Laser Irradiation Time Research Articles

The biothermal analysis of a human eye subjected to exponentially decaying laser radiation under the dual phase-lag heat conduction law

In this paper, a biomathematical model of the human eye subjected to an exponentially decaying laser concerning the change in blood perfusion, porosity, evaporation rate, and ambient temperatures, has been constructed based on dual phase-lag (DPL) heat conduction law. The human eye has been divided into six layers. Appropriate boundary and interface continuity conditions have been considered. A separable function has been assumed, and twelve equations have been formulated in a matrix form. The solutions have been calculated by using MAPLE. The results have been shown in figures with different cases. The absolute temperature distribution based on various values of the power density of laser irradiation and relaxation times parameters have been discussed first. The effect of the porosity, evaporation rate, time, and ambient temperatures have also been discussed. The power density of laser irradiation, porosity, evaporation rate, time, and ambient temperatures have significant effects on the temperature passing through the human eye layers.

The Thermal Behavior Analysis of a Human Eye Subjected to Laser Radiation Under the Non-Fourier Law of Heat Conduction

Abstract Purpose: The physiological conditions and environment have vital roles in the heat transfer in the human tissues, such as the multilayered human-eye. In this paper, a mathematical model of the human eye subjected to an exponential laser beam concerning the change in blood perfusion, porosity, evaporation rate, and ambient temperatures has been constructed based on non-Fourier heat conduction law. Methods: The human eye has been divided into six layers. Appropriate boundary and interface conditions have been considered. A separable function has been assumed, and the twelve equations have been formulated in matrix form. The solutions have been calculated by using maple 17 software. Results: The results have been shown in figures with different cases. The absolute temperature distribution based on various values of the power density of laser irradiation and relaxation times parameters have been discussed first. The effect of the blood perfusion, porosity, evaporation rate, time, and ambient temperatures have also been discussed. Conclusions: The power density of laser irradiation, blood perfusion, porosity, evaporation rate, time, and ambient temperatures significantly affects the value of the temperature passing through the human eye layers.

Thermal response during volumetric ablation of carbon fiber composites under a high intensity continuous laser irradiation

The phenomenon of volumetric ablation of carbon fiber composites by a continuous high power density laser was investigated theoretically and numerically. The main goal of this study was to investigate the thermal responses of the heat shields of re-entry vehicles in the extreme thermal environment. The composite was considered as a homogenized block in geometry. And a one-dimensional transient model was proposed. The laser power density varied from 50W/cm2 to 500W/cm2 and the laser irradiation time varied from 0 to 5 s. During volumetric ablation, the composite could be separated into three zones: the virgin zone, the pyrolysis zone and the char zone. It was found that a higher laser power density led to a smaller pyrolysis zone. The peak pressure of pyrolysis gases in the composite appeared in the region with a low degree of pyrolysis reaction, which had a significantly low porosity and permeability. When the initial porosity of the composite was low, a small amount of gas generation might lead to a high gas pressure, causing mechanical failure of the composite. And the magnitude of the peak pressure decreased quickly with the initial porosity increasing. Therefore, the porous structure and the honeycomb sandwich structure used inside of the composite should decrease the internal gas pressure to prevent the material from mechanical damage. The simulation result of this study was helpful for the design of high temperature thermal protection systems.

Research on multivariate nonlinear regression model of specific energy of rock with laser drilling based on response surface methodology

Based on Box–Behnken Design of response surface methodology, multiple experiments of laser drilling (four centimeters thickness of sandstone) were performed by continuous fiber laser (Model MFSC) with a maximum laser power 1 kW to obtain the specific energy of rock with three experimental parameters of laser power (400∼800 W), irradiation time (6∼10 s) and spot diameter (0.01∼0.03 m). According to experimental results, a multivariate nonlinear mathematical regression model correlating the experimental parameters with the specific energy of rock was established and the accuracy of the model was found to be good by variance analysis. Univariate analysis of the model revealed that laser power had the greatest influence on the specific energy of rock, while irradiation time affected the least. Considering the interaction effect among three experimental parameters, calculation results of the model exhibited that the combination of laser power and irradiation time, as well as that of laser power and spot diameter, had obvious influence on the specific energy of rock, while the combination of irradiation time and spot diameter showed little effect. After that, the optimal parameter combination (P=768.9 W, t=8.3 s, d=0.01 m) was obtained. Five repeated experiments under the optimal parameter combination clearly illustrated good agreement between predicted values and measured values. This paper proposed a multivariate nonlinear model based on the response surface method with high precision in predicting the specific energy of rock, which could help reduce the specific energy of rock and improve the efficiency of rock breaking.

Fabrication of microstructures by picosecond laser

Microstructures assume crucial role in preparation of functional surfaces, such as self-cleaning, anti-icing and drag reduction. In the paper, picosecond laser is used for the fabrication of the microstructures by the balanced photothermal and photochemical action. In order to improve the controllability of structural dimensions, we reported on fabrication of smooth swelling by picosecond laser irradiation of two-layer substrate. The upper layer is swelling doped PMMA; the lower layer is black acrylic. This work first obtained different microlines by tuning the scanning speed through focusing on the interface. Then, different swelling structures were fabricated by adjustment of laser irradiation time. Further, the dependence of swelling morphology on irradiation time and laser power were studied. For the different swellings, the microlens array was obtained by replication and the imaging performance was tested. This demonstrated the possibility of the method for preparation of the microlens array and other functional microstructures.

Effect of pulsed laser irradiation on the thermal diffusivity of bimetallic Au/Ag nanoparticles

Bimetallic Au/Ag nanoparticles have been synthesized by laser ablation technique using a pulsed Nd:YAG laser with fundamental wavelength of 1064 nm. Initially, gold nanoparticles were synthesized in PVP solution by the ablation technique. For the generation of bimetallic Au/Ag nanoparticles, a silver plate was ablated for different time durations in the already synthesized colloidal gold nanoparticle solution. These source samples were further subjected to pulsed laser irradiation using a Q-switched frequency doubled Nd:YAG laser at a wavelength of 532 nm for varying time periods. Formation of the bimetallic nanoparticles was confirmed by Transmission Electron Microscopy (TEM) as well as absorption spectroscopy. Stability of the samples was established by the zeta potential analysis. Thermal diffusivity of the samples was determined using a dual-beam mode matched thermal lens technique at two different pump wavelengths. A systematic increase in the thermal diffusivity values was observed with increase in the ablation time of silver plate in gold nanoparticle solution which is attributed to the morphological variations occurring to the bimetallic nanoparticles. The effect of laser irradiation on the thermal diffusivity values was also investigated. An increase in thermal diffusivity was observed as the laser irradiation time increased due to the agglomeration of the bimetallic nanoparticles. The study can act as the basis for using plasmonic bimetallic nanoparticles as a nanoheat source in the medical field applications.

Laser Irradiation of Super-Nonwettable Carbon Soot Coatings–Physicochemical Implications

Accounting the increasing commercial need of rational strategies for passive icing and anti-microbial protection, the development of simple, time-efficient and scalable laboratory micropatterning techniques is highly desirable. Whilst the laser irradiation is an acknowledged technology for rapidly tuning the properties of any carbon allotropes, including soot aerosols, very barely is known about the impact of the laser beam on the physicochemical profile of the soot if it appears as a functional coating. In this pioneering research, the prolonged laser treatment of a super-nonwettable soot coating actuates morpho-chemical transformations in the material, depending on the laser power and irradiation time, without interfering its anti-wetting capability and optical transmittance. Our observations could be used as a foundation for facilitating the launch of soot coatings with customized anti-icing and anti-microbial performance.

Preparation of Cu2ZnSnS4 nanoparticles by laser ablation in liquid and characterization

Cu2ZnSnS4 (CZTS) nanoparticles were successfully prepared by laser ablation in liquid. CZTS powders were irradiated with nanosecond-pulsed laser (Nd:YAG, second harmonic generation) to prepare nanoparticles. The primary particle size of prepared nanoparticles was decreased with the increase in laser fluence, and the decrease was saturated around 11 nm. The secondary particle size of them was increased with the increase in laser fluence because aggregation would proceed. A by-product such as Cu2–xS was created by this method, and the amount was increased with laser fluence and irradiation time.

Improved High-Performance Solution Processed In₂O₃ Thin Film Transistor Fabricated by Femtosecond Laser Pre-Annealing Process

The low-temperature annealing process has a critical impact on the electrical performance of thin-film transistors (TFTs). This paper reports significant performance enhancements of TFTs using a femtosecond laser pre-annealing (FLA)-based preparation method. The solution-processed In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> films were fabricated by FLA at various laser irradiation times and then annealed on a hot-plate at 230 °C. When the FLA time was set to 30 s, the device exhibited high saturation mobility of 10.03 ± 0.64 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs, I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> of 3.4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> , low V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> of 0.14 ± 0.64 V, and small SS of 1.44 ± 0.37 V/dec. The FLA process improved the formation of M-O lattices effectively, which led to an improvement in mobility. Furthermore, the gate-bias-stress stability and time-dependent environmental stability were improved considerably by the FLA process. These results show that high-performance In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> TFTs can be prepared at low temperatures using FLA-centered annealing technology. This work suggests that the FLA preparation method has tremendous potential for the fabrication of low-cost, high performance, and flexible TFT devices.

Plasmon-enhanced nanosoldering of silver nanoparticles for high-conductive nanowires electrodes

The silver nanowires (Ag NWs) electrodes, which consist of incompact Ag nanoparticles (NPs) formed by multi-photon photoreduction, usually have poor conductivities. An effective strategy for enhancing conductivity of the Ag NWs electrodes is plasmon-enhanced nanosoldering (PLNS) by laser irradiation. Here, plasmon-enhanced photothermal effect is used to locally solder Ag NPs and then aggregates of these NPs grow into large irregular particles in PLNS process. Finite element method (FEM) simulations indicate that the soldering process is triggered by localized surface plasmon-induced electric field enhancement at “hot-spots”. The effectiveness of PLNS for enhancing conductivity depends on laser power density and irradiation time. By optimizing the conditions of PLNS, the electrical conductivity of Ag NWs is significantly enhanced and the conductivity <em>σ</em>_s is increased to 2.45×10⁷ S/m, which is about 39% of the bulk Ag. This PLNS of Ag NWs provides an efficient and cost-effective technique to rapidly produce large-area metal nanowire electrodes and capacitors with high conductivity, excellent uniformity, and good flexibility.

One-step fabrication of regular hierarchical micro/nano-structures on glassy carbon by nanosecond pulsed laser irradiation

Fabrication of hierarchical micro/nano-structures on glassy carbon (GC) surface is important for the application of GC as the mold material for glass molding, but it is still challenging due to the high brittleness and hardness of the material. In this study, by using a nanosecond pulsed laser, a hierarchical micro/nano-structure, i.e., micro-dimple with ring-like nanostructure on its inner wall, was generated on the GC surface. The effects of laser parameters, such as laser irradiation time and fluence, on the formation and evolution of the hierarchical micro/nano-structure were experimentally studied. By comparative experiments with graphite, the role of amorphous nature of GC on the formation of very regular hierarchical micro/nano-structure was confirmed. The results obtained by irradiating GC in argon and nitrogen gas further indicated that the formation of hierarchical micro/nano-structure was independent of the gas atmosphere. By controlling the relative positions of point shots, various micro-dimple arrays were successfully fabricated on the GC surface which significantly changed its wetting behavior. Finally, formation mechanism of the hierarchical micro/nano-structure was discussed according to the experimental results as well as some previous literatures. This study provides a one-step method for fabricating hierarchical micro/nano-structures on the GC surface by nanosecond pulsed laser irradiation, which would be meaningful for the functional applications of GC.

Phase Control of MoTe2 Synthesized Via Laser Annealing Process: A Non-Transfer, Fast and Patternable Approach

Layared materials such as graphite and transition metal dichalcogenides have attracted lots of attention owing to their unusal nature of reacing atomic thickness. These so-called two-dimensional materials reveal outstanding physical properties when their thickness reduce to mono layer, such as indirect to direct bandgap transition for TMDs, which is ideal for different kinds of potential applications in optoelectronics, energy harvesting, Li-ion batteries and supercapacitors. Among the numorous TMDs, MoTe2 is the only TMD which can be synthesized in two phases because of the small energy difference between them. However, the synthesis approach to control these two phases is not refined enough. Most reliable strategy is CVD process, but its require high temperature annealing for a long time while control the Te atomphere at the same time. These complicated process is hard to applied and high temperature also restrict the use of substrates. Therefore, further improvement of the synthesis methods is an important issue. Here, we use a laser approach to induce the MoTe2 growth directly on different substrates such as Quartz and sapphire and so on. We control the two phases by tuning the laser power and irradiation time. TEM supported by Raman and X-ray Photoelectron Spectroscopies confirm the existence and quality of the synthesized films. Furtheremore, this approach can be extended to the synthesis of other TMDs. The laser annealing assisted method develops a new approach that is fast, cheap, patternable and does not require transfer giving a step forward on the technology development for practical applications.

(Invited) Laser-Assisted Exfoliation of Black Phosphorus with Thickness Control for Li-Ion Batteries

Few-layer black phosphorus (BP) is an emerging two-dimensional (2D) material with exciting properties such as tunable bandgap and high charge carrier mobility, which make it a suitable candidate for energy storage applications. However, its preparation remains challenging. Currently, the exfoliation of bulk crystal to its few-layer form assisted by liquid-phase exfoliation (LPE) process using ultrasonic agitation is commonly adopted, which is time-consuming and suffers low efficiency and lack of morphologic control. In this study, we demonstrate a highly-efficient route for the scalable production few-layer BP nanosheets using a pulsed laser in low-boiling point solvents. By adjusting the laser irradiation time and solvent type, the morphology (layer number and lateral size) of the few-layer BP nanosheets is tuned with a narrow distribution (layer number from 3 to 13, lateral size from <2 µm to >5 µm). The laser-assisted exfoliation is understood by a plasma quenching mechanism and interlayer interaction weakened by the in situ generated vapor bubbles. The fine control of thickness and lateral size of the BP nanosheets enables us to study their impact on Li-ion battery performance when applied as anode material. We present herein the correlation of the layer number and larger lateral size of BP with the electronic conductivity, Li+ ion transfer rate and diffusivity, as well as long-term cyclability, revealing the morphology-dependent battery performance. Figure 1

Size-controlled in situ synthesis of metal–polymer nanocomposite films using a CO2 laser

In situ synthesis of metal–polymer nanocomposite films by irradiating a CO2 laser for several seconds is a new alternative to fabricate metal–polymer nanocomposite films. The main features of this method are that the number density of the synthesized metal nanoparticles is very high so that the optical density easily exceeds 0.5 ~ 1.5 for the film thickness of ~ 200 nm, and owing to the short fabrication time and the use of non-focused laser beam, large-scale processing is possible. For this technique to be applicable for a variety of purposes, an important question is how and how much we can control the film properties. In this work, we demonstrate that the size and size distribution of metallic nanoparticles in the synthesized nanocomposite films can be well controlled by the choice of the laser power and irradiation time as well as the concentrations of nanoparticle precursor. Properties of the synthesized films can be roughly understood by considering the diffusion of metallic ions, atoms, and nanoparticles in the polymer film under the elevated temperature induced by the CO2 laser.

Coupling between laser irradiation and TiO2 nanoparticles on efficient decontamination of some pesticide's residues from orange and tomato puree

In this paper, we focused on the development of photocatalytic degradation to be a promising method for the treatment of decontaminated fruits and vegetables with pesticides. We investigate the coupling between Laser irradiation with TiO2 nanoparticles catalyst in order to study the photocatalytic degradation of metalaxyl, chlorpyrifos, and diazinon from artificially contaminated tomato puree and orange puree. Degradation products were identified by gas chromatography-mass spectrometry (GC–MS). The influences of different parameters such as catalyst concentration, irradiation time on the reaction rate were ascertained and optimum conditions for maximum degradation were determined. The degradation percentage of all pesticides was achieved under optimized conditions (1g/L catalyst at the irradiation time of 120 min). The study proved that the coupling between TiO2 nanoparticles and laser irradiation has a high potential for photocatalytic degradation of diazinon, chlorpyrifos, and metalaxyl from orange puree and tomato puree. And also, proved that the efficient degradation of pesticide residues increased with an increase in laser irradiation time (for 60 min) and catalyst (TiO2nanoparticles) dosage in all experiments. Maximum reduction >80% was observed in diazinon in all puree treatments. The processing factor (PFs) was generally less than one which indicates that all processes can reduce pesticide residues in all puree treatments. The less efficient removal of pesticides residues from all treatments without Laser irradiation (dark TiO2100mg) We concluded that the optimum conditions for the photodegradation of diazinon, chlorpyrifos, and metalaxyl in all puree treatments were TiO2100mg catalyst concentration and after 60 min of laser irradiation.

Folic Acid-Functionalized Composite Scaffolds of Gelatin and Gold Nanoparticles for Photothermal Ablation of Breast Cancer Cells.

Photothermal therapy (PTT) has been developed as a useful therapeutic method for cancer treatment. Localization of PTT agents in cancer sites and targeting capacity are required to further increase therapeutic efficacy. In this study, gold nanoparticles (AuNPs) and gelatin were functionalized with folic acid (FA) and hybridized to prepare FA-functionalized gelatin–AuNPs composite scaffolds. AuNPs with rod and star shapes of three sizes (40, 70, and 110 nm) were used for the hybridization to investigate the influence of AuNPs shape and size. The composite scaffolds showed porous structures with good interconnectivity. Modification with FA increased capture capacity of the composite scaffolds. Hybridization with AuNPs rendered the composite scaffold a good photothermal conversion property under near-infrared (NIR) laser irradiation. Temperature change during laser irradiation increased with the laser power intensity and irradiation time. The shape and size of AuNPs also affected their photothermal conversion property. The composite scaffold of gold nanorods 70 (FA-G/R70) had the highest photothermal conversion capacity. Breast cancer cells cultured in the FA-G/R70 composite scaffold were killed under NIR laser irradiation. Mouse subcutaneous implantation further demonstrated the excellent photothermal ablation capability of FA-G/R70 composite scaffold to breast cancer cells. The FA-functionalized composite scaffolds were demonstrated a high potential for local PPT of breast cancer.

IJU this issue

This issue contains 15 Original Articles, three of which are excellent prospective clinical trials, and one Urological Note. Cabozantinib is a multiple receptor tyrosine kinase inhibitor targeting MET (c-MET), VEGFR2, RET, AXL, KIT and TIE-2. In the phase III, randomized, open-label METEOR study, cabozantinib was associated with a significant progression-free survival benefit and a greater objective response rate versus everolimus in patients with metastatic renal cell carcinoma who had progressed after VEGFR-TKI. Tomita et al. (Niigata, Japan) carried out a bridging study to METEOR to evaluate the efficacy and safety of cabozantinib in Japanese patients. This phase II, open-label, single-arm study showed that cabozantinib provided clinical benefits in Japanese patients with renal cell carcinoma, with similar efficacy and safety to the non-Japanese population. Medical lasers are increasingly used to treat benign prostatic hyperplasia. Shoji et al. (Isehara, Japan) carried out a randomized prospective study to compare functional outcomes and complications over a period of 12 months in benign prostatic hyperplasia treated with thulium laser enucleation of the prostate or bipolar transurethral resection of the prostate. This study showed that thulium laser enucleation of the prostate is superior to bipolar transurethral resection of the prostate in resected volume, resected rates per prostate volume and transition zone volume, hemostasis, catheterization and hospitalization time, and decrease in prostate-specific antigen. However, excessive laser irradiation time in thulium laser enucleation of the prostate has the possibility to delay improvement of overactive bladder symptoms and decrease sexual function. Loose seeds and stranded seeds are available for low-dose rate brachytherapy. Each method has its own advantages and disadvantages, such as flexibility and fixation. Tanaka et al. (Kashihara, Japan) carried out a randomized controlled trial to compare the post-implant dosimetric parameters between the conventional method (using only the loose seeds) and the hybrid method. This study showed that the hybrid method of low-dose rate brachytherapy can achieve a higher coverage of the periprostatic region compared with the conventional method, while maintaining an acceptable level of urethral and rectal doses. The intravesical recurrence rate after transurethral resection of bladder tumor carried out for non-muscle-invasive bladder cancer (NMIBC) is high, and some risk factors for recurrence have been identified. Sazuka et al. (Chiba, Japan) evaluated the risk of the residual urine volume and preoperative pyuria in intravesical recurrence after transurethral resection of bladder tumor among NMIBC patients. They found that the presence of residual urine and pyuria raised the risk of intravesical recurrence after transurethral resection of bladder tumor for NMIBC. Furthermore, especially in men, the recurrence-free survival was significantly higher in patients without than with residual urine by propensity score matching analysis. Iwasawa et al. (Tokyo, Japan) investigated the relationship between fluid intake and tumor recurrence in NMIBC patients by using urine-specific gravity as an indicator of daily fluid intake. They found that high urine-specific gravity was associated with tumor recurrence, especially in patients not receiving adjuvant bacillus Calmette–Guérin therapy. This showed that increasing fluid intake might prevent recurrence in relatively low-risk NMIBC patients. Testicular microlithiasis (TM) is a relatively rare condition occurring in the testicular parenchyma that is characterized by multiple bright and small foci without acoustic shadow limited to the testicle on scrotal ultrasonography. TM is a characteristic of testicular dysgenesis syndrome and was shown to be associated with infertility. Hiramatsu et al. (Tokyo, Japan) evaluated the correlation between the degree of severity in TM and several factors. This study showed the prevalence of TM in normal healthy Japanese men who are trying for first-time pregnancy. This also showed that men with TM might have poor semen findings, and that men with severe TM might have even worse semen parameters. None declared.

Simulation and experimental study of laser-induced thermal deformation of spectral beam combination grating.

The multilayer dielectric (MLD) grating is a critical device for combining multiple laser beams into a single beam in a spectral beam combining (SBC) system. We established a theoretical thermal deformation model of the laser-irradiated MLD grating. Thermal deformation on the surface of the grating is simulated according to a series of parameters including the laser irradiation time, laser power density, and substrate size. To verify the model, we exposed a 960 l/mm, 50×50×1.5 mm3 grating to a laser power density of 3.61 kW/cm2 and observed the temperature change. We used a Twyman-Green interferometer to measure the interference fringes on the grating surface. Based on the Fourier-transform method and a Zernike polynomial fitting method, the real-time grating surface profile is reconstructed. The results show that substrate thickness increase or area decrease can reduce thermal deformation, the average decreases are 18.3% and 19.9%, respectively. The discussion and analysis of the grating thermal deformation are potentially valuable for designing grating to decrease the thermal deformation and improve the combined beam quality of a SBC system.

In vitro effect of antimicrobial photodynamic therapy with phycocyanin on Aggregatibacter actinomycetemcomitans biofilm on SLA titanium discs.

The aim of this in vitro study was to evaluate antimicrobial photodynamic therapy (aPDT) with phycocyanin on Aggregatibacter actinomycetemcomitans biofilm formed on sandblasted, large-grit, and acid-etched (SLA) titanium discs. In this in vitro experimental study, the minimum inhibitory concentration (MIC), sublethal dose of diode laser irradiation time, and sublethal dose of aPDT were first determined. Next, 30 SLA titanium discs with 8 mm diameter and 2 mm thickness were incubated with A. actinomycetemcomitans in order for the bacterial biofilm to form, and were randomly divided into 5 groups (n = 6): (I) negative control with no treatment, (II) positive control, immersed in 0.2 % chlorhexidine (CHX) for 5 min, (III) phycocyanin alone with ×2 MIC concentration for 5 min, (IV) diode laser alone (635 nm wavelength, 220 mW power), and (V) PDT with diode laser and phycocyanin. The samples were then sonicated, and the number of colony-forming units (CFUs) on each disc was calculated. Data were analyzed using one-way ANOVA, t-test, and a post-hoc test. aPDT with 125 μg/mL phycocyanin and 4 min irradiation of 635 nm diode laser decreasedA. actinomycetemcomitans biofilm by 40.07 %. The lowest mean colony count (CFUs/mL) was noted in 0.2 % CHX group (0.0 × 105 CFU/mL) while the highest mean was observed in the negative control group (4.55 ± 0.08 × 105 CFUs/mL). Using phycocyanin alone significantly decreased the A. actinomycetemcomitans count by 27.54 % (3.29 ± 0.06 × 105 CFUs/mL) compared with the negative control group (P < 0.0001). Significant differences were noted between the negative control and other groups (P < 0.0001). aPDT with phycocyanin and diode laser can decrease the A. actinomycetemcomitans biofilm on SLA titanium implant surfaces and can be used as a safe and non-invasive decontamination method for reduction of A. actinomycetemcomitans biofilm on implant surfaces.

Experimental study of laser pyrolysis of coal and residual oil

A lab-scale laser pyrolysis platform was set up to study the pyrolysis of coal and residual oil to light gases combining high accuracy, good repeatability and ultra-high temperature, fast heating rate. With a high-power CW CO2 laser used as heat source, the laser pyrolysis took place as a procedure-controlled reaction process connected with a specially designed GC to analyze the gas products on line. The temperature of samples was measured by a two-color infrared pyrometer in milliseconds time-step, and the measured ultimate temperature and heating rate exceeded 2900 K and 3 × 104 K/s respectively. Through a series of experiments, the accuracy and reliability of the laser pyrolysis platform are verified and the effects of sample weight, environmental atmosphere, laser irradiation time and power, hydrogen content in atmosphere on the yields of gas products were investigated. The appropriate operating conditions are: the weight of residual oil less than 1.0 mg, the laser irradiation time longer than 3.0 s, laser irradiation power stronger than 90 W. The relationship between laser pyrolysis and plasma pyrolysis processes has also been discussed in this work. This work established an efficient, easy-to-use method for the preliminary feedstock selection of plasma pyrolysis process because C1 + C2 yield from laser pyrolysis could be used as a criterion for plasma pyrolysis.