We investigate an electron flux dropout during a weak storm on 7–8 November 2008, with Dst minimum value being −37 nT. During this period, two clear dropouts were observed on GOES 11 > 2 MeV ...electrons. We also find a simultaneous dropout in the subrelativistic electrons recorded by Time History of Events and Macroscale Interactions during Substorms probes in the outer radiation belt. Using the Radiation Belt Environment model, we try to reproduce the observed dropout features in both relativistic and subrelativistic electrons. We found that there are local time dependences in the dropout for both observation and simulation in subrelativistic electrons: (1) particle loss begins from nightside and propagates into dayside and (2) resupply starts from near dawn magnetic local time and propagates into the dayside following electron drift direction. That resupply of the particles might be caused by substorm injections due to enhanced convection. We found a significant precipitation in hundreds keV electrons during the dropout. We observe electromagnetic ion cyclotron and chorus waves both on the ground and in space. We find the drift shells are opened near the beginning of the first dropout. The dropout in MeV electrons at GEO might therefore be initiated due to the magnetopause shadowing, and the followed dropout in hundreds keV electrons might be the result of the combination of magnetopause shadowing and precipitation loss into the Earth's atmosphere.
Key Points
RBE model reproduces flux dropouts in subrelativistic electrons
Dropout shows local time dependences in observation and simulation
Dropout in relativistic and subrelativisic electrons shows different features
Alpha backgrounds in the AMoRE-Pilot experiment Alenkov, V.; Bae, H. W.; Beyer, J. ...
European physical journal. C, Particles and fields,
12/2022, Letnik:
82, Številka:
12
Journal Article
Recenzirano
Odprti dostop
The Advanced Mo-based Rare process Experiment (AMoRE)-Pilot experiment is an initial phase of the AMoRE search for neutrinoless double beta decay of
100
Mo, with the purpose of investigating the ...level and sources of backgrounds. Searches for neutrinoless double beta decay generally require ultimately low backgrounds. Surface
α
decays on the crystals themselves or nearby materials can deposit a continuum of energies that can be as high as the
Q
-value of the decay itself and may fall in the region of interest (ROI). To understand these background events, we studied backgrounds from radioactive contaminations internal to and on the surface of the crystals or nearby materials with Geant4-based Monte Carlo simulations. In this study, we report on the measured
α
energy spectra fitted with the corresponding simulated spectra for six crystal detectors, where sources of background contributions could be identified through high energy
α
peaks and continuum parts in the energy spectrum for both internal and surface contaminations. We determine the low-energy contributions from internal and surface
α
contaminations by extrapolating from the
α
background fitting model.
The role of Si and Ca on new wrought Mg-Zn-Mn based alloy BEN-HAMU, G; ELIEZER, D; SHIN, K. S
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
02/2007, Letnik:
447, Številka:
1-2
Journal Article
Recenzirano
The development of new wrought magnesium alloys for automotive industry has increased in recent years due to their high potential as structural materials for low density and high strength/weight ...ratio demands. However, the poor mechanical properties of the magnesium alloys have led to search a new kind of magnesium alloys for better strength and ductility. Magnesium alloys show strong susceptibility to localized corrosion in chlorides solutions due to their inhomogeneous microstructure. The existence of intermetallics in the microstructure of magnesium alloys might represent initiation sites for localized corrosion. This is due to the formation of galvanic couples between the intermetallics and the surrounding matrix. The main objective of this research is to investigate the corrosion behavior of new magnesium alloys; Mg-Zn-Mn-Si-Ca (ZSMX) alloys. The ZSM6X1+YCa alloys were prepared by using hot extrusion method. AC and DC polarization tests were carried out on the extruded rods, which contain different amounts of silicon or calcium. The potential difference in air between different phases and the matrix was examined using scanning Kelvin probe force microscopy (SKPFM). The phases present in the alloys have been identified by optical microscopy and scanning electron microscopy/energy dispersive X-ray spectroscopy. Four different phases were found, i.e. intermetallics containing Si-Mn, Mg-Si, Mg-Zn and Mg-Si-Ca phase. All phases exhibited higher potential differences relative to magnesium matrix indicating a cathodic behavior. The potential difference revealed significant dependence on the chemical composition of the phases. Based on the results obtained from the scanning Kelvin probe force microscopy, the cathodic phases are effective sites for the initiation of localized corrosion in Mg-Zn-Mn-Si-Ca alloys.
•Four polysaccharides were isolated from Korean Citrus hallabong fruit.•Polysaccharides from hallabong peels prevent breast cancer metastasis.•Beneficial effect of polysaccharides was mediated by ...MMP-9 inhibition.
Although the peel of the hallabong (Citrus sphaerocarpa) fruit is rich in polysaccharides, which are valuable dietary ingredients for human health, it is normally wasted. The present study aimed to utilize the peel waste and identify properties it may have against breast cancer metastasis. Hallabong peel extract containing crude polysaccharides was fractionated by gel permeation chromatography to produce four different polysaccharide fractions (HBE-I, -II, -III, and -IV). The HBE polysaccharides significantly blocked tube formation of human umbilical vein vascular endothelial cells (HUVECs), at a concentration of 12.5 or 25μg/mL. Tube formation appeared to be more sensitive to HBE-II than to other HBE polysaccharides. HBE-II also inhibited breast cancer cell migration, through downregulation of matrix metalloproteinase-9 (MMP-9) in MDA-MB-231 triple-negative breast cancer cells. Therefore, inhibition of tube formation and MMP-9-mediated migration observed in HUVEC and MDA-MB-231 cells, respectively, are likely to be important therapeutic targets in triple-negative breast cancer metastasis.
Background
Patients with chronic granulomatous disease (CGD), whom inherit abnormal function of NADPH oxidase 2 (Nox2), suffer from hyperinflammatory responses in lung as well as bacterial and fungal ...infection. There have been studies to reveal the function of Nox2 in hyperinflammatory diseases, especially in asthma, but the exact role of Nox2 in asthma is still unclear and controversial. Therefore, we attempted to clarify the exact role of Nox2 in asthma, using various experimental asthma models.
Methods
Asthma phenotypes were analyzed in response to various allergen‐induced experimental asthma using Nox2‐deficient mice and recombinase gene‐activating‐1‐deficient mice. To understand the underlying mechanisms of exaggerated Th2 effector functions, we investigated the degree of T‐cell activation, levels of activation‐induced cell death (AICD), and regulatory T (Treg)‐cell differentiation in Nox2‐deficient T cells.
Results
Asthma phenotypes were increased through enhanced Th2 differentiation and function in Nox2‐null mice regardless of dose and route of various allergens. Nox2‐deficient T cells also showed hyperactivation, reduced AICD, and diminished Treg‐cell differentiation through increased AKT phosphorylation (T308/S473) and enhanced mitochondrial ROS production.
Conclusion
Our findings indicate that Nox2 deficiency results in exaggerated experimental asthma, which is caused by enhanced Th2 effector function in a T‐cell‐intrinsic manner.
Summary
In patients with cervical spine immobilisation, tracheal intubation devices other than a direct laryngoscope are frequently used to facilitate tracheal intubation and avoid related ...complications. In this randomised controlled trial, we compared videolaryngoscopic and fibrescopic tracheal intubation in patients with a cervical collar. Tracheal intubation was performed using either a videolaryngoscope with a non‐channelled Macintosh blade (n = 166) or a flexible fibrescope (n = 164) in patients having elective cervical spine surgery whose neck was immobilised with a cervical collar to simulate a difficult airway. The primary outcome was the first attempt success rate of tracheal intubation. Secondary outcomes were the overall success rate of tracheal intubation; time to tracheal intubation; use of additional airway manoeuvres; and incidence and severity of tracheal intubation‐related airway complications. First attempt success rate was higher in the videolaryngoscope group than in the fibrescope group (164/166 (98.8%) vs. 149/164 (90.9%), p = 0.003). Tracheal intubation was successful within three attempts in all patients. Median (IQR range) time to tracheal intubation was shorter (50.0 (41.0–72.0 25.0–170.0) s vs. 81.0 (65.0–107.0 24.0–178.0) s, p < 0.001) and additional airway manoeuvres were less frequent (30/166 (18.1%) vs. 91/164 (55.5%), p < 0.001) in the videolaryngoscope group compared with the fibrescope group. The incidence and severity of intubation‐related airway complications were not different between the two groups. When performing tracheal intubation in patients with a cervical collar, videolaryngoscopy with a non‐channelled Macintosh blade was superior to flexible fibrescopy.
The influence of the equal channel angular pressing (ECAP) and simple shear extrusion (SSE) processes on the microstructural and textural developments, as well as mechanical properties of Mg–4Zn ...alloy was studied. Application of 1, 2, and 4 passes of ECAP and SSE resulted in remarkable grain refinement of the initial microstructure of extruded material. Due to the greater shear strain and finer second phase particles, acting as obstacles to grain growth, smaller grain sizes were developed in the SSEed samples compared to the ECAPed counterparts. The fiber texture component of the extruded alloy was gradually transformed to a shear texture component after 4 ECAP passes, while 1, 2, and 4 passes of SSE produced a semi-fiber texture, in which basal planes were parallel to the longitudinal axis of the processed sample. Due to the applied reversal shear strain to the sample inside the SSE die, the volume fraction of the dynamically recrystallized (DRXed) regions was lower than that in the ECAP process which exerted a one-step shear strain to the sample. Shear punch test (SPT) results indicated that both ECAP and SSE improved the strength of the extruded alloy due to the grain boundary strengthening, texture hardening, and dislocation-dislocation interaction mechanisms. The strength of the SSEed samples was greater than ECAPed specimens, due to the finer grain size, higher volume fraction of un-DRXed grains, and lower Schmid factor of the semi-fiber texture component of the former.
Synthetic MR imaging is a time-efficient technique. However, its rather long scan time can be challenging for children. This study aimed to evaluate the clinical feasibility of accelerated synthetic ...MR imaging with deep learning-based reconstruction in pediatric neuroimaging and to investigate the impact of deep learning-based reconstruction on image quality and quantitative values in synthetic MR imaging.
This study included 47 children 2.3-14.7 years of age who underwent both standard and accelerated synthetic MR imaging at 3T. The accelerated synthetic MR imaging was reconstructed using a deep learning pipeline. The image quality, lesion detectability, tissue values, and brain volumetry were compared among accelerated deep learning and accelerated and standard synthetic data sets.
The use of deep learning-based reconstruction in the accelerated synthetic scans significantly improved image quality for all contrast weightings (
< .001), resulting in image quality comparable with or superior to that of standard scans. There was no significant difference in lesion detectability between the accelerated deep learning and standard scans (
> .05). The tissue values and brain tissue volumes obtained with accelerated deep learning and the other 2 scans showed excellent agreement and a strong linear relationship (all,
> 0.9). The difference in quantitative values of accelerated scans versus accelerated deep learning scans was very small (tissue values, <0.5%; volumetry, -1.46%-0.83%).
The use of deep learning-based reconstruction in synthetic MR imaging can reduce scan time by 42% while maintaining image quality and lesion detectability and providing consistent quantitative values. The accelerated deep learning synthetic MR imaging can replace standard synthetic MR imaging in both contrast-weighted and quantitative imaging.
In this study functional characteristics of 23 representative
Lactobacillus strains isolated from the Maasai traditional fermented milk ‘
Kule naoto’ were determined. The
Lb. acidophilus group ...strains showed resistance to gastric juice and bile. In addition, some
Lb. acidophilus strains expressed bile salt hydrolase activity, and had ability to assimilate cholesterol
in vitro.
In-vitro adhesion to HT29 MTX cells of up to 70% was recorded.
Lb. fermentum strains showed almost 100% survival under simulated stomach acidic conditions and physiological salt concentrations of bile salts, hydrophobicity values were over 80%. Most strains of the
Lb. casei and
Lb. acidophilus groups showed aggregation abilities of above 50%. Many strains expressed a protective effect against
N-methyl-
N′-nitro—
N-nitrosoguanidine induced DNA damage according to the ‘comet assay’ and none was virulent. The antibiotic minimum inhibitory concentration of selected strains was established. According to these results, the
Lactobacillus spp associated with ‘
Kule naoto’, contain potentially probiotic (functional) strains.
We present a comprehensive study of the nonproportionality of NaI(Tl) scintillation detectors within the context of dark matter search experiments. Our investigation, which integrates COSINE-100 data ...with supplementary
γ
spectroscopy, measures light yields across diverse energy levels from full-energy
γ
peaks produced by the decays of various isotopes. These
γ
peaks of interest were produced by decays supported by both long and short-lived isotopes. Analyzing peaks from decays supported only by short-lived isotopes presented a unique challenge due to their limited statistics and overlapping energies, which was overcome by long-term data collection and a time-dependent analysis. A key achievement is the direct measurement of the 0.87 keV light yield, resulting from the cascade following electron capture decay of
22
Na
from internal contamination. This measurement, previously accessible only indirectly, deepens our understanding of NaI(Tl) scintillator behavior in the region of interest for dark matter searches. This study holds substantial implications for background modeling and the interpretation of dark matter signals in NaI(Tl) experiments.
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