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https://www.readbyqxmd.com/read/28645036/influence-of-surface-states-on-blinking-characteristics-of-single-colloidal-cdse-cds-zns-core-multishell-quantum-dot
#1
Hao Xu, Hjalmar Brismar, Ying Fu
We carefully characterized the fluorescence blinking of single colloidal CdSe-CdS/ZnS core-multishell quantum dots (QDs) with different surface modifications, including octadecylamine (ODA) coated QDs dispersed in chloroform, aqueous 3-mercaptopropionic acids (3MPA) coated QDs in HEPES solution treated by Ca(2+) ions and ethylene glycol tetraacetic acid (EGTA, Ca(2+) chelator), and aqueous 3MPA-QDs treated by glycerol. It was found that the on- and off-state probability density distributions displayed different rules...
June 16, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28644668/strong-light-matter-interactions-in-single-open-plasmonic-nanocavities-at-the-quantum-optics-limit
#2
Renming Liu, Zhang-Kai Zhou, Yi-Cong Yu, Tengwei Zhang, Hao Wang, Guanghui Liu, Yuming Wei, Huanjun Chen, Xue-Hua Wang
Reaching the quantum optics limit of strong light-matter interactions between a single exciton and a plasmon mode is highly desirable, because it opens up possibilities to explore room-temperature quantum devices operating at the single-photon level. However, two challenges severely hinder the realization of this limit: the integration of single-exciton emitters with plasmonic nanostructures and making the coupling strength at the single-exciton level overcome the large damping of the plasmon mode. Here, we demonstrate that these two hindrances can be overcome by attaching individual J aggregates to single cuboid Au@Ag nanorods...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644661/soft-photon-and-graviton-theorems-in-effective-field-theory
#3
Henriette Elvang, Callum R T Jones, Stephen G Naculich
Extensions of the photon and graviton soft theorems are derived in 4D local effective field theories with massless particles of arbitrary spin. We prove that effective operators can result in new terms in the soft theorems at subleading order for photons and subsubleading order for gravitons. The new soft terms are unique, and we provide a complete classification of all local operators responsible for such modifications. We show that no local operators can modify the subleading soft graviton theorem. The soft limits are taken in a manifestly on-locus manner using a complex double deformation of the external momenta...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644642/probing-electron-phonon-interaction-through-two-photon-interference-in-resonantly-driven-semiconductor-quantum-dots
#4
Antoine Reigue, Jake Iles-Smith, Fabian Lux, Léonard Monniello, Mathieu Bernard, Florent Margaillan, Aristide Lemaitre, Anthony Martinez, Dara P S McCutcheon, Jesper Mørk, Richard Hostein, Valia Voliotis
We investigate the temperature dependence of photon coherence properties through two-photon interference (TPI) measurements from a single quantum dot (QD) under resonant excitation. We show that the loss of indistinguishability is related only to the electron-phonon coupling and is not affected by spectral diffusion. Through these measurements and a complementary microscopic theory, we identify two independent separate decoherence processes, both of which are associated with phonons. Below 10 K, we find that the relaxation of the vibrational lattice is the dominant contribution to the loss of TPI visibility...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644636/path-controlled-time-reordering-of-paired-photons-in-a-dressed-three-level-cascade
#5
Samir Bounouar, Max Strauß, Alexander Carmele, Peter Schnauber, Alexander Thoma, Manuel Gschrey, Jan-Hindrik Schulze, André Strittmatter, Sven Rodt, Andreas Knorr, Stephan Reitzenstein
The two-photon dressing of a "three-level ladder" system, here the ground state, the exciton, and the biexciton of a semiconductor quantum dot, leads to new eigenstates and allows one to manipulate the time ordering of the paired photons without unitary postprocessing. We show that, after spectral postselection of the single dressed states, the time ordering of the cascaded photons can be removed or conserved. Our joint experimental and theoretical study demonstrates the high potential of a "ladder" system to be a versatile source of orthogonally polarized, bunched or antibunched pairs of photons...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28643802/optogenetic-rewiring-of-thalamocortical-circuits-to-restore-function-in-the-stroke-injured-brain
#6
Kelly A Tennant, Stephanie L Taylor, Emily R White, Craig E Brown
To regain sensorimotor functions after stroke, surviving neural circuits must reorganize and form new connections. Although the thalamus is critical for processing and relaying sensory information to the cortex, little is known about how stroke affects the structure and function of these connections, or whether a therapeutic approach targeting these circuits can improve recovery. Here we reveal with in vivo calcium imaging that stroke in somatosensory cortex dampens the excitability of surviving thalamocortical circuits...
June 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643753/dosimetric-characteristic-of-physical-wedge-versus-enhanced-dynamic-wedge-based-on-monte-carlo-simulations
#7
Seied Rabie Mahdavi, Ghazale Geraily, Ahmad Mostaar, Arman Zia, Golbarg Esmaili, Somayeh Farahani
AIM OF STUDY: Physical wedges (PWs) are widely used in radiotherapy to obtain tilted isodose curves, but they alter beam quality. Dynamic wedges (DWs) using moving collimator overcome this problem, but measuring their beam data is not simple. The main aim of this study is to obtain all dosimetric parameters of DWs produced by Varian 2100CD with Monte Carlo simulation and compare them to those from PWs. SUBJECTS AND METHODS: To simulate 6 MV photon beams equipped with PW and DW, BEAMnrc code was used...
April 2017: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/28643745/adjuvant-hypofractionated-radiation-in-carcinoma-breast-photon-versus-electron-comparison-of-treatment-outcome
#8
G Prameela Chelakkot, Rahul Ravind, K Sruthi, Namrata Chigurupati, Sanketh Kotne, Raghavendra Holla, Ram Madhavan, M Dinesh
BACKGROUND: Breast cancer tissue is sensitive to hypofractionation. This is an analysis of patients treated with hypofractionated protocols since 2009, at our tertiary cancer center. METHODS: Details of breast cancer patients treated with adjuvant hypofractionated external beam radiation therapy (EBRT) from January 2009 to December 2014 were retrieved and analyzed. RESULTS: One thousand seven hundred and eighty patients received adjuvant EBRT during this period...
April 2017: Journal of Cancer Research and Therapeutics
https://www.readbyqxmd.com/read/28642483/masking-of-a-circadian-behavior-in-larval-zebrafish-involves-the-thalamo-habenula-pathway
#9
Qian Lin, Suresh Jesuthasan
Changes in illumination can rapidly influence behavior that is normally controlled by the circadian clock. This effect is termed masking. In mice, masking requires melanopsin-expressing retinal ganglion cells that detect blue light and project to the thalamus. It is not known whether masking is wavelength-dependent in other vertebrates, nor is it known whether the thalamus is also involved or how it influences masking. Here, we address these questions in zebrafish. We find that diel vertical migration, a circadian behavior in larval zebrafish, is effectively triggered by blue, but not by red light...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28642481/deterministic-radiative-coupling-of-two-semiconductor-quantum-dots-to-the-optical-mode-of-a-photonic-crystal-nanocavity
#10
M Calic, C Jarlov, P Gallo, B Dwir, A Rudra, E Kapon
A system of two site-controlled semiconductor quantum dots (QDs) is deterministically integrated with a photonic crystal membrane nano-cavity. The two QDs are identified via their reproducible emission spectral features, and their coupling to the fundamental cavity mode is established by emission co-polarization and cavity feeding features. A theoretical model accounting for phonon interaction and pure dephasing reproduces the observed results and permits extraction of the light-matter coupling constant for this system...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28640817/an-r-camp1-07-reporter-mouse-for-cell-type-specific-expression-of-a-sensitive-red-fluorescent-calcium-indicator
#11
Philipp Bethge, Stefano Carta, Dayra A Lorenzo, Ladan Egolf, Despoina Goniotaki, Linda Madisen, Fabian F Voigt, Jerry L Chen, Bernard Schneider, Masamichi Ohkura, Junichi Nakai, Hongkui Zeng, Adriano Aguzzi, Fritjof Helmchen
Genetically encoded calcium indicators (GECIs) enable imaging of in vivo brain cell activity with high sensitivity and specificity. In contrast to viral infection or in utero electroporation, indicator expression in transgenic reporter lines is induced noninvasively, reliably, and homogenously. Recently, Cre/tTA-dependent reporter mice were introduced, which provide high-level expression of green fluorescent GECIs in a cell-type-specific and inducible manner when crossed with Cre and tTA driver mice. Here, we generated and characterized the first red-shifted GECI reporter line of this type using R-CaMP1...
2017: PloS One
https://www.readbyqxmd.com/read/28640628/oriented-gold-nanorods-and-gold-nanorod-chains-within-smectic-liquid-crystal-topological-defects
#12
Brigita Rožič, Jérôme Fresnais, Celine Molinaro, Joseph Calixte, Shivakumar Umadevi, Stephanie Lau-Truong, Nordin Felidj, Tobias Kraus, Fabrice Charra, Vincent Dupuis, Torsten Hegmann, Celine Fiorini-Debuisschert, Bruno Gallas, Emmanuelle Lacaze
We show that the use of oriented linear arrays of smectic A defects, the so-called smectic oily streaks, enables the orientation of gold nanorods (GNRs) for a large range of GNR diameters, ranging from 7 to 48 nm, and for various ligands. For the small GNRs it enables oriented end-to-end small chains of GNRs when the density is increased from around 2 GNRs/μm(2) to around 6 GNRs/μm(2). We have characterized the orientation of single GNRs by spectrophotometry and two-photon luminescence (TPL). A strongly anisotropic absorption of the composites and an on-off switching of GNR luminescence, both controlled by incident light polarization, are observed, revealing an orientation of the GNRs mostly parallel to the oily streaks...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28638099/brilliant-x-rays-using-a-two-stage-plasma-insertion-device
#13
J A Holloway, P A Norreys, A G R Thomas, R Bartolini, R Bingham, J Nydell, R M G M Trines, R Walker, M Wing
Particle accelerators have made an enormous impact in all fields of natural sciences, from elementary particle physics, to the imaging of proteins and the development of new pharmaceuticals. Modern light sources have advanced many fields by providing extraordinarily bright, short X-ray pulses. Here we present a novel numerical study, demonstrating that existing third generation light sources can significantly enhance the brightness and photon energy of their X-ray pulses by undulating their beams within plasma wakefields...
June 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28637403/experiences-with-99mtc-hmpao-in-a-diagnostic-pathway-for-violent-patients-with-schizophrenic-spectrum-disorders
#14
Morten Jacobsen, Arvid Jensen, Guttorm Breivik Storvestre, Tone Marie Bergstrom, Diyar Nori Mohamad Rashi, Nielssen Bjorn, Wiktor Pal, Hymer Knut-Erik
Background and objective In a security ward we assessed the diagnostic contribution of single photon scintigraphy [SPECT] in our diagnostic pathway for patients with serious mental disease and a history of violence. Methods Twenty patients were examined between 2012 and 2015 and the findings compared to those in nine patients with the same diagnosis, but no history of violence. Results All violent patients had areas with reduced accumulation of 99mTc-HMPAO frontally and in the temporal lobe, in the non-violent group only two patients demonstrated these findings...
June 21, 2017: Current Radiopharmaceuticals
https://www.readbyqxmd.com/read/28636755/technical-note-combination-of-multiple-epid-imager-layers-improves-image-quality-and-tracking-performance-of-low-contrast-to-noise-objects
#15
Stephen Sf Yip, Joerg Rottmann, Haijian Chen, Daniel Morf, Rony Füglistaller, Josh Star-Lack, George Zentai, Ross Berbeco
PURPOSE: We hypothesized that combining multiple amorphous silicon flat panel layers increases photon detection efficiency in an electronic portal imaging device (EPID), improving image quality and tracking accuracy of low contrast targets during radiotherapy METHODS: The prototype imager evaluated in this study contained 4 individually programmable layers each with a copper converter layer, Gd2 O2 S scintillator and active-matrix flat panel imager (AMFPI). The imager was placed on a Varian TrueBeam linac and a Las Vegas phantom programmed with sinusoidal motion (peak-to-peak amplitude=20mm, Period=3...
June 21, 2017: Medical Physics
https://www.readbyqxmd.com/read/28636350/integrating-a-semi-transparent-fullerene-free-organic-solar-cell-in-tandem-with-a-bivo4-photoanode-for-unassisted-solar-water-splitting
#16
Yuelin Peng, Gokul V Govindaraju, Dong Ki Lee, Kyoung-Shin Choi, Trisha L Andrew
We report an unassisted solar water splitting system powered by a diketopyrrolopyrrole (DPP)-containing semi-transparent organic solar cell. Two major merits of this fullerene-free solar cell enable its integration with a BiVO4 photoanode. First is the high open circuit voltage and high fill factor displayed by this single junction solar cell, which yields sufficient power to effect water splitting when serially-connected to an appropriate electrode/catalyst. Second, the wavelength-resolved photoaction spectrum of the DPP-based solar cell has minimal overlap with that of the BiVO4 photoanode, thus ensuring that light collection across these two components can be optimized...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28636318/inverse-photonic-glasses-by-packing-bi-disperse-hollow-microspheres-with-uniform-cores
#17
Seung-Hyun Kim, Sofia Magkiriadou, Do Kyung Rhee, Doo Sung Lee, Pil J Yoo, Vinothan N Manoharan, Gi-Ra Yi
A major fabrication challenge is producing disordered photonic materials with angle-independent structural red color. Theoretical work has shown that such color can be produced by fabricating inverse photonic glasses with monodisperse, non-touching voids in a silica matrix. Here we demonstrate a route toward such materials and show that they have angle-independent red color. We first synthesize monodisperse hollow silica particles with precisely controlled shell thickness, then make glassy colloidal structures by mixing two types of hollow particles with the same core size and different shell thicknesses...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28634138/intracellular-and-transdermal-protein-delivery-mediated-by-non-covalent-interactions-with-a-synthetic-guanidine-rich-molecular-carrier
#18
Jungkyun Im, Sanket Das, Dongjun Jeong, Chang-Jin Kim, Hyun-Suk Lim, Ki Hean Kim, Sung-Kee Chung
The impermeability of the cell plasma membrane is one of the major barriers for protein transduction into mammalian cells, and it also limits the use of proteins as therapeutic agents. Protein transduction has usually been achieved based on certain invasive processes or cell penetrating peptides (CPP). Herein we report our study in which a synthetic guanidine-rich molecular carrier is used as a delivery vector for intracellular and transdermal delivery of proteins. First a sorbitol-based molecular carrier having 8 guanidine units (Sor-G8) was synthesized, and then was simply mixed with a cargo protein of varying sizes to form the non-covalent complex of carrier-cargo proteins...
June 17, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28632960/snap-tag-based-subcellular-proteins-labeling-and-fluorescent-imaging-with-naphthalimides
#19
Chao Wang, Xinbo Song, Yi Xiao
Genetically encoded technologies provide methods for specific labeling and imaging of proteins, which is essential for the understanding of their subcellular localization and function. Herein, we employ naphthalimide, an efficient two-photon fluorophore, to develop O6-benzylguanine (BG) derivatives for specific labeling of subcellular proteins and fluorescent imaging through the SNAP-tag. The three naphthalimide-BG derivatives, TNI-BG, QNI-BG and ONI-BG are conveniently synthesized through modular "click chemistry" with high yields...
June 20, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28632500/photon-detection-efficiency-of-laboratory-based-x-ray-phase-contrast-imaging-techniques-for-mammography-a-monte-carlo-study
#20
Somayeh Saghamanesh, Seyed Mohammad Reza Aghamiri, Alireza Kamali-Asl, Wataru Yashiro
An important challenge in real-world biomedical applications of X-ray phase contrast imaging (XPCI) techniques is the efficient use of the photon flux generated by an incoherent and polychromatic X-ray source. This efficiency can directly influence dose and exposure time and ideally should not affect the superior contrast and sensitivity of XPCI. In this paper, we present a quantitative evaluation of the photon detection efficiency of two laboratory-based XPCI methods, grating interferometry (GI) and coded-aperture (CA)...
June 20, 2017: Physics in Medicine and Biology
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