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Return period estimation plays an important role in the engineering practices of water resources and disaster management, but uncertainties accompany the calculation process. Based on the daily discharge records at two gauging stations (Cuntan and Pingshan) on the upper Yangtze River, three sampling methods (SMs; (annual maximum, peak over threshold, and decadal peak over threshold), five distribution functions (DFs; gamma, Gumbel, lognormal, Pearson III, and general extreme value), and three parameterization methods (PMs; maximum likelihood, L-Moment, and method of moment) were applied to analyze the uncertainties in return period estimation. The estimated return levels based on the different approaches were found to differ considerably at each station. The range of discharge for a 20-year return period was 63,800.8-74,024.1 m3 s-1 for Cuntan and 23,097.8-25,595.3 m3 s-1 for Pingshan, when using the 45 combinations of SMs, DFs, and PMs. For a 1000-year event, the estimated discharge ranges increased to 74,492.5-125,658.0 and 27,339.2-41,718.1 m3 s-1 for Cuntan and Pingshan, respectively. Application of the analysis of variance method showed that the total sum of the squares of the estimated return levels increased with the widening of the return periods, suggestive of increased uncertainties. However, the contributions of the different sources to the uncertainties were different. For Cuntan, where the discharge changed significantly, the SM appeared to be the largest source of uncertainty. For Pingshan, where the discharge series remained almost stable, the DF contributed most to the uncertainty. Therefore, multiple uncertainty sources in estimating return periods should be considered to meet the demands of different planning purposes. The research results also suggest that uncertainties of return level estimation could be reduced if an optimized DF were used, or if the decadal peak over threshold SM were used, which is capable of representing temporal changes of hydrological series. [ABSTRACT FROM AUTHOR]

In recent years, different space agencies have launched satellite missions that carry passive microwave instruments on-board that can measure surface soil moisture. Three currently operational missions are the Soil Moisture and Ocean Salinity (SMOS) mission developed by the European Space Agency (ESA), the Advanced Microwave Scanning Radiometer 2 (AMSR2) developed by the Japan Aerospace Exploration Agency (JAXA), and the Microwave Radiation Imager (MWRI) from China's National Satellite Meteorological Centre (NSMC). In this study, the quality of surface soil moisture anomalies derived from these passive microwave instruments was sequentially assessed over the mainland of the People's Republic of China. First, the impact of a recent update in the Land Parameter Retrieval Model (LPRM) was assessed for MWRI observations. Then, the soil moisture measurements retrieved from the X-band observations of MWRI were compared with those of AMSR2, followed by an internal comparison of the multiple frequencies of AMSR2. Finally, SMOS retrievals from two different algorithms were also included in the comparison. For each sequential step, processing and verification chains were specifically designed to isolate the impact of algorithm (version), observation frequency or instrument characteristics. Two verification techniques are used: the statistical Triple Collocation technique is used as the primary verification tool, while the precipitation-based Rvalue technique is used to confirm key results. Our results indicate a consistently better performance throughout the entire study area after the implementation of an update of the LPRM.We also find that passive microwave observations in the AMSR2 C-band frequency (6.9 GHz) have an advantage over the AMSR2 X-band frequency (10.7 GHz) over moderate to densely vegetated regions. This finding is in line with theoretical expectations as emitted soil radiation will become masked under a dense canopy with stricter thresholds for higher passive microwave frequencies. Both AMSR2 and MWRI make X-band observations; a direct comparison between them reveals a consistently higher quality obtained by AMSR2, specifically over semi-arid climate regimes. Unfortunately, Radio Frequency Interference hampers the usefulness of soil moisture products for the SMOS L-band mission, leading to a significantly reduced revisit time over the densely populated eastern part of the country. Nevertheless, our analysis demonstrates that soil moisture products from a number of multi-frequency microwave sensors are credible alternatives for this dedicated L-band mission over the mainland of the People's Republic of China. [ABSTRACT FROM AUTHOR]

By using a coupled land surface-atmosphere model with initial conditions of varying resolution and ensembles of systematically changed soil moisture, convective-scale simulations of a typical frontal rainstorm in the Yangtze River Basin are collected to investigate: (1) effects of different datasets on the simulated frontal mesoscale convective systems (MCSs); (2) possible linkages between soil moisture, planetary boundary layer (PBL), MCSs and precipitation in this modeled rainstorm. Firstly, initial soil moisture differences can affect the PBL, MCSs and precipitation of this frontal rainstorm. Specially, for a 90 mm precipitation forecast, the Threat score (TS) can increase 6.61% by using the Global Land Data Assimilation System (GLDAS) soil moisture. Secondly, sensitivity experiment results show that the near-surface thermodynamic conditions are more sensitive to dry soil than wet due to the initial moist surface; atmosphere conditions have suppressed the relations between soil and atmosphere; and decreased precipitation can be found over both wet and dry surfaces. Generally, a positive feedback between soil moisture and the near-surface thermodynamic conditions is identified, while the relations between soil moisture and precipitation are quite complicated. This relationship shows a daytime mixing of warm surface soil over dry surfaces and a daytime evaporation of adequate moisture over wet surfaces. The large-scale forcing can affect these relations and finally cause decreased precipitation over both wet and dry surfaces. [ABSTRACT FROM AUTHOR]

Here we report on the apparent reduction in surface chirality upon co-assembling a chiral and achiral molecule into a physisorbed self-assembled monolayer at the liquid/solid interface as revealed by scanning tunneling microscopy (STM). Chiral OPV with achiral thymine gives rise to surface-confined supramolecular diastereomers. [ABSTRACT FROM AUTHOR]

A new water-soluble fluorescent conjugated polyelectrolyte, poly[9,9-bis(3′-butyrate)fluoren-2,7-yl] sodium (BBS-PF), was studied as a fluorescent probe for protein sensing. The conjugated polyelectrolyte BBS-PF shows high fluorescence sensitivity to cytochrome c, lysozyme, and bovine serum albumin (BSA). The Stern-Volmer constant ( K) in cytochrome c was measured to be as high as 6.1 × 10 L/mol, approximately twice as that of the other two. Interestingly, it is found that BSA slightly enhances the fluorescence of BBS-PF rather than quenches the fluorescence at its micromolar concentrations. The excitation spectra confirm that the interaction of BBS-PF with the proteins could be different. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Hydrogels composed of hyperbranched poly(amine-ester) (HPAE) macromers with 36% of terminal CC groups were prepared as a pH-sensitive multi-drug release system with low swelling ratios (4.2% for the lowest one). Anticancer drugs including doxorubicin hydrochloride (Dox), 5-fluorouracil (5FU) and hydroxycamptothecin (HPT) were separately encapsulated in HPAE macromers before hydrogel formation and their release can be controlled by the conformational change of HPAE macromers under different pH conditions, fast when pH > 7 and slow when pH < 7. Furthermore, this system allows a combination release of multiple drugs and the release behavior of each drug was relatively independent with no interference from each other. This is different from traditional pH-sensitive hydrogel systems which control the drug release by a swelling-shrinking mechanism. HPAE hydrogels exhibited pH-controllable drug release properties with a relatively constant volume, because the swelling of hydrogel is limited due to the unique globe like structure of HPAE molecules. These findings show the great promise of HPAE hydrogels as a smart release system for controlled delivery of single or multiple drugs in combined therapy, and where a constant volume of the release system is required. [ABSTRACT FROM AUTHOR]

This work describes a comprehensive study of hydrogels based on polyethylene glycol diacrylates (PEGDAs) with the molecular weight (MW) range of 400-2000. The blends of low- and high-molecular weight PEGDA macromers with different ratios were photopolymerized under visible light irradiation, using a blue light sensitive photoinitiator Irgacure819, at the total polymer concentration of 60 wt %. Swelling ratios, wetting property, elastic moduli, transparency, and the microstructure of the resulting hydrogels were investigated. Among them, equilibrium water contents, hydrophilicity, and mesh size of the hydrogels increased while the elastic moduli decreased when increased the PEGDA MW or the content of higher MW PEGDA in the blends. Most of the hydrogels possessed excellent transparency in visible region. The viability of L929 cells on the surface of hydrogel was also estimated. All the selected hydrogels exhibited a relatively high proliferation rate, which demonstrated this hydrogel system with photoinitiator Irgacure819 had good biocompatibility. These results show the properties of PEGDA hydrogel could be easily adjusted by varying PEGDA MW or the ratios of low- and high-MW macromers in the composites. It could be helpful for the design of proper PEGDA hydrogels in the applications as tissue engineering or drug delivery system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

The synthesis and characterization of a shape-persistent triphenylene–butadiynylene macrocycle formed by intermolecular Glaser-coupling of two “half-rings” and also by intramolecular coupling of the appropriate open dimer, respectively, are described in detail. The investigation of the photophysics has revealed that—compared to its open dimer—the macrocycle is more conjugated in the ground state and less so in the excited state, a result of the diacetylene bending in the macrocycle due to its constrained topology. The macrocycle is decorated with flexible side groups that support its adsorption on highly oriented pyrolytic graphite (HOPG) where a concentration-dependence of the 2D-structure is observed by means of scanning tunnelling microscopy (STM). The flexible side groups also guarantee a high compound solubility even in nonpolar solvents (cyclohexane). However, solvophobic interactions lead to the formation of a tube-like superstructure, as revealed by dynamic light scattering, X-ray scattering and atomic force microscopy. [ABSTRACT FROM AUTHOR]

Soil moisture variability is analysed in the re-analysis data ERA-40 of the European Centre for Medium-Range Weather Forecasts (ECMWF) which includes four layers within 189 cm depth. Short-term correlations are characterised by an e-folding time scale assuming an exponential decay, whilst long-term memory is described by power law decays with exponents determined by detrended fluctuation analysis. On a global scale, the short-term variability varies congruently with long-term memory in the surface layer. Key climatic regions (Europe, Amazon and Sahara) reveal that soil moisture time series are non-stationary in arid regions and in deep layers within the time horizon of ERA-40. The physical processes leading to soil moisture variability are linear according to an analysis of volatility (the absolute differences), which is substantiated by surrogate data analysis preserving the long-term memory. [ABSTRACT FROM AUTHOR]

The article discusses a study on the use of thiol-ene photopolymerization in injectable intraocular lenses (IOLs). It mentions that poly(ethylene glycol) diacrylate (PEGDA) and pentaerythritol tetrakis(3-mercaptopropionate) (PTMP) samples have similar hydrophilicity and transparency from PEGDA by homophotopolymerization. Results suggest that thiol-ene photopolymerization is a potential method in obtaining ideal injectable IOLs.

The article discusses a study of the power law correlation properties of sign and magnitude series based on a series of observation records of flow of the River Yangtze in China. The results gave insights on the linear and nonlinear processes of the water cycle. The documented linkage between the sign series and the linear process can be verified with the delayed vector variance method and the surrogate test. The spectra estimated by detrended fluctuation analysis method show different properties of correlations in both sign and magnitude series.

A photo- and pH-responsive electrospun polymer film composed of a carboxy-azobenzene polymer (PAZO) and polystyrene (PS) has been fabricated. The wettability can be switched in response to pH variation and UV light irradiation. The controlled adsorption of protein, bovine serum albumin (BSA), on the electrospun films can be achieved under UV light irradiation. [ABSTRACT FROM AUTHOR]

The interactions of hen egg lysozyme (HEL) and bovine serum albumin (BSA) with an azobenzene polymer (P(AZO-co-AA)) were investigated by fluorescence spectroscopy. The azobenzene chromophore could strongly quench the intrinsic fluorescence of the proteins through the Förster resonance energy transfer (FRET) and the quenching effect was dependent on the pH values since the polymer also contained pH-sensitive carboxylic groups. The fluorescence quenching by azobenzene shows great potential applications in protein sensing. [ABSTRACT FROM AUTHOR]

During recent decades, Burundi was threatened by recurrent dry events resulting in crop failure and more socio-economic losses. To assess the drought occurrence, duration and intensity, this study used the Standardized Precipitation Index (SPI) at 3-, 6- and 12-month time scales for the period 1981–2017. The Mann Kendall and Modified Mann Kendall trend tests and Sen's slope statistic test were used to analyse the spatiotemporal drought trend. The overall analysis of SPI-3, SPI-6 and SPI-12 results revealed that the northern part of Burundi was the most threatened by dry events, where more than 80% of the extremely and severely dry events occurred within the period 1993–2000. The drought magnitude highly varied during the short rains season (SOND) specifically during the 1990s decade. The cumulative frequency of extremely dry events was very high in the North with 5.2%, 6.1% and 7.4% at 3-, 6- and 12-month time scales respectively. Likewise, the northern part experienced short, medium and long dry periods, thus 88 consecutive dry months within only 8 years. The North and East regions exhibited a positive increasing trend over annual and seasonal time scales at 3, 6 and 12 months while the mountainous region and the South experienced a significant decreasing trend. Investigation of teleconnection factors showed that dry events are associated with sea surface temperature anomalies over the Indian Ocean resulting in the weakening of southeasterly winds during the negative phase of Indian Ocean Dipole and La Nina years. [ABSTRACT FROM AUTHOR]

To achieve the double carbon goal of “carbon peaking and carbon neutrality”, the construction of the power system which is based on the green energy needs to be accelerated. With the growth of the system scale, the distributed green energy carbon trading mechanism and the carbon data management technology based on the blockchain technology can effectively encourage the development of green energy and become effective means for the implementation of low-carbon electricity. The accurate and real-time carbon emission calculation will further provide data support for the accuracy and security of carbon trading information. First, the current research status of green certificate trading and carbon asset management is introduced. Next, the adaptability analysis of the key technologies of the blockchain technology in the four directions of green electricity traceability, green certificate trading, carbon trading, and joint market of green certificate and carbon assets is performed. Afterwords, the specific mathematical models of carbon emission calculation is studied, and the data availability of carbon source traceability methods applicable to the blockchain architecture are discussed. Finally, some suggestions for the future development of carbon emission flow analysis are proposed.