Magicity versus Superfluidity around ^{28}O viewed from the Study of ^{30}F

The neutron-rich unbound fluorine isotope ^{30}F_{21} has been observed for the first time by measuring its neutron decay at the SAMURAI spectrometer (RIBF, RIKEN) in the quasifree proton knockout reaction of ^{31}Ne nuclei at 235  MeV/nucleon. The mass and thus one-neutron-separation energy of ^{30}F has been determined to be S_{n}=-472±58(stat)±33(sys)  keV from the measurement of its invariant-mass spectrum. The absence of a sharp drop in S_{n}(^{30}F) shows that the "magic" N=20 shell gap is not restored close to ^{28}O, which is in agreement with our shell-model calculations that predict a near degeneracy between the neutron d and fp orbitals, with the 1p_{3/2} and 1p_{1/2} orbitals becoming more bound than the 0f_{7/2} one. This degeneracy and reordering of orbitals has two potential consequences: ^{28}O behaves like a strongly superfluid nucleus with neutron pairs scattering across shells, and both ^{29,31}F appear to be good two-neutron halo-nucleus candidates.

First observation of 28O

Subjecting a physical system to extreme conditions is one of the means often used to obtain a better understanding and deeper insight into its organization and structure. In the case of the atomic nucleus, one such approach is to investigate isotopes that have very different neutron-to-proton (N/Z) ratios than in stable nuclei. Light, neutron-rich isotopes exhibit the most asymmetric N/Z ratios and those lying beyond the limits of binding, which undergo spontaneous neutron emission and exist only as very short-lived resonances (about 10-21 s), provide the most stringent tests of modern nuclear-structure theories. Here we report on the first observation of 28O and 27O through their decay into 24O and four and three neutrons, respectively. The 28O nucleus is of particular interest as, with the Z = 8 and N = 20 magic numbers1,2, it is expected in the standard shell-model picture of nuclear structure to be one of a relatively small number of so-called 'doubly magic' nuclei. Both 27O and 28O were found to exist as narrow, low-lying resonances and their decay energies are compared here to the results of sophisticated theoretical modelling, including a large-scale shell-model calculation and a newly developed statistical approach. In both cases, the underlying nuclear interactions were derived from effective field theories of quantum chromodynamics. Finally, it is shown that the cross-section for the production of 28O from a 29F beam is consistent with it not exhibiting a closed N = 20 shell structure.

Activation of the toll-like receptor 2 signaling pathway by GAPDH from bacterial strain RD055328

We characterized the membrane vesicle fraction (RD-MV fraction) from bacterial strain RD055328, which is related to members of the genus Companilactobacillus and Lactiplantibacillus plantarum. RD-MVs and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were detected in the RD-MV fraction. Immunoglobulin A (IgA) was produced by Peyer's patch cells following the addition of the RD-MV fraction. In the presence of the RD-MV fraction, RAW264 cells produced the pro-inflammatory cytokine IL-6. Recombinant GAPDH probably induced the production of IL-6 by RAW264 cells via superficial toll-like receptor 2 (TLR2) recognition. A confocal laser scanning microscopy image analysis indicated that RD-MVs and GAPDH were taken up by RAW264 cells. GAPDH wrapped around RAW264 cells. We suggest that GAPDH from strain RD055328 enhanced the production of IgA by acquired immune cells via the production of IL-6 by innate immune cells through TLR2 signal transduction.

Extended p_{3/2} Neutron Orbital and the N=32 Shell Closure in ^{52}Ca

The one-neutron knockout from ^{52}Ca in inverse kinematics onto a proton target was performed at ∼230  MeV/nucleon combined with prompt γ spectroscopy. Exclusive quasifree scattering cross sections to bound states in ^{51}Ca and the momentum distributions corresponding to the removal of 1f_{7/2} and 2p_{3/2} neutrons were measured. The cross sections, interpreted within the distorted-wave impulse approximation reaction framework, are consistent with a shell closure at the neutron number N=32, found as strong as at N=28 and N=34 in Ca isotopes from the same observables. The analysis of the momentum distributions leads to a difference of the root-mean-square radii of the neutron 1f_{7/2} and 2p_{3/2} orbitals of 0.61(23) fm, in agreement with the modified-shell-model prediction of 0.7 fm suggesting that the large root-mean-square radius of the 2p_{3/2} orbital in neutron-rich Ca isotopes is responsible for the unexpected linear increase of the charge radius with the neutron number.

Pathophysiological Analysis of Uninephrectomized db/db Mice as a Model of Severe Diabetic Kidney Disease

Diabetic nephropathy, included in diabetic kidney disease (DKD), is the primary disease leading to end-stage renal disease (ESRD) or dialysis treatment, accounting for more than 40% of all patients with ESRD or receiving dialysis. Developing new therapeutics to prevent the transition to ESRD or dialysis treatment requires an understanding of the pathophysiology of DKD and an appropriate animal model for drug efficacy studies. In this study, we investigated the pathophysiology of diabetic kidney disease with type 2 diabetes in uninephrectomized db/db mice. In addition, the nephrectomized db/db mice from 10 weeks to 42 weeks were used to assess the efficacy of long-term administration of the angiotensin-II–receptor antagonist losartan. The blood and urinary biochemical parameters and the blood pressure which is a main pharmacological endpoint of the losartan therapy, were periodically measured. And at the end, histopathological analysis was performed. Uninephrectomized db/db mice clearly developed obesity and hyperglycemia from young age. Furthermore, they showed renal pathophysiological changes, such as increased urinary albumin-creatinine ratio (UACR) (the peak value 3104±986 in 40-week-old mice), glomerular hypertrophy and increased fibrotic areas in the tubulointerstitial tubules. The blood pressure in the losartan group was significantly low compared to the normotensive Vehicle group. However, as expected, Losartan suppressed the increase in UACR (829±500) indicating the medication was sufficient, but the histopathological abnormalities including tubular interstitial fibrosis did not improve. These results suggest that the uninephrectomized db/db mice are useful as an animal model of the severe DKD indicated by the comparison of the efficacy of losartan in this model with the efficacy of losartan in clinical practice.

Pairing Forces Govern Population of Doubly Magic ^{54}Ca from Direct Reactions

Direct proton-knockout reactions of ^{55}Sc at ∼220  MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of ^{54}Ca were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the ^{55}Sc ground state with states in ^{54}Ca. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of ^{55}Sc, valence proton removals populated predominantly the ground state of ^{54}Ca. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Cell-Based Biohybrid Sensor Device for Chemical Source Direction Estimation

This paper describes a method to estimate the direction from which the signal molecule reaches the sensor by using living cells. In this context, biohybrid sensors that utilize a sophisticated sensing system of cells can potentially offer high levels of chemical-detection sensitivity and selectivity. However, biohybrid-sensor-based chemical-source-direction estimation has not received research attention because the cellular response to chemicals has not been examined in the context of directional information. In our approach, we fabricated a device that can limit the interface between the cell-laden hydrogel and the chemical solution of interest to enhance the time difference over which the chemical solution reaches the cells. Chemical detection by cells that express specific receptors is reflected as the fluorescence of the calcium indicator within the cells. Our device has eight chambers that each house 3D cell-laden collagen hydrogels facing circularly outward. The device also works as a cover to prevent chemicals from permeating the hydrogel from above. In our study, by observing the time course of the fluorescence emission of each chamber, we were able to successfully estimate the chemical-source direction within an error range of 7–13°. Our results suggest that a combination of microstructure devices embedded with living cells can be used to exploit cell functionalities to yield chemical-source directional information.

Effect of eicosapentaenoic acid/docosahexaenoic acid on coronary high-intensity plaques detected with non-contrast T1-weighted imaging: subgroup analysis of the AQUAMARINE EPA/DHA study

Background

In the recent the Reduction of Cardiovascular Events with EPA-Intervention Trial (REDUCE-IT), statin therapy plus high-dose eicosapentaenoic acid (EPA) significantly reduced the risk of cardiovascular death in patients with coronary artery disease (CAD) with elevated triglyceride (TG) levels. An epidemiologic study has shown that increasing the intake of long-chain n-3 polyunsaturated fatty acids, especially EPA and docosahexaenoic acid (DHA), are associated with a lower risk of fatal CAD. However, the anti-atherosclerotic effect of high-dose EPA/DHA has not be clarified.

We reported that coronary high-intensity plaques (HIPs) detected with non-contrast T1-weighted imaging (T1WI) on cardiac magnetic resonance (CMR), which can be uniquely quantitative assessed using the plaque-to-myocardium signal intensity ratio (PMR) of ≥1.4, are significantly associated with future coronary events. Moreover, we demonstrated that intensive statin therapy reduces the PMR of coronary HIPs by 19% but is unlikely to completely resolve HIP (PMR<1.0).

In the AQUAMARINE EPA/DHA study, our goal was to assess the anti-atherogenic effect of EPA/DHA in an exploratory manner by examining the change in PMR of coronary HIPs after 12 months of EPA/DHA therapy in patients with CAD on statin therapy.

Methods

This study was designed as a single-center, triple-arm, parallel-group, randomized controlled, open-label, superiority trial examining the effect of 12 months of additional EPA/DHA therapy on coronary HIPs in patients with CAD who receiving statin therapy. Eligible subjects are randomly assigned to the 2 g/day EPA/DHA group (n=26), the 4 g/day group (n=23), or the no EPA/DHA (statin-only) group (n=24) between May 2014 and December 2017. The PMR was defined as the signal intensity of the coronary plaque divided by that of nearby left ventricular myocardium. The primary endpoint is the change in PMR after EPA/DHA treatment.

Results

These 3 groups were well matched at baseline, with no statistically significant differences in age, male sex, conventional coronary risk factors, TG level, medications, and PMR. Figure 1 shows subgroup analysis of patients with high triglyceride levels (>150mg/dl). In the patient-based analysis (A), 12 months of EPA/DHA therapy significantly reduced the PMR of primary lesions. In the segment-based analysis (B), additional reduction of PMR was observed in the high-dose EPA/DHA group compared with the no EPA/DHA treatment group.

Discussion

The present study of patients with high triglyceride levels demonstrated that EPA/DHA had a dose-dependent anti-atherosclerotic effect. This finding may provide additional information of EPA/DHA for lowering the residual risk in patients with CAD on statin therapy.

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Takeda Pharmaceutical Co., Ltd.

Mapping of a New Deformation Region around ^{62}Ti

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.

Sequential Nature of (p,3p) Two-Proton Knockout from Neutron-Rich Nuclei

Twenty-one two-proton knockout (p,3p) cross sections were measured from neutron-rich nuclei at ∼250  MeV/nucleon in inverse kinematics. The angular distribution of the three emitted protons was determined for the first time, demonstrating that the (p,3p) kinematics are consistent with two sequential proton-proton collisions within the projectile nucleus. Ratios of (p,3p) over (p,2p) inclusive cross sections follow the trend of other many-nucleon removal reactions, further reinforcing the sequential nature of (p,3p) in neutron-rich nuclei.

Secretion of equine chorionic gonadotropin and its association with supplementary corpus luteum formation and progesterone concentration in Hokkaido native pony recipient mares

The objectives of this study were to determine the plasma profile of equine chorionic gonadotropin (eCG) and its association with the formation of supplementary corpus luteum (CL) and plasma progesterone concentrations in embryo transfer Hokkaido native pony recipient mares. Blood samples and transrectal ultrasound examination of the reproductive tract were carried out weekly from the day of ovulation until week 32 of gestation (n = 4). Plasma concentrations of eCG and progesterone were measured by enzyme immunoassays. The eCG concentration was first detectable at week 5 for 2 mares and at week 6 for another 2 mares. Immediately after detection, the mean plasma eCG concentrations were observed to rise sharply and reach a peak at week 8. The concentrations then declined dramatically to a baseline (<0.5 IU/mL) by week 21. Plasma progesterone p=p concentrations increased in 2 phases. First, a sharp increase from 0.18 ± 0.05 ng/mL at ovulation to 15.9 ± 4.6 ng/mL at week 1 was observed, then a decrease to 9.69 ± 2.27 ng/mL by week 2, and maintained at this level until week 5 of gestation. The onset of the second rise occurred at week 6 and was observed to peak to 58.3 ± 21.8 ng/mL at week 10, then gradually declined to <10 ng/mL by week 26. The supplementary CLs were first detectable by pregnancy week 6 and 7 for 2 mares each. All supplementary and primary CLs regressed by week 26 for 3 mares and by week 30 for the remaining mare. The mean number of supplementary CL was 4.5 ± 0.8 and their formation in the right ovary (66.7%, 12/18) was higher (P < 0.05) than that in the left ovary (33.3%, 6/18). Among the mares, 1 mare that developed only 2 supplementary CL had 35% lower level of peak eCG and 65% lower concentration of peak progesterone compared with other 3 mares that had 5 or 6 supplementary CL. In conclusion, development of supplementary CL and blood concentrations of progesterone from around day 40 of gestation were associated with eCG concentration. The total number of supplementary CL formation in the present study in embryo transfer Hokkaido native pony recipient mares seemed higher than previously reported supplementary CL number in pregnant mares, with a greater rate in the right ovary than in left.

Two-Neutron Halo is Unveiled in ^{29}F

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.

Halo Structure of the Neutron-Dripline Nucleus ^{19}B

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.

Evaluation of a high-speed but low-throughput RT-qPCR system for detection of SARS-CoV-2

With the emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), a high-speed and convenient detection technology should be at the forefront of medical care worldwide. This study evaluated the usefulness of GeneSoC, a compact, high-speed reciprocal flow quantitative reverse transcription polymerase chain reaction system, for the detection of SARS-CoV-2. The results support the use of this system for the rapid identification of SARS-CoV-2. This approach can contribute to the strategic selection of initial management strategies for patients with COVID-19.

Extending the Southern Shore of the Island of Inversion to ^{28}F

Detailed spectroscopy of the neutron-unbound nucleus ^{28}F has been performed for the first time following proton/neutron removal from ^{29}Ne/^{29}F beams at energies around 230  MeV/nucleon. The invariant-mass spectra were reconstructed for both the ^{27}F^{(*)}+n and ^{26}F^{(*)}+2n coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the ^{28}F ground state, with S_{n}(^{28}F)=-199(6)  keV, while analysis of the 2n decay channel allowed a considerably improved S_{n}(^{27}F)=1620(60)  keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of ^{28}F. Importantly, in the case of the ground state, the reconstructed ^{27}F+n momentum distribution following neutron removal from ^{29}F indicates that it arises mainly from the 1p_{3/2} neutron intruder configuration. This demonstrates that the island of inversion around N=20 includes ^{28}F, and most probably ^{29}F, and suggests that ^{28}O is not doubly magic.