A model has been developed to predict whether the development of acidity is feasible within actively corroding sites on spent nuclear fuel (UO
2
) surfaces inside a failed nuclear waste container. ...The model simulations demonstrate that the build-up of acidity is possible within flaws and pores in a corroded UO
2
surface, providing the separation of anodes and cathodes occurs. The extent to which the pH can be depressed is determined by the dissolution rate of the fuel, the dimensions of the defect, the local redox conditions which determine the corrosion potential, and the fraction of the fuel surface that is reactive. Based on the anticipated redox conditions established radiolytically in a failed container it is shown that a suppression of the pH sufficient to accelerate dissolution (pH≤5) is very unlikely.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Although abundant research has focused recently on the quantum criticality of itinerant magnets, critical phenomena of insulating magnets in the vicinity of critical endpoints (CEP's) have rarely ...been revealed. Here we observe an emergent CEP at 2.05 T and 2.2 K with a suppressed thermal conductivity and concomitant strong critical fluctuations evident via a divergent magnetic susceptibility (e.g., χ''(2.05 T,2.2 K)/χ''(3 T,2.2 K)≈23,500%, comparable to the critical opalescence in water) in the hexagonal insulating antiferromagnet HoMnO3.
When formed through dynamical interactions, stellar-mass binary black holes (BBHs) may retain eccentric orbits (e > 0.1 at 10 Hz) detectable by ground-based gravitational-wave detectors. Eccentricity ...can therefore be used to differentiate dynamically formed binaries from isolated BBH mergers. Current template-based gravitational-wave searches do not use waveform models associated with eccentric orbits, rendering the search less efficient for eccentric binary systems. Here we present the results of a search for BBH mergers that inspiral in eccentric orbits using data from the first and second observing runs (O1 and O2) of Advanced LIGO and Advanced Virgo. We carried out the search with the coherent WaveBurst algorithm, which uses minimal assumptions on the signal morphology and does not rely on binary waveform templates. We show that it is sensitive to binary mergers with a detection range that is weakly dependent on eccentricity for all bound systems. Our search did not identify any new binary merger candidates. We interpret these results in light of eccentric binary formation models. We rule out formation channels with rates 100 Gpc−3 yr−1 for e > 0.1, assuming a black hole mass spectrum with a power-law index 2.
Abstract Aims We carried out a large scale study to identify the risk factors for double primary malignancy (DPM) development in gastric cancer patients and to evaluate the clinical implications for ...these patients. Methods A total of 2593 patients who underwent gastrectomy for primary gastric cancer from January 2005 to November 2010 were reviewed with regard to DPM. We compared the clinicopathological characteristics, risk factors for developing DPM, and prognosis between the DPM(+) group and the DPM(−) group. Results Of the 2593 patients, 152 (5.9%) were diagnosed with DPM. The most common accompanying malignancies were colorectal, lung and thyroid. Multivariate analysis indicated that age ( p = 0.016) and MSI status ( p = 0.002) were associated with a higher frequency of DPM. 30.3% of patients were diagnosed with DPM within 1 year around perioperative period and 53.3% of patients had DPM detected during 5 years of post-operative follow up periods. Although there was no significant difference in overall survival between the DPM(+) and DPM(−) group, DPM(+) patients had a worse prognosis than DPM(−) patients in stage I gastric cancer. Conclusions Gastric cancer patients over the age of 60 or with a MSI-high status had an increased risk for developing DPM. Further, in stage I gastric cancer, the presence of DPM was associated with a worse prognosis. Therefore, careful pre- and postoperative surveillance is especially important in these patients.
MnSb 2 O 6 is based on the noncentrosymmetric P321 space group with magnetic Mn 2+ (S = 5/2, L ≈ 0) spins ordering below T N = 12 K in a cycloidal structure. The spin rotation plane was found to be ...tilted away from the c axis Kinoshita et al., Phys. Rev. Lett. 117, 047201 (2016) resulting as a helicoidal ground state, which we refer as the tilted structure. In our previous diffraction study Chan et al., Phys. Rev. B 106, 064403 (2022) we found no evidence that this tilted structure is favored over the pure cycloidal order (referred as the untilted structure). The ground-state magnetic structure, expected to be built and originate from seven nearest-neighbor Heisenberg exchange constants, has been shown to be coupled to the underlying crystallographic chirality with polar domain switching being reported. We apply neutron spectroscopy to extract these symmetric exchange constants. Given the high complexity of the magnetic exchange network, crystallographic structure and complications fitting many parameter linear spin-wave models, we take advantage of multiplexed neutron instrumentation to use the first moment sum rule of neutron scattering to estimate these symmetric exchange constants. The first moment of neutron scattering provides a way of deriving the Heisenberg exchange constant between two neighboring spins if the relative angle and distance of the two ordered spins is known. We show that the first moment sum rule combined with the known magnetic ordering wavevector fixes six of the seven exchange constants. The remaining exchange constant is not determined by this analysis because of the equal spatial bond distances present for different chiral exchange interactions. However, we find this parameter is fixed by the magnon dispersion near the magnetic zone boundary, which is not sensitive to the tilting of the global magnetic structure. We then use these parameters to calculate the low-energy spin-waves in the Néel state to reproduce the neutron response without strong antisymmetric coupling. Using Green's response functions, the stability of long-wavelength excitations in the context of our proposed untilted magnetic structures is then discussed. The results show the presence of strong symmetric exchange constants for the chiral exchange pathways and illustrate an underlying coupling between crystallographic and magnetic "chirality" through predominantly symmetric exchange. We further argue that the excitations can be consistently modelled in terms of an untilted magnetic structure in the presence of symmetric-only exchange constants.
In this study, we observed that the photoluminescence (PL) intensity of ZnO/Ag nanogratings was significantly enhanced compared with that of a planar counterpart under illumination of both transverse ...magnetic (TM) and transverse electric (TE)-mode light. In the TM mode, angle-resolved reflectance spectra exhibited dispersive dips, indicating cavity resonance as well as grating-coupled surface plasmon polariton (SPP) excitation. In the TE mode, cavity resonance only was allowed, and broad dips appeared in the reflectance spectra. Strong optical field confinement in the ZnO layers, with the help of SPP and cavity modes, facilitated polarization-insensitive PL enhancement. Optical simulation results were in good agreement with the experimental results, supporting the suggested scenario.
Abstract Aims There is little information on patient selection criteria for laparoscopy-assisted distal gastrectomy (LADG) that would facilitate a successful initial experience for a surgeon new to ...the procedure. This study aimed to establish patient selection criteria that will allow increased proficiency and shorter operation times for the LADG procedure. Method One hundred LADG with lymphadenectomy and no other combined procedures were consecutively performed by one surgeon. These 100 consecutive LADG procedures were analyzed retrospectively from a prospectively designed computer database. Uni- and multivariate analyses were performed to identify factors influencing operation time. Results According to univariate analysis, operation time was influenced by sex, BMI, surgical experience, and tumor location, whereas multivariate analysis indicated that operation time was significantly influenced only by BMI and surgical experience. The same analyses of only the first 50 cases showed that sex, BMI, surgical experience, and tumor location were independently associated with operation time. As BMI increased, so did operation time, whereas operation time decreased with increasing surgical experience. Conclusion This study suggests that surgeons who have limited experience with this advanced procedure may shorten operation time by considering patient and tumor characteristics in their early attempts at LADG. With a shortened operation time, surgeon with limited experience may become proficient to LADG rapidly.
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