High Temperature Corrosion Behaviors of the Superheater Materials

AbstractThe high temperature corrosion tests are performed on 20#steel, TP347H and superalloy C22. The high temperature corrosion behaviors of these superheater materials in the synthetic salt containing 80wt-%KCl+20wt-%K2SO4 have been investigated under the oxidizing atmosphere at a temperature of 650°C for 218hours. For comparison, the column diagram has been obtained by mass loss. The scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) is used to characterize the surface morphology and compositions of the corrosion products. The results have shown that the superalloy C22 exhibits the high corrosion resistance

A dynamical approach to identify vertices centrality in complex networks

In this paper, we proposed a dynamical approach to assess vertices centrality according to the synchronization process of the Kuramoto model. In our approach, the vertices dynamical centrality is calculated based on the Difference of vertices Synchronization Abilities (DSA), which are different from traditional centrality measurements that are related to the topological properties. Through applying our approach to complex networks with a clear community structure, we have calculated all vertices' dynamical centrality and found that vertices at the end of weak links have higher dynamical centrality. Meanwhile, we analyzed the robustness and efficiency of our dynamical approach through testing the probabilities that some known vital vertices were recognized. Finally, we applied our dynamical approach to identify community due to its satisfactory performance in assessing overlapping vertices. Our present work provides a new perspective and tools to understand the crucial role of heterogeneity in revealing the interplay between the dynamics and structure of complex networks

Time and spatial distribution of multidrug-resistant tuberculosis among Chinese people, 1981–2006: a systematic review

SummaryObjectivesWe aimed to investigate trends in the prevalence of multidrug-resistant tuberculosis (MDR-TB) among Chinese people from first report to 2006, and to detect the high prevalence regions in order to guide control efforts.Materials and methodsThe CBM, VIP, CNKI, and MEDLINE databases were searched through both keywords and subject headings. The literature was screened, and two investigators assessed the quality and extracted the data. Trends in MDR-TB prevalence in three groups – primary, acquired, and combined MDR-TB – were examined separately, using the Cochran–Armitage trend test. Differences were tested with the Kruskal–Wallis test. High prevalence provinces were explored through comparison of the 95% confidence interval (95% CI) with the national average level.ResultsOverall 169 studies were included, with 165 in Chinese and four in English. One hundred and sixteen studies concerned primary MDR-TB, 103 acquired MDR-TB, and 130 combined MDR-TB, with total positive Mycobacterium tuberculosis (MTB) isolates of 110 076, 25 187, and 150 233, respectively. The prevalences of MDR-TB in the three groups in 2005 were 2.64-, 6.20-, and 3.84-times that of 1985, respectively, all showing an upward trend (p<0.05). The prevalences among the three groups were significantly different (p<0.05), with acquired drug resistance (27.5%, 95% CI 26.9–28.1%) much higher than primary drug resistance (4.3%, 95% CI 4.2–4.4%), and combined resistance (9.9%, 95% CI 9.8–10.1%) in between. The top three prevalence regions for primary, acquired, and combined MDR-TB were distributed in the zone from the northeast to the southwest of China, with Hebei, Tibet, and Shanxi having an extremely high prevalence.ConclusionsThe prevalence of MDR-TB among the Chinese people has shown an upward trend since 1985. It is necessary to continue to monitor this trend in China. Special attention should be paid to provinces distributed in the zone from the northeast to the southwest of China for MDR-TB surveillance, research, and control

Preparation of terminal blend/ grafting activated crumb rubber composite modified asphalt based on response surface methodology

Recycling waste tires, crushing them into crumb rubber (CR) and adding them to asphalt can effectively improve the performance and prolong the service life of asphalt pavement. However, the crumb rubber modified asphalt (CRMA) prepared by aforementioned process is prone to segregation during storage and transportation. The terminal blend rubber asphalt (TB) prepared with fine rubber powder by high-speed shearing at high temperature for long time, which effectively improves the storage stability and working performance of crumb rubber modified asphalt, but reduces the high-temperature performance. In this study, grafting activated crumb rubber (GACR) was incorporated into TB to improve its high temperature performance without impairing storage stability. Using shearing temperature, shearing time and grafting activated crumb rubber content as influencing factors, the response surface method (RSM) was carried out to optimize the preparation process. The results indicated that 180°C was a critical temperature, and the swelling of crumb rubber dominated with the temperature below it, but the desulfurization prevailed with the temperature above it. The extension of time favored the swelling of crumb rubber at low temperature but promoted desulfurization at high temperature. With the increase of crumb rubber content, the high temperature performance of modified asphalt improved whereas the storage stability deteriorated. According to the determination of response values and the prediction of optimal values, the suitable preparation conditions and parameters were recommended as shearing temperature of 190°C, shearing time of 90 min, and GACR content of 15%. The composite modified asphalt prepared through the optimized process showed good high temperature stability and storage stability

Analysis and prediction of storability and storage quality of pear fruit based on clustering and time series analysis

Objective: The storability and storage quality of three pear varieties were evaluated to provide theoretical support for variety breeding and fresh-keeping technology. Methods: Zaoshengxinshui, HJ18 and HJ67 pear with similar genetic background were used as test materials. Fruit with the same maturity were stored in a cold storage with a temperature of （1.0±0.5） ℃ and a relative humidity of 85%~90% for 60 days. The fruit texture, sugar and acid and volatile substances were determined every 10 days, divide storage period and quality based on clustering, principal components and time series analysis. Results: The results showed that the fruit texture, sugar, acid and volatile substances of the three pear varieties were regulated by storage time, and there was a certain correlation among different indexes. Fourteen quality evaluation parameters could be simplified into 8 indexes: firmness, chewiness, compactness, brittleness, elasticity, malic acid, citric acid, soluble solids content （SSC） and fructose. The contribution rate of sensors S2, 6, 7, 8 and 9 was larger. Based on fourteen quality indexes, HJ67 was in a relatively independent space with Zaosheng Xinshui and HJ18 during storage. Based on the response values of ten sensors, the three varieties had spatial intersection, which had not been effectively distinguished. The storage time of three pear varieties was divided into different intervals, among which HJ67 was divided into four periods: 0~20 days, 30 days, 40~50 days and 60 days based on texture, nonvolatile and volatile substances. Conclusion: It is concluded that the texture, sugars and acids contents and volatile matter of HJ67 are significantly different from those of Zaoshengxinshui and HJ18, that has a rich flavor. The change of fruit texture of three pear varieties can be well fitted by exponential equation, and the change of sugar and acid content can be well described by nonlinear equation. The prediction errors of the two prediction models are low. Based on principal component analysis, cluster analysis and time series analysis, the storage period and comprehensive quality of three pear varieties can be comprehensively and objectively evaluated

Analysis and characterization of the functional TGFβ receptors required for BMP6-induced osteogenic differentiation of mesenchymal progenitor cells

Although BMP6 is highly capable of inducing osteogenicdifferentiation of mesenchymal progenitor cells (MPCs), themolecular mechanism involved remains to be fully elucidated.Using dominant negative (dn) mutant form of type I and type IITGFβ receptors, we demonstrated that three dn-type I receptors(dnALK2, dnALK3, dnALK6), and three dn-type II receptors(dnBMPRII, dnActRII, dnActRIIB), effectively diminished BMP6-induced osteogenic differentiation of MPCs. These findingssuggested that ALK2, ALK3, ALK6, BMPRII, ActRII and ActRIIBare essential for BMP6-induced osteogenic differentiation ofMPCs. However, MPCs in this study do not express ActRIIB.Moreover, RNA interference of ALK2, ALK3, ALK6, BMPRIIand ActRII inhibited BMP6-induced osteogenic differentiationin MPCs. Our results strongly suggested that BMP6-inducedosteogenic differentiation of MPCs is mediated by its functionalTGFβ receptors including ALK2, ALK3, ALK6, BMPRII, andActRII. [BMB Reports 2013; 46(2): 107-112

The oxidant-antioxidant imbalance was involved in the pathogenesis of chronic rhinosinusitis with nasal polyps

BackgroundAlthough oxidative stress is involved in the pathophysiological process of chronic rhinosinusitis with nasal polyps (CRSwNP), the specific underlying mechanism is still unclear. Whether antioxidant therapy can treat CRSwNP needs further investigation.MethodsImmunohistochemistry, immunofluorescence, western blotting and quantitative polymerase chain reaction (qPCR) analyses were performed to detect the distribution and expression of oxidants and antioxidants in nasal polyp tissues. qPCR revealed correlations between oxidase, antioxidant enzymes and inflammatory cytokine levels in CRSwNP patients. Human nasal epithelial cells (HNEpCs) and primary macrophages were cultured to track the cellular origin of oxidative stress in nasal polyps(NPs) and to determine whether crocin can reduce cellular inflammation by increasing the cellular antioxidant capacity.ResultsThe expression of NOS2, NOX1, HO-1 and SOD2 was increased in nasal epithelial cells and macrophages derived from nasal polyp tissue. Oxidase levels were positively correlated with those of inflammatory cytokines (IL-5 and IL-6). Conversely, the levels of antioxidant enzymes were negatively correlated with those of IL-13 and IFN-γ. Crocin inhibited M1 and M2 macrophage polarization as well as the expression of NOS2 and NOX1 and improved the antioxidant capacity of M2 macrophages. Moreover, crocin enhanced the ability of antioxidants to reduce inflammation via the KEAP1/NRF2/HO-1 pathway in HNEpCs treated with SEB or LPS. Additionally, we observed the antioxidant and anti-inflammatory effects of crocin in nasal explants.ConclusionOxidative stress plays an important role in the development of CRSwNP by promoting various types of inflammation. The oxidative stress of nasal polyps comes from epithelial cells and macrophages. Antioxidant therapy may be a promising strategy for treating CRSwNP

The Technology and Quality Research of Citrus Passion Fruit Compound Juice by Response Surface Methodology

To explore the best process quality of citrus and passion fruit to make compound juice, the pulp of citrus and passion fruit were used. After squeezing the juice and coarsely filtering, the raw juice of citrus and passion fruit was mixed in proportion, and pectinase was added as a clarifying agent for clarification. On the basis of single factor, three factors of clarification agent concentration, clarification temperature and clarification time were selected to design and analyze the optimal process conditions of the Box-Benhnken method in the response surface method. The optimal combination of processes selected through sensory evaluation was as follows: the mixing ratio of citrus and passion fruit raw juice was 2∶1; 0.19% of clarifying agent was added; the clarification temperature was 49 ℃; and the clarification time was 1.5 h. The compound juice of citrus and passion fruit is orange-yellow in color, rich fruit aroma, well-coordinated flavor and taste, and of good quality