825 research outputs found
Role of Atmosphere-ocean-ice Interaction in the Linkage between December Bering Sea Ice and Subsequent February Surface Air Temperature Over North America
Under embargo until 2023-08-16This study revealed that the interannual variations of December Bering Sea ice and subsequent February surface air temperature (SAT) over North America are significantly correlated during 2000/01-2020/21, which is not the case during 1966/67-1999/2000. During 2000/01-2020/21, reduced December Bering Sea ice is generally followed by a February meridional dipole pattern in the atmospheric circulation over North America, which provides favorable conditions for colder temperatures. Further analysis elucidates that the intensified persistence of December Bering Sea ice anomaly might be responsible for the identified change in such a lead-lag sea ice-SAT linkage. During 2000/01-2020/21, the Bering Sea ice anomaly in December can persist into the subsequent February during which the Bering Sea ice anomaly can stimulate an eastward-propagating Rossby wave train propagating to North America and causing the meridional dipole pattern. The longer persistence of December Bering Sea ice anomaly during 2000/01-2020/21 is attributed to the interdecadal intensified atmosphere-ocean-ice interaction over the Bering Sea - a positive feedback loop that favors the persistence of Bering Sea ice anomaly. A negative sea-ice concentration anomaly with more open water in the Bering Sea would allow the ocean to release more heat and warm more the air aloft. This will lead to more downward longwave radiation, preventing the winter sea ice growth and helping maintain the Bering Sea ice anomaly. Results of this study indicates that the intensity of atmosphere-ocean-ice interaction in the Bering Sea may modulate the linkage between the February SAT over North America and the preceding December Bering Sea ice.publishedVersio
A Knowledge-Based Service Composition Algorithm with Better QoS in Semantic Overlay
A semantic overlay network (SON) is a visual framework clustered under similar metaknowledge units such as ontologies, algorithms, and rule engines. Knowledge-based service composition (KC) has become a prominent aspect of building new and creative composed service through a combination of semantically similar information at the knowledge level. In this study, a promising approach to construct a standard knowledge model is developed to utilize the progress of KC. To evaluate and optimize the composition, we define the quantity of service (QoS) regarding user requirements in the KC instance, and a KC instance path with better QoS is found in the model using the KC algorithm. Simulation results prove that our approach has a tradeoff between efficiency and equality
Historical and future runoff changes in the Yangtze River Basin from CMIP6 models constrained by a weighting strategy
Based on the ERA5-Land datasets from 1981–2020, a decadal oscillation has been found in the variation of summer runoff in the middle and lower reaches of the Yangtze River Basin (MLYRB). The oscillation suggests that the MLYRB will experience increased runoff in the next few decades after 2020, which saw a record high runoff in the MLYRB. The decadal changes in summer runoff over the MLYRB under various climate change scenarios are then analyzed with direct runoff outputs from 28 general circulation models participating in the sixth phase of the Coupled Model Intercomparison Project. Given that the equal-weighted multi-model ensemble mean could not well represent the historical runoff changes in the MLYRB, in this paper we introduce a model weighting scheme that considers both the model skill and independence. It turns out that this scheme well constrains the models to represent the observed decadal changes of summer runoff. The weighted mean projections suggest that the summer runoff in the MLYRB during 2015–2100 under all warming scenarios will be higher than the present day; and 2021–2040 is likely to be a period with significantly increased summer runoff. Results of the present study have great implications for flood control and effective water resources management over the MLYRB in the future, and the weighting approach used in this paper can be applied to a wide range of projections at both regional and global scales.publishedVersio
Optimization of cyclosporin A production by Beauveria nivea in continuous fed-batch fermentation
To develop the effective control method for fed-batch culture of cyclosporin A production, we chose fructose, L-valine and (NH4)2HPO4 as feeding nutrients and compared their productivities in relation to different concentrations. The feeding rate of three kinds of feeding materials was controlled to maintain the suitable residual concentration. The fed-batch fermentation results indicated that the optimal concentrations of fructose, L-valine and (NH4)2HPO4 were about 20 g/L, 0.5 g/L and 0.6 g/L for cyclosporin A production, respectively. The cultivation of Beauveria nivea could produce cyclosporin A up to 6.2 g/L for 240 hrs through a continuous feeding-rate-controlled-batch process under the optimal feeding conditions
Ginsenosides are novel naturally-occurring aryl hydrocarbon receptor ligands.
The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor that mediates many of the biological and toxicological actions of structurally diverse chemicals. In this study, we examined the ability of a series of ginsenosides extracted from ginseng, a traditional Chinese medicine, to bind to and activate/inhibit the AHR and AHR signal transduction. Utilizing a combination of ligand and DNA binding assays, molecular docking and reporter gene analysis, we demonstrated the ability of selected ginsenosides to directly bind to and activate the guinea pig cytosolic AHR, and to stimulate/inhibit AHR-dependent luciferase gene expression in a recombinant guinea pig cell line. Comparative studies revealed significant species differences in the ability of ginsenosides to stimulate AHR-dependent gene expression in guinea pig, rat, mouse and human cell lines. Not only did selected ginsenosides preferentially activate the AHR from one species and not others, mouse cell line was also significantly less responsive to these chemicals than rat and guinea pig cell lines, but the endogenous gene CYP1A1 could still be inducted in mouse cell line. Overall, the ability of these compounds to stimulate AHR signal transduction demonstrated that these ginsenosides are a new class of naturally occurring AHR agonists
Theoretical and Experimental Research on The Optimal Displacement Ratio of Rotary Two-Stage Inverter Compressor With Vapor Injection
Displacement ratio is one of the most important parameters of designing rotary two-stage inverter compressor with vapor injection, which decides the COP (Coefficient of Performance) of the compressor. The optimal displacement ratio can bring about the highest COP. The mathematical model of the optimal displacement ratio of rotary two-stage inverter compressor with vapor injection has been developed and verified with the test data. It can be seen from theoretical and experimental research that the optimal displacement ratio of compressors in different working conditions can be obtained accurately by the mathematical model introduced in this paper
Evaluation of TGF-β1 and MCP-1 expression and tubulointerstitial fibrosis in children with Henoch-Schönlein purpura nephritis and IgA nephropathy: A clinical correlation
OBJECTIVES: Henoch-Schönlein purpura nephritis and immunoglobulin A nephropathy are two diseases with similar clinical presentations but very different prognoses. Transforming growth factor β1 and monocyte chemoattractant protein-1 have been associated with the development of tissue fibrosis. We examined the development of tubulointerstitial fibrosis and its relationship with Transforming growth factor β1 and monocyte chemoattractant protein-1 expression in these patients. METHODS: Renal tissue samples were collected by renal biopsy from 50 children with Henoch-Schönlein purpura nephritis and 50 children with immunoglobulin A nephropathy. Hematoxylin and eosin and Masson's trichrome-stained tissues were examined using light microscopy. Tubulointerstitial fibrosis was graded using the method described by Bohle et al. (1). The immunohistochemical detection of Transforming growth factor β1 and monocyte chemoattractant protein-1 expression was correlated with the tubulointerstitial fibrosis grade. Clinical Trial registration number: ZJCH-2012-0105. RESULTS: Transforming growth factor β1 and monocyte chemoattractant protein-1 expression in the renal tissues was significantly greater in the patients with immunoglobulin A nephropathy than in the patients with Henoch-Schönlein purpura nephritis (both
Numerical Analysis and Optimization for Hydrodynamic Lubrication in Journal Bearings of Rotary Compressor
Based on the average Reynolds’ equation of hydrodynamic lubrication, the axis locus and the minimum oil film thickness of the journal bearings under the dynamic load were numerically solved in this paper, and the movement and bearing characteristics of the compressor bearings at different rotation speeds were analyzed to evaluate the influence of the friction loss of the journal bearings on the performance of the rotary compressor. The simulation results indicated that the minimum oil film thickness of the sub bearing is smaller than the critical oil film thickness at low rotation speed (n ≤ 1800 rpm), therefore, the friction power increases significantly with the decrease of rotation speed. The effects of width-diameter ratio, clearance and viscosity of lubricating oil on the improvement of minimum oil film thickness were further analyzed. By optimizing the width-diameter ratio of the bearing, the load carrying capacity of the oil film is improved, and the friction power of sub bearing reduces by more than 80%. The experimental results showed that the performance of rotary compressor can be improved by more than 1% at low rotation speed
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