•Strong hydrodynamic force promoted sediment deposition in the trap.•Lake currents and waves’ action time on the sediment capture was different.•The effect of hydrodynamics on sediment capture in the ...trap was quantified.
Hydrodynamics are the key factor influencing sediment resuspension, transport and nutrient release in large shallow lakes. However, the hydrodynamic responses of bottom traps during pollutant capture remain unclear. In this study, a large eutrophic shallow lake was selected to carry out a field test of deep traps at the lake bottom. Based on observations of the lake current around the trap, the sedimentation rate of the particles in the trap and the nutrient content of the captured sediments, combined with the numerical simulation of the waves outside the trap, the effects of lake currents and waves on the sediment deposition in the traps were studied, and the response of the nutrient content of the sediments captured in the deep traps to the changes in lake currents and waves was analyzed. The results showed that the strong hydrodynamic force significantly promoted sediment deposition in the trap and enhanced the ability of the trap to capture sediments with high nutrient contents. The influences of waves and lake currents on the bottom trap capture of polluted sediments varied among different periods. Waves played the leading role in winter and spring, accelerating sediment capture in the bottom traps near the southern shore of eastern Lake Chaohu during this period. In summer, the lake current was the main dynamic factor contributing to the rapid deposition of particulate matter and the capture of sediments with high nutrient contents in the bottom traps of western Lake Chaohu. The multiple stepwise linear regression model based on lake current and wave data explained 37.6 % of the sediment deposition in the trap, and the model built for a single bottom trap explained more than 80 % of the deposition. After correcting the sediment deposition thickness in the trap by considering the water content of the sediment, the quantitative relation yield better inversion results for the sediment deposition process, and different thicknesses in the bottom trap were linked to different sediment deposition periods. According to the hydrodynamic strength in 2020, the thickness of the highly contaminated sediments captured by traps CC1-CC5 was calculated to be 1.09–1.93 m, and the corresponding TN and TP were 26.66–68.53 kg and 6.84–19.89 kg, respectively. This study provides a scientific analysis and guidance for the evaluation of endogenous nutrients captured by lake bottom trap methods.
With the rising aging population in China, increasing attention has been paid to the spatial layouts of medical and residential care facilities; however, the accessibility and aging suitability of ...these facilities have received less attention. Taking Guangdong province as an example, this study used the improved two-step floating catchment area method to measure the accessibility of medical and residential care facilities and summarized their spatial pattern characteristics from four dimensions (1 km, four regions, cities, and counties). A correlation was established between the elderly population density data and their degrees using the autocorrelation analysis method and the Gini coefficient to analyze the aging suitability and equality of medical and residential care facilities. Finally, the Spearman correlation coefficient was used to analyze the factors influencing the accessibility and equality from three aspects, namely: the natural environment, society, and economy. The following results were obtained
This investigation addressed the influence of severe plastic deformation (SPD) on dynamic strain aging (DSA) of ultrafine grained (UFG) Al–Mg alloys with different Mg content. Confined channel die ...pressing (CCDP) carried out at room temperature was used for SPD. Microcharacterization by TEM revealed a remarkable grain refinement and retarded dynamic recovery with increasing Mg content and plastic strain during SPD. Mechanical tests with jumping and constant strain rates demonstrated a complicated deformation behaviors of the UFG Al–Mg alloys: (i) the critical strain εc for initiation of serrated flow increased considerably with increasing strain and Mg content contrary to the behavior of the coarse grained and non-deformed counterparts; (ii) the instantaneous stress response (Δσi) and the instantaneous strain rate sensitivity (mi) during rate jumps were always positive and increased monotonically with CCDP pass and Mg content, however, they exhibited a distinctive asymmetry with respect to the strain rate jump direction, i.e. the values for strain rate towards down were about one order of magnitude larger than those for rate towards up and increased with progressing CCDP as well as with increasing Mg content; (iii) the steady state strain rate sensitivity ms was negative and decreased firstly with progressing CCDP up to a certain strain and then increased again. This mechanical behavior of UFG Al–Mg alloys is discussed on the basis of recently developed DSA models by relating the microstructure evolution of Al–Mg alloys during SPD to the influence of SPD on DSA.
At the beginning of 2020, to stop the spread of the coronavirus disease (COVID-19) to the campus, the Ministry of Education of China launched a policy "Suspension of classes without suspending ...schooling" for the spring semester of 2020. However, the drawbacks of online teaching (e.g., students' inadequate autonomous learning, the lack of effective online instruction) forced us to modify teaching strategies during this special period, especially developing courses that are suitable for student learning at home and improving their key competencies. In order to solve these problems, this study introduces some theoretical exploration and practical work of curriculum design under the guidance of thinking-based instruction theory (TBIT) during the pandemic. We firstly introduce TBIT, and elaborate on the curriculum design under the TBIT theoretical frame. Then we describe a series of TBIT-based micro-courses with the pandemic as background. A descriptive study is reported to illustrate the effects of three micro-courses. Results showed that, compared to national curricula, the TBIT-based micro-courses not only improved the course quality but also enhanced students' motivation and facilitated their online learning behavior (such as interactive communication) for the online courses. The current study has important implications for how to design effective and interesting online courses suitable under pandemic and capable of improving students' thinking abilities and key competencies.
•Proposed spectral indices for identifying aquatic vegetation types in Taihu Lake, China.•Knowing phenology of aquatic vegetation following hyper-temporal remote sensing data.•Using images from ...satellite of China (HJ 1A/1B-CCD) for tracking vegetated phenology.•Analyzing effect of temperature on growth for different types of aquatic vegetation.
Knowledge of the composition and areal distribution of aquatic vegetation types, as well as their seasonal and interannual variations, is crucial for managing and maintaining the balance of lake ecosystems. In this study, a series of remotely sensed images with a resolution of 30m (HJ-CCD and Landsat TM) were collected and used to map the distribution of aquatic vegetation types in Taihu Lake, China. Seasonal and interannual dynamics of aquatic vegetation types were explored and analyzed. The distribution areas of Type I (emergent, floating-leaved and floating vegetation) and Type II (submerged vegetation) were used to model their growing season phenology by double logistic functions. The resulting double logistic models showed, the area of Type I reached its peak in mid-August, and the maximum area for Type II occurred in mid-September. From 1984 to 2013, Type I area increased continuously from 59.75km2 to 148.00km2 (R2=0.84), whereas the area covered by Type II first increased and then decreased, with a trend conforming to a significant quadratic curve (R2=0.83). The eutrophication and stable state of Taihu Lake was assessed using a simple indicator which was expressed as a ratio of Type II area to Type I area. The results showed that the eutrophication in the lake might have been increasing in the area studied since 2000. Additionally, the results showed that air temperature had likely a direct effect on the growth of Type I (R2=0.66) and a significant, but delayed, effect on the growth of Type II.
To improve lake water quality, two experimental water transfers were conducted in winter–spring 2002 and summer–fall 2003 in Lake Taihu, a large shallow lake in China. Both observed data and ...estimated nutrient concentration with the elimination of effect from natural factors were used in this research to assess the spatial and temporal variations of water quality improvement induced by the two transfers. Clear improvement of water quality associated with deduction of TN, TP, and chlorophyll a (Chl-a) concentration was observed in many areas of the lake during the two water transfers. The over all reduction in TP concentration was notable in Southwest Zone, Centre Zone, and Dongtaihu Bay during the 2002 transfer, and was more pronounced in Meiliang Bay and Southwest Zone during the 2003 transfer period. However, the reduction in TN and Chl-a concentration was relatively weak. Results indicate a less impressive improvement of water quality from water transfer in large lakes than in small ones as the effectiveness of water transfer in large lakes is generally limited by large size, complex boundaries, and the difficulty of finding proper water source to be transferred. The comparison of observed and estimated water transfer effectiveness suggests a greater improvement of water quality derived from water transfer than appeared from the observation.
Little is known about the distribution and risk levels of nutrients and organic matter (OM) in the surface sediment of shallow submerged macrophyte-dominated lakes. In the current study, sixty ...surface sediment samples were collected from Xukou Bay, a typical submerged macrophyte-dominated zone in Lake Taihu, China. A 60-day degradation experiment of Potamogeton malaianus, a dominant species in the bay, was done in the laboratory. The results demonstrated that the ranges of total nitrogen (TN) and total phosphorus (TP), alkali-hydrolyzable nitrogen (AN), available phosphorus (AP), and OM in the surface sediment of the bay were 262.2–2,979.6 mg/kg, 41.2–728.7 mg/kg, 8.6–150.0 mg/kg, 4.4–36.4 mg/kg, and 3.7–50.2 g/kg, respectively. The spatial distributions of TN, OM, and AN concentrations showed similar trends: The highest concentrations were present in the northeastern and southwestern zones, while the TP and AP concentrations were high in the northeastern, central, and southwestern zones. The heterogeneity in the spatial distribution of nutrients and OM in the surface sediment of the bay was associated with aquatic vegetation and anthropogenic activities. The comprehensive risk index and organic nitrogen index revealed that the surface sediment was moderately, interactively contaminated by TN and TP and by organic nitrogen. TN and OM in the northeastern zone were mainly derived from endogenous residues due to the decomposition of aquatic plants, while TN in the southwestern zone was primarily derived from agricultural wastewater. Consequently, targeted measures should be implemented to reduce TN and OM in the surface sediment of macrophyte-dominated lakes.
In this work, a high-manganese Fe–23Mn–1.5Al–0.3C Twinning-Induced Plasticity (TWIP) steel was subjected to plastic shear deformation using Equal-Channel Angular Pressing (ECAP) at 300 °C following ...route BC and additional annealing. The microstructure evolution during both deformation by ECAP and subsequent annealing was investigated and correlated with the mechanical properties. The successive grain refinement during ECAP was promoted by two parallel mechanisms, namely dislocation driven grain fragmentation and twin fragmentation, and accounted for the ultra-high strength. In addition, due to the relatively low volume fraction of deformation twins after ECAP at 300 °C, further contribution of deformation twinning during room temperature deformation allowed additional work-hardening capacity and elongation. During subsequent recovery annealing the ultra-fine grains and deformation twins were thermally stable, which supported retainment of the high yield strength along with regained uniform elongation. For the first time, the texture evolution during ECAP and during the following heat treatment was analyzed. After 1, 2, and 4 ECAP passes a transition texture with the characteristic texture components of both high- and low-SFE materials developed. During the following heat treatment the texture evolution proceeded similar to that observed in the same material after cold rolling. Retaining of the ECAP texture components due to oriented nucleation at grain boundaries and triple junctions as well as annealing twinning accounted for the formation of a weak, retained ECAP texture after recrystallization.
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Chronic obstructive pulmonary disease (COPD) is a significant public health problem characterized by persistent airflow limitation. Despite previous research into the pathogenesis of COPD, a ...comprehensive understanding of the cell-type-specific mechanisms in COPD remains lacking. Recent studies have implicated Rab GTPases in regulating chronic immune response and inflammation via multiple pathways. In this study, the molecular regulating mechanism of RAB32 in COPD was investigated by multiple bioinformatics mining and experimental verification.
We collected lung tissue surgical specimens from Zhongshan Hospital, Fudan University, and RT-qPCR and western blotting were used to detect the expression of Rabs in COPD lung tissues. Four COPD microarray datasets from the Gene Expression Omnibus (GEO) were analyzed. COPD-related epithelial cell scRNA-seq data was obtained from the GSE173896 dataset. Weighted gene co-expression network analysis (WGCNA), mfuzz cluster, and Spearman correlation analysis were combined to obtain the regulatory network of RAB32 in COPD. The slingshot algorithm was used to identify the regulatory molecule, and the co-localization of RAB32 and GPRC5A was observed with immunofluorescence.
WGCNA identified 771 key module genes significantly associated with the occurrence of COPD, including five Rab genes. RAB32 was up-regulated in lung tissues from subjects with COPD as contrast to those without COPD on both mRNA and protein levels. Integrating the results of WGCNA, Mfuzz clusters, and Spearman analysis, nine potential interacting genes with RAB32 were identified. Among these genes, GPRC5A exhibited a similar molecular expression pattern to RAB32. Co-expression density analysis at the cell level demonstrated that the co-expression density of RAB32 and GPRC5A was higher in type I alveolar epithelial cells (AT1s) than in type II alveolar epithelial cells (AT2s). The immunofluorescence also confirmed the co-localization of RAB32 and GPRC5A, and the Pearson correlation analysis found the relationship between RAB32 and GPRC5A was significantly stronger in the COPD lungs (r = 0.65) compared to the non-COPD lungs (r = 0.33).
Our study marked endeavor to delineate the molecular regulatory axis of RAB32 in COPD by employing diverse methods and identifying GPRC5A as a potential interacting molecule with RAB32. These findings offered novel perspectives on the mechanism of COPD.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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