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1.
A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r＝50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results. 相似文献
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Dong-Yi Jin Cong-Lin Liu Jun-Nan Tang Zhao-Zhong Zhu Xue-Xi Xuan Xiao-Dan Zhu Yun-Zhe Wang Tian-Xia Zhang De-Liang Shen Xiao-Fang Wang Guo-Ping Shi Jin-Ying Zhang 《Journal of Zhejiang University. Science. B》2017,18(8):685-695
Background
Coronary heart disease (CHD) is characterized by arterial wall inflammation and matrix degradation. Matrix metalloproteinase (MMP)-22 and -29 and pro-inflammatory cytokine interleukin-18 (IL18) are present in human hearts. IL18 may regulate MMP-22 and -29 expression, which may correlate with CHD progression.Methods and results
Immunoblot analysis showed that IL18 induced MMP-22 expression in human aortic smooth muscle cells. The Mann Whitney test from a prospective study of 194 CHD patients and 68 non-CHD controls demonstrated higher plasma levels of IL18, MMP-22 and -29 in CHD patients than in the controls. A logistic regression test suggested that plasma IL18 (odds ratio (OR)=1.131, P=0.007), MMP-22 (OR=1.213, P=0.040), and MMP-29 (OR=1.198, P=0.033) were independent risk factors of CHD. Pearson’s correlation test showed that IL18 (coefficient (r)=0.214, P=0.045; r=0.246, P=0.031) and MMP-22 (r=0.273, P=0.006; r=0.286, P=0.012) were associated with the Gensini score before and after adjusting for potential confounding factors. The multivariate Pearson’s correlation test showed that plasma MMP-22 levels correlated positively with high-sensitive-C-reactive protein (hs-CRP) (r=0.167, P=0.023), and MMP-29 levels correlated negatively with triglyceride (r=?0.169, P=0.018). Spearman’s correlation test indicated that plasma IL18 levels associated positively with plasma MMP-22 (r=0.845, P<0.001) and MMP-29 (r=0.548, P<0.001).Conclusions
Our observations suggest that IL18, MMP-22 and -29 serve as biomarkers and independent risk factors of CHD. Increased systemic IL18 in CHD patients may contribute to elevated plasma MMP-22 and -29 levels in these patients.4.
1 Introduction AmatrixA∈Cn×missaidtobecentrohermitianifA =Jn AJm,andskewcentrohermitianifA =-Jn AJm,where Adenotetheconjugateofthema trixAandJlisthepermutationmatrixoforderlwithonesonthecrossdiagonal(bottomlefttotopright)andzeroselsewhere .ThehermitianToeplitzmatricesformanimportantsubclassofcentrohermi tianmatriceswhichoccurnaturallyindigitalsignalprocessingandotherareas ,seeforinstance[1] andreferencetherein .Thecentrohermitianandrelatedmatricesrecentlyplayanimportantroleinthesolu… 相似文献
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The aim of this study was to examine the potential impact of the representational characteristics of models and students’ educational levels on students’ views of scientific models and modeling (VSMM). An online multimedia questionnaire was designed to address three major aspects of VSMM, namely the nature of models, the nature of modeling, and the purpose of models. The three scales of representational characteristics included modality, dimensionality, and dynamics. A total of 102 eighth graders and 87 eleventh graders were surveyed. Both quantitative data and written responses were analyzed. The influence of the representational characteristics seemed to be more salient on the nature of models and the purpose of models. Some interactions between the educational levels and the representational characteristics showed that the high school students were more likely to recognize textual representations and pictorial representations as models, while also being more likely to appreciate the differences between 2D and 3D models. However, some other differences between educational levels did not necessarily suggest that the high school students attained more sophisticated VSMM. For instance, in considering what information should be included in a model, students’ attention to particular affordances of the representation can lead to a more naive view of modeling. Implications for developing future questionnaires and for teaching modeling are suggested in this study. 相似文献
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A circular jet has broad and important applications in practical engineering. Most research in this area has focused on a free jet, a wall jet or a vertical jet in a bounded domain. In this study, the mean velocities of circular offset jets were studied for four jet exit Froude numbers (Fr), three offset heights (S) (S/d=1, 2, 3) and three submergence ratios (ht/S) (surface jet, mixed jet, and submerged jet) in a bounded basin. Based on the results, we propose a velocity decay formula for a circular jet. The lateral velocity spread was more consistent with Gaussian and Cauchy–Lorentz distributions than the vertical velocity. Moreover, Fr had little effect on the decay of the mean velocity for a circular jet when Re>1×104. The lateral and vertical spreads showed a quadratic relationship with the streamwise distance for different values of Fr at X/d<10. The positions of maximum mean velocity decay were independent of Fr and S/d when X/d<10. The spread rate was more uniform in the lateral direction than that in the vertical direction in a certain region for different S/d and ht/S. Therefore, the decay, spread, and maximum velocity position of the mean velocity for a circular offset jet can remain stable under different values of Fr, offset height, and submergence ratio. 相似文献
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The objective of this study was to describe the fecal microbiota succession of piglets from birth to post-weaning by pyrosequencing. The dominant bacterial phyla were Bacteroidetes, Firmicutes, Proteobacteria, and Fusobacteria, although the composition of the fecal microbiota changed as the piglets grew. Bacteroides, Parabacteroides, Prevotella, Lactobacillus, unclassified Lachnospiraceae, Ruminococcus, Oscillospira, Phascolarctobacterium, and Desulfovibrio were the core genera in the feces of piglets and existed from birth to post-weaning. Bacteroides was the most abundant at birth; however, the proportion of Bacteroides decreased as the piglets aged, while the proportion of Prevotella increased until it became the most abundant genus at the post-weaning stage. Principal coordinate analysis indicated that the microbial communities of piglet fecal samples from birth to post-weaning could be separated into four groups according to the similarity of community composition. These corresponded to time points on day 0 (birth); day 7; days 14, 21, and 28 (pre-weaning); and day 35 (post-weaning). This study suggests that the development of the intestinal microbiota in the piglet is a gradual and sequential process. This methodology establishes a basis for broader studies to investigate the microbiota of the piglet intestinal tract. 相似文献
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Parth Prashant Karnawat 《Resonance》2018,23(5):591-596
As an easy application of the intermediate value theorem, one can show that for any continuous function f: [0, 1] → ? with f (0) = f (1), there are points a, a + 1/2 both in [0, 1] such that f (a) = f (a + 1/2). In this note, we show that this property holds with 1/2 replaced by any number of the form 1/n for a positive integer n. More interestingly, we show that this is false for every number not of the form 1/n. 相似文献
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Objective
To evaluate the comparative therapeutic efficacy of radiofrequency ablation (RFA) and hepatic resection (HR) for breast cancer liver metastases (BCLMs).Methods
Studies that had examined the outcomes for both RFA and HR for BCLM were identified by searching the electronic databases PubMed, EMBASE, and the Cochrane Library. Pooled analyzes of the overall survival (OS), disease-free survival (DFS), and short-term outcomes of BCLM were performed.Results
Patients with BCLM gained many more survival benefits from HR than from RFA with regard to the 3-year OS rate (combined odds ratio (OR) 0.41, 95% confidence interval (CI) 0.29–0.59, P<0.001), 5-year OS rate (combined OR 0.38, 95% CI 0.32–0.46, P<0.001), 3-year DFS (combined OR 0.36, 95% CI 0.27–0.49, P<0.001), and 5-year DFS (combined OR 0.51, 95% CI 0.40–0.66, P<0.001). RFA had fewer postoperative complications (combined OR 0.30, 95% CI 0.20–0.44, P<0.001) and shorter hospital stays (combined OR -9.01, 95% CI -13.49–4.54, P<0.001) than HR.Conclusions
HR takes precedence over RFA in the treatment of patients with BCLM, considering the better survival rate. RFA gives rise to fewer complications and can be carried out with a shorter hospital stay, compared to HR. RFA should be reserved for patients who are not optimum candidates for resection.11.
Bai-kui Wang Yu-long Mao Li Gong Xin Xu Shou-qun Jiang Yi-bing Wang Wei-fen Li 《Journal of Zhejiang University. Science. B》2018,19(10):785-795
Objective
Salmonella enterica remains a major cause of food-borne disease in humans, and Salmonella Typhimurium (ST) contamination of poultry products is a worldwide problem. Since macrophages play an essential role in controlling Salmonella infection, the aim of this study was to evaluate the effect of glycyrrhizic acid (GA) on immune function of chicken HD11 macrophages.Methods
Chicken HD11 macrophages were treated with GA (0, 12.5, 25, 50, 100, 200, 400, or 800 μg/ml) and lipopolysaccharide (LPS, 500 ng/ml) for 3, 6, 12, 24, or 48 h. Evaluated responses included phagocytosis, bacteria-killing, gene expression of cell surface molecules (cluster of differentiation 40 (CD40), CD80, CD83, and CD197) and antimicrobial effectors (inducible nitric oxide synthase (iNOS), NADPH oxidase-1 (NOX-1), interferon-γ (IFN-γ), LPS-induced tumor necrosis factor (TNF)-α factor (LITAF), interleukin-6 (IL-6), and IL-10), and production of nitric oxide (NO) and hydrogen peroxide (H2O2).Results
GA increased the internalization of both fluorescein isothiocyanate (FITC)-dextran and ST by HD11 cells and markedly decreased the intracellular survival of ST. We found that the messenger RNA (mRNA) expression of cell surface molecules (CD40, CD80, CD83, and CD197) and cytokines (IFN-γ, IL-6, and IL-10) of HD11 cells was up-regulated following GA exposure. The expression of iNOS and NOX-1 was induced by GA and thereby the productions of NO and H2O2 in HD11 cells were enhanced. Notably, it was verified that nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK) pathways were responsible for GA-induced synthesis of NO and IFN-γ gene expression.Conclusions
Taken together, these results suggested that GA exhibits a potent immune regulatory effect to activate chicken macrophages and enhances Salmonella-killing capacity.12.
Shao-hua Hu Shu-xing Yuan Hai Qu Tao Jiang Ya-jun Zhou Ming-xi Wang De-song Ming 《Journal of Zhejiang University. Science. B》2016,17(3):188-199
Bacteria of the genus Myroides (Myroides spp.) are rare opportunistic pathogens. Myroides sp. infections have been reported mainly in China. Myroides sp. is highly resistant to most available antibiotics, but the resistance mechanisms are not fully elucidated. Current strain identification methods based on biochemical traits are unable to identify strains accurately at the species level. While 16S ribosomal RNA (rRNA) gene sequencing can accurately achieve this, it fails to give information on the status and mechanisms of antibiotic resistance, because the 16S rRNA sequence contains no information on resistance genes, resistance islands or enzymes. We hypothesized that obtaining the whole genome sequence of Myroides sp., using next generation sequencing methods, would help to clarify the mechanisms of pathogenesis and antibiotic resistance, and guide antibiotic selection to treat Myroides sp. infections. As Myroides sp. can survive in hospitals and the environment, there is a risk of nosocomial infections and pandemics. For better management of Myroides sp. infections, it is imperative to apply next generation sequencing technologies to clarify the antibiotic resistance mechanisms in these bacteria. 相似文献
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Chen Zhi-guo 《浙江大学学报(A卷英文版)》2006,7(2):198-202
In this paper we give a short survey on a problem on extremal quasiconformal extensions. It had been a conjecture for a long time that the dilatations K0(h) and K1(h) are equal before Anderson and Hinkkanen disproved this by constructing concrete examples of a family of affine mappings of some parallelograms. The problem also engendered many interesting results. At the end of the current paper, we discuss relationships among K0(h), H(h) and K1(h) as a concluding remark. 相似文献
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Ai-bin Zhang Ye Wang Chen Hu Yan Shen Shu-sen Zheng 《Journal of Zhejiang University. Science. B》2017,18(6):532-538
Objective
The aim of this study was to compare complications and oncologic outcomes of patients undergoing laparoscopic distal pancreatectomy (LDP) and open distal pancreatectomy (LDP) at a single center.Methods
Distal pancreatectomies performed for pancreatic ductal adenocarcinoma during a 4-year period were included in this study. A retrospective analysis of a database of this cohort was conducted.Results
Twenty-two patients underwent LDP for pancreatic ductal adenocarcinoma, in comparison to seventy-six patients with comparable tumor characteristics treated by LDP. No patients with locally advanced lesions were included in this study. Comparing LDP group to LDP group, there were no significant differences in operation time (P=0.06) or blood loss (P=0.24). Complications (pancreatic fistula, P=0.62; intra-abdominal abscess, P=0.44; postpancreatectomy hemorrhage, P=0.34) were similar. There were no significant differences in the number of lymph nodes harvested (11.2±4.6 in LDP group vs. 14.4±5.5 in LDP group, P=0.44) nor the rate of patients with positive lymph nodes (36% in LDP group vs. 41% in LDP group, P=0.71). Incidence of positive margins was similar (9% in LDP group vs. 13% in LDP group, P=0.61). The mean overall survival time was (29.6±3.7) months for the LDP group and (27.6±2.1) months for LDP group. There was no difference in overall survival between the two groups (P=0.34).Conclusions
LDP is a safe and effective treatment for selected patients with pancreatic ductal adenocarcinoma. A slow-compression of pancreas tissue with the GIA stapler is effective in preventing postoperative pancreatic fistula. The oncologic outcome is comparable with the conventional open approach. Laparoscopic radical antegrade modular pancreatosplenectomy contributed to oncological clearance.16.
Starting with an elementary problem that appeared in the Putnam mathematics competition, we proceed to discuss some techniques of transcendental number theory and prove the following result. If p, q, r are distinct primes and if c is a real number with the property that pc, qc, rc are integers, then c must be a non-negative integer. The tools used are some linear algebra and complex analysis. The zero-density estimate method discussed here was used by Alan Baker to prove his celebrated theorem on linear forms in logarithms. The question as to whether we can replace three primes by two primes is an open question. 相似文献
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This empirically driven paper is about workplace learning with specific focus on the ‘work’ of consuming practices. By consuming we refer to the eating, and the drinking, and (at times) to the smoking that workers, in most organisations, do on a daily basis. Indeed, it is the quotidian nature of consuming, coupled with its absence from workplace learning research that make them noteworthy practices to explore. In using the term practice we draw on the recent tranche of practice based theorisations: notably Schatzki (1996, Organization Studies, 26(3), 465-484, 2005, Organization Studies, 27(12), 1863-1873, 2006) and Gherardi (Human Relations, 54(1), 131-139, 2001, 2006, Learning Organization, 16(5), 352-359, 2009). The paper frames consuming practices as ‘dispersed’ (general) practices and, illustrated through empirical data from multiple projects, we progressively outline how these contribute to the learning of ‘integrative’ (specialized work) practices. Our overall aim is to (re)position consuming practices from prosaic, to having much relevance for research on workplace learning. 相似文献
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This key paper is intended to produce a comparison of Bildung and globalization, acknowledging that Bildung and globalization are both fuzzy concepts. Our comparison of globalization and Bildung therefore is to be seen as a construction. To reach this objective, we start with the identification of dimensions of the concept of globalization based predominantly on sociological research. This analysis is followed by explication of dimensions of the concept of Bildung as they can be identified before a frame of globalization. We want to find out whether it makes sense to see globalization as one part of a new model of Bildung. In the conclusion, we demonstrate the normativity of each and any theory of Bildung in globalizing times, and we explain why it is necessary to reflect on the normativity of the different concepts. We indicate where we see connections with the other papers of this special issue of “Zeitschrift für Erziehungswissenschaft”. 相似文献