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Light spectrum

Stefano Grigolato, Omar Mologni, Andrea Rosario Proto, Giuseppe Zimbalatti, Raffaele Cavalli
The use of helicopter rises discussion about environmental noise propagation especially when it operates in proximity of environmentally sensitive areas (ESAs) for an extended period because of its potential implications in wildlife behaviours. In order to support decisions on helicopter logging operation management in proximity of ESAs, this study focused on (i) analysing the noise spectrum of a light-lift helicopter during logging operations and on (ii) assessing the noise propagation in the surrounding environments...
January 20, 2018: Environmental Monitoring and Assessment
Rinku Saran, Richard J Curry
Visible spectrum photodetector devices fabricated using molecular crystals of carbon C60 are reported. The devices operate efficiently, extending over and beyond the full visible light spectrum (300-710 nm) with a bias voltage tunable responsivity of 4 mA-0.5 mA W-1 . Across this range of wavelengths, the noise equivalent power of these devices remains below 102 nW Hz-1/2 , providing a detectivity of 107 Jones. The noise current in these devices is found to have a strong dependence on both bias voltage and frequency, varying by 4 orders of magnitude from 1 nA Hz-1/2 to 0...
January 19, 2018: Small
Helena Sehlin, Britt Hedman Ahlström, Gerhard Andersson, Elisabet Wentz
BACKGROUND: There is a great demand for non-medical treatment and support targeting the needs of adolescents and young adults with autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD). There is also a lack of qualitative studies providing in-depth insight into these individuals' own experiences within this area. The current study aimed to explore how adolescents and young adults with ADHD, ASD or both experienced taking part in an internet-based support and coaching intervention...
January 18, 2018: BMC Psychiatry
Lorian E Schweikert, Michael S Grace
BACKGROUND: For many fish species, retinal function changes between life history stages as part of an encoded developmental program. Retinal change is also known to exhibit plasticity because retinal form and function can be influenced by light exposure over the course of development. Aside from studies of gene expression, it remains largely unknown whether retinal plasticity can provide functional responses to short-term changes in environmental light quality. The aim of this study was to determine whether the structure and function of the fish retina can change in response to altered light intensity and spectrum-not over the course of a developmental regime, but over shorter time periods relevant to marine habitat disturbance...
January 18, 2018: BMC Ecology
Jason K Gurchiek, Han Bao, Maria Agustina Domínguez-Martín, Sarah E McGovern, Claire E Marquardt, Jerome D Roscioli, Soumen Ghosh, Cheryl A Kerfeld, Warren F Beck
The Orange Carotenoid Protein (OCP) mediates nonphotochemical quenching (NPQ) mechanisms in cyanobacteria. A bound ketocarotenoid serves as a sensor of mid-visible light intensity and as a quencher of phycocyanobilin excitons in the phycobilisome. The photochemical mechanism that triggers conversion of the protein from a resting, orange state (OCPO) to an active, red state (OCPR) after optical preparation of the S2 state of the carotenoid remains an open question. We report here that the fluorescence spectrum and quantum yield of the bound carotenoids in OCPO report important details of the motions that follow optical preparation of the S2 state...
January 18, 2018: Journal of Physical Chemistry. B
A Radosavljević, G Gligorić, P P Beličev, A Maluckov, M Stepić
By introducing evolving disorder in the binary kagome ribbons, we study the establishment of diffusive spreading of flat band states characterized by diffractionless propagation in regular periodic ribbons. Our numerical analysis relies on controlling strength and rate of change of disorder during light propagation while tailoring binarism of the kagome ribbons in order to isolate the flat band with the gap from the rest of the ribbon's eigenvalue spectrum and study systematically its influence on diffusion...
July 2017: Physical Review. E
Wael Awad, Sven Kjellstrom, Gabriel Svensson Birkedal, Katrin Mani, Derek Thomas Logan
Heparan sulfate proteoglycans are proteins substituted with one or more heparan sulfate (HS) polysaccharides, found in abundance at cell surfaces. HS chains influence the activity of many biologically important molecules involved in cellular communication and signaling. The exostosin (EXT) proteins are glycosyltransferases in the Golgi apparatus that assemble HS chains on HSPGs. The EXTL3 enzyme mainly works as an initiator in HS biosynthesis. In this work, human lumenal N-glycosylated EXTL3 (EXTL3ΔN) was cloned, expressed in human embryonic kidney cells and purified...
January 18, 2018: Biochemistry
Nicola Chiarelli, Giulia Carini, Nicoletta Zoppi, Marco Ritelli, Marina Colombi
Vascular Ehlers-Danlos syndrome (vEDS) is a dominantly inherited connective tissue disorder caused by mutations in the COL3A1 gene that encodes type III collagen (COLLIII), which is the major expressed collagen in blood vessels and hollow organs. The majority of disease-causing variants in COL3A1 are glycine substitutions and in-frame splice mutations in the triple helix domain that through a dominant negative effect are associated with the severe clinical spectrum potentially lethal of vEDS, characterized by fragility of soft connective tissues with arterial and organ ruptures...
2018: PloS One
Sebastian Maehrlein, Alexander Paarmann, Martin Wolf, Tobias Kampfrath
In stimulated Raman scattering, two incident optical waves induce a force oscillating at the difference of the two light frequencies. This process has enabled important applications such as the excitation and coherent control of phonons and magnons by femtosecond laser pulses. Here, we experimentally and theoretically demonstrate the so far neglected up-conversion counterpart of this process: THz sum-frequency excitation of a Raman-active phonon mode, which is tantamount to two-photon absorption by an optical transition between two adjacent vibrational levels...
September 22, 2017: Physical Review Letters
Jose Navarrete, Chris Siefe, Samuel Alcantar, Michael Belt, Galen D Stucky, Martin Moskovits
Metallic nanostructures exhibit a strong plasmon resonance at a wavelength whose value is sensitive to the charge density in the nanostructure, its size, shape, interparticle coupling and the dielectric properties of its surrounding medium. Here we use UV-Visible transmission and reflectance spectroscopy to track the shifts of the plasmon resonance in an array of gold nanoparticles buried under metal-oxide layers of varying thickness produced using atomic layer deposition (ALD), then coated with bulk layers of one of three metals: aluminum, silver, and gold...
January 17, 2018: Nano Letters
G Annadurai, S Masilla Moses Kennedy, V Sivakumar
Dysprosium ion (Dy3+ ) activated Ba2 CaZn2 Si6 O17 phosphors were synthesized using high temperature solid-state reaction method. Powder X-ray diffraction (PXRD) analysis confirmed the phase formation of the as-prepared phosphors. Scanning electron microscopy (SEM) analysis disclosed an agglomeration of particles with an irregular morphology. Under 350 nm excitation, the emission spectrum of Dy3+ ions showed bands at 481 nm (blue), 577 nm (yellow) and 674 nm (red). The influence of the Dy3+ concentration on its emission intensity was investigated...
January 17, 2018: Luminescence: the Journal of Biological and Chemical Luminescence
D Schleier, P Constantinidis, N Faßheber, I Fischer, G Friedrichs, P Hemberger, E Reusch, B Sztáray, K Voronova
The kinetics of the combustion-relevant reaction of the allyl radical, a-C3H5, with molecular oxygen has been studied in a flow tube reactor at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source storage ring, using the CRF-PEPICO (Combustion Reactions Followed by Photoelectron Photoion Coincidence Spectroscopy) setup. The ability to measure threshold photoelectron spectra enables a background-free detection of reactive species as well as an isomer-specific analysis of reaction products. Allyl was generated by direct photodissociation of allyl iodide at 266 nm and 213 nm and indirectly by the reaction of propene with Cl atoms, which were generated by photolysis from oxalyl chloride at 266 nm...
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
Ying-Chu Chen, Yu-Kuei Hsu, Radian Popescu, Dagmar Gerthsen, Yan-Gu Lin, Claus Feldmann
Full-spectrum utilization of diffusive solar energy by a photocatalyst for environmental remediation and fuel generation has long been pursued. In contrast to tremendous efforts in the UV-to-VIS light regime of the solar spectrum, the NIR and IR areas have been barely addressed although they represent about 50% of the solar flux. Here we put forward a biomimetic photocatalyst blueprint that emulates the growth pattern of a natural plant-a peapod-to address this issue. This design is exemplified via unidirectionally seeding core-shell Au@Nb nanoparticles in the cavity of semiconducting H x K1-xNbO3 nanoscrolls...
January 16, 2018: Nature Communications
Raoul Wolf, Jan-Erik Thrane, Dag Olav Hessen, Tom Andersen
Concentrations of dissolved organic matter (DOM) are increasing in a large number of lakes across the Northern hemisphere. This browning serves a dual role for biota by protecting against harmful ultraviolet radiation, while also absorbing photosynthetically active radiation. The photochemical activation of DOM and subsequent formation of reactive oxygen species (ROS) is a potentially harmful side effect, but can be difficult to measure directly in situ. In this study, we combine a data set of physico-chemical properties from 71 Nordic lakes with in vitro ROS formation quantum yields to predict ROS formations across a representative boreal ecosystem gradient...
January 11, 2018: Water Research
Young Duck Kim, Yuanda Gao, Ren-Jye Shiue, Lei Wang, Ozgur Burak Aslan, Myung-Ho Bae, Hyungsik Kim, Dongjea Seo, Heon-Jin Choi, Suk Hyun Kim, Andrei Nemilentsau, Tony Low, Cheng Tan, Dmitri K Efetov, Takashi Taniguchi, Kenji Watanabe, Kenneth L Shepard, Tony F Heinz, Dirk Englund, James C Hone
Ultrafast electrically driven nanoscale light sources are critical components in nanophotonics. Compound semiconductor-based light sources for the nanophotonic platforms have been extensively investigated over the past decades. However, monolithic ultrafast light sources with a small footprint remain a challenge. Here, we demonstrate electrically driven ultrafast graphene light emitters that achieve light pulse generation with up to 10 GHz bandwidth, across a broad spectral range from the visible to the near-infrared...
January 16, 2018: Nano Letters
Robin E Rodríguez, Sneha P Agarwal, Shun An, Eric Kazyak, Debashree Das, Wen Shang, Rachael Skye, Tao Deng, Neil P Dasgupta
Morpho sulkowskyi butterfly wings contain naturally occurring hierarchical nanostructures that produce structural coloration. The high aspect ratio and surface area of these wings make them attractive nanostructured templates for applications in solar energy and photocatalysis. However, biomimetic approaches to replicate their complex structural features and integrate functional materials into their three-dimensional framework are highly limited in precision and scalability. Herein, a biotemplating approach is presented that precisely replicates Morpho nanostructures by depositing nanocrystalline ZnO coatings onto wings via low-temperature atomic layer deposition (ALD)...
January 16, 2018: ACS Applied Materials & Interfaces
Isaac N Mills, Jonathan A Porras, Stefan Bernhard
The exponential growth in published studies on phosphorescent metal complexes has been triggered by their utilization in optoelectronics, solar energy conversion, and biological labeling applications. Very recent breakthroughs in organic photoredox transformations have further increased the research efforts dedicated to discerning the inner workings and structure-property relationships of these chromophores. Initially, the principal focus was on the Ru(II)-tris-diimine complex family. However, the limited photostability and lack of luminescence tunability discovered in these complexes prompted a broadening of the research to include 5d transition metal ions...
January 16, 2018: Accounts of Chemical Research
Xuan Cao, Gang Lei, Jingjing Feng, Qi Pan, Xiaodong Wen, Yan He
Creating color difference and improving the color resolution in digital imaging is crucial for better application of color analy-sis. Herein, a novel color modulation analysis strategy was developed by using a homemade tunable multiband laser illumi-nation device, in which the portions of R, G, and B components of the illumination light are discretionarily adjustable, and hence the sample color could be visually modulated continuously in the RGB color space. Through this strategy, the color appearance of single gold nanorods (AuNRs) under dark-field microscopy, was migrated from the spectrally insensitive red region to the spectrally sensitive green-yellow-red region...
January 15, 2018: Analytical Chemistry
Fang Zhao, Dario Cambié, Jeroen Janse, Eric W Wieland, Koen P L Kuijpers, Volker Hessel, Michael G Debije, Timothy Noël
The use of solar energy to power chemical reactions is a long-standing dream of the chemical community. Recently, visible-light-mediated photoredox catalysis has been recognized as the ideal catalytic transformation to convert solar energy into chemical bonds. However, scaling photochemical transformations has been extremely challenging due to Bouguer-Lambert-Beer law. Recently, we have pioneered the development of luminescent solar concentrator photomicroreactors (LSC-PMs), which display an excellent energy efficiency...
January 2, 2018: ACS Sustainable Chemistry & Engineering
Xiaozhen Lu, Hongxia Jia, Xiaohua Yan, Jingsha Wang, Yucong Wang, Chenghui Liu
A simple and homogeneous histone assay is developed based on histone-induced DNA compressing coupled with cationic conjugated polymer (CCP)-mediated fluorescence resonance energy transfer (FRET). In this strategy, the CCP serves as the FRET donor and SYBR Green I (SG), which can strongly fluoresce not at its free state but after intercalated into the double stranded calf thymus DNA (dsDNA), serves as the acceptor of FRET. In the absence of histone, the dsDNA-SG and CCP combine with each other through electrostatic interaction and the strong FRET from CCP to SG occurs due to the overlapping between the fluorescent emitting spectrum of the CCP and the absorption spectrum of SG...
April 1, 2018: Talanta
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