[en] The structural and thermodynamic properties of intermetallic compounds Co₂Zr and Co₂Ti are calculated by first principle calculations with ab initio plane-wave pseudopotential density functional theory (PWPDFT) and the generalized gradient approximation (GGA) under high temperature and pressure. Co₂Zr and Co₂Ti are both cubic crystals with Cu₂Mg type structure. The results calculated are consistent with the experimental data. The thermodynamic properties are calculated in the quasi-harmonic Debye model. In the range of 0 ∼ 100 GPa pressure and 0 ∼ 1500 K temperature, the Debye temperature Θ, the heat capacity C_V and the thermal expansion α vary with pressure and temperature. The Debye temperature increases monotonically as the pressure increases. Besides, Co₂Ti has a higher Debye temperature than Co₂Zr under the same pressure. Both the heat capacity C_V and the thermal expansion α increase with increasing temperature whereas decrease with increasing pressure, which illustrates decreasing temperature and increasing pressure have the same effects on C_V and α. (authors)

[en] The nonlocal beam theories are widely used to study the mechanics of cylindrical nanotubes (NTs). The one-dimensional models however are unable to account for the nonlocal effect in the circumferential direction, which may substantially affect the applicability of the nonlocal beam models. To address the issue this letter examines the circumferential nonlocal effect (CNE) on the buckling and vibration of the NTs. Here the CNE is characterized by the difference between the nonlocal beam model considering the axial nonlocal effect only and the nonlocal shell model with both axial and circumferential nonlocal effects. The aspect ratio and radius-dependence of the CNE are calculated for the singlewall carbon NTs selected as a typical example. The results show that the CNE is substantial for the buckling and vibration of the NTs with small radius (e.g., <1 nm) and aspect ratio (e.g., <15). It however decreases with the rising radius and the aspect ratio, and turns out to be small for relatively wide and long NTs. The nonlocal beam theories thus may overestimate the buckling load and vibration frequency for the thin and short NTs. - Highlights: • First revealed the substantial circumferential nonlocal effect (CNE) on nanotube buckling. • Achieved radius/aspect ratio-dependence of CNE on nanotube buckling and vibration. • Located the range of applicability of the nonlocal beam theory without CNE.

[en] Highlights: • A CMRT method for coherent energy transfer in molecular aggregates was developed. • Applicability of the method was verified in two-site systems with various parameters. • CMRT accurately describes population dynamics in the FMO-complex. • The method is accurate in a large parameter space and computationally efficient. - Abstract: Excitation energy transfer (EET) is crucial in photosynthetic light harvesting, and quantum coherence has been recently proven to be a ubiquitous phenomenon in photosynthetic EET. In this work, we derive a coherent modified Redfield theory (CMRT) that generalizes the modified Redfield theory to treat coherence dynamics. We apply the CMRT method to simulate the EET in a dimer system and compare the results with those obtained from numerically exact path integral calculations. The comparison shows that CMRT provides excellent computational efficiency and accuracy within a large EET parameter space. Furthermore, we simulate the EET dynamics in the FMO complex at 77 K using CMRT. The results show pronounced non-Markovian effects and long-lasting coherences in the ultrafast EET, in excellent agreement with calculations using the hierarchy equation of motion approach. In summary, we have successfully developed a simple yet powerful framework for coherent EET dynamics in photosynthetic systems and organic materials

[en] Using a vacuum ultraviolet spectrometer and P-terphenyl, scintillator, the relative intensities of emitted lines of CV 40.2/40.7 A, etc. have been measured on a θ-pinch device, and electron temperature of the hydrogen plasma as a function of time is determined from the intensity ratio of these lines. The electron temperature is about 35 eV at the peak of the second half cycle of the discharge

[en] Patients are exposed to both the internal radiation from radiopharmaceutical and the external radiation from the X-rays during PET/CT examination. Estimating patients' radiation dose from whole body PET/CT examination could eliminate their apprehension and give clinical physicians guidance about whether the patients need to perform PET/CT examination. The calculation methods, influencing factors, cancer risk of PET/CT imaging and how to reduce the radiation dose are reviewed in this paper. (authors)

[en] Considerable effort has been devoted over the last decade to the development of extreme ultraviolet (EUV) light sources for nanolithography. The 13.5 nm wavelength was imposed by industrial standards due to the availability of high-reflectivity Mo/Si multilayer mirrors so that a resolution of 32 nm can be attained. Xenon and tin are considered to be the best candidates for EUV light sources. In this review we first briefly introduce the concepts and principle of EUV lithography, and then discuss recent progress in both experimental and theoretical research on laser produced and gas discharge produced plasma light sources, with emphasis on the emission and absorption properties of xenon and tin plasmas. Theoretical studies show that statistical physical model are not yet able to predict the exact absorption and emission spectra of EUV plasmas. It is imperative that a detailed energy level model be developed to obtain accurate optical parameters to guide experimental design and to improve EUV conversion efficiency. (authors)

[en] Objective: To explore a rapid method of calculating an equivalent square field for irregular photon beam fields. Methods: Irregular photon fields can be divided into two types: the fields symmetric to the beam central axis and the fields dissymmetric to the beam central axis. Each type contains three conditions (i. e. R>1, R=1, R<1) according to the perimeter ratios of the irregular fields to the original fields. To choose 6 irregular fields and measure the absorption doses. Then work out the equivalent square field of each of the 6 irregular fields by means of A, B and C. Finally compare the prescription doses and those measured. Results: In the condition R>1, method B worked precisely. In the condition R=1, method A and method C worked rather precisely, while method B meet the accuracy demand. In the condition R>1, method A, B and C worked precisely and consistently. Conclusion: Method B can be recommended for clinical use, for it is convenient for standardized operations and meets the accuracy demand. (authors)

[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] As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near underground waste emplacement drifts. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower post-closure temperature, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses are currently being resolved. Good agreement in the basic thermal-mechanical responses was also achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglect complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level

[en] Aerosol-phase humic-like substances (HULIS) have received increasingly attention due to their universal ambient presence, active participation in atmospheric chemistry and important environmental and health effects. In last decade, intensive field works have promoted development of quantification and analysis method, unearthed spatio-temporal variation, and proved evidence for source identification of HULIS. These important developments were summarized in this review to provide a global perspective of HULIS. The diverse operational HULIS definitions were gradually focused onto several versions. Although found globally in Europe, Asia, Australasia and North America, HULIS are far more typical in continental and near-ground aerosols. HULIS concentrations varied from <1 μg/m³ to >13 μg/m³, with their carbon fraction making up 9%–72% of water soluble organic carbon. Dominant HULIS source was suggested as secondary processes and biomass burning, with the detailed formation pathways suggested and verified in laboratory works. -- Highlights: •Diverse operational definitions of HULIS were found to focus on several specific versions of definitions. •The global map of presence and abundance of HULIS was shown. •Size distribution and spatial-temporal variation of HULIS were summarized. •Dominant HULIS sources were recognized as biomass burning and secondary reactions. •Detailed formation pathways of HULIS were categorized. -- This review summarized important developments in measurement of aerosol-phase humic-like substances in the last decade