To our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level. We also measured the spectral attenuation with our OTDR setup and compared it with a standardized measurement method. At the attenuation minima within the measured spectral range the backscattering level of a 1 ns pulse is about -46 dB at 520 nm, -48 dB at 570 nm, and -51 dB at 650 nm. We were also able to show by the observed wavelength dependence that Rayleigh scattering causes a majority of the scattering.
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http://dx.doi.org/10.1364/OE.437903 | DOI Listing |
Integr Environ Assess Manag
January 2025
Mu Gamma Consultants Pvt. Ltd, Gurgaon, India, 122018.
Microplastics (MPs) have become a notable concern and are released into the environment through the disposal or fragmentation of large plastics. Rivers have been the major pathways for MPs present in the oceans, which significantly affects the marine environment. In the current study, water samples were collected from the upper stream and downstream of Damanganga and Tapi rivers across different sites in the state of Gujarat, India for exploration of MPs contamination.
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January 2025
Department of Physics, Washington State University, Pullman, WA 99163, USA.
This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating.
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January 2025
Department of Advanced Oral Sciences and Therapeutics, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.
Background: Polymethyl methacrylate (PMMA) is ideal for denture bases but is prone to biofilm accumulation, leading to denture stomatitis (DS), often involving . Dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are introduced into dental materials for their antimicrobial and protein-repellent properties. This study investigates the effects of incorporating dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) into heat-polymerized (HP) and 3D-printed (3DP) denture base resins on microbial adhesion and cytotoxicity.
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January 2025
College of Engineering and Applied Sciences, Nanjing University, Nanjing 210023, China.
Quantum dot-polymer composites have the advantages of high luminescent quantum yield (PLQY), narrow emission half-peak full width (FWHM), and tunable emission spectra, and have broad application prospects in display and lighting fields. Research on quantum dots embedded in polymer films and plates has made great progress in both synthesis technology and optical properties. However, due to the shortcomings of quantum dots, such as cadmium selenide (CdSe), indium phosphide (InP), lead halide perovskite (LHP), poor water, oxygen, and light stability, and incapacity for large-scale synthesis, their practical application is still restricted.
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January 2025
Jožef Stefan Institute, Department of Physical and Organic Chemistry, Jamova c. 39, SI-1000 Ljubljana, Slovenia.
The study aimed to develop a superhydrophobic coating on the aluminium alloy 2024-T3 surface. The desired surface roughness and low surface energy were achieved with SiO nanoparticles, synthesised via the Stöber method and modified with alkyl silane (AS) or perfluoroalkyl silane (FAS). To enhance particle adhesion to the alloy substrate, nanoparticles were incorporated into a hybrid sol-gel coating composed of tetraethyl orthosilicate, methyl methacrylate, and 3-methacryloxypropyl trimethoxysilane.
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