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https://www.readbyqxmd.com/read/29331219/polycyclic-aromatic-hydrocarbons-in-soils-and-lichen-from-the-western-tibetan-plateau-concentration-profiles-distribution-and-its-influencing-factors
#1
Ruichen Zhou, Ruiqiang Yang, Chuanyong Jing
The Tibetan Plateau (TP) is a huge area and rarely affected by human activity, and is regarded as one of the most remote regions on the earth. Many studies about the long-range atmospheric transport (LRAT) of semi-volatile organic compounds (SVOCs) were conducted in southern and central TP. However, there are very limited studies focused on PAHs in the western TP and the concentrations profiles, distribution and its controlling factors in this area remains unclear. Thus, to explore this knowledge gap, 37 surface soil samples and 23 lichen samples were collected and analyzed for PAHs...
January 10, 2018: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/29330425/formation-and-dynamics-of-a-solar-eruptive-flux-tube
#2
Satoshi Inoue, Kanya Kusano, Jörg Büchner, Jan Skála
Solar eruptions are well-known drivers of extreme space weather, which can greatly disturb the Earth's magnetosphere and ionosphere. The triggering process and initial dynamics of these eruptions are still an area of intense study. Here we perform a magnetohydrodynamic simulation taking into account the observed photospheric magnetic field to reveal the dynamics of a solar eruption in a real magnetic environment. In our simulation, we confirmed that tether-cutting reconnection occurring locally above the polarity inversion line creates a twisted flux tube, which is lifted into a toroidal unstable area where it loses equilibrium, destroying the force-free state, and driving the eruption...
January 12, 2018: Nature Communications
https://www.readbyqxmd.com/read/29330188/germination-outgrowth-and-vegetative-growth-kinetics-of-dry-heat-treated-individual-spores-of-bacillus-species
#3
Lin He, Zhan Chen, Shiwei Wang, Muying Wu, Peter Setlow, Yong-Qing Li
DNA damage kills dry-heated spores of Bacillus subtilis, but dry heat-treatment effects on spore germination and outgrowth have not been studied. This is important, since if dry heat-killed spores germinate and undergo outgrowth, toxic proteins could be synthesized. Here, Raman spectroscopy and differential interference contrast microscopy were used to study germination and outgrowth of individual dry heat-treated B. subtilis and Bacillus megaterium spores. Major findings in this work were as follows. 1) Spores dry heat-treated at 140°C for 20 min nearly all lost viability but retained their Ca2+-dipicolinic acid (CaDPA) depot...
January 12, 2018: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29329243/characteristics-of-beidou-navigation-satellite-system-multipath-and-its-mitigation-method-based-on-kalman-filter-and-rauch-tung-striebel-smoother
#4
Qiuzhao Zhang, Wei Yang, Shubi Zhang, Xin Liu
Global Navigation Satellite System (GNSS) carrier phase measurement for short baseline meets the requirements of deformation monitoring of large structures. However, the carrier phase multipath effect is the main error source with double difference (DD) processing. There are lots of methods to deal with the multipath errors of Global Position System (GPS) carrier phase data. The BeiDou navigation satellite System (BDS) multipath mitigation is still a research hotspot because the unique constellation design of BDS makes it different to mitigate multipath effects compared to GPS...
January 12, 2018: Sensors
https://www.readbyqxmd.com/read/29328192/near-quantum-noise-limited-and-absolute-frequency-stabilized-1083%C3%A2-%C3%A2-nm-single-frequency-fiber-laser
#5
Qilai Zhao, Kaijun Zhou, Zisheng Wu, Changsheng Yang, Zhouming Feng, Huihui Cheng, Jiulin Gan, Mingying Peng, Zhongmin Yang, Shanhui Xu
The Earth's magnetic field has significant effects that protect us from cosmic radiation and provide navigation for biological migration. However, slow temporal variations originating in the liquid outer core invariably exist. To understand the working mechanism of the geomagnetic field and improve accuracy of navigation systems, a high-precision magnetometer is essential to measure the absolute magnetic field. A helium optically pumping magnetometer is an advanced approach, but its sensitivity and accuracy are directly limited by the low-frequency relative intensity noise and frequency stability characteristics of a light source...
January 1, 2018: Optics Letters
https://www.readbyqxmd.com/read/29328104/statistical-properties-of-single-mode-fiber-coupling-of-satellite-to-ground-laser-links-partially-corrected-by-adaptive-optics
#6
Lucien Canuet, Nicolas Védrenne, Jean-Marc Conan, Cyril Petit, Geraldine Artaud, Angelique Rissons, Jerome Lacan
In the framework of satellite-to-ground laser downlinks, an analytical model describing the variations of the instantaneous coupled flux into a single-mode fiber after correction of the incoming wavefront by partial adaptive optics (AO) is presented. Expressions for the probability density function and the cumulative distribution function as well as for the average fading duration and fading duration distribution of the corrected coupled flux are given. These results are of prime interest for the computation of metrics related to coded transmissions over correlated channels, and they are confronted by end-to-end wave-optics simulations in the case of a geosynchronous satellite (GEO)-to-ground and a low earth orbit satellite (LEO)-to-ground scenario...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29328058/behaviour-of-niobium-during-early-earth-s-differentiation-insights-from-its-local-structure-and-oxidation-state-in-silicate-melts-at-high-pressure
#7
Chrystele Sanloup, Benjamin Cochain, Charlotte de Grouchy, Konstantin Glazyrin, Zuzana Konopkova, Hanns-Peter Liermann, Innokenty Kantor, Raffaella Torchio, O Mathon, Tetsuo Irifune
Niobium (Nb) is one of the key trace elements used to understand Earth's formation and differentiation, and is remarkable for its deficiency relative to tantalum in terrestrial rocks compared to the building chondritic blocks. In this context, the local environment of Nb in silica-rich melts and glasses is studied by in situ X-ray absorption spectroscopy (XAS) at high pressure (P) up to 9.3 GPa and 1350 K using resistive-heating diamond-anvil cells. Nb is slightly less oxidized in the melt (intermediate valence between +4 and +5) than in the glass (+5), an effect evidenced from the shift of the Nb-edge towards lower energies...
January 12, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29326998/in-situ-development-of-amorphous-mn-co-p-shell-on-mnco2o4-nanowire-array-for-superior-oxygen-evolution-electrocatalysis-in-alkaline-media
#8
Jingrui Han, Shuai Hao, Zhiang Liu, Abdullah M Asiri, Xuping Sun, Yuanhong Xu
Exploitation of efficient and earth-abundant electrocatalysts for the oxygen evolution reaction (OER) is of great importance. Herein, we report that the formation of an amorphous Mn-Co-P shell on MnCo2O4 can boost its OER activity in alkaline media. The core-shell Mn-Co-P@MnCo2O4 nanowire array on Ti mesh (Mn-Co-P@MnCo2O4/Ti) shows excellent electrochemical catalytic activity and requires an overpotential of 269 mV to drive 10 mA cm-2 in 1.0 M KOH, which is 93 mV less than that for the MnCo2O4 nanoarray. Notably, this catalyst also shows strong long-term electrochemical durability with its activity being maintained for at least 100 h and achieves a high turnover frequency of 1...
January 12, 2018: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29326985/use-of-an-autonomous-surface-vehicle-reveals-small-scale-diel-vertical-migrations-of-zooplankton-and-susceptibility-to-light-pollution-under-low-solar-irradiance
#9
Martin Ludvigsen, Jørgen Berge, Maxime Geoffroy, Jonathan H Cohen, Pedro R De La Torre, Stein M Nornes, Hanumant Singh, Asgeir J Sørensen, Malin Daase, Geir Johnsen
Light is a major cue for nearly all life on Earth. However, most of our knowledge concerning the importance of light is based on organisms' response to light during daytime, including the dusk and dawn phase. When it is dark, light is most often considered as pollution, with increasing appreciation of its negative ecological effects. Using an Autonomous Surface Vehicle fitted with a hyperspectral irradiance sensor and an acoustic profiler, we detected and quantified the behavior of zooplankton in an unpolluted light environment in the high Arctic polar night and compared the results with that from a light-polluted environment close to our research vessels...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29326981/adaptation-required-to-preserve-future-high-end-river-flood-risk-at-present-levels
#10
Sven N Willner, Anders Levermann, Fang Zhao, Katja Frieler
Earth's surface temperature will continue to rise for another 20 to 30 years even with the strongest carbon emission reduction currently considered. The associated changes in rainfall patterns can result in an increased flood risk worldwide. We compute the required increase in flood protection to keep high-end fluvial flood risk at present levels. The analysis is carried out worldwide for subnational administrative units. Most of the United States, Central Europe, and Northeast and West Africa, as well as large parts of India and Indonesia, require the strongest adaptation effort...
January 2018: Science Advances
https://www.readbyqxmd.com/read/29326250/earth-scientists-list-top-priorities-for-space-missions
#11
Paul Voosen
No abstract text is available yet for this article.
January 12, 2018: Science
https://www.readbyqxmd.com/read/29324435/intermediate-valence-state-of-the-sm-and-eu-in-smb6-and-eucu2si2-neutron-spectroscopy-data-and-analysis
#12
P S Savchenkov, P A Alekseev, A Podlesnyak, A I Kolesnikov, K S Nemkovski
Magnetic neutron scattering data for Sm (SmB6, Sm(Y)S) and Eu (EuCu2Si2-x Ge x ) intermediate-valence compounds have been analysed in terms of a generalized model of the intermediate-radius exciton. Special attention is paid to the correlation between the average ion's valence and parameters of the low-energy excitation in the neutron spectra, such as the resonance mode, including its magnetic form factor. Along with specific features of the formation of the intermediate-valence state for Sm and Eu ions, common physical mechanisms have been revealed for systems based on these elements from the middle of the rare-earth series...
January 11, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/29324395/effects-of-lanthanum-on-microcystis-aeruginosa-attention-to-the-changes-in-composition-and-content-of-cellular-microcystins
#13
Fei Shen, Lihong Wang, Qing Zhou, Xiaohua Huang
Algal blooms threaten human health and aquatic ecosystem through the production of microcystins (MCs) by toxic strains. The accumulation of rare earth elements (REEs) in water affects the growth and physiological activities of algae. However, whether or how REEs affect cellular microcystins (MCs) is largely unknown. In this study, the effects of lanthanum ion [La(III)], a type of REE, on the MCs in Microcystis aeruginosa were investigated, and the mechanism of the effect was analyzed using ecological stoichiometry...
January 6, 2018: Aquatic Toxicology
https://www.readbyqxmd.com/read/29323892/same-substrate-many-reactions-oxygen-activation-in-flavoenzymes
#14
Elvira Romero, J Rubén Gómez Castellanos, Giovanni Gadda, Marco W Fraaije, Andrea Mattevi
Over time, organisms have evolved strategies to cope with the abundance of dioxygen on Earth. Oxygen-utilizing enzymes tightly control the reactions involving O2 mostly by modulating the reactivity of their cofactors. Flavins are extremely versatile cofactors that are capable of undergoing redox reactions by accepting either one electron or two electrons, alternating between the oxidized and the reduced states. The physical and chemical principles of flavin-based chemistry have been investigated widely. In the following pages we summarize the state of the art on a key area of research in flavin enzymology: the molecular basis for the activation of O2 by flavin-dependent oxidases and monooxygenases...
January 11, 2018: Chemical Reviews
https://www.readbyqxmd.com/read/29323299/rotation-in-c-ii-emitting-gas-in-two-galaxies-at-a-redshift-of-6-8
#15
Renske Smit, Rychard J Bouwens, Stefano Carniani, Pascal A Oesch, Ivo Labbé, Garth D Illingworth, Paul van der Werf, Larry D Bradley, Valentino Gonzalez, Jacqueline A Hodge, Benne W Holwerda, Roberto Maiolino, Wei Zheng
The earliest galaxies are thought to have emerged during the first billion years of cosmic history, initiating the ionization of the neutral hydrogen that pervaded the Universe at this time. Studying this 'epoch of reionization' involves looking for the spectral signatures of ancient galaxies that are, owing to the expansion of the Universe, now very distant from Earth and therefore exhibit large redshifts. However, finding these spectral fingerprints is challenging. One spectral characteristic of ancient and distant galaxies is strong hydrogen-emission lines (known as Lyman-α lines), but the neutral intergalactic medium that was present early in the epoch of reionization scatters such Lyman-α photons...
January 10, 2018: Nature
https://www.readbyqxmd.com/read/29323296/a-rapid-decrease-in-the-rotation-rate-of-comet-41p-tuttle-giacobini-kres%C3%A3-k
#16
Dennis Bodewits, Tony L Farnham, Michael S P Kelley, Matthew M Knight
Cometary outgassing can produce torques that change the spin state of the cometary nucleus, which in turn influences the evolution and lifetime of the comet. If these torques increase the rate of rotation to the extent that centripetal forces exceed the material strength of the nucleus, the comet can fragment. Torques that slow down the rotation can cause the spin state to become unstable, but if the torques persist the nucleus can eventually reorient itself and the rotation rate can increase again. Simulations predict that most comets go through a short phase of rapid changes in spin state, after which changes occur gradually over longer times...
January 10, 2018: Nature
https://www.readbyqxmd.com/read/29323150/stratification-induced-reorientation-of-disk-settling-through-ambient-density-transition
#17
Magdalena M Mrokowska
Settling due to gravity force is a basic transport mechanism of solid particles in fluids in the Earth. A large portion of particles occurring in nature and used in technical applications are non-spherical. Settling of particles is usually studied in homogeneous ambient conditions, however, stratification is inherent of natural fluids. It has been acknowledged that stratification modifies the velocity of settling spheres and amorphous aggregates. However, the effect of particle shape on the dynamics of settling through density-stratified ambient fluid has not been recognized well enough...
January 11, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29323115/wet-dry-cycles-enable-the-parallel-origin-of-canonical-and-non-canonical-nucleosides-by-continuous-synthesis
#18
Sidney Becker, Christina Schneider, Hidenori Okamura, Antony Crisp, Tynchtyk Amatov, Milan Dejmek, Thomas Carell
The molecules of life were created by a continuous physicochemical process on an early Earth. In this hadean environment, chemical transformations were driven by fluctuations of the naturally given physical parameters established for example by wet-dry cycles. These conditions might have allowed for the formation of (self)-replicating RNA as the fundamental biopolymer during chemical evolution. The question of how a complex multistep chemical synthesis of RNA building blocks was possible in such an environment remains unanswered...
January 11, 2018: Nature Communications
https://www.readbyqxmd.com/read/29322618/genome-enabled-metabolic-reconstruction-of-dominant-chemosynthetic-colonizers-in-deep-sea-massive-sulfide-deposits
#19
Shingo Kato, Takazo Shibuya, Yoshihiro Takaki, Miho Hirai, Takuro Nunoura, Katsuhiko Suzuki
Deep-sea massive sulfide deposits remaining after ceasing of hydrothermal activity potentially provide energy for a chemosynthetic ecosystem in the dark, cold marine environments. Although yet-uncultivated bacteria in the phylum Nitrospirae and the class Deltaproteobacteria are known to dominate the microbial communities of sulfide deposits at and below the seafloor, their metabolic capabilities remain largely elusive. Here, we reveal the metabolic potential of these yet-uncultivated bacteria in hydrothermally inactive sulfide deposits collected at the Southern Mariana Trough by seafloor drilling...
January 10, 2018: Environmental Microbiology
https://www.readbyqxmd.com/read/29322097/toward-a-leading-indicator-of-catastrophic-shifts-in-complex-systems-assessing-changing-conditions-in-nation-states
#20
Leisha Vance, Tarsha Eason, Heriberto Cabezas, Michael E Gorman
The 20th century was characterized by substantial change on a global scale. There were multiple wars and unrest, social and political transitions, technological innovation and widespread development that impacted every corner of the earth. In order to assess the sustainability implications of these changes, we conducted a study of three advanced nations particularly affected during this time: France, Germany and the United States (USA). All three nation states withstood these changes and yet continued to thrive, which speaks to their resilience...
December 2017: Heliyon
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