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https://www.readbyqxmd.com/read/28227793/experimental-validation-of-neutron-activation-simulation-of-a-varian-medical-linear-accelerator
#1
S Morato, B Juste, R Miro, G Verdu, S Diez, S Morato, B Juste, R Miro, G Verdu, S Diez, B Juste, S Diez, R Miro, S Morato, G Verdu
This work presents a Monte Carlo simulation using the last version of MCNP, v. 6.1.1, of a Varian CLinAc emitting a 15MeV photon beam. The main objective of the work is to estimate the photoneutron production and activated products inside the medical linear accelerator head. To that, the Varian LinAc head was modelled in detail using the manufacturer information, and the model was generated with a CAD software and exported as a mesh to be included in the particle transport simulation. The model includes the transport of photoneutrons generated by primary photons and the (n, γ) reactions which can result in activation products...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28227506/a-pdms-based-optical-waveguide-for-transcutaneous-powering-of-microelectrode-arrays
#2
Ali Ersen, Mesut Sahin, Ali Ersen, Mesut Sahin, Ali Ersen, Mesut Sahin
Implantable microelectrode arrays (MEAs) usually have on-site electronics that need to be powered, both in neural recording and stimulation applications. Interconnecting wires between implanted electrodes and the outside world constitute a major source of complications. Our solution to this tethering problem is to design a light waveguide that can collect the optical power transcutaneously and transmit it to the microelectrode array where it is to be converted to an electric current. A polydimethylsiloxane (PDMS)-based waveguide was fabricated and its attenuation was measured in vitro and found to be 0...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226531/bayesian-deconvolution-of-scanning-electron-microscopy-images-using-point-spread-function-estimation-and-non-local-regularization
#3
Joris Roels, Jan Aelterman, Jonas De Vylder, Hiep Luong, Yvan Saeys, Wilfried Philips, Joris Roels, Jan Aelterman, Jonas De Vylder, Hiep Luong, Yvan Saeys, Wilfried Philips, Hiep Luong, Wilfried Philips, Jan Aelterman, Jonas De Vylder, Yvan Saeys, Joris Roels
Microscopy is one of the most essential imaging techniques in life sciences. High-quality images are required in order to solve (potentially life-saving) biomedical research problems. Many microscopy techniques do not achieve sufficient resolution for these purposes, being limited by physical diffraction and hardware deficiencies. Electron microscopy addresses optical diffraction by measuring emitted or transmitted electrons instead of photons, yielding nanometer resolution. Despite pushing back the diffraction limit, blur should still be taken into account because of practical hardware imperfections and remaining electron diffraction...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28225761/amplified-stimulated-emission-in-upconversion-nanoparticles-for-super-resolution-nanoscopy
#4
Yujia Liu, Yiqing Lu, Xusan Yang, Xianlin Zheng, Shihui Wen, Fan Wang, Xavier Vidal, Jiangbo Zhao, Deming Liu, Zhiguang Zhou, Chenshuo Ma, Jiajia Zhou, James A Piper, Peng Xi, Dayong Jin
Lanthanide-doped glasses and crystals are attractive for laser applications because the metastable energy levels of the trivalent lanthanide ions facilitate the establishment of population inversion and amplified stimulated emission at relatively low pump power. At the nanometre scale, lanthanide-doped upconversion nanoparticles (UCNPs) can now be made with precisely controlled phase, dimension and doping level. When excited in the near-infrared, these UCNPs emit stable, bright visible luminescence at a variety of selectable wavelengths, with single-nanoparticle sensitivity, which makes them suitable for advanced luminescence microscopy applications...
February 22, 2017: Nature
https://www.readbyqxmd.com/read/28225752/prefrontal-cortex-output-circuits-guide-reward-seeking-through-divergent-cue-encoding
#5
James M Otis, Vijay M K Namboodiri, Ana M Matan, Elisa S Voets, Emily P Mohorn, Oksana Kosyk, Jenna A McHenry, J Elliott Robinson, Shanna L Resendez, Mark A Rossi, Garret D Stuber
The prefrontal cortex is a critical neuroanatomical hub for controlling motivated behaviours across mammalian species. In addition to intra-cortical connectivity, prefrontal projection neurons innervate subcortical structures that contribute to reward-seeking behaviours, such as the ventral striatum and midline thalamus. While connectivity among these structures contributes to appetitive behaviours, how projection-specific prefrontal neurons encode reward-relevant information to guide reward seeking is unknown...
February 22, 2017: Nature
https://www.readbyqxmd.com/read/28225630/scalable-quantum-photonics-with-single-color-centers-in-silicon-carbide
#6
Marina Radulaski, Matthias Widmann, Matthias Niethammer, Jingyuan Linda Zhang, Sangyun Lee, Torsten Rendler, Konstantinos G Lagoudakis, Nguyen Tien Son, Erik Janzén, Takeshi Ohshima, Jörg Wrachtrup, Jelena Vuckovic
Silicon carbide is a promising platform for single photon sources, quantum bits (qubits) and nanoscale sensors based on individual color centers. Towards this goal, we develop a scalable array of nanopillars incorporating single silicon vacancy centers in 4H-SiC, readily available for efficient interfacing with free-space objective and lensed-fibers. A commercially obtained substrate is irradiated with 2 MeV electron beams to create vacancies. Subsequent lithographic process forms 800 nm tall nanopillars with 400-1,400 nm diameters...
February 22, 2017: Nano Letters
https://www.readbyqxmd.com/read/28225353/impact-of-fluorescence-emission-from-gold-atoms-on-surrounding-biological-tissue-implications-for-nanoparticle-radio-enhancement
#7
Hilary L Byrne, Yaser Gholami, Zdenka Kuncic
The addition of gold nanoparticles within target tissue (i.e. a tumour) to enhance the delivered radiation dose is a well studied radiotherapy treatment strategy, despite not yet having been translated into standard clinical practice. While several studies have used Monte Carlo simulations to investigate radiation dose enhancement by Auger electrons emitted from irradiated gold nanoparticles, none have yet considered the effects due to escaping fluorescence photons. Geant4 was used to simulate a water phantom containing 10 mg/mL uniformly dispersed gold (1% by mass) at 5cm depth...
February 22, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28225261/structural-color-for-additive-manufacturing-3d-printed-photonic-crystals-from-block-copolymers
#8
Bret M Boyle, Tracy A French, Ryan Michael Pearson, Blaine G McCarthy, Garret M Miyake
The incorporation of structural color into 3D printed parts is reported, presenting an alternative to the need for pigments or dyes for colored parts produced through additive manufacturing. Thermoplastic build materials composed of dendritic block copolymers were designed, synthesized, and used to additively manufacture plastic parts exhibiting structural color. The reflection properties of the photonic crystals arise from the periodic nanostructure formed through block copolymer self-assembly during polymer processing...
February 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28225160/emerging-low-dimensional-materials-for-nonlinear-optics-and-ultrafast-photonics
#9
REVIEW
Xiaofeng Liu, Qiangbing Guo, Jianrong Qiu
Low-dimensional (LD) materials demonstrate intriguing optical properties, which lead to applications in diverse fields, such as photonics, biomedicine and energy. Due to modulation of electronic structure by the reduced structural dimensionality, LD versions of metal, semiconductor and topological insulators (TIs) at the same time bear distinct nonlinear optical (NLO) properties as compared with their bulk counterparts. Their interaction with short pulse laser excitation exhibits a strong nonlinear character manifested by NLO absorption, giving rise to optical limiting or saturated absorption associated with excited state absorption and Pauli blocking in different materials...
February 22, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28225119/dna-photonic-nanowires-with-tunable-fret-signals-on-the-basis-of-toehold-mediated-dna-strand-displacement-reactions
#10
Bei Wang, Xiaojing Wang, Bing Wei, Fujian Huang, Dongbao Yao, Haojun Liang
A DNA photonic nanowire with tunable FRET signals was fabricated on the basis of cascaded toehold-mediated DNA strand displacement reactions. Different DNA inputs were added to trigger the reaction network, and the corresponding FRET signals were obtained. Compared to the direct hybridization, this design is sensitive for 2 nM targets within 20 min and also causes color changes of the solution with blue-light excitation. It could also be applied in live cells to monitor MicroRNA with a simple modification which might become a low-cost method for further application in the future...
February 22, 2017: Nanoscale
https://www.readbyqxmd.com/read/28225100/hybrid-plasmonic-photonic-whispering-gallery-mode-resonators-for-sensing-a-critical-review
#11
REVIEW
Angelo Bozzola, Sara Perotto, Francesco De Angelis
In this review we present the state of the art and the most recent advances in the field of optical sensing with hybrid plasmonic-photonic whispering gallery mode (WGM) resonators. After a brief introduction on the basic physics behind photonic WGM resonators and localized surface plasmon (LSP) nanostructures, we analyze the different types of optical sensors specifically designed for bulk refractive index sensing, molecular binding and single object detection. We point out the physical and technological key points of the different approaches proposed in the literature, and we systematically compare hybrid sensors and purely photonic WGM sensors...
February 22, 2017: Analyst
https://www.readbyqxmd.com/read/28225031/realizing-total-reciprocity-violation-in-the-phase-for-photon-scattering
#12
László Deák, László Bottyán, Tamás Fülöp, Dániel Géza Merkel, Dénes Lajos Nagy, Szilárd Sajti, Kai Sven Schulze, Hartmut Spiering, Ingo Uschmann, Hans-Christian Wille
Reciprocity is when wave or quantum scattering satisfies a symmetry property, connecting a scattering process with the reversed one. While reciprocity involves the interchange of source and detector, it is fundamentally different from rotational invariance, and is a generalization of time reversal invariance, occurring in absorptive media as well. Due to its presence at diverse areas of physics, it admits a wide variety of applications. For polarization dependent scatterings, reciprocity is often violated, but violation in the phase of the scattering amplitude is much harder to experimentally observe than violation in magnitude...
February 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28224903/in%C3%A2-vivo-near-infrared-fluorescence-imaging-of-amyloid-%C3%AE-plaques-with-a-dicyanoisophorone-based-probe
#13
Jia-Ying Zhu, Lin-Fu Zhou, Yu-Kun Li, Shuo-Bin Chen, Jin-Wu Yan, Lei Zhang
A dicyanoisophorone-based probe with two-photon absorption and NIR emission was developed for the in vivo fluorescence imaging of amyloid-β plaques, which exhibited high selectivity toward Aβ aggregates over other intracellular proteins. The detection limit was calculated to be as low as 109 nM. In vivo imaging studies indicated that the probe could penetrate the blood-brain barrier and label Aβ plaques in the living transgenic mice, and its specific binding to cerebral Aβ plaques was further confirmed by one- and two-photon ex vivo fluorescence imaging...
April 8, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28224449/the-exerrt-trial-exercise-to-regadenoson-in-recovery-trial-a-phase-3b-open-label-parallel-group-randomized-multicenter-study-to-assess-regadenoson-administration-following-an-inadequate-exercise-stress-test-as-compared-to-regadenoson-without-exercise-for-myocardial
#14
Gregory S Thomas, S James Cullom, Therese M Kitt, Kathleen M Feaheny, Karthikeyan Ananthasubramaniam, Robert J Gropler, Diwakar Jain, Randall C Thompson
BACKGROUND: This study assessed the non-inferiority and safety of regadenoson administration during recovery from inadequate exercise compared with administration without exercise. METHODS: Patients unable to achieve adequate exercise stress were randomized to regadenoson 0.4 mg either during recovery (Ex-Reg) or 1 hour after inadequate exercise (Regadenoson) (MPI1). All patients also underwent non-exercise regadenoson MPI 1-14 days later (MPI2). The number of segments with reversible perfusion defects (RPDs) detected using single photon emission computerized tomography imaging was categorized...
February 21, 2017: Journal of Nuclear Cardiology: Official Publication of the American Society of Nuclear Cardiology
https://www.readbyqxmd.com/read/28222509/galantamine-response-associates-with-agitation-and-the-prefrontal-cortex-in-patients-with-alzheimer-s-disease
#15
Sachiko Nakayama, Akimitsu Suda, Hajime Nakanishi, Yumiko Motoi, Nobutaka Hattori
Behavioral and psychological symptoms of dementia (BPSD) occur in up to 80% of AD patients and represent one of the largest factors contributing to caregiver burden. To analyze the effect of galantamine on BPSD and caregiver burden, we treated a total of 50 patients with mild AD for 12 weeks and evaluated them using the Neuropsychiatric Inventory (NPI) and Japanese version of the Zarit Caregiver Burden Interview (ZBI). We also performed regional cerebral blood flow single photon emission computed tomography (rCBF SPECT) at baseline using three-dimensional sterotatic surface projections...
February 10, 2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28221808/decoupled-hierarchical-structures-for-suppression-of-leidenfrost-phenomenon
#16
Nazanin Farokhnia, Seyed Mohammad Sajadi, Peyman Irajizad, Hadi Ghasemi
Thermal management of high temperature systems through cooling droplets is limited by the existence of the Leidenfrost point (LFP), at which the formation of a continuous vapor film between a hot solid and a cooling droplet diminishes the heat transfer rate. This limit results in a bottleneck for the advancement of the wide spectrum of systems including high-temperature power generation, electronics/photonics, reactors, and spacecraft. Despite a long time effort on development of surfaces for suppression of this phenomenon, this limit has only shifted to higher temperatures, but still exists...
February 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28221779/experimental-assessment-of-photon-fluence-rate-distributions-in-a-medium-pressure-uv-photoreactor
#17
Mengkai Li, Zhimin Qiang, Chen Wang, James R Bolton, Ernest R Blatchley
The performance of a medium-pressure (MP) mercury lamp photoreactor is strongly influenced by the spatial photon fluence rate (PFR) distributions, which are wavelength-dependent. To address this issue, PFR distributions in an MP lamp photoreactor were measured using a 360-degree response micro-fluorescent silica detector (MFSD). To accurately express the optical behavior in an MP photoreactor, PFR, MFSD response PFR (PFRMFSD), and effective germicidal PFR (PFRGER) were defined and compared. The measured axial and radial PFRMFSD values agreed well with the corresponding results from a simulation model (UVCalc®)...
February 21, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28221764/correlation-of-bandgap-reduction-with-inversion-response-in-si-gesn-high-k-metal-stacks
#18
Christian Schulte-Braucks, Keyvan Narimani, Stefan Glass, Nils von den Driesch, Jean-Michel Hartmann, Zoran Ikonic, Valeri V Afanas'ev, Qing-Tai Zhao, Siegfried Mantl, Dan Buca
The bandgap tunability of (Si)GeSn group IV semiconductors opens a new era in Si-technology. Depending on the Si/Sn contents, direct and indirect bandgaps in the range of 0.4 eV to 0.8 eV can be obtained, offering a broad spectrum of both photonic and low power electronic applications. In this work, we systematically studied capacitance-voltage characteristics of high-k/metal gate stacks formed on GeSn and SiGeSn alloys with Sn-contents ranging from 0 to 14 at.% and Si-contents from 0 to 10 at.% particularly focusing on the minority carrier inversion response...
February 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28221714/photonic-devices-out-of-equilibrium-transient-memory-signal-propagation-and-sensing
#19
Thomas Heuser, Rémi Merindol, Sebastian Loescher, Aileen Klaus, Andreas Walther
Soft photonic materials are important for sensors, displays, or energy management and have become switchable under static equilibrium conditions by integration of responsive polymer features. The next step is to equip such materials with the ability for autonomously dynamic and self-regulating behavior, which would advance their functionality and application possibilities to new levels. Here, this study shows the system integration of a nonlinear, biocatalytic pH-feedback system with a pH-responsive block copolymer photonic gel, and demonstrates autonomous transient memories, remotely controlled signal propagation, and sensing...
February 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28221047/excited-state-proton-transfer-in-indigo
#20
Joao Pina, Daniela Santos Sarmento, Marco Accoto, Pier Luigi Gentili, Luigi Vaccaro, Adelino M Galvão, J Sérgio Seixas de Melo
Excited state proton transfer (ESPT) in Indigo (Ind) and its mono hexyl-substituted derivative (NHxInd) in solution was investigated experimentally as a function of solvent viscosity, polarity and temperature, and theoretically by time-dependent DFT (TDDFT) calculations. Although a single emission band is observed, the fluorescence decays (collected at different wavelengths along the emission band using time-correlated single photon counting (TCSPC)) are bi-exponential, with two identical decay times but different pre-exponential factors, consistent with the existence of excited state keto and enol species...
February 21, 2017: Journal of Physical Chemistry. B
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