[en] Accumulative roll bonding (ARB) is an effective method to produce ultrafine-grained (UFG) sheet materials with high strength. In this work, fully annealed AA1050 sheet with an initial thickness of 1.5 mm was processed by ARB up to five cycles. The microstructure was examined by optical microscopy (OM) and transmission electron microscopy (TEM). The results revealed that ARB is a promising process for fabricating ultrafine grained structures in aluminium sheets and the average grain size after 5-cycle ARB reached approximately 300 nm. Meanwhile, a remarkable enhancement in the strength was achieved and the value was about three times the strength of starting material. The microstructure at the bond interface introduced during ARB was investigated and its influence was discussed in detail. In addition, the microstructure and mechanical properties after ARB were compared with that after deformation by equal channel angular pressing (ECAP) up to the same strain. It has been found that ARB is more efficient in grain refinement and strengthening, which can be attributed to the different deformation modes of the two techniques

[en] A series of experiments were performed to simulate the environmental behavior and fate of graphene oxide nanoparticles (GONPs) involved in the surface environment relating to divalent cations, natural organic matter (NOM), and hydraulics. The electrokinetic properties and hydrodynamic diameters of GONPs was systematically determined to characterize GONPs stability and the results indicated Ca"2"+ (Mg"2"+) significantly destabilized GONPs with high aggregate strength factors (SF) and fractal dimension (FD), whereas NOM decreased aggregate SF with lower FD and improved GONPs stability primarily because of increasing steric repulsion and electrostatic repulsion. Furthermore, the GONPs resuspension from the sand bed into overlying water with shear flow confirmed that the release would be restricted by Ca"2"+ (Mg"2"+), however, enhanced by NOM. The interaction energy based on Derjaguin–Landau–Verwey–Overbeek theory verifies the aggregation and resuspension well. Overall, these experiments provide an innovative look and more details to study the behavior and fate of GONPs. - Highlights: • Aggregation and resuspension of GONPs relating to surface environment are presented. • Aggregate strength factors of GONPs aggregates are quantitated by breakage experiment. • Compactness of the aggregates is closely related to fractal dimension. • Models for GONPs aggregation and breakage are synthetically proposed. • Interaction energy based on DLVO theory could interpret aggregation and resuspension of GONPs. - Aggregation and resuspension of graphene oxide relating to divalent cations, natural organic matter (NOM), and hydraulics are investigated based on DLVO theory

[en] The island paradigm for the fine-grained entropy of Hawking radiation is applied to eternal charged accelerating black holes. In the absence of the island, the entanglement entropy grows linearly and divergent at late times, while once the island outside the event horizon is taken into account, the unitary Page curve is reproduced naturally. The impact of the charge and the acceleration on Page curves is investigated at late times. For the Page time and the scrambling time, they both increase as the acceleration increases, while decreasing as the charge increases. In particular, neutral black holes have the largest Page time and scrambling time. It is worth noting that the Page time and the scrambling time is divergent at the extremal case, which implies that islands may be related to the causal structure of spacetime.

[en] The layout and the water intakes of a small modular reactor are quite different from previous nuclear power plants (NPPs). There are three main problems with the water intake engineering in this small modular reactor: the water supply problem of the service water system during the plant maintenance; the problem of biofouling in the water intake tunnel; and the high unit energy cost (UEC) of water intake engineering. In order to solve these problems, a variety of solutions are proposed and analyzed in this paper. (author)

[en] Objective: To study the dose rate distribution on cultured cell plane and establish a reference dose rate table of in vitro cell line ¹²⁵I seed irradiator. Methods: Thermoluminescence dosimetry (TLD) was used to measure the irradiation dose rate of a single 6711 model ¹²⁵I seed with apparent activity of 10.323 MBq in water at point P. Meanwhile, the theoretic value of the irradiation dose rate at point P was calculated with theoretic formula. The difference between the calculated and observed values within 10% was set as standard to analyze the accuracy of the measurement. The irradiation dose rate ora single 6711 model ¹²⁵I seed was measured in 1 mm- thick polystyrene + water medium at point P. The value was applied to differential m non-differential proof along with the value from water medium to study the effect of 1 mm thick polystyrene on distribution of irradiation dose in water. Finally, by simulating the ¹²⁵I seed plane irradiator with nine ¹²⁵I seeds, the distribution table of irradiation dose rate on the cultured cell plane was calculated with theoretical formula. Results: The observed value (n 10) of irradiation dose rate with one ¹²⁵I seed in water at point P was(0.359 ± 0.023) eGy/h and the calculated value was 0.347 cGy/h, the difference was within 10%. The observed value (n=10) of irradiation dose of one ¹²⁵I seed in 1 mm-thick polystyrene + water medium at point P was (0.350±0.027) cGy/h, which showed no statistical difference from the observed value in water under differential and non-differential proof. The reference table on dose rate distribution for cells exposed to ¹²⁵I seed irradiation in vitro was developed. Conclusions: 1 mm-thick polystyrene gives no significant effect on irradiation dose rate distribution flora ¹²⁵I seeds in water. A reference table on the dose rate distribution for cells exposed to ¹²⁵I seed irradiation in vitro has been developed, which can be used to determine an optimal irradiating strategy for future work. (authors)

[en] Nanotwinned copper (Cu) exhibits an unusual combination of ultra-high yield strength and high ductility. A brittle-to-ductile transition was previously experimentally observed in nanotwinned Cu despite Cu being an intrinsically ductile metal. However, the atomic mechanisms responsible for brittle fracture and ductile fracture in nanotwinned Cu are still not clear. In this study, molecular dynamics (MD) simulations at different temperatures have been performed to investigate the fracture behaviour of a nanotwinned Cu specimen with a single-edge-notched crack whose surface coincides with a twin boundary. Three temperature ranges are identified, indicative of distinct fracture regimes, under tensile straining perpendicular to the twin boundary. Below 1.1 K, the crack propagates in a brittle fashion. Between 2 K and 30 K a dynamic brittle-to-ductile transition is observed. Above 40 K the crack propagates in a ductile mode. A detailed analysis has been carried out to understand the atomic fracture mechanism in each fracture regime

[en] We consider the entanglement island in a deformed Jackiw-Teitelboim black hole in the presence of the phase transition. This black hole has the van der Waals-Maxwell-like phase structure as it is coupled with a Maxwell field. We study the behavior of the Page curve of this black hole by using the island paradigm. In the fixed charge ensemble, we discuss different situations with different charges that influence the system's phase structure. There is only a Hawking-Page phase transition in the absence of charges, which leads to an unstable small black hole. Hence, the related Page curve does not exist. However, a van der Waals-Maxwell-like phase transition occurs in the presence of charges. This yields three black hole solutions. The Page curve of the middle size black hole does not exist. For the extremal black hole, the Page time approaches zero in the phase transition situation but becomes divergent without the phase transition. In a word, we study the Page curve and the island paradigm for different black hole phases and in different phase transition situations.

[en] This paper computes the rotational energy levels of the HCO B-tilde ²A'-X²A' transition, especially, the higher values of the rotational quantum numbers N_KaKc and K_a, with the rotational constants which are obtained via B3LYP method with 6–311G basis set, and the results show that the calculated frequencies using the computed vibration-rotation energy levels are in reasonable agreement with the data from the experiment. Meanwhile, the line intensities of HCO are first reported, the results are of significance for the studying HCO. (atomic and molecular physics)

[en] The lateral force mode of an atomic force microscope is a contact-based measurement where the cantilever moves laterally in order to contribute to the lateral component of the tip–surface interaction. An accurate quantitative measure is difficult to achieve and is subject to the calibration of a model of the machine such that the output signal is related to the contact forces. Currently available models and calibration methods do not consider the existence of crosstalk. The influence of the latter on the measurement is not clearly identified and raises the question of the result's accuracy. In this paper a definition of the crosstalk is given and the diversity of the crosstalk briefly presented. A first-order, two-dimensional model of the system that includes the force-based crosstalk is presented. The model is used to simulate a calibration method known as the 'wedge method'. A parametric study is carried out to evaluate the calibration errors that can be made by the 'wedge method'. Results show that force-based crosstalk can have a noticeable influence on the calibration as well as on the estimated friction coefficient

[en] We consider a two-qubit system described by the Heisenberg XY model with Dzyaloshinski–Moriya (DM) anisotropic interaction in a perpendicular magnetic field to investigate the relation between entanglement, geometric phase and quantum phase transition (QPT). It is shown that the DM interaction has an effect on the critical boundary. The combination of entanglement and geometric phase may characterize QPT completely. Their jumps mean that the occurrence of QPT and inversely the QPT at the critical point at least corresponds to a jump of one of them. (general)