Laser Irradiation Conditions Research Articles

Application of Perfluorooctylbromide Nanoparticles with Ulinastatin for Early Brain Injury Caused by Carbon Monoxide Poisoning

ABSTRACTThis study aimed to explore the mechanism of perfluorooctylbromide (PFOB) nanoparticles (NPs) combined with ulinastatin (UTI) on early brain injury (EBI) caused by carbon monoxide poisoning (CMP). Firstly, PFOB NPs were prepared by high-speed dispersion and high-speed homogenization. The physicochemical characteristics of the particle size distribution and Zeta potential distribution of the NPs were analyzed using a laser particle size analyzer. The thermal and photoinduced phase transition characteristics of the NPs were analyzed under heating and laser irradiation conditions. Then, 50 Sprague Dawley (SD) rats were deemed as the research objects to establish the CMP rat models using hyperbaric oxygen chambers. According to different treatment methods, they were rolled into a healthy control group, a carbon monoxide (CO) model group, a PTOB treatment group, an UTI treatment group, and a PTOB + UTI treatment group. The brain tissues of each group of rats were collected 3 days after treatment. The neuronal cell apoptosis, expression of Caspase-3, messenger ribonucleic acid (mRNA) of inflammatory factors interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in rat brain tissue were detected through immunohistochemical staining, in situ cell apoptosis detection, Reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting, so did the relative expression of target proteins B-cell lymphoma-2 (Bcl-2), Bcl2-Associated X (Bax) and myelin basic protein (MBP). As a result, the average particle size and the average Zeta potential of the prepared PFOB NPs was 103±31 nm and −23 ± 15 mV, respectively. When the PFOB NPs were heated to 80 °C, the particle size increased greatly and cracks appeared. The particle size of PFOB NPs also increased obviously after laser irradiation, and the PFOB inside the particles changed into gas phase. Compared to CO group, expression of Caspase-3, neuronal cell apoptosis rate, mRNA expression of IL-1β and TNF-α, and protein expression of Bax and Bcl-2 in the brain tissue of PTOB group, UTI group, and PFOB + UTI group were notably decreased (P < 0.05), while the MBP protein expression increased considerably (P < 0.05). Changes in PFOB + UTI group were more obvious than those in PTOB group and UTI group, and those indicators weren’t considerably different from the controls. In summary, PFOB NPs were successfully prepared with favorable phase transition characteristics. Moreover, PFOB NPs combined with UTI could reduce the apoptosis of brain neurons after CMP, improve the inflammatory response, and play a protective effect on EBI of CMP.

Aluminum ion plasma monitored by SiC detectors from low to high laser intensity and from ns up to fs pulse duration

Thick and thin films of Al targets were irradiated in vacuum with different IR lasers at intensities between 1010 W/cm 2 and 1019 W/cm2, with pulse duration ranging between 3 ns and 45 fs. The laser-generated plasma was monitored in forward and backward directions, from thin and thick targets, by using SiC detectors, ion collectors, ion energy analyzer, optical spectrometer, Thomson parabola spectrometer and X-ray streak camera. Ion emission shows a maximum ion acceleration proportional to the laser intensity, which reaches about 1 MeV per charge state at 1016 W/cm2. Using fs laser, Al ion acceleration occurs at energies up to about 26 MeV and protons are accelerated at energies up to about 2.0 MeV.In the used experimental conditions, the maximum ion acceleration can be controlled by the laser parameters, irradiation conditions, and target geometry, such as the pulse energy, the focal position and the target thickness. Although different lasers and irradiation conditions were employed, the produced ion charges per solid angle of detection remain comparable, as it will be discussed.

Serum Protects Cells and Increases Intracellular Delivery of Molecules by Nanoparticle-Mediated Photoporation.

IntroductionIntracellular delivery of molecules is central to applications in biotechnology, medicine, and basic research. Nanoparticle-mediated photoporation using carbon black nanoparticles exposed to pulsed, near-infrared laser irradiation offers a physical route to create transient cell membrane pores, enabling intracellular delivery. However, nanoparticle-mediated photoporation, like other physical intracellular delivery technologies, necessitates a trade-off between achieving efficient uptake of exogenous molecules and maintaining high cell viability.MethodsIn this study, we sought to shift this balance by adding serum to cells during nanoparticle-mediated photoporation as a viability protectant. DU-145 prostate cancer cells and human dermal fibroblasts were exposed to laser irradiation in the presence of carbon black (CB) nanoparticles and other formulation additives, including fetal bovine serum (FBS) and polymers.ResultsOur studies showed that FBS can protect cells from viability loss, even at high-fluence laser irradiation conditions that lead to high levels of intracellular delivery in two different mammalian cell types. Further studies revealed that full FBS was not needed: viability protection was achieved with denatured FBS, with just the high molecular weight fraction of FBS (>30 kDa), or even with individual proteins like albumin or hemoglobin. Finally, we found that viability protection was also obtained using certain neutral water-soluble polymers, including Pluronic F127, polyvinylpyrrolidone, poly(2-ethyl-2-oxazoline), and polyethylene glycol, which were more effective at increased concentration, molecular weight, or hydrophobicity.ConclusionAltogether, these findings suggest an interaction between amphiphilic domains of polymers with the cell membrane to help cells maintain viability, possibly by facilitating transmembrane pore closure. In this way, serum components or synthetic polymers can be used to increase intracellular delivery by nanoparticle-mediated photoporation while maintaining high cell viability.

RETRACTED ARTICLE: ATP level in red blood cells improves by altering the low-level DPSS laser irradiation condition

The effects of DPSS laser irradiating stored blood at 405, 589, and 670 nm on the ATP levels in human red blood cells have been studied in comparison. Human blood samples were taken from healthy donors’ whole blood and stored. A DPSS laser with different wavelengths was used as a radiation source, with an output power of 10 mW and a fluence of 70 J/cm2 per irradiated sample. The CellTiter-GloLuminescent Assay kit (Promega) was used to determine ATP levels in RBCs. The blood was kept for a maximum of 20 days, and samples were evaluated on days 0, 5, 10, 15, and 20 before and after irradiation. The red blood cell ATP level was calculated by optical density using an ELISA reader to test the emission intensity. No significant differences in RBCs counts were found between pre- and post-irradiated cells at various storage periods with different laser wavelengths. In contrast, at a laser wavelength of 589 nm with storage times of 5, 10, 15, and 20 days, the RBCs had more significant differences (P < 0.05, P < 0.05, P < 0.03, P < 0.02, respectively) between pre- and post-irradiated cells. Moreover, various DPSS lasers were applied and were found to induce significant changes in ATP levels (P < 0.0003, P < 0.04, and P < 0.01, respectively). The highest increase in the ATP level (4.9%) was observed when the laser dose of 70 J/cm2 was delivered at a 589 nm wavelength. Our results clearly demonstrate that red blood cell radiation with low-power lasers of 405, 589, and 670 nm increases the ATP level in RBCs compared with their non-irradiated counterparts at various storage times. This, it is suggested that laser DPSS can cause structural transformations of the red blood cell membrane or components of the membrane.

Thermal annealing and laser-induced mechanisms in controlling the size and size-distribution of silver nanoparticles in Ag+-Na+ ion-exchanged silicate glasses

Controlled precipitation of metal nanostructures into glassy matrices have demonstrated to be a valid way to synthesize materials suitable for photonics, optoelectronics and telecom purposes. However, the development of strategies for driving nanostructure formation, and then for tailoring the optical response of the metal doped systems, is still a challenge. Aiming at this, the present study focuses on silver state modification including nucleation/growth of Ag nanoparticles (NPs), manipulation of Ag NPs size and size-distribution in Ag+-Na+ ion exchanged silicate glasses undergone post-exchange treatments, such as thermal annealing and laser irradiation with different irradiation parameters. Raman and optical absorption spectroscopy analyses allow to follow the evolution of the Ag NPs precipitation process starting from the early stages of the overall mechanism, where the glassy matrix is permeated by a dense distribution of Ag0, Ag+ and small aggregates, which are the seeds for the formation of the larger particles upon energetic treatments. In these regards, it is observed that a proper choice of laser irradiation conditions, in terms of wavelength and pulse energy, has a direct impact on the occurrence of the overall clustering process, by specifically promoting Ag ion reduction as well as cluster nucleation, growth and fragmentation. This definitely paves the way to efficient strategies for the realization of optical materials based on controlled distribution of metal clusters with finely tuned structural and optical properties.

Cold electrons acceleration in TNSA laser‐generated plasma using a low‐contrast fs laser

AbstractThe fs laser facility in Bordeaux, delivering an intensity of 1018 W/cm2 at normal incidence on thin foils, has been used to induce forward electron and ion acceleration in target‐normal‐sheath‐acceleration (TNSA) regime. Micrometric thin foils with different composition, thickness, and electron density, were prepared to promote the charge particle acceleration in the forward direction. The plasma electron and ion emission monitoring were performed on‐line using SiC semiconductor detectors in time‐of‐flight (TOF) configuration and gaf‐chromics films both covered by thin absorber filters. The experiment has permitted to accelerate electrons and protons. A special attention was placed to detect relativistic hot electrons escaping from the plasma and cold electrons returning to the target position. The electron energies of the order of 100 keV and of about 1 keV were detected as representative of hot and cold electrons, respectively. A high cold electron contribution was measured using low‐contrast fs laser, while it is less evident using high‐contrast fs lasers. The charge particle acceleration depends on the laser parameters, irradiation conditions, and target properties, as will be presented and discussed.

Rational design of a FRET-based nanoprobe of gold-conjugated carbon dots for simultaneous monitoring and disruption of Pseudomonas aeruginosa biofilm through selective detection of virulence factor pyocyanin

Fluorescent nanoprobe for detection of pyocyanin to monitor Pseudomonas aeruginosa biofilm formation.

Effect of the laser irradiation condition on surface roughness of metallic powder bed fusion

Effect of the laser irradiation condition on surface roughness of metallic powder bed fusion

High-Speed Micro-Grooving of Metal by Angled Irradiation of Single-Mode CW Fiber Laser

Laser micro-grooving has excellent potential to improve the surface properties of metals. In this study, high-speed micro-grooving of the surfaces of mild steel SS400 and aluminum alloy A1050 was investigated using a single-mode continuous-wave fiber laser with an average power of 200 W. Experiments were conducted at laser beam scanning speeds of 1 to 6 m/s. The incident angle of the laser beam in the plane perpendicular to the scanning axis was varied from 0 to 60°. A relatively deep groove (approximately 30 µm in depth) and a high upheaval (10 µm in height) were formed along the scanning line at an incident angle of 45° on the SS400, whereas only shallow grooves were formed on A1050. The micro-groove formation mechanism was discussed on the basis of high-speed camera observation, groove shapes, and the thermophysical properties of the metal. Asymmetric molten metal flow and solidification around the keyhole are thought to play important roles in micro-groove formation. Although the laser irradiation conditions must be optimized according to the thermophysical properties of the material, angled laser irradiation has the potential to effectively form micro-grooves.

Dynamic mechanical characterization of two-photon-polymerized SZ2080 photoresist

Two-photon polymerization (2PP) is a material processing technique employed for the production of high-resolution microstructures. The high potential of this technique in the fabrication of structured materials, or metamaterials, has recently attracted significant research interest. To proceed toward real applications, the mechanical properties of the material obtained by 2PP should be known. These properties depend on all the process parameters, which affect the cross-linking between the polymeric chains, and very few results are available in the literature. In this work, we perform a systematic characterization of the elastic properties of femtosecond laser-polymerized SZ2080 (hybrid organic–inorganic photoresist) by combining dynamic experimental tests and numerical simulations on properly designed microstructures. Studying the resonance frequencies of micro-cantilevers, we demonstrate the possibility of tailoring the mechanical properties of the material by changing the laser irradiation conditions. This result paves the way to the use of 2PP for the fabrication of microdevices operating in a dynamic regime with optimized material properties.

Effects of fabrication conditions on the microstructure, pore characteristics and gas retention of pure tungsten prepared by laser powder bed fusion

In this study, the effects of fabrication conditions on the microstructure, pore characteristics and gas retention of pure tungsten specimens prepared by laser powder bed fusion (LPBF) were investigated. The LPBF specimens contained micro- and nano- sized pores as internal defects. By optimizing the laser irradiation conditions, the formation of micropores was suppressed. The densest LPBF specimen was obtained when the input energy density was adjusted to be 411 J/mm3, and the relative density of the specimen measured by utilizing Archimedes' principle reached 98.58 ± 0.25% (19.03 ± 0.05 g/cm3). Heat treatment at a high temperature (1900 °C) was effective to reduce the number density of nanopores. The compositions and amounts of internal gas in the specimens were examined using a quadrupole mass spectrometer. The results indicated that the specimens contained the argon (Ar), which was used as the shielding gas. The Ar retention was correlated with the number density of nanopores in the specimens and not with the density of micropores. The Ar retention decreased to almost half that in the as-fabricated specimen after the heat treatment at 1900 °C. These observations suggest that Ar gas was trapped in nanopores in the LPBF material. It was demonstrated that a part of the trapped Ar dissolved and diffused in grains during the heat treatment and was released to the outside.

Mixing periodic topographies and structural patterns on silicon surfaces mediated by ultrafast photoexcited charge carriers

This work uses a three-dimensional mesoscopic vision and time-dynamics evolution to study silicon under ultrafast laser irradiation conditions, and shows how the crystal lattice is destabilized and turns periodically into an amorphous state.

Laser-Induced Biochar Formation through 355 nm Pulsed Laser Irradiation of Wood, and Application to Eco-Friendly pH Sensors.

Due to the limited availability of agricultural land, pH sensing is becoming more and more important these days to produce efficient agricultural products. Therefore, to fabricate eco-friendly and disposable sensors, the black carbon, which is called biochar, is formed by irradiation of a UV pulsed laser having a wavelength of 355 nm onto wood and applying the resulting material as a pH sensor. The surfaces of three types of wood (beech, cork oak, and ash) were converted to the graphitic structure after UV laser irradiation; their morphologies were investigated. In addition, since the content of lignin, an organic polymer, is different for each wood, optimal laser irradiation conditions (laser fluence) needed to form these woods into pH sensors were considered. Depending on the degree of oil-like material generated after laser irradiation, a disposable pH sensor that can be used from one to three times is fabricated; due to the environmental characteristics of wood and biochar, the sensor shows high availability in that it can be easily discarded after use on agricultural land. After that, it can be used as filter in soil. Our wood-based pH sensor sensitively measures sequential changes from pH 4 to pH 10 and shows a very linear change of △R/R, indicating its potential for use in agriculture.

Mechanical Properties of AlSi12 Alloy Manufactured by Laser Powder Bed Fusion Technique

Mechanical properties of AlSi12 alloy, which was manufactured by laser powder bed fusion (LPBF) technique, were investigated. Some basic properties of fabricated objects such as density and tensile strength were clarified. The suitable laser irradiation condition of fabricated objects that had own high relative density was showed. The microstructure of fabricated objects with as-manufactured condition was also evaluated. The fabricated objects exhibited the similar ultimate tensile strength and the Young’s modulus according to the building directions, although other mechanical properties slightly differed. Mechanical properties of fabricated objects made by reused powders also exhibited the similar values of those manufactured by unused powders. In contrast, the mechanical properties excluding the Young’s modulus of the fabricated objects, which were annealed, differed due to annealing treatment. Furthermore, the mechanical properties excluding the Young’s modulus of the fabricated objects for the designed shapes manufactured to the tensile test specimen were smaller than those of the fabricated objects machined from LPBFed rectangular block. Therefore, the attention is necessary for the mechanical design of fabricated object through LPBF technique and that with annealing treatment, because of the difference in the mechanical properties between the object built as the designed shape and the object made from LPBFed bulk product.

Initial treatment for patients with temporomandibular disorders: pain relief and muscle tone relief by photobiomodulation therapy using carbon dioxide laser

PurposeTo investigate the efficacy of photobiomodulation therapy (PBMT) with a CO2 laser (Bel Laser, Takara Belmont, CO. Ltd., Osaka, Japan; wavelength 10.6 μm) (tissue surface absorption effects) in conjunction with mouth opening training in patients with temporomandibular disorders (TMDs).MethodsThis is a retrospective study on TMD patients with pre- and post-treatment assessments. The study included 36 patients (7 men and 29 women, mean age 58.2 years (SD 18.3)) (after excluding 4 patients due to dropouts, loss to follow up or refusal of treatment) with symptoms of pain and muscle tenderness during mouth opening. Treatment included Amfenac sodium (50 mg per day, thrice daily after meals) for 1–2 weeks for acute symptoms. Based on the diagnostic criteria for TMD, we identified the trigger point (muscle contracture site). We implemented muscle massage and stretching therapy as mouth opening training after PBMT. The laser irradiance conditions were as follows: output 1.5 W, on time 0.01 s, off time 0.05 s, and repeat pulse. Distance between the laser source and the skin was approximately 10 cm; irradiation time was 3 min (approximately 56.9 J/cm2). Mouth opening training involved massaging the areas of muscle contracture that were the trigger points, as well as muscle stretching to improve temporomandibular joint flexibility. One PBMT cycle and mouth opening training was conducted per week for four cycles. We determined the effects before and after intervention. A numeric rating scale (NRS; range 0–10) was used to evaluate pain, and maximum mouth opening (MMO) capacity was also assessed. Data were analyzed using the Wilcoxon signed-rank test.ResultsThe mean (SD) pain levels, as determined via NRS, were 4.9(3.6) and 2.7 (3.0) (p < 0.001), before and after four treatment cycles, respectively. The mean (SD) of MMO was 39.6 (5.9) and 44.6 mm (4.8) (p < 0.001), before and after treatment, respectively.ConclusionThe current study suggests that PBMT using a CO2 laser combined with mouth opening training is effective for the treatment of temporomandibular disorders.

Study on the oxidation of WC-Co cemented carbide under different conditions

The oxidation of cemented carbide can affect its service performance due to the significant reduction in mechanical properties. This paper investigates the oxidation of WC-Co cemented carbide under both isothermally and laser irradiation conditions. The nanosecond pulsed laser was used to perform laser-induced oxidation in both air and pure oxygen. In comparison, the microstructures of oxide layer in laser-induced oxidation were very different to isothermal oxidation. The more porous oxide layers with spider web and cotton microstructure were observed in laser-induced oxidation. The oxide layer on material surface was stacked a small mountain shape due to the Gaussian profile of pulsed laser beam. The oxygen content curve showed a rapidly increasing trend at the beginning, and then became stable with increasing laser power.

Robust Hydroxyapatite Coating by Laser‐Induced Hydrothermal Synthesis

AbstractOwing to enhanced biocompatibility and osseointegration, hydroxyapatite (HAp) coatings are often applied to biomedical devices that are implanted directly on the bone. Although various HAp coating techniques have been developed, they are restricted due to the time‐consuming HAp synthesis and additional coating processes. Herein, the development of a rapid single‐step method for simultaneous synthesis and coating of HAp via nanosecond laser surface treatment is described. In the conventional HAp‐coating method, the resulting interface between the HAp layer and the base material is clearly distinguished. However, in this method, HAp synthesis and coating occur simultaneously via the melting of the base material (i.e., titanium, polyetheretherketone, and polycaprolactone) to form a gradient HAp‐base material composite coating layer. The resultant coating layer on a titanium surface exhibits a binding force of 31.7–47.2 N, which is sufficient for medical implant applications. Changing the laser irradiation conditions provides quantitative adjustment of the HAp formation process and coating layer thickness. Furthermore, the resulting HAp coating layer better facilitates the attachment of bone cells. These results offer a breakthrough in the surface treatment of bone‐bonding sites of metal and polymer biomedical devices.

Thermosensitive nanocomposite gel loaded zinc phthalocyanine for photodynamic therapy

The purpose of this work was first to propose a thermosensitive hydrogel incorporating Zn phthalocyanine loaded mixed micelles for drug delivery. The mixed micelles was prepared easily by dialysis method and the thermosensitive hydrogel was prepared by “cold method” using Pluronic F127 as hydrogel matrix. The properties of sol and gel transition caused by F127 temperature response enables the drug loaded micellar hydrogel(DLM-Gel) to gel in situ gelification upon injection providing long-term retention within the tumor. Sodium deoxycholate (SDC) and D-alpha tocopheryl polyethylene glycol succinate (TPGS) were utilized as micelles materials. Micelles resulted in a mean particle size around 106 nm, spherical morphology and loading efficiency up to 92%. The DLM-Gel displayed a three-dimensional network structure, which helps to stabilize ZnPc molecules because it can reduce the rotation and intermolecular collision of the ZnPc molecules, leading to the enhancement of fluorescence intensity and 1O2 generation. The production of 1O2 from DLM-Gel was more efficient than micelles under the same laser irradiation condition. The DLM-Gel was more photostable than free ZnPc and micelles in the timescale typically used in photodynamic therapy(PDT), only a small photobleaching event(16.91%) was observed after 20 min of light irradiation. Rheology studies demonstrated that DLM-Gel has the potential to be injected at room temperature and to adapt to the deformation of surrounding tissues during human motion. The in vitro drug release studies of DLM-Gel demonstrated slower drug release than mixed micelles. Phototoxicity experiments in A549 cells showed that DLM-Gel had significante toxicity.Therefore the injective micellar hydrogels is a potential drug delivery system for PDT.

Surface modification by high-speed laser gas carburization in low-alloy steel

Carburization of steels is a widely used industrial technique; however, a long processing time is generally required for this process. Herein, laser irradiation in low-alloy steel in a propane gas atmosphere was conducted using equipment that comprises a plastic chamber. This method is a novel laser carburization technique conducted in the liquid-phase-free temperature range. By controlling the laser irradiation conditions, the material could be carburized at a temperature of ~1500 K, which is difficult to achieve using conventional carburizing equipment. This method substantially reduced the processing time, i.e., promoted high-speed carburization.

Unidirectional Crystal Orientation of Dual-Phase Ni3Al-Based Alloy via Laser Irradiation

Dual-phase Ni3Al-based alloys feature extensive applicability even under high-temperature conditions. We selectively modified the microstructure of a representative dual-phase Ni3Al-based alloy from equi-axed grains to unidirectional grains, using a kW-class high-power laser irradiation technique. On employing the laser probe to linearly scan the Ni-9 at.% Al-16 at.% V alloy specimen, the laser-irradiated region was partially molten and then immediately solidified from the two edges of the molten pool toward the center. Laser irradiation under low-speed scanning increased the molten pool width. The grains in the laser-irradiated region extended preferentially from the two edges toward the center; their crystal orientation was similar to adjacent substrate grains, suggesting epitaxial growth. Therefore, the unidirectional orientation of grains could be extended via wide-range scanning using laser irradiation. This suggests that the microstructure of the alloy can be selectively modified to unidirectional orientated grains by optimizing laser irradiation conditions, such as the power density, scanning speed, and scanning paths. The hardness of the laser-irradiated region decreased due to the phase transformation from the ordered Ni3Al and Ni3V phases to the disordered fcc phase. However, the hardness improved to a value comparable to that of the alloy subjected to heat treatment at 980 °C for 1 h.