Modern Physics Letters B

Using a non-equilibrium Green’s function framework in combination with the complex energy-band method, an atomistic full-quantum model for solving quantum transport problems for a zigzag-edge graphene nanoribbon (zGNR) structure is proposed. For transport calculations, the mathematical expressions from the theory for zGNR-based device structures are derived in detail. The transport properties of zGNR-based devices are calculated and studied in detail using the proposed method.

In the current study, ABO₃ (A = Pb, Ba, Sr and B = Ti) perovskite structures are produced by the auto-combustion route by using citric acid (CA) and nitric acid (NA) as fuel and oxidizer. The X-ray diffraction (XRD) patterns confirmed the perovskite nanostructure with cubic, tetragonal, and rhombohedral for SrTiO₃, PbTiO₃, and BaTiO₃, respectively. Using Scherrer’s equation and XRD pattern, the average crystallite size of the samples were acquired. The effect of Ti–O bond length on the structure of the samples was evaluated. The type of structures obtained depends on Ti–O bond length which is in turn influenced by A${}^{2+}$ substitutions. Microstructural studies of nanostructures calcined at 850${}^{\circ }$C confirmed the formation of polyhedral particles with a narrow size distribution. The values of optical band gaps were measured and the impact of A${}^{2+}$ was discussed. The optical properties such as the complex refractive index and dielectric function were calculated by IR spectroscopy and Kramers–Kronig (K–K) relations. Lead, as the element with the highest density as compared to other elements, changes the optical constants, remarkably due to altering titanium and oxygen distance in TO₆ groups.

We investigate through numerical simulation the anomalous reflection (AR) of acoustic waves with perfect phononic crystals (PCs). Broadband AR is observed in a wide angle for the oblique incidence. The AR is due to the unsymmetrical specific acoustic impedance (SAI) profile along the surface, which is caused by the high frequency incidence. The findings in this paper complement the theories for the AR of acoustic waves with PCs, and may find applications in acoustic engineerings.

The experimental measurements of the isotope shifts (ISs) for the ¹S₀–³P₁ spin-forbidden transition at 791 nm in neutral barium have been carried out with a thermal barium atom beam. The hyperfine structure (HFS) constants a and b of the odd isotopes ${}^{137}$Ba and ${}^{135}$Ba for this transition have been extracted from the experimental results: a(${}^{137}$Ba) = 1149.9(1.0) MHz, b(${}^{137}$Ba)= −41.6(0.5) MHz, a(${}^{135}$Ba) = 1028.0(1.0) MHz, b(${}^{135}$Ba) = −27.5(0.5) MHz. The measured IS results with the reference isotope ${}^{138}$Ba are 183.7(1.0) MHz (${}^{137}$Ba–${}^{138}$Ba), 108.5(0.3) MHz (${}^{136}$Ba–${}^{138}$Ba) and 218.9(1.0) MHz (${}^{135}$Ba–${}^{138}$Ba). Our IS measurements are in good agreement with the previous experiments. The field shift (FS) factor $F_k$ and the mass shift (MS) coefficient $\mathrm{\Delta }{K}^{\mathrm{\text{MS}}}$ for this spin-forbidden transition have be determined experimentally as −3.19(4) GHz ⋅ fm${}^{-2}$ and −242(20) GHz ⋅ amu, respectively. The results provided herein could be used for further checks theoretically and experimentally, and could also contribute to the study on the nuclear structure of the barium isotopic nuclei.

In this paper, we proposed a new corresponding state-based correlation for organic fatty (aliphatic, carboxylic and polyfunctional) acids. By using the recently published surface tension data of the 99 acids [A. Mulero and I. Cachadiña, J. Phys. Chem. Ref. Data 45 (2016) 033105] and comparing with the recently published other corresponding state correlations, we found that this correlation reproduces the lowest absolute average deviation (AAD) values for 82 acids out of the 99 acids. It can reproduce the surface tension data with AAD less than 10% for 89 out of the 99 acids.

We calculate the pressure and entropy of a unitary Fermi gas based on universal relations combined with our previous prediction of energy which was calculated within the framework of the non-self-consistent T-matrix approximation with particle-hole fluctuation. The resulting entropy and pressure are compared with the experimental data and the theoretical results without induced interaction. For entropy, we find good agreement between our results with particle-hole fluctuation and the experimental measurements reported by ENS group and MIT experiment. For pressure, our results suffer from a systematic upshift compared to MIT data.

An ultrathin metasurface-based absorber consisting of titanium nitride (TiN) nano-disk arrays–dielectric layer-TiN substrate is proposed in this paper. The absorber exhibits near-unity absorption in the whole visible range of 380–780 nm. Our results demonstrate that the proposed metasurface-based absorber is not only independent of light polarization, but also exhibits angle-independent absorption behavior for oblique incidence up to 70${}^{\circ }$. The high absorption performance of the TiN nano-disk arrays-based absorber can attribute to two different loss mechanisms associated with the intrinsic loss and plasmonic resonance.

Based on the two velocity difference model (TVDM), an extended car-following model is developed to investigate the effect of driver’s memory and jerk on traffic flow in this paper. By using linear stability analysis, the stability conditions are derived. And through nonlinear analysis, the time-dependent Ginzburg–Landau (TDGL) equation and the modified Korteweg–de Vries (mKdV) equation are obtained, respectively. The mKdV equation is constructed to describe the traffic behavior near the critical point. The evolution of traffic congestion and the corresponding energy consumption are discussed. Numerical simulations show that the improved model is found not only to enhance the stability of traffic flow, but also to depress the energy consumption, which are consistent with the theoretical analysis.

The effects of quenching from 600${}^{\circ }$C and subsequent room-temperature annealing on the basal-plane electrical resistivity of underdoped HoBa₂Cu₃O${}_{7-\delta }$ single crystals are investigated. Regions with different superconducting transition temperatures, $T_c$, have been revealed in the sample after quenching and attributed to a non-uniform distribution of the labile oxygen in the sample volume. Room-temperature annealing has been revealed to lead to an increase of $T_c$ of all regions and a decrease of their number, attributed to the coalescence of clusters of oxygen vacancies. The temperature dependence of the resistance in the normal state is characterized by a decrease of the residual resistivity and the phonon scattering coefficient.

This paper investigates the finite-time synchronization of complex networks (CNs) with non-identical nodes and impulsive disturbances. By utilizing stability theories, new 1-norm-based analytical techniques and suitable comparison, systems, several sufficient conditions are obtained to realize the synchronization goal in finite time. State feedback controllers with and without the sign function are designed. Results show that the controllers with sign function can reduce the conservativeness of control gains and the controllers without sign function can overcome the chattering phenomenon. Numerical simulations are offered to verify the effectiveness of the theoretical analysis.

Experimental investigations of unsteady cavitating flows in a hydrofoil tip leakage region with different gap sizes are conducted to highlight the development of gap cavitation. The experiments were taken in a closed cavitation tunnel, during which high-speed camera had been used to capture the cavitation patterns. A new visualization method based on image processing was developed to capture time-dependent cavitation patterns. The results show that the visualization method can effectively capture the cavitation patterns in the tip region, including both the attached cavity in the gap and the tip leakage vortex (TLV) cavity near the trailing edge. Moreover, with the decrease of cavitation number, the TLV cavity develops from a rapid onset-growth-collapse process to a continuous process, and extends both upstream and downstream. The attached cavity in the gap develops gradually stretching beyond the gap and combines with the vortex cavity to form the triangle cavitating region. Furthermore, the influences of gap size on the cavitation are also discussed. The gap size has a great influence on the loss across the gap, and hence the locations of the inception attached cavity. Besides, inception locations and extending direction of the TLV cavity with different gap sizes also differ. The TLV in the case with $\tau$ = 0.061 is more likely to be jet-like compared with that in the case with $\tau$ = 0.024, and the gap size has a great influence on the TLV strength.

Community detection and link prediction are both of great significance in network analysis, which provide very valuable insights into topological structures of the network from different perspectives. In this paper, we propose a novel community detection algorithm with inclusion of link prediction, motivated by the question whether link prediction can be devoted to improving the accuracy of community partition. For link prediction, we propose two novel indices to compute the similarity between each pair of nodes, one of which aims to add missing links, and the other tries to remove spurious edges. Extensive experiments are conducted on benchmark data sets, and the results of our proposed algorithm are compared with two classes of baselines. In conclusion, our proposed algorithm is competitive, revealing that link prediction does improve the precision of community detection.

Under investigation in this paper is the Kundu equation, which may be used to describe the propagation process of ultrashort optical pulses in nonlinear optics. The modulational instability of the plane-wave for the possible reason of the formation of the rogue wave (RW) is studied for the system. Based on our proposed generalized perturbation $(n,N-n)$-fold Darboux transformation (DT), some new higher-order implicit RW solutions in terms of determinants are obtained by means of the generalized perturbation $(1,N-1)$-fold DT, when choosing different special parameters, these results will reduce to the RW solutions of the Kaup–Newell (KN) equation, Chen–Lee–Liu (CLL) equation and Gerjikov–Ivanov (GI) equation, respectively. The relevant wave structures are shown graphically, which display abundant interesting wave structures. The dynamical behaviors and propagation stability of the first-order and second-order RW solutions are discussed by using numerical simulations, the higher-order nonlinear terms for the Kundu equation have an impact on the propagation instability of the RW. The method can also be extended to find the higher-order RW or rational solutions of other integrable nonlinear equations.

Electronic and elastic properties of the half-Heusler CoCrSn are calculated using first-principles method. The results show that CoCrSn is a half-metallic ferrimagnetism with the total magnetic moment of 1.00 ${\mu }_B$ per formula unit at equilibrium lattice constant. The results agree well with the Slatere–Pauling rule based on the relationship of valence electrons and total magnetic moment. The half-Heusler CoCrSn maintains the half-metallic stability within the lattice constants ranging from 5.17 Å to 5.91 Å in GGA, from 5.24 Å to 5.89 Å in GGA+SOC, and from the 4.63 Å to 6.18 Å in GGA+U, respectively. The mechanical parameters of CoCrSn, such as elastic constants, bulk modulus, shear modulus, Pough’s ratio, Frantesvich ratio, Young’s modulus, Poisson’s ratio, Kleinman parameter and Debye temperature are calculated for the first time, and the results show that it is mechanically stable and is a ductile material. The studies show that the half-Heusler CoCrSn is a promising half-metal in spintronics.