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Organic elastomers such as polyurethane are widely used as a filling material in underground coal mines. However, the risk of fire hazard in coal seams is increased due to the flammability of polyurethane. Laboratory tests illustrate that in a thermostatic reactor with initial temperature of 25 °C, the temperature during the production of polyurethane increases up to > 140 °C. Adiabatic oxidation experiments and TG–DTG analysis showed that the heating rate of the mixed samples of polyurethane and coal was higher than that of any single component in the initial oxidation stage. From the initial temperature to 100 °C, increasing the proportion of polyurethane was conducive to the acceleration of temperature rise. From 0.180 to 0.850 mm, the self-heating rate was inversely proportional to the particle size. At the initial stage, the low ventilation rate promoted the spontaneous combustion of mixed samples, but when the temperature is > 70 °C, an opposite trend was seen. Kinetic parameters suggested that the activation energy decreases with the introduction of polyurethane. According to the mathematical model, the variation of the spontaneous combustion period of coal and polyurethane was predicted.

High dielectric loss is one of the current obstacles to the application of dielectric materials. In this paper, we synthesized a new dielectric material, i.e., (Yb + Ta)-co-doped TiO2 dielectric material. The (Yb0.5Ta0.5)xTi1−xO2 ceramics were synthesized by the solid-state reaction method. It has been found that (Yb0.5Ta0.5)xTi1−xO2 ceramics had a dense ceramic microstructure, and (Yb0.5Ta0.5)xTi1−xO2 ceramics exhibited the rutile TiO2 structure. All (Yb0.5Ta0.5)xTi1−xO2 ceramics exhibited low dielectric loss ( 105). The optimal dielectric properties are obtained at a doping level of x = 0.05 with dielectric constant of 5.1 × 105 and dielectric loss of 0.037. Further study of the thermal stability of the dielectric properties was performed in the temperature range from − 50 to 250 ℃, which indicates that the ceramic sample with x = 0.05 co-dopant concentration maintains good dielectric properties in the temperature range from − 50 to 100 ℃. XPS shows that high dielectric properties can be explained by the electron-pinned defect-dipole mechanism.

Few cases of uraemic tumoral calcinosis (UTC) have been reported. This study aimed to investigate the clinical efficacy of parathyroidectomy for UTC. Historical clinical data of patients with end-stage renal disease and UTC who underwent parathyroidectomy were analysed. Absorption of metastatic calcification was compared before and after operation. Changes in intact parathyroid hormone, serum calcium, phosphorus, and alkaline phosphatase levels were analysed before parathyroidectomy and at 1 week and 3, 6, and 12 months after parathyroidectomy. Eight patients met the enrolment criteria (men, 6; mean age, 38.6 SD 10.9 years). Uraemic tumoral calcinosis, which developed 2–8 years after dialysis began, was caused by secondary hyperparathyroidism. Massive calcium deposition was found in the shoulder (n = 6), hip (n = 3), and elbow (n = 2). Four patients had > 2 joints affected, and a single joint was involved for four patients. Seven patients had rapid remission (p p > 0.05). Parathyroidectomy has promising efficacy for UTC treatment and regulation of serum intact parathyroid hormone and phosphorus. Hypocalcaemia is a common complication after parathyroidectomy. Current Controlled Trials ChiCTR2000041311, date of registration: Dec. 23, 2020.