The Numerical Simulation of Enhanced Heat Transfer Tubes

AbstractThe enhancing heat transfer mechanism of the transversally corrugated tube,converged-diverging tube and corrugated tube compared with that of the smooth tube was studied in this paper. Here heat transfer models were established with water as the medium of the enhanced heat transfer tubes .We used simplec methods and the standard k- ɛ turbulence model in Fluent and analyzed the impact of different tube structure on heat transfer tubes, finally, achieved visualization of flow field in enhanced heat transfer tubes. it can been concluded from the figures that: within the scope of this study, the order of three tubes according to the merits is transversally corrugated tube, convergeddiverging tube and corrugated tube

Stable functors and cohomology theory in Grothendieck categories

In this paper, we introduce and study a relative complete cohomology theory in Grothendieck categories. Some properties of this cohomology including vanishing and balancedness are given. As an application of our approach, we prove a new balanced result for Tate cohomology in Grothendieck categories.Comment: 25 page

Construction and Analysis of the Index of the Construction Capacity of Civic Science Literacy in China

The Construction of Chinese Civic Scientific Literacy (CCSL) was the outcome of the promotion and implementation of the Outline of National Scientific Literacy. It was significant to evaluate the development of CCSL in each area. In this paper, relevant statistical data of civic scientific literacy were abstracted from the Statistics of Science and Technology Popularization in China to construct the Index of the Construction of Chinese Civic Scientific Literacy (ICCCSL). Through the measurement analysis of the ICCCSL, the status of CCSL in each area was clearly reflected and a theoretical guideline was provided for the fair development of CCSL

Hypoglycemic, hypolipidemic and antioxidant effects of iridoid glycosides extracted from: Corni fructus: Possible involvement of the PI3K-Akt/PKB signaling pathway

Iridoid glycosides (CIG) are the major component of Corni fructus. In this work, we researched the antioxidative, hypoglycemic and lowering blood lipids effects of CIG on diabetic mice induced by a high-fat diet (HFD) and streptozotocin (STZ). Furthermore, to investigate the molecular mechanism of action, the phosphorylation and protein expression of phosphoinositide 3-kinase (PI3K) and its downstream proteins, such as insulin receptor (INSR), protein kinase B (Akt/PKB) and glucose transporter 4 (GLUT4) have been detected. The results showed that CIG significantly improved oral glucose tolerance in diabetic mice. Biochemical indices also revealed that CIG had a positive effect on lipid metabolism and oxidative stress. In addition, CIG can significantly enhance the expression level of the PI3K-Akt/PKB pathway related proteins in skeletal muscle, which is the key pathway of insulin metabolism. These findings show that CIG can improve the hyperglycemia and hyperlipidemia of HFD-STZ-induced diabetic mice through the PI3K-Akt/PKB signaling pathway, and CIG might be a potential medicine or functional food for type 2 diabetes mellitus remedies. © 2018 The Royal Society of Chemistry

Mechanisms of Mating-Behavior Deterioration in Early Aging Male C. elegans

Aging has been a subject of interest throughout history. Scientific studies have focused on lifespan regulation, but ignored many other aspects of aging such as behavioral decline. Research using the model organism C. elegans has contributed significantly to the aging field. In this dissertation, I used C. elegans males to determine the molecular mechanisms of behavioral deterioration during aging. Through mating potency assays, I found that the mating behavior of C. elegans declines at early adulthood, as the mating potency of 3-day-old wild-type males is significantly lower than 1-day-old males. Meanwhile, using both pharmacological tests and calcium imaging, I showed that the excitability of the mating circuit increased during early adulthood. This is consistent with the observation that old males exhibit reduced control over their ability to mate. Caloric restriction is an efficient non-genetic intervention to increase lifespan. I demonstrated here that it also improves mating behavior in 3-day-old males, possibly through reducing the excitability of the mating circuitry by up-regulation of potassium channels and additional metabolic enzymes. To explore the relationship between metabolic status and behavioral deterioration, I characterized the dynamics of male mating deterioration in males containing a deletion in the metabolism-regulator sir-2.1. sir-2.1 encodes a NAD^(+) dependent histone deacetylase, which might be involved in regulating aging. I discovered that sir-2.1(0) males have a premature decline in mating potency and an accelerated increase in the excitability of the mating circuitry. Direct mating behavior observations indicated that a significant proportion of 2-day-old sir-2.1(0) males cannot transfer their sperm into their hermaphrodite mates. Through Ca^(2+) imaging, I found that the genital sex muscles are hyper-contracted during sperm transfer. This hyper-contraction blocks the vas deferens and obstructs sperm release. Furthermore, through qPCR, measurements of metabolites, and diet supplementation, I found that the potentially enhanced catabolism in 1-day-old sir-2.1(0) and 2-day-old wild-type males generates excess reactive oxygen species (ROS). ROS increases the excitability of the mating circuitry and leads to the mating potency decline in subsequent days. Meanwhile, anabolic processes such as gluconeogenesis/glyceroneogenesis are also elevated. These processes shunt pyruvate from oxidative processes to lipid synthesis, and serve as a potential compensatory mechanism to reduce energy and ROS production. In conclusion, I demonstrated that a complex behavior in C. elegans deteriorated during early aging due to the physiological state change, which is possibly caused by ROS induced by both metabolic and stress-response alteration