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<jats:p>Unveiling the thermal transport properties of various one-dimensional (1D) or quasi-1D materials like nanowires, nanotubes, and nanorods is of great importance both theoretically and experimentally. The dimension or size dependence of thermal conductivity is crucial in understanding the phonon–phonon interaction in the low-dimensional systems. In this paper, we experimentally investigate the size-dependent thermal conductivity of individual single crystalline <jats:italic>α</jats:italic>-Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> nanowires collaborating the suspended thermal bridge method and the focused electron-beam self-heating technique, with the sample diameter (<jats:italic>d</jats:italic>) ranging from 180 nm to 661 nm and length (<jats:italic>L</jats:italic>) changing from 4.84 μm to 20.73 μm. An empirical relationship for diameter-/length-dependent thermal conductivity is obtained, which shows an approximately linear dependence on the aspect ratio (<jats:italic>L</jats:italic>/(1 + <jats:italic>Cd</jats:italic>)) at <jats:italic>T</jats:italic> = 300 K, where <jats:italic>C</jats:italic> is a fitting parameter. This is related to the boundary scattering and diameter effect of <jats:italic>α</jats:italic>-Fe<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> nanowires although rigorous calculations are needed to confirm the result.</jats:p>

<jats:p>Exit choice is one of the most important pedestrian behaviors during evacuation. Distance to the exit is a generally recognized factor influencing expected moving time to the exit. Visual range determines how much information a pedestrian can perceive, thus the number of pedestrians within the visual field can be used to estimate waiting time at the exit. Besides, the choice firmness that reflects the degree to which a pedestrian would persist in his/her previous choice of exit is proposed. By integrating game theory into a cellular automata simulation framework, the pedestrian exit choice mechanism is investigated and explicitly modeled in this paper. A systematic analysis of the key factors influencing pedestrian evacuation is conducted, including visual radius and choice firmness of a pedestrian, initial crowd distribution of the room, exit layout as well as exit width. It is found that low choice firmness level can lead to unnatural pedestrian behavior such as wandering, which is adverse to evacuation. The longer the pedestrian’s visual radius, the earlier the pedestrian can determine his/her final selection of the exit. Compared with the scenario where the pedestrians are randomly distributed, pedestrians clustered together in a corner of the room lead to high crowd density and imbalanced use of exits. Furthermore, the exit layout and exit width also have a certain influence on pedestrian evacuation process. The results of this paper may be of benefit to the formulation of behavioral rules in other pedestrian simulation models.</jats:p>

<jats:p>As the mesoscale eddies in oceans and semi-enclosed seas are significant in horizontal dispersion of pollutants, we investigate the seasonal variations of these eddies in the Persian Gulf (PG) that are usually generated due to seasonal winds and baroclinic instability. The sea surface height (SSH) data from 2010 to 2014 of AVISO are used to identify and track eddies, using the SSH-based method. Then seasonal horizontal dispersion coefficients are estimated for the PG, using the properties of eddies. The results show an annual mean of 78 eddies with a minimum lifetime of one week. Most of the eddies are predominantly cyclonic (59.1%) and have longer lifetimes and higher diffusion coefficients than the anti-cyclonic eddies. The eddy activity is higher in warm seasons, compared to that of cold seasons. As locations with high eddy diffusion coefficients are high-risk areas by using maps of horizontal eddy diffusion coefficients, perilous times and locations of the release of pollutants are specified to be within the longitude from 51.38°E to 55.28°E. The mentioned areas are located from the Strait of Hormuz towards the northeast of the PG, closer to Iranian coast. Moreover, July can be considered as the most dangerous time of pollution release.</jats:p>

<jats:p>We experimentally observed properties of liquid film breakup for shock-wave-initiated disturbances in air at normal temperature and pressure. The tested liquids include water and various glycerol mixtures. High speed camera and multiple-spark high speed camera were utilized to record the process of liquid film breakup. A phase Doppler particle analyzer was also used to record droplet size and velocity. The experimental results show that liquid viscosity plays a vital role in the deformation, breakup and atomization of liquid films. After the interaction of shock waves, the droplet size of various glycerol mixtures is significantly smaller than either water or glycerol. Richtmyer–Meshkov instability is an important factor in the breakup and atomization of liquid films induced by shock waves. Furthermore, a dispersal model is established to study breakup mechanisms of liquid films. The correlation between droplet size and velocity is revealed quantitatively. The research results may provide improved understanding of breakup mechanisms of liquid films, and have important implications for many fields, especially for heterogeneous detonations of gas/liquid mixtures.</jats:p>

<jats:p>The equation of state (EOS) of Cr<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub> at high pressure is studied by the synchrotron radiation x-ray diffraction (XRD) in a diamond anvil cell (DAC) at ambient temperature, and density functional theory (DFT). The XRD analysis shows that the orthorhombic structure is maintained to a maximum pressure of 44.5 GPa. The XRD data show that the bulk modulus is <jats:italic>K</jats:italic> <jats:sub>0</jats:sub> = 292 (18) GPa with <jats:inline-formula> <jats:tex-math> <?CDATA ${K}_{0}^{^{\prime} }=3.25(0.85)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>K</mml:mi> <mml:mn>0</mml:mn> <mml:mo>′</mml:mo> </mml:msubsup> <mml:mo>=</mml:mo> <mml:mn>3.25</mml:mn> <mml:mo stretchy="false">(</mml:mo> <mml:mn>0.85</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_29_8_086401_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>. In addition, the high-pressure compression behavior of Cr<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub> is studied by first principles calculations. The obtained bulk modulus of Cr<jats:sub>3</jats:sub>C<jats:sub>2</jats:sub> is 323 (1) GPa.</jats:p>

<jats:p>A relationship between thermal effects and relaxation of the high-frequency shear modulus upon heat treatment of bulk Zr<jats:sub>48</jats:sub>(Cu<jats:sub>5/6</jats:sub>Ag<jats:sub>1/6</jats:sub>)<jats:sub>44</jats:sub>Al<jats:sub>8</jats:sub> metallic glass is found. This relationship is attributed to the relaxation of a interstitial-type defect system frozen-in from the melt upon glass production. Calorimetric data show that thermal effects occurring on heating include heat release below the glass transition temperature, heat absorption above it and heat release caused by crystallization. The equation derived within the Interstitialcy theory can be used to calculate the shear modulus relaxation using the calorimetric data. The obtained results are used to trace the defect concentration as functions of temperature and thermal prehistory.</jats:p>

<jats:p>Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxides but little is known about their effect on thermal expansion. Herein we report the effect of oxygen defects on the structure formation and thermal expansion properties of the layered perovskite Ca<jats:sub>2</jats:sub>RuO<jats:sub>4</jats:sub> (CRO). It is shown that the CRO containing excess oxygen crystallizes in a metallic <jats:italic>L</jats:italic>-CRO phase without structure transition from 100 K to 500 K and displays a normal thermal expansion behavior, whereas those with oxygen vacancies adopt at room temperature an insulating <jats:italic>S</jats:italic>-CRO phase and exhibit an enormous negative thermal expansion (NTE) from 100 K to about 360 K, from where they undergo a structure transition to a high temperature metallic <jats:italic>L</jats:italic>-CRO phase. Compared to the <jats:italic>L</jats:italic>-CRO containing excess oxygen, the <jats:italic>S</jats:italic>-CRO structure has increasingly large orthorhombic strain and distinctive in-plane distortion upon cooling. The in-plane distortion of the RuO<jats:sub>6</jats:sub> octahedra reaches a maximum across 260 K and then relaxes monotonically, providing a structure evidence for the appearance of an antiferromagnetic orbital ordering in the paramagnetic phase and the <jats:italic>A<jats:sub>g</jats:sub> </jats:italic> phonon mode suppression and phase flip across the same temperature found recently. Both the <jats:italic>L</jats:italic>- and <jats:italic>S</jats:italic>-CRO display an antiferromagnetic ordering at about 150–110 K, with ferromagnetic ordering components at lower temperature. The NTE in <jats:italic>S</jats:italic>-CRO is a result of a complex interplay among the spin, orbital, and lattice.</jats:p>

<jats:p>The ultra-low thermal conductivity of roughened silicon nanowires (SiNWs) can not be explained by the classical phonon–surface scattering mechanism. Although there have been several efforts at developing theories of phonon–surface scattering to interpret it, but the underlying reason is still debatable. We consider that the bond order loss and correlative bond hardening on the surface of roughened SiNWs will deeply influence the thermal transport because of their ultra-high surface-to-volume ratio. By combining this mechanism with the phonon Boltzmann transport equation, we explicate that the suppression of high-frequency phonons results in the obvious reduction of thermal conductivity of roughened SiNWs. Moreover, we verify that the roughness amplitude has more remarkable influence on thermal conductivity of SiNWs than the roughness correlation length, and the surface-to-volume ratio is a nearly universal gauge for thermal conductivity of roughened SiNWs.</jats:p>

<jats:p>Point and line defects are of vital importance to the physical and chemical properties of certain two-dimensional (2D) materials. Although electron beams have been demonstrated to be capable of creating single- and multi-atom defects in 2D materials, the products are often random and difficult to predict without theoretical inputs. In this study, the thermal motion of atoms and electron incident angle were additionally considered to study the vacancy evolution in a black phosphorus (BP) monolayer by using an improved first-principles molecular dynamics method. The P atoms in monolayer BP tend to be struck away one by one under an electron beam within the displacement threshold energy range of 8.55–8.79 eV, which ultimately induces the formation of a zigzag-like chain vacancy. The chain vacancy is a thermodynamically metastable state and is difficult to obtain by conventional synthesis methods because the vacancy formation energy of 0.79 eV/edge atom is higher than the typical energy in monolayer BP. Covalent-like quasi-bonds and a charge density wave are formed along the chain vacancy, exhibiting rich electronic properties. This work proposes a theoretical protocol for simulating a complete elastic collision process of electron beams with 2D layers and will facilitate the establishment of detailed theoretical guidelines for experiments on 2D material etching using focused high-energy electron beams.</jats:p>

<jats:p>The electronic structures, magnetic properties, and martensitic transformation in all-d-metal Heusler-like alloys Cd<jats:sub>2</jats:sub>Mn<jats:italic>TM</jats:italic> (<jats:italic>TM</jats:italic> = Fe, Ni, Cu) were investigated by the first-principles calculations based on density-functional theory. The results indicate that all three alloys are stabilized in the ferromagnetic L2<jats:sub>1</jats:sub>-type structure. The total magnetic moments mainly come from Mn and Fe atoms for Cd<jats:sub>2</jats:sub>MnFe, whereas, only from Mn atoms for Cd<jats:sub>2</jats:sub>MnNi and Cd<jats:sub>2</jats:sub>MnCu. The magnetic moment at equilibrium lattice constant of Cd<jats:sub>2</jats:sub>MnFe (6.36 <jats:italic>μ</jats:italic> <jats:sub>B</jats:sub>) is obviously larger than that of Cd<jats:sub>2</jats:sub>MnNi (3.95 <jats:italic>μ</jats:italic> <jats:sub>B</jats:sub>) and Cd<jats:sub>2</jats:sub>MnCu (3.82 <jats:italic>μ</jats:italic> <jats:sub>B</jats:sub>). The large negative energy differences (Δ<jats:italic>E</jats:italic>) between martensite and austenite in Cd<jats:sub>2</jats:sub>MnFe and Cd<jats:sub>2</jats:sub>MnNi under tetragonal distortion and different uniform strains indicate the possible occurrence of ferromagnetic martensitic transformation (FMMT). The minimum total energies in martensitic phase are located with the <jats:italic>c</jats:italic>/<jats:italic>a</jats:italic> ratios of 1.41 and 1.33 for Cd<jats:sub>2</jats:sub>MnFe and Cd<jats:sub>2</jats:sub>MnNi, respectively. The total moments in martensitic state still maintain large values compared with those in cubic state. The study is useful to find the new all-d-metal Heusler alloys with FMMT.</jats:p>