Non-Contact Adaptive Voltage Sensor Based on Electric Field Coupling Principle.

Non-contact voltage sensors based on the principle of electric field coupling have the advantages of simple loading and unloading, high construction safety, and the fact that they are not affected by line insulation. They can accurately measure line voltage without the need to connect to the measured object. Starting from the principle of non-contact voltage measurement, this article abstracts a non-contact voltage measurement model into the principle of capacitive voltage sharing and deduces its transfer relationship. Secondly, it is theoretically inferred that the edge effect of the traditional symmetric structure sensor plate will cause the actual capacitance value between the sensor plates to be greater than the theoretically calculated capacitance value, resulting in a certain measurement error. Therefore, the addition of an equipotential ring structure is proposed to eliminate the edge additional capacitance caused by the edge effect in order to design the sensor structure. In addition, due to the influence of sensor volume, material dielectric constant, and other factors, the capacitance value of the sensor itself is only at pF level, resulting in poor low-frequency performance and imbuing the sensor with a low voltage division ratio. In this regard, this article analyzes the measurement principle of non-contact voltage sensors. By paralleling ceramic capacitors between the two electrode plates of the sensor, the capacitance of the sensor itself is effectively increased, improving the low-frequency performance of the sensor while also increasing the sensor's voltage division ratio. In addition, by introducing a single pole double throw switch to switch parallel capacitors with different capacitance values, the sensor can have different voltage division ratios in different measurement scenarios, giving it a certain degree of adaptability. The final sensor prototype was made, and a high and low voltage experimental platform was built to test the sensor performance. The experimental results showed that the sensor has good linearity and high measurement accuracy, with a ratio error of within ±3%.

Application of Copper(II)-Organic Frameworks Bearing Dilophine Derivatives in Photocatalysis and Guest Separation.

The functionalized design of metal-organic frameworks (MOFs) has been rapidly developed in the last 20 years, and its broad applicability has been demonstrated in many fields. MOFs with desired functions can be assembled using predesigned organic linkers with specific metal nodes, which possess the ordered functional sites and open structures. Although a large number of carboxylic acid junctions have been used to construct MOFs, it is still a great challenge to realize their multifunctionality. In particular, there is a relative lack of research on MOFs as direct photocatalysts, which require not only abundant active sites and open structures but also adsorption groups and effective electron-hole separation performance. To this end, MOFs constructed from the carboxylic acid ligands derived from lophine-based derivatives and copper ions were deliberately used as a photocatalyst, and then, their application in dye degradation and aromatic alcohol conversion was investigated. In addition, in combination with the abundant Lewis sites of copper ions and imidazole sites, the material shows not only the adsorption and separation of C2 series and dyes but also the application of dye degradation and conversion of aromatic alcohols under illumination conditions. The corresponding results fully illustrate that the MOF constructed by using lophine derivatives can be an effective way to prepare photocatalysts. The subsequent research ideas will focus on designing a series of MOFs constructed with multilinked moieties of lophine groups and exploring their application strategies in the field of photocatalysis.

Contactless AC/DC Wide-Bandwidth Current Sensor Based on Composite Measurement Principle.

With the accelerated construction of the smart grid, new energy sources such as photovoltaic and wind power are connected to the grid. In addition to power frequency, the current signal of power grid also includes several DC signals, as well as medium-high and high-frequency transient signals. Traditional current sensors for power grids are bulky, have a narrow measurement range, and cannot measure both AC and DC at the same time. Therefore, this paper designs a non-intrusive, AC-DC wide-bandwidth current sensor based on the composite measurement principle. The proposed composite current detection scheme combines two different isolation detection technologies, namely tunneling reluctance and the Rogowski coil. These two current sensing techniques are complementary (tunneling magnetoresistive sensors have good low-frequency characteristics and Rogowski coils have good high-frequency characteristics, allowing for a wide detection bandwidth). Through theoretical and simulation analysis, the feasibility of the composite measurement scheme was verified. The prototype of composite current sensor was developed. The DC and AC transmission characteristics of the sensor prototype were measured, and the sensitivity and linearity were 11.96 mV/A, 1.14%, respectively. Finally, the sweep current method and pulse current method experiments prove that the designed composite current sensor can realize the current measurement from DC to 17 MHz.

Study of composite Al2O3-Ce:Y3Mg1.8Al1.4Si1.8O12 ceramic phosphors.

The nominal composition of Al2O3-Ce:Y3Mg1.8Al1.4Si1.8O12 (A-Ce:YMASG) ceramic phosphors was fabricated by the vacuum sintering technique. The introduction of Al2O3 as a second phase partially enters the crystal lattice, which was confirmed by the composition changing of the samples through x-ray diffraction measurement. An impurity phase of Y4MgSi3O13 was observed in Ce:YMASG and disappeared with the introduction of Al2O3 at the concentration of 10 wt. %. When the content of Al2O3 increased to 30 and 50 wt. %, the second phase of Al2O3 was measured with actual weight ratios of 7.72 and 20.55 wt. %, respectively. The third phase of MgAl2O4 was found with the further addition of Al2O3at 70 wt. %; the weight ratios of Ce:YMASG, Al2O3, and MgAl2O4 were 68.756, 18.457, and 12.787 wt. %, respectively. The luminescent characters of the samples were measured by the photoluminescence spectra and electroluminescent spectra. With the increase of Al2O3 from 0 to 30 wt. %, the emission wavelength of Ce3+ plummeted from 610 to 552 nm, and the luminous efficacy of the samples increased from 35 to 65 lm/W.

Introducing a Pyrazinoquinoxaline Derivative into a Metal-Organic Framework: Achieving Fluorescence-Enhanced Detection for Cs+ and Enhancing Photocatalytic Activity.

Conventional photoresponsive materials have low photon utilization due to irregular distribution of photoactive groups, which severely limits the related real applications. Metal-organic frameworks (MOFs) can modulate the regular arrangement of functional groups to improve the electron transport paths and enhance the photon utilization, which provides strong support for the development of photoactive materials with excellent performance. In this work, one effective strategy for constructing a photoactive MOF had been developed via the utilization of Cd2+ and pyrazinoquinoxaline tetracarboxylic acid. The structural advantages of the Cd-MOF, such as a porous structure, abundant subject-object interaction sites, and a stable framework, ensure the prerequisite for various applications, while the better synergistic effect of Cd3 clusters and the pyrazinoquinoxaline derivative ensures efficient electron transfer efficiency. Therefore, by virtue of these structural advantages, the Cd-MOF can achieve fluorescence quenching detection for a variety of substrates, such as Fe3+, Cr2O72-, MnO4-, nitrofuran antibiotics, and TNP explosives, while fluorescence enhancement detection can be achieved for halogen ions, Cs+, Pb2+, and NO2-. In addition, the Cd-MOF can be used as a photocatalyst to successfully achieve the photocatalytic conversion of benzylamine to N-benzylbenzimidate under mild conditions. Thus, the Cd-MOF as a whole shows the possibility of application as a diverse fluorescence detection and photocatalyst and also illustrates the feasibility of preparing high-performance photoactive materials using the pyrazinoquinoxaline derivative.

Modulating the relaxation dynamics via structural transition from a dinuclear dysprosium cluster to a nonanuclear cluster.

A dinuclear dysprosium cluster [Dy2(NO3)4(H2O)2(L)2]·2CH3CN was successfully prepared by employing HL (HL = 2,6-dimethoxyphenol) and Dy(NO3)3·6H2O in a mixture of CH3OH and CH3CN. The conversion of this Dy2 compound by reaction with additional deprotonated ligand generated a Dy9 cluster [Dy9(µ4-OH)2(µ3-OH)8(µ2-OCH3)4(NO3)8(H2O)8(L)4](OH)·2H2O with the well-known "diabolo" topology. Magnetic investigation revealed that both of the clusters exhibit typical SMM characteristics, and variable magnetic relaxation with the energy barrier changing from 217.87 K to 9.24 K along with the transition from a dinuclear dysprosium cluster to a nonanuclear one. Ab initio calculations further confirm the corresponding structure-activity relationships that originate the different magnetic behaviours. This design may afford a feasible strategy for modulating the magnetic relaxation dynamics of polynuclear systems.