Polymer Water Research Articles

Impacts of late-spring North Eurasian soil moisture variation on summer rainfall anomalies in Northern East Asia

This paper reports findings from a diagnostic and modeling analysis that investigates the impacts of the boreal late-spring soil moisture anomalies over North Eurasia on the summer rainfall over northern East Asia (NEA). The soil moisture in May from the Kara-Laptev Sea coasts to Central Siberian Plateau is found to be negatively correlated with the summer rainfall from Mongolia to Northeast China. The atmospheric circulation anomalies associated with the anomalously dry soil are characterized by a pressure dipole with the high-pressure center located over North Eurasia and low-pressure center over NEA, where an anomalous water vapor convergence occurs, favoring rainfall formation. Diagnoses and modeling experiments demonstrate that the effects of the spring lower soil moisture over North Eurasia may persist into the following summer, then increase the low-level air temperature at higher latitudes through modulating local surface latent and sensible heat fluxes, and effectively reduce the meridional temperature gradient north of NEA. The weakened temperature gradient could induce the decreased vertical shear of zonal wind and generate an anomalously cyclonic center over NEA by affecting the baroclinicity around 60° N, associated with a favorable condition of local synoptic activity to increase rainfall. The above relationships and mechanisms are vice versa for the prior wetter North Eurasian soil and decreased NEA rainfall. These findings suggest that the soil moisture anomalies at higher latitudes may act as a new precursor providing an additional predictability source for better predicting the summer rainfall in NEA.

The 2019 Autumn Hot Drought Over the Middle‐Lower Reaches of the Yangtze River in China: Early Propagation, Process Evolution, and Concurrence

AbstractHot droughts (i.e., concurrent droughts and hot anomalies) have drawn much attention recently, but current knowledge about early propagation and concurrence remains limited. The 2019 autumn severe hot drought (2019AHD) over the middle‐lower reaches of the Yangtze River (MLYR) is employed for process‐based analysis, while water vapor transport, heating budgets, and atmospheric dynamics are comprehensively investigated. The main achievements are as follows: (a) The 2019AHD over MLYR is not isolated and is related to early propagation from adjacent North China (NC) two months earlier. (b) Direct physical causes are explored. Drought evolution is related to anomalous water vapor transport dominated by low‐level cyclonic anomalies over the East China Sea. Concurrently, local low‐level hot anomalies over MLYR are related to amplified horizontal advection heating, while near‐surface warming is favored by decreased low cloud cover and enhanced downward shortwave radiation. (c) Regional‐scale concurrence of droughts and hot extremes might be understood by the combined effects of amplified subsidence (suppressing precipitation formation) and intensified low‐level divergence (reducing low cloud cover). (d) From a large‐scale dynamic perspective, early propagation and development of the 2019AHD are related to the southward shift and enhancement of the subsidence branch of meridional circulations. Meanwhile, intensity variation in 200 hPa cyclonic anomalies over MLYR corresponds well with local drought development, and the enhanced intensity at the time of drought occurrence is probably related to Silk Road Pattern–like wave train propagation over Eurasia. These insights can help us understand the mechanisms and detect early signals of hot droughts.

Concurrent Enhancement of Conductivity and Stability in Water of Poly(3,4‐Ethylenedioxythiophene):Poly(Styrenesulfonate) Films Using an Oxetane Additive

AbstractPoly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is the most used conducting polymer in organic electronics and bioelectronics owing to its high conductivity combined with high optical transparency and availability as a stable colloidal aqueous dispersion, that can be processed as a conducting ink to produce thin and flexible films and electrodes. In this work, water‐resistant films of PEDOT:PSS showing enhanced conductivity are prepared by solely adding one reagent, 3‐methyl‐3‐oxetanemethanol, to PEDOT:PSS aqueous dispersions. The stability of the resultant thin films in water is attributed to the covalent cross‐linking of benzene rings anchored in PSS chains to polyether chains originated from the polymerization of oxetane groups, as indicated by NMR studies. A phase‐segregation within the PEDOT:cross‐linked PSS film is suggested to facilitate charge transport within the PEDOT network and to be at the origin of the improved conductivity. When immersed in water, the films exhibit increased water‐resistance towards resuspension and delamination and exhibit an increase of conductivity, by two to three orders of magnitude, depending on the used raw PEDOT:PSS formulation. The method described in this work is advantageous in originating water‐stable and highly conducting thin films of PEDOT:PSS as it does not involve high temperatures nor strong acids.

Dominant Modes of Interannual Variability in Atmospheric Water Vapor Content over East Asia during Winter and Their Associated Mechanisms

Atmospheric water vapor content (WVC) is a critical factor for East Asian winter precipitation. This study investigates the dominant modes of interannual variability in WVC over East Asia during winter and the underlying mechanisms. Based on the empirical orthogonal function (EOF) method, the leading mode (EOF1, R2=28.9%) of the interannual variability in the East Asian winter WVC exhibits a meridional dipole pattern characterized by opposite WVC anomalies over northeastern China and eastern China; the second mode (EOF2, R2=24.3%) of the interannual variability in the East Asian winter WVC exhibits a monopole pattern characterized by consistent WVC anomalies over eastern China. EOF1 is mainly modulated by two anomalous zonal water vapor transport (WVT) branches over northeastern China and eastern China, which are associated with an anomalous atmospheric wave train over Eurasia affected by sea ice cover in the Kara Sea-Barents Sea (SIC-KSBS) area in the preceding October-November (ON). EOF2 is mainly modulated by an anomalous westerly WVT branch over eastern China, which is associated with a circumglobal atmospheric zonal wave train in the Northern Hemisphere. This circumglobal zonal wave train is modulated by concurrent central and eastern tropical Pacific sea surface temperature anomalies. The SIC-KSBS anomalies in ON and the concurrent SST anomalies over tropical Pacific may partially account for the interannual variability of EOF1 and EOF2 in winter WVC, thus may providing a theoretical basis for improving the prediction of winter climate over East Asia.

Water absorption and hydrothermal ageing of epoxy adhesives reinforced with amino-functionalized graphene oxide nanoparticles

The study is focused on quantitative characterization of water absorption and hydrothermal ageing effects in a room-temperature amine cured epoxy adhesive widely used in automotive, aerospace, construction, and marine industries. Amino-functionalized graphene oxide (mGO) nanoparticles were incorporated into the epoxy (up to 1.72 wt.%) enabled cross-linking reactions and providing high interfacial adhesion, superior reinforcement efficiency and enhanced resistance to hydrothermal ageing of nanocomposites. Anomalous water absorption accompanied by progressive weight loss of samples (down to 7%) is fitted by two-stage models considering additive and coupled contribution from water diffusion and leaching of low molecular weight epoxy species. Nanocomposites are characterized by lower water diffusivity (40%) and decreased leaching effects (70%). High reinforcing efficiency of epoxy/mGO appeared in the increased glassy and rubbery storage moduli (60%), glass transition temperature (10 °C) and activation energy of glass transition (70%) compared to the neat epoxy. Hydrothermal ageing resulted in noticeable properties degradation of samples, although to a much lower extent in the case of nanocomposites. The results will contribute to the enhancement of global durability of common epoxy-based adhesives and extension of their lifetime.

Using CANARY event detection software for water quality analysis in the Milwaukee River

Urban water sources are susceptible to various contamination events as a result of natural, accidental, and human-induced occurrences. An early warning monitoring system provides timely information on changes in urban water quality. In this study, an analysis was made with CANARY event detection software (EDS) to monitor water quality parameters in river water and to identify the onset of anomalous water quality periods. Water quality signals including pH, conductivity, and turbidity from the Milwaukee River over specified periods during the summer season of 2018–2020 were employed as inputs to event detection algorithms in CANARY. The data analysis results show that CANARY can be useful as an early warning system for monitoring contamination in urban water sources and help to identify abnormal conditions quickly. The sensibility of the model relies on optimizing the configuration parameters, which involves selecting the ideal set of parameters for the event detection algorithm and adjusting the BED parameters to increase or decrease the probability of generating an alarm. The number of events reported between the Linear Prediction Correction Filter (LPCF) and Multivariate Nearest Neighbor (MVNN) algorithms varied as a result of different residual calculation mechanisms. Climate factors that contributed to the abnormal water quality events in the river were examined. The analysis of rainfall on water quality was carried out using a statistical method by determining whether there is a significant difference (p-value) between the seasonal mean water quality data and the mean value of water parameters during the sampling duration. Regression analysis was also performed to estimate the best model that describes the relationship between each of the water quality parameters and temperature.

Seasonal, Interannual, and Interdecadal Variations of the East Asian Summer Monsoon: A Diurnal-Cycle Perspective

AbstractThis study revisits the long-term variabilities of the East Asian summer monsoon (EASM) in 1958–2017 through examination of diurnal cycles. We group monsoon days into four dynamic quadrants (Q1 to Q4), with emphasis on the strong daily southerlies coupled with a large (Q1) or small (Q4) diurnal amplitude over Southeast China. The occurrence day of Q1 increases in June–July with the seasonal progress of the EASM. It is most pronounced in the 1960s to the 1970s and declines to the lowest in the 1980s to the 1990s, whereas the Q4 occurrence increases notably from the 1970s to the 1990s; both groups return to normal in recent years. The interdecadal decrease (increase) of Q1 (Q4) occurrence corresponds well to the known weakening of EASM in the twentieth century, and it also coincides with the rainfall anomalies over China shifting from a “north flooding and south drought” to a “north drought and south flooding” mode. The rainfall under Q1 (Q4) can account for ~60% of the interannual variance of summer rainfall in northern (southern) China. The contrasting effects of Q1 and Q4 on rainfall are due to their remarkably different regulation on water vapor transport and convergence. The interannual/interdecadal variations of Q1 (Q4) occurrence determine the anomalous water vapor transports to northern (southern) China, in association with the various expansion of the western Pacific subtropical high. In particular, Q1 conditions can greatly intensify nighttime moisture convergence, which is responsible for the long-term variations of rainfall in northern China. The results highlight that the diurnal cycles in monsoon flow act as a key regional process working with large-scale circulation to regulate the spatial distributions and long-term variabilities of EASM rainfall.

Lagged recovery of fish spatial distributions following a cold-water perturbation

Anomalous local temperature and extreme events (e.g. heat-waves) can cause rapid change and gradual recovery of local environmental conditions. However, few studies have tested whether species distribution can recover following returning environmental conditions. Here, we tested for change and recovery of the spatial distributions of two flatfish populations, American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea), in response to consecutive decreasing and increasing water temperature on the Grand Bank off Newfoundland, Canada from 1985 to 2018. Using a Vector Autoregressive Spatiotemporal model, we found the distributions of both species shifted southwards following a period when anomalous cold water covered the northern sections of the Grand Bank. After accounting for density-dependent effects, we observed that yellowtail flounder re-distributed northwards when water temperature returned and exceeded levels recorded before the cold period, while the spatial distribution of American plaice has not recovered. Our study demonstrates nonlinear effects of an environmental factor on species distribution, implying the possibility of irreversible (or hard-to-reverse) changes of species distribution following a rapid change and gradual recovery of environmental conditions.

Influences of thermal damage on water transport in heat-treated cement mortar: Experimental and theoretical analyses

Water transport in the heat-damaged cement mortar is closely related to the evaluation of durability for structures exposed to fire and the recycling of thermally damaged cement-based materials. In this study, the influence of microstructure on water transport in unsaturated and saturated heat-treated cement mortar was analyzed based on experimental results from neutron radiography, water permeability, mercury intrusion porosimetry (MIP) and X-ray computed tomography (CT) tests. Neutron radiography was employed to track the dynamic wetting front in real time during water imbibition in the heat-treated mortar specimens exposed to a series of temperatures (105°C, 200°C, 400°C, 600°C, 800°C). The evolution of the wetting front was analyzed according to the square root of time based on neutron images. A deviation from the standard t1/2 pattern of the wetting front was found when water imbibition in the cement mortar specimens treated by a temperature ≥400°C. The absorptivities of different imbibition stages were determined for heat-damaged cement mortar. Mechanisms for the change of typical absorptivities with the evolution of thermal damage were discussed from the perspective of microstructure. In addition, causes for the occurrence of anomalous water absorption were explored by considering the role of thermal cracks and potential physicochemical reactions. Methods were proposed to estimate the effective tortuosity of water channels in the cement mortar damaged by different temperatures. The representative size of water channels was estimated with the calculated tortuosity. The estimated water channels size was compared with the pore aperture determined by MIP. At last, the estimated water channels size and tortuosity from imbibition data were utilized to predict the water permeability of the heat-treated mortar using a capillary model. By comparing the predicted and measured permeabilities, the correlation and difference between unsaturated and saturated water transport in the heat-treated cement mortar were analysed. Future work for modeling water transport in heat-damaged cement mortar was discussed.

Dynamic Control of the Dominant Modes of Interannual Variability of Snowfall Frequency in China

AbstractThis study investigates the first two leading modes of the interannual variability of frequency of snowfall events (FSE) over China in the winter during 1986–2018. The positive phase of the first leading mode (EOF1) is mainly characterized by positive FSE anomalies in northeastern–northwestern China and negative FSE anomalies in the three-river-source region. In contrast, the positive phase of the second leading mode (EOF2) is mainly characterized by positive FSE anomalies in central-eastern China (CEC). EOF1 is affected by the synoptic-scale wave activity over the midlatitudes of the East Asian continent, where active synoptic-scale wave activity over the midlatitudes may cause increased FSE over northeastern–northwestern China, and vice versa. In a winter of a negative phase of the North Atlantic Oscillation, an anomalous deep cold low may occur over Siberia, which may induce increased meridional air temperature gradient, increased atmospheric baroclinicity, and hence increased FSE over the midlatitudes of the East Asian continent. The EOF2 is affected by the interaction between anomalous northerly cold advection and anomalous southerly water vapor transport over CEC. The positive phase of EOF2 is associated with negative sea ice anomalies in the Barents Sea–Kara Sea region and negative sea surface temperature anomalies in the central-eastern tropical Pacific. Reduced sea ice in the Barents Sea–Kara Sea during January–February may cause increased northerly cold advection over CEC, while a La Niña–like condition during January may induce southerly water vapor transport anomalies over CEC.

Visualization of water concentration distribution in human skin by ultra-multiplex coherent anti-Stokes Raman scattering (CARS) microscopy

Ultra-multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopic imaging was used to visualize the distribution of water concentration in human skin ex vivo. The CARS signal of the OH stretching vibrational mode of water was found to coexist with the signal of intercellular lipids such as ceramides, which were visualized by a sharp vibrational band at 2882 cm−1. Depth-resolved CARS spectroscopic imaging of a skin sample revealed that ceramides were localized in the stratum corneum. These findings demonstrate the powerful potential of CARS spectroscopic imaging for probing pathological changes caused by anomalous water concentration distribution in human skin.

Silicone Polymers—Celebrating 80 Years of the Direct Process

Silicone Polymers—Celebrating 80 Years of the Direct Process

Quantifying the anomalous water absorption behavior of cement mortar in view of its physical sensitivity to water

The one-dimensional water absorption into cement-based materials, possibly the simplest case of unsaturated water flow playing a fundamental role in predicting mass transport and durability, is still far from being completely understood due to several puzzling anomalies. Considering the water sensitivity of C-S-H gels (swell upon wetting and contract upon drying), a modified Richards equation (MRE) is proposed to quantify the anomalous water absorption into cement-based materials of changing porosity. Consistent experimental tests on a cement mortar and calculations indicate that the MRE with time-decaying water permeability can quantitatively capture the long-term absorption with two linear stages and a nonlinear transition stage between them. The water sensitivity is validated to be responsible for the anomalous deviation of water absorption from the classical square root of time law. It also partially contributes to the anomalous dependence of sorptivity on the temperature-dependent surface tension and viscosity of water and many organic liquids.

Interannual variation in summer extreme precipitation over Southwestern China and the possible associated mechanisms

AbstractThis study explores the spatial–temporal variations in summer extreme precipitation over Southwestern China (SWC). The frequency of summer extreme precipitation (FEP) has exhibited strong interannual variation with slightly strengthened intensity in recent decades. The associated anomalous water vapour transport mainly originates from northern China, the Indian Ocean, the South China Sea and the Northwest Pacific. The high FEP over SWC is generally associated with the strong Eurasian (EU) pattern and the pattern that is similar to Pacific‐Japan (PJ) teleconnection. The results further indicate that the anomalous May Arctic sea ice concentration and the sea surface temperature anomaly over the Northwest Pacific play an important role in the variation of FEP over SWC. On the one hand, the reduction in Arctic sea ice concentration intensifies Rossby wave propagation and then stimulates the formation of EU teleconnection pattern. The associated anomalous northeasterly integrated water vapour transport and high‐level westerly anomalies can result in strong interannual changes in FEP over SWC. On the other hand, the sea surface temperature anomaly over the Northwest Pacific can induce an anomalous PJ‐like pattern, and the associated anomalous southwesterly water vapour transport also exerts an impact on the change in FEP over SWC.

Critical thickness for the emergence of Weyl features in Co3Sn2S2 thin films

Magnetic Weyl semimetals are quantum phases of matter arising from the interplay of linearly dispersive bands, spin-orbit coupling, and time reversal symmetry breaking. This can be realised, for example, in Co3Sn2S2, based on a cobalt kagome lattice and characterised by intriguing phenomena such as large anomalous Hall effect, Nernst effect, and water oxidation. Here, we attempt to determine the robustness of the twofold necessary conditions for the emergence of the magnetic Weyl semimetal phase in Co3Sn2S2 ultrathin films. Except for two-dimensional layered materials, a reduction of thickness generally makes it difficult to develop topological character and ferromagnetic long-range order. In Co3Sn2S2 films, while ferromagnetic ordering appears robustly even in average thicknesses of one or two unit cells with island-like polycrystalline domains, the anomalous Hall conductivity appears only above a critical thickness of approximately 10 nm. The emergence of surface conduction and large anomalous Hall effect implies the distinct contribution of Weyl nodes and their Berry curvature. These findings reveal an exotic feature of Weyl physics in thin-film based superstructures as well as a potential for future applications in electronic devices.

Subthermocline Eddies in the Kuroshio Extension Region Observed by Mooring Arrays

AbstractSubthermocline eddies (STEs), also termed intrathermocline eddies or submesoscale coherent vortices, are lens-shaped eddies with anomalous water properties located in or below the thermocline. Although STEs have been discovered in many parts of the World Ocean, most of them were observed accidentally in hydrographic profiles, and direct velocity measurements are very rare. In this study, dynamic features of STEs in the Kuroshio Extension (KE) region are examined in detail using concurrent temperature/salinity and velocity measurements from mooring arrays. During the moored observation periods of 2004–06 and 2015–19, 11 single-core STEs, including 8 with warm/salty cores and 3 with cold/fresh cores, were captured. The thermohaline properties in their cores suggest that these STEs may originate from the subarctic front and the upstream Kuroshio south of Japan. The estimated radius of these STEs varied from 8 to 66 km with the mean value of ~30 km. The warm/salty STEs seemed to be larger and rotate faster than the cold/fresh ones. In addition to single-core STEs, a dual-core STE was observed in the KE recirculation region, which showed that the upper cold/fresh cores stacked vertically over the lower warm/salty cores. Based on the observed parameters of the STEs, their Rossby number and Burger number were further estimated, with values up to 0.5 and 1, respectively. Furthermore, a low Richardson number O (0.25) was found at the periphery of these STEs, suggesting that shear instability-induced turbulent mixing may be an erosion route for the STEs.

How can the winter North Atlantic Oscillation influence the early summer precipitation in Northeast Asia: effect of the Arctic sea ice

The early summer (May–June) precipitation in Northeast Asia (NEA) accounts for about 25% of the annual total, which is important for the local agriculture production. The potential influencing factors and the related mechanisms of early summer NEA precipitation variability, however, are not fully understood. Our study suggests that a dipolar NEA precipitation anomaly pattern in May–June highly resembles the second leading mode of NEA early summer precipitation variability, can be induced by the winter North Atlantic Oscillation (NAO) through the “capacitor” effect of the Barents sea ice (BSI). Further analysis indicated that during negative NAO winter, anomalous northerlies controlling the Barents Sea tend to increase the local sea ice and reach its peak in spring. The BSI anomalies persist from spring to the following early summer generates the “positive–negative–positive” geopotential height anomalies occupying the Arctic, Kamchatka, and extra-tropical western Pacific. The southerlies on the west flank of the anomalous extra-tropical western Pacific anticyclone advect sufficient water vapor from the Pacific to southern NEA, concurrent with lower-troposphere convergence, leading to rich rainfall over Korea and southern Japan. In contrast, the lower-level divergence may reduce the precipitation over northern NEA. At last, a physical-based empirical model is established using the winter NAO index. It shows that the winter NAO provides a promising predictability source for this anomalous NEA dipolar precipitation pattern.

Anomalous Water Sorption Kinetics in Supported Nafion Thin-Films as Membrane-Electrode Assemblies

Anomalous Water Sorption Kinetics in Supported Nafion Thin-Films as Membrane-Electrode Assemblies

Unusually heavy stable Mo isotope signatures of the Ottawa River: Causes and implications for global riverine Mo fluxes

The accurate use of Mo isotope mass balance modelling of ancient oceans relies on the assumption that the δ98Mo of modern riverine inputs represents a reasonable estimate of the past. A growing number of studies of global rivers have demonstrated significant variation in δ98Mo from the bedrock sources of Mo. The Ottawa River, Canada, was previously identified as having an anomalously heavy Mo isotope composition, with a δ98Mo signature close to seawater (2.3‰), for a seemingly pristine natural river. To further explore this unusual signature, we collected and filtered 29 water samples from the Ottawa River, tributaries, and small lakes, and analysed them for Mo isotopes as well as major and trace elements. Here, we fully document heavy δ98Mo signatures throughout the Ottawa River and its absence in surrounding areas of the wider Ottawa River basin (ORB). Our results reveal a progressive upstream increase in both Mo concentration and δ98Mo signatures in the Ottawa River towards values even heavier than seawater, up to 3.13‰ – the heaviest Mo isotopic signature of river water measured to date. In contrast, the tributaries and lakes display far lighter and more consistent δ98Mo signatures within the range previously found in other rivers. Weathering of an isotopically heavy bedrock source, fractionation during weathering and retention of light isotopes in soils have all been proposed as sources of heavy δ98Mo in rivers; however, none of these mechanisms can satisfactorily explain our new observations. Colloidal and particulate processes that remove elements downstream, as inferred from some trace element proxies, also cannot explain the decreasing δ98Mo, since the preferential removal of light Mo isotopes is predicted from these processes. Similarly, the downstream trends show no apparent relationships with constructed dams or known potential industrial sources. Therefore, our findings from the Ottawa River are best explained as the dilution of a yet unidentified point source of heavy Mo upstream of sampling, or a significant permanent sink for light isotopes existing only in the upper reaches of the catchment. In both cases, anthropogenic contribution from a large mining district in the headwaters of the river must be considered and should be explored further. Fractionation of Mo in waste rock storage facilities has been previously identified and may provide an unnatural sink for isotopically light Mo through the Rayleigh-type fractionation of dissolved Mo on oxyhydr(oxide) mineral surfaces. The implied anthropogenic alteration of the natural Mo cycle highlights the significant and wide-reaching effects of unnatural point sources of Mo on the cumulative δ98Mo signatures of the catchment, and emphasises the necessity for detailed geochemical screening of anomalous river water isotope signatures before natural isotope compositions are inferred.

Recent changes of water level in Lake Khanka and their consequences for its fisheries resources

Interannual variation of the water level in Lake Khanka is considered on satellite altimetry data; its extreme rising in recent years is noted, with the maximum in 2016. Using a simple balance model, contribution of the main components of its water balance to the modern rise is determined, as precipitation in its basin, evaporation, and water discharge through the Sungacha River. Growth of summer precipitation is defined as the main reason of the level rising. However, the water income to the lake does not correlate with the precipitation volume since 2010 that confirms the hypothesis about artificial influence on the water balance of Lake Khanka by its connection with the Mulin River (China) and worsening of the outflow through the Sungacha. As the result, the lake got additionally about 1.3 km3in 2014–2015 that promoted the level rise to the highest mark. But before and after this period, the water inflow was lower than its expected values, obviously because of its redistribution. Positive influence of the anomalous water level growth on total abundance of commercial fish species is shown. The high level is favorable for reproduction of phytophilic species (Cyprinus rubrofuscus), whereas abundance of pelagophilic species (Chanodichthys erythropterus) declines.