International Journal of Modern Physics B

This paper presents a novel digital silicon gyroscope interface circuit, designed by 0.35 $\mu$m BCD process, and the chip area is 4.8 mm ∗ 5.0 mm. The traditional noise model of charge amplifier decomposes the noise into voltage noise and current noise. But the test results show that current noise accounts for a large proportion, which is not consistent with the theoretical model. Through the analysis of experimental data and the study of operational amplifier’s working principle in charge amplifier, a new noise model is established, which makes the experimental data closer to the theoretical model. The design makes use of the bandpass characteristics of the bandpass sigma–delta modulator consistent with the sensitive structure of the silicon gyroscope, and optimizes the digital principle of the silicon gyroscope. The digital demodulation of bandpass sigma–delta modulator (BP SDM) can directly separate the in-phase component from the orthogonal component, which eliminates the tedious design of carrier signal digitization and multi-digital filtering, simplifies the frame structure of the whole digital silicon gyroscope system and reduces the design difficulty and physical cost. The ASIC of silicon gyroscope digital interface circuit is tested in combination with the sensitive structure. The noise density of 0.0014${}^{\circ }$/s/Hz${}^{1/2}$, zero stability of 1${}^{\circ }$/h (1$\sigma$) and 0.2${}^{\circ }$/h (Allen variation). The test of ASIC and the whole machine proves the correctness of the theoretical model, which reflects the correctness of the performance of the digital interface circuit of silicon gyroscope.

First-principles method based on density functional theory has been performed to study the crystal structures, phase stability, site preferences, elastic properties, hardness, melting points, Debye temperatures and electronic properties of Al-doped B2-NiSc intermetallics with different concentrations systematically. The results show that the Al atom occupies the Sc site preferentially. For the doped systems in which an Sc atom is substituted by one Al atom, the bulk modulus increases as the Al doping concentration increases and is larger than that of pure B2-NiSc. However, the shear modulus and Young’s modulus are smaller than the parent phase. The ductility of B2-NiSc intermetallics can be improved by adding Al element, and it increases with the increase of doping concentration. But, the increase of ductility is accompanied by the decrease of hardness. The melting points of doped alloys are all lower than the parent phase. Besides, on the basis of the calculated electronic properties, Al doping weakens covalent bonding and enhances the metal bonding of Al-doped NiSc.

We report the properties of superconductivity and Hall effect in 100 nm Pb${}_{82}$Bi${}_{18}$ alloy thin films which were prepared by thermal evaporation with quench condensation using liquid nitrogen. X-ray diffraction indicates the films are $\alpha$-phase with peaks shifted to lower angles compared to pure Pb. The $T_C$ of the films was higher than those of an amorphous Pb–Bi alloy thin film of the same composition and pure bulk Pb. The resistivity, critical field and critical current density of the thin films are reported. The coherence length ($\xi$) and London penetration depth ($\lambda$) near $T_C$ were calculated from the experimental results. The films are in the dirty limit and behave as type-II superconductors with a Ginzburg–Landau parameter of about 10. Additionally, the films show sign reversal in Hall measurements. These films have been quite useful in a comprehensive study of the effects of flux pinning by integrated ferromagnetic nanostructures conducted in hybrid ferromagnet–superconductor samples in our lab over the past few years due to their single-phase nature and strong type-II behavior.

During these last years, the substantially biological field effect transistors (BioFET) are one of the most abundant classes of electronic sensors for biomolecular detection. The determination of glucose levels using these biosensors, especially in the medical diagnosis and food industries, is gaining popularity. Among them, ion-sensitive field effect transistor (ISFET) is considered one of the most intriguing approaches in electrical biosensitivity technology. The glucose sensor ISFET detects the glucose molecule by catalyzing glucose to gluconic acid and hydrogen peroxide in the presence of oxygen. In this paper, first of all we examine some of the main advantages in this field, the perspective of applications and the main issues in order to stimulate a broader interest in the development of biosensors based on ISFET and to extend their applications for a reliable and sensitive glucose analysis. Thereafter, a biosensor with field effect sensitive to the ions for the detection of glucose is modeled analytically. In the proposed model, the glucose concentration is presented according to the gate voltage. The simulated data show that the analytical model can be used with an electrochemical glucose sensor to predict mechanism’s behavior of detection in the biosensors.

Materials with novel properties and compounds of intelligent material combinations are a key to innovation in various successful sectors of the global industry as well as for its export. Magnetorheological elastomer materials have interesting physical properties; most of these properties are modified and adapted under the influence of external parameters such as the magnetic field. In this work, an experimental characterization of the magnetorheological elastomers (MRE) loaded with 20% of the iron particles was made. The results showed that the properties of these materials can be modified very selectively and reversibly under the influence of magnetic field, where the stiffness of the material varies depending on the magnetic field intensity that influences the attractive force between iron particles.

A method was devised to construct a generalized dual field theory with a quantum field theory named the dual Hamiltonian (DH) method. As a simple example using this method, we examined the duality between coherent quantum phase-slip and Josephson junction (JJ) in single junction systems and nanowires. This method was proved to be reliable within the Villain approximation.

A novel design of a silicon-on-insulator (SOI)-based resonator based on slot micro-ring and Bragg gratings is presented. The corrugated Bragg gratings are structured on both sides of slot micro-ring waveguides. The variation of the effective refractive index is detected by monitoring the shift of the spectral of the resonator. The transmission spectrum and field distribution of the sensor structures are simulated using finite-difference time-domain (FDTD) method. With the combination of the Bragg gratings, the measurement range of the sensor significantly increases without the restriction of a free spectral range (FSR). Our proposed sensor design provides a promising candidate for on-chip integration with other silicon photonic element.

During development of multicellular organisms, morphogen is a kind of signaling molecules produced at a local region and transported into a development field, which acts as dose-dependent regulators of gene expression, directs and controls cellular differentiation. Some experiments showed that during embryo development, dynamical processes of morphogen transport always accompany the tissue growth. However, how tissue growth affects morphogen gradients remains to be explored. To answer this problem, we propose a reaction-diffusion-convection model for morphogen transport. For this model, we mainly investigate local accumulation times (LATs) of morphogen gradients, which are a measure for time of forming the steady state of morphogen gradients. In this paper, we simplify the method of calculating the LATs and use this method to obtain analytic expressions of the LATs for uniform and linear growth, respectively. Besides, for tissue nonuniform growth, we apply an approximation method of the LATs to study them. This paper shows that tissue growth can shorten the LATs of morphogen gradients.

In this paper, we proposed a new one-parameter correlation for the surface tension of saturated fluids. This new correlation requires only the critical temperature as inputs and is tested by using the REFPROP data for 72 saturated fluids including refrigerants, alkanes and some other simple fluids such as argon, carbon dioxide, etc. It is found that this correlation well stands in the whole temperature range from the triple point to the critical point with high accuracy for 59 liquids with average absolute deviations (AADs) less than 5%, 50 liquids with AADs less than 3%, and 13 liquids with AADs less than 1%. These results are clearly better than those of the other available correlations. This correlation can be used to estimate the value of the surface tension of the corresponding liquids at any temperature point from the triple point to the critical point.

Boron nitride (BN) and Titanium nitrides (TiNs) have been successfully researched recently. In order to analyze the relationship among the Boron, Nitrogen and Titanium, the ternary compounds with an orthorhombic structure Immm- are studied. We further researched on the mechanical, electronic and optical properties of new Immm-B${}_x$Ti${}_{3-x}$N₂ ($x=1,2$). The structures of BTi₂N₂ and B₂TiN₂ are mechanically stable at 0, 50 and 100 GPa. The BTi₂N₂ has the higher cutting resistance and better ductility than the B₂TiN₂. The higher Young’s modulus of B₂TiN₂ indicates the B₂TiN₂ is stiffer than BTi₂N₂. The BTi₂N₂ is harder to compress in the $Y$ direction and the B₂TiN₂ is harder in $Z$ direction. Immm-BTi₂N₂ and B₂TiN₂ have good metallicity at 0 and 100 GPa. Immm-BTi₂N₂ has the higher dielectric function than B₂TiN₂ and the plasma frequency of B₂TiN₂ is bigger than that of BTi₂N₂. We hope our work will provide some help to the experimental work about the technology of the material.

In this paper, we explore the emergence of patterns in a fractional cross-diffusion model with Beddington–DeAngelis type functional response. First, we explore the stability of the equilibrium points with or without fractional cross-diffusion. Instability of equilibria can be induced by cross-diffusion. We perform the linear stability analysis to obtain the constraints for the Turing instability. It is found by theoretical analysis that cross-diffusion is an important mechanism for the appearance of Turing patterns. For the dynamics of pattern, the weakly nonlinear multi-scaling analysis has been performed to obtain the amplitude equations. Finally, we ensure the existence of Turing patterns such as squares, spots and stripes by using the stability analysis of the amplitude equations. Moreover, with the assistance of numerical simulations, we verify the theoretical results.

The structural, electronic and elastic properties of orthorhombic ZnGeN₂ and wurtzite (WZ)-GaN semiconductors have been studied under different pressures using first-principle density functional theory (DFT) calculations. The lattice constants (a, b and c) and energy bandgaps ($E_g$) have been calculated under ambient condition. The elastic properties such as elastic stiffness constants ($C_{ij}$), shear modulus (G), bulk modulus (B), Young modulus ($\gamma$), B/G ratio and Poisson ratio ($\upsilon$) have been studied at 50, 100, 110, 120, 150, 160, 180 and 190 GPa pressures for the first time as well as at 0 GPa. The calculated values of $C_{ij}$ show that the ZnGeN₂ and GaN are stable up to 180 and 150 GPa, respectively, and afterwards phase changes and become unstable. The band structure of ZnGeN₂ reveals direct band gap behavior up to 100 GPa and becomes indirect band gap at 110 GPa. However, GaN is direct band gap up to 150 GPa and becomes indirect at 160 GPa. Comparing the results of both semiconductors, it is observed that ZnGeN₂ is similar to WZ-GaN up to 100 GPa in all respect and can be used in many applications in place of WZ-GaN. The calculated values of all parameters are in reasonable agreement with the known values.

Deep rolling is a surface treatment method by which a hydraulically controlled ball produces a specific pressure on material surface, causing plastic deformation and introducing compressive residual stresses. In this paper, LZ50 steel which is often used as high speed train axle is treated by deep rolling. Surface morphology was observed, and roughness, microhardness and residual stress were measured. Effects of deep rolling parameters (pressure, feed speed, speed, number of runs) on the surface integrity of LZ50 axles were studied systematically. The results show that the surface roughness decreases obviously after deep rolling compared with the original surface. The feed speed has greater influence than other parameters on surface roughness. The minimum roughness (Ra) can decrease to 0.14 $\mu$m. The surface layer of LZ50 deforms in different degrees. Meanwhile, the surface stress state of LZ50 changes from tensile stress to compressive stress after deep rolling. The maximum residual compressive stress is 862 MPa. The main influence factor is pressure. However, for LZ50 axle, the surface hardness does not change significantly after deep rolling.

We study the distribution of the stationary correlations in a system of two nonidentical as well as identical two-level atoms separated by an arbitrary distance and interacting with a squeezed vacuum. We investigate how the interatomic distance and the squeezing mean number of photons influence the way that one of the atoms is quantum correlated with the environment. Both for nonidentical and identical atoms, the approach of the two atoms can maximize the entanglement and quantum discord between the pair of atoms. For nonidentical atoms, the bigger the mean number of photons, the stronger the stationary correlations, i.e., entanglement of formation (EOF) and quantum discord (QD) between the qubit and the environment as the increase of distance. The increase of EOF and QD with the environment is always accompanied by a decrease of the correlations between the subsystems with regard to the interatomic distance no matter what the mean number of photons is. For identical atoms, the stationary correlations EOF and QD between each partition behave similarly with respect to the distance when the mean number of photons is very small.