[en] In this work, an electrochemical sensor coupled with an effective flow-injection amperometry (FIA) system is developed, targeting the determination of gallic acid (GA) in a mild neutral condition, in contrast to the existing electrochemical methods. The sensor is based on a thin electroactive poly(melamine) film immobilized on a pre-anodized screen-printed carbon electrode (SPCE*/PME). The characteristics of the sensing surface are well-characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and surface water contact angle experiments. The proposed assay exhibits a wide linear response to GA in both pH 3 and pH 7.0 phosphate buffer solutions (PBS) under the optimized flow-injection amperometry. The detection limit (S/N = 3) is 0.076 μM and 0.21 μM in the pH 3 and pH 7 solutions, respectively. A relative standard deviation (RSD) of 3.9% is obtained for 57 successive measurements of 50 μM GA in pH 7 solutions. Interference studies indicate that some inorganic salts, catechol, caffeine and ascorbic acid do not interfere with the GA assay. The interference effects from some orthodiphenolic compounds are also investigated. The proposed method and a conventional Folin–Ciocalteu method are applied to detect GA in green tea samples using the standard addition method, and satisfactory spiked recoveries are obtained. - Highlights: • A nitrogen-rich conducting polymer was used for electroanalysis of gallic acid. • The sensor exhibits excellent electrochemical activity in both acidic and neutral media. • Good analytical results in terms of low detection limit and wide linear range are obtained. • The flow-injection amperometric assay is highly stable for continuous 57 replicates measurement (RSD = 3.9%). • The assay shows good recovery for green tea samples.

[en] Highlights: • A novel overoxidized poly(3,4-ethylenedioxythiophene) film is obtained. • The film structure favors the adsorption of dopamine. • The sensor is able to detect dopamine in the presence of ascorbic acid (1000X). - Abstract: An overoxidized poly(3,4-ethylenedioxythiophene) film-modified screen-printed carbon electrodes (SPCE/PEDOT_o_x) was prepared and characterized by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle techniques. The obtained film is a porous structure with highly abundant oxygen functionality. The SPCE/PEDOT_o_x could adsorb cations strongly and perform catalytic oxidation of biomolecules. The potential-induced adsorption of dopamine was observed for SPCE/PEDOT_o_x. A simple medium-exchange procedure was developed for the selective determination of dopamine by the use of the dopamine-adsorbed electrode. Under optimal differential pulse voltammetry (DPV), the proposed assay can be employed in the determination of submicromolar concentration of dopamine without the coexisting interferences of ascorbic acid (1000-fold) and uric acid (10-fold)

[en] The gas-liquid counter-current flow limitation (CCFL) is closely related to efficient and safety operation of many equipment in industrial cycle. Air-water countercurrent flow experiments were performed in a tube with diameter of 25 mm to understand the triggering mechanism of CCFL. A parallel electrode probe was utilized to measure film thickness whereby the time domain and frequency domain characteristics of liquid film was obtained. The amplitude of the interface wave is small at low liquid flow rate while it becomes large at high liquid flow rate after being disturbed by the airflow. The spectral characteristic curve shows a peak-shaped distribution. The crest exists between 0 and 10 Hz and the amplitude decreases with the frequency increase. The analysis of visual observation and characteristic of film thickness indicate that two flooding mechanisms were identified at low and high liquid flow rate, respectively. At low liquid flow rate, the interfacial waves upward propagation is responsible for the formation of CCFL onset. While flooding at high liquid flow rate takes place as a direct consequence of the liquid bridging in tube due to the turbulent flow pattern. Moreover, it is believed that there is a transition region between the low and high liquid flow rate

[en] The fabrication of metal film steps used in equation of state experiment targets was investigated. The metal film step of hundreds of microns width was cut by picosecond laser processing technology. The factors of generating heat effect in the processing were analyzed. The processing parameters were as follows: power 0.5 W, pulse width 10 ps, wavelength 355 nm, and scanning speed 100 mm/s. Two metal films of 400 and 120 microns width were obtained in the experiment. The measurement results show that the width of metal film can be precisely controlled and the quality of metal film surface before and after cutting was the same. (authors)

[en] A line velocity interferometer for any reflector has been implemented at the Shenguang-II laser facility. This instrument is the primary diagnostic for a variety of experiments involving laser-driven shock-wave propagation,materials characterization experiments and shock timing experiments. It measures velocities of interfaces, free surfaces and shock fronts traveling through transparent media. It can measure shock breakout time at temporal resolutions as low as 20 ps, and spatial resolution 10 μm. Experiments were carried out on the Shenguang-II laser facility and high quality interference images were obtained. (authors)

[en] In this paper, the development of nuclear targets for nuclear reaction experiments in the Institute of Atomic Energy, Peking, China, is described. The techniques of vacuum evaporation, electroplating and isotopic material produced by electromagnetic isotope separators are discussed. The number of different kinds of targets produced are about thirty and they are in the thickness range of a few μg/cm₂ to several mg/cm₂. About one-hundred isotopes of twenty-six elements have been produced in this Institute

[en] Measurement of shock temperature under high temperature and high pressure is an essential part of equations of state(EOS) research. This paper introduces a temperature diagnosis system for laser-driven shock wave experiment on the basis of SG-Ⅱ high-power laser facility. The system comprised the streaked optical pyrometer (SOP) which is high time-resolved and the spectral resolved SOP (SSOP). The VISAR system was added to measure emissivity. The on-line calibration system of temperature measurement was established simultaneously using a NIST traceable standard lamp. High time-resolved signal images of the high temperature radiation spectrum were obtained through experiments driven by high power laser on aluminum using the diagnosis system. The shock temperature of aluminum was obtained according to gray body radiation theoretical model. The measured temperature was 2.95 eV, which was close to Hugoniot temperature in SESAME library at the same shock wave velocity. The experiment result indicates that the temperature measurement system used in the experiment can diagnose the shock temperature of metallic materials effectively. (authors)

[en] Liquid hydrogen and deuterium have abundant electrical and optical properties at high pressure. A simple model to calculate the conductivity of low-Z materials was constructed. Combining the model with experiment, this paper introduces the study of the ionization and conductivity of liquid deuterium at around 70 GPa. The results show that, deuterium at this range of pressure has an ionization about 0.067%, conductivity about 2.87 × 10⁵(W·m)^-1, which means the shocked deuterium reaches a conducting state with characteristic of metallic fluid. Apparently, the transition from the insulating molecular state to metallic state of deuterium begins at a lower pressure. (authors)

[en] We report the diffusion behavior of dimer vacancies on a Si(100)-(2×1) surface by using ultrahigh-vacuum scanning tunneling microscopy. The dimer vacancies are created by oxygen etching of Si atoms at elevated temperatures. By annealing the sample at 600–750 °C, the dimer vacancies uniformly distribute on the terrace nucleate to form larger elongated voids of one atomic layer deep. The long axis of these voids is parallel to the Si dimer rows. During annealing, the surface morphology evolves in a way dominantly caused by the anisotropic diffusion of the dimer vacancies. A difference of diffusion barriers of 0.17±0.09eV is obtained between the [110] and [11-bar0] directions. (condensed matter: structure, mechanical and thermal properties)

[en] A line-imaging optically recording velocity interferometer system (L-ORVIS) fitting the high-strain rate motion of solids as in shock wave experiments requires a high power single-mode laser. We have put forward a new illumination method which can increase threefold the luminosity of such a diagnostic. A modified illumination system is applied to the L-ORVIS which was implemented at 'Shenguang-II' laser facility. The modified L-ORVIS is applied to laser-driven shock wave experiments and platinum Hugoniots were obtained at both high pressure and low pressure