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https://www.readbyqxmd.com/read/28228170/a-second-amorphous-layer-underneath-surface-oxide
#1
Bin Zhang, Kunlin Peng, Xuechao Sha, Ang Li, Xiaoyuan Zhou, Yanhui Chen, QingSong Deng, Dingfeng Yang, Evan Ma, Xiaodong Han
Formation of a nanometer-scale oxide surface layer is common when a material is exposed to oxygen-containing environment. Employing aberration-corrected analytical transmission electron microscopy and using single crystal SnSe as an example, we show that for an alloy, a second thin amorphous layer can appear underneath the outmost oxide layer. This inner amorphous layer is not oxide based, but instead originates from solid-state amorphization of the base alloy when its free energy rises to above that of the metastable amorphous state; which is a result of the composition shift due to the preferential depletion of the oxidizing species, in our case, the outgoing Sn reacting with the oxygen atmosphere...
February 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28227441/novel-ti-nb-alloys-with-improved-wear-resistance-for-biomedical-implant-application
#2
Praveen Chapala, Swati Ghosh Acharyya, S M Shariff, Ganesh Naik, Praveen Chapala, Swati Ghosh Acharyya, S M Shariff, Ganesh Naik, Ganesh Naik, S M Shariff, Praveen Chapala, Swati Ghosh Acharyya
The present study involved fabrication of titanium niobium based alloys having elastic modulus close to that of human bone and subsequently determining the wear resistance of these alloys for biomedical application. In the present study three beta stabilized titanium niobium alloys having composition Ti-24Nb-4Zr-8Sn, Ti-35Nb-4Sn and Ti-29Nb-13Ta-7Zr were made by vacuum arc melting. The alloys were then aged at 1000 C for 6 hours in an argon atmosphere. Detailed microstructural characterization and phase identification was carried out using scanning electron microscopy and x-ray diffraction respectively...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28218326/diffusive-confinement-of-free-radical-intermediates-in-the-oh-radical-oxidation-of-semisolid-aerosols
#3
Aaron A Wiegel, Matthew J Liu, William D Hinsberg, Kevin R Wilson, Frances A Houle
Multiphase chemical reactions (gas + solid/liquid) involve a complex interplay between bulk and interface chemistry, diffusion, evaporation, and condensation. Reactions of atmospheric aerosols are an important example of this type of chemistry: the rich array of particle phase states and multiphase transformation pathways produce diverse but poorly understood interactions between chemistry and transport. Their chemistry is of intrinsic interest because of their role in controlling climate. Their characteristics also make them useful models for the study of principles of reactivity of condensed materials under confined conditions...
February 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28218253/environmental-conditions-regulate-the-impact-of-plants-on-cloud-formation
#4
D F Zhao, A Buchholz, R Tillmann, E Kleist, C Wu, F Rubach, A Kiendler-Scharr, Y Rudich, J Wildt, Th F Mentel
The terrestrial vegetation emits large amounts of volatile organic compounds (VOC) into the atmosphere, which on oxidation produce secondary organic aerosol (SOA). By acting as cloud condensation nuclei (CCN), SOA influences cloud formation and climate. In a warming climate, changes in environmental factors can cause stresses to plants, inducing changes of the emitted VOC. These can modify particle size and composition. Here we report how induced emissions eventually affect CCN activity of SOA, a key parameter in cloud formation...
February 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28217121/seasonal-variation-in-abundance-and-diversity-of-bacterial-methanotrophs-in-five-temperate-lakes
#5
Md Sainur Samad, Stefan Bertilsson
Lakes are significant sources of methane (CH4) to the atmosphere. Within these systems, methanotrophs consume CH4 and act as a potential biofilter mitigating the emission of this potent greenhouse gas. However, it is still not well understood how spatial and temporal variation in environmental parameters influence the abundance, diversity, and community structure of methanotrophs in lakes. To address this gap in knowledge, we collected water samples from three depths (surface, middle, and bottom) representing oxic to suboxic or anoxic zones of five different Swedish lakes in winter (ice-covered) and summer...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28214009/trophic-magnification-of-dechlorane-plus-in-the-marine-food-webs-of-fildes-peninsula-in-antarctica
#6
Guangshui Na, Yao Yao, Hui Gao, Ruijing Li, Linke Ge, Ivan A Titaley, Lisandra Santiago-Delgado, Staci L Massey Simonich
The food web composition, assimilation efficiency of Dechlorane Plus (DP) in food web components, and even extrinsic conditions can affect the trophic biomagnification potentials of DP isomers in food webs. Antarctica ecological system is characterized by the presence of few consumers and simple trophic levels (TLs), which are crucial in discussing the behavior of contaminants. To assess the biomagnification potential of DP in the Antarctic food web, nine representative species were sampled and analyzed from the Fildes Peninsula...
February 14, 2017: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/28203457/effect-of-strontium-on-nd-doped-ba1-x-sr-x-ce0-65zr0-25nd0-1o3-%C3%AE-proton-conductor-as-an-electrolyte-for-solid-oxide-fuel-cells
#7
J Madhuri Sailaja, K Vijaya Babu, N Murali, V Veeraiah
This paper investigated the Sr doping effect on the microstructure, chemical stability, and conductivity of Ba1-x Sr x Ce0.65Zr0.25Nd0.1O3-δ (0 ⩽ x ⩽ 0.2) electrolyte prepared by sol-gel method. The lattice constants and unit cell volumes were found to decrease as Sr atomic percentage increased in accordance with the Vegard law, confirming the formation of solid solution. Incorporation of Sr into the composition resulted in smaller grains besides suppressing the formation of secondary phases of SrCeO3...
May 2017: Journal of Advanced Research
https://www.readbyqxmd.com/read/28197606/the-properties-and-behavior-of-%C3%AE-pinene-secondary-organic-aerosol-particles-exposed-to-ammonia-under-dry-conditions
#8
David M Bell, Dan Imre, Scot T Martin, Alla Zelenyuk
Chemical transformations and aging of secondary organic aerosol (SOA) particles can alter their physical and chemical properties, including particle morphology. Ammonia, one of the common atmospheric reactive constituents, can react with SOA particles, changing their properties and behavior. At low relative humidity, NH3 uptake by α-pinene SOA particles appears to be limited to the particle surface, which suggests that the reacted particles might not be homogeneous and have complex morphology. Here, we present a study aimed at detailed characterization of the effect of ammonia on the composition, density, morphology, shape, and evaporation kinetics of α-pinene SOA particles...
February 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28195722/effects-of-relative-humidity-and-particle-phase-water-on-the-heterogeneous-oh-oxidation-of-2-methylglutaric-acid-aqueous-droplets
#9
Man Mei Chim, Chun Yin Chow, James F Davies, ManNin Chan
Organic aerosols can exist as aqueous droplets, with variable water content depending on their composition and environmental conditions (e.g. relative humidity (RH)). Recent laboratory studies have revealed that oxidation kinetics in highly concentrated droplets can be much slower from those in dilute solutions. However, it remains unclear whether particle phase water affects the formation of reaction products physically and/or chemically. In this work, we investigate the role of particle phase water on the heterogeneous chemistry of aqueous organic droplets consisting of 2-methylglutaric acid (2-MGA), measuring the reaction kinetics and the reaction products upon heterogeneous OH oxidation over a range of RH...
February 14, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28194455/structural-and-elemental-influence-from-various-mofs-on-the-performance-of-fe-c-catalysts-for-fischer-tropsch-synthesis
#10
Tim A Wezendonk, Quirinus S E Warringa, Vera P Santos, Adam Chojecki, Matthijs Ruitenbeek, Garry Meima, Michiel Makkee, Freek Kapteijn, Jorge Gascon
The structure and elementary composition of various commercial Fe-based MOFs used as precursors for Fischer-Tropsch synthesis (FTS) catalysts have a large influence on the high-temperature FTS activity and selectivity of the resulting Fe on carbon composites. The selected Fe-MOF topologies (MIL-68, MIL-88A, MIL-100, MIL-101, MIL-127, and Fe-BTC) differ from each other in terms of porosity, surface area, Fe and heteroatom content, crystal density and thermal stability. They are re-engineered towards FTS catalysts by means of simple pyrolysis at 500 °C under a N2 atmosphere and afterwards characterized in terms of porosity, crystallite phase, bulk and surface Fe content, Fe nanoparticle size and oxidation state...
February 14, 2017: Faraday Discussions
https://www.readbyqxmd.com/read/28193064/vapor-pressure-isotope-effects-in-halogenated-organic-compounds-and-alcohols-dissolved-in-water
#11
Axel Horst, Georges Lacrampe-Couloume, Barbara Sherwood Lollar
Volatilization causes changes in the isotopic composition of organic compounds as a result of different vapor pressures of molecules containing heavy and light isotopes. Both normal and inverse vapor pressure isotope effects (VPIE) have been observed, depending on molecular interactions in the liquid phase and the investigated element. Previous studies have focused mostly on pure compound volatilization or on compounds dissolved in organic liquids. Environmentally relevant scenarios, such as isotope fractionation during volatilization of organics from open water surfaces, have largely been neglected...
December 20, 2016: Analytical Chemistry
https://www.readbyqxmd.com/read/28192926/mass-spectrometry-characterization-of-peroxycarboxylic-acids-as-proxies-for-reactive-oxygen-species-and-highly-oxygenated-molecules-in-atmospheric-aerosols
#12
Sarah S Steimer, Ivan Kourtchev, Markus Kalberer
A significant fraction of atmospheric aerosol particles is composed of organic material with a highly complex but poorly characterized composition. For a better understanding of aerosol effects and processes in the atmosphere, a more detailed knowledge of aerosol components at a molecular level is needed. Peroxy acids might play a significant role in particle toxicity, due to their oxidizing properties, and they were recently found to be involved in particle formation. Because of the lack of appropriate standards, the identification and quantification of peroxy acids is often highly uncertain...
February 10, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28188868/gene-sequence-variations-and-expression-patterns-of-mitochondrial-genes-are-associated-with-the-adaptive-evolution-of-two-gynaephora-species-lepidoptera-lymantriinae-living-in-different-high-elevation-environments
#13
Qi-Lin Zhang, Li Zhang, Tian-Xuan Zhao, Juan Wang, Qian-Hua Zhu, Jun-Yuan Chen, Ming-Long Yuan
The adaptive evolution of animals to high-elevation environments has been extensively studied in vertebrates, while few studies have focused on insects. Gynaephora species (Lepidoptera: Lymantriinae) are endemic to the Qinghai-Tibetan Plateau (QTP) and represent an important insect pest of alpine meadows. Here, we present a detailed comparative analysis of the mitochondrial genomes (mitogenomes) of two Gynaephora species inhabiting different high-elevation environments: G. alpherakii and G. menyuanensis. The results indicated that the general mitogenomic features (genome size, nucleotide composition, codon usage and secondary structures of tRNAs) were well conserved between the two species...
February 7, 2017: Gene
https://www.readbyqxmd.com/read/28186521/diverging-effects-of-isotopic-fractionation-upon-molecular-diffusion-of-noble-gases-in-water-mechanistic-insights-through-ab-initio-molecular-dynamics-simulations
#14
Halua Pinto de Magalhães, Matthias S Brennwald, Rolf Kipfer
Atmospheric noble gases are routinely used as natural tracers to analyze gas transfer processes in aquatic systems. Their isotopic ratios can be employed to discriminate between different physical transport mechanisms by comparison to the unfractionated atmospheric isotope composition. In many applications of aquatic systems molecular diffusion was thought to cause a mass dependent fractionation of noble gases and their isotopes according to the square root ratio of their masses. However, recent experiments focusing on isotopic fractionation within a single element challenged this broadly accepted assumption...
February 10, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28182638/effect-of-elevated-atmospheric-co2-concentration-on-growth-and-leaf-litter-decomposition-of-quercus-acutissima-and-fraxinus-rhynchophylla
#15
Sangsub Cha, Hee-Myung Chae, Sang-Hoon Lee, Jae-Kuk Shim
The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions...
2017: PloS One
https://www.readbyqxmd.com/read/28168799/nanostructured-materials-for-heterogeneous-electrocatalytic-co2-reduction-and-related-reaction-mechanisms
#16
Jinlong Gong, Lei Zhang, Zhi-Jian Zhao
The gradually increased concentration of carbon dioxide (CO2) in the atmosphere has been recognized as the primary culprit for the raise of the global mean temperature, thus resulting in the aggravated desert formation and extinction of species. In recent years, development of the routes for highly efficient conversion of CO2 has received numerous attentions. Among them, the reduction of CO2 with electric power is an important transformation route with high application prospect, due to its high environmental compatibility and good combination with other renewable energy sources such as solar and wind energy...
February 6, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28165773/greenhouse-gas-emissions-from-a-cu-contaminated-soil-remediated-by-in-situ-stabilization-and-phytomanaged-by-a-mixed-stand-of-poplar-willows-and-false-indigo-bush
#17
M Šimek, D Elhottová, M Mench, L Giagnoni, P Nannipieri, G Renella
Phytomanagement of trace element-contaminated soils can reduce the soil toxicity and restore the soil ecological functions, including the soil gas exchange with the atmosphere. We studied the emission rate of the greenhouse gases (GHG) CO2, CH4 and N2O, and the potential CH4 oxidation, denitrification activity (DEA) and glucose mineralization of a Cu-contaminated soil amended with dolomitic limestone and compost, alone or in combination, after a 2 year-phytomanagement with a mixed stand of Populus nigra, Salix viminalis, S...
February 6, 2017: International Journal of Phytoremediation
https://www.readbyqxmd.com/read/28165715/electrospinning-of-fe-sic-hybrid-fibers-for-highly-efficient-microwave-absorption
#18
Yi Hou, Laifei Cheng, Yani Zhang, Yong Yang, Chaoran Deng, Zhihong Yang, Qi Chen, Peng Wang, Lianxi Zheng
Fe/SiC hybrid fibers have been fabricated by electrospinning and subsequent high-temperature (1300 °C) pyrolysis in Ar atmosphere using polycarbosilane (PCS) and Fe3O4 precursors. It is found that the introduction of Fe has had a dramatic impact on the morphology, crystallization temperature, and microwave electromagnetic properties of the hybrid fibers. In addition, the Fe particles have acted as catalyst sites to facilitate the growth of SiCO nanowires on the surface of the hybrid fibers. As a result, the permittivity and permeability have been enhanced effectively, and the high reflection loss (RL) has been achieved at a low frequency band with a thin absorber thickness...
February 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28165040/lead-free-piezoelectrics-v-3-to-v-5-ion-conversion-promoting-the-performances-of-v-doped-zinc-oxide
#19
M Laurenti, M Castellino, D Perrone, A Asvarov, G Canavese, A Chiolerio
Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn(2+) with V(3+) and V(5+) ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion...
February 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28165021/black-tio2-nanobelts-g-c3n4-nanosheets-laminated-heterojunctions-with-efficient-visible-light-driven-photocatalytic-performance
#20
Liyan Shen, Zipeng Xing, Jinlong Zou, Zhenzi Li, Xiaoyan Wu, Yuchi Zhang, Qi Zhu, Shilin Yang, Wei Zhou
Black TiO2 nanobelts/g-C3N4 nanosheets laminated heterojunctions (b-TiO2/g-C3N4) as visible-light-driven photocatalysts are fabricated through a simple hydrothermal-calcination process and an in-situ solid-state chemical reduction approach, followed by the mild thermal treatment (350 °C) in argon atmosphere. The prepared samples are evidently investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption, and UV-visible diffuse reflectance spectroscopy, respectively...
February 6, 2017: Scientific Reports
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