Novel optical film sensor design based on p-polarized reflectance

A new scheme of optical film sensor is presented. The sensor is based on p-polarized reflectance, consisting of a sensing coated substrate, is easily optimized for maximum sensitivity in different applications. The resolutions of refractive index n_f, extinction coefficient k_f and thickness h_f of the sensitive films are predicted to be 10⁻⁷, 10⁻⁵ and 10⁻³ nm, respectively. Experimentally, we selected the sol–gel derived SnO₂ films as gas-sensitive films and conducted preliminary gas-sensing test. The results indicate that novel optical film sensor scheme has higher sensitivity, and the detection sensitivity is available to 10⁻¹ ppm on the condition of optimum optical parameters and incident angle.     

Control of adiabatic two-phase dielectric fluid flow distribution with EHD conduction pumping

Electrohydrodynamic (EHD) conduction pumping is associated with the heterocharge layers of finite thickness in the vicinity of the electrodes, which are based on the process of dissociation of the neutral electrolytic species and recombination of the generated ions. This paper presents the successful control of dielectric liquid/vapor flow distribution between two parallel branch lines utilizing an EHD conduction pump at a select mass flux level under adiabatic condition.     

Anisotropies in soft magnetic nanocrystalline alloys

The article reviews and updates the understanding of the soft magnetic properties of nanocrystalline Fe-based alloys. In optimized compositions the random magneto-crystalline anisotropy of the structural phases is largely averaged out. The soft magnetic properties are then controlled by magneto-elastic and induced anisotropies which are uniform on a scale much larger than the exchange length. But unlike to the case of soft magnetic amorphous alloys, there is still a competition between the random and the more uniform anisotropy contributions. The experimental findings are complemented by theoretical results.     

Effect of initial phosphate concentration on cell growth and ginsenoside saponin production by suspended cultures of panax notoginseng

Effects of initial phosphate concentration on the growth, ginsenoside saponin production, and the consumption of sugar and nitrogen sources by suspended cells ofPanax notoginseng (Burk) F. H. Chen were investigated in a 250-mL shake flask. The results indicate that by increasing the initial phosphate concentration in the medium in the range of 0–1.25 mM, both the cell growth and the saponin accumulation were greatly improved, and the utilization of sugar and nitrogen sources was also increased. The highest production, productivity, and yield of ginsenosides obtained were 0.98 g/L, 45.5 mg/L/d, and 0.030 g/g at 1.25 mM of initial medium phosphate. At a relatively higher level of medium phosphate, i.e., 2.0 mM, the product accumulation was inhibited to some degree, although the cell growth was not.     

Critical point transitions of wurtzite indium nitride

The optical transmission, photoluminescence, and reflection spectra have been measured on a high-quality wurtzite indium nitride (InN) single crystal in the range of 0.5–20.0 eV. The fundamental bandgap of intrinsic InN has been extracted by taking into account the Burstein–Moss shift, bandgap renormalization and Urbach band tail effects, and found to be very close to the recent strongly re-established value of ∼1.2 eV. With the aid of Adachi's dielectric function model for the vacuum ultraviolet reflection spectra and the empirical pseudopotential method approach for the electron band-structure, we are able to identify up to nine electronic transitions, showing clear picture for the critical point transitions in InN. The temperature dependence of these interband transitions has also been revealed.     

Study of HfSiO film prepared by electron beam evaporation for high-k gate dielectric applications

The purpose of this paper is to report some experimental results with HfSiO films formed on silicon substrates by electron beam evaporation (EB-PVD) and annealed at different temperatures. The images of atomic force microscope (AFM) indicated that HfSiO film annealed at 900 °C was still amorphous, with a surface roughness of 0.173 nm. X-ray photoelectron spectroscopy (XPS) analysis revealed that the chemical composition of the film was (HfO₂)₃(SiO₂) and Hf-Si-O bonds existed in the annealed film. Electrical measurements showed that the equivalent oxide thickness (EOT) was 4 nm, the dielectric constant was around 6, the breakdown voltage was 10 MV/cm, the fixed charge density was −1.2 × 10¹² cm⁻², and the leakage current was 0.4 μA/cm² at the gate bias of 2 V for 6 nm HfSiO film. The annealing after deposition effectively reduced trapping density and the leakage current, and eliminated hysteresis in the C-V curves. Annealing also induced SiO₂ growth at the interface.     

Neutrino nucleus cross sections for low energy neutrinos at SNS facilities

We calculate the neutrino nucleus cross sections for charged lepton production relevant for the experiments proposed with the stopped muon neutrinos using neutron spallation source facility. The calculations are done in local density approximation taking into account Pauli blocking, Fermi motion effects and renormalization of weak transition strengths in the nuclear medium. The effect of Coulomb distortion of the lepton produced in charge current reactions is taken into account by using the Fermi function as well as in a model where an effective momentum has been used for the lepton moving in the local Coulomb field of the final nucleus. The numerical results for the neutrino nucleus total cross sections averaged over Michel spectrum are presented for various nuclei.     

Density viscous continuum traffic flow model

A new traffic flow model called density viscous continuum model is developed to describe traffic more reasonably. The two delay time scales are taken into consideration, differing from the model proposed by Xue and Dai [Phys. Rev. E 68 (2003) 066123]. Moreover the relative density is added to the motion equation from which the viscous term can be derived, so we obtain the macroscopic continuum model from microscopic car following model successfully. The condition for stable traffic flow is derived. Nonlinear analysis shows that the density fluctuation in traffic flow induces density waves. Near the onset of instability, a small disturbance could lead to solitons determined by the Korteweg-de-Vries (KdV) equation, and the soliton solution is derived. The results show that local cluster effects can be obtained from the new model and are consistent with the diverse nonlinear dynamical phenomena observed in the freeway traffic.