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In this paper, we consider the spectral properties of the Moran measure μ R , D on R 2 generated by the pair ( R , D ) , where R = b 1 0 0 b 2 is an expanding real matrix, and D = { D i } i = 1 ∞ ⊆ Z 2 with # D i = p , where sup i ∈ N , d ∈ D i | d | < ∞ , and p is a prime number. Let B ( p ) : ≡ 1 p j k : 1 ⩽ j , k ⩽ p − 1 and Z ( δ ^ E ) = { x ∈ R 2 : δ ^ E ( x ) = 0 } , where δ E = 1 # E ∑ e ∈ E δ e , δ e denotes the Dirac measure at e. We show that under the conditions that Z ( δ ^ D i ) = ⋃ j = 1 p − 1 ( j a i + Z 2 ) for some a i ∈ B ( p ) , and { x ∈ 0 , 1 2 : | δ ^ D i ( x ) | = 1 } = 0 0 , then μ R , D is a spectral measure if and only if R = p k 1 0 0 p k 2 for some k 1 , k 2 ∈ N . A special case is the self-affine Sierpinski-type measure with D = 0 0 , 1 0 , 0 1 , which was considered by Dai, Fu and the author [ACHA, 2021], over which R = 3 k 1 0 0 3 k 2 for some k i ∈ N , i = 1, 2.

Bi4Br4 is a quasi-one-dimensional van der Waals topological insulator with novel electronic properties. Several efforts have been devoted to the understanding of its bulk form, yet it remains a challenge to explore the transport properties in low-dimensional structures due to the difficulty of device fabrication. Here we report for the first time a gate-tunable transport in exfoliated Bi4Br4 nanobelts. Notable two-frequency Shubnikov–de Haas oscillations oscillations are discovered at low temperatures, with the low- and high-frequency parts coming from the three-dimensional bulk state and the two-dimensional surface state, respectively. In addition, ambipolar field effect is realized with a longitudinal resistance peak and a sign reverse in the Hall coefficient. Our successful measurements of quantum oscillations and realization of gate-tunable transport lay a foundation for further investigation of novel topological properties and room-temperature quantum spin Hall states in Bi4Br4.

In this letter, an annular anode is designed for producing arc plasmas with a large non-equilibrium region by using a counterflow cold gas through the annular anode. The coupled mass-momentum-energy exchange processes in an argon arc plasma are studied numerically and experimentally. The counter-injection of the cold argon gas from the center of the anode leads to a steep gradient of the heavy-particle temperature due to the formation of a thin stagnation layer resulting from the interaction of the high temperature plasma with the cold gas; and in particular, a large volume non-equilibrium ‘dark’ plasma region is obtained above the anode surface. The results show that, with the enhancement of the convective heat transfer process in the plasma core region, the fraction of the non-equilibrium region to the whole arc plasma region reaches 92.2% where the heavy-particle temperature can be reduced significantly, e.g. ∼2300 K, while simultaneously, the electron temperature and number density are remained at high levels greater than 8000 K and 2.4 × 1020 m−3, respectively, under the operating condition studied in this letter. This research not only deepens the understanding to the non-equilibrium synergistic transport mechanisms of arc plasmas, but also provides a method for producing a large volume non-equilibrium plasma region so as to promote various existing applications, or even creating new applications in the future.

The plastic deformation properties of cylindrical pre-void aluminum–magnesium (Al–Mg) alloy under uniaxial tension are explored using molecular dynamics simulations with embedded atom method (EAM) potential. The factors of Mg content, void size, and temperature are considered. The results show that the void fraction decreases with increasing Mg in the plastic deformation, and it is almost independent of Mg content when Mg is beyond 5%. Both Mg contents and stacking faults around the void affect the void growth. These phenomena are explained by the dislocation density of the sample and stacking faults distribution around the void. The variation trends of yield stress caused by void size are in good agreement with the Lubarda model. Moreover, temperature effects are explored, the yield stress and Young’s modulus obviously decrease with temperature. Our results may enrich and facilitate the understanding of the plastic mechanism of Al–Mg with defects or other alloys.

Aiming at the selective adsorption treatment of 90Sr in radioactive waste liquid, we need to synthesize MnO2 and other inorganic ion exchanger with high selectivity for Sr2+ in the waste water, find the best material ratio, and prepare the raw material liquid. The feed liquid is blown into the hot dimethylsilicone oil by the self-made spherical particle preparation device and loaded on the Al2O3 matrix. The composite adsorbent with appearance and size similar to ion exchange resin was prepared. The physicochemical properties of the composite adsorbent were characterized by SEM,FT-IR and XRD.Different concentrations of strontium ion solution were prepared to study the change of adsorption capacity of Sr2+ at different time. The effects of pH on the adsorption properties of the adsorption properties under the influence of different initial concentrations and different coexisting ions were studied. According to the experimental data, the pseudo first order and quasi second order kinetic first order and quasi second order kinetic equations were used to fit the adsorption process. Two typical adsorption isotherm models, Langmuir and Freundlich models, were used to describe the adsorption process of Sr2+ by composite adsorbents.

Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1−xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1−xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1−xTix) O3 thin films can be adjusted by choosing the suitable substrates.

The photon flux-dependent transient absorption spectroscopy is employed to investigate the carrier dynamics of Cs2AgBiBr6 nanocrystals (NCs), exhibiting that the hot carrier cooling, the self-trapping process, the surface defect capture and the carrier recombination together participate in the carrier relaxation process after photoexcitation. The evolution of their lifetimes as a function of 〈N〉 (average photon number per nanocrystal) all show two stages. Moreover, the role of HC in the subsequent carrier dynamics is also discussed. These results can help explain the carrier dynamics in the double perovskite NCs for designing and optimizing the perovskite-based optoelectronic devices with high performance.

We report a transportable one-dimensional optical lattice clock based on 87Sr at the National Time Service Center. The transportable apparatus consists of a compact vacuum system and compact optical subsystems. The vacuum system with a size of 90 cm× 20 cm× 42 cm and the beam distributors are assembled on a double-layer optical breadboard. The modularized optical subsystems are integrated on independent optical breadboards. By using a 230 ms clock laser pulse, spin-polarized spectroscopy with a linewidth of 4.8 Hz is obtained which is close to the 3.9 Hz Fourier-limit linewidth. The time interleaved self-comparison frequency instability is determined to be 6.3 × 10–17 at an averaging time of 2000 s.

Surface hydroxylation of crude Al2O3 (c-Al2O3) nanoparticles by H2O2 was conducted to tailor the electrical properties of UV-cured resin. The hydroxyl groups on Al2O3 particles were designed to establish hydrogen bonding between the hydroxyl and carboxyl groups, which favors the enhancement of interfacial strength between fillers and UV-cured resin matrix. The effect of interfacial strength on the electrical properties was investigated. Owing to the improved interfacial strength, it can be conjectured that a larger volume of the interaction zone exists in UV-cured resin/hydroxylated Al2O3 (UV/h-Al2O3) composites. As a consequence, the number of deeper traps is increased, restraining the charge migration and raising the charge injection barrier. Thus, UV/h-Al2O3 composites exhibit remarkably enhanced breakdown strength, improved volume resistivity and suppressed space charge accumulation in comparison with that of UV/c-Al2O3 composites at the same filler content. It was found that the addition of 0.5 wt% h-Al2O3 increases the AC breakdown strength and volume resistivity by 15.5% and 367.9%, respectively. Our results suggest that hydroxylation is an efficient way to improve the electrical properties of UV-cured resin nanocomposites, thus promoting stereolithography 3D printing in the application of electrical and electronic fields.

Quantum metrology is being gradually studied for weak measurement systems. For weak measurement systems with thermal state pointer, we find that in the displacement space corresponding to imaginary weak values, the maximal quantum Fisher information (QFI) after the postselection for accepted event (Conversely, postselection for rejected event) can attain the level of thermal fluctuations, without surpassing total QFI, and that QFI which increases with increasing temperature can constantly improve the measurement precision. These results are much better than that of weak measurement with pure state (i.e., Gaussian state) pointer. On the other hand, in Kerr nonlinear interaction systems with weak measurement, and by using thermal state pointer, we obtain in the phase space the accepted postselection and the postselected measurement both achieve the Heisenberg limit of quantum metrology, and show weak measurement with thermal states only obtain classical Fisher information (CFI) which increases with increasing temperature and achieves classical enhanced scaling of N^{2}. Moreover, weak measurement with thermal states has an advantage over that with coherent states or mixed states of the light because generating these states with more large uncertainty are limited under the current technology, but thermal states with more large uncertainly are very easy to achieve with increasing temperature in nature, such as optical systems and optomechanical systems.

High pressure structural phase transition of monoclinic paraotwayite type α-Ni(OH)2 nanowires with a diameter of 15 nm–20 nm and a length of several micrometers were studied by synchrotron x-ray diffraction (XRD) and Raman spectra. It is found that the α-Ni(OH)2 nanowires experience an isostructural phase transition associated with the amorphization of the H-sublattice of hydroxide in the interlayer spaces of the two-dimensional crystal structure at 6.3 GPa–9.3 GPa. We suggest that the isostructural phase transition can be attributed to the amorphization of the H-sublattice. The bulk moduli for the low pressure phase and the high pressure phase are 41.2 (4.2) GPa and 94.4 (5.6) GPa, respectively. Both the pressure-induced isostructural phase transition and the amorphization of the H-sublattice in the α-Ni(OH)2 nanowires are reversible upon decompression. Our results show that the foreign anions intercalated between the α-Ni(OH)2 layers play important roles in their structural phase transition.

The carrier behavior in CuInS2 thin films at femtosecond and microsecond time scales is discussed in detail. Transient absorption data suggests that the photo-generated carriers relax rapidly accompanied by a change in energy. The photo-generated charge carriers are extracted by a bias electric field E in the nanosecond transient photocurrent system. An applied E improves the efficiency of photon conversion to charge carriers and enhances the velocity of the extracted charge carriers. In addition, there exists a threshold of illumination intensity in the extraction process of charge carriers in the CuInS2 thin film, above which carrier recombination occurs. The corresponding loss further increases with illumination intensity and the recombination rate is almost independent of E. Our results provide useful insights into the characteristics of carriers in the CuInS2 thin film and are important for the operation of optoelectronic devices realized with these films.

We demonstrated a mode-locked erbium doped fiber laser (EDFL) operating at 1558?nm by exploiting ferroferric-oxide nanoparticles (FONPs) as the saturable absorber (SA) material. FONPs, with an average diameter of ~20?nm, were prepared by a thermal decomposition method, then mixed with sodium carboxymethylcelluose to form an FONP film. The FONP SA was fabricated through a sandwiched FONP film between two fiber connectors. By inserting the FONPs SA into an EDFL cavity pumped by a 980?nm laser diode, stable passive mode-locking was achieved with a threshold pump power of ~120 mW. The obtained mode-locked laser had a central wavelength of ~1558?nm, a spectral bandwidth of ~0.8?nm, a pulse width of ~4.35 ns, and a repetition rate of ~37.32 MHz. Furthermore, a maximum average power of ~17 mW was obtained for a pump power of 340 mW. To the best of our knowledge, this is the first time that it has been demonstrated that FONPs can be used for constructing mode-locked fiber lasers.

Many P-wave mixing heavy-light 1+ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1+ states D 0, , , B 0, and B s are studied by the improved Bethe-Salpeter (B-S) method with two conditions of mixing angle θ: one is θ = 35.3°; the other is considering a correction to the mixing angle . Valuable predictions for the strong decay widths are obtained: , , , , , , , , and . It is found that the decay widths of and are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.

We report a dual-wavelength erbium-doped fiber laser (EDFL) with a tunable wavelength spacing from ~9 to 58 nm based on a single multimode interference filter (MMIF). The MMIF has a simple structure of single mode fiber (SMF)-multimode fiber-SMF and two main transmission peaks at 1537 and 1565 nm, which are located in the gain spectrum of the EDF. The wavelength spacings of these two transmission peaks were tuned from 7.8 to 58.5 nm, owing to the multimode interference effect by mechanically bending the MMIF. By adding the MMIF into the EDFL cavity, dual-wavelength lasers were obtained and the corresponding wavelength spacing was tuned from 9 to 58 nm by adjusting the MMIF. To the best of our knowledge, this is the first time an all fiber dual-wavelength EDFL with a tunable wavelength spacing using a curved MMIF has been reported.