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A new isotope 203Ac was produced in the reaction 40Ca + 169Tm at beam energy of 226 MeV. One correlated α-decay chain was attributed to 203Ac. The α-particle energy and half-life were determined to be 8217(16) keV and 56−26+269 μs, respectively. The reduced α-decay width (δ2) of 203Ac was deduced to be 1096−906+921 keV, which indicates a favored α decay. The systematics of δ2 and single-particle energy levels indicate that the new state probably arises from the intruder s1/2 configuration, which shows an onset of deformation in Ac isotopes. The proton separation energy Sp of 203Ac was extracted as −1214(22) keV and the systematics of Sp for odd-A isotopes beyond proton drip line were discussed.

A new proton-unbound isotope 204Ac was produced in the fusion-evaporation reaction Tm(40169Ca,5n)204Ac and identified via the recoil-α correlation at the gas-filled recoiled separators SHANS2 and SHANS. The excitation function for producing 204Ac was measured and the optimal beam energy was evaluated to be 212 MeV. Nineteen ER - α1 - α2 - α3 decay chains were observed for this isotope. Based on these chains, the α-particle energy and half-life of 204Ac were determined to be 7948(15) keV and 7.4−1.4+2.2 ms, respectively. Both are consistent with the theoretical prediction. The reduced α-decay width was deduced to be 49−15+10 keV, which indicates a favored α decay for 204Ac. In addition, more precise decay properties of Eα = 7883(15) keV and T1/2 = 7.7−1.6+2.7 ms were obtained for 205Ac.

The precession of an atomic nucleus can be approximately described as wobbling motion, arising from the coupling of a rotation and a harmonic vibration. Recently, a number of wobbling bands were reported at low spin, which violate the wobbling approximation that can be valid only at high spin. In the present work, we explore the nature of the reported low-spin wobbling bands. Via a new experiment including both angular correlation and linear polarization measurements, we demonstrate that one such band in 187Au is generated by dominant single-particle excitation rather than by the excitation of a wobbling phonon. Assessing the experimental proofs and discussions to assign the reported low-spin wobbling bands, we further point out that the imperfect research paradigm used previously would lead to unreliable identification of low-spin wobbling bands.

The electromagnetic character of the ΔI=1 transitions connecting the 1- to 0-phonon and the 2- to 1-phonon wobbling bands should be dominated by an E2 component, due to the collective motion of the entire nuclear charge. In the present work it is shown, based on combined angular correlation and linear polarization measurements, that the mixing ratios of all analyzed connecting transitions between low-lying bands in 135Pr interpreted as 0-, 1-, and 2-phonon wobbling bands, have absolute values smaller than one. This indicates predominant M1 magnetic character, which is incompatible with the proposed wobbling nature. All experimental observables are instead in good agreement with quasiparticle-plus-triaxial-rotor model calculations, which describe the bands as resulting from a rapid re-alignment of the total angular momentum from the short to the intermediate nuclear axis.

The injection of energetic neutral particles into the plasma of magnetic confinement fusion reactors is a widely-accepted method for heating such plasmas; various types of neutral beam are also used for diagnostic purposes. Accurate atomic data are required to properly model beam penetration into the plasma and to interpret photoemission spectra from both the beam particles themselves (e.g. beam emission spectroscopy) and from plasma impurities with which they interact (e.g. charge exchange recombination spectroscopy). This paper reviews and compares theoretical methods for calculating ionization, excitation and charge exchange cross sections applied to several important processes relevant to neutral hydrogen beams, including H + Be ^4+ and H + H ^+ . In particular, a new cross section for the proton-impact ionization of H (1s) is recommended which is significantly larger than that previously accepted at fusion-relevant energies. Coefficients for an empirical fit function to this cross section and to that of the first excited states of H are provided and uncertainties estimated. The propagation of uncertainties in this cross section in modeling codes under JET-like conditions has been studied and the newly-recommended values determined to have a significant effect on the predicted beam attenuation. In addition to accurate calculations of collisional atomic data, the use of these data in codes modeling beam penetration and photoemission for fusion-relevant plasma density and temperature profiles is discussed. In particular, the discrepancies in the modeling of impurities are reported. The present paper originates from a Coordinated Research Project (CRP) on the topic of fundamental atomic data for neutral beam modeling that the International Atomic Energy Agency (IAEA) ran from 2017 to 2022; this project brought together ten research groups in the fields of fusion plasma modeling and collisional cross section calculations. Data calculated during the CRP is summarized in an appendix and is available online in the IAEA’s atomic database, CollisionDB.

Heat treatment on shale reservoirs can promote the development of secondary fractures in a matrix on the basis of hydraulic fracturing, forming multi-scale gas–water seepage channels and strengthening the gas desorption. Experimental evidence shows that heat treatment can enhance gas recovery in the same mining life. Heat treatment on a shale gas reservoir is a multi-physical and multi-phase coupling process. However, how the thermal stimulation interacts with nonlinear two-phase flow in heterogeneous shale volume fracturing has not been clear. In this paper, a fully coupled THGM model for heating-enhanced shale-gas recovery in heterogeneous shale reservoirs is proposed. First, the governing equations are formulated for the shale-reservoir deformation involving both gas adsorption and thermal expansion, the permeability evolution model for the cracking process of fractured shale, the gas–water two-phase continuity equation considering the effects of gas solubility and the heat transfer equation for heat conduction and convection. The interactions among stress, temperature and seepage in a heterogeneous shale reservoir were studied. Secondly, a test on shale permeability after 50 °C temperature treatment was conducted. The evolution of temperature, capillary pressure, water and gas saturation and the permeability of shale during the heat treatment of the reservoir were numerically analyzed. Finally, the gas production from a shale gas reservoir was numerically simulated with this THGM model. The numerical results indicated that the thermal-induced fracturing, gas desorption and separation from water make predominant contributions to the evolution of permeability. The heat treatment can enhance cumulative gas production by 58.7% after 27.4 years of heat injection through promoting gas desorption and matrix diffusion.

Several new bands have been identified in 130Ba, among which there is one with band-head spin 8+. Its properties are in agreement with the Fermi-aligned νh11/22, 7/2−[523]⊗9/2−[514] Nilsson configuration. This is the first observation of a two-quasiparticle t-band in the A=130 mass region. The t-band is fed by a dipole band involving two additional h11/2 protons. The odd-spin partners of the proton and neutron S-bands and the ground-state band at high spins are also newly identified. The observed bands are discussed using several theoretical models, total Routhians surfaces (TRS), tilted axis cranking (TAC), particle rotor model (PRM) and projected shell model (PSM), which strongly suggest the coexistence of prolate and oblate shapes polarized by rotation aligned two-proton and two-neutron configurations, as well as prolate collective rotations around axes with different orientations. With the new results, 130Ba presents one of the best and most complete sets of collective excitations that a γ-soft nucleus can manifest at medium and high spins, revealing a diversity of shapes and rotations for the nuclei in the A=130 mass region. Keywords: Nuclear structure, Collective rotations, Shape coexistence, Particle rotor model, Projected shell model, Tiltid axis cranking

Three nearly degenerate pairs of doublet bands are identified in 131Ba. Two of them, with positive-parity, are interpreted as pseudospin-chiral quartet bands. This is the first time that a complete set of chiral doublet bands built on the pseudospin partners π(d5/2,g7/2) is observed. The chiral bands with opposite parity built on 3-quasiparticle configurations are directly connected by many E1 transitions, without involving an intermediary non-chiral configuration. The observed band structures in 131Ba have been investigated by using the reflection-asymmetric particle rotor model. The energies and the electromagnetic transition ratios of the three pairs of doublet bands observed in 131Ba are reproduced and they are interpreted as chiral doublet bands with three-quasiparticle configurations. It is the first time that multiple chiral bands are observed in the presence of enhanced octupole correlations and pseudospin symmetry.

The mass of 27P is expected to impact the X-ray burst (XRB) model predictions of burst light curves and the composition of the burst ashes, but large uncertainties and inconsistencies still exist in the reported 27P masses. We have used the β-decay spectroscopy of 27S to determine the most precise mass excess of 27P to date to be −659(9) keV, which is 63 keV (2.3σ) higher and a factor of 3 more precise than the value recommended in the 2016 Atomic Mass Evaluation. Based on the new 27P mass, the Si26(p,γ)27P reaction rate and its uncertainty were recalculated using Monte Carlo techniques. We also estimated the previously unknown mass excess of 27S to be 17678(77) keV, based on the measured β-delayed two-proton energy and the Coulomb displacement energy relations. The impact of these well-constrained masses and reaction rates on the modeling of the explosive astrophysical scenarios has been investigated by post-processing XRB and hydrodynamic nova models. Compared to the model calculations based on the masses and rates from databases, the abundance of A=26 in the burst ashes is increased by a factor of 2.4, while no substantial change was found in the XRB energy generation rate or the light curve. Our calculation also suggests that 27S is not a significant waiting point in the rapid proton capture process, and the change of the Si26(p,γ)27P reaction rate is not sufficiently large to affect the conclusion previously drawn on the nova contribution to the synthesis of galactic 26Al. Keywords: Masses of 27P and 27S, Si26(p,γ)27P reaction, X-ray bursts, Nova outbursts

Fine structure in the α decay of 223U was observed in the fusion-evaporation reaction 187Re(40Ar, p3n) by using fast digital pulse processing technique. Two α-decay branches of 223U feeding the ground state and 244 keV excited state of 219Th were identified by establishing the decay chain 223U →α1 219Th →α2 215Ra →α3 211Rn. The α-particle energy for the ground-state to ground-state transition of 223U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62−10+14 μs. Evolution of nuclear structure for N = 131 even-Z isotones from Po to U was discussed in the frameworks of nuclear mass and reduced α-decay width, a weakening octupole deformation in the ground state of 223U relative to its lighter isotones 219Ra and 221Th was suggested. Keywords: Fine structure, α decay, Spin and parity, Reduced α-decay width, Quadrupole-octupole deformation

The decay of 218Pa was investigated by means of α and γ spectroscopy. The nucleus was produced in the fusion reaction 40Ar+182W and separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). The known α decays of 218Pa were measured with improved precision and newly assigned to be originating from the ground state, which clarified the ambiguities in their previous assignments. In addition, a new isomeric state in 218Pa decaying with α-particle energies of 9691(15) keV, 9595(21) keV and a half-life of 135−32+62 μs was identified. The spins and parities of the involved states were tentatively assigned on the basis of the systematic α-decay properties of the odd-proton N=127 isotones and shell model calculations. Keywords: Odd-proton N=127 isotones, Isomeric state, α-particle energy, Half-life, Shell model calculation, Spin and parity

The spectral line intensities and line shifts of Lyman and Balmer series for transitions up to n = 5 of hydrogen-like ion are studied in plasmas with densities and temperatures in the ranges ne ∼ 1018–1021 cm−3, Te = 0.3–1.2 eV respectively. The screened potential used to describe the interaction between charged particles includes the electron exchange-correlation and finite-temperature gradient effects and is valid for both weakly and strongly coupled plasmas. The dependencies of alpha, beta and gamma line shifts of Lyman and Balmer series on plasma density (for fixed temperature) and temperature (for fixed density) are investigated. The results for the Hα line shifts are compared with the available high-density experimental data.

The β-delayed two-proton emission from 22Al was investigated experimentally through the implantation-decay method. A β-delayed two-proton decay branch from 22Al were identified based on the coincidence of the charged particles and γ-ray signals. The relative momentum (qpp) and the opening angle (θpp) distributions of the two β-delayed protons are measured and a strong peak at qpp∼20MeV/c, as well as a peak at θpp∼30∘ are observed clearly. The β-delayed 2He emission from 22Al with a probability of 29 (13)% by fitting the experimental data with the results of Monte Carlo simulations.

Owing to their unique mechanical and functional properties, both amorphous and nanocrystalline alloys have attracted extensive research interest over the past decades. However, in spite of the tremendous efforts dedicated to both kinds of alloys, their engineering applications are still hindered today because some fundamental issues, such as low thermal stability and poor ductility, are yet to be solved. To overcome these issues, one recent strategy proposed is to combine both amorphous and nanocrystalline structures in a single alloy through the use of either an amorphous or a nanocrystalline alloy as a “template”. On the one hand, the derived amorphous–nanocrystalline alloys may inherit the unique properties from either the amorphous or the nanocrystalline “template”, such as outstanding magnetic properties, extraordinary wear/corrosion resistance, and superior hardness and strength. On the other hand, these amorphous–nanocrystalline alloys also exhibit enhanced thermal stability and ductility, which are difficult to achieve for either the amorphous or the nanocrystalline alloy template. In this review article, we would like to first discuss a number of experimental methods developed to fabricate amorphous–nanocrystalline alloys, including partial crystallization in amorphous precursors, grain boundary amorphization, and physical vapor deposition. After that, we will give an overview of the mechanical and functional properties of the amorphous–nanocrystalline alloys. Finally, we will have a discussion on the existing applications of the amorphous–nanocrystalline alloys in various areas such as renewable and green energy, catalysis, and surface protection. Keywords: Amorphous alloys, Nanocrystalline alloys, Metallic glasses, Composites

The semi-magic nucleus 219Np was produced in the fusion reaction 187Re(36Ar, 4n)219Np at the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure). A fast electronics system based on waveform digitizers was used in the data acquisition and the sampled pulses were processed by digital algorithms. The reaction products were identified using spatial and time correlations between the implants and subsequent α decays. According to the observed α-decay chain, an energy of Eα=9039(40) keV and a half-life of T1/2=0.15−0.07+0.72 ms were determined for 219Np. The deduced proton binding energy of 219Np fits well into the systematics, which gives another evidence of that there is no sub-shell closure at Z=92. The influence of the N=126 shell closure on the stability of Np isotopes is discussed within the framework of α-decay reduced widths. Keywords: N=126 shell closure, Digital algorithm, α-particle energy, Half-life, Proton drip-line

The N=130 short-lived isotope 223Np was produced as evaporation residue (ER) in the fusion reaction 40Ar + 187Re at the gas-filled recoil separator Spectrometer for Heavy Atom and Nuclear Structure (SHANS). It was identified through temporal and spatial correlations with α decays of 215Ac and/or 211Fr, the third and fourth members of the α-decay chain starting from 223Np. The pileup signals of ER(223Np)–α(223Np)–α(219Pa) were resolved by using the digital pulse processing technique. An α decay with half-life of T1/2=2.15(52100) μs and energy of Eα=9477(44)keV was attributed to 223Np. Spin and parity of 9/2− were tentatively proposed for the ground state of 223Np by combining the reduced α-decay width and large-scale shell-model calculations. This assignment together with the proton separation energy disprove the existence of a Z=92 subshell closure. Keywords: New isotope, Short-lived α radioactivity, Proton separation energy, Subshell closure

The decay of the lightest nucleus with Tz=−3, 22Si, was studied by a silicon array. A charged-particle group at 5600 (70) keV in the decay-energy spectrum was identified experimentally as β-delayed two-proton emission from the isobaric analog state (IAS) of 22Al. Experimental results of the IAS fed by a superallowed Fermi transition were compared with our large-scale shell-model calculations. The ground-state mass of 22Si was obtained indirectly in the experiment for the first time. Two-proton separation energy for 22Si is deduced to be −108 (125) keV, which indicates that it is a very marginal candidate for two-proton ground-state emission.

The electron capture in N5+-H collisions imbedded in a Debye plasma is studied by using the two-center atomic orbital close-coupling method in the energy range from 1 keV/u to 200 keV/u. The atomic orbitals and electron binding energies of atomic states are calculated within the Debye–Hückel approximation of the screened Coulomb potential and used in atomic orbital close-coupling dynamics formalism to calculate the electron capture cross sections. The electron capture cross sections and the charge transfer spectral lines of N4+(1s2nl) for a number of representative screening parameter values are presented and discussed. It is found that the screening of Coulomb interactions affects the entire collision dynamics and the magnitude and energy behavior of state-selective cross sections. The changes in electron binding energies and capture cross sections when the interaction screening varies introduce dramatic changes in the radiation spectrum of N4+(1s2nl) capture states with respect to the unscreened interaction case.

Caprock is a water-saturated formation with a sufficient entry capillary pressure to prevent the upward migration of a buoyant fluid. When the entry capillary pressure of caprock is smaller than the pressure exerted by the buoyant CO2 plume, CO2 gradually penetrates into the caprock. The CO2 penetration depth into a caprock layer can be used to measure the caprock sealing efficiency and becomes the key issue to the assessment of caprock sealing efficiency. On the other hand, our numerical simulations on a caprock layer have revealed that a square root law for time and pore pressure exists for the CO2 penetration into the caprock layer. Based on this finding, this study proposes a simple approach to estimate the CO2 penetration depth into a caprock layer. This simple approach is initially developed to consider the speed of CO2 invading front. It explicitly expresses the penetration depth with pressuring time, pressure difference and pressure magnitude. This simple approach is then used to fit three sets of experimental data and good fittings are observed regardless of pressures, strengths of porous media, and pore fluids (water, hydrochloric acid, and carbonic acid). Finally, theoretical analyses are conducted to explore those factors affecting CO2 penetration depth. The effects of capillary pressure, gas sorption induced swelling, and fluid property are then included in this simple approach. These results show that this simple approach can predict the penetration depth into a caprock layer with sufficient accuracy, even if complicated interactions in penetration process are not explicitly expressed in this simple formula.

This paper proposes a novel method based on first-order statistics, aims to solve the problem of the independent component extraction of complex valued signals in instantaneous linear mixtures. Single-step and iterative algorithms are proposed and discussed under the engineering practice. Theoretical performance analysis about asymptotic interference-to-signal ratio (ISR) and probability of correct support estimation (PCE) are accomplished. Simulation examples validate the theoretic analysis, and demonstrate that the single-step algorithm is extremely effective. Moreover, the iterative algorithm is more efficient than complex FastICA under certain circumstances.

Unlike conventional blind source separation (BSS) deals with independent identically distributed (i.i.d.) sources, this paper addresses the separation from mixtures of sources with temporal structure, such as linear autocorrelations. Many sequential extraction algorithms have been reported, resulting in inevitable cumulated errors introduced by the deflation scheme. We propose a robust separation algorithm to recover original sources simultaneously, through a joint diagonalizer of several average delayed covariance matrices at positions of the optimal time delay and its integers. The proposed algorithm is computationally simple and efficient, since it is based on the second-order statistics only. Extensive simulation results confirm the validity and high performance of the algorithm. Compared with related extraction algorithms, its separation signal-to-noise rate for a desired source can reach 20dB higher, and it seems rather insensitive to the estimation error of the time delay.

Polymorphisms of DGAT1 and STAT5A genes in Xinong Saanen and Guanzhong goat breeds were investigated. PCR-RFLP, SSCP, and DNA sequencing were used to identify three SNPs: DQ380250:g.407_408insC in the DGAT1 gene, AJ237937:g.6798C>T and g.6852C>T in the STAT5A gene. In DGAT1 g.407_408insC locus, the frequencies of C- allele were 0.79-0.85, and frequencies of C+ allele were 0.21-0.15. At STAT5A g.6852C>T locus, frequencies of C allele were 0.70-0.72, and frequencies of T allele were 0.30-0.28. Compared with goats with DGAT1 C-C-, those with C-C+ genotype had greater milk fat (P < 0.05). The goats with STAT5A CT had greater milk yield than those with CC genotype (P < 0.05). The results showed that does with C-C-CT and C-C+CT yielded more milk than those with C-C-CC(P < 0.05). In addition, does with C-C+CT had the highest milk fat in comparison with other combination genotypes (P < 0.05).

The myostatin (MSTN) gene was studied as a candidate genetic marker for growth traits. We investigated polymorphisms of the MSTN gene in 664 individuals from four goat populations and applied PCR-SSCP and DNA sequencing analysis to reveal two single nucleotide polymorphisms (DQ167575: g.368A>C (p.Lys49Thr) and g.4911C>T. At g.368A>Clocus, the frequencies of g.368A allele were 0.75-0.81, and the frequencies of g.368C allele were 0.19-0.25. At g.4911C>T locus, the frequencies of g.4911C allele were 0.76-0.82, and frequencies of g.4911T allele were 0.18-0.24. Compared to the female goats with AC genotype, those with AA genotype had superior body weight in Boer goats (15.69 ± 0.28 vs. 14.51 ± 0.31, P < 0.05) and F1 generation of Boer × Guanzhong dairy goats (19.39 ± 0.34 vs. 18.27 ± 0.33, P < 0.05). In addition, the female goats with AA genotype (45.80 ± 0.33 cm) had greater withers height than those with AC genotype (44.78 ± 0.36 cm) in F2 generation of Boer × Guanzhong dairy goats (P < 0.05). Hence, the biochemical and physiological functions along with the results obtained in our investigation suggest that the MSTN gene might play an important role in affecting the growth traits in goats.