121 research outputs found
Plasma Vitamin E and Blood Selenium Concentrations in Norwegian Dairy Cows: Regional Differences and Relations to Feeding and Health
Plasma α-tocopherol (vit E) and blood selenium (Se) concentrations in February were determined in samples from 314 dairy cows in Norway, selected to provide a representative subset of the Norwegian dairy cow population. Each sample was followed by a questionnaire with information about feeding of the cow at the time of sampling. The results were correlated to herd data and to calving and health data for each cow from the Norwegian Dairy Herd Recording System and the Norwegian Cattle Health Recording System. The mean concentrations were 6.9 μg vit E per ml plasma and 0.16 μg Se per g blood. Both levels were highest in mid lactation. Plasma vit E varied with the amount of silage fed to the cow, while blood Se varied with the amount of concentrates and mineral supplements, and with geographical region. No differences in vit E or Se levels were found between cows with recorded treatments for mastitis, parturient paresis or reproductive disorders in the lactation during or immediately prior to sampling, and those without such treatments. For ketosis, a small difference in blood Se was found between the groups with or without recorded treatments. It is concluded that winter-fed lactating cows in Norway had an adequate plasma level of vit E and a marginal-to-adequate level of Se
Calculated phase diagrams, iron tolerance limits, and corrosion of Mg-Al alloys
The factors determining corrosion are reviewed in this paper, with an emphasis on iron tolerance limit and the production of high-purity castings. To understand the iron impurity tolerance limit, magnesium phase diagrams were calculated using the Pandat software package. Calculated phase diagrams can explain the iron tolerance limit and the production of high-purity castings by means of control of melt conditions; this is significant for the production of quality castings from recycled magnesium. Based on the new insight, the influence of the microstructure on corrosion of magnesium alloys is reviewed
Adherence measurements and corrosion resistance in primer/hot-dip galvanized steel systems
This paper focuses on the adherence during ageing of a primer (made of polyester resins crosslinked with melamine) applied onto hot-dip galvanized (HDG) steel for coil coating application and its influence on corrosion protection. A chromium-free surface treatment, composed of fluorotitanic acid, phosphoric acid, manganese phosphate, and vinylphenol was applied on the HDG steel to obtain high corrosion resistance and high adherence of a polyester and melamine primer. The influence of the manganese phosphate on the corrosion and adherence was investigated. To measure the adherence between the metal and the primer, a three-point flexure test was set up. The adherence was then linked with corrosion resistance during ageing, using electrochemical impedance spectroscopy
European emissions of the powerful greenhouse gases hydrofluorocarbons inferred from atmospheric measurements and their comparison with annual national reports to UNFCCC
Hydrofluorocarbons are powerful greenhouse gases developed by industry after the phase-out of the
ozone depleting chlorofluorocarbons and hydrochlorofluorocarbons required by the Montreal Protocol.
The climate benefit of reducing the emissions of hydrofluorocarbons has been widely recognised, leading
to an amendment of the Montreal Protocol (Kigali Amendment) calling for developed countries to start
to phase-down hydrofluorocarbons by 2019 and in developing countries to follow with a freeze between
2024 and 2028. In this way, nearly half a degree Celsius of warming would be avoided by the end of the
century. Hydrofluorocarbons are also included in the basket of gases controlled under the Kyoto Protocol
of the United Nations Framework Convention on Climate Change. Annex I parties to the Convention
submit annual national greenhouse gas inventories based on a bottom-up approach, which relies on
declared anthropogenic activities. Top-down methodologies, based on atmospheric measurements and
modelling, can be used in support to the inventory compilation. In this study we used atmospheric data
from four European sites combined with the FLEXPART dispersion model and a Bayesian inversion
method, in order to derive emissions of nine individual hydrofluorocarbons from the whole European
Geographic Domain and from twelve regions within it, then comparing our results with the annual
emissions that the European countries submit every year to the United Nations Framework Convention
on Climate Change, as well as with the bottom-up Emissions Database for Global Atmospheric Research.
We found several discrepancies when considering the specific compounds and on the country level.
However, an overall agreement is found when comparing European aggregated data, which between
2008 and 2014 are on average 84.2 ± 28.0 Tg-CO2-eqyr1 reported by UNFCCC in the same period. Therefore, in agreement with other studies, the gap on the global level
between bottom-up estimates of Annex I countries and total global top-down emissions should be
essentially due to emissions from non-reporting countries (non-Annex I)
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ACTRIS ACSM intercomparison - Part 2: Intercomparison of ME-2 organic source apportionment results from 15 individual, co-located aerosol mass spectrometers
Chemically resolved atmospheric aerosol data sets from the largest intercomparison of the Aerodyne aerosol chemical speciation monitors (ACSMs) performed to date were collected at the French atmospheric supersite SIRTA. In total 13 quadrupole ACSMs (Q-ACSM) from the European ACTRIS ACSM network, one time-of-flight ACSM (ToF-ACSM), and one high-resolution ToF aerosol mass spectrometer (AMS) were operated in parallel for about 3 weeks in November and December~2013. Part 1 of this study reports on the accuracy and precision of the instruments for all the measured species. In this work we report on the intercomparison of organic components and the results from factor analysis source apportionment by positive matrix factorisation (PMF) utilising the multilinear engine 2 (ME-2). Except for the organic contribution of mass-to-charge ratio m/z 44 to the total organics (f44), which varied by factors between 0.6 and 1.3 compared to the mean, the peaks in the organic mass spectra were similar among instruments. The m/z 44 differences in the spectra resulted in a variable f44 in the source profiles extracted by ME-2, but had only a minor influence on the extracted mass contributions of the sources. The presented source apportionment yielded four factors for all 15 instruments: hydrocarbon-like organic aerosol (HOA), cooking-related organic aerosol (COA), biomass burning-related organic aerosol (BBOA) and secondary oxygenated organic aerosol (OOA). ME-2 boundary conditions (profile constraints) were optimised individually by means of correlation to external data in order to achieve equivalent / comparable solutions for all ACSM instruments and the results are discussed together with the investigation of the influence of alternative anchors (reference profiles). A comparison of the ME-2 source apportionment output of all 15 instruments resulted in relative standard deviations (SD) from the mean between 13.7 and 22.7 % of the source's average mass contribution depending on the factors (HOA: 14.3 ± 2.2 %, COA: 15.0 ± 3.4 %, OOA: 41.5 ± 5.7 %, BBOA: 29.3 ± 5.0 %). Factors which tend to be subject to minor factor mixing (in this case COA) have higher relative uncertainties than factors which are recognised more readily like the OOA. Averaged over all factors and instruments the relative first SD from the mean of a source extracted with ME-2 was 17.2 %
History of chemically and radiatively important atmospheric gases from the Advanced Global Atmospheric Gases Experiment (AGAGE)
We present the organization, instrumentation, datasets, data interpretation,
modeling, and accomplishments of the multinational global atmospheric
measurement program AGAGE (Advanced Global Atmospheric Gases Experiment).
AGAGE is distinguished by its capability to measure globally, at high
frequency, and at multiple sites all the important species in the Montreal
Protocol and all the important non-carbon-dioxide (non-CO<sub>2</sub>) gases
assessed by the Intergovernmental Panel on Climate Change (CO<sub>2</sub> is
also measured at several sites). The scientific objectives of AGAGE are
important in furthering our understanding of global chemical and climatic
phenomena. They are the following: (1) to accurately measure the temporal and
spatial distributions of anthropogenic gases that contribute the majority of
reactive halogen to the stratosphere and/or are strong infrared absorbers
(chlorocarbons, chlorofluorocarbons – CFCs, bromocarbons,
hydrochlorofluorocarbons – HCFCs, hydrofluorocarbons – HFCs and
polyfluorinated compounds (perfluorocarbons – PFCs), nitrogen trifluoride –
NF<sub>3</sub>, sulfuryl fluoride – SO<sub>2</sub>F<sub>2</sub>, and sulfur hexafluoride –
SF<sub>6</sub>) and use these measurements to determine the global rates of
their emission and/or destruction (i.e., lifetimes); (2) to accurately
measure the global distributions and temporal behaviors and determine the
sources and sinks of non-CO<sub>2</sub> biogenic–anthropogenic gases important
to climate change and/or ozone depletion (methane – CH<sub>4</sub>, nitrous
oxide – N<sub>2</sub>O,
carbon monoxide – CO, molecular hydrogen – H<sub>2</sub>, methyl chloride
– CH<sub>3</sub>Cl, and methyl bromide – CH<sub>3</sub>Br); (3) to identify new
long-lived greenhouse and ozone-depleting gases (e.g., SO<sub>2</sub>F<sub>2</sub>,
NF<sub>3</sub>, heavy PFCs (C<sub>4</sub>F<sub>10</sub>, C<sub>5</sub>F<sub>12</sub>,
C<sub>6</sub>F<sub>14</sub>, C<sub>7</sub>F<sub>16</sub>, and C<sub>8</sub>F<sub>18</sub>) and
hydrofluoroolefins (HFOs; e.g., CH<sub>2</sub> = CFCF<sub>3</sub>) have been
identified in AGAGE), initiate the real-time monitoring of these new gases,
and reconstruct their past histories from AGAGE, air archive, and firn air
measurements; (4) to determine the average concentrations and trends of
tropospheric hydroxyl radicals (OH) from the rates of destruction of
atmospheric trichloroethane (CH<sub>3</sub>CCl<sub>3</sub>), HFCs, and HCFCs and estimates
of their emissions; (5) to determine from atmospheric observations and
estimates of their destruction rates the magnitudes and distributions by
region of surface sources and sinks of all measured gases; (6) to provide
accurate data on the global accumulation of many of these trace gases that
are used to test the synoptic-, regional-, and global-scale circulations
predicted by three-dimensional models; and (7) to provide global and regional
measurements of methane, carbon monoxide, and molecular hydrogen and
estimates of hydroxyl levels to test primary atmospheric oxidation pathways
at midlatitudes and the tropics. Network Information and Data Repository:
<a href="http://agage.mit.edu/data" target="_blank">http://agage.mit.edu/data</a> or
<a href="http://cdiac.ess-dive.lbl.gov/ndps/alegage.html" target="_blank">http://cdiac.ess-dive.lbl.gov/ndps/alegage.html</a>
(<a href="https://doi.org/10.3334/CDIAC/atg.db1001" target="_blank">https://doi.org/10.3334/CDIAC/atg.db1001</a>)
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A European aerosol phenomenology - 7: High-time resolution chemical characteristics of submicron particulate matter across Europe
Similarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62°N and 10° W – 26°E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and following common measurement guidelines. Data regarding organics, sulfate, nitrate and ammonium concentrations, as well as the sum of them called non-refractory submicron aerosol mass concentration ([NR-PM1]) are discussed. NR-PM1 concentrations generally increase from remote to urban sites. They are mostly larger in the mid-latitude band than in southern and northern Europe. On average, organics account for the major part (36–64%) of NR-PM1 followed by sulfate (12–44%) and nitrate (6–35%). The annual mean chemical composition of NR-PM1 at rural (or regional background) sites and urban background sites are very similar. Considering rural and regional background sites only, nitrate contribution is higher and sulfate contribution is lower in mid-latitude Europe compared to northern and southern Europe. Large seasonal variations in concentrations (μg/m³) of one or more components of NR-PM1 can be observed at all sites, as well as in the chemical composition of NR-PM1 (%) at most sites. Significant diel cycles in the contribution to [NR-PM1] of organics, sulfate, and nitrate can be observed at a majority of sites both in winter and summer. Early morning minima in organics in concomitance with maxima in nitrate are common features at regional and urban background sites. Daily variations are much smaller at a number of coastal and rural sites. Looking at NR-PM1 chemical composition as a function of NR-PM1 mass concentration reveals that although organics account for the major fraction of NR-PM1 at all concentration levels at most sites, nitrate contribution generally increases with NR-PM1 mass concentration and predominates when NR-PM1 mass concentrations exceed 40 μg/m³ at half of the sites. © 2021 The Author
A European aerosol phenomenology - 7 : High-time resolution chemical characteristics of submicron particulate matter across Europe
Similarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62 degrees N and 10 degrees W - 26 degrees E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and following common measurement guidelines. Data regarding organics, sulfate, nitrate and ammonium concentrations, as well as the sum of them called non-refractory submicron aerosol mass concentration ([NR-PM1]) are discussed. NR-PM1 concentrations generally increase from remote to urban sites. They are mostly larger in the mid-latitude band than in southern and northern Europe. On average, organics account for the major part (36-64%) of NR-PM1 followed by sulfate (12-44%) and nitrate (6-35%). The annual mean chemical composition of NR-PM1 at rural (or regional background) sites and urban background sites are very similar. Considering rural and regional background sites only, nitrate contribution is higher and sulfate contribution is lower in midlatitude Europe compared to northern and southern Europe. Large seasonal variations in concentrations (mu g/m(3)) of one or more components of NR-PM1 can be observed at all sites, as well as in the chemical composition of NR-PM1 (%) at most sites. Significant diel cycles in the contribution to [NR-PM1] of organics, sulfate, and nitrate can be observed at a majority of sites both in winter and summer. Early morning minima in organics in concomitance with maxima in nitrate are common features at regional and urban background sites. Daily variations are much smaller at a number of coastal and rural sites. Looking at NR-PM1 chemical composition as a function of NR-PM1 mass concentration reveals that although organics account for the major fraction of NR-PM1 at all concentration levels at most sites, nitrate contribution generally increases with NR-PM1 mass concentration and predominates when NR-PM1 mass concentrations exceed 40 mu g/m(3) at half of the sites.Peer reviewe
Acute effects of orexigenic antipsychotic drugs on lipid and carbohydrate metabolism in rat
This study aims to investigate whether orexigenic antipsychotic drugs may induce dyslipidemia and glucose disturbances in female rats through direct perturbation of metabolically active peripheral tissues, independent of prior weight gain. Methods In the current study, we examined whether a single intraperitoneal injection of clozapine or olanzapine induced metabolic disturbances in adult female outbred Sprague–Dawley rats. Serum glucose and lipid parameters were measured during time-course experiments up to 48 h. Real-time quantitative PCR was used to measure specific transcriptional alterations in lipid and carbohydrate metabolism in adipose tissue depots or in the liver. Results Our results demonstrated that acute administration of clozapine or olanzapine induced a rapid, robust elevation of free fatty acids and glucose in serum, followed by hepatic accumulation of lipids evident after 12–24 h. These metabolic disturbances were associated with biphasic patterns of gluconeogenic and lipid-related gene expression in the liver and in white adipose tissue depots. Conclusion Our results support that clozapine and olanzapine are associated with primary effects on carbohydrate and lipid metabolism associated with transcriptional changes in metabolically active peripheral tissues prior to the development of drug-induced weight gain
Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH3CHF2) from in situ and air archive observations
High frequency, in situ observations from 11 globally distributed sites for the period 1994–2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2). These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a top-down approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an annual average rate of growth in 2013–2014 of −0.06 ± 0.05 ppt yr−1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called “bottom up” emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate ( > 20 Gg) of “bottom-up” reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions
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