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The additive manufacturing is a free-form metal deposition process, which allows generating a prototype or small series of near net-shape structures. Despite numerous advantages, one of the most critical issues of the technique is that produced pieces have a deleterious surface quality which requires post machining. Besides conventional post processes such as turning, milling, or photo-chemical etching, laser processes are increasingly being used for surface finishing of metals. In this study, a hybrid laser polishing technique consisting of nanosecond pulsed laser material removal and continuous wave (CW) laser polishing was utilized to polish the laser directed energy deposition (LDED) Ti-6Al-4 V samples. To account for this, the effect of hybrid laser polishing on the surface modification of LDED Ti-6Al-4 V alloy has been investigated. The surface morphology, microstructure evolution, and mechanical properties of the as-fabricated, the pulsed laser material removal processed, and the hybrid laser polishing processed samples were investigated. The results revealed that hybrid laser polishing not only eliminates the unmelted particles, oxides, and defects of as-fabricated Ti-6Al-4 V but also reconstructs the surface morphology, which improved the surface roughness by 98.32%. After hybrid laser polishing, the average thickness of the remelted layer has increased to 85 μm, while the acicular martensite α´ grows epitaxially from the substrate across the layer bands. Additionally, due to the formation of α′ martensite, the microhardness is about 21.02% higher than LDED Ti-6Al-4 V sample. The wear rate is decreased from 1.36 × 10−3 to 0.86 × 10−3 mm3/N·m, which was reduced by 38.23% compared to the as-fabricated. [ABSTRACT FROM AUTHOR]

Addressing the challenge of breaking rocks deep within the earth requires innovative solutions, and the pulsed laser technology has emerged as a promising noncontact alternative for rock breaking. We developed an automated experimental platform with robotic arms and a rock mechanics testing device to quantitatively study the impact of laser technology on rock breaking. Our investigation delved into the damage caused to rocks by different types of lasers, focusing on understanding their underlying damage mechanisms. Pulsed lasers, excluding thermal effects, reduced the red sandstone strength by 68.07%, with a decrease in peak tensile force by 30-33 N per 1000 pulses. Furthermore, we conducted detailed quantitative analyses to understand how laser power (P), irradiation duration, and output energy affeted rock damage. Increasing laser power or irradiation duration enhanced rock damage since this increased the laser output energy. For every 100.00 W power increase, the peak force decreased by 51.00-88.00 N, and for every 1000.00 ms duration increase, the peak force decreased by 34.00-42.00 N. Maintaining constant output energy while changing the laser power revealed a quadratic nonlinearity in peak force, aiding in determining optimal laser parameters. This study highlights the potential of laser technology for effective rock fracturing during deep earth exploration. The established experimental platform improves the accuracy and reliability of laser-induced rock breaking, offering insights for future advancements in this field. [ABSTRACT FROM AUTHOR]

Nowadays, the development of devices based on organic materials is an interesting research challenge. The performance of such devices is strongly influenced by material selection, material properties, design, and the manufacturing process. Usually, buckminsterfullerene (C60) is employed as electron transport material in organic photovoltaic (OPV) devices due to its high mobility. However, considering its low solubility, there have been many attempts to replace it with more soluble non-fullerene compounds. In this study, bulk heterojunction thin films with various compositions of zinc phthalocyanine (ZnPc), a perylene diimide derivative, or C60 were prepared by matrix-assisted pulsed laser evaporation (MAPLE) technique to assess the influence of C60 replacement on fabricated heterostructure properties. The investigations revealed that the optical features and the electrical parameters of the organic heterostructures based on this perylene diimide derivative used as an organic acceptor were improved. An increase in the JSC value (4.3 × 10−4 A/cm2) was obtained for the structures where the perylene diimide derivative acceptor entirely replaced C60 compared to the JSC value (7.5 × 10−8 A/cm2) for the heterostructure fabricated only with fullerene. These results are encouraging, demonstrating the potential of non-fullerene compounds as electron transport material in OPV devices. [ABSTRACT FROM AUTHOR]

The current strategy for treating osteomyelitis includes surgical procedures for complete debridement of the formed biofilm and necrotic tissues, systemic and oral antibiotic therapy, and the clinical use of cements and three-dimensional scaffolds as bone defect fillers and delivery systems for therapeutic agents. The aim of our research was to formulate a low-cost hybrid nanoparticulate biomaterial using poly(lactic-co-glycolic acid) (PLGA), in which we incorporated the therapeutic agent (ciprofloxacin), and to deposit this material on titanium plates using the matrix-assisted pulsed laser evaporation (MAPLE) technique. The deposited material demonstrated antibacterial properties, with all analyzed samples inhibiting the growth of tested bacterial strains, confirming the release of active substances from the investigated biocomposite. The poly(lactic-co-glycolic acid)-ciprofloxacin (PLGA-CIP) nanoparticle scaffolds displayed a prolonged local sustained release profile over a period of 45 days, which shows great promise in bone infections. Furthermore, the burst release ensures a highly efficient concentration, followed by a constant sustained release which allows the drug to remain in the implant-adjacent area for an extended time period. [ABSTRACT FROM AUTHOR]

In the field of precision machining, with the popularity of brittle and hard materials such as infrared windows, it has become difficult for conventional diamond grinding wheels to effectively perform high-quality machining. The structuring of traditional diamond grinding wheels using a pulsed laser is a key technology to effectively improve the grinding quality of grinding wheels. In this paper, three new shark fin diamond grinding wheels (SFSGW) with different slot widths are designed based on the excellent drag-reducing and channelizing properties of shark dorsal fins. The grinding performance of traditional grinding wheels (USGW) and SFSGW on magnesium fluoride ceramics was compared. The effects of SFSGW on the surface quality, surface roughness and wheel damage of the workpiece were investigated. The results showed that the surface roughness of ceramics after grinding by SFSGW was reduced by 22.15 % compared with USGW, and the surface quality was better. Proper construction increases the material removal rate of the wheel and improves the wear resistance and service life of the wheel. [ABSTRACT FROM AUTHOR]

We introduce a method utilizing single laser-generated cavitation bubbles to stimulate cellular mechanotransduction in dermal fibroblasts embedded within 3D hydrogels. We demonstrate that fibroblasts embedded in either amorphous or fibrillar hydrogels engage in Ca2+ signaling following exposure to an impulsive mechanical stimulus provided by a single 250 µm diameter laser-generated cavitation bubble. We find that the spatial extent of the cellular signaling is larger for cells embedded within a fibrous collagen hydrogel as compared to those embedded within an amorphous polyvinyl alcohol polymer (SLO-PVA) hydrogel. Additionally, for fibroblasts embedded in collagen, we find an increased range of cellular mechanosensitivity for cells that are polarized relative to the radial axis as compared to the circumferential axis. By contrast, fibroblasts embedded within SLO-PVA did not display orientation-dependent mechanosensitivity. Fibroblasts embedded in hydrogels and cultured in calcium-free media did not show cavitation-induced mechanotransduction; implicating calcium signaling based on transmembrane Ca2+ transport. This study demonstrates the utility of single laser-generated cavitation bubbles to provide local non-invasive impulsive mechanical stimuli within 3D hydrogel tissue models with concurrent imaging using optical microscopy. Currently, there are limited methods for the non-invasive real-time assessment of cellular sensitivity to mechanical stimuli within 3D tissue scaffolds. We describe an original approach that utilizes a pulsed laser microbeam within a standard laser scanning microscope system to generate single cavitation bubbles to provide impulsive mechanostimulation to cells within 3D fibrillar and amorphous hydrogels. Using this technique, we measure the cellular mechanosensitivity of primary human dermal fibroblasts embedded in amorphous and fibrillar hydrogels, thereby providing a useful method to examine cellular mechanotransduction in 3D biomaterials. Moreover, the implementation of our method within a standard optical microscope makes it suitable for broad adoption by cellular mechanotransduction researchers and opens the possibility of high-throughput evaluation of biomaterials with respect to cellular mechanosignaling. [Display omitted] [ABSTRACT FROM AUTHOR]

We report an application of a pulsed ultraviolet (UV) laser (λ = 355 nm) in producing translucent Si solar cells. This process efficiently generates a densely packed microhole array on a fully fabricated Si P‐N junction solar cell in just a few minutes. Herein, prototype cells with a nominal microhole diameter of 23 μm with a spacing between 60 and 300 μm are fabricated. High‐resolution electron‐beam microscopy reveals that the UV laser beam introduces amorphized silicon oxide (SiOx) in proximity to the patterned microholes via localized heating in air. Quantitative photovoltaic (PV) analysis shows a decline in the open‐circuit voltage (Voc) and the fill factor (FF) of the cells with the increase in the microhole density, likely due to the P‐N junction damage during the laser beam irradiation. Despite the reduction in Voc and FF, the solar cells retain a short‐circuit current density (Jsc) above 90% without post‐processing. The inherent microhole geometry associated with the laser beam profile allows multiple light scattering within the confined microhole structure, enhancing the translucency of the cells. While further development is required for optimization, these findings support the potential use of UV laser beams for fast and scalable production of translucent solar cells. [ABSTRACT FROM AUTHOR]

The generation of pressure perturbations in matter stimulated by pulsed light is a method widely recognized as the photoacoustic or light‐induced thermoelastic effect. In a series of psychophysical experiments, the robustness of the tactile perception generated with a variety of light sources is examined: a diverging pulsed laser used for photoacoustic tomography optical parameter oscillation (OPO), a miniature diode laser (MDL), and a commercial digital light processing (DLP) projector. It is demonstrated that participants can accurately detect, categorically describe the sensations, and discern the direction of pulsed light travel. High detection accuracy is reported as follows: (d′ = 4.95 (OPO); d′ = 2.78 (modulated MDL); d′ = 2.99 (DLP)) of the stimulus on glabrous skin coated with a thin layer of dye absorber. For all light sources, the predominant sensation is felt as vibration at the distal phalanx (i.e., fingertip, 55.21–57.29%) and the proximal phalanx (41.67–44.79%). At the fingertip, thermal sensations are perceived less frequently than mechanical ones. Moreover, these haptic effects are preserved under a wide range of pulse widths, spot sizes, optical energies, and wavelengths of the light sources. This form of sensory stimulation demonstrates a generalizable non‐contact, non‐optogenetic, in situ activation of the mechanosensory system. [ABSTRACT FROM AUTHOR]

In this work, the nonlinear optical (NLO) properties of CuO nanoparticles (CuO NPs) were studied experimentally using the pulsed laser ablation (PLA) technique. A nanosecond Nd: YAG laser was employed as the ablation excitation source to create CuO NPs in distilled water. Various CuO NPs samples were prepared at ablation periods of 20, 30, and 40 min. Utilizing HR-TEM, the structure of the synthesized CuO NPs samples was verified. In addition, a UV–VIS spectrophotometer was used to investigate the linear features of the samples. The Z-scan technique was utilized to explore the NLO properties of CuO NPs samples, including the nonlinear absorption coefficient (β) and nonlinear refractive index ( n 2 ). An experimental study on the NLO features was conducted at a variety of excitation wavelengths (750–850 nm), average excitation powers (0.8–1.2 W), and CuO NPs sample concentrations and sizes. The reverse saturable absorption (RSA) behavior of all CuO NPs samples differed with the excitation wavelength and average excitation power. In addition, the CuO NPs samples demonstrated excellent optical limiters at various excitation wavelengths, with limitations dependent on the size and concentration of CuO NPs. [ABSTRACT FROM AUTHOR]

Halide perovskite materials have garnered significant research attention due to their remarkable performance in both photoharvesting photovoltaics and photoemission applications. Recently, self-assembled CsPbBr3 superstructures (SSs) have been demonstrated to be promising lasing materials. In this study, we report the ultrastable two-photon-pumped amplified stimulated emission from a CsPbBr3 SS/Ag hybrid microcavity with a low threshold of 0.8 mJ/cm2 at room temperature. The experimental results combined with numerical simulations show that the CsPbBr3 SS exhibits a significant enhancement in the electromagnetic properties in the hybrid microcavity on Ag film, leading to the uniform spatial temperature distribution under the irradiation of a pulsed laser, which is conducive to facilitate the recrystallization process of the QDs and improve their structural integrity and optical properties. This study provides a new idea for the application of CsPbBr3/Ag hybrid microcavity in photonic devices, demonstrating its potential in efficient optical amplification and upconversion lasers. [ABSTRACT FROM AUTHOR]

Recent progress has seen multiple Ta2O5 polymorphs generated by different synthesis techniques. However, discrepancies arise when these polymorphs are produced in widely varying thermodynamic conditions and characterized using different techniques. This work aimed to characterize and compare Ta2O5 particles formed at high and low temperatures using nanosecond pulsed laser ablation (PLA) and continuous wave (CW) laser heating of a local area of tantalum in either air or an 18O2 atmosphere. Scanning electron microscopy (SEM) and Raman spectroscopy of the micrometer-sized particles generated by PLA were consistent with either a localized amorphous Ta2O5 phase or a similar, but not identical, crystalline β-Ta2O5 phase. The Raman spectrum of the material formed at the point of CW laser impingement was in good agreement with the previously established ceramic "H-Ta2O5" phase. TEM and electron diffraction analysis of these particles indicated the phase structure matched an oxygen-vacated superstructure of monoclinic H-Ta2O5. Further from the point of laser impingement, CW heating produced particles with a Raman spectrum that matched β-Ta2O5. We confirmed that the high-temperature ceramic phase characterized in previous work by Raman spectroscopy was the same monoclinic phase characterized in different work by TEM and could be produced by direct laser heating of metal in air. [ABSTRACT FROM AUTHOR]

Accurate three-dimensional spatiotemporal distribution information on near-surface aerosols is of great significance for environmental research. In this study, a 3D scanning coaxial Mie lidar (3D-STML) was developed to achieve a fast three-dimensional scanning observation of aerosol diffusion processes in near-surface areas. 3D-STML generates high-spatiotemporal resolution images of aerosol extinction coefficient in real-time and captures the dynamic changes of aerosols in near real-time. By optimizing the design of the light guide mirror and the telescope sub-mirror, the system has a small overlap. Based on this, a highly stable and high-speed mechanical rotation mechanism was developed to enable three-dimensional observations. The integration of a solid-state high-repetition-rate pulsed laser and a coaxial, optical system for the transmitter and receiver ensures rapid tracking of aerosol plumes. To meet the observation requirements of near-surface aerosols, an aerosol inversion algorithm combining the Fernald and Klett methods was designed and developed. For aerosol plume monitoring needs, an aerosol plume-tracking algorithm based on Kalman filtering was developed to track the spatiotemporal evolution of aerosols automatically. Experimental results demonstrated that 3D-STML is capable of detecting aerosols in a range from 15 m to 4 km, with a distance resolution of 1.5 m and a time resolution of 0.083 s. It can effectively track and capture aerosol plumes. It can be used for large-scale, long-term observation of near-surface aerosols and for monitoring the spatiotemporal evolution of aerosol plumes. [ABSTRACT FROM AUTHOR]

In recent years, academic research on perovskite solar cells (PSCs) has attracted remarkable attention, and one of the most crucial issues is promoting the power conversion efficiency (PCE) and operational stability of PSCs. Generally, modification of the electron or hole transport layers between the perovskite layers and electrodes via surface engineering is considered an effective strategy because the inherent structural defects between charge carrier transport layers and perovskite layers can be reshaped and modified by adopting the functional nanomaterials, and thus the charge recombination rate can be naturally decreased. At present, large amounts of available nanomaterials for surface modification of the perovskite films are extensively investigated, mainly including nanocrystals, nanorods, nanoarrays, and even colloidal quantum dots (QDs). In particular, as unique size-dependent nanomaterials, the diverse quantum properties of colloidal QDs are different from other nanomaterials, such as their quantum confinement effects, quantum-tunable effects, and quantum surface effects, which display great potential in promoting the PCE and operational stability of PSCs as the charge carriers in perovskite layers can be effectively tuned by these quantum effects. However, preparing QDs with a neat and desirable size remains a technical difficulty, even though the present chemical engineering is highly advanced. Fortunately, the rapid advances in laser technology have provided new insight into the precise preparation of QDs. In this review, we introduce a new approach for preparing the QDs, namely pulsed laser irradiation in colloids (PLIC), and briefly highlight the innovative works on PLIC-prepared QDs for the optimization of PSCs. This review not only highlights the advantages of PLIC for QD preparation but also critically points out the challenges and prospects of QD-based PSCs. [ABSTRACT FROM AUTHOR]

Many of the CM carbonaceous chondrites are regolith breccias and so should have abundant evidence for collisional processing. The constituent clasts of these fragmental rocks frequently display compactional petrofabrics; yet, olivine microstructures show that most CMs are unshocked. To better understand the reasons for this contradiction, we have sought other evidence for hypervelocity impact processing of CM chondrites using the Cold Bokkeveld meteorite. We find that this regolith breccia contains rare particles of vesicular shock melt that are close in chemical composition to bulk CM chondrite. Transmission electron microscopy of a melt bead shows that it is composed of silicate glass with inclusions of pentlandite, pyrrhotite, and wüstite. Characterization of shards of another bead by atom probe tomography reveals nanoscale clusters of sulfur that represent sulfide inclusions arrested at an early stage of growth. These glass particles are mineralogically comparable to micrometeoroid impact melt described from the Cb‐type asteroid Ryugu and melt that has been experimentally produced by pulsed laser irradiation of CM targets. The glass could have formed by in situ shock‐melting, but petrographic evidence is more consistent with an origin as ballistic ejecta from a distal impact. The scarcity of melt in this meteorite, and CM chondrites more broadly, is consistent with the explosive fragmentation of hydrous asteroids following energetic collisions. Cold Bokkeveld's parent body is likely to be a second‐generation asteroid that was constructed from the debris of one or more earlier bodies, and only a small proportion of the reaccreted material had been highly shocked and melted. [ABSTRACT FROM AUTHOR]

Although immunogenic cell death (ICD) induced by lysosomal membrane permeabilization (LMP) evidently enhance the effectiveness of antitumor immunity for triple-negative breast cancer (TNBC) with poor immunogenicity, their potential is increasingly restricted by the development of other death pathways and the repair of lysosomes by endoplasmic reticulum (ER) during LMP induction. Herein, a polydopamine nanocomposite with i-motif DNA modified and BNN6 loaded is prepared toward boosting LMP and immunotherapy of TNBC by synergy of spatially confined photoacoustic (PA) effects and nitric oxide. Combining the high-frequency pulsed laser (4000 kHz) with the intra-lysosomal assembly of nanocomposites produced spatially confined and significantly boosted PA effects (4.8-fold higher than the individually dispersed particles extracellular), suppressing damage to other cellular components and selectively reducing lysosomal integrity to 19.2 %. Simultaneously, the releasing of nitric oxide inhibited the repair of lysosomes by ER stress, causing exacerbated LMP. Consequently, efficient immune activation was achieved, including the abundant releasing of CRT/HMGB1 (5.93–6.8-fold), the increasing maturation of dendritic cells (3.41-fold), and the fostered recruitment of CD4+/CD8+ T cells (3.99–3.78-fold) in vivo. The study paves a new avenue for the rational design and synergy of confined energy conversion and responsive nanostructures to achieve the treatment of low immunogenicity tumors. A strategy of boosting lysosomal membrane permeabilization (LMP) and concomitantly preventing the repair was developed to address the immunotherapy challenge of triple-negative breast cancer. Spatially confined and significantly enhanced photoacoustic (PA) effects were achieved through DNA-guided pH-responsive assembly of polydopamine nanocomposites in lysosomes and application of a high-frequency pulsed laser. Efficient immunogenic cell death was guaranteed by selective and powerful damage of lysosomal membranes through the significant contrast of PA intensities for dispersed/assembled particles and nitric oxide release induced endoplasmic reticulum stress. The study paves a new avenue for the rational design and synergy of confined energy conversion and responsive nanostructures to achieve the treatment of low immunogenicity tumors. [Display omitted] [ABSTRACT FROM AUTHOR]

Background. Facial angiofibromas (FAs) are a dermatological characteristic which are typically linked to tuberous sclerosis (TS). Aim. We discuss our experience, highlighting a rare occurrence of multiple FAs in a young patient, successfully treated with ablative CO2 laser combined with PDL therapy. Methods. A 23‐year‐old male patient affected by TS who presents multiple erythematous and colored papules/nodules located on the face, mainly concentrated around nose, perinasal area, cheeks, and chin area, was treated with a combination of ablative CO2 laser and a pulsed dye laser. The patient underwent 3 sessions of combined treatment with CO2 and pulsed dye laser. The intralesional dye laser treatment was administered immediately after the CO2 laser session. The time interval between the combined laser treatments was approximately two months. Results. After 4 months from the last laser treatment session, most of the facial erythematous and protruding lesions had improved. Following these procedures, the patient did not experience complications or severe adverse reaction. Conclusion. The combined use of the CO2 and dye laser has been proved to be a safe and effective treatment for multiple FAs in the young patient affected by tuberous sclerosis. [ABSTRACT FROM AUTHOR]

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman–Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam. [ABSTRACT FROM AUTHOR]

In this study, silicon carbide nanoparticles (NPs) were produced via pulsed laser ablation in liquid, aiming to investigate the influence of processing parameters on the properties of the resultant NPs and their applicability for inkjet printing. The results revealed an increase in NP concentration with increasing laser power, but the maximal absorbance in the case of 0.743 and 1.505 W is lower than that for 1.282 W laser. Dynamic light scattering was employed to determine the size distribution of the NPs, demonstrating a range of 89 to 155 nm in diameter. Notably, an inverse relationship was established between increasing laser scanning speed and pulse repetition rate (PRR) and the mean size of the NPs. Higher PRR and laser power exhibited an augmentation in the concentration of NPs. Conversely, an increase in scanning speed resulted in a reduction in NP concentration. Based on FTIR, data formation of SiC NPs based on the target material is the most dominant behavior observed followed by an amount of oxidation of the NPs. Examination of the resulting NPs through field emission scanning electron microscopy equipped with energy-dispersive X-ray analysis (EDX) unveiled a predominantly spherical morphology, accompanied by particle agglomeration in some cases, and the elemental composition showed silicon, carbon, and some oxygen present in the resulting NPs. Furthermore, the modulation of colloidal solution viscosity was explored by incorporating glycerol, yielding a maximal viscosity of 10.95 mPa·s. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive study on the impact of irradiation optical fiber cores with a femtosecond-pulsed laser, operating at a wavelength of 1030 nm, on the signal amplitude in Rayleigh scattering-based optical frequency domain reflectometry (OFDR). The experimental study involves two fibers with significantly different levels of germanium doping: the standard single-mode fiber (SMF-28) and the ultra-high numerical aperture fiber (UHNA7). The research findings reveal distinct characteristics of reflected and scattered light amplitudes as a function of pulse energy. Although different amplitude changes are observed for the examined fibers, both can yield an enhancement of amplitude. The paper further investigates the effect of fiber Bragg grating inscription on the overall amplitude of reflected light. The insights gained from this study could be beneficial for controlling the enhancement of light scattering amplitude in fibers with low or high levels of germanium doping. [ABSTRACT FROM AUTHOR]

Facial redness in atopic dermatitis (AD) is often intractable due to factors like chronic inflammation, steroid-induced telangiectasia, and rosacea-like dermatitis from topical treatments. Pulsed-dye laser (PDL) effectively treats both vascular and non-vascular inflammatory conditions, but its use in adult AD is limited. This study presents three cases of refractory AD with significant facial erythema treated with PDL. Two women and one man had undergone five to thirteen PDL treatments at 3 weeks to 3-month intervals. Clinical response was evaluated using the Eczema Severity Score, which showed significant improvement after PDL treatments. Our cases explore the efficacy of PDL in treating refractory facial erythema in adult AD patients. Patients tolerated the procedures well without severe complications such as hyperpigmentation, hypopigmentation, or blister formation. These findings suggest that PDL effectively reduces facial redness and alleviates associated AD symptoms. PDL is expected to address both vasodilation and cutaneous inflammation as an adjunctive therapy to manage refractory facial redness in adult AD. Further cases and research are needed to fully understand PDL's immunomodulatory effects. [ABSTRACT FROM AUTHOR]

Surface hydroxyls (OH) are crucial for heterogeneous catalysis in water. However, they are commonly characterized at solid–gas interfaces (e.g., FTIR, XPS, TGA), which may not represent the surface in aqueous environments. Here, the surface OH of five catalytically relevant oxides (Al2O3, ZrO2, TiO2, Fe2O3, Co3O4) are quantified by substituting them with F− ions at pH 3–10, where the surface fluoride (F) density is evaluated by XPS using the geometry factor for spherical particles. These results show that the surface F density peaks at around pH 4 across all oxides, but decreases at more basic pH due to increased OH− competition. Generally, oxides more abundant in surface OH can also accommodate more surface F, establishing F− ions as effective probes. While terminal F are likely the preferential substitution product, bridging F also appear to form at lower pH levels. Furthermore, fluoride substitution is applied to a series of Co3O4 gradually enriched with defects using pulsed laser defect engineering in liquid (PUDEL). This approach reveals a linear correlation between laser processing and surface OH density, which aligns with a previously observed improvement in OER activity, and is supported by additional DFT calculations here. This work will stimulate further studies adopting fluoride substitution to better understand the relationship between surface chemistry and catalytic processes in aqueous environments. [ABSTRACT FROM AUTHOR]

Epsilon tungsten trioxide (ε-WO 3) has drawn much attention for its unique gas sensing and ferroelectric properties. However, the strong metastability of ε-phase makes it extremely difficult to stabilize the phase at room temperature. For a long time, it was believed that the ε-phase can only be stabilized by rapid solidification processing. In this study, ε-WO 3 was stabilized by employing solvothermal synthesis and subsequent annealing, with the help of Cr- and Ti-dopants. Structural characterization using XRD, Raman and TEM analysis revealed that the as-annealed powders are a mixture of ε-WO 3 and γ-WO 3 and the fraction of ε-WO 3 is directly correlated with the Cr- and Ti-doping levels. Rietveld refinement suggests that the maximum obtainable fractions of ε-phase in as-annealed WO 3 are ∼68 % for Cr-doping and ∼87 % for Ti-doping. The growth mechanism is that solvothermal synthesis produced Cr- and Ti-doped W 18 O 49 and subsequent annealing resulted in phase transition from W 18 O 49 to ε-WO 3. The XPS analysis reveals the phase stabilization mechanism to involve the interstitial sites of WO 3 being occupied by Cr3+ and Ti4+ dopants, resulting in structure distortions. The fraction of ε-WO 3 can be further improved to almost 100 % by introducing kinetic constraints using pulsed laser irradiation to rapidly melt and solidify the WO 3 (in several milliseconds). A viable solvothermal synthesis route for ε-WO 3 and the feasibility to produce ε-phase via additive manufacturing are illustrated in this work. [ABSTRACT FROM AUTHOR]

High-power lasers play an important role in modern science, industry, and medicine. A significant milestone was reached on 5 December 2022, when Inertial Confinement Nuclear Fusion (ICF) achieved scientific breakeven, releasing more energy than the input laser energy. Additionally, Extreme Ultraviolet Lithography (EUVL) has enabled the development of microchips with 3 nm process nodes, marking a leap in semiconductor technology. These examples, together with the recent achievement of 10 PW (1015 W) laser output, herald remarkable advancements in technology and science. Laser systems are broadly classified based on their operating regimes into two main categories: Continuous Wave (CW) operation, where the laser is continuously pumped and emits a steady beam of light, and the pulsed regime, in which the laser produces single or multiple pulses at various repetition rates. This review will primarily focus on pulsed laser systems, exploring their various types and recent technological advancements. [ABSTRACT FROM AUTHOR]

Remote detection of trace explosives and hazardous chemicals has been an ongoing challenge and a critical issue in defense science, public safety, and counterterrorism. Raman spectroscopy, a form of inelastic scattering, acts as a "fingerprint" analysis method for substance identification with high confidence in the detection of chemicals based on their vibrational modes. Here, we present a portable stand-off time-gated Raman spectroscopy, which consists of a passive Q-switched pulsed laser, a designed gated ICMOS, a spectrometer, and a telescope, with an overall size of 476.5 × 321.5 × 219.3 mm and a weight of 23.2 kg, which is much more compact and portable than reported previously. To confirm the effectiveness of the designed portable time-gated Raman spectroscopy, detections at different working distances and various amounts of substances are carried out. High levels of Raman identification are acquired even for 0.1 mg at a 10-m distance. Furthermore, we simulate realistic encounters in a possible war-zone scenario by testing the system's ability to recognize urea samples on different substrates such as an aluminum plate, woodblock, cardboard, black cloth, and leaf; good characteristic recognition is shown. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Pulsed dye laser (PDL) has proven effective in resolving lupus miliaris disseminatus faciei (LMDF) where drug therapies have failed with a lack of treatment consensus for LMDF, considering early PDL intervention is crucial to achieve resolution without scarring, prevent relapse, and enhance overall treatment outcomes. Lupus miliaris disseminatus faciei (LMDF) is a rare inflammatory and granulomatous dermatologic disease that primarily affects the face. The optimal treatment for LMDF remains controversial, and there is a lack of consensus on the most effective therapy. This case report highlights the successful use of a 595 nm pulsed dye laser (PDL) in the treatment of LMDF following unsuccessful drug therapy. A 28‐year‐old male presented with reddish‐brown eruptions on his face that had persisted for several months. Clinical examination revealed discrete dome‐shaped eruptions in clusters on the central area of the face. Histopathological examination confirmed the diagnosis of LMDF, based on the presence of epithelioid granulomas with central caseous necrosis. Previous treatment with an oral isotretinoin and methotrexate combination also failed to yield satisfactory results. After discontinuing drug therapy, the patient underwent five sessions of PDL treatment. Ten days after the first session, the eruptions began to regress without scarring. Subsequent PDL sessions led to the complete resolution of the eruptions. The patient experienced no relapse during the follow‐up period. This case report suggests that PDL treatment may be an effective option for LMDF, particularly in cases where drug therapy has failed. Early initiation of laser treatment may prevent scarring, minimize the adverse effects associated with drug therapy, and reduce the risk of disease relapse. Further research and controlled trials are needed to establish the efficacy of laser therapy in the treatment of LMDF. [ABSTRACT FROM AUTHOR]

The Keck‐PAD (pixel array detector) was developed at Cornell as a burst‐rate imager capable of recording images from successive electron bunches (153 ns period) from the Advanced Photon Source (APS). Both Si and hole‐collecting Schottky CdTe have been successfully bonded to this ASIC (application‐specific integrated circuit) and used with this frame rate. The facility upgrades at the APS will lower the bunch period to 77 ns, which will require modifications to the Keck‐PAD electronics to image properly at this reduced period. In addition, operation at high X‐ray energies will require a different sensor material having a shorter charge collection time. For the target energy of 40 keV for this project, simulations have shown that electron‐collecting CdTe should allow >90% charge collection within 35 ns. This collection time will be sufficient to sample the signal from one frame and prepare for the next. 750 µm‐thick electron‐collecting Schottky CdTe has been obtained from Acrorad and bonded to two different charge‐integrating ASICs developed at Cornell, the Keck‐PAD and the CU‐APS‐PAD. Carrier mobility has been investigated using the detector response to single X‐ray bunches at the Cornell High Energy Synchrotron Source and to a pulsed optical laser. The tests indicate that the collection time will meet the requirements for 77 ns imaging. [ABSTRACT FROM AUTHOR]

Heat flux is an important parameter to be considered for the field of the optimization of thermal protection to maintain the hot-end component's long lifetime and stability under extreme working environments. For accurately detecting the rapidly changing heat flux under the working state, the atomic layer thermopile (ALTP) heat flux sensor with highly time-resolved characteristic could be one of the most potential means. However, the traditional ALTP heat flux sensor is almost based on the sensitive film with inclined c -axis epitaxial growth on the single crystal substrate to generate the transverse thermoelectric effect. The large size and millimeter thickness of the ALTP heat flux sensor based on the single crystal substrate limits the assembly on the heteromorphic surface of hot-end components. In this article, the flexible ALTP heat flux sensor was successfully fabricated on the unoriented Hastelloy C-276 tape by the introduction of the controlled inclined c -axis MgO template via the Inclined Substrate Deposition method. The shadowing effect caused by the different substrate inclined angles led to the inclined c -axis orientation growth of MgO, and La 1-x Ca x MnO 3 (LCMO) sensitive film was epitaxially grown on MgO film with a cube-on-cube-type arrangement through the MOCVD system. Under the radiation of the pulsed laser, the response time of the LCMO film based on the flexible substrate increases from 108 ns to 248 ns with the increasing inclined angle of the c -axis, and the fast response characteristic of the sensitive film can still maintain in the bending state. When the substrate inclined angle is 30°, the sensor represents a sensitivity of 2.81 μV/(kW/m2). After a 20-day stability test, the flexible heat flux sensor has stable sensitivity showing the stability of the ALTP heat flux sensor. Those results will lay a foundation for the subsequent application of the ALTP heat flux sensor on the irregular surface. [ABSTRACT FROM AUTHOR]

Herein, the efficiently high‐power pulsed Raman lasers with wavelength above 2.1 μm are experimentally demonstrated relying on the stimulated Raman scattering. A tailored high‐power noise‐like pulse (NLP) fiber laser system centered at ≈1953 nm with a maximum output power of ≈10.9 W is served as the pump source. By directly pumping a section of highly Ge‐doped silica fiber, the first pulsed Raman laser (centered at≈2139 nm) and the second pulsed Raman laser (centered at ≈2353 nm) with maximum output powers of ≈3.8 and ≈0.25 W are obtained, respectively, which represent the highest output powers of NLP at these wavelength regions, to the best of knowledge. Moreover, a high spectral purity of ≈94.3% of the first Raman laser is obtained, which indicates the significantly potential application of NLP in pulsed Raman laser. The midinfrared NLP fiber laser source will have potential applications in transparent polymer materials processing and midinfrared spectroscopy. [ABSTRACT FROM AUTHOR]

As devices become more miniaturized and integrated, the heat flux density has increased, highlighting the issue of heat concentration, especially for low thermal conductivity gallium oxide (Ga2O3). This study utilizes diamond composite substrates with an AlN transition layer to assist Ga2O3 in rapid thermal dissipation. All samples were prepared using pulsed laser deposition (PLD) and annealed at 600–1000 °C. The microstructure, surface morphology, vacancy defects, and thermal characteristics of post-annealed Ga2O3 were then thoroughly investigated to determine the mechanism by which annealing temperature influences the heat transfer of heterostructures. The results demonstrate that increasing the annealing temperature can improve the crystallinity of Ga2O3 while also reducing oxygen vacancy defects from 20.6% to 9.9%. As the temperature rises to 1000 °C, the thermal conductivity of Ga2O3 reaches a maximum of 12.25 W/(m·K). However, the interface microstructure has no direct correlation with annealing temperature. At 700 °C, Ga2O3/diamond exhibits a maximum thermal boundary conductance of 127.06 MW/(m2·K). Higher temperatures (>800 °C) cause irregular mixtures to form near the heterointerface, intensifying phonon interface scattering and sharply deteriorating interfacial heat transfer. These findings contribute to a better understanding of the heterointerface thermal transfer influence mechanism and provide theoretical guidance for the thermal management design and physical analysis of Ga2O3-based power devices. [ABSTRACT FROM AUTHOR]

In order to study the mechanism of microcrack generation in the process of pulsed laser polishing of zirconia ceramics and the influence of laser polishing process parameters on the surface temperature and surface stress, this paper establishes a finite element computational model of pulsed laser polishing of zirconia ceramics based on the COMSOL Multiphysics multi-physics field simulation software. Firstly, in the process of establishing the finite element model, the temperature field and stress field coupling is used to analyze the temperature field and stress field changes during the laser polishing process, which reveals the microcrack generation mechanism and size characteristics of zirconia ceramics in the process of pulsed laser polishing. Secondly, through parameterized scanning, the variation rules of surface temperature and surface stress were studied under different process parameters of laser power, scanning speed, pulse frequency and pulse width. Finally, the validity of the finite element calculation model is verified by the pulsed laser polishing zirconia ceramics experiment. The results show that, in a certain energy range, the high-energy laser beam can effectively reduce the surface roughness of the material, and with the increase in the time of laser action on the surface layer of the material, it will cause the temperature and thermal stress of the surface layer of the material to continue to accumulate, and when the stress value exceeds the yield limit of the material, cracks will form in the surface layer of the material; because the laser power, scanning speed, pulse frequency and pulse width are used to affect the laser energy density, and then, the pulse width will be affected by the process parameters of the laser energy density, and thus the surface temperature and thermal stress of the surface layer of the material. Because the laser power, scanning speed, pulse frequency and pulse width all affect the thermal stress on the material surface by influencing the laser energy density acting on the material surface, the laser energy density is the main influencing factor of the dimensional characteristics of the microcracks. In addition, the microcrack width and depth will increase when the laser energy density acting on the material surface layer increases. [ABSTRACT FROM AUTHOR]

As the fatigue properties of as-built components of additively manufactured (AM) metals are considerably weaker than those of wrought metals because of their rougher surface, post-processing is necessary to improve the fatigue properties. To demonstrate the improvement in the fatigue properties of AM metals via post-processing methods, the fabrication of AlSi10Mg, i.e., PBF–LS/AlSi10Mg, through powder bed fusion (PBF) using laser sintering (LS) and its treatment via submerged laser peening (SLP), using a fiber laser and/or a Nd/YAG laser, was evaluated via plane bending fatigue tests. In SLP, laser ablation (LA) is generated by a pulsed laser and a bubble is generated after LA, which behaves like a cavitation bubble that is referred to as "laser cavitation (LC)". In this paper, LA-dominated SLP is referred to as "laser treatment (LT)", while LC collapse-dominated SLP is referred to as "laser cavitation peening (LCP)", as the impact of LC collapse is used for peening. It was revealed that SLP using a fiber laser corresponded with LT rather than LCP. It was demonstrated that the fatigue strength at N = 107 was 85 MPa for LCP and 103 MPa for the combined process of blasting (B) + LT + LCP, whereas the fatigue strength of the as-built specimen was 54 MPa. [ABSTRACT FROM AUTHOR]

The present work utilizes Direct Laser Interference Patterning (DLIP) to impart periodic microstructures onto the surface of nickel foils. A pulsed laser source emitting green radiation (514 nm) with pulse duration between 282 fs and 1 ps is utilized to produce line and cross-like pattern geometries having a spatial period of 3.0 µm and a maximum structure depth of ~ 2.8 µm. Both the pulse duration and number of consecutive scans are varied in order to assess their influence on the structure formation. Afterwards, the treated Ni- electrodes are used for alkaline water electrolysis. The most active electrode exhibits an overpotential of -227 mV at a current density of -0.5 A cm-2 for the Hydrogen Evolution Reaction (HER). Thus, the technique here proposed permitted a 51 % reduction in the overpotential of the HER compared to the untreated Ni-electrode, opening up possibilities for the development of more efficient electrodes for hydrogen production. [ABSTRACT FROM AUTHOR]

6005A aluminum alloy is widely used in the railway industry due to its excellent performance. Paint removal from the railway surface is an important step in the repair process. Compared with continuous laser that damages the substrate and low efficiency of pulsed laser, compound laser can achieve efficient paint removal. In this study, paint removal from the surface of 6005A aluminum alloy was performed using a combination of continuous and pulsed fiber lasers. When delay time was 0.4 s, the maximum paint thickness reduction of one single machining was 93 μm, which was 22.4% better than single laser efficiency. Performance tests on the surface of 6005A aluminum alloy substrate showed that, when delay time was 0.4 s, the minimum surface roughness was 1.04 μm and the ablation of paint from the substrate surface was observed by electron microscopy. There were no obvious changes in grain size after compound laser paint removal. The contact angle of the substrate surface after compound laser paint removal was 87.3° on average, which was 13.4% less than the original surface. It was more hydrophilic to make it easier to repaint. This research provided the theoretical foundation for the application of compound laser in railway paint removal. [ABSTRACT FROM AUTHOR]

Short-pulsed lasers can treat dermal pigmented lesions through selective photothermolysis. The irradiated light experiences multiple scattering by the skin and is absorbed by abnormal melanosomes as well as by normal blood vessels above the target. Because the fluence is extremely high, the absorbed light can cause thermal damage to the adjacent tissue components, leading to complications. To minimize radiant exposure and reduce the risk of burns, a model of the melanosome-disruption threshold fluence (MDTF) has been developed that accounts for the light-propagation efficiency in the skin. However, the light-propagation efficiency is attenuated because of multiple scattering, which limits the extent to which the radiant exposure required for treatment can be reduced. Here, this study demonstrates the principle of melanosome disruption with localized thermal damage through a turbid medium by ultralow radiant exposure of a short-pulsed laser. The MDTF model was combined with a wavefront-shaping technique to design an irradiation condition that can increase the light-propagation efficiency to the target. Under this irradiation condition, melanosomes were disrupted at a radiant exposure 25 times lower than the minimal value used in conventional laser treatments. Furthermore, almost no thermal damage to the skin was confirmed through a numerical simulation. These experimental and numerical results show the potential for noninvasive melanosome disruption and may lead to the improvement of the safety of short-pulsed laser treatment. [ABSTRACT FROM AUTHOR]

Neuromodulation is a powerful tool for fundamental studies in neuroscience and potential treatments of neurological disorders. Both photoacoustic (PA) and photothermal (PT) effects are harnessed for non‐genetic high‐precision neural stimulation. Using a fiber‐based device excitable by a nanosecond pulsed laser and a continuous wave laser for PA and PT stimulation, respectively, PA and PT neuromodulation is systematically investigated at the single neuron level. These results show that to achieve the same level of neuron activation recorded by Ca2+ imaging, the laser energy needed for PA stimulation is 1/40 of that needed for PT stimulation. The threshold energy for PA stimulation is found to be further reduced in neurons overexpressing mechano‐sensitive channels, indicating direct involvement of mechano‐sensitive channels in PA stimulation. Electrophysiology study of single neurons upon PA and PT stimulation is performed by patch clamp recordings. Electrophysiological features induced by PA are distinct from those by PT, confirming that PA and PT stimulation operate through different mechanisms. These insights offer a foundation for the rational design of more efficient and safer non‐genetic neural modulation approaches. [ABSTRACT FROM AUTHOR]

In recent years, research on hyperdoped semiconductors has accelerated, displaying dopant concentrations far exceeding solubility limits to surpass the limitations of conventionally doped materials. Nitrogen defects in silicon have been extensively investigated for their unique characteristics compared to other pnictogen dopants. However, previous practical investigations have encountered challenges in achieving high nitrogen defect concentrations due to the low solubility and diffusivity of nitrogen in silicon, and the necessary non-equilibrium techniques, such as ion implantation, resulting in crystal damage and amorphisation. In this study, we present a single-step technique called high-pressure gas immersion excimer laser doping (HP-GIELD) to manufacture nitrogen-hyperdoped silicon. Our approach offers ultrafast processing, scalability, high control, and reproducibility. Employing HP-GIELD, we achieved nitrogen concentrations exceeding 6 at% (3.01 × 1021 at/cm3) in intrinsic silicon. Notably, nitrogen concentration remained above the liquid solubility limit to ~1 µm in depth. HP-GIELD's high-pressure environment effectively suppressed physical surface damage and the generation of silicon dangling bonds, while the well-known effects of pulsed laser annealing (PLA) preserved crystallinity. Additionally, we conducted a theoretical analysis of light-matter interactions and thermal effects governing nitrogen diffusion during HP-GIELD, which provided insights into the doping mechanism. Leveraging excimer lasers, our method is well-suited for integration into high-volume semiconductor manufacturing, particularly front-end-of-line processes. [ABSTRACT FROM AUTHOR]

Structural health monitoring applications have gained significant attention in recent research, particularly in the study of the mechanical–electrical properties of materials such as cement-based composites. While most researchers have focused on the piezoresistive properties of cement-based composites under compressive stress, exploring the electrical impedance of such materials can provide valuable insights into the relationship between their mechanical and electrical characteristics. In this study, we investigated the connection between the mechanical properties and electrical impedance of cement-based composites modified with Au nanoparticles. Cylindrical samples with dimensions of 3 cm in diameter and 6 cm in length were prepared with a ratio of w/c = 0.47. The Au nanoparticles (Au NPs) were synthesized using pulsed laser ablation in liquids, and their size distribution was analyzed through dynamical light scattering. Mechanical properties were evaluated by analyzing the Young modulus derived from strain–stress curves obtained at various force rates. Electrical properties were measured by means of electrical impedance spectroscopy. The experimental results revealed a notable reduction of 91% in the mechanical properties of Au NPs-cement compounds, while their electrical properties demonstrated a significant improvement of 65%. Interestingly, the decrease in mechanical properties resulting from the inclusion of gold nanoparticles in cementitious materials was found to be comparable to that resulting from variations in the water/cement ratios or the hydration reaction. [ABSTRACT FROM AUTHOR]

Introduction: Topographic surface patterning in the micro- and nanometer scale has evolved into a well applied approach in surface functionalization following biomimetic blueprints from nature. Depending on the production process an additional impact of process-related substrate modification has to be considered in functional surface optimization. This is especially true in case of antimicrobial applications of Cu surfaces where a modification of the substrate properties might impact bactericidal efficiency. Methods: In this regard, the effect of ultrashort pulsed direct laser interference patterning on the microstructure of pure Cu and resulting antimicrobial properties was investigated alongside line-like patterning in the scale of single bacterial cells. Results and Discussion: The process-induced microstructure modification was shown to play an important role in corrosion processes on Cu surfaces in saline environment, whereas the superficial microstructure impacts both corrosive interaction and ion emission. Surprisingly, antimicrobial efficiency is not predominantly following deviating trends in Cu ion release rates but rather depends on surface topography and wettability, which was shown to be impacted by the substrate microstructure state, as well. This highlights the need of an in-depth understanding on how different surface properties are simultaneously modulated during laser processing and how their interaction has to be designed to acquire an effective surface optimization e.g., to agitate active antimicrobial surface functionalization. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles have gained attention in technological fields, particularly photonics. The creation of silver/gold (Ag/Au) alloy NPs upon laser exposure of an assembly of these NPs was described. First, using the Nd: YAG pulsed laser ablation's second harmonic at the same average power and exposure time, Ag and Au NPs in distilled water were created individually. Next, the assembly of Ag and Au NP colloids was exposed again to the pulsed laser, and the effects were examined at different average powers and exposure times. Furthermore, Ag/Au alloy nanoparticles were synthesized with by raising the average power and exposure time. The absorption spectrum, average size, and shape of alloy NPs were obtained by using an ultraviolet-visible (UV–Vis) spectrophotometer and transmission electron microscope instrument. Ag/Au alloy NPs have been obtained in the limit of quantum dots (<10 nm). The optical band gap energies of the Ag/Au alloy colloidal solutions were assessed for different Ag/Au alloy NP concentrations and NP sizes as a function of the exposure time and average power. The experimental data showed a trend toward an increasing bandgap with decreasing nanoparticle size. The nonlinear optical characteristics of Ag/Au NPs were evaluated and measured by the Z-scan technique using high repetition rate (80 MHz), femtosecond (100 fs), and near-infrared (NIR) (750–850 nm) laser pulses. In open aperture (OA) Z-scan measurements, Ag, Au, and Ag/AuNPs present reverse saturation absorption (RSA) behavior, indicating a positive nonlinear absorption (NLA) coefficient. In the close-aperture (CA) measurements, the nonlinear refractive (NLR) indices (n2) of the Ag, Au, and Ag/Au NP samples were ascribed to the self-defocusing effect, indicating an effective negative nonlinearity for the nanoparticles. The NLA and NLR characteristics of the Ag/Au NPs colloids were found to be influenced by the incident power and excitation wavelength. The optical limiting (OL) effects of the Ag/Au alloy solution at various excitation wavelengths were studied. The OL effect of alloy NPs is greater than that of monometallic NPs. The Ag/Au bimetallic nanoparticles were found to be more suitable for optical-limiting applications. [ABSTRACT FROM AUTHOR]

The application of cold spray (CS) for 316L stainless steel (SS) has been an increasingly popular process in recent years. However, defects in the form of porosity hamper their frictional resistance. In an effort to enhance the frictional resistance of CS 316L SS, novel indirect-laser surface texturing without confinement (ILSTwC) and direct-laser surface texturing without confinement (DLSTwC) processes are introduced as viable surface texturing, densifying, and strengthening techniques. These techniques operate by taking advantage of the severe plastic deformation and heating kinetics of a pulsed laser to an externally applied mesh, thus creating a surface texture that is highly dense and work-hardened. For the ILSTwC treatment, utilizing a laser intensity of 6.13 GW cm−2 led to significant changes in surface properties. Compared to the non-textured CS surface, there was a 24.1% increase in surface roughness, a notable 262.2% increase in surface skewness, a 26.0% increase in surface hardness, and a substantial 54.4% decrease in frictional response. For the DLSTwC treatment at the same laser intensity, the surface properties exhibited contrasting behavior. There was a remarkable 80.4% reduction in surface roughness, accompanied by a 63.6% increase in surface skewness, a 26.4% increase in surface hardness, and a significant 65.1% decrease in frictional response compared to the non-textured CS surface. Between the ILSTwC and DLSTwC surfaces, the DLSTwC surface had the greatest reduction in friction due to the lessened tribological contacts from the negatively skewed surface. Based on these findings, this work indicates that laser surface texturing has an influential effect on enhancing surface hardness and density and is indeed a viable technique to control the tribological performance of harder materials such as CS 316L SS. [ABSTRACT FROM AUTHOR]

This paper explores the characteristics of processing carbon fiber-reinforced plastic (CFRP) materials with ultra-short pulsed lasers. By combining experimental and numerical simulation methods, the processing characteristics when ultra-short pulsed lasers interact with CFRP are analyzed, including processing depth, processing width, the formation of heat-affected zone (HAZ), and the microstructure of the processed surface. The experimental part involves using picosecond and femtosecond lasers to machine holes or slots in CFRP under different process parameters and comparing their morphologies. Numerical simulation constructs a three-dimensional model to predict the temperature field distribution and material removal dynamics during the laser processing process. The results of experiments and simulations indicate that picosecond laser processing produced a visible HAZ and thermal damage; as the power of the picosecond laser increases, the ablation holes and HAZ gradually expand. In contrast, no HAZ is observed in femtosecond laser processing. Femtosecond pulsed lasers can effectively reduce the thermal damage during the CFRP processing. The anisotropic properties of CFRP materials have a significant impact on the laser processing effects. The research findings provide a theoretical basis and technical support for the precise processing of CFRP materials, which is of great significance for the application of CFRP materials in fields such as aerospace and automotive manufacturing. [ABSTRACT FROM AUTHOR]

Nanosecond pulsed laser etching for fabricating anti-reflective gratings and inducing synchronous laser annealing was performed on Ag/AZO films. The optimum grating pitch was determined by performance analyses of laser-etched unidirectional gratings, based on which laser-etched bidirectional gratings were fabricated to further determine the optimum grating tilt angle. The results revealed that with the increase of grating pitch, the grating ridge total-side-area was gradually decreased to cause a gradually weakened anti-reflective effect, but the superimposed heat-affected zones between adjacent grooves became smaller or even disappeared, which brought about different synchronous laser annealing effects. The unidirectional grating-textured film with a medium grating pitch of 200 μm showed the best overall performance under the combined influence from anti-reflective gratings and synchronous laser annealing. For the bidirectional gratings, although increasing the grating tilt angle did not change the grating ridge total-side-area, it would enable the laser energy to be more uniformly distributed on the whole film surface, producing a better synchronous laser annealing effect. The bidirectional grating-textured film with a grating tilt angle of 90° had the best overall performance with the highest FOM value of 2.18 × 10−2 Ω−1 that was ∼3.2 times that of the as-prepared film. The results are instructive for preparing high-performance TCO-based films. [ABSTRACT FROM AUTHOR]

In this paper we present the principle of operation, fabrication and performance of a phosphorescent optical-fiber quasi-distributed sensor with contactless smartphone interrogation. An array of short strong corrugated long-period gratings (C-LPG) is used as a platform to spatially locate and to excite the phosphors whose time responses are temperature-dependent. The C-LPG array was fabricated using a pulsed CO2 laser. The quasi-distributed sensing array is excited by a UV LED and the normalized differential rise/decay time response measured by a smartphone is used as a measure of the temperature. The sensing spots have a volume smaller than 0.5 μL, can be separated by several millimeters to several meters and the interrogation can be simultaneous or in a sequence. The response and the sensitivity to temperature have been measured. The sensing array has been shown to measure abrupt and gradual temperature changes in space as well as time-dependent processes in the 0 °C to 100 °C range and with a measurement time of 1 s. [ABSTRACT FROM AUTHOR]

Falling within the safe bands for human eyes, 1550 nm semiconductor lasers have a wide range of applications in the fields of LIDAR, fast-ranging long-distance optical communication, and gas sensing. The 1550 nm human eye-safe high-power tunnel junction quantum well laser developed in this paper uses three quantum well structures connected by two tunnel junctions as the active region; photolithography and etching were performed to form two trenches perpendicular to the direction of the epitaxial layer growth with a depth exceeding the tunnel junction, and the trenches were finally filled with oxides to reduce the extension current. Finally, a 1550 nm InGaAlAs quantum well laser with a pulsed peak power of 31 W at 30 A (10 KHz, 100 ns) was realized for a single-emitter laser device with an injection strip width of 190 μm, a ridge width of 300 μm, and a cavity length of 2 mm, with a final slope efficiency of 1.03 W/A, and with a horizontal divergence angle of about 13° and a vertical divergence angle of no more than 30°. The device has good slope efficiency, and this 100 ns pulse width can be effectively applied in the fields of fog-transparent imaging sensors and fast headroom ranging radar areas. [ABSTRACT FROM AUTHOR]

This article aims to explore the most optimal pulsed laser energy density when using the pulsed laser deposition (PLD) process to prepare the MoS2 films. We gradually increased the pulsed laser energy density from 70 mJ·cm−2 to 110 mJ·cm−2 and finally determined that 100 mJ·cm−2 was the best-pulsed laser energy density for MoS2 films by PLD. The surface morphology and crystallization of the MoS2 films prepared under this condition are the best. The films consist of a high-crystallized 2H-MoS2 phase with strong (002) preferential orientation, and their direct optical band gap (Eg) is 1.614 eV. At the same time, the Si/MoS2 heterojunction prepared under the optimal pulsed laser energy density shows an opening voltage of 0.61 V and a rectification ratio of 457.0. [ABSTRACT FROM AUTHOR]

Phase-pure crystalline cubic boron nitride (c-BN) thin films are of immense scientific and technical interest because of their suitable properties for optoelectronic and high-power applications, high thermal conductivity and hardness, chemical inertness to ferrous materials in high-temperature and caustic environments, and high optical transmittance over a broad wavelength range from the ultraviolet (UV) to the visible spectrum. However, the lack of controlled fabrication techniques for high-quality c-BN films significantly affects the reliable practical applications of this material. Recently, phase-pure single-crystal c-BN and a new phase of BN with unique properties, called quenched-BN (Q-BN), have been synthesized using a pulsed laser annealing (PLA) technique to overcome the current impediments in c-BN synthesis. This review paper comprehensively examines the current status of analytical research on the growth, characterization, and properties (optical and electrical) of c-BN films fabricated by different synthesis techniques, with a particular emphasis on the immensely promising PLA technique. In particular, the paper focuses on the processes used to obtain phase-pure c-BN films via epitaxial growth, characterization of defects and interfaces, and control of the structural, electrical, and optical properties of these films by controlling the growth parameters, including the laser–solid interaction for the direct conversion of nanocrystalline hexagonal boron nitride (h-BN) into crystalline c-BN using the PLA technique. The latest developments in c-BN electronics are also discussed, with a focus on producing p-and n-type conductivity using different dopants to achieve dopant concentrations far beyond the retrograde thermodynamic solid solubility limits. Finally, the future prospects and possible applications in emerging areas are discussed, as well as the goals and guidelines for future research of PLA-grown c-BN films. A comprehensive overview of the properties, application, characterization, shortcomings, and future prospects of c-BN [ABSTRACT FROM AUTHOR]

Platinum diselenide (PtSe2), classified as a noble metal dichalcogenide, has garnered substantial interest owing to its layer-dependent band structure, remarkable air-stability, and high charge-carrier mobilities. These properties make it highly promising for a wide array of applications in next-generation electronic and optoelectronic devices, as well as sensors. Additionally, two-dimensional (2D) PtSe2 demonstrates significant potential as a saturable absorber due to its exceptional nonlinear optical response across an ultrabroad spectra range, presenting exciting opportunities in ultrafast and nonlinear photonics. In this work, we explore the second-order nonlinear optical characteristics of 2D PtSe2 by analyzing its second-harmonic generation (SHG) excited by a pulsed laser at 1064 nm. Our investigation unveils a layer-dependent SHG response in PtSe2, with prominent SHG intensity observed in few-layer PtSe2. The distinct six-fold polarization dependence pattern observed in the SHG intensity reflects the inherent threefold rotational symmetry inherent to the PtSe2 crystal structure. Remarkably, the SHG intensity of 4-layer PtSe2 surpasses that of mechanically exfoliated monolayer molybdenum disulfide (MoS2) by approximately two orders of magnitude (60-fold), underscoring its exceptional second-order nonlinear optical response. Combined with its ultrahigh air-stability, these distinctive nonlinear optical characteristics position two-dimensional PtSe2 as a promising candidate for ultrathin nonlinear nanophotonic devices. [ABSTRACT FROM AUTHOR]

Photoacoustics can provide a direct measurement of light absorption by microalgae depending on the photosynthesis pigment within them. In this study, we have performed photoacoustic flowmetry on living microalgae cells to measure their flow characteristics, which include flow speed, flow angle, flow direction, and, more importantly, the photoacoustic absorption spectrum, all by observing the photoacoustic Doppler power spectra during their flowing state. A supercontinuum pulsed laser with a high repetition frequency is used as the light source: through intensity modulation at a specified frequency, it can provide wavelength-selectable excitation of a photoacoustic signal centered around this frequency. Our approach can be useful to simultaneously measure the flow characteristics of microalgae and easily discriminate their different species with high accuracy in both static and dynamic states, thus facilitating the study of their cultivation and their role in our ecosystem. [ABSTRACT FROM AUTHOR]

Titanium nitride (TiN) is a candidate material for several plasmonic applications, and pulsed laser ablation in liquids (PLAL) represents a rapid, scalable, and environmentally friendly approach for the large-scale production of nanomaterials with customized properties. In this work, the nanosecond PLAL process is developed, and we provide a concise understanding of the process parameters, such as the solvent and the laser fluence and pulse wavelength, to the size and structure of the produced TiN nanoparticles (NPs). TiN films of a 0.6 μm thickness developed by direct-current (DC) magnetron sputtering were used as the ablation targets. All laser process parameters lead to the fabrication of spherical NPs, while the laser pulse fluence was used to control the NPs' size. High laser pulse fluence values result in larger TiN NPs (diameter around 42 nm for 5 mJ and 25 nm for 1 mJ), as measured from scanning electron microscopy (SEM). On the other hand, the wavelength of the laser pulse does not affect the mean size of the TiN NPs (24, 26, and 25 nm for 355, 532, and 1064 nm wavelengths, respectively). However, the wavelength plays a vital role in the quality of the produced TiN NPs. Shorter wavelengths result in NPs with fewer defects, as indicated by Raman spectra and XPS analysis. The solvent type also significantly affects the size of the NPs. In aqueous solutions, strong oxidation of the NPs is evident, while organic solvents such as acetone, carbides, and oxides cover the TiN NPs. [ABSTRACT FROM AUTHOR]

Pulsed laser ablation (PLA) technology has been utilized for creating nano-sized particles from silver oxide, zinc oxide, and mixed oxide (Ag2O, ZnO, ZnO: Ag2O) combined with polyvinylpyrrolidone (PVP) for environmental applications, especially the filtration regarding oil-polluted water in rivers. A range of analytical methods have been employed to describe the prepared as well as polymer-supported nanomaterials' characteristics. Energy-dispersive X-ray spectroscopy, scanning \ transmission electron microscopy (SEM \ TEM) analysis, X-ray diffraction \ fluorescence (XRD \ XRF), Fourier-transform infrared spectroscopy, and photoluminescence measurements (PL) were among them. The nanocomposite ZnO: Ag2O showed numerous nanostructures with diverse orientations, according to XRD analysis. SEM imaging of the Ag2O nanoparticles indicated polydispersed spherical particles with widespread aggregation. Furthermore, the study incorporated the use of polymer-supported nanomaterials, with PVP selected for its excellent chemical and thermal resistance. Various membrane structures with differing porosities were prepared and effectively employed for the filtration of oil-polluted water, as validated through TEM, XRF, and other measurements. In this context, the polymer functioned akin to a sponge for water pollution remediation. [ABSTRACT FROM AUTHOR]