Subsynchronous Shaft Vibration in an Integrally Geared Expander-Compressor due to Vortex Flow in an Expander

Lectur

Subsynchronous Shaft Vibration in an Integrally Geared Expander-Compressor due to Vortex Flow in an Expander

LecturesSubsynchronous shaft vibration was observed in an integrally geared expander-compressor when the machine was operated with a partial load in the course of plant start up. The root cause of the synchronous shaft vibration was identified, by means of CFD analysis, as the vortex flow which was generated in the downstream piping of the gas expander wheel. OEM installed an object, called “vortex breaker”, in the piping in order to eliminate the excitation force of the vortex flow, and as the result, the subsynchronous shaft vibration disappeared. This paper provides the detailed shaft vibration data, root cause analysis, countermeasure and the result from the countermeasure

Nasal glucagon as a viable alternative for treating insulin‐induced hypoglycaemia in Japanese patients with type 1 or type 2 diabetes : A phase 3 randomized crossover study

Aim: To compare nasal glucagon (NG) with intramuscular glucagon (IMG) for the treatment of insulin‐induced hypoglycaemia in Japanese patients with type 1 (T1DM) or type 2 diabetes mellitus (T2DM). Materials and methods: This phase 3, randomized, open‐label, two‐treatment, two‐period crossover non‐inferiority study enrolled Japanese adults with T1DM or T2DM on insulin therapy, with glycated haemoglobin levels ≤86 mmol/mol (≤10%). After ≥8 hours of fasting, hypoglycaemia was induced with human regular insulin (intravenous infusion). Patients received NG 3 mg or IMG 1 mg approximately 5 minutes after insulin termination. The primary endpoint was the proportion of patients achieving treatment success [plasma glucose (PG) increase to ≥3.9 mmol/L (≥70 mg/dL) or ≥1.1 mmol/L (≥20 mg/dL) increase from the PG nadir within 30 minutes of receiving glucagon]. Non‐inferiority was declared if the upper limit of the two‐sided 95% confidence interval (CI) of the mean difference in the percentage of patients achieving treatment success (IMG minus NG) was <10%. Results: Seventy‐five patients with T1DM (n = 34) or T2DM (n = 41) were enrolled; 72 patients (50 men, 22 women) received ≥1 study drug dose (T1DM, n = 33; T2DM, n = 39). Sixty‐eight patients completed the study and were evaluable. All NG‐ and IMG‐treated patients achieved treatment success (treatment arm difference: 0%; upper limit of two‐sided 95% CI 1.47%); NG met prespecified conditions defining non‐inferiority versus IMG. Glucagon was rapidly absorbed after both nasal and intramuscular administration; PG profiles were similar between administration routes during the first 60 minutes post dose. Study drug‐related treatment‐emergent adverse events affecting >2 patients were rhinalgia, increased blood pressure, nausea, ear pain and vomiting in the NG group, and nausea and vomiting in the IMG group. Conclusion: Nasal glucagon was non‐inferior to IMG for successful treatment of insulin‐induced hypoglycaemia in Japanese patients with T1DM/T2DM, supporting use of NG as a rescue treatment for severe hypoglycaemia

Sleep Consolidates Motor Learning of Complex Movement Sequences in Mice

Introduction: Sleep-dependent consolidation of motor learning has been extensively studied in humans, but it remains unclear why some, but not all, learned skills benefit from sleep. Aims and methods: Here, we compared 2 different motor tasks, both requiring the mice to run on an accelerating device. In the rotarod task, mice learn to maintain balance while running on a small rod, while in the complex wheel task, mice run on an accelerating wheel with an irregular rung pattern. Results: In the rotarod task, performance improved to the same extent after sleep or after sleep deprivation (SD). Overall, using 7 different experimental protocols (41 sleep deprived mice, 26 sleeping controls), we found large interindividual differences in the learning and consolidation of the rotarod task, but sleep before/after training did not account for this variability. By contrast, using the complex wheel, we found that sleep after training, relative to SD, led to better performance from the beginning of the retest session, and longer sleep was correlated with greater subsequent performance. As in humans, the effects of sleep showed large interindividual variability and varied between fast and slow learners, with sleep favoring the preservation of learned skills in fast learners and leading to a net offline gain in the performance in slow learners. Using Fos expression as a proxy for neuronal activation, we also found that complex wheel training engaged motor cortex and hippocampus more than the rotarod training. Conclusions: Sleep specifically consolidates a motor skill that requires complex movement sequences and strongly engages both motor cortex and hippocampus

Subsynchronous Shaft Vibration in an Integrally Geared Expander-Compressor due to Vortex Flow in an Expander

LecturesSubsynchronous shaft vibration was observed in an integrally geared expander-compressor when the machine was operated with a partial load in the course of plant start up. The root cause of the synchronous shaft vibration was identified, by means of CFD analysis, as the vortex flow which was generated in the downstream piping of the gas expander wheel. OEM installed an object, called “vortex breaker”, in the piping in order to eliminate the excitation force of the vortex flow, and as the result, the subsynchronous shaft vibration disappeared. This paper provides the detailed shaft vibration data, root cause analysis, countermeasure and the result from the countermeasure

Subsynchronous Shaft Vibration in an Integrally Geared Expander-Compressor due to Vortex Flow in an Expander

LecturesSubsynchronous shaft vibration was observed in an integrally geared expander-compressor when the machine was operated with a partial load in the course of plant start up. The root cause of the synchronous shaft vibration was identified, by means of CFD analysis, as the vortex flow which was generated in the downstream piping of the gas expander wheel. OEM installed an object, called “vortex breaker”, in the piping in order to eliminate the excitation force of the vortex flow, and as the result, the subsynchronous shaft vibration disappeared. This paper provides the detailed shaft vibration data, root cause analysis, countermeasure and the result from the countermeasure

Culture temperature affects human chondrocyte messenger RNA expression in monolayer and pellet culture systems

Cell-based therapy has been explored for articular cartilage regeneration. Autologous chondrocyte implantation is a promising cell-based technique for repairing articular cartilage defects. However, there are several issues such as chondrocyte de-differentiation. While numerous studies have been designed to overcome some of these issues, only a few have focused on the thermal environment that can affect chondrocyte metabolism and phenotype. In this study, the effects of different culture temperatures on human chondrocyte metabolism- and phenotype-related gene expression were investigated in 2D and 3D environments. Human chondrocytes were cultured in a monolayer or in a pellet culture system at three different culture temperatures (32° C, 37° C, and 41° C) for 3 days. The results showed that the total RNA level, normalized to the threshold cycle value of internal reference genes, was higher at lower temperatures in both culture systems. Glyceraldehyde-3- phosphate dehydrogenase (GAPDH) and citrate synthase (CS), which are involved in glycolysis and the citric acid cycle, respectively, were expressed at similar levels at 32° C and 37° C in pellet cultures, but the levels were significantly lower at 41° C. Expression of the chondrogenic markers, collagen type IIA1 (COL2A1) and aggrecan (ACAN), was higher at 37° C than at 32° C and 41° C in both culture systems. However, this phenomenon did not coincide with SRY (sex-determining region Y)-box 9 (SOX9), which is a fundamental transcription factor for chondrogenesis, indicating that a SOX9-independent pathway might be involved in this phenomenon. In conclusion, the expression of chondrocyte metabolism-related genes at 32° C was maintained or enhanced compared to that at 37° C. However, chondrogenesis-related genes were further induced at 37° C in both culture systems. Therefore, manipulating the culture temperature may be an advantageous approach for regulating human chondrocyte metabolic activity and chondrogenesis

Immature articular cartilage and subchondral bone covered by menisci are potentially susceptive to mechanical load

BACKGROUND: The differences of mechanical and histological properties between cartilage covered by menisci and uncovered by menisci may contribute to the osteoarthritis after meniscectomy and these differences are not fully understood. The purpose of this study is to investigate potential differences in the mechanical and histological properties, and in particular the collagen architecture, of the superficial cartilage layer and subchondral bone between regions covered and uncovered by menisci using immature knee. METHODS: Osteochondral plugs were obtained from porcine tibial cartilage that was either covered or uncovered by menisci. Investigation of the thickness, mechanical properties, histology, and water content of the cartilage as well as micro-computed tomography analysis of the subchondral bone was performed to compare these regions. Collagen architecture was also assessed by using scanning electron microscopy. RESULTS: Compared to the cartilage uncovered by menisci, that covered by menisci was thinner and showed a higher deformity to compression loading and higher water content. In the superficial layer of cartilage in the uncovered regions, collagen fibers showed high density, whereas they showed low density in covered regions. Furthermore, subchondral bone architecture varied between the 2 regions, and showed low bone density in covered regions. CONCLUSIONS: Cartilage covered by menisci differed from that uncovered in both its mechanical and histological properties, especially with regards to the density of the superficial collagen layer. These regional differences may be related to local mechanical environment in normal condition and indicate that cartilage covered by menisci is tightly guarded by menisci from extreme mechanical loading. Our results indicate that immature cartilage degeneration and subchondral microfracture may occur easily to extreme direct mechanical loading in covered region after meniscectomy

Contributions of biarticular myogenic components to the limitation of the range of motion after immobilization of rat knee joint

BACKGROUND: Muscle atrophy caused by immobilization in the shortened position is characterized by a decrease in the size or cross-sectional area (CSA) of myofibers and decreased muscle length. Few studies have addressed the relationship between limitation of the range of motion (ROM) and the changes in CSA specifically in biarticular muscles after atrophy because of immobilization. We aimed to determine the contribution of 2 distinct muscle groups, the biarticular muscles of the post thigh (PT) and those of the post leg (PL), to the limitation of ROM as well as changes in the myofiber CSAs after joint immobilization surgery. METHODS: Male Wistar rats (n = 40) were randomly divided into experimental and control groups. In the experimental group, the left knee was surgically immobilized by external fixation for 1, 2, 4, 8, or 16 weeks (n = 5 each) and sham surgery was performed on the right knee. The rats in the control groups (n = 3 per time point) did not undergo surgery. After the indicated immobilization periods, myotomy of the PT or PL biarticular muscles was performed and the ROM was measured. The hamstrings and gastrocnemius muscles from the animals operated for 1 or 16 weeks were subjected to morphological analysis. RESULTS: In immobilized knees, the relative contribution of the PT biarticular myogenic components to the total restriction reached 80% throughout the first 4 weeks and decreased thereafter. The relative contribution of the PL biarticular myogenic components remained <20% throughout the immobilization period. The ratio of the myofiber CSA of the immobilized to that of the sham-operated knees was significantly lower at 16 weeks after surgery than at 1 week after surgery only in the hamstrings. CONCLUSIONS: The relative contribution of the PT and PL components to myogenic contracture did not significantly change during the experimental period. However, the ratio of hamstrings CSAs to the sham side was larger than the ratio of medial gastrocnemius CSAs to the sham side after complete atrophy because of immobilization