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Quartz Optical Fibers with Increased Content of Fluorine for Fluorimeter Probes
摘要： A method to fabricate quartz optical fibers for probes employed in fluorescence diagnostics of tumors is proposed. It is shown that the sensitivity of fluorimeters in the near-IR spectral range can be increased using quartz–quartz optical fiber probes with the core made of the Heraeus glass and the SiO2–F cladding with an increased content of fluorine in the glass of up 7 wt %. The numerical aperture of such optical fibers amounts to 0.32. The optical fibers are used to develop a prototype of a multifiber high-aperture probe for a laser oncofluorimeter with a relatively high sensitivity in a spectral interval of 900–1100 nm.
关键词： fluorimeter probes,fluorescence diagnostics,quartz optical fibers,fluorine,near-IR spectral range
更新于2025-09-12 10:27:22
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Analysis of Plasmonic Gold Nanostar Arrays with the Optimum Sers Enhancement Factor on the Human Skin Tissue
摘要： We analyze the performance of the surface-enhanced Raman spectroscopy (SERS) substrate based on high-density gold nanostar nanoparticle (GNS) arrays assembled on the gold film and embedded in the human skin tissue as a surrounding medium. A self-assembled monolayer (SAM) of 3-aminopropyltriethoxy silane (APTES) is used for immobilizing GNSs on the Au film. The GNS–Au film and GNS–GNS coupling in the gap regions and also the GNSs interparticle coupling at their branches are observed, so the GNS arrays show more field enhancements and the sensitivity of the GNS sensor can be increased further. When the SERS substrate based on the GNS arrays is excited by a 785-nm laser line, a maximum enhancement factor (EF) of 109 is observed. It is demonstrated that the normalized EF depends on the geometry of the GNSs, the thickness of the Au film, and the separation distance between the cores of the GNSs.
关键词： thin films,spectroscopy,biomaterials,tissue diagnostics,nanostars,surface plasmons,plasmonics
更新于2025-09-12 10:27:22
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A Robust and General Approach to Quantitatively Conjugate Enzymes to Plasmonic Nanoparticles
摘要： Bioconjugates of plasmonic nanoparticles have received considerable attention due to their potential biomedical applications. Succesfull bioconjugation requires control over the number and activity of the conjugated proteins, and the colloidal stability of the particles. In practice, this requires re-optimization of the conjugation protocol for each combination of protein and nanoparticle. Here we report a robust and general protocol that allows for the conjugation of a range of proteins to di?erent types of nanoparticles using very short polyethylene-glycol(PEG) linkers, while simultaneously preserving protein activity and colloidal stability. The use of short linkers ensures that the protein is located close to the particle surface, where their refractive index sensitivity and near-?eld enhancement is maximal. We demonstrate that the use a Tween20 containing stabilizing bu?er is critical in maintaining colloidal stability and protein function throughout the protocol. We obtain quantitative control over the average number of enzymes per particle by either varying the number of functional groups on the particle, or the enzyme concentration during incubation. This new route of preparing quantitative protein-nanoparticle bioconjugates paves the way to develop rational and quantitative strategies to functionalize nanoparticles for applications in sensing, medical diagnostics and drug delivery.
关键词： medical diagnostics,drug delivery,quantitative control,protein activity,plasmonic nanoparticles,colloidal stability,sensing,bioconjugation,PEG linkers,Tween20
更新于2025-09-12 10:27:22
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Mitigation of EC breakdown in the gyrotron transmission line of the ITER Collective Thomson Scattering diagnostic via a Split Biased Waveguide
摘要： In this paper we present the results of the R&D work that has been performed on avoiding electron cyclotron (EC) gas breakdown inside the launcher transmission line (TL) of the ITER collective Thomson scattering (CTS) diagnostic, due to encountering the fundamental EC resonance, which is located inside the port plug vacuum for the baseline ITER magnetic field scenario. If an EC breakdown occurs, this can lead to strong local absorption of the CTS gyrotron beam, as well as arcing inside the ITER vacuum vessel, which must be avoided. Due to the hostile, restrictive, and nuclear environment in ITER, it is not possible to implement the standard method for avoiding EC breakdown - a controlled atmosphere at the EC resonance. Instead, the CTS diagnostic will include a longitudinally-split electrically-biased corrugated waveguide (SBWG) in the launcher transmission line. The SBWG works by applying a transverse DC bias voltage across the two electrically-isolated waveguide halves, causing free electrons to diffuse out of the EC resonant region before they can cause an electron-impact ionisation-avalanche, and thus an EC breakdown. Due to insufficient experimental facilities, the functionality of the SBWG is validated through Monte Carlo electron modelling.
关键词： Interaction of radiation with matter,Nuclear instruments and methods for hot plasma diagnostics,Overall mechanics design (support structures and materials, vibration analysis etc),Detector design and construction technologies and materials
更新于2025-09-12 10:27:22
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Matrix-Assisted Laser Desorption/Ionization Time-of-Flight
摘要： Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has undoubtedly changed the way clinical microbiology laboratories (CMLs) diagnose infectious diseases. Now commonly used for the routine identification of cultured bacteria and yeast, CMLs are looking to expand the use of MALDI-TOF MS to other areas of infectious diseases diagnostics. The relative ease of performance, low cost per test, and rapidity of results has prompted the development of advanced techniques, such as antimicrobial susceptibility, direct-from-specimen organism identification, and several other techniques that may improve on conventional techniques.
关键词： MALDI-TOF MS,Phenotypic susceptibility testing,Rapid organism identification,Infectious diseases diagnostics
更新于2025-09-11 14:15:04
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Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques
摘要： There is a wealth of existing experimental data of flames collected using laser diagnostics. The primary objective of this review is to provide context and guidance in interpreting these laser diagnostic data. This educational piece is intended to benefit those new to laser diagnostics or with specialization in other facets of combustion science, such as computational modeling. This review focuses on laser-diagnostics in the context of the commonly used canonical jet-in-hot-coflow (JHC) burner, although the content is applicable to a wide variety of configurations including, but not restricted to, simple jet, bluff body, swirling and stratified flames. The JHC burner configuration has been used for fundamental studies of moderate or intense low oxygen dilution (MILD) combustion, autoignition and flame stabilization in hot environments. These environments emulate sequential combustion or exhaust gas recirculation. The JHC configuration has been applied in several burners for parametric studies of MILD combustion, flame reaction zone structure, behavior of fuels covering a significant range of chemical complexity, and the collection of data for numerical model validation. Studies of unconfined JHC burners using gaseous fuels have employed point-based Rayleigh-Raman or two-dimensional Rayleigh scattering measurements for the temperature field. While the former also provides simultaneous measurements of major species concentrations, the latter has often been used in conjunction with planar laser-induced fluorescence (PLIF) to simultaneously provide quantitative or qualitative measurements of radical and intermediary species. These established scattering-based thermography techniques are not, however, effective in droplet or particle laden flows, or in confined burners with significant background scattering. Techniques including coherent anti-Stokes Raman scattering (CARS) and non-linear excitation regime two-line atomic fluorescence (NTLAF) have, however, been successfully demonstrated in both sooting and spray flames. This review gives an overview of diagnostics techniques undertaken in canonical burners, with the intention of providing an introduction to laser-based measurements in combustion. The efficacy, applicability and accuracy of the experimental techniques are also discussed, with examples from studies of flames in JHC burners. Finally, current and future directions for studies of flames using the JHC configuration including spray flames and studies and elevated pressures are summarized.
关键词： moderate or intense low oxygen dilution (MILD) combustion,autoignition,vitiated coflow burner (VCB),laser-induced fluorescence (LIF),thermography,jet in hot coflow (JHC),planar laser diagnostics
更新于2025-09-11 14:15:04
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Ultrafast Broadband Diagnostics of the Filling of the s Band at the Two-Photon Femtosecond Laser Excitation of a Gold Film
摘要： The transmission of near infrared femtosecond laser pulses (wavelength of 800 nm) and supercontinuum radiation (300–750 nm) generated by them through a 50-nm gold film immersed in water has been experimentally studied at the power of focused laser radiation in the range of 1–10 GW. An increase in the excitation intensity is accompanied by the blueshift of the edge of the extinction band of the film, which is attributed to the filling of electronic states of the s band with a low density of states caused by two-photon interband transitions from d bands with a high density of states.
关键词： supercontinuum radiation,gold film,ultrafast broadband diagnostics,s band filling,two-photon femtosecond laser excitation
更新于2025-09-11 14:15:04
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Fluorescent Nanosensors Based on Colloidal Quantum Dots for the Determination of Reduced Glutathione
摘要： A ? uorescent nanosensor based on colloidal quantum dots CdSe/ZnS modi? ed with mercaptoacetic acid to determine reduced glutathione, a non-protein compound that plays an important role in protection against oxidative stress, is developed. Sample preparation protocols that allow determination of reduced glutathione in a wide range of concentrations are presented. Dependence of the ? uorescence intensity of the system on the incubation time for a number of concentrations of reduced glutathione was measured. The possibility of using the proposed nanosensor for reliable and sensitive determination of reduced glutathione in the concentration range from 10 to 1000 μM is con? rmed. The results can be used for quantitative determination of reduced glutathione in physiological media, which is of considerable interest for medical diagnostics.
关键词： quantum dots,nanoparticles,optical nanosensors,? uorescence,reduced glutathione,disease markers,medical diagnostics
更新于2025-09-11 14:15:04
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Application of portable near-infrared spectrometer to Heliotron J plasma diagnostics
摘要： A simple near-infrared (NIR) spectrometer with a wavelength range of 898–2130 nm has recently been applied to diagnose Heliotron J plasmas. It adopts a symmetrical crossed Czerny–Turner mount equipped with a thermoelectrically cooled 512 channel InGaAs linear sensor. Reciprocal linear dispersion was deduced to 96.37 nm/mm at the center of the detector. External ?lters can be inserted into the path of the collection optics to reject second-order spectra, as needed. Absolute intensity calibration was performed together with a visible spectrometer using a tungsten halogen lamp, and the effect of the transmittance fringe in the visible region of the applied long-pass ?lter on the NIR calibration was investigated. The intended application of the NIR spectrometer includes extending the wavelength region of a spectral monitor to less contaminated regions for Heliotron J plasma studies. In preliminary measurements, we observed the Paschen series for the hydrogen pellet injection plasma and two atomic helium lines, i.e., 2S-2P singlet and triplet lines, in helium gas puf?ng experiments. A continuum spectrum in this regime that is attributable to black-body radiation from hot spots on the plasma-facing components was identi?ed. In addition, this may also be used to monitor background radiation in the YAG-Thomson scattering signals near 1064 nm.
关键词： near-infrared spectrometer,YAG-Thomson scattering,plasma diagnostics,helium lines,black-body radiation,Paschen series,Heliotron J
更新于2025-09-10 09:29:36
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Reconstruction and analysis of exploding wire particle trajectories via automatic calibration of stereo images
摘要： Quantitative understanding of the physics of dust or granular matter transport significantly impacts several aspects of burning plasma science and technology. This work takes machine vision techniques popular in robotics and self-driving cars and applies them to identification and analysis of microparticles generated from exploding wires. Using only the image frames and knowledge of the intrinsic properties of the cameras, a Python code was written to identify the particles, automatically calibrate the relative image positions, and extract trajectory data. After identifying approximately 50 particles based on the timing of secondary particle explosions, the eight point and random sample consensus algorithms were used to determine the geometric correlation between the cameras. Over 100 particle matches were found between the two camera views. These correlated trajectories were used in subsequent 3D track reconstruction and analysis of the physics behind the particle motion. The 3D reconstruction resulted in accurate positioning of the particles with respect to the experimental setup. The particle motion was consistent with the effects of a 1 g gravitational field modified by drag forces. The methods and analyses presented here can be used in many facets of high temperature plasma diagnostics.
关键词： stereo images,automatic calibration,plasma diagnostics,particle trajectories,3D reconstruction,exploding wire
更新于2025-09-10 09:29:36