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<jats:p>The effects of 400 keV helium ion irradiation dose and temperature on the microstructure of the Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> ceramic were systematically investigated by grazing incidence x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The helium irradiation experiments were performed at both room temperature (RT) and 500 °C with a fluence up to 2.0 ×10<jats:sup>17</jats:sup> He<jats:sup>+</jats:sup>/cm<jats:sup>2</jats:sup> that resulted in a maximum damage of 9.6 displacements per atom. Our results demonstrate that He irradiations produce a large number of nanometer defects in Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> lattice and then cause the dissociation of Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> to TiC nano-grains with the increasing He fluence. Irradiation induced cell volume swelling of Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> at RT is slightly higher than that at 500 °C, suggesting that Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> is more suitable for use in a high temperature environment. The temperature dependence of cell parameter evolution and the aggregation of He bubbles in Ti<jats:sub>3</jats:sub>SiC<jats:sub>2</jats:sub> are different from those in Ti<jats:sub>3</jats:sub>AlC<jats:sub>2</jats:sub>. The formation of defects and He bubbles at the projected depth would induce the degradation of mechanical performance.</jats:p>

<jats:p>A dualband terahertz (THz) absorber including periodically distributed cross-shaped graphene arrays and a gold layer spaced by a thin dielectric layer is investigated. Numerical results reveal that the THz absorber displays two perfect absorption peaks. To elucidate the resonant behavior, the LC model is introduced to fit the spectra. Moreover, the strength and linewidth of the absorption peak can be effectively tuned with structural parameters and the relaxation time of graphene. Owing to its rotational symmetry, this THz absorber exhibits polarization insensitivity. Our designed absorber is a promising candidate in applications of tunable optical sensors and optical filters.</jats:p>

<jats:p>This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the single-event transient (SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor (SiGe HBT). The ion-induced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design (TCAD) simulation. The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected. With a proton fluence of 5×10<jats:sup>13</jats:sup> cm<jats:sup>−2</jats:sup>, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation (DTI), where prompt funneling collection is the dominating mechanism. Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.</jats:p>

<jats:p>The Stokes–Einstein relation <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\eta $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>η</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> and its two variants <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim {\tau }^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow> <mml:mi>τ</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\tau $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>τ</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> follow a fractional form in supercooled liquids, where <jats:italic>D</jats:italic> is the diffusion constant, <jats:italic>T</jats:italic> the temperature, <jats:italic>η</jats:italic> the shear viscosity, and <jats:italic>τ</jats:italic> the structural relaxation time. The fractional Stokes–Einstein relation is proposed to result from the dynamic heterogeneity of supercooled liquids. In this work, by performing molecular dynamics simulations, we show that the analogous fractional form also exists in sodium chloride (NaCl) solutions above room temperature. <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim {\tau }^{-1}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:msup> <mml:mrow> <mml:mi>τ</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn4.gif" xlink:type="simple" /> </jats:inline-formula> takes a fractional form within 300–800 K; a crossover is observed in both <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\tau $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>τ</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn5.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\eta $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>η</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn6.gif" xlink:type="simple" /> </jats:inline-formula>. Both <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\tau $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>τ</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn7.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\eta $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>η</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn8.gif" xlink:type="simple" /> </jats:inline-formula> are valid below the crossover temperature <jats:italic>T</jats:italic> <jats:sub> <jats:italic>x</jats:italic> </jats:sub>, but take a fractional form for <jats:inline-formula> <jats:tex-math> <?CDATA $T\gt {T}_{x}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>T</mml:mi> <mml:mo>&gt;</mml:mo> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>x</mml:mi> </mml:mrow> </mml:msub> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn9.gif" xlink:type="simple" /> </jats:inline-formula>. Our results indicate that the fractional Stokes–Einstein relation not only exists in supercooled liquids but also exists in NaCl solutions at high enough temperatures far away from the glass transition point. We propose that <jats:inline-formula> <jats:tex-math> <?CDATA $D\sim T/\eta $?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mo>∼</mml:mo> <mml:mi>T</mml:mi> <mml:mrow> <mml:mo stretchy="false">/</mml:mo> </mml:mrow> <mml:mi>η</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076107_ieqn10.gif" xlink:type="simple" /> </jats:inline-formula> and its two variants should be critically evaluated to test the validity of the Stokes–Einstein relation.</jats:p>

<jats:p>To achieve <jats:italic>de novo</jats:italic> protein structure determination of challenging cases, multi-wavelength anomalous diffraction (MAD) and multiple isomorphous replacement (MIR) phasing can be powerful tools to obtain low-resolution initial phases from heavy-atom derivative datasets, then phase extension is needed against high-resolution data to obtain accurate structures. In this context, we propose a direct-methods procedure here that could improve the initial low-resolution MAD/MIR phase quality. And accordingly, an automated process for extending initial phases to high resolution is also described. These two procedures are both implanted in the newly released IPCAS pipeline. Three cases are used to perform the test, including one set of 4.17 Å MAD data from a membrane protein and two sets of MAD/MIR data with derivatives truncated down to 6.80 Å and 6.90 Å, respectively. All the results have shown that the initial phases generated from the direct-methods procedure are better than that from the conventional MAD/MIR methods. The automated phase extensions for the latter two cases starting from 6.80 Å to 3.00 Å and 6.90 Å to 2.80 Å are proved to be successful, leading to complete models. This may provide convenient and reliable tools for phase improvement and phase extension in difficult low-resolution tasks.</jats:p>

<jats:p>The electrical transport properties and structures of Y<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/ZrO<jats:sub>2</jats:sub> solid solution have been studied under high pressure up to 23.2 GPa by means of <jats:italic>in situ</jats:italic> impedance spectroscopy and x-ray diffraction (XRD) measurements. In the impedance spectra, it can be found that the pressure-dependent resistance of Y<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/ZrO<jats:sub>2</jats:sub> presents two different change trends before and after 13.3 GPa, but the crystal symmetry still remains stable in the cubic structure revealed by the XRD measurement and Rietveld refinement. The pressure dependence of the lattice constant and unit cell volume shows that the Y<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/ZrO<jats:sub>2</jats:sub> solid solution undergoes an isostructural phase transition at 13.1 GPa, which is responsible for the abnormal change in resistance. By fitting the volume data with the Birch–Murnaghan equation of state, we found that the bulk modulus <jats:italic>B</jats:italic> <jats:sub>0</jats:sub> of the Y<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/ZrO<jats:sub>2</jats:sub> solid solution increases by 131.9% from 125.2 GPa to 290.3 GPa due to the pressure-induced isostructural phase transition.</jats:p>

<jats:p>We investigate the structural phase transitions and electronic properties of GaAs nanowires under high pressure by using synchrotron x-ray diffraction and infrared reflectance spectroscopy methods up to 26.2 GPa at room temperature. The zinc-blende to orthorhombic phase transition was observed at around 20.0 GPa. In the same pressure range, pressure-induced metallization of GaAs nanowires was confirmed by infrared reflectance spectra. The metallization originates from the zinc-blende to orthorhombic phase transition. Decompression results demonstrated that the phase transition from zinc-blende to orthorhombic and the pressure-induced metallization are reversible. Compared to bulk materials, GaAs nanowires show larger bulk modulus and enhanced transition pressure due to the size effects and high surface energy.</jats:p>

<jats:p>As a representative of small aromatic molecules, triphenylene (TP) has markedly high carrier mobility and is an ideal precursor for building graphene nanostructures. We mainly investigated the adsorption behavior of TP molecules on Ru(0001) by using scanning tunneling microscopy (STM). In submonolayer regime, TP molecules are randomly dispersed on Ru(0001) and the TP overlayer can be thoroughly dehydrogenated and converted into graphene islands at 700 K. Due to weak interaction between TP molecules and graphene, the grooves formed among graphene islands have confinement effect on TP molecules. TP adopts a flat-lying adsorption mode and has two adsorption configurations with the 3-fold molecular axis aligned almost parallel or antiparallel to the <jats:inline-formula> <jats:tex-math><?CDATA $[1\bar{1}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">[</mml:mo> <mml:mn>1</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076801_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> 00] direction of the substrate. At TP coverages of 0.6 monolayer (ML) and 0.8 ML, the orientational distributions of the two adsorption configurations are equal. At about 1.0 ML, we find the coexistence of locally ordered and disordered phases. The ordered phase includes two sets of different superstructures with the symmetries of <jats:inline-formula> <jats:tex-math><?CDATA $(\sqrt{19}\times \sqrt{19})R23.41^\circ $?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:msqrt> <mml:mrow> <mml:mn>19</mml:mn> </mml:mrow> </mml:msqrt> <mml:mo>×</mml:mo> <mml:msqrt> <mml:mrow> <mml:mn>19</mml:mn> </mml:mrow> </mml:msqrt> <mml:mo stretchy="false">)</mml:mo> <mml:mi>R</mml:mi> <mml:mn>23.41</mml:mn> <mml:mo>°</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_076801_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> and <jats:italic>p</jats:italic>(4×4), respectively. The adsorption behavior of TP on Ru(0001) can be attributed to the delicate balance between molecule–substrate and molecule–molecule interactions.</jats:p>

<jats:p>Two-dimensional systems with chiral symmetry allow stable discrete band crossings (nodal points) in Brillouin zones. Here we study the local evolutions of these nodal points under chiral symmetry preserving perturbations. We find that these evolutions can be classified by different types of local <jats:inline-formula> <jats:tex-math> <?CDATA ${\boldsymbol{k}}\cdot {\boldsymbol{p}}$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi mathvariant="bold-italic">k</mml:mi> <mml:mo>·</mml:mo> <mml:mi mathvariant="bold-italic">p</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_7_077101_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> models around the nodal points. Several concrete examples are calculated to illustrate our results.</jats:p>

<jats:p>Motivated by the growing interest in the novel quantum phases in materials with strong electron correlations and spin–orbit coupling, we study the interplay among the spin–orbit coupling, Kondo interaction, and magnetic frustration of a Kondo lattice model on a two-dimensional honeycomb lattice. We calculate the renormalized electronic structure and correlation functions at the saddle point based on a fermionic representation of the spin operators. We find a global phase diagram of the model at half-filling, which contains a variety of phases due to the competing interactions. In addition to a Kondo insulator, there is a topological insulator with valence bond solid correlations in the spin sector, and two antiferromagnetic phases. Due to the competition between the spin–orbit coupling and Kondo interaction, the direction of the magnetic moments in the antiferromagnetic phases can be either within or perpendicular to the lattice plane. The latter antiferromagnetic state is topologically nontrivial for moderate and strong spin–orbit couplings.</jats:p>