2,986 results match your criteria photons productivity

Facile Fabrication of Ultrasensitive Honeycomb Nano-Mesh Ultraviolet Photodetectors Based on Self-Assembled Plasmonic Architectures.

ACS Appl Mater Interfaces 2021 Jul 21. Epub 2021 Jul 21.

Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China.

The dilemma of harvesting fugacious photons by photoactive nanomaterials of limited absorption volume fundamentally hinders the photodetection at relatively lower light intensities. To address the insufficient light utilization efficiency, spatial light confinement becomes an effective and promising approach. High-performance ultraviolet (UV) photodetectors based on the self-assembled Au nanoparticle/ZnO honeycomb nano-mesh (Au NP/ZnO HN) are demonstrated through a facile solution-processed method on anodized aluminum oxide (AAO) membranes. Read More

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Assessment of multi-energy inter-pixel coincidence counters for photon counting detectors at the presence of charge sharing and pulse pileup: a simulation study.

Med Phys 2021 Jul 20. Epub 2021 Jul 20.

Independent consultant, Los Angeles, California, 90049, USA.

Purpose: Spectral distortion due to charge sharing (CS) and pulse pileup (PP) in photon counting detectors (PCDs) degrades the quality of PCD data. We recently proposed multi-energy inter-pixel coincidence counters (MEICC) that provided spectral cross-talk information related to CS. When PP was absent, the normalized Cramér-Rao lower bounds (nCRLBs) of 225-µm pixel PCDs with MEICC was comparable to those of 450-µm pixel PCD without MEICC. Read More

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Particulate photocatalytic reactors with spectrum-splitting function for artificial photosynthesis.

Phys Chem Chem Phys 2021 Jul 16. Epub 2021 Jul 16.

Toyota Central Research and Development Laboratories, Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.

We have applied spectrum splitting, which is the most reliable way for highly efficient solar energy utilization, to particulate photocatalytic reactors. We have elucidated that the spectrum splitting is feasible using plural cells/compartments, in which photocatalyst particles of different bandgaps are suspended respectively, arranged optically in series. When the particles are sufficiently small (≤20 nm in diameter), high-energy photons are absorbed in the wide-gap cell/compartment on the solar illumination side while low-energy photons reach the backside narrow-gap cell/compartment with being scarcely diffuse-reflected. Read More

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Efficient generation of ultra-broadband parametric fluorescence using chirped quasi-phase-matched waveguide devices.

Opt Express 2021 Jul;29(14):21615-21628

We present a highly efficient photon pair source using chirped quasi-phase-matched (QPM) devices with a ridge waveguide structure. We developed QPM waveguide devices with chirp rates of 3% and 6.7%. Read More

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Quantum study of reaction O( ) + H (, ) → OH + H: OH formation in strongly UV-irradiated gas.

Astron Astrophys 2021 Apr 15;648. Epub 2021 Apr 15.

Departamento de Química Física (Unidad Asociada al CSIC), Universidad Complutense de Madrid, Ciudad Universitaria, S/N, E-20840, Madrid, Spain.

The reaction between atomic oxygen and molecular hydrogen is an important one in astrochemistry as it regulates the abundance of the hydroxyl radical and serves to open the chemistry of oxygen in diverse astronomical environments. However, the existence of a high activation barrier in the reaction with ground state oxygen atoms limits its efficiency in cold gas. In this study we calculate the dependence of the reaction rate coefficient on the rotational and vibrational state of H and evaluate the impact on the abundance of OH in interstellar regions strongly irradiated by far-UV photons, where H can be efficiently pumped to excited vibrational states. Read More

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Phonon-assisted up-conversion photoluminescence of quantum dots.

Nat Commun 2021 Jul 13;12(1):4283. Epub 2021 Jul 13.

Key Laboratory of Excited-State Materials of Zhejiang Province, Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.

Phonon-assisted up-conversion photoluminescence can boost energy of an emission photon to be higher than that of the excitation photon by absorbing vibration energy (or phonons) of the emitter. Here, up-conversion photoluminescence power-conversion efficiency (power ratio between the emission and excitation photons) for CdSe/CdS core/shell quantum dots is observed to be beyond unity. Instead of commonly known defect-assisted up-conversion photoluminescence for colloidal quantum dots, temperature-dependent measurements and single-dot spectroscopy reveal the up-conversion photoluminescence and conventional down-conversion photoluminescence share the same electron-phonon coupled electronic states. Read More

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Assessment of Multienergy Interpixel Coincidence Counters (MEICC) for Charge Sharing Correction or Compensation for Photon Counting Detectors With Boxcar Signals.

IEEE Trans Radiat Plasma Med Sci 2021 Jul 17;5(4):465-475. Epub 2020 Jun 17.

Russell H. Morgan Department of Radiology and Radiological Science, the Johns Hopkins University School of Medicine, Baltimore, MD.

Recently, multi-energy inter-pixel coincidence counter (MEICC) has been proposed for charge sharing correction and compensation for photon counting detectors (PCDs), which uses energy-dependent coincidence counters to record coincident events between multiple energy windows of a pixel-of-interest and those of neighboring pixels. A Monte Carlo (MC) simulation study was performed to assess the performance of MEICC; however, the performance might have been overestimated in a previous study. The charge sharing increases the number of photons recorded at a PCD pixel at the expense of the spatial resolution, and therefore, when spatially uniform flat-field x-ray signals are used, it gives PCDs with charge sharing more signals than a PCD without charge sharing. Read More

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Billion-pixel x-ray camera (BiPC-X).

Rev Sci Instrum 2021 Apr;92(4):043708

Dartmouth College, Hanover, New Hampshire 03755, USA.

The continuing improvement in quantum efficiency (above 90% for single visible photons), reduction in noise (below 1 electron per pixel), and shrink in pixel pitch (less than 1 μm) enable billion-pixel x-ray cameras (BiPC-X) based on commercial complementary metal-oxide-semiconductor (CMOS) imaging sensors. We describe BiPC-X designs and prototype construction based on flexible tiling of commercial CMOS imaging sensors with millions of pixels. Device models are given for direct detection of low energy x rays (<10 keV) and indirect detection of higher energies using scintillators. Read More

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Designing high-power, octave spanning entangled photon sources for quantum spectroscopy.

J Chem Phys 2021 Jun;154(24):244201

Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.

Entangled photon spectroscopy is a nascent field that has important implications for measurement and imaging across chemical, biology, and materials fields. Entangled photon spectroscopy potentially offers improved spatial and temporal-frequency resolutions, increased cross sections for multiphoton and nonlinear measurements, and new abilities in inducing or measuring quantum correlations. A critical step in enabling entangled photon spectroscopies is the creation of high-flux entangled sources that can use conventional detectors as well as provide redundancy for the losses in realistic samples. Read More

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Wave chaos enhanced light trapping in optically thin solar cells.

Chaos 2021 Jun;31(6):063136

Department of Physics, Wesleyan University, Middletown, Connecticut 06459-0155, USA.

Enhancing the energy output of solar cells increases their competitiveness as a source of energy. Producing thinner solar cells is attractive, but a thin absorbing layer demands excellent light management in order to keep transmission- and reflection-related losses of incident photons at a minimum. We maximize absorption by trapping light rays to make the mean average path length in the absorber as long as possible. Read More

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Harnessing Sunlight via Molecular Photon Upconversion.

ACS Appl Mater Interfaces 2021 Jul 6;13(28):32601-32605. Epub 2021 Jul 6.

Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.

Molecular photon upconversion via triplet-triplet annihilation (TTA-UC) is an intriguing strategy to harness sub-bandgap photons and surpass the Shockley-Queisser (SQ) limit for solar energy conversion. In this perspective, we briefly summarize the progress to date harnessing TTA-UC in solar cells using both optically and electrically coupled schemes. We then highlight the efficiency limiting processes for these schemes and outline possible paths toward upconverted photocurrent contributions of >1 mA/cm. Read More

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Metabolic Reliance on Photosynthesis Depends on Both Irradiance and Prey Availability in the Mixotrophic Ciliate, cf. .

Front Microbiol 2021 17;12:642600. Epub 2021 Jun 17.

Marine Biological Section, Biological Institute, University of Copenhagen, Copenhagen, Denmark.

Many species of the ciliate genus can acquire functional chloroplasts from a wide range of algal prey and are thus classified as generalist non-constitutive mixotrophs. Little, however, is known about the influence of irradiance and prey availability on their ability to exploit the photosynthetic potential of the chloroplasts, and how this may explain their spatial and temporal distribution in nature. In this study, inorganic carbon uptake, growth, and ingestion rates were measured for cf. Read More

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Mononuclear phagocyte system blockade using extracellular vesicles modified with CD47 on membrane surface for myocardial infarction reperfusion injury treatment.

Biomaterials 2021 Jun 28;275:121000. Epub 2021 Jun 28.

Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, China; Institute of Biomedical Science, Fudan University, Shanghai, China. Electronic address:

Mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) with anti-apoptotic and anti-inflammatory properties have been intensively studied. However, rapid clearance by the mononuclear phagocyte system remains a huge barrier for the delivery of extracellular vesicle contents into target organs and restricts its wider application, particularly in the heart. CD47 is a transmembrane protein that enables cancer cells to evade clearance by macrophages through CD47 signal regulatory proteinα binding, which initiates a "don't eat me" signal. Read More

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Multiplexed PSF Engineering for Three-Dimensional Multicolor Particle Tracking.

Nano Lett 2021 07 2;21(13):5888-5895. Epub 2021 Jul 2.

Three-dimensional spatiotemporal tracking of microscopic particles in multiple colors is a challenging optical imaging task. Existing approaches require a trade-off between photon efficiency, field of view, mechanical complexity, spectral specificity, and speed. Here, we introduce multiplexed point-spread-function engineering that achieves photon-efficient, 3D multicolor particle tracking over a large field of view. Read More

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Features of the Duckweed That Support Rapid Growth under Extremes of Light Intensity.

Cells 2021 Jun 12;10(6). Epub 2021 Jun 12.

Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.

This study addresses the unique functional features of duckweed via comparison of grown under controlled conditions of 50 versus 1000 µmol photons m s and of a population in a local pond with a nearby population of the biennial weed . Principal component analysis of foliar pigment composition revealed that was similar to fast-growing annuals, while was similar to slow-growing evergreens. Overall, exhibited traits reminiscent of those of its close relatives in the family Araceae, with a remarkable ability to acclimate to both deep shade and full sunlight. Read More

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Diatom Biosilica Doped with Palladium(II) Chloride Nanoparticles as New Efficient Photocatalysts for Methyl Orange Degradation.

Int J Mol Sci 2021 Jun 23;22(13). Epub 2021 Jun 23.

Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 61-614 Poznań, Poland.

A new catalyst based on biosilica doped with palladium(II) chloride nanoparticles was prepared and tested for efficient degradation of methyl orange (MO) in water solution under UV light excitation. The obtained photocatalyst was characterized by X-ray diffraction, TEM and N adsorption/desorption isotherms. The photocatalytic degradation process was studied as a function of pH of the solution, temperature, UV irradiation time, and MO initial concentration. Read More

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Highly efficient terahertz photoconductive metasurface detectors operating at microwatt-level gate powers.

Opt Lett 2021 Jul;46(13):3159-3162

Despite their wide use in terahertz (THz) research and technology, the application spectra of photoconductive antenna (PCA) THz detectors are severely limited due to the relatively high optical gating power requirement. This originates from poor conversion efficiency of optical gate beam photons to photocurrent in materials with sub-picosecond carrier lifetimes. Here we show that using an ultra-thin (160 nm), perfectly absorbing low-temperature grown GaAs metasurface as the photoconductive channel drastically improves the efficiency of THz PCA detectors. Read More

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Low random duty-cycle errors in periodically poled KTP revealed by sum-frequency generation.

Opt Lett 2021 Jul;46(13):3049-3052

Low-noise quantum frequency conversion in periodically poled nonlinear crystals has proved challenging when the pump wavelength is shorter than the target wavelength. This is-at least in large part-a consequence of the parasitic spontaneous parametric downconversion of pump photons, whose efficiency is increased by fabrication errors in the periodic poling. Here we characterize the poling quality of commercial periodically poled bulk potassium titanyl phosphate (ppKTP) by measuring the sum-frequency generation (SFG) efficiency over a large phase mismatch range from 0 to more than 400. Read More

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Soft X-ray Atmospheric Pressure Photoionization in Liquid Chromatography-Mass Spectrometry.

Anal Chem 2021 07 1;93(27):9309-9313. Epub 2021 Jul 1.

Drug Research Program and Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland.

Soft X-ray atmospheric pressure photoionization (soft X-ray APPI) as an ionization method in liquid chromatography-mass spectrometry (LC-MS) is presented. The ionization mechanism was examined with selected test compounds in the negative ion mode, using soft X-ray APPI source emitting 4.9 keV photons. Read More

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Low-dose real-time X-ray imaging with nontoxic double perovskite scintillators.

Light Sci Appl 2020 Jun 30;9(1):112. Epub 2020 Jun 30.

State Key Laboratory of Modern Optical Instrumentation, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou, Zhejiang, China.

X-rays are widely used in probing inside information nondestructively, enabling broad applications in the medical radiography and electronic industries. X-ray imaging based on emerging lead halide perovskite scintillators has received extensive attention recently. However, the strong self-absorption, relatively low light yield and lead toxicity of these perovskites restrict their practical applications. Read More

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Competition of Several Energy-Transport Initiation Mechanisms Defines the Ballistic Transport Speed.

J Phys Chem B 2021 Jul 29;125(27):7546-7555. Epub 2021 Jun 29.

Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States.

The ballistic regime of vibrational energy transport in oligomeric molecular chains occurs with a constant, often high, transport speed and high efficiency. Such a transport regime can be initiated by exciting a chain end group with a mid-infrared (IR) photon. To better understand the wavepacket formation process, two chemically identical end groups, azido groups with normal, N-, and isotopically substituted, N-, nitrogen atoms, were tested for wavepacket initiation in compounds with alkyl chains of = 5, 10, and 15 methylene units terminated with a carboxylic acid (-a) group, denoted as NC-a and NC-a. Read More

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Low-threshold topological nanolasers based on the second-order corner state.

Light Sci Appl 2020 Jun 29;9(1):109. Epub 2020 Jun 29.

Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.

Topological lasers are immune to imperfections and disorder. They have been recently demonstrated based on many kinds of robust edge states, which are mostly at the microscale. The realization of 2D on-chip topological nanolasers with a small footprint, a low threshold and high energy efficiency has yet to be explored. Read More

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Where in the cell is my protein?

David J DeRosier

Q Rev Biophys 2021 Jun 21;54:e9. Epub 2021 Jun 21.

Brandeis University, Waltham, MA, USA.

The application of cryo-correlative light and cryo-electron microscopy (cryo-CLEM) gives us a way to locate structures of interest in the electron microscope. In brief, the structures of interest are fluorescently tagged, and images from the cryo-fluorescent microscope (cryo-FM) maps are superimposed on those from the cryo-electron microscope (cryo-EM). By enhancing cryo-FM to include single-molecule localization microscopy (SMLM), we can achieve much better localization. Read More

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Niobium nitride plasmonic perfect absorbers for tunable infrared superconducting nanowire photodetection.

Opt Express 2021 May;29(11):17087-17096

Quantum technologies such as quantum computing and quantum cryptography exhibit rapid progress. This requires the provision of high-quality photodetectors and the ability to efficiently detect single photons. Hence, conventional avalanche photodiodes for single photon detection are not the first choice anymore. Read More

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Avalanche photodetectors with photon trapping structures for biomedical imaging applications.

Opt Express 2021 Jun;29(12):19024-19033

Enhancing photon detection efficiency and time resolution in photodetectors in the entire visible range is critical to improve the image quality of time-of-flight (TOF)-based imaging systems and fluorescence lifetime imaging (FLIM). In this work, we evaluate the gain, detection efficiency, and timing performance of avalanche photodiodes (APD) with photon trapping nanostructures for photons with 450 nm and 850 nm wavelengths. At 850 nm wavelength, our photon trapping avalanche photodiodes showed 30 times higher gain, an increase from 16% to >60% enhanced absorption efficiency, and a 50% reduction in the full width at half maximum (FWHM) pulse response time close to the breakdown voltage. Read More

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Time-domain based evaluation of detection efficiency in liquid scintillation counting.

Sci Rep 2021 Jun 14;11(1):12424. Epub 2021 Jun 14.

Université Paris-Saclay, CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), 91120, Palaiseau, France.

This work explores the distribution of time intervals between signals from the photomultiplier tubes (PMTs) of a liquid scintillation counting (LSC) system when a scintillation burst caused by an ionizing particle is detected. This distribution is termed the cross-correlation distribution and it is shown that it contains information about the probability to detect a scintillation event. A theoretical model that describes the cross-correlation distribution is derived. Read More

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Enhanced Efficiency of Dye Sensitized Solar Cell Using Eu doped TiO2-ZrO2 Nanocomposite.

Recent Pat Nanotechnol 2021 Jun 14. Epub 2021 Jun 14.

Applied Physics Department, Faculty of Technology & Engineering, The M. S. University of Baroda, Vadodara, India.

Hydrothermal method was used to prepare TiO-ZrO and Eu doped TiO-ZrO nanocomposites for dye sensitized solar cell application. X ray diffraction was used to study the structural properties of prepared samples. Anatase, Rutile phases of TiO2 and Monoclinic and tetragonal phases of ZrO have been detected from XRD in prepared samples. Read More

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Luminescent AIE Dots for Anticancer Photodynamic Therapy.

Front Chem 2021 25;9:672917. Epub 2021 May 25.

National Engineering Research Center for Nanomedicine, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China.

Photodynamic therapy (PDT) is an emerging effective strategy for cancer treatment. Compared with conventional cancer therapies, such as surgery, chemotherapy, and radiotherapy, PDT has shown great promise as a next-generation cancer therapeutic strategy owing to its many advantages such as non-invasiveness, negligible observed drug resistance, localized treatment, and fewer side effects. One of the key elements in photodynamic therapy is the photosensitizer (PS) which converts photons into active cytotoxic species, namely, reactive oxygen species (ROS). Read More

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Tapered Coaxial Arrays for Photon- and Plasmon-Enhanced Light Harvesting in Perovskite Solar Cells: A Theoretical Investigation Using the Finite Element Method.

Chempluschem 2021 May 14;86(6):858-864. Epub 2021 May 14.

Key Laboratory of Applied Surface and Colloid Chemistry, National Ministry of Education, Shaanxi Engineering Lab for Advanced Energy Technology, School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.

Although there have been reports of separate studies of photon-enhanced and plasmon-enhanced light harvesting to improve perovskite solar cell (PSC) efficiency, there are none that have achieved simultaneous enhancement in both photonic and plasmonic effects in PSCs. In this work, we designed a layer of tapered coaxial humps (TCHs) to harvest both in PSCs. The light absorption behavior of the textured perovskite layer in PSCs was systematically investigated through the finite element method (FEM). Read More

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Monte Carlo calculated calibration settings for commercially available nuclear medicine ionisation chambers.

Med Phys 2021 Jun 8. Epub 2021 Jun 8.

Austin Health, 145 Studley Road, Heidelberg, VIC, 3084, Australia.

Purpose: A method for calculating nuclear medicine ionisation chamber (NMIC) calibration settings with a Monte Carlo model is presented and validated against physical measurements. This work provides Monte Carlo calculated calibration settings for select isotopes with no current manufacturer recommendations and a method by which NMIC manufacturers or standards laboratories can utilise highly detailed specifications to calculate comprehensive lists of calibration settings for general isotopes.

Methods: A Monte Carlo model of a Capintec PET series NMIC was developed and used to calculate the chamber response to relevant radioactive decay products over an energy range relevant to nuclear medicine. Read More

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