Excited-State Half-Lives in

The known I^{π}=8_{1}^{+}, E_{x}=2129-keV isomer in the semimagic nucleus ^{130}Cd_{82} was populated in the projectile fission of a ^{238}U beam at the Radioactive Isotope Beam Factory at RIKEN. The high counting statistics of the accumulated data allowed us to determine the excitation energy, E_{x}=2001.2(7) keV, and half-life, T_{1/2}=57(3) ns, of the I^{π}=6_{1}^{+} state based on γγ coincidence information. Furthermore, the half-life of the 8_{1}^{+} state, T_{1/2}=224(4) ns, was remeasured with high precision. The new experimental information, combined with available data for ^{134}Sn and large-scale shell model calculations, allowed us to extract proton and neutron effective charges for ^{132}Sn, a doubly magic nucleus far-off stability. A comparison to analogous information for ^{100}Sn provides first reliable information regarding the isospin dependence of the isoscalar and isovector effective charges in heavy nuclei.

Anatase and rutile titanium oxide nanoparticles induce acute kidney injury by coadministration with paraquat, cisplatin or 5-aminosalicylic acid.

Nanoparticles are used in a variety of fields; for example, titanium oxide nanoparticles are used in paints, food additives, cosmetics, and sunscreen materials. Although the use of titanium oxide nanoparticles is regulated, their safety has not been established. Furthermore, the interaction between titanium oxide nanoparticles and various chemical substances and pharmaceuticals is unknown. We co-administered rutile-type titanium oxide nanoparticles (nTR) or anatase-type titanium oxide nanoparticles (nTA) to mice together with paraquat (PQ), cisplatin (CDDP), or anti-5-aminosalicylic acid (5-ASA), and investigated the extent, if any, of liver and kidney injury. As a result, when nTA and nTR were administered alone, no increases were observed in aspartate aminotransferase (AST) and alanine aminotransferase (ALT), which are indicators of liver damage, or urea nitrogen (BUN), which is an indicator of kidney damage. Next, nTA and nTR were co-administered with PQ, CDDP or 5-ASA. Although no increase in ALT or AST was observed, BUN levels increased significantly and acute kidney injury was induced. The findings suggested that titanium oxide nanoparticles induce acute kidney injury through their interaction with chemicals and drugs.

Randomized Trial to Test a Chemo-Mechanical Antiplaque Regimen as Adjunct to Periodontal Therapy.

BACKGROUND: The control of dental biofilm regrowth after nonsurgical periodontal therapy is associated with better clinical outcomes. However, many patients have difficulty achieving optimal plaque control. Subjects with diabetes, in which immune and wound-healing responses are typically impaired, may benefit from intensive antiplaque control regimens after scaling and root planing (SRP). OBJECTIVES: This study aimed to evaluate the effects of an intensive, at-home, chemical, and mechanical antiplaque regimen as an adjunct to SRP for the treatment of moderate to severe periodontitis. A secondary objective was to compare responses in subjects with type 2 diabetes and nondiabetics. METHODS: This was a 6-mo, single-center, parallel-group, randomized trial. The test group received SRP and oral hygiene instructions, and subjects were instructed to use a 0.12% chlorhexidine gluconate mouthrinse twice a day for 3 mo and utilize rubber interproximal bristle cleaners twice a day for 6 mo. The control group received SRP and oral hygiene instructions. The main outcome was change in mean probing depth (PD) from baseline to 6 mo. Secondary outcomes included change in sites with deep PDs, mean clinical attachment level, bleeding on probing, plaque index, hemoglobin A1C, fasting blood glucose, C-reactive protein, and taste assessment. This study was registered at ClinicalTrials.gov as NCT04830969. RESULTS: In total, 114 subjects were randomized to either treatment. Eighty-six subjects completed the trial with no missing visits. Neither an intention-to-treat nor a per-protocol analysis showed statistically significant differences between treatment groups in mean PD at 6 mo. In a subgroup analysis, subjects with diabetes in the test group showed a statistically significant greater reduction in mean PD at 6 mo when compared to subjects with diabetes receiving the control treatment (Δ = 0.15, P = 0.04), while there were no differences within nondiabetics (Δ = 0.02, P = 0.75). CONCLUSION: Outcomes in subjects with diabetes may be improved by chemo-mechanical antiplaque measures after nonsurgical periodontal therapy. KNOWLEDGE TRANSFER STATEMENT: This study suggests diabetic subjects may benefit from an intensive, at-home, chemical, and mechanical antiplaque regimen to improve nonsurgical periodontal therapy outcomes.

Development of continuous measurement system for hydrogen and impurity gases using detector tube.

A relatively accurate, inexpensive, simple, and continuous quantification system for hydrogen and impurity gas(es) using a detector tube was developed in this study. Additionally, different detector tubes can be applied to measure different types of gases in a wide range from ppm order to % level. We optimized this system and evaluated its accuracy as well as the behavior of released H2 and impurity (NH3) gases from a hydrolysis of ammonia borane using a Pt/Al2O3 catalyst. The accuracy of hydrogen quantitation achieved by this system was comparable to that of commercial mass flow meters, and the accuracy of ammonia quantitation was 10% or 5% relative standard deviation, which depends on the detector tube. The concentration of released NH3 was evaluated by image analysis with a time-lapse video of the detector tube and succeeded in analyzing from ppm to % order. The H2 and NH3 release behaviors agreed with pH, and the percentage of reaction was estimated by NMR measurement of the reacted solution. These results confirmed the accuracy of this system.

Bowel movement frequency, stool consistency, and risk of disabling dementia: a population-based cohort study in Japan.

OBJECTIVES: This population-based study aimed to evaluate the association between bowel habits from midlife and dementia. STUDY DESIGN: This was a cohort study using certification records for national long-term care insurance in Japan. METHODS: Participants aged 50 to 79 years who reported bowel habits from eight districts within the Japan Public Health Center-based Prospective Study (JPHC Study) were followed from 2006 to 2016 for incident dementia. Hazard ratio (HR) and 95% confidence interval (CI) were estimated for men and women separately using Cox proportional hazards models accounting for various lifestyle factors and medical histories. RESULTS: Among 19,396 men and 22,859 women, 1889 men and 2685 women were diagnosed with dementia. In men, the multivariable-adjusted HRs compared with bowel movement frequency (BMF) of once/day were 1.00 (95% CI: 0.87-1.14) for twice/day or more, 1.38 (1.16-1.65) for 5-6 times/week, 1.46 (1.18-1.80) for 3-4 times/week, and 1.79 (1.34-2.39) for <3 times/week (P for trend <0.001). In women, the corresponding HRs were 1.14 (0.998-1.31), 1.03 (0.91-1.17), 1.16 (1.01-1.33), and 1.29 (1.08-1.55) (P for trend = 0.043). Harder stool was associated with higher risk (P for trend: 0.0030 for men and 0.024 for women), with adjusted HRs compared to normal stool of 1.30 (1.08-1.57) for hard stool and 2.18 (1.23-3.85) for very hard stool in men, and 1.15 (1.002-1.32) and 1.84 (1.29-2.63) in women. CONCLUSIONS: Lower BMF and harder stool were each associated with higher risk of dementia.

Multiple Mechanisms in Proton-Induced Nucleon Removal at ∼100 MeV/Nucleon.

We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient ^{14}O nucleus with large Fermi-surface asymmetry S_{n}-S_{p}=18.6 MeV at ∼100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the ^{13}N and ^{13}O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering, and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.

Discovery of

The new isotope ^{39}Na, the most neutron-rich sodium nucleus observed so far, was discovered at the RIKEN Nishina Center Radioactive Isotope Beam Factory using the projectile fragmentation of an intense ^{48}Ca beam at 345 MeV/nucleon on a beryllium target. Projectile fragments were separated and identified in flight with the large-acceptance two-stage separator BigRIPS. Nine ^{39}Na events have been unambiguously observed in this work and clearly establish the particle stability of ^{39}Na. Furthermore, the lack of observation of ^{35,36}Ne isotopes in this experiment significantly improves the overall confidence that ^{34}Ne is the neutron dripline nucleus of neon. These results provide new key information to understand nuclear binding and nuclear structure under extremely neutron-rich conditions. The newly established stability of ^{39}Na has a significant impact on nuclear models and theories predicting the neutron dripline and also provides a key to understanding the nuclear shell property of ^{39}Na at the neutron number N=28, which is normally a magic number.

First Application of Mass Measurements with the Rare-RI Ring Reveals the Solar r-Process Abundance Trend at A=122 and A=123.

The Rare-RI Ring (R3) is a recently commissioned cyclotronlike storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF-^{127}Sn, ^{126}In, ^{125}Cd, ^{124}Ag, ^{123}Pd-were injected in R3. Masses of ^{126}In, ^{125}Cd, and ^{123}Pd were measured whereby the mass uncertainty of ^{123}Pd was improved. This is the first reported measurement with a new storage ring mass spectrometry technique realized at a heavy-ion cyclotron and employing individual injection of the preidentified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF. The impact of the new ^{123}Pd result on the solar r-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction Y_{e}. It is found that the neutron capture cross section on ^{123}Pd increases by a factor of 2.2 and ß-delayed neutron emission probability, P_{1 n}, of ^{123}Rh increases by 14%. The neutron capture cross section on ^{122}Pd decreases by a factor of 2.6 leading to pileup of material at A=122, thus reproducing the trend of the solar r-process abundances. The trend of the two-neutron separation energies (S_{2n}) was investigated for the Pd isotopic chain. The new mass measurement with improved uncertainty excludes large changes of the S_{2n} value at N=77. Such large increase of the S_{2n} values before N=82 was proposed as an alternative to the quenching of the N=82 shell gap to reproduce r-process abundances in the mass region of A=112-124.

Transition from spin glass to paramagnetism in the magnetic properties of PrAu2Si2.

It is unexpected that a spin-glass (SG) transition, which generally occurs only in systems with some form of disorder, was observed in the ThCr2Si2-type compound PrAu2Si2at a temperature of ∼3 K. This puzzling phenomenon was later explained based on a novel dynamic frustration model that does not involve static disorder. We present the results of re-verification of the reported SG behaviors by measuring the physical properties of three polycrystalline PrAu2Si2samples annealed under different conditions. Indeed, in the sample annealed at 827 °C for one week, a SG transition does occur at a temperature ofTf∼ 2.8 K as that reported previously in the literature. However, it is newly found that the SG effect is actually more pronounced in the as-cast sample, and almost completely disappears in the well-annealed (at 850 °C for four weeks) sample. The annealing effect observed in PrAu2Si2, that is, SG to paramagnetism transition is discussed by comparing with earlier results reported on the same system and other isomorphic compounds.

Probing the Symmetry Energy with the Spectral Pion Ratio.

Many neutron star properties, such as the proton fraction, reflect the symmetry energy contributions to the equation of state that dominate when neutron and proton densities differ strongly. To constrain these contributions at suprasaturation densities, we measure the spectra of charged pions produced by colliding rare isotope tin (Sn) beams with isotopically enriched Sn targets. Using ratios of the charged pion spectra measured at high transverse momenta, we deduce the slope of the symmetry energy to be 42

Magnetic and transport properties of new ternary uranium-based germanide U2Rh3Ge5.

A new ternary uranium germanide U2Rh3Ge5 has been successfully synthesized and investigated by means of magnetic susceptibility χ(T, H), isothermal magnetization M(T, H), electrical resistivity ρ(T), and specific heat C(T, H) measurements. This compound is found to crystallize in the U2Co3Si5-type orthorhombic structure. The low-field χ(T) shows a clear peak at T N = 41.5 K corresponding to an antiferromagnetic transition. The M(H) curve measured up to 70 kOe exhibits an H-linear behavior at 2 K with very small induced magnetic moments, while it shows upward curvature with increasing temperature, implying the possible presence of a metamagnetic transition in high-field region above 70 kOe. As the temperature decreases, ρ(T) increases slowly at T > T N and decreases rapidly at T < T N, which can be understood based on a semiconductor-like narrow band gap model (or the c-f hybridization effect) and an antiferromagnetic spin-wave model, respectively. No evidence of heavy-fermion behavior or superconductivity transition is observed at temperatures as low as 0.4 K. The obtained experimental results are discussed by comparing with those reported for the isomorphic compound U2Ir3Si5 and the quasi-isomorphic compound U2Rh3Si5.

Mapping of a New Deformation Region around

We performed the first direct mass measurements of neutron-rich scandium, titanium, and vanadium isotopes around the neutron number 40 at the RIKEN RI Beam Factory using the time-of-flight magnetic-rigidity technique. The atomic mass excesses of ^{58-60}Sc, ^{60-62}Ti, and ^{62-64}V were measured for the first time. The experimental results show that the two-neutron separation energies in the vicinity of ^{62}Ti increase compared to neighboring nuclei. This shows that the masses of Ti isotopes near N=40 are affected by the Jahn-Teller effect. Therefore, a development of Jahn-Teller stabilization appears below the Cr isotopes, and the systematics in Sc, Ti, and V isotopes suggest that ^{62}Ti is located close to the peak of the Jahn-Teller effect.

Halo Structure of the Neutron-Dripline Nucleus

The heaviest bound isotope of boron ^{19}B has been investigated using exclusive measurements of its Coulomb dissociation, into ^{17}B and two neutrons, in collisions with Pb at 220 MeV/nucleon. Enhanced electric dipole (E1) strength is observed just above the two-neutron decay threshold with an integrated E1 strength of B(E1)=1.64±0.06(stat)±0.12(sys) e^{2} fm^{2} for relative energies below 6 MeV. This feature, known as a soft E1 excitation, provides the first firm evidence that ^{19}B has a prominent two-neutron halo. Three-body calculations that reproduce the energy spectrum indicate that the valence neutrons have a significant s-wave configuration and exhibit a dineutronlike correlation.

Two-Neutron Halo is Unveiled in

We report the measurement of reaction cross sections (σ_{R}^{ex}) of ^{27,29}F with a carbon target at RIKEN. The unexpectedly large σ_{R}^{ex} and derived matter radius identify ^{29}F as the heaviest two-neutron Borromean halo to date. The halo is attributed to neutrons occupying the 2p_{3/2} orbital, thereby vanishing the shell closure associated with the neutron number N=20. The results are explained by state-of-the-art shell model calculations. Coupled-cluster computations based on effective field theories of the strong nuclear force describe the matter radius of ^{27}F but are challenged for ^{29}F.