Low-intensity pulsed laser

BACKGROUND: The low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) have been recently applied to control pain during orthodontic treatment. OBJECTIVE: To evaluate and compare the effectiveness of LLLT and LIPUS in reducing pain induced by orthodontic separation. STUDY DESIGN: A single-blinded randomized controlled trial. METHODS: One hundred and fifty patients were randomly assigned into three groups; LLLT group, LIPUS group, and control group...

We demonstrate a bidirectional mode-locked erbium-doped fiber laser by incorporating gold nanofilm as a saturable absorber (SA). The gold nanofilm SA has the advantages of high stability and high optical damage threshold. Besides, the SA exhibits a large modulation depth of 26% and a low saturation intensity of 1.22 MW/cm2 at 1.56 μm wavelength band, facilitating the mode-locking of bidirectional propagating solitons within a single laser cavity. Bidirectional mode-locked solitons are achieved, with the clockwise pulse centered at 1568...

The nuclear and petrochemical industries often require multi-metal parts that are corrosion-resistant, heat-resistant, and possess high strength to enhance equipment safety and reduce downtime. Additive manufacturing technology enables the rapid and flexible processing of multi-metal parts to meet these stringent demands. This study is aimed at investigating the interface hardness between CoCrMo/IN625 to determine optimal processing parameters that can be utilized in manufacturing reliable and durable multi-metal parts...

This work presents the results of research conducted with an aim to improve the surface quality, hardness and wear resistance of titanium alloy Ti6Al4V, obtained via the laser powder bed fusion of metals (PBF-LB/M) process of additive manufacturing (AM) known as the 3D printing of metals. The 3D surfaces were coated via reactive electrospark deposition (RESD) with low-pulse energy and electrode materials of low-melting metals and multi-component hard alloys. The relationship between the electrical parameters of the RESD process and the quality, composition, structure, microhardness and wear resistance of the treated surfaces were investigated and analysed...

We study the Thomson scattering from highly oriented pyrolitic graphite excited by the extreme ultraviolet, coherent pulses of FERMI free electron laser (FEL). An apparent nonlinear behavior is observed and fully described in terms of the coherent nature of both exciting FEL beam and scattered radiation, producing an intensity-dependent enhancement of the Thomson scattering cross-section. The process resembles Dicke's superradiant phenomenon and is thus interpreted as the observation of superradiant Thomson scattering...

In this study, we investigated how high-temperature, high-pressure hydrogen affects the optical properties of three kinds of sealing rubber (chloroprene rubber, ethylene propylene diene monomer, and acrylonitrile butadiene rubber) using pulsed terahertz waves. The optical properties of the rubber samples were analyzed before and after exposure to hydrogen (80 °C and 200 bar) for 72 h. The results showed that the terahertz waves had a shorter time delay and a lower signal intensity for all rubber types...

Two-dimensional terahertz-infrared-visible (2D TIRV) spectroscopy directly measures the coupling between quantum high-frequency vibrations and classical low-frequency modes of molecular motion. In addition to coupling strength, the signal intensity in 2D TIRV spectroscopy can also depend on the selection rules of the excited transitions. Here, we explore the selection rules in 2D TIRV spectroscopy by studying the coupling between the high-frequency CH3 stretching and low-frequency vibrations of liquid dimethyl sulfoxide (DMSO)...

Diabetic wounds remain a great challenge for clinicians globally as a lack of effective radical treatment often results in poor prognosis. Exosomes derived from adipose‑derived stem cells (ADSC‑Exos) have been explored as an appealing nanodrug delivery system in the treatment of diabetic wounds. However, the short half‑life and low utilization efficiency of exosomes limit their therapeutic effects. Low‑intensity pulsed ultrasound (LIPUS) provides a non‑invasive mechanical stimulus to cells and exerts a number of biological effects such as cavitation and thermal effects...

The blood-brain barrier (BBB) poses a significant challenge to drug delivery for brain tumors, with most chemotherapeutics having limited permeability into non-malignant brain tissue and only restricted access to primary and metastatic brain cancers. Consequently, due to the drug's inability to effectively penetrate the BBB, outcomes following brain chemotherapy continue to be suboptimal. Several methods to open the BBB and obtain higher drug concentrations in tumors have been proposed, with the selection of the optimal method depending on the size of the targeted tumor volume, the chosen therapeutic agent, and individual patient characteristics...

Intense lasers enable generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. The high energy conversion efficiency of DLA makes it ideal for generating large numbers of photonuclear reactions. In this work, we reveal that, for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed...

We demonstrate a GHz repetition rate mode-locked Tm3+ -doped fiber laser with low noise. Based on a home-made Tm3+ -doped barium gallo-germanate fiber with reduced dispersion, a broad optical spectrum of mode-locking is achieved, and its amplified spontaneous emission quantum-limited timing jitter is largely suppressed. Besides, we carefully investigate the influence of the intracavity pump strength on the noise performance of the mode-locked pulses and find that manipulating the intracavity pump power can be an effective method for optimizing the timing jitter and relative intensity noise (RIN)...

Pulsed laser deposited films on glass substrate deposited at different substrate temperatures (Ts ) and partial pressures of oxygen, Ho3+ -doped Bi2 O3 films were produced. The degradation capability of the Rhodamine B dye using the Bi2 O3 :Ho3+ films was explored. The impact of the Bi2 O3 :Ho3+ content on the dye degradation performance was analyzed. The X-ray powder diffraction patterns showed that the films deposited at 400 °C had an α-Bi2 O3 phase. The impacts of various Ts and O2 partial pressures were correlated with the surface morphology and the thickness of the films using results of field emission scanning electron microscope...

Metal halide perovskite films have gained significant attention because of their remarkable optoelectronic performances. However, their poor stability upon the severe environment appears to be one of the main facets that impedes their further commercial applications. Herein, a method to improve the stability of flexible photodetectors under water and humidity environment without encapsulation is reported. The devices were fabricated using the physical vapor deposition method (Pulse Laser Deposition & Thermal Evaporation) under high-vacuum conditions...

In this work, we systematically explore the third-order nonlinear optical properties of all-inorganic CsPbX3 (X = Cl, Br, I) perovskite precursor solutions and thin films using femtosecond and nanosecond laser pulses. We show that these samples possess strong two-photon absorption (TPA) and reverse saturable absorption (RSA), which depend on the excitation wavelength. The obtained nonlinear absorption and refraction coefficients for precursor solutions are followed by the relation CsPbCl3  > CsPbBr3  > CsPbI3 for the 800 and 1,064 nm excitation wavelengths, whereas this relation became reverse in the case of 355 and 400 nm laser pulses...

Improper disposal of waste oils containing hazardous components damages the environment and the ecosystem, posing a significant threat to human life and health. Here, we present a method of discharge-assisted laser-induced breakdown spectroscopy combined with filter paper sampling (DA-LIBS-FPS) to detect hazardous components and trace the source of polluting elements. DA-LIBS-FPS significantly enhances spectral intensity by 1-2 orders of magnitude due to the discharge energy deposition into the laser-induced plasma and the highly efficient laser-sample interaction on the filter paper, when compared to single-pulse LIBS with silica wafer sampling (SP-LIBS-SWS)...

Nanodroplets' explosive vaporization triggered by absorption of laser pulses produces very large volume changes. These volume changes are two orders of magnitude higher than those of thermoelastic expansion generated by equivalent laser pulses, and should generate correspondingly higher photoacoustic waves (PAW). The generation of intense PAWs is desirable in photoacoustic tomography (PAT) to increase sensitivity. The biocompatibility and simplicity of nanodroplets obtained by sonication of perfluoropentane (PFP) in an aqueous solution of bovine serum albumin (BSA) containing a dye make them particularly appealing for use as contrast agents in clinical applications of PAT...

INTRODUCTION: Epidural electrical stimulation (EES) has been shown to improve motor dysfunction after spinal cord injury (SCI) by activating residual locomotor neural networks. However, the stimulation current often spreads excessively, leading to activation of non-target muscles and reducing the accuracy of stimulation regulation. OBJECTIVES: Near-infrared nerve stimulation (nINS) was combined with EES to explore its regulatory effect on lower limb muscle activity in spinal-cord-transected rats...

INTRODUCTION: Hypertrophic scarring is a common and debilitating consequence of burn scars. While there is limited evidence for current treatment options, laser therapy has been shown to be effective, low risk and minimally invasive. This study assesses the use of carbon dioxide lasers and intense pulsed light devices in the treatment of hypertrophic burn scars. METHODS: In this case series, patients were recruited from a hypertrophic burn scar waitlist and completed a Patient and Observer Scar Assessment Scale prior to and six weeks after laser therapy...

INTRODUCTION: Non-specific low back pain is a common and clinically significant condition with substantial socioeconomic implications. Pulsed electromagnetic field (PEMF) therapy has shown benefits in pain reduction and improvement of physical function in patients with pain-associated disorders like osteoarthritis. However, studies had heterogeneous settings. The aim of this study was to assess the effects of PEMF on pain and function on patients with non-specific low back pain. METHODS: A systematic literature search of randomized controlled trials in PubMed, MEDLINE, EMBASE, Cochrane Library, and PEDro was performed (from inception until 15/5/2023)...

The recent interests in bridging intriguing optical phenomena and thermal energy management has led to the demonstration of controlling thermal radiation with epsilon-near-zero (ENZ) and the related near-zero-index (NZI) optical media. In particular, the manipulation of thermal emission using phononic ENZ and NZI materials has shown promise in mid-infrared radiative cooling systems operating under low-temperature environments (below 100 °C). However, the absence of NZI materials capable of withstanding high temperatures has limited the spectral extension of these advanced technologies to the near-infrared (NIR) regime...