Mass Measurement of Upper fp-Shell N=Z-2 and N=Z-1 Nuclei and the Importance of Three-Nucleon Force along the N=Z Line.

Using a novel method of isochronous mass spectrometry, the masses of ^{62}Ge, ^{64}As, ^{66}Se, and ^{70}Kr are measured for the first time, and the masses of ^{58}Zn, ^{61}Ga, ^{63}Ge, ^{65}As, ^{67}Se, ^{71}Kr, and ^{75}Sr are redetermined with improved accuracy. The new masses allow us to derive residual proton-neutron interactions (δV_{pn}) in the N=Z nuclei, which are found to decrease (increase) with increasing mass A for even-even (odd-odd) nuclei beyond Z=28. This bifurcation of δV_{pn} cannot be reproduced by the available mass models, nor is it consistent with expectations of a pseudo-SU(4) symmetry restoration in the fp shell. We performed ab initio calculations with a chiral three-nucleon force (3NF) included, which indicate the enhancement of the T=1 pn pairing over the T=0 pn pairing in this mass region, leading to the opposite evolving trends of δV_{pn} in even-even and odd-odd nuclei.

Effects of fish oil-derived fatty acids on suboptimal cardiovascular health: A multicenter, randomized, double-blind, placebo-controlled trial.

BACKGROUND AND AIMS: Suboptimal health and metabolic disorders are common in the general population. Both are related to cardiovascular disease. Suboptimal cardiovascular health is defined by the presence of both suboptimal health and metabolic disorders. The aim of the study was to investigate the potential benefit of n-3 long-chain polyunsaturated fatty acids (LCPUFA) in participants with suboptimal cardiovascular health. METHODS AND RESULTS: A total of 422 participants with suboptimal cardiovascular health, from two clinics in China, were enrolled from September 2014 to April 2015. All the enrolled participants were randomly assigned to receive 4 g/d of fish oil or placebo for three months. Suboptimal health was defined using an accepted questionnaire. Metabolic disorders were defined as one or more abnormalities in blood pressure, fasting plasma glucose, blood lipids, and body mass index (BMI). After treatment, the mean BMI fell significantly more in the n-3 LCPUFA group than in the placebo group (-0.29 ± 0.06 kg/m2 vs. -0.02 ± 0.06 kg/m2, P = 0.003). Similar results were found in the changes of suboptimal health status and suboptimal cardiovascular health status (P < 0.05 for all). In a multivariate analysis, the n-3 LCPUFA group was 5.44 (1.15, 25.67) times more likely to have optimal cardiovascular health status after treatment. CONCLUSIONS: n-3 LCPUFA intake improved suboptimal cardiovascular health in this placebo-controlled, randomized, double-blind trial. TRIAL REGISTRATION: This study is registered at www.clinicaltrials.govNCT02103517.

Identification of the Lowest T=2, J

Masses of ^{52g,52m}Co were measured for the first time with an accuracy of ∼10 keV, an unprecedented precision reached for short-lived nuclei in the isochronous mass spectrometry. Combining our results with the previous ß-γ measurements of ^{52}Ni, the T=2, J^{π}=0^{+} isobaric analog state (IAS) in ^{52}Co was newly assigned, questioning the conventional identification of IASs from the ß-delayed proton emissions. Using our energy of the IAS in ^{52}Co, the masses of the T=2 multiplet fit well into the isobaric multiplet mass equation. We find that the IAS in ^{52}Co decays predominantly via γ transitions while the proton emission is negligibly small. According to our large-scale shell model calculations, this phenomenon has been interpreted to be due to very low isospin mixing in the IAS.

VULNERABILITY OF LOW-ARSENIC AQUIFERS TO MUNICIPAL PUMPING IN BANGLADESH.

Sandy aquifers deposited >12,000 years ago, some as shallow as 30 m, have provided a reliable supply of low-arsenic (As) drinking water in rural Bangladesh. This study concerns the potential risk of contaminating these aquifers in areas surrounding the city of Dhaka where hydraulic heads in aquifers >150 m deep have dropped by 70 m in a few decades due to municipal pumping. Water levels measured continuously from 2012 to 2014 in 12 deep (>150m), 3 intermediate (90-150 m) and 6 shallow (<90 m) community wells, 1 shallow private well, and 1 river piezometer show that the resulting drawdown cone extends 15-35 km east of Dhaka. Water levels in 4 low-As community wells within the 62-147 m depth range closest to Dhaka were inaccessible by suction for up to a third of the year. Lateral hydraulic gradients in the deep aquifer system ranged from 1.7×10-4 to 3.7×10-4 indicating flow towards Dhaka throughout 2012-2014. Vertical recharge on the edge of the drawdown cone was estimated at 0.21±0.06 m/yr. The data suggest that continued municipal pumping in Dhaka could eventually contaminate some relatively shallow community wells.

Mass measurements of the neutron-deficient 41Ti, 45Cr, 49Fe, and 53Ni nuclides: first test of the isobaric multiplet mass equation in f p-shell nuclei.

Isochronous mass spectrometry has been applied to neutron-deficient 58Ni projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived T(z)=-3/2 nuclides including 41Ti, 45Cr, 49Fe, and 53Ni have been measured with a precision of 20-40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the A=53, T=3/2 quartet. We perform full space shell model calculations and compare them with the new experimental results.

Direct mass measurements of short-lived A=2Z-1 nuclides (63)Ge, (65)As, (67)Se, and (71)Kr and their impact on nucleosynthesis in the rp process.

Mass excesses of short-lived A=2Z-1 nuclei (63)Ge, (65)As, (67)Se, and (71)Kr have been directly measured to be -46,921(37), -46,937(85), -46,580(67), and -46,320(141) keV, respectively. The deduced proton separation energy of -90(85) keV for (65)As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of (65)As suggest that the majority of the reaction flow passes through (64)Ge via proton capture, indicating that (64)Ge is not a significant rp-process waiting point.