Nd-YAG Research Articles

Development of graded composition and microstructure on Inconel 718 by laser surface alloying with Si, Al and ZrB2 for improvement in high temperature oxidation resistance

The present study evaluates the scope of improvement of oxidation resistance of Inconel 718 (IN718) by laser surface alloying (LSA) with Si, Al and ZrB2 using a 0.5 kW continuous wave Nd-YAG laser. The alloyed zone (AZ) is free of macro-defects (porosity, crack, etc.) and contains microstructural and compositional gradation along vertical depth from the top surface until the AZ-substrate interface. Detailed microstructural and phase evolution studies indicate that the AZ consists of multiple intermetallic phases/compounds of Si, Al or Zr with multi-phase eutectic aggregate including Ni-rich matrix phase. The identity, size, morphology and relative amount of these phases vary with LSA parameters and vertical depth within the AZ. Accordingly, the microhardness profile along depth corroborates such graded microstructure and phase aggregate confined to the AZ. Isothermal oxidation studies at 900 °C show significant improvement in oxidation resistance due to LSA in comparison to that of as-received IN718, particularly in case of LSA with Si. Post oxidation studies reveal that the oxide scale consists of adherent oxides like SiO2, Al2O3 or ZrO2, in addition to several intermetallic phases pre-existing in the AZ prior to oxidation. Thus, it follows that the intermetallic phase rich AZ developed by LSA is adherent, defect-free, strong and offers very high resistance to oxidation in IN718 at elevated temperature.

Surface treatment of RMGIC to composite resin using different photosensitizers and lasers: A bond assessment of closed Sandwich restoration.

The aim of present study was to assess and compare different conditioning methods (laser, PDT and conventional) on shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) bonded to composite (sandwich technique). Fifty specimens were prepared from RMGIC and were packed in a teflon mould placed on glass slab. Through each of the glass slab the cement was light cured for 20 s. Now samples were randomly allocated into five groups (n = 10) according to pre-treatment protocols. In group 1 RMGIC were conditioned with MBP using PDT, Samples in group 2 treated with Er,Cr:YSGG (ECYL), group 3 pre-treated with Nd:YAG laser (NYL), samples in group 4 surface conditioned with air abrasion (AA) and group 5 conditioned with 37 % phosphoric acid (PA). Specimens after conditioning were rinsed with distilled water. Adhesive Adper Single Bond 2 was applied on treated surface of RMGIC and cured. Teflon mold was utilized to hold the composite Filtek Z250 in an incremental technique. For SBS testing all specimens were placed under shear knife edge at 1 K N at a speed of 0.5mm2 until bond failure. Optical microscope was used to evaluate failure pattern at 10x magnification. The data of SBS in Megapascal were subjected to statistical test. Analysis of variance was followed by Post hoc test with level of significance at 5 %. The maximum SBS was found in group 5 RMGIC conditioned with 37 % PA (16.45 ± 0.32 MPa). Whereas, group 1 (MBP, PDT) demonstrated significantly lower bond integrity (9.82 ± 1.08 MPa) compared to all experimental groups. Bond integrity of RMGIC surface treated with MBP, PDT (9.82 ± 1.08 MPa), group 3 lased with NYL (11.47 ± 0.53 MPa) and samples in group 4 conditioned with AA (11.23 ± 0.47 MPa) were comparable (p > 0.05). ECYL has a potential to be used for conditioning of RMGIC prior to composite restoration (sandwich technique). MBP at 100 mg/L deteriorates SBS of composite to RMGIC.

Split-face comparison of grid fractional radiofrequency vs 1064-nm Nd-YAG laser treatment of periorbital rhytides among Filipino patients.

Despite multiple individual studies proving efficacy of grid fractional monopolar radiofrequency (Grid RF) and near-infrared irradiation 1064-nm long-pulsed neodymium:YAG laser (Laser Genesis), there is a lack of controlled comparative trials between these devices. This study aims to compare the efficacy and safety of Grid RF versus Laser Genesis in the treatment of periorbital rhytides. This is a randomized, single-blind, split-face, prospective study. Eight patients with moderate to severe periorbital rhytides were treated with either Grid RF or Laser Genesis on each side of the face. Photographic and live assessment with the Lemperle Wrinkle Assessment grading scale was compared after 2 months. Difference in scores between Grid RF vs Laser genesis groups after 2 months was not statistically significant (P = 0.244). Each group showed statistically significant improvement months post-procedure (P < .05). Immediate adverse effects and satisfaction scale were similar for both groups (P > .05). At 2 months follow-up, no adverse effects were seen. Grid monopolar radiofrequency (Grid RF) vs near-infrared radiation 1064 nm long-pulsed Nd-YAG laser (Laser Genesis) were equally efficacious, safe, and well-tolerated among patients in the treatment of periorbital wrinkles (P > .05).

Experimental investigation of laser ablation of stone polycrystalline targets

We report the results of an experimental investigation of ablation of stone polycrystalline targets of complex multicomponent composition, which imitate the substance of asteroids. The targets were irradiated by nanosecond pulses of a neodymium laser at an energy density ΦL of up to 5 × 104 J cm−2. The experiments demonstrated the existence of two ablation regimes, with the boundary between them lying at ΦL ≈ 4000 J cm−2. The regime change is characterised by a change in the form of the dependence of the surface mass density of removed target material on the laser energy density and by the appearance of a minimum in the dependence of specific energy of destruction on ΦL. This is supposedly related to the passage from a one-dimensional plasma plume expansion to the three-dimensional one and the corresponding decrease in the efficiency of energy transfer from the laser beam to the target due to a lowering of laser-produced plasma density. Our experiments also showed the existence of a maximum in impulse coupling coefficient Cm as a function of laser energy density (Cm ≈ 6.3 × 10−5 N W−1 for ΦL = Φopt ≈ 25 J cm−2). Maxima were also recorded in the dependences of the ablation efficiency and average ablation flow velocity on ΦL. For ΦL > Φopt, the decrease in the function Cm(ΦL) turns out to be much steeper than for metals and polymer materials. The difference is supposedly due to the lower strength and lower plasticity of the polycrystalline stone targets.

Neodymium YAG laser chemical vapor deposition growth of luminescent Mo2S3 nanocrystals using bulk MoS2 and its structural, optical properties and caspase-mediated apoptosis in THP-1 monocytic cells

Metal-sulphur phase-based semiconductor materials are often investigated in the field of nanotechnology. Herein, we describe the synthetic route to obtain Mo2S3 nanocrystals from MoS2 via a laser-furnace technique. These nanocrystals have been tested for cytotoxicity against the monocytic leukemic THP-1 cell line. The synthetic process caused a phase change from MoS2 to Mo2S3 at a temperature of 1100 °C and a pressure of 400 Torr. Powder X-ray diffraction analysis confirmed the crystallinity and structure and X-ray photoelectron spectroscopy confirmed the chemical composition and oxidation states of the Mo2S3 nanocrystals. The morphology of the Mo2S3 has been observed by using field emission scanning electron microscopy and high-resolution transmission electron microscopy. The in vitro cytotoxicity evaluation of the Mo2S3 nanocrystals was determined in the THP-1 cell line. The cytotoxic potential of the Mo2S3 against THP-1 cells was assessed by the WST-1 assay and intracellular caspase activities. The caspase activities were significantly elevated indicating the initiation of both the intrinsic and extrinsic apoptotic pathways when compared to untreated cells. Field emission scanning electron microscopy revealed that the Mo2S3 NCs compromised the cell membrane integrity resulting in a loss of THP-1 cell viability and apoptosis. Thus, Mo2S3 is an aqueous nanocrystal which shows promising cytotoxicity effect against THP-1 with good photoluminescent properties.

Synthesis and characterization of PVA-Graphene-Ag nanocomposite by using laser ablation technique

The PVA-G-Ag nanocomposite have been synthesized effectively by pulsed laser ablation liquid (PLAL) as a considered to be environmentally friendly and free of residues from chemical reactions. The high excellence silver plate (99.99%) and graphite plate (99.99%) was immersed in the polyvinyl alcohol (PVA) solution and irradiated with the Nd-YAG laser at wavelength 1064 nm, power 160 mJ for the silver plate and 80mJ for graphite plate, reiteration rate 6 Hz, 10 ns pulse width and 300 pules for graphite plate and 700 pulse for silver plate. The pure of PVA, PVA-Graphene and PVA-Graphene-Ag nanocomposite were investigated using UV-VIS spectroscopy, FTIR and SEM. The absorption spectra of PVA-Graphene-Ag nanocomposite show the presence of two peaks one 0.4 at 272 and second 0.47 at 403 nm. The optical energy gap (Eg) decreased from 5eV of a pure PVA to 4.6eV of a PVA-G-Ag for indirect allowed transition and therefore, decreased from 4.4eV of a pure PVA to 4.1eV of a PVA-G-Ag for indirect forbidden transition. The transmittance and absorption coefficient have been determined. The SEM images confirmed that homogenous composite without aggregation of the components. The average size of nanoparticles of GNPs and AgNPs for PVA-G and PVA-G-Ag nanocomposite was 130 and 115 nm respectively. The FTIR has demonstrated that the connection between the graphene, silver and polymer network was enough to have stable nanocomposite. This investigation demonstrates that the pulse laser ablation decent instrument to decorated metals on the graphene with the presence of the polymer.

The Performance of Plasmonic Gold and Silver Nanoparticle-Based SERS Sensors

The influence of different types of plasmonic gold (Au-NPs) and silver (Ag-NPs) nanoparticles as well as aging on the performance of Surface-Enhanced Raman Scattering (SERS) sensors were studied. The average diameters of Au-NPs and Ag-NPs were about 23 nm and 15 nm, respectively, with a number of laser pulses of about 200. plasmonic nanoparticles were synthesized by laser ablation process in distilled water using a fixed energy laser fluence of about 14 J/cm2 of Nd-YAG laser, with 1060 nm wavelength and 1 Hz pulse repetition rate. The SERS sensor was carried out by quick drop casting process of plasmonicplasmonic nanoparticles on glass substrates. The morphological aspects and the performance of SERS sensors were investigated by high resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy. All the results indicated the significant dependence of the performance of the sensor on the types of the plasmonic nanoparticles . The obtained Raman signal intensity of Ag-NPs was about 105a.u. compared with 103a.u. for Au-NPs. While, the stability of Au-NPs was much higher than that of Ag-NPs based on SERS sensors due to the normal oxidation process of Ag-NPs.

Frequency of Raised Intraocular Pressure and its Correlations to the energy used following Neodymium YAG Laser Posterior Capsulotomy in Pseudophakes

Objective: To determine the frequency of raised intraocular pressure in pseudophakic undergoing Nd YAG laser posterior capsulotomy.&#x0D; To compare the frequency of raised intraocular pressure in pseudophakic undergoing high and low energy Nd YAG laser posterior capsulotomy&#x0D; Methods: This Descriptive case series included 140 patients with pseudophakic posterior capsular opacity. After dilating the pupils with tropicamide Nd YAG laser posterior capsulotomy was performed and the total amount of energy used was noted. The frequency of raised IOP in post-laser patients and comparison of frequencies of raised IOP undergoing high and low energy Nd YAG laser posterior capsulotomies (≤ 50 MJ labeled as low energy and &gt; 50 MJ labeled as high energy) were calculated&#x0D; Results: The mean age was 57.37 ±8.74. Mean pre laser IOP was 15.15 and post-laser IOP was 17.50. The rise in IOP was normal in 82.9% and raised in 17.1%. In lower energy group normal IOP was found in 35.7% and raised in 2.9%. In a higher energy group, normal IOP was found in 47.1%, and raised IOP was found to be 14.3%.&#x0D; Conclusion: Higher the energy used during the Nd YAG laser posterior capsulotomy procedure, more is the chance of a rise in post-laser intraocular pressure as compared to those in which lesser energy was being used.

"Effect of Doping on Electrical Properties of Nickel Oxide (NPs) Prepared by Pulse Nd-Yag Laser Deposition Method "

"In this study, nickel oxide (NPs) films were produced by doping each element with 2% zinc, tin, iron, cobalt and magnesium. pulsed laser deposition was used to deposit them on glass substrates , and we used a pulsed Nd-YAG laser with a wavelength of 1064nm. All the films were annealed with one temperature (573k). The electrical properties of the prepared films were studied, such as the continuous electrical conductivity and activation energy, and we found that increasing the temperature increases the electrical conductivity values Also, the value of the electrical conductivity and the activation energy change according to the type of added doping. We also discovered many activation energy values in the temperature ranges of (308K-428K) , and observed the conduct of nanoparticle oxide doping with various metals at these temperatures.

Study the Characteristics of the nanocomposite prepared by two steps laser ablation in liquids

In the present work, structural, optical, electrical and sensing properties have been studied for the (TiO2/rGO) nanocomposite prepared by the pulse laser ablation method in the liquid, where the Nd-Yag laser was used, and the two wave pulses (1064-532) and 300mJ, which were deposited on glass bases , The structural properties have been investigated by X-Ray diffraction technique analysis and morphological by atomic force microscope (AFM), The particle size of the membranes is less in the films prepared using wavelength (1064) than in the prepared films using wavelength (532). The optical properties of the nanocomposites have been determined by using the optical transmittance measurements in the spectral region from (300- 1100) nm. Electrical properties such as I-V properties were also studied. sensing properties measurements showed good Humidity sensitivity within the range (20-80) RH.

Possibilities of using neodymium laser (ND:YAG) in gynecological practice

The article is devoted to the possibilities of using laser technologies in the treatment of urogynecological diseases on the example of the experience of doctors of the Volga district medical center of the FMBA of Russia.

Катамениальный пневмоторакс как особая форма спонтанного пневмоторакса (обзор литературы)

Spontaneous pneumothorax is a common (more than 12.5% of all urgent conditions in thoracic surgery) life-threatening condition, statistically more commonly found in men with pulmonary emphysema. However, a rare and difficult diagnostic form of spontaneous pneumothorax that develops in more than 73% of women of reproductive age with thoracic endometriosis is spontaneous catamenial pneumothorax. In the prevailing majority of patients, this pneumothorax turns out to be right-sided and recurrent in more than 70% of cases. The “gold standard” for verification of thoracic endometriosis is the visual inspection of the chest organs and biopsy using video-assisted mini-thoracotomy (VATS). The signs of thoracic endometriosis detected intraoperatively include the identification of fenestrations of the diaphragm, endometriosis of the visceral pleura, bullae of various calibers, cicatricial changes in lung parenchyma, etc. There is no consensus on the tactics of patients´ management, however, the primary importance in the treatment of thoracic endometriosis and spontaneous catamenial pneumothorax as its main manifestation should be given to surgical interventions: suturing diaphragm defects, typical (anatomical) or atypical resection of the lungs in different volumes, pleurodesis to prevent the recurrence of pneumothorax, etc. The most effective pleurodesis methods are chemical pleurodesis with sterile talc, the use of YAG-ND and CO2 lasers. Apical pleurectomy is actively used; various materials (fibrin gel, polyglycolic acid, etc.) are being studied as suture-line coverage to create aerostasis. Along with surgical methods, the use of COCs, analogues of gonadotropin-releasing hormone, danazole, progestins, and aromatase inhibitors minimizes the recurrence of spontaneous pneumothorax in patients with thoracic endometriosis.

A comparation of different strategies in Principle Component Analysis (PCA) algorithm for clustering human tooth surface using Laser-Induced Breakdown Spectroscopy (LIBS)

The aim of this work was to observe homogeneity of human tooth surface using classification technique by laser-induced breakdown spectroscopy (LIBS) coupled with principle component analysis (PCA) algorithm. The human tooth was irradiated by 110 mJ Nd-YaG laser (1064 nm) under Helium gas with flow rate of 50 ml/s to produce plasma. Photon emission of the plasma was captured by ocean optic spectrometer HR 2500+ and displayed spectra of intensity as a function of wavelength. The spectra data were analysed by different strategies in PCA algorithm for classifying human tooth surface. The spectra data were split into three ranges that were a full spectral window, FW (200-850 nm), long special spectral window, LSW (380 – 660 nm) and short special spectral window, SSW (550 – 600 nm). These selected suitable input variables using spectral windows can reduce the influence of over fitting phenomena on classification results. Prior to PCA analysing, data were treated by different strategies of pre-processing namely linear baseline correction, area normalisation, and no pre-processing. The results showed that the short special spectral window (SSW) using pre-processing of area normalization could either clustering and distinguishing parts of human tooth surface clearly. Conclusion dentin surface has highest homogeneity of all.

Novel acentric D-π-A-π-D nonlinear optical (2E, 4E)-[dimethylamino) phenyl]-1-(4methylphenyl)penta-2,4-dien-1-one crystal for second and third order nonlinear applications

A novel organic crystal namely (2E, 4E)-[dimethylamino) phenyl]-1-(4methylphenyl) penta-2, 4-dien-1-one has been grown successfully from the slow evaporation method. The single-crystal X-ray diffraction study revealed that the compound belongs to the orthorhombic crystallographic system with non-centrosymmetric P212121 space group with lattice parameters α = 7.1354(3) A, β = 11.2112(7) A and 20.0744(11) A. The thermal properties have been studied by using Thermo Gravimetric (TG) and Differential Scanning calorimetry (DSC). The second harmonic generation (SHG) efficiency of the compound is 2.9 times that of urea for Nd-YAG laser operating at wavelength 1064 nm. We also report the results of thermally induced third-order nonlinear optical (NLO) properties of NLO material investigated by Z-scan technique using continuous wave (CW) laser. The calculated values of $$ \chi_{R}^{(3)} \,({\text{esu}}) $$, $$ \chi_{i}^{(3)} \,({\text{esu}}) $$ and $$ \chi^{(3)} $$ are of the order of 10−7esu, 10−8 esu and 10−7 esu, respectively. The estimated value of the non-linear refractive index is found to be − 4.21 × 10−8 cm2/W. The compound also exhibits promising optical limiting properties at 532 nm wavelength. The synthesis and structural characterization of a new D-π-A-π-D Nonlinear Optical material namely (2E, 4E)-[dimethylamino) phenyl]-1-(4methylphenyl)penta-2,4-dien-1-one Crystal is reported. The material can be utilized for both second and third-order nonlinear applications.

Deposition of biphasic calcium phosphate film on laser surface textured Ti–6Al–4V and its effect on different biological properties for orthopedic applications

Abstract The present study reports laser surface texturing (LST) of Ti–6Al–4V using a Nd-YAG laser with a particular set of parameters and three different overlapping factors (OF): 0%, 25% and 50%. Biphasic calcium phosphate (BCP) film was deposited on bare as well as textured Ti–6Al–4V specimens by using radio frequency (RF) sputtering. The simultaneous effect of texturing as well as BCP coating on different physical and biological properties was investigated. The study revealed that the surface wettability of bare Ti–6Al–4V enhanced after laser texturing (as contact angle reduced from 89° to 71°-77°). It was further improved upon BCP deposition to make the Ti–6Al–4V superhydrophilic (contact angle ≈ 17°-21°). It was also observed that the surface roughness of bare Ti–6Al–4V significantly increased from Ra ≈ 94 nm to Ra ≈ 0.98–1.84 μm for different micro-dimpled texture substrates. The dimensions of micro-dimpled texture did not change after BCP deposition; however, a non-uniform film is deposited with increase in surface roughness. Protein adsorption was found as a function of surface hydrophobicity, which increased from 5.3 to 7.11 μg/cm2 with the rise in hydrophobicity of modified surfaces. Compared to bare Ti–6Al–4V and BCP deposited bare-Ti-6Al–4V surfaces, the BCP deposited textured surfaces exhibit higher number of well spread MG63 osteoblast cells. For the same surface chemistry, increase in surface area (roughness) improves cellular behavior. With texturing of the substrate, the cell adhered percentage and average cell area improved significantly and BCP-(50% OF)–Ti–6Al–4V was found to have the maximum cell spreading and proliferation. Overall, these findings revealed that a micro-dimpled textured surface followed by BCP film deposition strategy improved the physio-chemical properties of surfaces such as surface roughness and wettability. This in turn enhanced the bioactivity, cell adhesion and proliferation of bone cells (MG63) on modified Ti–6Al–4V surfaces and based on the results we envisage that can be potentially used for orthopedic and dental applications.

Novel method to synthesis ZnO nanostructures via irradiation zinc acetate with a nanosecond laser for photocatalytic applications

In this study, a novel method to prepare ZnO nanostructures was proposed by irradiation zinc acetate with nanosecond laser in a liquid medium. Nd-YAG laser was used with energy of 180 mJ and 6000 pulses. As well as, the effects of using various liquids such as ethanol, deionized water, and ethylene glycol on the properties of the prepared ZnO were investigated. Structural, morphological, and optical properties were studied for all samples. Specifically, the X-ray diffractometer results revealed the presence of ZnO with hexagonal crystallization. Most importantly, as indicated by micrographs of scanning electron microscopy, the laser irradiation caused the immediate growth of ZnO nanorods in aqueous solution on the contrary of nanospheres which were grown in the other used solutions. Notably, the optical properties of the prepared ZnO showed that the highest absorption was obtained by ZnO nanospheres. Meanwhile, the energy gap was also studied and found to be between 3.5 and 3.59 eV. The incorporation of all these investigations provides a clear vision for growth mechanisms. This mechanism revealed the one-step growth of ZnO nanostructures with interesting properties that prepared by laser irradiation method. The splendid properties of nanorods structures enhance the photocatalytic performance of ZnO rather than spherical structures. The photocatalyst results revealed that the maximum decomposition of 5 ppm MB by the ZnO nanorods was greater than 98% which achieved after 40 min under UV light irradiation with a fixed catalyst concentration of 12 mg / L.

10B-based films grown by pulsed laser deposition for neutron conversion applications

Solid-state neutron detectors exploit nuclear interactions producing energetic charged particles within a converter layer embedding nuclei with high neutron capture cross section and with thickness compatible with the charged particle range. Recently, boron-10 (10B) is being considered as a valid alternative to the expensive and decreasingly available 3He gas thanks to its large neutron absorption cross section and high-energy reaction products. Minimized amounts of impurities, films with optimal and well-controlled thickness, good uniformity over large areas and good adhesion to the substrates are essential to achieve efficient neutron detection performance. In this study, we present well-adherent 1-µm-thick 10B-enriched boron coatings, deposited over a large area by off-axis pulsed laser deposition (PLD) using a nanosecond Nd-YAG laser beam operating at 1064 nm and high fluence (~ 10 J/cm2), onto 1-mm-thick Al substrate as well as smooth and rough C substrates. By combining plasma plume divergence and peaked profile under off-axis deposition geometry, uniform10B films were obtained over an area of a 3.4 × 3.4 cm2. We discuss the morphological characteristics of our deposits as related to the mechanisms of nanosecond laser ablation and present energy dispersive spectroscopy (EDS) elemental analysis of the film, paying attention to the different surface features. Negligible presence of O, N and C contaminants was achieved by controlled vacuum conditions. Moreover, we present encouraging neutron detection performances of our film deposited onto Al.

Laser management for congenital dermal melanocytosis

Congenital dermal melanocytosis (CDM) is a malformation of the dermis caused by antenatal impairment of melanogenesis. There are considered data on the epidemiology, history of the study, the characteristics of the pathogenesis and clinical picture of CDM. Data on the efficacy and side effects of treatment of CDM with ruby, alexandrite and neodymium laser in children and adults are compared. The effectiveness of laser treatment for CDM is closely related to the value of the integral absorption of radiation by targeted photothermophores of the epidermis and dermis: melanin, oxyhemoglobin and reduced hemoglobin. The safety of laser exposure is determined by its selectivity, which directly depends on the ratio between the absorption of radiation by the main target photothermophores and water. For the first time, integral indices of the absorption of laser radiation in the pathological focus area by the main photothermophores of the epidermis and dermis (oxyhemoglobin, reduced hemoglobin, as well as the melanin content and localization of ectopic melanocytes in the reticular layer of the dermis) and water are presented. In the CDM involved area, the integrated coefficients of absorption by the main target photothermophores of radiation with a wavelength of 511 nm and 578 nm were shown to be much higher, and the absorption by water is much lower than for radiation with a wavelength of more than 600 nm generated by a ruby, alexandrite or neodymium laser. The described pathogenetic features of laser skin biophotonics upon exposure of the CDM region to the radiation with a wavelength of more than 600 nm increases the risk of the development of such characteristic side effects as hyperpigmentation, deterioration of the collagen structure of the dermis with subsequent formation of scars in the postradiated area. To ensure the complete elimination of ectopic melanocytes and minimize the risk of side effects during laser surgical treatment of CMD area, it is advisable to use the two-wavelengths radiation generated by the copper vapor laser: with a wavelength that is maximally absorbed by melanin (511 nm) and with a wavelength with high absorption of both oxyhemoglobin and hemoglobin (578 nm), but with negligible absorption by water.

Realization of the Radiance Scale Using Transfer Function of the Laser-Based Optical System

This work aims to determine the radiance responsivity to be used in the calibration of polychromatic radiation sources with low uncertainty. To realize the radiance, Ar-ion, He-Ne, and Nd-YAG lasers as well as an integrating sphere with a 0.15 m diameter are used to obtain radiation sources having Lambertian distributions. Then, a silicon photodiode-based reflection-type trap detector with calibrated precision aperture, which is traceable to a liquid helium cooled laser-based cryogenic radiometer, is used to measure the photocurrent corresponding to each wavelength and thereby to obtain radiance. The proposed system, which measures the spectral current response of this laser-based radiance, is a double-grating monochromator with a 2 × 300 mm focal length and triple gratings in each of its turrets. First, the radiance of the laser beam that emerged from the integrating sphere is calculated, and then the radiance responsivity of the system is obtained by measuring the photocurrent outputted from the exit slit of the monochromator at each laser wavelength. Finally, the spectral radiance values of the polychromatic lamps are obtained using the radiance responsivity of the system. Consequently, the study aims to develop the derivation and better understand traceability of the other radiometric and photometric quantities with low uncertainty from the fundamental radiometric radiance unit. Measurement results obtained in the expanded measurement uncertainty scale are determined using both classical and Monte Carlo methods.

Effects of Nd:Yag Laser on some virulence factor genes of Pseudomonas aeruginosa bacteria

The aim of this study was to assess effects of the 532nm Nd-yag laser on the genes of Tox A, Exo S, and Opr L, of Pseudomonas aeruginosa (P. aeruginosa) bacteria isolated from clinical (wounds, burns, otitis media) and environmental (water, soil) samples. Clinical samples were collected from patients coming to Saladdin General Hospital from wound, burns and middle ear infections while environmental samples were extracted from water and soil for Saladdin General Hospital . Bacterial samples irradiated by Nd-Yag laser with wavelength of 532 nm using energies (300mj,500mj) with (15 and 25 sec) and genomic DNA were extracted from all samples after the diagnosis of P. aeruginosa bacteria depending on the macroscopic and biochemical examination, then the PCR technique was performed. The results have shown an impact on P. aeruginosa bacteria of Nd-Yag laser by comparing PCR results of treated samples with control (unexposed) as loss of normal bands. This indicates that the laser had a genetic effect on the P. aeruginosa bacteria. We conclude that the laser induces genetic changes in P. aeruginosa's DNA so that lasers can be used in treatment and sterilization for clinical and environmental . The PCR technique could be used as a biomarker study to determine the biological effects of radiation on bacteria.