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Light spectrum

Solmaz Marzooghi, Bryson E Finch, William A Stubblefield, Dominic M Di Toro
The toxicity of petroleum can increase considerably when exposed to solar radiation. It occurs when certain components in the mixture, including polycyclic aromatic hydrocarbons (PAHs), absorb light in ultraviolet and visible portions of the solar radiation spectrum. A phototoxic target lipid model (PTLM), previously developed to predict phototoxicity of single PAHs, is validated for four species: Americamysis bahia, Rhepoxynius abronius, Daphnia magna, and Pimephales promelas exposed to 12 compounds that are components of petroleum, including alkylated PAHs and dibenzothiophene...
May 19, 2018: Environmental Toxicology and Chemistry
Maxim V Pyatnov, Stepan Ya Vetrov, Ivan V Timofeev
Coupling between the defect mode of a cholesteric liquid crystal and the localized mode of a cholesteric liquid crystal-phase plate-metal structure is theoretically demonstrated. It is shown that the transmittance spectrum can be tuned by changing the twist-defect angle and helix pitch, which are governed by external factors. The spectra for different circular polarizations of the incident light are different; specifically, at the nondiffracting polarization, there is no defect-mode transmittance peak.
March 2018: Physical Review. E
Karol Wysokiński, Dawid Budnicki, Janusz Fidelus, Łukasz Szostkiewicz, Łukasz Ostrowski, Micha Murawski, Marcin Staniszewski, Magdalena Staniszewska, Marek Napierała, Tomasz Nasiłowski
An optical fiber interferometric microprobe for detection of specific proteins is presented in this paper. The microprobe is an all-fiber device, which is based on Michelson interferometer configuration, which allows for detection of protein antigens in an analyzed solution thanks to antibodies immobilized on the sensor surface. The interferometer is made of dual core fiber and has a precisely formed arm length difference, achieved by splicing a fragment of polarization maintaining fiber to one of the cores...
May 9, 2018: Biosensors & Bioelectronics
H Askar, F Schwendicke, J Lausch, H Meyer-Lueckel, S Paris
OBJECTIVE: Infiltrant resin (IR) is currently indicated for non-cavitated caries lesions. However, modifying the technique might expand its indication spectrum to micro-cavitated lesions. The present study aimed to evaluate the penetration/filling ability of a newly developed micro-filled infiltrant resin (MFIR) in non-, micro- and cavitated natural caries lesions. MATERIALS AND METHODS: Proximal lesions in 120 extracted human teeth with ICDAS-2 (n = 30), 3 (n = 45) and 5 (n = 45) lesions were etched with 15% hydrochloric acid gel for 2 min and allocated to one of the following treatments; IR: lesions (ICDAS-2, 3 and 5; each n = 15) were treated with commercial infiltrant resin for 3 min...
May 16, 2018: Journal of Dentistry
Guy F de Téramond, Tianbo Liu, Raza Sabbir Sufian, Hans Günter Dosch, Stanley J Brodsky, Alexandre Deur
The structure of generalized parton distributions is determined from light-front holographic QCD up to a universal reparametrization function w(x) which incorporates Regge behavior at small x and inclusive counting rules at x→1. A simple ansatz for w(x) that fulfills these physics constraints with a single-parameter results in precise descriptions of both the nucleon and the pion quark distribution functions in comparison with global fits. The analytic structure of the amplitudes leads to a connection with the Veneziano model and hence to a nontrivial connection with Regge theory and the hadron spectrum...
May 4, 2018: Physical Review Letters
Steve Ulrich, Tabitha Sutch, Greg Szulczewski, Matthias Schweizer, Newton Barbosa, Paulo Araujo
We investigate the P(NDI2OD-T2) photophysical properties via absorbance and fluorescence spectroscopy, in association with the experimental approach baptized Stokes Spectroscopy, which provides valuable material information through the acquisition and analysis of the fluorescence polarization degree. By changing solvents and using different samples such as solutions, thick, and thin films, it is possible to control the polarization degree spectrum associated to the fluorescence emitted by the polymer's isolated chains and aggregates...
May 18, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Aurore Morel, Elodie Peyroux, Arnaud Leleu, Emilie Favre, Nicolas Franck, Caroline Demily
Rare neurodevelopmental syndromes often present social cognitive deficits that may underlie difficulties in social interactions and increase the risk of psychosis or autism spectrum disorders. However, little is known regarding the specificities of social cognitive impairment across syndromes while it remains a major challenge for the care. Our review provides an overview of social cognitive dysfunctions in rare diseases associated with psychiatric symptoms (with a prevalence estimated between 1 in 1,200 and 1 in 25,000 live births: 22q11...
2018: Frontiers in Pediatrics
Kareem Soliman, Fabian Göttfert, Hendrik Rosewich, Sven Thoms, Jutta Gärtner
Peroxisomes are ubiquitous cell organelles involved in many metabolic and signaling functions. Their assembly requires peroxins, encoded by PEX genes. Mutations in PEX genes are the cause of Zellweger Syndrome spectrum (ZSS), a heterogeneous group of peroxisomal biogenesis disorders (PBD). The size and morphological features of peroxisomes are below the diffraction limit of light, which makes them attractive for super-resolution imaging. We applied Stimulated Emission Depletion (STED) microscopy to study the morphology of human peroxisomes and peroxisomal protein localization in human controls and ZSS patients...
May 17, 2018: Scientific Reports
Kelsey Mandak, Janice Light, Susannah Boyle
The purpose of this systematic review was to investigate the effects of instruction on single-word reading of individuals who use aided augmentative and alternative communication (AAC). A systematic search identified nine single-case experimental design studies that involved 24 individuals who used aided AAC. Overall, the evidence indicated that instruction had positive effects on reading at the single-word level for individuals across ages and diagnostic categories (i.e., autism spectrum disorder (ASD), cerebral palsy (CP), Down syndrome, and intellectual disability)...
May 18, 2018: Augmentative and Alternative Communication: AAC
Franziska Steudel, Jacqueline A Johnson, Charles E Johnson, Stefan Schweizer
The application of Mössbauer spectroscopy to luminescent materials is described. Many solids doped with europium are luminescent, i.e., when irradiated with light they emit light of a longer wavelength. These materials therefore have practical applications in tuning the light output of devices like light emitting diodes. The optical properties are very different for the two possible valence states Eu 2 + and Eu 3 + , the former producing ultraviolet/visible light that shifts from violet to red depending on the host and the latter red light, so it is important to have a knowledge of their behavior in a sample environment...
May 17, 2018: Materials
Hao Zhang, Junzhen Jiang, Shuang Liu, Huaixi Chen, Xiaoqian Zheng, Yishen Qiu
Demodulation is a bottleneck for applications involving fiber Bragg gratings (FBGs). An overlap spectrum FBG sensor based on a light power demodulation method is presented in this paper. The demodulation method uses two chirp FBGs (cFBGs) of which the reflection spectra partially overlap each other. The light power variation of the overlap spectrum can be linked to changes in the measurand, and the sensor function can be realized via this relationship. A temperature experiment showed that the relationship between the overlap power spectrum of the FBG sensor and temperature had good linearity and agreed with the theoretical analysis...
May 17, 2018: Sensors
Maja Grubisic, Roy H A van Grunsven, Alessandro Manfrin, Michael T Monaghan, Franz Hölker
The increasing use of artificial light at night (ALAN) has led to exposure of freshwater ecosystems to light pollution worldwide. Simultaneously, the spectral composition of nocturnal illumination is changing, following the current shift in outdoor lighting technologies from traditional light sources to light emitting diodes (LED). LEDs emit broad-spectrum white light, with a significant amount of photosynthetically active radiation, and typically a high content of blue light that regulates circadian rhythms in many organisms...
May 14, 2018: Environmental Pollution
Seok Hyun Yun, Dimitri Chernyak
PURPOSE OF REVIEW: Assessment of corneal biomechanics has been an unmet clinical need in ophthalmology for many years. Many researchers and clinicians have identified corneal biomechanics as source of variability in refractive procedures and one of the main factors in keratoconus. However, it has been difficult to accurately characterize corneal biomechanics in patients. The recent development of Brillouin light scattering microscopy heightens the promise of bringing biomechanics into the clinic...
May 15, 2018: Current Opinion in Ophthalmology
Eavan M McGovern, Emmanuel Roze, Timothy J Counihan
PURPOSE OF REVIEW: This review will discuss the expanding clinical spectrum of paroxysmal movement disorders and therapeutic options in light of emerging genotypic heterogeneity in these conditions. RECENT FINDINGS: Paroxysmal movement disorders comprise a heterogeneous group of rare neurological conditions characterized by intermittent episodes of abnormal movement associated with various triggers. As the clinical and genotypic spectrum of these disorders evolves, so also has the range of therapeutic options...
May 15, 2018: Current Opinion in Neurology
John Biggins, Sadegh Yazdi, Emilie Ringe
Nanoparticles of some metals (Cu/Ag/Au) sustain oscillations of their electron cloud called localized surface plasmon resonances (LSPRs). These resonances can occur at optical frequencies and be driven by light, generating enhanced electric fields and spectacular photon scattering. However, current plasmonic metals are rare, expensive, and have a limited resonant frequency range. Recently, much attention has been focused on earth-abundant Al, but Al nanoparticles cannot resonate in the IR. The earth-abundant Mg nanoparticles reported here surmount this limitation...
May 17, 2018: Nano Letters
Marie S Prevost, Gabriel Waksman
Human infections by the intracellular bacterial pathogen Legionella pneumophila result in a severe form of pneumonia, the Legionnaire's disease. L. pneumophila utilises a type IVb secretion (T4bS) system termed "dot/icm" to secrete protein effectors to the host cytoplasm. The dot/icm system is powered at least in part by a functionally critical AAA+ ATPase, a protein called DotB, thought to belong to the VirB11 family of proteins. Here we present the crystal structure of DotB at 3.19 Å resolution, in its hexameric form...
May 17, 2018: Protein Science: a Publication of the Protein Society
Yujie Bai, Gaixia Luo, Lijuan Meng, Qinfang Zhang, Ning Xu, Haiyang Zhang, Xiuqiang Wu, Fanjie Kong, Baolin Wang
Searching for two-dimensional semiconductor materials that are suitable for visible-light photocatalytic water splitting provides a sustainable solution to deal with the future energy crisis and environmental problems. Herein, based on first-principles calculations, single-layer ZnMN2 (M = Si, Ge, Sn) zinc nitrides are proposed as efficient photocatalysts for water splitting. Stability analyses show that the single-layer ZnMN2 zinc nitrides exhibit energetic and dynamical stability. The electronic properties reveal that all of the single-layer ZnMN2 zinc nitrides are semiconductors...
May 17, 2018: Physical Chemistry Chemical Physics: PCCP
Meredith C Schuman, Ian T Baldwin
Plants are at the trophic base of most ecosystems, embedded in a rich network of ecological interactions in which they evolved. While their limited range and speed of motion precludes animal-typical behavior, plants are accomplished chemists, producing thousands of specialized metabolites which may function to convey information, or even to manipulate the physiology of other organisms. Plants' complex interactions and their underlying mechanisms are typically dissected within the controlled environments of growth chambers and glasshouses, but doing so introduces conditions alien to plants evolved in natural environments, such as being pot-bound, and receiving artificial light with a spectrum very different from sunlight...
May 17, 2018: Chemical Society Reviews
Magdalena Staniszewska, Stephan Kupfer, Julien Guthmuller
Time-dependent density functional theory calculations combined with the Marcus theory of electron transfer (ET) were applied on the molecular photocatalyst [(tbbpy)2Ru(tpphz)PdCl2]2+ in order to elucidate the light-induced relaxation pathways populated upon excitation in the longer wavelength range of its absorption spectrum. The computational results show that after the initial excitation, metal (Ru) to ligand (tpphz) charge transfer (MLCT) triplet states are energetically accessible, but that an ET toward the catalytic center (PdCl2) from these states is a slow process, with estimated time constants above 1 ns...
May 16, 2018: Chemistry: a European Journal
Asmathunisha Nabikhan, Suji Rathinam, Kathiresan Kandasamy
The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from Avicennia marina as bioreductant for eco-friendly bioremediation of 4-nitrophenol (4-NP) . The AuNPs synthesised were confirmed by UV spectrum, transmission electron microscopy (TEM), X-ray diffraction, Fourier transmission infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential. The AuNPs were found to be spherical in shape with size ranging from 4 to 13 nm, as evident by TEM and DLS...
June 2018: IET Nanobiotechnology
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