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Ibrahim Danad, Pieter G Raijmakers, Roel S Driessen, Jonathon Leipsic, Rekha Raju, Chris Naoum, Juhani Knuuti, Maija Mäki, Richard S Underwood, James K Min, Kimberly Elmore, Wynand J Stuijfzand, Niels van Royen, Igor I Tulevski, Aernout G Somsen, Marc C Huisman, Arthur A van Lingen, Martijn W Heymans, Peter M van de Ven, Cornelis van Kuijk, Adriaan A Lammertsma, Albert C van Rossum, Paul Knaapen
Importance: At present, the choice of noninvasive testing for a diagnosis of significant coronary artery disease (CAD) is ambiguous, but nuclear myocardial perfusion imaging with single-photon emission tomography (SPECT) or positron emission tomography (PET) and coronary computed tomography angiography (CCTA) is predominantly used for this purpose. However, to date, prospective head-to-head studies are lacking regarding the diagnostic accuracy of these imaging modalities. Furthermore, the combination of anatomical and functional assessments configuring a hybrid approach may yield improved accuracy...
August 16, 2017: JAMA Cardiology
Amy Lynne Bondy, Rachel M Kirpes, Rachel Leah Merzel, Kerri A Pratt, Mark M Banaszak Holl, Andrew P Ault
Chemical analysis of atmospheric aerosols is an analytical challenge, as aerosol particles are complex chemical mixtures that can contain hundreds to thousands of species in attoliter volumes at the most abundant sizes in the atmosphere (~100 nm). These particles have global impacts on climate and health, but there are few methods available that combine imaging and the detailed molecular information from vibrational spectroscopy for individual particles <500 nm. Herein, we show the first application of atomic force microscopy with infrared spectroscopy (AFM-IR) to detect trace organic and inorganic species and probe intraparticle chemical variation in individual particles down to 150 nm...
August 16, 2017: Analytical Chemistry
Lucas Schwob, Mathieu Lalande, Dmitrii Egorov, Jimmy Rangama, Ronnie Hoekstra, Violaine Vizcaino, Thomas Schlathölter, Jean-Christophe Poully
We report on an experimental single-photon absorption study on gas-phase protonated collagen peptides employing a combination of mass spectrometry and synchrotron radiation. Partial ion yields for the main photoabsorption products vary steadily with photon energy over the range from 14 to 545 eV. At low energy, non-dissociative photoionisation competes with neutral molecule loss from the precursor ion, whereas fragmentation of the peptide backbone dominates at soft X-ray energies. Neutral molecule losses from the ionised peptide are found to have low energy barriers and most likely involve amino-acid residue side-chains with radical character, in particular aspartic acid...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Naila Khalid, Asma Iqbal, Humaira Masood Siddiqi, O Ok Park
A series of poly(azomethine)s (PAMs) were synthesized from N(1)-(4-aminophenyl)-N(1)-(4-phenoxyphenyl)benzene-1,4-diamine (DA) and various dialdehydes to investigate the influence of structure of polymer chain and triphenylamine-based phenoxy pendant group on the optoelectronic properties. The structural characterization of the resulting poly(azomethine)s was carried out by solubility test, gel permeation chromatography, viscosity measurement, fourier transform infrared (FTIR) spectral and CHN elemental analysis...
August 15, 2017: Journal of Fluorescence
M Oujja, S Psilodimitrakopoulos, E Carrasco, M Sanz, A Philippidis, A Selimis, P Pouli, G Filippidis, M Castillejo
The nonlinear optical microscopy (NLM) modalities of Multi-Photon Excited Fluorescence (MPEF) and Third Harmonic Generation (THG) have been combined in this work to characterize as a function of depth with micrometric resolution the type and extent of morphological and photochemical modifications that take place upon ultraviolet (UV) pulsed laser removal of a dammar varnish layer applied on a photosensitive substrate. The latter consists on a layer of the synthetic polymer poly-methyl methacrylate doped with a photosensitizer, the aromatic compound 1,4-di[2-(5-phenyloxazolyl)] benzene, that strongly fluoresces upon UV light illumination...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
Ivan Hidrovo, Joyoni Dey, Megan E Chesal, Dmytro Shumilov, Narayan Bhusal, J Michael Mathis
BACKGROUND: Over the last decade, several theoretical tumor-models have been developed to describe tumor growth. Oncology imaging is performed using various modalities including computed tomography (CT), magnetic resonance imaging (MRI), single-photon emission computed tomography (SPECT) and fluorodeoxyglucose-positron emission tomography (FDG-PET). Our goal is to extract useful, otherwise hidden, quantitative biophysical parameters (such as growth-rate, tumor-necrotic-factor, etc.) from these serial images of tumors by fitting mathematical models to images...
June 2017: Quantitative Imaging in Medicine and Surgery
Golam Haider, Rini Ravindranath, Tzu-Pei Chen, Prathik Roy, Pradip Kumar Roy, Shu-Yi Cai, Huan-Tsung Chang, Yang-Fang Chen
The occurrence of zero effective mass of electrons at the vicinity of the Dirac point is expected to create new paradigms for scientific research and technological applications, but the related discoveries are rather limited. Here, we demonstrate that a simple architecture composed of graphene quantum dots sandwiched by graphene layers can exhibit several intriguing features, including the Dirac point induced ultralow-threshold laser, giant peak-to-valley ratio (PVR) with ultra-narrow spectra of negative differential resistance and quantum oscillations of current as well as light emission intensity...
August 15, 2017: Nature Communications
Wen Wang, Shudu Yang, Ashu Wang
Graphene, a two-dimensional material, has a wide range of unique properties and could be used in the development of varieties of mechanic, electronic and photonic devices, therefore methods to synthesis large-area high-quality graphene films are urgently required. Chemical vapor deposition (CVD) has been of particular interest recently due to its simplicity and low cost. However, because of the mismatch of thermal expansion coefficients, high densities of wrinkles are commonly observed. Despite their prevalence and potential impact on large-scale graphene properties, relatively little is known about their structural morphology and formation mechanism...
August 15, 2017: Scientific Reports
Matthias Wurdack, Nils Lundt, Martin Klaas, Vasilij Baumann, Alexey V Kavokin, Sven Höfling, Christian Schneider
Strong light matter coupling between excitons and microcavity photons, as described in the framework of cavity quantum electrodynamics, leads to the hybridization of light and matter excitations. The regime of collective strong coupling arises, when various excitations from different host media are strongly coupled to the same optical resonance. This leads to a well-controllable admixture of various matter components in three hybrid polariton modes. Here, we study a cavity device with four embedded GaAs quantum wells hosting excitons that are spectrally matched to the A-valley exciton resonance of a MoSe2 monolayer...
August 15, 2017: Nature Communications
Alexander Chi, Lien-Chun Lin, Sijin Wen, Haijuan Yan, Wen-Chien Hsi
PURPOSE: The aim of the present study was to compare the dose distribution generated from photon volumetric modulated arc therapy (VMAT), intensity modulated proton therapy (IMPT), and intensity modulated carbon ion therapy (IMCIT) in the delivery of hypo-fractionated thoracic radiotherapy. METHODS AND MATERIALS: Ten selected patients who underwent thoracic particle therapy between 2015 and 2016 were re-planned to receive a relative biological effectiveness (RBE) weighted dose of 60 Gy (i...
August 15, 2017: Radiation Oncology
Degao Wang, Matthew V Sheridan, Bing Shan, Byron H Farnum, Seth L Marquard, Benjamin D Sherman, Michael S Eberhart, Animesh Nayak, Christopher Dares, Atanu Das, R Morris Bullock, Thomas J Meyer
In a Dye Sensitized Photoelectrosynthesis Cell (DSPEC) the relative orientation of the catalyst and chromophore plays an important role in determining the device efficiency. Here we introduce a new, robust atomic layer deposition (ALD) procedure for the preparation of molecular chromophore-catalyst assemblies on wide bandgap semiconductors. In this procedure, solution deposited, phosphonate derivatized metal complexes on metal oxide surfaces are treated with reactive metal reagents in the gas phase by ALD to form an outer metal ion bridging group which can bind a second phosphonate containing species from solution to establish a R1-PO2-O-M-O-PO2-R2 type surface assembly...
August 15, 2017: Journal of the American Chemical Society
Sebastian A Schulz, Jeremy Upham, Liam O'Faolain, Robert W Boyd
Slow light photonic crystal waveguides tightly compress propagating light and increase interaction times, showing immense potential for all-optical delay and enhanced light-matter interactions. Yet, their practical application has largely been limited to moderate group index values (<100), due to a lack of waveguides that reliably demonstrate slower light. This limitation persists because nearly all such research has focused on a single photonic crystal lattice type: the triangular lattice. Here, we present waveguides based on the kagome lattice that demonstrate an intrinsically high group index and exhibit slow and stopped light...
August 15, 2017: Optics Letters
S Longhi
An arbitrarily shaped optical potential on a discrete photonic lattice, which transversely drifts at a speed greater than the maximum speed allowed by the light cone of the lattice band, becomes reflectionless. Such an intriguing result, which arises from the discrete translational symmetry of the lattice, is peculiar to discretized light and does not have any counterpart for light scattering in continuous optical media. A drifting non-Hermitian optical potential of the Kramers-Kronig type also is an invisible potential, i...
August 15, 2017: Optics Letters
Zhi-Xiong Xiao, Yong-Zhen Huang, Yue-De Yang, Min Tang, Jin-Long Xiao
Modulation bandwidth enhancements are investigated for coupled twin-square microcavity lasers due to photon-photon resonance effect. For a coupled twin-square microcavity laser with the square side length of 20 μm, we demonstrate the increase of 3-dB modulation bandwidth from 9.6 GHz to 19.5 GHz, by adjusting the resonance mode wavelength interval between two square microcavities. The enhanced modulation bandwidth is explained by rate equation analysis, and numerical simulations are conducted for large signal modulation with improved eye-diagrams at 40 Gbit/s...
August 15, 2017: Optics Letters
Peixuan Li, Wei Pan, Xihua Zou, Lianshan Yan, Yan Pan
A photonic radiofrequency (RF) filter with two complementary bandpass and bandstop responses that is capable of simultaneously providing a single transmission channel at one port and a notch rejection channel at the other port is proposed. An integrated polarization division-multiplexing Mach-Zehnder modulator and the in-fiber stimulated Brillouin scattering effect are used to control the amplitudes and phases of the RF modulation sidebands along two orthogonal states of polarization to generate two complementary bandpass and bandstop responses at two output ports, respectively...
August 15, 2017: Optics Letters
Feng Zhou, Wei Ji
We develop a theoretical model to quantify the two-photon absorption (2 PA) coefficients of monolayer MoS2. Based on two-dimensional excitons, our model reveals the 2 PA coefficient spectrum on the order of 0.01-0.1 cm/MW in the near-infrared for monolayer MoS2. As compared to the band theory for bulk semiconductors, these coefficients are enhanced by at least one order of magnitude. Our model is in agreement with light-intensity-dependent photocurrent measurements on a monolayer MoS2, subband photodetector with femtosecond laser pulses...
August 15, 2017: Optics Letters
Dan Zhang, Xing Liu, Lingmeng Yang, Xinghua Li, Zhaoyang Zhang, Yanpeng Zhang
We have experimentally generated a vortex six-wave mixing (SWM) signal via a photonic band gap structure in a hot atomic ensemble. The output SWM carrying orbital angular momentum, transferred from a probe beam, has the interaction with the nonlinear effect in the multilevel atomic system. Our results show that a spatial SWM image can be modulated by the detunings and intensities of the related generating fields. Also, the nonreciprocal feature of the SWM signal is demonstrated. Such characteristics can potentially be used in information processing...
August 15, 2017: Optics Letters
Zejie Yu, Haoran Cui, Xiankai Sun
Polarization control of light waves is an important technique in optical communication and signal processing. On-chip polarization rotation from the fundamental transverse-electric (TE00) mode to the fundamental transverse-magnetic (TM00) mode is usually difficult because of their large effective refractive index difference. Here, we demonstrate an on-chip wideband polarization rotator designed with a genetic algorithm to convert the TE00 mode into the TM00 mode within a footprint of 0.96 μm ×4.2  μm...
August 15, 2017: Optics Letters
Yuting Yang, Tao Xu, Yun Fei Xu, Zhi Hong Hang
Interface states in photonic crystals provide efficient approaches to control the flow of light. Photonic Zak phase determines the bulk band properties of photonic crystals, and, by assembling two photonic crystals with different bulk band properties together, deterministic interface states can be realized. By translating each unit cell of a photonic crystal by half the lattice constant, another photonic crystal with identical common gaps but a different Zak phase at each photonic band can be created. By assembling these two photonic crystals together, multiband waveguide can thus be easily created and then experimentally characterized...
August 15, 2017: Optics Letters
Samuel Serna, Nicolas Dubreuil
The characterization of a third-order nonlinear integrated waveguide is reported for the first time by means of a top-hat dispersive-scan (D-Scan) technique, a temporal analog of the top-hat Z-Scan. With a single laser beam, and by carrying two counterdirectional nonlinear transmissions to assess the input and output coupling efficiencies, a novel procedure is described leading to accurate measurement of the TPA figure of merit, the effective two-photon absorption (TPA), and optical Kerr (including the sign) coefficients...
August 15, 2017: Optics Letters
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