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We report the experimental realization of quantum degenerate Fermi gases of 87Sr atoms under controlled 10- and dual-nuclear-spin configurations. Based on laser cooling and evaporative cooling, we achieve an ultracold Fermi gas of 105 atoms equally distributed over 10 spin states, with a temperature of T/TF=0.21. We further prepare a dual-spin gas by optically pumping atoms to the mF=9/2 and mF=7/2 states and observe a slightly lower T/TF than that for a 10-spin gas under the same trapping condition, showing efficient evaporative cooling under a decreasing number N of spin states ( N ≥ 2 ) despite the increasing importance of Pauli exclusion. Given that rethermalization becomes less efficient with N approaching unity, we evaporatively cool an almost polarized gas to 130 nK. The simple and efficient preparation of ultracold Fermi gases of 87Sr with tunable spin configurations provides a first step towards engineering topological quantum systems.

Vickers hardness calculations of eleven wurtzite-structured semiconductors are performed based on the microscopic hardness model. All the parameters are obtained from first-principles calculations. There are two types of chemical bonds in wurtzite-structured crystals. The overlap populations of the two types of chemical bonds in lonsdaleite are chosen as Pc for wurtzite structure. The calculated bond ionicity values of the wurtzite-structured semiconductors are in good agreement with the ionicities from the dielectric definition. When the hardness of wurtzite-structured crystal is higher than 20GPa, our calculated Vickers hardness is within 10% accuracy. Therefore, the hardness of novel wurtzite-structured crystal could be estimated from first-principles calculations.

We investigate the traffic flow volume data on the time dependent activity of Beijing's urban road network. The couplings between the average flux and the fluctuations on individual links are shown to follow certain scaling laws and yield a wide variety of scaling exponents between 1/2 and 1. To quantitatively explain this interesting phenomenon, a non-stationary Poisson arriving model is proposed. The scaling property is interpreted as the result of the time-variation of the arriving rate of flux over the network, which nicely explicates the effect of aggregation windows, and provides a concise model for the dependence of scaling exponent on the external/internal force ratio.

Based on the hexagonal BN structure, six possible layered B2CN structures are constructed. Their total energies, lattice constants as well as electronic properties are calculated using the ab initio pseudopotential density functional method within the local density approximation. The calculated results show that the B2CN-V configuration with AA stacking sequence is the most stable among the six B2CN layered structures. The characteristics of electronic structures indicate that the B2CN-V shows metallicity, which mainly comes from -B1–C–B1–C- chains.

We investigate hexagonal BC2N in graphite unit cells using the first-principles method and calculate the total energies, lattice parameters, and electronic band structures after full relaxation. It is shown that stable hexagonal BC2N should be stacked sequentially with one graphite layer and one h-BN layer. The density of states indicates that this structure should have metallicity.

Electron cloud instability (ECI) may take place in a positron storage ring when the machine is operated with a multi-bunch positron beam. According to the actual shape of the vacuum chamber in the BEPCII, a programme which is different from the other simulation codes has been developed. Because of the distance between dipole magnet and sextupole, the quadrupole magnet of BEPCII is very short, much of the photoelectrons can be produced and can move in magnetic fields. The motion of electrons in various kinds of magnetic fields is studied in detail, especially for the solenoid field which will be wound in the vacuum pipe of BEPCII. Simulation shows that the solenoid field is very effective to confine the electrons to the vicinity of the vacuum chamber wall and to make an electron free region at the vacuum pipe Centre.

We found that the bacteriorhodopsin (bR) film has a special property of complementary suppression modulated transmission (CSMT). The yellow and the blue beams can be suppressed mutually when both the beams illuminate the bR film simultaneously. When the blue beam carrying an image with a bright-background noise illuminates on the bR film and then a yellow beam with uniform intensity distribution illuminates the same area, the bright-background can be removed due to the CSMT. In our demonstration, the pattern model is letters ``VLSI'' with ground noise of small words and the ground noise is removed from the pattern by the new optical filter.

A chemical reaction for the preparation of B–C–N compounds by using carbon tetrachloride (CCl4), boron tribromide (BBr3), lithium nitride (Li3N) and sodium as reactants has been carried out at the temperature of 400°C. Measurements of FTIR, XRD, TEM and EELS show that two kinds of compounds have been formed in the prepared sample. One is hollow sphere-like C–N with an amorphous structure; the other is piece-like polycrystalline B–C–N with the hexagonal structure. Their determined compositions are close to C3N and BC2N, respectively.

B2CN precursor is prepared by a mechanical vibration-milling process using amorphous boron, graphite and h-BN powders with mole ratio of 1:1:1. A mixture of precursor and Ca3B2N4 catalyst is treated under high pressure and high temperature. A boron rich cubic B(CxN1−x) phase is obtained after removing the catalyst by acid treatment. The average C content of the boron-rich cubic phase is about 6 at.% detected by energy-dispersive x-ray analysis spectroscopy. It is found that the highest carbon content in the cubic phase is as large as 16 at.%.

We present an experimental method to obtain neutral beam injection (NBI) power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission efficiency, the neutralization efficiency and so on. With the empirical scaling laws, the estimating power can be obtained in every shot of experiment on time, therefore the important parameters such as the energy confinement time can be obtained precisely. The simulation results by the tokamak simulation code (TSC) show that the evolution of the plasma parameters is in good agreement with the experimental results by using the NBI power from the empirical scaling law.

In this paper, the modulated transmission property of bacteriorhodopsin (bR) film is analyzed theoretically when two beams of light, yellow light and purple light, illuminate the bR film simultaneously. By using the transmission property of bR film, the winner-take-all thresholding operation can be realized.

We perform first-principles calculations for ZnO thin films with oxygen vacancy defects. The densities of states, partial atomic densities of states, charge density differences and atomic populations are presented. We show that the SET process, i.e., from a high resistive state to a low resistive state, is attributable to the aggregation and regular arrangement of the oxygen vacancies, which causes the formation of conductive filaments and leads to the low resistive state of the system.

We investigate the photoluminescence (PL) emission from InGaN/GaN multiple quantum-well structures before and after 1 MeV electron irradiation. The PL peak intensity exhibits a slight enhancement after low-dose electron irradiation (2 x 10(13) e/cm(2)), and then decreases with the cumulative electron dose. Meanwhile, the full width at half maximum of the PL spectrum narrows after low-dose electron irradiation and widens when the irradiation dose is relatively high. With respect to the yellow photoluminescence, there is no significant change until the electron fluence has accumulated up to 10(14) e/cm(2).

HCSB-DEMO concept design is carried out at SWIP. In order to handle power from a core plasma region, a super-X divertor is preliminarily designed and investigated for HCSB-DEMO. It increases the target surface area by expanding the magnetic flux surface with another X-point generated near the targets and increases the parallel connection length by moving the outer divertor target to larger R and Z. The heat load at the targets is investigated by B2.5-Eirene. With heating power flowing into SOL/divertor regions being P = 600 MW, when the density at the separatrix is ne = 3.5 × 1019 m−3, the peak heat load at the inner and outer divertor is 9.2 MW/m2 and 3.7 MW/m2, respectively, which is much less than those of the standard divertor without impurity seeding, and also below the design targets (10 MW/m2). Thus the super-X divertor may work well for HCSB-DEMO to solve the high heat load problem at the divertor target without impurity seeding from this preliminary concept design and simulation.

To verify the influence of the functional elements particular size for the radiation attenuation coefficients and mechanical properties radiation shielding material based on epoxy resin, we prepare two WO3/E44 samples with different particular sizes of WO3 by a solidified forming approach. The linear attenuation coefficients of these samples are measured for γ-ray photo energies of 59.6, 121.8, and 344.1 keV, etc. using narrow beam transmission geometry. It is found that the linear attenuation coefficients would increase with the decreasing particle size of the WO3 in the epoxy resin based radiation shielding material. The theoretical values of the linear attenuation coefficients and mass attenuation are calculated using WinXcom, and good agreements between the experimental data and the theoretical values are observed. From the studies of the obtained results, it is reported that from the shielding point of view the nano-WO3 is more effective than micro-WO3 in the epoxy resin based radiation shielding material.

Phosphorus-doped ZnO (ZnO:P) thin films are deposited on a c-plane sapphire in oxygen at 350°C, 450°C, 550°C and 650°C, respectively, by pulsed laser deposition (PLD), then all the ZnO:P samples are annealed at 650°C in oxygen with a pressure of 1 × 105 Pa. X-ray diffraction measurements indicate that the crystalline quality of the ZnO:P thin films is improved with the increasing substrate temperature from 350°C to 550°C. With a further increase of the deposition temperature, the crystalline quality of the ZnO:P sample is degraded. The measurements of low-temperature photoluminescence spectra demonstrate that the samples deposited at the substrate temperatures of 350°C and 450°C show a strong acceptor-bound exciton (A°X) emission. The electrical properties of ZnO:P films strongly depend on the deposition temperature. The ZnO:P samples deposited at 350°C and 450°C exhibit p-type conductivity. The p-type ZnO:P film deposited at 450°C shows a resistivity of 1.846 Ωcm and a relatively high hole concentration of 5.100 × 1017 cm−3 at room temperature.

The electron cloud accumulated in the vicinity of positron beam generates longitudinal electric field during the passage of bunch. The longitudinal interaction between bunch and electron cloud can lead to the distortion of the bunch shape. We use a simple analytic formula to calculate the longitudinal electric field due to electron cloud. Based on the longitudinal wake field, the macro-particle tracking method is used to simulate the variation of bunch longitudinal profile in different electron cloud densities and the simulation also shows that the synchrotron oscillation tune is slightly shifted by the wake field. By comparing the simulation results and the analytical estimation from potential distortion theory, the longitudinal wake field from electron cloud can be seen as a potential well effect.

A pressure-induced phase transition and stability in Si2CN4 polymorphs under high pressure are studied by first-principles calculations. The result shows that the phase transition pressure of α- and β-Si2CN4 to the cubic spinal phase is 29.9 GPa and 27.5 GPa predicted by thermodynamic method respectively. Under ambient condition, all of the three Si2CN4 polymorphs are metastable with positive formation enthalpy. Unlike the stability of Si3N4 polymorphs, α-Si2CN4 is more stable than the β phase.