The effect of ruhrstahl and hereaeus (RH) operation on the mixing of molten steel

The flow and mixing characteristics of molten steel in the RH refining process were studied. A hydraulic simulation system with the geometric similarity ratio of 1:4 was built with 210 tons of RH as the prototype. The influence of different locations of tracers and different operation processes on the mixing of molten steel in ladle was studied. The results show that the RH operation should adopt a large air blowing amount, the insertion depth of the impregnated tube should not be less than 560 mm, and the liquid level of the vacuum chamber should be kept small

The influential factor studies on the cooling rate of roller quenching for ultra-heavy plate

In this paper, the gradient temperature rolling (GTR) method is used to establish the 12-pass rolling model by Deform- 3D finite element (FE) software. The variation of temperature field and strain field of ultra-heavy plate slab under different conditions is systematically studied. The result shows that the more the number of water cooling between the passes during the rolling process, the greater the deformation of the core of slab, and the one of plate rolling with large temperature difference does not appear on near surface but gradually moves to the central part of the plate as cooling times increase

Effect of insulin and metformin on methylation and glycolipid metabolism of peroxisome proliferator-activated receptor γ coactivator-1A of rat offspring with gestational diabetes mellitus

AbstractObjectiveTo discuss the effect of insulin and metformin on a methylation and glycolipid metabolism of peroxisome proliferator-activated receptor γ coactivator-1A (PPARGC1A) of rat offspring with gestational diabetes mellitus (GDM).MethodsA total of 45 pregnant rats received the intraperitoneal injection of streptozotocin to establish the pregnant rat model of GDM. A total of 21 pregnant rats with GDM were randomly divided into three groups, with 7 rats in each group, namely the insulin group, metformin group and control group. Rats in the insulin group received the abdominal subcutaneous injection of 1 mL/kg recombinant insulin glargine at 18:00 every day. Rats in the metformin group received the intragastric infusion of metformin hydrochloride at 18:00 every day, with the first dose of 300 mg/kg. The doses of two groups were adjusted every 3 d to maintain the blood glucose level at 2.65–7.62 mmol/L. Rats in the control group received the intragastric infusion of 1 mL normal saline at 18:00 every day. After the natural delivery of pregnant rats, 10 offspring rats were randomly selected from each group. At birth, 4 wk and 8 wk after the birth of offspring rats, the weight of offspring rats was measured. The blood glucose level of offspring rats was measured at 4 wk and 8 wk, while the level of serum insulin, triglyceride and leptin was measured at 8 wk.ResultsThe weight of offspring rats at birth in the insulin group and metformin group was significantly lower than the one in the control group (P < 0.05), and there was no significant difference at 4 wk and 8 wk among three groups (P > 0.05). The fasting blood glucose and random blood glucose in the insulin group and metformin group at 4 wk and 8 wk were all significantly lower than ones in the control group (P < 0.05); there was no significant difference between the insulin group and metformin group (P > 0.05). The expression of PPARGC1A mRNA in the insulin group and metformin group was significantly higher and the methylation level of PPARGC1A was significantly lower than the one in the control group (P < 0.05); but there was no significant difference between the insulin group and metformin group (P > 0.05). Insulin and leptin at 8 wk in the insulin group and metformin group were significantly higher, while triglyceride was significantly lower than the one in the control group (P < 0.05); triglyceride level in the insulin group was significantly higher than the one in the metformin group (P < 0.05). There was no significant difference in insulin and leptin level between the insulin group and metformin group (P > 0.05).ConclusionsGDM can induce the methylation of PPARGC1A of offspring rats to reduce the expression of PPARGC1A mRNA and then cause the disorder of glycolipid metabolism when the offspring rats grow up; the insulin or metformin in the treatment of pregnant rats with GDM can reduce the methylation level of PPARGC1A and thus improve the abnormal glycolipid metabolism of offspring rats

Neural Basis of Working Memory Enhancement after Acute Aerobic Exercise: fMRI Study of Preadolescent Children

Working memory lies at the core of cognitive function and plays a crucial role in children’s learning, reasoning, problem solving, and intellectual activity. Behavioral findings have suggested that acute aerobic exercise improves children’s working memory; however, there is still very little knowledge about whether a single session of aerobic exercise can alter working memory’s brain activation patterns, as assessed by functional magnetic resonance imaging (fMRI). Therefore, we investigated the effect of acute moderate-intensity aerobic exercise on working memory and its brain activation patterns in preadolescent children, and further explored the neural basis of acute aerobic exercise on working memory in these children. We used a within-subjects design with a counterbalanced order. Nine healthy, right-handed children were scanned with a Siemens MAGNETOM Trio 3.0 Tesla magnetic resonance imaging scanner while they performed a working memory task (N-back task), following a baseline session and a 30-min, moderate-intensity exercise session. Compared with the baseline session, acute moderate-intensity aerobic exercise benefitted performance in the N-back task, increasing brain activities of bilateral parietal cortices, left hippocampus, and the bilateral cerebellum. These data extend the current knowledge by indicating that acute aerobic exercise enhances children’s working memory, and the neural basis may be related to changes in the working memory’s brain activation patterns elicited by acute aerobic exercise

Computational fluid dynamics simulations of blade damage effect on the performance of a transonic axial compressor near stall

Gas turbine axial compressor blades may encounter damage during service for various reasons such as damage by debris from casing or foreign objects impacting the blades, typically near the rotor’s tip. This may lead to deterioration of performance and reduction in the surge margin. The damage breaks the cyclic symmetry of the rotor assembly; thus, computational fluid dynamics simulations have to be performed using full annulus compressor assembly. Moreover, downstream boundary conditions are unknown during rotating stall or surge, and simulations become difficult. This paper presents unsteady computational fluid dynamics analyses of compressor performance with tip curl damage. Computations were performed near the stall boundary. The primary objectives are to understand the effect of the damage on the flow behaviour and compressor stability. Computations for the undamaged rotor assembly were also performed as a reference case. A transonic axial compressor rotor was used for the time-accurate numerical unsteady flow simulations, with a variable area nozzle downstream simulating an experimental throttle. Computations were performed at 60% of the rotor design speed. Two different degrees of damage for one blade and multiple damaged blades were investigated. Rotating stall characteristics differ including the number of stall cells, propagation speed and rotating stall cell characteristics. Contrary to expectations, damaged blades with typical degrees of damage do not show noticeable effects on the global compressor performance near stall

Effect of Physical Exercise on Life Satisfaction of Chinese Primary Students: The Chain Mediating Role of Self-Confidence and Resilience

Life satisfaction is an overall cognitive evaluation of an individual\u27s living condition for the most of time or over a certain period of time according to the standard of one’s own choice. It is an important psychological variable in the developmental stage of children and adolescents. Some studies had shown that life satisfaction was closely related to children\u27s and adolescents\u27 mental health levels, including their emotional and behavioral conditions. However, the Blue Book for Children: China Children\u27s Development Report (2020) published by China Children\u27s Center stated that Chinese students did not fare well in terms of life satisfaction. Previous studies had indicated that physical exercise was an important factor that had a positive effect on life satisfaction, as well as on self-confidence and resilience. Also, there is a correlation between self-confidence, resilience, and life satisfaction. Nonetheless, few studies have researched the role of self-confidence and resilience in the impact of physical exercise on the life satisfaction of primary school students. To explore the mediating role of self-confidence and resilience between physical exercise and life satisfaction, in order to provide a theoretical basis and practical guidance for how to effectively promote life satisfaction and psychological well-being of primary school students in the practice of physical exercise. Group measurements of 1009 students (519 boys and 490 girls; 576 fifth graders and 433 sixth graders) are carried out by using the Scale of Physical Exercise Level, Children and Adolescent Self-Confidence Scale, Children and Adolescent Life Satisfaction Scale, and Adolescent Resilience Scale, and Structural Equation Model and Bootstrap are used to analyze the mediating effect of self-confidence and resilience. The results reveal that there is a positive correlation between physical exercise and life satisfaction (r=0.218), but the effect on life satisfaction is not significant (P=0.516); the indirect effect of physical exercise on life satisfaction consists of two paths: physical exercise to self-confidence to life satisfaction (95% CI: 0.128,0.267); physical exercise to self-confidence to resilience to life satisfaction (95% CI:0.109,0.209). It is concluded that physical exercise has an indirect but significant effect on primary school students\u27 life satisfaction--the independent mediating effect of self-confidence and the chain mediation effect of self-confidence and resilience. The study further confirms that physical exercise can promote students\u27 self-confidence levels and the formation of tenacious psychological quality, thus improving their life satisfaction levels. Therefore, society, schools and families should pay close attention to the positive effects of physical exercise on primary school students’ emotional and behavioral conditions