► The integrated modeling system proved to be a useful approach for studying the effects of urbanization on runoff and flood. ► Smaller flood event is more affected by urbanization than larger flood. ...► Floods discharges are more affected by urbanization than annual runoff. ► At daily time step modeling, flood volume is more affected by urbanization than flood peak.
This study developed and used an integrated modeling system, coupling a distributed hydrologic and a dynamic land-use change model, to examine effects of urbanization on annual runoff and flood events of the Qinhuai River watershed in Jiangsu Province, China. The Hydrologic Engineering Center’s Hydrologic Modeling System (HEC-HMS) was used to calculate runoff generation and the integrated Markov Chain and Cellular Automata model (CA-Markov model) was used to develop future land use maps. The model was calibrated and validated using observed daily streamflow data collected at the two outlets of watershed. Landsat Thematic Mapper (TM) images from 1988, 1994, 2006, Enhanced Thematic Mapper Plus (ETM+) images from 2001, 2003 and a China–Brazil Earth Resources Satellite (CBERS) image from 2009 were used to obtain historical land use maps. These imageries revealed that the watershed experienced conversion of approximately 17% non-urban area to urban area between 1988 and 2009. The urbanization scenarios for various years were developed by overlaying impervious surfaces of different land use maps to 1988 (as a reference year) map sequentially. The simulation results of HEC-HMS model for the various urbanization scenarios indicate that annual runoff, daily peak flow, and flood volume have increased to different degrees due to urban expansion during the study period (1988–2009), and will continue to increase as urban areas increase in the future. When impervious ratios change from 3% (1988) to 31% (2018), the mean annual runoff would increase slightly and the annual runoff in the dry year would increase more than that in the wet year. The daily peak discharge of eight selected floods would increase from 2.3% to 13.9%. The change trend of flood volumes is similar with that of peak discharge, but with larger percentage changes than that of daily peak flows in all scenarios. Sensitivity analysis revealed that the potential changes in peak discharge and flood volume with increasing impervious surface showed a linear relationship, and the changes of small floods were larger than those of large floods with the same impervious increase, indicating that the small floods were more sensitive than large floods to urbanization. These results suggest that integrating distributed land use change model and distributed hydrological model can be a good approach to evaluate the hydrologic impacts of urbanization, which are essential for watershed management, water resources planning, and flood management for sustainable development.
Furans represent one of the most important classes of intermediates in the conversion of non-edible lignocellulosic biomass into bio-based chemicals and fuels. At present, bio-furan derivatives are ...generally obtained from cellulose and hemicellulose fractions of biomass via the acid-catalyzed dehydration of their relative C6-C5 sugars and then converted into a wide range of products. Furfural (FUR) and 5-hydroxymethylfurfural (HMF) are surely the most used furan-based feedstocks since their chemical structure allows the preparation of various high-value-added chemicals. Among several well-established catalytic approaches, hydrogenation and oxygenation processes have been efficiently adopted for upgrading furans; however, harsh reaction conditions are generally required. In this review, we aim to discuss the conversion of biomass derived FUR and HMF through unconventional (transfer hydrogenation, photocatalytic and electrocatalytic) catalytic processes promoted by heterogeneous catalytic systems. The reaction conditions adopted, the chemical nature and the physico-chemical properties of the most employed heterogeneous systems in enhancing the catalytic activity and in driving the selectivity to desired products are presented and compared. At the same time, the latest results in the production of FUR and HMF through novel environmental friendly processes starting from lignocellulose as well as from wastes and by-products obtained in the processing of biomass are also overviewed.
Abstract
Two-dimensional (2D) topological insulators (TIs) are promising platforms for low-dissipation spintronic devices based on the quantum-spin-Hall (QSH) effect, but experimental realization of ...such systems with a large band gap suitable for room-temperature applications has proven difficult. Here, we report the successful growth on bilayer graphene of a quasi-freestanding WSe
2
single layer with the 1
T
′ structure that does not exist in the bulk form of WSe
2
. Using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy/spectroscopy (STM/STS), we observe a gap of 129 meV in the 1
T
′ layer and an in-gap edge state located near the layer boundary. The system′s 2D TI characters are confirmed by first-principles calculations. The observed gap diminishes with doping by Rb adsorption, ultimately leading to an insulator–semimetal transition. The discovery of this large-gap 2D TI with a tunable band gap opens up opportunities for developing advanced nanoscale systems and quantum devices.
Abstract
Two-dimensional materials constitute a promising platform for developing nanoscale devices and systems. Their physical properties can be very different from those of the corresponding ...three-dimensional materials because of extreme quantum confinement and dimensional reduction. Here we report a study of TiTe
2
from the single-layer to the bulk limit. Using angle-resolved photoemission spectroscopy and scanning tunneling microscopy and spectroscopy, we observed the emergence of a (2 × 2) charge density wave order in single-layer TiTe
2
with a transition temperature of 92 ± 3 K. Also observed was a pseudogap of about 28 meV at the Fermi level at 4.2 K. Surprisingly, no charge density wave transitions were observed in two-layer and multi-layer TiTe
2
, despite the quasi-two-dimensional nature of the material in the bulk. The unique charge density wave phenomenon in the single layer raises intriguing questions that challenge the prevailing thinking about the mechanisms of charge density wave formation.
► We conducted the case study on the hydrologic response to urbanization using SWAT model. ► Hydrological responses were different in different seasons and hydrological years. ► Urbanization and its ...impacts were more sensitive in the suburban basin close to city. ► Urbanization had a more remarkable impact on surface runoff than on total streamflow. ► Urbanization tended to increase peak discharge and flood volume.
The Main objective of the study is to understand and quantify the hydrological responses of land use and land cover changes. The Yangtze River Delta is one of the most developed regions in China with the rapid development of urbanization which serves as an excellent case study site for understanding the hydrological response to urbanization and land use change. The Xitiaoxi River basin, one of the main upstream rivers to the Taihu Lake in the Yangtze River Delta, was selected to perform the study. The urban area in the basin increased from 37.8km2 in 1985 to 105km2 in 2008. SWAT model, which makes direct use of land cover and land use data in simulating streamflow, provides as a useful tool for performing such studies and is therefore used in this study. The results showed that (1) the expansion of urban areas had a slight influence on the simulated annual streamflow and evapotranspiration (ET) as far as the whole catchment is concerned; (2) surface runoff and baseflow were found more sensitive to urbanization, which had increased by 11.3% and declined by 11.2%, respectively; (3) changes in streamflow, evapotranspiration and surface runoff were more pronounced during the wet season (from May to August), while baseflow and lateral flow had a slight seasonal variation; (4) the model simulated peak discharge increased 1.6–4.3% and flood volume increased 0.7–2.3% for the selected storm rainfall events at the entire basin level, and the change rate was larger for smaller flood events than for larger events; (5) spatially, changes of hydrological fluxes were more remarkable in the suburban basin which had a relative larger increase in urbanization than in rural sub-basins; and (6) analysis of future scenarios showed the impacts of urbanization on hydrological fluxes would be more obvious with growth in impervious areas from 15% to 30%. In conclusion, the urbanization would have a slight impact on annual water yield, but a remarkable impact was found on surface runoff, peak discharge and flood volume especially in suburban basins in the study area. The study suggested that more attention must be paid for flood mitigation and water resources management in planning future urban development in the region.
Genomic selection holds a great promise to accelerate plant breeding via early selection before phenotypes are measured, and it offers major advantages over marker-assisted selection for highly ...polygenic traits. In addition to genomic data, metabolome and transcriptome are increasingly receiving attention as new data sources for phenotype prediction. We used data available from maize as a model to compare the predictive abilities of three different omic data sources using eight representative methods for six traits. We found that the best linear unbiased prediction overall performs better than other methods across different traits and different omic data, and genomic prediction performs better than transcriptomic and metabolomic predictions. For the same maize data, we also conducted genome-wide association study, transcriptome-wide association studies and metabolome-wide association studies for the six agronomic traits using both the genome-wide efficient mixed model association (GEMMA) method and a modified least absolute shrinkage and selection operator (LASSO) method. The new LASSO method has the ability to perform statistical tests. Simulation studies show that the modified LASSO performs better than GEMMA in terms of high power and low Type 1 error.
ABSTRACT
The receptor activator of NF‐κB ligand‐induced osteoclast differentiation has a critical role in the process of bone metabolism. Overactivation of osteoclastogenesis may result in a series ...of diseases. Irisin, a novel myokine, which was first reported in 2012, has been proposed to mediate the beneficial metabolic effects of exercise. Studies have demonstrated that irisin targets osteoblasts by promoting osteoblast proliferation and differentiation; how ever, the underlying mechanism regarding the effect of irisin on osteoclasts remains elusive. Using 2 types of osteoclast precursor cells, RAW264.7 cells and mouse bone marrow monocytes, we showed that irisin promoted osteoclast precursor cell proliferation but inhibited osteoclast differentiation. Irisin down‐regulated the expression of osteoclast differentiation marker genes, including receptor activators of NF‐κB, nuclear factor of activated T cells, cytoplasmic 1, cathepsin K, and tartrate‐resistant acid phosphatase (TRAP), as well as decreasing the number of TRAP‐positive multinucleated cells and hydroxyapatite resorption pits. Furthermore, we showed that irisin sup pressed the NF‐κB signaling pathway, but activated the p38 and JNK signaling pathways. In the presence of an inhibitor of p38 and JNK, irisin‐induced promotion of RAW264.7 cell proliferation was attenuated. However, irisin‐ induced inhibition of osteoclast differentiation was not affected by either the p38 or JNK signaling pathway. Our study suggested the direct effect of irisin on osteoclastogenesis and revealed the mechanism responsible for the therapeutic potential of irisin in bone metabolism disease.—Ma, Y., Qiao, X., Zeng, R., Cheng, R., Zhang, J., Luo, Y., Nie, Y., Hu, Y., Yang, Z., Zhang, J., Liu, L., Xu, W., Xu, C. C., Xu, L. Irisin promotes proliferation but inhibits differentiation in osteoclast precursor cells. FASEB J. 32, 5813–5823 (2018). www.fasebj.org
Three evapotranspiration models using the complementary relationship approach for estimating areal actual evapotranspiration were evaluated and compared in three study regions representing a large ...geographic and climatic diversity: NOPEX region in Central Sweden (cool temperate, humid), Baixi catchment in Eastern China (subtropical, humid), and the Potamos tou Pyrgou River catchment in Northwestern Cyprus (semiarid to arid). The models are the CRAE model of Morton, the advection–aridity (AA) model of Brutsaert and Stricker, and the GG model proposed by Granger and Gray using the concept of relative evapotranspiration (the ratio of actual to potential evapotranspiration). The calculation was made on a daily basis and comparison was made on monthly and annual bases. The study was performed in two steps: First, the three evapotranspiration models with their original parameter values were applied to the three regions in order to test their general applicability. Second, the parameter values were locally calibrated based on the water balance study. The results showed that (1) using the original parameter values all three complementary relationship models worked reasonably well for the temperate humid region, while the predictive power decreases in moving toward regions of increased soil moisture control, i.e. increased aridity. In such regions, the parameters need to be calibrated. (2) Using the locally calibrated parameter values all three models produced the annual values correctly. For the monthly values there was a time shift for the appearance of maximum monthly values between the evapotranspiration model estimations and water balance calculations, and the drier the region, the larger the difference. Further examination of the water balance components showed that while the actual evapotranspiration is controlled by several hydrometeorological factors in warmer and drier months the soil moisture is the dominating factor.
Nonlinear microscopy techniques developed over the past two decades have provided dramatic new capabilities for biological imaging. The initial demonstrations of nonlinear microscopies coincided with ...the development of solid-state femtosecond lasers, which continue to dominate applications of nonlinear microscopy. Fiber lasers offer attractive features for biological and biomedical imaging, and recent advances are leading to high-performance sources with the potential for robust, inexpensive, integrated instruments. This article discusses recent advances, and identifies challenges and opportunities for fiber lasers in nonlinear bioimaging.
PDF
