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Salinispirillum sp. LH 10-3-1 was newly isolated from the alkali lake water samples collected in Inner Mongolia. In this study, a gene coding for D-lactate dehydrogenase from the strain LH 10-3-1 (SaLDH) was cloned and characterized. The recombinant enzyme was a tetramer with a native molecular mass of 146.2 kDa. The optimal conditions for SaLDH to reduce pyruvate and oxidize D-lactic acid were pH 8.0 and pH 5.0, at 25 °C. Cu2+ and Ca2+ slightly promoted the oxidation and reduction activities of SaLDH, respectively. To improve the stability of SaLDH, the enzyme was immobilized on Cu3(PO4)2-based inorganic hybrid nanoflowers. The results showed that the reduction activity of the hybrid nanoflowers disappeared, and the optimum temperature, specific activity, thermostability, and storage stability of the immobilized SaLDH were significantly improved. In addition, the biotransformation of D-lactic acid to pyruvate catalyzed by SaLDH and the hybrid nanoflowers was investigated. The maximum conversion of D-lactic acid catalyzed by the immobilized SaLDH was 25.7% higher than by free enzymes, and the immobilized SaLDH could maintain 84% of its initial activity after six cycles. [ABSTRACT FROM AUTHOR]

A numerical simulation model of a natural ventilation greenhouse is helpful for improving the production and quality of greenhouse crops in tropical areas. Field experiments show that the mean coefficient of variation of indoor light intensity in four seasons was lower than 10.0%. The highest indoor temperature reached 39.3 °C during summer, while the average indoor temperature ranged from 24 °C to 26 °C in the other three seasons. The average relative humidity in the greenhouse ranged from 76% to 87% annually, which was higher and more stable than that in the external environment. A three-dimensional steady-state numerical model of the greenhouse was established based on computational fluid dynamics. Under natural ventilation conditions, the maximum error between the simulated value and the measured value of the temperature in each measuring point was 5.90%. And the average relative error between the simulated and measured values was 3.0% in the range of 0.7−1.5 m of crop cultivation height. Finally, a numerical simulation of adding side windows and expanding the vents was carried out. The results show that these methods can homogenize the airflow distribution in the greenhouse and improve the utilization efficiency of natural ventilation without more mechanical system operations. [ABSTRACT FROM AUTHOR]

In this study, SnO2-Sb2O3/GAC particle electrodes were prepared using the dip-calcination method. The particle electrodes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET), thermogravimetric test and linear sweep voltammetry (LSV), which proved that the metal oxide was successfully loaded on the granular activated carbon and exhibited high electrocatalytic activity and thermal stability. The effects of initial pH, electrolytic voltage, electrolyte concentration, initial phenol concentration and particle electrode dosage on the performance of the three-dimensional (3D) electrocatalytic oxidation in phenol degradation were investigated. The results showed that under the optimal conditions, the removal rates of phenol and chemical oxygen demand (COD) were 99.65% and 67.16%, respectively. Finally, it was found that the novel particle electrodes had the ability of stable operation, maintaining high-efficiency operation no less than 15 times, which further highlights their robustness and durability. [ABSTRACT FROM AUTHOR]

Timely and accurate fault location for a 35-kVhigh-reliability distribution network is one of the key technologies to improve the safety and efficiency of distribution network operations. A novel fault location method of 35-kV high-reliability distribution network is proposed in this paper. First, the distributed multipoint fault location model is established based on the power structure of a 35-kV high-reliability distribution network. The distribution of voltage and current traveling waves along the lines is comprehensively considered in this model. Secondly, we analyze the influence of noise interference, analog-digital conversion frequency, and conversion bits on the location accuracy. The simulation method of noise and analog-digital conversion is proposed based on simulated samples. Then, a wavelet filter is used to reduce the influence of noise on the calibration of the traveling wave arrival time, and matrix modulus of S transform is used to identify the arrival time for the wave. Finally, the simulation model of a 35-kV high-reliability distribution network is established to analyze the location accuracy in the case of single-phase to ground via resistance, two-phase short-circuit to ground via resistance, and three-phase short-circuit faults. The simulation results indicate that the proposed method has high location accuracy under the above fault conditions. [ABSTRACT FROM AUTHOR]