The Efficacy of Selected Sodium Hypochlorite Heating Methods for Increasing and Maintaining Its Intracanal Temperature—An Ex Vivo Study

Background: Enhancement of the temperature of sodium hypochlorite (NaOCl) solution would increase its cleaning potential and decontamination of the root canal system. Therefore, the aim of the present in vitro investigation was to compare the efficacy of different methods of NaOCl heating by evaluating the temperature profiles developed at different levels of the root canal system. Methods: Five thermocouples were applied at different levels of the root canal system of extracted human premolars. NaOCl solution was heated according to two methods: extraoral heating (50 °C, 60 °C, and 70 °C) using a magnetic hotplate heater and intracanal heating by F-06, XF-30/04, and ML-12 pluggers at 100 °C, 150 °C, and 180 °C. Results: The extraoral heating method was ineffective to produce a significant temperature increase at the root apex. Comparable results were obtained using the intracanal heating method through the ML-12 plugger that showed slightly better results only when set at 180 °C. On the other hand, negligible differences were observed in terms of temperature maintenance at several levels of the root between the F-06 and XF-30/04 pluggers, even though the time intervals were higher in case of XF-30/04. Conclusions: The intracanal heating method provided a better temperature persistence in the middle third of the root canal system. Conversely, extraoral heating was ineffective to produce a significant temperature increase at the apex of the root. Comparable results were obtained even using the ML-12 plugger.

Analysis of the Operation Principle of Typical Cogeneration Units

Cogeneration is a comprehensive energy utilization technology. While generating electricity, it effectively uses vaporized latent heat for heating, which has many advantages such as high energy utilization efficiency and environmental protection. The technical characteristics of several different forms of cogeneration such as gas turbines, gas-steams and fuel cells are analyzed. It can be seen from this paper that the heating method in the cogeneration area is advanced and reasonable, which has a good reference significance for improving energy utilization, energy conservation and emission reduction.

Application of the technology of induction chemical-thermal treatment to improve the physical and mechanical properties of tantalum

The results of the chemical thermal treatment (CTT) of tantalum in a solid carbon- containing medium in the temperature range from 1000 to 1300 °C were presented. CTT consisted in heating a workpiece with a working medium in a container made of a refractory material. The induction heating method was used for heating. After strengthening treatment, tantalum samples were characterized by increased hardness, which grew from 140 to 1100 HV0.02.