•This water cycle study focuses on the impacts of climate change and human activities.•River basin management requires an integrated model of hydro-bio-geochemistry.•Co-evolution of the human–water ...systems should be the focus of future study.
Water is the fundamental natural resource that supports life, ecosystems and human society. Thus studying the water cycle is important for sustainable development. In the context of global climate change, a better understanding of the water cycle is needed. This study summarises current research and highlights future directions of water science from four perspectives: (i) the water cycle; (ii) hydrologic processes; (iii) coupled natural-social water systems; and (iv) integrated watershed management. Emphasis should be placed on understanding the joint impacts of climate change and human activities on hydrological processes and water resources across temporal and spatial scales. Understanding the interactions between land and atmosphere are keys to addressing this issue. Furthermore systematic approaches should be developed for large basin studies. Areas for focused research include: variations of cryosphere hydrological processes in upper alpine zones; and human activities on the water cycle and relevant biogeochemical processes in middle-lower reaches. Because the water cycle is naturally coupled with social characteristics across multiple scales, multi-process and multi-scale models are needed. Hydrological studies should use this new paradigm as part of water-food-energy frontier research. This will help to promote interdisciplinary study across natural and social sciences in accordance with the United Nation's sustainable development goals.
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•Review on the mechanism of kaempferol in the treatment of breast cancer.•Developing into preparations can improve the low bioavailability of kaempferol.•Targeted drug delivery system ...may be a new strategy for kaempferol in the treatment of breast cancer.
In the last century, natural compounds have achieved remarkable achievements in the treatment of tumors through chemotherapy. This inspired scientists to continuously explore anticancer agents from natural compounds. Kaempferol is an ordinary natural compound, the most common flavonoid, which is widely existed in vegetables and fruits. It has been reported to have various anticancer activities, including breast cancer, prostate cancer, bladder cancer, cervical cancer, colon cancer, liver cancer, lung cancer, ovarian cancer, leukemia, etc. Meanwhile, we found that there were more reports on breast cancer among these cancers although there are limited clinical studies that have addressed the benefits of kaempferol as an anti-cancer agent for breast cancer treatment. Then we realize that although kaempferol has been reported to have anti-breast cancer effect many times, it is still far from becoming a real anti-breast cancer agent. Therefore, in this review, we talk about the options for improving the anti-breast cancer effect of kaempferol, including various techniques and methods to improve the bioavailability of kaempferol, the idea of combining other compounds to produce synergistic effects, and the possibility of developing kaempferol into a targeted drug delivery system.
Utilizing the robust transport properties of the topological photonic crystal interface, we experimentally realize two-dimensional topological photonic crystal cavities, where discrete whispering ...gallery modes can propagate unidirectionally along the cavity circumference. Different from traditional cavities, these topological whispering galley modes are insensitive to cavity shapes. Our microwave demonstration has a good agreement with numerical simulations. Using pure dielectrics, by scaling down to the optical wavelength, an optical directional coupler based on the same topological photonic crystal scheme is also proposed. We here show that topological photonics can provide more novel designs for optical devices.
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
Cancer, in any of its forms, remains a significant public health concern worldwide. Advances in early detection and treatment could lead to a decline in the overall death rate from cancer in recent ...decades. Therefore, tumor prediction and classification play an important role in fighting cancer. This study built computational models for a joint analysis of RNA seq, copy number variation (CNV), and DNA methylation to classify normal and tumor samples across liver cancer, breast cancer, and colon adenocarcinoma from The Cancer Genome Atlas (TCGA) dataset. Total of 18 machine learning methods were evaluated based on the AUC, precision, recall, and F-measure. Besides, five techniques were compared to ameliorate problems of class imbalance in the cancer datasets. Synthetic Minority Oversampling Technique (SMOTE) demonstrated the best performance. The results indicate that the model applying Stochastic Gradient Descent (SGD) for learning binary class SVM with hinge loss has the highest classification results on liver cancer and breast cancer datasets, with accuracy over 99% and AUC greater than or equal to 0.999. For colon adenocarcinoma dataset, both SGD and Sequential Minimal Optimization (SMO) that implements John Platt's sequential minimal optimization algorithm for training a support vector machine shows an outstanding classification performance with accuracy of 100%, AUC, precision, recall, and F-measure all at 1.000.
DNA materials have emerged as potential nanocarriers for targeted cancer therapy to precisely deliver cargos with specific purposes. The short half‐life and low bioavailability of DNA materials due ...to their interception by the reticuloendothelial system and blood clearance further limit their clinical translation. This study employs an HER2‐targeted DNA‐aptamer‐modified DNA tetrahedron (HApt‐tFNA) as a drug delivery system, and combines maytansine (DM1) to develop the HApt‐DNA tetrahedron/DM1 conjugate (HApt‐tFNA@DM1, HTD, HApDC) for targeted therapy of HER2‐positive cancer. To optimize the pharmacokinetics and tumor‐aggregation of HTD, a biomimetic camouflage is applied to embed HTD. The biomimetic camouflage is constructed by merging the erythrocyte membrane with pH‐responsive functionalized synthetic liposomes, thus with excellent performance of drug delivery and tumor‐stimulated drug release. The hybrid erythrosome‐based nanoparticles show better inhibition of HER2‐positive cancer than other drug formulations and exhibit superior biosafety. With the strengths of precise delivery, increased drug loading, sensitive tumor probing, and prolonged circulation time, the HApDC represents a promising nanomedicine to treat HER2‐positive tumors. Notably, this study developsa dual‐targeting nanoparticle by combining pH‐sensitive camouflage and HApDC, initiating an important step toward the development and application of DNA‐based medicine and biomimetic cell membrane materials in cancer treatment and other potential biological applications.
A PEOz‐erythrosome vesicle loaded with HER2 aptamer‐DNA tetrahedron/maytansine conjugates (HApt‐tFNA@DM1, HTD) is developed for targeted delivery of the HApDCs to HER2‐positive cancer. The PEOz‐erythrosome@HTD prolongs the blood circulation of HTD, protects it from the early blood clearance, and then delivers and releases it into the tumor microenvironment, further improving the antitumor activity of HApDC.
Potential evaporation (EP) is an important concept that has been extensively used in hydrology, climate, agriculture and many other relevant fields. However, EP estimates using conventional ...approaches generally do not conform with the underlying idea of EP, since meteorological forcing variables observed under real conditions are not necessarily equivalent to those over a hypothetical surface with an unlimited water supply. Here, we estimate EP using a recently developed ocean surface evaporation model (i.e., the maximum evaporation model) that explicitly acknowledges the inter‐dependence between evaporation, surface temperature (Ts) and radiation such that is able to recover radiation and Ts to a hypothetical wet surface. We first test the maximum evaporation model over land by validating its evaporation estimates with evaporation observations under unstressed conditions at 86 flux sites and found an overall good performance. We then apply the maximum evaporation model to the entire terrestrial surfaces under both wet and dry conditions to estimate EP. The mean annual (1979–2019) global land EP from the maximum evaporation model (EP_max) is 1,272 mm yr−1, which is 11.2% higher than that estimated using the widely adopted Priestley‐Taylor model (EP_PT). The difference between EP_max and EP_PT is negligible in humid regions or under wet conditions but becomes increasingly larger as the surface moisture availability decreases. This difference is primarily caused by increased net radiation (Rn) when restoring the dry surfaces to hypothetical wet surfaces, despite a lower Ts obtained under hypothetical wet conditions in the maximum evaporation model.
Key Points
We estimate potential evaporation (EP) using a maximum evaporation model that recovers radiation and temperature to a hypothetical wet condition
Mean global land EP from the maximum evaporation model is 1,272 mm yr−1, which is 11.2% higher than the Priestley‐Taylor estimate
The higher EP from the maximum evaporation model is mainly caused by higher net radiation over hypothetical wet surfaces
Accurate assessments of spatial–temporal variations in water use efficiency (WUE) are important for evaluation of carbon and water balances. In this study, the spatial and temporal patterns of WUE ...and associated climate controls in China's Loess Plateau are investigated over 2000–2010 by utilizing remote sensing data and multiple statistical methods; which provides a greater understanding about how WUE changed after the Grain to Green Program (GTGP) launched. Carbon sequestration (i.e., net primary productivity, NPP) is estimated with the CASA model and water consumption (i.e., evapotranspiration, ET) is obtained from the MODIS product (i.e., MOD16). Our results identify an increasing trend in the regional mean NPP that amounted to 7.593gC/m2·yr with an average value of 310.035gC/m2·yr. Changes in ET are segmented into three stages, the growth (2000−2003), decline (2004–2006) and stable (2007–2010) stages. Regional WUE is measured at 0.915gC/mm·m2 and shows an upward trend at a rate of 0.027gC/mm·m2·yr. Spatially, significant regional heterogeneity is found in both NPP and WUE with gradients decreasing from the southeast to the northwest, but sharp rises detected in northern Shaanxi. At the biome level, the annual average WUE of the four groups decrease in the order of grasslands>woodlands>shrublands>croplands. Moreover, all biomes in the grassland ecosystems exhibit a growth in WUE as does the arid desert zone in the northwestern region, suggesting that vegetation in moderately water-deficient areas may have a higher tolerance to drought. Among different meteorological factors, precipitation and drought severity index (DSI) in the Loess Plateau show a latitudinal zonality and influences the WUE, which indicated that the moisture rather than temperature would be the major control factor of the regional WUE. Finally, significant variation in vegetation WUE sensitivity in response to meteorological factors is noted. Temperature is found to be the dominant driving factor of shrublands WUE, whereas precipitation primarily influenced the WUE of grasslands, croplands, and woodlands.
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•Spatial pattern of water use efficiency (WUE) is mainly explained by precipitation•WUE shows the highest growth rate in water deficient regions•Loess Plateau's WUE increased both at the regional and biome levels•Grassland has the highest annual average WUE and the supreme WUE growth rate•Precipitation has significant influence on grassland, cropland and woodland's WUE
Two-dimensional photonic crystals, in analogy to AB/BA stacking bilayer graphene in electronic system, are studied. Inequivalent valleys in the momentum space for photons can be manipulated by simply ...engineering diameters of cylinders in a honeycomb lattice. The inequivalent valleys in photonic crystal are selectively excited by a designed optical chiral source and bulk valley polarizations are visualized. Unidirectional valley interface states are proved to exist on a domain wall connecting two photonic crystals with different valley Chern numbers. With the similar optical vortex index, interface states can couple with bulk valley polarizations and thus valley filter and valley coupler can be designed. Our simple dielectric PC scheme can help to exploit the valley degree of freedom for future optical devices.
Plant rooting depth (Zr) is a key parameter in hydrological and biogeochemical models, yet the global spatial distribution of Zr is largely unknown due to the difficulties in its direct measurement. ...Additionally, Zr observations are usually only representative of a single plant or several plants, which can differ greatly from the effective Zr over a modeling unit (e.g., catchment or grid‐box). Here, we provide a global parameterization of an analytical Zr model that balances the marginal carbon cost and benefit of deeper roots, and produce a climatological (i.e., 1982–2010 average) global Zr map. To test the Zr estimates, we apply the estimated Zr in a highly transparent hydrological model (i.e., the Budyko‐Choudhury‐Porporato (BCP) model) to estimate mean annual actual evapotranspiration (E) across the globe. We then compare the estimated E with both water balance‐based E observations at 32 major catchments and satellite grid‐box retrievals across the globe. Our results show that the BCP model, when implemented with Zr estimated herein, optimally reproduced the spatial pattern of E at both scales (i.e., R2 = 0.94, RMSD = 74 mm yr−1 for catchments, and R2 = 0.90, RMSD = 125 mm yr−1 for grid‐boxes) and provides improved model outputs when compared to BCP model results from two already existing global Zr data sets. These results suggest that our Zr estimates can be effectively used in state‐of‐the‐art hydrological models, and potentially biogeochemical models, where the determination of Zr currently largely relies on biome type‐based look‐up tables.
Key Points:
We estimate the effective plant rooting depth (Zr) using a carbon cost‐benefit model across global terrestrial ecosystems
Both mean climate conditions and climate seasonality are essential in determining Zr
Zr estimated herein is more hydrologically effective than existing global Zr data sets
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