Modern Physics Letters B

Molecular sensor applications are used in different fields including environmental monitoring and medical diagnosis. Graphene, a single atomic layer consisting of the hexagonally arranged carbon material, is one of the most promising materials for ideal channels in field-effect transistors to be used as electronic sensing applications owing to its lightweight, mechanical robustness, high electronic conductivity and large surface-to-volume ratio. This paper provides a review of molecular adsorptions, electronic properties and quantum transport of graphene based on the first-principles density-functional study. The adsorption properties of environmentally polluting or toxic molecules and electronic transport of graphene are revealed. The possibility of detecting these molecules selectively is also discussed for designing the graphene-based sensor applications.

Molecular docking and molecular dynamics (MD) are powerful tools used to investigate protein-ligand interactions. Molecular docking programs predict the binding pose and affinity of a protein-ligand complex, while MD can be used to incorporate flexibility into docking calculations and gain further information on the kinetics and stability of the protein-ligand bond. This review covers state-of-the-art methods of using molecular docking and MD to explore protein-ligand interactions, with emphasis on application to drug discovery. We also call for further research on combining common molecular docking and MD methods.

In this paper, the forward bias conduction and low frequency noise (LFN) characteristics of GaN Schottky barrier diodes (SBDs) have been measured and studied in the temperature range from 300 K to 450 K. Based on I–V measured results, the temperature dependence of ideality factor and zero bias Schottky barrier height reveals the inhomogeneities of Schottky barriers at the metal-semiconductor (MS) interface. Further study of the LFN measured results shows that the flicker noise ($1/f$ noise) is the main component of LFN in GaN SBDs. The current dependence of LFN indicates the influences of the Schottky barrier and the series resistance on $1/f$ noise, and the temperature dependence of LFN is analyzed according to Luo’s model and the barrier inhomogeneities model.

The two-dimensional transition-metal dichalcogenides (2D TMDs) WX₂ (S, Se, Te) have received extensive attention and research since they have excellent physical properties and have been widely used in the fields of photoelectronics. Monolayer (ML) WX₂ has excellent physical properties and can be modified by simple strain. Using the first principles based on density functional theory (DFT), this paper mainly studies the electronic properties of ML WS₂, WSe₂ and Wte₂. We also study the stabilities of three ML structures, the changes of Raman spectra and the movement of Raman peaks under biaxial tensile and compressive strains. Under the control of strain not only does the bandgap changes, but also the band properties shift between the direct bandgap and the indirect bandgap. With the increase of strain, bond length and bond angle change in the opposite trend. At the same time, we also studied the phonon dispersion relations of WX₂ under different strains. We found that three structures showed good thermodynamic stabilities under the tensile strain (1–10%). When the compressive strain is 2%, one of the acoustic modes of WS₂ or Wse₂ becomes imaginary at $\mathrm{\Gamma }$ point, which indicates the structural instability. When tensile strain Raman summit blueshifts and when compressive strains, the redshift occurs.

In this work, a novel stishovite–aluminum alloy with chemical formula SiO₂–Al–SiO₂ is proposed. The structural, electronic and optical properties were obtained using GGA-PBE functional. The study of electronic properties of SiO₂–Al–SiO₂ shows that it has a bandgap energy at 22 meV, compared to a much wider energy gap inside stishovite. The band structure of SiO₂–Al–SiO₂ reported in this work indicates that the SiO₂–Al alloy proposed is found to be a semi-metal. Also, we report a reflectivity of 73% (2.53 eV) and 70% (7.97 eV), based on 8.36 nm of its total thickness. The strong optical absorption at 2.11 eV and 5.79 eV is suggesting the SiO₂–Al–SiO₂ can be used as both visible part (orange) sensing and the UV photodetectors. Thus, the SiO₂–Al alloy can have potential application in optoelectronic device fabrications.

Based on the logic Bell states, we present two novel multi-party quantum key agreement (QKA) protocols under collective noise. The proposed protocols make full use of four-qubit logic Bell states as quantum resources and perform the novel encoding operation to generate the shared key. The security analysis shows that these two protocols can resist against both participant and outsider attacks. Furthermore, compared with the other existing multi-party QKA protocols over collective noise, our protocols have higher qubit efficiency. Finally, we perform the simulation of the relationship between efficiency and security, which is completely consistent with the conclusion of the security analysis of the protocols.

In this paper, we consider the shallow water wave model in the (2+1)-dimensions. The Hirota simple method is applied to construct the new dynamics one-, two-, three-, $N$-soliton solutions, complex multi-soliton, fusion, and breather solutions. By using the quadratic function, the one-lump, mixed kink-lump and periodic lump solutions to the model are obtained. The Hirota bilinear form variable of this model is derived at first via logarithmic variable transform. The physical phenomena to this model are explored. The obtained results verify the proposed model.

In this paper, we study (2+1)-dimensional non-linear spin dynamics of Heisenberg ferromagnetic spin chains equation (HFSCE) for various soliton solutions. We obtain two types of optical solitons i.e. chirp free and chirped solitons. We obtain bright and bright-like soliton, singular-like solitons, periodic and rational solutions, Weierstrass elliptic functions solutions and other solitary wave solutions for HFSCE with the aid of sub-ODE method. At the end, we present graphical representation of our solutions.

Based on the investigation of (2+1)-dimensional ZK–mZK–BBM equation, it describes the gravity water waves in a long-wave regime. With the help of the semi-inverse method and the variational method, the time fractional ZK–mZK–BBM equation is derived in the sense of Riemann–Liouville fractional derivatives, which opens a new window for understanding the features of gravity water waves. Further, the symmetry of the (2+1)-dimensional time fractional ZK–mZK–BBM equation is studied by fractional order symmetry. Meanwhile, based on the new conservation theorem, the conserved laws of (2+1)-dimensional time fractional ZK–mZK–BBM equation are constructed. Finally, we show how to derive the solutions of the time fractional ZK–mZK–BBM equation by a bilinear method and the radial basis functions (RBFs) meshless approach.

The effects of grain boundary (GB) and defect on the deformation behaviors of graphene under tension or compression in directions perpendicular ($x$-axis) or parallel ($y$-axis) to GB are investigated by molecular dynamics (MD) simulation. The results show that the bicrystalline graphene can sustain more load under tension along $y$-axis than along $x$-axis, and that regardless of tensile directions, the yield strength of bicrystalline graphene with high misorientation angle is higher than that with low angle. Furthermore, we found that the effect of GB on the deformation behavior of graphene under compression strain along $x$-axis is more obvious than that along $y$-axis.

TiO₂ thin films were deposited on quartz substrate by RF-magnetron sputtering technique. The effect of varying oxygen fraction $f({\mathrm{\text{O}}}_2)=({\mathrm{\text{O}}}_2/(\mathrm{\text{Ar}}+{\mathrm{\text{O}}}_2)$ on the surface morphology, structure, electrical and optical properties was investigated. Decreasing the oxygen fraction promotes phase transformation to the extent of isolating anatase phase with well oriented A(101) preferred crystal orientation at $f({\mathrm{\text{O}}}_2)$ of 0.1%. The refractive index dispersion curves were utilized to estimate the single oscillator parameters. In addition, an enhancement in the electrical conductivity to $2.6\times 10^{-2}{\mathrm{\Omega }}^{-1}{\mathrm{\text{cm}}}^{-1}$ at $f({\mathrm{\text{O}}}_2)=0.1$% was established. This enhancement was attributed to the deficiency of oxygen as well as the formation of anatase phase.

In this paper, the first-principles calculation methods are used to obtain the generalized stacking fault (GSF) energy of Al and Al alloy surface structures. At the same time, after obtaining the atomic pair potential, GSF energy is calculated by the means of atomic simulation simultaneously. By comparison, the calculation of GSF energy at different scales is consistent and the study of GSF energy from different scale level with an acceptable accuracy is realized. For the study of surface structure dislocation defects, the calculation of antiphase boundary (APB) energy is pretty significant. By means of the atomic pair potential, we calculate the APB energy of surface structure of the NiAl, FeAl and CoAl binary Al-based alloys. Therefore, in this paper, the surface structural dislocation of Al-base binary alloys was studied on different scales.

An equal-period plane diffraction grating fabricated through electron beam lithography line-by-line method was designed and applied to the experiment of angle sensitivity testing. The size of the fabricated grating region was $50\times 10$ mm and the period was 1526 nm. The incident light was transmitted via the Y-type fiber to collimator lens fixed on the angle disc, which can be adjusted to change the incident light angle. The diffraction spectra generated by the incident light irradiating the grating surface were collected by the optical spectrum analyzer. In this experiment, the incident light angle was fixed at 25${}^{\circ }$. When the spot moved horizontally by 50 mm, the diffraction wavelength was basically unchanged. When the incident light angle was adjusted from 15${}^{\circ }$ to 31${}^{\circ }$, the diffraction wavelength was changed from 834.03 nm to 1589.80 nm, the angular sensitivity was 47.508 nm/${}^{\circ }$, and the linearity was 0.9998.

In 2017, Chen et al. [Quantum Inf. Process. 16 (2017) 201] proposed a scheme for cyclic quantum teleportation (CYQT) of three single-qubit information states among three participants by using six-qubit entangled state as a quantum channel. Following the work of Chen et al., we propose a new scheme for CYQT in which four participants cyclically teleport four arbitrary single-qubit information states among themselves by using two $G$-states as a quantum channel. In our scheme, reverse CYQT can also be realized throughout changing the qubit pairs to be measured by each participant. We also generalize our scheme for CYQT of $N$-qubit entangled states.

In this paper, the boundary rounding effects of two types of non-circular GaN microcavity system are numerically simulated by the finite element method. When the rounding parameter $s$ of the hexagonal microcavity decreases, the six corners of the regular hexagon are gradually rounded, the results show that the optical mode gradually changes from the hexagonal whispering-gallery mode (WGM) to the perfect circular WGM, and the quality factor of the modes increases correspondingly. For the oval microcavity, the structure parameter $\delta$ increases from 0 to 1 when the oval microcavity gradually changes from a stadium cavity to a circular cavity. The simulation results show that the quality factor increases with $\delta$, and the optical mode changes from high-leak mode to WGM. Our results demonstrate the effect of the boundary rounding on the mode pattern and quality factor in hexagonal and oval microcavities.

Thermal hysteresis and stability of agarose–water gelling systems were studied by the spectrophotometer for different concentrations at different temperatures. Gelation temperature depends on the concentration of agarose. With the increase in the concentration of agarose gelation temperature, strength of agarose increases too. With the increase in the concentration of polymer solvent–gel phase transition, gel melting happens at higher temperatures. The price of enthalpy was determined (150.0127 KC/mol). In gelation process, the phase separation is completed and in this process, the value of this $\mathrm{\Delta }t=t_{\mathrm{\text{melting}}}-t_{\mathrm{\text{gelation}}}$ equally increases.