GaAs Laser Irradiation Research Articles

Effects of Gallium Arsenide Laser on Pain and Grip Strength in Patients With Tennis Elbow

Introduction: Tennis elbow (Lateral Epicondylitis) is one the most common elbow and arm musculoskeletal disorders. About 1% to 3% of active population in modern societies suffer from tennis elbow. Tennis elbow is usually caused by repetitive activities of hand and wrist, especially wrist extension and forearm supination. This research aimed to study high and also medium power gallium arsenide (Ga-As) laser irradiation on improving pain and grip strength (functional mobility) in patients with tennis elbow. Material and Methods: Thirty female [Mean(SD) age: 49(2.3) y] patients with acute tennis elbow were recruited for this study. The patients were randomly divided into two groups based on random allocation table. Group A (15 patients) had been received 10 J/cm2 under a 0.5 W beam medium power Ga-As laser irradiation of 980 nm wave length. Group B (15 patients) had been received same energy density under 2 W beam high Ga-As laser irradiation with the same wavelength. Laser irradiation was performed on a 9 cm2 surface of lateral elbow epicondyle based on Grid laser application technique. The patients were under treatment for 10 sessions every other day. The outcome measures of pain at rest and ring finger extension against loading, grip strength and hand function were recorded and analyzed in a pre- and post-setting. The pain severity was measured by VAS (Visual Analog Scale) and McGill questionnaire and upper extremity function was measured by DASH questionnaire. Results: Significant pain reduction was observed in resting position and ring finger extension against loading after application of both high and medium power (980 nm, 0.5-2 W) laser therapy (P<0.05) for 10 sessions. High power laser irradiation could also increase grip strength and mobility in patients with lateral epicondylitis (P<0.05). Conclusion: High and low power Ga-As laser irradiation may improve pain and grip strength in patients with acute tennis elbow.

Low-Level Laser Therapy (904 nm) Counteracts Motor Deficit of Mice Hind Limb following Skeletal Muscle Injury Caused by Snakebite-Mimicking Intramuscular Venom Injection.

Myotoxins present in Bothrops venom disrupt the sarcolemma of muscle fibers leading to the release of sarcoplasmic proteins and loss of muscle homeostasis. Myonecrosis and tissue anoxia induced by vascularization impairment can lead to amputation or motor functional deficit. The objective of this study was to investigate the dynamic behavior of motor function in mice subjected to injection of Bothrops jararacussu venom (Bjssu) and exposed to low-level laser therapy (LLLT). Male Swiss mice received Bjssu injection (830 μg/kg) into the medial portion of the right gastrocnemius muscle. Three hours later the injected region was irradiated with diode semiconductor Gallium Arsenide (GaAs– 904 nm, 4 J/cm²) laser following by irradiation at 24, 48 and 72 hours. Saline injection (0.9% NaCl) was used as control. Gait analysis was performed 24 hours before Bjssu injection and at every period post-Bjssu using CatWalk method. Data from spatiotemporal parameters Stand, Maximum Intensity, Swing, Swing Speed, Stride Length and Step Cycle were considered. The period of 3 hours post venom-induced injury was considered critical for all parameters evaluated in the right hindlimb. Differences (p<0.05) were concentrated in venom and venom + placebo laser groups during the 3 hours post-injury period, in which the values of stand of most animals were null. After this period, the gait characteristics were re-established for all parameters. The venom + laser group kept the values at 3 hours post-Bjssu equal to that at 24 hours before Bjssu injection indicating that the GaAs laser therapy improved spatially and temporally gait parameters at the critical injury period caused by Bjssu. This is the first study to analyze with cutting edge technology the gait functional deficits caused by snake envenoming and gait gains produced by GaAs laser irradiation. In this sense, the study fills a gap on the field of motor function after laser treatment following snake envenoming.

Effects of a low-level semiconductor gallium arsenide laser on local pathological alterations induced by Bothrops moojeni snake venom

Antivenom therapy has been ineffective in neutralizing the tissue damage caused by snakebites. Among therapeutic strategies to minimize effects after envenoming, it was hypothesized that a low level laser would reduce complications and reduce the severity of local snake venom effects. In the current study, the effect of a low-level semiconductor gallium arsenide (GaAs) laser on the local pathological alterations induced by B. moojeni snake venom was investigated. The experimental groups consisted of five male mice, each administered either B. moojeni venom (VB), B. moojeni venom + antivenom (VAV), B. moojeni venom + laser (VL), B. moojeni venom + antivenom + laser (VAVL), or sterile saline solution (SSS) alone. Paw oedema was induced by intradermal administration of 0.05 mg kg(-1) of B. moojeni venom and was expressed in mm of directly induced oedema. Mice received by subcutaneous route 0.20 mg kg(-1) of venom for evaluating nociceptive activity and the time (in seconds) spent in licking and biting the injected paw was taken as an indicator of pain response. Inflammatory infiltration was determined by counting the number of leukocytes present in the gastrocnemius muscle after venom injection (0.10 mg kg(-1)). For histological examination of myonecrosis, venom (0.10 mg kg(-1)) was administered intramuscularly. The site of venom injection was irradiated by the GaAs laser and some animals received antivenom intraperitoneally. The results indicated that GaAs laser irradiation can help in reducing some local effects produced by the B. moojeni venom in mice, stimulating phagocytosis, proliferation of myoblasts and the regeneration of muscle fibers.

Comparative study of the application of microcurrent and AsGa 904 nm laser radiation in the process of repair after calvaria bone excision in rats

This study evaluated the effects of microcurrent stimulation (10 μA/5 min) and 904 nm GaAs laser irradiation (3 J cm−2 for 69 s/day) on excisional lesions created in the calvaria bone of Wistar rats. The results showed significant responses in the reduction of inflammatory cells and an increase in the number of new blood vessels, number of fibroblasts and deposition of birefringent collagen fibers when these data were compared with those of samples of the untreated lesions. Both applications, microcurrent and laser at 904 nm, favored tissue repair in the region of bone excisions during the study period and these techniques can be used as coadjuvantes in the repair of bone tissue.

INFLUENCE OF A LOW-LEVEL SEMICONDUCTOR GALLIUM ARSENATE LASER IN EXPERIMENTAL ENVENOMATION INDUCED BY &lt;i&gt;BOTHROPS ATROX&lt;/i&gt; SNAKE VENOM

Bothrops atrox is responsible for the majority of snakebite accidents in Brazilian Amazon and its venom can cause prominent local tissue damage. Experimental groups consisted of five male mice, each administered either B. atrox Venom (VB), B. atrox Venom + Antivenom (VAV), B. atrox Venom + Laser (VL), B. atrox Venom + Antivenom + Laser (VAVL), or Sterile Saline Solution (SSS) alone. Paw oedema was induced by intradermal administration of 0.05 mg kg-1 of B. atrox venom and was expressed in mm of directly induced oedema. Mice were subcutaneously injected with 0.10 mg kg-1 of venom for evaluation nociceptive activity and the time (in seconds) spent in licking and biting responses of the injected paw were taken as an indicator of pain response. Inflammatory infiltration was determined by counting the number of leukocytes present in the gastrocnemius muscle after venom injection (0.10 mg kg-1). Myotoxicity was studied by determining the plasmatic rise of creatine kinase activity after venom injection (0.20 mg kg-1). For histological examination of myonecrosis, venom (0.10 mg kg-1) was administered intramuscularly. The site of venom injection was irradiated by GaAs laser and some animals received antivenom intraperitoneally. GaAs laser irradiation administered in conjunction with antivenom, reduced pain, oedema, inflammation and myonecrosis induced by B. atrox venom in mice. The combined antivenom and GaAs laser treatment was more effective than separately treatments. The results suggest that laser therapy may reduce the local effects induced by B. atrox venom when associated with antivenom.

Analysis of 532nm long pulse laser-induced thermal decomposition damage to GaAs by semi-analytical method

Considering the fact that the GaAs has the characteristics of thermal decomposition, the thermal decomposition damage to GaAs surface, induced by a 532 nm wavelength long pulse laser with a millisecond pulse width is studied by the heat conduction theoretical and semi-analytical method. First, the calculation models of two-dimensional axisymmetric transient temperature field and the surface thermal decomposition damage threshold for long pulse laser irradiation of GaAs are established, and the transient temperature fields and the thermal decomposition damage thresholds in GaAs with different absorption rates are simulated. The results show that the higher absorption rate causes the higher temperature rise on the surface of material, but the required decomposition damage energy density is lower. With the increase of laser energy density, the decomposition damage occurs more early. This paper has guiding significance and practical value for investigating the interaction between long pulse laser and GaAs and its damage mechanism.

Time delay in InGaN multiple quantum well laser diodes at room temperature

This paper reports that a long delay between the beginning of pumping current pulse and the onset of optical pulse is observed in InGaN laser diodes. The delay time decreases as the pumping current increases, and the speed of the delay time reduction becomes slower as the current amplitude increases further. Such delay phenomena are remarkably less serious in laser diodes grown on GaN substrate than those on sapphire. It attributes the delay to the traps which cause a large optical loss by saturable absorption and retard the laser action. The traps can be bleached by capturing injected carriers. The effect of GaAs laser irradiation on InGaN laser action demonstrates that the traps responsible for the delay are deep centres which can be filled by the photo-assisted processes.

A Laserterapia de baixa intensidade acelera a regeneração de nervos periféricos

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% (p&lt;0.05). Observou-se melhora progressiva do IFC tanto nos nervos irradiados como nos controles (69% e 45%, respectivamente), com diferença significante entre ambos na segunda semana (p=0,04). A densidade de fibras aumentou para os nervos irradiados e diminuiu para os nervos controle, a diferença entre ambos sendo significante (p=0,001). Os autores concluem que a terapia com o laser de baixa intensidade efetivamente acelera a regeneração do nervo isquiático do rato.

Ga-As (808 nm) Laser Irradiation Enhances ATP Production in Human Neuronal Cells in Culture

The aim of the present study was to investigate whether Ga-As laser irradiation can enhance adenosine triphosphate (ATP) production in normal human neural progenitor (NHNP) cells in culture. NHNP were grown in tissue culture and were treated by Ga-As laser (808 nm, 50 mW/cm(2), 0.05 J/cm(2)), and ATP was determined at 10 min after laser application. The quantity of ATP in laser-treated cells was 7513 +/- 970 units, which was significantly higher (p < 0.05) than the non-treated cells, which comprised 3808 +/- 539 ATP units. Laser application to NHNP cells significantly increases ATP production in these cells. These findings may explain the beneficial effects of low-level laser therapy (LLLT) in stroked rats. Tissue culture of NHNP cells might offer a good model to study the mechanisms associated with promotion of ATP production in the nervous system by LLLT.

Effects of the Ga-As laser irradiation on myonecrosis caused by Bothrops Moojeni snake venom.

Viper snake envenoming induces in the victims systemic coagulopathy, and severe local tissue damage such as edema, hemorrhage, intense pain, and myonecrosis. Serumtherapy and other first-aid managements are ineffective in neutralizing these local effects. The effects of the gallium-arsenide (Ga-As) laser irradiation on mice gastrocnemius injected intramuscularly (i.m.) with Bothrops moojeni snake venom were investigated. Macroscopical, histopatological, and myonecrosis quantification through serum creatine kinase (CK) evaluation was done at 3, 12, and 24 hours (two, five, and eight irradiation sessions, 4 J/cm(2), 1 minute 32 seconds per period, respectively), were done after the venom or saline injection, and in venom-unirradiated mice. In unirradiated gastrocnemius, the venom induced massive hemorrhage, vascular congestion, time-progressing myonecrosis, edema, abundant inflammatory infiltrate, and high CK serum levels. Ga-As irradiation significantly decreased the amount of myonecrosis in all the periods tested (P < 0.05). The laser treatment significantly inhibited the ability of B. moojeni venom to rapidly disrupt the integrity of the plasma membrane.

Laser irradiation of GaAs[sbnd]GaAlAs multi-quantum well structure

We have studied the effects produced by laser irradiation with 355 nm photons on a heterostructure made of three independent GaAs/Ga0.67Al0.33As quantum wells. By comparing the luminescence of the three quantum wells before and after the laser irradiation for different durations and fluence values one could determine if the structure of each quantum well has been altered or not. Then we achieved complementary observations of the irradiated multi-quantum wells structures, using both scanning and transmission electron microscopy. We came to the conclusion that the alteration of the multi-quantum wells structure results from two main consequences of the sample pulsed laser heating: the formation of an altered layer which accompanies the pulsed laser sputtering process and the thermal diffusion process.

Cw laser irradiation of GaAs: Arsenic formation and photoluminescence degradation

Low-power, cw laser irradiation of GaAs leads to the formation of solid arsenic at the sample surface and to the degradation of band-gap photoluminescence (PL) efficiency. In situ Raman scattering and PL are used to measure the lattice and carrier temperature in addition to monitoring the arsenic formation and PL efficiency. Both effects are athermal, do not involve surface oxidation, and occur in n,p and semi-insulating GaAs prepared by different growth techniques. These observations suggest that arsenic formation and PL decrease may both be the result of a nonradiative recombination process.

Effect of semiconductor GaAs laser irradiation on pain perception in mice

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.

Pulsed-Laser Induced Desorption in GaAs: A Dynamic Pulse Mass Counting Study

Desorption of neutral atoms and molecules of pulsed laser irradiation of GaAs has been studied by means of a pulse mass counting technique. The translational temperature of desorbing molecules, As2 is found to be three times higher than that of As atoms. Remarkable angular dependence of translational temperature is also observed. These facts suggest that the translational temperature does not necessarily indicate the surface temperature when particles are desorbed.

Pulsed laser irradiation of GaAs under oxygen and silane atmosphere: Incorporation, losses, influence of native oxide

Gallium arsenide single crystals and thin GaAs amorphous deposits (in the 100-nm range) on Si have been irradiated by pulsed (15 ns) ruby laser under various pressures of 16O2. All the samples were anodically preoxidized in order to obtain a 10-nm-thick 18O enriched oxide, the aim being to study the influence of native oxide on oxygen incorporation during irradiation. Nuclear microanalysis and channeling experiments provide information on (i) 16O incorporation, (ii) 18O losses and concentration profile, (iii) Ga and As atoms out of crystallographic sites for single crystal irradiations, and (iv) Ga and As losses for thin films irradations. Our results demonstrate that a surface oxide is formed with a composition near the Ga2O3-As2O3 stoichiometry via oxygen penetration in the melted layer once the native oxide has been evaporated at irradiation energies above 1 J/cm2. Before complete evaporation,this latter oxide diffuses in GaAs and is responsible for defect creation at irradiation energies as low as 0.4 J/cm2. We also find that for irradiation in vacuum the surface composition varies continuously, from Ga to As rich, when the irradiation energy density goes from 0.4 to 1.5 J/cm2. Pulsed irradiations at 0.53 μm under silane atmosphere lead to strong Si doping. We show that the mechanism involved is pyrolisis of SiH4, surface deposition of the Si formed and finally diffusion of the deposited layer in GaAs during melting.

Evaporation and ripple formation during pulsed laser irradiation of GaAs

The evaporation of As and Ga during pulsed laser irradiation of GaAs single crystals was measured under vacuum. The data were reproduced in a thermal-model calculation. The laser power density useful for annealing was found to be limited both by excessive evaporation and surface ripple formation.

Effects of laser irradiation of GaAs observed by d.l.t.s.

A Q-switched ruby laser has been used to heat-treat vapourphase-epitaxial (v.p.e.) GaAs. The characteristic A-centre, a deep trapping level at 0.83 eV, is removed using a laser pulse of energy density 0.3 J cm−2. Trapping levels are observed using deep-level transient spectroscopy (d.l.t.s.).