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https://www.readbyqxmd.com/read/29332796/direct-olive-oil-analysis-by-mass-spectrometry-a-comparison-of-different-ambient-ionization-methods
#1
Felipe J Lara-Ortega, Miriam Beneito-Cambra, José Robles-Molina, Juan F García-Reyes, Bienvenida Gilbert-López, Antonio Molina-Díaz
Analytical methods based on ambient ionization mass spectrometry (AIMS) combine the classic outstanding performance of mass spectrometry in terms of sensitivity and selectivity along with convenient features related to the lack of sample workup required. In this work, the performance of different mass spectrometry-based methods has been assessed for the direct analyses of virgin olive oil for quality purposes. Two sets of experiments have been setup: (1) direct analysis of untreated olive oil using AIMS methods such as Low-Temperature Plasma Mass Spectrometry (LTP-MS) or paper spray mass spectrometry (PS-MS); or alternatively (2) the use of atmospheric pressure ionization (API) mass spectrometry by direct infusion of a diluted sample through either atmospheric pressure chemical ionization (APCI) or electrospray (ESI) ionization sources...
April 1, 2018: Talanta
https://www.readbyqxmd.com/read/29330495/large-unexplained-suite-of-chemically-reactive-compounds-present-in-ambient-air-due-to-biomass-fires
#2
V Kumar, B P Chandra, V Sinha
Biomass fires impact global atmospheric chemistry. The reactive compounds emitted and formed due to biomass fires drive ozone and organic aerosol formation, affecting both air quality and climate. Direct hydroxyl (OH) Reactivity measurements quantify total gaseous reactive pollutant loadings and comparison with measured compounds yields the fraction of unmeasured compounds. Here, we quantified the magnitude and composition of total OH reactivity in the north-west Indo-Gangetic Plain. More than 120% increase occurred in total OH reactivity (28 s-1 to 64 s-1) and from no missing OH reactivity in the normal summertime air, the missing OH reactivity fraction increased to ~40 % in the post-harvest summertime period influenced by large scale biomass fires highlighting presence of unmeasured compounds...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29322769/composition-microstructure-and-electrical-performances-of-sputtered-sno-thin-film-for-p-type-oxide-semiconductor
#3
Seung Jun Lee, Yoon Jin Jang, Han Joon Kim, Eun Suk Hwang, Seok Min Jeon, Jun Shik Kim, Taehwan Moon, Kyung-Tae Jang, Young-Chang Joo, Deok-Yong Cho, Cheol Seong Hwang
P-Type SnO thin films were deposited on Si substrate by a co-sputtering process using ce-ramic SnO and metal Sn targets at room temperature without adding oxygen. By varying the DC sputtering power applied to the Sn target while maintaining the RF power to the SnO target constant, the Sn:O ratio could vary from 56:44 to 74:26 at the as-deposited state. After the thermal annealing at 180 oC for 25 min under air atmosphere using a microwave annealing system, the films were crystallized into the tetragonal SnO while the Sn:O ratio became from 44:56 to 57:43...
January 11, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29321679/responses-of-intrinsic-water-use-efficiency-and-tree-growth-to-climate-change-in-semi-arid-areas-of-north-china
#4
L U Weiwei, Y U Xinxiao, J I A Guodong, L I Hanzhi, L I U Ziqiang
Tree-level intrinsic water-use efficiency (iWUE) is derived from the tree-ring 13C isotope composition (δ13C) and is an important indicator of the adaptability for trees to climate change. However, there is still uncertainty regarding the relationship between long-term forest ecosystem carbon sequestration capacity and iWUE. To determine whether elevated atmospheric CO2 concentration (Ca) increase iWUE and tree growth (basal area increment, BAI), dendrochronological methods and stable isotope analyses were used to examine annual changes in the tree-ring width and carbon isotope composition (δ13C) of Platycladus orientalis in northern China...
January 10, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29314468/a-mineralogical-record-of-ocean-change-decadal-and-centennial-patterns-in-the-california-mussel
#5
Sophie J McCoy, Nicholas A Kamenos, Peter Chung, Timothy J Wootton, Catherine A Pfister
Ocean acidification, a product of increasing atmospheric carbon dioxide, may already have affected calcified organisms in the coastal zone, such as bivalves and other shellfish. Understanding species' responses to climate change requires the context of long-term dynamics. This can be particularly difficult given the longevity of many important species in contrast with the relatively rapid onset of environmental changes. Here, we present a unique archival dataset of mussel shells from a locale with recent environmental monitoring and historical climate reconstructions...
January 4, 2018: Global Change Biology
https://www.readbyqxmd.com/read/29313661/metallic-intermediate-phase-inducing-morphological-transformation-in-thermal-nitridation-ni3fen-based-3d-hierarchical-electrocatalyst-for-water-splitting
#6
Zhihe Liu, Hua Tan, Jianping Xin, Jiazhi Duan, Xiaowen Su, Pin Hao, Junfeng Xie, Jie Zhan, Jing Zhang, Jian-Jun Wang, Hong Liu
Transition metal nitrides have attracted a great deal of interest as electrocatalysts for water splitting due to their super metallic performance, high efficiency and good stability. Herein, we report a novel design of hierarchical electrocatalyst based on Ni3FeN, where the presence of carbon fiber cloth as scaffold can effectively alleviate the aggregation of Ni3FeN nanostructure and form 3D conducting networks to enlarge the surface area and simultaneously enhance the charge transfer. The composition and morphological variations of NiFe-precursors during annealing in different atmosphere were investigated...
January 9, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29306164/long-term-observations-of-the-background-aerosol-at-cabauw-the-netherlands
#7
D Mamali, J Mikkilä, B Henzing, R Spoor, M Ehn, T Petäjä, H Russchenberg, G Biskos
Long-term measurements of PM2.5 mass concentrations and aerosol particle size distributions from 2008 to 2015, as well as hygroscopicity measurements conducted over one year (2008-2009) at Cabauw, The Netherlands, are compiled here in order to provide a comprehensive dataset for understanding the trends and annual variabilities of the atmospheric aerosol in the region. PM2.5 concentrations have a mean value of 14.4μgm-3 with standard deviation 2.1μgm-3, and exhibit an overall decreasing trend of -0.74μgm-3year-1...
January 3, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29297964/elevated-co2-induces-substantial-and-persistent-declines-in-forage-quality-irrespective-of-warming-in-mixedgrass-prairie
#8
David J Augustine, Dana M Blumenthal, Tim L Springer, Daniel R LeCain, Stacey A Gunter, Justin D Derner
Increasing atmospheric [CO2 ] and temperature are expected to affect the productivity, species composition, biogeochemistry, and therefore the quantity and quality of forage available to herbivores in rangeland ecosystems. Both elevated CO2 (eCO2 ) and warming affect plant tissue chemistry through multiple direct and indirect pathways, such that the cumulative outcomes of these effects are difficult to predict. Here, we report on a 7-year study examining effects of CO2 enrichment (to 600 ppm) and infrared warming (+1...
January 3, 2018: Ecological Applications: a Publication of the Ecological Society of America
https://www.readbyqxmd.com/read/29297910/effects-of-salinity-on-the-adsorption-of-nucleotides-onto-phyllosilicates
#9
Ulysse Pedreira-Segade, Laurent J Michot, Isabelle Daniel
In the context of the origin of life, phyllosilicate surfaces might favor the adsorption, concentration and reactivity of otherwise diluted prebiotic molecules. The primitive oceanic seafloor was certainly rich in Fe-Mg-rich phyllosilicates. The salinity of the primitive seawater remains largely unknown. Values ranging from 1 to 15 times modern salinity have been proposed and the salt composition of the primitive ocean also remains elusive although it may have played a role in the interactions between nucleotides and mineral surfaces...
January 3, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29288063/the-immune-related-fatty-acids-are-responsive-to-co2-driven-seawater-acidification-in-a-crustacean-brine-shrimp-artemia-sinica
#10
Yan Gao, Shu-Cheng Zheng, Chao-Qun Zheng, Yue-Chen Shi, Xiao-Lu Xie, Ke-Jian Wang, Hai-Peng Liu
The gradual increase of CO2 concentration in the atmosphere, absorbed by the ocean surface water through air to sea equilibration termed ocean acidification (OA), leads to the decline of pH in seawater. It is not clear so far how the composition of fatty acids, particular the immune-related, in marine crustacean and the subsequent energy supply in marine ecosystem are affected by OA. The brine shrimp Artemia sinica is an open and common feed that provide essential fatty acids for mariculture. In this study, the fatty acids profiles of brine shrimp cultured under different lower pH levels of CO2 driven seawater were investigated...
December 26, 2017: Developmental and Comparative Immunology
https://www.readbyqxmd.com/read/29284089/natural-silicon-isotopic-signatures-reveal-the-sources-of-airborne-fine-particulate-matter
#11
Dawei Lu, Qian Liu, Miao Yu, Xuezhi Yang, Qiang Fu, Xiaoshan Zhang, Yujing Mu, Guibin Jiang
Airborne particulate pollution is a critical environmental problem affecting human health and sustainable development. Understanding of the sources of aerosol particles is of extreme importance for regional air pollution control. Here we show that natural Si isotopic signature can be used as a new tool to elucidate the sources of fine particulate matter (PM2.5). Through the analysis of Si isotopic composition (δ30Si) of PM2.5 and its primary sources collected in a typical pollution region-Beijing, we recognized the direct source tracing ability of Si isotopes for PM2...
December 28, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29282824/flowering-in-grassland-predicted-by-co2-and-resource-effects-on-species-aboveground-biomass
#12
Philip A Fay, Michael J Aspinwall, Harold P Collins, Anne E Gibson, Richard H Gill, Robert B Jackson, Virginia L Jin, Albina R Khasanova, Lara G Reichmann, H Wayne Polley
Continuing enrichment of atmospheric CO2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for ten years in C4 dominated grassland communities on contrasting soils along a CO2 concentration gradient spanning pre-industrial to expected mid-21st century levels (250 - 500 μL L-1 )...
December 28, 2017: Global Change Biology
https://www.readbyqxmd.com/read/29279668/x-ray-diffraction-analysis-of-hydroxyapatite-coated-in-different-plasma-gas-atmosphere-on-ti-and-ti-6al-4v
#13
Ravindra Kotian, P Prasad Rao, Prashanthi Madhyastha
Objective: The aim is to study the effect of plasma working gas on composition, crystallinity, and microstructure of hydroxyapatite (HA) coated on Ti and Ti-6Al-4V metal substrates. Materials and Methods: Ti and Ti-6Al-4V metal substrates were coated with HA by plasma spray using four plasma gas atmospheres of argon, argon/hydrogen, nitrogen, and nitrogen/hydrogen. The degree of crystallinity, the phases present, and microstructure of HA coating were characterized using X-ray diffraction and scanning electron microscopy...
October 2017: European Journal of Dentistry
https://www.readbyqxmd.com/read/29277946/discrimination-of-constructed-air-samples-using-multivariate-analysis-of-full-scan-membrane-introduction-mass-spectrometry-mims-data
#14
L C Richards, N G Davey, T M Fyles, C G Gill, E T Krogh
RATIONALE: Volatile and semi-volatile organic compounds (S/VOCs) are important atmospheric pollutants affecting both human and environmental health. They are directly measured as an unresolved mixture using membrane introduction mass spectrometry (MIMS). We apply chemometric techniques to discriminate, classify, and apportion air samples from a variety of sources. METHODS: Full scan mass spectra of lab constructed air samples were obtained using a polydimethylsiloxane membrane interface and an electron ionization ion trap mass spectrometer...
December 26, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29248703/sequential-samples-reveal-significant-variation-of-mercury-isotope-ratios-during-single-rainfall-events
#15
Shengliu Yuan, Jiubin Chen, Hongming Cai, Wei Yuan, Zhongwei Wang, Qiang Huang, Yujie Liu, Xingyang Wu
Although the investigation of mercury (Hg) isotopes in precipitation has largely improved our knowledge of the source and transformation of Hg in the atmosphere, rainwater investigated in previous studies were integrated samples collected over an event and could obscure key information about the physiochemical transformation and deposition dynamics of Hg (and its isotopes) in short precipitation events. In this study, we investigated Hg isotopic composition of filtered (HgF) and particulate Hg (HgPM) in sequential rain samples from three single rainfall events in Guiyang, China...
December 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29246075/perspective-aerosol-microphysics-from-molecules-to-the-chemical-physics-of-aerosols
#16
Bryan R Bzdek, Jonathan P Reid
Aerosols are found in a wide diversity of contexts and applications, including the atmosphere, pharmaceutics, and industry. Aerosols are dispersions of particles in a gas, and the coupling of the two phases results in highly dynamic systems where chemical and physical properties like size, composition, phase, and refractive index change rapidly in response to environmental perturbations. Aerosol particles span a wide range of sizes from 1 nm to tens of micrometres or from small molecular clusters that may more closely resemble gas phase molecules to large particles that can have similar qualities to bulk materials...
December 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/29244949/growth-kinetics-and-size-distribution-dynamics-of-viscous-secondary-organic-aerosol
#17
Rahul A Zaveri, John E Shilling, Alla Zelenyuk, Jiumeng Liu, David M Bell, Emma L D'Ambro, Cassandra J Gaston, Joel A Thornton, Alexander Laskin, Peng Lin, Jacqueline M Wilson, Richard C Easter, Jian Wang, Allan K Bertram, Scot T Martin, John H Seinfeld, Douglas R Worsnop
Low bulk diffusivity inside viscous semisolid atmospheric secondary organic aerosol (SOA) can prolong equilibration timescale, but its broader impacts on aerosol growth and size distribution dynamics are poorly understood. Here we present quantitative insights into the effects of bulk diffusivity on the growth and evaporation kinetics of SOA formed under dry conditions from photooxidation of isoprene in the presence of a bimodal aerosol consisting of Aitken (ammonium sulfate) and accumulation (isoprene or -pinene SOA) mode particles...
December 15, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29240968/monitoring-of-spoilage-associated-microbiota-on-modified-atmosphere-packaged-beef-and-differentiation-of-psychrophilic-and-psychrotrophic-strains
#18
Maik Hilgarth, Jürgen Behr, Rudi F Vogel
AIMS: This study aimed to explore the discriminatory power of MALDI-TOF MS as a high-throughput method to monitor growth dynamics of meat-spoiling bacteria on modified atmosphere packaged (MAP) beef and to differentiate psychrophilic and psychrotrophic spoilage-associated strains. METHODS AND RESULTS: MAP beef steaks were incubated for 21 days at constant 4 and 10 °C. Development of headspace gas composition, pH, CFU and spoilage-associated microbial composition were monitored...
December 14, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/29235455/atmospheric-pressure-mass-spectrometric-imaging-of-live-hippocampal-tissue-slices-with-subcellular-spatial-resolution
#19
Jae Young Kim, Eun Seok Seo, Hyunmin Kim, Ji-Won Park, Dong-Kwon Lim, Dae Won Moon
We report a high spatial resolution mass spectrometry (MS) system that allows us to image live hippocampal tissue slices under open-air atmospheric pressure (AP) and ambient temperature conditions at the subcellular level. The method is based on an efficient desorption process by femtosecond (fs) laser assisted with nanoparticles and a subsequent ionization step by applying nonthermal plasma, termed AP nanoparticle and plasma assisted laser desorption ionization (AP-nanoPALDI) MS method. Combining the AP-nanoPALDI with microscopic sample scanning, MS imaging with spatial resolution of 2...
December 13, 2017: Nature Communications
https://www.readbyqxmd.com/read/29233849/exogenous-malate-does-not-invert-the-reverse-sensitivity-of-isoprene-emission-to-high-co2
#20
Bahtijor Rasulov, Eero Talts, Irina Bichele, Ulo Niinemets
Isoprene is synthesized via chloroplastic 2-C-methyl-D-erythritol 4-phosphate/1-deoxy-D-xylulose 5-phosphate (MEP/DOXP) pathway and its synthesis is directly related to photosynthesis, except under high CO2 concentration when the rate of photosynthesis increases, but isoprene emission decreases. Suppression of MEP/DOXP pathway activity by high CO2 has been explained by limited supply of cytosolic substrate precursor, phosphoenolpyruvate (PEP) into chloroplast as the result of enhanced activity of PEP carboxylase (PEPC) or by limited supply of energetic and reductive equivalents...
December 12, 2017: Plant Physiology
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