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Low-intensity pulsed laser

Marija Vranic, Ondrej Klimo, Georg Korn, Stefan Weber
The new generation of laser facilities is expected to deliver short (10 fs-100 fs) laser pulses with 10-100 PW of peak power. This opens an opportunity to study matter at extreme intensities in the laboratory and provides access to new physics. Here we propose to scatter GeV-class electron beams from laser-plasma accelerators with a multi-PW laser at normal incidence. In this configuration, one can both create and accelerate electron-positron pairs. The new particles are generated in the laser focus and gain relativistic momentum in the direction of laser propagation...
March 16, 2018: Scientific Reports
Tanya Moutray, Jennifer R Evans, Noemi Lois, David J Armstrong, Tunde Peto, Augusto Azuara-Blanco
BACKGROUND: Diabetic retinopathy (DR) is a chronic progressive disease of the retinal microvasculature associated with prolonged hyperglycaemia. Proliferative DR (PDR) is a sight-threatening complication of DR and is characterised by the development of abnormal new vessels in the retina, optic nerve head or anterior segment of the eye. Argon laser photocoagulation has been the gold standard for the treatment of PDR for many years, using regimens evaluated by the Early Treatment of Diabetic Retinopathy Study (ETDRS)...
March 15, 2018: Cochrane Database of Systematic Reviews
Joshua H Marks, Timothy B Ward, Michael A Duncan
Manganese oxide cluster cations are produced by laser vaporization in a pulsed nozzle source, and detected with time-of-flight mass spectrometry. The mass spectrum contains intense peaks for stoichiometries corresponding to (MnO)n+. Multiphoton photodissociation of these clusters yields smaller ions with the same stoichiometric ratio, either by sequential elimination of MnO units or by various fission processes with roughly equal efficiencies. Fragmentation of clusters containing excess oxygen also yields (MnO)n+ fragments...
March 14, 2018: Journal of Physical Chemistry. A
Andreas Leonidou, Panagiotis Lepetsos, Michalis Mintzas, Eustathios Kenanidis, George Macheras, Maria Tzetis, Michael Potoupnis, Eleftherios Tsiridis
Inducible nitric oxide synthase (iNOS) is the enzyme responsible for the production of nitric oxide (NO), a major proinflammatory and destructive mediator in osteoarthritis (OA). Areas covered: This is a comprehensive review of the recent literature on the involvement of iNOS in osteoarthritis and its potential to be used as a target for OA treatment. Evidence from in vitro, in vivo and human studies was systematically collected using medical search engines. Preclinical studies have focused on the effect of direct and indirect iNOS inhibitors in both animal and human tissues...
March 5, 2018: Expert Opinion on Therapeutic Targets
Mei-Ling Chen, Zhi-Wen Gao, Xue-Min Chen, Shu-Chao Pang, Yi Zhang
Magnetic graphene-based hybrids are being increasing recognized as an effective nanotheranostic agent in biomedicine. Conventional technologies for their synthesis have drawbacks not only from a synthetic standpoint, mainly requiring high temperatures and multi-step processes, but also from a biological perspective, chemical precursors or surfactants involved in the chemical process are toxic to cells. Herein, we report a novel approach for one-step fabricating magnetic graphene hybrid nanocomposites based on laser irradiation of an Fe target in GO-PEG aqueous solution at room temperature without using any other chemical reagent...
May 15, 2018: Talanta
Luca Fedeli, Arianna Formenti, Lorenzo Cialfi, Andrea Pazzaglia, Matteo Passoni
Near-critical plasmas irradiated at ultra-high laser intensities (I > 1018 W/cm2 ) allow to improve the performances of laser-driven particle and radiation sources and to explore scenarios of great astrophysical interest. Near-critical plasmas with controlled properties can be obtained with nanostructured low-density materials. By means of 3D Particle-In-Cell simulations, we investigate how realistic nanostructures influence the interaction of an ultra-intense laser with a plasma having a near-critical average electron density...
March 1, 2018: Scientific Reports
Mehmet Emre Coskun, Kubra Acikalin Coskun, Yusuf Tutar
OBJECTIVE: The aim of this study was to determine the optimum operating parameters (pulse duration, energy levels, and application time) to promote induction of osteoblast and fibroblast cell proliferation and to maintain cell viability treated with low-intensity pulsed ultrasound (LIPUS) and low-level laser therapy (LLLT). BACKGROUND DATA: The positive effects of LIPUS and LLLT on cellular activity have been reported in recent years. Comparisons between experimental parameters of previous studies are difficult because scientific studies reported frequencies and the duty cycles of LIPUS and wavelengths and doses of LLLT in a wide range of parameters...
February 21, 2018: Photomedicine and Laser Surgery
E Di Russo, I Blum, J Houard, M Gilbert, G Da Costa, D Blavette, L Rigutti
A systematic study of the biases occurring in the measurement of the composition of GaN by Atom Probe Tomography was carried out, in which the role of surface electric field and laser pulse intensity has been investigated. Our data confirm that the electric field is the main factor influencing the measured composition, which exhibits a deficiency of N at low field and a deficiency of Ga at high field. The deficiency of Ga at high field is interpreted in terms of preferential evaporation of Ga. The detailed analysis of multiple evaporation events reveals that the measured composition is not affected by pile-up phenomena occurring in detection system...
February 6, 2018: Ultramicroscopy
N Lemos, L Cardoso, J Geada, G Figueira, F Albert, J M Dias
We experimentally demonstrate that plasma waveguides produced with ultra-short laser pulses (sub-picosecond) in gas jets are capable of guiding high intensity laser pulses. This scheme has the unique ability of guiding a high-intensity laser pulse in a plasma waveguide created by the same laser system in the very simple and stable experimental setup. A hot plasma column was created by a femtosecond class laser that expands into an on-axis parabolic low density profile suitable to act as a waveguide for high intensity laser beams...
February 16, 2018: Scientific Reports
Paul S Hsu, Naibo Jiang, Paul M Danehy, James R Gord, Sukesh Roy
Transmission of intense ultrashort laser pulses through hollow-core fibers (HCFs) is investigated for molecular-tagging velocimetry. A low-vacuumed HCF beam-delivery system is developed to transmit high-peak-power pulses. Vacuum pressure effects on transmission efficiency and nonlinear effects at the fiber output are studied for 100 ps and 100 fs laser beams. With a 0.1 bar vacuum in the fiber, transmission efficiency increases by ∼30%, while spectral broadening is reduced. A 1 m long, 1 mm core metal-dielectric-coated HCF can transmit ∼45  mJ/pulse and ∼2...
January 20, 2018: Applied Optics
Kuo-Jui Chu, Po-Chun Chen, Yun-Wen You, Hsun-Yun Chang, Wei-Lun Kao, Yi-Hsuan Chu, Chen-Yi Wu, Jing-Jong Shyue
With its low-cost fabrication and ease of modification, paper-based analytical devices have developed rapidly in recent years. Microarrays allow automatic analysis of multiple samples or multiple reactions with minimal sample consumption. While cellulose paper is generally used, its high backgrounds in spectrometry outside of the visible range has limited its application to be mostly colorimetric analysis. In this work, glass-microfiber paper is used as the substrate for a microarray. The glass-microfiber is essentially chemically inert SiOx, and the lower background from this inorganic microfiber can avoid interference from organic analytes in various spectrometers...
April 16, 2018: Analytica Chimica Acta
Qing Tong, Yuhua Wang, Xiangxiang Yu, Bo Wang, Zhuang Liang, Meng Tang, An-Shun Wu, Haijun Zhang, Feng Liang, Ya-Feng Xie, Jun Wang
Graphene-ZnO (GZO) nanocomposites were synthesized by a modified solvothermal method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectra and UV-vis absorption spectra. The controllable nonlinear optical (NLO) properties of as-prepared GZO nanocomposites were tested by an open-aperture (OA) Z-scan method equipped with 1030 nm femtosecond laser pulses and it showed that the five photons absorption (5PA) at 46.8 GW/cm2, three photons absorption (3PA) at 28.1 GW/cm2, two photons absorption (2PA) at 18...
January 31, 2018: Nanotechnology
P A Zhokhov, A M Zheltikov
We show that a broadly accepted criterion of laser-induced breakdown in solids, defining the laser-breakdown threshold in terms of the laser fluence or laser intensity needed to generate a certain fraction of the critical electron density rc within the laser pulse, fails in the case of high-intensity few-cycle laser pulses. Such laser pulses can give rise to subcycle oscillations of electron density ρ with peak ρ values well above ρc even when the total energy of the laser pulse is too low to induce a laser damage of material...
January 29, 2018: Scientific Reports
S V Moskvin, T V Konchugova, A А Khadartsev
One of the most widely employed methods of laser therapy is laser irradiation of blood (LIB). There are two modifications of this technique, one being intravenous low-intensity laser irradiation of blood (ILIB), the other non-invasive blood irradiation(NLIB). The two methods have been developing independently since either has its advantages and disadvantages. The present article was designed to review the main currently available techniques for laser irradiation of blood which are presented in the form of tables (charts)...
December 5, 2017: Voprosy Kurortologii, Fizioterapii, i Lechebnoĭ Fizicheskoĭ Kultury
O I Apolikhin, S V Moskvin
Male infertility is a multifactorial syndrome associated with a wide range of pathological conditions affecting both the sexual and other body systems: endocrine, nervous, blood, and immune. Laser therapy is a form of modern physiotherapy that applies low-intensity laser irradiation (LILI) in various parts of the body. It is widely used in all areas of modern medicine due to its high efficiency, ease of use, the absence of contraindications and side effects. The authors reviewed the results of 171 studies investigating laser therapy, of which 93 were experimental (20 in Russian and 73 international publications), four clinical and experimental (all in Russian), 74 clinical (73 in Russian and 1 in English)...
December 2017: Urologii︠a︡
Thomas Willemsen, Marco Jupé, Mark Gyamfi, Sebastian Schlichting, Detlev Ristau
Dielectric components are essential for laser applications. Chirped mirrors are applied to compress the temporal pulse broadening crucial in the femtosecond regime. However, the design sensitivity and the electric field distribution of chirped mirrors is complex often resulting in low laser induced damage resistances. An approach is presented to increase the damage resistance of pulse compressing mirrors up to 190% in the NIR spectral range. Layers with critical high field intensity of a binary mirror design are substituted by ternary composites and quantized nanolaminates, respectively...
December 11, 2017: Optics Express
M Kübel, Z Dube, A Yu Naumov, M Spanner, G G Paulus, M F Kling, D M Villeneuve, P B Corkum, A Staudte
Ionization of an atom or molecule by a strong laser field produces suboptical cycle wave packets whose control has given rise to attosecond science. The final states of the wave packets depend on ionization and deflection by the laser field, which are convoluted in conventional experiments. Here, we demonstrate a technique enabling efficient electron deflection, separate from the field driving strong-field ionization. Using a midinfrared deflection field permits one to distinguish electron wave packets generated at different field maxima of an intense few-cycle visible laser pulse...
November 3, 2017: Physical Review Letters
K Hicke, D Brunner, M C Soriano, I Fischer
We investigate the dynamics of semiconductor lasers subject to time-delayed optical feedback from the perspective of dynamical self-injection locking. Based on the Lang-Kobayashi model, we perform an analysis of the well-known Low Frequency Fluctuations (LFFs) in the frequency-intensity plane. Moreover, we investigate a recently found dynamical regime of fragmented LFFs by means of a locking-range analysis, spectral comparison and precursor pulse identification. We show that LFF dynamics can be explained by dynamical optical injection locking due to the delayed optical feedback...
November 2017: Chaos
Mohammad Bayat, Amarjit Virdi, Fatemehalsadat Rezaei, Sufan Chien
To compare the in vitro effectiveness of Low-Level Laser Therapy (LLLT) and Low Intensity Pulsed Ultrasound (LIPUS) on bony cells and related stem cells. In this study, we aim to systematically review the published scientific literature which explores the use of LLLT and LIPUS to biostimulate the activity or the proliferation of bony cells or stem cells in vitro. We searched the database PubMed for LLLT or LIPUS, with/without bone, osteoblast, osteocyte, stem cells, the human osteosarcoma cell line (MG63), bone-forming cells, and cell culture (or in vitro)...
November 8, 2017: Progress in Biophysics and Molecular Biology
J Wätzel, J Berakdar
Irradiating intercalated nanorings by optical vortices ignites a charge flow that emits coherent trains of high harmonic bursts with frequencies and time structures that are controllable by the topological charge of the driving vortex beam. Similar to synchrotron radiation, the polarization of emitted harmonics is also selectable by tuning to the appropriate emission angle with respect to the ring plane. The nonequilibrium orbital magnetic moment triggered in a ring tunnels quantum mechanically to smaller and larger rings leading respectively to high and low-frequency harmonic generation...
October 30, 2017: Optics Express
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