We report the first measurement of the flux-integrated cross section of νμ charged-current single π0 production on argon. This measurement is performed with the MicroBooNE detector, an 85 ton active ...mass liquid argon time projection chamber exposed to the Booster Neutrino Beam at Fermilab. This result on argon is compared to past measurements on lighter nuclei to investigate the scaling assumptions used in models of the production and transport of pions in neutrino-nucleus scattering. The techniques used are an important demonstration of the successful reconstruction and analysis of neutrino interactions producing electromagnetic final states using a liquid argon time projection chamber operating at the Earth's surface.
The 40Ar/39Ar dating technique is a high precision (<0.1%) method with wide application to geological samples. However, the method is predicated on the availability of natural mineral standards of ...known age. Widely used 40Ar/39Ar standards include sanidine from the (ca. 28Ma) Fish Canyon Tuff (FCT) and the (ca. 1.2Ma) Alder Creek Rhyolite (ACR). Despite common usage, the ages of FCT and ACR sanidine have proven contentious, with reported values varying by >2%; well outside the ±0.1% aspiration of EARTHTIME (www.earth-time.org). The current study presents ultra-high precision, multi-collector 40Ar/39Ar results for FCT and ACR sanidine, using a new generation ARGUSVI mass spectrometer. These analyses demonstrate the significantly higher (by a factor of ∼10) level of precision achievable using the ARGUSVI system, compared to most previous studies. Significantly, 40Ar/39Ar step-heating analyses resolve distinct age gradients for both FCT and ACR sanidine. Possible explanations for these gradients include combinations of recoil loss of 39Ar, instrumental bias, isotopic fractionation during step-heating, thermally induced argon loss and/or extraneous argon contamination. Minor recoil loss of 39Ar and partial retention of inherited argon during extended magma residence, are deemed the most plausible causes of the age discordance. Given this assumption, we calculate revised (maximum?) eruption ages of 28.01±0.04Ma (2σ) for FCT and 1.178±0.002Ma (2σ) for ACR, relative to the astronomically calibrated age of A1 Tephra sanidine, Crete Rivera et al. (2011)Earth Planet Sci. Lett.311, 420–426. Nonetheless, the ARGUSVI data demonstrate that FCT and ACR sanidine are non-ideal as high precision 40Ar/39Ar standards, with different heating protocols likely to induce inter-laboratory bias. The current findings account for at least some of the scatter in inter-calibration ages reported previously for various 40Ar/39Ar standards. In broader terms, the results mandate a re-evaluation of the astronomically calibrated ages for these and other sanidine samples, while the new generation of multi-collector mass spectrometers provides the means to further evaluate 40Ar/39Ar ages used to define new decay constants and standard ages.
Pelvic radiation is a commonly utilized treatment for malignancy of the genitourinary and lower gastrointestinal tract. Radiation proctitis and the resultant clinical picture varies from asymptomatic ...to potentially life threatening. Similarly, treatment options also vary greatly, from medical therapy to surgical intervention. Commonly utilized medical therapy includes sucralfate enemas, antibiotics, 5-aminosalicylic acid derivatives, probiotics, antioxidants, short-chain fatty acids, formalin instillation and fractionated hyperbaric oxygen. More invasive treatments include endoscopic-based, focally ablative interventions such as dilation, heater and bipolar cautery, neodymium/yttrium aluminum garnet argon laser, radiofrequency ablation or argon plasma coagulation. Despite its relatively common frequency, there is a dearth of existing literature reporting headto-head comparisons of the various treatment options via a randomized controlled approach. The purpose of our review was to present the reader a consolidation of the existing evidence-based literature with the goal of highlighting the comparative effectiveness and risks of the various treatment approaches. Finally, we outline a pragmatic approach to the treatment of radiation proctitis. In light of the lack of randomized data, our goal is to pursue as least invasive an approach as possible, with escalation of care tailored to the severity of the patient’s symptoms. For those cases that are clinicallyasymptomatic or only mildly symptomatic, observation or medical management can be considered. Once a patient fails such management or symptoms become more severe, invasive procedures such as endoscopically based focal ablation or surgical intervention can be considered. Although not all recommendations are supported by level I evidence, reported case series and single-institutional studies in the literature suggest that successful treatment with cessation of symptoms can be obtained in the majority of cases.
Metallurgical converters such as the argon–oxygen decarburization (AOD) converter generally utilize gas blowing for the mixing and refinement of liquid steel. Due to the harsh environment of the ...complex and opaque system, it is common practice to study the stirring of the process through physical and numerical models. Effective mixing in the bath has an important role in refinement such as decarburization and has been vividly studied before. However, high‐temperature chemical reactions that also play a major role are sparsely investigated. With the help of modeling, a computational fluid dynamics model coupled with chemical reactions is developed, allowing the study of both dynamic fluid transport and chemical reactions. Herein, the chemical reactions for a single gas bubble in the AOD are investigated. The study shows that a 60 mm oxygen gas bubble rapidly reacts with the melt and is saturated with carbon in 0.2–0.25 s at low‐pressure levels. The saturation time is affected by the pressure and the composition of the injected gas bubble. The impact of ferrostatic pressure on the reactions is more significant at larger depth differences.
A coupled thermodynamic and fluid transport model on a dynamic bubble in liquid steel is developed to fundamentally investigate pressure differences in decarburization reactions. The impact of ferrostatic pressure is more significant at larger depth differences. A bubble closer to the surface is saturated at higher carbon levels due to the lowered partial pressure of the elements in the gas.
This paper reports an XPS surface study of pure phase BiFeO3 thin film produced and later etched by pure argon ions. Analysis of high-resolution spectra from Fe 2p, Bi 4f and 5d, O 1s, and the ...valence band, exhibited mainly Fe3+ and Bi3+ components, but also reveal Fe2+. High-energy argon etching induces the growth of Fe(0) and Bi(0) and an increment of Fe2+, as expected. The BiFeO3 semiconductor character is preserved despite the oxygen loss, an interesting aspect for the study of the photovoltaic effect through oxygen vacancies in some ceramic films. The metal-oxygen bonds in O 1s spectra are related only to one binding energy contrary to the split from bismuth and iron reported in other works. All these data evidence that the low-pressure argon atmosphere is proved to be efficient to produce pure phase BiFeO3, even after argon etching.
Nanostructured ceramics of the composition Bi0.95La0.05FeO3 were fabricated, and the structure was studied before and after exposure to an argon plasma flow at a temperature of ∼ 600 °C for ∼ 30 ...minutes. Plasma treatment of the surface, with a positive effect of the formation of a monolithically conjugated structure and an increase in the size of grain crystallites, leads to a decrease in the proportion of the main phase on the surface to ∼70%. It has been established that compaction is up to ∼30% of the sample thickness.
The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or ...etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents.
In this study a Candida albicans biofilm, formed on polystyrene (PS) wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture). The capability of plasma-assisted biofilm removal was assessed by microscopic imaging.
The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy.
During the last twelve years the ELSA Project (Eifel Laminated Sediment Archive) at Mainz University has drilled a total of about 52 cores from 27 maar lakes and filled-in maar basins in the ...Eifel/Germany. Dating has been completed for the Holocene cores using 6 different methods (210Pb and 137Cs activities, palynostratigraphy, event markers, varve counting, 14C). In general, the different methods consistently complement one another within error margins. Event correlation was used for relating typical lithological changes with historically known events such as the two major Holocene flood events at 1342 AD and ca 800 BC. Dating of MIS2–MIS3 core sections is based on greyscale tuning, radiocarbon and OSL dating, magnetostratigraphy and tephrochronology. The lithological changes in the sediment cores demonstrate a sequence of events similar to the North Atlantic rapid climate variability of the Last Glacial Cycle. The warmest of the MIS3 interstadials was GI14, when a forest with abundant spruce covered the Eifel area from 55 to 48 ka BP, i.e. during a time when also other climate archives in Europe suggested very warm conditions. The forest of this “Early Stage 3 warm phase” developed subsequently into a steppe with scattered birch and pine, and finally into a glacial desert at around 25 ka BP. Evidence for Mono Lake and Laschamp geomagnetic excursions is found in two long cores. Several large eruptions during Middle and Late Pleistocene (Ulmener Maar – 11,000 varve years BP, Laacher See – 12,900 varve years BP, Mosenberg volcanoes/Meerfelder Maar 41–45 cal ka BP, Dümpel Maar 116 ka BP, Glees Maar – 151 ka BP) produced distinct ash-layers crucial for inter-core and inter-site correlations. The oldest investigated maar of the Eifel is 40Ar/39Ar dated to the time older than 520 ka BP.
► 11 dating methods are applied to 42 sediment cores from 17 Eifel maar lakes. ► 137Cs, 210Pb, 14C, varves, events, palynostratigraphy, palaeomagnetism, OSL, tuning, tephrachronology, Ar/Ar. ► Consistent stratigraphy of sedimentation in Eifel maar lakes during the last 70,000 years. ► Temperate phase during the early MIS3 (GI14) with thermophilous pollen.
The family of isomeric H
C
O
radical cations is of great interest for physical organic chemistry and chemistry occurring in extraterrestrial media. In this work, we have experimentally examined a ...unique synthetic route to the generation of H
C
O
from the C
H
···CO intermolecular complex and also considered the relative stability and monomolecular transformations of the H
C
O
isomers through high-level
calculations. The structures, energetics, harmonic frequencies, hyperfine coupling constants, and isomerization pathways for several of the most important H
C
O
isomers were calculated at the UCCSD(T) level of theory. The complementary FTIR and EPR studies in argon matrices at 5 K have demonstrated that the ionized C
H
···CO complex transforms into the
-HCCHCO
isomer, and this latter species is supposed to be the key intermediate in further chemical transformations, providing a remarkable piece of evidence for kinetic control in low-temperature chemistry. Photolysis of this species at λ = 410-465 nm results in its transformation to the thermodynamically most stable H
CCCO
isomer. Possible implications of the results and potentiality of the proposed synthetic strategy to the preparation of highly reactive organic radical cations are discussed.
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