Theories and applications of electrical quantum benchmarks

The voltage unit and the resistance unit are the basic units in electrical metering. The Josephson voltage standard and the quantized Hall resistance standard have replaced the physical reference that was maintained by standard batteries and standard resistors. This paper investigates the working principle of voltage quantum reference, resistance quantum reference and current quantum reference. Furthermore, the applications of these new electrical References are discussed. This study provides theoretical support for the development of electricity value transfer methods.

Quantum Hall devices for the primary resistance standard based on the GaAs/AlxGa1−x As heterostructure

Quantum Hall devices for primary resistance metrology based on the GaAs/Al[Formula: see text]Ga[Formula: see text]As heterostructure were fabricated and compared with the devices from international metrology organization International Bureau of Weights and Measures (BIPM) by calibrating the same 100 [Formula: see text] transfer standard resistor with a cryogenic current comparator. Relative deviation between NIM-made device NIM-C1 and BIPM-made device BIPM-1 was −4.49 parts in 109 with an uncertainty of 3.63 parts in 109 which indicated NIM-C1 satisfied the requirement for the primary resistance standard.

Volume and/or Time of NaOCl Influences the Fracture Strength of Endodontically Treated Bovine Teeth

The aim of this study was to evaluate whether amplifying the volume and/or time of contact of NaOCl affects the fracture strength of endodontically treated bovine teeth. Four bovine incisors from 10 animals were allocated into 4 groups using a split-mouth design. Root canals were instrumented using a sequence of 4 manual stainless steel files and irrigated with a 5.25% alkalized NaOCl solution. The total volume and time of irrigation, per sample, varied among the groups as following: standard volume and time of contact - 15 mL/11.5 min; volume raise - 30 mL/11.5 min; time of contact raise - 15 mL/19 min; and volume and time of contact raise - 30 mL/19 min. Samples were subjected to a fracture resistance assay. At p=0.05, two-way ANOVA statistically scrutinized the results. Effect size of NaOCl time of contact and volume were also calculated (η2). The variation in time (p=0.000), volume of irrigation (p=0.000) and the combination of both (p=0.038) negatively influenced the fracture resistance. Standard volume and time of irrigation showed the highest fracture strength while isolated increase in volume or time reduced in 25% and 37%, respectively, the fracture resistance; the simultaneous increase in volume and time of irrigation promoted a reduction of 47%. Effect size of NaOCl time of contact was superior (0.746) than the volume (0.564). Raising the volume and/or time of a 5.25% alkalized NaOCl solution reduces the fracture resistance of endodontically treated bovine teeth.