Ion and solvent transfer discrimination at a nickel hydroxide film exposed to LiOH by combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) techniques

A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers associated with the redox processes of thin (Γ100–150 nmol cm⁻²) α- and β-nickel hydroxide films exposed to aqueous LiOH solution. A comparison of the measured PBD signal with the predicted PBD profiles, calculated by temporal convolution analysis of the current and mass responses, enabled the contributions to redox switching of anion (OH⁻) and solvent (H₂O) transfers to be discriminated quantitatively. The responses from the combined instrument are reconciled in terms of H⁺ deintercalation/intercalation within the nickel hydroxide structure as OH⁻ ions enter/exit the film. Hydroxide ion movement is associated with a counterflux of water. Thin nickel hydroxide films show a gradual α→β phase transformation with continuous voltammetric cycling, especially when the films are exposed to high concentrations of electrolyte. α-Films are characterised by OH⁻ transfers that dominate the H⁺ and H₂O movements; β-films are characterised by an increased participation of water and protons to the exchange dynamics.     

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum mutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate (omega(Q) = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.     

Manipulation of tunneling induced transparency windows and optical switching features in fivefold quantum dot molecules

Transient and steady-state behavior of the probe absorption in a multiple quantum dot (QD) molecule composed of five quantum dots molecules (with a center dot and four satellite dots) is explored with application in all-optical switching. We find that the absorption spectra of the light pulse can be efficiently modified via the effect of inter-dot tunnel couplings of QDs and incoherent pumping field. Results show that depending on the values of system parameters, at least one and at most four tunneling induced transparency (TIT) windows can be established in the multiple QD medium. We then investigate the dynamical behavior of the probe absorption-amplification as well as the optical switching in pulsed regime. By adjusting the incoherent pumping rate, the required switching time for changing the gain to the absorption or vice versa is then estimated approximately to be 20.7 nanosecond (ns), that is an appropriate time for such a QDM-based switch.     

Determination of Adrenaline by Atomic Absorption Spectrometry Using Copper as Probe Reagent in Pharmaceutical and Serum Samples

In this paper, an atomic absorption spectrometric method has been established to determine adrenaline using Cu(II) as probe reagent. In the presence of SCN^?, it has been demonstrated that Cu(II) is reduced to Cu(I) by adrenaline at pH 6.0, and the in situ formed Cu(I) reacts with SCN‐ to form the white emulsion of CuSCN. According to the amount of residual Cu(II) which is measured by atomic absorption spectrometry, the amount of adrenaline can be determined indirectly. Beer's law is obeyed in the range of adrenaline concentration of 0.080‐6.00 mg mL‐1, and the linear regression equation is A = 0.20342 ‐ 0.02756C (μg mL^?1) with a correlation coefficient of 0.9998. The detection limit is 0.033 μg mL^?1 and R.S.D. is 0.56%. This method has been successfully applied to determine adrenaline in pharmaceutical and serum samples with satisfactory results.     

基于探针的端到端设备故障检测模式

随着宽带、VoIP、IPTV、大客户网络等应用的大范围普及，用户感知层面的服务保障要求越来越高。基于主动发现式网络检测，降低投诉量，帮助客户服务人员改善一次性派单成功率，集成整合现网诊断手段，智能排障，降低故障定位和解决时间。本文基于中国联通的接入网现状，以软件系统辅助探针部署的方式，探索一种有效的主动式端到端设备故障检测模式，丰富并完善运营商故障检测诊断手段。     

脉冲放电止裂后裂尖处纳米尺度下的力学性能测试

应用扫描探针显微镜SPM(scanning Probe Microscopy)，对经过脉冲放电止裂后的40Cr模具钢裂尖处的组织进行了纳米尺度下的力学性能测试。测试结果表明：脉冲放电不仅使裂纹尖端钝化，同时使围绕裂尖处组织的细观硬度和细观杨氏弹性模量得到了提高，与宏观观测和分析规律相符，纳米尺度下微观力学性能测试结果为脉冲放电裂纹止裂技术的工程应用提供了微观尺度下的证据。     

Simple and Sensitive Electrochemical DNA Detection of Primer Generation‐Rolling Circle Amplification

A new electrochemical sequence‐specific DNA detection platform based on primer generation‐rolling circle amplification (PG‐RCA), methylene blue (MB) redox indicator, and indium tin oxide (ITO) electrode is reported. In the presence of a specific target sequence, PG‐RCA, an isothermal DNA amplification technique, produced large amounts of amplicons in an exponential manner. In addition to the standard components, the reaction mixture contained MB, which bound with the PG‐RCA amplicons. End‐point electrochemical measurement by differential pulse voltammetry (DPV) was performed using ITO electrode. The amplicon‐bound MB resulted in a lower DPV signal than free MB due to a smaller diffusion coefficient as well as electrostatic repulsion between the negatively charged amplicon‐bound MB and ITO electrode. With simple assay design (recognition probe) and instrumentation (operating temperature at 37 °C and ITO electrode without the need for probe immobilization), this detection platform is well suited for point‐of‐care and on‐site testing. Real‐time measurement was also achieved by pretreating the ITO electrode with bovine serum albumin.     

Control of the probe absorption via incoherent pumping fields in asymmetric semiconductor quantum wells

In a three-level asymmetric semiconductor quantum well system, owing to the effects that result from the incoherent pumping fields, the probe absorption of probe field can be effectively controlled. The result is achieved by applying the two incoherent pumping fields, so it is different from the conventional way in ordinary laser-driven schemes that coherent driving fields are necessary to control the probe absorption. Otherwise, our study is much more practical than its atomic counterpart due to its flexible design and the controllable interference strength. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.     

An alternative optical method of determining the unknown microwave frequency by the use of electro-optic materials and semiconductor optical amplifier

There are found different established methods for measuring the frequency of an unknown microwave signal. Several resonating and electronic methods are found where the frequency of a microwave is measured with good performances, where each method has its own advantage. Here in this communication the authors propose a new concept of measuring the frequency of unknown microwave with the joint uses of reflecting semiconductor optical amplifier (RSOA) and electro-optic Pockel cell. To measure the frequency a known microwave source of variable and calibrated frequency is also required. Then with the help of a RSOA and electro-optic material one can find the unknown microwave frequency more accurately than that of any conventional mechanism. This method can extend a high degree of accuracy as optics is used to measure the unknown microwave frequency. As optical signal has million time greater frequency than that of microwave signal therefore a high degree of accuracy of frequency measurement is achieved. The electro-optic material takes the role of phase modulation for splitting an optical wave into several frequencies.     

Experimental study of carbon materials behavior under high temperature and VUV radiation: Application to Solar Probe+ heat shield

The aim of the Solar Probe Plus (SP+) mission is to understand how the solar corona is heated and how the solar wind is accelerated. To achieve these goals, in situ measurements are necessary and the spacecraft has to approach the Sun as close as 9.5 solar radii. This trajectory induces extreme environmental conditions such as high temperatures and intense Vacuum Ultraviolet radiation (VUV). To protect the measurement and communication instruments, a heat shield constituted of a carbon material is placed on the top of the probe. In this study, the physical and chemical behavior of carbon materials is experimentally investigated under high temperatures (1600-2100 K), high vacuum (10⁻⁴ Pa) and VUV radiation in conditions near those at perihelion for SP+. Thanks to several in situ and ex situ characterizations, it was found that VUV radiation induced modification of outgassing and of mass loss rate together with alteration of microstructure and morphology.