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A caged metal–organic framework based on heptanuclear and binuclear copper clusters, namely [Cu9(L)10(H2O)2][Me2NH2+]2 (Cu-MOF) (L = rigid 6-(1H-tetrazol-5-yl)-2-naphthoic acid) was synthesized and structurally characterized by a solvothermal method. Single-crystal X-ray diffraction shows that Cu-MOF displays a three-dimensional porous anionic framework and exhibits a cage-cavity structure. The tri-functional ligand uses two coordination modes to bridge different SBUs to form a dodecahedral cage. Since Cu-MOF possesses both anionic and porous frameworks, it could be used for efficient and selective absorption of cationic organic dyes. Further studies truly showed that both the charge and size of the dye molecules affect the absorption of Cu-MOF. Besides, thanks to the electronic configuration and wide range of visible light absorption properties of the heptanuclear copper clusters, Cu-MOF could be used as a photocatalyst for energy transfer from oxygen molecules to singlet oxygen, and successfully oxidized benzyl alcohol to benzoic acid in air under additive-free mild conditions. Therefore, rationally prepared Cu-MOFs, guided by crystal engineering, demonstrate potential for application as organic dye adsorption separators and photocatalysts, and the feasibility of preparing functionally tailored frameworks using tri-functional ligands consisting of tetrazolium and carboxylate acid is presented. [ABSTRACT FROM AUTHOR]

As one of the most important electrical equipment in power system, the stable operation of transformer is the key factor to ensure the safety of power grid system. Winding deformation is the most common fault of transformer, which will seriously affect the reliable operation of the whole power system. Therefore, the detection of transformer winding deformation is of great significance to prevent transformer accidents. In order to further improve the reliability of transformer winding deformation detection, this paper proposes a transformer winding deformation detection method based on oscillation wave method. Firstly, the equivalent circuit model of transformer winding is established, and the transformer winding fault is simulated by changing the inductance and capacitance parameters in the model, and the law between the change of oscillation wave curve and the change of related performance indexes and equivalent parameters is obtained. Finally, the field test verification is carried out on a 10 kV transformer in the laboratory. The results show that the oscillation wave method can diagnose the transformer winding deformation and can be used for the actual transformer winding deformation detection. [ABSTRACT FROM AUTHOR]

With the increasing demand for electricity, voltage measurement has been applied in various fields of the power grid, especially in low-voltage distribution networks and household appliances. However, in low-voltage distribution networks, traditional contact measurement cannot be used due to technical limitations such as the need to damage the insulation layer. Non contact voltage measurement is becoming the main voltage measurement method, A major technical challenge in non-contact measurement is the interference of external electric fields. In order to solve the above problems, this article develops a new type of non-contact low-voltage measurement equipment, which can overcome the interference of external electric fields on measurement and achieve high-precision non-contact voltage measurement. The experimental results indicate that the sensor designed in this paper has high measurement accuracy. The ratio error at power frequency is within ± 0.9%, and the phase error is within 3°. In addition, the sensor also has the advantages of low cost, small size, and convenient manufacturing. [ABSTRACT FROM AUTHOR]

Transformer-based contact voltage measurement requires electrically charged installation during use. Moreover, there are problems with large sizes and restricted installation locations. The current non-contact voltage measurement technology is based on the principle of capacitive coupling in measurement. The capacitance between the probe and the wire is affected by the diameter of the wire and the insulation material. This results in an unstable sensor gain relationship, which leads to low measurement accuracy. This paper proposes a non-contact multi-wire adaptive voltage measurement method, and self-calibration of the sensor gain is achieved through practical measurements. First, the basic principle of capacitively coupled voltage measurement is introduced, from which the existing problems are condensed. An impedance-based adaptive method is proposed, based on which a new sensor probe is developed. The accuracy test reveals that the maximum relative error of voltage amplitude is 0.89 percent, the relative error of phase is 0.38%, and the relative phase error is within 1 degree for a specified voltage range (100 V-300V). The scenario adaptability test shows that the maximum relative error is 1.7% when performing tests on different types of lines. This sensor has the advantages of compactness, convenience, low cost, and high practicality. [ABSTRACT FROM AUTHOR]

Photocatalysis is an effective approach to convert solar energy into chemical energy using semiconductor materials. However, the fast recombination rate of electron–hole pairs in these materials leads to low energy utilization efficiency and poor photocatalytic performance. Herein, an iron-based Metal–Organic Framework (Fe-MOF) was constructed via structural tailoring, which has structural advantages such as a one-dimensional Fe–O-triazole chain and strong π–π stacking interaction, ensuring a broad absorption range, high electron conductivity (5.53 × 10−4 S m−1), and good photogenerated electron–hole separation efficiency. Fe-MOF as a photosensitizer could facilitate the efficient degradation of tetracycline hydrochloride (TC) under visible light irradiation (e.g., 40 ml of 350 mg L−1 TC showed over 99% degradation in 5 minutes with 5 mg Fe-MOF as the photocatalyst). As a comparison, Zn-MOF, which is isomorphic to Fe-MOF, was prepared using crystal engineering and its photodegradation efficiency was greatly reduced. The results provide a design basis for the development of light harvesting in artificial photosynthesis. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs) are sets of carbon quantum dots derived from graphene or graphene oxide, and they have obvious graphene lattice properties. The number of layers in GQDs is generally no more than five layers, and the diameter size of GQDs is generally less than 10 nm. GQDs have stable photoluminescence characteristics, high specific surface areas, high conductivity levels and adjustable band gaps, and they can be used in sensing systems such as ion detection sensing, optical biosensing, electrochemical biosensing and electronic sensing. Based on the research status of GQDs in recent years and the application background of sensing systems, this review paper focuses on the synthesis strategies, sizes, chemical compositions, crystal structures, optical properties and sensor applications of GQDs. [ABSTRACT FROM AUTHOR]

In recent years, advances in novel photosensitive materials have been expected to drive the development of next-generation smart devices, especially in the field of high visible-light utilization. Limited by synthetic techniques, the development of sensitive photoresponsive materials driven by visible light has been slow, especially as the distribution of strictly ordered photoresponsive groups cannot be solved. Here, we report the synergistic construction of a photosensitive metal–organic framework (MOF) consisting of uniform photoresponsive groups. By means of two photoactive units and D–A–D characteristics, short-range photo-generated electron transfer (PET) efficiency is ensured; by virtue of lophine, radical-induced photochromism is generated; thanks to the spatial confinement effect of Zr-MOF and the affinity of the anthracene ring toward singlet oxygen, unlike the previously reported dimerization reaction, the photochemical polymerization of adjacent anthracene rings can be monitored via SCXRD, clearly illustrating the detailed mechanism of visible-light-etching at the nanoscale. The occurrence of polymerization not only induces a contraction of the framework, but also improves the long-range PET and overall photon utilization, which is also demonstrated by the effective photocatalytic activation of C(sp3)–H and construction of C–N. The related results demonstrate that exploiting the structural tailoring of MOF can provide valuable insights into the development of highly sensitive visible-light-driven lithography designs. [ABSTRACT FROM AUTHOR]

The clinical effect of ultrasound guided standard channel percutaneous nephrolithotomy (PCNL) in the treatment of staghorn calculi were discussed m this study. A retrospective analysis of 200 patients with staghorn calculi who were treated with PCNL under the standard channel, 100 patients underwent ultrasound-guided PCNL surgery (uitrasound group) and the other 100 patients PCNL surgery was performed after X-ray position (X-ray group). The number of punctures n the uitrasound group, the establishment time of skin and kidney channels, the length of hospitalization, and the proportion of patients treated with extracorporeal lithotripsy were lower than those in the X-ray group (P$0. 05). The primary stone Clarence rate of the uitrasound group was higher than that of the X-ray group (P$0. 05). Twenty-four hours after surgery, the uitrasound group Cor kvel was lower than the X-ray group (P$0. 05). Ultrasound-guided standard channel PCNL treatment of staghorn calculi more accurate than X-ray positioning and puncture, import operation and has damage, which is beneficial to improve the primary stone clearance rate and to a certain extent, it beneficial to reduce the traumatic stress caused by surgery. [ABSTRACT FROM AUTHOR]