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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Electronic-Excitation Energy Transfer between Dye Molecules Adsorbed in One-Dimensional Photonic Crystals

Electronic-excitation energy transfer between molecules of Coumarin 7 (donor) and Rhodamine B (acceptor) have been experimentally investigated in one-dimensional photonic crystals based on oxidized mesoporous silicon and in a similar matrix, which does not possess the properties of a photonic crystal. The efficiencies of excitation transfer between donor and acceptor molecules have been determined based on the donor-fluorescence quenching and sensitized acceptor luminescence. It is established that the efficiency of electronic-excitation energy transfer in a photonic crystal increases in comparison with that for porous silicon.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Cobalt and Yttrium Modified TiO{sub 2} Nanotubes Based Dye-Sensitized Solar Cells for Solar-Energy Conversion

The solar-energy conversion in eosin-sensitized solar cells based on cobalt and yttrium modified TiO2 nanotubes has been studied.It is established that the doping with metal ions shifts the absorption edge for Co and Y doped titanium dioxide samples to longer and shorter wavelengths, respectively. The efficiency of solar energy conversion depends on the wide bandgap of the semiconductor anode and reaches a maximum (4.4%) for yttrium-doped TiO{sub 2} in comparison to that (4.1%) for pure titanium dioxide.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Tumor Resection Guided by Intraoperative Indocyanine Green Dye Fluorescence Angiography Results in Negative Surgical Margins and Decreased Local Recurrence in an Orthotopic Mouse Model of Osteosarcoma

Background: Surgical resection with negative margins is the foundation of extremity sarcoma management. Failure to achieve negative surgical margins can result in local recurrence (LR), a potentially devastating complication. Indocyanine green (ICG) is a US FDA-approved fluorophore previously used to guide carcinoma resections. We investigated the potential of ICG as an intraoperative guide during experimental sarcoma resection. Methods: Fifty 6-week-old immunocompetent Balb/c female mice received left proximal tibia paraphyseal injections of 5 × 10{sup 5} K7M2 murine osteosarcoma cells. Animals were separated into two groups (n = 25 each): (1) ICG-assisted surgical resection; and (2) no ICG-assisted resection. Resections were performed 4 weeks after primary tumor engraftment. All animals received 7.5 ug ICG via retro-orbital injection 12 h prior to surgery. ICG fluorescence measurements and clinical evaluations were performed 4 weeks after resection to detect LR. Results: Eleven of 25 animals from each group developed gross tumors. Four weeks after resection, group 1 had 0/11 tumor recurrences, while group 2 had recurrences in 9/11 (81.8%) experimental mice (p < 0.0002) (Fig. 2). There was a 100% NPV in group 1, and no tumor recurrence with fluorescence-free margins after the primary surgery. Group 2 had a 100% positive predictive value for the development of an LR if any fluorescent signal was present at the surgical margin after resection. Conclusion: Intraoperative ICG guidance led to reliably negative surgical margins and a diminished LR rate. Given the benign safety profile of ICG and its prior clinical success, these results could be immediately translatable to the clinical realm.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Tuning the Optical and Photophysical Properties of Boron Aza-Dipyridylmethene dyes for Optoelectronics Application

A series of substituted boron aza-dipyridylmethene (aD) compounds are explored for their attractive photophysical and electrochemical properties as fluorescent emitters for blue OLEDs. Previous work in our lab have demonstrated the synthetic ease of dipyridylmethene monomers and their interesting photophysical properties as homoleptic meso-linked dimers. Using Density Functional Theory (DFT) modeling, we combine our theoretical and experimental efforts to synthesize a library of aD compounds by replacing the meso carbon with nitrogen to destabilize the HOMO energy. The synthesized aD derivatives emit blue light with λ max between 400-460 nm and internal quantum efficiencies above 85 % . From TD-DFT calculations, estimation of the singlet and triplet energies that are deduced from fluorescence and phosphorescence emission, respectively, closely matches the experimental data of ΔE ST ≤ 0.4 eV. Aza-dipyridylmethene show promising potential as blue emitting fluorophores in OLEDs with EQE max = 4.5 %, approaching the maximum theoretical limit of fluorescent (fl) OLED of 5.5 %. Boron aza-dipyridylmethene are synthetically tunable compounds which show interesting photophysical properties for applications in organic electronics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1976

Two-wavelength dye laser

Double-pulse laser utilizes existing optical components in unique design and is used in DIAL (differential absorption LIDAR) experiments to remotely detect pollutant and trace gases in atmosphere. It can be used with any double-pulsed pump laser or two single-pulse lasers that can be sequentially pulsed within short period of time.

Browell, E. V.↗