RESUMEN
As an important part of die steels, hot-work die steels are mainly used to manufacture molds made of solid metal or high-temperature liquid metal from heating to recrystallization temperature. In view of the requirements for mechanical properties and service life for hot-work die steel, it is conducive to improve the thermal fatigue resistance, wear resistance, and oxidation resistance of hot work die steel. In this review, the main failure modes of hot-work die steel were analyzed. Four traditional methods of strengthening and toughening die steel were summarized, including optimizing alloying elements, electroslag remelting, increasing the forging ratio, and heat treatment process enhancement. A new nano-strengthening method was introduced that aimed to refine the microstructure of hot-work abrasive steel and improve its service performance by adding nanoparticles into molten steel to achieve uniform dispersion. This review provides an overview to improve the service performance and service life of hot work die steel.
RESUMEN
BACKGROUND: The occurrence of a diaphragmatic hernia during the third trimester of pregnancy is rare; to our knowledge, there has only been a single case report related to congenital Bochdalek hernia complicated with mild acute pancreatitis during pregnancy. Nonspecific symptoms and lack of experience due to its rarity make the diagnosis of this condition very challenging. We report a case of diaphragmatic hernia accompanied by mild acute pancreatitis in the third trimester of pregnancy, which was misdiagnosed as severe acute pancreatitis. CASE SUMMARY: A 19-year-old woman presented at gestation of 31+2 weeks with continuous distension pain for 3 d in the left lumbar region of no obvious cause. Ultrasonographic findings of left ureterectasis, with nonspecific lumbago and abdominal pain, led to the misdiagnosis of renal colic. Increased serum amylase and/or lipase levels indicated acute pancreatitis. Following the treatment of pancreatitis, her condition deteriorated. The patient was finally diagnosed with a diaphragmatic hernia complicated with mild acute pancreatitis on magnetic resonance imaging at our hospital. Caesarean section was performed at gestation of 31+6 weeks, followed by hernia repair, and the pancreatitis was treated sequentially. The patient was discharged in good condition 20 d after the surgery. CONCLUSION: In this case, surgical treatment was not the same as that for non-pregnant diaphragmatic hernia repair. It is important to first perform a cesarean section before commencing the therapy.
RESUMEN
Xylitol production from xylose by a self-isolated furfural and 5-hydroxymethyl furfural assimilating Pichia guilliermondii was studied under oxygen limitation. An extremely low initial volumetric oxygen transfer coefficient (0.075 h(-1)) was found most favorable to the xylitol production with yield of 0.61 g g(-1). Related enzymes activities were also investigated and discussed.