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<jats:p>We investigate the influence of an external electric field on the dewetting behavior of nitrogen-water systems between two hydrophobic plates using molecular dynamics simulations. It is found that the critical distance of dewetting increases obviously with the electric field strength, indicating that the effective range of hydrophobic attraction is extended. The mechanism behind this interesting phenomenon is related to the rearrangement of hydrogen bond networks between water molecules induced by the external electric field. Changes in the hydrogen bond networks and in the dipole orientation of the water molecules result in the redistribution of the neutral nitrogen molecules, especially in the region close to the hydrophobic plates. Our findings may be helpful for understanding the effects of the electric field on the long-range hydrophobic interactions.</jats:p>

<jats:p>As a prototype material of colossal barocaloric effects, neopentylglycol is investigated by combining high-precision differential scanning calorimetric measurement and high-energy x-ray diffraction measurement. The diffraction data at constant temperatures indicate a first-order phase transition with thermal hysteresis as well as the phase transition asymmetry, specifically, the phase transition is completed faster at cooling than at heating. The analysis of resulting pair distribution function confirms the intermolecular disorder in the high-temperature phase. The phase transition asymmetry is quantitatively characterized by time-resolved x-ray diffraction, which is in agreement with the thermal measurement. Also, such an asymmetry is observed to be suppressed at high pressures.</jats:p>

<jats:p>A kind of nested eccentric waveguide constructed with two cylindrical nanowires coated with graphene was designed. The mode characteristics of this waveguide were studied using the multipole method. It was found that the three lowest modes (mode 0, mode 1 and mode 2) can be combined by the zero-order mode or/and the first-order modes of two single nanowires. Mode 0 has a higher figure of merit and the best performance among these modes within the parameter range of interest. The mode characteristics can be adjusted by changing the parameters of the waveguide. For example, the propagation length will be increased when the operating wavelength, the minimum spacing between the inner and outer cylinders, the inner cylinder radius and the Fermi energy are increased. However, when the outer cylinder radius, the dielectric constants of region I, or the dielectric constants of region III are increased, the opposite effect can be seen. These results are consistent with the results obtained using the finite element method (FEM). The waveguide structure designed in this paper is easy to fabricate and can be applied to the field of micro/nano sensing.</jats:p>

<jats:p>Recently, two-dimensional van der Waals (vdW) magnetic heterostructures have attracted intensive attention since they can show remarkable properties due to the magnetic proximity effect. In this work, the spin-polarized electronic structures of antimonene/Fe<jats:sub>3</jats:sub>GeTe<jats:sub>2</jats:sub> vdW heterostructures were investigated through the first-principles calculations. Owing to the magnetic proximity effect, the spin splitting appears at the conduction-band minimum (CBM) and the valence-band maximum (VBM) of the antimonene. A low-energy effective Hamiltonian was proposed to depict the spin splitting. It was found that the spin splitting can be modulated by means of applying an external electric field, changing interlayer distance or changing stacking configuration. The spin splitting energy at the CBM monotonously increases as the external electric field changes from –5 V/nm to 5 V/nm, while the spin splitting energy at the VBM almost remains the same. Meanwhile, as the interlayer distance increases, the spin splitting energies at the CBM and VBM both decrease. The different stacking configurations can also induce different spin splitting energies at the CBM and VBM. Our work demonstrates that the spin splitting of antimonene in this heterostructure is not singly dependent on the nearest Sb–Fe distance, which indicates that magnetic proximity effect in heterostructures may be modulated by multiple factors, such as hybridization of electronic states and the local electronic environment. The results enrich the fundamental understanding of the magnetic proximity effect in two-dimensional vdW heterostructures.</jats:p>

<jats:p>High-pressure Raman scattering from hexagonal close-packed (HCP) metals Os and Re have been extended up to 200 GPa, and the pressure-dependent shear modulus <jats:italic>C</jats:italic> <jats:sub>44</jats:sub> has been deduced from the Raman-active mode <jats:italic>E</jats:italic> <jats:sub>2<jats:italic>g</jats:italic> </jats:sub>, which is generated from the adjacent vibration of atoms in hexagonal planes, providing the valuable information about the elastic properties for HCP metals under high pressure. Combined with the available data of HCP metals from previous works, a further study indicates that the <jats:inline-formula> <jats:tex-math><?CDATA ${C}_{44}^{\prime}/{C}_{44}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>C</mml:mi> <mml:mrow> <mml:mn>44</mml:mn> </mml:mrow> <mml:mo>′</mml:mo> </mml:msubsup> <mml:mo>/</mml:mo> <mml:msub> <mml:mi>C</mml:mi> <mml:mrow> <mml:mn>44</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_31_3_037801_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula> ratio would be close to a constant value, 0.01, with increasing atomic number of metals. The results obtained from high-pressure Raman scattering will allow us to probe the elastic anisotropy of the HCP metals at very high pressure.</jats:p>

<jats:p>Wheat leaves with natural microstructures as substrates were covered by the silver nanoislands by magnetron to prepare a low-cost, environment-friendly and mass production surface-enhanced fluorescence (SEF) substrate (Ag-WL substrate). The best SEF substrate was selected by repeatly certifying the fluorescence intensity of 10<jats:sup>−5</jats:sup> M Rhodamine B (RB) and 10<jats:sup>−5</jats:sup> M Rhodamine 6G (R6G) aqueous solutions. The abundant semi-spherical protrusions and flake-like structures on the surface of the Ag-WL substrate produce high-density hot spots, which provides a new and simple idea for the preparation of biomimetic materials. The results of 3D finite-different time-domain (FDTD) simulation show that the nanoisland gap of semi-spherical protrusions and flake-like structures has produced rich hotspots. By adjusting the time of magnetron sputtering, the enhancement factor (EF) was as high as 839 times, relative standard deviation (RSD) reached as low as 10.7%, and the substrate was very stable and repeatable, which shows that Ag-WL substrate is trustworthy. Moreover, semi-spherical protrusions provide stronger surface-enhanced Raman scattering (SERS) effects compared to flake-like structure. What is more surprising is that the detection limit of the substrate for toxic substance crystal violet (CV) is as low as 10<jats:sup>−10</jats:sup> M.</jats:p>

<jats:p>In order to significantly improve the absorption efficiency of monolayer molybdenum disulfide (M-MoS<jats:sub>2</jats:sub>), an ultra-narrowband M-MoS<jats:sub>2</jats:sub> metamaterial absorber was obtained through theoretical analysis and numerical calculation using the finite difference time domain method. The physical mechanism can be better analyzed through critical coupling and guided mode resonance. Its absorption rate at <jats:italic>λ</jats:italic> = 806.41 nm is as high as 99.8%, which is more than 12 times that of bare M-MoS<jats:sub>2</jats:sub>. From the simulation results, adjusting the geometric parameters of the structure can control the resonant wavelength range of the M-MoS<jats:sub>2</jats:sub>. In addition, we also found that the maximum quality factor is 1256.8. The numerical result shows that the design provides new possibilities for ultra-narrowband M-MoS<jats:sub>2</jats:sub> perfect absorbers in the near-infrared spectrum. The results of this work indicate that the designed structure has excellent prospects for application in wavelength-selective photoluminescence and photodetection.</jats:p>

<jats:p>Among all the known electrode materials, vanadium pentoxide (V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub>) has high reversible capacity. It is a very valuable material for research of the complexity, rich structure and morphology. However, it also has some disadvantages, such as poor cycle stability, low discharge voltage, low conductivity and Li<jats:sup>+</jats:sup> diffusion coefficient. In this regard, researchers have carried out a lot of research, such as using various methods to improve the nanostructures, introducing heterostructures, introducing point defects or cation doping in the crystal structure, etc. The electrochemical performance of V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> has been significantly improved in reversible capacity, high-rate capacity and long-term cycle stability. In this paper, V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> based nanostructure with different chemical composition are briefly introduced, and it covers V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> nanomaterials with different morphology, including 1D nanorods, nanobelts, nanotubes, 2D leaf like nanosheets and other nanosheets, and 3D hollow structures, porous nanostructures, porous eggshell microsphere structures. The composite nanomaterials of V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> and different carbonaceous supports are also introduced. Finally, the V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> composite materials doped with cations are discussed. The electrochemical performance of V<jats:sub>2</jats:sub>O<jats:sub>5</jats:sub> based electrode can be improved effectively by obtaining appropriate nanostructure and optimized chemical composition.</jats:p>

<jats:p>For convenient and efficient verification of the magnetoresistance effect in graphene spintronic devices, vertical magnetic junctions with monolayer graphene sandwiched between two NiFe electrodes are fabricated by a relatively simple way of transferring CVD graphene onto the bottom ferromagnetic stripes. The anisotropic magnetoresistance contribution is excluded by the experimental result of magnetoresistance (MR) ratio dependence on the magnetic field direction. The spin-dependent transport measurement reveals two distinct resistance states switching under an in-plane sweeping magnetic field. A magnetoresistance ratio of about 0.17 % is obtained at room temperature and it shows a typical monotonic downward trend with the bias current increasing. This bias dependence of MR further verifies that the spin transport signal in our device is not from the anisotropic magnetoresistance. Meanwhile, the <jats:italic>I</jats:italic>–<jats:italic>V</jats:italic> curve is found to manifest a linear behavior, which demonstrates the Ohmic contacts at the interface and the metallic transport characteristic of vertical graphene junction.</jats:p>

<jats:p>Perovskite solar cells (PSCs) are the most promising commercial photoelectric conversion technology in the future. The planar p–i–n structure cells have advantages in negligible hysteresis, low temperature preparation and excellent stability. However, for inverted planar PSCs, the non-radiative recombination at the interface is an important reason that impedes the charge transfer and improvement of power conversion efficiency. Having a homogeneous, compact, and energy-level-matched charge transport layer is the key to reducing non-radiative recombination. In our study, NiO<jats:sub> <jats:italic>x</jats:italic> </jats:sub>/Sr:NiO<jats:sub> <jats:italic>x</jats:italic> </jats:sub> bilayer hole transport layer (HTL) improves the holes transmission of NiO<jats:sub> <jats:italic>x</jats:italic> </jats:sub> based HTL, reduces the recombination in the interface between perovskite and HTL layer and improves the device performance. The bilayer HTL enhances the hole transfer by forming a driving force of an electric field and further improves <jats:italic>J</jats:italic> <jats:sub>sc</jats:sub>. As a result, the device has a power conversion efficiency of 18.44%, a short circuit current density of 22.81 mA⋅cm<jats:sup>−2</jats:sup> and a fill factor of 0.80. Compared to the pristine PSCs, there are certain improvements of optical parameters. This method provides a new idea for the future design of novel hole transport layers and the development of high-performance solar cells.</jats:p>