Accurately accounting for new particle formation (NPF) is crucial to our ability to predict aerosol number concentrations in many environments and thus cloud properties, which is in turn vital in ...simulating radiative transfer and climate. Here we present an analysis of NPF events observed in the Greenland Sea during the summertime as part of the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. While NPF events have been reported in the Arctic before, we were able, for the first time, to detect iodine in the growing particles using an Aerosol Mass Spectrometer (AMS) during a persistent event in the region of the coastal sea-ice near Greenland. Given the potency of iodine as a nucleation precursor, the results imply that iodine was responsible for the initial NPF, a phenomenon that has been reported at lower latitudes and associated with molecular iodine emissions from coastal macroalgae. The initial source of iodine in this instance is not clear, but it was associated with air originating approximately 1 day previously over melting coastal sea-ice. These results show that atmospheric models must consider iodine as a source of new particles in addition to established precursors such as sulfur compounds.
Isoprene surface ocean concentrations and vertical distribution, atmospheric mixing ratios, and calculated sea‐to‐air fluxes spanning approximately 125° of latitude (80°N–45°S) over the Arctic and ...Atlantic Oceans are reported. Oceanic isoprene concentrations were associated with a number of concurrently monitored biological variables including chlorophyll a (Chl a), photoprotective pigments, integrated primary production (intPP), and cyanobacterial cell counts, with higher isoprene concentrations relative to all respective variables found at sea surface temperatures greater than 20°C. The correlation between isoprene and the sum of photoprotective carotenoids, which is reported here for the first time, was the most consistent across all cruises. Parameterizations based on linear regression analyses of these relationships perform well for Arctic and Atlantic data, producing a better fit to observations than an existing Chl a‐based parameterization. Global extrapolation of isoprene surface water concentrations using satellite‐derived Chl a and intPP reproduced general trends in the in situ data and absolute values within a factor of 2 between 60% and 85%, depending on the data set and algorithm used.
Key Points
Isoprene water concentrations correlated well with Chl a, primary production, photoprotective pigments, and cyanobacterial cell counts
Higher isoprene concentrations relative to all respective variables were found at sea surface temperatures greater than 20°C
Predicted isoprene water concentrations based on satellite Chl a compared well with observations
Highlights • Glibenclamide reduced brain edema by 15% 24 h after CCI injury in rats. • Glibenclamide diminished contusion volumes assessed by MRI imaging (8 h–7 d post CCI). • Glibenclamide-treated ...rats showed reduced number and duration of epileptic seizures. • Mikrodialyses showed a positive correlation between glutamate and epileptic seizures.
We provide new estimates of the air‐sea flux of CCl4 using simulations from a global ocean biogeochemistry model (NEMO‐PlankTOM) in combination with depth‐resolved CCl4 observations from global ...oceanic databases. Estimates of global oceanic CCl4 uptake are derived from a range of model analyses, including prescribed parameterizations using reported values on hydrolysis and degradation, and analyses optimized using the global observational databases. We evaluate the sensitivity of our results to uncertainties in air‐sea gas exchange parameterization, estimation period, and circulation processes. Our best constrained estimate of ocean CCl4 uptake for the period 1996–2000 is 20.1 Gg/year (range 16.6–22.7), corresponding to estimates of the partial atmospheric lifetime with respect to ocean uptake of 124 (110–150) years. This new oceanic lifetime implies higher emissions of CCl4 than currently estimated and therefore a larger missing atmospheric source of CCl4.
Plain Language Summary
Carbon tetrachloride (CCl4) is a trace gas emitted to the atmosphere during the industrial manufacture of refrigerants and solvents. CCl4 is also an ozone‐depleting agent affecting loss of the atmosphere's protective ozone layer, and CCl4 emissions are now controlled by the Montreal Protocol. However, recent analyses of observed atmospheric CCl4 concentration conclude that the current rate of atmospheric decline is slower than expected, and inconsistent with recent estimates of CCl4 emissions to and removal from the atmosphere. Estimated oceanic uptake of CCl4 has been noted as potentially the most uncertain of the atmospheric loss processes, and here we provide new quantification of this flux. Our methodology employs a novel approach and uses a global ocean biogeochemistry model which includes representation of known physical and biogeochemical processes influencing oceanic CCl4 uptake, together with a compiled global ocean database of CCl4 observations. The observational database is used to evaluate model simulations, and to derive optimized estimates of the oceanic uptake flux by minimizing the discrepancies between the model and observations. We also evaluate the sensitivity of our estimates of ocean CCl4 uptake to known uncertainties in the model representation of processes, including air‐sea gas transfer and oceanic chemical and biogeochemical loss. Our best constrained estimate of ocean CCl4 uptake for the 1996–2000 period is 20.1 Gg/year (range 16.6–22.7), which is greater than previous recent estimates, and implies a larger missing source to the atmosphere of CCl4.
Key Points
New estimate of ocean uptake of atmospheric CCl4 derived using an ocean biogeochemical model and global databases of CCl4 measurements
Best estimate of ocean CCl4 uptake is 20.1 Gg/year (16.6–22.7), with a corresponding partial atmospheric lifetime with respect to ocean uptake of 124 (110–150) years
Estimated ocean CCl4 uptake is larger than recent estimates and implies a larger missing source to the atmosphere
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► The production of well-characterised in-house reference material is described. ► Homogeneity and stability studies were carried out. ► The realisation of a proficiency test for ...steroids in bovine urine is described. ► Both GC–MS and LC–MS/MS methods were successfully applied.
Within the framework of the German National Residue Control Plan a specific number of samples of animal origin have to be analysed for natural and synthetic steroids each year. As a measure of external quality control of the methods applied in routine analysis a proficiency test was carried out. To this end, in-house reference material containing incurred residues of 17α- and 17β-nortestosterone and 17α- and 17β-estradiol as well as fortified residues of 17α-methyltestosterone and 17α-trenbolone in bovine urine were produced. Before sending the proficiency test material to the participants, the homogeneity of all samples was tested and confirmed. Furthermore extensive short- and long-term stability studies were carried out.
The statistical evaluation of the proficiency test was performed by applying robust statistics as described in standard DIN 38402. Based on the target value and standard deviation z-scores were calculated as standardised measure of the laboratory performance. The evaluation of the proficiency test showed that nine laboratories submitted quantitative results within the tolerance limits for all analytes. Taking into account the individual decision limits, there were no false negative results. In overall evaluation, 11 of 12 laboratories participated successfully.
Abstract
We provide new estimates of the air‐sea flux of CCl
4
using simulations from a global ocean biogeochemistry model (NEMO‐PlankTOM) in combination with depth‐resolved CCl
4
observations from ...global oceanic databases. Estimates of global oceanic CCl
4
uptake are derived from a range of model analyses, including prescribed parameterizations using reported values on hydrolysis and degradation, and analyses optimized using the global observational databases. We evaluate the sensitivity of our results to uncertainties in air‐sea gas exchange parameterization, estimation period, and circulation processes. Our best constrained estimate of ocean CCl
4
uptake for the period 1996–2000 is 20.1 Gg/year (range 16.6–22.7), corresponding to estimates of the partial atmospheric lifetime with respect to ocean uptake of 124 (110–150) years. This new oceanic lifetime implies higher emissions of CCl
4
than currently estimated and therefore a larger missing atmospheric source of CCl
4
.
Plain Language Summary
Carbon tetrachloride (CCl
4
) is a trace gas emitted to the atmosphere during the industrial manufacture of refrigerants and solvents. CCl
4
is also an ozone‐depleting agent affecting loss of the atmosphere's protective ozone layer, and CCl
4
emissions are now controlled by the Montreal Protocol. However, recent analyses of observed atmospheric CCl
4
concentration conclude that the current rate of atmospheric decline is slower than expected, and inconsistent with recent estimates of CCl
4
emissions to and removal from the atmosphere. Estimated oceanic uptake of CCl
4
has been noted as potentially the most uncertain of the atmospheric loss processes, and here we provide new quantification of this flux. Our methodology employs a novel approach and uses a global ocean biogeochemistry model which includes representation of known physical and biogeochemical processes influencing oceanic CCl
4
uptake, together with a compiled global ocean database of CCl
4
observations. The observational database is used to evaluate model simulations, and to derive optimized estimates of the oceanic uptake flux by minimizing the discrepancies between the model and observations. We also evaluate the sensitivity of our estimates of ocean CCl
4
uptake to known uncertainties in the model representation of processes, including air‐sea gas transfer and oceanic chemical and biogeochemical loss. Our best constrained estimate of ocean CCl
4
uptake for the 1996–2000 period is 20.1 Gg/year (range 16.6–22.7), which is greater than previous recent estimates, and implies a larger missing source to the atmosphere of CCl
4
.
Key Points
New estimate of ocean uptake of atmospheric CCl
4
derived using an ocean biogeochemical model and global databases of CCl
4
measurements
Best estimate of ocean CCl
4
uptake is 20.1 Gg/year (16.6–22.7), with a corresponding partial atmospheric lifetime with respect to ocean uptake of 124 (110–150) years
Estimated ocean CCl
4
uptake is larger than recent estimates and implies a larger missing source to the atmosphere
Various morphologies have been observed in sputter-deposited Be ablator capsules, including nodular growth, cone growth and twisted grain growth. By devising an agitation method that includes both ...bouncing and rolling the spherical mandrels during deposition, and by reducing the coating rate, consistent columnar grain structure has now been obtained up to 170 mm. Low mode deformation of the shells is observed on thin CH mandrels, but is suppressed if stiffer mandrels are used. Ablator density measured by weighing and x-ray radiography is 93%-95% of bulk density of Be. Transmission electron microscopy shows 100.200 nm size voids in the film and striations inside the grains. Be shells produced with rolling agitation have met most of the NIF specifications. Some of the few remaining issues will be discussed.
The goal of the quench and partition (Q&P) process for steel heat treatment is to enrich austenite with carbon during a partitioning treatment after initial quenching below the martensite start ...temperature (Ms). Two proposed mechanisms for austenite carbon enrichment during partitioning include carbon transport from martensite and/or the formation of carbide-free bainite. Theoretical calculations show experimentally measured austenite fractions are difficult to explain based upon a mechanism involving solely bainite formation. Carbon partitioning from martensite provides a more satisfactory explanation, although the formation of bainite during partitioning cannot be completely excluded.
Unruptured intracranial aneurysms not undergoing preventive endovascular or neurosurgical treatment are often monitored radiologically to detect aneurysm growth, which is associated with an increase ...in risk of rupture. However, the absolute risk of aneurysm rupture after detection of growth remains unclear.
To determine the absolute risk of rupture of an aneurysm after detection of growth during follow-up and to develop a prediction model for rupture.
Individual patient data were obtained from 15 international cohorts. Patients 18 years and older who had follow-up imaging for at least 1 untreated unruptured intracranial aneurysm with growth detected at follow-up imaging and with 1 day or longer of follow-up after growth were included. Fusiform or arteriovenous malformation-related aneurysms were excluded. Of the 5166 eligible patients who had follow-up imaging for intracranial aneurysms, 4827 were excluded because no aneurysm growth was detected, and 27 were excluded because they had less than 1 day follow-up after detection of growth.
All included aneurysms had growth, defined as 1 mm or greater increase in 1 direction at follow-up imaging.
The primary outcome was aneurysm rupture. The absolute risk of rupture was measured with the Kaplan-Meier estimate at 3 time points (6 months, 1 year, and 2 years) after initial growth. Cox proportional hazards regression was used to identify predictors of rupture after growth detection.
A total of 312 patients were included (223 71% were women; mean SD age, 61 12 years) with 329 aneurysms with growth. During 864 aneurysm-years of follow-up, 25 (7.6%) of these aneurysms ruptured. The absolute risk of rupture after growth was 2.9% (95% CI, 0.9-4.9) at 6 months, 4.3% (95% CI, 1.9-6.7) at 1 year, and 6.0% (95% CI, 2.9-9.1) at 2 years. In multivariable analyses, predictors of rupture were size (7 mm or larger hazard ratio, 3.1; 95% CI, 1.4-7.2), shape (irregular hazard ratio, 2.9; 95% CI, 1.3-6.5), and site (middle cerebral artery hazard ratio, 3.6; 95% CI, 0.8-16.3; anterior cerebral artery, posterior communicating artery, or posterior circulation hazard ratio, 2.8; 95% CI, 0.6-13.0). In the triple-S (size, site, shape) prediction model, the 1-year risk of rupture ranged from 2.1% to 10.6%.
Within 1 year after growth detection, rupture occurred in approximately 1 of 25 aneurysms. The triple-S risk prediction model can be used to estimate absolute risk of rupture for the initial period after detection of growth.
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