•The effect of global warming on soil erosion was quantified.•The suitability of soil erosion models for global scale assessment was evaluated.•Spatial patterns of soil erosion under global warming ...were analyzed comprehensively.•The main climatic forces driving changes in soil erosion were analyzed.
Climate warming has widely variable effects on terrestrial ecosystems, and warming-induced changes in soil erosion could accelerate or slow down future warming. Numerous methods and models have been developed to evaluate soil erosion. However, the quantification of the impact of climate change on soil erosion and selection of the most appropriate soil erosion model for a particular study area remain unclear. With the intensification of climate warming, solutions to these problems are becoming increasingly more important. In this study, we performed a meta-analysis of research on global soil erosion to verify the effects of climate warming on soil erosion. Four databases were searched for relevant peer-reviewed publications from 1980 to 2019 using five keywords. The results showed that soil erosion has increased worldwide, mainly in semiarid areas (p < 0.001). While soil erosion has decreased at high latitudes, it has increased at middle and low latitudes. Different soil erosion models provided significantly different simulation results. Among various models, the Revised Universal Soil Loss Equation and Wind Erosion Equation models showed the highest simulation accuracies for water erosion (p < 0.001) and wind erosion (p < 0.05), respectively. At present, the factors driving soil erosion under climate warming remain highly uncertain. In addition, differences in underlying surfaces and the number of study samples also affect soil erosion assessments. In the future, interactions between climate warming and soil erosion (especially in wind erosion models) should be studied in more detail, and the relationship between the UN Sustainable Development Goals and soil erosion should be further considered.
•A model was built to be suitable for soil conservation (SC) in Central Asia (CA).•For the first time, the SC in four major basins (FMB) in CA was evaluated.•Under global warming scenarios, the SC in ...FMB of CA was quantified.•The contributions of climate and vegetation factors to SC in FMB were analysed.
As a key service for regulating ecosystems, soil conservation (SC) plays a critical role in preventing regional land degradation. However, there are few studies on SC services in Central Asia, and there is a lack of quantitative assessments of long-term time series. Meanwhile, future climate change is also expected to exacerbate the uncertainty in SC assessments in Central Asia. Based on this, we modified the revised universal soil loss equation (RUSLE) model applicable to the Central Asia region through the localizing parameters. This study represents the first comprehensive assessment to investigate the SC in the four major basins (FMB) in Central Asia (Amu Darya Basin, ADB; Syr Darya Basin, SDB; Ili River Basin, IRB; and Tarim River Basin, TRB) in the current period (1996–2015) and in the future (with global warming of 1.5 °C (GW_1.5 °C) and 2.0 °C (GW_2.0 °C)). The results indicate that the current and future SC in Central Asia generally show increasing trends, but these trends slow with increasing temperature. Compared with the current value, the future SC in Central Asia is 4.7% and 7.9% lower under GW_1.5 °C and GW_2.0 °C, respectively. The future SC in the FMB decreases under global warming of 2.0 °C (GW_2.0 °C), with the decreases in the basins exhibiting the following order: TRB (-15.1%) > SDB (-8.6%) > ADB (-4.6%) > IRB (-3.3%). With increasing elevation, the SC in Central Asia increases and then decreases. Moreover, under GW_1.5 °C and GW_2.0 °C, the areas with the most concentrated SC extend from the areas at elevations of 1500–3500 m to areas at higher elevations. Temperature and precipitation had a synergistic effect on SC in Central Asia. Among the FMB, the TRB is most sensitive to climate variability. As the temperature increases by 16.9% and the precipitation increases by 30.0%, the SC in the TRB decreases by 7.0% (20.3 t km−2). The SC in the TRB should be prioritized in the FMB in Central Asia under GW_1.5 °C and GW_2.0 °C. The present study fills the gaps in the study of SC services in Central Asia and improves the simulation and risk assessment of SC in arid regions.
Iron oxide nanoparticles were synthesized on the halloysite nanotube (HNT) to prepare the magnetic sorbent HNT–Fe
3O
4, which was explored the adsorption for three dyes, namely methylene blue (MB), ...neutral red (NR) and methyl orange (MO). HNT–Fe
3O
4 was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. HNT was attached with clusters of Fe
3O
4 nanoparticles, and the HNT component was about 50.5
wt% in HNT–Fe
3O
4. Magnetic properties illustrated that HNT–Fe
3O
4 was superparamagnetic with a saturation magnetization (27.91
emu
g
−1). The magnetic HNT–Fe
3O
4 exhibited better adsorption on MB than NR, while the adsorption of MO was very little. And as the adsorbent, HNT–Fe
3O
4 could be easily separated from the aqueous solution in a magnetic field.
•Quantified the change of soil erosion in Central Asia under global warming.•Effects of natural factors on soil erosion were analyzed.•Population exposure was introduced to evaluate the risk of soil ...erosion.•Wind erosion will decrease and water erosion will increase in Central Asia.
Soil erosion is a threat to the ecological environment and human health. Climate change is closely related to soil erosion, and the ecological environment in Central Asia is sensitive to climate change. However, there is a lack of comprehensive risk assessments of the soil erosion by wind and water in Central Asia under climate change. This study used climate model data to simulate the spatiotemporal variation of wind and water erosion in Central Asia during the current period (1996–2015) and in the future with global warming of 1.5 °C and 2.0 °C (GW1.5 °C and GW2.0 °C, respectively) compared with the pre-industrial levels. The variations of exposure of population to soil erosion in the future were assessed. The results showed that the overall wind erosion in Central Asia is decreasing, but the area in which increasing wind erosion occurs will increase (2.6% under GW1.5 °C, and 8.6% under GW2.0 °C) compared with the current period. Water erosion in Central Asia is increasing, and the area in which increasing water erosion occurs will increase by 10.2% under GW1.5 °C, and 20.3% under GW2.0 °C. The central arid desert shrub area of Central Asia is the only area where both wind and water erosion increase significantly. Wind speed and precipitation are the main factors that contribute to wind and water erosion. Higher vegetation cover helps to reduce wind and water erosion. Under global warming, more population in Central Asia will be affected by soil erosion, primarily in the upper reaches of the Amu River and the lower reaches of the Syr River. This study should provide a scientific basis for formulating the ecological development plans in Central Asia to meet the United Nations Sustainable Development Goals (SDGs).
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•A multiscale approach for modeling viscoelastic composite laminates is developed.•Abaqus plug-in predicts viscoelastic properties of unidirectional composites.•Simulation shows ...effect of stowage on deployment dynamics of a composite hinge.
Due to the inherent viscoelasticity of constituent matrix and the possibility of long-term storage, space deployable structures made of composites are likely to exhibit relaxation in the stored strain energy, which may degrade their deployment performance. This paper presents a bottom-up finite element based multiscale computational strategy that bridges the experimentally measurable properties of constituent fibers and matrix to numerical predictions of viscoelastic behavior of composite laminates and general shell structures. A user-friendly RVE analysis plug-in tool is developed in Abaqus/CAE to rapidly estimate the effective orthotropic viscoelastic properties of unidirectional composites by taking as input the microstructure geometry as well as the known properties of fibers and matrix. Some benchmark problems were solved, and the accuracy and efficiency of the proposed plug-in tool were verified. Next, the strategy is shown to be applicable to model the viscoelastic behavior of macroscale composite laminates and deployable shell structures, by utilizing built-in functions in Abaqus to define the stacking sequence and accordingly update the material properties. In particular, the proposed multiscale strategy was employed to simulate the influence of modulus relaxation on the deployment dynamics of a composite tape-spring hinge, and good agreement was achieved as compared to reported experimental results.
Among natural polymers, starch is one of the most promising biodegradable materials because it is a renewable bioresource that is universally available and of low cost. However, the properties of ...starch-based materials are not satisfactory. One approach is the use of nano-filler as reinforcement for starch-based materials. In this paper, a nanocomposite is prepared using ZnO nanoparticles stabilized by carboxymethylcellulose sodium (CMC) as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. According to the characterization of ZnO–CMC particles with Fourier transform infrared (FTIR), Ultraviolet–visible (UV–vis), X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), ZnO (about 60
wt%) is encapsulated with CMC (about 40
wt%) in ZnO–CMC particles with the size of about 30–40
nm. A low loading of ZnO–CMC particles can obviously improve the pasting viscosity, storage modulus, the glass transition temperature and UV absorbance of GPS/ZnO–CMC nanocomposites. When the ZnO–CMC contents vary from 0 to 5
wt%, the tensile yield strength increase from 3.94
MPa to 9.81
MPa, while the elongation at break reduce from 42.2% to 25.8%. The water vapor permeability decrease from 4.76
×
10
−10 to 1.65
×
10
−10
g
m
−1
s
−1
Pa
−1.
Oklahoma earthquakes in the past decade have been mostly associated with wastewater injection. Here we use a machine learning technique-the Random Forest to forecast induced seismicity rate in ...Oklahoma based on injection-related parameters. We split the data into training (2011.01-2015.05) and test (2015.06-2020.12) periods. The model forecasts seismicity rate during the test period based on input features, including operational parameters (injection rate and pressure), geological information (depth to basement), and modeled pore pressure and poroelastic stress. The results show overall good match with observed seismicity rate (adjusted Formula: see text of 0.75). The model shows that pore pressure rate and poroelastic stressing rates are the two most important features in forecasting. The absolute values of pore pressure and poroelastic stress, and the injection rate itself, are less important than the stressing rates. These findings further emphasize that temporal changes of stressing rates would lead to significant changes in seismicity rates.
Crumpled nanopaper from graphene oxide Ma, Xiaofei; Zachariah, Michael R; Zangmeister, Christopher D
Nano letters,
01/2012, Letnik:
12, Številka:
1
Journal Article
Recenzirano
Graphene oxide (GO) in aqueous solution was aerosolized and rapidly dried to produce crumpled nanopaper-like sheets. Online size selection and aerosol mass analysis was used to determine the fractal ...dimension (D) of crumpled GO nanosheets as 2.54 ± 0.04. That is identical to macroscale materials, such as crumpled balls of paper and foil. Thermal reduction of crumpled GO nanosheets did not change D, even after loss of nearly 25% of the nanosheets mass. We demonstrate that D is able to be tuned by altering solvent conditions. A 10% acetone mixture increased D to 2.68 ± 0.02. Calculations of the confinement force show that crumpling of GO nanosheets is driven by the capillary force associated with rapid solvent loss.
•Water sources of sand-binding vegetation in China were quantified.•Isotope ratios of shallow soil moisture increased along with rainfall.•Root depth determined the differences in water use in ...sand-binding vegetation.•Climate change poses the greatest threat to the stability of Tmarix ramosissima.
Water is the most important factor limiting the growth of sand-binding vegetation (SBV) in desert ecosystems. This study explored the water sources and water use strategies of SBV under a natural precipitation gradient. Six typical SBV species were selected, comprising three tree species, Pinus sylvestris, Haloxylon ammodendron and Populus euphratica, and three shrub species, Artemesia ordosica, Caragana korshinshii and Tmarix ramosissima. The stable isotope values (δD, δ18O) of xylem water and potential water sources (precipitation, soil water, and groundwater) of these species under a precipitation gradient in the sandy regions of northern China were measured. In addition, the relative contributions of the different potential water sources to water use by SBV were analyzed using the MixSIAR model. The results indicated that the Local Meteoric Water Lines (LMWLs) of the six SBV species were located on the right side of the Global Meteoric Water Line (GMWL), with the degree of deviation gradually increasing with a decrease in precipitation. The results showed that T. ramosissima, H. ammodendron and P. euphratica mainly used groundwater (GW), whereas P. sylvestris, A. ordosica and C. korshinshii mainly used soil water. Among those species using soil water, P. sylvestris and A. ordosica mainly used shallow soil water (20–80 cm). P. sylvestris and C. korshinshii showed the highest soil water utilization rate of 14%, whereas P. euphratica showed the lowest soil water utilization rate of 2%. The different SBV species showed significantly different soil water utilization rates due to the influence of plant root distribution (p < 0.001). Among the six SBV species, trees showed a higher GW utilization rate compared to shrubs at 65.74% and 47.29%, respectively, whereas shrubs showed a higher deep soil water utilization rate (140–200 cm) compared to trees at 65.74% and 47.29%, respectively. The precipitation utilization rates amongst the six SBV species were highest in spring, followed by autumn and summer. The utilization of GW by SBV will be intensified in the future due to climate change. However, the stability of T. ramosissima may pose a threat due to its low utilization rate of GW.
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•A successful welded joint between Al 6061 and SS 304 is achieved by CDFW.•The formed IMCs were identified as Fe2Al5, Fe4Al13 and FeAl2.•A thinner diffusion zone was favorable for ...better joint strength and bend ductility.•A low friction time and a high upset pressure caused the optimum joint strength and bend ductility.
A quality joining of Al alloy to steel is difficult to be obtained by fusion welding processes owing to the large difference between melting temperatures and the formation of thick brittle Al/Fe intermetallic compounds (IMCs) layer at the joint interface. In this study, the 6061 Al alloy and 304 austenitic stainless steel were successfully joined by the continuous drive friction welding under different welding parameters. A sound welded joint with joint efficiency of 88 % and bending angle of 80° was obtained at a low friction time and a high upset pressure, where no detect was found at the interface. The IMCs layer was not formed at the interface, but a thin diffusion zone could be observed, indicating the realization of the metallurgical bonding. Under experimental range, a relatively thinner diffusion zone was recommended to ensure higher joint strength and more excellent bend ductility. The IMCs were identified as Fe2Al5, Fe4Al13 and FeAl2 at fracture surface by XRD. The propagation of cracks during tensile testing concentrated on the area where the IMCs existed. The less amount of IMCs was detrimental for joint properties at a low welding parameters. Fracture analysis showed that the dimple fracture predominated the fracture mode for a sound joint.
