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The electrochemical behavior of carbon steel in high pressure CO2-containing formation water was studied by in situ electrochemical measurements in an autoclave. According to a thermodynamics model, the equilibrium concentrations of various species and the equilibrium potentials of various electrode reactions were calculated to determine the possible electrode reactions. Electrochemical measurements show that in the initial stage, the impedance spectra exhibit three time constants, i.e., capacitive semicircle at high frequency, inductive semicircle at intermediate frequency and capacitive semicircle at low frequency. As corrosion proceeds, the inductive semicircle shrinks and the capacitive semicircle at low frequency enlarges. Impedance spectra exhibit double capacitive semicircles later. In the last stage, Warburg impedance representing diffusion effect appears at low frequency. The electrochemical mechanism is closely related to the formation process of corrosion scales. [ABSTRACT FROM AUTHOR]

Nanocrystalline (Ni0·5Zn0·5)xCo1-xFe2O4 with 0&les;x&les;1·0 are prepared by spraying co-precipitation method. Their microstructure and magnetic properties are investigated. The results show that nanocrystalline (Ni0·5Zn0·5)xCo1-xFe2O4 ferrites are spinel phase. Coercivity and retentivity of specimens increase with cobalt content. The enhancement of the saturation magnetisation up to a maximum value of 102·1 A m2 kg-1 in nanocrystalline (Ni0·5Zn0·5)0·5Co0·5Fe2O4 ferrite is observed. This can be attributed to the change of the net magnetic moment between the sublattices of structure for the substitution of Ni2+ and Zn2+ ions with Co2+ ions. The coercivity of nanocrystalline (Ni0·5Zn0·5)0·5Co0·5Fe2O4 ferrite increases monotonously in the grain size regime d<69 nm, and then coercivity decreases with grain size. The initial increase in coercivity of the nanocrystalline (Ni0·5Zn0·5)0·5Co0·5Fe2O4 ferrite with increasing size is due to the enhanced role of the surface and its strong random anisotropy. [ABSTRACT FROM AUTHOR]

Inhibition performance and adsorption behaviour of lauric acid in acidic and near neutral environments were investigated by electrochemical and surface analysis methods. The results showed that the inhibition ability and the minimum effective inhibitor concentration are both pH dependent. The former decreased and the latter increased with pH value. The adsorption of the inhibitor was the predominant mechanism at lower pH values, with the formation of a protective adsorption film. At higher pH value, the inhibitor cannot prevent the corrosion process effectively and hence the adsorption of the inhibitor and formation of FeCO3 like corrosion product coexisted. The difference of inhibition performance can be ascribed to the different adsorption state of the inhibitor on metal surface at different pH value resulting in a different interaction with the metal surface, which was validated by vibrational spectroscopy (attenuated total reflection Fourier transform infrared spectroscopy). [ABSTRACT FROM AUTHOR]

Objective: To investigate the current status and influencing factors of occupational stress among couriers. Methods: Couriers ( n =925) were selected on this study used cluster sampling method from January to March 2018. They were from SF and Zhongtong Express Co., Ltd., on the Wechat platform, and surveyed by a job stress questionnaire based on a job demand-control model.Valid questionnaires( n =617) were obtained. Results: A total of 418 workers were occupational stress positive (67.7%). The results of Chi-square analysis showed that there were significant differences in occupational stress among workers categorized by job position, working years, mealtime, sleeping time, and weekly work time ( P <0.05). The multivariate logistic analysis indicated that non-regular meals, short-term sleep and less than 0.5 working years were risk factors for occupational stress( P <0.05). Conclusion: Couriers generally have occupational stress. The main influencing factors are job position, working years mealtime, sleeping time, and weekly work time. It is necessary to guide healthy lifestyle, rationally organize labor and assign tasks, and improve working environment to relieve their occupational stress.

Using the detailed configuration accounting with the term structures treated by the unresolved transition array model, we have presented a method to calculate the spectral-resolved opacity for high temperature and density plasmas. Due to the fully relativistic treatment, incorporated with the quantum defect theory to handle the huge number of transition arrays from configurations with high principal quantum number, we can calculate the opacity of any medium- and high-Z plasmas conveniently. In the present work, the frequency-dependent opacity and the Rosseland mean opacity are calculated for a mixture of gold and gadolinium at a high temperature, 250 eV, and three densities, 0.1 g/cm(3), 1.0 g/cm(3), and 10.0 g/cm(3). Agreement between our theoretical results and experimental measurements and other theoretical simulations is obtained.

Objective: To develop an instrument used in measurement of physiological parameters in laboratories or field. Method A: computer was used to process data in the telemetry system. The frequency-time division modulation technique was adopted. The low frequency signals were directly connected to the computer serial port after demodulation, and measurement control was achieved by single-chip computer. Temperature measurement results were obtained by conversion table., Result: It is capable of telemeter and processing ECG, wind speed and temperature signals in real-time. Good results were gained in high temperature condition and -17 degrees C environment., Conclusion: The instrument has many advantages, such as high accuracy, good processing ability, reliability, long operation distance, small volume and easy operation.

Aminoacylase from Aspergillus oryzae was adsorbed on functionallized macroporous copolymers where the enzyme showed excellent catalyzing activity and operation stability. Various factors which effect the activity of the immobilized aminoacylase such as temperature, pH and ionic strength were investigated. The continuous operation of the enzyme immobilized on macroporous copolymers was compared with that of the enzyme immobilized on DEAE-Sephadex.

The aminoacylase from Aspergillus oryzae was adsorbed on polymer carriers where the enzyme showed excellent catalyzing activity and operating stability. It was found that the pore structure and functional group were the basic factors which affected the activity of the adsorbed enzyme. The hydrophobility of the carriers did not play an important role in the enzymatic resolution. Various factors, such as percentage and nature of cross-linking agent, porogenic agents and functionalizing agents which controlled the pore structure and properties of the polymer carriers during their preparation, were investigated and relationship between the activity of the adsorbed aminoacylase and the carrier structure was also discussed.