In this work, Fe3O4 nanoparticles (NPs) were synthesized by reverse microemulsion method. After that, in a strong alkaline environment, the Fe3O4 NPs were coated with l3-cyclodextrin (l3 -CD). Then y-glycidoxypropyl-trimethoxysilane (KH560) was used to modified Fe3O4@l3-CD NPs to obtain Fe3O4@l3-CD-g-KH560 NPs. Through the click reaction between the epoxy group of KH560 and the amino group of Penicillin G acylase (PGA), the covalent immobilization of PGA was realized under mild conditions. The results showed that the enzyme activity (EA), enzyme activity recovery (EAR) and maximum loading (ELC) of immobilized PGA were 28242 U/g, 84 % and 112 mg/g, respectively. Its enzyme activity was kept at 43 % after repeated use for 4 times. Afterwards, in the process of l3 -CD coating Fe3O4 NPs, Mn2+ doped, and Scanning electron microscopy -Energy dispersive spectrometer (SEM-EDS) was used to scan the metal ion doped sample. The results showed that Mn2+-Fe3O4@l3-CD-g-KH560 NPs performed higher EAR and reusability (Ra (%)) than Fe3O4@l3-CD-g-KH560 NPs. The immo-bilized PGA performed higher EAR and reusability, i.e. its EA, EAR and ELC were 31528 U/g, 94.2 % and 105 mg/ g, respectively, and 72 % of the original enzyme activity was remained after repeated use for 11 times. Furthermore, the structures of the magnetic composites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Vibrating sample magnetometer (VSM) and Transmission electron microscopy (TEM).

Based on the beneficial effects of magnesium ions on biomolecules, it was first introduced into enzyme immobilization carriers to promote the comprehensive performance of immobilized enzymes in repeated use. Firstly, Fe3O4 nanoparticles (NPs) were prepared by the inverse microemulsion method, then, Mg2+ was doped in the process of coating beta-cyclodextrin (beta-CD) on the surface of Fe3O4 NPs. Afterward, through acetal reaction, glutaraldehyde (GA) was grafted to the material's surface to obtain Mg2+-Fe3O4 @ beta-CD-g-GA NPs, and covalent bond immobilization of Penicillin G acylase (PGA) was realized by the Schiff base reaction of the carriers' aldehyde group and PGA's amino group. After optimization of process conditions, the results show that the performances of the immobilized PGA achieve the best, when the concentration of the enzyme solution is 3.00 vol%, pH is 8.0, the immobilization time is 30 h, and the immobilization temperature is 37 C. Its enzyme activity recovery (EAR), enzyme activity (EA) and enzyme loading capacity (ELC) are 95.6%, 31997 U/g, 110 mg/g, respectively. Lastly, the operational stability, reusability, and storage stability of Mg2+-Fe3O4 @ 8-CD-g-GA-PGA NPs were researched. Relative to free PGA, immobilized PGA has better operation stability and storage stability. After 11 repeated uses, the immobilized PGA still has 56% of the initial vitality, and the carrier recovery (R-e) is 86.6%.

In order to utilize and dispose vegetable wastes（VWs） by ensiling in a timely and safe manner, the aim of this work is to investigate the inoculation of Lactobacillus plantarum（LP） on the ensiling quality of cauliflower wastes at different temperature（20℃,25℃,30℃,35℃,40℃ and 45℃） in terms of organic components, fermentation quality and microbial community.On this basis, the correlation between microbial community and ensiling quality parameters during ensiling were established.The addition of LP can significantly increase the content of dry matter, crude protein and lactic acid accompanied by the decrease of pH and ammonia nitrogen content for the silages.The dry matter, soluble carbohydrate and crude protein contents in LP were significantly higher than those in the control group（no additive, CK） under medium and low temperatures（20～35℃）.the contents of lignocellulosic fractions such as neutral detergent fiber, acid detergent fiber and cellulose in LP group were significantly higher than those in CK,which resulted in the significant decrease for relative forage value under high temperatures（40℃ and 45℃）.The ratios of lactic acid/acetic acid and lactic acid/total organic acid in LP were lower than those in CK,indicating that the fermentation intensity of lactic acid bacteria in LP was weakened at high temperature.Firmicutes in silages were dominant at phyla, and the abundance of lactic acid bacteria（LAB） in LP was significantly higher than that in CK（except 45℃）,especially the abundance of LAB in LP exceeded 90% at 30℃ and 35℃,indicating that a well lactic acid fermentation was formed, which suppressed the undesirable microorganisms.Lactobacillus is the main genus of LAB,and its abundance is negatively correlated with the content of neutral detergent fiber and acidic detergent lignin, and positively correlated with the content of lactic acid.In conclusion, the temperature and Lactobacillus plantarum had a significant effect on the ensiling quality, the ensiling of cauliflower wastes inoculated with lactobacillus plantarum at middle-low temperature could effectively improve the ensiling quality and relative feed value.Therefore, the ensiling disposition of cauliflower wastes at 20～35℃ was recommended preferentially.

When lightning strikes the transmission tower, lightning current is shunted between the ground wires and the tower. The shunting changes the current waveform in the tower, which may affect the potential rise of the tower and the grounding device. A field test is conducted on a 220 kV transmission line and the characteristics of lightning current shunting are obtained in this paper. The test results are compared with the simulation results, which verifies the feasibility of the commonly used simulation models. The main influencing factors of the shunting are discussed. The results show that the current in the tower changes obviously in our case compared to the applied impulse current. The high frequency components of the impulse current mainly enter the tower, which leads to a steeper current waveform in the tower. The difference is closely related to the waveform of the applied impulse current. The slower the impulse current waveform, the greater the difference between the front time and amplitude of the current in the tower and that of the original impulse current. Although part of the current flows along ground wires, this phenomenon may put forward higher requirements for the tower grounding device.

In order to explore the effect of various factors on the lightning withstand level of transmission line, taking 110kV transmission line as an example, the simulation calculation model is established in ATP-EMTP software according to the actual line tower type, line structure and other parameters, the flashover model is established with 50% flashover voltage of insulator string as the index, and the flashover of insulator string is taken as the measure index of lightning withstand level, This paper analyzes the effect of tower grounding resistance value, insulation level, i.e. the number of insulators, whether to install arresters and the number of lightning wires on the lightning withstand level of 110kV voltage grade transmission lines, and summarizes the law of improving the lightning withstand level of transmission lines, which is helpful to guide the transmission lines to improve the lightning withstand level in engineering practice and for the lines with different voltage grades To provide reference.

In order to disclose the effect of soil on the corrosion of earthing metal materials in power grid in Shaanxi Province, 152 stations with related soil environment are selected, and the corrosion data of four earthing metal materials including carbon steel, hot-dip galvanized steel, copper and copper-clad steel in different substations and external environments are measured. Then the average corrosion rate of four kinds of earthing metal materials in Shaanxi is calculated by weighing experiment. Based on geographic data information system (GIS), the environmental soil corrosion rate map of metal materials is drawn, and the average corrosion rate of earthing metal materials in substations of different cities in Shaanxi Province is compared and analyzed. Simultaneously, the main factors affecting the corrosion of metal materials are analyzed combining with soil properties parameters. The results show that the average annual soil corrosion rate of eastern region is higher than that of western area in Shaanxi Province after the earthing metal material buried one year. The average corrosion rate of copper and hot dip galvanized steel is slower than that of carbon steel. Comparatively, the corrosion rate in the substation is higher than that outside the station, and soil moisture, pH and chloride content have obvious effects on the corrosion rate. This result can provide reference for the design of earth power grid in Shaanxi Province.

So far, many control algorithms have been developed for singularly perturbed systems. However, in many industrial processes, enforcing closed-loop fast-slow dynamics for peculiarly nonseparable ones is a prior request and a crucial issue to be resolved. Aiming at the above problem, this article presents two dual-level model predictive control (MPC) algorithms for multitimescale dynamical systems with unknown bounded disturbances and input constraints. The proposed algorithms, each one composed of two regulators working in slow and fast time scales, are designed to generate closed-loop separable dynamics at high and low levels. As a prominent feature, the proposed algorithms are not only suitable for singularly perturbed systems but also capable of imposing separable closed-loop performance for dynamics that are nonseparable and strongly coupled. The recursive feasibility and convergence properties are proven under suitable assumptions. The simulation results on controlling a boiler turbine (BT) system, including the comparisons with other classic controllers, are demonstrated, which show the effectiveness of the proposed algorithms.

A reliable high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the simultaneous detection of zearalenone-14-glucoside (ZEN-14G) and its metabolite, zearalenone (ZEN), in the plasma, urine, and various tissues of rats. The performance of the developed method was validated by determining the selectivity, linearity (R2 > 0.99), sensitivity (lower limit of quantification, 0.1–1 μg/L), recovery (80.7 ± 3.0–112.3 ± 3.1%), precision (0.6–16.5%), and stability (81.7 ± 1.7–104.1 ± 3.9%). Through use of the methodological advances, the subsequent kinetics and distribution after administration of ZEN-14G by gavage were thoroughly investigated. ZEN-14G and ZEN exhibited similar trends in the plasma, and reached their peak concentrations at 10 min and then rapidly decreased. ZEN-14G could be quantified in the stomach, small intestine, and large intestine 24 h after administration, while ZEN was detectable in all tested tissues. Interestingly, ZEN-14G (7.6 ± 3.0 μg/L) and ZEN (977.5 ± 98.0 μg/L) were also detected in the urine 24 h after administration, indicating that ZEN-14G was prone to be slowly and continuously hydrolyzed into ZEN to be absorbed into the plasma and distributed to various tissues, thus leading to a cumulative exposure. Continuous attention should be paid to the co-exposure of ZEN and ZEN-14G, which might pose additional health risks to humans and animals.

When a lightning strikes a substation, transient disturbance will affect the secondary cable on the grounding grid through the uneven ground potential distribution and the mutual inductance between the cable and the ground grid. In this paper, a numerical method to calculate the transient disturbance in the secondary cable is presented. Based on the method of moments, a circuit model of grounding grid is developed taking into consideration the mutual inductance between the secondary cable and the ground conductor, while a transmission line model of the secondary cable is established with the consideration of uneven ground potential distribution and the mutual inductance between the secondary cable and the ground conductor. Then, the two models are unified. Simulation results show that the mutual inductance between the double end grounded cable and the grounding conductors greatly affects the transient disturbance in secondary cable. While the uneven potential distribution mainly affects that by forming a potential difference between both ends of the cable and the ground grid.

针对场磨式三维电场传感器产生的信号微弱、信噪比不足,且存在零点漂移等现象,导致无法进行有效的A/D转换的问题,研究了一种包含I-V积分变换电路、差分放大电路以及偏置电路的放大电路,对传感器产生的微弱信号进行放大、平移处理达到A/D转换要求.通过Multisim 12.0仿真对I-V积分变换电路中的反馈电阻与积分电容的参数进行优化,优化了电路的通频带的中心频率和带宽;设计了一种二级差分放大电路及偏置电路,满足了信号的A/D转换要求.将场磨式三维电场传感器的输出信号经过设计的放大电路进行实际测试,实验证明了本电路有效提高了信号放大电路的灵敏度,提高了信号的信噪比,同时提高了电路的抗干扰能力.

In this work, Fe3O4 nanoparticles (NPs) were synthesized by reverse microemulsion method. After that, in a strong alkaline environment, the Fe3O4 NPs were coated with β-cyclodextrin (β-CD). Then γ-glycidoxypropyltrimethoxysilane (KH560) was used to modified Fe3O4@β-CD NPs to obtain Fe3O4@β-CD-g-KH560 NPs. Through the click reaction between the epoxy group of KH560 and the amino group of Penicillin G acylase (PGA), the covalent immobilization of PGA was realized under mild conditions. The results showed that the enzyme activity (EA), enzyme activity recovery (EAR) and maximum loading (ELC) of immobilized PGA were 28242 U/g, 84 % and 112 mg/g, respectively. Its enzyme activity was kept at 43 % after repeated use for 4 times. Afterwards, in the process of β-CD coating Fe3O4 NPs, Mn2+ doped, and Scanning electron microscopy - Energy dispersive spectrometer (SEM-EDS) was used to scan the metal ion doped sample. The results showed that Mn2+-Fe3O4@β-CD-g-KH560 NPs performed higher EAR and reusability (Ra (%)) than Fe3O4@β-CD-g-KH560 NPs. The immobilized PGA performed higher EAR and reusability, i.e. its EA, EAR and ELC were 31528 U/g, 94.2 % and 105 mg/g, respectively, and 72 % of the original enzyme activity was remained after repeated use for 11 times. Furthermore, the structures of the magnetic composites were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Vibrating sample magnetometer (VSM) and Transmission electron microscopy (TEM).

The traditional process of measuring a three-dimensional (3D) electric field in the atmosphere may suffer from limited accuracy of the electric field component intensity due to multiple factors, such as the 3D electric field sensor’s pose change due to the sensor-carrier motion and the non-parallel positions between the 3D electric compass and field sensor’s measurement axes. Thus, this paper proposes a modified 3D electric field directional decomposition algorithm to overcome this problem. Specifically, the developed solution utilizes a parameter identification and fine-tuning scheme that solves the inaccurate measurement problem caused by the non-coaxial 3D positions between the electric field sensor and the compass. The measurement results highlight that the proposed method eliminates the instability of the electric field intensity measurement errors caused by the 3D electric field sensor changes because the measurement accuracy of the corrected electric field component intensity does not change with the sensor’s rotation angle. Our technique reduces the measurement error of the electric field intensity originating from the non-parallel position 3D electronic compass and field sensor measurement axes, further improving the measurement accuracy of the atmospheric field intensity.

The mechanical properties of resin samples in low-force stereolithography additive manufacturing were affected by the printing orientation, and were investigated and optimized to achieve excellent single or comprehensive tensile strength, compressive strength, and flexural modulus. The resin samples were fabricated using a Form3 3D printer based on light curing technology according to the corresponding national standards, and they were detected using a universal testing machine to test their mechanical properties. The influence of the printing orientation was represented by the rotation angle of the resin samples relative to the x–axis, y–axis and z–axis, and the parameters was selected in the range 0°–90° with an interval of 30°. The multiple regression models for the mechanical properties of the prepared resin samples were obtained based on least square estimation, which offered a foundation from which to optimize the parameters of the printing orientation by cuckoo search algorithm. The optimal parameters for the tensile strength, compressive strength and flexural modulus were ‘α = 45°, β = 25°, γ = 90°’, ‘β = 0°, β = 51°, γ = 85°’ and ‘α = 26°, β = 0°, γ = 90°’, respectively, which obtained the improvements of 80.52%, 15.94%, and 48.85%, respectively, relative to the worst conditions. The mechanism was qualitatively discussed based on the force analysis. The achievements obtained in this study proved that optimization of the printing orientation could improve the mechanical properties of the fabricated sample, which provided a reference for all additive manufacturing methods.

The internal resistance of a dynamometer is regarded as a constant force when using traditional test methods, which means that the measurement values for the instantaneous power output of the vehicle driving wheel are underestimated. In this study, we aimed to resolve this issue. Thus, we constructed a system for measuring drum movement and propose a method for measuring the instantaneous power output of a vehicle's driving wheel. Further, we created a mathematical model of the instantaneous power output from a vehicle's driving wheel. Comparing the results from our model with our experimental results, we found that the actual power output of the driving wheel was reflected more accurately by our proposed method, and that the accuracy of the measurement results was not affected by the vehicle's speed. The output torque of the vehicle's driving wheel calculated using our proposed model was closer to the running resistance of the vehicle. Thus, our model facilitates accurate no-dismounting, rapid measurement of the power output of a driving wheel, and accurate simulation of road running resistance using a dynamometer.

The variable noise spectrum for many actual application scenarios requires a sound absorber to adapt to this variation. An adjustable sound absorber of multiple parallel-connection Helmholtz resonators with tunable apertures (TA–MPCHRs) is prepared by the low-force stereolithography of photopolymer resin, which aims to improve the applicability of the proposed sound absorber for noise with various frequency ranges. The proposed TA–MPCHR metamaterial contains five metamaterial cells. Each metamaterial cell contains nine single Helmholtz resonators. It is treated as a basic structural unit for an array arrangement. The tunable aperture is realized by utilizing four segments of extendable cylindrical chambers with length l0, which indicates that the length of the aperture l is in the range of [l0, 4l0], and that it is tunable. With a certain group of specific parameters for the proposed TA–MPCHR, the influence of the tunable aperture with a variable length is investigated by acoustic finite element simulation with a two-dimensional rotational symmetric model. For the given noise spectrum of certain actual equipment with four operating modes, the TA–MPCHR sample with a limited total thickness of 40 mm is optimized, which is made of photopolymer resin by the low-force stereolithography, and its actual average sound absorption coefficients for the frequency ranges of 500–800 Hz, 550–900 Hz, 600–1000 Hz and 700–1150 Hz reach 0.9203, 0.9202, 0.9436 and 0.9561, respectively. Relative to common non-adjustable metamaterials, the TA–MPCHR made of photopolymer resin can reduce occupied space and improve absorption efficiency, which is favorable in promoting its practical applications in the noise pollution prevention.

羊肚菌是一类名贵的食药兼用菌,被誉为"菌中之王".为深入了解国内外有关羊肚菌的研究现状与发展态势,以Web of Science(WoS)核心合集和中国知网(CNKI)数据库为基础,采用文献计量学方法对羊肚菌主题相关文献的发文作者、期刊、机构以及关键词等内容进行分析.结果表明,自2012年实现羊肚菌的大田商业栽培后,研究热度日益活跃,近五年发文量总体呈现上升趋势.美国(263篇)、法国(147篇)和中国(141篇)发文量位居前三,发文量占比均超过20％,各国之间合作密切;法国国家科学研究中心的发文量(55篇)和总被引频次(2261次)位居第一;接收文献最多的期刊为《Mycologia》;有关羊肚菌的研究主要集中在人工栽培、液体发酵、多糖提取、抗氧化等方面.综上,羊肚菌领域仍处于活跃的发展状态,应用场景日趋丰富,未来可能会在羊肚菌栽培技术和功能性食品、药品研发上挖掘到崭新的研究应用方向.

Field test is an important way to study the lightning response of transmission lines. When conducting lightning impulse tests on real transmission lines, the arrangement of the test circuit has a significant impact on the test results. In order to obtain reasonable test results, this paper studies the influence of the angle between the test circuit and the tested transmission line and the position of the current return electrode and voltage reference electrode on the test results. Then a test method for lightning response of real transmission lines is proposed, which contains the position selection of the electrode and the arrangement of the current lead and voltage lead. Based on the test method, a lightning impulse test is carried out on a 220 kV transmission line. The ideal test results prove the feasibility of the proposed test method.

•The activity of immobilized Penicillin G acylase significantly improved by Mn2+ doped for the first time.•The reusability of immobilized Penicillin G acylase was improved by Mn2+ doped for the first time.•Mn2+-Fe3O4@β-CD-g-KH560 realized magnetic recovery of immobilized Penicillin G acylase by click reaction.•The reagents used were environmentally friendly, and preparation process was simple.

Soil is composed of many minerals. Because minerals have different spectral features of emission and reflection, the spectral characteristics of soils are different. Although there are mineral spectral libraries for the spectral analysis of pure minerals (mainly primary minerals), it is difficult to quantitatively determine the composition and content of minerals in soils with secondary minerals and clay minerals. Thermal infrared (8 ~ 14 μm) hyperspectral remote sensing has the ability to identify minerals, but there are few studies on mineral identification in soil. This study takes the Baiquan area of China as the research area, and hyperspectral infrared sensors, known as the Thermal Airborne Spectrographic Imager (TASI), are used for image analysis and mineral mapping. The emissivity data are formed by the emissivity normalization method. After interference information such as humidity is removed by masking, the spectral endmembers in the soil are classified by the sequential maximum angle convex cone (SMACC) method; thus, an endmember spectrum is formed. Based on a comparison of the endmember spectra from the TASI images and the field-measured spectra with the mineral spectra in the ASU and USGS spectral libraries, the main mineral types in the soil are determined. Finally, a map of mineral abundance in soil is formed by matched filtering. The results show that the main mineral types in the soil of the Baiquan area include palygorskite, anorthite, halloysite, montmorillonite and carolinite. Additionally, in the visible shortwave infrared (VIS-SWIR) spectral ranges, hydroxyl minerals can be distinguished, and the absorption characteristics of clay minerals are based mainly on their absorption depth. However, if noise is generated in the case of soil with humidity, it is not easy to identify hydroxyl minerals, but the thermal infrared band can have a greater ability to distinguish minerals in this situation. In this study, the quantitative inversion of soil mineral composition based on thermal infrared hyperspectral data and the method of drawing a soil mineral abundance map are proposed. Compared with the traditional laboratory analysis of soil samples, the proposed strategy has the advantages of being nondestructive, rapid, and widely applicable, and compared with previous mineral mapping based only on the VIS-SWIR range, the proposed strategy improves the ability of fine identification of minerals in the thermal infrared range. These results provide a basis for the study of fine soil mapping and mineral distribution in soil based on full-spectrum hyperspectral images.

多黏类芽孢杆菌具有调节肠道微生态平衡、预防疾病、抑制病原菌生长、增强动物免疫力等多种功效.文章综述多黏类芽孢杆菌的生物学特性,对畜牧生长性能、肠道微生态平衡、抗氧化能力的影响及未来的发展趋势,为加快畜牧类饲料添加剂的研究提供参考.