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In recent years, there has been growing concern that vegetation changes on the Tibetan Plateau are associated with climate change (temperature and precipitation) and human activities. This study used six types of remote sensing vegetation data, including GIMMS (Global Inventory Modelling and Mapping Studies) NDVI (Normalized Difference Vegetation Index), MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI, MODIS EVI (Enhanced Vegetation Index), SPOT Vegetation (Spot-VGT) NDVI, LAI (Leaf Area Index) and NPP (Net Primary Productivity), and applied the maximum synthesis method, trend analysis, correlation analysis, and multivariate statistical analysis to investigate vegetation change processes since the 1980s. The study showed that the amount of vegetation on the TP had increased significantly since 2000 (p <.01), especially in the northeastern part of the TP. There was no significant change prior to 2000. The different vegetation data sources varied greatly. Four remote sensing indices, MODIS EVI, Spot-VGT NDVI, LAI, and NPP, showed a significant increase in vegetation from 2000, accounting for 16.18%, 44.55%, 30.44% and 8.94% of the total area, respectively (p <.05). Multiple data sources provided a more comprehensive understanding, whereas a single data source had substantial uncertainty. Human activities, such as the implementation of large-scale ecological projects, played a dominant role in increasing vegetation, while climate change played a subsidiary role. The MODIS EVI, Spot-VGT NDVI, LAI, and NPP data showed that the area of increased vegetation caused by human activities accounted for 53.51%, 45.68%, 37.52%, and 31.79% of the total area of the TP, respectively. The relative increase from climate change was 10.28%, 17.49%, 13.15%, and 8.82%, respectively. The current study applied multi-source remotely sensed vegetation data, which effectively reduced the uncertainty caused by individual data sources and provided more rigorous and scientific research conclusions. [ABSTRACT FROM AUTHOR]

Sandwich composites are widely used in aviation, aerospace and marine engineering fields because of their excellent comprehensive properties. However, it is difficult to accurately predict the ultimate performance of sandwich composite structures because of their complex failure modes and uncoordinated damage processes. In this paper, the ultimate load, progressive failure process and failure mode of sandwich composite T-joints under three-point bending and lateral bending loads are predicted and verified by using an improved progressive damage analysis program. Moreover, the bio-inspired optimization of the composite T-joint is carried out, and the corner shape and material combination of the T-joint are designed and optimized based on the contour of the flange bone of the bird. The main factors affecting the bearing capacity of T-joint are further discussed, and a reasonable and feasible bio-inspired optimization scheme is obtained, which provides some reference for the design of marine composite T-joint. [ABSTRACT FROM AUTHOR]

The eco-system in the Qinghai-Tibet Plateau (QTP) is extremely fragile, and highly vulnerable to climate change. Knowledge of the changes in the ecological conditions is vital to mitigate the impact of climate change. In this study, we investigated the trend of ecological conditions of the QTP using the remotely sensed ecological index (RSEI), which is the first PCA (principal component analysis) axis of the four indexes derived from the MODIS (Moderate resolution Imaging Spectroradiometer) images captured in the growing season of 2000–2020. The four indexes, i.e., NDVI (normalized difference vegetation index), heat (land surface temperature, LST), wetness (tasseled cap wetness index, WET) and dryness (normalized difference impervious surface index, NDBSI), were calculated on the Google Earth Engine platform. Using land use cover change (LUCC) data, long-term meteorological records and the supplementary annual livestock production, we explored the drivers of spatiotemporal changes in the RSEI. The results show the following points: (1) the ecological conditions of the QTP have remarkable spatiotemporal variations. There were two ecological degradation periods, one of them occurred in the central region during 2005–2010, mainly attributed to the rising temperatures and decreasing precipitation. The other occurred during 2015–2020, driven primarily by overgrazing in the southwest. From 2000 to 2005, it was a period of rapid ecological restoration in the ecologically fragile northeast region. (2) The contribution rate of pc1 was stable at 60%, while the contribution rate of pc2 remained below 40%, indicating that pc1 demonstrated most of the characteristics of the four indexes. The correlation coefficients between NDVI and WET with pc1 are both positive, while LST and NDBSI have negative correlation coefficients, i.e., negative effects. This is consistent with the actual situation. (3) Overgrazing caused grass degradation in the southwest area of the QTP, which might be the main reason for the poor ecological conditions (i.e., low RSEI value) during 2015–2020. (4) Temperature and precipitation showed an increasing trend during the study period. A warmer and wetter climate is expected to have profound impacts on the ecosystems in QTP and practices should be concentrated on identifying climate-sensitive ecosystem components and designating adaptative options. [ABSTRACT FROM AUTHOR]

Background: An important aspect of studying evolution is to understand how new species are formed and their uniqueness is maintained. Hybridization can lead to the formation of new species through reorganization of the adaptive system and significant changes in phenotype. Interestingly, eight stable strains of 2nNCRC derived from interspecies hybridization have been established in our laboratory. To examine the phylogeographical pattern of the widely distributed genus Carassius across Eurasia and investigate the possible homoploid hybrid origin of the Carassius auratus complex lineage in light of past climatic events, the mitochondrial genome (mtDNA) and one nuclear DNA were used to reconstruct the phylogenetic relationship between the C. auratus complex and 2nNCRC and to assess how demographic history, dispersal and barriers to gene flow have led to the current distribution of the C. auratus complex. Results: As expected, 2nNCRC had a very close relationship with the C. auratus complex and similar morphological characteristics to those of the C. auratus complex, which is genetically distinct from the other three species of Carassius. The estimation of divergence time and ancestral state demonstrated that the C. auratus complex possibly originated from the Yangtze River basin in China. There were seven sublineages of the C. auratus complex across Eurasia and at least four mtDNA lineages endemic to particular geographical regions in China. The primary colonization route from China to Mongolia and the Far East (Russia) occurred during the Late Pliocene, and the diversification of other sublineages of the C. auratus complex specifically coincided with the interglacial stage during the Early and Mid-Pleistocene in China. Conclusion: Our results support the origin of the C. auratus complex in China, and its wide distribution across Eurasia was mainly due to natural Pleistocene dispersal and recent anthropogenic translocation. The sympatric distribution of the ancestral area for both parents of 2nNCRC and the C. auratus complex, as well as the significant changes in the structure of pharyngeal teeth and morphological characteristics between 2nNCRC and its parents, imply that homoploid hybrid speciation (HHS) for C. auratus could likely have occurred in nature. The diversification pattern indicated an independent evolutionary history of the C. auratus complex, which was not separated from the most recent common ancestor of C. carassius or C. cuvieri. Considering that the paleoclimate oscillation and the development of an eastward-flowing drainage system during the Pliocene and Pleistocene in China provided an opportunity for hybridization between divergent lineages, the formation of 2nNCRC in our laboratory could be a good candidate for explaining the HHS of C. auratus in nature. [ABSTRACT FROM AUTHOR]

Reducing carbon emissions and increasing carbon sinks are key strategies to effectively remove greenhouse gases from the atmosphere. Assessing the current carbon emission status and predicting future carbon emission scenarios could help formulate effective regional carbon emission reduction targets. However, it is necessary to enhance the carbon sink capacity of terrestrial ecosystems and improve forest management methods to promote greenhouse gas absorption. In this study, the spatiotemporal characteristics and dynamic evolution of fossil fuel CO 2 (FFCO 2) emissions in China from 2000 to 2019 were analyzed using the standard deviation ellipse, kernel density of emissions, and Theil index. A backpropagation (BP) neural network optimized with a genetic algorithm (GA) was used to predict FFCO 2 emission during 2020–2030. The biomass increment methodology was used to predict the potential carbon sinks generated by Chinese Certified Emission Reduction (CCER) carbon-sink forestry projects during 2020–2030. The results showed that China's FFCO 2 emissions exhibited a gradual increasing trend during 2000–2019, with an average annual growth rate of 6.29%. China's FFCO 2 emissions show a greater distribution on the southeastern coast than in the northwestern interior. The GA-BP prediction shows that China's FFCO 2 emissions will continue to fluctuate and increase between 2020 and 2030. The potential of carbon sinks will be 0.69 × 108 Mg C generated by the CCER carbon-sink forestry projects during 2020–2030, which could offset 0.56% of FFCO 2 emissions. In the future, imbalances in regional development should be considered when formulating carbon-reduction strategies. Moreover, using carbon-sink of forestry projects of CCER to balance economic development including poverty eradication and environmental conservation should be considered. Specifically, establishing a methodology of projects for the management of natural forests' carbon-sink will be an important future strategy. • China's FFCO 2 emissions rose in volatility with an average growth rate of 6.29%. • The spatial differences of FFCO 2 emissions are gradually narrowing. • FFCO 2 emissions will continue to rise in the future. • Carbon-sink forestry project is ideal approach to offset carbon emission. • The Methodology of Forests Management for natural forest should be focused. [ABSTRACT FROM AUTHOR]

Based on the wear analysis of a propeller hub bearing, wear tests are designed under different marine environments to illustrate wear failure mechanisms. The results reveal that the wear failure characteristics of the propeller hub bearing are primarily abrasive wear, accompanied by adhesion and oxidation wears, and plastic deformation. These results agree well with the wear morphologies of the torsional fretting wear tests under starvation lubrication. The wear tests confirm that the wear failure of the propeller hub bearing is owing to the coexistence of multiple wear mechanisms, which is attributed primarily to the superimposed wear behaviors induced by loading, continuous fretting wear, and starvation lubrication in the local contact areas. Hence, the negative effects of interfacial micro-protrusion adhesion and fracture during oil lubrication are difficult to eliminate. Moreover, The uneven radial loads of the contact surfaces of the propeller hub bearing also exhibit a significant influence on the thickness and formation of the oil film at the friction interface. [Display omitted] • Wear failure mechanisms of bearing coated with NAB alloys had been studied. • The designed wear tests were conducted by a self-assemble tribological platform. • Wear failure morphologies of bearing and wear tests results had been discussed. • Physical model at the different wear stages was established. [ABSTRACT FROM AUTHOR]