Uncertainties in the nu p-process: supernova dynamics versus nuclear physics

We examine how the uncertainties involved in supernova dynamics as well as in nuclear data inputs affect the nup-process in the neutrino-driven winds. For the supernova dynamics, we find that the wind termination by the preceding dense ejecta shell, as well as the electron fraction (Y_{e, 3}; at 3 10^9 K) play a crucial role. A wind termination within the temperature range of (1.5-3) 10^9 K greatly enhances the efficiency of the nu p-process. This implies that the early wind phase, when the innermost layer of the preceding supernova ejecta is still 200-1000 km from the center, is most relevant to the nup-process. The outflows with Y_{e, 3} = 0.52-0.60 result in the production of the p-nuclei up to A=108 with interesting amounts. Furthermore, the p-nuclei up to A=152 can be produced if Y_{e, 3} = 0.65 is achieved. For the nuclear data inputs, we test the sensitivity to the rates relevant to the breakout from the pp-chain region (A < 12), to the (n, p) rates on heavy nuclei, and to the nuclear masses along the nup-process pathway. We find that a small variation of the rates of triple-alpha and of the (n, p) reaction on 56Ni leads to a substantial change in the p-nuclei production. We also find that 96Pd (N=50) on the nup-process path plays a role as a second seed nucleus for the production of heavier p-nuclei. The uncertainty in the nuclear mass of 82Zr can lead to a factor of two reduction in the abundance of the p-isotope 84Sr.Comment: 20 pages, 22 figures, accepted for publication in Ap

Water immersion increases the concentration of the immunoreactive N-terminal fragment of pro-atrial natriuretic factor in human plasma

Atrial natriuretic factor (ANF) N-terminal (ANF 1–98) and C-terminal (ANF 99–126) fragments were determined by radioimmunoassay in human plasma. Mean basal plasma ANF N-terminal concentrations in 9 healthy subjects were 461 ± 58 fmol/ml,significantly (p<0.0001) higher than ANF C-terminal concentrations ( 4.8 ± 0.5 fmol/ml). Central volume stimulation by one hour head-out water immersion (WI) induced a significant (p<0.01) increase of the C-terminal peptide levels to 11.6 ± 2.3 fmol/ml,paralleled by a significant (p<0.001) increase of the N-terminal fragment levels to 749 ± 96 fmol/ml. Increases of plasma concentrations of both fragments upon WI correlated significantly (r=0.71;p<0.05). These data suggest cosecretion of the N-terminal fragment with the C-terminal fragment of pro ANF 1–126 following a physiological stimulus of ANF release in man

First-principles study of nickel-silicides ordered phases

We present a study of nickel-silicides ordered alloys by means of first-principles calculations. Emphasis was put on the phases (low and high temperatures) identified in the binary phase diagram, namely: Ni3Si-β1, -β2, and -β3, Ni31Si12-γ, Ni2Si-δ, -θ, Ni3Si2-ɛ, NiSi-MnP and NiSi2-α. In addition, some common structures are computed for information: L12, D03 and D022. The simulations reproduce with a high accuracy lattice parameters and formation energies of main experimental structures, except for β2 and β3. Our results clarify the crystallographic nature of the γ structure, and the comparison of experimental Raman spectra and vibrational calculations will help experimentalists to identify without ambiguity NiSi3 structures

Dietary fibre and cell-wall polysaccharides in chaenomeles fruits

In this paper, research on dietary fibre and cell-wall polysaccharides in chaenomeles fruits is reported and summarised. The dietary fibre in fruits of 12 genotypes of Japanese quince (Chaenomeles japonica) and 1 genotype of flowering quince (C. speciosa) was prepared using two different methods: the Alcohol Insoluble Solid (AIS) method; and the AOAC method for total as well as for soluble and insoluble fibre. The two methods resulted in significantly different estimates, however, no interaction was found between the methods and the genotypes studied. For content of total dietary fibre, three main groups were distinguished, one containing a low amount of fibre (3 genotypes, 28–30 g/100 g dry matter); one containing a moderate amount of fibre (9 genotypes, 30–36 g/100 g dry matter) and an isolated genotype (C. speciosa) that contained a high amount of fibre (38 g/100 g dry matter). The amount and the nature of monomeric sugars in the constituent polysaccharides of the fibre were determined after total hydrolysis of the AIS and the TDF (Total Dietary Fibre). The fibre contained mostly pectic and cellulosic polysaccharides. A sequential extraction scheme allowed the separation of the cell-wall material into its major components (cellulose, pectins and hemicelluloses). The AIS was composed of 30 g pectins, 8 g hemicelluloses and 60 g cellulosic residue/100 g AIS. In 100 g entire dry fruit (800 g entire fresh fruit) there were 11 g pectins, 3 g hemicelluloses and 18 g cellulosic residue. Pectins were mostly located in the flesh of the fruit. Pectins were more efficiently extracted with hot dilute acid than with other extraction media. Pectins had a high degree of methylation (DM) and a low degree of acetylation (DAc). No difference was found in the quantity of polysaccharides extracted from two Japanese quince genotypes, or in the composition of these constituent polysaccharides. The physico-chemical properties of pectins extracted from two genotypes of Japanese quince were studied. On average, the fruits contained 11 g pectins/100 g dry fruit corresponding to 1.4 g pectins/100 g fresh fruit. Pectins were sequentially extracted, and the cells from the flesh of the fruits were observed with a confocal laser scan microscope. Although the dilute acid conditions were the most efficient for extraction of pectins, pectins extracted by water or potassium oxalate had higher (> 600 ml/g) intrinsic viscosities than pectins extracted by dilute acid (< 400 ml/g). Anionic exchange chromatography was performed on the acid-extracted pectins. The pectins were composed of four populations, the first being mainly composed of arabinans, the second of homogalacturonans and the third of rhamnogalacturonans. The composition of the fourth population differed depending on the genotype studied

X-ray ptychography on low-dimensional hard-condensed matter materials

Tailoring structural, chemical, and electronic (dis-)order in heterogeneous media is one of the transformative opportunities to enable new functionalities and sciences in energy and quantum materials. This endeavor requires elemental, chemical, and magnetic sensitivities at the nano/atomic scale in two- and three-dimensional space. Soft X-ray radiation and hard X-ray radiation provided by synchrotron facilities have emerged as standard characterization probes owing to their inherent element-specificity and high intensity. One of the most promising methods in view of sensitivity and spatial resolution is coherent diffraction imaging, namely, X-ray ptychography, which is envisioned to take on the dominance of electron imaging techniques offering with atomic resolution in the age of diffraction limited light sources. In this review, we discuss the current research examples of far-field diffraction-based X-ray ptychography on two-dimensional and three-dimensional semiconductors, ferroelectrics, and ferromagnets and their blooming future as a mainstream tool for materials sciences

Penning trap mass measurements on (99-109)$Cd with ISOLTRAP and implications on the rp process

Penning trap mass measurements on neutron-deficient Cd isotopes (99-109)Cd have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all with relative mass uncertainties below 3*10^8. A new mass evaluation has been performed. The mass of 99Cd has been determined for the first time which extends the region of accurately known mass values towards the doubly magic nucleus 100Sn. The implication of the results on the reaction path of the rp process in stellar X-ray bursts is discussed. In particular, the uncertainty of the abundance and the overproduction created by the rp-process for the mass A = 99 is demonstrated by reducing the uncertainty of the proton-separation energy of 100In Sp(100In) by a factor of 2.5.Comment: 14 pages, 9 figure