Ga-As-Al laser, at 790 nm, have been detached acting not only as a coadjutant but some times as an specific treatment. Low power lasers provide non thermal effect at wavelengths believed to stimulate circulation and cellular activity. These lasers have been used to promote wound healing and reduce inflammation edema and pain. This work presents a five year clinical study with good results related to oral tissue healing. Oral cavity lesions, like herpes and aphthous ulcers were irradiated with Ga-Al- As laser. In both cases, an excellent result was obtained. The low power laser application decrease the painful sintomatology immediately and increase the reparation process of these lesions. An excellent result was obtained with application of low power laser in herpetic lesions associated with a secondary infection situated at the lip commissure covering the internal tissue of the mouth. The healing occurred after one week. An association of Ga-Al-As laser and Nd:YAG laser have been also proven to be good therapy for these kind of lesions. This association of low and high power laser has been done since 1992 and it seems to be a complement of the conventional therapies.

  11. Low power laser in Odonto-stomathology

    International Nuclear Information System (INIS)

    Valiente Zaldivar, Carolina

    2009-01-01

    The use of low power laser technology in our country, and mainly in Odonto-stomathology, have gad a constant evolution and development since the 80's, being significant the social repercution between professionals and patients, achieving and alternative of treatment, which is non painful, and the results, either analgesic, anti-inflammatory, and stimulating of the tissue regeneration. This work intends to show the therapeutic procedure, and the different clinical entities, treated with Cuban instruments, that contains red or infrared diode lasers. The experience, during more than 20 years of the use of this kind of low power lasers, with different radiation techniques, includes: laser therapy or their combination with acupuncture points, so-called Laser puncture, which makes this technology an alternative of treatment for several clinical entities in correspondence with alterations of the tissues of the tooth, the mucose, neuronal alterations, and so on, procedures that are generalized in more that 60 services of our country. (Author)

  12. Low-power-laser therapy used in tendon damage

    Science.gov (United States)

    Strupinska, Ewa

    1996-03-01

    The following paper covers evaluation of low-power laser therapy results in chronic Achilles tendon damage and external Epicondylalia (tennis elbow). Fifty patients with Achilles damage (18 women and 32 men, age average 30, 24 plus or minus 10, 39 years) and fifty patients having external Epicondyalgiae (31 women and 19 men, age average 44, 36 plus or minus 10, 88 years) have been examined. The patients were irradiated by semiconductor infrared laser wavelength 904 nm separately or together with helium-neon laser wavelength 632.8 nm. The results of therapy have been based on the patient's interviews and examinations of patients as well as on the Laitinen pain questionnaire. The results prove analgesic effects in usage of low- power laser radiation therapy can be obtained.

  13. Penile anesthesia in Post SSRI Sexual Dysfunction (PSSD) responds to low-power laser irradiation : A case study and hypothesis about the role of transient receptor potential (TRP) ion channels

    NARCIS (Netherlands)

    Waldinger, Marcel D.; van Coevorden, Ruben S.; Schweitzer, Dave H.; Georgiadis, Janniko

    2015-01-01

    Treatment of paroxetine-induced penile anesthesia in Post SSRI Sexual Dysfunction (PSSD) by Low-power Laser Irradiation (PLO is unknown in medical literature. The aim of the current article is to report partial efficacy of LPLI for paroxetine-induced persistent penile anesthesia. We report on a male

  14. Glycogen synthase kinase-3β facilitates cell apoptosis induced by high fluence low-power laser irradiation through acceleration of Bax translocation

    Science.gov (United States)

    Huang, Lei; Wu, Shengnan; Xing, Da

    2011-03-01

    Glycogen synthase kinase-3β (GSK-3β) is a critical activator of cell apoptosis induced by a diverse array of insults. However, the effects of GSK-3β on the human lung adenocarcinoma cell (ASTC-a-1) apoptosis induced by high fluence low-power laser irradiation (HF-LPLI) are not clear. Here, we showed that GSK-3β was constantly translocated from cytoplasm to nucleus and activated during HF-LPLI-induced cell apoptosis. In addition, we found that co-overexpression of YFP-GSK-3β and CFP-Bax in ASTC-a-1 cells accelerated both Bax translocations to mitochondria and cell apoptosis, compared to the cells expressed CFP-Bax only under HF-LPLI treatment, indicating that GSK-3β facilitated ASTC-a-1 cells apoptosis through acceleration mitochondrial translocation of Bax. Our results demonstrate that GSK-3β exerts some of its pro-apoptotic effects in ASTC-a-1 cells by regulating the mitochondrial localization of Bax, a key component of the intrinsic apoptotic cascade.

  15. Low power cw-laser signatures on human skin

    International Nuclear Information System (INIS)

    Lihachev, A; Lesinsh, J; Jakovels, D; Spigulis, J

    2011-01-01

    Impact of cw laser radiation on autofluorescence features of human skin is studied. Two methods of autofluorescence detection are applied: the spectral method with the use of a fibreoptic probe and spectrometer for determining the autofluorescence recovery kinetics at a fixed skin area of ∼12 mm 2 , and the multispectral visualisation method with the use of a multispectral imaging camera for visualising long-term autofluorescence changes in a skin area of ∼4 cm 2 . The autofluorescence recovery kinetics after preliminary laser irradiation is determined. Skin autofluorescence images with visible long-term changes - 'signatures' of low power laser treatment are acquired. (application of lasers and laser-optical methods in life sciences)

  16. [Low power laser biostimulation in the treatment of bronchial asthma].

    Science.gov (United States)

    Milojević, Momir; Kuruc, Vesna

    2003-01-01

    Modern concept of acupuncture is based on the fact there are designated locations on the surface of human body, which are related to integrative systems of an organism by means of sensory nerves, correlating and synchronizing organ functioning, depending on external and internal conditions, by means of nervous and neurohumoral regulation of metabolic and regenerative processes, including also mobilisation of immunological, protective and antistress reactions. Apart from standard needle acupuncture, other methods of stimulating acupuncture points are also applied. Due to invention of low power lasers, irradiation laser acupuncture has been introduced into routine medical practice, characterised by painless and aseptic technique and outstanding clinical results. The investigation was aimed at defining therapeutic effects of low power laser irradiation by stimulating acupuncture points or local treatment of asthma. A prospective analysis included 50 patients treated at the Institute of Pulmonary Diseases in Sremska Kamenica during 2000, 2001 and 2002. Together with conservative treatment of present disease, these patients were treated with laser stimulation of acupuncture points in duration of ten days. During treatment changes of functional respiratory parameters were recorded. Results were compared with those in the control group. The control group consisted of the same number of patients and differed from the examination group only by not using laser stimulation. Patients with bronchial asthma presented with significant improvement (p lower frequency and intensity of attacks. The mechanism of laser stimulation activity in treatment of bronchial asthma is explained in detail, correlating our results to those obtained by other authors. A ten-day course of low-power laser stimulation of acupuncture points in patients with bronchial asthma improves both the lung function and gas exchange parameters. Positive effects of laser treatment in patients with bronchial asthma

  17. Biophysical basis of low-power-laser effects

    Science.gov (United States)

    Karu, Tiina I.

    1996-06-01

    Biological responses of cells to visible and near IR (laser) radiation occur due to physical and/or chemical changes in photoacceptor molecules, components of respiratory chains (cyt a/a3 in mitochondria). As a result of the photoexcitation of electronic states, the following physical and/or chemical changes can occur: alteration of redox properties and acceleration of electron transfer, changes in biochemical activity due to local transient heating of chromophores, one-electron auto-oxidation and O2- production, and photodynamic action and 1O2 production. Different reaction channels can be activated to achieve the photobiological macroeffect. The primary physical and/or chemical changes induced by light in photoacceptor molecules are followed by a cascade of biochemical reactions in the cell that do not need further light activation and occur in the dark (photosignal transduction and amplification chains). These actions are connected with changes in cellular homeostasis parameters. The crucial step here is thought to be an alteration of the cellular redox state: a shift towards oxidation is associated with stimulation of cellular vitality, and a shift towards reduction is linked to inhibition. Cells with a lower than normal pH, where the redox state is shifted in the reduced direction, are considered to be more sensitive to the stimulative action of light than those with the respective parameters being optimal or near optimal. This circumstance explains the possible variations in observed magnitudes of low-power laser effects. Light action on the redox state of a cell via the respiratory chain also explains the diversity of low-power laser effects. Beside explaining many controversies in the field of low-power laser effects (i.e., the diversity of effects, the variable magnitude or absence of effects in certain studies), the proposed redox-regulation mechanism may be a fundamental explanation for some clinical effects of irradiation, for example the positive

  18. Low-power laser therapy for carpal tunnel syndrome: effective optical power

    Directory of Open Access Journals (Sweden)

    Yan Chen

    2016-01-01

    Full Text Available Low-power laser therapy has been used for the non-surgical treatment of mild to moderate carpal tunnel syndrome, although its efficacy has been a long-standing controversy. The laser parameters in low-power laser therapy are closely related to the laser effect on human tissue. To evaluate the efficacy of low-power laser therapy, laser parameters should be accurately measured and controlled, which has been ignored in previous clinical trials. Here, we report the measurement of the effective optical power of low-power laser therapy for carpal tunnel syndrome. By monitoring the backside reflection and scattering laser power from human skin at the wrist, the effective laser power can be inferred. Using clinical measurements from 30 cases, we found that the effective laser power differed significantly among cases, with the measured laser reflection coefficient ranging from 1.8% to 54%. The reflection coefficient for 36.7% of these 30 cases was in the range of 10–20%, but for 16.7% of cases, it was higher than 40%. Consequently, monitoring the effective optical power during laser irradiation is necessary for the laser therapy of carpal tunnel syndrome.

  19. Biomedical effects of low-power laser controlled by electroacupuncture

    Science.gov (United States)

    Kalenchits, Nadezhda I.; Nicolaenko, Andrej A.; Shpilevoj, Boris N.

    1997-12-01

    The methods and technical facilities of testing the biomedical effects caused by the influence of low-power laser radiation in the process of laser therapy are presented. Described studies have been conducted by means of the complex of fireware facilities consisting of the system of electroacupuncture diagnostics (EA) and a system of laser therapy on the basis of multichannel laser and magneto-laser devices. The task of laser therapy was concluded in undertaking acupuncture anaesthetization, achievement of antioedemic and dispersional actions, raising tone of musculus and nervous system, normalization of immunity factors under the control of system EA. The 82 percent to 95 percent agreement of the result of an electroacupuncture diagnostics with clinical diagnoses were achieved.

  20. Random Sequence for Optimal Low-Power Laser Generated Ultrasound

    Science.gov (United States)

    Vangi, D.; Virga, A.; Gulino, M. S.

    2017-08-01

    Low-power laser generated ultrasounds are lately gaining importance in the research world, thanks to the possibility of investigating a mechanical component structural integrity through a non-contact and Non-Destructive Testing (NDT) procedure. The ultrasounds are, however, very low in amplitude, making it necessary to use pre-processing and post-processing operations on the signals to detect them. The cross-correlation technique is used in this work, meaning that a random signal must be used as laser input. For this purpose, a highly random and simple-to-create code called T sequence, capable of enhancing the ultrasound detectability, is introduced (not previously available at the state of the art). Several important parameters which characterize the T sequence can influence the process: the number of pulses Npulses , the pulse duration δ and the distance between pulses dpulses . A Finite Element FE model of a 3 mm steel disk has been initially developed to analytically study the longitudinal ultrasound generation mechanism and the obtainable outputs. Later, experimental tests have shown that the T sequence is highly flexible for ultrasound detection purposes, making it optimal to use high Npulses and δ but low dpulses . In the end, apart from describing all phenomena that arise in the low-power laser generation process, the results of this study are also important for setting up an effective NDT procedure using this technology.

  1. Research on laser detonation pulse circuit with low-power based on super capacitor

    Science.gov (United States)

    Wang, Hao-yu; Hong, Jin; He, Aifeng; Jing, Bo; Cao, Chun-qiang; Ma, Yue; Chu, En-yi; Hu, Ya-dong

    2018-03-01

    According to the demand of laser initiating device miniaturization and low power consumption of weapon system, research on the low power pulse laser detonation circuit with super capacitor. Established a dynamic model of laser output based on super capacitance storage capacity, discharge voltage and programmable output pulse width. The output performance of the super capacitor under different energy storage capacity and discharge voltage is obtained by simulation. The experimental test system was set up, and the laser diode of low power pulsed laser detonation circuit was tested and the laser output waveform of laser diode in different energy storage capacity and discharge voltage was collected. Experiments show that low power pulse laser detonation based on super capacitor energy storage circuit discharge with high efficiency, good transient performance, for a low power consumption requirement, for laser detonation system and low power consumption and provide reference light miniaturization of engineering practice.

  2. Laser Cutting of Thick Diamond Films Using Low-Power Laser

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.J.; Baik, Y.J. [Korea Institute of Science and Technology, Seoul (Korea)

    2000-02-01

    Laser cutting of thick diamond films is studied rising a low-power(10 W) copper vapor laser. Due to the existence of the saturation depth in laser cutting, thick diamond films are not easily cut by low-power lasers. In this study, we have adopted a low thermal- conductivity underlayer of alumina and a heating stage (up to 500 deg. C in air) to prevent the laser energy from consuming-out and, in turn, enhance the cutting efficiency. Aspect ratio increases twice from 3.5 to 7 when the alumina underlayer used. Adopting a heating stage also increases aspect ratio and more than 10 is obtained at higher temperatures than 400 deg. C. These results show that thick diamond films can be cut, with low-power lasers, simply by modifying the thermal property of underlayer. (author). 13 refs., 5 figs.

  3. Effect of low-power density laser radiation on heatling of open skin wounds in rats

    Energy Technology Data Exchange (ETDEWEB)

    Kana, J.S.; Hutschenreiter, G.; Haina, D.; Waidelich, W.

    1981-03-01

    Researchers performed a study to determine whether laser radation of low-power density would affect the healing of open skin wounds in rats. The wounds were irradiated daily with a helium-neon laser and an argon laser at a constant power density of 45 mW/sq cm. The rate of wound closure was followed by photographing the wounds in a standardized way. The collagen hydroxyproline concentration in the scar tissue was determined on the 18th postoperative day. Helium-neon laser radiation had a statistically significant stimulating effect on collagen synthesis in the wound, with a maximum effect at an energy density of 4 joules/sq cm. The rate of wound closure was enhanced significantly between the third and 12th postoperative days. The argon laser exposure produced a significant increase in collagen concentration both in irradiated and nonirradiated contralateral wounds. However, an acceleration of the healing rate was not registered in this case. The wound contraction up to the fourth day of the experiment was inhibited under helium-neon and argon laser exposure to 20 joules/sq cm. The described effects were not specific for the laser light. There may be a wavelength-selective influence of coherent light on the metabolic and proliferation processes in wound healing, with the associated problem of the possible carcinogenic effects of laser radiation.

  4. Fluorescence lifetime spectroscopy: potential for in-vivo estimation of skin fluorophores changes after low power laser treatment

    Science.gov (United States)

    Ferulova, Inesa; Lihachev, Alexey; Spigulis, Janis

    2013-11-01

    The impact of visible cwlaser irradiation on skin autofluorescence lifetimes was investigated in spectral range from 450 nm to 600 nm. Skin optical provocations were performed during 1 min by 405 nm low power cw laser with power density up to 20 mW/cm2. Autofluorescence lifetimes were measured before and immediately after the optical provocation.

  5. Low-power laser effects in equine traumatology and postsurgically

    Science.gov (United States)

    Antikas, Theo G.

    1991-05-01

    The present field study on 800 cases of LPL treatments in situ using a preset `blind code' was designed to verify previously published field results; and to check whether a practicing equine vet, trainer, horse owner or rider may obtain beneficial therapeutic effects in traumatology and/or post-surgery, two of the most prevailing modalities in equine sportsmedicine. With the exception of chronic infected traumas, the positive/beneficial response to LPL treatment was verified in a range of 33.3% (infected) to 100% (non-infected, surgical) of the traumas under investigation. The administration of antibiotics, a modality compatible with LPL treatment in infected injuries, increased the beneficial effects of LPL irradiation to 66.7%. This fact indicates that laser irradiation should not be considered a replacement of common therapeutic routine but simply an efficient follow up or parallel treatment that may act synergistically to the benefit of an injured equine athlete. In the case of non-infected surgical trauma, LPL-treatment was additionally found to shorten the post-surgical `inactive' time period or `comeback time' (CBT), thus bringing the horse back into its sportive capacity considerably faster than without LPL irradiation, and at a statistically significant level (p < 0.001).

  6. Low-Power-Consumption Integrated PPM Laser Transmitter, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Conventional PPM laser transmitters, a CW laser followed by a modulator, are inherently inefficient since the data must be carved from the laser's steady output. 95%...

  7. Low-Power-Consumption Integrated PPM Laser Transmitter, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Conventional PPM laser transmitters, a CW laser followed by a modulator, are inherently inefficient since the data must be carved from the laser's steady output. 95%...

  8. A study of low power laser on the regenerative process of Girardia tigrina (Girard,1850) (Turbellaria; Tricladida; Dugesiidae).

    Science.gov (United States)

    Lopes, K A R; Campos Velho, N M R; Munin, E

    2009-05-01

    The mechanism of regeneration does not start to restore the wound until its corresponding epimorphic phase. A bioestimulation of tissues and cells by laser radiation depends on the wavelength, on the dose, and on the intensity of the light. The goal of this work was to verify the effect of the low power laser at 660 nm on the regenerative process of Girardia tigrina. The specimens were maintained in the laboratory under a temperature ranging from 19 degrees up to 24 degrees C for 21 days. The planarians were anesthetized by placing them on ice and then cut them with a scalpel. The three treatments were as following: animals individually irradiated with 14 sessions with 1 minute duration (treatment 1), 14 sessions with 3 minutes duration (treatment 2), and without irradiation (control). The planarians were amputated and divided in three study treatments: a control group (without radiation), and two other treatments: irradiated for 1 minute, and irradiated for 3 minutes. The animals were irradiated with diode laser (660 nm) with 3.3 +/- 0.3 mW of power, using 0.94 mW.mm-2 power density for each irradiation procedure. During the experiment, 14 irradiation sessions were undertaken. The specimens were fixed in Bouin, and stained with hematoxyline and eosin. From observation and histological analysis, it was possible to assess the effects of interaction between laser and tissue. The head fragment after 1 minute of irradiation presented a better organized tissue scheme, when compared with the other treatments. Aspects of the body fragments submitted to 3 minutes of light treatment were very similar to fragments that had not been injured. It can be concluded that there are changes in the quality of regeneration when treated with low power laser under the conditions mentioned above.

  9. Backreflectance from the blood plexus in the skin under the low-power laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Naumenko, E.K. [Institute of Physics National Academy of Sciences of Belarus, Nezavisimosti Avenue, 68, 220072 Minsk (Belarus); Korolevich, A.N. [Institute of Physics National Academy of Sciences of Belarus, Nezavisimosti Avenue, 68, 220072 Minsk (Belarus) and Physics Department, Minho University, Campus Gualtar, 4709 Braga (Portugal)]. E-mail: akaralevich@fisica.uminho.pt; Dubina, N.S. [GP ' MTZ Medservice' , Stahanovskaia Street, 10A, 220009 Minsk (Belarus); Vecherinsky, S.I. [GP ' MTZ Medservice' , Stahanovskaia Street, 10A, 220009 Minsk (Belarus); Belsley, M. [Physics Department, Minho University, Campus Gualtar, 4709 Braga (Portugal)

    2007-07-15

    The intensity of light backscattered when low-power laser radiation is incident on the skin is investigated in vivo. The exposure of blood to low-power laser light in the absorption range of haemoglobin leads to an increased intensity of the backscattered light. The theoretical calculation using the existing optical model of erythrocyte aggregation suggests that the fragmentation of erythrocyte aggregates is the most probable mechanism leading to the enhanced backscattering.

  10. Low Power Consumption Lasers for Miniature Optical Spectrometers for Trace Gas Analysis

    Science.gov (United States)

    Forouhar, S.; Frez, C.; Franz, K. J.; Ksendzov, A.; Qiu, Y.; Soibel, K. A.; Chen, J.; Hosoda, T.; Kipshidze, G.; Shterengas, L.; hide

    2011-01-01

    The air quality of any manned spacecraft needs to be continuously monitored in order to safeguard the health of the crew. Air quality monitoring grows in importance as mission duration increases. Due to the small size, low power draw, and performance reliability, semiconductor laser-based instruments are viable candidates for this purpose. Achieving a minimum instrument size requires lasers with emission wavelength coinciding with the absorption of the fundamental absorption lines of the target gases, which are mostly in the 3.0-5.0 micron wavelength range. In this paper we report on our progress developing high wall plug efficiency type-I quantum-well GaSb-based diode lasers operating at room temperatures in the spectral region near 3.0-3.5 micron and quantum cascade (QC) lasers in the 4.0-5.0 micron range. These lasers will enable the development of miniature, low-power laser spectrometers for environmental monitoring of the spacecraft.

  11. Effect of Low-power Laser on Treatment of Orofacial Pain

    Directory of Open Access Journals (Sweden)

    Hamid Reza Khalighi

    2010-09-01

    Full Text Available Low-power lasers are a group of lasers with a power less than 250 mW and unlike high-power lasers they have no effect on tissue temperature; they produce light-dependent chemical reactions in tissues. These lasers have analgesic features with their ability to trigger reactions that reduce pain and inflammatory mediators. Low-power lasers can also be used instead of needles in acupuncture to decrease pain. Due to these features they have been used in the treatment of orofacial pain, including tooth hypersensitivity, post-operative flare-ups, mucositis, facial myalgia, temporomandibular joint disorders and neuralgia. In this article we review the effects of low-power lasers and their success rate in different studies. As the name implies (LASER: Light Amplification by the Stimulated Emission of Radiation, laser amplifies light by stimulated and excited radiation; in other words, it is amplification of excited light emission. Such radiation usually has some characteristic features, including mono-chromaticity, coherency, high intensity and polarity. There are various classifications for lasers based on their active material (solid, fluid and gas, wavelength, emission type and power.

  12. Low-power photolytically pumped lasers: Final technical report

    International Nuclear Information System (INIS)

    Messing, I.; Lorents, D.C.; Eckstrom, D.J.

    1987-08-01

    We have carried out an extensive series of measurements of the time-resolved Xe 2 * emission spectra following optical pumping by a short-pulse F 2 laser at 157.6 nm. Most measurements were performed using a gated Optical Multichannel Analyzer detector; we also made measurements using a scanning monochromator fitted with a photomultiplier and using a boxcar integrator for time resolution. The two sets of results agree well and show that both the singlet and triplet emission bands are broader than expected and have center wavelengths closer together than expected. Measurements were performed both at room temperature and at elevated (140 0 C) and reduced (-27 0 C) temperatures. The broad bandwidth of the individual spectral bands was unexpected and conflicted with a previous spectral measurement using optical pumping by the Xe* resonance line from a microwave discharge lamp. Therefore, we also performed a series of spectral measurements using this type of optical pumping. We achieved good agreement with some previous results in the literature, but not with the result in question. We conclude that the present results are reliable. The results presented in this report provide the first definitive measurement of the individual excimer emissions from each of the Xe 2 (0/sub u/ + ) and Xe 2 (1/sub u/) states. From these measurements and the known ground state potential, we derived a 1/sub u/ potential that reproduces the emission band very well. However, the 1/sub u/ potential is in substantial disagreement with the recent 1/sub u/ potential derived by the Toronto group. 13 refs., 32 figs., 3 tabs

  13. Disturbance of visual functions as a result of temporary blinding from low power lasers

    Science.gov (United States)

    Reidenbach, Hans-Dieter

    2010-04-01

    Although it is well-known that dazzle, flash-blindness and afterimages may be caused by bright optical radiation, only sparse quantitative data are available with regard to the effects arising from low power laser products. Indirect effects like temporary blinding might result in serious incidents or even accidents due to the alteration of visual functions like visual acuity, contrast sensitivity and color discrimination. In order to determine the degree and duration of impairment resulting from dazzle, flash-blindness and afterimages, caused by a laser beam, an investigation has been performed with the goal to improve the current knowledge as far as especially the visual acuity recovery duration is concerned. Two different test set-ups were designed and applied in order to determine the afterimage duration and the recovery time for visual acuity after temporary blinding from a laser, respectively. In order to get the desired information a helium-neon laser was mounted on a movable assembly where the respective beam position and direction could be set up on a semicircle. In addition the mount could be inclined in a vertical plane in order to increase the variability of feasible settings. The power was adjusted in several steps in order to investigate the respective dependence of the afterimage. The investigations were relatively time consuming, since re-adaptation of about half an hour was necessary after every exposure in order not to falsify the results. The trials have been done with several volunteers in the laboratory. After the experimental mapping of the local afterimage duration for the various sites on the retina the foveal afterimage duration taf,fv produced by a red laser beam was determined. The investigations have shown a strong dependence on the angle between the line of sight and the beam direction. Besides a maximum of 300 s the dose relationship taf,fv/s ~ 50.6•ln[(P•texp)/μJ] - 13.4 for laser output powers P between 10 μW and 30 μW with

  14. A study on excavation of rock mass by lasers. Researching the possibility of utilizing low-power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Fumio [Taisei Corporation, Technology Research Center, Yokohama, Kanagawa (Japan)

    2000-03-01

    The object of this research is to develop the techniques of rock-mass excavation by laser irradiation. This rock-mass excavation technique by lasers has a characteristic of extremely little effect to the surroundings of an excavation site no matter how the target rock mass is with regard to geological aspects and given physical property. Moreover, it could be utilized in excavation of waste dump facilities, which need to be re-buried, and applied to excavation of long piles and tunnels, which are drilled through different kinds of strata, and to improvement of rock mass and ground. Lasers have a characteristic of concentrating the energy into a limited point and not only discontinue or cut a large area with a small output like sharp scissors but also block up the cracks deep inside the rock mass by fusing vitrification for its improvement. It leads to restrain the loss of energy, minimization of the effected environment, effective utilization of resources and energy, environmental restoration, and improvement of the working environment. In the field of nuclear fuel, which includes excavating dump pits, dismantling a furnace, and taking appropriate steps of mine remains, excavating, cutting, and fusing could be required to do within a limited space of rock mass or concrete. Up to the present, those things have been done mainly by large machines, but it is too scarce in possibility for them to improve their large size, heavy weight, difficulty in unmanned operation, limited shapes of cutting, and stabilization of waste. In this research the concrete system images have been examined, doing the fundamental researches about higher-power lasers, smaller sizing, transmitting by fibers to find our the breakthrough to realization of laser excavation, This year, as the summary of examining the laser excavation techniques, utilizing a low-power laser, which is thought to be highly effective in rock-mass improvement, will be examined, considering application of the technique

  15. Study of a low power dissipation, miniature laser-pumped rubidium frequency standard

    Institute of Scientific and Technical Information of China (English)

    Liu Guo-Bin; Zhao Feng; Gu Si-Hong

    2009-01-01

    This paper studies a miniature low power consumption laser-pumped atom vapour cell clock scheme. Pumping 87Rb with a vertical cavity surface emitting laser diode pump and locking the laser frequency on a Doppler-broadened spectral line,it records a 5×10-11τ-1/2 (τ<500 s) frequency stability with a table-top system in a primary experiment.The study reveals that the evaluated scheme is at the level of 2.7 watts power consumption,90 cm3 volume and 10-12τ- 1/2 short-term frequency stability.

  16. Low power laser generated ultrasound: Signal processing for time domain data acquisition

    International Nuclear Information System (INIS)

    Cleary, A; Thursby, G; McKee, C; Armstrong, I; Culshaw, B; Veres, I; Pierce, S G

    2011-01-01

    The use of low power modulated laser diode systems has previously been established as a suitable method for non-destructive laser generation of ultrasound. Using a quasi-continuous optical excitation amplified by an erbium-doped fibre amplifier (EDFA) allows flexible generation of ultrasonic waves, offering control of further parameters such as the frequency content or signal shape. In addition, pseudo-random binary sequences (PRBS) can be used to improve the detected impulse response. Here we compare two sequences, the m-sequence and the Golay code, and discuss the advantages and practical limits of their application with laser diode based optical excitation of ultrasound.

  17. Low-power laser use in the treatment of alopecia and crural ulcers

    Science.gov (United States)

    Ciuchita, Tavi; Usurelu, Mircea; Antipa, Ciprian; Vlaiculescu, Mihaela; Ionescu, Elena

    1998-07-01

    The authors tried to verify the efficacy of Low Power Laser (LPL) in scalp alopecia and crural ulcers of different causes. Laser used was (red diode, continuous emission, 8 mW power, wave length 670 nm spot size about 5 mm diameter on some points 1 - 2 minutes per point. We also use as control classical therapy. Before, during and after treatment, histological samples were done for alopecia. For laser groups (alopecia and ulcers) the results were rather superior and in a three or twice time shorter than control group. We conclude that LPL therapy is a very useful complementary method for the treatment of scalp alopecia and crural ulcers.

  18. Investigations on the potential of a low power diode pumped Er:YAG laser system for oral surgery

    Science.gov (United States)

    Stock, Karl; Wurm, Holger; Hausladen, Florian; Wagner, Sophia; Hibst, Raimund

    2015-02-01

    Flash lamp pumped Er:YAG-lasers are used in clinical practice for dental applications successfully. As an alternative, several diode pumped Er:YAG laser systems (Pantec Engineering AG) become available, with mean laser power of 2W, 15W, and 30W. The aim of the presented study is to investigate the potential of the 2W Er:YAG laser system for oral surgery. At first an appropriate experimental set-up was realized with a beam delivery and both, a focusing unit for non-contact tissue cutting and a fiber tip for tissue cutting in contact mode. In order to produce reproducible cuts, the samples (porcine gingiva) were moved by a computer controlled translation stage. On the fresh samples cutting depth and quality were determined by light microscopy. Afterwards histological sections were prepared and microscopically analyzed regarding cutting depth and thermal damage zone. The experiments show that low laser power ≤ 2W is sufficient to perform efficient oral soft tissue cutting with cut depth up to 2mm (sample movement 2mm/s). The width of the thermal damage zone can be controlled by the irradiation parameters within a range of about 50μm to 110μm. In general, thermal injury is more pronounced using fiber tips in contact mode compared to the focused laser beam. In conclusion the results reveal that even the low power diode pumped Er:YAG laser is an appropriate tool for oral surgery.

  19. Low power infrared laser modifies the morphology of lung affected with acute injury induced by sepsis

    Science.gov (United States)

    Sergio, L. P. S.; Trajano, L. A. S. N.; Thomé, A. M. C.; Mencalha, A. L.; Paoli, F.; Fonseca, A. S.

    2018-06-01

    Acute lung injury (ALI) is a potentially fatal disease characterized by uncontrolled hyperinflammatory responses in the lungs as a consequence of sepsis. ALI is divided into two sequential and time-dependent phases, exudative and fibroproliferative phases, with increased permeability of the alveolar barrier, causing edema and inflammation. However, there are no specific treatments for ALI. Low-power lasers have been successfully used in the resolution of acute inflammatory processes. The aim of this study was to evaluate the effects of low-power infrared laser exposure on alveolus and interalveolar septa of Wistar rats affected by ALI-induced by sepsis. Laser fluences, power, and the emission mode were those used in clinical protocols for the treatment of acute inflammation. Adult male Wistar rats were randomized into six groups: control, 10 J cm‑2, 20 J cm‑2, ALI, ALI  +  10 J cm‑2, and ALI  +  20 J cm‑2. ALI was induced by intraperitoneal Escherichia coli lipopolysaccharide (LPS). Lungs were removed and processed for hematoxylin–eosin staining. Morphological alterations induced by LPS in lung tissue were quantified by morphometry with a 32-point cyclic arcs test system in Stepanizer. Data showed that exposure to low-power infrared laser in both fluences reduced the thickening of interalveolar septa in lungs affected by ALI, increasing the alveolar space; however, inflammatory infiltrate was still observed. Our research showed that exposure to low-power infrared laser improves the lung parenchyma in Wistar rats affected by ALI, which could be an alternative approach for treatment of inflammatory lung injuries.

  20. Low Power Consumption Laser for Next Generation Miniature Optical Spectrometers for Trace Gas Analysis

    Science.gov (United States)

    Forouhar, S.; Frez, C.; Franz, K. J.; Ksendzov, A.; Qiu, Y.; Soibel, K. A.; Chen, J.; Hosoda, T.; Kipshidze, G.; Shterengas, L.; hide

    2011-01-01

    The air quality of any manned spacecraft needs to be continuously monitored in order to safeguard the health of the crew. Air quality monitoring grows in importance as mission duration increases. Due to the small size, low power draw, and performance reliability, semiconductor laser-based instruments are viable candidates for this purpose. Achieving a minimum instrument size requires lasers with emission wavelength coinciding with the absorption of the fundamental absorption lines of the target gases, which are mostly in the 3.0-5.0 mu m wavelength range. In this paper we report on our progress developing high wall plug efficiency type-I quantum-well GaSb-based diode lasers operating at room temperatures in the spectral region near 3.0-3.5 mu m and quantum cascade (QC) lasers in the 4.0-5.0 mu m range. These lasers will enable the development of miniature, low-power laser spectrometers for environmental monitoring of the spacecraft

  1. High-resolution multiphoton microscopy with a low-power continuous wave laser pump.

    Science.gov (United States)

    Chen, Xiang-Dong; Li, Shen; Du, Bo; Dong, Yang; Wang, Ze-Hao; Guo, Guang-Can; Sun, Fang-Wen

    2018-02-15

    Multiphoton microscopy (MPM) has been widely used for three-dimensional biological imaging. Here, based on the photon-induced charge state conversion process, we demonstrated a low-power high-resolution MPM with a nitrogen vacancy (NV) center in diamond. Continuous wave green and orange lasers were used to pump and detect the two-photon charge state conversion, respectively. The power of the laser for multiphoton excitation was 40 μW. Both the axial and lateral resolutions were improved approximately 1.5 times compared with confocal microscopy. The results can be used to improve the resolution of the NV center-based quantum sensing and biological imaging.

  2. Influence on living body by radiant rays produced in low power reactor. Irradiation of rabbit inside of low power reactor (UTR-KINKI)

    Energy Technology Data Exchange (ETDEWEB)

    Ogura, Isao; Nakamura, Katsuichi; Usuyama, Hideo; Usui, Akinori; Hosomi, Takashi; Yoshimura, Yoshinao; Nakai, Takahide; Egashira, Masamichi

    1984-12-01

    There is possibility of a risk that a living body is irradiated by those for slightly indifference to radiant rays, radiation source or devices of low level dose or dose rate. Accordingly, a low power reactor (UTR-KINKI) was utilized for a observation of influence by radiation of low level dose or dose rate, the rabbits were irradiated in it at output 1 w. The large influence was not expected for the low level dose rate of 1.313 Rad/hr even if they were irradiated for the several hours, but in a part of blood components a slight change was recognized. The change of M pattern in white blood corpuscle number was indicated likewise as irradiation of 500R X-ray, reported from Jacobson and others, by irradiation to about 13 Rads. In addition, lymphocyte number was increased considerably in an early stage. This fact will be useful for a recovery of an injury as mentioned by Lucky. The rabbits of alloxan diabetes mellitus and hepatitis were irradiated in the same way as above, but they scarcely showed the alterations. However, numerous rabbits can't be used in this experiment for the equipment and others. (author).

  3. Low power laser effects in cancer cells and fibroblasts submitted the ionizing radiation

    International Nuclear Information System (INIS)

    Silva, Camila Ramos

    2015-01-01

    Cancer is considered a public health problem worldwide. According to Brazil's the National Cancer Institute (INCA), 576,000 new cases of cancer were estimated for 2015 in Brazil, representing the second leading cause of death. Radiotherapy may be a treatment to several of types of cancer, frequently using ionizing radiation to eradicate or prevent the proliferation of tumor cells. This treatment, however, can lead to death of non-tumor cells around in irradiated tissue. Given this, adjuvant therapies that can minimize the side effects of ionizing radiation are of extremely importance. In this context, low power laser (LPL) may be an alternative to modulate the response of healthy cells to ionizing radiation. In this study, cells of human gingival fibroblasts (FMM1) and breast cancer (MDAMB- 231) were exposed to gamma radiation at doses of 2.5 and 10 Gy. After twenty-four hours, cell were irradiated with LPL ( λ= 660 nm, 40 mW and total area of 0.04 cm²) with energy densities of 30, 60, 90, 120 and 150 J/cm². The cell viability was measured during four days, using the trypan blue technique. The influence of LPL on the cell cycle and on expression of the nuclear antigen of cellular proliferation (PCNA) was evaluated by flow cytometry. The expression of β-Galactosidase was the chosen method to assess cell senescence. Considering our adopted parameters, and focusing on the non-tumor cells, we have observed an increase in: 1) cell viability; 2) cell population in phases S and G 2 /M cell cycle; 3) PCNA expression with decrease in senescence. No alterations were observed in the cell viability, with greater population in phases S and G 2 /M cell cycle, while the number of senescent cells and the expression of PCNA were decreased. Therefore, we have concluded that the LPL promoted effects on both cell lineages, with increased cell viability on FMM1 cells, whether cancer cells maintained a decreased proliferation. (author)

  4. Characterisation of beams of low power infrared lasers for medical uses

    International Nuclear Information System (INIS)

    Welch, M.; Ramsay, D.

    1996-01-01

    Full text: The initial aim of this work was to investigate the power stability, both temporally and spatially, of the beams of low power infrared diode lasers of the type used by physiotherapists and vascular surgeons. Most of the lasers in this category are small, handheld devices, often with on/off switches which are manually held on while the laser is running. Two of those tested were larger, on stands, and could be set to run for a nominated time. Measurements made by one of us prior to the project had indicated that the power output of at least one of the lasers in use at Westmead Hospital was varying significantly over the treatment time. It is not at present known whether or not uniformity of power output is a significant factor in low power laser therapy, which has been shown to have beneficial effects for conditions ranging from torn muscles and arthritis to birth marks. Dramatic improvement in the healing of skin ulcers and wounds such as amputation scars has also been recorded. Equipment was chosen and a set of techniques developed for analysing the laser beams (some of which operated in continuous wave mode, some in pulsed mode, and some in both) with respect to: power output over time; power distribution within the beam, ie., beam profile; beam divergence; and pulse repetition frequency and pulse shape, if applicable. The fact that some of the lasers were continuous wave, some were pulsed and that some had very high pulse repetition frequencies placed restrictions on the type of power meter which could be used. Eventually a surface absorbing thermal power meter, responsive over a wide range of wavelengths, was chosen for temporal power measurements. Pulse repetition rates and pulse shapes were shown on a CRO; and spatial power distribution, beam shape, power distribution and divergence were recorded via a CCD camera and Spiricon laser beam analyser. 3D printouts from the Spiricon were made showing distribution of beam power. Nine lasers were analysed

  5. Functional approach to the assessment of ocular hazards of low-power lasers

    Energy Technology Data Exchange (ETDEWEB)

    Raybourn, M.S.; Kong, R.L.

    1984-01-01

    An electrophysiological bioassay system has been developed to provide safety-related information about the functional consequences of non-thermal laser irradiation of the vertebrate retina. This in vitro preparation allows precise dosimetry at the retinal surface, provides for an intra-retinal control, comparing lased vs non-lased tissue, and permits quantitative assessment of the biophysical mechanisms of laser-induced retinal dysfunction.

  6. Low Power Consumption Lasers for Next Generation Miniature Optical Spectrometers for Major Constituent and Trace Gas Analysis

    Science.gov (United States)

    Forouhar, Siamak; Soibel, Alexander; Frez, Clifford; Qiu, Yueming; Chen, J.; Hosoda, T.; Kipshidze, G.; Shterengas, L.; Tsvid, G.; Belenky, G.; hide

    2010-01-01

    The air quality of any manned spacecraft needs to be continuously monitored in order to safeguard the health of the crew. Air quality monitoring grows in importance as mission duration increases. Due to the small size, low power draw, and performance reliability, semiconductor laser-based instruments are viable candidates for this purpose. The minimum instrument size requires lasers with emission wavelength coinciding with the absorption of the fundamental frequency of the target gases which are mostly in the 3.0-5.0 micrometers wavelength range. In this paper we report on our progress developing high wall plug efficiency type-I quantum-well GaSb-based diode lasers operating at room temperatures in the spectral region near 3.0-3.5 micrometers and quantum cascade (QC) lasers in the 4.0-5.0 micrometers range. These lasers will enable the development of miniature, low-power laser spectrometers for environmental monitoring of the spacecraft.

  7. Efeitos da terapia fotodinâmica e de uma única aplicação de laser de baixa potência em bactérias in vitro Effects of photodynamic therapy and of a sole low-power laser irradiation on bacteria in vitro

    Directory of Open Access Journals (Sweden)

    Rogério Gubert Benvindo

    2008-01-01

    were prepared, 16 with Pseudomonas aeruginosa and 16 with Staphilococcus aureus, and divided into eight subgroups each: three subgroups treated with 2 J/cm², 4 J/cm², and 6 J/cm² laser; three subgroups treated with 2 J/cm², 4 J/cm², and 6 J/cm² PDT; one treated solely with photosensitiser; and a non-treated (control subgroup. Laser and PDT groups were irradiated once and incubated for 24 hours; the other two subgroups underwent no irradiation. Cultures were visually analysed in search of inhibition haloes. In all subgroups, for both bacteria, no inhibition or growing signs could be detected. Hence neither low-level laser or PDT (InGaP, 670 nm produced any bactericidal or bacteriostatic effect, nor any biostimulation effect, onto analysed bacteria.

  8. The effectiveness of the low-power laser and kinesiotaping in the treatment of carpal tunnel syndrome, a pilot study.

    Science.gov (United States)

    Güner, A; Altan, L; Kasapoğlu Aksoy, M

    2018-05-01

    In mild and moderate cases of carpal tunnel syndrome (CTS), the conservative approach is suggested. The purpose of this study is to assess and compare the effect of low-power laser versus the combination of low-power laser and kinesiotaping on pain, muscle strength, functionality, and electrophysiologic parameters in the patients with CTS. The study was planned as single-blind, prospective, randomized control. 64 hands diagnosed with CTS were included in the study. The patients were randomly divided into three groups by closed envelope method. Low-power laser therapy was applied to Group 1 (21 hands), kinesiotaping and low-power laser therapy in group 2 (22 hands), sham laser therapy in Group 3 (21 hands). All patients were assessed by visual numeric pain scale (VNS), hand grip strength (HGS), finger pinch strength (FPS), the Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ), before treatment, after treatment (3rd week), and after (12th week) 3 months the treatment with the same physician. Motor and sensory nerve conduction studies were performed with electroneuromyography (ENMG) before the treatment (0th week) and at the end of the 12th week. Comparison of the group 1 with the group 3 showed significantly better improvement in the former in VNS, BCTSQ at 3rd week and 12th week compared to 0th week, and in FPS and HGS at 3rd week. Comparison of the group 2 with the group 3 showed significantly better improvement in the former VNS, BCTSQ, FPS and HGS at 3rd and 12th week compared to 0th week. When Group 1 and Group 2 were compared there was no statistically significant difference in any parameters in the 3rd week, but there was a statistically significant difference in favor of group 2 in FPS and HGS parameters at the 12th week. We have found that the kinesiotaping method applied with low-power laser treatment does not provide any additional benefit to the low-power laser treatment in the short term, however, in the long term, the increase in the HGS and FPS has

  9. Comparison of the effect of low-power laser with therapeutic ultrasound on the treatment of rotator cuff tendonitis

    Directory of Open Access Journals (Sweden)

    asghar Akbari

    2009-01-01

    Full Text Available Akbari A1 1. Assistant Professor, Department of Physiotherapy, Faculty of Medicine, Zahedan University of Medical Sciences Abstract Background: Shoulder pain is the third most prevalent cause of musculoskeletal disorder after low back and cervical pains. Most of the shoulder symptoms are attributed to the rotator cuff. The objective of this study was to compare the effects of low-power laser therapy with ultrasound therapy on the patients with rotator cuff tendonitis. Materials and methods: This clinical trial was performed in Zahedan university of medical sciences in 2006. Thirty patients with rotator cuff tendonitis were randomly assigned to either a low-power laser therapy group (15 patients or an ultrasound therapy group (15 patients. Strength (kg of shoulder abductor, and internal and external rotator muscles, as well as range (degree of shoulder abduction, and internal and external rotation were measured before and after intervention using hand-held dynamometer and goniometer respectively. The pain was evaluated using the visual analogue scale. In the laser group, a low-level Ga-As laser was applied with a 100 mw point probe (average power, wave length of 905 nm, pulse duration of 200 ns, 6 J/cm2 dosage, 5 KHz frequency, and lasting 3 minutes. The ultrasound treatment was applied with a power of 1 W/cm2, a frequency of 1 MHz, pulse mode of 1:4, and lasting 10 minutes on each occasion. The treatment was carried out 3 times weekly for 10 days. The data were analyzed using independent sample t-test and paired t-test. Results: The pain in the laser group was significantly decreased from 6.06±1.6 to 5±1.3 in abduction, from 5.3±1.5 to 4.7±1.3 in internal rotation, and from 5.06±1.4 to 4.3±1.44 in external rotation (p0.05. A significant improvement after treatment was observed in the laser group in measures of shoulder abductor, internal rotator and external rotator muscles strength compared to those of the ultrasound therapy group (p<0

  10. Non-Contact Thermal Properties Measurement with Low-Power Laser and IR Camera System

    Science.gov (United States)

    Hudson, Troy L.; Hecht, Michael H.

    2011-01-01

    As shown by the Phoenix Mars Lander's Thermal and Electrical Conductivity Probe (TECP), contact measurements of thermal conductivity and diffusivity (using a modified flux-plate or line-source heat-pulse method) are constrained by a number of factors. Robotic resources must be used to place the probe, making them unavailable for other operations for the duration of the measurement. The range of placement is also limited by mobility, particularly in the case of a lander. Placement is also subject to irregularities in contact quality, resulting in non-repeatable heat transfer to the material under test. Most important from a scientific perspective, the varieties of materials which can be measured are limited to unconsolidated or weakly-cohesive regolith materials, rocks, and ices being too hard for nominal insertion strengths. Accurately measuring thermal properties in the laboratory requires significant experimental finesse, involving sample preparation, controlled and repeatable procedures, and, practically, instrumentation much more voluminous than the sample being tested (heater plates, insulation, temperature sensors). Remote measurements (infrared images from orbiting spacecraft) can reveal composite properties like thermal inertia, but suffer both from a large footprint (low spatial resolution) and convolution of the thermal properties of a potentially layered medium. In situ measurement techniques (the Phoenix TECP is the only robotic measurement of thermal properties to date) suffer from problems of placement range, placement quality, occupation of robotic resources, and the ability to only measure materials of low mechanical strength. A spacecraft needs the ability to perform a non-contact thermal properties measurement in situ. Essential components include low power consumption, leveraging of existing or highly-developed flight technologies, and mechanical simplicity. This new in situ method, by virtue of its being non-contact, bypasses all of these

  11. Design of compact dispersion interferometer with a high efficiency nonlinear crystal and a low power CO2 laser

    Science.gov (United States)

    Akiyama, T.; Yoshimura, S.; Tomita, K.; Shirai, N.; Murakami, T.; Urabe, K.

    2017-12-01

    When the electron density of a plasma generated in high pressure environment is measured by a conventional interferometer, the phase shifts due to changes of the neutral gas density cause significant measurement errors. A dispersion interferometer, which measures the phase shift that arises from dispersion of medium between the fundamental and the second harmonic wavelengths of laser light, can suppress the measured phase shift due to the variations of neutral gas density. In recent years, the CO2 laser dispersion interferometer has been applied to the atmospheric pressure plasmas and its feasibility has been demonstrated. By combining a low power laser and a high efficiency nonlinear crystal for the second harmonic component generation, a compact dispersion interferometer can be designed. The optical design and preliminary experiments are conducted.

  12. Efeitos bioestimulantes do laser de baixa potência no processo de reparo Biostimulation effects of low-power laser in the repair process

    Directory of Open Access Journals (Sweden)

    Ruthinéia Diógenes Alves Uchôa Lins

    2010-12-01

    Full Text Available Os lasers de baixa potência promovem efeitos biológicos benéficos, de caráter analgésico, antiinflamatório e cicatrizante, por meio de um fenômeno de bioestimulação. A radiação emitida pelo laser terapêutico afeta os processos metabólicos das células-alvo, produzindo efeitos bioestimulantes que resultam na ocorrência de eventos celulares e vasculares, os quais parecem interferir diretamente no processo de reparo. Este trabalho visa estudar o fenômeno da bioestimulação e destacar os principais efeitos bioestimulantes do laser de baixa potência na reparação tecidual.The wound healing process has always been an excellent subject for researchers. The use of low-power laser on wounds during the postoperative phase has increased the speed of the healing process. It has been implied that low power radiation affects cellular metabolic processes and promotes beneficial biological effects (analgesic, anti-inflammatory, and healing. Laser biostimulation appears to influence the behavior of the repair process. This paper aims at reviewing the most interesting aspects of the use of low-power laser in the tissue-repair process.

  13. Enhancement of low power CO2 laser cutting process for injection molded polycarbonate

    Science.gov (United States)

    Moradi, Mahmoud; Mehrabi, Omid; Azdast, Taher; Benyounis, Khaled Y.

    2017-11-01

    Laser cutting technology is a non-contact process that typically is used for industrial manufacturing applications. Laser cut quality is strongly influenced by the cutting processing parameters. In this research, CO2 laser cutting specifications have been investigated by using design of experiments (DOE) with considering laser cutting speed, laser power and focal plane position as process input parameters and kerf geometry dimensions (i.e. top and bottom kerf width, ratio of the upper kerf to lower kerf, upper heat affected zone (HAZ)) and surface roughness of the kerf wall as process output responses. A 60 Watts CO2 laser cutting machine is used for cutting the injection molded samples of polycarbonate sheet with the thickness of 3.2 mm. Results reveal that by decreasing the laser focal plane position and laser power, the bottom kerf width will be decreased. Also the bottom kerf width decreases by increasing the cutting speed. As a general result, locating the laser spot point in the depth of the workpiece the laser cutting quality increases. Minimum value of the responses (top kerf, heat affected zone, ratio of the upper kerf to lower kerf, and surface roughness) are considered as optimization criteria. Validating the theoretical results using the experimental tests is carried out in order to analyze the results obtained via software.

  14. Low-power colorless all-optical 2R regeneration of 25 Gb/s NRZ signals using a standard DFB laser

    DEFF Research Database (Denmark)

    Huybrechts, Koen; Peucheret, Christophe; Seoane, Jorge

    2010-01-01

    We demonstrate the first all-optical 2R regeneration of 25 Gbit/s NRZ data based on hysteresis in a DFB laser. The scheme results in BER improvement, exhibits low power consumption and is effective after fiber transmission.......We demonstrate the first all-optical 2R regeneration of 25 Gbit/s NRZ data based on hysteresis in a DFB laser. The scheme results in BER improvement, exhibits low power consumption and is effective after fiber transmission....

  15. A randomized placebo-blind study of the effect of low power laser on pain caused by irreversible pulpitis.

    Science.gov (United States)

    Ramalho, Karen Müller; de Souza, Lárissa Marcondes Paladini; Tortamano, Isabel Peixoto; Adde, Carlos Alberto; Rocha, Rodney Garcia; de Paula Eduardo, Carlos

    2016-12-01

    This randomized placebo-blind study aimed to evaluate the effect of laser phototherapy (LPT) on pain caused by symptomatic irreversible pulpitis (SIP). Sixty patients diagnosed with SIP were randomly assigned to treatment groups (n = 15): G1 (control), G2 (laser placebo-sham irradiation), G3 (laser irradiation at 780 nm, 40 mW, 4 J/cm 2 ), and G4 (laser irradiation at 780 nm, 40 mW, 40 J/cm 2 ). Spontaneous pain was recorded using a VAS score before (T0), immediately after (T1), and 15 min after treatment (T2). Local anesthetics failure during emergency endodontic treatment was also assessed. There was no pain difference in T1 and T2 between the experimental laser groups (G3 and G4) and the placebo group (G2). The 4-J/cm 2 (G3) irradiation resulted in significant increase in the local anesthetics failure in lower jar teeth. This effect could be suggested as consequence of the LPT improvement in local circulation and vasodilatation that would result in the increase of local anesthetic agent absorption. The application of 780-nm diode laser irradiation, at 4 and 40 J/cm 2 , showed no effect in reducing the pain in SIP in comparison to the placebo group. The fluence of 4 J/cm 2 showed a negative effect in local anesthetics, resulting in significant increase of complimentary local anesthesia during emergency endodontic treatment. This work provides evidence of the consequence of LPT application on teeth with symptomatic irreversible pulpitis. LPT should be avoided in teeth with pain due to irreversible pulpitis.

  16. A molecular low power CO/sub 2/ laser with a stabilized output frequency

    Energy Technology Data Exchange (ETDEWEB)

    Plinski, E.F.; Abramski, K.M.; Nowicki, R.; Pienkowski, J.; Rzepka, J.

    1983-01-01

    This laser has a resonator consisting of a spherical mirror with a slope radius of 10 meters and a reflecting diffraction grating (120 lines per millimeter). The use of this grating makes it possible to isolate one of the lines in the 10.4 or 9.4 micrometer bands. A mirror with a central hole 2.5 millimeters in diameter is mounted on a piezoceramic holder designed for tuning the resonator. Frequency stabilization is based on synchronous detection. An auxillary modulating signal injected to a specific section of the piezoceramic holder modulates the level of the laser. The change in the output power may be detected using an uncooled detector (Cd, Hg) Te. The error signal, injected to the holder, tunes the resonator so that it operates in the center of the output power curve.

  17. Development of oral mucositis model induced by radiation in hamsters: prevention and treatment with low power laser

    Energy Technology Data Exchange (ETDEWEB)

    Galletta, Vivian C.; Folgosi-Correa, Melissa S.; Zezell, Denise M., E-mail: vivian.galletta@gmail.com, E-mail: melfolgosi@gmail.com, E-mail: zezell@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Gouw-Soares, Sheila, E-mail: sheilagouw@hotmail.com [Universidade Cruzeiro do Sul (UNICSUL), Sao Paulo, SP (Brazil). Fac. de Odontologia; Correa, Luciana, E-mail: lcorrea@usp.br [Universidade de Sao Paulo (FO/USP), SP (Brazil). Fac. de Odontologia

    2013-07-01

    Despite the benefits for the prognosis of patients treated with radiotherapy for oral cancer treatment, it might cause local side effects such as oral mucositis. The oral mucositis is a pathological condition that may appear in affected oral mucosa by ionizing radiation, and the pain related can alter and even stop the antineoplastic treatment, decreasing tumor control rates. Oral mucositis has several treatment modalities, although it remains as a problem since therapies available are not enough to treat efficiently this inflammatory process. Many pharmacological solutions (anti-inflammatory, antibiotics, antiseptic, lubricant agents) are used to alleviate oral mucositis symptoms. Laser treatment has been used as an option, but there is lack of studies to verify the process of laser therapy in oral mucositis caused by ionizing radiation. This work accomplishes follow-up of oral mucositis evolution, comparing laser and benzydamine therapies in an animal model. Forty-two animals were irradiated at head and neck in a single dose of 30 Grays, by means of a Co{sup 60} source. After irradiation, treatments were applied daily, once a day, for 20 days, in which severity of lesions were clinically classified by two calibrated examiners. Histological evaluation was performed to search for mucosal alterations at treated tissues. Statistical analysis of data showed that laser treatment was more efficient than benzydamine treatment, diminishing severity and duration of oral mucosal lesions caused by ionizing irradiation. (author)

  18. Development of oral mucositis model induced by radiation in hamsters: prevention and treatment with low power laser

    International Nuclear Information System (INIS)

    Galletta, Vivian C.; Folgosi-Correa, Melissa S.; Zezell, Denise M.; Gouw-Soares, Sheila; Correa, Luciana

    2013-01-01

    Despite the benefits for the prognosis of patients treated with radiotherapy for oral cancer treatment, it might cause local side effects such as oral mucositis. The oral mucositis is a pathological condition that may appear in affected oral mucosa by ionizing radiation, and the pain related can alter and even stop the antineoplastic treatment, decreasing tumor control rates. Oral mucositis has several treatment modalities, although it remains as a problem since therapies available are not enough to treat efficiently this inflammatory process. Many pharmacological solutions (anti-inflammatory, antibiotics, antiseptic, lubricant agents) are used to alleviate oral mucositis symptoms. Laser treatment has been used as an option, but there is lack of studies to verify the process of laser therapy in oral mucositis caused by ionizing radiation. This work accomplishes follow-up of oral mucositis evolution, comparing laser and benzydamine therapies in an animal model. Forty-two animals were irradiated at head and neck in a single dose of 30 Grays, by means of a Co 60 source. After irradiation, treatments were applied daily, once a day, for 20 days, in which severity of lesions were clinically classified by two calibrated examiners. Histological evaluation was performed to search for mucosal alterations at treated tissues. Statistical analysis of data showed that laser treatment was more efficient than benzydamine treatment, diminishing severity and duration of oral mucosal lesions caused by ionizing irradiation. (author)

  19. Spatially resolved nanostructural transformation in graphite under femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Marcu, A., E-mail: aurelian.marcu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Avotina, L. [Institute of Chemical Physics, University of Latvia, Kronvalda 4, LV 1010 Riga (Latvia); Porosnicu, C. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Marin, A. [Ilie Murgulescu” Institute of Physical Chemistry, 202 Splaiul Independentei 060021, Bucharest (Romania); Grigorescu, C.E.A. [National Institute R& D for Optoelectronics INOE 2000, 077125 Bucharest (Romania); Ursescu, D. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Lungu, M. [National Institute of Materials Physics Atomistilor Str., 105 bis, 077125, Magurele (Romania); Demitri, N. [Hard X-ray Beamline and Structural Biology, Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163,5 in AREA Science Park, 34149 Basovizza TS Italy (Italy); Lungu, C.P. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania)

    2015-11-15

    Graphical abstract: - Highlights: • Polycrystalline graphite was irradiated with a high power fs (IR) laser. • Presence of a diamond peak was detected by synchrotron XRD. • XPS and Raman showed in-depth sp{sup 3}% increase at tens of nm below the surface. • sp{sup 3}% is increasing with laser power density but it is independent of photon absorption rate. • Graphite crystallite size locally increase at tens of nanometers below the irradiated spots. - Abstract: A polycrystalline graphite target was irradiated using infrared (800 nm) femtosecond (120 fs) laser pulses of different energies. Increase of sp{sup 3} bonds percentage and possible diamond crystal formation were investigated ‘in-depth’ and on the irradiated surfaces. Synchrotron X-ray diffraction pattern have shown the presence of a diamond peak in one of the irradiated zones while X-ray photoelectron spectroscopy investigations have shown an increasing tendency of the sp{sup 3} percent in the low power irradiated areas and similarly ‘in the depth’ of the higher power irradiated zones. Multiple wavelength Micro-Raman investigations have confirmed this trend along with an ‘in-depth’ (but not on the surface) increase of the crystallite size. Based on the wavelength dependent photon absorption into graphite, the observed effects are correlated with high density photon per atom and attributed to the melting and recrystallization processes taking place tens of nanometers below the target surface.

  20. Spatially resolved nanostructural transformation in graphite under femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Marcu, A.; Avotina, L.; Porosnicu, C.; Marin, A.; Grigorescu, C.E.A.; Ursescu, D.; Lungu, M.; Demitri, N.; Lungu, C.P.

    2015-01-01

    Graphical abstract: - Highlights: • Polycrystalline graphite was irradiated with a high power fs (IR) laser. • Presence of a diamond peak was detected by synchrotron XRD. • XPS and Raman showed in-depth sp 3 % increase at tens of nm below the surface. • sp 3 % is increasing with laser power density but it is independent of photon absorption rate. • Graphite crystallite size locally increase at tens of nanometers below the irradiated spots. - Abstract: A polycrystalline graphite target was irradiated using infrared (800 nm) femtosecond (120 fs) laser pulses of different energies. Increase of sp 3 bonds percentage and possible diamond crystal formation were investigated ‘in-depth’ and on the irradiated surfaces. Synchrotron X-ray diffraction pattern have shown the presence of a diamond peak in one of the irradiated zones while X-ray photoelectron spectroscopy investigations have shown an increasing tendency of the sp 3 percent in the low power irradiated areas and similarly ‘in the depth’ of the higher power irradiated zones. Multiple wavelength Micro-Raman investigations have confirmed this trend along with an ‘in-depth’ (but not on the surface) increase of the crystallite size. Based on the wavelength dependent photon absorption into graphite, the observed effects are correlated with high density photon per atom and attributed to the melting and recrystallization processes taking place tens of nanometers below the target surface.

  1. Fungicidal response of a novel natural photosensitizer (Beta vulgaris) on Candida albicans with low-power laser radiation

    International Nuclear Information System (INIS)

    Mittal, Subhangi; Srivastava, J N; Roy, Sukhdev

    2013-01-01

    We report the efficacy of an aqueous extract of Beta vulgaris as a novel, natural photosensitizer for use in photodynamic therapy against Candidiasis disease. This study evaluates the effect of different laser wavelengths (He–Ne: 633 nm, Nd-YAG: 532 nm), power (17, 27 mW) and duration of exposure (5, 10, 15 min) in combination with the Beta vulgaris natural photosensitizer on the viability of Candida albicans causing Candidiasis disease. Although inhibition was observed in all cases, a maximum of 51.91% inhibition takes place with the combination of Beta vulgaris exposed to 532 nm at 27 mW for 15 min by the Agar well diffusion method. The study is important in optimizing different parameters and designing a low-power, compact, non-invasive and portable device for treatment. (paper)

  2. Low power laser driver design in 28nm CMOS for on-chip and chip-to-chip optical interconnect

    Science.gov (United States)

    Belfiore, Guido; Szilagyi, Laszlo; Henker, Ronny; Ellinger, Frank

    2015-09-01

    This paper discusses the challenges and the trade-offs in the design of laser drivers for very-short distance optical communications. A prototype integrated circuit is designed and fabricated in 28 nm super-low-power CMOS technology. The power consumption of the transmitter is 17.2 mW excluding the VCSEL that in our test has a DC power consumption of 10 mW. The active area of the driver is only 0.0045 mm2. The driver can achieve an error-free (BER < 10 -12) electrical data-rate of 25 Gbit/s using a pseudo random bit sequence of 27 -1. When the driver is connected to the VCSEL module an open optical eye is reported at 15 Gbit/s. In the tested bias point the VCSEL module has a measured bandwidth of 10.7 GHz.

  3. Clinical effectiveness of low-power laser radiation and functioning of hemosalivatory barrier in patients with rheumatic diseases

    Science.gov (United States)

    Gladkova, Natalia D.; Karachistov, Alexander B.; Komarova, Lia G.; Alekseeva, Olga P.; Grunina, Elena A.

    1996-11-01

    We have estimated the clinical effectiveness of several regimes and ways of low power laser therapy (LT) on the basis of a double 'blind', placebo-controlling randomizing comparative test in 454 patients with rheumatic diseases (RD). LT for RD has a well-expressed placebo effect. The level of clinical effect of LT for RD is not so high. We couldn't achieve 'a considerable improvement' in any cases, 'an improvement' was secured in only 18 percent. LT should be viewed as a symptomatic means, with a primary anesthetic and feebly expressed anti-inflammatory effect, which can not influence the course of the rheumatoid process. Only in 15 percent of patients with RD, a sufficient functioning of hemo-salivary barrier was observed, the latter providing a reserve for adaption mechanism, which leads under the influence of stressor agents of medium strength not only to anesthetic, but also to moderately expressed anti- inflammatory effect.

  4. [Krypton laser photocoagulation at low power setting for age-related macular degeneration complicated with subfoveal choroidal neovascularization].

    Science.gov (United States)

    Zhang, Cheng-fen; Jia, Yan; Li, Zhi-qing; Du, Hong; Han, Bao-ling

    2004-12-01

    To evaluate the efficacy of krypton laser photocoagulation for treatment of age-related macular degeneration (AMD) complicated with mainly subfoveal classic choroidal neovascularization (CNV). Seventeen eyes of 17 cases, aged 50 - 74 years (averaged 60.8 years) with mainly subfoveal classic choroidal neovascularization were treated with krypton laser at lower power setting. The treatment was completed in one session. Another course of treatment was given 4 weeks later if there was active leakage demonstrated at the CNV area. Visual acuity, anterior segment and fundus examination, perimetry test, fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were performed before and after treatment. The follow-up period was 3.5 years on average (1 - 8 years). There was no immediately decrease of visual acuity after treatment. All treated eyes showed absorption of hemorrhages and/or exudates and diminished leakages. Visual acuity was stable in 8 eyes; improved in 6 eyes (>/= 2 lines), and decreased in 3 eyes (Krypton laser photocoagulation at low power setting is an effective treatment for AMD with mainly classic subfoveal choroidal neovascularization.

  5. Effect of UV laser irradiation on tissue

    International Nuclear Information System (INIS)

    Nakayama, Takeyoshi; Kubo, Uichi

    1992-01-01

    Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)

  6. Analysis of the influence of low-power HeNe laser on the healing of skin wounds in diabetic and non-diabetic rats

    Directory of Open Access Journals (Sweden)

    Carvalho Paulo de Tarso Camillo de

    2006-01-01

    Full Text Available PURPOSE: To study the influence of HeNe laser irradiation on the collagen percentage in surgically-induced skin wounds in rats with and without alloxan-induced diabetes, by morphometric analysis of collagen fibers. METHODS: 48 male Wistar rats were used, divided into groups: laser-treated diabetic (group 1; untreated diabetic (group 2; treated non-diabetic (group 3; and untreated non-diabetic (group 4. For groups 1 and 2, diabetes was induced by intravenous injection of alloxan (2,4,5,6-tetraoxypyrimidine; 5,6-dioxyuracil; Sigma, into the dorsal vein of the penis, at a rate of 0.1 ml of solution per 100 g of body weight. A wound was made on the back of all the animals. Groups 1 and 3 were treated with HeNe laser (4 J/cm² for 60 s. One animal from each group was sacrificed on the 3rd, 7th and 14th days after wounding. Samples were taken, embedded in paraffin, stained with hematoxylin-eosin and Masson's trichrome, and morphometrically analyzed using the Imagelab software. The percentages of collagen fibers were determined from the samples from the euthanasia animals. The data were treated statistically using analysis of variance (ANOVA and the Student t and Kruskal-Wallis tests. The significance level was set at 0.05 or 5%. RESULTS: The results obtained from the samples taken on the third, seventh and fourteenth days after wounding demonstrated that the laser-treated group presented a statistically significant (p<0.05 greater mean quantity of collagen fibers than in the non-treated group, both for diabetic rats (p = 0.0104 and for non-diabetic rats (p = 0.039. CONCLUSION: The low-power laser (632.8 nm was shown to be capable of influencing the collagen percentage in skin wounds by increasing the mean quantity of collagen fibers, both for the diabetic and for the non-diabetic group.

  7. Histological and radiographic evaluation of the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a scaffold of inorganic bone and after stimulation with low-power laser light

    Directory of Open Access Journals (Sweden)

    Bengtson Antonio

    2010-01-01

    Full Text Available Objective: The present study histologically and radiologically evaluates the muscle tissue of rats after implantation of bone morphogenic protein (rhBMP-2 in a natural inorganic bone mineral scaffold from a bull calf femur and irradiation with low-power light laser. Materials and Methods: The right and left hind limbs of 16 rats were shaved and an incision was made in the muscle on the face corresponding to the median portion of the tibia, into which rhBMP-2 in a scaffold of inorganic bone was implanted. Two groups of limbs were formed: control (G1 and laser irradiation (G2. G2 received diode laser light applied in the direction of the implant, at a dose of 8 J/cm2 for three minutes. On the 7th, 21st, 40th and 112th days after implantation, hind limbs of 4 animals were radiographed and their implants removed together with the surrounding tissue for study under the microscope. The histological results were graded as 0=absence, 1=slight presence, 2=representative and 3=very representative, with regard to the following events: formation of osteoid structure, acute inflammation, chronic inflammation, fibrin deposition, neovascularization, foreign-body granuloma and fibrosis. Results: There were no statistically significant differences in these events at each evaluation times, between the two groups (P > 0.05; Mann-Whitney test. Nevertheless, it could be concluded that the natural inorganic bone matrix with rhBMP-2, from the femur of a bull calf, is a biocompatible combination. Conclusions: Under these conditions, the inductive capacity of rhBMP-2 for cell differentiation was inhibited. There was a slight acceleration in tissue healing in the group that received irradiation with low-power laser light.

  8. A low-power RF system with accurate synchronization for a S-band RF-gun using a laser-triggered photocathode

    International Nuclear Information System (INIS)

    Otake, Y.; Naito, T.; Shintake, T.; Takata, K.; Takeuchi, Y.; Urakawa, J.; Yoshioka, M.; Akiyama, H.

    1992-01-01

    An S-band RF-gun using a laser-triggered photocathode and its low-power RF system have been constructed. The main elements of the low-power RF system comprise a 600-W amplifier, an amplitude modulator, a phase detector, a phase shifter and a frequency-divider module. Synchronization between the RF fields for acceleration and the mode-locked laser pulses for beam triggering are among the important points concerning the RF-gun. The frequency divider module which down-converts from 2856 MHz(RF) to 89.25 MHz(laser), and the electrical phase-shifter were specially developed for stable phase control. The phase jitter of the frequency divider should be less than 10 ps to satisfy our present requirements. The first experiments to trigger and accelerate beams with the above-mentioned system were carried out in January, 1992. (Author) 6 figs., 5 refs

  9. Sapphire capillary interstitial irradiators for laser medicine

    Science.gov (United States)

    Shikunova, I. A.; Dolganova, I. N.; Dubyanskaya, E. N.; Mukhina, E. E.; Zaytsev, K. I.; Kurlov, V. N.

    2018-04-01

    In this paper, we demonstrate instruments for laser radiation delivery based on sapphire capillary needles. Such sapphire irradiators (introducers) can be used for various medical applications, such as photodynamic therapy, laser hyperthermia, laser interstitial thermal therapy, and ablation of tumors of various organs. Unique properties of sapphire allow for effective redistribution of the heat, generated in biological tissues during their exposure to laser radiation. This leads to homogeneous distribution of the laser irradiation around the needle, and lower possibility of formation of the overheating focuses, as well as the following non-transparent thrombi.

  10. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    Directory of Open Access Journals (Sweden)

    Shamini Janasekaran

    2016-06-01

    Full Text Available Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW, low-power Ytterbium (Yb-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on weld morphology and properties was investigated using scanning electron microscopy (SEM and X-ray diffraction (XRD, respectively. XRD analysis revealed the presence of intermetallic layers containing NiTi and NiTi2 at the skin-stringer joint. The strength of the joints was evaluated using pull testing, while the hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM, fusion zone (FZ and heat-affected zone (HAZ. The results showed that the highest force needed to break the samples apart was approximately 150 N at a laser welding power of 250 W, welding speed of 40 mm/s and overlapping factor of 50%. During low-power single-sided laser welding, the properties of the T-joints were affected by the overlapping factor and laser welding speed.

  11. Study of the effect of low-power pulse laser on arc plasma and magnesium alloy target in hybrid welding by spectral diagnosis technique

    Science.gov (United States)

    Liu, Liming; Hao, Xinfeng

    2008-10-01

    In order to study the effect of laser pulses on arc plasma and target metal in the hybrid welding process, the spectra of the plasmas in the welding process of magnesium alloys are analysed in this paper. The acquisition system of plasma spectra is set up and the spectral lines of welding plasma are acquired. Compared with tungsten-inert gas (TIG) welding, the intensities of the spectral lines of magnesium increase sharply while those of Ar decrease for strong evaporation and ionization of magnesium alloys in low-power laser/arc hybrid welding. The electron temperature and density are estimated by the Boltzmann plot method and the Stark broadening effect. The result shows that the electron temperature of arc plasma in the hybrid welding process is much lower than that in TIG welding, especially in the laser beam-affected zone. In contrast, the electron density of the plasma is enhanced. The influences of laser parameters on electron temperature are also studied. The changes in electron temperature and density indicate that the effect of laser pulse on the target metal is the dominant factor influencing the electron temperature and density in low-power laser/arc hybrid welding.

  12. A study of low power laser on the regenerative process of Girardia tigrina (Girard,1850 (Turbellaria; Tricladida; Dugesiidae Um estudo de laser de baixa potência no processo regenerativo de Girardia tigrina (Girard,1850 (Turbellaria; Tricladida; Dugesiidae

    Directory of Open Access Journals (Sweden)

    KAR. Lopes

    2009-05-01

    Full Text Available The mechanism of regeneration does not start to restore the wound until its corresponding epimorphic phase. A bioestimulation of tissues and cells by laser radiation depends on the wavelength, on the dose, and on the intensity of the light. The goal of this work was to verify the effect of the low power laser at 660 nm on the regenerative process of Girardia tigrina. The specimens were maintained in the laboratory under a temperature ranging from 19° up to 24 °C for 21 days. The planarians were anesthetized by placing them on ice and then cut them with a scalpel. The three treatments were as following: animals individually irradiated with 14 sessions with 1 minute duration (treatment 1, 14 sessions with 3 minutes duration (treatment 2, and without irradiation (control. The planarians were amputated and divided in three study treatments: a control group (without radiation, and two other treatments: irradiated for 1 minute, and irradiated for 3 minutes. The animals were irradiated with diode laser (660 nm with 3.3 ± 0.3 mW of power, using 0.94 mW.mm-2 power density for each irradiation procedure. During the experiment, 14 irradiation sessions were undertaken. The specimens were fixed in Bouin, and stained with hematoxyline and eosin. From observation and histological analysis, it was possible to assess the effects of interaction between laser and tissue. The head fragment after 1 minute of irradiation presented a better organized tissue scheme, when compared with the other treatments. Aspects of the body fragments submitted to 3 minutes of light treatment were very similar to fragments that had not been injured. It can be concluded that there are changes in the quality of regeneration when treated with low power laser under the conditions mentioned above.O mecanismo de regeneração não restaura a ferida até sua fase epimórfica correspondente. A bioestimulação de tecidos e células por radiação laser depende do comprimento de onda, da

  13. Laser irradiation of carbon–tungsten materials

    International Nuclear Information System (INIS)

    Marcu, A; Lungu, C P; Ursescu, D; Porosnicu, C; Grigoriu, C; Avotina, L; Kizane, G; Marin, A; Osiceanu, P; Grigorescu, C E A; Demitri, N

    2014-01-01

    Carbon–tungsten layers deposited on graphite by thermionic vacuum arc (TVA) were directly irradiated with a femtosecond terawatt laser. The morphological and structural changes produced in the irradiated area by different numbers of pulses were systematically explored, both along the spots and in their depths. Although micro-Raman and Synchrotron-x-ray diffraction investigations have shown no carbide formation, they have shown the unexpected presence of embedded nano-diamonds in the areas irradiated with high fluencies. Scanning electron microscopy images show a cumulative effect of the laser pulses on the morphology through the ablation process. The micro-Raman spatial mapping signalled an increased percentage of sp 3 carbon bonding in the areas irradiated with laser fluencies around the ablation threshold. In-depth x-ray photoelectron spectroscopy investigations suggested a weak cumulative effect on the percentage increase of the sp 2 -sp 3 transitions with the number of laser pulses just for nanometric layer thicknesses. (paper)

  14. Interactions of low-power photons with natural opals—PBG materials, photonic control, natural metamaterials, spontaneous laser emissions, and band-gap boundary responses

    International Nuclear Information System (INIS)

    Stem, Michelle R.

    2012-01-01

    Four views of each of the opal research specimens in white light (for in-article or cover), in the same order as the specimens depicted in Fig. 3 of the main manuscript. A.On the left: 1.5 carat oval cabochon precious fire opal. B.In the center: 2.5 carats faceted fancy shield precious fire contra luz with mild adularescence. C.On the right: 5.0 carats round cabochon precious crystal opal with blue adularescence. Highlights: ► Emission of micro-lasers from microspheroid cluster boundary zones (quantum dots). ► Lasers illuminated or fluoresced the intra-opal structures of microspheroid photonic glass clusters. ► Microspheroid boundaries are durable to low power light sources. ► Display of previously unknown low power photonic optic properties. ► The research specimens are natural metamaterials. - Abstract: One overall goal of this research was to examine types of naturally-occurring opals that exhibit photonic control to learn about previously-unknown properties of naturally occurring photonic control that may be developed for broader applications. Three different photon sources were applied consecutively to three different types of natural, flawless, gem-quality precious opals. Two photon sources were lasers (green and red) and one was simulated daylight tungsten white. As each type of precious opal was exposed to each of the photon sources, the respective refractions, reflections, and transmissions were studied. This research is the first to show that applying various pleochroic and laser photon sources to these types of opals revealed significant information regarding naturally occurring photonic control, metamaterials, spontaneous laser emissions, and microspheroid cluster (inter-PBG zone) boundary effects. Plus, minimizing ambient light and the use of low power photon sources were critical to observing the properties regarding this photonic materials research. This research yielded information applicable to the development of materials to advance

  15. Age-dependent effects of He-Ne laser irradiation on the membrane fluidity of human erythrocytes

    Science.gov (United States)

    Kovacs, Eugenia; Savopol, Tudor; Pologea-Moraru, Roxana; Makropoulou, Mersini I.; Serafetinides, Alexander A.

    1997-12-01

    The low power He-Ne laser radiation has been extensively used in past decades as medical device to relieve pain, accelerate wound healing as well as aiming beam in invisible laser beam in invisible laser beam applications. It is not known however if there are any secondary, undesirable effects of He-Ne laser radiation on the irradiated tissue. In this paper we investigate the changes induced in membrane fluidity of human erythrocyte during/upon the interaction with the He-Ne laser beam having the parameters currently used for target aiming in laser surgery.

  16. Effect of semiconductor GaAs laser irradiation on pain perception in mice

    Energy Technology Data Exchange (ETDEWEB)

    Zarkovic, N.; Manev, H.; Pericic, D.; Skala, K.; Jurin, M.; Persin, A.; Kubovic, M.

    1989-01-01

    The influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser-stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot-licking or jumping from the surface of a 53 degrees C hot plate. Repeated hot-plate testing resulted in shortening of latencies in both sham- and laser-irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception. Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham- and laser-irradiated mice. This prolongation tended to be lesser in laser-irradiated animals. Further investigations are required to elucidate the mechanism of the observed effect of laser.

  17. Microstructure and properties of the low-power-laser clad coatings on magnesium alloy with different amount of rare earth addition

    International Nuclear Information System (INIS)

    Zhu, Rundong; Li, Zhiyong; Li, Xiaoxi; Sun, Qi

    2015-01-01

    Highlights: • The low-power-laser was used to obtain the excellent coatings with different amount of Y_2O_3 addition. • The addition of rare earth oxide Y_2O_3 refined and purified the microstructure of the coatings, meanwhile, increased the thickness of the coatings and reduced the dilution of cladding materials from based alloy. • The primary phases in the coatings are Mg_3_2Al_4_7Cu_7, MgCu_6Al_5, Al_2CuMg and Al_1_2Mg_1_7. The A_l_4MgY and MgAl_2O_4 phase can be found in Y_2O_3-modified coatings. • The micro-hardness and the abrasion resistance of the coatings with Y_2O_3 had been improved obviously compared with the coatings without Y_2O_3. • The corrosion resistance of the AZ91D magnesium alloy had been improved by laser cladding. And the effect of Y_2O_3 on the corrosion potential of the coatings was less than the effect of Y_2O_3 on corrosion current density of the coatings. - Abstract: Due to the low-melting-point and high evaporation rate of magnesium at elevated temperature, high power laser clad coating on magnesium always causes subsidence and deterioration in the surface. Low power laser can reduce the evaporation effect while brings problems such as decreased thickness, incomplete fusion and unsatisfied performance. Therefore, low power laser with selected parameters was used in our research work to obtain Al–Cu coatings with Y_2O_3 addition on AZ91D magnesium alloy. The addition of Y_2O_3 obviously increases thickness of the coating and improves the melting efficiency. Furthermore, the effect of Y_2O_3 addition on the microstructure of laser clad Al–Cu coatings was investigated by scanning electron microscopy. The energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to examine the elemental and phase compositions of the coatings. The properties were investigated by micro-hardness test, dry wear test and electrochemical corrosion. It was found that the addition of Y_2O_3 refined the microstructure. The micro

  18. Argon laser irradiation of the otolithic organ

    Energy Technology Data Exchange (ETDEWEB)

    Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

    1990-12-01

    An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

  19. Application of Laser Irradiation for Restorative Treatments

    OpenAIRE

    Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

    2016-01-01

    Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal ...

  20. Effects of He-Ne laser irradiation on red blood cells in vitro

    Science.gov (United States)

    Ghadage, Vijay H.; Kulkarni, Gauri R.

    2011-03-01

    Laser radiation has many applications in biomedical field, such as wound healing, tissue repairing, heating and ablation processes. Intravenous low power laser radiation is used clinically for skin and vascular disorders. Laser radiation improves microcirculation and modulates the rheological properties of blood. FTIR (Fourier Transform Infra Red Spectra) is used to see the structural changes in erythrocyte membrane. In the present work He Ne laser (λ= 632nm, power=2mW) is used to irradiate human Red blood cells. Red blood cells are separated from human whole blood using centrifugation method (time=10 min., temperature=15°C and RPM=3000) and then exposed to HeNe laser radiation. Laser exposure time is varied from 10 min. to 40min for Red blood cells. Absorption spectrum, FTIR and fluorescence spectra of RBC are compared before and after HeNe laser irradiation. The absorption spectrum of RBC after exposure to HeNe laser shows a significant decrease in absorbance. The FTIR spectrum of non irradiated RBC clearly show the peaks due to O-H (free group), C=O (amide I group), N=O (nitro group), C-O (anhydride group) and C-H (aromatic group). Laser radiation changes in transmittance in FTIR spectra related to C=O group and percentage of transmittance increases for O-H, C=C, N=O, C-O and C-H group.

  1. Heat profiles of laser-irradiated nails.

    Science.gov (United States)

    Paasch, Uwe; Nenoff, Pietro; Seitz, Anna-Theresa; Wagner, Justinus A; Kendler, Michael; Simon, Jan C; Grunewald, Sonja

    2014-01-01

    Onychomycosis is a worldwide problem with no tendency for self-healing, and existing systemic treatments achieve disease-free nails in only 35 to 76% of cases. Recently, treatment of nail fungus with a near-infrared laser has been introduced. It is assumed that fungal eradication is mediated by local heat. To investigate if laser treatment has the potential to eradicate fungal hyphae and arthrospores, laser heat application and propagation needs to be studied in detail. This study aimed to measure nail temperatures using real-time videothermography during laser irradiation. Treatment was performed using 808- and 980-nm linear scanning diode lasers developed for hair removal, enabling contact-free homogeneous irradiation of a human nail plate in one pass. Average and peak temperatures increased pass by pass, while the laser beam moved along the nail plates. The achieved mean peak temperatures (808 nm: 74.1 to 112.4°C, 980 nm: 45.8 to 53.5°C), as well as the elevation of average temperatures (808 nm: 29.5 to 38.2°C, 980 nm: 27.1 to 32.6°C) were associated with pain that was equivalent to that of hair removal procedures and was not significantly different for various wavelengths. The linear scanning laser devices provide the benefits of contact-free homogeneous heating of the human nail while ensuring adequate temperature rises.

  2. Application of Laser Irradiation for Restorative Treatments.

    Science.gov (United States)

    Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

    2016-01-01

    Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal hemorrhage, sterilization, healing of collagenic proteins, formation of a fibrous matrix, and inducing hard tissue barrier. Nevertheless, there are many controversies in literatures regarding their effects on the quality of bonded restorations. It hampered a wide application of lasers in some aspects of restorative dentistry and requirements to identify the best way to use this technology. The aim of this mini review is to explain special characteristics of laser therapy and to introduce the possible applications of laser devices for dental purposes.

  3. Low-power holmium:YAG laser urethrotomy for treatment of urethral strictures: functional outcome and quality of life.

    Science.gov (United States)

    Kamp, Stefan; Knoll, Thomas; Osman, Mahmoud M; Köhrmann, Kai Uwe; Michel, Maurice S; Alken, Peter

    2006-01-01

    To evaluate the efficacy of endourethrotomy with the holmium:YAG laser as a minimally invasive treatment for urethral stricture. Between January 2002 and January 2004, 32 male patients with symptomatic urethral strictures (8 bulbar, 9 penile, 9 combined) were treated with Ho:YAG-laser urethrotomy in our department. The stricture was iatrogenic in 60% (N = 18), inflammatory in 16.6% (N = 5), traumatic in 13.3% (N = 4), and idiopathic in 7% (N = 3). The stricture was incised under vision at the 12 o'clock location or the site of maximum scar tissue or narrowing in asymmetric strictures. Laser energy was set on 1200 to 1400 mJ with a frequency of 10 to 13 Hz. Postoperatively, drainage of the bladder was performed for 4 days using a 18F silicone catheter. Triamcinolone was instilled intraurethrally after removal of the catheter in all patients. Patients were followed up by mailed questionnaire, including International Prostate Symptom Score and quality of life. Retrograde endoscopic Ho:YAG laser urethrotomy could be performed in all 32 patients. Most patients (22; 68.7%) did not need any reintervention. Ten patients developed recurrent strictures that were treated by another laser urethrotomy in 4 patients (12.5%), while 6 patients (18.7%) needed open urethroplasty with buccal mucosa. Including 2 patients treated with repeat laser urethrotomy, 24 patients (75%) were considered successful after a mean follow-up of 27 months (range 13-38 months). No intraoperative complications were encountered, although in 5% of patients, a urinary-tract infection was diagnosed postoperatively. No gross hematuria occurred. The Ho:YAG laser urethrotomy is a safe and effective minimally invasive therapeutic modality for urethral stricture with results comparable to those of conventional urethrotomy. Further data from long-time follow-up are necessary to compare the success rate with that of conventional urethrotomy and urethroplasty. Nevertheless, the Ho:YAG laser urethrotomy might at

  4. Performance of Shiva as a laser fusion irradiation facility

    International Nuclear Information System (INIS)

    Speck, D.R.; Bliss, E.S.; Glaze, J.A.; Johnson, B.C.; Manes, K.R.; Ozarski, R.G.; Rupert, P.R.; Simmons, W.W.; Swift, C.D.; Thompson, C.E.

    1979-01-01

    Shiva is a 20 beam Nd:Glass Laser and Target Irradiation Facility at the Lawrence Livermore Laboratory. The laser system and integrated target facility evolved during the last year from a large, untested, experimental laser system to a target irradiation facility which has provided significant laser driven inertial confinement fusion data. The operation of the facility is discussed

  5. Stable single-mode distributed feedback quantum cascade lasers at λ ∼ 4.25 μm with low power consumption

    Science.gov (United States)

    Jia, Zhiwei; Wang, Lijun; Zhang, Jinchuan; Liu, Fengqi; Zhuo, Ning; Zhai, Shenqiang; Liu, Junqi; Wang, Zhanguo

    2016-10-01

    Short-wavelength (4.25 μm) distributed-feedback quantum cascade laser operating in continuous wave (cw) mode at room temperature with low power consumption was presented. Stable single-mode operation with a side-mode-suppression-ratio above 25 dB was maintained for the whole measured current and temperature range by enlarging gain difference and strong grating coupling. Because of the strong coupling, very low threshold current and power consumption were achieved. For a device of 9-μm-wide and 2-mm-long, the cw threshold current and power consumption at 293 K were as low as 126 mA and 1.45 W, respectively. All results above were from the device without using buried heterostructure geometry.

  6. Al-TiC in situ composite coating fabricated by low power pulsed laser cladding on AZ91D magnesium alloy

    Science.gov (United States)

    Yang, Liuqing; Li, Zhiyong; Zhang, Yingqiao; Wei, Shouzheng; Liu, Fuqiang

    2018-03-01

    Al + (Ti + B4C) composite coating was cladded on AZ91D magnesium alloy by a low power pulsed Nd-YAG laser. The Ti+B4C mixed powder is with the ratio of Ti: B4C = 5:1, which was then mixed with Al powder by weight fraction of 10%, 15% and 20%, respectively. Scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction were used to study the microstructure, chemical composition and phase composition of the coating. Results showed that the coating had satisfied metallurgical bonding with the magnesium substrate. Al3Mg2, Al12Mg17, Al3Ti and TiC were formed by in-situ reaction. The coatings have micro-hardness of 348HV, which is about 5-6 times higher than that of AZ91D. The wear resistance and corrosion resistance of the coatings are enhanced with the addition of the mixed powder.

  7. Effect of bone marrow and low power lasers on fracture healing with destruction of both periosteum and endosteum in rabbits

    Directory of Open Access Journals (Sweden)

    M. G. Thanoon

    2010-01-01

    Full Text Available Ten mature rabbits of local breed were used in this study; weighing between 1.5 to 1.75 kg and aged about 1–2 years. These animals were divided into two equal groups; in group A destruction of both periosteum and endosteum was done one centimeter from each side of mid-shaft femoral bone fracture, then sufficient amount of autogenously bone marrow was injected directly at the fracture site after immobilization by intramedullary pin. In group B a similar procedure was achieved as in group A, but in additional to that He-Ne infrared laser therapy was used for several sessions. The result of radiological findings indicated that, the fracture healing occurred within group B at fifteen weeks, whereas in group A the healing occurred at eighteen weeks after operation. The implantation of autologous bone marrow enhanced the fracture healing, whereas using of combinations of autologous bone marrow and He-Ne infrared laser therapy hastened the healing.

  8. Microstructure and properties of the low-power-laser clad coatings on magnesium alloy with different amount of rare earth addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Rundong; Li, Zhiyong, E-mail: lizhiyong@nuc.edu.cn; Li, Xiaoxi; Sun, Qi

    2015-10-30

    Highlights: • The low-power-laser was used to obtain the excellent coatings with different amount of Y{sub 2}O{sub 3} addition. • The addition of rare earth oxide Y{sub 2}O{sub 3} refined and purified the microstructure of the coatings, meanwhile, increased the thickness of the coatings and reduced the dilution of cladding materials from based alloy. • The primary phases in the coatings are Mg{sub 32}Al{sub 47}Cu{sub 7}, MgCu{sub 6}Al{sub 5}, Al{sub 2}CuMg and Al{sub 12}Mg{sub 17}. The A{sub l4}MgY and MgAl{sub 2}O{sub 4} phase can be found in Y{sub 2}O{sub 3}-modified coatings. • The micro-hardness and the abrasion resistance of the coatings with Y{sub 2}O{sub 3} had been improved obviously compared with the coatings without Y{sub 2}O{sub 3}. • The corrosion resistance of the AZ91D magnesium alloy had been improved by laser cladding. And the effect of Y{sub 2}O{sub 3} on the corrosion potential of the coatings was less than the effect of Y{sub 2}O{sub 3} on corrosion current density of the coatings. - Abstract: Due to the low-melting-point and high evaporation rate of magnesium at elevated temperature, high power laser clad coating on magnesium always causes subsidence and deterioration in the surface. Low power laser can reduce the evaporation effect while brings problems such as decreased thickness, incomplete fusion and unsatisfied performance. Therefore, low power laser with selected parameters was used in our research work to obtain Al–Cu coatings with Y{sub 2}O{sub 3} addition on AZ91D magnesium alloy. The addition of Y{sub 2}O{sub 3} obviously increases thickness of the coating and improves the melting efficiency. Furthermore, the effect of Y{sub 2}O{sub 3} addition on the microstructure of laser clad Al–Cu coatings was investigated by scanning electron microscopy. The energy-dispersive spectrometer (EDS) and X-ray diffractometer (XRD) were used to examine the elemental and phase compositions of the coatings. The properties were investigated

  9. Low power laser effects in cancer cells and fibroblasts submitted the ionizing radiation; Efeitos do laser de baixa potencia em celulas de linhagem tumoral e fibroblastos submetidos a radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Camila Ramos

    2015-07-01

    Cancer is considered a public health problem worldwide. According to Brazil's the National Cancer Institute (INCA), 576,000 new cases of cancer were estimated for 2015 in Brazil, representing the second leading cause of death. Radiotherapy may be a treatment to several of types of cancer, frequently using ionizing radiation to eradicate or prevent the proliferation of tumor cells. This treatment, however, can lead to death of non-tumor cells around in irradiated tissue. Given this, adjuvant therapies that can minimize the side effects of ionizing radiation are of extremely importance. In this context, low power laser (LPL) may be an alternative to modulate the response of healthy cells to ionizing radiation. In this study, cells of human gingival fibroblasts (FMM1) and breast cancer (MDAMB- 231) were exposed to gamma radiation at doses of 2.5 and 10 Gy. After twenty-four hours, cell were irradiated with LPL ( λ= 660 nm, 40 mW and total area of 0.04 cm²) with energy densities of 30, 60, 90, 120 and 150 J/cm². The cell viability was measured during four days, using the trypan blue technique. The influence of LPL on the cell cycle and on expression of the nuclear antigen of cellular proliferation (PCNA) was evaluated by flow cytometry. The expression of β-Galactosidase was the chosen method to assess cell senescence. Considering our adopted parameters, and focusing on the non-tumor cells, we have observed an increase in: 1) cell viability; 2) cell population in phases S and G{sub 2}/M cell cycle; 3) PCNA expression with decrease in senescence. No alterations were observed in the cell viability, with greater population in phases S and G{sub 2}/M cell cycle, while the number of senescent cells and the expression of PCNA were decreased. Therefore, we have concluded that the LPL promoted effects on both cell lineages, with increased cell viability on FMM1 cells, whether cancer cells maintained a decreased proliferation. (author)

  10. Excimer laser irradiation of metal surfaces

    Science.gov (United States)

    Kinsman, Grant

    In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

  11. Fundamentals of laser pulse irradiation of silicon

    International Nuclear Information System (INIS)

    Rimini, E.; Baeri, P.; Russo, G.

    1985-01-01

    A computer model has been developed to describe the space and time evolution of carrier concentration, carrier energy and lattice temperature during nanosecond and picosecond laser pulse irradiation of Si single crystals. In particular the dynamic response has been evaluated for energy density of the ps laser pulse below and above the density threshold for surface melting. The obtained data allow a comparison with time-resolved reflectivity measurements reported in the literature. The available data are fitted by the computer model assuming a relaxation time for the energy transfer from the carriers to the lattice of 1 ps. The validity of the thermal model used to describe laser annealing in the nanosecond regime is assessed. (author)

  12. Enhancement of methane gas sensing characteristics of graphene oxide sensor by heat treatment and laser irradiation.

    Science.gov (United States)

    Assar, Mohammadreza; Karimzadeh, Rouhollah

    2016-12-01

    The present study uses a rapid, easy and practical method for cost-effective fabrication of a methane gas sensor. The sensor was made by drop-casting a graphene oxide suspension onto an interdigital circuit surface. The electrical conductivity and gas-sensing characteristics of the sensor were determined and then heat treatment and in situ laser irradiation were applied to improve the device conductivity and gas sensitivity. Real-time monitoring of the evolution of the device current as a function of heat treatment time revealed significant changes in the conductance of the graphene oxide sensor. The use of low power laser irradiation enhanced both the electrical conductivity and sensing response of the graphene oxide sensor. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Method for mounting laser fusion targets for irradiation

    Science.gov (United States)

    Fries, R. Jay; Farnum, Eugene H.; McCall, Gene H.

    1977-07-26

    Methods for preparing laser fusion targets of the ball-and-disk type are disclosed. Such targets are suitable for irradiation with one or two laser beams to produce the requisite uniform compression of the fuel material.

  14. A Laserterapia de baixa intensidade acelera a regeneração de nervos periféricos Low-power laser therapy accelerates peripheral nerves' regeneration

    Directory of Open Access Journals (Sweden)

    Cristina Endo

    2008-01-01

    Full Text Available Há evidências de que a terapia com o laser pode estimular a regeneração de nervos e esta hipótese foi testada em ratos. Uma lesão por esmagamento controlado foi produzida no nervo isquiático de 20 ratos Wistar, metade dos quais foram submetidos a irradiação efetiva com o laser de arseneto de gálio (AsGa e a outra metade a irradiação simulada, durante dez dias consecutivos, começando no primeiro dia pós-operatório. Os resultados foram avaliados com três semanas pela medida do índice funcional do isquiático (IFC em intervalos semanais e pela medida do número total de fibras nervosas e da densidade de fibras dos nervos, após o sacrifício dos animais na terceira semana, com o nível de significância de 5% (pThere are evidences that laser therapy may stimulate nerve regeneration and this hypothesis was tested in rats. A controlled crush injury was produced on the sciatic nerve of 20 Wistar rats, half of which submitted to effective Ga-As laser irradiation and the other half to simulated irradiation for 10 consecutive days beginning on the first postoperative day. Results were evaluated at three weeks postoperatively by measuring the sciatic functional index (SFI at weekly intervals and the total number of nerve fibers and nerve fiber density of the sciatic nerve at three weeks (p<0.05. The SFI progressively improved for both irradiated and control nerves (69% and 45%, respectively with a significant difference between them at two weeks (p=0.04. Nerve fiber density increased for the irradiated nerves and decreased for the control nerves, with significant differences between them (p=0.001. Low intensity therapeutic ultrasound accelerates nerve regeneration, as demonstrated with significance on the 21st postoperative day.

  15. Kinetics of laser irradiated nanoparticles cloud

    Science.gov (United States)

    Mishra, S. K.; Upadhyay Kahaly, M.; Misra, Shikha

    2018-02-01

    A comprehensive kinetic model describing the complex kinetics of a laser irradiated nanoparticle ensemble has been developed. The absorbed laser radiation here serves dual purpose, viz., photoenhanced thermionic emission via rise in its temperature and direct photoemission of electrons. On the basis of mean charge theory along with the equations for particle (electron) and energy flux balance over the nanoparticles, the transient processes of charge/temperature evolution over its surface and mass diminution on account of the sublimation (phase change) process have been elucidated. Using this formulation phenomenon of nanoparticle charging, its temperature rise to the sublimation point, mass ablation, and cloud disintegration have been investigated; afterwards, typical timescales of disintegration, sublimation and complete evaporation in reference to a graphite nanoparticle cloud (as an illustrative case) have been parametrically investigated. Based on a numerical analysis, an adequate parameter space describing the nanoparticle operation below the sublimation temperature, in terms of laser intensity, wavelength and nanoparticle material work function, has been identified. The cloud disintegration is found to be sensitive to the nanoparticle charging through photoemission; as a consequence, it illustrates that radiation operating below the photoemission threshold causes disintegration in the phase change state, while above the threshold, it occurs with the onset of surface heating.

  16. Single event upset threshold estimation based on local laser irradiation

    International Nuclear Information System (INIS)

    Chumakov, A.I.; Egorov, A.N.; Mavritsky, O.B.; Yanenko, A.V.

    1999-01-01

    An approach for estimation of ion-induced SEU threshold based on local laser irradiation is presented. Comparative experiment and software simulation research were performed at various pulse duration and spot size. Correlation of single event threshold LET to upset threshold laser energy under local irradiation was found. The computer analysis of local laser irradiation of IC structures was developed for SEU threshold LET estimation. The correlation of local laser threshold energy with SEU threshold LET was shown. Two estimation techniques were suggested. The first one is based on the determination of local laser threshold dose taking into account the relation of sensitive area to local irradiated area. The second technique uses the photocurrent peak value instead of this relation. The agreement between the predicted and experimental results demonstrates the applicability of this approach. (authors)

  17. FInal Technical Repot of the Project: Design and Implementation of Low-Power 10Gb/s/channel Laser/Silicon Photonics Modulator Drivers with SEU Tolerance for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gui, Ping [Southern Methodist Univ., Dallas, TX (United States)

    2017-08-09

    During the funding period of this award from May 1, 2014 through March 30, 2016, we have accomplished the design, implementation and measurement results of two laser driver chips: LpGBLD10+ which is a low-power single-channel 10Gb/s laser driver IC, and LDQ10P, which is a 4x10Gb/s driver array chip for High Energy Physics (HEP) applications. With new circuit techniques, the driver consumes a record-low power consumption, 31 mW @10Gb/s/channel and occupies a small area of 400 µm × 1750 µm for the single-channel driver IC and 1900umx1700um for the LDQ10P chip. These characteristics allow for both the LpGBLD10+ ICs and LDQ10P suitable candidate for the Versatile Link PLUS (VL+) project, offering flexibility in configuring multiple Transmitters and receivers.

  18. Effect of high-frequency near-infrared diode laser irradiation on periodontal tissues during experimental tooth movement in rats.

    Science.gov (United States)

    Gunji, Hidemi; Kunimatsu, Ryo; Tsuka, Yuji; Yoshimi, Yuki; Sumi, Keisuke; Awada, Tetsuya; Nakajima, Kengo; Kimura, Aya; Hiraki, Tomoka; Hirose, Naoto; Yanoshita, Makoto; Tanimoto, Kotaro

    2018-02-05

    Tooth movement during orthodontic treatment is associated with bone neoplasticity and bone resorption on the tension and pressure sides. Previous clinical studies have suggested that low-power laser irradiation can accelerate tooth movement during orthodontic treatment, although the underlying mechanism remains unclear. In this study, we used a high-frequency near-infrared diode laser that generates less heat and examined the histologic changes in periodontal tissue during experimental tooth movement with laser irradiation. A nickel-titanium closed coil was mounted between the maxillary left side first molar and incisor of rats to model experimental tooth movement. The laser-irradiation and the control groups were set, and the amount of movement of the first molar on 7th and 14th days after the start of pulling of the first molar tooth on the maxillary left was measured by three-dimensional analysis of µCT. After tooth movement, tissue samples from the mesial and tension sides were collected, and successive horizontal sections were prepared and examined using hematoxylin-eosin and TRAP staining and immunohistochemical staining for RANKL, OPG, ALP, and proliferating cell nuclear antigen (PCNA). Changes in tissue temperature following laser irradiation were also examined. Laser irradiation significantly increased tooth movement compared with non-irradiated controls. Histologic staining of the pressure-side mesial root in laser-irradiated rats revealed enhanced RANKL expression and increased numbers of TRAP-positive cells compared with controls. By contrast, on the tension side, laser irradiation led to increased expression of ALP and PCNA. These data indicate that high-frequency near-infrared diode laser irradiation on the pressure side upregulates RANKL expression and accelerates osteoclast differentiation, facilitating bone resorption, whereas bone formation is induced on the tension side. This study demonstrates that high-frequency near-infrared diode laser

  19. Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

    Energy Technology Data Exchange (ETDEWEB)

    Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

    2016-11-15

    Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

  20. Validity of reciprocity rule on mouse skin thermal damage due to CO2 laser irradiation

    Science.gov (United States)

    Parvin, P.; Dehghanpour, H. R.; Moghadam, M. S.; Daneshafrooz, V.

    2013-07-01

    CO2 laser (10.6 μm) is a well-known infrared coherent light source as a tool in surgery. At this wavelength there is a high absorbance coefficient (860 cm-1), because of vibration mode resonance of H2O molecules. Therefore, the majority of the irradiation energy is absorbed in the tissue and the temperature of the tissue rises as a function of power density and laser exposure duration. In this work, the tissue damage caused by CO2 laser (1-10 W, ˜40-400 W cm-2, 0.1-6 s) was measured using 30 mouse skin samples. Skin damage assessment was based on measurements of the depth of cut, mean diameter of the crater and the carbonized layer. The results show that tissue damage as assessed above parameters increased with laser fluence and saturated at 1000 J cm-2. Moreover, the damage effect due to high power density at short duration was not equivalent to that with low power density at longer irradiation time even though the energy delivered was identical. These results indicate the lack of validity of reciprocity (Bunsen-Roscoe) rule for the thermal damage.

  1. Low power arcjet performance

    Science.gov (United States)

    Curran, Francis M.; Sarmiento, Charles J.

    1990-01-01

    An experimental investigation was performed to evaluate arcjet operation at low power. A standard, 1 kW, constricted arcjet was run using nozzles with three different constrictor diameters. Each nozzle was run over a range of current and mass flow rates to explore stability and performance in the low power regime. A standard pulse-width modulated power processor was modified to accommodate the high operating voltages required under certain conditions. Stable, reliable operation at power levels below 0.5 kW was obtained at efficiencies between 30 and 40 percent. The operating range was found to be somewhat dependent on constrictor geometry at low mass flow rates. Quasi-periodic voltage fluctuations were observed at the low power end of the operating envelope. The nozzle insert geometry was found to have little effect on the performance of the device. The observed performance levels show that specific impulse levels above 350 seconds can be obtained at the 0.5 kW power level.

  2. Morphological and spectroscopic characterization of laser-ablated tungsten at various laser irradiances

    Energy Technology Data Exchange (ETDEWEB)

    Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Dawood, Asadullah [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Rafique, Muhammad Shahid [University of Engineering and Technology, Department of Physics, Lahore (Pakistan); Bashir, M.F. [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan)

    2015-06-15

    The variation in surface morphology and plasma parameters of laser irradiated tungsten has been investigated as a function of irradiance. For this purpose, Nd:YAG laser (1064 nm, 10 ns, 10 Hz) is employed. Tungsten targets were exposed to various laser irradiances ranging from 6 to 50 GW/cm{sup 2} under ambient environment of argon at a pressure of 20 Torr. Scanning electron microscope analysis has been performed to analyze the surface modification of irradiated tungsten. It revealed the formation of micro- and nanoscale surface structures. In central ablated area, distinct grains and crack formation are observed, whereas peripheral ablated areas are dominated by cones and pinhole formation. It was observed that at irradiances exceeding a value of 13 GW/cm{sup 2}, the morphological trend of the observed structures has been changed from erosion to melting and re-deposition dominant phase. Ablation efficiency as a function of laser irradiance has also been investigated by measuring the crater depth using surface profilometry analysis. It is found to be maximum at an irradiance of 13 GW/cm{sup 2} and decreases at high laser irradiances. In order to correlate the accumulated effects of plasma parameters with the surface modification, laser-induced breakdown spectroscopy analysis has been performed. The electron temperature and number density of tungsten plasma have been evaluated at various laser irradiances. Initially with the increase of the laser irradiance up to 13 GW/cm{sup 2}, an increasing trend is observed for both plasma parameters due to enhanced energy deposition. Afterward, a decreasing trend is achieved which is attributed to the shielding effect. With further increase in irradiance, a saturation stage comes and insignificant changes are observed in plasma parameters. This saturation is explainable on the basis of the formation of a self-regulating regime near the target surface. Surface modifications of laser irradiated tungsten have been correlated with

  3. First results of laser welding of neutron irradiated stainless steel

    International Nuclear Information System (INIS)

    Osch, E.V. van; Hulst, D.S. d'; Laan, J.G. van der.

    1994-10-01

    First results of experimental investigations on the laser reweldability of neutron irradiated material are reported. These experiments include the manufacture of 'heterogeneous' joints, which means joining of irradiated stainless steel of type AISI 316L-SPH to 'fresh' unirradiated material. The newly developed laser welding facility in the ECN Hot Cell Laboratory and experimental procedures are described. Visual inspections of welded joints are reported as well as results of electron microscopy and preliminary metallographic examinations. (orig.)

  4. Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

    Directory of Open Access Journals (Sweden)

    Qinghua Zhu

    2015-04-01

    Full Text Available The near-infrared (NIR absorption below band gap energy of crystalline silicon is significantly increased after the silicon is irradiated with femtosecond laser pulses at a simple experimental condition. The absorption increase in the NIR range primarily depends on the femtosecond laser pulse energy, pulse number, and pulse duration. The Raman spectroscopy analysis shows that after the laser irradiation, the silicon surface consists of silicon nanostructure and amorphous silicon. The femtosecond laser irradiation leads to the formation of a composite of nanocrystalline, amorphous, and the crystal silicon substrate surface with microstructures. The composite has an optical absorption enhancement at visible wavelengths as well as at NIR wavelength. The composite may be useful for an NIR detector, for example, for gas sensing because of its large surface area.

  5. Retrospective analysis of the treatment of melasma lesions exhibiting increased vascularity with the 595-nm pulsed dye laser combined with the 1927-nm fractional low-powered diode laser.

    Science.gov (United States)

    Geddes, Elizabeth R C; Stout, Ashlyn B; Friedman, Paul M

    2017-01-01

    Melasma presents a significant challenge to laser surgeons. Aggressive treatments often result in rebound melasma or post-inflammatory pigmentary alteration. Recent reports suggest melasma pathogenesis may have a vascular component. Spectrocolorimetry can detect subtle or sub-clinical telangiectatic erythema within melasma lesions. For certain patients identified by spectrocolorimetry, effective melasma treatment may include vascular-targeted therapy together with pigment-specific treatment modalities. Such combined therapies may reduce the likelihood of melasma recurrence. To evaluate the efficacy of treating melasma lesions exhibiting subtle or sub-clinical telangiectatic erythema with the 595-nm pulsed dye laser (PDL) combined with the 1927-nm fractional low-powered diode laser (FDL). A retrospective review was performed over a 2-year period as follows. Evaluated patients (n = 11) include 10 women and 1 man, average age of 38.7 years, and Fitzpatrick skin types II-IV. Each patient exhibited melasma lesions with subtle or sub-clinical telangiectatic erythema identified by spectrocolorimetry. Each underwent a series of treatments (average of four) at approximate 4-6 week intervals of the PDL followed by the FDL. Treatments were performed same-day, sequentially, with 10-15 minute interim time allowance for skin cooling. The following PDL parameters were utilized: 10 mm spot, 10-20 ms pulse duration, 7.5-8.5 J/cm 2 fluence, 30/30 DCD. Eight passes with the FDL (Clear + Brilliant ® Permea™, Solta Medical, Hayward, CA) were then performed utilizing a "low" treatment level. Clinical endpoint was mild erythema and edema. Patients were encouraged to practice strict photoprotection and apply topical skin lightening agents, but compliance was not measured. An independent physician evaluated photographs taken at baseline and at follow-up after last treatment session (average follow-up of 96 days). A quartile improvement score was used to grade the

  6. Using laser irradiation for the surgical treatment of periodontal disease

    Science.gov (United States)

    Vieru, Rozana D.; Lefter, Agafita; Herman, Sonia

    2002-10-01

    In the marginal pr ogressive profound periodontities, we associated low level laser therapy (LLLT) to the classical surgical treatment with implant of biovitroceramics. From a total of 50 patients, 37 where irradiated with the laser. We used a diode laser, =830 nm, energy density up to 2 J cm2, in Nogier pulsed mode. The laser treatment is used in a complex of therapeutic procedures: odontal, local anti-inflammatory -- as well as in the cabinet and at home --, prosthetic, and for the morphologic and functional rebalancing. The immediate effects where: an evolution without bleeding and without post-surgical complications, as can appear at the patients who didn't benefit of laser irradiation (hematom, pain, functional alteration in the first post-surgical week). Operated tissue is recovering faster. The percentage of recurrences decreases and the success depends less on the biological potential and the immunity of each individual.

  7. Communication: Mode bifurcation of droplet motion under stationary laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Takabatake, Fumi [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Department of Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8579 (Japan); Yoshikawa, Kenichi [Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394 (Japan); Ichikawa, Masatoshi, E-mail: ichi@scphys.kyoto-u.ac.jp [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)

    2014-08-07

    The self-propelled motion of a mm-sized oil droplet floating on water, induced by a local temperature gradient generated by CW laser irradiation is reported. The circular droplet exhibits two types of regular periodic motion, reciprocal and circular, around the laser spot under suitable laser power. With an increase in laser power, a mode bifurcation from rectilinear reciprocal motion to circular motion is caused. The essential aspects of this mode bifurcation are discussed in terms of spontaneous symmetry-breaking under temperature-induced interfacial instability, and are theoretically reproduced with simple coupled differential equations.

  8. 半导体激光治疗颞下颌关节滑膜炎的疗效评价%Efficacy of low-power laser therapy in treatment of painful arthrosynovitis of temporomandibular joint

    Institute of Scientific and Technical Information of China (English)

    周薇娜; 杜一飞; 张静露

    2015-01-01

    目的:探讨半导体激光疗法对颞下颌关节滑膜炎的临床疗效,为滑膜炎的治疗提供依据。方法选择确诊为颞下颌关节滑膜炎的患者60名,随机分成3组:激光治疗组、超短波治疗组、热敷组。采用疼痛直观模拟标尺(VAS)对治疗前后进行评分,并记录相应分值,测量最大张口度和最大前伸位移,进行治疗前后及组间比较。结果3种治疗方法均能够有效缓解颞下颌关节滑膜炎引起的关节区疼痛症状,改善张开口度。激光治疗组与超短波治疗组疗效均优于热敷治疗组,但前两组之间未见明显统计学差异。结论半导体激光治疗能够明显缓解颞下颌关节滑膜炎引起的关节的疼痛症状,并可以改善张口度,是一种可靠的临床无创治疗方法。%Objective To evaluate the effect of low-power laser therapy in treatment of painful arthrosynovitis of temporomandibular joint.Methods 60 patients with arthrosynovitis of temporomandibular joint were randomized into three groups:low-power laser thera-py,ultrashort wave and fomentation therapy.Scores of pain visual analog scale,the maximum of mandible open and protrusive position were recorded and analyzed.Results Pain of all patients was relieved after treatment in three groups.The effects of low-power laser,ul-trashort wave therapies were better than that of fomentation therapy.Conclusion Low-power laser therapy is a reliable clinical treat-ment for painful arthrosynovitis of temporomandibular joint.

  9. Improvement of laser irradiation uniformity in GEKKO XII glass laser system

    International Nuclear Information System (INIS)

    Miyanaga, Noriaki; Matsuoka, Shinichi; Ando, Akinobu; Amano, Shinji; Nakatsuka, Masahiro; Kanabe, Tadashi; Jitsuno, Takahisa; Nakai, Sadao

    1995-01-01

    The uniform laser irradiation is one of key issues in the direct drive laser fusion research. The several key technologies for the uniform laser irradiation are reported. This paper includes the uniformity performance as a result of the introduction of the random phase plate, the partially coherent light and the beam smoothing by spectral dispersion into the New Gekko XI glass laser system. Finally the authors summarize the overall irradiation uniformity on the spherical target surface by considering the power imbalance effect. The technologies developed for the beam smoothing and the power balance control enable them to achieve the irradiation nonuniformities of around 1% level for a foot pulse and of a few % for a main drive pulse, respectively

  10. Influence of powerful pulses of laser irradiation on metallic films

    International Nuclear Information System (INIS)

    Besogonov, V.V.; Chudinov, V.G.

    1999-01-01

    The relaxation process of energy transferred by powerful pulses of laser irradiation to a superficial layer in metallic films has been investigated by the molecular dynamics technique. Beam energy transformation into mechanical energy of movement of irradiated atoms is shown to be possible due to changing pair interaction potentials. Variation of the Coulomb interaction screening of an ionic subsystem through the excitation of valence electrons is illustrated as major of the reasons for changing the potentials

  11. Morphological changes in skin tumors caused by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Moskalik, K G; Lipova, V A; Neyshtadt, E L

    1979-01-01

    Morphological changes induced by treating melanomas, basaloma and flatcell skin cancers with a pulsed neodymium laser at 1060 nm, pulse length 1 msec and energy 250 to 500 J/cm/sup 2/, were studied using impressions and scrapings from the affected area. Nuclear pyknosis, nuclear and cellular elongation, vacuolization, frequent complete loss of cytoplasm, particulaly in the zone of direct irradiation, and loss of cellular structure were seen. These dystrophic changes increased with closeness to the zone of direct irradiation, culminating in necrosis. Formed and decomposed blood elements and melanin accumulated in the intracellular spaces, due to disruption of capillaries and small arteries and veins. Fewer and more aggregated melanoblasts were found after melanoma irradiation. Nuclear chromatin fusion, cytoplasmic changes and altered cell shape were observed. Basaloma cells were clustered and elongated after irradiation, with many fibrous structures and loss of cellular elements. Cytoplasmic vacuolization and lysis, bare nuclei, karyolysis, karyorrhexis and karyopyknosis were seen in corneous flat-cell cancer. In the few cases in which malignant cells were found under the scab from the first treatment the procedure was repeated. The morphological changes induced by pulsed laser irradiation are very similar to electrocoagulation necrosis, but are more localized. The ability of low and middle energy lasers to induce thrombosis and coagulation in vascular walls reduced the probability of hematogenic tumor cell dissemination. Cytological examination is highly effective in determining the degree of radical skin cancer healing due to laser treatment. 12 references, 2 figures.

  12. Closure phenomena in pinholes irradiated by Nd laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Auerbach, J.M.; Holmes, N.C.; Hunt, J.T.; Linford, G.J.

    1979-07-15

    An experimental investigation has been made on plasma closure in pinholes irradiated by Nd glass laser pulses; 300--500-..mu..m diam pinholes of various materials and thicknesses have been irradiated by 20--100-J 300-psec FWHM pulses on the Janus laser system. Calorimetry measurements have yielded data on pinhole energy transmission and intensity loading on the periphery of the pinhole. Ultrafast streak photography measurements indicate effective closure velocities of 2--5 x 10/sup 7/ cm/sec. Scattered light measurements have shown the transmission loss through a typical spatial filter configuration to be primarily refractive in nature.

  13. Pulse laser irradiation into superconducting MgB2 detector

    International Nuclear Information System (INIS)

    Fujiwara, Daisuke; Miki, Shigehito; Satoh, Kazuo; Yotsuya, Tsutomu; Shimakage, Hisashi; Wang, Zhen; Okayasu, Satoru; Katagiri, Masaki; Machida, Masahiko; Kato, Masaru; Ishida, Takekazu

    2005-01-01

    We performed 20-ps pulse laser irradiation experiments on a MgB 2 neutron detector to know a thermal-relaxation process for designing a MgB 2 neutron detector. The membrane-type structured MgB 2 device was fabricated to minimize the heat capacity of sensing part of a detector as well as to enhance its sensitivity. We successfully observed a thermal-relaxation signal resulting from pulse laser irradiation by developing a detection circuit. The response time was faster than 1 μs, meaning that the detector would be capable of counting neutrons at a rate of more than 10 6 events per second

  14. Laser effects on graphene oxide irradiated in high vacuum

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Silipigni, L.; Cutroneo, Mariapompea

    2018-01-01

    Roč. 173, 1-2 (2018), s. 73-84 ISSN 1042-0150 R&D Projects: GA MŠk LM2015056; GA ČR GA16-05167S Institutional support: RVO:61389005 Keywords : graphene oxide * laser irradiation * laser-generated plasma * radiation effects Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 0.443, year: 2016

  15. In vivo PIXE-PIGE study of enhanced retention of fluorine in tooth enamel after laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Demortier, Guy [Department of Physics, University of Namur, 61, rue de Bruxelles, B5000 Namur (Belgium)], E-mail: guy.demortier@tvcablenet.be; Nammour, Samir [Faculty of Medicine, University of Liege, 8, rue Paul Spaak, B-1000 Bruxelles (Belgium)

    2008-05-15

    The presence of fluoride in tooth enamel reduces the solubility of hydroxylapatite by acid attack. Fluoride presence (even at low concentration) in the oral cavity is efficient against caries process. We propose a new approach of the explanation of the increase of fluoride retention in the tooth enamel when low power laser irradiation is applied after the treatment with fluoride gel (fluoridation). External beam PIGE measurements of fluorine on extracted teeth have been made in order to determine the best sequence of the operations. The laser irradiation after fluoride application is more efficient than the reverse procedure. This observation is in agreement with previous observations that the fluorine penetration in the enamel takes place first in the soft organic material present between the polycrystalline (prismatic) structure before being integrated in the crystalline composition of hydroxylapatite in order to produce fluoro-apatite. As those in vitro measurements do not reflect the whole process in the saliva, in vivo PIGE measurements have been also performed. We have demonstrated, by repeating the PIGE measurements (at least five times at various time intervals) that a significant increase of the fluoride retention took place even 18 months after the unique laser treatment. The complete experimental procedure is described: fluoride application, laser irradiation, PIGE measurements with 2.7 MeV protons (repeated measurements at the same place on the same tooth in order to follow the evolution) and safety tests before in vivo analyses.

  16. Towards a laser fluence dependent nanostructuring of thin Au films on Si by nanosecond laser irradiation

    International Nuclear Information System (INIS)

    Ruffino, F.; Pugliara, A.; Carria, E.; Romano, L.; Bongiorno, C.; Fisicaro, G.; La Magna, A.; Spinella, C.; Grimaldi, M.G.

    2012-01-01

    Highlights: ► Au nanoclusters are produced by nanosecond laser irradiations of thin Au film on Si. ► The shape, size, and surface density of the Au nanoclusters are tunable by laser fluence. ► The formation dynamic of the Au nanoclusters under nanosecond laser irradiation is analyzed. - Abstract: In this work, we study the nanostructuring effects of nanosecond laser irradiations on 5 nm thick Au film sputter-deposited on Si. After deposition of Au on Si substrate, nanosecond laser irradiations were performed increasing the laser fluence from 750 to 1500 mJ/cm 2 . Several analyses techniques, such as Rutherford backscattering spectrometry, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy were crossed to study the morphological evolution of the Au film as a function of laser fluence. In particular, the formation of Au nanoparticles was observed. The analyses allowed a quantitative evaluation of the evolution of the nanoparticles size, surface density, and shape as a function of the laser fluence. Therefore, a control the structural properties of the Au nanoparticles is reached, for example, for applications in Si nanowires growth or plasmonics.

  17. Effect of maize seed laser irradiation on plant photosynthetic activity

    International Nuclear Information System (INIS)

    Antonov, M.; Stanev, V.; Velichkov, D.; Tsonev, Ts.

    1986-01-01

    Investigations were made with the two hybrids, H-708 and P x -20. The seeds were irradiated by a helium-neon quantum generator (L'vov-1 Electronica) with output power of 24 MW and 632.8 nm wave length. Once and twice irradiated seeds were sown on the 2nd, 5th and 10th day post irradiation. Changes in leaf area, chlorophyll content in the leaves, photosynthetic rate and its dependence on temperature and light, transpiration, stomatal resistance to CO 2 and total dry matter of the overground plant part were traced. Seed irradiation with laser rays did not affect the chlorophyll content of the leaves. The photosynthetic rate did not depend on the cultivar characteristics of the crop. Single and repeated irradiation of the hybrid H-708 in most case enhanced photosynthetic rate, but a similar effect was not observed in P x -20. Transpiration and CO 2 stomatal resistance were not equally affected by radiation. Laser rays enhanced the ability of the photosynthetic apparatus of the entire plants to use more efficiently high light intensities. The leaf area and the total plant dry matter increased in case of sowing on the 2nd and 5th day and a single irradiation and in case of sowing on the 5th and 10th day and twice repeated irradiations

  18. Optothermal transfer simulation in laser-irradiated human dentin.

    Science.gov (United States)

    Moriyama, Eduardo H; Zangaro, Renato A; Lobo, Paulo D C; Villaverde, Antonio Balbin; Pacheco, Marcos T; Watanabe, Ii-Sei; Vitkin, Alex

    2003-04-01

    Laser technology has been studied as a potential replacement to the conventional dental drill. However, to prevent pulpal cell damage, information related to the safety parameters using high-power lasers in oral mineralized tissues is needed. In this study, the heat distribution profiles at the surface and subsurface regions of human dentine samples irradiated with a Nd:YAG laser were simulated using Crank-Nicolson's finite difference method for different laser energies and pulse durations. Heat distribution throughout the dentin layer, from the external dentin surface to the pulp chamber wall, were calculated in each case, to investigate the details of pulsed laser-hard dental tissue interactions. The results showed that the final temperature at the pulp chamber wall and at the dentin surface are strongly dependent on the pulse duration, exposure time, and the energy contained in each pulse.

  19. Parameter optimization for steel quenching by C02-laser irradiation

    International Nuclear Information System (INIS)

    Moryashchev, S.F.; Kislitsyn, A.A.; Kosyrev, F.K.

    1984-01-01

    The dependence of average absorption factor on maximal temperature of the article surface during quenching by CO 2 -laser irradiation was determined empirically. The calculations of depth of a hardening zone and process productivity in 40 Kh, 4Kh13 steels and Armco-iron with regard to this dependence were conducted

  20. Petawatt laser and target irradiation system at LLNL

    International Nuclear Information System (INIS)

    Pennington, D.M.; Perry, M.D.; Britten, J.A.; Brown, C.G.; Herman, S.; Homer, J.; Miller, J.L.; Stuart, B.C.; Tietbohl, G.; Van Lue, J.; Yanovsky, V.

    1997-01-01

    In May, 1996, we demonstrated the production over a petawatt of peak power in the Nova/Petawatt Laser Facility, generating 620 J in ∼ 430 fs. Results of the first focused irradiance tests, and recent deployment of a novel targeting system will be presented

  1. Regrowth of Si and Ge under laser irradiation

    International Nuclear Information System (INIS)

    Bertolotti, M.; Vitali, G.

    1979-01-01

    The effects of pulsed laser irradiation on amorphous layers of Si and Ge obtained via ion implantation are considered. Amorphous-polycrystalline, amorphous-single crystal and polycrystalline-single crystal transitions have been obtained. Residual disorder and mechanical damage are considered. (author)

  2. Bactericidal effect of Nd:YAG laser irradiation in endodontics

    Science.gov (United States)

    Aun, Carlos E.; Barberini, Alexandre F.; Camargo, Selma C. C.; Silva Kfouri, Luciana; Lorenzetti Simionato, Maria R.

    1999-05-01

    The success of endodontic therapy is based on the elimination of bacterial colonization from the endodontic system and periapical tissues. Recent studies have been showing the bactericidal effect of laser in root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canals from upper central incisor. For the experiment 12 teeth were selected, respect at the apical third, sterilized, and 10 μm Streptococcus sanguis liquid culture were inoculated in the root canals. The laser test groups were irradiated with Nd:YAG laser at standard setting of 15Hz, 100mj and 1,5 W for 10, 20 and 30 seconds each in slow helicoidal movements from the apex to the top using a 300 micrometers fiber. After the procedure the specimens were placed in Tryptic Soy Agar, the number of colony forming units was evaluated. The experiment showed a significant reduction on viability of Streptococcus sanguis at the respective time of 20 and 30 seconds.

  3. Particle velocity measurements in laser irradiated foils using ORVIS

    International Nuclear Information System (INIS)

    Sheffield, S.A.; Fisk, G.A.

    1983-01-01

    Aluminum foils from 2- to 200-μm thick have been subjected to a Nd:YAG laser pulse of low irradiance (10 9 W/cm 2 , approx. 10 ns pulse) to produce laser-driven shocks in the foils. The particle velocity history of the foil side opposite the laser deposition was monitored with nanosecond resolution by a velocity interferometer system called ORVIS. These histories indicate a shock reverberation process accelerates the foil. Peak foil velocities can be adequately calculated using a ricket propulsion model developed from experiments at much higher irradiances. A velocity of 1 km/s was developed in a 2-μm-thick free foil in a time of 50 ns. Water-confined foils attained peak particle velocities about three times higher than those of free foils

  4. Optical-Thermal Response of Laser-Irradiated Tissue

    CERN Document Server

    Welch, Ashley J

    2011-01-01

    The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

  5. Segmental irradiation of the bladder with neodymium YAG laser irradiation

    International Nuclear Information System (INIS)

    McPhee, M.S.; Mador, D.R.; Tulip, J.; Ritchie, B.; Moore, R.; Lakey, W.H.

    1982-01-01

    The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma

  6. Effects of surface shape on the geometry and surface topography of the melt pool in low-power density laser melting

    KAUST Repository

    Kim, Youngdeuk

    2011-04-15

    The quantitative correlations between workpiece volume and melt pool geometry, as well as the flow and thermal features of the melt pool are established. Thermocapillary convections in melt pool with a deformable free surface are investigated with respect to surface shape and laser intensity. When the contact angle between the tangent to the top surface and the vertical wall at the hot center is acute, the free surface flattens, compared with that of the initial free surface. Otherwise, the free surface forms a bowl-like shape with a deep crater and a low peripheral rim when the contact angle at the hot center is obtuse. Increasing the workpiece volume at a fixed laser intensity and a negative radial height gradient cause linear decreases in the geometric size and magnitude of flow and temperature of the melt pool. Conversely, linear increases are observed with a positive radial height gradient. © 2011 American Institute of Chemical Engineers (AIChE).

  7. Physical and Chemical Changes of Polystyrene Nanospheres Irradiated with Laser

    International Nuclear Information System (INIS)

    Mustafa, Mohd Ubaidillah; Juremi, Nor Rashidah Md.; Mohamad, Farizan; Wibawa, Pratama Jujur; Agam, Mohd Arif; Ali, Ahmad Hadi

    2011-01-01

    It has been reported that polymer resist such as PMMA (Poly(methyl methacrylate) which is a well known and commonly used polymer resist for fabrication of electronic devices can show zwitter characteristic due to over exposure to electron beam radiation. Overexposed PMMA tend to changes their molecular structure to either become negative or positive resist corresponded to electron beam irradiation doses. These characteristic was due to crosslinking and scissors of the PMMA molecular structures, but till now the understanding of crosslinking and scissors of the polymer resist molecular structure due to electron beam exposure were still unknown to researchers. Previously we have over exposed polystyrene nanospheres to various radiation sources, such as electron beam, solar radiation and laser, which is another compound that can act as polymer resist. We investigated the physical and chemical structures of the irradiated polystyrene nanospheres with FTIR analysis. It is found that the physical and chemical changes of the irradiated polystyrene were found to be corresponded with the radiation dosages. Later, combining Laser irradiation and Reactive Ion Etching manipulation, created a facile technique that we called as LARIEA NSL (Laser and Reactive Ion Etching Assisted Nanosphere Lithography) which can be a facile technique to fabricate controllable carbonaceous nanoparticles for applications such as lithographic mask, catalysts and heavy metal absorbers.

  8. Over-expression of CXCR4, a stemness enhancer, in human blastocysts by low level laser irradiation

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Tahmasbi

    2013-09-01

    Full Text Available The key role of chemokine receptor CXCR4 in the maintenance of stemness property of stem cells has been shown recently. The low level laser irradiation (LLLI is being used currently in a wide variety of clinical cases as a therapeutic tool for wound healing, relieving pain and destroying tumor cells. The aim of this study was to evaluate the effect of LLLI mimicking low level laser therapy (LLLT on the expression level of CXCR4 gene a few hours after irradiation on human blastocysts. After the development of human embryos to the first grade blastocyst stage, they were irradiated with a low power Ga-Al-As laser at a continuous wavelength of 650 nm and a power output of 30 mW. The total RNA of the irradiated blastocysts and control groups were isolated in groups of 1x2 J/cm2, 2x2 J/cm2, 1x4 J/cm2 and 2x4 J/cm2 LLLI. Specific Real-Time PCR primers were designed to amplify all the two CXCR4 isoforms yet identified. RNA amplifications were done for all the groups. We showed for the first time that LLLI makes the human blastocysts to increase the expression level of CXCR4 a few hours after irradiation. Moreover, it was shown that two irradiation doses with one day interval can cause a significant increase in CXCR4 expression level in human blastocysts. This study revealed that LLLI could be a proliferation motivator for embryonic cell divisions through enhanced over-expression of CXCR4 level.

  9. Biofilms and their modifications by laser irradiation

    International Nuclear Information System (INIS)

    Richter, Asta; Gonpot, Preethee; Smith, Roger

    2001-01-01

    Biofilms are grown on different materials with various surface morphology and are investigated by light and scanning force microscopy. The growth patterns, coverage and adherence of the biofilm are shown to depend on the type of the substrate and its roughness as well as on the type of micro-organisms. Here we present investigations of Eschericia coli bacterial biofilms grown on the polymer material polyetheretherketone and also on titanium films on glass substrates. A Monte Carlo simulation of the growth process is developed which takes into account the aspect ratio of the micro-organisms and the diffusion of nutrient over the surface to feed them. A pulsed nitrogen laser has been applied to the samples and the interaction of the laser beam with the biofilm and the underlying substrate has been studied. Because of the inhomogeneity of the biofilms the ablated areas are different. With increasing number of laser pulses more biofilm material is removed but there appears also damage of the substrate. The threshold energy fluence for the biofilm ablation is estimated and depends on the sticking power of the bacteria. Ablation rates for the removal of the biofilms are also obtained

  10. Effects of Er:YAG laser irradiation on human cartilage

    Science.gov (United States)

    Glinkowski, Wojciech; Brzozowska, Malgorzata; Ciszek, Bogdan; Rowinski, Jan; Strek, Wieslaw

    1996-03-01

    Irradiation of the hyaline or fibrous cartilage excised from the body of a human cadaver with Er:YAG laser beam, single pulse with a dose of 1 J, produces a crater with a depth of approximately 500 micrometers and a diameter varying from 5 to 300 micrometers. Histological examination has revealed that the laser-made craters were surrounded by a thin rim (2-10 micrometer) of charred and coagulated tissue. No damage was observed in the cartilage surrounding the rim. The presence of sharp demarcation between the tissue areas ablated by laser energy and the undamaged areas argues for the potential usefulness of the Er:YAG laser in surgery of cartilages.

  11. Low power constant fraction discriminator

    International Nuclear Information System (INIS)

    Krishnan, Shanti; Raut, S.M.; Mukhopadhyay, P.K.

    2001-01-01

    This paper describes the design of a low power ultrafast constant fraction discriminator, which significantly reduces the power consumption. A conventional fast discriminator consumes about 1250 MW of power whereas this low power version consumes about 440 MW. In a multi detector system, where the number of discriminators is very large, reduction of power is of utmost importance. This low power discriminator is being designed for GRACE (Gamma Ray Atmospheric Cerenkov Experiments) telescope where 1000 channels of discriminators are required. A novel method of decreasing power consumption has been described. (author)

  12. Thermal Changes of Maize Seed by Laser Irradiation

    Science.gov (United States)

    Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.

    2015-09-01

    In this research, the thermal evolution in maize seeds ( Zea mays L.) was studied when low-intensity laser irradiation was applied during 60 s. The seeds were irradiated in three different conditions: suspended in air, placed on an aluminum surface, and finally placed on a cardboard; the evolution of the seed temperature was measured by an infrared camera. Photoacoustic spectroscopy and the Rosencwaig and Gersho model were used to determine the optical absorption coefficient (β ) of the seeds. The results indicate that using 650 nm laser light and 27.4 mW, it is possible to produce temperature changes (up to 9.06°C after 1 min) on the seeds. Comparing the mean temperature of the seeds, during and after the incidence of light from a laser, it was found that there were statistically significant differences (P≤ 0.05) from time t1 to time t_{16} (t1 to t_{16}) and t3 to t_{16}, for the laser turned on and off, respectively. The seed condition that had the highest temperature variation, relative to the initial temperature (during the irradiation laser exposure), involved the seeds suspended in air. With regard to the stage of decay of the temperature, it was found that the seed condition that decays more slowly was the seed placed on the cardboard. It was also found that black-dyed maize seeds are optically opaque in the 300 nm to 700 nm range Also, the thermal diffusion length is smaller than the optical penetration length. In the present investigation, it was shown that there is a thermal component associated with the mechanisms of laser biostimulation, which is also a function of the container materials of the seed. In this way, the effects of laser treatment on maize seeds involve at least a temperature effect. It is important to know the temperature changes in the seeds that have been irradiated with a laser beam since they could have substantial practical and theoretical importance.

  13. Diffuse scattering from laser-irradiated plane targets

    International Nuclear Information System (INIS)

    Kessel, C.G.M. van; Olsen, J.N.; Sachsenmaier, P.; Sigel, R.; Eidmann, K.; Godwin, R.P.

    1976-11-01

    Optical calorimetry of the laser radiation scattered from plane targets irradiated by 0.3 Joule/30 ps Nd-laser pulses with intensities up to 10 16 W cm -2 has been performed with an emphasis on diffuse scattering. Diffuse scattering outside the solid angle of the focusing lens is found to be a major reflection loss from the target. A fraction of 0.3 to 0.5 of the incident pulse energy was absorbed in the target with only a very weak dependence on pulse energy and target material. (orig.) [de

  14. LPI studies with grazing incidence irradiation at the Nike laser

    Science.gov (United States)

    Weaver, J.; Kehne, D.; Schmitt, A.; Obenschain, S.; Serlin, V.; Oh, J.; Lehmberg, R.; Seely, J.

    2013-10-01

    Studies of laser plasma instabilities (LPI) at the Nike laser facility at NRL have previously concentrated on planar targets irradiated with their surface normal aligned to the central axis of the laser. Shots with planar targets rotated up 60° to the laser have shown changes in thresholds for the two-plasmon decay instability and stimulated Raman scattering near the quarter critical region. In the case of rotated low-Z targets, spectra were observed to shift to lower wavelength and were substantially stronger in the visible and ultraviolet spectral ranges. The low-Z target data show growth at an incident intensity slightly below (~30%) the threshold values observed at normal incidence. A rapid rise in signal level over the same laser intensities was also observed in the hard x-ray data which serve as an overall indicator of LPI activity. Shots with rotated planar high-Z targets showed that the visible and ultraviolet emissions dropped significantly when compared to low-Z targets in the same geometry. This presentation will include results from upcoming experiments to determine the LPI signal for low-Z, high-Z, and high-Z coated targets at lower laser intensities for several angles of target rotation. Shots with widely separated laser beams are also planned to explore cross beam energy transport at Nike. Work supported by DoE/NNSA.

  15. Effect Of Laser Irradiation On Biosynthesis Of Antibiotics

    International Nuclear Information System (INIS)

    SALAMA, S.M.; MAHMOUD, S.M.; EL-KABBANY, H.M.

    2010-01-01

    An investigation concerning the effect of He:Ne laser irradiation on some isolated actinomycetes was carried out. Seven isolated actinomycetes were considered as most potent producing broad spectrum antibiotics. The strains have been identified on the basis of taxonomic studies as Streptomyces nogalator (H12), Streptomyces griseoluteus (YM23), Amycolatopsis mediterranei (B40), Glycomyces harbinensis (KA16), Streptosporangium corrugatum (B67), Streptoalloteichus hindustamus (B74) and Streptomyces aurantiogriseus (S15). Seven genotypes were chosen after He:Ne laser irradiation as representative for each isolated strain. The active metabolite from most potent genotype of Streptomyces nogalator (H12) was extracted by ethyl acetate then concentrated under vacuo and the crude fraction was purified using thin layer and column chromatography. Ultra violet maximum absorption peak was recorded at 231.5 and 206 nm. The IR and NMR were consulted to confirm the chemical characteristics of the antibiotic. The biological activity and toxicity were also investigated.

  16. Research on interaction of laser light and non-metals. Evaluation of laser irradiation behavior to concrete

    International Nuclear Information System (INIS)

    Yamada, Tomonori; Muramatsu, Toshiharu

    2015-02-01

    In this study the response of hardened cement pastes, which are a major component of concrete, to laser irradiation was investigated under various experimental conditions aiming at the future application to “laser-processing” of concrete. (1) 75 tests were performed with combinations of following experimental conditions: (a) a water/cement ratio of the hardened cement pastes was either of 0.25, 0.30, or 0.35; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 1 to 40 seconds. It was found that hardened cement paste subjected to laser irradiation explodes very easily to be hollowed in all the experimental conditions; this response is applicable to “laser-drilling” of a hardened cement paste. The “laser-drilling” speeds up following to laser power increment or to irradiation time extension. It was also found that samples tend to melt rather than explode under the irradiation with a smaller laser power density (100 W/cm 2 ) at a high water/cement ratio (0.35). (2) Totally 75 laser irradiation tests for fixed mortar blocks were performed with combinations of following experimental conditions: (a) fine aggregate in the mortar blocks was either of quartz, limestone, or Nachiguro-ishi; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 0.2 to 40 seconds. Although it was found that all kinds of the mortar fuse under laser irradiation after all, difference in the response to laser irradiation among the mortars was also found; energy density required to fuse the mortar including limestone was larger than that required to fuse the mortar including quartz or Nachiguro-ishi. (author)

  17. Toxicity of laser irradiated photoactive fluoride PrF3 nanoparticles toward bacteria

    International Nuclear Information System (INIS)

    Pudovkin, M S; Korableva, S L; Krasheninnicova, A O; Nizamutdinov, A S; Semashko, V V; Zelenihin, P V; Alakshin, E M; Nevzorova, T A

    2014-01-01

    The article is devoted to exploration of biological effects of crystalline PrF 3 nanoparticles toward Salmonella typhimurium TA 98 bacteria under the laser irradiation. Obtained results show bactericidal activity of PrF 3 nanoparticles and optimal parameters of laser irradiation (power of laser irradiation, wavelength, diameter of the laser spoil, and exposure time) have been found under which the effects of bactericidal activity become the most significant. Survival of bacterial cells under laser irradiation with wavelength 532 nm in colloidal solution of PrF 3 nanoparticles was 39%, 34%, 20% for exposure times 5 minutes, 15 minutes and 30 minutes, correspondingly

  18. Chalcogen doping of silicon via intense femtosecond-laser irradiation

    International Nuclear Information System (INIS)

    Sheehy, Michael A.; Tull, Brian R.; Friend, Cynthia M.; Mazur, Eric

    2007-01-01

    We have previously shown that doping silicon with sulfur via femtosecond-laser irradiation leads to near-unity absorption of radiation from ultraviolet wavelengths to below band gap short-wave infrared wavelengths. Here, we demonstrate that doping silicon with two other group VI elements (chalcogens), selenium and tellurium, also leads to near-unity broadband absorption. A powder of the chalcogen dopant is spread on the silicon substrate and irradiated with femtosecond-laser pulses. We examine and compare the resulting morphology, optical properties, and chemical composition for each chalcogen-doped substrate before and after thermal annealing. Thermal annealing reduces the absorption of below band gap radiation by an amount that correlates with the diffusivity of the chalcogen dopant used to make the sample. We propose a mechanism for the absorption of below band gap radiation based on defects in the lattice brought about by the femtosecond-laser irradiation and the presence of a supersaturated concentration of chalcogen dopant atoms. The selenium and tellurium doped samples show particular promise for use in infrared photodetectors as they retain most of their infrared absorptance even after thermal annealing-a necessary step in many semiconductor device manufacturing processes

  19. Thermal shock testing of ceramics with pulsed laser irradiation

    International Nuclear Information System (INIS)

    Benz, R.; Naoumidis, A.; Nickel, H.

    1986-04-01

    Arguments are presented showing that the resistance to thermal stressing (''thermal shock'') under pulsed thermal energy deposition by various kinds of beam irradiations is approximately proportional to Φ a √tp, where Φ a is the absorbed power density and tp is the pulse length, under conditions of diffusivity controlled spreading of heat. In practical beam irradiation testing, incident power density, Φ, is reported. To evaluate the usefulness of Φ√tp as an approximation to Φ a √tp, damage threshold values are reviewed for different kinds of beams (electron, proton, and laser) for a range of tp values 5x10 -6 to 2 s. Ruby laser beam irradiation tests were made on the following ceramics: AlN, BN, graphite, αSiC, β-SiC coated graphites, (α+β)Si 3 N 4 , CVD (chemical vapor deposition) TiC coated graphite, CVD TiC coated Mo, and CVD TiN coated IN 625. The identified failure mechanisms are: 1. plastic flow followed by tensile and bend fracturing, 2. chemical decomposition, 3. melting, and 4. loss by thermal spallation. In view of the theoretical approximations and the neglect of reflection losses there is reasonable accord between the damage threshold Φ√tp values from the laser, electron, and proton beam tests. (orig./IHOE)

  20. Physiological characteristics of cucumber seed production plants by presowing laser and gamma irradiation

    International Nuclear Information System (INIS)

    Cholakov, D.; Petkova, V.

    1994-01-01

    Seeds from G-3 maternal line of hybrid cucumber cultivar Pobeda F 1 were treated with helium-neon 632.8 nm laser-exit power 20 mW and gamma-rays ( 60 Co) in a field experiment under conditions suitable for hybrid seed production. The irradiation was carried out a week before sowing and the following variants were investigated: 1. sevenfold laser irradiation; 2. 10 Gy gamma irradiation; 3. combined laser + gamma rays irradiation. Seeds from the parent line were not irradiated. A positive effect of irradiation on the photosynthetic intensity, content of plastid pigments in leaves and activity of catalase and peroxidase has been observed. (author)

  1. Activity of respiratory system during laser irradiation of brain structures

    Science.gov (United States)

    Merkulova, N. A.; Sergeyeva, L. I.

    1984-06-01

    The performance of one of the principal links of the respiratory system, the respiratory center, was studied as a function of the exposure of the medulla oblongata and the sensomotor zone of the cerebral hemisphere cortex to low level laser irradiation in the red wavelength of the spectrum. Experiments were done on white rats under barbital anesthesia. Under such conditions a substantial effect was observed on the activity of the respiratory center. Laser light may display activating or inhibitory influences, in some cases the bilateral symmetry of the activity of the respiratory center is affected indicating deep changes in the integrative mechanism of the functioning of the right and left sides of the hemispheres. The laser beam effect depends on many factors: specific light properties, duration of the exposure, repetition of exposures, initial functional state of the CNS, etc.

  2. High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

    Science.gov (United States)

    Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

    2010-03-01

    A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

  3. Protocol of irradiation laser of low-power conditions fluence (energy density) controlled; Protocolo de irradiacion laser de baja potencia en condiciones de fluencia (densidad de energia) controlada

    Energy Technology Data Exchange (ETDEWEB)

    Romero, C.; Gil-Benso, R.; Perez-Montoyo, H.; Cibrian, R.; Salvador, R.; Gonzalez-Pena, R.; Dalmases, F.

    2013-07-01

    The Assembly and proposed Protocol reveal themselves fully indicated for this type of in vitro studies, allowing to establish, in a much safer manner, the doses of radiation received almost evenly by the analyzed culture. (Author)

  4. Realization of double-pulse laser irradiating scheme for laser ion sources

    International Nuclear Information System (INIS)

    Li Zhangmin; Jin Qianyu; Liu Wei; Zhang Junjie; Sha Shan; Zhao Huanyu; Sun Liangting; Zhang Xuezhen; Zhao Hongwei

    2015-01-01

    A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd : YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3 : 8 to 8 : 3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies. (authors)

  5. Laser ablation of liquid surface in air induced by laser irradiation through liquid medium

    Science.gov (United States)

    Utsunomiya, Yuji; Kajiwara, Takashi; Nishiyama, Takashi; Nagayama, Kunihito; Kubota, Shiro; Nakahara, Motonao

    2010-10-01

    The pulse laser ablation of a liquid surface in air when induced by laser irradiation through a liquid medium has been experimentally investigated. A supersonic liquid jet is observed at the liquid-air interface. The liquid surface layer is driven by a plasma plume that is produced by laser ablation at the layer, resulting in a liquid jet. This phenomenon occurs only when an Nd:YAG laser pulse (wavelength: 1064 nm) is focused from the liquid onto air at a low fluence of 20 J/cm2. In this case, as Fresnel’s law shows, the incident and reflected electric fields near the liquid surface layer are superposed constructively. In contrast, when the incident laser is focused from air onto the liquid, a liquid jet is produced only at an extremely high fluence, several times larger than that in the former case. The similarities and differences in the liquid jets and atomization processes are studied for several liquid samples, including water, ethanol, and vacuum oil. The laser ablation of the liquid surface is found to depend on the incident laser energy and laser fluence. A pulse laser light source and high-resolution film are required to observe the detailed structure of a liquid jet.

  6. Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

    International Nuclear Information System (INIS)

    Khachatrian, Ani; Dagdigian, Paul J.

    2010-01-01

    An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

  7. Low-power wind plants

    International Nuclear Information System (INIS)

    Kovalenko, V.I.; Shevchenko, Yu.V.; Shikhajlov, N.A.; Kokhanevich, V.P.; Tanan, G.L.

    1993-01-01

    Design peculiarities, as well as the prospects of development and introduction of the low-power (from 0.5 up to 4 kW) wind power plants (WPP) are considered. The variants of WPP with vertical and horizontal rotation axis are described. The data characterizing cost and structure of expenditures on WPP manufacture and operation are given

  8. The osmotic fragility of human erythrocytes is inhibited by laser irradiation

    International Nuclear Information System (INIS)

    Habodaszova, D.; Sikurova, L.; Waczulikova, I.

    2004-01-01

    In this study we investigated the influence of green laser irradiation (532 nm, 30 mW, 31,7 J/cm 2 ) on the membrane integrity of human erythrocytes and compared the results with the effect of infrared laser irradiation (810 nm, 50 mW, 31,3 J/cm 2 ). To evaluate the membrane integrity of erythrocytes, one clinical parameter, the osmotic fragility, was investigated. We observed a decrease in osmotic fragility of the erythrocytes after irradiation by the green laser light as well as by the infrared laser compared to non-irradiated controls (Authors)

  9. Research on temperature characteristics of laser energy meter absorber irradiated by ms magnitude long pulse laser

    Science.gov (United States)

    Li, Nan; Qiao, Chunhong; Fan, Chengyu; Zhang, Jinghui; Yang, Gaochao

    2017-10-01

    The research on temperature characteristics for large-energy laser energy meter absorber is about continuous wave (CW) laser before. For the measuring requirements of millisecond magnitude long pulse laser energy, the temperature characteristics for absorber are numerically calculated and analyzed. In calculation, the temperature field distributions are described by heat conduction equations, and the metal cylinder cavity is used for absorber model. The results show that, the temperature of absorber inwall appears periodic oscillation with pulse structure, the oscillation period and amplitude respectively relate to the pulse repetition frequency and single pulse energy. With the wall deep increasing, the oscillation amplitude decreases rapidly. The temperature of absorber outerwall is without periodism, and rises gradually with time. The factors to affect the temperature rise of absorber are single pulse energy, pulse width and repetition frequency. When the laser irradiation stops, the temperature between absorber inwall and outerwall will reach agreement rapidly. After special technology processing to enhance the capacity of resisting laser damage for absorber inwall, the ms magnitude long pulse laser energy can be obtained with the method of measuring the temperature of absorber outerwall. Meanwhile, by optimization design of absorber structure, when the repetition frequency of ms magnitude pulse laser is less than 10Hz, the energy of every pulse for low repetition frequency pulse sequence can be measured. The work offers valuable references for the design of ms magnitude large-energy pulse laser energy meter.

  10. Thermal transport measurements of uv laser irradiated spherical targets

    International Nuclear Information System (INIS)

    Jaanimagi, P.A.; Delettrez, J.; Henke, B.L.; Richardson, M.C.

    1985-01-01

    New measurements are presented of thermal transport in spherical geometry using time-resolved x-ray spectroscopy. We determine the time dependence of the mass ablation rate m(dot) by following the progress of the ablation surface through thin layers of material embedded at various depths below the surface of the target. These measurements made with 6 and 12 uv (351 nm) beams from OMEGA are compared to previous thermal transport data and are in qualitative agreement with detailed LILAC hydrodynamic code simulations which predict a sharp decrease in m(dot) after the peak of the laser pulse. Non-uniform laser irradiation of the target results in the anomalously high values of m(dot) measured in these experiments

  11. Reducing wall plasma expansion with gold foam irradiated by laser

    International Nuclear Information System (INIS)

    Zhang, Lu; Ding, Yongkun; Jiang, Shaoen; Yang, Jiamin; Li, Hang; Kuang, Longyu; Lin, Zhiwei; Jing, Longfei; Li, Liling; Deng, Bo; Yuan, Zheng; Chen, Tao; Yuan, Guanghui; Tan, Xiulan; Li, Ping

    2015-01-01

    The experimental study on the expanding plasma movement of low-density gold foam (∼1% solid density) irradiated by a high power laser is reported in this paper. Experiments were conducted using the SG-III prototype laser. Compared to solid gold with 19.3 g/cc density, the velocities of X-ray emission fronts moving off the wall are much smaller for gold foam with 0.3 g/cc density. Theoretical analysis and MULTI 1D simulation results also show less plasma blow-off, and that the density contour movement velocities of gold foam are smaller than those of solid gold, agreeing with experimental results. These results indicate that foam walls have advantages in symmetry control and lowering plasma fill when used in ignition hohlraum

  12. Reducing wall plasma expansion with gold foam irradiated by laser

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lu; Ding, Yongkun, E-mail: ding-yk@vip.sina.com; Jiang, Shaoen, E-mail: jiangshn@vip.sina.com; Yang, Jiamin; Li, Hang; Kuang, Longyu; Lin, Zhiwei; Jing, Longfei; Li, Liling; Deng, Bo; Yuan, Zheng; Chen, Tao; Yuan, Guanghui; Tan, Xiulan; Li, Ping [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)

    2015-11-15

    The experimental study on the expanding plasma movement of low-density gold foam (∼1% solid density) irradiated by a high power laser is reported in this paper. Experiments were conducted using the SG-III prototype laser. Compared to solid gold with 19.3 g/cc density, the velocities of X-ray emission fronts moving off the wall are much smaller for gold foam with 0.3 g/cc density. Theoretical analysis and MULTI 1D simulation results also show less plasma blow-off, and that the density contour movement velocities of gold foam are smaller than those of solid gold, agreeing with experimental results. These results indicate that foam walls have advantages in symmetry control and lowering plasma fill when used in ignition hohlraum.

  13. Thermal imaging of high power diode lasers subject to back-irradiance

    Science.gov (United States)

    Li, C.; Pipe, K. P.; Cao, C.; Thiagarajan, P.; Deri, R. J.; Leisher, P. O.

    2018-03-01

    CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying the relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.

  14. Measurement of large nonlinear refractive index of natural pigment extracted from Hibiscus rosa-sinensis leaves with a low power CW laser and by spatial self-phase modulation technique

    Science.gov (United States)

    Biswas, S.; Kumbhakar, P.

    2017-02-01

    We have reported here, for the first time, to the best of our knowledge, a high nonlinear refractive index (n2e) of a natural pigment extracted from Hibiscus rosa-sinensis leaves by using spatial self-phase modulation technique (SSPM) with a low power CW He-Ne laser radiation at 632.8 nm. It is found by UV-Vis absorption spectroscopic analysis that chlrophyll-a, chlrophyll-b and carotenoid are present in the pigment extract with 56%, 25% and 19%, respectively. The photoluminescence (PL) emission characteristics of the extracted samples have also been measured at room temperature as well as in the temperature range of 283-333 K to investigate the effect of temperature on luminescent properties of the sample. By analyzing the SSPM experimental data, the nonlinear refractive index value of pigment extract has been determined to be 3.5 × 10- 5 cm2/W. The large nonlinear refractive index has been assigned due to asymmetrical structure, molecular reorientation and thermally induced nonlinearity in the sample. The presented results might open new avenues for the green and economical technique of syntheses of organic dyes with such a large nonlinear optical property.

  15. Charged-particle acceleration through laser irradiation of thin foils at Prague Asterix Laser System

    International Nuclear Information System (INIS)

    Torrisi, Lorenzo; Cutroneo, Maria; Cavallaro, Salvatore; Musumeci, Paolo; Calcagno, Lucia; Wolowski, Jerzy; Rosinski, Marcin; Zaras-Szydlowska, Agnieszka; Ullschmied, Jiri; Krousky, Eduard; Pfeifer, Miroslav; Skala, Jiri; Velyhan, Andreiy

    2014-01-01

    Thin foils, 0.5–50 μm in thickness, have been irradiated in vacuum at Prague Asterix Laser System in Prague using 10 15–16  W cm −2 laser intensity, 1315 nm wavelength, 300 ps pulse duration and different focal positions. Produced plasmas from metals and polymers films have been monitored in the forward and backward directions. Ion and electron accelerations have been investigated by using Thomson parabola spectrometer, x-ray streak camera, ion collectors and SiC semiconductor detectors, the latter employed in time-of-flight configuration. Ion acceleration up to about 3 MeV per charge state was measured in the forward direction. Ion and electron emissions were detected at different angles as a function of the irradiation conditions. (paper)

  16. Investigation of field emission properties of laser irradiated tungsten

    International Nuclear Information System (INIS)

    Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Jalil, Sohail Abdul; Rafique, Muhammad Shahid

    2018-01-01

    Nd:YAG laser irradiation of Tungsten (W) has been performed in air at atmospheric pressure for four laser fluences ranging from 130 to 500 J/cm 2 . Scanning electron microscope analysis revealed the formation of micro and nanoscale surface features including cones, grains, mounds and pores. Field emission (FE) studies have been performed in a planar diode configuration under ultra-high vacuum conditions by recording I-V characteristics and plotting corresponding electric field (E) versus emission current density (J). The Fowler-Nordheim (FN) plots are found to be linear confirming the quantum mechanical tunneling phenomena for the structured targets. The irradiated samples at different fluences exhibit a turn-on field, field enhancement factor β and a maximum current density ranging from 5 to 8.5 V/μm, 1300 to 3490 and 107 to 350 μA/cm 2 , respectively. The difference in the FE properties is attributed to the variation in the nature and density of the grown structures at different fluences. (orig.)

  17. Evolution of Oxygen Deficiency Center on Fused Silica Surface Irradiated by Ultraviolet Laser and Posttreatment

    Directory of Open Access Journals (Sweden)

    Hai-Bing Lü

    2014-01-01

    Full Text Available Evolution of oxygen deficiency centers (ODCs on a fused silica surface irradiated using a 355 nm ultraviolet (UV laser beam in both vacuum and atmospheric conditions was quantitatively studied using photoluminescence and X-ray photoelectron spectroscopy. When the fusedsilica surface was exposed to the UV laser in vacuum, the laser damage threshold was decreased whereas the concentration of the ODCs was increased. For the fuse silica operated under the high power lasers, creation of ODCs on their surface resulted from the UV laser irradiation, and this is more severe in a high vacuum. The laser fluence and/or laser intensity have significant effects on the increase of the ODCs concentration. The ODCs can be effectively repaired using postoxygen plasma treatment and UV laser irradiation in an excessive oxygen environment. Results also demonstrated that the “gain” and “loss” of oxygen at the silica surface is a reversible and dynamic process.

  18. Multipulse nanosecond laser irradiation of silicon for the investigation of surface morphology and photoelectric properties

    Science.gov (United States)

    Sardar, Maryam; Chen, Jun; Ullah, Zaka; Jelani, Mohsan; Tabassum, Aasma; Cheng, Ju; Sun, Yuxiang; Lu, Jian

    2017-12-01

    We irradiate the single crystal boron-doped silicon (Si) with different number of laser pulses at constant fluence (7.5 J cm-2) in ambient air using Nd:YAG laser and examine its surface morphology and photoelectric properties in details. The results obtained from optical micrographs reveal the increase in heat affected zone (HAZ) and melted area of laser irradiated Si with increasing number of laser pulses. The SEM micrographs evidence the formation of various surface morphologies like laser induced periodic surface structures, crater, microcracks, clusters, cavities, pores, trapped bubbles, nucleation sites, micro-bumps, redeposited material and micro- and nano-particles on the surface of irradiated Si. The surface profilometry analysis informs that the depth of crater is increased with increase in number of incident laser pulses. The spectroscopic ellipsometry reveals that the multipulse irradiation of Si changes its optical properties (refractive index and extinction coefficient). The current-voltage (I-V) characteristic curves of laser irradiated Si show that although the multipulse laser irradiation produces considerable number of surface defects and damages, the electrical properties of Si are well sustained after the multipulse irradiation. The current findings suggest that the multipulse irradiation can be an effective way to tune the optical properties of Si for the fabrication of wide range of optoelectronic devices.

  19. Effect of laser-plasma X-ray irradiation on crystallization of amorphous silicon film by excimer laser annealing

    International Nuclear Information System (INIS)

    Matsuo, Naoto; Uejukkoku, Kazuya; Heya, Akira; Takanashi, Yasuyuki; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

    2007-01-01

    The effect of laser plasma soft X-ray (LPX) irradiation on crystallization by excimer laser annealing (ELA) was investigated at low ELA energy densities. The crystalline fraction at energy densities of 50 and 60 mJ/cm 2 for LPX followed by ELA is nearly equal to that at 80 to 100 mJ/cm 2 for the ELA method with non-LPX irradiation. The results obtained indicate that LPX irradiation before ELA reduces the critical energy density for the start of crystallization. The combined method of LPX irradiation and ELA will enable us to realize a low-temperature process for ELA crystallization. (author)

  20. Simulation analysis of impulse characteristics of space debris irradiated by multi-pulse laser

    Science.gov (United States)

    Lin, Zhengguo; Jin, Xing; Chang, Hao; You, Xiangyu

    2018-02-01

    Cleaning space debris with laser is a hot topic in the field of space security research. Impulse characteristics are the basis of cleaning space debris with laser. In order to study the impulse characteristics of rotating irregular space debris irradiated by multi-pulse laser, the impulse calculation method of rotating space debris irradiated by multi-pulse laser is established based on the area matrix method. The calculation method of impulse and impulsive moment under multi-pulse irradiation is given. The calculation process of total impulse under multi-pulse irradiation is analyzed. With a typical non-planar space debris (cube) as example, the impulse characteristics of space debris irradiated by multi-pulse laser are simulated and analyzed. The effects of initial angular velocity, spot size and pulse frequency on impulse characteristics are investigated.

  1. Measurements of three dimensional residual stress distribution on laser irradiated spot

    International Nuclear Information System (INIS)

    Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

    2004-01-01

    Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

  2. Femtosecond laser irradiation of the fluorescent molecules-loaded poly(lactic-co-glycolic acid)

    Science.gov (United States)

    Umemoto, Taiga; Shibata, Akimichi; Terakawa, Mitsuhiro

    2017-09-01

    Molecular release from scaffolds is desired for tailoring cell-compatible tissue engineering. Several methods have been proposed to control molecular release, such as annealing, plasma treatment, and laser processing. In this study, we describe the alteration of Rhodamine B (RhB)-loaded poly(lactic-co-glycolic acid) (PLGA) after femtosecond laser irradiation, which was evaluated on the basis of the water absorption and mass remaining. Fluorescence measurement of released RhB molecules revealed the acceleration of the molecular release upon 400-nm laser irradiation, whereas 800-nm laser irradiation did not induce a comparable degree of change compared with non-irradiated samples. The result of the water absorption measurement indicates that the large amount of water absorption of 400-nm laser-irradiated PLGA sample may accelerate the diffusion of the loaded molecules through absorbing water, which resulted in the faster molecular release.

  3. In Vitro UV-Visible Spectroscopy Study of Yellow Laser Irradiation on Human Blood

    Science.gov (United States)

    Fuad, Siti Sakinah Mohd; Suardi, N.; Mustafa, I. S.

    2018-04-01

    This experimental study was performed to investigate the effect of low level yellow laser of 589nm wavelength with various laser irradiation time. Human blood samples with random diseases are irradiated with yellow laser of power density of 450mW/cm2 from 10 minutes to 60 minutes at 10 minutes intervals. The morphology of the red blood cell were also observed for different irradiation time. The result shows that there is a significant different in the absorption of light with varying laser irradiation time (p<0.01). The maximum absorption recorded at 40 minutes of irradiation at 340nm peak. Blood smear of the samples reveals that there are observable changes in the morphology of the red blood cell at 40 minutes and 60 minutes of irradiation.

  4. ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

    Science.gov (United States)

    Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

    2018-05-01

    We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

  5. Low power digital signal processing

    DEFF Research Database (Denmark)

    Paker, Ozgun

    2003-01-01

    hardwired ASICs and more than 6 21 times lower than current state of the art low-power DSP processors. An orthogonal but practical contribution of this thesis is the test bench implementation. A PCI-based FPGA board has been used to equip a standard desktop PC with tester facilities. The test bench proved...... to be a viable alternative to conventional expensive test equipment. Finally, the work presented in this thesis has been published at several IEEE workshops and conferences, and in the Journal of VLSI Signal Processing....

  6. Role of laser fluence in protein synthesis of cultured DRG neurons following low-level laser irradiation

    Science.gov (United States)

    Zheng, Liqin; Qiu, Caimin; Wang, Yuhua; Zeng, Yixiu; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

    2014-11-01

    Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals. So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ·cm-2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ·cm-2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose- or fluence- dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.

  7. Low-Power Photothermal Probing of Single Plasmonic Nanostructures with Nanomechanical String Resonators

    DEFF Research Database (Denmark)

    Schmid, Silvan; Wu, Kaiyu; Larsen, Peter Emil

    2014-01-01

    We demonstrate the direct photothermal probing and mapping of single plasmonic nanostructures via the temperature-induced detuning of nanomechanical string resonators. Single Au nanoslits and nanorods are illuminated with a partially polarized focused laser beam (λ = 633 nm) with irradiances...... in the range of 0.26–38 μW/μm2. Photothermal heating maps with a resolution of ∼375 nm are obtained by scanning the laser over the nanostructures. Based on the string sensitivities, absorption efficiencies of 2.3 ± 0.3 and 1.1 ± 0.7 are extracted for a single nanoslit (53 nm × 1 μm) and nanorod (75 nm × 185 nm......). Our results show that nanomechanical resonators are a unique and robust analysis tool for the low-power investigation of thermoplasmonic effects in plasmonic hot spots....

  8. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang [Keio University, Department of Mechanical Engineering, Faculty of Science and Technology, Yokohama (Japan)

    2016-10-15

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN. (orig.)

  9. Microsized structures assisted nanostructure formation on ZnSe wafer by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Wang, Shutong; Feng, Guoying; Zhou, Shouhuan

    2014-01-01

    Micro/nano patterning of ZnSe wafer is demonstrated by femtosecond laser irradiation through a diffracting pinhole. The irradiation results obtained at fluences above the ablation threshold are characterized by scanning electron microscopy. The microsized structure with low spatial frequency has a good agreement with Fresnel diffraction theory. Laser induced periodic surface structures and laser-induced periodic curvelet surface structures with high spatial frequency have been found on the surfaces of microsized structures, such as spikes and valleys. We interpret its formation in terms of the interference between the reflected laser field on the surface of the valley and the incident laser pulse

  10. Shield gas induced cracks during nanosecond-pulsed laser irradiation of Zr-based metallic glass

    Science.gov (United States)

    Huang, Hu; Noguchi, Jun; Yan, Jiwang

    2016-10-01

    Laser processing techniques have been given increasing attentions in the field of metallic glasses (MGs). In this work, effects of two kinds of shield gases, nitrogen and argon, on nanosecond-pulsed laser irradiation of Zr-based MG were comparatively investigated. Results showed that compared to argon gas, nitrogen gas remarkably promoted the formation of cracks during laser irradiation. Furthermore, crack formation in nitrogen gas was enhanced by increasing the peak laser power intensity or decreasing the laser scanning speed. X-ray diffraction and micro-Raman spectroscopy indicated that the reason for enhanced cracks in nitrogen gas was the formation of ZrN.

  11. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Pérez del Pino, Ángel, E-mail: aperez@icmab.es; Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); György, Enikö [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiation Physics, P. O. Box MG 36, 76900 Bucharest V (Romania); Ballesteros, Belén [ICN2—Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

    2014-03-07

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

  12. Laser irradiation effects and its possible mechanisms of action on spermatozoa functions in domestic animals

    Directory of Open Access Journals (Sweden)

    S A Lone

    2017-01-01

    Full Text Available This article presents a review pertains the laser irradiation effects and its possible mechanisms of action on spermatozoa functions in domestic animals. To improve artificial insemination, laser is sensitive and cost effective technique, when compared to other conventional methods. Laser may have both positive and negative effects on spermatozoa functions. Since the effects of light are mediated by reactive oxygen species, and the levels of these reactive oxygen species following irradiating spermatozoa with laser may be responsible for determining the effects of laser on sperm. Dose of laser may be regarded as of great significance and this dosage of laser may be responsible for determining its effects on spermatozoa. Optimum dosage of laser for improving seminal attributes may vary among various species and this need to be standardized in each of them. The beneficial effects include improving sperm livability, acrosomal integrity, hypo-osmotic swelling response, mitochondrial function and computer-aided sperm analysis parameters. The increase in cytochrome c oxidase activity, ATP levels and mitochondrial membrane potential, in laser irradiated cells may be responsible for enhanced sperm quality parameters. Improving fertility with laser irradiated spermatozoa has been reported in few species like boar and need to be elaborated in other species. In conclusion laser may be regarded as an easy, cheap and time saving technology for improving artificial insemination; in addition, laser may have various potential applications in the field of reproductive biotechnology as well as in livestock farms and veterinary polyclinics.

  13. Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M.; Rodriguez, A.

    2014-01-01

    The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800 nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600 nm) and High Spatial Frequency LIPSS, showing a periodicity around 300 nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100 nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced

  14. Formation of laser-induced periodic surface structures on niobium by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pan, A.; Dias, A.; Gomez-Aranzadi, M.; Olaizola, S. M. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain); CEIT-IK4 and Tecnun, University of Navarra, Manuel Lardizábal 15, 20018 San Sebastián (Spain); Rodriguez, A. [CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón (Spain)

    2014-05-07

    The surface morphology of a Niobium sample, irradiated in air by a femtosecond laser with a wavelength of 800 nm and pulse duration of 100 fs, was examined. The period of the micro/nanostructures, parallel and perpendicularly oriented to the linearly polarized fs-laser beam, was studied by means of 2D Fast Fourier Transform analysis. The observed Laser-Induced Periodic Surface Structures (LIPSS) were classified as Low Spatial Frequency LIPSS (periods about 600 nm) and High Spatial Frequency LIPSS, showing a periodicity around 300 nm, both of them perpendicularly oriented to the polarization of the incident laser wave. Moreover, parallel high spatial frequency LIPSS were observed with periods around 100 nm located at the peripheral areas of the laser fingerprint and overwritten on the perpendicular periodic gratings. The results indicate that this method of micro/nanostructuring allows controlling the Niobium grating period by the number of pulses applied, so the scan speed and not the fluence is the key parameter of control. A discussion on the mechanism of the surface topology evolution was also introduced.

  15. Histological observation on dental hard tissue irradiated by ultrashort-pulsed laser

    Science.gov (United States)

    Uchizono, Takeyuki; Awazu, Kunio; Igarashi, Akihiro; Kato, Junji; Hirai, Yoshito

    2006-04-01

    In the field of dentistry, effectiveness of USPL irradiation is researched because USPL has less thermal side effect to dental hard tissue. In this paper, we observed morphological change and optical change of dental hard tissue irradiated by USPL for discussing the safety and effectiveness of USPL irradiation to dental hard tissues. Irradiated samples were crown enamel and root dentin of bovine teeth. Lasers were Ti:sapphire laser, which had pulse duration (P d)of 130 fsec and pulse repetition rate (f) of 1kHz and wavelength (l) of 800nm, free electron laser (FEL), which had P d of 15 μsec and f of 10Hz and wavelength of 9.6μm, and Er:YAG laser, which had P d of 250 μsec and f of 10Hz and wavelength of 2.94μm. After laser irradiation, the sample surfaces and cross sections were examined with SEM and EDX. The optical change of samples was observed using FTIR. In SEM, the samples irradiated by USPL had sharp and accurate ablation with no crack and no carbonization. But, in FEL and Er:YAG laser, the samples has rough ablation with crack and carbonization. It was cleared that the P/Ca ratio of samples irradiated by USPL had same value as non-irradiated samples. There was no change in the IR absorption spectrum between samples irradiated by USPL and non-irradiated sample. But, they of samples irradiated by FEL and Er:YAG laser, however, had difference value as non-irradiated samples. These results showed that USPL might be effective to ablate dental hard tissue without thermal damage.

  16. Influence of laser shock peening on irradiation defects in austenitic stainless steels

    Science.gov (United States)

    Lu, Qiaofeng; Su, Qing; Wang, Fei; Zhang, Chenfei; Lu, Yongfeng; Nastasi, Michael; Cui, Bai

    2017-06-01

    The laser shock peening process can generate a dislocation network, stacking faults, and deformation twins in the near surface of austenitic stainless steels by the interaction of laser-driven shock waves with metals. In-situ transmission electron microscopy (TEM) irradiation studies suggest that these dislocations and incoherent twin boundaries can serve as effective sinks for the annihilation of irradiation defects. As a result, the irradiation resistance is improved as the density of irradiation defects in laser-peened stainless steels is much lower than that in untreated steels. After heating to 300 °C, a portion of the dislocations and stacking faults are annealed out while the deformation twins remain stable, which still provides improved irradiation resistance. These findings have important implications on the role of laser shock peening on the lifetime extension of austenitic stainless steel components in nuclear reactor environments.

  17. SEM analysis of enamel surface treated by Er:YAG laser: influence of irradiation distance.

    Science.gov (United States)

    Souza-Gabriel, A E; Chinelatti, M A; Borsatto, M C; Pécora, J D; Palma-Dibb, R G; Corona, S A M

    2008-07-01

    Depending on the distance of laser tip to dental surface a specific morphological pattern should be expected. However, there have been limited reports that correlate the Er:YAG irradiation distance with dental morphology. To assess the influence of Er:YAG laser irradiation distance on enamel morphology, by means of scanning electron microscopy (SEM). Sixty human third molars were employed to obtain discs (approximately =1 mm thick) that were randomly assigned to six groups (n=10). Five groups received Er:YAG laser irradiation (80 mJ/2 Hz) for 20 s, according to the irradiation distance: 11, 12, 14, 16, or 17 mm and the control group was treated with 37% phosphoric acid for 15 s. The laser-irradiated discs were bisected. One hemi-disc was separated for superficial analysis without subsequent acid etching, and the other one, received the phosphoric acid for 15 s. Samples were prepared for SEM. Laser irradiation at 11 and 12 mm provided an evident ablation of enamel, with evident fissures and some fused areas. At 14, 16 and 17 mm the superficial topography was flatter than in the other distances. The subsequent acid etching on the lased-surface partially removed the disorganized tissue. Er:YAG laser in defocused mode promoted slight morphological alterations and seems more suitable for enamel conditioning than focused irradiation. The application of phosphoric acid on lased-enamel surface, regardless of the irradiation distance, decreased the superficial irregularities.

  18. Apraclonidine effects on ocular responses to YAG laser irradiation to the rabbit iris

    International Nuclear Information System (INIS)

    Sugiyama, K.; Kitazawa, Y.; Kawai, K.

    1990-01-01

    Apraclonidine (p-aminoclonidine) ophthalmic solution effectively reduces the rise in intraocular pressure (IOP) following anterior segment laser surgery. We tested the effect of topical 0.5% apraclonidine on intraocular pressure and on protein and prostaglandin (PG) E2 concentrations in aqueous humor following Q-switched Nd:YAG laser irradiation to the iris of albino rabbits, at an energy level of 2 to 200 mJ. IOP was measured prior to and for 24 hr after irradiation. Aqueous humor was withdrawn before and 1 hr after laser irradiation for determining protein (Lowry method) and PGE2 (radioimmunoassay). Four to seven rabbits were used for each experiment. The increase in IOP and protein concentration following laser irradiation was demonstrated to be dependent on the amount of laser energy. Apraclonidine completely abolished the IOP rise, and significantly reduced the elevation of protein content. Apraclonidine failed to affect the increase in PGE2

  19. Low power unattended defense reactor

    International Nuclear Information System (INIS)

    Kirchner, W.L.; Meier, K.L.

    1984-01-01

    A small, low power, passive, nuclear reactor electric power supply has been designed for unattended defense applications. Through innovative utilization of existing proven technologies and components, a highly reliable, ''walk-away safe'' design has been obtained. Operating at a thermal power level of 200 kWt, the reactor uses low enrichment uranium fuel in a graphite block core to generate heat that is transferred through heat pipes to a thermoelectric (TE) converter. Waste heat is removed from the TEs by circulation of ambient air. Because such a power supply offers the promise of minimal operation and maintenance (OandM) costs as well as no fuel logistics, it is particularly attractive for remote, unattended applications such as the North Warning System

  20. Low power unattended defense reactor

    International Nuclear Information System (INIS)

    Kirchner, W.L.; Meier, K.L.

    1984-01-01

    A small, low power, passive, nuclear reactor electric power supply has been designed for unattended defense applications. Through innovative utilization of existing proven technologies and components, a highly reliable, walk-away safe design has been obtained. Operating at a thermal power level of 200 kWt, the reactor uses low enrichment uranium fuel in a graphite block core to generate heat that is transferred through heat pipes to a thermoelectric (TE) converter. Waste heat is removed from the TEs by circulation of ambient air. Because such a power supply offers the promise of minimal operation and maintenance (O and M) costs as well as no fuel logistics, it is particularly attractive for remote, unattended applications such as the North Warning System

  1. Oscillating flux in petroleum emulsions irradiated with laser; Flujo oscilatorio en emulsiones de petroleo irradiadas con laser

    Energy Technology Data Exchange (ETDEWEB)

    Costa, G. Da; Parra, J.E.; Mosqueda, F. [Departamento de Fisica, Laboratorio de Optica y Fluidos, Universidad Simon Bolivar, Apartado Postal 89000, Caracas 1080-A, (Venezuela)]. e-mail: german@usb.ve; Romanelli, A.; Sicardi-Schifino, A. [Instituto de Fisica, Facultad de Ingenieria, Julio Herrera y Reissig 565, Montevideo, (Uruguay)]. e-mail alejo@fing.edu.uy

    2003-07-01

    Oil-in-water emulsions are irradiated with a Cw laser beam. A floating oil layer grows up in the water free surface. Laser-induced wave propagation in the oil layer gives rise to space-time self-modulation of the reflected light beam. A theoretical model explains main features of observed phenomena. (Author)

  2. Effect of laser pulse parameters on the size and fluorescence of nanodiamonds formed upon pulsed-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Peikang [School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China); Hu, Shengliang, E-mail: hsliang@yeah.net [Key Laboratory of Instrumentation Science and Dynamic Measurement (North University of China), Ministry of Education, National Key Laboratory Science and Technology on Electronic Test and Measurement, Taiyuan 030051 (China); School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China); Zhang, Taiping; Sun, Jing [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Cao, Shirui [School of Materials Science and Engineering, North University of China, Taiyuan 030051 (China)

    2010-07-15

    The size of nanodiamonds formed upon laser irradiation could be easily controlled over simply adjusting laser pulse parameters. The stable size and structure of nanodiamonds were mostly determined by laser power density and pulse width. Both large nanodiamonds with multiply twinning structure (MTS) and small nanodiamonds with single crystalline structure (SCS) emitted strong visible light after surface passivation, and their fluorescence quantum yield (QY) was 4.6% and 7.1%, respectively.

  3. Effect of laser pulse parameters on the size and fluorescence of nanodiamonds formed upon pulsed-laser irradiation

    International Nuclear Information System (INIS)

    Bai, Peikang; Hu, Shengliang; Zhang, Taiping; Sun, Jing; Cao, Shirui

    2010-01-01

    The size of nanodiamonds formed upon laser irradiation could be easily controlled over simply adjusting laser pulse parameters. The stable size and structure of nanodiamonds were mostly determined by laser power density and pulse width. Both large nanodiamonds with multiply twinning structure (MTS) and small nanodiamonds with single crystalline structure (SCS) emitted strong visible light after surface passivation, and their fluorescence quantum yield (QY) was 4.6% and 7.1%, respectively.

  4. Improving the bulk laser-damage resistance of KDP by baking and pulsed-laser irradiation

    International Nuclear Information System (INIS)

    Swain, J.E.; Stokowski, S.E.; Milam, D.; Rainer, F.

    1981-01-01

    Isolated bulk damage centers are produced when KDP crystals are irradiated by 1-ns 1064-nm pulses. We have tested about 100 samples and find the median threshold to be 7 J/cm 2 when the samples are irradiated only once at each test volume (1-on-1 tests). The median threshold increased to 11 J/cm 2 when the test volumes were first subjected to subthreshold laser irradiation (n-on-1 tests). We baked several crystals at temperatures from 110 to 165 0 C and remeasured their thresholds. Baking increased thresholds in some crystals, but did not change thresholds of others. The median threshold of baked crystals ranged from 8 to 10 J/cm 2 depending on the baking temperature. In crystals that had been baked, subthreshold irradiation produced a large change in the bulk damage threshold, and reduced the volume density of damage centers relative to the density observed in unbaked crystals. The data are summarized in the table

  5. [Effects of Nd: YAG laser irradiation on the root surfaces and adhesion of Streptococcus mutans].

    Science.gov (United States)

    Yuanhong, Li; Zhongcheng, Li; Mengqi, Luo; Daonan, Shen; Shu, Zhang; Shu, Meng

    2016-12-01

    This study aimed to evaluate the effects of treatment with different powers of Nd: YAG laser irradiation on root surfaces and Streptococcus mutans (S. mutans) adhesion. Extracted teeth because of severe periodontal disease were divided into the following four groups: control group, laser group 1, laser group 2, and laser group 3. After scaling and root planning, laser group 1, laser group 2, and laser group 3 were separately treated with Nd: YAG laser irradiation (4/6/8 W, 60 s); however, the control group did not receive the treatment. Scanning electron microscopy (SEM) was used to determine the morphology. S. mutans were cultured with root slices from each group. Colony forming unit per mL (CFU·mL⁻¹) was used to count and compare the amounts of bacteria adhesion among groups. SEM was used to observe the difference of bacteria adhesion to root surfaces between control group (scaling) and laser group 2 (6 W, 60 s), thereby indicating the different bacteria adhesions because of different treatments. Morphology alterations indicated that root surfaces in control group contain obvious smear layer, debris, and biofilm; whereas the root surfaces in laser group contain more cracks with less smear layer and debris. The bacteria counting indicated that S. mutans adhesion to laser group was weaker than that of control group (P0.05) was observed. Morphology alterations also verified that S. mutans adhesion to laser group 2 (6 W, 60 s) was weaker than that of control group (scaling). This study demonstrated that Nd: YAG laser irradiation treatment after scaling can reduce smear layer, debris, and biofilm on the root surfaces as compared with conventional scaling. The laser treatment reduces the adhesion of S. mutans as well. However, Nd: YAG laser irradiation can cause cracks on the root surfaces. In this experiment, the optimum laser power of 6 W can thoroughly remove the smear layer and debris, as well as relatively improve the control of thermal damagee.

  6. Acute effects of pulsed-laser irradiation on the arterial wall

    Science.gov (United States)

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

    1992-08-01

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

  7. Small-scale heat detection using catalytic microengines irradiated by laser

    Science.gov (United States)

    Liu, Zhaoqian; Li, Jinxing; Wang, Jiao; Huang, Gaoshan; Liu, Ran; Mei, Yongfeng

    2013-01-01

    We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection.We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32494f

  8. Low- and high-dose laser irradiation effects on cell migration and destruction

    Science.gov (United States)

    Layton, Elivia; Gallagher, Kyra A.; Zukerman, Sara; Stevens, Brianna; Zhou, Feifan; Liu, Hong; Chen, Wei R.

    2018-02-01

    Metastases are the cause of more than 90 percent of cancer-related deaths. Current treatment methods, including chemotherapy, radiation, and surgery, fail to target the metastases effectively. One potential treatment for metastatic cancer is laser immunotherapy (LIT). LIT combines the use of a photothermal laser with an immunoadjuvant, Glycated Chitosan (GC). GC combined with single-walled carbon nanotubes (SWNTs) has proven to be a viable alternative to traditional cancer treatment methods, when under irradiation of laser with appropriate wavelength. In this study, the effects of low dose and high dose laser irradiation on metastatic pancreatic cancer cell migration were observed. It was found that low dose irradiation increased the migration rate, but the high dose irradiation significantly decreased the migration rate of the cancer cells. When using LIT, the goal is to kill tumor cells and to prompt the correct immune response. If the tumor were irradiated with a low dose, it would promote metastasis. If the dose of irradiation were too high, it would destroy the entire tumor and the immune response would not recognize the tumor. Therefore, the laser dose plays an important role in LIT, particularly when using SWNT as light absorbing agent. Our results from this study will delineate the optimal laser irradiation dose for destroying tumor cells and at the same time preserve and release tumor antigens as a precursor of antitumor immune response.

  9. In Vitro Evaluation of Dentin Hydraulic Conductance After 980 nm Diode Laser Irradiation.

    Science.gov (United States)

    Rizzante, Fabio A P; Maenosono, Rafael M; Duarte, Marco A H; Furuse, Adilson Y; Palma-Dibb, Regina G; Ishikiriama, Sérgio K

    2016-03-01

    Dentin hypersensitivity treatments are based on the physical obliteration of the dentinal tubules to reduce hydraulic conductance. The aim of the present study is to evaluate the hydraulic conductance of bovine root dentin after irradiation with a 980-nm diode laser, with or without associated fluoride varnish. Sixty bovine root dentin specimens were divided into six groups (n = 10 in each group): G1, G3, and G5 (0.5 W, 0.7 W, and 1 W diode laser, respectively); G2, G4, and G6 (fluoride varnish application + 0.5 W, 0.7 W, and 1 W diode laser, respectively). The dentin hydraulic conductance was evaluated at four time periods with a fluxmeter: 1) with smear layer, 2) after 37% phosphoric acid etching, 3) after the treatments, and 4) after 6% citric acid challenge. After the dentinal fluid flow measurements, specimens were also evaluated for mineral composition using energy dispersive X-ray spectroscopy (EDS). Analysis demonstrated a better result with increased irradiation power (P diode laser irradiation was associated with the application of fluoride varnish (P laser irradiation, the 1 W group was superior when compared with the 0.5 W and 0.7 W irradiated groups immediately after treatment (P laser treatments. Laser irradiation of exposed dentin promoted significant reduction in the dentin hydraulic conductance, mainly with higher energy densities and association with fluoride varnish.

  10. Laser irradiation reduces HIV-1 infection in TZM-bl cells

    CSIR Research Space (South Africa)

    Lugongolo, Masixole Y

    2016-10-01

    Full Text Available HIV-1 epidemic remains a major health challenge. This study explores the effects of low level laser therapy on HIV-1 infected cells. Infection is reduced by irradiation and the mechanism needs to be investigated further....

  11. Bond strength of an adhesive system irradiated with Nd:YAG laser in dentin treated with Er:YAG laser

    International Nuclear Information System (INIS)

    Malta, D A M P; De Andrade, M F; Costa, M M; Lizarelli, R F Z; Pelino, J E P

    2008-01-01

    The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm 2 . The adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm 2 . Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser

  12. Low Level (Sub Threshold), Large Spot Laser Irradiations of the Foveas of Macaca Mulatta.

    Science.gov (United States)

    1981-11-01

    spherules. In a portion of the block containing the macula a degenerating patch is seen, displaying considerable edema, with pyknotic and missing nuclei...6 Peripheral areas 11 Macula 11 Eye # 3 M31 2KD 15 (enucleated 7 days after focal irradiation jby gallium arsenide laser). Control areas 15 Neodymium...laser irradiations peripheral areas 23 Macula 28 TABLE OF CONTENTS continued Page Eye # 5 M443 2JD Patched Eye 32 Most areas 32 area nasal to optic disc

  13. Wavelength influence on nitrogen insertion into titanium by nanosecond pulsed laser irradiation in air

    Energy Technology Data Exchange (ETDEWEB)

    Torrent, F.; Lavisse, L. [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France); Berger, P. [CEA/DSM/IRAMIS/SIS2M, CEA-Saclay, F-91191 Gif sur Yvette (France); SIS2M, UMR CEA-CNRS 3299, CEA-Saclay, F-91191 Gif sur Yvette (France); Jouvard, J.-M.; Andrzejewski, H.; Pillon, G.; Bourgeois, S.; Marco de Lucas, M.C. [Laboratoire Interdisciplinaire Carnot de Bourgogne (ICB), UMR 6303 CNRS-Université de Bourgogne, 9 Av. A. Savary, BP 47 870, F-21078 Dijon Cedex (France)

    2013-08-01

    We studied in this work the influence of the wavelength (532 vs. 1064 nm) on the insertion of nitrogen in titanium targets by surface laser treatments in air. The laser pulses were of 5 ns and the irradiance was lower than 25 × 10{sup 12} W/m{sup 2}. Results obtained using a frequency-doubled Nd:YAG laser at 532 nm were compared with those previously reported for laser treatments at 1064 nm. Nuclear reaction analysis and micro-Raman spectroscopy were used for determining the composition and the structure of the surface layers, respectively. Results showed the lower efficiency of irradiation at 532 nm for nitrogen insertion, which is possible only above threshold conditions depending on both the laser irradiance and the number of cumulated impacts per point. This was explained as being due to a higher ablative effect in the visible range. The insertion of oxygen giving rise to the growth of titanium oxynitrides was also discussed.

  14. In vitro assessment of the bactericidal effect of low-power arsenium-gallium (AsGa laser treatment Avaliação in vitro da ação bactericida do laser de baixa potência (AsGa

    Directory of Open Access Journals (Sweden)

    Adilvania Ferreira da Costa

    2012-08-01

    Full Text Available The objective of the present study was to perform an in vitro evaluation of the bactericidal action of a low-power arsenium-gallium (AsGa laser at a wavelength of 904nm and energy density of 6 J/cm². Ten petri dishes were seeded with Pseudomonas aeruginosa and another ten with Staphylococcus aureus. The dishes were then randomly divided into four groups with five plates in each group. Two groups were treated with AsGa laser once a day for 5 days, while the other two groups received no treatment. No halo of growth inhibition was found in any of the groups. It was therefore concluded that laser treatment (AsGa, 904nm, 6J/cm² had no bactericidal effect.Verificar, in vitro, o efeito bactericida do laser de baixa potência, AsGa, 904nm, na dose 6 J/cm2. Foram semeadas 10 placas de Petri com a bactéria Pseudomonas aeruginosa e 10 placas de Petri com Staphylococcus aureus. Aleatoriamente, foram divididas em quatro grupos (5 placas cada: dois grupos foram tratados com o laser AsGa a cada 24 horas, durante cinco dias, e dois grupos não receberam tratamento. Em todos os grupos, não foi observado qualquer halo de inibição do crescimento. Assim, concluiuse que a terapia a laser (AsGa, 904nm, 6 J/cm² não produziu efeito bactericida.

  15. Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis

    Energy Technology Data Exchange (ETDEWEB)

    Picard, J., E-mail: jessica.picard@cea.fr [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Sirven, J.-B.; Lacour, J.-L. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France); Musset, O. [Université de Bourgogne, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, F-21000 Dijon (France); Cardona, D.; Hubinois, J.-C. [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Mauchien, P. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France)

    2014-11-01

    The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser–plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser beam spatial profile at the sample surface was characterized in order to give realistic values of the irradiance. The effect of the number of accumulated laser shots on the crater volume was studied. Then, the ablation crater morphology, volume, depth and diameter were measured as a function of irradiance between 0.35 and 96 GW/cm². Results show that in the vacuum, a regular trend is observed over the whole irradiance range. In air at 1 bar, below a certain irradiance, laser ablation is very similar to the vacuum case, and the ablation efficiency of copper was estimated at 0.15 ± 0.03 atom/photon. Beyond this irradiance, the laser beam propagation is strongly disrupted by the expansion of the dense plasma, and plasma shielding appears. The fraction of laser energy used for laser ablation and for plasma heating is estimated in the different irradiance regimes. - Highlights: • The morphology of copper's craters was studied as a function of the pulse energy. • Correlation at low energy and two pressures between crater volume and pulse energy • The ablation efficiency of copper at 1 bar is equal to 0.15 atom/photon. • Ablation efficiency in the vacuum is not limited by laser–plasma interaction. • Physical mechanisms of laser ablation at both pressures are discussed.

  16. Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

    Directory of Open Access Journals (Sweden)

    Abbas Monzavi

    2014-04-01

    Full Text Available Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage.The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems.Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture.In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (P<0.001.Based on the results, no thermal damage was observed during implant surface decontamination by Er:YAG laser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

  17. Generation of polyyne and methylpolyyne molecules from toluene by intense femtosecond laser pulse irradiation

    International Nuclear Information System (INIS)

    Ramadhan, Ali; Wesolowski, Michal; Duley, Walter; Sanderson, Joseph; Wakabayashi, Tomonari; Shiromaru, Haruo; Fujino, Tatsuya; Kodama, Takeshi

    2015-01-01

    Hydrogen-capped and methyl-capped carbon chains (polyynes) have been generated by intense femtosecond laser irradiation of pure liquid toluene. UV-Vis and Raman spectroscopy were used to confirm the presence of polyynes in the irradiated samples, and high performance liquid chromatography (HPLC) was used to separate polyynes up to C 18 H 2 and HC 13 CH 3 . (paper)

  18. Analysis of irradiation processes for laser-induced periodic surface structures

    NARCIS (Netherlands)

    Eichstädt, J.; Huis In 't Veld, A.J.

    2013-01-01

    The influence of errors on the irradiation process for laser-induced periodic surface structures (LIPSS) was studied theoretically with energy density simulations. Therefore an irradiation model has been extended by a selection of technical variations. The influence of errors has been found in a

  19. Data formats design of laser irradiation experiments in view of data analysis

    International Nuclear Information System (INIS)

    Su Chunxiao; Yu Xiaoqi; Yang Cunbang; Guo Su; Chen Hongsu

    2002-01-01

    The designing rules of new data file formats of laser irradiation experiments are introduced. Object-oriented programs are designed in studying experimental data of the laser facilities. The new format data files are combinations of the experiment data and diagnostic configuration data, which are applied in data processing and analysis. The edit of diagnostic configuration data in data acquisition program is also described

  20. Temperature response of biological materials to pulsed non-ablative CO2 laser irradiation

    NARCIS (Netherlands)

    Brugmans, M. J.; Kemper, J.; Gijsbers, G. H.; van der Meulen, F. W.; van Gemert, M. J.

    1991-01-01

    This paper presents surface temperature responses of various tissue phantoms and in vitro and in vivo biological materials in air to non-ablative pulsed CO2 laser irradiation, measured with a thermocamera. We studied cooling off behavior of the materials after a laser pulse, to come to an

  1. Modeling and simulation of heat distribution in human skin caused by laser irradiation

    NARCIS (Netherlands)

    Luan, Y.; Dams, S.D.

    2009-01-01

    Study of light-based skin rejuvenation needs prospective insights of mechanism of laser tissue interaction. A well-built model plays a key role in predicting temperature distribution in human skin exposed to laser irradiation. Therefore, it not only provides guidance for in vitro experiment, but

  2. Cladding-like waveguide fabricated by cooperation of ultrafast laser writing and ion irradiation: characterization and laser generation.

    Science.gov (United States)

    Lv, Jinman; Shang, Zhen; Tan, Yang; Vázquez de Aldana, Javier Rodríguez; Chen, Feng

    2017-08-07

    We report the surface cladding-like waveguide fabricated by the cooperation of the ultrafast laser writing and the ion irradiation. The ultrafast laser writes tracks near the surface of the Nd:YAG crystal, constructing a semi-circle columnar structure with a decreased refractive index of - 0.00208. Then, the Nd:YAG crystal is irradiated by the Carbon ion beam, forming an enhanced-well in the semi-circle columnar with an increased refractive index of + 0.0024. Tracks and the enhanced-well consisted a surface cladding-like waveguide. Utilizing this cladding-like waveguide as the gain medium for the waveguide lasing, optimized characterizations were observed compared with the monolayer waveguide. This work demonstrates the refractive index of the Nd:YAG crystal can be well tailored by the cooperation of the ultrafast laser writing and the ion irradiation, which provides an convenient way to fabricate the complex and multilayered photonics devices.

  3. Low-Power Wireless Sensor Network Infrastructures

    DEFF Research Database (Denmark)

    Hansen, Morten Tranberg

    Advancements in wireless communication and electronics improving form factor and hardware capabilities has expanded the applicability of wireless sensor networks. Despite these advancements, devices are still limited in terms of energy which creates the need for duty-cycling and low-power protocols...... peripherals need to by duty-cycled and the low-power wireless radios are severely influenced by the environmental effects causing bursty and unreliable wireless channels. This dissertation presents a communication stack providing services for low-power communication, secure communication, data collection......, and network management which enables construction of low-power wireless sensor network applications. More specifically, these services are designed with the extreme low-power scenarios of the SensoByg project in mind and are implemented as follows. First, low-power communication is implemented with Auto...

  4. Effect of Nd: YAG laser irradiation on surface properties and bond strength of zirconia ceramics.

    Science.gov (United States)

    Liu, Li; Liu, Suogang; Song, Xiaomeng; Zhu, Qingping; Zhang, Wei

    2015-02-01

    This study investigated the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser irradiation on surface properties and bond strength of zirconia ceramics. Specimens of zirconia ceramic pieces were divided into 11 groups according to surface treatments as follows: one control group (no treatment), one air abrasion group, and nine laser groups (Nd: YAG irradiation). The laser groups were divided by applying with different output power (1, 2, or 3 W) and irradiation time (30, 60, or 90 s). Following surface treatments, the morphological characteristics of ceramic pieces was observed, and the surface roughness was measured. All specimens were bonded to resin cement. After, stored in water for 24 h and additionally aged by thermocycling, the shear bond strength was measured. Dunnett's t test and one-way ANOVA were performed as the statistical analyses for the surface roughness and the shear bond strength, respectively, with α = .05. Rougher surface of the ceramics could be obtained by laser irradiation with higher output power (2 and 3 W). However, cracks and defects were also found on material surface. The shear bond strength of laser groups was not obviously increased, and it was significantly lower than that of air abrasion group. No significant differences of the shear bond strength were found among laser groups treated with different output power or irradiation time. Nd: YAG laser irradiation cannot improve the surface properties of zirconia ceramics and cannot increase the bond strength of the ceramics. Enhancing irradiation power and extending irradiation time cannot induce higher bond strength of the ceramics and may cause material defect.

  5. Soviet paper on laser target heating, symmetry of irradiation, and two-dimensional effects on compression

    International Nuclear Information System (INIS)

    Sahlin, H.L.

    1976-01-01

    Included is a paper presented at the Annual Meeting of the Plasma Physics Division of the American Physical Society in San Francisco on November 19, 1976. The paper discusses some theoretical problems of laser target irradiation and compression investigated at the laboratory of quantum radiophysics of Lebedev Physical Institute. Of significant interest was the absorption and reflection of laser radiation in the corona plasma of a laser target

  6. Realignment process of actin stress fibers in single living cells studied by focused femtosecond laser irradiation

    OpenAIRE

    Yasukuni, Ryohei; Spitz, Jean-Alexis; Meallet-Renault, Rachel; Negishi, Takayuki; Tada, Takuji; Hosokawa, Yoichiroh; Asahi, Tsuyoshi; Shukunami, Chisa; Hiraki, Yuji; Masuhara, Hiroshi

    2007-01-01

    Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a...

  7. Alignment control of columnar liquid crystals with wavelength tunable CO2 laser irradiation

    International Nuclear Information System (INIS)

    Monobe, Hirosato; Awazu, Kunio; Shimizu, Yo

    2008-01-01

    Infrared-induced alignment change with wavelength tunable CO 2 laser irradiation for columnar liquid crystal domains was investigated for a liquid crystalline triphenylene derivative. A uniformly aligned alignment change of domains was observed when a chopped linearly polarized infrared laser light corresponding to the wavelength of the aromatic C-O-C stretching vibration band (9.65 μm) was irradiated. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophase as a liquid crystalline semiconductor

  8. Excimer-laser-irradiation-induced effects in C60 films for photovoltaic applications

    International Nuclear Information System (INIS)

    Narayanan, K.L.; Yamaguchi, M.; Azuma, H.

    2002-01-01

    Thin films of fullerene C 60 deposited by the molecular-beam epitaxy method have been subjected to a 248 nm excimer laser for various timings. Reduction in the electrical resistance of the films and the spectral evolution of the D and G bands in the Raman spectra, due to the sharp tendency towards graphitization accompanied by an increasing level of structural disorder, are observed during laser irradiation. Based on the above results, an attempt has been carried out on these irradiated C 60 films to make a device sandwiched with n-type Si, and the photovoltaic parameters are reported as a function of the laser exposure times

  9. Monooxignase ensymic system of a liver of rats exposed to intravascular laser irradiation of blood

    International Nuclear Information System (INIS)

    Ibadova, G.A.

    1997-01-01

    Experimental study of the dynamic monooxidation of liver enzymic system was carried out on rats with experimental salmonellosis and the influence of the blood intravascular laser irradiation of blood on these enzymes was revealed. It was determined that by experimental salmonellosis oppression of the MOES activity of hepatocytes occurred. The blood intravascular irradiation by He-Ne laser promotes MOES oppression in rats suffered from salmonellosis. IVLIB as well as UV-laser show pronounced effect on the enzymes detoxication protection, mobilize their resistance to endogenic intoxication under the conditions of experimental salmonellosis. (author)

  10. Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings

    Science.gov (United States)

    Li, Bo; Jin, Yan; Yao, Jianhua; Li, Zhihong; Zhang, Qunli; Zhang, Xin

    2018-03-01

    Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.

  11. Laser irradiation effects on the surface, structural and mechanical properties of Al-Cu alloy 2024

    Science.gov (United States)

    Yousaf, Daniel; Bashir, Shazia; Akram, Mahreen; kalsoom, Umm-i.-; Ali, Nisar

    2014-02-01

    Laser irradiation effects on surface, structural and mechanical properties of Al-Cu-Mg alloy (Al-Cu alloy 2024) have been investigated. The specimens were irradiated for various fluences ranging from 3.8 to 5.5 J/cm2 using an Excimer (KrF) laser (248 nm, 18 ns, 30 Hz) under vacuum environment. The surface and structural modifications of the irradiated targets have been investigated by scanning electron microscope (SEM) and X-ray diffractometer (XRD), respectively. SEM analysis reveals the formation of micro-sized craters along the growth of periodic surface structures (ripples) at their peripheries. The size of the craters initially increases and then decreases by increasing the laser fluence. XRD analysis shows an anomalous trend in the peak intensity and crystallite size of the specimen irradiated for various fluences. A universal tensile testing machine and Vickers microhardness tester were employed in order to investigate the mechanical properties of the irradiated targets. The changes in yield strength, ultimate tensile strength and microhardness were found to be anomalous with increasing laser fluences. The changes in the surface and structural properties of Al-Cu alloy 2024 after laser irradiation have been associated with the changes in mechanical properties.

  12. Influence of laser shock peening on irradiation defects in austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Qiaofeng [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Su, Qing [Nebraska Center for Energy Sciences Research, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Wang, Fei [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Zhang, Chenfei; Lu, Yongfeng [Department of Electrical Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nastasi, Michael [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Energy Sciences Research, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Cui, Bai, E-mail: bcui3@unl.edu [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

    2017-06-15

    The laser shock peening process can generate a dislocation network, stacking faults, and deformation twins in the near surface of austenitic stainless steels by the interaction of laser-driven shock waves with metals. In-situ transmission electron microscopy (TEM) irradiation studies suggest that these dislocations and incoherent twin boundaries can serve as effective sinks for the annihilation of irradiation defects. As a result, the irradiation resistance is improved as the density of irradiation defects in laser-peened stainless steels is much lower than that in untreated steels. After heating to 300 °C, a portion of the dislocations and stacking faults are annealed out while the deformation twins remain stable, which still provides improved irradiation resistance. These findings have important implications on the role of laser shock peening on the lifetime extension of austenitic stainless steel components in nuclear reactor environments. - Highlights: •Laser shock peening generates a dislocation network, stacking faults and deformation twins in stainless steels. •Dislocations and incoherent twin boundaries serve as effective sinks for the annihilation of irradiation defects. •Incoherent twin boundaries remain as stable and effective defect sinks at 300 °C.

  13. Residual stress improvement mechanism on metal material by underwater laser irradiation

    International Nuclear Information System (INIS)

    Sano, Yuji; Yoda, Masaki; Mukai, Naruhiko; Obata, Minoru; Kanno, Masanori

    2000-01-01

    Residual stress improvement technology for component surface by underwater pulsed laser irradiation has been developed as a method of preventing stress corrosion cracking (SCC) of core components in nuclear reactors. In order to optimize the laser irradiation conditions based on a complete understanding of the mechanism, the propagation of a shock wave induced by the impulse of laser irradiation and the dynamic response of the irradiated material were analyzed through time-dependent elasto-plastic calculations with a finite element program. The calculated results are compared with the measured results obtained by experiments in which laser pulses with an energy of 200 mJ are focused to a diameter of 0.8 mm on a water-immersed test piece of 20% cold-worked Type 304 austenitic stainless steel to simulate neutron irradiation hardening. A residual compressive stress, which is nearly equivalent to the yield stress of the processed material, remains on the material surface after passage of the shock wave with enough amplitude to induce a permanent strain. Multiple irradiation of laser pulses extends the stress-improved depth to about 1 mm, which would be the limit corresponding to the three-dimensional dispersion effect of the shock wave. (author)

  14. A low power ADS for transmutation studies in fast systems

    Science.gov (United States)

    Panza, Fabio; Firpo, Gabriele; Lomonaco, Guglielmo; Osipenko, Mikhail; Ricco, Giovanni; Ripani, Marco; Saracco, Paolo; Viberti, Carlo Maria

    2017-12-01

    In this work, we report studies on a fast low power accelerator driven system model as a possible experimental facility, focusing on its capabilities in terms of measurement of relevant integral nuclear quantities. In particular, we performed Monte Carlo simulations of minor actinides and fission products irradiation and estimated the fission rate within fission chambers in the reactor core and the reflector, in order to evaluate the transmutation rates and the measurement sensitivity. We also performed a photo-peak analysis of available experimental data from a research reactor, in order to estimate the expected sensitivity of this analysis method on the irradiation of samples in the ADS considered.

  15. Thermal Effects Induced by Laser Irradiation of Solids

    International Nuclear Information System (INIS)

    Galovic, S.

    2004-01-01

    A part of incident energy is absorbed within the irradiated sample when a solid is exposed to the influence of laser radiation, to more general electromagnetic radiation within the wide range of wavelengths (from microwaves, to infrared radiation to X-rays), or to the energy of particle beams (electronic, protonic, or ionic). The absorption process signifies a highly selective excitation of the electronic state of atoms or molecules, followed by thermal and non-thermal de-excitation processes. Non-radiation de-excitation-relaxation processes induce direct sample heating. In addition, a great number of non-thermal processes (e.g., photoluminescence, photochemistry, photovoltage) may also induce heat generation as a secondary process. This method of producing heat is called the photothermal effect.The photothermal effect and subsequent propagation of thermal waves on the surface and in the volume of the solid absorbing the exciting beam may produce the following: variations in the temperature on the surfaces of the sample; deformation and displacement of surfaces; secondary infrared radiation (photothermal radiation); the formation of the gradient of the refractivity index; changes in coefficients of reflection and absorbtion; the generation of sound (photoacoustic generation), etc. These phenomena may be used in the investigation and measurement of various material properties since the profile and magnitude of the generated signal depend upon the nature of material absorbing radiation. A series of non-destructive spectroscopic, microscopic and defectoscopic detecting techniques, called photothermal methods, is developed on the basis of the above-mentioned phenomena.This paper outlines the interaction between the intensity modulated laser beam and solids, and presents a mathematical model of generated thermal sources. Generalized models for a photothermal response of optically excited materials have been obtained, including thermal memory influence on the propagation

  16. Magnetic resonance thermometry for monitoring photothermal effects of interstitial laser irradiation

    Science.gov (United States)

    Goddard, Jessica; Jose, Jessnie; Figueroa, Daniel; Le, Kelvin; Liu, Hong; Nordquist, Robert E.; Hode, Tomas; Chen, Wei R.

    2012-03-01

    Selective photothermal interaction using dye-assisted non-invasive laser irradiation has limitations when treating deeper tumors or when the overlying skin is heavily pigmented. We developed an interstitial laser irradiation method to induce the desired photothermal effects. An 805-nm near-infrared laser with a cylindrical diffuser was used to treat rat mammary tumors by placing the active tip of the fiber inside the target tumors. Three different power settings (1.0 to 1.5 watts) were applied to treat animal tumors with an irradiation duration of 10 minutes. The temperature distributions of the treated tumors were measured by a 7.1-Tesla magnetic resonance imager using proton resonance frequency (PRF) method. Three-dimensional temperature profiles were reconstructed and assessed using PRF. This is the first time a 7.1-Tesla magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. This study provides a basic understanding of the photothermal interaction needed to control the thermal damage inside tumor using interstitial laser irradiation. It also shows that PRF can be used effectively in monitoring photothermal interaction. Our long-term goal is to develop a PRF-guided laser therapy for cancer treatment.

  17. Laser cutting equipment for dismantling irradiated PFR fuel sub-assemblies

    International Nuclear Information System (INIS)

    Higginson, P.R.; Campbell, D.A.

    1981-01-01

    Laser cutting was identified as a possible technique for dismantling irradiated Prototype Fast Reactor (P.F.R.) fuel sub-assemblies and initial trials showed that it could be used to make essentially swarf free cuts in P.F.R. wrapper material provided sufficient laser power was available to allow use of an inert cutting gas. A programme of development work has established a technique for inert gas cutting with the reliable, commercially available Ferranti MF 400 laser and equipment for laser cutting of sub-assemblies has been installed in the Irradiated Fuel Cave at P.F.R. Test cuts carried out with this equipment on un-irradiated wrapper sections have shown it to be easy to operate remotely, optically stable and reliable in operation. (author)

  18. Low power consumption O-band VCSEL sources for upstream channels in PON systems

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Rodes Lopez, Roberto; Tafur Monroy, Idelfonso

    2012-01-01

    This paper presents an experimental validation of a low power optical network unit employing vertical-cavity surface-emitting lasers as upstream sources for passive optical networks with an increased power budget, enabling even larger splitting ratios....

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

    Science.gov (United States)

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

    2013-12-01

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

  20. Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani, S.A. Ahmad, E-mail: Ramazani@sharif.ir [Polymer Group, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mousavi, Seyyed Abbas, E-mail: Musavi@che.sharif.ir [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Seyedjafari, Ehsan [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of); Poursalehi, Reza [Department of Physics, University of Shahed, Tehran (Iran, Islamic Republic of); Sareh, Shohreh [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Silakhori, Kaveh [Laser Research Center, Atomic Energy Organization, Tehran (Iran, Islamic Republic of); Poorfatollah, Ali Akbar [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Shamkhali, Amir Nasser [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2009-05-05

    Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after treatment. The results obtained from this test showed that after laser treatment, the cells were attached and proliferated extensively on the Nd:YAG laser treated films in comparison with the unmodified PC. Moreover, it was revealed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface. The obtained results also showed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface.

  1. The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D.; Reeves, Robert V.; Yarrington, Cole D.; Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

    2015-12-07

    Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. High-speed photography was used to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

  2. Effect of LASER Irradiation on the Shear Bond Strength of Zirconia Ceramic Surface to Dentin

    Directory of Open Access Journals (Sweden)

    Sima Shahabi

    2012-09-01

    Full Text Available Background and Aims: Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin. Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO2 laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM. Results: The mean shear bond strength of zirconia ceramic to dentin was 7.79±3.03, 9.85±4.69, 14.92±4.48 MPa for CO2 irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO2 (P=0.001 and Nd:YAG laser (P=0.017 irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods (P=0.47. The mode of bond failure was predominantly adhesive in test groups (CO2 irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%. Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO2 and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics.

  3. Morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel.

    Science.gov (United States)

    Manuela Díaz-Monroy, Jennifer; Contreras-Bulnes, Rosalía; Fernando Olea-Mejía, Oscar; Emma Rodríguez-Vilchis, Laura; Sanchez-Flores, Ignacio

    2014-06-01

    Several scientific reports have shown the effects of Er:YAG laser irradiation on enamel morphology. However, there is lack of information regarding the morphological alterations produced by the acid attack on the irradiated surfaces. The aim of this study was to evaluate the morphological changes produced by acid dissolution in Er:YAG laser irradiated dental enamel. Forty-eight enamel samples were divided into four groups (n = 12). GI (control); Groups II, III, and IV were irradiated with Er:YAG at 100 mJ (12.7 J/cm(2) ), 200 mJ (25.5 J/cm(2) ), and 300 mJ (38.2 J/cm(2) ), respectively, at 10 Hz without water irrigation. Enamel morphology was evaluated before-irradiation, after-irradiation, and after-acid dissolution, by scanning electron microscopy (SEM). Sample coating was avoided and SEM analysis was performed in a low-vacuum mode. To facilitate the location of the assessment area, a reference point was marked. Morphological changes produced by acid dissolution of irradiated enamel were observed, specifically on laser-induced undesired effects. These morphological changes were from mild to severe, depending on the presence of after-irradiation undesired effects. © 2014 Wiley Periodicals, Inc.

  4. Determining the field emitter temperature during laser irradiation in the pulsed laser atom probe

    International Nuclear Information System (INIS)

    Kellogg, G.L.

    1981-01-01

    Three methods are discussed for determining the field emitter temperature during laser irradiation in the recently developed Pulsed Laser Atom Probe. A procedure based on the reduction of the lattice evaporation field with increasing emitter temperature is found to be the most convenient and reliable method between 60 and 500 K. Calibration curves (plots of the evaporation field versus temperature) are presented for dc and pulsed field evaporation of W, Mo, and Rh. These results show directly the important influence of the evaporation rate on the temperature dependence of the evaporation field. The possibility of a temperature calibration based on the ionic charge state distribution of field evaporated lattice atoms is also discussed. The shift in the charge state distributions which occurs when the emitter temperature is increased and the applied field strength is decreased at a constant rate of evaporation is shown to be due to the changing field and not the changing temperature. Nevertheless, the emitter temperature can be deduced from the charge state distribution for a specified evaporation rate. Charge state distributions as a function of field strength and temperature are presented for the same three materials. Finally, a preliminary experiment is reported which shows that the emitter temperature can be determined from field ion microscope observations of single atom surface diffusion over low index crystal planes. This last calibration procedure is shown to be very useful at higher temperatures (>600 K) where the other two methods become unreliable

  5. Effect of laser and/or electron beam irradiation on void swelling in SUS316L austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Subing [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Zhanbing, E-mail: yangzhanbing@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Hui [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Watanabe, Seiichi; Shibayama, Tamaki [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan)

    2017-05-15

    Large amounts of void swelling still limit the application of austenitic stainless steels in nuclear reactors due to radiation-induced lattice point defects. In this study, laser and/or beam irradiation was conducted in a temperature range of 573–773 K to explore the suppression of void swelling. The results show that during sequential laser-electron beam irradiation, the void nucleation is enhanced because of the vacancy clusters and void nuclei formed under pre-laser irradiation, causing greater void swelling than single electron beam irradiation. However, simultaneous laser-electron dual-beam irradiation exhibits an obvious suppression effect on void swelling due to the enhanced recombination between interstitials and vacancies in the temperature range of 573–773 K; especially at 723 K, the swelling under simultaneous dual-beam irradiation is 0.031% which is only 22% of the swelling under electron beam irradiation (0.137%). These results provide new insight into the suppression of void swelling during irradiation. - Highlights: •The temperature dependence of void swelling under simultaneous laser-electron dual-beam irradiation has been investigated. •Pre-laser irradiation enhances void nucleation at temperatures from 573 K to 773 K. •Simultaneous laser-electron dual-beam irradiation suppresses void swelling in the temperature range of 573–773 K.

  6. Study on Dental Treatment with YAG Laser (1st Report): Temperature of Dental Tissue Irradiated with Laser Beam

    OpenAIRE

    上田, 隆司; 山田, 啓司; 古本, 達明

    2000-01-01

    The flash temperature of a dental hard tissue irradiated with pulsed Nd:YAG laser is measured using a two-color pyrometer with an optical fiber. This pyrometer consists of a chalcogenide optical fiber and a laminated infrared detector. The influence of the laser power on the temperature of the dental tissue is investigated, and the relationship between the laser power and the removal volume of the dental tissue is obtained. In order to examine the thermal damage on the dental tissue, hardness...

  7. Charged particle and laser irradiation of selected materials

    International Nuclear Information System (INIS)

    Svendsen, W.E.

    1996-11-01

    The main topics of the present thesis are the processes governing electronic sputtering of insulators and laser ablation of metals and insulators. The sputtering yield for electron bombardment of solid deuterium was investigated using quartz crystal microbalances as the measuring technique. The sputtering yield was measured with varying electron energy and deuterium film thickness. Laser ablation measurements of silver and nickel were carried out using a Nd:YAG laser. The effect of various experimental parameters such as background gas pressure (Ar, N 2 ), position of quartz crystals with respect to target position and the optimal number of laser shots for carrying out the experiments were investigated. The deposition rate was measured with varying laser wavelength and laser fluence. The angular distribution of the ablated material was measured for silver as well. A theoretical model based on the thermal properties of laser interaction with metals was applied in the initial phase of ablation. For the non-thermal processes governing laser interaction with the ablated plasma plume, a model developed by Phipps and Dreyfus was used to interpret the results. Laser ablation measurements of water-ice were carried using a Nitrogen laser. Attempts were made to measure the deposition rate for various the laser wavelengths and energies. (au) 8 tabs., 49 ills., 77 refs

  8. Charged particle and laser irradiation of selected materials

    Energy Technology Data Exchange (ETDEWEB)

    Svendsen, W E

    1996-11-01

    The main topics of the present thesis are the processes governing electronic sputtering of insulators and laser ablation of metals and insulators. The sputtering yield for electron bombardment of solid deuterium was investigated using quartz crystal microbalances as the measuring technique. The sputtering yield was measured with varying electron energy and deuterium film thickness. Laser ablation measurements of silver and nickel were carried out using a Nd:YAG laser. The effect of various experimental parameters such as background gas pressure (Ar, N{sub 2}), position of quartz crystals with respect to target position and the optimal number of laser shots for carrying out the experiments were investigated. The deposition rate was measured with varying laser wavelength and laser fluence. The angular distribution of the ablated material was measured for silver as well. A theoretical model based on the thermal properties of laser interaction with metals was applied in the initial phase of ablation. For the non-thermal processes governing laser interaction with the ablated plasma plume, a model developed by Phipps and Dreyfus was used to interpret the results. Laser ablation measurements of water-ice were carried using a Nitrogen laser. Attempts were made to measure the deposition rate for various the laser wavelengths and energies. (au) 8 tabs., 49 ills., 77 refs.

  9. Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Primo, Gastón A.; Alvarez Igarzabal, Cecilia I. [IMBIV (CONICET), Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba X5000HUA (Argentina); Pino, Gustavo A.; Ferrero, Juan C. [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina); Rossa, Maximiliano, E-mail: mrossa@fcq.unc.edu.ar [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina)

    2016-04-30

    Graphical abstract: - Highlights: • Laser-induced surface modification of crosslinked hydrophilic co-polymers by ns pulses. • Formation of ablation craters observed under most of the single-pulse experimental conditions. • UV laser foaming of dried hydrogel samples resulting from single- and multiple-pulse experiments. • Threshold values of the incident laser fluence reported for the observed surface modifications. • Lower threshold fluences for acrylate-based, compared to acrylamide-based hydrogels. - Abstract: This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

  10. Ultrastructural analysis of root canal dentine irradiated with 980-nm diode laser energy at different parameters.

    Science.gov (United States)

    Marchesan, Melissa Andréia; Brugnera-Junior, Aldo; Souza-Gabriel, Aline Evangelista; Correa-Silva, Silvio Rocha; Sousa-Neto, Manoel D

    2008-06-01

    The purpose of this in vitro study was to investigate using the scanning electron microscope (SEM) the ultrastructural morphological changes of the radicular dentine surface after irradiation with 980-nm diode laser energy at different parameters and angles of incidence. There have been limited reports on the effects of diode laser irradiation at 980 nm on radicular dentin morphology. Seventy-two maxillary canines were sectioned and roots were biomechanically prepared using K3 rotary instruments. The teeth were irrigated with 2 mL of distilled water between files and final irrigation was performed with 10 mL of distilled water. The teeth were then randomly divided into five groups (n = 8 each) according to their diode laser parameters: Group 1: no irradiation (control); group 2: 1.5 W/continuous wave (CW) emission (the manufacturer's parameters); group 3: 1.5 W/100 Hz; group 4: 3 W/CW; and group 5: 3 W/100 Hz. Laser energy was applied with helicoid movements (parallel to the canal walls) for 20 sec. Eight additional teeth for each group were endodontically prepared and split longitudinally and irradiation was applied perpendicularly to the root surface. Statistical analysis showed no difference between the root canal thirds irradiated with the 980-nm diode laser, and similar results between the parameters 1.5 W/CW and 3 W/100 Hz (p > 0.05). When considering different output powers and delivery modes our results showed that changes varied from smear layer removal to dentine fusion.

  11. Nano-pulsed laser irradiation scanning system for phase-change materials

    International Nuclear Information System (INIS)

    Kim, Sookyung; Li Xuezhe; Lee, Sangbin; Kim, Kyung-Ho; Lee, Seung-Yop

    2008-01-01

    Recently, the demand of a laser irradiation tester is increasing for phase change random access memory (PRAM) as well as conventional optical storage media. In this study, a nano-pulsed laser irradiation system is developed to characterize the optical property and writing performance of phase-change materials, based on a commercially available digital versatile disk (DVD) optical pick-up. The precisely controlled focusing and scanning on the material's surface are implemented using the auto-focusing mechanism and a voice coil motor (VCM) of the commercial DVD pick-up. The laser irradiation system provides various writing and reading functions such as adjustable laser power, pulse duration, recording pattern (spot, line and area), and writing/reading repetition, phase transition, and in situ reflectivity measurement before/after irradiation. Measurements of power time effect (PTE) diagram and reflectivity map of Ge 2 Sb 2 Te 5 samples show that the proposed laser irradiation system provides the powerful scanning tool to quantify the optical characteristics of phase-change materials

  12. Sub ablative Er: YAG laser irradiation on surface roughness of eroded dental enamel.

    Science.gov (United States)

    Curylofo-Zotti, Fabiana Almeida; Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2015-11-01

    This study evaluated the effects of Er:YAG laser irradiation applied at varying pulse repetition rate on the surface roughness of eroded enamel. Bovine enamel slabs (n = 10) were embedded in polyester resin, ground, and polished. To erosive challenges, specimens were immersed two times per day in 20mL of concentrated orange juice (pH = 3.84) under agitation, during a two-day period. Specimens were randomly assigned to irradiation with the Er:YAG laser (focused mode, pulse energy of 60 mJ and energy density of 3.79 J/cm(2) ) operating at 1, 2, 3, or 4 Hz. The control group was left nonirradiated. Surface roughness measurements were recorded post erosion-like formation and further erosive episodes by a profilometer and observed through atomic force microscopy (AFM). Analysis of variance revealed that the control group showed the lowest surface roughness, while laser-irradiated substrates did not differ from each other following post erosion-like lesion formation. According to analysis of covariance, at further erosive episodes, the control group demonstrated lower surface roughness (P > 0.05), than any of the irradiated groups (P enamel eroded. The AFM images showed that the specimens irradiated by the Er:YAG laser at 1 Hz presented a less rough surface than those irradiated at 2, 3, and 4 Hz. © 2015 Wiley Periodicals, Inc.

  13. Changes in surface morphology of enamel after Er:YAG laser irradiation

    Science.gov (United States)

    Rechmann, Peter; Goldin, Dan S.; Hennig, Thomas

    1998-04-01

    Aim of the study was to investigate the surface and subsurface structure of enamel after irradiation with an Er:YAG laser (wavelength 2.94 micrometer, pulse duration 250 - 500 microseconds, free running, beam profile close to tophead, focus diameter 600 micrometer, focus distance 13 mm, different power settings, air-water spray 2 ml/min; KAVO Key Laser 1242, Kavo Biberach, Germany). The surface of more than 40 freshly extracted wisdom teeth were irradiated using a standardized application protocol (pulse repetition rate 4 and 6 Hz, moving speed of the irradiation table 2 mm/sec and 3 mm/sec, respectively). On each surface between 3 and 5 tracks were irradiated at different laser energies (60 - 500 mJ/pulse) while each track was irradiated between one and ten times respectively. For the scanning electron microscope investigation teeth were dried in alcohol and sputtered with gold. For light microscopic examinations following laser impact, samples were fixed in formaldehyde, dried in alcohol and embedded in acrylic resin. Investigations revealed that at subsurface level cracks can not be observed even at application of highest energies. Borders of the irradiated tracks seem to be sharp while melted areas of different sizes are observed on the bottom of the tracks depending on applied energy. Small microcracks can be seen on the surface of these melted areas.

  14. Shock dynamics induced by double-spot laser irradiation of layered targets

    Directory of Open Access Journals (Sweden)

    Aliverdiev Abutrab A.

    2015-06-01

    Full Text Available We studied the interaction of a double-spot laser beam with targets using the Prague Asterix Laser System (PALS iodine laser working at 0.44 μm wavelength and intensity of about 1015 W/cm2. Shock breakout signals were recorder using time-resolved self-emission from target rear side of irradiated targets. We compared the behavior of pure Al targets and of targets with a foam layer on the laser side. Results have been simulated using hydrodynamic numerical codes.

  15. Study of non-thermal effects from laser radiation on live tissues

    International Nuclear Information System (INIS)

    Cotta, M.A.

    1987-02-01

    The functional biological effects related to the irradiation of live tissues with low power lasers, called non-thermal effects were theoretical and experimentally studied. For the experimental part, a device which allows to: irradiation lesions artificially created on the back of rats by a He-Ne laser, or put a moving ground glass in front of the laser beam, by irradiation of this same laser with its coherence degree decreased. The relevance of the radiation coherence in the lesion cicatrization process was shown. The electrical field distribution and the intensity distribution on a surface with micro-roughness when irradiated by coherent light are theoretically studied. (M.C.K.) [pt

  16. Laser pulse heating of steel mixing with WC particles in a irradiated region

    Science.gov (United States)

    Shuja, S. Z.; Yilbas, B. S.; Ali, H.; Karatas, C.

    2016-12-01

    Laser pulse heating of steel mixing with tungsten carbide (WC) particles is carried out. Temperature field in the irradiated region is simulated in line with the experimental conditions. In the analysis, a laser pulse parameter is introduced, which defines the laser pulse intensity distribution at the irradiated surface. The influence of the laser parameter on the melt pool size and the maximum temperature increase in the irradiated region is examined. Surface temperature predictions are compared with the experimental data. In addition, the distribution of WC particles and their re-locations in the treated layer, due to combination of the natural convection and Marangoni currents, are predicted. The findings are compared to the experimental data. It is found that surface temperature predictions agree well with the experimental data. The dislocated WC particles form a streamlining in the near region of the melt pool wall, which agree with the experimental findings. The Gaussian distribution of the laser pulse intensity results in the maximum peak temperature and the maximum flow velocity inside the melt pool. In this case, the melt pool depth becomes the largest as compared to those corresponding to other laser pulse intensity distributions at the irradiated surface.

  17. Inhibition of Escherichia coli respiratory enzymes by short visible femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Lu, Chieh-Han; Hsu, Yung-Yuan; Lin, Kung-Hsuan; Tsen, Kong-Thon; Kuan, Yung-Shu

    2014-01-01

    A visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner. However, the mechanism of how a visible femtosecond laser affects the viability of different microorganisms is still elusive. In this paper, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E. coli) irradiated by a visible femtosecond laser (λ = 415 nm, pulse width = 100 fs) with different exposure times were investigated. Our results showed that femtosecond laser treatment for 60 min led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of the E. coli cell membrane. In comparison, a 10 min exposure of bacteria to femtosecond laser irradiation induced an immediate reduction of 75% in the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected. Results from enzymatic assays showed that oxidases and dehydrogenases involved in the E. coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to have a dominant effect on the early stage of bacteria inactivation. (paper)

  18. Ablation from artificial or laser-induced crater surfaces of silver by laser irradiation at 355 nm

    DEFF Research Database (Denmark)

    Toftmann, B.; Schou, Jørgen; Larsen, N.B.

    1999-01-01

    The angular distribution of laser ablated particles from silver irradiated at 355 nm has been studied. The angular distribution from craters prepared by more than 10(4) shots exhibits only minor changes compared with that from a nonirradiated target. The distribution from artificial cylindrical c...... craters of a depth comparable to the laser spot dimensions is about one order of magnitude smaller at large exit angles than that from a flat target.......The angular distribution of laser ablated particles from silver irradiated at 355 nm has been studied. The angular distribution from craters prepared by more than 10(4) shots exhibits only minor changes compared with that from a nonirradiated target. The distribution from artificial cylindrical...

  19. Laser polarization dependence of proton emission from a thin foil target irradiated by a 70 fs, intense laser pulse

    International Nuclear Information System (INIS)

    Fukumi, A.; Nishiuchi, M.; Daido, H.; Li, Z.; Sagisaka, A.; Ogura, K.; Orimo, S.; Kado, M.; Hayashi, Y.; Mori, M.; Bulanov, S.V.; Esirkepov, T.; Nemoto, K.; Oishi, Y.; Nayuki, T.; Fujii, T.; Noda, A.; Nakamura, S.

    2005-01-01

    A study of proton emission from a 3-μm-thick Ta foil target irradiated by p-, s-, and circularly polarized laser pulses with respect to the target plane has been carried out. Protons with energies up to 880 keV were observed in the target normal direction under the irradiation by the p-polarized laser pulse, which yielded the highest efficiency for proton emission. In contrast, s- and circularly polarized laser pulses gave the maximum energies of 610 and 680 keV, respectively. The difference in the maximum energy between the p- and s-polarized cases was associated with the difference between the sheath fields estimated from electron spectra

  20. Demonstration of a neonlike argon soft-x-ray laser with a picosecond-laser-irradiated gas puff target.

    Science.gov (United States)

    Fiedorowicz, H; Bartnik, A; Dunn, J; Smith, R F; Hunter, J; Nilsen, J; Osterheld, A L; Shlyaptsev, V N

    2001-09-15

    We demonstrate a neonlike argon-ion x-ray laser, using a short-pulse laser-irradiated gas puff target. The gas puff target was formed by pulsed injection of gas from a high-pressure solenoid valve through a nozzle in the form of a narrow slit and irradiated with a combination of long, 600-ps and short, 6-ps high-power laser pulses with a total of 10 J of energy in a traveling-wave excitation scheme. Lasing was observed on the 3p (1)S(0)?3s (1)P(1) transition at 46.9 nm and the 3d (1)P(1)?3p (1)P(1) transition at 45.1 nm. A gain of 11 cm(-1) was measured on these transitions for targets up to 0.9 cm long.

  1. Enhanced mass removal due to phase explosion during high irradiance nanosecond laser ablation of silicon

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jong Hyun [Univ. of California, Berkeley, CA (United States)

    2000-05-01

    The morphology of craters resulting from high irradiance laser ablation of silicon was measured using a white light interferometry microscope. The craters show a dramatic increase in their depth and volume at a certain irradiance, indicating a change in the primary mechanism for mass removal. Laser shadowgraph imaging was used to characterize and differentiate the mass ejection processes for laser irradiances above and below the threshold value. Time-resolved images show distinct features of the mass ejected at irradiances above the threshold value including the presence of micron-sized particulates; this begins at approximately 300 ~ 400 ns after the start of laser heating. The analysis of the phenomena was carried out by using two models: a thermal evaporation model and a phase explosion model. Estimation of the crater depth due to the thermally evaporated mass led to a large underestimation of the crater depth for irradiances above the threshold. Above the threshold irradiance, the possibility of phase explosion was analyzed. Two important results are the thickness of the superheated liquid layer that is close to the critical temperature and the time for vapor bubbles that are generated in the superheated liquid to achieve a critical size. After reaching the critical size, vapor bubbles can grow spontaneously resulting in a violent ejection of liquid droplets from the superheated volume. The effects of an induced transparency, i.e. of liquid silicon turning into an optically transparent liquid dielectric medium, are also introduced. The estimated time for a bubble to reach the critical size is in agreement with the delay time measured for the initiation of large mass ejection. Also, the thickness of the superheated liquid layer that is close to the critical temperature at the time of the beginning of the large mass ejection is representative of the crater depth at the threshold irradiance. These results suggest that phase explosion is a plausible thermal

  2. Laboratory investigation of the efficacy of holmium:YAG laser irradiation in removing intracanal debris

    Science.gov (United States)

    Nuebler-Moritz, Michael; Gutknecht, Norbert; Sailer, Hermann F.; Hering, Peter; Prettl, Wilhelm

    1997-05-01

    Current endodontic therapy involves debridement and disinfection of the root canal by means of mechanical instrumentation and chemical irrigation. However, several studies have shown that these techniques fail to achieve complete cleansing. Recently, lasers have been suggested for use within root canals. This study was conducted to determine the efficacy of Holmium:YAG laser irradiation in removing intracanal debris and smear layer. Root canal surfaces of freshly-extracted human teeth were exposed to pulsed Ho:YAG laser radiation. Subsequently, laser induced structural changes were investigated using scanning electron microscopy. Temperature measurements during irradiation were performed by means of thermocouples. The result of this survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment survey give a preliminary indication of the ability of the Ho:YAG laser to improve current endodontic treatment modalities. However, limitations exist with regard to circumscribed and well-quantified irradiation of root canal surfaces, due to the lack of perpendicular delivery of the laser beam. Additional studies will be required to develop suitable optical transmission systems, in order to achieve complete cleansing and to avoid damage to the periradicular tissues, respectively.

  3. Formation of silver microbelt structures by laser irradiation of silver nanoparticles in ethanol

    Directory of Open Access Journals (Sweden)

    Zamiri R

    2011-10-01

    Full Text Available Reza Zamiri1, Azmi Zakaria1,2, Mohd Shahril Husin1, Zaidan Abd Wahab1, Forough Kalaei Nazarpour3 1Department of Physics, Faculty of Science, 2Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, 3Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia Abstract: In the present work, we prepared silver nanoparticles by laser ablation of pure silver plate in ethanol and then irradiated the silver nanoparticles using a 532 nm Q-switched Nd:YAG pulsed laser. Transmission electron microscopic images of the sample after irradiation clearly showed formation of big structures, such as microrods and microbelts in ethanol. The obtained microbelts had a width of about 0.166 µm and a length of 1.472 µm. The reason for the formation of such a big structure is the tendency of the nanoparticles to aggregate in ethanol before irradiation, which causes fusion of the nanoparticles. Keywords: nanomaterial, laser ablation, nanoparticles

  4. Formation of novel reactive intermediate by electron-laser dual beam irradiation

    International Nuclear Information System (INIS)

    Ishida, Akito; Takamuku, Setsuo

    1992-01-01

    The pulse radiolysis system of the Institute of Scientific and Industrial Research, Osaka University, (ISIR) has been progressed to observe a highly reactive species, which is produced by successive irradiation of electron and laser or of CW-UV-light and electron. The dual beam irradiation system, which consists of the beam synchronization system, the optical alignment, and the measurement system, is described in detail. Dual beam irradiation studies on 2-methylbenzophenone and some compounds with a C=N bond have been carried out by use of this system. Pulse radiolysis of 2-methylbenzophenone in benzene induced formation of an unstable photoenol via the triplet state, which was irradiated by a visible laser pulse to give dihydroanthrone. Pulse radiolysis of syn-benzalaniline and a nitrileylide in 2-methyltetrahydrofuran, which were produced by steady state photoirradiation at low temperature, enabled us to observe their very unstable radical anions. (author)

  5. Photoacoustic spectroscopy applied to the study of the influence of laser irradiation on corn seeds

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Aguilar, C.; Michtchenko, A. [Instituto Politecnico Nacional (Mexico); Carballo, A. [Colegio de Postgraduados, Programa de Semillas (IREGEP) (Mexico); Cruz-Orea, A. [Centro de Investigacion y de Estudios Avanzados-IPN (Mexico); Ivanov, R. [Universidad Autonoma de Zacatecas, Unidad Academia de Fisica (Mexico); San Martin Martinez, E. [Centro de Investigacion en ciencia Aplicada y Tecnologia Avanzada-IPN (Mexico)

    2005-06-01

    In the present study we were interested in the effects of low intensity laser irradiation on hybrid corn seeds CL{sub 1} x CL{sub 4} when these seeds were exposed to different laser intensities and irradiation times. In order to observe qualitative differences in chlorophyll a and b optical absorption spectra of seedling's leaves, whose seeds were irradiated and non irradiated, were obtained by using photoacoustic spectroscopy (PAS). A randomized complete blocks experimental design with three replications was used. The experimental unit included 10 seeds, from which we randomly choose three seedlings. The variance analysis (ANOVA) for both chlorophylls revealed significant (P < 0.05) differences among treatments. (authors)

  6. Repair bond strength of composite resin to sandblasted and laser irradiated Y-TZP ceramic surfaces.

    Science.gov (United States)

    Kirmali, Omer; Barutcigil, Çağatay; Ozarslan, Mehmet Mustafa; Barutcigil, Kubilay; Harorlı, Osman Tolga

    2015-01-01

    This study investigated the effects of different surface treatments on the repair bond strength of yttrium-stabilized tetragonal zirconia polycrystalline ceramic (Y-TZP) zirconia to a composite resin. Sixty Y-TZP zirconia specimens were prepared and randomly divided into six groups (n = 10) as follows: Group 1, surface grinding with Cimara grinding bur (control); Group 2, sandblasted with 30 µm silica-coated alumina particles; Group 3, Nd:YAG laser irradiation; Group 4, Er,Cr:YSGG laser irradiation; Group 5, sandblasted + Nd:YAG laser irradiation; and Group 6, sandblasted + Er,Cr:YSGG laser irradiation. After surface treatments, the Cimara(®) System was selected for the repair method and applied to all specimens. A composite resin was built-up on each zirconia surface using a cylindrical mold (5 × 3 mm) and incrementally filled. The repair bond strength was measured with a universal test machine. Data were analyzed using a one-way ANOVA and a Tukey HSD test (p = 0.05). Surface topography after treatments were evaluated by a scanning electron microscope (SEM). Shear bond strength mean values ranged from 15.896 to 18.875 MPa. There was a statistically significant difference between group 3 and the control group (p < 0.05). Also, a significant increase in bond strength values was noted in group 6 (p < 0.05). All surface treatment methods enhanced the repair bond strength of the composite to zirconia; however, there were no significant differences between treatment methods. The results revealed that Nd:YAG laser irradiation along with the combination of sandblasting and Er,Cr:YSGG laser irradiation provided a significant increase in bond strength between the zirconia and composite resin. © Wiley Periodicals, Inc.

  7. Does laser diode irradiation improve the degree of conversion of simplified dentin bonding systems?

    Directory of Open Access Journals (Sweden)

    Leticia Ferreira de Freitas BRIANEZZI

    Full Text Available Abstract Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC, water sorption (WS, and water solubility (WSB of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU]. Square-shaped specimens were prepared and assigned into 4 groups (n=5: SB and SU (control groups – no laser irradiation and SB-L and SU-L [SB and SU laser (L – irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5 of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10 were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm, irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2. Results Laser irradiation immediately before photopolymerization increased the DC (% of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3, only the dentin bonding system (DBS was a significant factor (pSU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

  8. Nanosecond pulsed laser nanostructuring of Au thin films: Comparison between irradiation at low and atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Aké, C., E-mail: citlali.sanchez@ccadet.unam.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico); Canales-Ramos, A. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico); García-Fernández, T. [Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, Col. San Lorenzo Tezonco, México D.F., C.P. 09790 (Mexico); Villagrán-Muniz, M. [Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Circuito Exterior S/N, C. U., Delegación Coyoacán, C.P. 04510, México D.F. (Mexico)

    2017-05-01

    Highlights: • Background pressure plays an important role in NPs formation and its characteristics. • The NPs diameter and their size dispersion are smaller when irradiating in vacuum. • The plasmon resonance shifts ∼15 nm to higher frequencies when irradiating in vacuum. • Film partial ablation cannot be neglected for thickness in the range 40–80 nm. • In situ optical techniques monitor the timescale of the process and ablation dynamics. - Abstract: Au thin films with tens of nm in thickness deposited on glass substrates were irradiated with nanosecond UV (355 nm) laser pulses at atmospheric pressure and in vacuum conditions (∼600 and 10{sup −5} Torr). We studied the effect of the laser fluence (200–400 mJ/cm{sup 2}), thickness of the starting film (∼40–80 nm) and surrounding pressure on the partial ablation/evaporation of the films and the morphology of the produced nanoparticles (NPs). The dynamics of NPs formation was studied by measuring in real time the transmission of the samples upon continuous-wave laser exposure, and by means of probe beam deflection technique. The ejection of material from the film as a result of the irradiation was confirmed by time-resolved shadowgraphy technique. Experiments show that the NPs diameter and their size distribution are smaller when the irradiation is performed in vacuum regardless the laser fluence and thickness of the started film. It is also shown that the plasmon band shifts to higher frequencies with lower background pressure. The optical measurements show that the films melt and ablate during the laser pulse, but the transmission of the irradiated areas continues changing during tens of microseconds due to ejection of material and solidification of the remaining gold. Our results indicate that partial ablation cannot be neglected in nanostructuration by ns-pulsed irradiation of thin films when their thickness is in the studied range.

  9. Ionization mechanism of cesium plasma produced by irradiation of dye laser

    International Nuclear Information System (INIS)

    Yamada, Jun; Shibata, Kohji; Uchida, Yoshiyuki; Hioki, Yoshiaki; Sahashi, Toshio.

    1992-01-01

    When a cesium vapor was irradiated by a dye laser which was tuned to the cesium atomic transition line, the number of charged particles produced by the laser radiation was observed. Several sharp peaks in the number of charged particles were observed, which corresponded to the atomic transition where the lower level was the 6P excited atom. The ionization mechanism of the laser-produced cesium plasma has been discussed. An initial electron is produced by laser absorptions of the cesium dimer. When the cesium density is high, many 6P excited atoms are excited by electron collisions. The 6P excited atom further absorbs the laser photon and is ionized through the higher-energy state. As the cesium vapor pressure increases, the resonance effect becomes observable. The 6P excited atom plays dominant role in the ionization mechanism of the laser-produced cesium plasma. (author)

  10. Study of silica coatings degradation under laser irradiation and in controlled environment

    International Nuclear Information System (INIS)

    Becker, S.

    2006-11-01

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

  11. Advanced targets preparation for TNSA laser irradiation and their characterization

    Czech Academy of Sciences Publication Activity Database

    Ceccio, G.; Torrisi, L.; Cutroneo, Mariapompea

    2016-01-01

    Roč. 11, APR (2016), C04017 ISSN 1748-0221. [Conference on Plasma Physics by Laser and Applications (PPLA). Frascati, 05.10.2015-07.10.2015] Institutional support: RVO:61389005 Keywords : TOF * ion sources * plasma diagnostics Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.220, year: 2016

  12. Electron ionization and spin polarization control of Fe atom adsorbed graphene irradiated by a femtosecond laser

    International Nuclear Information System (INIS)

    Yu, Dong; Jiang, Lan; Wang, Feng; Li, Xin; Qu, Liangti; Lu, Yongfeng

    2015-01-01

    We investigate the structural properties and ionized spin electrons of an Fe–graphene system, in which the time-dependent density functional theory (TDDFT) within the generalized gradient approximation is used. The electron dynamics, including electron ionization and ionized electron spin polarization, is described for Fe atom adsorbed graphene under femtosecond laser irradiation. The theoretical results show that the electron ionization and ionized electron spin polarization are sensitive to the laser parameters, such as the incident angle and the peak intensity. The spin polarization presents the maximum value under certain laser parameters, which may be used as a source of spin-polarized electrons. - Highlights: • The structural properties of Fe–graphene system are investigated. • The electron dynamics of Fe–graphene system under laser irradiation are described. • The Fe–graphene system may be used as a source of spin-polarized electrons

  13. Pyrolysis responses of kevlar/epoxy composite materials on laser irradiating

    Science.gov (United States)

    Liu, Wei-ping; Wei, Cheng-hua; Zhou, Meng-lian; Ma, Zhi-liang; Song, Ming-ying; Wu, Li-xiong

    2017-05-01

    The pyrolysis responses of kevlar/epoxy composite materials are valuable to study in a case of high temperature rising rate for its widely application. Distinguishing from the Thermal Gravimetric Analysis method, an apparatus is built to research the pyrolysis responses of kevlar/epoxy composite materials irradiated by laser in order to offer a high temperature rising rate of the sample. By deploying the apparatus, a near real-time gas pressure response can be obtained. The sample mass is weighted before laser irradiating and after an experiment finished. Then, the gas products molecular weight and the sample mass loss evolution are derived. It is found that the pressure and mass of the gas products increase with the laser power if it is less than 240W, while the molecular weight varies inversely. The variation tendency is confusing while the laser power is bigger than 240W. It needs more deeper investigations to bring it to light.

  14. X-ray imaging of targets irradiated by the Nike KrF laser

    International Nuclear Information System (INIS)

    Brown, C.; Seely, J.; Feldman, U.; Obenschain, S.; Bodner, S.; Pawley, C.; Gerber, K.; Serlin, V.; Sethian, J.; Aglitskiy, Y.; Lehecka, T.; Holland, G.

    1997-01-01

    Foil targets irradiated by the Naval Research Laboratory Nike KrF laser were imaged in the x-ray region with two-dimensional spatial resolution in the 2 endash 10 μm range. The images revealed the smoothness of the emission from target and backlighter foils, the acceleration of the target foils, and the growth of Rayleigh endash Taylor instabilities that were seeded by patterns on the irradiated sides of CH foils

  15. Results of presowing helium-neon-laser irradiation of sunflower seeds

    International Nuclear Information System (INIS)

    Tsvetanova, K.

    1989-01-01

    In the period of 1983-1985 under non-irrigation, on calcareous chernozem a trial was carried out with the Start hybrid through single-, double-and triple irradiation of the seeds being stored for 1.8 and 16 days prior to sowing. It is found that the presowing helium-neon-laser irradiation of the sunflower seeds of the Start hybrid exerts a negative effect on the seed yield. Laser use does not stimulate the following: emerged seeds and percentage of the plants being in blossom in the beginning of the phase and after 7 days, seed moisture in harvesting and oil content in them

  16. Time-resolved x-ray spectra of laser irradiated high-Z targets

    International Nuclear Information System (INIS)

    Lee, P.H.Y.; Attwood, D.T.; Boyle, M.J.; Campbell, E.M.; Coleman, L.C.; Kornblum, H.N.

    1977-01-01

    Recent results obtained by using the Livermore 15 psec x-ray streak camera to record x-ray emission from laser-irradiated high-z targets in the 1-20 keV range are reported. Nine to eleven K-edge filter channels were used for the measurements. In the lower energy channels, a dynamic range of x-ray emission intensity of better than three orders of magnitude have been recorded. Data will be presented which describe temporally and spectrally resolved x-ray spectra of gold disk targets irradiated by laser pulses from the Argus facility, including the temporal evolution of the superthermal x-ray tail

  17. Perspectives on Low Power and Shutdown Risk

    International Nuclear Information System (INIS)

    Camp, Allen L.; Whitehead, Donnie W.; Wheeler, Timothy A.; Lehner, John; Chu, Tsong-Lun; Lois, Erasmai; Drouin, Mary

    2000-01-01

    This paper presents results from a program sponsored by the US Nuclear Regulatory Commission to examine the risks from low power and shutdown operations. Significant progress has been made by the industry in reducing such risks; however, important operational events continue to occur. Current perceptions of low power and shutdown risks are discussed in the paper along with an assessment of the current methods for understanding important events and quantifying their associated risk

  18. Ultra low power full adder topologies

    DEFF Research Database (Denmark)

    Moradi, Farshad; Wisland, Dag T.; Mahmoodi, Hamid

    In this paper several low power full adder topologies are presented. The main idea of these circuits is based on the sense energy recovery full adder (SERF) design and the GDI (gate diffusion input) technique. These subthreshold circuits are employed for ultra low power applications. While the pr...... the proposed circuits have some area overhead that is negligible, they have at least 62% less power dissipation when compared with existing designs. In this paper, 65 nm standard models are used for simulations....

  19. Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

    International Nuclear Information System (INIS)

    Barboza, Carlos Augusto Galvão; Ginani, Fernanda; Soares, Diego Moura; Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida

    2014-01-01

    To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm"2). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm"2, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm"2, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering

  20. Semiconductor laser irradiation improves root canal sealing during routine root canal therapy

    Science.gov (United States)

    Hu, Xingxue; Wang, Dashan; Cui, Ting; Yao, Ruyong

    2017-01-01

    Objective To evaluate the effect of semiconductor laser irradiation on root canal sealing after routine root canal therapy (RCT). Methods Sixty freshly extracted single-rooted human teeth were randomly divided into six groups (n = 10). The anatomic crowns were sectioned at the cementoenamel junction and the remaining roots were prepared endodontically with conventional RCT methods. Groups A and B were irradiated with semiconductor laser at 1W for 20 seconds; Groups C and D were ultrasonically rinsed for 60 seconds as positive control groups; Groups E and F without treatment of root canal prior to RCT as negative control groups. Root canal sealing of Groups A, C and E were evaluated by measurements of apical microleakage. The teeth from Groups B, D and F were sectioned, and the micro-structures were examined with scanning electron microscopy (SEM). One way ANOVA and LSD-t test were used for statistical analysis (α = .05). Results The apical sealing of both the laser irradiated group and the ultrasonic irrigated group were significantly different from the control group (pirrigated group (p>0.5). SEM observation showed that most of the dentinal tubules in the laser irradiation group melted, narrowed or closed, while most of the dentinal tubules in the ultrasonic irrigation group were filled with tooth paste. Conclusion The application of semiconductor laser prior to root canal obturation increases the apical sealing of the roots treated. PMID:28957407

  1. Low-level laser irradiation induces in vitro proliferation of mesenchymal stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Barboza, Carlos Augusto Galvão; Ginani, Fernanda [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil); Soares, Diego Moura [Universidade Federal de Pernambuco, Recife, PE (Brazil); Henriques, Águida Cristina Gomes; Freitas, Roseana de Almeida [Universidade Federal do Rio Grande do Norte, Natal, RN (Brazil)

    2014-07-01

    To evaluate the effect of low-level laser irradiation on the proliferation and possible nuclear morphological changes of mouse mesenchymal stem cells. Mesenchymal stem cells derived from bone marrow and adipose tissue were submitted to two applications (T0 and T48 hours) of low-level laser irradiation (660nm; doses of 0.5 and 1.0J/cm{sup 2}). The trypan blue assay was used to evaluate cell viability, and growth curves were used to analyze proliferation at zero, 24, 48, and 72 hours. Nuclear alterations were evaluated by staining with DAPI (4'-6-diamidino-2-phenylindole) at 72 hours. Bone marrow-derived mesenchymal stem cells responded to laser therapy in a dose-dependent manner. Higher cell growth was observed when the cells were irradiated with a dose of 1.0J/cm{sup 2}, especially after 24 hours (p<0.01). Adipose-derived mesenchymal stem cells responded better to a dose of 1.0J/cm{sup 2}, but higher cell proliferation was observed after 48 hours (p<0.05) and 72 hours (p<0.01). Neither nuclear alterations nor a significant change in cell viability was detected in the studied groups. Low-level laser irradiation stimulated the proliferation of mouse mesenchymal stem cells without causing nuclear alterations. The biostimulation of mesenchymal stem cells using laser therapy might be an important tool for regenerative therapy and tissue engineering.

  2. Surface modification of Ti dental implants by Nd:YVO4 laser irradiation

    International Nuclear Information System (INIS)

    Braga, Francisco J.C.; Marques, Rodrigo F.C.; Filho, Edson de A.; Guastaldi, Antonio C.

    2007-01-01

    Surface modifications have been applied in endosteal bone devices in order to improve the osseointegration through direct contact between neoformed bone and the implant without an intervening soft tissue layer. Surface characteristics of titanium implants have been modified by addictive methods, such as metallic titanium, titanium oxide and hydroxyapatite powder plasma spray, as well as by subtractive methods, such as acid etching, acid etching associated with sandblasting by either AlO 2 or TiO 2 , and recently by laser ablation. Surface modification for dental and medical implants can be obtained by using laser irradiation technique where its parameters like repetition rate, pulse energy, scanning speed and fluency must be taken into accounting to the appropriate surface topography. Surfaces of commercially pure Ti (cpTi) were modified by laser Nd:YVO 4 in nine different parameters configurations, all under normal atmosphere. The samples were characterized by SEM and XRD refined by Rietveld method. The crystalline phases αTi, βTi, Ti 6 O, Ti 3 O and TiO were formed by the melting and fast cooling processes during irradiation. The resulting phases on the irradiated surface were correlated with the laser beam parameters. The aim of the present work was to control titanium oxides formations in order to improve implants osseointegration by using a laser irradiation technique which is of great importance to biomaterial devices due to being a clean and reproducible process

  3. Localized Temperature Variations in Laser-Irradiated Composites with Embedded Fiber Bragg Grating Sensors

    OpenAIRE

    R. Brian Jenkins; Peter Joyce; Deborah Mechtel

    2017-01-01

    Fiber Bragg grating (FBG) temperature sensors are embedded in composites to detect localized temperature gradients resulting from high energy infrared laser radiation. The goal is to detect the presence of radiation on a composite structure as rapidly as possible and to identify its location, much the same way human skin senses heat. A secondary goal is to determine how a network of sensors can be optimized to detect thermal damage in laser-irradiated composite materials or structures. Initia...

  4. Lateral propagation of MeV electrons generated by femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Seely, J. F.; Szabo, C. I.; Audebert, P.; Brambrink, E.; Tabakhoff, E.; Hudson, L. T.

    2010-01-01

    The propagation of MeV electrons generated by intense (≅10 20 W/cm 2 ) femtosecond laser irradiation, in the lateral direction perpendicular to the incident laser beam, was studied using targets consisting of irradiated metal wires and neighboring spectator wires embedded in electrically conductive (aluminum) or resistive (Teflon) substrates. The K shell spectra in the energy range 40-60 keV from wires of Gd, Dy, Hf, and W were recorded by a transmission crystal spectrometer. The spectra were produced by 1s electron ionization in the irradiated wire and by energetic electron propagation through the substrate material to the spectator wire of a different metal. The electron range and energy were determined from the relative K shell emissions from the irradiated and spectator wires separated by varying substrate lateral distances of up to 1 mm. It was found that electron propagation through Teflon was inhibited, compared to aluminum, implying a relatively weak return current and incomplete space-charge neutralization. The energetic electron propagation in the direction parallel to the electric field of the laser beam was larger than perpendicular to the electric field. Energetic electron production was lower when directly irradiating aluminum or Teflon compared to irradiating the heavy metal wires. These experiments are important for the determination of the energetic electron production mechanism and for understanding lateral electron propagation that can be detrimental to fast-ignition fusion and hard x-ray backlighter radiography.

  5. Fabrication of SERS Active Surface on Polyimide Sample by Excimer Laser Irradiation

    Directory of Open Access Journals (Sweden)

    T. Csizmadia

    2014-01-01

    Full Text Available A possible application of excimer laser irradiation for the preparation of surface enhanced Raman spectroscopy (SERS substrate is demonstrated. A polyimide foil of 125 μm thickness was irradiated by 240 pulses of focused ArF excimer laser beam (λ = 193 nm, FWHM = 20 ns. The applied fluence was varied between 40 and 80 mJ/cm2. After laser processing, the sample was coated with 40 nm silver by PLD in order to create a conducting layer required for the SERS application. The SERS activity of the samples was tested by Raman microscopy. The Raman spectra of Rhodamine 6G aqueous solution (c=10−3 mol/dm3 were collected from the patterned and metalized areas. For areas prepared at 40–60 mJ/cm2 laser fluences, the measured Raman intensities have shown a linear dependence on the applied laser fluence, while above 60 mJ/cm2 saturation was observed. The morphology of the SERS active surface areas was investigated by scanning electron microscopy. Finite element modeling was performed in order to simulate the laser-absorption induced heating of the polyimide foil. The simulation resulted in the temporal and spatial distribution of the estimated temperature in the irradiated polyimide sample, which are important for understanding the structure formation process.

  6. Ablation, surface activation, and electroless metallization of insulating materials by pulsed excimer laser irradiation

    International Nuclear Information System (INIS)

    Lowndes, D.H.; Godbole, M.J.; Pedraza, A.J.

    1993-01-01

    Pulsed-laser irradiation of wide bandgap ceramic substrates, using photons with sub-bandgap energies, activates the ceramic surface for subsequent electroless copper deposition. The copper deposit is confined within the irradiated region when the substrate is subsequently immersed in an electroless copper bath. However, a high laser fluence (typically several j/cm 2 ) and repeated laser shots are needed to obtain uniform copper coverage by this direct-irradiation process. In contrast, by first applying an evaporated SiO x thin film (with x ∼1), laser ablation at quite low energy density (∼0.5 J/cm 2 ) results in re-deposition on the ceramic substrate of material that is catalytic for subsequent electroless copper deposition. Experiments indicate that the re-deposited material is on silicon, on which copper nucleates. Using an SiO x film on a laser-transparent substrate, quite fine (∼12 μm) copper lines can be formed at the boundary of the region that is laser-etched in SiO x . Using SiO x with an absorbing (polycrystalline) ceramic substrate, more-or-less uniform activation and subsequent copper deposition are obtained. In the later case, interactions with the ceramic substrate also may be important for uniform deposition

  7. Computational science simulation of laser materials processing and provision of their irradiation conditions

    International Nuclear Information System (INIS)

    Muramatsu, Toshiharu

    2016-01-01

    In laser processing, it is necessary for achieving the intended performance and product, to understand the complex physical courses including melting and solidification phenomena occurring in laser processing, and thus to set proper laser irradiation conditions. This condition optimization work requires an enormous amount of overhead due to repeated efforts, and has become a cause for inhibiting the introduction of laser processing technology into the industrial field that points to the small lot production of many products. JAEA tried to make it possible to quantitatively handle the complex physical course from the laser light irradiation to the fabricating material until the completion of processing, and is under development of the computational science simulation code SPLICE that connects micro behavior and macro behavior through a multi-level scale model. This SPLICE is able to visualize the design space and to reduce the overhead associated with the setting of laser irradiation conditions and the like, which gives the prospect of being effective as a tool for front-loading. This approach has been confirmed to be effective for the welding and fusing process. (A.O.)

  8. Mechanism of laser ablation for aqueous media irradiated under confined-stress conditions

    International Nuclear Information System (INIS)

    Oraevsky, A.A.; Jacques, S.L.; Tittel, F.K.

    1995-01-01

    Pulsed laser ablation of aqueous medium irradiated under conditions of temporal confinement of thermal stress is described. Time-resolved measurements of laser-induced transient stress waves with simultaneous imaging of ablation process by laser-flash photography were performed. Stress transients induced in aqueous solution of K 2 CrO 4 by ablative nanosecond laser pulses at 355 nm were studied by a broad-band lithium niobate acoustic transducer. Recoil momentum upon material ejection was measured from the temporal profiles of the acoustic transducer signal as a function of incident laser fluence. Cavitation bubbles produced in the irradiated volume during the tensile phase of thermoelastic stress were shown to drive material ejection at temperatures substantially below 100 degree C. Experimental data are evident that nanosecond-pulse laser ablation of aqueous media (when temporal stress-confinement conditions are satisfied) include the following two main stages of material ejection: (1) ejection of water microdroplets due to expansion and rupture of subsurface cavitation bubbles; (2) ejection of liquid streams with substantial volume upon collapse of initial crater and large cavitation bubbles in the depth of irradiated volume (after coalescence of smaller bubbles). copyright 1995 American Institute of Physics

  9. Application of Laser Micro-irradiation for Examination of Single and Double Strand Break Repair in Mammalian Cells.

    Science.gov (United States)

    Holton, Nathaniel W; Andrews, Joel F; Gassman, Natalie R

    2017-09-05

    Highly coordinated DNA repair pathways exist to detect, excise and replace damaged DNA bases, and coordinate repair of DNA strand breaks. While molecular biology techniques have clarified structure, enzymatic functions, and kinetics of repair proteins, there is still a need to understand how repair is coordinated within the nucleus. Laser micro-irradiation offers a powerful tool for inducing DNA damage and monitoring the recruitment of repair proteins. Induction of DNA damage by laser micro-irradiation can occur with a range of wavelengths, and users can reliably induce single strand breaks, base lesions and double strand breaks with a range of doses. Here, laser micro-irradiation is used to examine repair of single and double strand breaks induced by two common confocal laser wavelengths, 355 nm and 405 nm. Further, proper characterization of the applied laser dose for inducing specific damage mixtures is described, so users can reproducibly perform laser micro-irradiation data acquisition and analysis.

  10. Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

    Directory of Open Access Journals (Sweden)

    Trišić Dijana

    2017-07-01

    Full Text Available Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm, at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

  11. Investigations of ultrafast charge dynamics in laser-irradiated targets by a self probing technique employing laser driven protons

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, H. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Kar, S., E-mail: s.kar@qub.ac.uk [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Cantono, G. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Department of Physics “E. Fermi”, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, Research Unit Adriano Gozzini, via G. Moruzzi 1, Pisa 56124 (Italy); Nersisyan, G. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Brauckmann, S. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany); Doria, D.; Gwynne, D. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Macchi, A. [Department of Physics “E. Fermi”, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica, Research Unit Adriano Gozzini, via G. Moruzzi 1, Pisa 56124 (Italy); Naughton, K. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Willi, O. [Institut für Laser-und Plasmaphysik, Heinrich-Heine-Universität, Düsseldorf (Germany); Lewis, C.L.S.; Borghesi, M. [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom)

    2016-09-01

    The divergent and broadband proton beams produced by the target normal sheath acceleration mechanism provide the unique opportunity to probe, in a point-projection imaging scheme, the dynamics of the transient electric and magnetic fields produced during laser-plasma interactions. Commonly such experimental setup entails two intense laser beams, where the interaction produced by one beam is probed with the protons produced by the second. We present here experimental studies of the ultra-fast charge dynamics along a wire connected to laser irradiated target carried out by employing a ‘self’ proton probing arrangement – i.e. by connecting the wire to the target generating the probe protons. The experimental data shows that an electromagnetic pulse carrying a significant amount of charge is launched along the wire, which travels as a unified pulse of 10s of ps duration with a velocity close to speed of light. The experimental capabilities and the analysis procedure of this specific type of proton probing technique are discussed. - Highlights: • Prompt charging of laser irradiated target generates ultra-short EM pulses. • Its ultrafast propagation along a wire was studied by self-proton probing technique. • Self-proton probing technique is the proton probing with one laser pulse. • Pulse temporal profile and speed along the wire were measured with high resolution.

  12. Morphological modification of TiC by laser irradiation

    International Nuclear Information System (INIS)

    Baechli, A.; Blatter, A.

    1991-01-01

    The technique of laser quenching has been applied to TiC coatings on cemented carbide WC/Co material. In contrast to the original columnar morphology of TiC prepared by chemical vapour deposition, the laser-processed surface is isotropic and flat. With the proper parameters a smooth interface is formed and the TiC is alloyed to the substrate. The chemical composition as well as the beneficial tribological properties can be preserved. (orig.)

  13. Sustainable Entangled State of Two Qutrits Under Laser Irradiation

    Directory of Open Access Journals (Sweden)

    Biryukov A.А.

    2015-01-01

    Full Text Available We study the evolution of quantum entanglement in the model of two identical qubits interacting with a single-mode laser field. The density matrix and Peres-Horodecki parameter are calculated within the frameworks of path-integral formalism. The quantum entanglement measure is shown to be strongly dependent upon the phase difference between the laser radiation acting on each cubit. This observation may offer the possibility of quantum entanglement stationary control by varying the distance between the qubits.

  14. Laser-Irradiated Gas Puff Target Plasma Modeling

    Czech Academy of Sciences Publication Activity Database

    Vrba, Pavel; Vrbová, M.

    2014-01-01

    Roč. 42, č. 10 (2014), s. 2600-2601 ISSN 0093-3813 R&D Projects: GA ČR GAP102/12/2043 Grant - others:GA MŠk(CZ) CZ.1.07/2.3.00/20.0092 Institutional support: RVO:61389021 Keywords : Gas puff laser plasma * water window radiation source * RHMD code Z* Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.101, year: 2014 http://ieeexplore.ieee.org

  15. INTERACTION OF LASER RADIATION WITH MATTER AND OTHER LASER APPLICATIONS: Changes in the emission properties of metal targets during pulse-periodic laser irradiation

    Science.gov (United States)

    Konov, Vitalii I.; Pimenov, S. M.; Prokhorov, A. M.; Chapliev, N. I.

    1988-02-01

    A scanning electron microscope was used with a pulse-periodic CO2 laser to discover the laws governing the correlation of the modified microrelief of metal surfaces, subjected to the action of multiple laser pulses, with the emission of charged particles and the luminescence of the irradiated zone. It was established that the influence of sorption and laser-induced desorption on the emission signals may be manifested differently depending on the regime of current generation in the "target-vacuum chamber" circuit.

  16. Dentinal temperature transients caused by exposure to CO2 laser irradiation and possible pulpal damage.

    Science.gov (United States)

    Jeffrey, I W; Lawrenson, B; Saunders, E M; Longbottom, C

    1990-02-01

    An investigation is described that attempts to establish, in vitro, the characteristics of heat transference following laser irradiation of bovine dentinal tissue and the relationship with the periodicity of radiation. The results of this study appear to indicate that at depths of overlying dentine of up to 3 mm, laser-induced thermal injury to the pulp is a definite possibility. Fail-safe facilities to prevent build up of heat must be incorporated into the design of dental lasers to allow their beneficial effects to be utilized without the risk of iatrogenic damage.

  17. Theory of suppressing avalanche process of carrier in short pulse laser irradiated dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Deng, H. X., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu; Zu, X. T., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu; Xiang, X. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zheng, W. G.; Yuan, X. D. [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Sun, K., E-mail: hxdeng@uestc.edu.cn, E-mail: xtzu@uestc.edu.cn, E-mail: kaisun@umich.edu [Department of Materials Engineering and Sciences, University of Michigan, 413B Space Research Building, Ann Arbor, Michigan 48109-2143 (United States); Gao, F. [Pacific Northwest National Laboratory, P. O. Box 999, Richland, Washington 99352 (United States)

    2014-05-28

    A theory for controlling avalanche process of carrier during short pulse laser irradiation is proposed. We show that avalanche process of conduction band electrons (CBEs) is determined by the occupation number of phonons in dielectrics. The theory provides a way to suppress avalanche process and a direct judgment for the contribution of avalanche process and photon ionization process to the generation of CBEs. The obtained temperature dependent rate equation shows that the laser induced damage threshold of dielectrics, e.g., fused silica, increase nonlinearly with the decreases of temperature. Present theory predicts a new approach to improve the laser induced damage threshold of dielectrics.

  18. Enhanced light scattering in Si nanostructures produced by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Sberna, P. M.; Scapellato, G. G.; Boninelli, S.; Miritello, M.; Crupi, I.; Bruno, E.; Privitera, V.; Simone, F.; Mirabella, S. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania (Italy); Piluso, N. [IMM-CNR, VIII strada 5, 95121 Catania (Italy)

    2013-11-25

    An innovative method for Si nanostructures (NS) fabrication is proposed, through nanosecond laser irradiation (λ = 532 nm) of thin Si film (120 nm) on quartz. Varying the laser energy fluences (425–1130 mJ/cm{sup 2}) distinct morphologies of Si NS appear, going from interconnected structures to isolated clusters. Film breaking occurs through a laser-induced dewetting process. Raman scattering is enhanced in all the obtained Si NS, with the largest enhancement in interconnected Si structures, pointing out an increased trapping of light due to multiple scattering. The reported method is fast, scalable and cheap, and can be applied for light management in photovoltaics.

  19. Measurements of laser generated soft X-ray emission from irradiated gold foils

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J. S.; Keiter, P. A.; Klein, S. R.; Drake, R. P.; Shvarts, D. [University of Michigan, 2455 Hayward St., Ann Arbor, Michigan 48109 (United States); Frank, Y.; Raicher, E.; Fraenkel, M. [Soreq Nuclear Research Center, Yavne (Israel)

    2016-11-15

    Soft x-ray emission from laser irradiated gold foils was measured at the Omega-60 laser system using the Dante photodiode array. The foils were heated with 2 kJ, 6 ns laser pulses and foil thicknesses were varied between 0.5, 1.0, and 2.0 μm. Initial Dante analysis indicates peak emission temperatures of roughly 100 eV and 80 eV for the 0.5 μm and 1.0 μm thick foils, respectively, with little measurable emission from the 2.0 μm foils.

  20. Relativistic electron acceleration by net inverse bremsstrahlung in a laser-irradiated plasma

    International Nuclear Information System (INIS)

    Kim, S.H.; Chen, K.W.

    1985-01-01

    Using the quantum-kinetic method, the net acceleration of relativistic electrons in a laser-irradiated plasma is studied as a function of the relevant parameters of the incident laser wave and the plasma wave. It is suggested that, in general, the net acceleration in laser-produced turbulent plasmas is primarily due to inverse bremsstrahlung proceses, and the acceleration gradient exceeds several hundreds gigavolt per meter when the electron energy is large (TeV) and the momentum spread of the beam is properly controlled

  1. Temperature evaluation of dental implant surface irradiated with high-power diode laser.

    Science.gov (United States)

    Rios, F G; Viana, E R; Ribeiro, G M; González, J C; Abelenda, A; Peruzzo, D C

    2016-09-01

    The prevalence of peri-implantitis and the absence of a standard approach for decontamination of the dental implant surface have led to searches for effective therapies. Since the source of diode lasers is portable, has reduced cost, and does not cause damage to the titanium surface of the implant, high-power diode lasers have been used for this purpose. The effect of laser irradiation on the implants is the elevation of the temperature surface. If this elevation exceeds 47 °C, the bone tissue is irreversibly damaged, so for a safety therapy, the laser parameters should be controlled. In this study, a diode laser of GaAsAl was used to irradiate titanium dental implants, for powers 1.32 to 2.64 W (real) or 2.00 to 4.00 W (nominal), in continuous/pulsed mode DC/AC, with exposure time of 5/10 s, with/without air flow for cooling. The elevation of the temperature was monitored in real time in two positions: cervical and apical. The best results for decontamination using a 968-nm diode laser were obtained for a power of 1.65 and 1.98 W (real) for 10 s, in DC or AC mode, with an air flow of 2.5 l/min. In our perspective in this article, we determine a suggested approach for decontamination of the dental implant surface using a 968-nm diode laser.

  2. Dosimetry of laser-accelerated electron beams used for in vitro cell irradiation experiments

    International Nuclear Information System (INIS)

    Richter, C.; Kaluza, M.; Karsch, L.; Schlenvoigt, H.-P.; Schürer, M.; Sobiella, M.; Woithe, J.; Pawelke, J.

    2011-01-01

    The dosimetric characterization of laser-accelerated electrons applied for the worldwide first systematic radiobiological in vitro cell irradiation will be presented. The laser-accelerated electron beam at the JeTi laser system has been optimized, monitored and controlled in terms of dose homogeneity, stability and absolute dose delivery. A combination of different dosimetric components were used to provide both an online beam as well as dose monitoring and a precise absolute dosimetry. In detail, the electron beam was controlled and monitored by means of an ionization chamber and an in-house produced Faraday cup for a defined delivery of the prescribed dose. Moreover, the precise absolute dose delivered to each cell sample was determined by an radiochromic EBT film positioned in front of the cell sample. Furthermore, the energy spectrum of the laser-accelerated electron beam was determined. As presented in a previous work of the authors, also for laser-accelerated protons a precise dosimetric characterization was performed that enabled initial radiobiological cell irradiation experiments with laser-accelerated protons. Therefore, a precise dosimetric characterization, optimization and control of laser-accelerated and therefore ultra-short pulsed, intense particle beams for both electrons and protons is possible, allowing radiobiological experiments and meeting all necessary requirements like homogeneity, stability and precise dose delivery. In order to fulfill the much higher dosimetric requirements for clinical application, several improvements concerning, i.e., particle energy and spectral shaping as well as patient safety are necessary.

  3. Scattered UV irradiation during VISX excimer laser keratorefractive surgery.

    Science.gov (United States)

    Hope, R J; Weber, E D; Bower, K S; Pasternak, J P; Sliney, D H

    2008-04-01

    To evaluate the potential occupational health hazards associated with scattered ultraviolet (UV) radiation during photorefractive keratectomy (PRK) using the VISX Star S3 excimer laser. The Laser Vision Center, National Naval Medical Center, Bethesda, Maryland, USA. Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model PD-10 with silicon detector) during PRK treatments as well as during required calibration procedures at a distance of 20.3 cm from the left cornea. These measurements were evaluated using a worst-case scenario for exposure, and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TVL) to perform a risk/hazard analysis. During the PRK procedures, the highest measured value was 248.4 nJ/pulse. During the calibration procedures, the highest measured UV scattered radiation level was 149.6 nJ/pulse. The maximum treatment time was 52 seconds. Using a worst-case scenario in which all treatments used the maximum power and time, the total energy per eye treated was 0.132 mJ/cm2 and the total UV radiation at close range (80 cm from the treated eye) was 0.0085 mJ/cm2. With a workload of 20 patients, the total occupational exposure at 80 cm to actinic UV radiation in an 8-hour period would be 0.425 mJ/cm2. The scattered actinic UV laser radiation from the VISX Star S3 excimer laser did not exceed occupational exposure limits during a busy 8-hour workday, provided that operating room personnel were at least 80 cm from the treated eye. While the use of protective eyewear is always prudent, this study demonstrates that the trace amounts of scattered laser emissions produced by this laser do not pose a serious health risk even without the use of protective eyewear.

  4. Modification induced by laser irradiation on physical features of plastics materials filled with nanoparticles

    Directory of Open Access Journals (Sweden)

    Scolaro Cristina

    2018-01-01

    Full Text Available The Thermal Laser Welding (TLW process involves localized heating at the interface of two pieces of plastic that will be joined. Polymeric materials of Ultra High Molecular Weight Polyethylene (UHMWPE, both pure and containing nanostructures at different concentrations (titanium and silver nanoparticles, were prepared as thin foils in order to produce an interface between a substrate transparent to the infrared laser wavelength and an highly absorbent substrate, in order to be welded by the laser irradiation. The used diode laser operates at 970 nm wavelength, in continuum, with a maximum energy of 100 mJ, for times of the order of 1 -60 s, with a spot of 300 μm of diameter. The properties of the polymers and of nanocomposite sheets, before and after the laser welding process, were measured in terms of optical characteristics, wetting ability, surface roughness and surface morphology.

  5. Microwave radiation mechanism in a pulse-laser-irradiated Cu foil target revisited

    International Nuclear Information System (INIS)

    Chen Ziyu; Li Jianfeng; Li Jun; Peng Qixian

    2011-01-01

    The microwave radiation mechanism in a Cu-based foil target irradiated by an intense laser pulse has been investigated. Microwave emission in the frequency range 0.5-4 GHz has been observed from a 200 ps laser pulse of intensity about 10 12 W cm -2 normally incident on the target surface. The total microwave power and energy emitted from the interaction were found to be about 0.4 W and 2 nJ, respectively, corresponding to an efficiency of coupling laser energy to microwave energy of 2x10 -8 . The result agrees well with quadrupole radiation calculated based on a circuit model of a laser plasma, which indicates that the radiative process can be explained by magnetic dipole or electric quadrupole radiation from the laser-produced symmetric poloidal current distribution at the plasma-target interface.

  6. Microwave radiation mechanism in a pulse-laser-irradiated Cu foil target revisited

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ziyu; Li Jianfeng; Li Jun; Peng Qixian, E-mail: ziyuch@gmail.com [Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621900 (China)

    2011-05-01

    The microwave radiation mechanism in a Cu-based foil target irradiated by an intense laser pulse has been investigated. Microwave emission in the frequency range 0.5-4 GHz has been observed from a 200 ps laser pulse of intensity about 10{sup 12} W cm{sup -2} normally incident on the target surface. The total microwave power and energy emitted from the interaction were found to be about 0.4 W and 2 nJ, respectively, corresponding to an efficiency of coupling laser energy to microwave energy of 2x10{sup -8}. The result agrees well with quadrupole radiation calculated based on a circuit model of a laser plasma, which indicates that the radiative process can be explained by magnetic dipole or electric quadrupole radiation from the laser-produced symmetric poloidal current distribution at the plasma-target interface.

  7. Carbon/hydrogen clusters [CnHx+] formation from laser irradiation of coronene

    International Nuclear Information System (INIS)

    Betancourt, F; Alvarez, I; Guerrero, A; Cisneros, C; Poveda, J C

    2015-01-01

    This article presents the photo induced dehydrogenation of a cooled molecular jet of coronene, exposed to 266 nm laser radiation. Using unfocused laser radiation of 1064 nm, synchronously coupled with the ionization laser pulses, a system recently developed. Molecular beams were produced by laser desorption of coronene. Analysis of the photoproducts made by time-of flight mass spectrometer showed that a wide variety of ionic species were formed; more than 300 different species were observed. The results showed carbon clusters C + n with n up to 24 as well as carbon/hydrogen clusters C + n H + x with masses higher than 300 m/z. The effect on the laser irradiance on the formation of different ions, in the rage from 10 9 W/cm2 to 10 10 W/cm2, is discussed as it is reflected on the evolution from the big ions to the smaller ones. (paper)

  8. X-ray emission from stainless steel foils irradiated by femtosecond petawatt laser pulses

    Science.gov (United States)

    Alkhimova, M. A.; Faenov, A. Ya; Pikuz, T. A.; Skobelev, I. Yu; Pikuz, S. A.; Nishiuchi, M.; Sakaki, H.; Pirozhkov, A. S.; Sagisaka, S.; Dover, N. P.; Kondo, Ko; Ogura, K.; Fukuda, Y.; Kiriyama, H.; Esirkepov, T.; Bulanov, S. V.; Andreev, A.; Kando, M.; Zhidkov, A.; Nishitani, K.; Miyahara, T.; Watanabe, Y.; Kodama, R.; Kondo, K.

    2018-01-01

    We report about nonlinear growth of x-ray emission intensity emitted from plasma generated by femtosecond petawatt laser pulses irradiating stainless steel foils. X-ray emission intensity increases as ˜ I 4.5 with laser intensity I on a target. High spectrally resolved x-ray emission from front and rear surfaces of 5 μm thickness stainless steel targets were obtained at the wavelength range 1.7-2.1 Å, for the first time in experiments at femtosecond petawatt laser facility J-KAREN-P. Total intensity of front x-ray spectra three times dominates to rear side spectra for maximum laser intensity I ≈ 3.2×1021 W/cm2. Growth of x-ray emission is mostly determined by contribution of bremsstrahlung radiation that allowed estimating bulk electron plasma temperature for various magnitude of laser intensity on target.

  9. Low damage electrical modification of 4H-SiC via ultrafast laser irradiation

    Science.gov (United States)

    Ahn, Minhyung; Cahyadi, Rico; Wendorf, Joseph; Bowen, Willie; Torralva, Ben; Yalisove, Steven; Phillips, Jamie

    2018-04-01

    The electrical properties of 4H-SiC under ultrafast laser irradiation in the low fluence regime (engineering spatially localized structural and electronic modification of wide bandgap materials such as 4H-SiC with relatively low surface damage via low temperature processing.

  10. The effects of laser radiation on the descendants of irradiated rats

    International Nuclear Information System (INIS)

    Hernandez, J.W.R.; Barbosa, C.A.A.; Moderno, L.A.O.; Parizzotto, N.A.

    1991-01-01

    The effects of low energy laser radiation on the descendants of irradiated rats were investigated by comparing natimortality and the frequency of congenital malformations in three experimental and a control group. Natimortality was not significantly different among the groups. However, cardiomegaly, anophtalmia, dilated abdominal viscera, and premature closures of cranial sutures were recorded only in the experimental groups. (author)

  11. Trigger effect of infrared femtosecond laser irradiation on neoplasm in experimental cervical cancer

    Science.gov (United States)

    Gening, Tatyana; Voronova, Olga; Zolotovskii, Igor; Sysoliatin, Alexey; Dolgova, Dinara; Abakumova, Tatyana

    2013-02-01

    The present work discusses effect of infrared (IR) femtosecond laser irradiation on neoplasm of white mice with experimental cervical cancer- 5 (CC-5 on the 20th and 30th days after tumor transplantation). Tumor tissue was irradiated by femtosecond erbium doped fiber laser: the wavelength is 1.55 μm, average and peak powers are1,25 mW and 6kW, respectively, irradiation trials n=10. The average energy density (energy dose) on a tissue for two groups of animals was 0,24 J/cm2 and 0,36 J/cm2 for a single trial. Irradiation was followed by biochemical determination of LPO AOS parameters ("Lipid peroxidation-antioxidants" system): malondialdehyde (MDA), activity of superoxide dismutase (SOD), catalase and glutathione-reductase (GR), glutathione-S-transferase (GST). A subsequent morphological study of tumor tissue was performed. Mathematical analysis of data demonstrates a weak dependence of the studied parameters on energy dose. The latter implies the trigger effect of IR femtosecond laser irradiation on redox-dependent processes in neoplasm at experimental cervical cancer.

  12. Low-intensity laser irradiation at 660 nm stimulates cytochrome c oxidase in stressed fibroblast cells.

    Science.gov (United States)

    Houreld, Nicolette N; Masha, Roland T; Abrahamse, Heidi

    2012-07-01

    Low-intensity laser irradiation (LILI) has been used to modulate a variety of biological processes, including diabetic wound healing. The mechanism of action is thought to exist primarily with the mitochondria. This study aimed to determine the effect of irradiation on normal, diabetic, and ischemic mitochondrial electron transport chain (ETC) complexes. Normal, diabetic and ischemic human skin fibroblast mitochondria were irradiated in vitro at a wavelength of 660 nm and a fluence of either 5 or 15 J/cm(2). Non-irradiated mitochondria served as controls. Enzyme activities of mitochondrial complexes I, II, III, and IV were determined immediately post-irradiation. Normal, diabetic, and ischemic cells were irradiated and adenosine triphosphate (ATP) and active mitochondria were determined by luminescence and fluorescent microscopy, respectively. Irradiated diabetic mitochondria at a fluence of 15 J/cm(2) showed a significant decrease in complex III activity (P < 0.05). Normal (P < 0.01) and diabetic (P < 0.05) mitochondria irradiated at either 5 or 15 J/cm(2) showed a significant increase in complex IV activity. ATP results showed a significant increase in irradiated normal cells (5 J/cm(2); P < 0.05) and diabetic cells (15 J/cm(2); P < 0.01). There was a higher accumulation of active mitochondria in irradiated cells than non-irradiated cells. Irradiation at 660 nm has the ability to influence mitochondrial enzyme activity, in particular cytochrome c oxidase. This leads to increased mitochondrial activity and ATP synthesis. Copyright © 2012 Wiley Periodicals, Inc.

  13. Analyses of surface coloration on TiO2 film irradiated with excimer laser

    International Nuclear Information System (INIS)

    Zheng, H.Y.; Qian, H.X.; Zhou, W.

    2008-01-01

    TiO 2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm 2 . Microcracks at medium laser fluence of 1000 mJ/cm 2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm 2 . The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO 2 film might be used for adjustable filters

  14. Study of the Conditions of Irradiating Laser for Removal of Toner from Used Paper

    Science.gov (United States)

    Ihori, Haruo; Inagawa, Yuki; Ito, Naohiro; Fujii, Masaharu; Ninomiya, Hideki

    Though it is said to the paper-less age with the spread of personal computer, amount of office papers to be used doesn't have tendency to decrease. In general, used papers are recovered and recycled in order to preserve the environment. The labor and costs are required for the recovery of used papers and a recycled paper is lower in quality. If we could reuse used papers repeatedly without withdrawing those, for example, by copying machine that could print again with removing toner on used paper, it is very convenient and ecological. So, we studied about removing toner from used papers by application of the laser ablation technique. As an optical source, SHG-YAG laser was chosen. For removal of toner from used papers, the energy density to irradiate them with SHG-YAG laser was examined. When approximately 12mJ/mm2 of the energy density, which was average value, toner was removed so much as to be able to reuse again. Moreover, conditions of the laser irradiation, concretely, the velocity scanning the laser and the number of the irradiation, were studied.

  15. The effect of laser irradiation on electrical and structural properties of ZnO thin films

    Directory of Open Access Journals (Sweden)

    P Kameli

    2013-03-01

    Full Text Available  In this paper, ZnO thin film was prepared by sol-gel process on glass substrates. The deposited films were dried at 100 and 240 ˚C and then annealed at 300, 400 and 500 ˚C. The two-probe measurement showed that resistance of as-prepared films is very high. The KrF excimer (λ=248 nm laser irradiation with 1000 pulses, frequency of 1 Hz and 90 mJ/cm2 energy on surface of film resulted in the reduction of the films electrical resistance. X-ray diffraction (XRD patterns confirmed the improved hexagonal wurtzite structure of film, and AFM and FE-SEM analyses showed regular and spherical grain was formed on the surface. The particle size was increased from ~10 to ~30 nm after leaser irradiation. Generally, it was showed that electrical, structural and morphological properties of films improve considerably by laser irradiation.

  16. Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

    International Nuclear Information System (INIS)

    Yamada, Hirokazu; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, George; Kohno, Wataru; Morishima, Yasuo

    2002-01-01

    SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process

  17. Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

    Science.gov (United States)

    Yamada, Hirokazu; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, George; Kohno, Wataru; Morishima, Yasuo

    2002-12-01

    SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process.

  18. Patterning of nanoparticulate transparent conductive ITO films using UV light irradiation and UV laser beam writing

    International Nuclear Information System (INIS)

    Solieman, A.; Moharram, A.H.; Aegerter, M.A.

    2010-01-01

    Indium tin oxide (ITO) thin film is one of the most widely used as transparent conductive electrodes in all forms of flat panel display (FPD) and microelectronic devices. Suspension of already crystalline conductive ITO nanoparticles fully dispersed in alcohol was spun, after modifying with coupling agent, on glass substrates. The low cost, simple and versatile traditional photolithography process without complication of the photoresist layer was used for patterning ITO films. Using of UV light irradiation through mask and direct UV laser beam writing resulted in an accurate linear, sharp edge and very smooth patterns. Irradiated ITO film showed a high transparency (∼85%) in the visible region. The electrical sheet resistance decrease with increasing time of exposure to UV light and UV laser. Only 5 min UV light irradiation is enough to decrease the electrical sheet resistance down to 5 kΩ□.

  19. Treatment of relapse in herpes simplex on labial and facial areas and of primary herpes simplex on genital areas and "area pudenda" with low-power He-Ne laser or Acyclovir administered orally

    Science.gov (United States)

    Velez-Gonzalez, Mariano; Urrea-Arbelaez, Alejandro; Nicolas, M.; Serra-Baldrich, E.; Perez, J. L.; Pavesi, M.; Camarasa, J. M.; Trelles, Mario A.

    1996-01-01

    Sixty patients (greater than 16 yrs old) suffering primary or relapse genital herpes simplex viruses (HSV) and relapse labial HSV were appointed for this study. Three or more relapses were experienced per year. Patients (under treatment) were divided into two groups (distribution areas), corresponding to either labial herpes or genital herpes. These groups were sub-divided into 3 groups. The total number of labial or facial HSV patients was 36 (10 in group 1, 12 in group 2, 14 in group 3) and 24 for genital, buttocks, or 'area pudenda' HSV patients (6 in group 1, 8 in group 2, 10 in group 3). The design was a randomized, double- blind study. The setting was hospital and outpatient. The patients diagnosed as having the HVS disease were sent to the dermatology department and were assigned to a group at random. Treatment was begun as follows: During the treatment signs and symptoms were assessed and after the treatment, the relapses were also assessed (biochemical and hematological tests before and after the treatment) and the diagnosis of the HSV type I and II. The statistical evaluation of the results was performed and carried out with the SPSS and BMDP program. The relapses of the herpes infection in the lips and the face were significantly reduced (p less than 0.026) in patients treated with laser He-Ne and laser He-Ne plus Acyclovir. The interim between the relapses also increased significantly (p less than 0.005) in relation with the group treated with Acyclovir. The duration of the herpetic eruptions was clearly reduced in all locations in patients treated with laser He-Ne plus Acyclovir. No differences were noted between patients treated with laser He-Ne only or Acyclovir only. Therefore it is probable that therapeutic synergism took place. In relation with this, laser He-Ne shows the same therapeutic efficacy as Acyclovir taken orally. The association of Acyclovir and laser Ne-Ne could be an alternative method for the treatment of HSV in the face. The number

  20. Low-intensity laser irradiation use for oral and lip precancer treatment

    Science.gov (United States)

    Kunin, Anatoly A.; Podolskaya, Elana E.; Stepanov, Nicolay N.; Petrov, Anatoly; Erina, Stanislava V.; Pankova, Svetlana N.

    1996-09-01

    Precancer and background diseases of the oral mucosa and lips, such as lichen planus, chronic ulcers and fissures, meteorological heilit, lupus erythematosus, after radiation heilit were treated by low-intensity laser irradiation. Laser therapy of the over-mentioned diseases was combined with medicinal treatment. All the patients were selected and treated in the limits of dispensary system. THe choice of diagnostic methods were made according to each concrete nosological form. A great attention was paid to the goal- directly sanitation of the oral cavity and treatment of attended internal diseases. The etiological factors were revealed and statistically analyzed. The results received during our researches demonstrated high effectiveness of laser irradiation combined with medicinal therapy in the treatment of oral mucosa and lips precancer diseases.

  1. Stability of iodinated contrast media in UV-laser irradiation and toxicity of photoproducts

    International Nuclear Information System (INIS)

    Groenewaeller, E.F.; Kehlbach, R.; Claussen, C.D.; Duda, S.H.; Wahl, H.G.; Rodemann, H.P.

    1998-01-01

    Purpose: In XeCl-Excimer laser angioplasty, unintended and possibly harmful interaction of the UV-laser light and the contrast media may occur due to the high concentration of contrast medium proximal to the occlusion or subtotal stenosis. Methods: One ml of three nonionic monomeric contrast agents (iopromide, iomeprol, iopamidol), one nonionic dimetric (jotrolane), and one ionic monomeric (amidotrizoate) X-ray contrast agent were irradiated with a XeCl excimer laser (λ=308 nm, pulse duration 120 ns, 50 Hz) using a 9 French multifiber catheter (12 sectors). Up to 20 000 pulses (106 J) were applied. Using high performance liquid chromatography the amount of liberated iodide as well as the fraction of unchanged contrast media were measured. Cytotoxicity of the photoproducts was tested in a colony formation assay of human skin fibroblasts. The contrast agents were irradiated with 2000 pulses/ml (5.3 mJ/pulse; 10.6 J) and then added to the cell cultures for a period of three hours in a concentration of 10%. Results: Excimer laser irradiation induced iodide liberation of up to 3.3 mg iodide/ml. Up to 19% of the contrast agents changed their original molecular structure. Incubation of irradiated contrast agents resulted in a significantly decreased potential for colony formation (p values ranging from 0.0044 to 0.0102) with significantly higher toxicity of amidotrizoate and iomeprol in comparison to iopromide, iotrolan, and iopamidol. Discussion: Due to the cytotoxic photoproducts and the high level of liberated iodide, it is recommended to flush the artery with physiological saline solution before applying a pulsed excimer laser in human arterial obstructions in order to reduce the contrast agent concentration at the site of irradiation. (orig.) [de

  2. Irradiation of nuclear materials with laser-plasma filaments produced in air and deuterium by terrawatt (TW) laser pulses

    Science.gov (United States)

    Avotina, Liga; Lungu, Mihail; Dinca, Paul; Butoi, Bogdan; Cojocaru, Gabriel; Ungureanu, Razvan; Marcu, Aurelian; Luculescu, Catalin; Hapenciuc, Claudiu; Ganea, Paul C.; Petjukevics, Aleksandrs; Lungu, Cristian P.; Kizane, Gunta; Ticos, C. M.; Antohe, Stefan

    2018-01-01

    Be-C-W mixed materials with variable atomic ratios were exposed to high power (TW) laser induced filamentation plasma in air in normal conditions and in deuterium at a reduced pressure of 20 Torr. Morphological and structural investigations were performed on the irradiated zones for both ambient conditions. The presence of low-pressure deuterium increased the overall ablation rate for all samples. From the elemental concentration point of view, the increase of the carbon percentage has led to an increase in the ablation rate. An increase of the tungsten percentage had the opposite effect. From structural spectroscopic investigations using XPS, Raman and FT-IR of the irradiated and non-irradiated sample surfaces, we conclude that deuterium-induced enhancement of the ablation process could be explained by preferential amorphous carbon removal, possibly by forming deuterated hydrocarbons which further evaporated, weakening the layer structure.

  3. Factors affecting color strength of printing on film-coated tablets by UV laser irradiation: TiO2 particle size, crystal structure, or concentration in the film, and the irradiated UV laser power.

    Science.gov (United States)

    Hosokawa, Akihiro; Kato, Yoshiteru

    2011-08-01

    The purpose of this article is to study factors affecting color strength of printing on film-coated tablets by ultraviolet (UV) laser irradiation: particle size, crystal structure, or concentration of titanium dioxide (TiO2) in film, and irradiated UV laser power. Hydroxypropylmethylcellulose films containing 4.0% of TiO2, of which BET particle sizes were ranging from 126.1 to 219.8 nm, were irradiated 3.14W of UV laser at a wavelength 355 nm to study effects of TiO2 particle size and crystal structure on the printing. The films containing TiO2 concentration ranging from 1.0 to 7.7% were irradiated 3.14 or 5.39W of the UV laser to study effect of TiO2 concentration on the printing. The film containing 4.0% of TiO2, was irradiated the UV laser up to 6.42W to study effect of the UV laser power on the printing. The color strength of the printed films was estimated by a spectrophotometer as total color difference (dE). Particle size, crystal structure, and concentration of TiO2 in the films did not affect the printing. In the relationship between the irradiated UV laser power and dE, there found an inflection point (1.6W). When the UV laser power was below 1.6W, the films were not printed. When it was beyond the point, total color difference increased linearly in proportion with the irradiated laser power. The color strength of the printing on film was not changed by TiO2 particle size, crystal structure, and concentration, but could be controlled by regulating the irradiated UV laser power beyond the inflection point.

  4. Characterization of advanced polymethylmethacrylate (PMMA) targets for TNSA laser irradiation

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Cutroneo, Mariapompea; Semián, Vladimír; Ceccio, G.

    2015-01-01

    Roč. 351, OCT (2015), s. 580-587 ISSN 0169-4332 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2011019 Institutional support: RVO:61389005 Keywords : PMMA * TNSA * ion acceleration * laser-generating plasma Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.150, year: 2015

  5. Study of shock coalescence in laser-irradiated targets

    International Nuclear Information System (INIS)

    Coe, S.E.; Willi, O.; Afshar-Rad, T.; Rose, S.J.

    1988-01-01

    We report on the first direct experimental observation of the coalescence of two shocks induced by a shaped laser pulse. Optical streak photography of the rear surface of aluminum multiple step targets was used to study the breakout of these shocks and observe their behavior. The experimental results are compared with simulations by a one-dimensional Lagrangian hydrodynamic code

  6. Measurement of Irradiated Pyroprocessing Samples via Laser Induced Breakdown Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Phongikaroon, Supathorn [Virginia Commonwealth Univ., Richmond, VA (United States)

    2016-10-31

    The primary objective of this research is to develop an applied technology and provide an assessment to remotely measure and analyze the real time or near real time concentrations of used nuclear fuel (UNF) dissolute in electrorefiners. Here, Laser-Induced Breakdown Spectroscopy (LIBS), in UNF pyroprocessing facilities will be investigated. LIBS is an elemental analysis method, which is based on the emission from plasma generated by focusing a laser beam into the medium. This technology has been reported to be applicable in the media of solids, liquids (includes molten metals), and gases for detecting elements of special nuclear materials. The advantages of applying the technology for pyroprocessing facilities are: (i) Rapid real-time elemental analysis|one measurement/laser pulse, or average spectra from multiple laser pulses for greater accuracy in < 2 minutes; (ii) Direct detection of elements and impurities in the system with low detection limits|element specific, ranging from 2-1000 ppm for most elements; and (iii) Near non-destructive elemental analysis method (about 1 g material). One important challenge to overcome is achieving high-resolution spectral analysis to quantitatively analyze all important fission products and actinides. Another important challenge is related to accessibility of molten salt, which is heated in a heavily insulated, remotely operated furnace in a high radiation environment with an argon atmosphere.

  7. Neutron energy spectra calculations in the low power research reactor

    International Nuclear Information System (INIS)

    Omar, H.; Khattab, K.; Ghazi, N.

    2011-01-01

    The neutron energy spectra have been calculated in the fuel region, inner and outer irradiation sites of the zero power research reactor using the MCNP-4C code and the combination of the WIMS-D/4 transport code for generation of group constants and the three-dimensional CITATION diffusion code for core analysis calculations. The neutron energy spectrum has been divided into three regions and compared with the proposed empirical correlations. The calculated thermal and fast neutron fluxes in the low power research reactor MNSR inner and outer irradiation sites have been compared with the measured results. Better agreements have been noticed between the calculated and measured results using the MCNP code than those obtained by the CITATION code. (author)

  8. Surface patterning of multilayer graphene by ultraviolet laser irradiation in biomolecule sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Tien-Li, E-mail: tlchang@ntnu.edu.tw; Chen, Zhao-Chi

    2015-12-30

    Graphical abstract: - Highlights: • Direct UV laser irradiation on multilayer graphene was discussed. • Multilayer graphene with screen-printed process was presented. • Surface patterning of multilayer graphene at fluence threshold was investigated. • Electrical response of glucose in sensing devices can be studied. - Abstract: The study presents a direct process for surface patterning of multilayer graphene on the glass substrate as a biosensing device. In contrast to lithography with etching, the proposed process provides simultaneous surface patterning of multilayer graphene through nanosecond laser irradiation. In this study, the multilayer graphene was prepared by a screen printing process. Additionally, the wavelength of the laser beam was 355 nm. To perform the effective laser process with the small heat affected zone, the surface patterns on the sensing devices could be directly fabricated using the laser with optimal control of the pulse overlap at a fluence threshold of 0.63 J/cm{sup 2}. The unique patterning of the laser-ablated surface exhibits their electrical and hydrophilic characteristics. The hydrophilic surface of graphene-based sensing devices was achieved in the process with the pulse overlap of 90%. Furthermore, the sensing devices for controlling the electrical response of glucose by using glucose oxidase can be used in sensors in commercial medical applications.

  9. High-energy, twelve-channel laser facility (DEFIN) for spherical irradiation of thermonuclear targets

    International Nuclear Information System (INIS)

    Basov, N.G.; Danilov, A.E.; Krokhin, O.N.; Kruglov, B.V.; Mikhailov, Yu.A.; Sklizkov, G.V.; Fedotov, S.I.; Fedorov, A.N.

    This paper describes a high-energy, twelve-channel laser facility (DELFIN) intended for high-temperature heating of thermonuclear targets with spherical symmetry. The facility includes a neodymium-glass laser with the ultimate radiation energy of 10 kJ, a pulse length of approximately 10 -10 to 10 -9 s, beam divergence of 5 x 10 -4 radians, a vacuum chamber in which laser radiation interacts with the plasma, and a system of diagnostic instrumentation for the observation of laser beam and plasma parameters. Described are the optical scheme and construction details of the laser facility. Presented is an analysis of focusing schemes for target irradiation and described is the focusing scheme of the DELFIN facility, which is capable of attaining a high degree of spherical symmetry in irradiating targets with maximum beam intensity at the target surface of approximately 10 15 W/cm 2 . This paper examines the most important problems connected with the physical investigations of thermonuclear laser plasma and the basic diagnostic problems involved in their solution

  10. Effect on isoflavone of soybean seedlings by 532nm laser irradiation

    Science.gov (United States)

    Tian, J.; Jin, L. H.; Li, J. M.; Shen, B. J.; Wang, C. Y.; Lu, X.; Zhao, X. L.

    2010-02-01

    We took soybeans as experimental substance to study how the 532nm laser with different power density and irradiation time affected the pullulation ratio of the soybeans, average height of seedlings and the isoflavone content of seedlings' cotyledon and laminae. The mechanism that laser pretreatment of soybean seeds could increase the isoflavone content of the seedlings was discussed in such both aspects as the efficiency of the photosynthesis and the activity of a phenylalanine ammonia-lyase (PAL) as an initial enzyme for synthesizing the isoflavone. The results showed that after the soybean seeds were pretreated by laser, the activity of the PAL and the resultants of the photosynthesis such as the sugar of dissolubility, the sucrose, and the amylum all increased with the soybean seeds irradiated by laser in which the effect on the soybean seeds pretreated by 15mW/mm2 laser for 5 min was the most obvious. As a result, the photosynthesis efficiency of the soybean seedlings increased after being pretreated by laser, which might offer the foundation for accumulating a large amount of isoflavone.

  11. Study etching characteristics of a track detector CR-39 with ultraviolet laser irradiation

    International Nuclear Information System (INIS)

    Dwaikat, Nidal; Iida, Toshiyuki; Sato, Fuminobu; Kato, Yushi; Ishikawa, Ippei; Kada, Wataru; Kishi, Atsuya; Sakai, Makoto; Ihara, Yohei

    2007-01-01

    The effect of pulsed ultraviolet Indium-doped Yttrium Aluminum Garnet (UV-In:YAG) laser of λ=266 nm, pulse energy 42 mJ/pulse at repetition rate10 Hz on the etching characteristics of Japanese CR-39 was studied at various energy intensities. Fifteen detectors were divided into two sets, each of seven samples and one sample was kept as a reference.The first set (post-exposed) was first exposed to alpha radiation with close contact to 241 Am and then treated in air with laser in the energy intensity range from 40 to160 J/cm 2 , 20 J/cm 2 in step. The second set (pre-exposed) was irradiated in reverse process (laser+alpha) with the same sources as the first set and under the same condition. The laser energy intensities ranged between 20 and 140 J/cm 2 , 20 J/cm 2 in step. For post-exposed samples (alpha+laser) bulk etch rate decreases up to 60 J/cm 2 and increases thereafter, while for pre-exposed samples (laser+alpha) the bulk etch rate oscillates without showing any precise periodicity. The bulk etch rate for both sets was found to be the same at 60≤energy intensity≤80 J/cm 2 and this may indicate that the same structural changes have happened. The track etch rate was found to be equal to the bulk etch rate for both sets, so the sensitivity is constant. In both sets several changes on the detector surfaces: tracks of different sizes and shapes and high density within the laser spot were observed. Out of the laser spot, the tracks become larger and lower density, indicating cross-linking and scission have happened, simultaneously, on the same surface as a result of UV-laser irradiation

  12. Corneal tissue welding with infrared laser irradiation after clear corneal incision.

    Science.gov (United States)

    Rasier, Rfat; Ozeren, Mediha; Artunay, Ozgür; Bahçecioğlu, Halil; Seçkin, Ismail; Kalaycoğlu, Hamit; Kurt, Adnan; Sennaroğlu, Alphan; Gülsoy, Murat

    2010-09-01

    The aim of this study was to investigate the potential of infrared lasers for corneal welding to seal corneal cuts done in an experimental animal model. Full-thickness corneal cuts on freshly enucleated bovine eyes were irradiated with infrared (809-nm diode, 980-nm diode, 1070-nm YLF, and 1980-nm Tm:YAP) lasers to get immediate laser welding. An 809-nm laser was used with the topical application of indocyanine green to enhance the photothermal interaction at the weld site. In total, 60 bovine eyes were used in this study; 40 eyes were used in the first part of the study for the determination of optimal welding parameters (15 eyes were excluded because of macroscopic carbonization, opacification, or corneal shrinkage; 2 eyes were used for control), and 20 eyes were used for further investigation of more promising lasers (YLF and Tm:YAP). Laser wavelength, irradiating power, exposure time, and spot size were the dose parameters, and optimal dose for immediate closure with minimal thermal damage was estimated through histological examination of welded samples. In the first part of the study, results showed that none of the applications was satisfactory. Full-thickness success rates were 28% (2 of 7) for 809-nm and for 980-nm diode lasers and 67% (2 of 3) for 1070-nm YLF and (4 of 6) for 1980-nm Tm:YAP lasers. In the second part of the study, YLF and Tm:YAP lasers were investigated with bigger sample size. Results were not conclusive but promising again. Five corneal incisions were full-thickness welded out of 10 corneas with 1070-nm laser, and 4 corneal incisions were partially welded out of 10 corneas with 1980-nm laser in the second part of the study. Results showed that noteworthy corneal welding could be obtained with 1070-nm YLF laser and 1980-nm Tm:YAP laser wavelengths. Furthermore, in vitro and in vivo studies will shed light on the potential usage of corneal laser welding technique.

  13. Effect of Laser Irradiation on Cell Function and Its Implications in Raman Spectroscopy.

    Science.gov (United States)

    Yuan, Xiaofei; Song, Yanqing; Song, Yizhi; Xu, Jiabao; Wu, Yinhu; Glidle, Andrew; Cusack, Maggie; Ijaz, Umer Z; Cooper, Jonathan M; Huang, Wei E; Yin, Huabing

    2018-04-15

    Lasers are instrumental in advanced bioimaging and Raman spectroscopy. However, they are also well known for their destructive effects on living organisms, leading to concerns about the adverse effects of laser technologies. To implement Raman spectroscopy for cell analysis and manipulation, such as Raman-activated cell sorting, it is crucial to identify nondestructive conditions for living cells. Here, we evaluated quantitatively the effect of 532-nm laser irradiation on bacterial cell fate and growth at the single-cell level. Using a purpose-built microfluidic platform, we were able to quantify the growth characteristics, i.e., specific growth rates and lag times of individual cells, as well as the survival rate of a population in conjunction with Raman spectroscopy. Representative Gram-negative and Gram-positive species show similar trends in response to a laser irradiation dose. Laser irradiation could compromise the physiological function of cells, and the degree of destruction is both dose and strain dependent, ranging from reduced cell growth to a complete loss of cell metabolic activity and finally to physical disintegration. Gram-positive bacterial cells are more susceptible than Gram-negative bacterial strains to irradiation-induced damage. By directly correlating Raman acquisition with single-cell growth characteristics, we provide evidence of nondestructive characteristics of Raman spectroscopy on individual bacterial cells. However, while strong Raman signals can be obtained without causing cell death, the variety of responses from different strains and from individual cells justifies careful evaluation of Raman acquisition conditions if cell viability is critical. IMPORTANCE In Raman spectroscopy, the use of powerful monochromatic light in laser-based systems facilitates the detection of inherently weak signals. This allows environmentally and clinically relevant microorganisms to be measured at the single-cell level. The significance of being able to

  14. Novel phenomena in clusters irradiated by short-wavelength free-electron lasers

    International Nuclear Information System (INIS)

    Fukuzawa, Hironobu; Ueda, Kiyoshi

    2017-01-01

    By electron spectroscopy, we investigated various phenomena that are caused by the irradiation of extreme ultraviolet (EUV) and X-ray free-electron laser (FEL) pulses on rare-gas clusters. The results for the Ne clusters, which were irradiated by EUVFEL pulses at a photon energy of 20.3 eV below the ionization threshold, illustrate that novel interatomic processes yield low-energy electrons. The results for the Xe clusters, irradiated by EUVFEL pulses at a photon energy of 24.3 eV above the threshold, illustrate that nanoplasma is formed as a result of trapping the photoelectrons and consequently emits low-energy thermal electrons. The results for the Ar clusters irradiated by 5 keV XFEL pulses illustrate that nanoplasma is formed by trapping low-energy Auger electrons and secondary electrons in the tens of fs range, and continuous thermal emission from the plasma occurs in the ps range. (author)

  15. Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials

    Science.gov (United States)

    Hermens, U.; Kirner, S. V.; Emonts, C.; Comanns, P.; Skoulas, E.; Mimidis, A.; Mescheder, H.; Winands, K.; Krüger, J.; Stratakis, E.; Bonse, J.

    2017-10-01

    Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface's wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties.

  16. Development of a Skin Burn Predictive Model adapted to Laser Irradiation

    Science.gov (United States)

    Sonneck-Museux, N.; Scheer, E.; Perez, L.; Agay, D.; Autrique, L.

    2016-12-01

    Laser technology is increasingly used, and it is crucial for both safety and medical reasons that the impact of laser irradiation on human skin can be accurately predicted. This study is mainly focused on laser-skin interactions and potential lesions (burns). A mathematical model dedicated to heat transfers in skin exposed to infrared laser radiations has been developed. The model is validated by studying heat transfers in human skin and simultaneously performing experimentations an animal model (pig). For all experimental tests, pig's skin surface temperature is recorded. Three laser wavelengths have been tested: 808 nm, 1940 nm and 10 600 nm. The first is a diode laser producing radiation absorbed deep within the skin. The second wavelength has a more superficial effect. For the third wavelength, skin is an opaque material. The validity of the developed models is verified by comparison with experimental results (in vivo tests) and the results of previous studies reported in the literature. The comparison shows that the models accurately predict the burn degree caused by laser radiation over a wide range of conditions. The results show that the important parameter for burn prediction is the extinction coefficient. For the 1940 nm wavelength especially, significant differences between modeling results and literature have been observed, mainly due to this coefficient's value. This new model can be used as a predictive tool in order to estimate the amount of injury induced by several types (couple power-time) of laser aggressions on the arm, the face and on the palm of the hand.

  17. Modification of electrical properties of zinc oxide by continuous wave ytterbium fiber laser irradiation

    International Nuclear Information System (INIS)

    Kido, H; Takahashi, M; Tani, J; Abe, N; Tsukamoto, M

    2011-01-01

    The polycrystalline plate-like ZnO samples were irradiated by a continuous wave Yb fiber laser and electrical properties of modified layer were investigated. The laser beam of spot size of 16 μm in diameter was scanned on the surface at a velocity of 5mm/s. There was a threshold for the laser modification. The laser etched grooves were formed above laser power of 20 W. The laser etched depth increased in relation to the laser power, 0.46 mm at 20 W and 5.0 mm at 126 W. The surface layers of laser etched grooves were modified in color and electrical property. The color changed from light yellow to black, and the electrical resistivity drastically decreased from initial value of 1.1x10 5 Ωcm to 3.2x10 -1 Ωcm at 56 W, 2.8x10 -1 Ωcm at 91 W, and 2.0x10 -1 Ωcm at 126 W. The Hall measurement showed that the modified surface layer was an n-type semiconductor and carrier concentration of the layer was 1.5x10 17 cm -3 at 56 W, 7.2x10 17 cm -3 at 91 W, and 1.9x10 18 cm -3 at 126 W.

  18. Modification of electrical properties of zinc oxide by continuous wave ytterbium fiber laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kido, H; Takahashi, M; Tani, J [Electronic Materials Research Division, Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553 (Japan); Abe, N; Tsukamoto, M, E-mail: kido@omtri.or.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan)

    2011-05-15

    The polycrystalline plate-like ZnO samples were irradiated by a continuous wave Yb fiber laser and electrical properties of modified layer were investigated. The laser beam of spot size of 16 {mu}m in diameter was scanned on the surface at a velocity of 5mm/s. There was a threshold for the laser modification. The laser etched grooves were formed above laser power of 20 W. The laser etched depth increased in relation to the laser power, 0.46 mm at 20 W and 5.0 mm at 126 W. The surface layers of laser etched grooves were modified in color and electrical property. The color changed from light yellow to black, and the electrical resistivity drastically decreased from initial value of 1.1x10{sup 5} {Omega}cm to 3.2x10{sup -1} {Omega}cm at 56 W, 2.8x10{sup -1} {Omega}cm at 91 W, and 2.0x10{sup -1} {Omega}cm at 126 W. The Hall measurement showed that the modified surface layer was an n-type semiconductor and carrier concentration of the layer was 1.5x10{sup 17} cm{sup -3} at 56 W, 7.2x10{sup 17} cm{sup -3} at 91 W, and 1.9x10{sup 18} cm{sup -3} at 126 W.

  19. Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers

    Science.gov (United States)

    Moura-Netto, Cacio; Mello-Moura, Anna Carolina Volpi; Palo, Renato Miotto; Prokopowitsch, Igor; Pameijer, Cornelis H.; Marques, Marcia Martins

    2015-03-01

    This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n=168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p<0.05). Both adaptation and sealer penetration in root canals were not affected by the laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p<0.05). It can be concluded that intracanal laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

  20. Adaptation and penetration of resin-based root canal sealers in root canals irradiated with high-intensity lasers.

    Science.gov (United States)

    Moura-Netto, Cacio; Mello-Moura, Anna Carolina Volpi; Palo, Renato Miotto; Prokopowitsch, Igor; Pameijer, Cornelis H; Marques, Marcia Martins

    2015-03-01

    This research analyzed the quality of resin-based sealer adaptation after intracanal laser irradiation. Extracted teeth (n = 168) were root canal treated and divided into four groups, according to dentin surface treatment: no laser; Nd:YAG laser (1.5 W, 100 mJ, 15 Hz); diode laser (2.5 W in CW), and Er:YAG laser (1 W, 100 mJ, 10 Hz). The teeth were divided into four subgroups according to the sealer used: AH Plus, EndoREZ, Epiphany, and EpiphanySE. For testing the sealing after root canal obturation, the penetration of silver nitrate solution was measured, whereas to evaluate the adaptation and penetration of the sealer into the dentin, environmental scanning electron microscopy (ESEM) was used. The ESEM images were analyzed using a four-grade criteria score by three evaluators. The inter-examiner agreement was confirmed by Kappa test and the scores statistically compared by the Kruskal-Wallis' test (p laser irradiation. Nd:YAG and diode laser decreased the tracer penetration for AH Plus, whereas EndoREZ and EpiphanySE performances were affected by Nd:YAG irradiation (p laser irradiation can be used as an adjunct in endodontic treatment; however, the use of hydrophilic resin sealers should be avoided when root canals were irradiated with Nd:YAG laser.

  1. He-Ne laser irradiation affects proliferation of cultured rat Schwann cells in a dose-dependent manner

    International Nuclear Information System (INIS)

    Breugel, H.H.F.I. van; Bar, P.R.

    1993-01-01

    Schwann cell proliferation is considered an essential part of Wallerian degeneration after nerve damage. Laminin, an important component of the extracellular matrix and produced by Schwann cells, provides a preferred substrate for outgrowing axons. To study whether low energy (He-Ne) laser irradiation may exert a positive effect on nerve regeneration through an effect on Schwann cells, its effect was evaluated in vitro. Schwann cells were isolated from sciatic nerves of 4-5-day old Wistar rats and cultures on 96-multiwell plates. The cells were irradiated by a He-Ne laser beam. At three consecutive days, starting either at day 5 or day 8, cells were irradiated each day for 0.5, 1, 2, 5 or 10 min. Both cell number and laminin production were determined for each irradiation condition within one experiment. Schwann cells that were irradiated from day 8 on were hardly affected by laser irradiation. However, the proliferation of cells that were irradiated starting on day 5 was significantly increased after 1, 2 and 5 min of daily irradiation, compared to non-irradiated control cultures. The lamin production per cell of these Schwann cells was not significantly altered. From these results we conclude that He-Ne laser irradiation can modulate proliferation of rat Schwann cells in vitro in a dose-dependent manner. (Author)

  2. Low-power FLC-based retromodulator communications system

    Science.gov (United States)

    Swenson, Charles M.; Steed, Clark A.; de La Rue, Imelda A.; Fugate, Robert Q.

    1997-05-01

    On September 15, 1996, researchers from Utah State University/Space Dynamics Lab in conjunction with Phillips Lab/Starfire Optical Range and Kjome Research successfully flew and tested a retromodulator laser communication package on a high altitude balloon. This paper addresses the layout and hardware used for the communication link, as well as presenting some preliminary data collected during the 6 hour flight of the balloon. The package was a proof of concept demonstration system for a low-power laser communications systems for small, low Earth orbiting satellites. The ferroelectric liquid crystal based retromodulator design of Utah State provided test patterns for modulation rates up to 20 kilo bits per second. Data was successfully downlinked using a 1200 bps RS232 format and a simplistic receiver. The Starfire Optical Range 1.5-meter telescope located on Kirtland AFB, tracked the balloon, which reached a float altitude of 31 km and collected the modulated light reflected from the payload.

  3. Smartphone-Driven Low-Power Light-Emitting Device

    Directory of Open Access Journals (Sweden)

    Hea-Ja An

    2017-01-01

    Full Text Available Low-level light (laser therapy (LLLT has been widely researched in the recent past. Existing LLLT studies were performed based on laser. Recently, studies using LED have increased. This study presents a smartphone-driven low-power light-emitting device for use in colour therapy as an alternative medicine. The device consists of a control unit and a colour probe. The device is powered by and communicates with a smartphone using USB On-The-Go (OTG technology. The control unit controls emitting time and intensity of illumination with the configuration value of a smartphone application. Intensity is controlled by pulse width modulation (PWM without feedback. A calibration is performed to resolve a drawback of no feedback. To calibrate, intensity is measured in every 10 percent PWM output. PWM value is linearly calibrated to obtain accurate intensity. The device can control the intensity of illumination, and so, it can find application in varied scenarios.

  4. In vitro analysis of low-level laser irradiation on human osteoblast-like cells proliferation

    Science.gov (United States)

    Bloise, Nora; Saino, Enrica; Bragheri, Francesca; Minzioni, Paolo; Cristiani, Ilaria; Imbriani, Marcello; Visai, Livia

    2011-07-01

    The objective of this study was to examine the in vitro effect of a single or a multiple doses of low-level laser irradiation (LLLI) on proliferation of the human osteosarcoma cell line, SAOS-2. SAOS-2 cells were divided in five groups and exposed to LLLI (659 nm diode laser; 11 mW power output): group I as a control (dark), group II exposed to a single laser dose of 1 J/cm2, group III irradiated with a single dose of 3 J/cm2, and group IV and V exposed for three consecutive days to 1 or 3 J/cm², respectively. Cellular proliferation was assessed daily up to 7 days of culturing. The obtained results showed an increase in proliferative capacity of SAOS-2 cells during the first 96 h of culturing time in once-irradiated cells, as compared to control cells. Furthermore, a significantly higher proliferation in the group IV and V was detected if compared to a single dose or to control group after 96 h and 7 days. In conclusion, the effect of the single dose on cell proliferation was transitory and repeated irradiations were necessary to observe a strong enhancement of SAOS-2 growth. As a future perspective, we would like to determine the potential of LLLI as a new approach for promoting bone regeneration onto biomaterials.

  5. Single session of Nd:YAG laser intracanal irradiation neutralizes endotoxin in dental root dentin.

    Science.gov (United States)

    Archilla, José R F; Moreira, Maria S N A; Miyagi, Sueli P H; Bombana, Antônio C; Gutknecht, Norbert; Marques, Márcia M

    2012-11-01

    Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124  J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

  6. Single session of Nd:YAG laser intracanal irradiation neutralizes endotoxin in dental root dentin

    Science.gov (United States)

    Archilla, José R. F.; Moreira, Maria S. N. A.; Miyagi, Sueli P. H.; Bombana, Antônio C.; Gutknecht, Norbert; Marques, Márcia M.

    2012-11-01

    Endotoxins released in the dental root by Gram-negative microorganisms can be neutralized by calcium hydroxide, when this medication is applied inside the root canal for at least seven days. However, several clinical situations demand faster root canal decontamination. Thus, for faster endotoxin neutralization, endodontists are seeking additional treatments. The in vitro study tested whether or not intracanal Nd:YAG laser irradiation would be able to neutralize endotoxin within the human dental root canal in a single session. Twenty-four human teeth with one root were mounted between two chambers. After conventional endodontic treatment, root canals were contaminated with Escherichia coli endotoxin. Then they were irradiated or not (controls) in contact mode with an Nd:YAG laser (1.5 W, 15 Hz, 100 mJ and pulse fluency of 124 J/cm2). The endotoxin activity was measured using the limulus lysate technique and data were statistically compared (p≤0.05). The concentration of active endotoxin measured in the negative control group was significantly lower than that of the positive control group (p=0.04). The concentrations of endotoxin in both irradiated groups were significantly lower than that of the positive control group (p=0.027) and similar to that of negative control group (p=0.20). A single session of intracanal Nd:YAG laser irradiation is able to neutralize endotoxin in the dental root tissues.

  7. Ablation and cone formation mechanism on CR-39 by ArF laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Jooybari, B., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Afarideh, H., E-mail: baninshakery@gmail.com, E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute NSRT, Tehran (Iran, Islamic Republic of); Ghergherehchi, M. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2015-03-07

    In this work, chemical properties, surface modification, and micro structures formation on ablated polyallyl di-glycol carbonate (CR-39) polymer by ArF laser irradiation (λ = 193 nm) at various fluences and pulse number were investigated. CR-39 samples have been irradiated with an ArF laser (193 nm) at a repetition rate of 1 Hz. Threshold fluence of ablation and effective absorption coefficient of CR-39 were determined. Conical microstructures (Taylor cone) formed on laser-ablated CR-39 exhibit: smooth, Taylor cone shape walls and sharp tips together with interference and well defined fringe-structure with a period of 230 nm, around cone base. Mechanism of cone formation and cone evolution of CR-39 ablated surface were investigated by change of fluences (at a given pulse number) and pulse number (at a given fluence). Cone height, cone base, and region of interface were increased in micrometer steps by increasing the total fluence. Depression on the base of the cone and the circular fringe were simulated. FTIR spectra were measured and energy dispersive x-ray analysis of irradiated and un-irradiated samples was performed.

  8. Femtosecond Laser Irradiation of Plasmonic Nanoparticles in Polymer Matrix: Implications for Photothermal and Photochemical Material Alteration

    Directory of Open Access Journals (Sweden)

    Anton A. Smirnov

    2014-11-01

    Full Text Available We analyze the opportunities provided by the plasmonic nanoparticles inserted into the bulk of a transparent medium to modify the material by laser light irradiation. This study is provoked by the advent of photo-induced nano-composites consisting of a typical polymer matrix and metal nanoparticles located in the light-irradiated domains of the initially homogeneous material. The subsequent irradiation of these domains by femtosecond laser pulses promotes a further alteration of the material properties. We separately consider two different mechanisms of material alteration. First, we analyze a photochemical reaction initiated by the two-photon absorption of light near the plasmonic nanoparticle within the matrix. We show that the spatial distribution of the products of such a reaction changes the symmetry of the material, resulting in the appearance of anisotropy in the initially isotropic material or even in the loss of the center of symmetry. Second, we analyze the efficiency of a thermally-activated chemical reaction at the surface of a plasmonic particle and the distribution of the product of such a reaction just near the metal nanoparticle irradiated by an ultrashort laser pulse.

  9. 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 pulse...

  10. Surface and morphological features of laser-irradiated silicon under vacuum, nitrogen and ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Hayat, Asma, E-mail: asmahayat@gcu.edu.pk; Bashir, Shazia; Akram, Mahreen; Mahmood, Khaliq; Iqbal, Muhammad Hassan

    2015-12-01

    Highlights: • Laser irradiation effects on Si surface have been explored. • An Excimer Laser was used as a source. • SEM analysis was performed to explore surface morphology. • Raman spectroscopy analysis was carried out to find crystallographical alterations. - Abstract: Laser-induced surface and structural modification of silicon (Si) has been investigated under three different environments of vacuum, nitrogen (100 Torr) and ethanol. The interaction of 1000 pulses of KrF (λ ≈ 248 nm, τ ≈ 18 ns, repetition rate ≈ 30 Hz) Excimer laser at two different fluences of 2.8 J/cm{sup 2} and 4 J/cm{sup 2} resulted in formation of various kinds of features such as laser induced periodic surface structures (LIPSS), spikes, columns, cones and cracks. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets is explored by Raman spectroscopy. SEM analysis exhibits a non-uniform distribution of micro-scale pillars and spikes at the central ablated regime of silicon irradiated at low laser fluence of 2.8 J/cm{sup 2} under vacuum. Whereas cones, pits, cavities and ripples like features are seen at the boundaries. At higher fluence of 4 J/cm{sup 2}, laser induced periodic structures as well as micro-columns are observed. In the case of ablation in nitrogen environment, melting, splashing, self-organized granular structures and cracks along with redeposition are observed at lower fluence. Such types of small scaled structures in nitrogen are attributed to confinement and shielding effects of nitrogen plasma. Whereas, a crater with multiple ablative layers is formed in the case of ablation at higher fluence. Significantly different surface morphology of Si is observed in the case of ablation in ethanol. It reveals the formation of cavities along with small scale pores and less redeposition. These results reveal that the growth of surface and morphological features of irradiated Si are strongly

  11. Surface and morphological features of laser-irradiated silicon under vacuum, nitrogen and ethanol

    International Nuclear Information System (INIS)

    Hayat, Asma; Bashir, Shazia; Akram, Mahreen; Mahmood, Khaliq; Iqbal, Muhammad Hassan

    2015-01-01

    Highlights: • Laser irradiation effects on Si surface have been explored. • An Excimer Laser was used as a source. • SEM analysis was performed to explore surface morphology. • Raman spectroscopy analysis was carried out to find crystallographical alterations. - Abstract: Laser-induced surface and structural modification of silicon (Si) has been investigated under three different environments of vacuum, nitrogen (100 Torr) and ethanol. The interaction of 1000 pulses of KrF (λ ≈ 248 nm, τ ≈ 18 ns, repetition rate ≈ 30 Hz) Excimer laser at two different fluences of 2.8 J/cm 2 and 4 J/cm 2 resulted in formation of various kinds of features such as laser induced periodic surface structures (LIPSS), spikes, columns, cones and cracks. Surface morphology has been observed by Scanning Electron Microscope (SEM). Whereas, structural modification of irradiated targets is explored by Raman spectroscopy. SEM analysis exhibits a non-uniform distribution of micro-scale pillars and spikes at the central ablated regime of silicon irradiated at low laser fluence of 2.8 J/cm 2 under vacuum. Whereas cones, pits, cavities and ripples like features are seen at the boundaries. At higher fluence of 4 J/cm 2 , laser induced periodic structures as well as micro-columns are observed. In the case of ablation in nitrogen environment, melting, splashing, self-organized granular structures and cracks along with redeposition are observed at lower fluence. Such types of small scaled structures in nitrogen are attributed to confinement and shielding effects of nitrogen plasma. Whereas, a crater with multiple ablative layers is formed in the case of ablation at higher fluence. Significantly different surface morphology of Si is observed in the case of ablation in ethanol. It reveals the formation of cavities along with small scale pores and less redeposition. These results reveal that the growth of surface and morphological features of irradiated Si are strongly dependent upon the

  12. Biomodulatory effects of laser irradiation on dental pulp cells in vitro

    Science.gov (United States)

    Milward, Michael R.; Hadis, Mohammed A.; Cooper, Paul R.; Gorecki, Patricia; Carroll, James D.; Palin, William M.

    2015-03-01

    Low level laser/light therapy (LLLT) or photobiomodulation is a biophysical approach that can be used to reduce pain, inflammation and modulate tissue healing and repair. However, its application has yet to be fully realized for dental disease treatment. The aim of this study was to assess the modulation of dental pulp cell (DPC) responses using two LLLT lasers with wavelengths of 660nm and 810nm. Human DPCs were isolated and cultured in phenol-red-free α- MEM/10%-FCS at 37°C in 5% CO2. Central wells of transparent-based black walled 96-microplates were seeded with DPCs (passages 2-4; 150μL; 25,000 cell/ml). At 24h post-seeding, cultures were irradiated using a Thor Photomedicine LLLT device (THOR Photomedicine, UK) at 660nm (3, 6 or 13s to give 2, 5 and 10J/cm2) or 810nm (for 1, 2 or 5s to deliver 5, 10 and 20J/cm2). Metabolic activity was assessed via a modified MTT assay 24h post-irradiation. Statistical differences were identified using analysis of variance and post-hoc Tukey tests (P=0.05) and compared with nonirradiated controls. Significantly higher MTT activity was obtained for both lasers (P0.05). Consequently, enhanced irradiation parameters was apparent for both lasers. These parameters should be further optimised to identify the most effective for therapeutic application.

  13. Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

    Science.gov (United States)

    Tadano, Shigeru; Yamada, Satoshi; Kanaoka, Masaru

    2014-01-01

    Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

  14. Determination of ablation threshold for composite resins and amalgam irradiated with femtosecond laser pulses

    International Nuclear Information System (INIS)

    Freitas, A Z; Samad, R E; Zezell, D M; Vieira Jr, N D; Freschi, L R; Gouw-Soares, S C

    2010-01-01

    The use of laser for caries removal and cavity preparation is already a reality in the dental clinic. The objective of the present study was to consider the viability of ultrashort laser pulses for restorative material selective removal, by determining the ablation threshold fluence for composite resins and amalgam irradiated with femtosecond laser pulses. Lasers pulses centered at 830 nm with 50 fs of duration and 1 kHz of repetition rate, with energies in the range of 300 to 770 μJ were used to irradiate the samples. The samples were irradiated using two different geometrical methods for ablation threshold fluence determinations and the volume ablation was measured by optical coherence tomography. The shape of the ablated surfaces were analyzed by optical microscopy and scanning electron microscopy. The determined ablation threshold fluence is 0.35 J/cm 2 for the composite resins Z-100 and Z-350, and 0.25 J/cm 2 for the amalgam. These values are half of the value for enamel in this temporal regime. Thermal damages were not observed in the samples. Using the OCT technique (optical coherence tomography) was possible to determine the ablated volume and the total mass removed

  15. Microstructure analysis of magnesium alloy melted by laser irradiation

    International Nuclear Information System (INIS)

    Liu, S.Y.; Hu, J.D.; Yang, Y.; Guo, Z.X.; Wang, H.Y.

    2005-01-01

    The effects of laser surface melting (LSM) on microstructure of magnesium alloy containing Al8.57%, Zn 0.68%, Mn0.15%, Ce0.52% were investigated. In the present work, a pulsed Nd:YAG laser was used to melt and rapidly solidify the surface of the magnesium alloy with the objective of changing microstructure and improving the corrosion resistance. The results indicate that laser-melted layer contains the finer dendrites and behaviors good resistance corrosion compared with the untreated layer. Furthermore, the absorption coefficient of the magnesium alloy has been estimated according to the numeral simulation of the thermal conditions. The formation process of fine microstructure in melted layers was investigated based on the experimental observation and the theoretical analysis. Some simulation results such as the re-solidification velocities are obtained. The phase constitutions of the melted layers determined by X-ray diffraction were β-Mg 17 Al 12 and α-Mg as well as some phases unidentified

  16. Measurements of Electron Transport in Foils Irradiated with a Picosecond Time Scale Laser Pulse

    International Nuclear Information System (INIS)

    Brown, C. R. D.; Hoarty, D. J.; James, S. F.; Swatton, D.; Hughes, S. J.; Morton, J. W.; Guymer, T. M.; Hill, M. P.; Chapman, D. A.; Andrew, J. E.; Comley, A. J.; Shepherd, R.; Dunn, J.; Chen, H.; Schneider, M.; Brown, G.; Beiersdorfer, P.; Emig, J.

    2011-01-01

    The heating of solid foils by a picosecond time scale laser pulse has been studied by using x-ray emission spectroscopy. The target material was plastic foil with a buried layer of a spectroscopic tracer material. The laser pulse length was either 0.5 or 2 ps, which resulted in a laser irradiance that varied over the range 10 16 -10 19 W/cm 2 . Time-resolved measurements of the buried layer emission spectra using an ultrafast x-ray streak camera were used to infer the density and temperature conditions as a function of laser parameters and depth of the buried layer. Comparison of the data to different models of electron transport showed that they are consistent with a model of electron transport that predicts the bulk of the target heating is due to return currents.

  17. Characteristics of laser irradiated Hg sub 0 ,835 Cd sub 0 ,165 Te analysed by resonant Raman spectroscopy

    International Nuclear Information System (INIS)

    Scepanovic, M.; Jevtic, M.

    1998-01-01

    The characteristics of Hg sub 0 ,835 Cd sub 0 ,165 Te sample irradiated by a nanosecond Nd: YAG laser pulse are investigated using a resonant Raman spectroscopy. The pulse energy density of 100 mJ/cm sup 2 is close to the energy threshold of material melting under the irradiated conditions. The presented Raman spectra of the unirradiated and irradiated sample parts point out that the laser irradiation induced a little concentration change in the surface sample layers without the essential structural changes (author)

  18. Important factors for cell-membrane permeabilization by gold nanoparticles activated by nanosecond-laser irradiation

    Directory of Open Access Journals (Sweden)

    Yao CP

    2017-08-01

    Full Text Available Cuiping Yao,1,2,* Florian Rudnitzki,2,* Gereon Hüttmann,2,3 Zhenxi Zhang,1 Ramtin Rahmanzadeh2 1Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Biomedical Analytical Technology and Instrumentation, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China; 2Institute of Biomedical Optics, University of Lübeck, Lübeck, 3Airway Research Center North (ARCN, Member of the German Center for Lung Research (DZL, Kiel, Germany *These authors contributed equally to this work Purpose: Pulsed-laser irradiation of light-absorbing gold nanoparticles (AuNPs attached to cells transiently increases cell membrane permeability for targeted molecule delivery. Here, we targeted EGFR on the ovarian carcinoma cell line OVCAR-3 with AuNPs. In order to optimize membrane permeability and to demonstrate molecule delivery into adherent OVCAR-3 cells, we systematically investigated different experimental conditions. Materials and methods: AuNPs (30 nm were functionalized by conjugation of the antibody cetuximab against EGFR. Selective binding of the particles was demonstrated by silver staining, multiphoton imaging, and fluorescence-lifetime imaging. After laser irradiation, membrane permeability of OVCAR-3 cells was studied under different conditions of AuNP concentration, cell-incubation medium, and cell–AuNP incubation time. Membrane permeability and cell viability were evaluated by flow cytometry, measuring propidium iodide and fluorescein isothiocyanate–dextran uptake. Results: Adherently growing OVCAR-3 cells can be effectively targeted with EGFR-AuNP. Laser irradiation led to successful permeabilization, and 150 kDa dextran was successfully delivered into cells with about 70% efficiency. Conclusion: Antibody-targeted and laser-irradiated AuNPs can be used to deliver molecules into adherent cells. Efficacy depends not only on laser parameters but also on AuNP:cell ratio, cell-incubation medium

  19. Influence of He-Ne laser irradiation of soybean seeds on seed mycoflora, growth, nodulation, and resistance to Fusarium solani

    International Nuclear Information System (INIS)

    Ouf, S.A.; Abdel-Hady, N.F.

    1999-01-01

    Laser irradiation of soybean seeds for 3 min caused a clear reduction in the number of seed-borne fungi which became more pronounced as the irradiation time was extended. Pretreatment of the seeds with methylene blue, methyl red and carmine enhanced the effect of laser. Rhizoctonia solani, Alternaria tenuissima, Cercospora kikuchii and Colletotrichum truncatum were completely eliminated when the seeds were pretreated with a dye and irradiated for 10 min. Seed germination was stimulated on exposure of the seed to 1-min irradiation. Chlorophyll a, chlorophyll b and carotenoid content of developed plants differed, depending on the irradiation dose and dye treatment of the seeds. The number and dry mass of nodules were mostly greater (as compared to the corresponding control), when the seeds irradiated for 1 or 3 min were pretreated with methyl red, chlorophenol red, crystal violet and methylene blue. Irradiation of pre-sowing seeds greatly protected soybean stands against F. solani

  20. Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment.

    Science.gov (United States)

    Liu, Neng; Moumanis, Khalid; Dubowski, Jan J

    2015-11-09

    The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75°. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm(2), respectively, has decreased the CA to near 15°, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer's surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm(2) and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103°. The XPS results indicate ArF laser induced formation of Si-(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

  1. Irradiation effects of GaAlAs (λ=830 nm) laser on oral traumatic ulceration

    International Nuclear Information System (INIS)

    Senna, Andre Machado de

    2003-01-01

    Low intensity GaAlAs (λ=830 nm) laser irradiation effects on oral traumatic ulceration were evaluated. For this purpose, twenty patients presenting orthodontic appliance - induced oral traumatic ulceration were randomly distributed in two groups. Patients in group 1 were submitted to the irradiation procedure and group 2 was the control one. The irradiation parameters employed were the following: wavelength 830 nm, one single application of 4 J/cm 2 , punctual in the contact mode and 30 mW power. The control group received the conventional treatment, consisting on topical application of Triancinolon based ointment four times a day. For both groups the agent responsible for the trauma was removed or covered with utility wax whenever removal was impossible. The results were evaluated concerning the wounds size reduction and pain relief. The time of laser irradiation was considered the starting time (time zero) and analysis were done 24 hours, 48 hours and seven days after that. The statistical analysis showed an acceleration in the healing process as well accentuated pain reduction for the irradiated group compared to the control one. These evidences allows us to indicate this protocol of one single application of 4 J/cm 2 as therapy when patients with oral traumatic ulceration can not attend several sessions for a multiple application procedure. (author)

  2. Soliton formation at critical density in laser-irradiated plasmas

    International Nuclear Information System (INIS)

    Anderson, D.; Bondeson, A.; Lisak, M.

    1979-01-01

    The generation of Langmuir solitons at the resonance layer in a plasma irradiated by a strong high-frequency pump is investigated. The process is modelled by the nonlinear Schrodinger equation including an external pump, a density gradient and linear damping. The evolution equation is reformulated as an exact variational principle and the one-soliton generation process is studied by substituting various trial solutions. The applicability conditions for the nonlinear Schrodinger equation are re-examined and found to be more restrictive than previously stated. (author)

  3. Measurement of the surface-enhanced coherent anti-Stokes Raman scattering (SECARS) due to the 1574 cm(-1) surface-enhanced Raman scattering (SERS) mode of benzenethiol using low-power (CW diode lasers.

    Science.gov (United States)

    Aggarwal, Roshan L; Farrar, Lewis W; Greeneltch, Nathan G; Van Duyne, Richard P; Polla, Dennis L

    2013-02-01

    The surface-enhanced coherent anti-Stokes Raman scattering (SECARS) from a self-assembled monolayer (SAM) of benzenethiol on a silver-coated surface-enhanced Raman scattering (SERS) substrate has been measured for the 1574 cm(-1) SERS mode. A value of 9.6 ± 1.7×10(-14) W was determined for the resonant component of the SECARS signal using 17.8 mW of 784.9 nm pump laser power and 7.1 mW of 895.5 nm Stokes laser power; the pump and Stokes lasers were polarized parallel to each other but perpendicular to the grooves of the diffraction grating in the spectrometer. The measured value of resonant component of the SECARS signal is in agreement with the calculated value of 9.3×10(-14) W using the measured value of 8.7 ± 0.5 cm(-1) for the SERS linewidth Γ (full width at half-maximum) and the value of 5.7 ± 1.4×10(-7) for the product of the Raman cross section σSERS and the surface concentration Ns of the benzenethiol SAM. The xxxx component of the resonant part of the third-order nonlinear optical susceptibility |3 χxxxx((3)R)| for the 1574 cm(-1) SERS mode has been determined to be 4.3 ± 1.1×10(-5) cm·g(-1)·s(2). The SERS enhancement factor for the 1574 cm(-1) mode was determined to be 3.6 ± 0.9×10(7) using the value of 1.8×10(15) molecules/cm(2) for Ns.

  4. Assessment of the bacteria reduction in the infected root canal irradiated with diode laser

    International Nuclear Information System (INIS)

    Radaelli, Claudia Amaral Rabello de Mello

    2002-01-01

    High success rates are achieved in conventional endodontic treatment of vital pulp teeth. However, in cases of non-vital pulp, a decrease in the rate of success occurs due to difficulties in achieving a complete disinfection of the root canals system. Some bacteria, such as Enterococcus faecalis, are frequently found in cases of endodontic treatment failure due to their high resistance to the conventional endodontic treatment. The aim of this study was to evaluate the efficiency of a high power diode laser irradiation in bacterial reduction of contaminated canals associated with dressing compose by calcium hydroxide paste propylene glycol and camphorated paramonochlorophenol. Eighty-two root canals were infected in vitro with Enterococcus faecalis in a concentration of 1x10 8 CFU/ml. Specimens were high intensity irradiated with a diode laser model Opus 10, at a wavelength of 830 nm. Two different parameters were employed in continuous mode: 3 W and 2,5 W with a 360 μm optical fiber at an angle of approximately 5 degrees respect to the dentine surface during 5 seconds, in 4 applications, with 20 seconds intervals among them. After these proceedings specimens were vortexed in peptone water and dilutions performed. Aliquots of the dilution were plated on m-Enterococcus agar, incubated, and the Colonies Forming Units (CFU) of ali groups was counted. The results showed a significant reduction of bacteria on ali groups after laser irradiation. A high reduction rate was achieved: 98.5% immediately after the laser irradiation; 48 hours after, the reduction was of 96,73% and, finally, a 100% reduction was achieved through the combination of laser irradiation and a long lasting dressing of calcium hydroxide paste, propylene glycol and camphorated paramonochlorophenol. High rates of bacteria reduction were achieved using the parameter of 3 W in continuous mode with the power of 2,9473 KW/cm 2 . The temperature was monitored with a K-pipe thermocouple placed at the

  5. Sb2S3:C/CdS p-n junction by laser irradiation

    International Nuclear Information System (INIS)

    Arato, A.; Cardenas, E.; Shaji, S.; O'Brien, J.J.; Liu, J.; Castillo, G. Alan; Das Roy, T.K.; Krishnan, B.

    2009-01-01

    In this paper, we report laser irradiated carbon doping of Sb 2 S 3 thin films and formation of a p-n junction photovoltaic structure using these films. A very thin carbon layer was evaporated on to chemical bath deposited Sb 2 S 3 thin films of approximately 0.5 μm in thickness. Sb 2 S 3 thin films were prepared from a solution containing SbCl 3 and Na 2 S 2 O 3 at 27 deg. C for 5 h and the films obtained were highly resistive. These C/Sb 2 S 3 thin films were irradiated by an expanded laser beam of diameter approximately 0.5 cm (5 W power, 532 nm Verdi laser), for 2 min at ambient atmosphere. Morphology and composition of these films were analyzed. These films showed p-type conductivity due to carbon diffusion (Sb 2 S 3 :C) by the thermal energy generated by the absorption of laser radiation. In addition, these thin films were incorporated in a photovoltaic structure Ag/Sb 2 S 3 :C/CdS/ITO/Glass. For this, CdS thin film of 50 nm in thickness was deposited on a commercially available ITO coated glass substrate from a chemical bath containing CdCl 2 , sodium citrate, NH 4 OH and thiourea at 70 deg. C . On the CdS film, Sb 2 S 3 /C layers were deposited. This multilayer structure was subjected to the laser irradiation, C/Sb 2 S 3 side facing the beam. The p-n junction formed by p-Sb 2 S 3 :C and n-type CdS showed V oc = 500 mV and J sc = 0.5 mA/cm 2 under illumination by a tungsten halogen lamp. This work opens up a new method to produce solar cell structures by laser assisted material processing

  6. Stimulation of DNA synthesis by 340nm/ 351nm UV laser irradiation

    International Nuclear Information System (INIS)

    Meldrum, R.A.; Wharton, C.W.

    1991-01-01

    During preliminary experiments designed to test the feasibility of using a 'caged' DNA break trapping agent, the authors observed a stimulation of incorporation of 3 H-thymidine into DNA when cells were irradiated with low doses (100-1000J/m 2 ) of 351nm UV laser irradiation. This wavelength is used to photolyse 'caged' dideoxynucleotides in our fast time course measurements of DNA repair in mammalian cells. The dose at which this stimulation was observed is well below that at which measurable damage is detected. (author)

  7. Influence of IR-laser irradiation on α-SiC-chromium silicides ceramics

    International Nuclear Information System (INIS)

    Vlasova, M.; Marquez Aguilar, P.A.; Resendiz-Gonzalez, M.C.; Kakazey, M.; Bykov, A.; Gonzalez Morales, I.

    2005-01-01

    This project investigated the influence of IR-laser irradiation (λ = 1064 nm, P = 240 mW) on composite ceramics SiC-chromium silicides (CrSi 2 , CrSi, Cr 5 Si 3 ) by methods of X-ray diffraction, electron microscopy, atomic force microscopy, and X-ray microanalysis. Samples were irradiated in air. It was established that a surface temperature of 1990 K was required to melt chromium silicides, evaporate silicon from SiC, oxidize chromium silicides, and enrich superficial layer by carbon and chromium oxide

  8. Monitoring of the morphologic reconstruction of deposited ablation products in laser irradiation of silicon

    Directory of Open Access Journals (Sweden)

    Vlasova M.

    2008-01-01

    Full Text Available Using electron microscopy, atomic force microscopy, X-ray microanalysis, and IR spectroscopy, it was established that, in the regime of continuous laser irradiation of silicon at P = 170 W in different gaseous atmospheres with an oxygen impurity, SiOx composite films with a complex morphology form. The main components of ablation products are clusters that form during flight of ablation products and as a result of separation of SiOx-clusters from the zone of the irradiation channel. The roughness and density of the films depend on the heating temperature of the target surface and the type of deposited clusters.

  9. Structure and composition of enamel and dentin after thermal treatment or infrared laser irradiation

    International Nuclear Information System (INIS)

    Bachmann, Luciano

    2004-01-01

    The main purpose of this work is to identify the crystallographic structure, optical properties, chemical composition and electron paramagnetic signals that laser irradiation or oven heating produces on the tissue. The thermal treatment was conducted in oven with temperature range below 1000 deg C and the laser irradiation with holmium (Ho:YLF - 2,065 μm) and erbium (Er:YAG - 2,94 μm) laser. The tissue characterization was carried out with X-ray diffraction, scanning electron microscopy, ultraviolet and visible transmission spectroscopy, light microscopy, infrared transmission/reflection spectroscopy and electron paramagnetic resonance. The holmium irradiated enamel (600-800 J/cm 2 ) shows the presence of tetracalcium phosphate that coexists with the natural phase (hydroxyapatite). The irradiated dentin shows only the sharper diffraction peaks of the natural phase. The narrows peaks, observed after irradiation, could be assigned to the dentin crystal growth and impurities elimination. Tissue discoloration is observed after thermal treatment with temperatures above 100 deg C. Heated enamel become white-opaque and the origin is assigned to the water elimination, which promotes higher light scattering by the prismatic structure. On the other hand, heated dentin, with similar temperatures becomes brown. The dentin browning changes with the temperature and shown two peaks, at 375 deg C and 700 deg C. The peak at 375 deg C is assigned to the collagen structure degradation and at 700 deg C to the cyanate formation. The dentin discoloration produced with temperatures below 200 deg C is reversible after the tissue hydration. Both enamel and dentin discoloration are also observed in erbium irradiated tissues. Thermal treatments, heating in oven or laser irradiation, change mainly the organic matrix composition and water present in the tissues. The inorganic matrix is more stable and its radicals are changed, with more predominance, only at temperatures higher than 500 deg

  10. Optimal dye concentration and irradiance for laser-assisted vascular anastomosis.

    Science.gov (United States)

    Ren, Zhen; Xie, Hua; Lagerquist, Kathryn A; Burke, Allen; Prahl, Scott; Gregory, Kenton W; Furnary, Anthony P

    2004-04-01

    This investigation was done in order to find optimal indocyanine green (ICG) concentration and energy irradiance in laser vascular welding. Many studies have shown that laser tissue welding with albumin solder/ICG may be an effective technique in surgical reconstruction. However, there are few reports regarding optimal laser settings and concentrations of ICG within the albumin solder in laser-assisted vascular anastomosis. Porcine carotid artery strips (n = 120) were welded in end-to-end by diode laser with 50% albumin solder of 0.01, 0.1, and 1.0 mM ICG at irradiance of 27.7, 56.7, and 76.9 W/cm(2), respectively. Temperature was measured by inserting thermocouples outside and inside the vessel. Tensile strength and histology were studied. Temperature and strength of the anastomosis significantly decreased (all p < 0.05) with increasing ICG concentration at 56.7 W/cm(2). Histological study showed minimal thermal injury limited to adventitia and no appreciable difference between all groups. ICG concentration within solder is the most important factor affecting both vascular temperature and tensile strength. The optimal balance between strength and minimal thermal injury may be achieved primarily at 56.7 W/cm(2) and 0.01 mM ICG.

  11. Hydrophilicity and morphological investigation of polycarbonate irradiated by ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Jaleh, B. [Bu-Ali-Sina University, Physics Department, Postal Code 65174, Hamedan (Iran, Islamic Republic of)], E-mail: jaleh@basu.ac.ir; Parvin, P. [Amir Kabir University of Technology, Physics Department, P.O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sheikh, N. [Nuclear Science and Technology Research Institute, Radiation Applications Research School, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sajad, B. [Azzahra University, Physics Department, Tehran (Iran, Islamic Republic of)

    2007-12-15

    Lasers are used to modify polymeric materials. In this work, a number of polycarbonate (PC) pieces were exposed by ArF excimer laser, 193 nm, at various UV doses from 10 to 100 J/cm{sup 2} with 50-500 mJ/pulse at 10 Hz pulse repetition rate. Morphology of PC has been investigated by scanning electron microscope (SEM) at three regimes pre-ablation, slow and fast ablation. SEM identifies that the conical defects are created on the polymer surface to grow opposite to the direction of laser irradiation. It increases the superficial absorptivity of the material dependent on the ArF laser induced conical microstructure geometry. The contact angle measurement was performed here, in order to determine the hydrophilicity of the irradiated polymer at various coherent doses. It is shown that the contact angle of PC samples which are exposed to the ArF laser significantly alters with UV dose below 7 J/cm{sup 2}.

  12. The effect of gamma-irradiation on laser ablation of polyketone

    International Nuclear Information System (INIS)

    Golodkov, O.N.; Ol'khov, Yu.A.; Allayarov, S.R.; Belov, G.P.; Ivanov, L.F.; Kalinin, L.A.; Grakovich, P.N.

    2013-01-01

    Results of a pioneering study of the effect of laser radiation in vacuum on the surface of a polyketone (alternating terpolymer of ethylene, propylene, and carbon monoxide, POK) plate are presented. The preliminary γirradiation of POK to a dose of 100 kGy enhances its laser ablation rate. It has been found that laser beam irradiation leads to the surface heating of the plate, its melting, and the formation of a characteristic surface microrelief, an ablation crater, from which the gas flow of the ablation plume carries away products that are deposited on surfaces outside the laser beam area to form a coating with a chemical composition close to that of the substrate POK. A rim grows from molten POK around the crater. The melting point of the crystalline modification (377 K), the molecular flow temperature (427 K), and the molecular weight of the coating (25 560) are much lower than those of the initial POK (464 K, 477 K, and 159200, respectively), thereby indicating laser - induced chain degradation of POK. (authors)

  13. 'In vitro' study of the efficacy of diode laser and LED irradiation during dental bleaching

    International Nuclear Information System (INIS)

    Barroso, Marcia Cristina da Silva

    2003-01-01

    This in vitro study evaluated the efficacy of LED and laser diode irradiation during the dental bleaching procedure, using two bleaching agents (Opalescence X-tra and HP Whiteness). The diode laser and the LED were operated in the continuous mode, with wavelength of 808 nm and 470 nm, respectively. The results of the irradiations were characterized with the CIELAB system calculating the L * a * b * values for the darkened and the bleached teeth (60 bovine incisors). This is to our knowledge the first time that light sources laser and LED are compared with respect to their whitening capability when applied to different agents. Significant differences in the chroma value are obtained for the two whitening agents and for the different light sources, too. Also, in terms of luminance, the combination of laser/ Whiteness HP showed significantly better results than when the same agent was used alone or in combination with LED. Best overall results are obtained with the combination of Whiteness HP and laser. (author)

  14. Mathematical simulation of the thermal diffusion in dentine irradiated with Nd:YAG laser using finite difference method

    Science.gov (United States)

    Moriyama, Eduardo H.; Zangaro, Renato A.; Lobo, Paulo D. d. C.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Pacheco, Marcos T. T.; Otsuka, Daniel K.

    2002-06-01

    Thermal damage in dental pulp during Nd:YAG laser irradiation have been studied by several researchers; but due to dentin inhomogeneous structure, laser interaction with dentin in the hypersensitivity treatment are not fully understood. In this work, heat distribution profile on human dentine samples irradiated with Nd:YAG laser was simulated at surface and subjacent layers. Calculations were carried out using the Crank-Nicolson's finite difference method. Sixteen dentin samples with 1,5 mm of thickness were evenly distributed into four groups and irradiated with Nd:YAG laser pulses, according to the following scheme: (I) 1 pulse of 900 mJ, (II) 2 pulses of 450 mJ, (III) 3 pulses of 300 mJ, (IV) 6 pulses of 150 mJ; corresponding to a total laser energy of 900 mJ. The pulse interval was 300ms, the pulse duration of 900 ms and irradiated surface area of 0,005 mm2. Laser induced morphological changes in dentin were observed for all the irradiated samples. The heat distribution throughout the dentin layer, from the external dentin surface to the pulpal chamber wall, was calculated for each case, in order to obtain further information about the pulsed Nd:YAG laser-oral hard tissue interaction. The simulation showed significant differences in the final temperature at the pulpal chamber, depending on the exposition time and the energy contained in the laser pulse.

  15. Electron emission from laser irradiating target normal sheath acceleration (TNSA)

    Czech Academy of Sciences Publication Activity Database

    Torrisi, L.; Cutroneo, Mariapompea

    2016-01-01

    Roč. 171, 9-10 (2016), s. 754-765 ISSN 1042-0150. [12th Workshop on European Collaboration for Higher Education and Research in Nuclear Engineering and Radiological Protection. Bologna, Catania, Milan, 30.05.2016-01.06.2016] R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : electron emission from plasma * TNSA * TOF * SiC * plastic scintillator * Thomson parabola spectrometer Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.443, year: 2016

  16. Smart skin structures for identifying and locating laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    LaDelfe, P.C.; Goeller, R.M.; Murray, H.S.

    1992-12-31

    A pyramidal arrangement of wavelength-selective optical detectors can be used to determine the identity (wavelength), intensity, and direction-of-arrival of faser irradiation. The advantages of this technique are that only unobtrusive, skin-like structures are required and that large collection areas provide high sensitivity. The disadvantage is that the angular resolution (approximately 5 degrees in a 60 degree field-of--view) is less than that which can be achieved using methods requiring thicker structures. The detector elements are large-area, polyvinylidine fluoride, pyroelectric devices with wavelength selective coatinits. Four identical arrays of these elements are situated on the top and sides of a frustrated, three--sided prism. Since only the relative orientations are significant, these faces can be selected regions on the surface of an existing structure. We first describe the construction of the detectors and the system, then develop the mathematical description of the system. Using coated detectors whose performance has been experimentally verified, we will model the response to in-channel, monochromatic irradiation and then describe the data analysis algorithm. Although we will limit our model to a simple, two-channel system, the concept and algorithm can easily be extended to a system of any reasonable number of nonoverlapping channels.

  17. Smart skin structures for identifying and locating laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    LaDelfe, P.C.; Goeller, R.M.; Murray, H.S.

    1992-01-01

    A pyramidal arrangement of wavelength-selective optical detectors can be used to determine the identity (wavelength), intensity, and direction-of-arrival of faser irradiation. The advantages of this technique are that only unobtrusive, skin-like structures are required and that large collection areas provide high sensitivity. The disadvantage is that the angular resolution (approximately 5 degrees in a 60 degree field-of--view) is less than that which can be achieved using methods requiring thicker structures. The detector elements are large-area, polyvinylidine fluoride, pyroelectric devices with wavelength selective coatinits. Four identical arrays of these elements are situated on the top and sides of a frustrated, three--sided prism. Since only the relative orientations are significant, these faces can be selected regions on the surface of an existing structure. We first describe the construction of the detectors and the system, then develop the mathematical description of the system. Using coated detectors whose performance has been experimentally verified, we will model the response to in-channel, monochromatic irradiation and then describe the data analysis algorithm. Although we will limit our model to a simple, two-channel system, the concept and algorithm can easily be extended to a system of any reasonable number of nonoverlapping channels.

  18. Influences on target irradiation symmetry in CO2 laser-fusion experiments

    International Nuclear Information System (INIS)

    Carman, R.L.

    1981-01-01

    The existence of very steep density profiles and high upper shelf densities imply that the CO 2 laser deposits its energy spatially quite close to the ablation surface where calculations indicate that a high degree of symmetry must exist in order to achieve the necessary high compression ratios. Thus, energy transport provides only limited improvement in the ablative symmetry over that achieved in the irradiation symmetry. Current data suggests that a balance between radiation pressure and hydrodynamic pressure underestimates the density to which the CO 2 laser light penetrates for early times

  19. Internal stress distribution for generating closure domains in laser-irradiated Fe–3%Si(110) steels

    International Nuclear Information System (INIS)

    Iwata, Keiji; Imafuku, Muneyuki; Orihara, Hideto; Sakai, Yusuke; Ohya, Shin-Ichi; Suzuki, Tamaki; Shobu, Takahisa; Akita, Koichi; Ishiyama, Kazushi

    2015-01-01

    Internal stress distribution for generating closure domains occurring in laser-irradiated Fe–3%Si(110) steels was investigated using high-energy X-ray analysis and domain theory based on the variational principle. The measured triaxial stresses inside the specimen were compressive and the stress in the rolling direction became more dominant than stresses in the other directions. The calculations based on the variational principle of magnetic energy for closure domains showed that the measured triaxial stresses made the closure domains more stable than the basic domain without closure domains. The experimental and calculation results reveal that the laser-introduced internal stresses result in the occurrence of the closure domains

  20. Wound healing in porcine skin following low-output carbon dioxide laser irradiation of the incision

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, J.K.; Garden, J.M.; Taute, P.M.; Leibovich, S.J.; Lautenschlager, E.P.; Hartz, R.S.

    1987-06-01

    Wound healing of scalpel incisions to the depth of adipose tissue closed with conventional methods was compared with closure by low-output carbon dioxide laser irradiation. In 3 Pitman-Moore minipigs wound healing was evaluated at intervals from 1 to 90 days by the following methods: clinical variables of wound healing; formation of the basement membrane components bullous pemphigoid antigen, laminin, and fibronectin; and histological evaluation of the regeneration of the epidermis, neovascularization, and elastin and collagen formation. There was no significant difference in healing between wounds closed by the various conventional methods and by the low-output carbon dioxide laser.

  1. Mono-energetic ions emission by nanosecond laser solid target irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Muoio, A., E-mail: Annamaria.Muoio@lns.infn.it [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Tudisco, S. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Altana, C. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lanzalone, G. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Università degli Studi di Enna “Kore”, Via delle Olimpiadi, 94100 Enna (Italy); Mascali, D.; Cirrone, G.A.P.; Schillaci, F. [Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy); Trifirò, A. [Dipartimento di Fisica e Scienze della Terra, Università degli Studi di Messina, Viale F.S. D’Alcontres 31, 98166 Messina (Italy); Sezione INFN, Catania (Italy)

    2016-09-01

    An experimental campaign aiming to investigate the acceleration mechanisms through laser–matter interaction in nanosecond domain has been carried out at the LENS (Laser Energy for Nuclear Science) laboratory of INFN-LNS, Catania. Pure Al targets were irradiated by 6 ns laser pulses at different pumping energies, up to 2 J. Advanced diagnostics tools were used to characterize the plasma plume and ion production. We show the preliminary results of this experimental campaign, and especially the ones showing the production of multicharged ions having very narrow energy spreads.

  2. Lateral propagation of fast electrons at the laser-irradiated target surfaces

    International Nuclear Information System (INIS)

    Li, Y T; Lin, X X; Liu, B C; Du, F; Wang, S J; Li, C; Zhou, M L; Zhang, L; Liu, X; Wang, J; Liu, X L; Chen, L M; Wang, Z H; Ma, J L; Wei, Z Y; Zhang, J; Liu, F; Liu, F

    2010-01-01

    Lateral propagation of fast electrons at the target surfaces irradiated by femtosecond intense laser pulses is measured by k α x-ray imaging technique when a preplasma is presented. An annular halo surrounding a bright spot is observed in the x-ray images when the scale length of the electron density is large. For an incidence angle of 70 0 the x-ray images show a non-symmetrical distribution peaked to the laser propagation direction. The x-ray photons in the halo are mainly excited by the fast electrons that flow in the preplasma when their paths intersect the high density regions near the target surface.

  3. Human dental enamel and dentin structural effects after Er:YAG laser irradiation.

    Science.gov (United States)

    Lima, Darlon Martíns; Tonetto, Mateus Rodrigues; de Mendonça, Adriano Augusto Melo; Elossais, André Afif; Saad, José Roberto Cury; de Andrade, Marcelo Ferrarezi; Pinto, Shelon Cristina Souza; Bandéca, Matheus Coelho

    2014-05-01

    Ideally projected to be applied on soft tissues, infrared lasers were improved by restorative dentistry to be used in hard dental tissues cavity preparations--namely enamel and dentin. This paper evidentiates the relevant aspects of infrared Erbium laser's action mechanism and its effects, and characterizes the different effects deriving from the laser's beams emission. The criteria for use and selection of optimal parameters for the correct application of laser systems and influence of supporting factors on the process, such as water amount and its presence in the ablation process, protection exerted by the plasma shielding and structural factors, which are indispensable in dental tissues cavity preparation related to restorative technique, are subordinated to optical modifications caused by the interaction of the energy dissipated by these laser light emission systems in the targeted tissue substrate. Differences in the action of infrared Erbium laser system in regard to the nature of the ablation process and variations on the morphological aspects observed in the superficial structure of the target tissue irradiated, may be correlated to the structural optical modifications of the substrate produced by an interaction of the energy propagated by laser systems.

  4. Low-Power Public Key Cryptography

    Energy Technology Data Exchange (ETDEWEB)

    BEAVER,CHERYL L.; DRAELOS,TIMOTHY J.; HAMILTON,VICTORIA A.; SCHROEPPEL,RICHARD C.; GONZALES,RITA A.; MILLER,RUSSELL D.; THOMAS,EDWARD V.

    2000-11-01

    This report presents research on public key, digital signature algorithms for cryptographic authentication in low-powered, low-computation environments. We assessed algorithms for suitability based on their signature size, and computation and storage requirements. We evaluated a variety of general purpose and special purpose computing platforms to address issues such as memory, voltage requirements, and special functionality for low-powered applications. In addition, we examined custom design platforms. We found that a custom design offers the most flexibility and can be optimized for specific algorithms. Furthermore, the entire platform can exist on a single Application Specific Integrated Circuit (ASIC) or can be integrated with commercially available components to produce the desired computing platform.

  5. Evaluation of thermal shock strengths for graphite materials using a laser irradiation method

    International Nuclear Information System (INIS)

    Kim, Jae Hoon; Lee, Young Shin; Kim, Duck Hoi; Park, No Seok; Suh, Jeong; Kim, Jeng O.; Il Moon, Soon

    2004-01-01

    Thermal shock is a physical phenomenon that occurs during the exposure to rapidly high temperature and pressure changes or during quenching of a material. The rocket nozzle throat is exposed to combustion gas of high temperature. Therefore, it is important to select suitable materials having the appropriate thermal shock resistance and to evaluate these materials for rocket nozzle design. The material of this study is ATJ graphite, which is the candidate material for rocket nozzle throat. This study presents an experimental method to evaluate the thermal shock resistance and thermal shock fracture toughness of ATJ graphite using laser irradiation. In particular, thermal shock resistance tests are conducted with changes of specimen thickness, with laser source irradiated at the center of the specimen. Temperature distributions on the specimen surface are detected using type K and C thermocouples. Scanning electron microscope (SEM) is used to observe the thermal cracks on specimen surface

  6. New metal-organic nanomaterials synthesized by laser irradiation of organic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmin, Stanislav L.; Wesolowski, Michal J.; Duley, Walter W. [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 (Canada)

    2014-03-31

    A new type of metal-organic composition consisting of clusters of nanoparticles has been synthesised by laser irradiation of metallocene/benzene solutions. The metallocene molecules in this reaction become the source of the metal. Exposure to high-energy femtosecond laser pulses dehydrogenate benzene molecules and initiate the high-temperature high-pressure conditions that results in the synthesis of new materials. Irradiation experiments have been carried out on ferrocene/benzene and on other solutions. With ferrocene the synthesis of a new compound has been confirmed by X-ray powder diffraction as the peaks detected do not correspond to any known substance in the Crystallography Open Database. Theoretical simulation of the periodic structure of this new carbide predicts that it has hexagonal symmetry and a unit cell with a = 3.2A and c =2.8A. The exact structure is still uncertain but may be determined from scanning tunneling microscope (STM) studies.

  7. Experiments with polymer coated microspheres irradiated by the Shiva laser system

    International Nuclear Information System (INIS)

    Auerbach, J.M.; Manes, K.R.; Matthews, D.L.

    1979-01-01

    Polymer coated spherical targets have been irradiated by the Shiva laser system in an effort to compress the contained 10 mg/cc DT fuel to super liquid densities. Glass microspheres of 140 μm ID and 5 μm wall thickness with polymer coatings 15 μm to 100 μm thick have been irradiated with laser pulses of 4 kilojoules in 200 psec FWHM. Target performance was diagnosed with neutron yield measurements, radiochemistry, Argon line imaging, and x-ray imaging techniques. Ball in plate targets achieved greater implosion symmetry than free-standing ball targets. With yields of 10 7 to 10 8 neutrons, targets reached DT fuel compressions of several times liquid density

  8. Reparative processes of the iris after irradiation with the argon-ion laser

    International Nuclear Information System (INIS)

    Huber, G.K.; Zypen, E. van der; Fankhauser, F.

    1979-01-01

    The reparative processes of the pigmented iris of the rabbit were analysed with ultrastructural methods. Clearing of the damaged area by macrophages is the first step in the reparative processes. Clump cells are macrophages which are observed from the first day of the injury until the ninth week. Repair of the anterior surface of the iris is largely finished after 32 days. The repair of collagenous fibres reaches its maximum activity 32 days after irradiation. The pigment epithelium has only an insignificant regeneration potential. Irradiation of the iris by the argon-ion laser results in an atropic, hyperpigmented scar. The rapid regeneration of a lesion induced by the argon-ion laser in the rabbit iris casts doubt as to whether this method could be applied to the human eye with equal success. (orig.) 891 AJ/orig. 892 MB

  9. Pulsed TEA CO2 Laser Irradiation of Titanium in Nitrogen and Carbon Dioxide Gases

    Science.gov (United States)

    Ciganovic, J.; Matavulj, P.; Trtica, M.; Stasic, J.; Savovic, J.; Zivkovic, S.; Momcilovic, M.

    2017-12-01

    Surface changes created by interaction of transversely excited atmospheric carbon dioxide (TEA CO2) laser with titanium target/implant in nitrogen and carbon dioxide gas were studied. TEA CO2 laser operated at 10.6 μm, pulse length of 100 ns and fluence of ˜17 J/cm2 which was sufficient for inducing surface modifications. Induced changes depend on the gas used. In both gases the grain structure was produced (central irradiated zone) but its forms were diverse, (N2: irregular shape; CO2: hill-like forms). Hydrodynamic features at peripheral zone, like resolidified droplets, were recorded only in CO2 gas. Elemental analysis of the titanium target surface indicated that under a nitrogen atmosphere surface nitridation occurred. In addition, irradiation in both gases was followed by appearance of plasma in front of the target. The existence of plasma indicates relatively high temperatures created above the target surface offering a sterilizing effect.

  10. Low Cost, Low Power, High Sensitivity Magnetometer

    Science.gov (United States)

    2008-12-01

    which are used to measure the small magnetic signals from brain. Other types of vector magnetometers are fluxgate , coil based, and magnetoresistance...concentrator with the magnetometer currently used in Army multimodal sensor systems, the Brown fluxgate . One sees the MEMS fluxgate magnetometer is...Guedes, A.; et al., 2008: Hybrid - LOW COST, LOW POWER, HIGH SENSITIVITY MAGNETOMETER A.S. Edelstein*, James E. Burnette, Greg A. Fischer, M.G

  11. Integrated low power ultrasound sensor interfaces

    OpenAIRE

    Gustafsson, Martin

    2005-01-01

    Imagine that the technical development can take the ultrasound measurement systems from the large piece of machinery today, to a coin size system tomorrow. The factor that has reduced the size of electronic systems over time is integration and integrated circuits. In this thesis circuit simulator models of complete ultrasound systems are used to design custom integrated circuits. These circuits are optimized for low power consumption and small size. The models that are used predict the acoust...

  12. Evaluation in vitro of effects of Er:YAG and Nd:YAG lasers irradiation on root canal wall, by stereoscopy, scanning electron micrography and thermographic camera

    International Nuclear Information System (INIS)

    Goya, Claudia

    2001-01-01

    This study was carried out to evaluate in vitro the effects of Nd:YAG laser and Er:YAG laser irradiation in the root canal wall by SEM, evaluating the apical leakage and the temperature changes during the laser irradiation. Seventy four extracted human teeth were used, they were instrumented and divided into seven groups of 10 teeth each. The teeth were evaluated through stereoscopy, by SEM, and with the thermographic camera. The Nd:YAG laser irradiation parameters were 100 mJ/p, 15 Hz, and Er:YAG laser were 160 mJ/p and 10 Hz, the irradiation was 4 times at 2 mm/sec speed, with 20 sec interval. The apical leakage was not observed in the teeth irradiated by Nd:YAG laser alone or in association with Er:YAG laser. However in the teeth irradiated only by the Er:YAG laser we observed a little leakage. By SEM observation the Nd:YAG laser irradiation showed melting and recrystallization in the dentin surface closing dentinal tubules, and in the samples irradiated by Er:Y AG laser a clean surface, opened dentinal tubules, and the combination by two lasers, showed melting covering some dentinal tubules The thermographic study found the temperature increase was not more than 6 deg C. This study showed the safety parameters applications of Er:YAG laser in association with Nd:YAG laser in root canal treatment, in order to not cause thermal damages to the periodontal tissues. (author)

  13. Surgical performance of a 405-nm diode laser in treatment of soft tissue

    International Nuclear Information System (INIS)

    Kato, J; Akashi, G; Moriya, K; Hirai, Y; Hatayama, H; Inoue, A; Miyazaki, H

    2008-01-01

    The study was conducted to evaluate the surgical performance of a 405-nm diode laser ex vivo. The experiments were carried out using tuna tissue, which was irradiated with a 405-nm diode laser at output powers of 400 mW (694 W/cm 2 ) to 1 W (1735 W/cm 2 ) on a motorized stage moving at a rate of 1 mm/sec. As a control, a 920-nm diode laser was used with the same irradiation conditions. After irradiation, the thickness of ablation and coagulation was measured by stereoscopic microscopy and evaluated statistically. Ablation and coagulation zones were obtained with 405-nm laser irradiation, but not with irradiation at 920 nm. Ablation depth increased significantly with output power and a thick coagulation zone was observed with 405-nm irradiation. The 405-nm diode laser performed well for incising and coagulating soft tissue at a low power density

  14. Investigation of the Impact of Transient Heat Loads Applied by Laser Irradiation on ITER-Grade Tungsten

    OpenAIRE

    Huber, Alexander; Arakcheev, A.; Philipps, V.; Pintsuk, Gerald; Reinhart, Michael; Samm, Ulrich; Shoshin, A.; Schweer, Bernd; Unterberg, Bernhard; Zlobinski, M.; Sergienko, Gennady; Steudel, Isabel; Wirtz, Marius; Burdakov, A. V.; Coenen, Jan Willem

    2014-01-01

    Cracking thresholds and crack patterns in tungsten targets after repetitive ITER-like edge localized mode (ELM) pulses have been studied in recent simulation experiments by laser irradiation. The tungsten specimens were tested under selected conditions to quantify the thermal shock response. A Nd:YAG laser capable of delivering up to 32 J of energy per pulse with a duration of 1 ms at the fundamental wavelength λ = 1064 nm has been used to irradiate ITER-grade tungsten samples with repetitive...

  15. A Study of Polycrystalline Silicon Damage Features Based on Nanosecond Pulse Laser Irradiation with Different Wavelength Effects

    OpenAIRE

    Xu, Jiangmin; Chen, Chao; Zhang, Tengfei; Han, Zhenchun

    2017-01-01

    Based on PVDF (piezoelectric sensing techniques), this paper attempts to study the propagation law of shock waves in brittle materials during the process of three-wavelength laser irradiation of polysilicon, and discusses the formation mechanism of thermal shock failure. The experimental results show that the vapor pressure effect and the plasma pressure effect in the process of pulsed laser irradiation lead to the splashing of high temperature and high density melt. With the decrease of the ...

  16. Effects of low intensity laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes

    Science.gov (United States)

    Xiong, Guoxin; Xiong, Leilei; Li, Xinzhong

    2016-09-01

    To investigate the effects of low intensity semiconductor laser acupoint irradiation on inhibiting islet beta-cell apoptosis in rats with type 2 diabetes, a method using a high-fat diet and low-dose intraperitoneal injections of streptozotocin established a type 2 diabetes mellitus rat model. Model rats were randomly divided into a laser acupoint irradiation group, rosiglitazone control group, and placebo group; each group had 10 rats. In addition, 10 normal male rats were selected for the normal control group. The Housanli, Neiting and Yishu acupoints of the rats in the laser acupoint irradiation group were irradiated with a 10 mW semiconductor laser; each point was irradiated for 15 min, once every 2 d over 28 d, for a total of 14 episodes of irradiation. The rosiglitazone group rats were given rosiglitazone (0.2 mg kg-1) intragastrically; the placebo group rats were given 0.9% brine (0.2 mg kg-1) intragastrically, once daily, for four consecutive weeks. The change of fasting blood glucose was determined before and after each treatment. The islet beta-cell apoptosis was determined. The islet beta-cell apoptosis rates of the laser acupoint irradiation group and the rosiglitazone group were significantly lower than the rate of the placebo group. Even though the rate was lower in the laser acupoint irradiation group than in the rosiglitazone group, there was no significant difference between them. It is shown that acupoint irradiation with a semiconductor laser can effectively inhibit islet beta-cell apoptosis in rats with type 2 diabetes.

  17. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  18. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    International Nuclear Information System (INIS)

    Qi, Dongfeng; Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Grigoropoulos, Costas P.; Chen, Songyan

    2016-01-01

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  19. Time-resolved analysis of thickness-dependent dewetting and ablation of silver films upon nanosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Dongfeng [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China); Paeng, Dongwoo; Yeo, Junyeob; Kim, Eunpa; Wang, Letian; Grigoropoulos, Costas P., E-mail: cgrigoro@berkeley.edu [Laser Thermal Laboratory, Department of Mechanical Engineering, University of California, Berkeley, California 94720-1740 (United States); Chen, Songyan [Semiconductor Photonics Research Center, Department of Physics, Xiamen University, Xiamen 361005 (China)

    2016-05-23

    Nanosecond pulsed laser dewetting and ablation of thin silver films is investigated by time-resolved imaging. Laser pulses of 532 nm wavelength and 5 ns temporal width are irradiated on silver films of different thicknesses (50 nm, 80 nm, and 350 nm). Below the ablation threshold, it is observed that the dewetting process does not conclude until 630 ns after the laser irradiation for all samples, forming droplet-like particles in the spot central region. At higher laser intensities, ablative material removal occurs in the spot center. Cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter at about 700 ns following the laser pulse exposure. In addition to these features, droplet fingers are superposed upon irradiation of 350-nm thick silver films with higher intensity.

  20. Surface modification of RuO2 electrodes by laser irradiation and ion ...

    Indian Academy of Sciences (India)

    RuO2 thin layers were deposited on Ti supports by thermal decomposition of RuCl3 at 400°C. Some of the samples were subjected to laser irradiation between 0.5 and 1.5 J cm-2. Some others to Kr bombardment with doses between 1015 and 1016 cm-2. Modifications introduced by the surface treatments were monitored ...

  1. Microvascular blood flow dynamics associated with photodynamic therapy, pulsed dye laser irradiation and combined regimens

    OpenAIRE

    Smith, TK; Choi, B; Ramirez-San-Juan, JC; Nelson, JS; Osann, K; Kelly, KM

    2006-01-01

    Background and Objectives: Previous in vitro studies demonstrated the potential utility of benzoporphyrin derivative monoacid ring A (BPD) photodynamic therapy (PDT) for vascular destruction. Moreover, the effects of PDT were enhanced when this intervention was followed immediately by pulsed dye laser (PDL) irradiation (PDT/ PDL). We further evaluate vascular effects of PDT alone, PDL alone and PDT/PDL in an in vivo rodent dorsal skinfold model. Study Design/Materials and Methods: A dorsal sk...

  2. Quantum-dot temperature profiles during laser irradiation for semiconductor-doped glasses

    International Nuclear Information System (INIS)

    Nagpal, Swati

    2002-01-01

    Temperature profiles around laser irradiated CdX (X=S, Se, and Te) quantum dots in borosilicate glasses were theoretically modeled. Initially the quantum dots heat up rapidly, followed by a gradual increase of temperature. Also it is found that larger dots reach higher temperatures for the same pulse characteristics. After the pulse is turned off, the dots initially cool rapidly, followed by a gradual decrease in temperature

  3. Quantum-dot temperature profiles during laser irradiation for semiconductor-doped glasses

    Science.gov (United States)

    Nagpal, Swati

    2002-12-01

    Temperature profiles around laser irradiated CdX (X=S, Se, and Te) quantum dots in borosilicate glasses were theoretically modeled. Initially the quantum dots heat up rapidly, followed by a gradual increase of temperature. Also it is found that larger dots reach higher temperatures for the same pulse characteristics. After the pulse is turned off, the dots initially cool rapidly, followed by a gradual decrease in temperature.

  4. Search for Rayleigh-Taylor instability in laser irradiated layered thin foil targets

    International Nuclear Information System (INIS)

    Kilkenny, J.D.; Hares, J.D.; Rumsby, P.T.

    1980-01-01

    An experiment to measure the Rayleigh-Taylor instability at the vacuum-ablation surface of laser irradiated layered targets by time resolved x-ray spectroscopy is described. The time taken to burn through a layer of material is measured to be the same for massive targets as for thin foil accelerating targets. It is inferred that the thin foil targets might be Rayleigh-Taylor stable despite the values of γtauapproximately equal to15 calculated from classical theory. (author)

  5. Properties of ZnO whiskers under CO2-laser irradiation

    International Nuclear Information System (INIS)

    Shkumbatyuk, P. S.

    2010-01-01

    Needlelike ZnO single crystals (whiskers) 0.3-0.8 mm long and 1-10 μm in diameter with a resistivity from 3 x 10 2 to 1 Ω cm have been grown under cw CO 2 -laser irradiation. The whiskers exhibit weak electroluminescence caused by injection from contacts with participation of intrinsic defects, which affect the electric field distribution.

  6. Effects of increased low-level diode laser irradiation time on extraction socket healing in rats.

    Science.gov (United States)

    Park, Joon Bong; Ahn, Su-Jin; Kang, Yoon-Goo; Kim, Eun-Cheol; Heo, Jung Sun; Kang, Kyung Lhi

    2015-02-01

    In our previous studies, we confirmed that low-level laser therapy (LLLT) with a 980-nm gallium-aluminum-arsenide diode laser was beneficial for the healing of the alveolar bone in rats with systemic disease. However, many factors can affect the biostimulatory effects of LLLT. Thus, we attempted to investigate the effects of irradiation time on the healing of extraction sockets by evaluating the expressions of genes and proteins related to bone healing. The left and right first maxillary molars of 24 rats were extracted. Rats were randomly divided into four groups in which extraction sockets were irradiated for 0, 1, 2, or 5 min each day for 3 or 7 days. Specimens containing the sockets were examined using quantitative real-time reverse transcription polymerase chain reaction and western blotting. LLLT increased the expressions of all tested genes, Runx2, collagen type 1, osteocalcin, platelet-derived growth factor-B, and vascular endothelial growth factor, in a time-dependent manner. The highest levels of gene expressions were in the 5-min group after 7 days. Five minutes of irradiation caused prominent increases of the expression of all tested proteins after both 3 and 7 days. The expression level of each protein in group 4 was higher by almost twofold compared with group 1 after 7 days. Laser irradiation for 5 min caused the highest expressions of genes and proteins related to bone healing. In conclusion, LLLT had positive effects on the early stages of bone healing of extraction sockets in rats, which were irradiation time-dependent.

  7. Effects of laser acupoint irradiation on blood glucose and glycosylated hemoglobin in type 2 diabetes mellitus

    Science.gov (United States)

    Hui-Hui, Liu; Guo-Xin, Xiong; Li-Ping, Zhang

    2016-06-01

    To investigate the effects of semiconductor laser acupoint irradiation on blood glucose, glycosylated hemoglobin and physical fitness in type 2 diabetes mellitus, 44 cases of type 2 diabetic patients were randomly divided into a control group and a treatment group. All patients in both groups were given a drug treatment. The Hegu, Quchi and Zusanli acupoints of patients in the treatment group were then irradiated daily for 15 d with a 10 MW semiconductor laser. Before and after treatment, patients in both groups underwent a variety of tests and measurements: a two-hour postprandial blood glucose test; a glycosylated hemoglobin test and body mass index (BMI), waist-to-hip ratio (WHR) and body fat percentage (BFP) measurements. The data detected after treatment greatly decreased in the treatment group and was significantly different from that in the control group. It is shown that the acupoint irradiation with a semiconductor laser can improve two-hour postprandial blood glucose, glycosylated hemoglobin and some physical fitness measurements in type 2 diabetes mellitus patients.

  8. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    International Nuclear Information System (INIS)

    Kikuchi, T.; Takahashi, H.; Maruko, T.

    2007-01-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθ stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 μm line width were obtained successfully

  9. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan)]. E-mail: kiku@elechem1-mc.eng.hokudai.ac.jp; Takahashi, H. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan); Maruko, T. [Furuya Metal Co. Ltd., R and D Group, Shimodate Daiichi Kogyodanchi 1915, Morisoejima, Chikusei, Ibaraki (Japan)

    2007-02-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZ{theta} stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 {mu}m line width were obtained successfully.

  10. Ag clustering investigation in laser irradiated ion-exchanged glasses by optical and vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Trave, E., E-mail: enrico.trave@unive.it [Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venezia, Dorsoduro 2137, I-30123 Venezia (Italy); Cattaruzza, E.; Gonella, F.; Calvelli, P. [Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venezia, Dorsoduro 2137, I-30123 Venezia (Italy); Quaranta, A. [Department of Materials Engineering and Industrial Technologies, University of Trento, via Mesiano 77, I-38050 Povo (Italy); Rahman, A.; Mariotto, G. [Department of Computer Science, University of Verona, Strada le Grazie 15, 37134 Verona (Italy)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer We modify the properties of Ag{sup +} exchanged glasses by thermal and laser treatment. Black-Right-Pointing-Pointer The induced microstructural changes are analyzed by optical and Raman spectroscopy. Black-Right-Pointing-Pointer Ag-based species in the glass show a peculiar PL activity in the UV-Vis range. Black-Right-Pointing-Pointer Raman and OA analysis allow for determining the Ag cluster size evolution. Black-Right-Pointing-Pointer Laser processing leads to different cluster formation and fragmentation mechanisms. - Abstract: Ion exchange process is widely used to dope silicate glass layers with silver for several applications, ranging from light waveguide to nanostructured composite glass fabrication. The silver-doped structure and its physical properties depend on the preparation parameters as well as on subsequent treatments. In particular, laser irradiation of the ion exchanged glasses has been demonstrated to be an effective tool to control cluster size and size distribution. Nevertheless, a complete comprehension of the basic phenomena and a systematic characterization of these systems are still lacking. In this paper, an extended optical characterization is presented for soda-lime glass slides, doped with silver by Ag{sup +}-Na{sup +} ion exchange, thermally treated and irradiated with a Nd:YAG laser beam at different wavelengths, and for different energy density. The samples were characterized by various spectroscopic techniques, namely, optical absorption, photoluminescence and micro-Raman analysis. The availability of all these characterization techniques allowed pointing out a suitable scenario for the Ag clustering evolution as a function of the ion exchange, annealing and laser irradiation parameters.

  11. Experimental study on ablative stabilization of Rayleigh-Taylor instability of laser-irradiated targets

    Science.gov (United States)

    Shigemori, Keisuke; Sakaiya, Tatsuhiko; Otani, Kazuto; Fujioka, Shinsuke; Nakai, Mitsuo; Azechi, Hiroshi; Shiraga, Hiroyuki; Tamari, Yohei; Okuno, Kazuki; Sunahara, Atsushi; Nagatomo, Hideo; Murakami, Masakatsu; Nishihara, Katsunobu; Izawa, Yasukazu

    2004-09-01

    Hydrodynamic instabilities are key issues of the physics of inertial confinement fusion (ICF) targets. Among the instabilities, Rayleigh-Taylor (RT) instability is the most important because it gives the largest growth factor in the ICF targets. Perturbations on the laser irradiated surface grow exponentially, but the growth rate is reduced by ablation flow. The growth rate γ is written as Takabe-Betti formula: γ = [kg/(1+kL)]1/2-βkm/pa, where k is wave number of the perturbation, g is acceleration, L is density scale-length, β is a coefficient, m is mass ablation rate per unit surface, and ρa is density at the ablation front. We experimentally measured all the parameters in the formula for polystyrene (CH) targets. Experiments were done on the HIPER laser facility at Institute of Laser Engineering, Osaka University. We found that the β value in the formula is ~ 1.7, which is in good agreements with the theoretical prediction, whereas the β for certain perturbation wavelengths are larger than the prediction. This disagreement between the experiment and the theory is mainly due to the deformation of the cutoff surface, which is created by non-uniform ablation flow from the ablation surface. We also found that high-Z doped plastic targets have multiablation structure, which can reduce the RT growth rate. When a low-Z target with high-Z dopant is irradiated by laser, radiation due to the high-Z dopant creates secondary ablation front deep inside the target. Since, the secondary ablation front is ablated by x-rays, the mass ablation rate is larger than the laser-irradiated ablation surface, that is, further reduction of the RT growth is expected. We measured the RT growth rate of Br-doped polystyrene targets. The experimental results indicate that of the CHBr targets show significantly small growth rate, which is very good news for the design of the ICF targets.

  12. FT-Raman spectroscopic characterization of enamel surfaces irradiated with Nd:YAG and Er:YAG lasers

    Directory of Open Access Journals (Sweden)

    Sima Shahabi

    2016-12-01

    Full Text Available Background. Despite recent advances in dental caries prevention, caries is common and remains a serious health problem. Laser irradiation is one of the most common methods in preventive measures in recent years. Raman spectroscopy technique is utilized to study the microcrystalline structure of dental enamel. In this study, FT-Raman spectroscopy was used to evaluate chemical changes in enamel structure irradiated with Nd:YAG and Er:YAG lasers. Methods. We used 15 freshly-extracted, non-carious, human molars that were treated as follows: No treatment was carried out in group A (control group; Group B was irradiated with Er:YAG laser for 10 seconds under air and water spray; and Group C was irradiated with Nd:YAG laser for 10 seconds under air and water spray. After treatment, the samples were analyzed by FT-Raman spectroscopy. Results. The carbonate content evaluation with regard to the integrated area under the curve (1065/960 cm–1 exhibited a significant reduction in its ratio in groups B and C. The organic content (2935/960 cm-1 area exhibited a significant decrease after laser irradiation in group B and C. Conclusion. The results showed that the mineral and organic matrices of enamel structure were affected by laser irradiation; therefore, it might be a suitable method for caries prevention.

  13. Evaluation of Diode laser (940 nm irradiation effect on microleakage in class V composite restoration before and after adhesive application

    Directory of Open Access Journals (Sweden)

    loghman rezaei

    2018-03-01

    Full Text Available Introduction: Nowadays, the main focus of dental studies is on adhesive dental materials; since clinical long-term success of bonded restorations depended more on marginal microleakage minimization. So, the aim of this study was Evaluation of Diode laser irradiation effect on microleakage in class V composite restoration before and after adhesive application. Materials and methods: In this in vitro-experimental study, standard class V cavity was prepared on lingual and buccal surfaces of 60 premolar teeth. For evaluation of microleakage, 60 teeth were divided randomly into four groups A, B, C, D (n=15: A primer + adhesive (Clearfil TM SE Bond, B primer + Diode laser + adhesive (940nm wave-length, 21J total energy, 0.7W power, 30s irradiation time C primer + adhesive + Diode laser D primer + Diode laser + adhesive + Diode laser. Then, restoration was completed by Z250 composite. For data analyzing, we used SPSS 16 software. For statistical analysis, we used Non-parametric Kruskal-Wallis & Mann-Whitney tests at 0.05% significance level.  Results: According to non-parametric Kruskal-Wallis test, microleakage scores had not significant difference before and after laser irradiation on gingival margins (p=0.116. But, in occlusal margins the results were significant among the groups (p=0.015. Also according to non-parametric Mann-Whitney tests among the occlusal microleakage scores, group B and D (Diode laser irradiation after primer and Diode laser irradiation after primer and adhesive showed significant results. Conclusion: This study findings showed that in 6th generation adhesives, Diode laser irradiation on self-etch primer before bonding have significant effect on reduction of occlusal marginal microleakage in class V cavities although there was no significant positive effect of Diode laser on gingival margins.

  14. Morphological alterations of radicular dentine pretreated with different irrigating solutions and irradiated with 980-nm diode laser.

    Science.gov (United States)

    Alfredo, Edson; Souza-Gabriel, Aline E; Silva, Silvio Rocha C; Sousa-Neto, Manoel D; Brugnera-Junior, Aldo; Silva-Sousa, Yara T C

    2009-01-01

    The topographical features of intraradicular dentine pretreated with sodium hypochlorite (NaOCl) or ethylenediamine tetraacetic acid (EDTA) followed by diode laser irradiation have not yet been determined. To evaluate the alterations of dentine irradiated with 980-nm diode laser at different parameters after the surface treatment with NaOCl and EDTA. Roots of 60 canines were biomechanically prepared and irrigated with NaOCl or EDTA. Groups were divided according to the laser parameters: 1.5 W/CW; 1.5 W/100 Hz; 3.0 W/CW; 3.0 W/100 Hz and no irradiation (control). The roots were splited longitudinally and analyzed by scanning electron microscopy (SEM) in a quali-quatitative way. The scores were submitted to two-way Kruskal-Wallis and Dunn's tests. The statistical analysis demonstrated that the specimens treated only with NaOCl or EDTA (control groups) were statistically different (P laser-irradiated specimens, regardless of the parameter setting. The specimens treated with NaOCl showed a laser-modified surface with smear layer, fissures, and no visible tubules. Those treated with EDTA and irradiated by laser presented absence of smear layer, tubules partially exposed and melting areas. The tested parameters of 980-nm diode laser promoted similar alterations on dentine morphology, dependent to the type of surface pretreatment. Copyright 2008 Wiley-Liss, Inc.

  15. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Wei; He, Hao, E-mail: haohe@tju.edu.cn; Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue [Ultrafast Laser Laboratory, Key Laboratory of Optoelectronic Information Technology (Ministry of Education), College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin (China)

    2014-02-24

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca{sup 2+} release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  16. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    Science.gov (United States)

    Yan, Wei; He, Hao; Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-02-01

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  17. Mechanical response of agar gel irradiated with Nd:YAG nanosecond laser pulses

    Science.gov (United States)

    Pérez-Gutiérrez, Francisco G.; Evans, Rodger; Camacho-López, Santiago; Aguilar, Guillermo

    2010-02-01

    Nanosecond long laser pulses are used in medical applications where precise tissue ablation with minimal thermal and mechanical collateral damage is required. When a laser pulse is incident on a material, optical energy will be absorbed by a combination of linear and nonlinear absorption according to both: laser light intensity and material properties. In the case of water or gels, the first results in heat generation and thermoelastic expansion; while the second results in an expanding plasma formation that launches a shock wave and a cavitation/boiling bubble. Plasma formation due to nonlinear absorption of nanosecond laser pulses is originated by a combination of multiphoton ionization and thermionic emission of free electrons, which is enhanced when the material has high linear absorption coefficient. In this work, we present measurements of pressure transients originated when 6 ns laser pulses are incident on agar gels with varying linear absorption coefficient, mechanical properties and irradiation geometry using laser radiant exposures above threshold for bubble formation. The underlying hypothesis is that pressure transients are composed of the superposition of both: shock wave originated by hot expanding plasma resulting from nonlinear absorption of optical energy and, thermoelastic expansion originated by heat generation due to linear absorption of optical energy. The objective of this work is to evaluate the relative contribution of each absorption mechanism to mechanical effects in agar gel. Real time pressure transients are recorded with PVDF piezoelectric sensors and time-resilved imaging from 50 μm to 10 mm away from focal point.

  18. Bright x-ray sources from laser irradiation of foams with high concentration of Ti

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, F., E-mail: perez75@llnl.gov; Patterson, J. R.; May, M.; Colvin, J. D.; Biener, M. M.; Wittstock, A.; Kucheyev, S. O.; Charnvanichborikarn, S.; Satcher, J. H.; Gammon, S. A.; Poco, J. F.; Fournier, K. B. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Fujioka, S.; Zhang, Z.; Ishihara, K.; Tanaka, N.; Ikenouchi, T.; Nishimura, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-Oka, Suita, Osaka 565-0871 (Japan)

    2014-02-15

    Low-density foams irradiated by a 20 kJ laser at the Omega laser facility (Laboratory for Laser Energetics, Rochester, NY, USA) are shown to convert more than 5% of the laser energy into 4.6 to 6.0 keV x rays. This record efficiency with foam targets is due to novel fabrication techniques based on atomic-layer-deposition of Ti atoms on an aerogel scaffold. A Ti concentration of 33 at. % was obtained in a foam with a total density of 5 mg/cm{sup 3}. The dynamics of the ionization front through these foams were investigated at the 1 kJ laser of the Gekko XII facility (Institute for Laser Engineering, Osaka, Japan). Hydrodynamic simulations can reproduce the average electron temperature but fail to predict accurately the heat front velocity in the foam. This discrepancy is shown to be unrelated to the possible water adsorbed in the foam but could be attributed to effects of the foam micro-structure.

  19. Efficacy of corneal eye shields in protecting patients' eyes from laser irradiation.

    Science.gov (United States)

    Russell, S W; Dinehart, S M; Davis, I; Flock, S T

    1996-07-01

    The continuing development of new types and applications of lasers has appeared to surpass the development of specific eye protection for these lasers. There are a variety of eye shields on the market, but few are specifically designed for laser protection. Our purpose was to test a variety of eye shields by two parameters, light transmission and temperature rise, and to determine from these measurements the most protective shield for patients. We tested four plastic shields, one metal shield, and two sets of tanning goggles for temperature rise and light transmission when irradiated with a beam from a flashlamp-pumped, pulsed-dye laser. The temperature rise at the surface of the shield opposite the laser impacts was no more than 0.2 degree C in any case. White light was transmitted at significant levels through several of the shields, but yellow light transmittance was noted only through the green eye shield. Our measurements indicate that all except the green shield appeared safe from transmission of the 585-nm radiant energy. However, the optimal laser eye shield, in our opinion, would be a composite of several different shields' characteristics.

  20. Incubation behaviour in triazenepolymer thin films upon near-infrared femtosecond laser pulse irradiation

    International Nuclear Information System (INIS)

    Bonse, J; Wiggins, S M; Solis, J; Sturm, H; Urech, L; Wokaun, A; Lippert, T

    2007-01-01

    The effects of laser radiation induced by a sequence of ultrashort (130 fs), near-infrared (800 nm) Ti:sapphire laser pulses in ∼1 μm thick triazenepolymer films on glass substrates have been investigated by means of in-situ real-time reflectivity measurements featuring a ps-resolution streak camera and a ns-resolution photodiode set-up. The polymer films show incubation effects when each laser pulse in the sequence has a fluence below the single-pulse damage threshold. Non-damage conditions are maintained for several incubation pulses such that the reflectivity of the film shows a rapid decrease of up to 30% within 1 ns but subsequently recovers to its initial value on a ms timescale. Additional pulses lead to a permanent film damage. The critical number of laser pulses needed to generate a permanent damage of the film has been studied as a function of the laser fluence. Once damage is created, further laser pulses cause a partial removal of the film material from the glass substrate. Scanning force microscopy has been used to characterise ex-situ the irradiated surface areas. Based on these complementary measurements possible incubation mechanisms are discussed

  1. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    International Nuclear Information System (INIS)

    Yan, Wei; He, Hao; Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-01-01

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca 2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging

  2. The effect of ArF laser irradiation (193 nm) on the photodegradation and etching properties of alpha-irradiated CR-39 detectors

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Jooybari, B. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute (NSRT), Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Ghergherehchi, M. [College of Information and Technology/ school of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Afarideh, H., E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute (NSRT), Tehran, Islamic Republic of Iran (Iran, Islamic Republic of)

    2015-01-01

    The effects of ArF laser irradiation (λ=193nm) at various fluences (energy dose or energy density) on the etching properties of pre-exposed (laser + alpha) CR-39 detectors were studied. First, UV–Vis and Fourier transform infrared (FTIR) spectra were acquired for non-laser-irradiated and laser-irradiated samples to detect the influence of the ArF laser on the chemical modification of the CR-39. Changes observed in the spectra indicated that the predominant process that occurred upon ArF laser irradiation was a bond-scission process. Thereafter, the mean track and bulk etching parameters were experimentally measured in ArF-laser-irradiated CR-39 detectors exposed to an alpha source ({sup 241}Am, E = 5.49 MeV). Inhomogeneous regions in the laser-irradiated side of the CR-39 demonstrated a variable etching rate on only the front side of the CR-39 detector. New equations are also presented for the average bulk etching rate for these inhomogeneous regions (front side). The mean bulk and track etching rates and the mean track dimensions increased in a fluence range of 0–37.03 mJ/cm{sup 2} because of photodegradation and the scission of chemical bonds, which are the predominant processes in this range. When the fluence was increased from 37.03 to 123.45 mJ/cm{sup 2}, the bulk and track etching rates and the track dimensions slowly decreased because of the formation of cross-linked structures on the CR-39 surface. The behavior of the bulk and track etching rates and the track dimensions appears to be proportional to the dose absorbed on the detector surface. It was observed that as the etching time was increased, the bulk and track etching rates and the track dimensions of the laser-irradiated samples decreased because of the shallow penetration depth of the 193 nm laser and the reduction in the oxygen penetration depth.

  3. He-Ne Laser Irradiation Encourages reparative Processes After cartilage loss in New Zealand rabbits

    International Nuclear Information System (INIS)

    Ali, I.K.

    2008-01-01

    Many therapeutic methods used to encourage reparative processes of cartilage and accelerate their healing such as drugs, magneto-laser and so on.Twenty four adult New Zealand rabbits used in this study.They were divided in to two groups; control and treaded with He-Ne laser.A square skin flap done on the medial aspect of both auricles followed by pealing a square piece of cartilage from the auricle then the flaps sutured.The site of the operation in the rabbits of the treatedgroup were irradiated with He-Ne laser 5mw power for seven days began after the operation directly.3 rabbits from each group used for collection of specimens for histopathological examination at the 1, 2, 4 & 6 weeks post the operation.Significantly well developed cartilage growth, chondroblasts and chondrocytes invade the area of the operation.High increase in the thickness of connective tissue in the same area contain mainly collagen fibers and lesser amount of elastic fibers.He-Ne laser irradiation raised the mitotic activity of the cartilage cells, activated the reproduction processes in addition to the intra and extra regenerative repair

  4. Elemental redistribution behavior in tellurite glass induced by high repetition rate femtosecond laser irradiation

    International Nuclear Information System (INIS)

    Teng, Yu; Zhou, Jiajia; Khisro, Said Nasir; Zhou, Shifeng; Qiu, Jianrong

    2014-01-01

    Highlights: • Abnormal elements redistribution behavior was observed in tellurite glass. • The refractive index and Raman intensity distribution changed significantly. • The relative glass composition remained unchanged while the glass density changed. • First time report on the abnormal element redistribution behavior in glass. • The glass network structure determines the elemental redistribution behavior. - Abstract: The success in the fabrication of micro-structures in glassy materials using femtosecond laser irradiation has proved its potential applications in the construction of three-dimensional micro-optical components or devices. In this paper, we report the elemental redistribution behavior in tellurite glass after the irradiation of high repetition rate femtosecond laser pulses. The relative glass composition remained unchanged while the glass density changed significantly, which is quite different from previously reported results about the high repetition rate femtosecond laser induced elemental redistribution in silicate glasses. The involved mechanism is discussed with the conclusion that the glass network structure plays the key role to determine the elemental redistribution. This observation not only helps to understand the interaction process of femtosecond laser with glassy materials, but also has potential applications in the fabrication of micro-optical devices

  5. The effect of fractional CO2 laser irradiation on remineralization of enamel white spot lesions.

    Science.gov (United States)

    Poosti, Maryam; Ahrari, Farzaneh; Moosavi, Horieh; Najjaran, Hoda

    2014-07-01

    This study investigated the combined effect of fractional CO(2) laser irradiation and fluoride on treatment of enamel caries. Sixty intact premolars were randomly assigned into four groups and then stored in a demineralizing solution to induce white spot lesions. Tooth color was determined at baseline (T1) and after demineralization (T2). Afterwards, the teeth in group 1 remained untreated (control), while group 2 was exposed to an acidulated phosphate fluoride (APF) gel for 4 min. In groups 3 and 4, a fractional CO(2) laser was applied (10 mJ, 200 Hz, 10 s) either before (group 3) or through (group 4) the APF gel. The teeth were then immersed in artificial saliva for 90 days while subjected to daily fluoride mouthrinse and weekly brushing. Color examinations were repeated after topical fluoride application (T3) and 90 days later (T4). Finally, the teeth were sectioned, and microhardness was measured at the enamel surface and at 30 and 60 μ from the surface. In both lased groups, the color change between T1 and T4 stages (∆E(T1-T4)) was significantly lower than those of the other groups (p Laser irradiation followed by fluoride application (group 3) caused a significant increase in surface microhardness compared to APF alone and control groups (p laser before fluoride therapy is suggested for recovering the color and rehardening of demineralized enamel.

  6. Laser-induced nanostructures on a polymer irradiated through a contact mask

    Energy Technology Data Exchange (ETDEWEB)

    Neděla, O. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic); Malý, J.; Štofík, M. [Department of Biology, Faculty of Science, J.E. Purkyně University, 400 96 Usti nad Labem (Czech Republic); Švorčík, V. [Department of Solid State Engineering, Institute of Chemical Technology, 166 28 Prague (Czech Republic)

    2014-12-01

    Highlights: • The unique nanopatterning method of PEN was proposed. • Laser treatment through micrometer slit was utilized. • Dimensions of nanostructures can be precisely controlled. • Laser treatment changes the PEN surface chemistry and morphology (sensor applications). - Abstract: The nanopatterning method applied through micrometer slit for polyethylene naphthalate (PEN) substrate was proposed in this paper. Surface roughness, formation of nanoscale ripple-like structures and the dependence of their dimensions on the value of laser fluence was determined by atomic force and laser confocal microscopy, and compared with values obtained from samples irradiated directly (without a contact mask) under similar conditions. The morphology of the unirradiated surface of the substrate in between the slits is also studied, as well as the morphology of the transitional area between the irradiated and unirradiated surface. Thin layer of gold was deposited on selected samples. Chemical composition of the surface was determined from XPS spectra. The potential application of this research can be found predominantly in the field of selective sensor applications, where the designated area for the consecutive grafting procedures is of great importance.

  7. Formation of highly toxic hydrogen cyanide upon ruby laser irradiation of the tattoo pigment phthalocyanine blue

    Science.gov (United States)

    Schreiver, Ines; Hutzler, Christoph; Laux, Peter; Berlien, Hans-Peter; Luch, Andreas

    2015-08-01

    Since laser treatment of tattoos is the favored method for the removing of no longer wanted permanent skin paintings, analytical, biokinetics and toxicological data on the fragmentation pattern of commonly used pigments are urgently required for health safety reasons. Applying dynamic headspace—gas chromatography with mass spectrometric detection (DHS—GC/MS) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC—ToF-MS), we identified 1,2-benzene dicarbonitrile, benzonitrile, benzene, and the poisonous gas hydrogen cyanide (HCN) as main fragmentation products emerging dose-dependently upon ruby laser irradiation of the popular blue pigment copper phthalocyanine in suspension. Skin cell viability was found to be significantly compromised at cyanide levels of ≥1 mM liberated during ruby laser irradiation of >1.5 mg/ml phthalocyanine blue. Further, for the first time we introduce pyrolysis-GC/MS as method suitable to simulate pigment fragmentation that may occur spontaneously or during laser removal of organic pigments in the living skin of tattooed people. According to the literature such regular tattoos hold up to 9 mg pigment/cm2 skin.

  8. Influence of irradiation conditions on plasma evolution in laser-surface interaction

    Science.gov (United States)

    Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

    1993-09-01

    The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

  9. High-speed photographic methods for compression dynamics investigation of laser irradiated shell target

    International Nuclear Information System (INIS)

    Basov, N.G.; Kologrivov, A.A.; Krokhin, O.N.; Rupasov, A.A.; Shikanov, A.S.

    1979-01-01

    Three methods are described for a high-speed diagnostics of compression dynamics of shell targets being spherically laser-heated on the installation ''Kal'mar''. The first method is based on the direct investigation of the space-time evolution of the critical-density region for Nd-laser emission (N sub(e) asymptotically equals 10 21 I/cm 3 ) by means of the streak photography of plasma image in the second-harmonic light. The second method involves investigation of time evolution of the second-harmonic spectral distribution by means of a spectrograph coupled with a streak camera. The use of a special laser pulse with two time-distributed intensity maxima for the irradiation of shell targets, and the analysis of the obtained X-ray pin-hole pictures constitute the basis of the third method. (author)

  10. Laser microsampling method for determination of retained fission gas in irradiated nuclear fuels

    International Nuclear Information System (INIS)

    Graczyk, D.G.; Bandyopadhyay, G.; Gehl, S.M.; Hughes, J.P.; Goodspeed, H.T.

    1979-10-01

    A small ruby laser adapted to fire through a microscope is used to release fission gases from specific sites on a plane surface of an irradiated fuel specimen. Interaction of the focused laser pulse with the specimen surface results in a conical crater from which sampled material has been vaporized; the crater is surrounded by a heat-affected zone in which intergranular fracture and grain separation allow release of grain-boundary gases. Procedures for measuring the amount of krypton-85 released by laser heating and the volume of material from which the release occurred are presented. The data obtained may be used to obtain local krypton fission-gas concentrations and the intragranular/intergranular distribution

  11. Thermal stress in dentin and enamel under CO2 laser irradiation

    Science.gov (United States)

    Meyer, Dirk H.; Foth, Hans-Jochen

    1996-01-01

    Ablation of dentin and tartar was studied under carbon dioxide-laser irradiation in cw and pulse mode with pulse length down to 150 microseconds. The specimens had been cut by a diamant blade to slices of thicknesses between 0.8 and 2.8 mm. The laser induced temperature rise was measured by an infrared camera monitoring the backside of the samples. The specimens shape and structure at the laser spot was analyzed by electron microscopy. Of special interest was the testing of the SwiftLaseTM to reducing the heat. The experimental results show the necessity of a water cooling in all application modes. The origin of the cracks which had been observed in many of the samples, is currently under investigation.

  12. Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

    Science.gov (United States)

    Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

    2015-03-28

    Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

  13. Investigation of the lasing of dyes under copper vapor laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Danilova, V I; Kopylova, T N; Maier, G V; Masarnovskii, L V; Soldatov, A N; Sukhanov, V B

    1980-10-01

    The lasing characteristics of dyes pumped by copper vapor laser radiation are investigated in order to determine the optimal energetic parameters of the dye-laser system. Expressions are derived for the yields of stimulated emission from dye molecules, and it is shown that the most effective means of improving the lasing characteristics of rhodamine dye solutions is by the modification of intermolecular interactions, in part by the use of multicomponent solutions. Results are then presented of experimental measurements of the emission intensities of combinations of rhodamine dyes irradiated by the 5106-A line of a copper vapor laser. An increase in the lasing efficiency of the acceptor molecule is found for all the dye pairs investigated, with even greater emission intensities observed for multicomponent dye mixtures when the mixtures were pumped transversely. Under longitudinal pumping, improvements in lasing efficiency were obtained only for mixtures of rhodamine 6 Zh with cresil violet.

  14. Diode laser irradiation of rat blood and its effect on hemoglobin and plasma

    International Nuclear Information System (INIS)

    Saad-El-Din, A.A.; El-Ahdaal, M.A.; Omran, M.F.

    2002-01-01

    Blood was exposed to diode laser irradiation of wavelength 830 nm and maximum powe of 31.4 MW, with exposure times 15, 30, 45 and 60 minutes. Hemoglobin IR spectra and X-ray crystallography, plasma Na + , K + , Ca + +. cholesterol concentrations and viscosity were measured. There were changes in hemoglobin amide groups as well as changes in the X-ray in hemoglobin structure. Decreases in both Na concentration and plasma viscosity occurred at 15 and 30 minutes of laser exposure. On increasing time to 45 and 60 minutes, the Na concentration and viscosity were increased. K, Ca and cholesterol concentration were decreased linearly with time. Na / K ratio was increased also with time of exposure. The results have been indicated that the diode laser affect the secondary structure of hemoglobin, membranes structures and plasma

  15. Laser irradiation of penile blood as treatment of sexual dysfunctions

    Science.gov (United States)

    Koultchavenia, Ekaterina V.; Khomyakov, Victor T.

    2001-05-01

    40-60% of the men of average age suffer from the violations of sexual functions. Impotence doesn't make direct threat to life; nevertheless this disease essentially reduces quality of life, and consequently deserves the most steadfast attention. There are many methods of treatment of erectile dysfunction. However they are connected with a reception of medicines, which is expensive and has a number of contraindications, or with invasive procedures, or with surgical intervention, that also not always is desirable. We have developed the original device permitting to cause passive erection by creation of a local decompression. The second stage is the effect by an infrared laser radiation (denseness of a potency 4.2 mWt/sm2, continuous radiation with length of a wave 0.89 microns, exposition 5 minutes) on erection glans penis. We observed 24 patients with the complaints on insufficient erection (18), premature ejaculation (6); 2 patients in addition presented the complaint on small sizes of the penis. Age of the patients was 24-46 years, on the average 34.3 years. All have received treatment from 15 sessions in day.

  16. Effect of irradiation angle on the efficiency of formation of multiply charged ions in a laser-produced plasma

    International Nuclear Information System (INIS)

    Bedilov, M R; Beisembaeva, Kh B; Tsoi, T G; Satybaldiev, T B; Sabitov, M S

    2000-01-01

    Mass spectrometry is used to investigate the emission behaviour and the characteristics of multiply charged ions in a plasma produced at small angles of incidence of laser radiation (α∼20 0 ) and also at grazing incidence (α∼85 0 ). It is found that upon grazing incidence of the laser radiation onto a target, the efficiency of production of multiply charged ions is reduced compared to that for α∼20 0 . However, this geometry of laser irradiation of solids can be used for the elemental analysis of surface layers of a sample. (interaction of laser radiation with matter. laser plasma)

  17. The effect of 648 nm diode laser irradiation on second messengers in senescent human keratinocytes

    Science.gov (United States)

    Hawkins Evans, D.; Abrahamse, H.

    2009-02-01

    Background/purpose: Stress induced premature senescence (SIPS) is defined as the long-term effect of subcytotoxic stress on proliferative cell types. Cells in SIPS display differences at the level of protein expression which affect energy metabolism, defense systems, redox potential, cell morphology and transduction pathways. This study aimed to determine the effect of laser irradiation on second messengers in senescent cells and to establish if that effect can be directly linked to changes in cellular function such as cell viability or proliferation. Materials and Methods: Human keratinocyte cell cultures were modified to induce premature senescence using repeated sub-lethal stresses of 200 uM H2O2 or 5% OH every day for four days with two days recovery. SIPS was confirmed by senescence-associated β-galactosidase staining. Control conditions included normal, repeated stress of 500 uM H2O2 to induce apoptosis and 200 uM PBN as an anti-oxidant or free radical scavenger. Cells were irradiated with 1.5 J/cm2 on day 1 and 4 using a 648 nm diode laser (3.3 mW/cm2) and cellular responses were measured 1 h post irradiation. The affect on second messengers was assessed by measuring cAMP, cGMP, nitric oxide and intracellular calcium (Ca2+) while functional changes were assessed using cell morphology, ATP cell viability, LDH membrane integrity and WST-1 cell proliferation. Results: Results indicate an increase in NO and a decrease in cGMP and Ca2+ in 200 uM H2O2 irradiated cells while PBN irradiated cells showed a decrease in cAMP and an increase in ATP viability and cell proliferation. Conclusion: Laser irradiation influences cell signaling which ultimately changes the biological function of senescent cells. If laser therapy can stimulate the biological function of senescent cells it may be beneficial to conditions such as immune senescence, skin ageing, muscle atrophy, premature ageing of arteries in patients with advanced heart disease, neurodegenerative disorders and

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

    Science.gov (United States)

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

    2014-11-01

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

  19. A low power Multi-Channel Analyzer

    International Nuclear Information System (INIS)

    Anderson, G.A.; Brackenbush, L.W.

    1993-06-01

    The instrumentation used in nuclear spectroscopy is generally large, is not portable, and requires a lot of power. Key components of these counting systems are the computer and the Multi-Channel Analyzer (MCA). To assist in performing measurements requiring portable systems, a small, very low power MCA has been developed at Pacific Northwest Laboratory (PNL). This MCA is interfaced with a Hewlett Packard palm top computer for portable applications. The MCA can also be connected to an IBM/PC for data storage and analysis. In addition, a real-time time display mode allows the user to view the spectra as they are collected

  20. Cold neutron radiography using low power accelerator

    International Nuclear Information System (INIS)

    Kiyanagi, Yoshiaki; Iwasa, Hirokatu

    1993-01-01

    A cold neutron source which can be adopted at a low power accelerator was studied. Time-of-flight radiography using the cold neutron source was performed. It is suggested that time-of-flight cold neutron radiography has possibility to distinguish the materials more clearly than the traditional film method since large contrast differences can be obtained by using digital data of the neutron intensity at different energies from thermal to cold region. Material will be identified at the same time by this method. (author)

  1. Effect of Suyuping combined with semiconductor laser irradiation on wound healing after anal fistula surgery

    Institute of Scientific and Technical Information of China (English)

    Min Zhao; Chang-Ye Sang; Zhen-Jun Wang; Yan-Chun Xu

    2016-01-01

    Objective:To explore the effect of Suyuping combined with semiconductor laser irradiation on the wound healing after anal fistula surgery.Methods:A total of 180 patients with anal fistula who were admitted in our hospital from October, 2013 to May, 2015 for surgery were included in the study and randomized into the treatment group and the control group with 90 cases in each group. The patients in the control group were given the conventional surgical debridement dressing, a time a day. On this basis, the patients in the treatment group were given Suyuping smearing on the wound sinus tract combined with semiconductor laser irradiation, a time a day for 10 min, continuous irradiation until wound healing. The postoperative wound swelling fading, wound surface secretion amount, and the clinical efficacy in the two groups were recorded.Results:The wound surface swelling degree and wound pain degree at each timing point after operation in the treatment group were significantly lower than those in the control group (P<0.05). The wound surface area at each timing point after operation in the treatment group was significantly lower than that in the control group (P<0.05). The wound surface secretion amount 6, 9, and 12 days after operation in the treatment group was significantly lower than that in the control group (P<0.05). The total effective rate in the treatment group was significantly higher than that in the control group (P<0.05). The average healing time in the treatment group was significantly faster than that in the control group (P<0.05). Conclusions: Suyuping combined with semiconductor laser irradiation in the treatment of patients after anal fistula can effectively improve the local blood and lymphatic circulation of wound surface, promote the growth of granulation tissues, and contribute the wound healing.

  2. Effect of Suyuping combined with semiconductor laser irradiation on wound healing after anal fistula surgery

    Directory of Open Access Journals (Sweden)

    Min Zhao

    2016-06-01

    Full Text Available Objective: To explore the effect of Suyuping combined with semiconductor laser irradiation on the wound healing after anal fistula surgery. Methods: A total of 180 patients with anal fistula who were admitted in our hospital from October, 2013 to May, 2015 for surgery were included in the study and randomized into the treatment group and the control group with 90 cases in each group. The patients in the control group were given the conventional surgical debridement dressing, a time a day. On this basis, the patients in the treatment group were given Suyuping smearing on the wound sinus tract combined with semiconductor laser irradiation, a time a day for 10 min, continuous irradiation until wound healing. The postoperative wound swelling fading, wound surface secretion amount, and the clinical efficacy in the two groups were recorded. Results: The wound surface swelling degree and wound pain degree at each timing point after operation in the treatment group were significantly lower than those in the control group (P<0.05. The wound surface area at each timing point after operation in the treatment group was significantly lower than that in the control group (P<0.05. The wound surface secretion amount 6, 9, and 12 days after operation in the treatment group was significantly lower than that in the control group (P<0.05. The total effective rate in the treatment group was significantly higher than that in the control group (P<0.05. The average healing time in the treatment group was significantly faster than that in the control group (P<0.05. Conclusions: Suyuping combined with semiconductor laser irradiation in the treatment of patients after anal fistula can effectively improve the local blood and lymphatic circulation of wound surface, promote the growth of granulation tissues, and contribute the wound healing.

  3. Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins

    International Nuclear Information System (INIS)

    Ecault, Romain; Touchard, Fabienne; Boustie, Michel; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Voillaume, Hubert

    2015-01-01

    In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy setup has been developed using the photoelasticimetry principle to enhance the shear wave observation. Shear waves have been observed in epoxy resin after laser irradiation. Their propagation has been quantified in comparison with the main shock propagation. A discussion, hinging on numerical results, is finally given to improve understanding of the phenomenon. (paper)

  4. Effect of Irradiation Parameters on Morphology of Polishing DF2 (AISI-O1 Surface by Nd:YAG Laser

    Directory of Open Access Journals (Sweden)

    Wei Guo

    2007-01-01

    Full Text Available Pulse Nd:YAG laser was used to polish DF2 cold work steel. Influence of irradiation parameters on the 3D surface morphology was studied by 3D profilometer, scanning electron microscopy (SEM, and atomic force microscope (AFM. Results among the tests showed when DF2 specimens were irradiated with parameters of (i laser input energy P=1 J, (ii pulse feedrate=300 mm/min, (iii pulse duration (PD =3 milliseconds, and (iv pulse frequency f=20∼25 Hz, laser polishing of DF2 cold work steel seemed to be successful.

  5. In situ investigation of formation of self-assembled nanodomain structure in lithium niobate after pulse laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shur, V. Ya.; Kuznetsov, D. K.; Mingaliev, E. A.; Yakunina, E. M.; Lobov, A. I.; Ievlev, A. V. [Ferroelectric Laboratory, Institute of Physics and Applied Mathematics, Ural State University, Lenin Ave. 51, Ekaterinburg 620083 (Russian Federation)

    2011-08-22

    The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation was studied by in situ optical observation. The average periods of the structures are much less than the sizes of the laser spots. The polarization reversal occurs through covering of the whole irradiated area by the nets of the spatially separated nanodomain chains and microdomain rays--''hatching effect.'' The main stages of the anisotropic nanodomain kinetics: nucleation, growth, and branching, have been singled out. The observed abnormal domain kinetics was attributed to the action of the pyroelectric field arising during cooling after laser heating.

  6. Investigation on femto-second laser irradiation assisted shock peening of medium carbon (0.4% C) steel

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Jyotsna Dutta, E-mail: jyotsna@metal.iitkgp.ernet.in [Dept. of Metal. & Maters. Eng., I. I. T., Kharagpur, WB 721302 (India); Gurevich, Evgeny L., E-mail: gurevich@lat.rub.de [Ruhr-Universität Bochum, Ls. Laseranwendungstechnik, Universitätsstr. 150, 44801 Bochum (Germany); Kumari, Renu, E-mail: renumetalbit@gmail.com [Dept. of Metal. & Maters. Eng., I. I. T., Kharagpur, WB 721302 (India); Ostendorf, Andreas, E-mail: andreas.ostendorf@ruhr-uni-bochum.de [Ruhr-Universität Bochum, Ls. Laseranwendungstechnik, Universitätsstr. 150, 44801 Bochum (Germany)

    2016-02-28

    Graphical abstract: - Highlights: • Peening effect of 0.4% C steel by femtosecond laser irradiation. • Microstructural investigation of the irradiated surface. • Residual stress decreased from 152 MPa to 140 MPa to −330 MPa by laser processing. • Decreased wear depth to a maximum of four times as compared to as-received substrate. • Mechanism of wear for both as-received and laser processed surface were established. - Abstract: In the present study, the effect of femtosecond laser irradiation on the peening behavior of 0.4% C steel has been evaluated. Laser irradiation has been conducted with a 100 μJ and 300 fs laser with multiple pulses under varied energy. Followed by laser irradiation, a detailed characterization of the processed zone was undertaken by scanning electron microscopy, and X-ray diffraction technique. Finally, the residual stress distribution, microhardness and wear resistance properties of the processed zone were also evaluated. Laser processing leads to shock peening associated with plasma formation and its expansion, formation of martensite and ferrito–pearlitic phase in the microstructure. Due to laser processing, there is introduction of residual stress on the surface which varies from high tensile (140 MPa) to compressive (−335 MPa) as compared to 152 MPa of the substrate. There is a significant increase in microhardness to 350–500 VHN as compared to 250 VHN of substrate. The fretting wear behavior against hardened steel ball shows a significant reduction in wear depth due to laser processing. Finally, a conclusion of the mechanism of wear has been established.

  7. Low-Power Architecture for an Optical Life Gas Analyzer

    Science.gov (United States)

    Pilgrim, Jeffrey; Vakhtin, Andrei

    2012-01-01

    Analog and digital electronic control architecture has been combined with an operating methodology for an optical trace gas sensor platform that allows very low power consumption while providing four independent gas measurements in essentially real time, as well as a user interface and digital data storage and output. The implemented design eliminates the cross-talk between the measurement channels while maximizing the sensitivity, selectivity, and dynamic range for each measured gas. The combination provides for battery operation on a simple camcorder battery for as long as eight hours. The custom, compact, rugged, self-contained design specifically targets applications of optical major constituent and trace gas detection for multiple gases using multiple lasers and photodetectors in an integrated package.

  8. Effect of low-level laser irradiation on osteoblast-like cells cultured on porous hydroxyapatite scaffolds

    Directory of Open Access Journals (Sweden)

    Serena Incerti Parenti

    2013-09-01

    Full Text Available OBJECTIVE: To determine the effect of laser irradiation at a low dose on human osteoblastlike cells. Materials and methods: 32 porous hydroxyapatite scaffolds currently used for bone tissue engineering were seeded with MG63 cells and irradiated or not with a GaAlAs diode laser (wavelength 915 nm, dose 2 J/cm² using different power density and exposure duration. RESULTS: After 72-h incubation, cells showed well spread morphology and good adhesion on both laser-treated and untreated scaffolds. Laser irradiation did not interfere in cell viability and proliferation as compared with the non-irradiated controls. CONCLUSION: This study suggests that there is no effect of 915 nm laser irradiation at a dose of 2 J/cm² on the proliferation rate of MG63 cells. Future investigations are needed to compare different dose and wavelength regimens in order to determine the optimal set of laser parameters for maximum cell yield and safe clinical application.

  9. Dependence of adhesion strength between GaN LEDs and sapphire substrate on power density of UV laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Park, Junsu [Department of Nano-Manufacturing Technology, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of); Sin, Young-Gwan [Department of Nano-Mechatronics, Korea University of Science and Technology (UST), 217 Gajeong-Ro, Yuseong-Gu, Daejeon 34113 (Korea, Republic of); Kim, Jae-Hyun [Department of Nano-Mechanics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of); Kim, Jaegu, E-mail: gugu99@kimm.re.kr [Department of Nano-Manufacturing Technology, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of)

    2016-10-30

    Highlights: • Fundamental relationship between laser irradiation and adhesion strength, between gallium-nitride light emitted diode and sapphire substrate, is proposed during selective laser lift-off. • Two competing mechanisms affect adhesion at the irradiated interface between the GaN LED and sapphire substrate. • Ga precipitation caused by thermal decomposition and roughened interface caused by thermal damage lead to the considerable difference of adhesion strength at the interface. - Abstract: Selective laser lift-off (SLLO) is an innovative technology used to manufacture and repair micro-light-emitting diode (LED) displays. In SLLO, laser is irradiated to selectively separate micro-LED devices from a transparent sapphire substrate. The light source used is an ultraviolet (UV) laser with a wavelength of 266 nm, pulse duration of 20 ns, and repetition rate of 30 kHz. Controlled adhesion between a LED and the substrate is key for a SLLO process with high yield and reliability. This study examined the fundamental relationship between adhesion and laser irradiation. Two competing mechanisms affect adhesion at the irradiated interface between the GaN LED and sapphire substrate: Ga precipitation caused by the thermal decomposition of GaN and roughened interface caused by thermal damage on the sapphire. The competition between these two mechanisms leads to a non-trivial SLLO condition that needs optimization. This study helps understand the SLLO process, and accelerate the development of a process for manufacturing micro-LED displays via SLLO for future applications.

  10. Laser Phototherapy (660 nm Can Be Beneficial for Reducing Gingival Inflammation in Prosthodontics

    Directory of Open Access Journals (Sweden)

    Sávio José Cardoso Bezerra

    2015-01-01

    Full Text Available Among the new technologies developed, low power lasers have enabled new approaches to provide conservative treatment. Low power lasers act at cellular level, resulting in reduced pain, modulating inflammation, and improved tissue healing. Clinical application of the low power laser requires specific knowledge concerning laser interaction with biological tissue so that the correct irradiation protocol can be established. The present case report describes the clinical steps involved in an indirect composite resin restoration performed in a 31-year-old patient, in whom low power laser was used for soft tissue biomodulation. Laser therapy was applied with a semiconductor laser 660 nm, spot size of 0.028 cm2, energy density of 35.7 J/cm2, mean power of 100 mW, and energy per point as 1 J, in contact mode, on a total of 2 points (mesial and distal, totaling 2 J of energy. The therapy with low power laser can contribute positively to the success of an indirect restorative treatment.

  11. Growth behavior of laser-induced damage on fused silica optics under UV, ns laser irradiation.

    Science.gov (United States)

    Negres, Raluca A; Norton, Mary A; Cross, David A; Carr, Christopher W

    2010-09-13

    The growth behavior of laser-induced damage sites is affected by a large number of laser parameters as well as site morphology. Here we investigate the effects of pulse duration on the growth rate of damage sites located on the exit surface of fused silica optics. Results demonstrate a significant dependence of the growth parameters on laser pulse duration at 351 nm from 1 ns to 15 ns, including the observation of a dominant exponential versus linear, multiple-shot growth behavior for long and short pulses, respectively. These salient behaviors are tied to the damage morphology and suggest a shift in the fundamental growth mechanisms for pulses in the 1-5 ns range.

  12. assessment Of the effect Of low Level Laser Therapy on Parotid glands of gamma Irradiated Rats

    International Nuclear Information System (INIS)

    Ahmed, S.F.

    2013-01-01

    Gamma radiation-induced salivary gland dysfunction has a major deleterious effect on oral health. Aim: This study was carried out to evaluate the possible effect of low level laser therapy (LLLT) on radiation induced oxidative stress in rats’ salivary glands. Material and Methods: Sixty four male Albino rats were divided into two groups. One group where the left parotid gland was exposed to 3 sessions of LLL, then rats were subjected to 3 sessions of whole body gamma-radiation. In the other group, rats were subjected to 3 sessions of gamma-radiation; each was followed by a session of LLL to the left parotid gland. The right gland of both groups was used as irradiated control. Parotid glands were collected 1 day, 3 days, 1 week and 2 weeks after the end of treatment and were subjected to histological examination and immunohistochemical analysis. Results: The parotid gland of both laser groups showed less intra cytoplasmic vacuolisation, slight alteration of acinar architecture and almost even size nuclei as compared to the irradiated gland. LLL either before or parallel to gamma-irradiation was effective in increasing cell proliferation on the third and seventh day, respectively as compared to the gamma irradiated group (P<0.05). Statistically, results revealed significant decrease in optical density of caspase 3 activity in the lased groups on the first week as compared to the control. Conclusion: LLLT attenuates the harmful effect of gamma irradiation on the parotid glands of the rats. Also, it improves gland regeneration through modulation of cell proliferation and apoptosis inflammation

  13. Low-level laser irradiation protects the chick embryo chorioallantoic membrane from UV cytotoxicity

    Directory of Open Access Journals (Sweden)

    Hammami Amira

    2018-01-01

    Full Text Available Low-level laser therapy or photobiomodulation is the medical use of a very low intensity light in the red to near infrared (wavelengths in the range of 630-940 nm. The present work was conducted to explore the effects of both UV and low-level laser irradiation (LLLI on microcirculation using the in vivo model of the chick embryo chorioallantoic membrane (CAM. The effects were assessed by measuring lipid peroxidation and antioxidant enzyme activity. Cell cytotoxicity, survival and intracellular reactive oxygen species (ROS of the CAM were also evaluated. We found that UV irradiation induced alterations of the vessels, leading to bleeding and extravasation. This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema. UVA irradiation increased cell cytotoxicity as assessed by lactate dehydrogenase (LDH release (56.23% of control and reduced cell viability as assessed by decreased fluorescein diacetate (FDA fluorescence (56.23% of control. Pretreatment with LLLI prior to UV exposure protected the CAM tissue from UV-mediated cell death. This protective effect was supported by the observation of significantly inhibited lipid peroxidation (from 0.3±0.004 for UV, to 0.177±0.012 after LLLI pretreatment, ROS and O2 -production, as indicated by respective dihydrorhodamine (DHR and dihydroethidium (DHE intensities (from 132.78% of control for UVA, to 95.90% of control for L-UV (DHR, and from 127.34% of control for UVA, to 82.03% of control for L-UV (DHE, and by preventing the increase in oxidative activities. LLLI efficiently protected CAM cells from UV-induced oxidative stress and appeared as a safe protective pretreatment against UV irradiation.

  14. Laser biostimulation of articular cartilage: in vitro evaluation

    Science.gov (United States)

    Jia, Yali; Guo, Zhouyi; Yang, Xiaohong; Zeng, Chang-Chun

    2004-07-01

    In the orthopaedic field, the repair of ariticular cartilage is still a difficult problem, because of the physiological characters of cartilaginous tissues and chondrocytes. To find an effective method of stimulating their regeneration, this in vitro study focuses on the biostimulation of rabbit articular chondrocytes by low-power He-Ne laser. The articular chondrocytes isolated from the cartilage of the medial condyle of the femur of the rabbit were incubated in HamF12 medium. The second passage culture were spread on 24 petri dishes and were irradiated with laser at power density of 2 - 12 mW/cm2 for 6.5 minutes, corresponding to the energy density of 1-6 J/cm2. Laser treatment was performed three times at a 24-hour interval. After lasering, incubation was continued for 24 hours. Non-irradiated cells were kept under the same conditions as the irradiated ones. The cell proliferation activity was evaluated with a XTT colorimetric method. Irradiation of 4 - 6 J/cm2 revealed a considerably higher cell proliferation activity comparing to control cultures. Thereinto, the energy density of 4 and 5 J/cm2 remarkably increased cell growth (P<0.01). The present study showed that a particular laser irradiation stimulates articular chondrocytes proliferation. These findings might be clinically relevant, indicating that low-power laser irradiation treatment is likely to achieve the repair of articular cartilage in clinic.

  15. Effect of laser irradiation on Ag4In12Sb56Te28

    Science.gov (United States)

    Chinnusamy, Rangasami

    2018-04-01

    Ag4In12Sb56Te28 has been synthesized by melt-quench method. Phase homogeneity, crystal structure and effect of laser irradiation have been investigated using X-ray diffraction (XRD) and Raman spectroscopy. Rietveld refinement of crystal structure revealed that Ag4In12Sb56Te28 is a multiphase system with AgIn3Te5, Sb8Te3 and Sb phases. Combined optical microscopy and Raman spectroscopy have been used to understand the distribution of different phases on the surface of the samples, which substantiated the results of Rietveld analysis. Interaction of 20 mW laser beam with samples has been investigated using Raman measurements. The results have shown that regions with large phase fraction of AgIn3Te5 become amorphous during laser-sample interaction, but the starting phase remains nearly same after the interaction. Regions with AgIn3Te5 and nearly equal or larger amount of Sb8Te3 have shown significant growth of α-Sb2O3 during and after laser-sample interaction. Regions rich in Sb have shown formation of AgIn3Te5 and growth of α-Sb2O3 during and after interaction. These observations have been explained based on the maximum temperature rise at different regions during laser-sample interaction.

  16. Effect of laser irradiation for healing of the skin-muscle wounds of animals

    Science.gov (United States)

    Lapina, Victoria A.; Veremei, Eduard I.; Pancovets, Evgeniy A.

    2000-05-01

    The purpose of our investigation was to study the medical effect of low-intensity laser influence on healing of skin- muscle wounds of agricultural animals. We used the laser radiation of low intensity for cub's therapy: to sucking-pigs after herniotomy and castration, to cattle cubs after skin- muscle wounds. The animals were kept under clinical observation up to their recovery. The recuperation dynamic was observed by changing of blood quotients, leukograms, sizes of inflammatory edema, general behavior of animals. The positive dynamic of blood quotients of the experimental animal groups was really higher than that in control. The analysis of wound healing after laser influence shows that wound surface of experimental group was to a great extent smaller in comparison with control group of animals. So, these facts testify about anti-inflammatory action of laser radiation, which hastens regenerative and rehabilitative processes. Analysis of the obtained experimental data has revealed the positive influence of laser irradiation on the dynamics of wound adhesion of agricultural animals.

  17. Basic study of charring detection at the laser catheter-tip using back scattering light measurement during therapeutic laser irradiation in blood.

    Science.gov (United States)

    Takahashi, Mei; Ito, Arisa; Kajihara, Takuro; Matsuo, Hiroki; Arai, Tsunenori

    2010-01-01

    The purpose of this study is to investigate transient process of the charring at the laser catheter-tip in blood during therapeutic laser irradiation by the back scattering light measurement to detect precursor state of the charring. We took account of using photodynamic therapy for arrhythmia in blood through the laser catheter. We observed the influence of the red laser irradiation (λ=663 nm) upon the shape of red blood cells (RBCs). The RBCs aggregation, round formation, and hemolysis were took place sequentially before charring. With a model blood sandwiched between glass plates simulated as a catheter-tip boundary, we measured diffuse-reflected-light power and transmitted-light power simultaneously and continuously by a microscopic optics during the laser irradiation. We found that measured light power changes were originated with RBCs shape change induced by temperature rise due to the laser irradiation. A gentle peak following a slow descending was observed in the diffuse-reflected-light power history. This history might indicate the precursor state of the charring, in which the hemolysis might be considered to advance rapidly. We think that the measurement of diffuse-reflected-light power history might be able to detect precursor state of charring at the catheter-tip in blood.

  18. Energy of a shock wave generated in different metals under irradiation by a high-power laser pulse

    International Nuclear Information System (INIS)

    Gus'kov, S. Yu.; Kasperczuk, A.; Pisarczyk, T.; Borodziuk, S.; Ullschmied, J.; Krousky, E.; Masek, K.; Pfeifer, M.; Skala, J.; Pisarczyk, P.

    2007-01-01

    The energies of a shock wave generated in different metals under irradiation by a high-power laser beam were determined experimentally. The experiments were performed with the use of targets prepared from a number of metals, such as aluminum, copper, silver and lead (which belong to different periods of the periodic table) under irradiation by pulses of the first and third harmonics of the PALS iodine laser at a radiation intensity of approximately 10 14 W/cm 2 . It was found that, for heavy metals, like for light solid materials, the fraction of laser radiation energy converted into the energy of a shock wave under irradiation by a laser pulse of the third harmonic considerably (by a factor of 2-3) exceeds the fraction of laser radiation energy converted under irradiation by a laser pulse of the first harmonic. The influence of radiation processes on the efficiency of conversion of the laser energy into the energy of the shock wave was analyzed

  19. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    International Nuclear Information System (INIS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2002-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  20. Chemical and physical analysis on hard tissues after irradiation with short pulse Nd:YAG laser

    International Nuclear Information System (INIS)

    Pereira, Andrea Antunes

    2003-01-01

    This work reports on a study that was designed to investigate chemical, physical and morphological alterations in the dental enamel surface. The influence of application of laser in enamel surface by microscopic technical, X-ray fluorescence for chemical analysis, physical property as well as hardness and thermal analysis with Nd:YAG laser is also pointed out. A prototype of Nd:YAG (Q-switched) laser developed at the Center of Lasers and Applications - Institute of Energetic and Nuclear Research, aiming applications in the Medical Sciences that typical wavelength of 1.064 nm was used. The modifications in human dental enamel chemical composition for major and trace elements are here outlined. The accuracy of procedures was performed by analysis of natural hydroxyapatite as standard reference material. The identification and quantification of the chemical elements presented in the dental tissue samples were performed trough EDS, XRF and INAA. We determined the rate Calcium/Phosphorus (Ca/P) for different techniques. We performed an analysis in different regions of the surface and for different areas allowing a description of the chemical change in the total area of the specimen and the assessment of the compositional homogeneity of the each specimen. A comparison between XRF and INAA is presented. Based on morphological analysis of the irradiated surfaces with short pulse Nd:YAG laser we determined the area surrounded by the irradiation for the parameters for this thesis, and this technique allowed us to visualize the regions of fusion and re-solidification. The energy densities ranged from 10 J/cm 2 to 40 J/cm 2 , with pulse width of 6, 10 e 200 ns, and repetition rates of 5 and 7 Hz. In this thesis, FTIR-spectroscopy is used to analyze powder of mineralized tissue as well as enamel, dentine, root and cementum for human and bovine teeth after irradiation with short-pulse Nd:YAG laser. Characteristic spectra were obtained for the proteins components and mineral

  1. Effects of high-frequency near-infrared diode laser irradiation on the proliferation and migration of mouse calvarial osteoblasts.

    Science.gov (United States)

    Kunimatsu, Ryo; Gunji, Hidemi; Tsuka, Yuji; Yoshimi, Yuki; Awada, Tetsuya; Sumi, Keisuke; Nakajima, Kengo; Kimura, Aya; Hiraki, Tomoka; Abe, Takaharu; Naoto, Hirose; Yanoshita, Makoto; Tanimoto, Kotaro

    2018-01-04

    Laser irradiation activates a range of cellular processes and can promote tissue repair. Here, we examined the effects of high-frequency near-infrared (NIR) diode laser irradiation on the proliferation and migration of mouse calvarial osteoblastic cells (MC3T3-E1). MC3T3-E1 cells were cultured and exposed to high-frequency (30 kHz) 910-nm diode laser irradiation at a dose of 0, 1.42, 2.85, 5.7, or 17.1 J/cm 2 . Cell proliferation was evaluated with BrdU and ATP concentration assays. Cell migration was analyzed by quantitative assessment of wound healing using the Incucyt ® ZOOM system. In addition, phosphorylation of mitogen-activated protein kinase (MAPK) family members including p38 mitogen-activated protein kinase (p38), stress-activated protein kinase/Jun-amino-terminal kinase (SAPK/JNK), and extracellular signal-regulated protein kinase (ERK)1/2) after laser irradiation was examined with western blotting. Compared to the control, cell proliferation was significantly increased by laser irradiation at a dose of 2.85, 5.7, or 17.1 J/cm 2 . Laser irradiation at a dose of 2.85 J/cm 2 induced MC3T3-E1 cells to migrate more rapidly than non-irradiated control cells. Irradiation with the high-frequency 910-nm diode laser at a dose of 2.85 J/cm 2 induced phosphorylation of MAPK/ERK1/2 15 and 30 min later. However, phosphorylation of p38 MAPK and SAPK/JNK was not changed by NIR diode laser irradiation at a dose of 2.85 J/cm 2 . Irradiation with a high-frequency NIR diode laser increased cell division and migration of MT3T3-E1 cells, possibly via MAPK/ERK signaling. These observations may be important for enhancing proliferation and migration of osteoblasts to improve regeneration of bone tissues.

  2. Enhancing hair follicle regeneration by nonablative fractional laser: Assessment of irradiation parameters and tissue response.

    Science.gov (United States)

    Wu, Yueh-Feng; Wang, Shiou-Han; Wu, Pei-Shan; Fan, Sabrina Mai-Yi; Chiu, Hsien-Yi; Tsai, Tsung-Hua; Lin, Sung-Jan

    2015-04-01

    Identification of methods to enhance anagen entry can be helpful for alopecia. Recently, nonablative laser has been proposed as a potential treatment for alopecia. However, how the laser parameters affect stem cell activity, hair cycles and the associated side effects have not been well characterized. Here we examine the effects of irradiation parameters of 1,550-nm fractional laser on hair cycles. The dorsal skin of eight-week-old female C57BL/6 mice with hair follicles in synchronized telogen was shaved and irradiated with a 1,550-nm fractional erbium-glass laser (Fraxel RE:STORE (SR1500) Laser System, Solta Medical, U.S.A.) with varied beam energies (5-35 mJ) and beam densities (500-3500 microthermal zones/cm(2) ). The cutaneous changes were evaluated both grossly and histologically. Hair follicle stem cell activity was detected by BrdU incorporation and changes in gene expression were quantified by real-time PCR. Direct thermal injury to hair follicles could be observed early after irradiation, especially at higher beam energy. Anagen induction in the irradiated skin showed an all-or-non change. Anagen induction and ulcer formation were affected by the combination of beam energy and density. The lowest beam energy of 5 mJ failed to promote anagen entry at all beam densities tested. As beam energy increased from 10 mJ to 35 mJ, we found a decreasing trend of beam density that could induce anagen entry within 7-9 days with activation of hair follicle stem cells. Beam density above the pro-regeneration density could lead to ulcers and scarring followed by anagen entry in adjacent skin. Analysis of inflammatory cytokines, including TNF-α, IL-1β, and IL-6, revealed that transient moderate inflammation was associated with anagen induction and intense prolonged inflammation preceded ulcer formation. To avoid side effects of hair follicle injury and scarring, appropriate combination of beam energy and density is required. Parameters outside the therapeutic

  3. Laser irradiation of centrosomes in newt eosinophils: evidence of centriole role in motility

    Energy Technology Data Exchange (ETDEWEB)

    Koonce, M.P.; Cloney, R.A.; Berns, M.W.

    1984-06-01

    Newt eosinophils are motile granulated leukocytes that uniquely display a highly visible centrosomal area. Electron microscope and tubulin antibody fluorescence confirms the presence of centrioles, pericentriolar material, and radiating microtubules within this visible area. Actin antibodies intensely stain the advancing cell edges and tail but only weakly stain pseudopods being withdrawn into the cell. Randomly activated eosinophils follow a roughly consistent direction with an average rate of 22.5 ..mu..m/min. The position of the centrosome is always located between the trailing cell nucleus and advancing cell edge. If the cell extends more than one pseudopod, the one closest to or containing the centrosome is always the one in which motility continues. Laser irradiation of the visible centrosomal area resulted in rapid cell rounding. After several minutes following irradiation, most cells flattened and movement continued. However, postirradiation motility was uncoordinated and directionless, and the rate decreased to an average of 14.5 ..mu..m/min. Electron microscopy and tubulin immunofluorescence indicated that an initial disorganization of microtubules resulted from the laser microirradiations. After several minutes, organized microtubules reappeared, but the centrioles appeared increasingly damaged. The irregularities in motility due to irradiation are probably related to the damaged centrioles. The results presented in this paper suggest that the centrosome is an important structure in controlling the rate and direction of newt eosinophil motility.

  4. 3D Monte Carlo model of optical transport in laser-irradiated cutaneous vascular malformations

    Science.gov (United States)

    Majaron, Boris; Milanič, Matija; Jia, Wangcun; Nelson, J. S.

    2010-11-01

    We have developed a three-dimensional Monte Carlo (MC) model of optical transport in skin and applied it to analysis of port wine stain treatment with sequential laser irradiation and intermittent cryogen spray cooling. Our MC model extends the approaches of the popular multi-layer model by Wang et al.1 to three dimensions, thus allowing treatment of skin inclusions with more complex geometries and arbitrary irradiation patterns. To overcome the obvious drawbacks of either "escape" or "mirror" boundary conditions at the lateral boundaries of the finely discretized volume of interest (VOI), photons exiting the VOI are propagated in laterally infinite tissue layers with appropriate optical properties, until they loose all their energy, escape into the air, or return to the VOI, but the energy deposition outside of the VOI is not computed and recorded. After discussing the selection of tissue parameters, we apply the model to analysis of blood photocoagulation and collateral thermal damage in treatment of port wine stain (PWS) lesions with sequential laser irradiation and intermittent cryogen spray cooling.

  5. Thermal imaging of levitated fresh and salt water drops during laser irradiation

    Science.gov (United States)

    Brownell, Cody; Biggs, Harrison

    2017-11-01

    Simulation of high energy laser propagation and scattering in the maritime environment is problematic, due to the high likelihood of turbulence, fog, and rain or sea spray within the beam path. Considering large water drops (diameters of approximately 1-mm), such as those found in a light rain, an incident high energy laser will lead to rapid evaporation of the water drop as it traverses the beam path. In this work we present surface temperature measurements of a water drop obtained using a FLIR IR camera. The drop is acoustically levitated, and subject to a continuous wave laser with a wavelength of 1070-nm and a mean irradiance of approximately 800 W/cm2. These measurements show that the steady-state surface temperature of the drop is well below the saturation temperature, and for pure substances the equilibrium temperature decreases with decreasing drop volume similar to observations with smaller aqueous aerosols. Temperature non-uniformity within the drop is also assessed from statistics of the surface temperature fluctuations. Preliminary results from irradiated salt water drops show notably different behavior from fresh water drops, including temperature spikes as the drop volume decreases and occasional nucleate boiling. Acknowledge support from ONR #N00014-17-WX-00031.

  6. Synergistic effect of fluoride and laser irradiation for the inhibition of the demineralization of dental enamel

    Science.gov (United States)

    Lee, Raymond; Chan, Kenneth H.; Jew, Jamison; Simon, Jacob C.; Fried, Daniel

    2017-02-01

    Both laser irradiation and fluoride treatment alone are known to provide increased resistance to acid dissolution. CO2 lasers tuned to a wavelength of 9.3 μm can be used to efficiently convert the carbonated hydroxyapatite of enamel to a much more acid resistant purer phase hydroxyapatite (HAP). Further studies have shown that fluoride application to HAP yields fluoroapatite (FAP) which is even more resistant against acid dissolution. Previous studies show that CO2 lasers and fluoride treatments interact synergistically to provide significantly higher protection than either method alone, but the mechanism of interaction has not been elucidated. We recently observed the formation of microcracks or a "crazed" zone in the irradiated region that is resistant to demineralization using high-resolution microscopy. The microcracks are formed due to the slight contraction of enamel due to transformation of carbonated hydroxyapatite to the more acid resistant pure phase hydroxyapatite (HAP) that has a smaller lattice. In this study, we test the hypothesis that these small cracks will provide greater adhesion for topical fluoride for greater protection against acid demineralization.

  7. 367 cases of CO2 laser therapy on facial acne

    Science.gov (United States)

    Gao, Yunqing; Liu, Songhao; Zhang, You; Liu, T. C.

    1996-09-01

    Since 1989, we have cured 367 persons of facial acne of different course by using direct irradiation of high-power CO2 laser combing with operative therapy of low-power CO2 laser. The cure rate is 100 percent. In this paper, we stated the therapeutic approach. It was shown that this therapeutic approach is simple and effective, and its recurrence rate is zero. There are no cicatrices after healing. It is easy to accept it, and is worthy of extension.

  8. Stress relaxation damage in K9 glass plate irradiated by 1.06μm CW laser

    International Nuclear Information System (INIS)

    Luo Fu; Sun Chengwei

    2001-01-01

    Based on the stress relaxation model in 1D planar geometry and the visco-elastic constitutive equation, the temperature and stress histories in the K9 glass samples irradiated by CW laser beams (λ = 1.06 μm) have been calculated. The results indicate that the residual tensile stress due to the stress relaxation effect during cooling after the laser radiation may be greater than the tensile fracture strength of samples, while the maximum compression stress during the laser heating is less than the requirement for compression damage. For a K9 glass window of 3 mm thickness, its damage due to the stress relaxation may be induced by a laser radiation of 0.946 MW/cm 2 for 0.2s . Therefore, the stress relaxation should be regarded as the main mechanism of damage in K9 glass windows while a CW laser beam (λ = 1.06 μm) irradiates it with large spot

  9. Increase in the temperature of a laser plasma formed by two-frequency UV - IR irradiation of metal targets

    International Nuclear Information System (INIS)

    Antipov, A A; Grasyuk, Arkadii Z; Efimovskii, S V; Kurbasov, Sergei V; Losev, Leonid L; Soskov, V I

    1998-01-01

    An experimental investigation was made of a laser plasma formed by successive irradiation of a metal target with 30-ps UV and IR laser pulses. The UV prepulse, of 266 nm wavelength, was of relatively low intensity (∼ 10 12 W cm -2 ), whereas the intensity of an IR pulse, of 10.6 μm wavelength, was considerably higher (∼3 x 10 14 W cm -2 ) and it was delayed by 0 - 6 ns (the optimal delay was 2 ns). Such two-frequency UV - IR irradiation produced a laser plasma with an electron temperature 5 times higher than that of a plasma created by singe-frequency IR pulses of the same (∼3 x 10 14 W cm -2 ) intensity. (interaction of laser radiation with matter. laser plasma)

  10. Low power adder based auditory filter architecture.

    Science.gov (United States)

    Rahiman, P F Khaleelur; Jayanthi, V S

    2014-01-01

    Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT) based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.

  11. Low Power Adder Based Auditory Filter Architecture

    Directory of Open Access Journals (Sweden)

    P. F. Khaleelur Rahiman

    2014-01-01

    Full Text Available Cochlea devices are powered up with the help of batteries and they should possess long working life to avoid replacing of devices at regular interval of years. Hence the devices with low power consumptions are required. In cochlea devices there are numerous filters, each responsible for frequency variant signals, which helps in identifying speech signals of different audible range. In this paper, multiplierless lookup table (LUT based auditory filter is implemented. Power aware adder architectures are utilized to add the output samples of the LUT, available at every clock cycle. The design is developed and modeled using Verilog HDL, simulated using Mentor Graphics Model-Sim Simulator, and synthesized using Synopsys Design Compiler tool. The design was mapped to TSMC 65 nm technological node. The standard ASIC design methodology has been adapted to carry out the power analysis. The proposed FIR filter architecture has reduced the leakage power by 15% and increased its performance by 2.76%.

  12. Low power reactor for remote applications

    International Nuclear Information System (INIS)

    Meier, K.L.; Palmer, R.G.; Kirchner, W.L.

    1985-01-01

    A compact, low power reactor is being designed to provide electric power for remote, unattended applications. Because of the high fuel and maintenance costs for conventional power sources such as diesel generators, a reactor power supply appears especially attractive for remote and inaccessible locations. Operating at a thermal power level of 135 kWt, the power supply achieves a gross electrical output of 25 kWe from an organic Rankine cycle (ORC) engine. By intentional selection of design features stressing inherent safety, operation in an unattended mode is possible with minimal risk to the environment. Reliability is achieved through the use of components representing existing, proven technology. Low enrichment uranium particle fuel, in graphite core blocks, cooled by heat pipes coupled to an ORC converter insures long-term, virtually maintenance free, operation of this reactor for remote applications. 10 refs., 7 figs., 3 tabs

  13. Effects of gamma irradiations on reactive pulsed laser deposited vanadium dioxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Madiba, I.G., E-mail: madibagiven@gmail.com [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Émond, N.; Chaker, M. [Institut National de la Recherche Scientifique (INRS),1650 Blvd. Lionel-Boulet, Varennes, Québec J3X1S2 (Canada); Thema, F.T. [UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, P O Box 392, Pretoria (South Africa); iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Tadadjeu, S.I. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Muller, U.; Zolliker, P. [Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Braun, A. [ETH Zurich, Swiss Federal Institute of Technology, CH-8057, Zurich (Switzerland); Empa, Swiss Federal Laboratories Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Kotsedi, L. [iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); and others

    2017-07-31

    Highlights: • Synthesis of VO{sub 2} thin films by Reactive pulsed laser deposition has been achieved. • Properties VO{sub 2} remain mainly unaffected when subjected to gamma ray doses similar to those encountered during space missions. • The long range crystal structure of VO{sub 2} remains intact upon irradiation on different doses up to 100 kGy. • XPS reveals a shift from V{sup 4+} to V{sup 5+} oxidation state upon irradiation, due to the frenkel pair formation on the surface. • Irradiated films show the characteristic SMT of VO{sub 2}, although the electrical and optical properties are slightly affected. - Abstract: Vanadium oxide films are considered suitable coatings for various applications such as thermal protective coating of small spacecrafts because of their thermochromic properties. While in outer space, such coating will be exposed to cosmic radiations which include γ-rays. To study the effect of these γ-rays on the coating properties, we have deposited vanadium dioxide (VO{sub 2}) films on silicon substrates and subjected them to extensive γ-irradiations with typical doses encountered in space missions. The prevalent crystallographic phase after irradiation remains the monoclinic VO{sub 2} phase but the films preferential orientation shifts to lower angles due to the presence of disordered regions caused by radiations. Raman spectroscopy measurements also evidences that the VO{sub 2} structure is slightly affected by gamma irradiation. Indeed, increasing the gamma rays dose locally alters the crystalline and electronic structures of the films by modifying the V–V inter-dimer distance, which in turns favours the presence of the VO{sub 2} metallic phase. From the XPS measurements of V2p and O1s core level spectra, an oxidation of vanadium from V{sup 4+} towards V{sup 5+} is revealed. The data also reveal a hydroxylation upon irradiation which is corroborated by the vanishing of a low oxidation state peak near the Fermi energy in the

  14. Fabrication of periodical surface structures by picosecond laser irradiation of carbon thin films: transformation of amorphous carbon in nanographite

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, C.; Dorcioman, G. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125 (Romania); Bita, B. [National Institute for Research and Development in Microtechnologies, 126A Erou Iancu Nicolae Street, Voluntari RO-077190 (Romania); Faculty of Physics, 405 Atomistilor Street, Magurele RO-077125 (Romania); Besleaga, C.; Zgura, I. [National Institute of Materials Physics, 105bis Atomistilor Street, Magurele RO-077125 (Romania); Himcinschi, C. [Institute of Theoretical Physics, TU Bergakademie Freiberg, Freiberg D-09596 (Germany); Popescu, A.C., E-mail: andrei.popescu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele RO-077125 (Romania)

    2016-12-30

    Highlights: • Ripples obtained on carbon films after irradiation with visible ps laser pulses. • Amorphous carbon was transformed in nanographite following irradiation. • Ripples had a complex morphology, being made of islands of smaller ripples. • Hydrophilic carbon films became hydrophobic after surface structuring. - Abstract: Thin films of carbon were synthesized by ns pulsed laser deposition in vacuum on silicon substrates, starting from graphite targets. Further on, the films were irradiated with a picosecond laser source emitting in visible at 532 nm. After tuning of laser parameters, we obtained a film surface covered by laser induced periodical surface structures (LIPSS). They were investigated by optical, scanning electron and atomic force microscopy. It was observed that changing the irradiation angle influences the LIPSS covered area. At high magnification it was revealed that the LIPSS pattern was quite complex, being composed of other small LIPSS islands, interconnected by bridges of nanoparticles. Raman spectra for the non-irradiated carbon films were typical for a-C type of diamond-like carbon, while the LIPSS spectra were characteristic to nano-graphite. The pristine carbon film was hydrophilic, while the LIPSS covered film surface was hydrophobic.

  15. Systematic analysis of DNA damage induction and DNA repair pathway activation by continuous wave visible light laser micro-irradiation

    Directory of Open Access Journals (Sweden)

    Britta Muster

    2017-02-01

    Full Text Available Laser micro-irradiation can be used to induce DNA damage with high spatial and temporal resolution, representing a powerful tool to analyze DNA repair in vivo in the context of chromatin. However, most lasers induce a mixture of DNA damage leading to the activation of multiple DNA repair pathways and making it impossible to study individual repair processes. Hence, we aimed to establish and validate micro-irradiation conditions together with inhibition of several key proteins to discriminate different types of DNA damage and repair pathways using lasers commonly available in confocal microscopes. Using time-lapse analysis of cells expressing fluorescently tagged repair proteins and also validation of the DNA damage generated by micro-irradiation using several key damage markers, we show that irradiation with a 405 nm continuous wave laser lead to the activation of all repair pathways even in the absence of exogenous sensitization. In contrast, we found that irradiation with 488 nm laser lead to the selective activation of non-processive short-patch base excision and single strand break repair, which were further validated by PARP inhibition and metoxyamine treatment. We conclude that these low energy conditions discriminated against processive long-patch base excision repair, nucleotide excision repair as well as double strand break repair pathways.

  16. Stimulation of mitochondrial respiration induced by laser irradiation in the presence of rhodamine dyes

    International Nuclear Information System (INIS)

    Krasnikov, B.F.; Zorov, D.B.

    1996-01-01

    The effect of micromolar concentration of rhodamine 123 (methylrhodamine) and ethyl and amyl esters of unsubstituted rhodamine on oxygen consumption by rat liver mitochondria was studied under irradiation by an argon laser (488 and 514 nm). Irradiation of mitochondria in the presence of rhodamine stimulates their respiration. Light-induced stimulation of respiration is not inhibited by free radical scavenger ionol and by inhibitor of the permeability transition pore cyclosporine A. Stimulation of respiration by moderate doses of radiation is reversed in the dark. Increase in radiation dose resulted in only partial reversal of stimulated respiration in the dark. Rhodamine efficacy in stimulation of mitochondrial respiration depends on its structure (amyl > ethyl > methylrhodamine). 22 refs.; 4 figs

  17. Effect of He-Ne laser irradiation on hydrogen production by Enterobacter aerogenes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Wenyu; Wen, Jianping; Jia, Xiaoqiang; Sun, Bing; Chen, Yu.; Liu, Minhui [Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2008-01-15

    Enterobacter aerogenes W-23 bacteria exhibiting hydrogen production (HP) ability were exposed to He-Ne laser irradiation (632.8 nm) to improve the HP ability. Upon the optimum irradiation dosage (18 mW for 22.2 min), a stable positive mutant strain E. aerogenes HB-5M was obtained. The maximum specific rate of HP of the mutant strain was 0.042h{sup -1}, which was about twice that of the wild strain. It was suggested that the higher HP ability of the mutant strain might be presumably attributed to the enhancement of hydrogenase activity. In addition, the kinetic parameters of cell growth, substrate consumption and HP of the wild strain and its mutant strain were regressed to simulate the fermentation process of E. aerogenes. The simulated results agreed well with the experimental data. (author)

  18. Thermal damage produced by high-irradiance continuous wave CO2 laser cutting of tissue.

    Science.gov (United States)

    Schomacker, K T; Walsh, J T; Flotte, T J; Deutsch, T F

    1990-01-01

    Thermal damage produced by continuous wave (cw) CO2 laser ablation of tissue in vitro was measured for irradiances ranging from 360 W/cm2 to 740 kW/cm2 in order to investigate the extent to which ablative cooling can limit tissue damage. Damage zones thinner than 100 microns were readily produced using single pulses to cut guinea pig skin as well as bovine cornea, aorta, and myocardium. Multiple pulses can lead to increased damage. However, a systematic decrease in damage with irradiance, predicted theoretically by an evaporation model of ablation, was not observed. The damage-zone thickness was approximately constant around the periphery of the cut, consistent with the existence of a liquid layer which stores heat and leads to tissue damage, and with a model of damage and ablation recently proposed by Zweig et al.

  19. Laser irradiation of disk targets at 0.53 μm wavelength

    International Nuclear Information System (INIS)

    Mead, W.C.; Campbell, E.M.; Estabrook, K.G.

    1981-01-01

    We present results and analysis for laser-irradiations of Be, CH, Ti, and Au disk targets with 0.53 μm light in 3 to 35 J, 600 ps pulses, at nominal intensities from 3 x 10 13 to approx. 4 x 10 15 W/cm 2 . The measured absorptions are higher than observed in similar 1.06 μm irradiations, and are largely consistent with modeling which shows the importance of inverse bremsstrahlung and Brillouin scattering. Observed red-shifted back-reflected light shows that Brillouin is operating at low to moderate levels. The measured fluxes of multi-keV x-rays indicate low hot-electron fractions, with temperatures which are consistent with resonance absorption. Measurements show efficient conversion of absorbed light into sub-keV x-rays, with time-, angular-, and spatial-emission distributions which are generally consistent with non-LTE modeling using inhibited thermal electron transport

  20. Bone regeneration after different lengths of exposure to laser irradiation. [Rabbits

    Energy Technology Data Exchange (ETDEWEB)

    Strigina, L P

    1976-01-01

    Rabbits in which a portion of the tibia was excised and replaced with preserved bone were locally irradiated by an LG-75 laser (25 mv) for 30 seconds, 1, 2, 5, and 10 minutes a day for a month. Histological examination of sections showed an acceleration of the inflammatory reaction and more rapid maturation of periosteal callus in experimental animals compared to controls. Cartilage appeared on day 9 instead of 15. The proliferation of histiogenic cells and their differentiation into fibroblasts and osteoblasts were more vigorous than in the control. The effects of irradiation on osteosynthesis were directly dependent on the duration of exposure. The development of the inflammatory reaction and resorption of the graft were most pronounced in the animals exposed for 10 minutes daily.

  1. Phase change dynamics in a polymer thin film upon femtosecond and picosecond laser irradiation

    International Nuclear Information System (INIS)

    Bonse, J.; Wiggins, S.M.; Solis, J.; Lippert, T.

    2005-01-01

    The influence of the pulse duration on the laser-induced changes in a thin triazenepolymer film on a glass substrate has been investigated for single, near-infrared (800 nm) Ti:sapphire laser pulses with durations ranging from 130 fs up to 2.6 ps. Post-irradiation optical microscopy has been used to quantitatively determine the damage threshold fluence. The latter decreases from ∼800 mJ/cm 2 for a 2.6 ps laser pulse to ∼500 mJ/cm 2 for a pulse duration of 130 fs. In situ real-time reflectivity (RTR) measurements have been performed using a ps-resolution streak camera set-up to study the transformation dynamics upon excitation with single pulses of duration of 130 fs and fluences close to the damage threshold. Very different reflectivity transients have been observed above and below the damage threshold fluence. Above the damage threshold, an extremely complicated behaviour with oscillations of up to 100% in the transient reflectivity has been observed. Below the damage threshold, the transient reflectivity decreases by as much as 70% within 1 ns with a subsequent recovery to the initial level occurring on the ms timescale. No apparent damage could be detected by optical microscopy under these irradiation conditions. Furthermore, within the 395-410 mJ/cm 2 fluence range, the transient reflectivity increases by ∼10%. The analysis of these results indicates that the observed transformations are thermal in nature, in contrast to the known photochemical decomposition of this triazenepolymer under UV irradiation

  2. Radiation Tolerant Low Power Precision Time Source, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The availability of small, low power atomic clocks is now a reality for ground-based and airborne navigation systems. Kernco's Low Power Precision Time Source...

  3. A pulse amplitude discriminator with very low-power consuming

    International Nuclear Information System (INIS)

    Deng Changming; Liu Zhengshan; Zhang Zhiyong; Cheng Chang

    2000-01-01

    A low-power pulse amplitude discriminator is described. The discriminator circuit is mainly composed of an integrated voltage comparator, MAX921, and owns the characters of very low-power and low operating voltage

  4. Morphological changes in skeletal muscle after irradiation with nano- and microsecond laser pulses

    International Nuclear Information System (INIS)

    Gratzl, T.

    1995-09-01

    For therapeutic application of laser light it is necessary to minimize defects in the nonirradiated tissue. These defects depend on the primary mechanism of interaction between tissue and laser light. Three experiments were performed to distinguish between mechanical and thermal effects of nano- and microsecond laser pulses in skeletal muscle of the rat. The light, transmission and scanning electron microscopes were used. Laser pulses were applied to unfixed muscle immediately after dissection. A Nd-YAG laser (wavelength 1064 nm; pulse repetition rate 10s -1 ; beam diameter 9 mm; pulse-energy 340 mJ) was used in the flashlamp-pulsed mode (pulse duration 100 μs) and the Q-switched mode (pulse duration 8 ns). When focused 2 mm below the tissue surface in the μs-experiments (100 μs) 200 laser pulses produced a small crater. The defective region after irradiation can be divided under the light microscope into four zones surrounding the crater. The innermost zone I showed vacuoles in the intensively stained muscle cells. In the next zone II the myofibrils were displaced and torn apart. Zone III is a sharply bordered, intensively stained region. The muscle cells in zone IV are contracted. All these tissue effects were thermally induced. When focused 4 mm below the tissue surface, the μs-pulses produced an expansion of the irradiated region, while leaving the surface intact. Here, only the features of zones II to IV were seen. In the spallation experiments muscle samples were placed on metal foil. The foil itself was dipped into water. A single laser pulse (8 ns) was directed at the underside of the foil. Only the pressure wave passed through the sample and was reflected on the muscle surface in a stretch wave. Tissue damage by mechanical action occurs inside the sample. Muscle fibers are torn apart and myofibrils are displaced. In the ns-experiments the mechanical action of a single ns pulse (8 ns) produced a crater. Only zones I and IV developed. With 50 to 100

  5. Laser stand for irradiation of targets by laser pulses from the Iskra-5 facility at a repetition rate of 100 MHz

    International Nuclear Information System (INIS)

    Annenkov, V I; Garanin, Sergey G; Eroshenko, V A; Zhidkov, N V; Zubkov, A V; Kalipanov, S V; Kalmykov, N A; Kovalenko, V P; Krotov, V A; Lapin, S G; Martynenko, S P; Pankratov, V I; Faizullin, V S; Khrustalev, V A; Khudikov, N M; Chebotar, V S

    2009-01-01

    A train of a few tens of high-power subnanosecond laser pulses with a repetition period of 10 ns is generated in the Iskra-5 facility. The laser pulse train has an energy of up to 300 J and contains up to 40 pulses (by the 0.15 intensity level), the single pulse duration in the train being ∼0.5 ns. The results of experiments on conversion of a train of laser pulses to a train of X-ray pulses are presented. Upon irradiation of a tungsten target, a train of X-ray pulses is generated with the shape of an envelope in the spectral band from 0.18 to 0.28 keV similar to that of the envelope of the laser pulse train. The duration of a single X-ray pulse in the train is equal to that of a single laser pulse. (lasers)

  6. Study of silica coatings degradation under laser irradiation and in controlled environment; Etude de la degradation de couches minces de silice sous flux laser et en environnement controle

    Energy Technology Data Exchange (ETDEWEB)

    Becker, S

    2006-11-15

    Performances of optical components submitted to high laser intensities are usually determined by their laser-induced damage threshold. This value represents the highest density of energy (fluence) sustainable by the component before its damage. When submitted to laser fluences far below this threshold, optical performances may also decrease with time. The degradation processes depend on laser characteristics, optical materials, and environment around the component. Silica being the most used material in optics, the aim of this study was to describe and analyse the physical-chemical mechanisms responsible for laser-induced degradation of silica coatings in controlled environment. Experimental results show that degradation is due to the growth of a carbon deposit in the irradiated zone. From these results, a phenomenological model has been proposed and validated with numerical simulations. Then, several technological solutions have been tested in order to reduce the laser-induced contamination of silica coatings. (author)

  7. Angle-dependent light emission from aligned multiwalled carbon nanotubes under CO2 laser irradiation

    International Nuclear Information System (INIS)

    Zhang, Y; Gong, T; Liu, W J; Wei, J Q; Zhang, X F; Wang, K L; Zhong, M L; Wu, D H

    2007-01-01

    This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO 2 laser (λ = 10.6 μm) irradiation. Results indicate that the light emission is dependent on the angle θ between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when θ varies from 0 0 to 90 0 . The Lorentzian fitting curve displays a distinct tendency between shorter (λ 700 nm). A minimum intensity was observed at θ m close to 67 0 under shorter wavelength, whereas a maximum intensity was shown at θ m of about 60 0 at longer wavelength. These results show the anisotropic property of aligned MWNTs

  8. Erosion of CFC, pyrolytic and boronated graphite under short pulsed laser irradiation

    International Nuclear Information System (INIS)

    Kraaij, G.J.; Bakker, J.; Stad, R.C.L. van der

    1992-07-01

    The effect of short pulsed laser irradiation of '0/3' ms and up to 10 MJ/m 2 on different types of carbon base materials is described. These materials are investigated as candidate protection materials for the Plasma Facing Components of NET/ITER. These materials are: carbon fibre composite graphite, pyrolytic graphite and boronated graphite. The volume of the laser induced craters was measured with an optical topographic scanner, and these data are evaluated with a simple model for the erosion. As a results, the enthalpy of ablation is estimated as 30±3 MJ/kg. A comparison is made with finite element numerical calculations, and the effect of lateral heat transfer is estimated using an analytical model. (author). 8 refs., 23 figs., 4 tabs

  9. High-Purity Hybrid Organolead Halide Perovskite Nanoparticles Obtained by Pulsed-Laser Irradiation in Liquid

    KAUST Repository

    Amendola, Vincenzo

    2016-11-17

    Nanoparticles of hybrid organic-inorganic perovskites have attracted a great deal of attention due to their variety of optoelectronic properties, their low cost, and their easier integration into devices with complex geometry, compared with microcrystalline, thin-film, or bulk metal halides. Here we present a novel one-step synthesis of organolead bromide perovskite nanocrystals based on pulsed-laser irradiation in a liquid environment (PLIL). Starting from a bulk CHNHPbBr crystal, our PLIL procedure does not involve the use of high-boiling-point polar solvents or templating agents, and runs at room temperature. The resulting nanoparticles are characterized by high crystallinity and are completely free of any microscopic product or organic coating layer. We also demonstrate the straightforward inclusion of laser-generated perovskite nanocrystals in a polymeric matrix to form a nanocomposite with single- and two-photon luminescence properties.

  10. Direct Experimental Evidence of Back-Surface Acceleration from Laser-Irradiated Foils

    International Nuclear Information System (INIS)

    Allen, M; Patel, P; Mackinnon, A; Price, D; Wilks, S; Morse, E

    2004-01-01

    Au foils were irradiated with a 100-TW, 100-fs laser at intensities greater than 10 20 W/cm 2 producing proton beams with a total yield of ∼ 10 11 and maximum proton energy of > 9 MeV. Removing contamination from the back surface of Au foils with an Ar-ion sputter gun reduced the total yield of accelerated protons to less than 1% of the yield observed without removing contamination. Removing contamination the front surface (laser-interaction side) of the target had no observable effect on the proton beam. We present a one-dimensional particle-in-cell simulation that models the experiment. Both experimental and simulation results are consistent with the back-surface acceleration mechanism described in the text

  11. Suppressing the memory state of floating gate transistors with repeated femtosecond laser backside irradiations

    Science.gov (United States)

    Chambonneau, Maxime; Souiki-Figuigui, Sarra; Chiquet, Philippe; Della Marca, Vincenzo; Postel-Pellerin, Jérémy; Canet, Pierre; Portal, Jean-Michel; Grojo, David

    2017-04-01

    We demonstrate that infrared femtosecond laser pulses with intensity above the two-photon ionization threshold of crystalline silicon induce charge transport through the tunnel oxide in floating gate Metal-Oxide-Semiconductor transistor devices. With repeated irradiations of Flash memory cells, we show how the laser-produced free-electrons naturally redistribute on both sides of the tunnel oxide until the electric field of the transistor is suppressed. This ability enables us to determine in a nondestructive, rapid and contactless way the flat band and the neutral threshold voltages of the tested device. The physical mechanisms including nonlinear ionization, quantum tunneling of free-carriers, and flattening of the band diagram are discussed for interpreting the experiments. The possibility to control the carriers in memory transistors with ultrashort pulses holds promises for fast and remote device analyses (reliability, security, and defectivity) and for considerable developments in the growing field of ultrafast microelectronics.

  12. POLYMERS CONTAINING Cu NANOPARTICLES IRRADIATED BY LASER TO ENHANCE THE ION ACCELERATION

    Directory of Open Access Journals (Sweden)

    Mariapompea Cutroneo

    2015-06-01

    Full Text Available Target Normal Sheath Acceleration method was employed at PALS to accelerate ions from laser-generated plasma at intensities above 1015 W/cm2. Laser parameters, irradiation conditions and target geometry and composition control the plasma properties and the electric field driving the ion acceleration. Cu nanoparticles deposited on the polymer promote resonant absorption effects increasing the plasma electron density and enhancing the proton acceleration. Protons can be accelerated in forward direction at kinetic energies up to about 3.5 MeV. The optimal target thickness, the maximum acceleration energy and the angular distribution of emitted particles have been measured using ion collectors, X-ray CCD streak camera, SiC detectors and Thomson Parabola Spectrometer.

  13. Measurements of the divergence of fast electrons in laser-irradiated spherical targets

    International Nuclear Information System (INIS)

    Yaakobi, B.; Solodov, A. A.; Myatt, J. F.; Delettrez, J. A.; Stoeckl, C.; Froula, D. H.

    2013-01-01

    In recent experiments using directly driven spherical targets on the OMEGA laser system, the energy in fast electrons was found to reach ∼1% of the laser energy at an irradiance of ∼1.1 × 10 15 W/cm 2 . The fraction of these fast electrons absorbed in the compressed fuel shell depends on their angular divergence. This paper describes measurements of this divergence deduced from a series of shots where Mo-coated shells of increasing diameter (D) were suspended within an outer CH shell. The intensity of the Mo–Kα line and the hard x-ray radiation were found to increase approximately as ∼D 2 , indicating wide divergence of the fast electrons. Alternative interpretations of these results (electron scattering, radiation excitation of Kα, and an electric field due to return current) are shown to be unimportant

  14. Three-dimensional temperature field model of thermally decomposing resin composite irradiated by laser

    International Nuclear Information System (INIS)

    Chen Minsun; Jiang Houman; Liu Zejin

    2011-01-01

    Fundamental equations governing the temperature field of thermally decomposing resin composite irradiated by laser are derived from mass and energy conservation laws with the control Janume method. The thermal decomposition of resin is described by a multi-step model. An assumption is proposed that the flow of pyrolysis gas is one-dimensional, which makes it possible to consider the influence of pyrolysis gas convective transport and realize the closure of the three-dimensional model without introducing mechanical quantities. In view of the anisotropy of resin composite, expressions of the thermal conductivities of partially pyrolyzed material are deduced, as well as the computing formula for the laser absorption coefficient of partially pyrolyzed material. The energy conservation equation is consistent with reference under some simplifications. (authors)

  15. Biological behaviour of cucumbers depending on rhythm of seed irradiation with laser beam

    International Nuclear Information System (INIS)

    Cholakov, D.

    1997-01-01

    The aim of the study was to determine the optimal parameters of laser stimulation and obtained as a result resonance activation of phytohormones responsible for growth and formation of generative organs. The influence of the rhythm of irradiation on its effect was investigated. Cucumber seeds from the Bulgarian salad cultivar Gergana were irradiated with helium-neon laser of 632.8 nm wave length and exit power 20 mw. Besides control samples, the following irradiation groups were examined: 7-times on the 28th day before sowing (variant 7); 7-times in rhythm - 4-times on the 28th and 3-times on the 14th day before sowing (4+3); 7-times in rhythm - 3-times on the 28th and 3-times on the 14th and once on the day before sowing (3+3+1); 7-times in rhythm - 2-times on the 28th, the 21st and the 14th day and once on the day before sowing (2+2+2+1); 7-times in rhythm - once on the 28th, 24th, 20th, 16th, 12th, 8th and 4th day before sowing (1+1+1+1+1+1+1). There was the highest radiobiological effect at the rhythm of irradiation (2+2+2+1) and (1+1+1+1+1+1+1). The rhythmical application of radiation dose ensures better accumulation of the polarized light by the plant cells. The change of their electric vectors accelerates their growth and forces the physiological and biochemical processes. As a result the early yield has been increased respectively by 15.6% and 12% and the total standard yield - by 15.4% and 11.7%

  16. X-ray diffraction in laser-irradiated epsomite crystals grown in presence of borax

    International Nuclear Information System (INIS)

    Zaitseva, E.V.; Portnov, V.N.; Faddeev, M.A.; Chuprunov, E.V.

    1997-01-01

    Relative changes in the intensities ΔI/I of the (220) and (440) X-ray diffraction reflection during laser irradiation of epsomite (MgSO 2 ·7H 2 O) crystals grown from an aqueous solution in the presence of borax (Na 2 B 4 O 7 ·10H 2 O) were measured using the CoK α , CuK α , MoK α radiations. The intensities measured depend on the real crystal structure dependent on the borax content in the solution. The dependence of ΔI/I is studied as a function of borax in the solution and X-ray-radiation wavelength

  17. On the importance of damping phenomena in clusters irradiated by intense laser fields

    International Nuclear Information System (INIS)

    Megi, F; Belkacem, M; Bouchene, M A; Suraud, E; Zwicknagel, G

    2003-01-01

    We study the dynamics of large clusters irradiated by intense and short laser pulses, within the framework of the nanoplasma model. Particular attention is paid to the influence of electron-surface collisions, which have not been considered in previous versions of the model. We show that they dominate inverse bremsstrahlung collisions when plasmon resonance occurs. The dynamics of the cluster changes considerably and the predictions of the model are significantly modified. Moreover, there is no evidence for the presence of highly charged ions and the hydrodynamic pressure is found to be smaller than the Coulomb one

  18. Effects of He-Ne laser irradiation on the storage of turkey semen

    Directory of Open Access Journals (Sweden)

    S. Passarella

    2011-03-01

    Full Text Available Maintenance or improvement of sperm quality during storage could prevent the loss of fertilizing capacity associated with stored turkey semen. Therefore the optimization of stored turkey semen could be useful to breeder industry since the commercial production of this bird relies almost entirely on artificial insemination. Previous research have shown that He-Ne laser irradiation in mammalian sperm increased the motility (Stato, 1986, decreased the mortality, promoted the acrosome reaction, which have a pivotal role in assisted fecundating programmes as therapy for resolving infertility in domestic animals..........

  19. Role of thermal stresses on pulsed laser irradiation of thin films under conditions of microbump formation and nonvaporization forward transfer

    Science.gov (United States)

    Meshcheryakov, Yuri P.; Shugaev, Maxim V.; Mattle, Thomas; Lippert, Thomas; Bulgakova, Nadezhda M.

    2013-11-01

    This paper presents a theoretical analysis of the processes in thin solid films irradiated by short and ultrashort laser pulses in the regimes of film structuring and laser-induced forward transfer. The regimes are considered at which vaporization of the film materials is insignificant and film dynamics is governed mainly by mechanical processes. Thermoelastoplastic modeling has been performed for a model film in one- and two-dimensional geometries. A method has been proposed to estimate the height of microbumps produced by nanosecond laser irradiation of solid films. Contrary to femtosecond laser pulses, in nanosecond pulse regimes, stress waves across the film are weak and cannot induce film damage. The main role in laser-induced dynamics of irradiated films is played by radial thermal stresses which lead to the formation of a bending wave propagating along the film and drawing the film matter to the center of the irradiation spot. The bending wave dynamics depends on the hardness of the substrate underlying the film. The causes of the receiver substrate damage sometimes observed upon laser-induced forward transfer in the scheme of the direct contact between the film and the receiver are discussed.

  20. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Simonds, Brian J. [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Kheraj, Vipul [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Applied Physics, S. V. National Institute of Technology, Surat 395 007 (India); Palekis, Vasilios; Ferekides, Christos [Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States); Scarpulla, Michael A., E-mail: scarpulla@eng.utah.edu [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-06-14

    Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.

  1. Proton irradiation effects in oxide-confined vertical cavity surface emitting laser (VCSEL) diodes

    International Nuclear Information System (INIS)

    Barnes, C.E.; Swift, G.M.; Guertin, S.; Schwank, J.R.; Armendariz, M.G.; Hash, G.L.; Choquette, K.D.

    1999-01-01

    Vertical cavity surface emitting laser (VCSEL) diodes are employed as the emitter portion of opto-couplers that are used in space applications. Proton irradiation studies on VCSELs were performed at the Indiana University cyclotron facility. The beam energy was set at 192 MeV, the beam current was 200 nA that is equivalent to a flux of approximately 1*10 11 protons/cm 2 .s. We conclude that the oxide confined VCSELs examined in this study show more than sufficient radiation hardness for nearly all space applications. The observed proton-induced decreases in light output and the corresponding increases in laser threshold current can be explained in terms of proton-induced displacement damage which introduces non-radiative recombination centers in the active region of the lasers and causes a decrease in laser efficiency. These radiation effects accentuate the detrimental thermal effects observed at high currents. We also note that forward bias annealing is effective in these devices in producing at least partial recovery of the light output, and that this may be a viable hardness assurance technique during a flight mission. (A.C.)

  2. The disintegration and vaporization of plastic targets irradiated by high-power laser pulses

    International Nuclear Information System (INIS)

    Greig, J.R.; Pechacek, R.E.

    1977-01-01

    We have studied the disintegration of polyethylene and polystyrene targets irradiated by 100-J 40-nsec Nd/glass laser pulses. At power densities of approximately-less-than10 12 W/cm 2 relatively massive targets (6 x 10 -5 to 5 x 10 -4 cm 3 ) are totally disintegrated to produce finely divided target material and un-ionized vapor. Both the size of the target and the presence or absence of a laser prepulse strongly influence the proportions of finely divided target material and un-ionized vapor, especially within the first few microseconds after peak laser power. This disintegration is always preceded by the emission of a hot fully ionized plasma, but only 1% of the target material is contained in the hot plasma. Typically, (1--3) x 10 19 atoms of un-ionized vapor are released as a slowly expanding (vapprox.10 5 cm/sec) cold dense gas cloud (n/sub o/>10 19 cm -3 ) surrounding the initial target position. This cloud of target material has subsequently been heated by absorption of a 300-J 100-nsec CO 2 laser pulse to produce an approximately fully ionized plasma

  3. TDDFT investigation of excitation of water tetramer under femtosecond laser pulse irradiation

    Science.gov (United States)

    Wang, Zhiping; Xu, Xuefen; Zhang, Fengshou; Qian, Chaoyi

    2018-04-01

    We study the static properties of water tetramer in ground state, the optical absorption spectra and ultrafast nonadiabatic dynamical response of water tetramer to short and intense laser pulses with different intensities by a real-space, real-time implementation of time-dependent density functional theory coupled to molecular dynamics (TDDFT-MD) nonadiabatically. The calculated results are in good agreement with available values in literature. Four typical irradiated scenarios of water tetramer in laser field, which are “normal vibration,” “break and reorganization,” “fragmentation and new formation” and “pure fragmentation”, are explored by discussing the ionization, the bond lengths of OH bonds and hydrogen bonds and the kinetic energy of ions. The dynamic simulation shows that the reaction channel of water tetramer can really be controlled by choosing appropriate laser parameters referring to the optical absorption spectra and hydrogen ions play an important role in the reaction channel. Furthermore, it is found that the laser intensity affects the kinetic energy of ejected protons more than that of the remaining fragments and all dynamic processes are somehow directly related to the velocity of departing protons.

  4. Melanosomes are a primary target of Q-switched ruby laser irradiation in guinea pig skin

    Energy Technology Data Exchange (ETDEWEB)

    Polla, L.L.; Margolis, R.J.; Dover, J.S.; Whitaker, D.; Murphy, G.F.; Jacques, S.L.; Anderson, R.R.

    1987-09-01

    The specific targeting of melanosomes may allow for laser therapy of pigmented cutaneous lesions. The mechanism of selective destruction of pigmented cells by various lasers, however, has not been fully clarified. Black, brown, and albino guinea pigs were exposed to optical pulses at various radiant exposure doses from a Q-switched, 40 nsec, 694 nm ruby laser. Biopsies were analyzed by light and electron microscopy (EM). Albino animals failed to develop clinical or microscopic evidence of cutaneous injury after irradiation. In both black and brown animals, the clinical threshold for gross change was 0.4 J/cm2, which produced an ash-white spot. By light microscopy, alterations appeared at 0.3 J/cm2 and included separation at the dermoepidermal junction, and the formation of vacuolated epidermal cells with a peripheral cytoplasmic condensation of pigment. By EM, enlarged melanosomes with a central lucent zone were observed within affected epidermal cells at 0.3 J/cm2. At 0.8 and 1.2 J/cm2, individual melanosomes were more intensely damaged and disruption of melanosomes deep in the hair papillae was observed. Dermal-epidermal blisters were formed precisely at the lamina lucida, leaving basal cell membranes and hemidesmosomes intact. Possible mechanisms for melanosomal injury are discussed. These observations show that the effects of the Q-switched ruby laser are melanin-specific and melanin-dependent, and may be useful in the selective destruction of pigmented as well as superficial cutaneous lesions.

  5. Micro-bubble generated by laser irradiation on an individual carbon nanocoil

    International Nuclear Information System (INIS)

    Sun, Yanming; Pan, Lujun; Liu, Yuli; Sun, Tao

    2015-01-01

    Highlights: • We have investigated laser irradiated microbubbles which can be generated at fixed point on surface of an individual carbon nanocoil (CNC) immerged in deionized water. • The microbubble can be operated easily and flexibly. • Based on classical heat and mass transfer theories, the bubble growth data is in good agreement with the simplified model. - Abstract: We have investigated the micro-bubbles generated by laser induction on an individual carbon nanocoil (CNC) immerged in deionized water. The photon energy of the incident focused laser beam is absorbed by CNC and converted to thermal energy, which efficiently vaporizes the surrounding water, and subsequently a micro-bubble is generated at the laser location. The dynamics behavior of bubble generation, including its nucleation, expansion and steady-state, has been studied experimentally and theoretically. We have derived equations to analyze the expansion process of a bubble based on classical heat and mass transfer theories. The conclusion is in good agreement with the experiment. CNC, which acts as a realistic micro-bubble generator, can be operated easily and flexibly

  6. Isotope separation of 17O by photodissociation of ozone with near-infrared laser irradiation

    Science.gov (United States)

    Hayashida, Shigeru; Kambe, Takashi; Sato, Tetsuya; Igarashi, Takehiro; Kuze, Hiroaki

    2012-04-01

    Oxygen-17 is a stable oxygen isotope useful for various diagnostics in both engineering and medical applications. Enrichment of 17O, however, has been very costly due to the lack of appropriate methods that enable efficient production of 17O on an industrial level. In this paper, we report the first 17O-selective photodissociation of ozone at a relatively high pressure, which has been achieved by irradiating a gas mixture of 10 vol% O3-90 vol% CF4 with narrowband laser. The experiment was conducted on a pilot-plant scale. A total laser power of 1.6 W was generated by external-cavity diode lasers with all the laser wavelengths fixed at the peak of an absorption line of 16O16O17O around 1 μm. The beams were introduced into a 25 -m long photoreaction cell under the sealed-off condition with a total pressure of 20 kPa. Lower cell temperature reduced the background decomposition of ozone, and at the temperature of 158 K, an 17O enrichment factor of 2.2 was attained.

  7. Ultrafast switching in wetting properties of TiO2/YSZ/Si(001) epitaxial heterostructures induced by laser irradiation

    International Nuclear Information System (INIS)

    Bayati, M. R.; Molaei, R.; Narayan, J.; Joshi, S.; Narayan, R. J.

    2013-01-01

    We have demonstrated dark hydrophilicity of single crystalline rutile TiO 2 (100) thin films, in which rapid switching from a hydrophobic to a hydrophilic surface was achieved using nanosecond excimer laser irradiation. The TiO 2 /YSZ/Si(001) single crystalline heterostructures were grown by pulsed laser deposition and were subsequently irradiated by a single pulse of a KrF excimer laser at several energies. The wettability of water on the surfaces of the samples was evaluated. The samples were hydrophobic prior to laser annealing and turned hydrophilic after laser annealing. Superhydrophilic surfaces were obtained at higher laser energy densities (e.g., 0.32 J.cm −2 ). The stoichiometries of the surface regions of the samples before and after laser annealing were examined using XPS. The results revealed the formation of oxygen vacancies on the surface, which are surmised to be responsible for the observed superhydrophilic behavior. According to the AFM images, surface smoothening was greater in films that were annealed at higher laser energy densities. The samples exhibited hydrophobic behavior after being placed in ambient atmosphere. The origin of laser induced wetting behavior was qualitatively understood to stem from an increase of point defects near the surface, which lowered the film/water interfacial energy. This type of rapid hydrophobic/hydrophilic switching may be used to facilitate fabrication of electronic and photonic devices with novel properties.

  8. Low power femtosecond tip-based nanofabrication with advanced control

    Science.gov (United States)

    Liu, Jiangbo; Guo, Zhixiong; Zou, Qingze

    2018-02-01

    In this paper, we propose an approach to enable the use of low power femtosecond laser in tip-based nanofabrication (TBN) without thermal damage. One major challenge in laser-assisted TBN is in maintaining precision control of the tip-surface positioning throughout the fabrication process. An advanced iterative learning control technique is exploited to overcome this challenge in achieving high-quality patterning of arbitrary shape on a metal surface. The experimental results are analyzed to understand the ablation mechanism involved. Specifically, the near-field radiation enhancement is examined via the surface-enhanced Raman scattering effect, and it was revealed the near-field enhanced plasma-mediated ablation. Moreover, silicon nitride tip is utilized to alleviate the adverse thermal damage. Experiment results including line patterns fabricated under different writing speeds and an "R" pattern are presented. The fabrication quality with regard to the line width, depth, and uniformity is characterized to demonstrate the efficacy of the proposed approach.

  9. A Study of Polycrystalline Silicon Damage Features Based on Nanosecond Pulse Laser Irradiation with Different Wavelength Effects.

    Science.gov (United States)

    Xu, Jiangmin; Chen, Chao; Zhang, Tengfei; Han, Zhenchun

    2017-03-03

    Based on PVDF (piezoelectric sensing techniques), this paper attempts to study the propagation law of shock waves in brittle materials during the process of three-wavelength laser irradiation