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two photon

Jianming Zhang, Yue Huang, Lei Jin, Federico Rosei, Fiorenzo Vetrone, Jerome P Claverie
We report the two-step synthesis of a core@shell nanohybrid material for visible-to-near-infrared (NIR) photocatalysis. The core is constituted of NaGdF4:Er(3+), Yb(3+) upconverting nanoparticles (UCNPs). A bismuth ferrite (BFO) shell is assembled around the UCNPs via a hydrothermal process. The photocatalytic degradation assays of organic compounds of methylene orange and 4-chlorophenol reveal that core@shell nanostructures possess remarkably enhanced reaction activity under visible and NIR irradiation, compared to the BFO powder alone and the BFO-UCNP mixture...
February 17, 2017: ACS Applied Materials & Interfaces
Pirmin H Lakner, Michael G Monaghan, Yvonne Möller, Monilola A Olayioye, Katja Schenke-Layland
Fluorescence lifetime imaging microscopy (FLIM) can measure and discriminate endogenous fluorophores present in biological samples. This study seeks to identify FLIM as a suitable method to non-invasively detect a shift in cellular metabolic activity towards glycolysis or oxidative phosphorylation in 3D Caco-2 models of colorectal carcinoma. These models were treated with potassium cyanide or hydrogen peroxide as controls, and epidermal growth factor (EGF) as a physiologically-relevant influencer of cell metabolic behaviour...
February 13, 2017: Scientific Reports
Zhong-Xiao Man, Yun-Jie Xia, Nguyen Ba An
We theoretically study wave-particle duality of two entangled photons in the spirit of quantum version of delayed-choice experiments using Hadamard gate controlled by the quantum state of an ancilla and show that the two photons may globally exhibit particle-like, wave-like or simultaneously both particle-like and wave-like behavior. We prove that the obtained results cannot be satisfactorily explained by any hidden-variable theory. We also propose an efficient and experimentally feasible scheme without using any ancilla and controlled-gates to directly (i...
February 13, 2017: Scientific Reports
Anirban Kundu, Renu Rani, Kiran S Hazra
The century-old controversy over two contradicting theories on radiation pressure of light proposed by Abraham and Minkowski can come to an end if there is a direct method to measure the surface deformation of the target material due to momentum transfer of photons. Here we have investigated the effect of radiation pressure on the surface morphology of Graphene Oxide (GO) film, experienced due to low power focused laser irradiation. In-depth investigation has been carried out to probe the bending of the GO surface due to radiation pressure by Atomic Force Microscopy (AFM) and subsequently the uniaxial strain induced on the GO film has been probed by Raman Spectroscopy...
February 13, 2017: Scientific Reports
Pawan Kumar, Satbir Singh, V N Singh, Nidhi Singh, R K Gupta, Bipin Kumar Gupta
A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho(3+)0.02/Yb(3+)0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively...
February 13, 2017: Scientific Reports
C Evain, E Roussel, M Le Parquier, C Szwaj, M-A Tordeux, J-B Brubach, L Manceron, P Roy, S Bielawski
In recent synchrotron radiation facilities, the use of short (picosecond) electron bunches is a powerful method for producing giant pulses of terahertz coherent synchrotron radiation. Here we report on the first direct observation of these pulse shapes with a few picoseconds resolution, and of their dynamics over a long time. We thus confirm in a very direct way the theories predicting an interplay between two physical processes. Below a critical bunch charge, we observe a train of identical THz pulses (a broadband Terahertz comb) stemming from the shortness of the electron bunches...
February 3, 2017: Physical Review Letters
J Du, M Zhang, Z Guo, J Chen, X Zhu, G Hu, P Peng, Z Zheng, H Zhang
We fabricate ultrasmall phosphorene quantum dots (PQDs) with an average size of 2.6 ± 0.9 nm using a liquid exfoliation method involving ultrasound probe sonication followed by bath sonication. By coupling the as-prepared PQDs with microfiber evanescent light field, the PQD-based saturable absorber (SA) device exhibits ultrafast nonlinear saturable absorption property, with an optical modulation depth of 8.1% at the telecommunication band. With the integration of the all-fiber PQD-based SA, a continuous-wave passively mode-locked erbium-doped (Er-doped) laser cavity delivers stable, self-starting pulses with a pulse duration of 0...
February 17, 2017: Scientific Reports
Zhen Zhao, Tanja Vajen, Ela Karshovska, Annemiek Dickhout, Martin M Schmitt, Remco T A Megens, Philipp von Hundelshausen, Thomas A Koeppel, Tilman M Hackeng, Christian Weber, Rory R Koenen
Platelets play an important role in the pathogenesis of vascular remodelling after injury. Junctional adhesion molecule A (JAM-A) was recently described to regulate platelet activation. Specific deletion of JAM-A from platelets resulted in increased reactivity and in accelerated progression of atherosclerosis. The aim of this study was to investigate the specific contribution of platelet-derived JAM-A to neointima formation after vascular injury. Mice with or without platelet-specific (tr)JAM-A-deficiency in an apolipoprotein e (apoe(-/-) ) background underwent wire-induced injury of the common carotid artery...
February 17, 2017: Journal of Cellular and Molecular Medicine
Matteo Morrocchi, Giovanni Ambrosi, Maria Giuseppina Bisogni, Filippo Bosi, Marco Boretto, Piergiorgio Cerello, Maria Ionica, Ben Liu, Francesco Pennazio, Maria Antonietta Piliero, Giovanni Pirrone, Vasile Postolache, Richard Wheadon, Alberto Del Guerra
BACKGROUND: Monolithic scintillators read out by arrays of photodetectors represent a promising solution to obtain high spatial resolution and the depth of interaction (DOI) of the annihilation photon. We have recently investigated a detector geometry composed of a monolithic scintillator readout on two sides by silicon photomultiplier (SiPM) arrays, and we have proposed two parameters for the DOI determination: the difference in the number of triggered SiPMs on the two sides of the detector and the difference in the maximum collected signal on a single SiPM on each side...
December 2017: EJNMMI Physics
André A Neves, Bangwen Xie, Sarah Fawcett, Israt S Alam, Timothy H Witney, Maaike M de Backer, Julia Summers, William Hughes, Sarah McGuire, Dmitry Soloviev, Jodie Miller, William J Howat, De-En Hu, Tiago B Rodrigues, David Y Lewis, Kevin M Brindle
Cell death is an important target for imaging the early response of tumors to treatment. We describe here validation of a phosphatidylserine-binding agent for detecting tumor cell death in vivo based on the C2A domain of Synaptotagmin-I. Methods: The capability of near infrared fluorophore-labeled and 99mTechnetium- and (111)Indium-labeled derivatives of C2Am for imaging tumor cell death, using planar near infrared fluorescence (NIRF) imaging and single photon computed tomography (SPECT) respectively, was evaluated in implanted and genetically engineered mouse models of lymphoma and in a human colorectal xenograft...
February 16, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
Maciej Modzel, Frederik W Lund, Daniel Wüstner
Cellular cholesterol homeostasis relies on precise control of the sterol content of organelle membranes. Obtaining insight into cholesterol trafficking pathways and kinetics by live-cell imaging relies on two conditions. First, one needs to develop suitable analogs that resemble cholesterol as closely as possible with respect to their biophysical and biochemical properties. Second, the cholesterol analogs should have good fluorescence properties. This interferes, however, often with the first requirement, such that the imaging instrumentation must be optimized to collect photons from suboptimal fluorophores, but good cholesterol mimics, such as the intrinsically fluorescent sterols, cholestatrienol (CTL) or dehydroergosterol (DHE)...
2017: Methods in Molecular Biology
M Gabriele Bixel, Anjali P Kusumbe, Saravana K Ramasamy, Kishor K Sivaraj, Stefan Butz, Dietmar Vestweber, Ralf H Adams
Measurements of flow velocities at the level of individual arterial vessels and sinusoidal capillaries are crucial for understanding the dynamics of hematopoietic stem and progenitor cell homing in the bone marrow vasculature. We have developed two complementary intravital two-photon imaging approaches to determine blood flow dynamics and velocities in multiple vessel segments by capturing the motion of red blood cells. High-resolution spatiotemporal measurements through a cranial window to determine short-time dynamics of flowing blood cells and repetitive centerline scans were used to obtain a detailed flow-profile map with hemodynamic parameters...
February 14, 2017: Cell Reports
Y Li, S Liu, D Liu, S Sun, C Kuang, Z Ding, X Liu
We propose a novel imaging method that enables the enhancement of three-dimensional resolution of confocal microscopy significantly and achieve experimentally a new fluorescence emission difference method for the first time, based on the parallel detection with a detector array. Following the principles of photon reassignment in image scanning microscopy, images captured by the detector array were arranged. And by selecting appropriate reassign patterns, the imaging result with enhanced resolution can be achieved with the method of fluorescence emission difference...
February 15, 2017: Journal of Microscopy
Daniel R Richardson, Sukesh Roy, James R Gord
Two-photon, planar laser-induced fluorescence (TP-PLIF) of carbon monoxide was performed in steady and driven flames using femtosecond (fs) laser pulses at 1 kHz. Excitation radiation at 230.1 nm (full-width at half-maximum bandwidth of 270  cm<sup>-1</sup>) was used to pump many rovibrational two-photon transitions in the B<sup>1</sup>∑<sup>+</sup>←X<sup>1</sup>∑<sup>+</sup> system. Visible fluorescence in the range 362-516 nm was captured using an image intensifier and high-speed camera...
February 15, 2017: Optics Letters
Mateusz Piekarek, Damien Bonneau, Shigehito Miki, Taro Yamashita, Mikio Fujiwara, Masahide Sasaki, Hirotaka Terai, Michael G Tanner, Chandra M Natarajan, Robert H Hadfield, Jeremy L O'Brien, Mark G Thompson
We present the generation of quantum-correlated photon pairs and subsequent pump rejection across two silicon-on-insulator photonic integrated circuits. Incoherently cascaded lattice filters are used to provide over 100 dB pass-band to stop-band contrast with no additional external filtering. Photon pairs generated in a microring resonator are successfully separated from the input pump, confirmed by temporal correlations measurements.
February 15, 2017: Optics Letters
Lin Chang, Martin H P Pfeiffer, Nicolas Volet, Michael Zervas, Jon D Peters, Costanza L Manganelli, Eric J Stanton, Yifei Li, Tobias J Kippenberg, John E Bowers
An ideal photonic integrated circuit for nonlinear photonic applications requires high optical nonlinearities and low loss. This work demonstrates a heterogeneous platform by bonding lithium niobate (LN) thin films onto a silicon nitride (Si<sub>3</sub>N<sub>4</sub>) waveguide layer on silicon. It not only provides large second- and third-order nonlinear coefficients, but also shows low propagation loss in both the Si<sub>3</sub>N<sub>4</sub> and the LN-Si<sub>3</sub>N<sub>4</sub> waveguides...
February 15, 2017: Optics Letters
Liang Yang, Dongdong Qian, Chen Xin, Zhijiang Hu, Shengyun Ji, Dong Wu, Yanlei Hu, Jiawen Li, Wenhao Huang, Jiaru Chu
In this Letter, superposed Bessel beams (SBBs) are realized by alternatively imprinting holograms of opposite-order Bessel beams along the radial direction on a spatial light modulator. The propagation invariance and non-rotation properties of SBBs are theoretically predicted and experimentally demonstrated. The focusing property of SBBs with a high numerical aperture (NA) objective is investigated with the Debye vectorial diffraction theory. Near the focal plane, a circularly distributed multiple foci pattern is achieved...
February 15, 2017: Optics Letters
Huihong Lin, Ting Yu, Gongxun Bai, Qinyuan Zhang, Jianhua Hao
Near-infrared-to-near-infrared (NIR-to-NIR) anti-Stokes luminescence from Cr<sup>3+</sup> singly doped Ca<sub>3</sub>Ga<sub>2</sub>Ge<sub>3</sub>O<sub>12</sub> (CGGG) occurs under the excitation of an 808 nm diode laser. The anti-Stokes processes vary from one photon to two photon, depending on the Cr<sup>3+</sup> content (x) in Ca<sub>3</sub>Ga<sub>2-x</sub>Cr<sub>x</sub>Ge<sub>3</sub>O<sub>12</sub>...
February 15, 2017: Optics Letters
Yejun Wang, Cade Capps, Waruna D Kulatilaka
Ultrashort-pulse (femtosecond-duration) two-photon laser-induced fluorescence (fs-TPLIF) of an inert gas tracer krypton (Kr) is investigated. A detailed spectroscopic study of fluorescence channels followed by the 5p<sup>'</sup>←←4p excitation of Kr at 204.1 nm is reported. The experimental line positions in the 750-840 nm emission region agree well with the NIST Atomic Spectra Database. The present work provides an accurate listing of relative line strengths in this spectral region. In the range of laser pulse energies investigated, a quadratic dependence was observed between the Kr-TPLIF signal and the laser pulse energy...
February 15, 2017: Optics Letters
Mohammad Khoshakhlagh, Jalil Pirayesh Islamian, Seyyed Mohammad Abedi, Babak Mahmoudian, Masoud Shayesteh Azar
BACKGROUND: Acquiring a high quality image has assigned an important concern for obtaining accurate diagnosis in nuclear medicine. Detector is a critical component of Single Photon Emission Computed Tomography (SPECT) imaging system for giving accurate information from exact pattern of radionuclide distribution in the target organ. The images are strongly affected by the attenuation, scattering, and response of the detector. The conventional detector is mainly made from sodium iodide activated by thallium [NaI(Tl)] in nuclear medicine imaging...
2017: Nuclear Medicine Review. Central & Eastern Europe
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