Upgrade of the KamLAND-Zen mini-balloon and future prospects Ozaki, H.; Takeuchi, A.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Volume:
958, Issue:
C
Journal Article
Peer reviewed
Open access
KamLAND-Zen is neutrinoless double beta (0νββ) decay search experiment with Xe-loaded liquid scintillator (XeLS) containing about 91% enriched 136Xe. The mini-balloon is a container for holding XeLS ...at the center of the KamLAND detector without impairing the extremely low radiation environment. We have installed a new mini-balloon with a thickness of 25μm and a radius of 1.92 m, which was made in a class 1 clean room and is almost twice the volume of the KamLAND-Zen 400 mini-balloon. We installed about 745 kg of Xe gas in the XeLS and started the 0νββ decay search in January 2019. In this paper, novel hardware developments to collect data without loss just after a large light yield event, such as a cosmic ray muon spallation are also introduced in preparation for the KamLAND2-Zen which is a future upgrade of the KamLAND-Zen.
We present an improved search for neutrinoless double-beta (0νββ) decay of ^{136}Xe in the KamLAND-Zen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a ...significant reduction of the ^{110m}Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of T_{1/2}^{0ν}>1.07×10^{26} yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region.
Abrasion of the brake lining of automobiles is one of the main antimony (Sb) sources on the road. Therefore, the road effluent possibly supplies Sb to the combined sewer collection system. However, ...Sb in road-sewer systems has attracted little concern, although heavy metals such as copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in sewer water have been studied by many previous authors. We investigated the effect of road effluent on Sb in the combined sewer water by collecting road effluent, road dust, and sewer water under rainy and dry weather conditions. Sb in road effluent showed a significantly higher concentration than the other types of samples, and the Sb concentration in sewer during wet weather was significantly higher than that during dry weather. Furthermore, the Sb concentration in sewer water decreased with time during a wash-off event. Clear positive relationships between Sb and Cu and between Sb and Ba in both road effluent and road dust extract indicate the effect of brake abrasion because the brake lining contains Cu, Sb, and Ba in high concentrations. Approximately 42% of Sb load occurred during the wash-off event, while the loads of Cu and Ba were much less. Unlike Cu and Ba, we conclude that Sb in combined sewer water largely depends on road effluent in wet weather due to the wash-off of road dust, which is probably associated with brake lining abrasion.
Background and Purpose
PGE2 is a major prostanoid that regulates inflammation by stimulating EP1–4 receptors. However, how PGE2 induces an initial inflammatory response to vascular hyper‐permeability ...remains unknown. Here we investigated the role of the PGE2‐EP receptor signal in modulating vascular permeability both in vivo and in vitro.
Experimental Approach
We used a modified Miles assay and intravital microscopy to examine vascular permeability in vivo. Endothelial barrier property was assessed by measuring transendothelial electrical resistance (TER) in vitro.
Key Results
Local administration of PGE2, an EP2 or EP4 receptor agonist into FVB/NJcl mouse ear skin caused vascular leakage, indicated by dye extravasation. Intravital microscopy and laser Doppler blood‐flow imaging revealed that these treatments dilated peripheral vessels and increased local blood flow. Pretreatment with the vasoconstrictor phenylephrine inhibited the PGE2‐induced blood flow increase and vascular leakage. In contrast to the EP2 and EP4 receptor agonists, administration of an EP3 receptor agonist suppressed vascular leakage without altering vascular diameter or blood flow. In isolated HUVECs, the EP3 receptor agonist elevated TER and blocked thrombin‐induced dextran passage. Inhibiting PKA restored the hypo‐permeability induced by the EP3 receptor agonist.
Conclusions and Implications
Activation of the PGE2‐EP2 or ‐EP4 receptor signal induces vasodilatation in mural cells, resulting in increased local blood flow and hyper‐permeability. In contrast, activation of the PGE2‐EP3 receptor signal induces a cAMP‐dependent enhancement of the endothelial barrier, leading to hypo‐permeability. We provide the first evidence that endothelial cells and mural cells cooperate to modulate vascular permeability.
To investigate the epidemiologic aspects of colibacillosis in broiler chickens, 83 Escherichia coli isolates obtained from the pericarditis and perihepatitis lesions in broiler chickens from 4 ...commercial farms, 5 isolates recovered from 5 samples of yolk sac contents that were pooled from 25 emaciated chicks, and 4 fecal isolates obtained from a hatchery that supplied chicks to the 4 commercial farms mentioned above were genetically and bacteriologically characterized. Using pulsed-field gel electrophoresis (PFGE), a total of 92 isolates were classified into 33 pulsotypes. Identical pulsotypes were observed in isolates obtained from hatchery samples and the affected broiler chickens on multiple farms at various sampling times. Seventeen representative isolates with no common origin belonging to 6 pulsotypes and an additional 27 isolates with the other pulsotypes were used for further experiments. Isolates with identical pulsotypes exhibited common traits for virulence-associated genes, lipopolysaccharide core types, and phylogenetic groups. Nine of the isolates were serologically typed as O125 with various types of H antigens and 3 were typed as O25:H4. In the 27 isolates resistant to ceftiofur (CTF), which is a third generation cephalosporin, the blaCTX-M-2, blaCMY-2, blaCTX-M-14, blaCTX-M-65 genes were found in 15, 8, 3, and 1 isolate(s), respectively, and another isolate resistant to CTF had both the blaCTX-M-2 and the blaCMY-2 genes. In the 16 isolates with the blaCTX-M-2 gene, the chromosomal location of the gene was identified in 12 isolates. The plasmid-mediated quinolone resistance genes, oqxAB and aac(6')-Ib-cr, were found in 2 and 3 isolates, respectively. Conjugation experiments revealed that the blaCTX-M-2 (4 isolates), blaCTX-M-14 (3 isolates), blaSHV-12 (1 isolate), and oqxAB (2 isolates) genes were transferred. Our data suggest that E. coli strains with identical pulsotypes had been caused the incidences of colibacillosis and that the antimicrobial resistance genes on conjugative plasmids and those integrated into the chromosome may be spread among avian pathogenic E. coli strains in multiple farms.
The decay of the primordial isotopes 238U, 235U, 232Th, and 40K has contributed to the terrestrial heat budget throughout the Earth's history. Hence, the individual abundance of those isotopes are ...key parameters in reconstructing contemporary Earth models. The geoneutrinos produced by the radioactive decays of uranium and thorium have been observed with the Kamioka Liquid‐Scintillator Antineutrino Detector (KamLAND). Those measurements have been improved with more than 18‐year observation time, and improvement in detector background levels mainly with an 8‐year nearly reactor‐free period, which now permit spectroscopy with geoneutrinos. Our results yield the first constraint on both uranium and thorium heat contributions. The KamLAND result is consistent with geochemical estimations based on elemental abundances of chondritic meteorites and mantle peridotites. The High‐Q model is disfavored at 99.76% C.L. and a fully radiogenic model is excluded at 5.2σ assuming a homogeneous heat producing element distribution in the mantle.
Plain Language Summary
The energy to drive the Earth's engine comes from two different sources: primordial and radiogenic. Primordial energy comes from the added heat by collisions of accreting material and less so by the energy accompanying the sinking of metal to form the core. The radioactive decays of heat producing elements (i.e., potassium, thorium, and uranium) also generate energy and some of these decaying elements produce antineutrinos (geoneutrinos). Geoneutrino measurements provide the Earth's fuel gauge for its radiogenic power supply and insights into the planet's cooling history. The measurement accuracy of the KamLAND experiment has been improved by an 18‐year long‐term observation and a reduction of the significant background generated by commercial reactors. Consequently, modern geoneutrino measurements have entered an era of distinct spectroscopic contributions coming from uranium and thorium. The KamLAND result is consistent with compositional models for the bulk silicate Earth (the crust plus the mantle) predicting low to medium radiogenic heat (10–20 TW (1012 W)) and disfavor high concentration models (30 TW). This constraint sets the best limit on the permissible radiogenic energy budget in the Earth. Geoneutrino observations now begin to make significant contributions to the understanding of fundamental driving forces powering the Earth dynamic behavior.
Key Points
Geoneutrino measurement with low reactor neutrino backgrounds improves the distinct spectroscopic contributions of U and Th
Radiogenic power in the Earth estimated from this geoneutrino measurement is consistent with a range of models and disfavors the higher power model
Identifying the Earth's mantle contribution to the total geoneutrino flux strongly depends on an accurate estimation of the crustal contribution
Background
Interstitial cells of Cajal (ICC) serve as intestinal pacemakers. Postoperative ileus (POI) is a gastrointestinal motility disorder that occurs following abdominal surgery, which is caused ...by inflammation‐induced dysfunction of smooth muscles and enteric neurons. However, the participation of ICC in POI is not well understood. In this study, we investigated the functional changes of ICC in a mouse model of POI.
Methods
Intestinal manipulation (IM) was performed to induce POI. At 24 h or 48 h after IM, the field potential of the intestinal tunica muscularis was investigated. Tissues were also examined by immunohistochemistry and electron microscopic analysis.
Key Results
Gastrointestinal transit was significantly decreased with intestinal tunica muscularis inflammation at 24 h after IM, which was ameliorated at 48 h after IM. The generation and propagation of pacemaker potentials were disrupted at 24 h after IM and recovered to the control level at 48 h after IM. ICC networks, detected by c‐Kit immunoreactivity, were remarkably disrupted at 24 h after IM. Electron microscopic analysis revealed abnormal vacuoles in the ICC cytoplasm. Interestingly, the ICC networks recovered at 48 h after IM. Administration of aminoguanidine, an inducible nitric oxide synthase inhibitor, suppressed the disruption of ICC networks. Ileal smooth muscle tissue cultured in the presence of nitric oxide donor, showed disrupted ICC networks.
Conclusions and Inferences
The generation and propagation of pacemaker potentials by ICC are disrupted via nitric oxide after IM, and this disruption may contribute to POI. When inflammation is ameliorated, ICC can recover their pacemaker function.
The participation of interstitial cells of Cajal (ICC) in the postoperative ileus (POI) is not well understood. In a mouse model of POI, the propagation of electrical pacemaker activity and the networks of ICC were disrupted. These changes were mediated by nitric oxide. In addition to smooth muscle and enteric neuron, ICC may be a new therapeutic target cell for prevention and therapeutic management of POI.
Natural organic matter (NOM) which is a complex mix of particulate and soluble materials in surface water has been identified and reported by previous studies as responsible for membrane fouling. ...However the component of NOM which primarily causes the fouling problem is still not well understood, especially relating to the specific fraction that is mainly responsible for flux decline. Therefore, the main objective of this study is to gain a better understanding on the ultrafiltration membrane fouling characteristics due to fractionated NOMs. The 68 kDa MWCO polysulfone (PSF) and 50 kDa MWCO cellulose acetate (CA) membranes formed by a simple phase inversion technique were employed, and the experiments were carried out in a submerged membrane configuration. The Ulu Pontian River water was fractionated into several components which were hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) fractions using DAX-8 and XAD-4 ion exchange resins. The experimental results showed that the HPI component of NOM exhibited the worst flux decline despite lesser DOC and UV
254 rejections compared to other fractions (HPO and TPI). On the other hand, the HPO fraction showed the highest DOC and UV
254 removals despite possessing lower organics concentration than HPI fraction. Therefore the degree of flux decline is not necessarily proportional with the DOC and UV
254 removals and in fact the degree of DOC and UV
254 rejections are relatively independent of the amount of organics in the source water. Thus, it is worth to note that rejection and fouling are not greatly dependent on the SUVA and DOC concentrations but mostly on the rejection mechanism resulted from the membrane-feed interactions. The hydraulic resistance in series assessment elucidated that the concentration polarization, adsorptive fouling and cake layer deposition were the dominant fouling mechanisms for HPO, HPI and TPI fractions, respectively. Furthermore the effect of cleaning solutions on flux recovery was found significant in nearly restoring the initial membrane permeability. Surprisingly, the HPI fraction was found to exhibit better flux recovery than HPO fraction despite its higher adsorption resistance (
R
a
). Therefore, in future applications, the type of fouling resistance and the dominant fouling mechanism are useful tools which can be employed as quantitative measurements for flux recovery and cleaning techniques effectiveness.
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