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Organic semiconductor single crystals (OSSCs) possess high mobility and ultra-long spin relaxation times in the millisecond or even second range, mainly due to their pure material systems, perfect periodic structures, and inherent weak spin–orbit coupling (SOC). Coupling this with their excellent photoelectric functionality, they have long been considered as perfect materials for organic spintronic applications to obtain both long-distance spin transport and novel multifunctionality at room temperature, attracting wide interest. Currently, spintronic studies based on OSSCs are still at the heuristic stage, and there are many related critical challenges, as well as important opportunities. Herein, this perspective article, relying on developed theory and in-depth investigations of organic semiconductors (OSCs) in electronics and spintronics, provides discussion and future prospects, focusing on several aspects of OSSCs; we aim to inspire progress in this new field and attempt to guide a wide range of research in related fields. Firstly, as the spin relaxation time and charge carrier mobility are the two main factors affecting the spin diffusion length, the effects of the molecular structure and stacking structure regarding these two factors are discussed, covering material design and regulation methods in detail. Then, the current situation and challenges relating to device fabrication technology based on OSSCs are outlined, highlighting what needs to be solved in order to build a foundation for achieving extra-long spin transport in OSSCs and novel multifunctional OSSC-based spintronic devices. Finally, based on various reported multifunctional spintronic devices and OSSCs with excellent photoelectric properties, the exploitation of novel multifunctional spintronic devices is discussed.

As a new type of inorganic-organic hybrid semiconductor, quantum confined atomically precise metal nanoclusters (MNCs) have been widely applied in the fields of chemical sensing, optical imaging, biomedicine and catalysis. Herein, we successfully design and fabricate the first example of MNC-based spin valves (SVs) that exhibit remarkable magnetoresistance (MR) value up to 1.6% even at room temperature (300 K). The concomitant photoresponse of MNC-based SVs unambiguously confirms that the spin-polarized electron transmission takes place across the MNC interlayer. Furthermore, the spin-dependent transport property of MNC-based SVs is largely varied by changing the atomic structure of MNCs. Both experimental proofs and quantum chemistry calculations reveal that the atomic structure-discriminative spin transport behavior is attributed to the distinct spin-orbit coupling (SOC) effect of MNCs.

As a traditional Chinese condiment, douchi has attracted the attention of Asian and European countries because of its high nutrient contents and unique flavors. The current production method of Douchi is mostly natural fermentation. The quality of douchi produced in this way is affected by microbial species, temperature, humidity and season, so the physical and chemical properties of the product, the content of flavor substances and the safety are unstable. In this study, four safe strains with high protease activity screened in the previous laboratory including Bacillus velezensis, Bacillus amyloliquefaciens, Lichtheimia ramosa, and Lichtheimia corymbifera were used as starter cultures for douchi fermentation.After 35 days, the results showed, the pH, titratable acids, free amino-type nitrogen, amino acids, the total number of colonies, and neutral protease activity of all samples reached an average level. Through GC-MS (Gas Chromatography-Mass Spectrometer) analysis, the content of key aroma substances aldehydes and esters were higher than commercial douchi and the free amino acids of douchi fermented by the four strains were 3 to 5 times that of commercial douchi, respectively. Among them, the douchi fermented by Bacillus amyloliquefaciens has more flavor substances, and the highest DPPH free radical scavenging rates of 92.4%. Four samples yielded total phenolic contents and soy isoflavones in the range of 0.98-1.93 g/kg and 0.58-0.89 g/kg.These findings indicate that the use of high protease activity starter to produce douchi can improve the quality of douchi to a certain extent. Among them, the douchi obtained by the strain of Bacillus amyloliquefaciens not only has good flavor but also has high antioxidant activities. This article is protected by copyright. All rights reserved.

The interrelationship between regional water, energy, food, and land systems is extremely complex. Hence, accurately assessing the coupling coordination relationship and identifying the influential factors of the water-energy-food-land nexus (WEFL nexus) are of utmost importance. This study proposes a novel analytical framework and evaluation index system for exploring interactions across the WEFL nexus. The comprehensive benefit evaluation index (CBEI), coupling coordination degree (CCD) model, and obstacle factor diagnosis model are integrated to assess and analyze the coupling coordination relationship and spatiotemporal dynamic evolution of the WEFL nexus in the Yangtze River Economic Belt (YREB) from 2006 to 2020. The results indicated that (1) the CBEI and CCD generally increased from 0.23 to 0.79 and 0.45 to 0.88, respectively, revealing the upward trend of the coordination development levels of the WEFL nexus in the YREB. (2) The lower reaches achieved a relatively higher coordination development degree than the upper and middle reaches of the YREB. (3) The findings of obstacle factors reveal that agricultural non-point source pollution control, waterlogging disaster prevention, industrial solid waste efficient treatment, and urban water-saving are the essential fields that need to be improved in YREB's future development. This study helps to understand the complex interrelation of the WEFL nexus at different spatial-temporal scales and provides a novel framework that can be used as an evaluation system and policy insights for a region's integrated resources, environmental management, and green sustainable development.

The emergency supply of transboundary water resources is a prominent problem affecting the social and economic development of basin countries. However, current water supply decisions on transboundary water resources may ignore the psychological perception of multi-stakeholders, and the evolution of emergencies increases the uncertainty of decision making. Both factors would lead to the low acceptance of water-related decisions. Utility satisfaction, perceived losses, and quantity satisfaction were selected in this paper to identify the perceived satisfaction of upstream governments, downstream governments, and the public, respectively, over multiple decision-making stages. A modeling framework combining prospect theory and the multi-stage multi-objective programming methodology was then developed to measure the perceived satisfaction of different stakeholders in a watershed under emergency. A two-stage NSGA-II and TOPSIS based approach was adopted to find the optimal compromise solution to solve the model. The framework was applied in the Lancang–Mekong River basin to provide suggestions to decision makers. Upstream decision makers must choose a moderate proportional fairness degree when making emergency decisions to maximize the perceived satisfaction of all stakeholders. Meanwhile, the perceived loss of downstream countries with low water demand should be considered first in the formulation of emergency water supply plans. Furthermore, although water supply from upstream countries can improve perceived water quantity satisfaction of downstream publics, additional actions must still be taken to change the traditional concepts of the public.

Under the combined effects of climate change and human activities, hydrological changes of large freshwater lakes in complex river–lake systems have attracted worldwide attention, mainly because of the high value of lakes in socio-economic development and environmental conservation. Poyang Lake in the Yangtze River basin of China was used as a case study to investigate the hydrological characteristics and their associated driving forces of influencing lake water level variability. Observed and simulated data and the composite multi-scale sample entropy to measure water level and streamflow complexity were used. The back-propagation neural network, combined with scenario testing analysis, was applied to determine the impact of streamflow and topographic changes on lake water level variability. Study results indicated that the water level complexity of Poyang Lake was higher than the streamflow complexity of the tributaries in the Poyang Lake basin and the main stem of the Yangtze River and that the complexity of both water level and streamflow was enhanced as the time scale increased. Comparing the condition from 2004 to 2016 with that from 1990 to 2002, Poyang Lake experienced a remarkable recession and an enhancement of water level complexity, as a coupling result of the streamflow and topographic changes. Streamflow reductions resulted in a water level drop throughout most of the year, particularly during the flood period. The impact of the deepened bottom topography was marginal during the flood period, but it was significant during the dry period. The strengthened water level complexity could be partially attributed to the deepened bottom topography, which enhanced the disorderliness of drought occurrence, the degree of drought, and the uncertainty in the prediction of drought events. Results from this study shed light on the impact of topographic changes on lake water level complexity and enhanced understanding of the characteristics and mechanisms behind the hydrological changes of large freshwater lakes.

Organic thin-film transistor (OTFT) has attracted considerable research interest in the past decades because of its great potential on flexible electronic applications. So far, there is still a big challenge to integrate high electrical properties and mechanical bending stability in single OTFT via a simple approach. A type of dielectric material possessing excellent flexibility, insulating property, compatibility with multiple organic semiconductors, and easy maneuverability are desirable. In this letter, the OTFT based on polyphenyleneoxide (PPO) dielectric, selected out from 10 different kinds of common polymers, shows invariant high mobility of around 1.5 cm2/Vs even after 5000-times mechanical bending with a small bending radius of merely 4 mm. Whereas the mobilities of OTFTs based on other polymeric dielectrics, such as PS and PMMA, obviously decrease within 100-times bending. Subsequently, flexible oscillators have also been fabricated based on PPO dielectric, which show negligible change on electrical performance after 500-times mechanical bending.

Research question What is the effect of C-type natriuretic peptide (CNP) on human sperm capacitation in vitro and what is the mechanism of this effect? Design CNP/NPR-B expression in the female rat genital tract was examined by immunohistochemistry and western blot assay, and then the role of CNP in human sperm capacitation was determined. The signal transduction pathway of CNP in the process was determined to elucidate the regulation mechanism of CNP by enzyme-linked immunosorbent assay and flow cytometry. Results Both CNP and NPR-B were expressed in the genital tract of female rats, especially in the mucosa epithelium cell of the oviduct; the CNP level in the rat oviduct was higher than that in the cervix. Both CNP and NPR-B level in the rat oviduct varied during the oestrus cycle, maximal expression being observed at proestrus. Furthermore, intracellular cGMP level in spermatozoa was significantly enhanced by CNP (P Conclusions CNP secreted by the female genital tract might bind to NPR-B on the spermatozoa. It successively stimulated intracellular cGMP/PKG signalling, increased Ca2+ and tyrosine-phosphorylated proteins, promoted hyperactivation and induced the acrosome reaction, which ultimately facilitated sperm capacitation.

The Ili-Balkhash Basin in Central Asia is an arid endorheic basin shared by China and Kazakhstan. Population growth, socio-economic development, ecological conservation measures, and climate change have spurred land use and land cover changes and ecosystem services variations. This study used the long-term dataset from 1992 to 2018 to detect the landscape pattern evolution and its association with ecosystem services. The landscape pattern was quantified using landscape metrics, and the GeoDetector model quantified the driving factors of landscape pattern evolution. The ecosystem service value was assessed using the benefit transfer method. The time series trend was identified by the linear regression analysis combined with the Mann-Kendall algorithm, and Pearson's correlation coefficient was used to confirm the correlation. The temporal dynamics of the landscape pattern indicated the significant conversion of bare land to grassland. Cropland and urban land expanded significantly at the expense of forestland, grassland, and bare land. Various landscape elements tended to be more uniformly distributed across the basin with more regular shape and higher aggregation. The ecosystem service value increased significantly, and its correlation with the landscape pattern varied according to land use and land cover (LULC) types. The weakened shape complexity, the strengthened aggregation degree, and the more uniform distribution of different LULC types helped elevate total ecosystem service value. The results advanced the understanding of landscape pattern evolution and provided the scientific reference for land management regarding ecosystem services. Given the watershed ecosystem's integrity, transboundary cooperation between China and Kazakhstan was suggested to reinforce watershed sustainability through integrated watershed land resource planning and the joint adaptive strategies to climate change.

Because of their extremely weak spin-orbit coupling and hence very long spin relaxation time, molecular semiconductors have considered to be very promising materials in spintronics. Since the first observation of spin transport in molecular semiconductors in 2002, molecular spintronics, as an emerging subject for studying spin-correlated phenomenon of electrons in molecular matrix, has attracted considerable research interests in the previous decade. Molecular spin valve is the most prototypical device in molecular spintronic, which should be the best test bed to study spintronic processes in molecules, including spin injection, spinterfacial effect, spin transport, as well as novel spintronic functions. Thus, to achieve highly reproducible molecular spin valves with high performances is of significant importance to the field of molecular spintronics, in which the efficient spin injection-transport process is the necessary precondition. However, according to current studies, there are several unexpected challenges for enhancing spin injection in spin valves, such as top electrode diffusion into molecular layer during device fabrication and the bad energy level alignment between ferromagnetic electrodes and molecules. To get away from these problems and improve device performance, considerable contributions have already been made to enhance spin injection from perspective of creating novel fabrication methods, optimizing device structure as well as various interfacial engineering methods. Besides, the spinterfacial effects at the interface between ferromagnetic electrodes and molecules are also considered to be crucial for spin injection. In latest studies, hybridized interface state (HIS) was proposed to characterize interaction between ferromagnetic electrode and the first molecular layer, and its spin-density of state at Fermi level of ferromagnetic electrode was changed. Therefore, spin polarization was influenced; as well its electronic structure at HIS was rebuilt to affect spin injection. In this review, research advances regarding spin transport mechanisms are also summarized, including tunneling transport and hopping transport separately. According to few recent reports, it is found that the hopping spin transport mode may avail longer spin transport distance especially at room temperature. Moreover, functional spintronic devices, integrated the spin transport and molecular functions (such as optical, electrical or spinterfacial) in one chip, are briefly introduced, which attracted considerable research interest very recently due to the great potential for applications in future. To summarize, the plentiful contributions regarding spintronic device, including performance optimization as well as mechanism study, have greatly facilitated the development of molecular spintronics in the past decade. However, molecular spintronics is an interdisciplinary filed of chemistry, physics and materials, thus exploring novel molecules that are suitable for spintronic applications must be one of the most important issues in future development of molecular spintronics.

The suitable cathode interlayer (CIL) plays a vital role in improving the photovoltaic performances of polymer solar cells, and small-molecule CILs with simple structure and significant modification are believed to have a prospect for commercialization. Herein, we apply the molecular tailoring strategy and synthesize a conjugated small-molecule CIL named SME1, which shows the better reproducibility in different batches than that polymer counterpart and thus ensure the consistent modification effect. It is found that, except for optimizing the molecule/metal contact to decrease the traps, SME1 can also extract electrons from the polymer donor and establish the available n-doping with the non-fullerene acceptor, which are conducive to more efficient exciton dissociation and charge collection in varied non-fullerene systems. By applying SME1 as CIL, one of top power conversion efficiencies of 18.4% (17.9% by the third-party certification) is achieved in PM6:BTP-eC9-based device. In this sense, SME1 can indeed help the emerging photovoltaic materials realize their full potential.

The long spin relaxation time of organic semiconductors up to millisecond level make organic spintronics an emerging and promising field, which has attracted wide range of interests since the birth of the first spin valve. Organic spin valve with sandwich structure is the typical device for spintronic study, and it is generally the vertical structure. During the device fabrication process, the organic semiconductor spacer is easily to be penetrated by top ferromagnetic metal atoms with high energy, and thus causes the formation of ill-defined layer at the interface between the top electrode and organic spacer. The ill-dedfined layer commonly includes filaments or pinholes, which will seriously affect the spin transport performance and spin-related multifunctional exploration. Therefore, reliable organic spin valve charactered by filament- and pinhole-free at the interface is strongly required. So far, a series of reliable spin valve preparation methods have been developed. In this review, following a simply introduction of spin valve, the advances of reliable spin valve preparation methods have been systematically discussed. Subsequently, the assessment approaches of reliable spin valve are presented. Finally, the challenges and perspectives towards the preparation and assessment of reliable spin valve are outlined to clarify the future efforts needed in this area.

Water conservancy projects occupy an extremely important status in human development history. Human cognition about water conservancy projects has been in constant evolution along with the changing relationship between humans and nature (water). Based on a literature review, this study provides a systemic summary of the evolution of the human need for water resources and of water conservancy projects, as well as the equilibrium between humans and nature (river and lake ecosystems). More importantly, the transformation of cognition concerning the governance of nature and river and lake ecosystems is reviewed. Taking the perspective of modern rationalism on water conservancy projects, four major changes in human cognition are identified. Further, the most salient water-related issues arising from China&rsquo, s largest freshwater lake, Poyang Lake, are analyzed and the history and predicament of its governance are described. This is accompanied by a discussion on the countermeasures. Finally, based on the evolution of the human&ndash, water relationship and cognitive transformation concerning water conservancy projects, several suggestions are proposed for the planned construction of the Poyang Lake Hydraulic Project. The conclusions of this paper shed new light on the principles of water governance and water conservancy project construction in a new era that has witnessed a growing conflict between socioeconomic development and the water environment. Our suggestions are also valuable for the governance of Poyang Lake.

The relevant documents and regulations on procedures and contents of transboundary impact assessment issued by the Mekong River Commission are combed. Combining with analysis of existing practice, experience and shortcomings of transboundary impact assessment in hydropower development on the main Mekong River is discussed. The results show that the transboundary impact assessment procedure of the Mekong River Commission is gradually improving. What’s more, the management mode of transboundary impact has gradually changed from paying attention to the prior evaluation to the whole process management. But there is no universal assessment standard for the transboundary impact, and the comprehensive assessment of the transboundary impact caused by hydropower development is lacked.

The histogram comparison approach (HCA) is proposed to assess the alteration of hydrologic regimes, which are characterized by the hydrologic metrics, for example, the indicators of hydrologic alteration. The HCA method considers alterations within the whole range of the hydrologic regime and estimates the alteration degree by comparing the pre-impact and post-impact histograms. A key parameter of the HCA method is the similarity degree, which considers both the class-by-class and cross-class information of histograms and reflects how many features of the pre-impact histogram remain in the post-impact histogram. The alteration degree is defined as the mathematical maximum similarity degree, that is, 100%, subtracted by the actual similarity degree in the HCA method. Comparing the HCA method to the existing range of variability approach and histogram matching approach through theoretical analysis and case studies, the HCA method can eliminate some limitations of the range of variability approach and histogram matching approach methods and can more accurately and effectively assess the hydrologic regime alteration. The Ob and Yangtze Rivers, which are located in different climatic zones, are used as case studies. Hydrologic regime alterations impacted by reservoirs with different regulation abilities (daily, seasonally and yearly) were assessed using the HCA method, the results of which verified its rationality and practicability. More sites with a wider range of flow variations will be examined in the future to assess the applicability of the HCA method. Copyright © 2017 John Wiley & Sons, Ltd.

Impacted by ongoing climate change and anthropogenic activities, large seasonal lakes experience water regime evolution, which raises challenges for the management of water resources and environment. The water regime evolution refers to the spatial and temporal alterations in the hydrological features of lakes. Characterizing the lake water regime and its alteration may help policymakers design effective adaption strategies. Therefore, total 47 hydrological indicators were proposed, considering intra-annual fluctuations, flood and drought features, and rate and frequency of water level variations. Combined with Mann-Kendall algorithm and Sen&rsquo, s slope, the indicators were applied in Poyang Lake, a typically large seasonal lake in China, as a case study. The results revealed temporal and spatial variations in different hydrological indicators. The most dramatic alteration was the water level decline in October and November over the entire study phase, especially over the past 30 years. This was an urgent environmental problem that Poyang Lake faced, partially caused by the increased hydraulic gradient between southern and northern lake. It could trigger the drought occurring earlier, prolong the drought duration, and impair the wetland ecosystem. Environmental water requirements of both Poyang Lake and Yangtze River were suggested for regional sustainable development. The application in Poyang Lake showed the practicability and reliability of the indicators, which are applicable in international seasonal lakes. The series of indicators can be used in whole or in part, determined by the ecohydrological characters of a specific lake and the research objectives.

The field of spintronics has triggered an enormous revolution in information storage since the first observation of giant magnetoresistance (GMR). Molecular semiconductors are characterized by having very long spin relaxation times up to milliseconds, and are thus widely considered to hold immense potential for spintronic applications. Along with the development of molecular spintronics, it is clear that the study of multipurpose spintronic devices has gradually grown into a new research and development direction. The abundant photoelectric properties of molecular semiconductors and the intriguing functionality of the spinterface, together with novel designs of device structures, have promoted the integration of multiple functions and different mechanisms into discrete spintronic devices. Here, according to the different relationships between the integrated mechanisms, multifunctional molecular spintronic devices containing parallel and interactive types are highlighted. This is followed by the introduction of pure-spin-current-type molecular spintronic devices that have already demonstrated great potential for multifunction exploration. Finally, the challenges and outlook that make this field young and energetic are outlined.

Hydrologic regimes are essential to riverine, lacustrine, and wetland ecosystems, and every component of a hydrologic regime has a specific ecological environmental function. In an outflow lake-river system, water levels are reduced by a reservoir constructed at the river, which interferes with the river-lake interrelationships by impairing the river’s blocking effect. This increases the lake-river hydraulic gradient and accelerates the lake’s drainage to the river, resulting in shrinkage of the lake and damaging environmental issues. To respond to these issues, we propose an environmental flow assessment that considers the river’s blocking effect on the lake. This novel methodology consists of four steps: data preparation, assessment of the lake’s environmental water level, assessment of the river’s environmental water level, and environmental flow assessment. We estimated the river’s environmental water level through a hydraulic correlation between the lake and the river, and found that the river’s blocking effect could be sustained. The Yangtze-Poyang system was selected as a case study to illustrate the methodology’s procedures and applicability. The impoundment of the Three Gorges Reservoir, during the fall retreating season, decreased the Yangtze’s water level and weakened the Yangtze’s blocking effect on Poyang Lake. Poyang Lake’s environmental water level, which ranges from 11.71 to 15.81 m in the month of October, was used to estimate the Yangtze’s environmental water level as falling in a range of 11.95 to 16.17 m, which corresponds to an environmental flow range of 16,822 to 32,371 m3/s. This study offers a solution for reservoir-induced accelerated lake drainage, which may be helpful in mitigating the negative impacts of reservoirs and sustaining natural rive-lake interactions.

What is the effect of C-type natriuretic peptide (CNP) on human sperm capacitation in vitro and what is the mechanism of this effect?CNP/NPR-B expression in the female rat genital tract was examined by immunohistochemistry and western blot assay, and then the role of CNP in human sperm capacitation was determined. The signal transduction pathway of CNP in the process was determined to elucidate the regulation mechanism of CNP by enzyme-linked immunosorbent assay and flow cytometry.Both CNP and NPR-B were expressed in the genital tract of female rats, especially in the mucosa epithelium cell of the oviduct; the CNP level in the rat oviduct was higher than that in the cervix. Both CNP and NPR-B level in the rat oviduct varied during the oestrus cycle, maximal expression being observed at proestrus. Furthermore, intracellular cGMP level in spermatozoa was significantly enhanced by CNP (P 0.01). PKG activity was detected in the spermatozoa, and it can be activated by the CNP and 8-Br-cGMP (cGMP analogue). The PKG inhibitor KT5823 inhibited the effect of CNP on sperm hyperactivation and the acrosome reaction. Finally, CaCNP secreted by the female genital tract might bind to NPR-B on the spermatozoa. It successively stimulated intracellular cGMP/PKG signalling, increased Ca

Hydrological parameters are significant both in hydrological events and ecological conservation. The implications of hydrological statistical parameters in river ecology were investigated by considering three basic parameters, as follows: (1) mean value, (2) coefficient of variation, and (3) extreme ratio. Four typical rivers selected as case studies include the Yellow and Yiluo Rivers in north China, and the Yangtze and Oujiang Rivers in south China. Hydrological statistical parameters were calculated using monthly flow data collected from the key hydrometric stations on each of the four rivers. The results revealed that the three hydrological statistical parameters are all crucial ecological indicators that reflect the ecological conditions of river ecosystems. The mean value of the flow may be the key determinant of habitat range and aquatic biomass. The coefficient of variation may reflect the stability or vulnerability of the ecological conditions of rivers, and the extreme ratio may reflect ...

This study analyzed the long-term trends and variations of temperature and precipitation on annual timescale in the Ili-Balkhash Basin (IBB), Kazakhstan. Some statistical tools were employed to detect any climate variations at four stations in the IBB during the period between 1936 and 2005. These methods included the Mann–Kendall trend test, the Theil–Sen approach, and the sequential Mann–Kendall test. The results showed that in temporal scale, the climate in the IBB has been becoming warmer and wetter in the past several decades as a whole. The annual mean temperature and the annual precipitation in the IBB showed an increasing trend since the 1970s and the 1940s, respectively. The significance of the annual mean temperature and annual precipitation trends in the IBB was tested at >95 % confidence level. The slope of the increasing trend of annual mean temperature ranges from 0.019 to 0.029 °C/year, and that of the annual precipitation ranges from 0.654 to 2.179 mm/year. In spatial scale, the multiyear mean values of temperature and precipitation are greater in the southern mountain region than those in the northern plain and hilly land area of the basin. The multiyear mean temperature decreases with the increasing latitudes, while increases with the increasing altitudes except for Karaganda; the multiyear mean precipitation increase with the increasing altitudes, while decreases centered with the Lake Balkhash from the surrounding area. The results may provide climatic backgrounds for solving the problems related to water sources of the IBB.

Central Asia is one of the regions that suffer the most prominent transboundary water and energy problems in the world. Effective transboundary water-energy resource management and cooperation are closely related with socioeconomic development and stability in the entire Central Asia. Similar to Central Asia, Northwest China has an arid climate and is experiencing a water shortage. It is now facing imbalanced supply—demand relations of water and energy resources. These issues in Northwest China and Central Asia pose severe challenges in the implementation of the Silk Road Economic Belt strategy. Based on the analysis of water and energy distribution characteristics in Central Asia as well as demand characteristics of different countries, the complexity of local transboundary water problems was explored by reviewing corresponding historical problems of involved countries, correlated energy issues, and the evolution of inter-country water-energy cooperation. With references to experiences and lessons of five countries, contradictions, opportunities, challenges and strategies for transboundary water-energy cooperation between China and Central Asia were discussed under the promotion of the Silk Road Economic Belt construction based on current cooperation conditions.

This paper investigates hydrologic changes in the Yangtze River using long-term daily stream flow records (1955–2013) collected from four flow gauging stations located from the upper to the lower reaches of the river. The hydrologic regime is quantified using the Indicators of Hydrologic Alteration, which statistically characterize hydrologic variation within each year. Scanning t-test is applied to analyze multiple changes in the hydrologic regime at different time scales. Then, coherency analysis is applied to identify common changes among different hydrologic indicators and across different reaches of the Yangtze River. The results point to various change patterns in the five components of hydrologic regime, including the magnitude of monthly water conditions, magnitude and duration of annual extreme water conditions, timing of annual extreme water conditions, frequency and duration of high and low pulses, and rate and frequency of water condition changes. The 32 hydrologic indicators feature multiple temporal-scale changes. Spatial variations can be observed in the hydrologic changes of the upper, middle, and lower reaches of the river. Common changes in different reaches consist of hydrologic indicators including the monthly flow in October and the low-flow indicators. The monthly flow in October is dominated by decreasing trends, while the monthly flows between January and March, the annual minimum 1/3/7/30/90-day flows, and the base flow index are characterized by increasing trends. Low pulse duration and total days of low pulses feature downward trends. The coherency analysis reveals significant relationships between the monthly flow in October and the low-flow indicators, indicating that reservoir regulation is an important factor behind the hydrologic changes.

As the largest tributary of the Ob River, the Irtysh River is an international river partially joining the territories of China, Kazakhstan, and Russia. Four meteorological stations in the Irtysh Basin were selected and the long-term observed daily temperature data were collected. The extreme temperature change was analyzed considering climate change. Detected by the heuristic segmentation by histogram comparison approach, climate was changed during the first half of the 1970s in terms of the increased mean value and decreased standard deviation of the daily temperature series. The noticeable change of the monthly mean temperature was the warmer winter. After climate change, the annual maximum temperature was little changed and its series was not segmented. However, the annual minimum temperature was significantly changed in terms of the increased mean value by more than 2°C, so its series was segmented to the pre- and post-change point subseries. The generalized extreme value distribution was fitted to the annual extreme temperature and the parameters were estimated by the maximum likelihood method. The return levels for 10/50/100-year return periods estimated by the profile likelihood method were obtained for the annual extreme temperature. The probability of occurrence of the cold extremes was decreased after 1970s.

Instream ecological flow is essential determinant of river health. In this paper, the monthly minimum flow calculation method, the (new) monthly frequency calculation method were applied to calculate and evaluate the minimum instream ecological flow and the optimal instream ecological flow for the Irtysh River, and the different criteria of instream ecological flow was calculated by the improved Tennant method. It is expected to provide a scientific basis for the reasonable allocation of water resource in Irtysh River basin by calculating the instream ecological flow.

Oujiang River was selected as the case study, and a dataset of daily flow series at Xuren Station was used to explore the hydrologic characteristics of rivers in humid areas, by using the ‘Indicators of Hydrologic Alteration’ approach and ‘Range of Variability Approach’. Results showed that the overall alteration of the hydrological regime for Oujiang River belonged to the low alteration category, and some key eco-hydrological characteristics should be protected in certain key periods to maintain the integrality and health status of river ecosystems.

This paper proposes a traffic-flow evolutionary model under a dual updating mechanism that describes the day-to-day (DTD) dynamics of traffic flow and travel cost. To illustrate the concept, a simple two-route network is considered. Based on the nonlinear dynamic theory, the equilibrium stability condition of the system is derived and the condition for the division between the bifurcation and chaotic states of the system is determined. The characteristics of the DTD dynamic evolution of network traffic flow are investigated using numerical experiments. The results show that the system is absolutely stable when the sensitivity of travelers toward the route cost parameter (&theta, ) is equal to or less than 0.923. The bifurcation appears in the system when &theta, is larger than 0.923. For values of &theta, equal to or larger than 4.402, the chaos appears in the evolution of the system. The results also show that with the appearance of chaos, the boundary and interior crises begin to appear in the system when &theta, is larger than 6.773 and 10.403, respectively. The evolution of network traffic flow is always stable when the proportion of travelers who do not change the route is 84% or greater.