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https://www.readbyqxmd.com/read/29043588/determination-of-element-composition-and-extraterrestrial-material-occurrence-in-moss-and-lichen-samples-from-king-george-island-antarctica-using-reactor-neutron-activation-analysis-and-sem-microscopy
#1
Tomasz Mróz, Katarzyna Szufa, Marina V Frontasyeva, Vladimir Tselmovich, Tatiana Ostrovnaya, Andrzej Kornaś, Maria A Olech, Jerzy W Mietelski, Kamil Brudecki
Seven lichens (Usnea antarctica and U. aurantiacoatra) and nine moss samples (Sanionia uncinata) collected in King George Island were analyzed using instrumental neutron activation analysis, and concentration of major and trace elements was calculated. For some elements, the concentrations observed in moss samples were higher than corresponding values reported from other sites in the Antarctica, but in the lichens, these were in the same range of concentrations. Scanning electron microscopy (SEM) and statistical analysis showed large influence of volcanic-origin particles...
October 18, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29043347/zinc-ing-it-out-zinc-homeostasis-mechanisms-and-their-impact-on-the-pathogenesis-of-human-pathogen-group-a-streptococcus
#2
REVIEW
Nishanth Makthal, Muthiah Kumaraswami
Group A Streptococccus (GAS) is a major human pathogen that causes significant morbidity and mortality. Zinc is an essential trace element required for GAS growth, however, zinc can be toxic at excess concentrations. The bacterial strategies to maintain zinc sufficiency without incurring zinc toxicity play a crucial role in host-GAS interactions and have a significant impact on GAS pathogenesis. The host deploys nutritional immune mechanisms to retard GAS growth by causing either zinc deprivation or zinc poisoning...
October 18, 2017: Metallomics: Integrated Biometal Science
https://www.readbyqxmd.com/read/29041735/analysis-of-spurious-diffraction-orders-of-computer-generated-hologram-in-symmetric-aspheric-metrology
#3
Yiwei He, Xi Hou, Fan Wu, Xinxue Ma, Rongguang Liang
Computer-generated hologram (CGH) has been widely used as a wavefront compensator in symmetric aspheric metrology. As a diffractive element, it generates different diffraction orders, but only the 1st-order diffraction is used to test aspheric surface. The light from spurious diffraction orders (SDO) will produce many high-frequency fringes in interferogram and reduce measurement accuracy. In this paper, we regard the CGH null system as an imaging system and develop an aberration model in Seidel formalism to analyze the SDO...
August 21, 2017: Optics Express
https://www.readbyqxmd.com/read/29041652/method-of-single-step-full-parallax-synthetic-holographic-stereogram-printing-based-on-effective-perspective-images-segmentation-and-mosaicking
#4
Jian Su, Quan Yuan, Yingqing Huang, Xiaoyu Jiang, Xingpeng Yan
With the principle of ray-tracing and the reversibility of light propagation, a new method of single-step full parallax synthetic holographic stereogram printing based on effective perspective images' segmentation and mosaicking (EPISM) is proposed. The perspective images of the scene are first sampled by a virtual camera and the exposing images, which are called synthetic effective perspective images, are achieved using the algorithm of effective perspective images' segmentation and mosaicking according to the propagation law of light and the viewing frustum effect of human eyes...
September 18, 2017: Optics Express
https://www.readbyqxmd.com/read/29041641/all-reflective-multiphoton-microscope
#5
Babak Amirsolaimani, Benjamin Cromey, N Peyghambarian, Khanh Kieu
We present the design, construction, and characterization of a multiphoton microscope that uses reflective elements for beam shaping and steering. This compact all reflective design removes the adverse effects of dispersion on laser pulse broadening as well as chromatic aberration in the focusing of broadband and multicolored laser sources. The design of this system is discussed in detail, including aberrations analysis via ray-tracing simulation and opto-mechanical design. The resolution of this mirror based all-reflective microscope is characterized using fluorescent microbeads...
September 18, 2017: Optics Express
https://www.readbyqxmd.com/read/29041509/measurement-system-and-model-for-simultaneously-measuring-6dof-geometric-errors
#6
Yuqiong Zhao, Bin Zhang, Qibo Feng
A measurement system to simultaneously measure six degree-of-freedom (6DOF) geometric errors is proposed. The measurement method is based on a combination of mono-frequency laser interferometry and laser fiber collimation. A simpler and more integrated optical configuration is designed. To compensate for the measurement errors introduced by error crosstalk, element fabrication error, laser beam drift, and nonparallelism of two measurement beam, a unified measurement model, which can improve the measurement accuracy, is deduced and established using the ray-tracing method...
September 4, 2017: Optics Express
https://www.readbyqxmd.com/read/29040932/fabrication-of-porous-covalent-organic-frameworks-as-selective-and-advanced-adsorbents-for-the-on-line-preconcentration-of-trace-elements-against-the-complex-sample-matrix
#7
Jing-Min Liu, Xing-Zhi Wang, Chao-Yue Zhao, Jia-Li Hao, Guo-Zhen Fang, Shuo Wang
Herein, for the first time, the typical porous Covalent Organic Frameworks (COFs) CTpBD with superior chemical stability and large surface area were applied as sorbents for solid phase extraction of trace ions via flow injection followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The well-prepared and fully-characterized CTpBD COFs were filled in solid phase extraction cartridge as novel and robust adsorbents for element analysis. Separation and enrichment of Cr (III), Mn (II), Co (II), Ni (II), Cd (II), V (V), Cu (II), As (III), Se (IV), and Mo (VI) was then carried out, and the contents were measured by ICP-MS...
October 12, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29039350/the-toxicity-of-vanadium-on-gastrointestinal-urinary-and-reproductive-system-and-its-influence-on-fertility-and-fetuses-malformations
#8
Aleksandra Wilk, Dagmara Szypulska-Koziarska, Barbara Wiszniewska
Vanadium is a transition metal that has a unique and beneficial effect on both humans and animals. For many years, studies have suggested that vanadium is an essential trace element. Its biological properties are of interest due to its therapeutic potential, including in the treatment of diabetes mellitus. Vanadium deficiencies can lead to a range of pathologies. However, excessive concentration of this metal can cause irreversible damage to various tissues and organs. Vanadium toxicity mainly manifests in gastrointestinal symptoms, including diarrhea, vomiting, and weight reduction...
September 25, 2017: Postȩpy Higieny i Medycyny Doświadczalnej
https://www.readbyqxmd.com/read/29039206/oxidative-stress-in-ischemia-and-reperfusion-current-concepts-novel-ideas-and-future-perspectives
#9
Christoph Sinning, Dirk Westermann, Peter Clemmensen
Oxidative stress remains a major contributor to myocardial injury after ischemia followed by reperfusion (I/R) as the reperfusion of the myocardial infarction (MI) area inevitably leads to a cascade of I/R injury. This review focused on concepts of the antioxidative defense system and elucidates recent research using antioxidants like vitamin C, E and β-carotene or essential trace elements to activate compounds of antioxidative pathways in the circulation. In this context, important defense mechanisms like superoxide dismutase and glutathione peroxidase will be described...
October 17, 2017: Biomarkers in Medicine
https://www.readbyqxmd.com/read/29037570/trace-elements-and-arsenic-speciation-in-tissues-of-tube-dwelling-polychaetes-from-hydrothermal-vent-ecosystems-east-pacific-rise-an-ecological-role-as-antipredatory-strategy
#10
Marta Di Carlo, Donato Giovannelli, Daniele Fattorini, Nadine Le Bris, Costantino Vetriani, Francesco Regoli
Hydrothermal vent systems are inhabited by dense benthic communities adapted to extreme conditions such as high temperature, hydrogen sulphide (H2S) and elevated fluxes of metals. In the present work, a wide range of trace elements (Ag, Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, V and Zn) were measured in tissues of three tube dwelling annelids, Alvinella pompejana, Alvinella caudata and Riftia pachyptila, which colonize distinct habitats of the East Pacific Rise (EPR) at 2500 m depth. Metals concentrations in alvinellids were often 2-4 orders of magnitude higher than those commonly found in marine organisms, while much lower values were observed in the vestimentiferan polychaete...
October 5, 2017: Marine Environmental Research
https://www.readbyqxmd.com/read/29037404/do-the-ornamented-osteoderms-influence-the-heat-conduction-through-the-skin-a-finite-element-analysis-in-crocodylomorpha
#11
F Clarac, F Goussard, L Teresi, Vde Buffrénil, V Sansalone
In order to assess the implication of the crocodylomorph ornamented osteoderms on the skin conduction during basking, we have performed three dimensional modeling and finite element analyses on a sample which includes both extant dry bones and well-preserved fossils tracing back to the Early Jurassic. In purpose to reveal the possible implication of the superficial ornamentation on the osteoderm heat conduction, we repeated the simulation on an equivalent set of smoothed 3D-modeled osteoderms. The comparison of the results evidenced that the presence of the apical sculpture has no significant impact on the osteoderm global conduction...
October 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29036152/single-freeform-surface-design-for-prescribed-input-wavefront-and-target-irradiance
#12
Christoph Bösel, Herbert Gross
In beam shaping applications, the minimization of the number of necessary optical elements for the beam shaping process can benefit the compactness of the optical system and reduce its cost. The single freeform surface design for input wavefronts, which are neither planar nor spherical, is therefore of interest. In this work, the design of single freeform surfaces for a given zero-étendue source and complex target irradiances is investigated. Hence, not only collimated input beams or point sources are assumed...
September 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29035796/characterization-of-iron-and-manganese-minerals-and-their-associated-microbiota-in-different-mine-sites-to-reveal-the-potential-interactions-of-microbiota-with-mineral-formation
#13
Jin Hee Park, Bong-Soo Kim, Chul-Min Chon
Different environmental conditions such as pH and dissolved elements of mine stream induce precipitation of different minerals and their associated microbial community may vary. Therefore, mine precipitates from various environmental conditions were collected and their associated microbiota were analyzed through metagenomic DNA sequencing. Various Fe and Mn minerals including ferrihydrite, schwertmannite, goethite, birnessite, and Mn-substituted δ-FeOOH (δ-(Fe1-x, Mnx)OOH) were found in the different environmental conditions...
October 9, 2017: Chemosphere
https://www.readbyqxmd.com/read/29035270/quantifying-trace-element-and-isotope-fluxes-at-the-ocean-sediment-boundary-a-review
#14
William B Homoky, Thomas Weber, William M Berelson, Tim M Conway, Gideon M Henderson, Marco van Hulten, Catherine Jeandel, Silke Severmann, Alessandro Tagliabue
Quantifying fluxes of trace elements and their isotopes (TEIs) at the ocean's sediment-water boundary is a pre-eminent challenge to understand their role in the present, past and future ocean. There are multiple processes that drive the uptake and release of TEIs, and properties that determine their rates are unevenly distributed (e.g. sediment composition, redox conditions and (bio)physical dynamics). These factors complicate our efforts to find, measure and extrapolate TEI fluxes across ocean basins. GEOTRACES observations are unveiling the oceanic distributions of many TEIs for the first time...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035268/trace-element-and-isotope-deposition-across-the-air-sea-interface-progress-and-research-needs
#15
REVIEW
A R Baker, W M Landing, E Bucciarelli, M Cheize, S Fietz, C T Hayes, D Kadko, P L Morton, N Rogan, G Sarthou, R U Shelley, Z Shi, A Shiller, M M P van Hulten
The importance of the atmospheric deposition of biologically essential trace elements, especially iron, is widely recognized, as are the difficulties of accurately quantifying the rates of trace element wet and dry deposition and their fractional solubility. This paper summarizes some of the recent progress in this field, particularly that driven by the GEOTRACES, and other, international research programmes. The utility and limitations of models used to estimate atmospheric deposition flux, for example, from the surface ocean distribution of tracers such as dissolved aluminium, are discussed and a relatively new technique for quantifying atmospheric deposition using the short-lived radionuclide beryllium-7 is highlighted...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035267/coastal-ocean-and-shelf-sea-biogeochemical-cycling-of-trace-elements-and-isotopes-lessons-learned-from-geotraces
#16
REVIEW
Matthew A Charette, Phoebe J Lam, Maeve C Lohan, Eun Young Kwon, Vanessa Hatje, Catherine Jeandel, Alan M Shiller, Gregory A Cutter, Alex Thomas, Philip W Boyd, William B Homoky, Angela Milne, Helmuth Thomas, Per S Andersson, Don Porcelli, Takahiro Tanaka, Walter Geibert, Frank Dehairs, Jordi Garcia-Orellana
Continental shelves and shelf seas play a central role in the global carbon cycle. However, their importance with respect to trace element and isotope (TEI) inputs to ocean basins is less well understood. Here, we present major findings on shelf TEI biogeochemistry from the GEOTRACES programme as well as a proof of concept for a new method to estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment micronutrient fluxes and basin-scale estimates of submarine groundwater discharge...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035266/lead-isotope-exchange-between-dissolved-and-fluvial-particulate-matter-a-laboratory-study-from-the-johor-river-estuary
#17
Mengli Chen, Edward A Boyle, Jong-Mi Lee, Intan Nurhati, Cheryl Zurbrick, Adam D Switzer, Gonzalo Carrasco
Atmospheric aerosols are the dominant source of Pb to the modern marine environment, and as a result, in most regions of the ocean the Pb isotopic composition of dissolved Pb in the surface ocean (and in corals) matches that of the regional aerosols. In the Singapore Strait, however, there is a large offset between seawater dissolved and coral Pb isotopes and that of the regional aerosols. We propose that this difference results from isotope exchange between dissolved Pb supplied by anthropogenic aerosol deposition and adsorbed natural crustal Pb on weathered particles delivered to the ocean by coastal rivers...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035265/hydrothermal-impacts-on-trace-element-and-isotope-ocean-biogeochemistry
#18
C R German, K A Casciotti, J-C Dutay, L E Heimbürger, W J Jenkins, C I Measures, R A Mills, H Obata, R Schlitzer, A Tagliabue, D R Turner, H Whitby
Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035264/ocean-trace-element-cycles
#19
Gideon M Henderson
No abstract text is available yet for this article.
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/29035263/developing-a-test-bed-for-robust-research-governance-of-geoengineering-the-contribution-of-ocean-iron-biogeochemistry
#20
Philip W Boyd, Matthieu Bressac
Geoengineering to mitigate climate change has long been proposed, but remains nebulous. Exploration of the feasibility of geoengineering first requires the development of research governance to move beyond the conceptual towards scientifically designed pilot studies. Fortuitously, 12 mesoscale (approx. 1000 km(2)) iron enrichments, funded to investigate how ocean iron biogeochemistry altered Earth's carbon cycle in the geological past, provide proxies to better understand the benefits and drawbacks of geoengineering...
November 28, 2016: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
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