By means of the ultrasonic surface impact (amplitude of 30 μm, strike number of 48,000 times/mm2), nanograins have been achieved in the surfaces of both Ti6Al4V(TC4) and Ti3Zr2Sn3Mo25Nb(TLM) titanium alloys, mainly because of the dislocation motion. Many mechanical properties are improved, such as hardness, residual stress, and roughness. The rotating–bending fatigue limits of TC4 and TLM subjected to ultrasonic impact are improved by 13.1% and 23.7%, separately. Because of the bending fatigue behavior, which is sensitive to the surface condition, cracks usually initiate from the surface defects under high stress amplitude. By means of an ultrasonic impact tip with the size of 8 mm, most of the inner cracks present at the zone with a depth range of 100~250 μm in the high life region. The inner crack core to TC4 usually appears as a deformed long and narrow α-phase, while the cracks in TLM specimens prefer to initiate at the triple grain boundary junctions. This zone crosses the grain refined layer and the deformed coarse grain layer. With the gradient change of elastic parameters, the model shows an increase of normal stress at this zone. Combined with the loss of plasticity and toughness, it is easy to understand these fatigue behaviors. 相似文献
Objective To observe the clinical characteristics and prognosis of patients with rapidly progressive glomerulonephritis (RPGN) caused by lupus nephritis, antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, or primary glomerulonephritis who were treated with peritoneal dialysis (PD) and then withdrew PD because of renal recovery. Methods Data of the above patients were retrospectively analyzed. The patients were diagnosed as RPGN and received PD therapy in Kidney Disease Center, the First Affiliated Hospital, College of Medicine, Zhejiang University from February 2009 to August 2018. The patients were divided into early withdrawal group (PD time≤183 days, n=24) and late withdrawal group (PD time>183 day, n=24). The differences of clinical characteristics between the two groups were compared. The cumulative incidence of adverse events in both groups was analyzed using Kaplan-Meier curves. Cox proportional hazards model was used to analyze the risk factors influencing the prognosis of patients. Results Forty-eight RPGN patients were included. The median time of maintaining PD was 178(76, 378) days. Compared with the late withdrawal group, the patients in early withdrawal group had lower levels of urine volume, serum albumin and parathyroid hormone, and lower rates of gross hematuria and hypertension at the beginning of PD, and received higher rates of methylprednisolone impulse, combined immunosuppressive agents, and hemodialysis or continuous renal replacement therapy (all P<0.05). At the time of PD withdrawal, the levels of serum creatinine, serum calcium, serum albumin and parathyroid hormone in the early withdrawal group were significantly lower than those in the late withdrawal group (all P<0.05). The Kaplan-Meier curves showed that there was no significant difference in the cumulative survival of patients in both groups (log-rank test χ2=3.485, P=0.062). Cox regression analysis revealed serum creatinine≥209 μmol/L at the time of PD withdrawal was an independent risk factor for poor prognosis (HR=5.253,95%CI 1.757-15.702, P=0.003). Conclusions PD can be used for RPGN patients caused by lupus nephritis, ANCA-associated vasculitis and primary nephritis. Serum creatinine≥209 μmol/L at the time of PD withdrawal is an independent risk factor for poor prognosis. 相似文献
Introduction: Research on medication use aims at assessing how much of current pharmacotherapy is rational. In neonates, this is hampered by extensive off-label drug use and limited knowledge.
Areas covered: We report on medication use research and have conducted a systematic review of observational studies on medication use to provide an updated overview on characteristics, objectives, methods, and patterns in hospitalized neonates. Moreover, a review on aspects of medication use for opioids, anti-epileptics, gastric acid-related disorders and respiratory stimulants with emphasis on trends and impact of interventions is presented, illustrating how research on medication use can contribute to improved neonatal pharmacotherapy and more focused research. Medication use reports describe patterns and provide signals on irrational use, benchmarking, or can guide research priorities. Moreover, this may generate information on how neonatal health topics and their pharmacotherapy are handled over time or across regions.
Expert opinion: Research on medicine utilization is relevant, since it will inform us on aspects like trends, variability, or about the impact and pattern of implementation of guidelines in neonates. Further progress necessitates to merge datasets on medication use with clinical characteristics, and perinatal drug use remains an area in need of additional research. 相似文献