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In a ZnO microcavity, the exciton-polariton effect with ultralarge Rabi splitting (can be as large as several hundreds of millielectron volts) may dominate the optical properties at the energies near the band edge. Due to the light-matter coupling, the renormalized energy states, i.e., the exciton-polariton states are expected to show very different dynamical behavior compared to the free exciton state. In this work, we used a femtosecond laser to pump a high-quality ZnO whispering gallery microcavity at room temperature. In the time-resolved photoluminescence measurements, we observed that both the fast and slow decay rates of the exciton-polaritons are faster than that of the free exciton due to the strong coupling between excitons and photons in a microcavity. The decay time constants are found to depend on the exciton-photon energy detuning (δ = E p h o t o n − E e x c i t o n ). [ABSTRACT FROM AUTHOR]

Engineering rock structures containing joints and fissures are frequently subjected to discontinuous periodic disturbances of varying amplitudes. To attain the quantitative relationship between the crack angle and the mechanical and deformation properties of rock under complex stress paths, uniaxial cyclic loading and unloading tests with increasing stress gradients were conducted on sandstone specimens containing a single crack of different angles. Our results showed that the bearing capacity of the sandstone increased as the crack angle increased. The irreversible strain and elastic moduli of the rock presented a sudden increase when entering the next cycle of the stepped loading. However, the entire loading process can be divided into three stages according to their respective trends. These three stages correspond to the three stages of rock deformation, i.e., the pore crack compaction stage, the elastic deformation to the stable micro-elastic crack development stage, and the unstable crack development stage. In addition, the crack angle of sandstone showed a negative correlation with the irreversible strain, but a positive correlation with the elastic modulus. With the increasing crack angle, the failure mode of the rock changed from the tensile-shear failure to the shear failure, and then to the interlayer dislocation failure. [ABSTRACT FROM AUTHOR]

The electrical conductivity of gabbroic melt with four different water contents (i.e. 0, 2.59 wt%, 5.92 wt% and 8.32 wt%) was measured at temperatures of 873–1373 K and pressures of 1.0–3.0 GPa using YJ–3000t multi‒anvil high−pressure apparatus and Solartron‒1260 impedance spectroscopy analyzer. At a fixed water content of 2.59 wt%, the electrical conductivity of the sample slightly decreased with increasing pressure at the temperature range of 873‒1373 K, and its corresponding activation energy and activation volume were determined as 0.87 ± 0.04 eV and ‒1.98 ± 0.02 cm3 mole–1, respectively. Under the certain conditions of 873‒1373 K and 1.0 GPa, the electrical conductivity of the gabbroic melts tends to gradually increase as the rise of water content from 0 to 8.32 wt%, and the activation enthalpy decreases from 0.93 eV to 0.63 eV, accordingly. Furthermore, the functional relation models for the electrical conductivity of gabbroic melts with the variations of temperature, pressure and water content were constructed at high‒temperature and high‒pressure conditions, respectively. In addition, the dependence relation of the electrical conductivity of melts with the degree of depolymerization was explored under conditions of four different water contents, 1373 K and 1.0 GPa, and three previously available reported results on those of representative calc‒alkaline igneous rock melts (i.e. dacitic melt, basaltic melt and andesitic melt) were detailedly compared. In comprehensive combination with our presently acquired electrical conductivity data of gabbroic melt with four different water contents and the available data of polycrystalline olivine, the electrical conductivity of gabbroic melt‒olivine system on the variation of volume percentage of anhydrous and hydrous melts was successfully constructed by virtue of the typical Hashin–Shtrikman upper bound model. In light of the electrical conductivity of gabbroic melt‒olivine system with the previous MT results, we find that the anhydrous and hydrous gabbroic melts can be employed to reasonably interpret the high conductivity anomalies in the Mohns ridge of the Arctic Ocean. [ABSTRACT FROM AUTHOR]

As(Ⅲ) is a highly toxic, mobile, and predominant arsenic species in anoxic groundwater.The removal of arsenic in contaminated water by using nanoscale iron particles has received extensive attention. The reduction potential and storage of Zn is lower and easier than that of Fe. Therefore, Zn is considered to be the best choice for the reduction of chlorinated organic compounds. To our knowledge, there is little research on the reduction of arsenic with nanoscale zinc in water. The objectives of this study were to investigate kinetics and impact factors by batch experiments. Pseudo-first-order, second-order kinetics and the intraparticle diffusion model were applied to simulate the sorption process. The sorption process was best fitted by the pseudo-second-order kinetic with reaction rate constants (k2) of 0.18 g/(mg·min). The adsorption capacity of nanoscale zinc for As(Ⅲ) was 0.47 mg/g. Chemical adsorption is the main mechanism of As(Ⅲ) removal by nanoscale zinc. The shaking time for optimum removal of As(Ⅲ) has been noted as 120 min for nanoscale zinc. The adsorbent dose for nanoscale zinc is 2.5 g/L. Maximum removal of As(Ⅲ) was observed in the pH range of 2-7. Over 99.5% As(Ⅲ) and As(Ⅴ) were removed within 120 min in an initial concentration of 0.565 g/L. These results suggest that nanoscale zinc particles can be used for treating As-affected groundwater that contains substantial As(Ⅲ) without preoxidation of As(Ⅲ) to As(Ⅴ). In comparison with traditional methods, the removal of As(Ⅲ) by nanoscale zinc is simple, inexpensive and has a high efficiency for application in water treatment facilities.

We are delighted to share with you our sixth Journal Club and highlight some of the most interesting papers published recently [...]

The layer-dependent properties are still unclarified in two-dimensional (2D) vertical heterostructures. In this study, we layer-by-layer deposited semimetal β-In2Se3 on monolayer MoS2 to form vertical β-In2Se3/MoS2 heterostructures by chemical vapor deposition. The defect-mediated nucleation mechanism induces β-In2Se3 nanosheets to grow on monolayer MoS2, and the layer number of stacked β-In2Se3 can be precisely regulated from 1 layer (L) to 13 L by prolonging the growth time. The β-In2Se3/MoS2 heterostructures reveal tunable type-II band alignment arrangement by altering the layer number of β-In2Se3, which optimizes the internal electron transfer. Meanwhile, the edge atomic structure of β-In2Se3 stacking on monolayer MoS2 shows the reconstruction derived from large lattice mismatch (∼ 29%), and the presence of β-In2Se3 also further increases the electrical conductivity of β-In2Se3/MoS2 heterostructures. Attributed to abundant layer-dependent edge active sites, edge reconstruction, improved hydrophilicity, and high electrical conductivity of β-In2Se3/MoS2 heterostructures, the edge of β-In2Se3/MoS2 heterostructures exhibits excellent electrocatalytic hydrogen evolution performance. Lower onset potential and smaller Tafel slope can be observed at the edge of monolayer MoS2 coupled with 13-L β-In2Se3. Hence, the outstanding conductive layers coupled with edge reconstruction in 2D vertical heterostructures play decisive roles in the optimization of electron energy levels and improvement of layer-dependent catalytic performance. [ABSTRACT FROM AUTHOR]

In the present work, considering the blocking effect of unpaired nucleons and the orbital angular momentum taken away by the emitted α particle, we put forward an improved Geiger-Nuttall law to calculate α -decay half-lives of heavy and superheavy nuclei. There are three adjustable parameters in this formula, whose values are obtained by fitting experimental α decay half-lives of 216 nuclei ranging from Z = 90 to Z = 118 with N ≥ 130 from the ground state and/or isomeric state. The calculated results are in good agreement with the experimental data. The corresponding root-mean-square (rms) are 0.301, 0.587 and 0.541 for 65 even–even, 116 odd-A and 35 odd–odd nuclei, respectively. For comparison, the Royer formula proposed by G. Royer [J. phys. G 26, 1149(2000)], Viola-Seaborg-Sobiczewski formula (VSS) proposed by A. Sobiczewski et al. [J. Inorg. Nucl. Chem 28, 741(1966)] and Sobiczewski-Parkhomenko formula (SP) proposed by A. Parkhomenko et al. [Acta. Phys. Pol. B 36, 3095(2005)] are also used. In addition, this improved formula is extended to predict α -decay half-lives for nuclei with Z = 117, 118, 119 and 120. The corresponding predictions of these formulae are basically consistent with each other. [ABSTRACT FROM AUTHOR]

This study aims to investigate the influence of length-to-diameter (L/D) ratio on the strain energy storage and evolution characteristics of rock materials during progressive rock failure under compression. Uniaxial compression tests and single-cycle loading–unloading uniaxial compression tests were conducted on four rock materials with two specimen L/D ratios. The uniaxial compressive strength (UCS) and peak strain of the rock specimens with L/D = 1 were significantly greater than those of the specimens with L/D = 2, thus exhibiting a strong size effect. In the single-cycle loading-unloading uniaxial compression tests, the total energy density, elastic energy density and dissipated energy density of the specimens with different L/D ratios increased nonlinearly with the actual stress level. The specimen L/D ratio had a significant impact on the nonlinear energy evolutions over various actual stress levels. Interestingly, regardless of the L/D ratio, failure pattern and type of material in the tests, highly linear relationships exist between the elastic energy, dissipated energy and total energy. Although the UCS is sensitive to the specimen L/D ratio, the energy storage coefficient (ESC) and energy dissipation coefficient (EDC) almost show a size-independent behaviour. The ESC and EDC are not affected by the L/D ratio and failure mode and can be used as physical parameters in geotechnical engineering design. [ABSTRACT FROM AUTHOR]