Search

Copyright of Journal of Mining & Metallurgy. Section B: Metallurgy is the property of Journal of Mining & Metallurgy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A type of carbon composite brick was produced via the microporous technique using natural flack graphite, &#945-Al2O3 and high-quality bauxite chamotte (Al2O3≥ 87 mass%) as raw materials with fine silicon powder as additive. The composition and microstructure of the obtained carbon composite were characterized using chemical analysis, XRD and SEM with EDS. The high temperature properties of thermal conductivity, oxidization and corrosion by molten slag and hot metal of the composite were analyzed. Based on these, the type of carbon composite brick worked in a blast furnace hearth for six years was further sampled at different positions. The protective layer was found and its chemical composition and microscopic morphology were investigated. It is found that the carbon composite brick combines the good properties of both the conventional carbon block and ceramic cup refractory. The protective layer near the hot face consists of two separated sublayers, i.e. the slag layer and the carbon layer. A certain amount of slag phase is contained in the carbon layer, which is caused by the reaction of coke ash with the refractory. No obvious change in the chemical composition of the protective laver along the depth of the sidewall is found. This work provides a useful guidance for the extension of the lifetime of blast furnace hearths. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effects of ultrasound-guided lateral and medial point blocks of thoracic paravertebral space on the rapid recovery of laparoscopic cholecystectomy. Methods: A total of 90 patients of either sex, aged 18-67 years, weighted 45.10-91.80 kg, of American Society of Anesthesiologists physical status Ⅰ or Ⅱ, undergoing elective laparoscopic cholecystectomy were divided into two groups ( n= 45) using a random number table: lateral point group of thoracic paravertebral space (group A) and medial point group of thoracic paravertebral space (group B). Ultrasound-guided thoracic paravertebral nerve block was performed before induction of general anesthesia. The puncture point of group A was positioned as the intercostal block of the thoracic paravertebral space of the right side of T(6)-T(11), and the puncture point of the group B was positioned as the thoracic paravertebral body of the right side of T(6)-T(11) thoracic paravertebral space. The thoracic paravertebral block was performed with 2 ml of 0.75% ropivacaine per injection for a total of 10 ml. The visual analog scale (VAS) scores of resting pain and active pain at 4, 8, 12 and 24 h after operation were observed. The anus recovery time after surgery and perioperative hypotension were also recorded. Results: The blood pressures in group A were significantly higher than those in group B at 4, 8, 12 and 24 h after operation, which were(73±7) vs (70±7), (78±7) vs (74±7),(82±7) vs (79±7),and (87±7) vs (83±7) mmHg,and the differences were statistically significant ( t= 2.29, 2.54, 2.33, 2.37, all P< 0.05). The VAS scores of resting pain and active pain in group A were significantly higher than those in group B, and the differences were statistically significant ( Z= -2.29, -2.51, -2.21, -2.39, -2.53, -2.25, -2.30, -2.24, all P< 0.05). The postoperative anal exhaust recovery time of the patients in group A was (21.8±1.9) min that was obvious lower than that in group B which was (22.7±1.9) min with statistically significant difference ( t= 2.12, P< 0.05). There was no significant difference in the incidence of postoperative dizziness, nausea, vomiting, and pruritus (χ(2)=0.28, 0.72, 0.45, 0.21,all P> 0.05). Conclusions: In the procedure of thoracic paravertebral block under the guidance of ultrasound, the closer blocking points are to the central axis of the spine, the better the postoperative analgesic effect, but the more obvious the postoperative blood pressure reduction and the longer the anal recovery exhaust time. The further away from the central axis of the spine, the more analgesic effect decreases, but the blood pressure decreases and the anal recovery time is relatively rapid.