Effect Of CO2 Laser Radiation Research Articles

Characterization by FTIR spectroscopy of degradation of polyethylene films exposed to CO2 laser radiation and domestic composting

Polyethylene (PE) is a non-biodegradable polymer and accumulate easily on environment due its high molecular weight. In order to reduce this problem low-density (LDPE), high-density (HDPE) and biodegradable (BIO-PE) polyethylene films were exposed to CO2 laser radiation at different fluences and to domestic composting, the effects of CO2 laser radiation and domestic composting were characterized by FTIR spectroscopy. LDPE, HDPE and BIO-PE exposed to CO2 laser radiation underwent thermodegradation reactions causing changes in LDPE, HDPE and BIO-PE chemical and physical properties due to chain scission. LDPE, HDPE and BIO-PE biodegradation reactions leading to the formation of carbonyl (C=O), vinyl (CH2=CH) and hydroxyl (OH) groups.

Electrochemical Properties of CO2 Laser Radiated Carbon-Based Electrodes for Supercapacitors

Supercapacitor have been widely researched in order to apply many fields such as a hybrid electric vehicles, high pulse power sources, and emergency power sources requiring high power instantly. However, supercapacitor has low energy density compared to batteries. In order to increase the energy density of supercapacitor, electrode is the very important. Until now, porous carbons, which have low energy density (5~10 Wh kg-1) are the widely used for electrode materials. Recently, many reports have been released using a surface treated carbon or graphene, RGO and CDC, etc. However, these ways have much time and costs in order to compensate the energy. In this study, the CO2 laser treated carbon electrode is investigated for high-performance supercapacitors. First of all, in order to investigate the effect of CO2 laser radiation on energy density and microstructure, carbon electrode was fabricated as a mixture of active material, conductive material, and PVDF binder. The mixed slurry with NMP was coated onto an aluminum plate and dried at 100 oC for 12h. And then CO2 laser was radiated onto the surface of the carbon electrode. A 2032coin cell was assembled with the TEABF4 as electrolyte and separator. The microstructure difference was investigated with SEM and cyclic voltammetry tests also were carried out in the potential range of 0 to 2.7 V for comparison to CO2 laser radiated and un-radiated carbon electrode.

Evaluation of the effect of CO2 laser radiation on root cementum

Evaluation of the effect of CO2 laser radiation on root cementum

Physical mechanisms of fast structure modification and the appearance of waves of optical bleaching in glass ceramics

Amorphization and reverse crystallization of glass ceramics under laser action is a popular object of research in recent years. This process has been shown to have some important peculiarities: a very high rate and nontraditional kinetics. These peculiarities are explained in this paper based on a thermophysical kinetic analysis and an unconventional consideration of amorphous material as a crystal deformed by vacancies (CDV). Experiments of the glass-ceramics structure modification were carried out under the action of two types of lasers: CO2 and YAG:Nd. The effect of CW YAG:Nd laser radiation with a wavelength of 1.06 μm differs significantly from the effect of CO2 laser radiation. The reason for the difference is that the crystalline phase absorbs the radiation at 1.06 μm, while the melted phase is transparent for that. As a result, the absorbing zone is shifted to the front of bleaching. In addition, the occurrence of the feedback between the heating rate and the optical properties results in the development of complex kinetics of both the temperature distribution and the optical properties. This specific thermooptical effect leads to the appearance of waves of optical bleaching.

Physical mechanisms of fast structure modification and the appearance of waves of optical bleaching in glass ceramics

Amorphization and reverse crystallization of glass ceramics under laser action is a popular object of research in recent years. This process has been shown to have some important peculiarities: a very high rate and nontraditional kinetics. These peculiarities are explained in this paper based on a thermophysical kinetic analysis and an unconventional consideration of amorphous material as a crystal deformed by vacancies (CDV). Experiments of the glass-ceramics structure modification were carried out under the action of two types of lasers: CO2 and YAG:Nd. The effect of CW YAG:Nd laser radiation with a wavelength of 1.06 μm differs significantly from the effect of CO2 laser radiation. The reason for the difference is that the crystalline phase absorbs the radiation at 1.06 μm, while the melted phase is transparent for that. As a result, the absorbing zone is shifted to the front of bleaching. In addition, the occurrence of the feedback between the heating rate and the optical properties results in the development of complex kinetics of both the temperature distribution and the optical properties. This specific thermooptical effect leads to the appearance of waves of optical bleaching.

Laser surface treatment of magnesia partially stabilized zirconia for enhanced human skin fibroblast cell response

Promoting or inhibiting cell adhesion to biomaterials is often crucial to the proper function of a biomaterial. In order to induce a surface with better bioactivity for promoting the bonding between the tissue and this bioinert ceramic interface, an industrial CO2 laser was used to alter the surface properties of magnesia (MgO)-partially stabilized zirconia (PSZ) with various laser power densities. The general effects of CO2 laser radiation on the MgO–PSZ were analyzed to investigate the modifications of surface microstructure, surface oxygen content, and surface roughness of the material. In in vitro evaluation, human skin fibroblast cells were seen to attach onto the MgO–PSZ following CO2 laser treatment, whereas, no cell attachment was found on the untreated MgO–PSZ after 7 day cell culture. Moreover, some cells on the CO2 laser treated MgO–PSZ could be considered as flattened and spread, implying the final stage of the cell attachment. A relationship was observed between the extent of cell attachment and surface properties of the MgO–PSZ with various laser power densities, exhibiting the ability of laser surface process for controlling the cell attachment.

Effect of CO2 laser radiation on the surface properties of polyethylene terephthalate

Abstract The surfaces of polyethylene terephthalate (PET) obtained by irradiation with a CO2 pulsed laser in air were studied. The complicated microstructures using various laser wavelengths were observed by scanning electron microscopy (SEM). The changes in chemical and physical properties of the irradiated PET surface were investigated by attenuated total reflectance infrared spectroscopy (ATR-FTIR) and contact angle measurements. ATR-IR spectrum showed that the crystallinity in the surface region decreased due to laser irradiation. The water drop contact angle also decreased with increasing of laser pulses. The density of peroxides formed on the irradiated PET surface were determined by iodide method.

Buried layer formation in silicon by laser radiation

The effect of CO2 laser radiation on the spatial distribution and state of oxygen or nitrogen atoms, implanted in silicon wafers, is investigated experimentally. Infrared spectroscopy of the implanted and irradiated samples showed the formation of a new phase inside the silicon. Auger spectrometry of the implanted oxygen atom distribution function showed a decrease in its width by 6%, and a shift of the distribution maximum toward the irradiated surface of the wafer by 0.25 of the initial half-width. A stochastic model describing the process of buried layer formation from interacting impurities in the presence of a temperature gradient is proposed. A nonlinear diffusion equation is derived and the results obtained within this model are in qualitative agreement with our experiments. The possibility of forming buried layers in Si, i.e., SiO2 or Si3N4, as well as controlling their thickness and depth of location by means of CO2 laser irradiation is shown both experimentally and theoretically.

Effects of CO2 laser radiation on large orthophosphoric acid and water drops and on spherical ice crystals

An experimental investigation is reported of the conditions present during evaporation of suspended orthophosphoric acid and water drops, and of spherical ice crystals with a radius of the order of 1 mm when the laser radiation power density was 20–104 W cm-2 at the wavelength of 10.6 μm. The lower limit of explosive evaporation was determined for H3PO4 drops and ice crystals. Only one evaporation mechanism of H3PO4 drops was observed (this mechanism was explosive), but there were two mechanisms in the case of water drops (convective with vapour ejection and explosive) and spherical ice crystals (melting followed by evaporation of a water drop and explosive evaporation). Repeated explosions of H2O drops were observed for a power density w = 104 W cm-2 when the beam diameter was 10 mm.

CO2-Laser radiation damage of the arterial wall

This study describes the effects of CO2 laser radiation on the histology of the normal rabbit arterial wall, using models that simulate laser angioplasty and anastomosis. Rabbit arteries were exposed to laser treatments similar to those used clinically; 40, 0.5 sec pulses of 40-60 mW, CO2 continuous wavelength laser, or a 1/2-circumferential laser anastomosis with a 60-80 mW continuous pulse. Aneurysms developed in 8 of 22 femoral, 1 of 22 carotid, and no controls at 12 week. There were small breaks in the internal elastic lamina with atrophy, loss of muscularis, "packing" of the elastica, thinning of the muscularis at the damage site, and enlargement of the arterial diameter. Aneurysms developed in one femoral and no carotid anastomosed artery. Laser anastomoses demonstrated more muscle damage and loss, with extensive scarring and a wider area of elastic loss than the controls. The intima was reestablished with focal reduplication of the internal elastic lamina. There were no histologic differences between the arteries which developed aneurysms and those which did not in either series. These results suggest that low power laser damage of the arterial wall consists mainly of destruction of the muscularis propria, with minimal damage to the elastica.

Bursting strength in CO2 laser-assisted microvascular anastomoses.

Iliac artery end-to-end anastomoses were performed in 42 Sprague-Dawley rats, divided into seven groups, to determine the welding effects of CO2 laser radiation in microvascular anastomoses. Conventional suture techniques were performed on right iliac arteries, and left iliac arteries were anastomosed with a laser-assisted technique. Bursting strength and diameters of the anastomotic sites were measured at different intervals (from one day to five weeks) post surgery. The anastomotic patency rate was 100 percent in both groups, and the aneurysm rate was only 2 percent in the laser group. Bursting strength was low at one and three days post surgery in both groups; then, it increased gradually until both groups could withstand higher than physiologic pressures. Results of high patency rates, low aneurysm formation, and the ability to withstand pressures higher than physiologic, suggest that the laser-assisted anastomotic technique can play an important role in microvascular surgery.

Effects of CO2 laser radiation on the skin of the rat. Light and scanning electron microscopy study.

Effects of CO2 laser radiation on the skin of the rat. Light and scanning electron microscopy study.

Interaction of CO2 laser and soft tissue. The basic mechanism of the carbon dioxide laser irradiation of the soft tissue.

The purpose of this paper was to investigate the immediate effects of CO2 laser radiation on soft tissue. The morphological changes were studied with gross observations, light microscopy, scanning electron microscopy and were related to the results of thermal measurements . The events which take place during the irradiation were viewed with ultra high speed photography. Air-borne tisssue particles were investigated with cytosmear test and tissue culture. Based upon the various observations, the following conclusions were drawn. The immediate effects of CO2 laser irradiation consit of two factors : physio-mechanical factor and physio-chemical factor. And the nature of the laser injury, in soft tissue, make laser surgery a practical and satisfactory method of controlled tissue removal.

CO2 laser in vitreoretinal surgery.

Radiation from a CO2 laser has the dual effect of phototransection and photocoagulation. Incisions have been made in scleral-chorioretinal tissue, lens tissue, and the vitreous body (with and without membrane formation). Results indicate that the CO2 laser may be useful in intravitreal surgery. Its simultaneous cutting and coagulating properties may make the experimental transvitreal chorioretinal biopsy reported by Griffin et al [12] and the full-thickness ocular wall resection for small melanosarcomas of the choroid reported by Peyman and Sanders [13] clinical possibilities in the not too distant future. Finally, the effects of CO2 laser radiation on the normal human lens suggests the possibility of the dissolution of cataracts by laser irradiation.

CO2 Laser in Vitreoretinal Surgery: 1. Quantitative Investigation of the Effects of CO2 Laser Radiation on Ocular Tissue

Scleral, lens, and vitreoretinal tissue was incised using CO2 laser radiation in a controlled and predictable fashion without producing untoward effects on neighboring ocular tissue. The penetration depth of infrared radiation into normal human vitreous was measured and was found to be exceedingly small. A quantitative correlation was observed between the CO2 laser power and the depth of penetration in scleral-chorio-retinal wall incisions and in lens tissue from human eyebank eyes. The results of this investigation suggest that the CO2 laser may be useful in intravitreal surgery, full-thickness scleral-chorio-retinal wall resections, transvitreal chorioretinal biopsy, and even dissolution of cataracts.

A model for laser isotope separation in SF6

We propose a model for the effect of CO2 laser radiation in decomposing and separating isotopes of SF6. Analytic expressions for oscillator strengths are derived for discrete-to-discrete, discrete-to-continuum, and continuum-to-continuum energy level transitions. Loss in oscillator strength as the system is driven up the manifold is compensated for by a cooperative power broadening that contains an explicit dependence on level degeneracies. Isotope selectivity and yield at low pressures are computed as a function of laser intensity, and a threshold in yield is found at approximately 14 MW/cm2.