[en] Concentrations of indoor and outdoor radon and its daughters in Liaoning region were measured using scintillation and two-filter methods. The distributions are approximately log-normal with 95 per cent of dwellings having radon levels less than 50 Bq·m^-3. The annual average of indoor and outdoor radon concentrations are 29.6 and 9.7 Bq·m^-3, respectively, their geometric means being 19.0 and 7.5 Bq·m^-3, respectively. With the application of an equilibrium factor of 0.49 to indoor radon and that of 0.61 to outdoor radon, the equilibrium equivalent concentrations of radon are calculated to be 14.5 and 5.9 Bq·m^-3, respectively. Adopting the dose conversion factors proposed by ICRP in its Publication No. 50, the calculated annual total effective dose equivalent is 1.16 mSv, including the contribution both from outdoor and indoor exposures

[en] This paper presents the course of analyzing abnormal improvement in particulate contamination of lubricating oil of the operating Turbine Unit 1 of Qinshan II, via various measures of oil analysis and method of exclusion. The scope of causes for the abnormal particulate contamination improvement is narrowed down to external pollution. Therefore the direction of solving the problems is identified. (authors)

[en] Properties of plasmon excitations in two-dimensional (2D) atomic cluster systems are theoretically studied within an extended Hubbard model. The collective oscillation equations of charge, plasmon eigen-equations and the energy-absorption spectrum formula are presented. The calculated results show that different symmetries of plasmons exist in the cluster systems, and the symmetry of charge distribution in the plasmon resonance originate from the intrinsic symmetry of the corresponding eigen-plasmon modes, but not from the symmetry of applied external fields; however, the plasmon excitation with a certain polarization direction should be excited by the field in this direction, the dipole mode of plasmons can be excited by both uniform and non-uniform fields, but multipole ones cannot be excited by an uniform field. In addition, we show that for a given electron density, plasmon spectra are red-shifted with increasing size of the systems.

[en] A zero-crossing dynamic speckle method is proposed to determine the velocities of nanoparticles in nanofluids. A Gaussian laser beam is used to illuminate nanofluids in a pipe, and the dynamic speckles are detected by a spatially integrating detector with an aperture. The integrated speckle intensity signal is processed by a computer and the zero-crossing rate is counted. The velocity of the nanoparticles can be determined from its relationship to zero-crossing rate. The results show that the nanoparticles exhibit features of flowing nanofluids, and when the average velocity of the nanofluids is 53.4 mm/s, the average velocity of the nanoparticles is 51.8 ± 5.1 mm/s. (authors)

[en] Using the nonlocal conductivity based on quantum response theory, we study the optical properties of p-polarized wave in quartz–metal–film–air structures, especially the influence of nonlocal effect on the surface plasmon polaritons (SPPs) resonance. In absorption spectrum, the resonant peak of SPP is found, and the dependence of the resonant peak on film thickness shows that nonlocal effect in the SPP resonance is enhanced significantly with the decrease of film-thickness, especially in the less than 20 nm metal film. We calculate the surface charge density as a function of frequency, and find that the frequencies at the charge and absorption peaks are the same. This clearly confirms that the absorption peak stems from SPP resonance excitation, and SPPs absorb the energy of the electromagnetic wave via charge oscillations. In the case of SPP resonance, the charge and electric field on the down-surface of thin film are always greater than that on the up-surface; however, the situation is just opposite in the case of no SPP resonance. This implies that the SPP resonance occurs near the down-surface of the film. Moreover, due to the nonlocal response of electric current to the electric field, the energy flow and electric current show anomalous oscillations, and with the increase of film thickness the anomalous oscillations exhibit obvious attenuation

[en] Highlights: • Electrolyte based on fluorinated ether of ETFE is used in Li/S battery. • ETFE improves cycling, rate and self-discharging performances of Li/S battery. • Surface film on Li anode modified by ETFE inhibits the shuttle of polysulfides. - Abstract: Fluorinated ether of ethyl 1,1,2,2-tetrafluoroethyl ether (ETFE) was selected as electrolyte solvent for lithium/sulfur battery, and the influence of ETFE in electrolyte on cell properties was first investigated. The enhanced stability of electrolyte/anode interface and improved electrochemical performances (cycling, rate and self-discharging) of the Li/S cell are presented by using ETFE-containing electrolyte, especially for complete replacement of tetraethylene glycol dimethyl ether (TEGDME) by ETFE in combine with 1,3-dioxolane (DOL). It is found that ETFE plays a key role in modifying the surface composition and structure of the metallic Li, forming a strengthened protective film on the anode during cycling. Besides, ETFE is considered to decrease the dissolution of polysulfides in the electrolyte. These factors together restrict the contact and reaction between polysulfides and Li anode

[en] The rapid dendritic growth of primary Ni₃Sn phase in undercooled Ni-30.9%Sn-5%Ge alloy is investigated by using the glass fluxing technique. The dendritic growth velocity of Ni₃Sn compound is measured as a function of undercooling, and a velocity of 2.47 m/s is achieved at the maximum undercooling of 251 K (0.17T_L). The addition of the Ge element reduces its growth velocity as compared with the binary Ni₇₅Sn₂₅ alloy. During rapid solidification, the Ni₃Sn compound behaves like a normal solid solution and it displays a morphological transition of 'coarse dendrite–equiaxed grain–vermicular structure' with the increase of undercooling. Significant solute trapping of Ge atoms occurs in the whole undercooling range. (cross-disciplinary physics and related areas of science and technology)

[en] Ce substitution can not only make Ce³⁺ doped into the crystal lattice, but stabilize the bulk structure by means of robust Ce-O bond, and form ceria coating layer at outer surface to protect matrix material. The influence of different Ce content on atomic occupation, lattice parameters and Li⁺/Ni²⁺ mixing extent were studied at length by Rietveld refinement. Profiting from the synergistic effect of lithium defects in ceria and enlarged crystal plane spacing, Ce 0.15%-NCM has superior electrochemical performance. Cycled at 5 C, Ce 0.15%-NCM has superior initial discharge capacity of 138.7 mAhg⁻¹ and capacity retention of 83.99% after 200 cycles. So far as to the full-cells state, Ce 0.15%-NCM delivers the initial energy density of 406 Wh kg⁻¹ and 72.94% retention after 200 cycles. Combined with the results of HRTEM and EDS spectrum, the cycled electrodes were investigated, and the mechanism of Ce modification at high potential cycling was further studied.

[en] For multilayer sandstone uranium deposit, two or more filter layers have to be constructed in order to implement different mining process for each layer in one drilling hole. According to the character of multilayer sandstone uranium deposit, on the basis of gravel-filling hole structure construction technology, layered gravel-filling hole technology is employed to construct two filter layers by man-made aquifuge in one time. The practice shows that the method of using layered gravel-filling hole structure to construct filter layers for each aquifer has the advantages of simple operation, short construction period, once-through well construction and low drilling hole cost. (authors)

[en] Highlights: • Methanogenesis plays an important role in phenanthrene elimination in paddy soil. • The role of microbial community structure in PAH degradation is reconfirmed. • Microbial co-occurrence is crucial for PAH elimination under methanogenesis. • Remediation of PAH-contaminated soil via methanogenesis is a promising measure. Although polycyclic aromatic hydrocarbons (PAHs) degradation under methanogenesis is an ideal approach to remediating PAH-polluted soil, the contribution of methanogenesis to soil PAH elimination and the relationships between microbial ecological characteristics and PAH degradation during this process remain unclear. Here, we conducted a short-term (60 days) incubation using a paddy soil amended with phenanthrene and examined the effects of a specific methanogenic inhibitor (2-bromoethanesulfonate, BES) on this process. As treatment assessments, the methane production activity (MPA), phenanthrene degradation rate (PDR), and microbial ecological characteristics were determined. The results indicated that BES significantly inhibited both soil MPA and PDR, and we detected a positive relationship between MPA and PDR. Furthermore, BES significantly altered the soil microbial community structure, and it was the microbial community structure but not α-diversity was significantly correlated with soil MPA and PDR. BES decentralized the co-occurrence of bacterial genera but intensified the co-occurrence of methanogens. Moreover, certain bacterial taxa, including Bacteroidetes-vadinHA17, Gemmatimonas, and Sporomusaceae, were responsible for the MPA and PDR in this paddy soil. Collectively, these findings confirm the role of methanogenesis in PAH elimination from paddy soil, and reveal the importance of microbial co-occurrence characteristics in the determination of soil MPA and pollutant metabolism.