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The perfluoronitriles and its mixtures have great dielectric strength and are environmentally friendly, which are considered as a typical class of alternative gases. This paper investigates the frequency breakdown characteristics of C4-PFN/CO2 mixtures in the nonuniform electric field. The influences of the electric field distribution, pressure and the C4-PFN component ratio on the dielectric strength of C4-PFN/CO2 mixtures are studied, which is compared with the cases for SF6 under the same conditions. It is shown that the sensitivity of C4-PFN/CO2 mixtures to the nonuniform electric field increases with the increase of the C4-PFN component ratio. For C4-PFN/CO2 mixtures containing more than 5% C4-PFN, the sensitivity is much greater than that of SF6. [ABSTRACT FROM AUTHOR]

CF3I-N2 mixtures have garnered much attention as potential SF6-substitutes due to their excellent dielectric strengths, and the dielectric strength of SF6-N2 mixtures has a good synergy effect. This paper attempts to propose an approach of adding a small amount of SF6 to improve the dielectric strength of the CF3I-N2 mixture, by making an all-around consideration of dielectric strength, impact on the environment and the limitations of engineering pressure and the lowest ambient temperature. The influences of adding different amounts of SF6 on the electron energy distribution function, the reduced ionization, attachment and effective ionization coefficients, the critical reduced electric field strength and critical electron temperature of ternary SF6-CF3I-N2 mixtures are investigated by Boltzmann analysis. Then the relations of the critical electric fiend strength, mixed ratio and saturated vapor pressure of the ternary SF6-CF3I-N2 mixture are built and analyzed. The results demonstrate that an effective improvement of its dielectric strength can be obtained by adding a small amount of SF6 into the CF3I-N2 mixture, and that a proper choice of the mixed ratio and the gas pressure of the ternary SF6-CF3I-N2 mixture can provide a comparable dielectric strength to pure SF6. [ABSTRACT FROM AUTHOR]

CF3I-N2 mixtures have garnered much attention as potential SF6-substitutes due to their excellent dielectric strengths, and the dielectric strength of SF6-N2 mixtures has a good synergy effect. This paper attempts to propose an approach of adding a small amount of SF6 to improve the dielectric strength of the CF3I-N2 mixture, by making an all-around consideration of dielectric strength, impact on the environment and the limitations of engineering pressure and the lowest ambient temperature. The influences of adding different amounts of SF6 on the electron energy distribution function, the reduced ionization, attachment and effective ionization coefficients, the critical reduced electric field strength and critical electron temperature of ternary SF6-CF3I-N2 mixtures are investigated by Boltzmann analysis. Then the relations of the critical electric fiend strength, mixed ratio and saturated vapor pressure of the ternary SF6-CF3I-N2 mixture are built and analyzed. The results demonstrate that an effective improvement of its dielectric strength can be obtained by adding a small amount of SF6 into the CF3I-N2 mixture, and that a proper choice of the mixed ratio and the gas pressure of the ternary SF6-CF3I-N2 mixture can provide a comparable dielectric strength to pure SF6. [ABSTRACT FROM AUTHOR]

SF6 gas is widely used in power systems, however, it has a strong greenhouse effect. The search for a new environmentally friendly alternative gas has become an urgent task for the power industry. In this paper, CF3I/CO2 gas mixtures in the ratio of 3:7 was tested based on a lightning impulse experimental platform. The 50% impulse breakdown voltage of CF3I/CO2 gas mixtures was determined under various pressures (0.1~0.3MPa) and gaps (5~30mm) and compared to pure SF6 gas. The results indicate that CF3I/CO2 gas mixtures has good insulation properties, reaching 0.84 times that of SF6 gas under slightly non-uniform electric field and 0.65 times that of SF6 gas in extremely inhomogeneous electric field. The polar effect of CF3I/CO2 gas mixtures was also analyzed and the coefficient K is proposed to describe and compare the differences of 50% breakdown voltages under different electric field. The results show that the polar effect of CF3I/CO2 gas mixtures under extremely inhomogeneous electric field is more obvious than that under slightly non-uniform electric field, and the polar reversal phenomenon occurs only under extremely inhomogeneous electric field. Considering various factors, CF3I/CO2 mixtures has the capability of replacing SF6 gas in power equipment such as GIL. [ABSTRACT FROM AUTHOR]

• Interaction between C4F7N and ZnO surface is stronger that on Zn surface. • The CN group shows a strong activity on the ZnO surface. • Activation energy of C 4 F 7 N dissociation on ZnO surface is higher than on Cu and Al. • Zinc shows potentials to be anti-corrosion material when using C 4 F 7 N. Recently, C 4 F 7 N has been considered as one of the most promising candidates to replace SF 6 due to its excellent insulation performance and environmental-friendly property. Metal zinc is widely used as a coating material in gas-insulated electrical equipment. However, its compatibility with C 4 F 7 N has never been explored before. In this paper, the adsorption properties of C 4 F 7 N on Zn(0 0 0 1) and ZnO(1 0 1 ¯ 0) surfaces were theoretically studied by a first-principles calculation. Adsorption energy, total charge transfer, density of states, and electron density difference were calculated to evaluate the compatibility of C 4 F 7 N with Zn and ZnO. The results demonstrated that the interaction between C 4 F 7 N and ZnO(1 0 1 ¯ 0) is stronger than that of Zn(0 0 0 1). The dissociation pathway of C 4 F 7 N after adsorption on the ZnO(1 0 1 ¯ 0) surface was also determined, which shows that ZnO(1 0 1 ¯ 0) has a catalytic effect on the decomposition process of C 4 F 7 N. Compared with Al(1 1 1) and Cu(1 1 1), the dissociation of C 4 F 7 N on ZnO(1 0 1 ¯ 0) has a higher energy barrier, indicating that the reaction is more difficult to occur. As a result, Zn and ZnO have certain compatibility with C 4 F 7 N, which was also verified by experiments. Therefore, we infer that Zn shows potentials to be used as anti-corrosion coating in C 4 F 7 N gas-insulated electrical equipment. [ABSTRACT FROM AUTHOR]

Background: The management of neuropathic pain (NP) is challenging despite it being the recent focus of extensive research. A number of clinical practice guidelines (CPGs) for the management of NP have been published worldwide over the past 2 decades. This study aimed to assess the quality of these CPGs., Methods: We performed a systematic review of published CPGs for the management of NP. Three reviewers independently assessed the quality of the CPGs using the Appraisal of Guidelines Research and Evaluation II (AGREE-II) instrument, and recommendations of CPGs were also appraised., Results: A total of 16 CPGs were included. Thirteen CPGs were developed using an evidence-based approach, and the remaining CPGs were produced by consensus panels. None of CPGs obtained a score greater than 50% in all six AGREE II instrument domains mainly owing to poor performance in the "Applicability" domain. The highest score of the CPGs was achieved in "Clarity and Presentation" domain, followed by "Scope and Purpose" and "Editorial Independence" domains, and the lowest scores were found the in "Applicability" domain. The majority of the CPG recommendations on the management of patients with NP were relatively consistent, especially regarding the recommendation of stepwise treatment with medication., Conclusions: Greater efforts are needed not only to improve the quality of development and presentation of the CPGs, but also to provide more efficacy evidence for the management of patients with NP.