Great enhancement in remnant polarisation of SrBi_4Ti_4O_(15) thin films by A-site doping of Fe^(3+) ions

SrBi4-xFexTi4015 （SBFT-x） thin films （x = 0.00, 0.05, 0.08, 0.15） have been synthesized on Pt/Ti/SiO2/Si （100） substrates by sol-gel method. This paper finds that Fe-doping does not change the crystal structure of SrBi4Ti4015 （SBTi）. The coercive filed （Ec） and remnant polarisation （Pr） increase at first, then decrease with the increase of Fe doping content. At a maximum applied field of 229 kV/cm, the 2Pr reaches a maximum value of 91.1μC/cm2 at x = 0.05 and the corresponding Ec is 72 kV/cm. The 2Pr increases by about 260% and the Ec decreases by about 6%, respectively. Obviously, the ferroelectric property of SrBi4Ti4015 is greatly enhanced by Fe doping. The fatigueendurance characteristic of the SBFT-0.05 is not improved. After 1.1× 10^9 read/write cycles at a frequency of 50 kHz, the nonvolatile polarisations （Pnv = P＊ - P^） decreased about 48% of its initial value.

Galvanostatic anodic polarisation of WE43

The Mg corrosion mechanism was explored using galvanostatic polarisation curves,hydrogen evolution and weight loss.The data(a)were consistent with the existence of the uni-positive Mg+ion,(b)indicated that some hydrogen dissolved in the WE43 metal,and(c)indicated that self corrosion was more important than the applied current density in causing weight loss.

Can the Prior Cathodic Polarisation Treatment Remove the Air-Formed Surface Film and Is It Necessary for the Potentiodynamic Polarisation Test?

This paper clarifies two issues related to the prior cathodic polarisation treatment(PCPT) for the potentiodynamic polarisation test: whether PCPT can(1) remove the air-formed surface film and(2) affect the polarisation test results. X-ray photoelectron spectroscopy analyses of fluoride ion-labelled samples show that PCPT cannot remove the surface film completely due to the low reaction rate. Potentiodynamic polarisation tests demonstrate that PCPT with proper operating parameters,-1.0 V SCE for 5 min with subsequent open circuit potential(OCP) stabilisation in this study, is necessary because it can improve the test reproducibility without affecting the corrosion parameters by unifying the initial surface state. However, PCPT with lower potentials, longer time or no OCP stabilisation has significant effects on the electrochemical corrosion parameters due to the hydrogen absorption under the conditions of this study.

Multi-scale polarisation phenomena

Multi-scale methods that separate different time or spatial scales are among the most powerful techniques in physics,especially in applications that study nonlinear systems with noise.When the time scales(noise and perturbation)are of the same order,the scales separation becomes impossible.Thus,the multi-scale approach has to be modified to characterise a variety of noise-induced phenomena.Here,based on stochastic modelling and analytical study,we demonstrate in terms of the fluctuation-induced phenomena and Hurst R/S analysis metrics that the matching scales of random birefringence and pump–signal states of polarisation interaction in a fibre Raman amplifier results in a new random birefringence-mediated phenomenon,which is similar to stochastic anti-resonance.The observed phenomenon,apart from the fundamental interest,provides a base for advancing multi-scale methods with application to different coupled nonlinear systems ranging from lasers(multimode,mode-locked,random,etc.)to nanostructures(light-mediated conformation of molecules and chemical reactions,Brownian motors,etc.).

Ultra-broadband polarisation beam splitters and rotators based on 3D-printed waveguides

Multi-photon lithography has emerged as a powerful tool for photonic integration,allowing to complement planar photonic circuits by 3D-printed freeform structures such as waveguides or micro-optical elements.These structures can be fabricated with a high precision on the facets of optical devices and enable highly efficient package-level chip-chip connections in photonic assemblies.However,plain light transport and efficient coupling is far from exploiting the full geometrical design freedom offered by 3D laser lithography.Here,we extended the functionality of 3D-printed optical structures to manipulation of optical polarisation states.We demonstrate compact ultra-broadband polarisation beam splitters(PBSs)that can be combined with polarisation rotators and mode-field adapters into a monolithic 3D-printed structure,fabricated directly on the facets of optical devices.In a proof-of-concept experiment,we demonstrate measured polarisation extinction ratios beyond 11 dB over a bandwidth of 350 nm at near-infrared telecommunication wavelengths around 1550 nm.We demonstrate the viability of the device by receiving a 640 Gbit/s dual-polarisation data signal using 16-state quadrature amplitude modulation(16QAM),without any measurable optical-signal-to-noise-ratio penalty compared to a commercial PBS.

人体关节活动度测量系统

关节活动度是康复学中鉴定肢体伤残等级和评定关节康复程度的一项重要指标。目前常用的测量方法有通用量角器、照相法和X光,但这些方法在精度、稳定性和实时性方面都无法满足临床需要。本文提出了将光学定位设备NDI Polaris Spectra应用于人体关节活动度的测量,从而提高精确度、可重复性和实时性。本方法首先将反光小球固定在人体的骨性标志点上,然后利用NDI Polaris Spectra追踪反光小球的位置。NDI Polaris Spectra会将反光小球的三维坐标数据反馈给计算机,根据这些反光小球的三维坐标数据使用最小二乘法拟合出肢体运动的轨迹和轴心,从而计算出关节运动的角度。该方法测量结果的精度可以达到0.5°,标准差不超过0.02°,精度和稳定性都优于现有方法,足以满足临床需要。

Corrosion Behaviours of Copper Alloy in Solutions Containing Na_2SO_4 and NaCl with Different Concentrations

Potentiodynamic polarisation, potential-time measurements, X-ray diffraction (XRD) and infrared spectroscopy (IR) have been used to investigate the effect of different concentrations of Na2SO4 in the absence and presence of NaCI, on the corrosion of Cu-alloy. The electrochemical measurements showed that the increase of Na2SO4 concentration led to increase the corrosion current density of Cu alloy and vice versa. The presence of NaCI shifted the potential to more cathodic potential, which had a great influence on the protectiveness of the Cu oxide layer formed on the surface in presence of Na2SO4. The spectrometric measurements indicated the constituents of the film formed on the alloy surface were mainly Cu2O, in addition to the oxides, NiO and Fe2O3, which were traced by XRD analysis.

Linearly polarised three-colour lasing emission from an evanescent wave pumped and gain coupled fibre laser

A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fibre immersed in a dye solution of lower refractive index. The dye molecules around the bare fibre are excited by the evanescent waves of pump light when they propagate along the fibre in a total internal reflection. When the pump beam within the fibre is a meridian beam, the WGM lasing emission from the fibre laser is a linearly polarised transverse electric wave, while it is a mixed wave of the linearly polarised transverse electric and magnetic waves if the pump beam is a skew beam within the fibre. Because the excited molecules are located within the evanescent field of WGM, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fibre. Once the bare fibre is inserted into three glass capillaries filled with Rhodamine 6G, 610 and 640 dye solutions, respectively, WGM laser oscillations at the wavelengths of 567-575, 605-614 and 656-666 nm occur simultaneously, and a linearly polarised three-colour lasing emission is achieved in a single optical fibre.

Omnidirectional iridescence via cylindricallypolarized femtosecond laser processing

We report the femtosecond(fs)laser fabrication of biomimetic omnidirectional iridescent metallic surfaces exhibiting efficient diffraction for practically any angle of light incidence.Such diffractive behavior is realized by means of multi-directional low-spatial-frequency,laser-induced periodic surface structures(LSFL)formed upon exploiting the cylindrical symmetry of a cylindrical vector(CV)fs field.We particularly demonstrate that the multi-directional gratings formed on stainless steel surface by a radially polarized fs beam,could mimic the omnidirectional structural coloration properties found in some natural species.Accordingly,the fabricated grating structures can spatially disperse the incident light into individual wavelength with high efficiency,exhibiting structural iridescence at all viewing angles.Analytical calculations using the grating equation reproduced the characteristic variation of the vivid colors observed as a function of incident angle.We envisage that our results will significantly contribute to the development of new photonic and light sensing devices.

Wavelength dependence four-wave mixing spectroscopy in a micrometric atomic vapour

This paper presents a theoretical study of wavelength dependence four-wave-mixing （FWM） spectroscopy in a micrometric thin atomic vapour. It compares three cases termed as mismatched case I, matched case and mismatched case II for the probe wavelength less, equal and greater than the pump wavelength respectively. It finds that Dicke- narrowing can overcome width broadening induced by Doppler effects and polarisation interference of thermal atoms, and high resolution FWM spectra can be achieved both in matched and mismatched wavelength for many cases. It also finds that the magnitude of the FWM signal can be dramatically modified to be suppressed or to be enhanced in comparison with that of matched wavelength in mismatched case I or II. The width narrowing and the magnitude suppression or enhancement can be demonstrated by considering enhanced contribution of slow atoms induced by atom-wall collision and transient effect of atom-light interaction in a micrometric thin vapour.

Effect of added cobalt ion on copper electrowinning from sulfate bath using doped polyaniline and Pb-Ag anodes

Effect of added Co2 +(aq)on copper electrowinning was studied using doped polyaniline(Pani)and Pb-Ag(1%)anodes and a stainless steel cathode.The presence of added Co2+ (aq)in the electrolyte solution was found to decrease the anode potentials.The optimum level of Co2 +(aq)concentration in the electrolyte,with respect to the maximum saving of power consumption was established.Linear sweep voltammetry(LSV)was used to study the influence of added Co2 +(aq)on the anodic processes in a copper sulfate-sulfuric acid electrolyte.The oxygen-evolution potential for Pani anode is depolarised at lower current densities(≤0.01 A/cm2)and attains saturation atρ(Co 2+ )o≈0.789 g/L;whilst the oxygen-evolution potential for Pb-Ag(1%)anode is depolarised at higher current densities(≤0.02 A/cm2)and attains saturation atρ(Co 2+ )o≈1.315 g/L.The preferred orientations of the copper deposits change from(220)to(111)with the addition of 0.394?0.789 g/L Co 2+ but higher concentrations favor(220)orientation again.

Blood classical monocytes phenotype is not altered in primary non-small cell lung cancer

AIM: To evaluate the M1 and M2 monocyte phenotype in patients with non-small cell lung cancer(NSCLC) compared to controls. Also, to examine the expression of Th1 and Th2 cytokines in plasma of NSCLC vs controls. METHODS: Freshly prepared peripheral blood mononuclear cells samples were obtained from patients with NSCLC(lung adenocarcinoma and squamous cell lung carcinoma) and from non-cancer controls. Flow cytometry was performed to investigate M1 and M2 phenotypes in peripheral monocytes(classical monocytes CD14+, CD45+ and CD16-) using conventional surface markers. Th1 and Th2 cytokine production was alsoanalysed in the plasma using cytometric bead array technique. RESULTS: There were no significant difference in expression of M1(HLA-DR) and/or M2 markers(CD163 and CD36) markers on classical monocytes in patients with NSCLC compared to non-cancer controls. Expression of CD11 b, CD11 c, CD71 and CD44 was also shown to be similar in patients with NSCLC compared to noncancer controls. Th1 and Th2 cytokines [interleukin(IL)-1β, IL-2, IL-4, IL-5, IL-8, IL-10, IL-12(p70), tumor necrosis factor(TNF)-α, TNF-β, and interferon-γ] analysis revealed no significant difference between patients with NSCLC and non-cancer controls. CONCLUSION: This study shows no alteration in peripheral monocyte phenotype in circulating classical monocytes in patients with NSCLC compared to noncancer controls. No difference in Th1 and Th2 cytokine levels were noted in the plasma of these patients.

Effects of Anodizing Parameters in Tartaric-Sulphuric Acid on Coating Thickness and Corrosion Resistance of Al 2024 T3 Alloy

2024 T3 is one of aluminium alloys which are widely used in the aircraft structures. Anodizing of alluminium alloy in tartaric-sulphuric acid (TSA) electrolyte is developed to obtain more environmentally-friendly process and to produce anodize layer with better corrosion resistance. In this research work, the influences of anodizing parameters of Al 2024 T3 in TSA on the thickness, weight and corrosion resistance of the anodize layer are studied. Corrosion resistance test was carried out by conducting salt spray test for 336 hours and anodic polarization measurements using potentiostat. Results of three-factor analysis of variance (ANOVA) demonstrated that the most influencing factor that determines the thickness and weight of the anodize layer is temperature, followed by applied voltage, duration of anodizing, voltage-temperature interaction, interaction of temperature-duration of anodizing, interaction of voltage-temperature-duration of anodizing, and interaction of voltage and duration of anodizing. The pit density and corrosion current density (icorr) were found to be dependent on the coating thickness. The anodize layer with a thickness of higher than 3 μm was not experienced to pitting corrosion during 336 hours of salt spray test.

Propagation properties of electromagnetic fields in elliptic dielectric hollow fibres and their applications

We numerically calculate and analyse the electromagnetic fields, optical intensity distributions, polarization states and orbital angular momentum of some elliptic hollow modes in an elliptic dielectric hollow fiber （EDHF） by using Mathieu functions, and also calculate the optical potential of the blue-detuned eHE11 mode evanescent-light wave for ^85Rb atoms, including the position-dependent van der Waals potential, and discuss briefly some potential applications of our EDHF in atom and molecule optics, etc. Our study shows that the vector electric field distributions of the odd modes in the cross section of the EDHF are the same as that of the even modes and with different boundary ellipses by rotating an angle of π/2, and the orbital angular momentum （OAM） of single HE （EH） mode is exactly equal to zero, while that of dual-mode in the EDHF is fractional in h, and has a sinusoidal oscillation as z varies. The EDHF can be used to produce various elliptic hollow beams, even to generate and study various atomic vortices with a fractional charge and its fractional quantum Hall effect in atomic Bose Einstein condensate, and so on.

A hybrid model for the charging process of the amorphous SiO_2 film in radio frequency microelectromechanical system capacitive switches

Charging is one of the most important reliability issues in radio frequency microelectro- mechanical systems （RF MEMS） capacitive switches since it makes the actuation voltage unstable. This paper proposes a hybrid model to describe the transient dielectric charging and discharging process in the defect-rich amorphous SiO2 RF MEMS capacitive switches and verifies experimentally. The hybrid model contains two parts according to two different charging mechanisms of the amorphous SiO2, which are the polarisation and charge injection. The models for polarisation and for charge injection are established, respectively. Analysis and experimental results show that polarisation is always effective, while the charge injection has a threshold electric field to the amorphous SiO2 film. Under different control voltage conditions, the hybrid model can accurately describe the experimental data.

Electrochemical Investigation of Corrosion on AISI 316 Stainless Steel and AISI 1010 Carbon Steel: Study of the Behaviour of Imidazole and Benzimidazole as Corrosion Inhibitors

An electrochemical investigation of the corrosion on AISI 316 austenitic stainless steel and AISI 1010 carbon steel in sodium chloride solution (3.0 wt.%) was performed in the absence and presence of imidazole and benzimidazole corrosion inhibitors. The results showed that at any inhibitor concentration (25 ppm to 1000 ppm), there was an increase in the polarisation resistance of both steels. The highest efficiency of corrosion inhibition was obtained using imidazole at a concentration of 50 ppm for both steels, with values of 96% for the AISI 316 stainless steel and 73% for the AISI 1010 carbon steel.

利用Polmon实现Polaris航海模拟器的管理

我院从2002年起,前后引进了三套挪威KONSBERG公司的第六代船舶操纵模拟器产品:Polaris航海模拟器。Polaris模拟器是个复杂的大型计算机仿真系统,管理维护起来也很繁琐。本文介绍了如何利用Polmon实现Polaris模拟器集中、方便、快捷的管理。

Corrosion Rate and Scale of Cast Iron in Water Distribution Systems

A specialised electrochemical measurement cell was plugged into a pilot water distribution system to simulate the pipe inner-wall corrosion. The linear polarisation resistance(LPR) technique and electrochemical impedance spectroscopy(EIS) were measured in real time to study the variation of the corrosion rate(CR) and scale of cast iron. Three corrosion stages were observed according to the LPR analysis: an initial stage with significantly fluctuating CR, a developmental stage with slowly decreasing CR, and a stable stage with a low CR of approximately 0.157 5 mm·a^(-1). The EIS revealed that the scales with a compact outer layer and a porous inner layer finally formed in the stable stage, and the polarisation resistance was approximately 2 175 ?·cm^2. A physicochemical analysis of the scales showed that ferric oxides, oxyhydroxides and calcite made the outer layer compact and effectively limited the diffusion of oxygen through the scales, which resulted in a low CR.

Two-dimensional non-spatial filtering based on holographic Bragg gratings

The filter made up of two gratings performs as a two-dimensional non-spatial filtering. This paper reports that the volume Bragg gratings are fabricated by interfering two collimated coherent laser beams in photopolymer. Diffraction efficiency of a single grating is up to 78% in Bragg＇s condition, then a two-dimensional non-spatial filter, which consists of two volume Bragg gratings and a half-wave plate, enables the laser beam filtered in two dimensions with the diffraction efficiency of 54%. The Bragg＇s condition and effect of polarisation on performances of the two-dimension filter are also discussed.

Finite size effect of ions and dipoles close to charged interfaces

The modified dipolar Poisson-Boltzmann （MDPB） equation, where the electrostatics of the dipolar interactions of solvent molecules and also the finite size effects of ions and dipolar solvent molecules are explicitly taken into account on a mean-field level, is studied numerically for a two-plate system with oppositely charged surfaces. The MDPB equation is solved numerically, using the nonlinear Multigrid method, for one-dimensional finite volume meshes. For a high enough surface charge density, numerical results of the MDPB equation reveal that the effective dielectric constant decreases with the increase of the surface charge density. Furthermore, increasing the salt concentration leads to the decrease of the effective dielectric constant close to the charged surfaces. This decrease of the effective dielectric constant with the surface charge density is opposite to the trend from the dipolar Poisson Boltzmann （DPB） equation. This seemingly inconsistent result is due to the fact that the mean-field approach breaks down in such highly charged systems where the counterions and dipoles are strongly attracted to the charged surfaces and form a quasi two-dimensional layer. In the weak-coupling regime with the electrostatic coupling parameter （the ratio of Bjerrum length to Gouy-Chapman length） Ξ 〈 1, where the MDPB equation works, the effective dielectric constant is independent of the distance from the charged surfaces and there is no accumulation of dipoles near the charged surfaces. Therefore, there are no physical and computational advantages for the MDPB equation over the modified Poisson-Boltzmann （MPB） equation where the effect of dipolar interactions of solvent dipoles is implicitly taken into account in the renormalised dielectric constant.