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https://www.readbyqxmd.com/read/28738612/sorption-luminescence-method-for-determination-of-terbium-using-transcarpathian-clinoptilolite
#1
V O Vasylechko, G V Gryshchouk, V P Zakordonskiy, L O Vasylechko, M Schmidt, I M Leshchack, Ya M Kalychak, S R Bagday
Sorption-luminescent method for terbium determination based on natural Transcarpathian clinoptilolite without using of complex synthetic organic compounds and toxic solvents was proposed. Optimal luminophore preparation conditions are sorption of Tb(III) on zeolite in the borate buffer solution with pH 8.25 and further calcination of clinoptilolite-Tb(III) samples at 500°C. For luminescence excitation the rays with wavelength of λ = 220nm of were used. Luminescence intensity at λ = 545nm was selected as analytical parameter for a quantitative terbium determination...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738410/no-large-population-of-unbound-or-wide-orbit-jupiter-mass-planets
#2
Przemek Mróz, Andrzej Udalski, Jan Skowron, Radosław Poleski, Szymon Kozłowski, Michał K Szymański, Igor Soszyński, Łukasz Wyrzykowski, Paweł Pietrukowicz, Krzysztof Ulaczyk, Dorota Skowron, Michał Pawlak
Planet formation theories predict that some planets may be ejected from their parent systems as result of dynamical interactions and other processes. Unbound planets can also be formed through gravitational collapse, in a way similar to that in which stars form. A handful of free-floating planetary-mass objects have been discovered by infrared surveys of young stellar clusters and star-forming regions as well as wide-field surveys, but these studies are incomplete for objects below five Jupiter masses. Gravitational microlensing is the only method capable of exploring the entire population of free-floating planets down to Mars-mass objects, because the microlensing signal does not depend on the brightness of the lensing object...
July 24, 2017: Nature
https://www.readbyqxmd.com/read/28738409/elements-of-eoarchean-life-trapped-in-mineral-inclusions
#3
T Hassenkam, M P Andersson, K N Dalby, D M A Mackenzie, M T Rosing
Metasedimentary rocks from Isua, West Greenland (over 3,700 million years old) contain (13)C-depleted carbonaceous compounds, with isotopic ratios that are compatible with a biogenic origin. Metamorphic garnet crystals in these rocks contain trails of carbonaceous inclusions that are contiguous with carbon-rich sedimentary beds in the host rock, where carbon is fully graphitized. Previous studies have not been able to document other elements of life (mainly hydrogen, oxygen, nitrogen and phosphorus) structurally bound to this carbonaceous material...
July 24, 2017: Nature
https://www.readbyqxmd.com/read/28738251/quantification-of-some-elements-of-nuclear-and-industrial-interest-from-zircon-mineral-using-neutron-activation-analysis-and-passive-gamma-ray-spectroscopy
#4
M F Attallah, M A Hilal, S I Moussa
A combined of various nuclear and analytical techniques were used for characterization of Egyptian zircon ore. Neutron activation analysis has been used for determination of the major, minor and trace elements from zircon ore. Non-destructive gamma-ray technique is also used for the radiometric analysis of zircon ore to quantify the natural radionuclides such as (238)U, (235)U, (232)Th, (226)Ra and (40)K. Zircon ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), and scanning electron microscopy (SEM)...
July 14, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28738206/a-preliminary-study-on-the-effects-of-lanthanum-iii-on-plant-vitronectin-like-protein-and-its-toxicological-basis
#5
Lihong Wang, Jingfang He, Qing Yang, Xiaodong Li, Haiyan Wei, David D Y Chen, Xiaohua Huang
Vitronectin-like protein (VN) is widely found outside plant plasma membranes. The VN molecular surface contains a large number of active groups that combine strongly with rare earth elements (REEs), which means that VN is a preferential binding target for REEs exhibiting their toxic effects, but the toxicological mechanism remains unknown. This study used transmission electron microscopy, circular dichroism, fluorescence spectrometry, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and calculational chemistry (homology modeling, molecular dynamics simulation and quantum chemical calculation) to preliminarily investigate the effect of lanthanum [La(III)] as an REE, on the structure of VN and its toxicological mechanism...
July 21, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28737704/toxicity-at-the-edge-of-life-a-review-on-cyanobacterial-toxins-from-extreme-environments
#6
REVIEW
Samuel Cirés, María Cristina Casero, Antonio Quesada
Cyanotoxins are secondary metabolites produced by cyanobacteria, of varied chemical nature and toxic effects. Although cyanobacteria thrive in all kinds of ecosystems on Earth even under very harsh conditions, current knowledge on cyanotoxin distribution is almost restricted to freshwaters from temperate latitudes. In this review, we bring to the forefront the presence of cyanotoxins in extreme environments. Cyanotoxins have been reported especially in polar deserts (both from the Arctic and Antarctica) and alkaline lakes, but also in hot deserts, hypersaline environments, and hot springs...
July 24, 2017: Marine Drugs
https://www.readbyqxmd.com/read/28737499/tunable-indirect-direct-transition-of-few-layer-snse-via-interface-engineering
#7
Hansika Iroshini Sirikumara, Thushari Jayasekera
Tin Selenide (SnSe) is one of the best thermoelectric materials reported to date. The possibility of growing few-layer SnSe helped boost the interest in this long-known, earth abundant material. Pristine SnSe in bulk, mono- and few-layer forms are reported to have indirect electronic bandgaps. Possible indirect-direct transition in SnSe is attractive for its optoelectronic-related applications. Based on the results from first principles Density Functional Theory (DFT) calculations, we carefully analyzed electronic band structures of bulk, and bilayer SnSe with various interlayer stackings...
July 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28737010/carbonate-ooids-of-the-mesoarchaean-pongola-supergroup-south-africa
#8
M Siahi, A Hofmann, S Master, C W Mueller, A Gerdes
Ooids from the Mesoarchaean Chobeni Formation, Pongola Supergroup, KwaZulu-Natal, South Africa are older than any ooids reported to date. They are made of dolomite and ankerite and show concentric, radial-concentric, micritic, and radial fabrics. Radial ooids are interpreted to have originated from high-Mg-calcite and probably formed by microbial activity in a low-energy regime, while concentric ooids had an aragonite precursor and formed biotically under agitated/high-energy environmental conditions. Micritic ooids formed via the recrystallization of concentric ooids...
July 24, 2017: Geobiology
https://www.readbyqxmd.com/read/28736951/component-customizable-porous-rare-earth-based-colloidal-spheres-towards-highly-effective-catalysts-and-bioimaging-applications
#9
Cheng Chao Li, Xianhong Rui, Weifeng Wei, Libao Chen
Multicomponent porous colloidal spheres are of interest because they not only show a combination of the properties associated with all different components, but also usually present synergy effect. However, combination of different components in a single porous sphere is still greatly challenged due to different precipitation behaviors of each component. In this work, we have developed a general synthetic route to prepare several categories of porous monodisperse RE-based colloidal spheres with customizable elemental compositions and uniform element distribution...
July 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28734132/high-dimensional-single-cell-mapping-of-cerium-distribution-in-the-lung-immune-microenvironment-of-an-active-smoker
#10
Adeeb H Rahman, Yonit Lavin, Soma Kobayashi, Andrew Leader, Miriam Merad
BACKGROUND: Mass cytometry leverages inductively coupled mass spectrometry to perform high dimensional single cell analyses using antibodies tagged with rare earth isotopes that are considered to be largely absent in biological samples. We have recently noted an unusual exception to this rule while analyzing tissue samples from patients undergoing surgical resection for early stage lung cancer, and here we present a detailed cytometric characterization of cerium in a clinical patient sample...
July 22, 2017: Cytometry. Part B, Clinical Cytometry
https://www.readbyqxmd.com/read/28733819/estimating-environmental-value-losses-from-earth-materials-excavation-and-infilling-for-large-scale-airport-construction-a-case-of-dalian-offshore-airport-dalian-china
#11
Hua-Kun Yan, Nuo Wang, Nuan Wu, Nan-Qi Song, Dao-Li Zhu
Large-scale airport construction removes large quantities of earth materials, resulting in serious environmental pollution and ecosystem damage. However, studies of environmental concerns caused by the materials used in airport construction are still preliminary, and those case studies on the impacts of large-scale offshore airport development are very limited. China's Dalian Offshore Airport is considered here to study the environmental value loss from 240 million m(3) of materials excavations and 21 km(2) of artificial island infillings...
July 21, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28733603/sediment-transport-drives-tidewater-glacier-periodicity
#12
Douglas Brinkerhoff, Martin Truffer, Andy Aschwanden
Most of Earth's glaciers are retreating, but some tidewater glaciers are advancing despite increasing temperatures and contrary to their neighbors. This can be explained by the coupling of ice and sediment dynamics: a shoal forms at the glacier terminus, reducing ice discharge and causing advance towards an unstable configuration followed by abrupt retreat, in a process known as the tidewater glacier cycle. Here we use a numerical model calibrated with observations to show that interactions between ice flow, glacial erosion, and sediment transport drive these cycles, which occur independent of climate variations...
July 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28733590/hypersaline-sapropels-act-as-hotspots-for-microbial-dark-matter
#13
Adrian-Ştefan Andrei, Andreea Baricz, Michael Scott Robeson, Manuela Raluca Păuşan, Tudor Tămaş, Cecilia Chiriac, Edina Szekeres, Lucian Barbu-Tudoran, Erika Andrea Levei, Cristian Coman, Mircea Podar, Horia Leonard Banciu
Present-day terrestrial analogue sites are crucial ground truth proxies for studying life in geochemical conditions close to those assumed to be present on early Earth or inferred to exist on other celestial bodies (e.g. Mars, Europa). Although hypersaline sapropels are border-of-life habitats with moderate occurrence, their microbiological and physicochemical characterization lags behind. Here, we study the diversity of life under low water activity by describing the prokaryotic communities from two disparate hypersaline sapropels (Transylvanian Basin, Romania) in relation to geochemical milieu and pore water chemistry, while inferring their role in carbon cycling by matching taxa to known taxon-specific biogeochemical functions...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28733579/the-permeability-of-fractured-rocks-in-pressurised-volcanic-and-geothermal-systems
#14
A Lamur, J E Kendrick, G H Eggertsson, R J Wall, J D Ashworth, Y Lavallée
The connectivity of rocks' porous structure and the presence of fractures influence the transfer of fluids in the Earth's crust. Here, we employed laboratory experiments to measure the influence of macro-fractures and effective pressure on the permeability of volcanic rocks with a wide range of initial porosities (1-41 vol. %) comprised of both vesicles and micro-cracks. We used a hand-held permeameter and hydrostatic cell to measure the permeability of intact rock cores at effective pressures up to 30 MPa; we then induced a macro-fracture to each sample using Brazilian tensile tests and measured the permeability of these macro-fractured rocks again...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28733006/physical-and-chemical-mechanism-underlying-ultrasonically-enhanced-hydrochloric-acid-leaching-of-non-oxidative-roasting-of-bastnaesite
#15
Dongliang Zhang, Mei Li, Kai Gao, Jianfei Li, Yujun Yan, Xingyu Liu
In this study, we investigated an alternative to the conventional hydrochloric acid leaching of roasted bastnaesite. The studies suggested that the rare earth oxyfluorides in non-oxidatively roasted bastnaesite can be selectively leached only at elevated temperatures Further, the Ce(IV) in oxidatively roasted bastnaesite does not leach readily at low temperatures, and it is difficult to induce it to form a complex with F(-) ions in order to increase the leaching efficiency. Moreover, it is inevitably reduced to Ce(III) at elevated temperatures...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28731691/singlet-oxygen-photophysics-in-liquid-solvents-converging-on-a-unified-picture
#16
Mikkel Bregnhøj, Michael Westberg, Boris F Minaev, Peter R Ogilby
Singlet oxygen, O2(a(1)Δg), the lowest excited electronic state of molecular oxygen, is an omnipresent part of life on earth. It is readily formed through a variety of chemical and photochemical processes, and its unique reactions are important not just as a tool in chemical syntheses but also in processes that range from polymer degradation to signaling in biological cells. For these reasons, O2(a(1)Δg) has been the subject of intense activity in a broad distribution of scientific fields for the past ∼50 years...
July 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28731294/the-bioinorganic-chemistry-of-lead-in-the-context-of-its-toxicity
#17
Wolfgang Maret
Owing to its abundance on earth and its multiple uses by humans, lead (Pb) is a major toxicant that has threatened human health for millennia and continues to do so. There is no safe level of exposure, necessitating a nuanced approach to its control in the food we consume, the water we drink, and the air we breathe. Turnover in soft tissues is within days. In contrast, lead accumulates in bone and turns over with a half-life of about 30 years, though it can be mobilized from bone under physiological and pathophysiological conditions of bone resorption...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28729857/nutrient-acquisition-and-the-metabolic-potential-of-photoferrotrophic-chlorobi
#18
Katharine J Thompson, Rachel L Simister, Aria S Hahn, Steven J Hallam, Sean A Crowe
Anoxygenic photosynthesis evolved prior to oxygenic photosynthesis and harnessed energy from sunlight to support biomass production on the early Earth. Models that consider the availability of electron donors predict that anoxygenic photosynthesis using Fe(II), known as photoferrotrophy, would have supported most global primary production before the proliferation of oxygenic phototrophs at approximately 2.3 billion years ago. These photoferrotrophs have also been implicated in the deposition of banded iron formations, the world's largest sedimentary iron ore deposits that formed mostly in late Archean and early Proterozoic Eons...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28729748/on-flare-cme-characteristics-from-sun-to-earth-combining-remote-sensing-image-data-with-in-situ-measurements-supported-by-modeling
#19
Manuela Temmer, Julia K Thalmann, Karin Dissauer, Astrid M Veronig, Johannes Tschernitz, Jürgen Hinterreiter, Luciano Rodriguez
We analyze the well-observed flare and coronal mass ejection (CME) from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of effects - from Sun to Earth - to better understand the dynamic evolution of the CME and its embedded magnetic field. We study in detail the solar surface and atmosphere associated with the flare and CME using the Solar Dynamics Observatory (SDO) and ground-based instruments. We also track the CME signature off-limb with combined extreme ultraviolet (EUV) and white-light data from the Solar Terrestrial Relations Observatory (STEREO)...
2017: Solar Physics
https://www.readbyqxmd.com/read/28729660/a-novel-optical-thermometry-based-on-the-energy-transfer-from-charge-transfer-band-to-eu-3-dy-3-ions
#20
Jing Wang, Yanyan Bu, Xiangfu Wang, Hyo Jin Seo
Optical thermometry based on the up-conversion intensity ratio of thermally coupled levels of rare earth ions has been widely studied to achieve an inaccessible temperature measurement in submicron scale. In this work, a novel optical temperature sensing strategy based on the energy transfer from charge transfer bands of W-O and Eu-O to Eu(3+)-Dy(3+) ions is proposed. A series of Eu(3+)/Dy(3+) co-doped SrWO4 is synthesized by the conventional high-temperature solid-state method. It is found that the emission spectra, emission intensity ratio of Dy(3+) (572 nm) and Eu(3+) (615 nm), fluorescence color, lifetime decay curves of Dy(3+) (572 nm) and Eu(3+) (615 nm), and relative and absolute sensitivities of Eu(3+)/Dy(3+) co-doped SrWO4 are temperature dependent under the 266 nm excitation in the temperature range from 11 K to 529 K...
July 20, 2017: Scientific Reports
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