Rapid population increase and economic growth in eastern China has lead
to the degradation of many water bodies in the region, such as Lake
Taihu, the third largest freshwater lake in China. Using ...data from
recent investigations, the correlations between algae (measured as
chlorophyll-a) and water quality indices in Lake Taihu were described
by multivariate statistical analyses, and the key driving factors for
the lake eutrophication were identified by principal component
analysis. Results revealed strong spatiotemporal variation in the
correlations between algae and water quality indices, suggesting that
the limiting factor for the dominant algae growth depends on
seasonality and location and it is necessary to reduce both nitrogen
and phosphorus inputs for a long-term eutrophication control in this
hyper-eutrophic system. Water temperature was another important
controlling factor for algal growth in the lake. Using principal
component analysis, nutrient contaminations from anthropogenic and
natural inputs were identified as the key driving factor for the water
quality problems of the lake. Moreover, five principal components were
extracted and characterized with high spatial and seasonal variations
in Lake Taihu. The key driving factors were believed to influence
spatial variations including heavily polluted areas located in the
northern and northwestern parts of the lake, where many manufacturing
factories were built and wastewater from domestic and industrial plants
was discharged. Based on this analysis, attention should be paid to
effective land management, industrial wastewater treatment, and
macrophytic vegetation restoration to reduce the pollutant loads and
improve water quality. Principal component analysis was found to be a
useful and effective method to reduce the number of analytical
parameters without notably impairing the quality of information in this
study.
AlCrMoNbZr/(AlCrMoNbZr)N multilayer coatings with equal individual layer thicknesses varying from 5 to 50 nm were deposited by using magnetron co-sputtering technology on N36 substrates ...(Zr1Sn1Nb-0.3Fe (wt.%)), to enhance the corrosion resistance of zirconium alloys in the event of a loss-of-coolant accident (LOCA). Comprehensive characterization by using X-ray diffraction and transmission electron microscopy revealed a multilayer structure consisting of a face-centred cubic (FCC) (AlCrMoNbZr)N layer and an amorphous AlCrMoNbZr layer. The structure and properties of the AlCrMoNbZr/(AlCrMoNbZr)N multilayer coatings with different individual layer thicknesses were studied, and the structure of all multilayer coatings contained coexisting amorphous and FCC phases. In addition, the multilayer coatings exhibited good interfacial bonding strength and good hydrophobicity. Corrosion tests were performed in static pure water at a temperature of 360 °C and a pressure of 18.7 MPa for 30 days. The results showed that the AlCrMoNbZr 50 nm/(AlCrMoNbZr)N 50 nm multilayer coating had superior anti-corrosion properties (4.4 mg/dm2 weight gain) to those of the AlCrMoNbZr 5 nm/(AlCrMoNbZr)N 5 nm and AlCrMoNbZr 10 nm/(AlCrMoNbZr)N 10 nm multilayer coatings. The AlCrMoNbZr/(AlCrMoNbZr)N multilayer structures inhibited Al migration and suppressed boehmite phase formation more effectively than single-layer AlCrMoNbZr or (AlCrMoNbZr)N.
•AlCrMoNbZr/(AlCrMoNbZr) multilayer coatings used for accident-tolerant fuel were prepared.•The microstructure and properties of the AlCrMoNbZr/(AlCrMoNbZr) multilayer coatings were systematically investigated.•The 50/50 nm AlCrMoNbZr/(AlCrMoNbZr) multilayer coating exhibits superior corrosion resistance.
The excellent electroluminescent (EL) properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles, 1-methyl-1,2,3,4,5-pentaphenylsilole (MPPS), and 1,1,2,3,4,5-hexaphenylsilole (HPS) have been found. ...Despite some studies devoted to these materials, very little is known about the real origin of their unique EL properties. Therefore, we investigated the structures, photoluminescence (PL), and charge carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles as well as the effect of substituents on these characteristics. The single crystals of the three siloles involving 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS), MPPS, and HPS were grown and their crystal structures were determined by X-ray diffraction. Three siloles have nonplanar molecular structures. The substituents at 1,1-positions enhance the steric hindrance and have predominant influence on the twisted degree of phenyl groups at ring carbons. This nonplanar structure reduces the intermolecular interaction and the likelihood of excimer formation, and increases PL efficiency in the solid state. The silole films show high fluorescence quantum yields (75−85%), whereas their dilute solutions exhibit a faint emission. The electronic structures of the three siloles were investigated using quantum chemical calculations. The highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) are mainly localized on the silole ring and two phenyl groups at 2,5-positions in all cases, while the LUMOs have a significant orbital density at two exocyclic Si−C bonds. The extremely theoretical studies of luminescent properties were carried out. We calculated the nonradiative decay rate of the first excited state as well as the radiative one. It is found that the faint emission of DMTPS in solutions mainly results from the huge nonradiative decay rate. In solid states, molecular packing can remarkably restrict the intramolecular rotation of the peripheral side phenyl ring, which has a large contribution to the nonradiative transition process. This explains why the 1,1-disubstituted 2,3,4,5-tetraphenylsiloles in the thin films exhibit high fluorescence quantum yields. The charge carrier mobilities of the MPPS and HPS films were measured using a transient EL technique. We obtained a mobility of 2.1 × 10-6 cm2/V·s in the MPPS film at an electric field of 1.2 × 106 V/cm. This mobility is comparable to that of Alq3, which is one of the most extensively used electron transport materials in organic light-emitting diodes (LEDs), at the same electric field. The electron mobility of the HPS film is about ∼1.5 times higher than that of the MPPS film. To the best of our knowledge, this kind of material is one of the most excellent emissive materials that possess both high charge carrier mobility and high PL efficiency in the solid states simultaneously. The excellent EL performances of MPPS and HPS are presumably ascribed to these characteristics.
•New Rotatable Hopkinson Bar is used for dynamic shear-compression on corrugated sandwich panel.•Three deformation modes of corrugations are identified for different loading conditions.•Loading rate ...effect under various combined loading is examined and attributed to inertia effect.
This paper studies the quasi-static and dynamic mechanical behaviors of a commercial corrugated sandwich panel under combined shear-compressive loading by using a modified MTS machine and the so-called Rotatable Hopkinson Bar (RHB) loading system. Particular focus is placed on identifying the differences of large deformation behaviors of corrugation panels between uniaxial compression and combined shear-compression, especially the influences of shear-compressive loading angle and loading rate on the stress-displacement curves and the deformation modes. It is found that the normal stress decreases with the loading angle, while the shear stress increases with it for both the quasi-static and dynamic loadings. Three deformation patterns are identified for five different loading angles from 0o (corresponding to uniaxial compression) to 50o. A positive loading rate effect is found for the initial collapse of corrugated panels, which is contributed to the inertia effect within corrugation buckling. The strength of the panels after initial collapse shows a negative loading rate effect, which may be due to the strain softening behavior of base material (5754-H48 Aluminum alloy) at impact loading.
This article studies the influence of the nonlocal scale parameter on the deflection of a nonlocal nanobeam and crack growth. Using the Timoshenko hypothesis, a single governing equation is derived ...and its exact solution can be determined through appropriate end‐support conditions. Numerical calculations are carried out for a cantilever microtubule in solution at a given flow speed. The effects of nonlocal scale parameter on the deflection are discussed. Based on the obtained solutions, the double cantilever beam model is utilized to determine energy release rate near a crack tip for an edge crack and a central crack, respectively. It is found that the scale parameter plays different roles in determining stress intensity factors and energy release rates, depending on crack constraints. When neglecting shear deformation, the results for nonlocal Euler‐Bernoulli beams can be directly obtained.
This article studies the influence of the nonlocal scale parameter on the deflection of a nonlocal nanobeam and crack growth. Using the Timoshenko hypothesis, a single governing equation is derived and its exact solution can be determined through appropriate end‐support conditions. Numerical calculations are carried out for a cantilevermicrotubule in solution at a given flow speed. The effects of nonlocal scale parameter on the deflection are discussed.
Gd-based amorphous alloys with excellent glass forming ability (GFA) exhibit outstanding magnetocaloric effect (MCE) at low temperature, but their GFA and MCE decrease dramatically with the ...increasing Curie temperature (Tc). In order to develop MCE materials suitable for room temperature refrigeration, it is urgent to further explore Gd-based amorphous alloys with enhanced MCE at or above room temperature. In this work, Tc of the Gd50Co50 amorphous alloy was successfully improved to room temperature by 2% (at. %) Fe substitution for Gd, accompanied with the enhanced GFA of the binary amorphous alloy. The maximum adiabatic temperature change of the Gd48Co50Fe2 amorphous alloy is at least 65% higher than those of the other metallic glasses at temperatures higher than 290 K. The results indicate that the Gd48Co50Fe2 amorphous alloy is a better candidate for magnetic refrigerant at room temperature.
•The GFA of the Gd50Co50 amorphous alloy was obviously improved by 2% (at. %) Fe substitution for Gd.•Tc of the Gd50Co50 amorphous alloy was successfully improved to room temperature by 2% (at. %) Fe substitution for Gd.•The maximum ΔTad of the Gd48Co50Fe2 ribbon is almost the highest in amorphous alloys at or above room temperatures.
Osteoarthritis (OA) is a prevalent joint disorder worldwide. Recent studies suggested that macrophages play an important role in the progression of OA. However, the detailed pathology related to ...macrophages is still ambiguous, especially where related to mechanotransduction. In this study, polycaprolactone (PCL) and Eucommia Ulmoides Gum (EUG) composite scaffolds were first fabricated by electrospinning. The stiffness of as-fabricated scaffolds was altered by adjusting the PCL-to-EUG ratio. The mechanical properties, structural characteristics and chemical composition of the scaffolds were investigated using various materials characterization techniques. The results show that stiffness of the scaffolds was in the same range as that of cartilage tissues with OA. Confocal microscopy and reverse transcription-polymerase chain reaction (RT-PCR) were performed to investigate the macrophages cultured on the scaffolds. Significant morphological changes of cells were observed on PCL/EUG scaffolds with different stiffness. The expression of inflammatory and fibrosis-related cytokines increases as scaffold stiffness decreases, similar to the trend observed in OA progression.
Fretting wear tests of Inconel 690 alloy have been carried out at various temperatures (room temperature – RT, 90°C, 200°C and 285°C) for tube/plate contact configuration. The worn surfaces and ...cross-sectional morphologies were observed through scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and electron probe microanalysis (EPMA). Moreover, a particular debris cleaning method was used to remove wear particles of worn Inconel 690 alloy effectively in order to estimate exact wear volume. Overall, the results indicated that temperature had a great impact on fretting wear behavior and wear mechanisms. With increase in temperature, the principal wear mechanisms changed from delamination wear to the combination of delamination and adhesive wear, as demonstrated by the presence of an adhesive transfer layer at 285°C, instead of a compacted debris bed at 90°C. The adhesive transfer layer seemed to protect the surfaces better due to a reduction in the interaction of the worn surfaces. Finally, higher friction coefficient and wear volume appeared at lower temperature (RT to 90°C), compared to that associated with higher temperature (200°C and 285°C).
•A chemistry cleaning method was used to remove the wear particles.•A model was proposed to describe wear mechanisms and temperature.•Adhesive wear played a significant role in wear above 200°C.
In this study, binary Dy-Co ribbons were synthesized by a conventional melt-spinning approach and glassy ribbons were successfully obtained within the compositional range Dy50Co50 to Dy68Co32. The ...glass formability and magnetic properties of these amorphous alloys were examined. The compositional dependence of glass formability, Curie temperature and magneto-caloric response of the DyxCo100-x (x=50, 55, 60, 65 and 68) amorphous alloys, as well as the mechanism involved, were determined.
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