Vegetation change is a critical factor that profoundly affects the terrestrial water cycle. Here we derive an analytical solution for the impact of vegetation changes on hydrological partitioning ...within the Budyko framework. This is achieved by deriving an analytical expression between leaf area index (LAI) change and the Budyko land surface parameter (n) change, through the combination of a steady state ecohydrological model with an analytical carbon cost‐benefit model for plant rooting depth. Using China where vegetation coverage has experienced dramatic changes over the past two decades as a study case, we quantify the impact of LAI changes on the hydrological partitioning during 1982–2010 and predict the future influence of these changes for the 21st century using climate model projections. Results show that LAI change exhibits an increasing importance on altering hydrological partitioning as climate becomes drier. In semiarid and arid China, increased LAI has led to substantial streamflow reductions over the past three decades (on average −8.5% in 1990s and −11.7% in 2000s compared to the 1980s baseline), and this decreasing trend in streamflow is projected to continue toward the end of this century due to predicted LAI increases. Our result calls for caution regarding the large‐scale revegetation activities currently being implemented in arid and semiarid China, which may result in serious future water scarcity issues here. The analytical model developed here is physically based and suitable for simultaneously assessing both vegetation changes and climate change induced changes to streamflow globally.
Key Points
We derive an analytical solution for the impact of LAI changes on hydrological partitioning within the Budyko framework
Sensitivity of hydrological partitioning to changes in LAI increases with the increase of climate aridity
Impacts of past and future vegetation and climate changes on streamflow across China were assessed
The changing climate is affecting the frozen soil at an unprecedented rate across the Northern Hemisphere. However, due to sparse ground measurements, the changes of frozen soil and the environmental ...controls over the vast cryosphere are still unclear, such as in the Tibetan Plateau (TP). In this study, a process-based model solely driven by satellite remote sensing data is employed to investigate the spatiotemporal changes of seasonally frozen ground and permafrost over the entire TP (~3 million km2) during 2002–2016 at a spatial resolution of 1 km. Comprehensive validations against in situ observations of frozen ground types, mean annual ground temperature, active layer thickness, soil temperature, and frozen depth at 608 boreholes and 109 meteorological stations demonstrate an overall satisfactory performance of the model in reproducing the spatial pattern and temporal evolution of the frozen soil in the region. Spatially, land surface temperature (LST; both in-season and off-season) primarily controls the frozen ground types and frozen depth, with seasonally frozen ground and permafrost covering ~56% and ~ 37% of the plateau, respectively. The estimated spatial-averaged annual maximum soil freeze depth (SFD) is ~1.29 m, and the annual maximum active layer thickness (ALT) of permafrost is ~1.85 m. Temporally, ALT shows an overall increasing trend at an average rate of +3.17 cm yr−1, while SFD exhibits both decreasing (at ~62% areas) and increasing (at ~38% areas) trends in the region. Again, LST is found to be the dominant factor that controls the temporal changes in both SFD and ALT while precipitation (i.e., both rainfall and snowfall) plays an important (especially in more arid areas and regions near the lower limit of permafrost) but secondary role. Our results demonstrate the advantages of the satellite-based method in frozen soil simulations over large scales with complex topography and landscape and highlight the important roles of both temperature and precipitation in shaping the frozen soil patterns on the TP or other cold, dry regions.
•Satellite-based model well reproduced frozen soil changes (FSC) across the TP•Permafrost show consistent degradation over 2002–2016•Seasonally frozen ground show roughly competent increasing and decreasing trends•Both in-season and off-season LST are found to impact on FSC•Precipitation affects FSC in arid regions and regions near permafrost lower limit
The ratio of potential evapotranspiration (E0) over precipitation (P), known as the aridity index (AI), has been commonly used to stratify global aridity zones and widely adopted to assess changes in ...aridity globally. Anthropogenic climate change, in particular atmospheric warming, is projected to increase AI, which has in most cases been interpreted as increasing terrestrial aridity. In this study we demonstrate, for both past and future conditions, that such an interpretation requires reconsideration. Using catchment observations over the past 30 years and climate model projections for the 21st century, we show that increased AI does not ubiquitously lead to a decreased water availability over land, using surface runoff (Q) as an indicator. This is primarily caused by a higher Q sensitivity to changes in P (SP) and a lower Q sensitivity to changes in E0 (SE0), with the ratio of SP over SE0 being higher than the relative changes of E0 compared to P (i.e., |P × SP| > |E0 × SE0|). Assessment of Coupled Model Intercomparison Project Phase 5 model outputs indicates that both Q and AI change‐induced Q changes are increasing over the majority of the globe for the 21st century despite increasing AI (a drying atmosphere). Our findings demonstrate a disconnection between the atmospheric drying trends and surface runoff trends and call for caution when interpreting retrospective and future changes in terrestrial aridity based on AI and related measures.
Key Points
We demonstrate a clear disconnection between the trends in atmospheric drying and continental runoff
The disconnection is due to a larger runoff change induced by precipitation change than that induced by potential evapotranspiration change
Reassessment of CMIP5 model projections reveals an increased runoff induced by increased atmospheric aridity in the coming century
Infrared temperature precursor anomalies are always accompanied by the propagation of cracks in rocks under external loads. Experiments were conducted to observe the infrared temperature change of ...granite surfaces to investigate the damage characteristics and failure mechanism of granite under ultrasonic vibration. Ultrasonic vibration load test of cylindrical granite samples with a 200 N force were carried out using a 30 kHz piezoelectric ceramic ultrasonic vibrator. During testing, an infrared thermal imager was used to observe and measure the infrared radiation temperature of the rock during the entire loading process. The experimental results show that sharp infrared temperature increase serving as a precursor to rock failure under ultrasonic vibration. The damage and failure process of the rock can be divided into the following three stages: Stage I, corresponding to elastic deformation (0–102.23 s, temperature range 26–150 °C), Stage II, which include micro-fracture and yield (102.3–118.5 s, temperature range 150–306.9 °C), and Stage III, in which macrocracks and failure are produced (118.5–191.833 s, temperature range 256.9–397.2 °C). The core of the rock may be divided into a fracture zone, plastic deformation zone, and elastic deformation zone according to the axial temperature variation of the sample. The effective fracture depth achieved in the rock is 10 mm. As a principal result we show that the fatigue damage caused by ultrasonic vibration and the thermal damage caused by rising temperature are the major factors for breaking granite. The research results in this paper will provide guidance for the application of ultrasonic technology in the drilling field.
Abstract In the 20th century, with the intensification of human activities, the Earth is experiencing unprecedented warming. However, there are certain differences in the sensitivity of temperature ...changes to anthropogenic forcings in different regions and at different altitudes of the troposphere. The time of emergence (TOE) is the key point at which the anthropogenic climate change signal exceeds from the internal climate variability serving as a noise. It is a crucial variable for climate change detection, climate prediction and risk assessment. Here, we systematically analyzed the spatiotemporal characteristics of the TOE of temperature changes over the past century by calculating the SNR based on the selected CMIP6 multi-model outputs. The results show that the temperature TOE, particularly in the lower and middle troposphere, shows distinct latitude dependence, displaying an ‘M-type’ distribution from the Antarctic to the Arctic: it first appears in low-latitudes, followed by high-latitudes, and last appears in the two mid latitude bands. For the tropics, the TOE of tropospheric temperatures becomes earlier with increasing altitude: the TOE of air temperatures at the surface, mid-tropospheric 500 hPa and upper-tropospheric 200 hPa occurs in 1980 ± 15, 1965 ± 20, and 1930 ± 30, respectively. The TOEs of tropospheric temperatures in eastern equatorial Pacific are 10–30 years later than those in the western equatorial Pacific. For the regional TOEs of surface air temperature diverse differences exist on land and ocean in various latitudes of two hemispheres.
It has long been assumed that over a sufficiently long period of time, changes in catchment water storage (ΔS) are a relatively minor term compared to other fluxes and can be neglected in the ...catchment water balance equation. However, the validity of this fundamental assumption has rarely been tested, and the associated uncertainties in water balance calculations remain unknown. Here, we use long‐term (1982–2011) observations of monthly streamflow (Q) and precipitation (P) for 1,057 global unimpaired catchments, combined with four independent evapotranspiration (E) estimates to infer ΔS and to provide a global assessment of the steady‐state assumption in catchment water balance calculations. Results show that when the threshold for steady state is set to 5% of the mean monthly P, ~70% of the catchments attain steady state within 10 years while ~6% of the catchments fail to reach a steady state even after 30 years. The time needed for a catchment to reach steady state (τs) shows a close relationship with climatic aridity and vegetation coverage, with arid/semiarid and sparsely vegetated catchments generally having a longer τs. Additionally, increasing snowfall fraction also increases τs. The imbalance (ewb) caused by ignoring ΔS decreases as averaging period for water balance calculations increases as expected. For a typical 10‐year averaging period, ewb accounts for ~7% of P in arid, but that decreases to ~3% of P in humid catchments. These results suggest that catchment properties should be considered when applying the steady‐state assumption and call for caution when ignoring ΔS in arid/semiarid regions.
Key Points
The steady‐state assumption in water balance calculation and associated errors across global catchments are assessed
Arid/semiarid catchments require a longer time to reach an approximate steady state than humid/subhumid catchments
Imbalance caused by ignoring storage change accounts for 7% (3%) of precipitation in arid (humid) catchments for a typical 10‐year period
Immunotherapy will significantly impact the standard of care in cancer treatment. Recent advances in nanotechnology can improve the efficacy of cancer immunotherapy. However, concerns regarding ...efficiency of cancer nanomedicine, complex tumor microenvironment, patient heterogeneity, and systemic immunotoxicity drive interest in more novel approaches to be developed. For this purpose, biomimetic nanoparticles are developed to make innovative changes in the delivery and biodistribution of immunotherapeutics. Biomimetic nanoparticles have several advantages that can advance the clinical efficacy of cancer immunotherapy. Thus there is a greater push toward the utilization of biomimetic nanotechnology for developing effective cancer immunotherapeutics that demonstrate increased specificity and potency. The recent works and state‐of‐the‐art strategies for anti‐tumor immunotherapeutics are highlighted here, and particular emphasis has been given to the applications of cell‐derived biomimetic nanotechnology for cancer immunotherapy.
Biomimetic nanotechnology has considerable scope for cancer immunotherapy. The optimized development of biomimetic nanoparticles can actively enhance the therapeutic efficacy of cancer immunotherapy. The review attempts to provide a brief overview of this emerging area, where biomimetic nanoparticles has been used in the field of immunotherapy for cancer treatment. It highlights the recent developments in immunotherapeutics based on cell membrane‐derived biomimetic nanoparticles and its related applications in cancer.
Based on the designed inverted Y-shaped peptide and MXene nanocomposite (MXene-Au@ZIF-67), a ratiometric anti-pollution electrochemical biosensor was designed and applied to the detection of ...biomarkers in serum. Au@ZIF-67 inserted into the interior of MXene can not only prevent the accumulation of MXene but also provide a large amounts of binding sites for capturing biomolecules. A designed multifunctional Y-shaped peptide containing anchoring, antifouling, and recognition sequences was anchored onto MXene-Au@ZIF-67 through Au–S bonds. Electrochemical signal molecules, ferrocenecarboxylic acid (Fc) and methylene blue (MB), were modified to another end of multifunctional peptide and interior of MXene-Au@ZIF-67, respectively, to produce a ratiometric electrochemical signal. We selected prostate specific antigen (PSA) as the model compound. PSA specifically recognizes and cleaves the recognition segment in the Y-shaped peptide, and the signal of Fc is reduced, while the signal of MB remains unchanged. The ratiometric strategy endows the present biosensor high accuracy and sensitivity with a detection limit of 0.85 pg/mL. In addition, the sensing surface has good antifouling ability due to the antifouling sequence of the two branching parts of the Y-shaped peptide. More importantly, by replacing the recognition segment of peptides also other targets are accessible, indicating the potential application of the universal detection strategy to the detection of various biomarkers in clinical diagnosis.
Graphical Abstract
The construction of N-N axially chiral motifs is an important research topic, owing to their wide occurrence in natural products, pharmaceuticals and chiral ligands. One efficient method is the ...atroposelective dihydropyrimidin-4-one formation. We present herein a direct catalytic synthesis of N-N atropisomers with simultaneous creation of contiguous axial and central chirality by oxidative NHC (N-heterocyclic carbenes) catalyzed (3 + 3) cycloaddition. Using our method, we are able to synthesize structurally diverse N-N axially chiral pyrroles and indoles with vicinal central chirality or bearing a 2,3-dihydropyrimidin-4-one moiety in moderate to good yields and excellent enantioselectivities. Further synthetic transformations of the obtained axially chiral pyrroles and indoles derivative products are demonstrated. The reaction mechanism and the origin of enantioselectivity are understood through DFT calculations.
•The contact line profile captured by TSP is consistent with that by an infrared camera.•Three stages could be observed during sessile droplet evaporation on a heated substrate.•The occurrence of ...convection cells leads to obvious temperature gradient on interface.•The heat flux at the contact line is higher than that at the centre.
The present work is aimed at analyzing changes in the interfacial temperature distribution and interfacial heat flux distribution during sessile droplet evaporation. In particular, two kinds of nonintrusive measurement techniques, temperature-sensitive paint (TSP) and infrared imaging were used simultaneously. TSP was used to capture the interfacial temperature distribution, and then a one-dimensional unsteady transient model was established to obtain the heat flux distribution. An infrared camera was applied to observe the thermal patterns during droplet evaporation from the top view. Three kinds of liquids, pentane, HFE-7100 and hexane, were used during our experiments, and the experimental results show that the contact line profile captured by TSP was consistent with that captured by an infrared camera. Three stages could be observed during droplet evaporation: initial droplet heating, convection cell evaporation and thin film evaporation. Convection cells could be observed in the infrared images during the second stage, and an obvious temperature gradient at the contact surface could also be seen from the images captured by TSP. In addition, the heat flux at the contact line was higher than that at the centre. Finally, the heat dissipation due to droplet evaporation could also be obtained by double integration of interfacial heat flux data with contact area and evaporation time, which further demonstrated the soundness of the present experimental and calculated methods.
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