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https://www.readbyqxmd.com/read/29145130/photophysical-and-photochemical-insights-into-the-photodegradation-of-sulfapyridine-in-water-a-joint-experimental-and-theoretical-study
#1
Heming Zhang, Xiaoxuan Wei, Xuedan Song, Shaheen Shah, Jingwen Chen, Jianhui Liu, Ce Hao, Zhongfang Chen
For organic pollutants, photodegradation, as a major abiotic elimination process and of great importance to the environmental fate and risk, involves rather complicated physical and chemical processes of excited molecules. Herein, we systematically studied the photophysical and photochemical processes of a widely used antibiotic, namely sulfapyridine. By means of density functional theory (DFT) computations, we examined the rate constants and the competition of both photophysical and photochemical processes, elucidated the photochemical reaction mechanism, calculated reaction quantum yield (Φ) based on both photophysical and photochemical processes, and subsequently estimated the photodegradation rate constant...
October 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/29144733/a-mechanism-for-symmetry-breaking-and-shape-control-in-single-crystal-gold-nanorods
#2
Michael J Walsh, Wenming Tong, Hadas Katz-Boon, Paul Mulvaney, Joanne Etheridge, Alison M Funston
The phenomenon of symmetry breaking-in which the order of symmetry of a system is reduced despite manifest higher-order symmetry in the underlying fundamental laws-is pervasive throughout science and nature, playing a critical role in fields ranging from particle physics and quantum theory to cosmology and general relativity. For the growth of crystals, symmetry breaking is the crucial step required to generate a macroscopic shape that has fewer symmetry elements than the unit cell and/or seed crystal from which it grew...
November 16, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29143845/pulse-laser-induced-fragmentation-of-carbon-quantum-dots-a-structural-analysis
#3
Han-Wei Chu, Ju-Yi Mao, Chia-Wen Lien, Pang-Hung Hsu, Yu-Jia Li, Jui-Yang Lai, Tai-Chia Chiu, Chih-Ching Huang
Carbon quantum dots (CQDs) have attracted enormous interest in recent years owing to their low cytotoxicity, excellent biocompatibility and strong fluorescence. They have been successfully employed in sensor, bio-imaging, and drug carrier applications. A complete understanding of their core-surface structure is essential for tuning their physical and chemical properties for various applications. Conventional characterizations of CQDs are conducted with electron microscopy or spectroscopy, such as transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy...
November 16, 2017: Nanoscale
https://www.readbyqxmd.com/read/29140344/experimental-realization-of-narrowband-four-photon-greenberger-horne-zeilinger-state-in-a-single-cold-atomic-ensemble
#4
Ming-Xin Dong, Wei Zhang, Zhi-Bo Hou, Yi-Chen Yu, Shuai Shi, Dong-Sheng Ding, Bao-Sen Shi
Multi-photon entangled states not only play a crucial role in research on quantum physics but also have many applications in quantum information fields such as quantum computation, quantum communication, and quantum metrology. To fully exploit the multi-photon entangled states, it is important to establish the interaction between entangled photons and matter, which requires that photons have narrow bandwidth. Here, we report on the experimental generation of a narrowband four-photon Greenberger-Horne-Zeilinger state with a fidelity of 64...
November 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29138427/laser-thinning-and-patterning-of-mos2-with-layer-by-layer-precision
#5
Lili Hu, Xinyan Shan, Yanling Wu, Jimin Zhao, Xinghua Lu
The recently discovered novel properties of two dimensional materials largely rely on the layer-critical variation in their electronic structure and lattice symmetry. Achieving layer-by-layer precision patterning is thus crucial for junction fabrications and device engineering, which hitherto poses an unprecedented challenge. Here we demonstrate laser thinning and patterning with layer-by-layer precision in a two dimensional (2D) quantum material MoS2. Monolayer, bilayer and trilayer of MoS2 films are produced with precise vertical and lateral control, which removes the extruding barrier for fabricating novel three dimensional (3D) devices composed of diverse layers and patterns...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29134796/enhanced-electrical-and-optoelectronic-characteristics-of-few-layer-type-ii-snse-mos2-van-der-waals-heterojunctions
#6
Shengxue Yang, Minghui Wu, Bin Wang, Li-Dong Zhao, Li Huang, Chengbao Jiang, Su-Huai Wei
Van der Waals heterojunctions formed by stacking various two-dimensional (2D) materials have a series of attractive physical properties, thus offering an ideal platform for versatile electronic and optoelectronic applications. Here, we report few-layer SnSe/MoS2 van der Waals heterojunctions and study their electrical and optoelectronic characteristics. The new heterojunctions present excellent electrical transport characteristics with a distinct rectification effect and a high current on/off ratio (~ 1 × 105)...
November 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29131635/temperature-dependent-coercive-field-measured-by-a-quantum-dot-strain-gauge
#7
Yan Chen, Yang Zhang, Robert Keil, Michael Zopf, Fei Ding, Oliver G Schmidt
Coercive fields of piezoelectric materials can be strongly influenced by environmental temperature. We investigate this influence using a heterostructure consisting of a single crystal piezoelectric film and a quantum dots containing membrane. Applying electric field leads to a physical deformation of the piezoelectric film, thereby inducing strain in the quantum dots and thus modifying their optical properties. The wavelength of the quantum dot emission shows butterfly-like loops, from which the coercive fields are directly derived...
November 15, 2017: Nano Letters
https://www.readbyqxmd.com/read/29131361/modeling-the-frequency-dependent-detective-quantum-efficiency-of-photon-counting-x-ray-detectors
#8
Karl Stierstorfer
PURPOSE: To find a simple model for the frequency dependent detective quantum efficiency (DQE) of photon counting detectors in the low flux limit. METHODS: Formula for the spatial crosstalk, the noise power spectrum and the DQE of a photon counting detector working at a given threshold are derived. Parameters are probabilities for types of events like single counts in the central pixel, double counts in the central pixel and a neighboring pixel or single count in a neighboring pixel only...
November 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/29127720/breaking-the-polar-nonpolar-division-in-solvation-free-energy-prediction
#9
Bao Wang, Chengzhang Wang, Kedi Wu, Guo-Wei Wei
Implicit solvent models divide solvation free energies into polar and nonpolar additive contributions, whereas polar and nonpolar interactions are inseparable and nonadditive. We present a feature functional theory (FFT) framework to break this ad hoc division. The essential ideas of FFT are as follows: (i) representability assumption: there exists a microscopic feature vector that can uniquely characterize and distinguish one molecule from another; (ii) feature-function relationship assumption: the macroscopic features, including solvation free energy, of a molecule is a functional of microscopic feature vectors; and (iii) similarity assumption: molecules with similar microscopic features have similar macroscopic properties, such as solvation free energies...
November 11, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/29127391/cooperative-polariton-dynamics-in-feedback-coupled-cavities
#10
Bimu Yao, Y S Gui, J W Rao, S Kaur, X S Chen, W Lu, Y Xiao, H Guo, K -P Marzlin, C -M Hu
The emerging field of cavity spintronics utilizes the cavity magnon polariton (CMP) induced by magnon Rabi oscillations. In contrast to a single-spin quantum system, such a cooperative spin dynamics in the linear regime is governed by the classical physics of harmonic oscillators. It makes the magnon Rabi frequency independent of the photon Fock state occupation, and thereby restricts the quantum application of CMP. Here we show that a feedback cavity architecture breaks the harmonic-oscillator restriction...
November 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/29125495/a-dialogue-on-the-issue-of-the-quantum-brain-between-consciousness-and%C3%A2-unconsciousness
#11
Massimo Cocchi, Fabio Gabrielli, Lucio Tonello, Jack Tuszynski
In this paper, we present some diverse points of view on the issue of the quantum brain.The paper is structured in the form of opening statements by each of the co-authors followed by comments and critique presented by the other co-authors. The main focus of the discussion is on the interplay between the state of being alive and consciousness, both of which possess characteristics of quantum physical states.
November 7, 2017: Journal of Integrative Neuroscience
https://www.readbyqxmd.com/read/29118667/twistor-theory-at-fifty-from-contour-integrals-to-twistor-strings
#12
REVIEW
Michael Atiyah, Maciej Dunajski, Lionel J Mason
We review aspects of twistor theory, its aims and achievements spanning the last five decades. In the twistor approach, space-time is secondary with events being derived objects that correspond to compact holomorphic curves in a complex threefold-the twistor space. After giving an elementary construction of this space, we demonstrate how solutions to linear and nonlinear equations of mathematical physics-anti-self-duality equations on Yang-Mills or conformal curvature-can be encoded into twistor cohomology...
October 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29118395/anisotropic-attosecond-charge-carrier-dynamics-and-layer-decoupling-in-quasi-2d-layered-sns2
#13
Calley N Eads, Dmytro Bandak, Mahesh R Neupane, Dennis Nordlund, Oliver L A Monti
Strong quantum confinement effects lead to striking new physics in two-dimensional materials such as graphene or transition metal dichalcogenides. While spectroscopic fingerprints of such quantum confinement have been demonstrated widely, the consequences for carrier dynamics are at present less clear, particularly on ultrafast timescales. This is important for tailoring, probing, and understanding spin and electron dynamics in layered and two-dimensional materials even in cases where the desired bandgap engineering has been achieved...
November 8, 2017: Nature Communications
https://www.readbyqxmd.com/read/29117691/theory-of-molecular-nonadiabatic-electron-dynamics-in-condensed-phases
#14
Kazuo Takatsuka
In light of the rapid progress of ultrafast chemical dynamics driven by the pulse lasers having width as short as several tens of attoseconds, we herein develop a theory of nonadiabatic electron wavepacket dynamics in condensed phases, with which to directly track the dynamics of electronic-state mixing such as electron transfer in liquid solvents. Toward this goal, we combine a theory of path-branching representation for nonadiabatic electron wavepacket dynamics in vacuum {a mixed quantum-classical representation, Yonehara and Takatsuka [J...
November 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29117688/mnnio3-revisited-with-modern-theoretical-and-experimental-methods
#15
Allison L Dzubak, Chandrima Mitra, Michael Chance, Stephen Kuhn, Gerald E Jellison, Athena S Sefat, Jaron T Krogel, Fernando A Reboredo
MnNiO3 is a strongly correlated transition metal oxide that has recently been investigated theoretically for its potential application as an oxygen-evolution photocatalyst. However, there is no experimental report on critical quantities such as the band gap or bulk modulus. Recent theoretical predictions with standard functionals such as LDA+U and HSE show large discrepancies in the band gaps (about 1.23 eV), depending on the nature of the functional used. Hence there is clearly a need for an accurate quantitative prediction of the band gap to gauge its utility as a photocatalyst...
November 7, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29116805/experimental-verification-of-entanglement-generated-in-a-plasmonic-system
#16
Frederik Dieleman, Mark Tame, Yannick Sonnefraud, M S Kim, Stefan A Maier
A core process in many quantum tasks is the generation of entanglement. It is being actively studied in a variety of physical settings -- from simple bipartite systems to complex multipartite systems. In this work we experimentally study the generation of bipartite entanglement in a nanophotonic system. Entanglement is generated via the quantum interference of two surface plasmon polaritons in a beamsplitter structure, {\it i.e.}~utilising the Hong-Ou-Mandel (HOM) effect, and its presence is verified using quantum state tomography...
November 8, 2017: Nano Letters
https://www.readbyqxmd.com/read/29116197/pathway-towards-high-efficiency-eu-doped-gan-light-emitting-diodes
#17
Ioannis E Fragkos, Chee-Keong Tan, Volkmar Dierolf, Yasufumi Fujiwara, Nelson Tansu
A physically intuitive current injection efficiency model for a GaN:Eu quantum well (QW) has been developed to clarify the necessary means to achieve device quantum efficiency higher than the state-of-the-art GaN:Eu system for red light emission. The identification and analysis of limiting factors for high internal quantum efficiencies (IQE) are accomplished through the current injection efficiency model. In addition, the issue of the significantly lower IQE in the electrically-driven GaN:Eu devices in comparison to the optically-pumped GaN:Eu devices is clarified in the framework of this injection efficiency model...
November 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29116092/observation-of-the-exceptional-point-in-cavity-magnon-polaritons
#18
Dengke Zhang, Xiao-Qing Luo, Yi-Pu Wang, Tie-Fu Li, J Q You
Magnon-polaritons are hybrid light-matter quasiparticles originating from the strong coupling between magnons and photons. They have emerged as a potential candidate for implementing quantum transducers and memories. Owing to the dampings of both photons and magnons, the polaritons have limited lifetimes. However, stationary magnon-polariton states can be reached by a dynamical balance between pumping and losses, so the intrinsically nonequilibrium system may be described by a non-Hermitian Hamiltonian. Here we design a tunable cavity quantum electrodynamics system with a small ferromagnetic sphere in a microwave cavity and engineer the dissipations of photons and magnons to create cavity magnon-polaritons which have non-Hermitian spectral degeneracies...
November 8, 2017: Nature Communications
https://www.readbyqxmd.com/read/29116086/quantum-wave-mixing-and-visualisation-of-coherent-and-superposed-photonic-states-in-a-waveguide
#19
A Yu Dmitriev, R Shaikhaidarov, V N Antonov, T Hönigl-Decrinis, O V Astafiev
Superconducting quantum systems (artificial atoms) have been recently successfully used to demonstrate on-chip effects of quantum optics with single atoms in the microwave range. In particular, a well-known effect of four wave mixing could reveal a series of features beyond classical physics, when a non-linear medium is scaled down to a single quantum scatterer. Here we demonstrate the phenomenon of quantum wave mixing (QWM) on a single superconducting artificial atom. In the QWM, the spectrum of elastically scattered radiation is a direct map of the interacting superposed and coherent photonic states...
November 7, 2017: Nature Communications
https://www.readbyqxmd.com/read/29115349/triplet-sensitized-photon-upconversion-in-deep-eutectic-solvents
#20
Yoichi Murakami, Sudhir Kumar Das, Yuki Himuro, Satoshi Maeda
Photon upconversion (UC) is a technology that can increase solar utilization efficiencies in broad photoenergy conversion systems by converting lower-energy photons into usable higher-energy photons. Recently, UC using triplet-triplet annihilation (TTA) of organic molecules has drawn attention because it is presently the only method applicable to weak and noncoherent light. To date, many attempts have been made to realize this UC technology in forms suitable for applications, but they typically suffer from either high cost or insufficient stability and/or safety of materials...
November 8, 2017: Physical Chemistry Chemical Physics: PCCP
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