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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Indocyanine Green Fluorescence Imaging with Lymphoscintigraphy for Sentinel Node Biopsy in Melanoma: Increasing the Sentinel Lymph Node-Positive Rate

Introduction: The goal of this study was to analyze patients who underwent a sentinel lymph node biopsy (SLNB) in melanoma with the combination of radioisotope lymphoscintigraphy and indocyanine green (ICG) fluorescence imaging to compare our true positive (TP) rate, a means to perform immediate analysis of the SLNB, with that of the literature. Methods: Consecutive cutaneous melanoma patients who underwent SLNB with lymphoscintigraphy and ICG-based fluorescence imaging by the senior author (BG) from 2012 to 2018 were prospectively enrolled. The average expected SLN-positive rate per T stage was calculated based on three studies and compared with our SLN-positive rate. Results: Overall, 574 consecutive patients were analyzed. Average Breslow thickness was 1.9 mm. A total of 1754 sentinel nodes were sampled; 1497 were identified by gamma probe signaling and ICG, 241 were identified by gamma probe signaling only, and 16 were identified by ICG only. There were 123 (21.4%) patients with at least one positive SLN; 113 (91.9%) had at least one positive node identified with both gamma probe signaling and ICG, 8 (6.5%) had positive node(s) identified with gamma probe signaling only, and 2 (1.6%) had positive node(s) identified with ICG only. There was an overall 21.4% SLN-positive rate, with 8% T1, 18.5% T2, 41.1% T3, and 52.4% T4, which is higher than the predicted rates for each stage. Conclusions: With the largest cohort of patients reported who underwent a melanoma SLNB with lymphoscintigraphy and ICG, we demonstrated that this technique results in higher SLN-positive rates than predicted. Patients are being followed but, given the TP data, knowledge of our results may foster the use of this modality to improve staging and treatment options.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Laser-induced fluorescence thermometry of supercritical CO 2 flows inside a micro-channel

This work demonstrates a thermometric technique using laser-induced fluorescence (LIF) in supercritical carbon dioxide flows in a micro-channel. Rhodamine 6G was used as a temperature-sensitive fluorescent dye. The flow conditions were at a pressure of 7.9 MPa and temperature in the range of 23°–90°C. 2D spatial distributions and time-resolved temperature profiles were obtained at this high pressure. Measured LIF signals showed close relations to the temperatures obtained from resistance temperature detectors.

Park, Suhyeon↗
DOE OSTI2022

In vitro and in vivo NIR fluorescence lifetime imaging with a time-gated SPAD camera

Near-infrared (NIR) fluorescence lifetime imaging (FLI) provides a unique contrast mechanism to monitor biological parameters and molecular events in vivo . Single-photon avalanche diode (SPAD) cameras have been recently demonstrated in FLI microscopy (FLIM) applications, but their suitability for in vivo macroscopic FLI (MFLI) in deep tissues remains to be demonstrated. Herein, we report in vivo NIR MFLI measurement with SwissSPAD2, a large time-gated SPAD camera. We first benchmark its performance in well-controlled in vitro experiments, ranging from monitoring environmental effects on fluorescence lifetime, to quantifying Förster resonant energy transfer (FRET) between dyes. Next, we use it for in vivo studies of target-drug engagement in live and intact tumor xenografts using FRET. Information obtained with SwissSPAD2 was successfully compared to that obtained with a gated intensified charge-coupled device (ICCD) camera, using two different approaches. Our results demonstrate that SPAD cameras offer a powerful technology for in vivo preclinical applications in the NIR window.

47 OTHER INSTRUMENTATION↗
DOE OSTI2012

Recovery of Red Fluorescent Protein Chromophore Maturation Deficiency through Rational Design

Red fluorescent proteins (RFPs) derived from organisms in the class Anthozoa have found widespread application as imaging tools in biological research. For most imaging experiments, RFPs that mature quickly to the red chromophore and produce little or no green chromophore are most useful. In this study, we used rational design to convert a yellow fluorescent mPlum mutant to a red-emitting RFP without reverting any of the mutations causing the maturation deficiency and without altering the red chromophore’s covalent structure. We also created an optimized mPlum mutant (mPlum-E16P) that matures almost exclusively to the red chromophore. Analysis of the structure/function relationships in these proteins revealed two structural characteristics that are important for efficient red chromophore maturation in DsRed-derived RFPs. The first is the presence of a lysine residue at position 70 that is able to interact directly with the chromophore. The second is an absence of non-bonding interactions limiting the conformational flexibility at the peptide backbone that is oxidized during red chromophore formation. Satisfying or improving these structural features in other maturation-deficient RFPs may result in RFPs with faster and more complete maturation to the red chromophore.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Sustainable LED Fluorescent Light Replacement Technology

Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable across lifecycle phases, subsystems, and environmental impact category, and can be normalized to a user-defined functional unit: Drill-down Review – These provide an in-depth look at individual lamp designs with the ability to review across subsystem or lifecycle phase.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Development of Bio-Compatible Fluorescent Sensor

The development for biocompatible fluorescent sensors is used to understand the movement and fracking of wild boar at SRS. Current fracking methods for wild boar include physical tagging, camera monitoring, and foot tracks in the soil. None of these methods are highly effective in determining the path and habits of the animals as it depends on live imaging, soil consistency (lack of rain), and potentially a gps system is tagged properly. This system allows fracking using an additive digested by the animal and released in the urine that will fluoresce when excited with a particular laser. This method helps determine the actual movements of the animals and even provide a potential prediction model based on their routine. We partnered with Ft. Gordon to utilize their animal testing expertise in determining the best material and pathway for these materials to be excreted.

47 OTHER INSTRUMENTATION↗
DOE OSTI2026

Fluorescent Particle Vertical Profiles at CoURAGE (FPVPC) Field Campaign Report

The Fluorescent Particle Vertical Profiles at CoURAGE (FPVPC) campaign was designed to characterize the vertical distribution of bioaerosol-relevant particles at the urban-rural interface sampled during the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) User Facility’s Coast-Urban-Rural Atmospheric Gradient Experiment (CoURAGE). Bioaerosols, including bacteria, fungi, viruses, pollen, spores, and biological fragments, can affect cloud formation, disease transmission, allergen exposure, and biogeochemical cycling. Although ground-level bioaerosol abundance and composition have been studied extensively, their vertical distributions remain poorly constrained across different ecosystems, source regions, and meteorological regimes. The CoURAGE deployment addresses this gap by pairing ARM tethered balloon system (TBS)vertical profiling with in situ single-particle fluorescence measurements and offline single-particle chemical analysis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Quantifying Moss Response to Metal Contaminant Exposure Using Laser-Induced Fluorescence

Tracing sources of contamination, including potentially toxic elements (PTEs), has historically been achieved through sampling and analysis of soil or biota, which are labor-intensive, costly, and destructive methods. Thus, availability of a non-destructive in situ remote sensing method for monitoring metals deposited in biota is of great interest. Laser-induced fluorescence (LIF) is an emerging spectroscopic and imaging technique that documents changes in molecular energy level in plants as a biological response to metal contamination. For a proof-of-concept study and preliminary experiment, moss was selected for experimentation due to its long history of use in tracing atmospheric deposition of PTEs. Consecutive treatments of copper chloride (CuCl2) were administered to three moss samples, simulating wet deposition every 48 h over 10 days until reaching cumulative Cu concentrations of 2.690 to 8.075 μmol/cm2. While these Cu amounts are above environmentally relevant concentrations, they allowed the best conditions for testing and fine tuning of the imaging and data processing protocols presented in this paper. Moss fluorescence was induced using both 532 nm green and 355 nm UV lasers. A CMOS camera captured images of the LIF response, and red–green–blue (RGB) decimal code values were extracted for each pixel in the images, and pixel densities of color channels from treated and untreated moss samples were compared. Results show a shift towards lower color decimal codes corresponding to increased Cu concentration. We developed and contrasted multiple quantitative analyses of color distributions and demonstrated that LIF shows great promise for remote sensing of Cu accumulation in moss at μmol/cm2 levels. Though currently, the method would be limited to highly toxic sites, it illustrates the possibility and provides a framework for development of higher-sensitivity methods to detect nmol/cm2 that are viable for urban contamination level monitoring.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2021

Effect of Solvent on Fluorescence Emission from Polyethylene Glycol-Coated Graphene Quantum Dots under Blue Light Illumination

To explore aggregate-induced emission (AIE) properties, this study adopts a one-pot hydrothermal route for synthesizing polyethylene glycol (PEG)-coated graphene quantum dot (GQD) clusters, enabling the emission of highly intense photoluminescence under blue light illumination. The hydrothermal synthesis was performed at 300 °C using o-phenylenediamine as the nitrogen and carbon sources in the presence of PEG. Three different solvents, propylene glycol methyl ether acetate (PGMEA), ethanol, and water, were used for dispersing the PEG-coated GQDs, where extremely high fluorescent emission was achieved at 530–550 nm. It was shown that the quantum yield (QY) of PEG-coated GQD suspensions is strongly dependent on the solvent type. The pristine GQD suspension tends to be quenched (i.e., QY: ~1%) when dispersed in PGMEA (aggregation-caused quenching). However, coating GQD nanoparticles with polyethylene glycol results in substantial enhancement of the quantum yield. When investigating the photoluminescence emission from PEG-coated GQD clusters, the surface tension of the solvents was within the range of from 26.9 to 46.0 mN/m. This critical index can be tuned for assessing the transition point needed to activate the AIE mechanism which ultimately boosts the fluorescence intensity. The one-pot hydrothermal route established in this study can be adopted to engineer PEG-coated GQD clusters with solid-state PL emission capabilities, which are needed for next-generation optical, bio-sensing, and energy storage/conversion devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Fluorescence Microscopy Denoising (FMD) dataset

We created a dataset - the Fluorescence Microscopy Denoising (FMD) dataset - that is dedicated to Poisson-Gaussian denoising. The dataset consists of 12,000 real fluorescence microscopy images obtained with commercial confocal, two-photon, and wide-field microscopes and representative biological samples such as BPAE cells, zebrafish, and mouse brain tissues. We use image averaging to effectively obtain ground truth images and 60,000 noisy images with different noise levels.

Image Denoising↗
DOE OSTI2013

Fluorescent sensors reporting the activity of ammonium transceptors in live cells

Ammonium serves as key nitrogen source and metabolic intermediate, yet excess causes toxicity. Ammonium uptake is mediated by ammonium transporters, whose regulation is poorly understood. While transport can easily be characterized in heterologous systems, measuring transporter activity in vivo remains challenging. Here we developed a simple assay for monitoring activity in vivo by inserting circularly-permutated GFP into conformation-sensitive positions of two plant and one yeast ammonium transceptors (‘AmTrac’ and ‘MepTrac’). Addition of ammonium to yeast cells expressing the sensors triggered concentration-dependent fluorescence intensity (FI) changes that strictly correlated with the activity of the transporter. Fluorescence-based activity sensors present a novel technology for monitoring the interaction of the transporters with their substrates, the activity of transporters and their regulation in vivo, which is particularly valuable in the context of analytes for which no radiotracers exist, as well as for cell-specific and subcellular transport processes that are otherwise difficult to track.

De Michele, Roberto↗
NASA NTRS1964

The Fluorescent Decay of CsI(T1) Excited by Charged Particles

The fluorescence from a CsI(0.08% T1) scintillator excited by charged particles which come to a stop within the scintillator has been measured for alpha particles, deuterons, and protons. In the region 0.1 to 0.6 microseconds after its initial rise, the fluorescent decay can be accurately described by a simple exponential. The characteristic time for this exponential decay has been measured at several energies up to 28.7 MeV for a particles and 7.2 MeV for protons. We have found a linear relationship between this decay time and the logarithm of the particle energy, τ = k ln E + τo, where k and τo are constants which are characteristic of the type of stopping particle.

Womack, E. A.↗
NASA NTRS1971

Apollo 15 X-ray fluorescence experiment

The X-ray fluorescence spectrometer, carried in the SIM bay of the command service module was employed principally for compositional mapping of the lunar surface while in lunar orbit, and secondarily, for X-ray astronomical observations during the trans-earth coast. The lunar surface measurements involved observations of the intensity and characteristics energy distribution of the secondary or fluorescent X-rays produced by the interaction of solar X-rays with the lunar surface. The astronomical observations consisted of relatively long periods of measurements of X-rays from pre-selected galactic sources such as Cyg-X-1 and Sco X-1 as well as from the galactic poles.

Adler, I.↗
NASA NTRS1972

X-ray fluorescence experiment

The preliminary results from the Sco X-1 and Cyg X-1 obtained from the Apollo 15 X-ray detector data are presented along with preliminary results of the X-ray fluorescence spectrometric data of the lunar surface composition. The production of the characteristic X-rays following the interaction of solar X-rays with the lunar surface is described along with the X-ray spectrometer. Preliminary analyses of the astronomical X-ray observation and the X-ray fluorescence data are presented.

Adler, I.↗
NASA NTRS1972

Fluorescence activated cell sorting.

An instrument has been developed for sorting biological cells. The cells are rendered differentially fluorescent and incorporated into a small liquid stream illuminated by a laser beam. The cells pass sequentially through the beam, and fluorescent light from the cells gives rise to electrical signals. The stream is broken into a series of uniform size drops downstream of the laser. The cell signals are used to give appropriate electrostatic charges to drops containing the cells. The drops then pass between two charged plates and are deflected to appropriate containers. The system has proved capable of providing fractions containing large numbers of viable cells highly enriched in a particular functional type.

Bonner, W. A.↗
NASA NTRS1972

Stimulated parametric fluorescence induced by picosecond pump pulses.

Stimulated parametric fluorescence emission tunable over the range from 0.96 to 1.16 microns has been obtained using a barium sodium niobate crystal pumped by a frequency-doubled and mode-locked neodymium:glass laser. The pump radiation in the form of a train of picosecond pulses produced infrared parametric fluorescence pulses, less than 10 psec in duration and with average peak powers on the order of 300 W when pumped with a power density of 300 MW/sq cm.

Rabson, T. A.↗
NASA NTRS1972

Quenching of the fluorescence of NO2

The fluorescence yield of NO2 was monitored at 25 C with incident wavelengths of 4047, 4358, and 4800A at fluorescence wavelengths of 4860, 5577, and 6300A. The NO2 pressure was varied between 0.004 and 0.080 torr. Measurements were taken both in the absence of foreign gases and in the presence of up to 30 torr. He, N2, and O2 at each NO2 pressure. In the absence of foreign gases, the self quenching follows a Stern-Volmer quenching mechanism, but foreign-gas quenching shows marked deviations from this mechanism. Both from lifetime and kinetic considerations, it is argued that the electronic state formed by absorption of the radiation cannot be the emitting state. Emission occurs from several vibrational levels of the emitting state, the various vibrational levels being formed by collisional cascade reactions. The appropriate quenching rate constant ratios were measured and tabulated. Even the two electronic state mechanism is insufficient to explain all the observations.

Braslavsky, S.↗