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Uranium, a double-edged sword with high-efficiency energy and radioactive toxicity, attracts people to enjoy the advantages by generating power, but at the same time brings potential harm by nuclide migration. Therefore, it is necessary to develop a highly-efficient sensor to monitor uranyl ions in the field. However, the designed processes of the reported sensors are random, time-consuming and difficulty. It is urgent to find a new strategy to rationally, quickly and effectively screen out the required molecule for efficient uranium detection. Herein, with the guidance from the rational design method, the parameter, Egap, was applied to judge the chromatic aberration between the designed PADAP derivate and its uranyl complex. And the optimized structure sensor, 2-((3-bromo-5-(9,9-dioctyl-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-fluoren-2-yl)-2-pyridylazo)-5-(diethylamino)phenol (abbr. W1H), was screened and successfully synthesized. W1H exhibited significant color change (red to blue) after binding uranyl ions, and its detection limit for uranium was as low as nanomolar. More meaningfully, the coordination mechanism of W1H toward uranium was clarified by theoretical calculation of the electron cloud density distribution, Ebind, and 1H NMR, IR and MS for the first time. With the more excellent uranyl sensitivity, selectivity, and recyclability, W1H and its colorimetric test strip have been applied to the detection of low-concentration uranium in environmental samples around the uranium tailings, providing a useful on-site method to monitor trace uranium in actual samples.

As an energy-efficient and eco-friendly technique, capacitive deionization (CDI) has shown great potential for uranium (U(VI)) capture recently. However, extracting U(VI) with high kinetics, capacity and selectivity remains a major challenge due to the current surface active sites-based material and co-existing ions in aqueous solution. Here we rationally designed a layered 2D/2D niobium phosphate/holey graphene (HGNbP) electrode material, and originally demonstrated its efficient U(VI) capture ability via an electro-adsorption and electrocatalytic reduction coupling process. The less-accumulative loose layered architecture, open polycrystalline construction of niobium phosphate with active phosphate sites, and rich in-plane nano-pores on conductive graphene nanosheets endowed HGNbP with fast charge/ion transport, high electroconductivity and superior pseudocapacitance, which enabled U(VI) ions first to be electro-adsorbed, then physico-chemical adsorbed, and finally electrocatalysis reduced/deposited onto electrode surface without the limitation of active sites under a low potential of 1.2 V. Based on these virtues, the HGNbP exhibited a fast adsorption kinetics, with a high removal rate of 99.9% within 30 min in 50 mg L

Ten previously undescribed compounds, including two benzobicyclic ketones, one cycloheptenone oxide derivative, three guaiane-type sesquiterpenes, and four alkaloids, along with one known cycloheptenone oxide derivative, were isolated from the whole plants of Taraxacum mongolicum Hand.-Mazz. Their structures were elucidated by UV, IR, HR-ESI-MS, 1D and 2D NMR spectroscopy, ECD spectroscopy, or X-ray diffraction analysis. Notably, benzobicyclic ketones have never been isolated from nature before. The 70% EtOH-H

With rapid development of nuclear industry, the overexploitation of uranium has brought a series of radioactive pollution problems to water, soil, atmosphere and ecosystem. Uranium and its compounds are highly carcinogenic and biologically toxic, posing a deadly threat to human health. Therefore, how to design a highly selective and sensitive sensor to detect uranyl ions in the environment and organisms has become an urgent task. This review summarizes relevant literature on the detection of uranyl ions by different sensors over the years. The detection methods can be roughly divided into three categories: optical sensors, electrochemical sensors and other sensors; further classification has also been carried out according to their detection mechanism. The detection limits and performances of different sensors are discussed to intuitively understand different capability for these methods in detecting uranyl ions. We also discuss the trend and future direction of uranium to provide a valuable reference for further developing better uranyl sensors.

The microchannel heat exchanger has been applied in many field because of its advantages, such as miniaturization, large specific surface area, and high heat and mass transfer rate. In this work, a microchannel heat exchanger with fan-shaped cavities (FSCs) was developed, and used to conduct comparative experimental studies with the conventional rectangular straight microchannel heat exchanger. The effects of structural parameters, such as the deviation degree, coincidence degree and distribution of FSCs, on the heat transfer performance of the microchannel heat exchanger were investigated. The results indicate that the performance of the microchannel heat exchanger with FSCs is better than that without FSCs and the pressure drop is smaller. It is also revealed that the deviation degree, coincidence degree and distribution of the FSCs have important effects on the heat transfer performance.

Sustainable development goals (SDGs) emphasize decent work and well-being, while sustainable career development is a key determinant of these two parts. Based on Psychological Capital Theory, we investigate the micro mechanism of new urban immigrants' sustainable career development which is good to their social incorporation and sustainability. Especially this paper constructs a model including job performance as mediator and origin region as moderator to propose the relationship between psychological capital and new urban immigrants' career successes. Several hypotheses are supported by empirical evidence of a sample of 306 questionnaires filled by supervisors and employees with 11 firms. We found that psychological capital has a significant impact on career development including opportunities and satisfaction through job performance. Employees' origin region moderates the relationship between psychological capital and job performance. Compared to urban employees, the psychological capital of rural employees has a stronger influence on job performance. Origin region also significantly moderates the relationship between job performance and career development opportunities. Namely at the same level of performance, supervisors give more career development opportunities to rural employees. In regard to career development, psychological capital is more important to new urban immigrants than urban aborigines. We suggest that government and firms should pay more attention to new urban immigrants' psychological capital to propel them achieve sustainable career development which is good to society sustainability.

Porous foam microchannel reactor can effectively improve the reaction efficiency of Methanol reforming hydrogen production. Currently, porous foam microchannel reactors are primarily formed by the solid phase and liquid phase sintering techniques which generally require the metal fiber sheet of semi-finished products sinter at 800-1000℃ temperature conditions for 30–60 minutes. In this paper, a method of laser-sintered porous metal fiber sintering plate is proposed. Compared with the traditional methods, laser sintering technology has the advantages of shorter sintering time and retaining the surface microstructure which is more conducive to the adhesion of the catalyst. The effects of laser power, scanning rate, scanning distance, and scanning path on the sintering effect were also studied and analyzed. The results show that the porosity of copper fiber laser sintering sheets can reach 80% by laser sintering. When the laser sintering parameters for I=60A, f=20Hz, h=6.5ms, v=15mm/s, under the condition of variable speed sintering can achieve the best mechanical properties.

A reversible Schiff's base fluorescence probe for Al3+, (3,5-dichloro-2- hydroxybenzylidene) quinoline-2-carbohydrazide (QC), based on quinoline derivative has been designed, synthesized and evaluated. The QC exhibited a high sensitivity and selectivity toward Al3+ in EtOH-H2O (v/v=1:9, pH=6) by forming a 1:1 complex with Al3+ and the detection limit of QC for Al3+ was as low as 0.012μM. Furthermore, these results displayed that the binding of QCAl3+ was broken by F-, so this system could be used to monitor F- in the future. The enhancement fluorescence of the QC could be attributed to the inhibition of PET and ESIPT and the emergency of CHEF process induced by Al3+. More importantly, QC was not only successfully used for the determination of trace Al3+ in the tap water and the human blood serum, but was valid for fluorescence imaging of Al3+ in the Hela cells.

The salt marshes of Jamaica Bay serve as a recreational outlet for New York City residents, mitigate wave impacts during coastal storms, and provide habitat for critical wildlife species. Hurricanes have been recognized as one of the critical drivers of coastal wetland morphology due to their effects on hydrodynamics and sediment transport, deposition, and erosion processes. In this study, the Delft3D modeling suite was utilized to examine the effects of Hurricane Sandy (2012) on salt marsh morphology in Jamaica Bay. Observed marsh elevation change and accretion from rod Surface Elevation Tables and feldspar Marker Horizons (SET-MH) and hydrodynamic measurements during Hurricane Sandy were used to calibrate and validate the wind-waves-surge-sediment transport-morphology coupled model. The model results agreed well with in situ field measurements. The validated model was then used to detect salt marsh morphological change due to Sandy across Jamaica Bay. Model results indicate that the island-wide morphological changes in the bay's salt marshes due to Sandy were in the range of −30 mm (erosion) to +15 mm (deposition), and spatially complex and heterogeneous. The storm generated paired deposition and erosion patches at local scales. Salt marshes inside the west section of the bay showed erosion overall while marshes inside the east section showed deposition from Sandy. The net sediment amount that Sandy brought into the bay is only about 1% of the total amount of reworked sediment within the bay during the storm. Numerical experiments show that waves and vegetation played a critical role in sediment transport and associated wetland morphological change in Jamaica Bay. Furthermore, without the protection of vegetation, the marsh islands of Jamaica Bay would experience both more erosion and less accretion in coastal storms.

With the increasing demand of nuclear power plant, the depleted uranium is inevitably emitted and causes environmental risk, hence it is crucial to develop new methods to efficiently eliminate uranium compounds from water. In this work, a bifunctional material core-shell-shell layered double hydroxide (LDH) decorated hollow magnetic polydopamine (MP) microspheres (defined as MPL) were synthesized and evaluated for the cleanup of uranium (VI) from aqueous solutions through specific adsorption. The experimental results showed that the adsorption was significantly affected by pH value rather than ionic strength, reflecting that the interaction was mainly governed by inner-sphere surface complexation owing to the multiple functional groups including imine, catechol, amine, and hydroxyl groups. The adsorption kinetics can be perfectly depicted by the pseudo-second-order model with high uptake percentage of 94.8%, which was superior to the previously reported materials. Interestingly, the maximum adsorption performance can be tuned by changing the thickness of polydopamine shell and the content of LDH, in the order of MP2L2 (344 mg/g) > MP2L3 (291 mg/g) > MP3L2 (245 mg/g) > MP2L1 (211 mg/g) > ML2 (142 mg/g) > MP1L2 (141 mg/g) > MP2 (71 mg/g) > Fe3O4 (34 mg/g) at 298.15 K and pH 5.0. The adsorption mechanism has been thoroughly investigated with techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), thermo-gravimetric analyses (TGA), Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). In summary, the bifunctional material could be applied as promising building block for the enrichment and recovery of uranium (VI) from aqueous solutions in environmental pollution cleanup.

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A fluorescent sensor Hn based on β-diketone derivative for Th 4+ ions was designed and investigated, which showed high selectivity in the present of other metal ions even UO 2 2+ in CH 3 OH:H 2 O (v/v = 2:8, pH = 7.2) solution. Meanwhile, the binding mode of the sensor Hn with Th 4+ ions was found to be 1:1 with association constant of 2.46 × 10 4 M −1 . And there was linear relationship between the fluorescent intensity of Hn -Th 4+ and the concentration of Th 4+ ions covering a range of 0.06 μM–1.0 μM and the detection limit was 0.0344 μM. At the same time, the interaction properties between the sensor Hn and Th 4+ ions and the fluorescent mechanism were investigated by IR, 1 HNMR and DFT. Most importantly, this fluorescent sensor was successfully utilized for the fluorescent imaging of Th 4+ ions in living cells.

A facile, friendly and one-step hydrothermal protocol was used to synthesize nitrogen-doped carbon dots (N-CDs) by utilizing hexamethylenetetramine and ethanediamine as the carbon and nitrogen sources. It demonstrated good water solubility and fluorescence properties were stable, whether in acidic or alkaline. Quantum yield (QY) of N-CDs was 8.3% at an excitation wavelength of 325 nm with maximum emission at 425 nm. The fluorescence of N-CDs achieved very high fluorescence quenching of 60% in the detection of p-nitrophenol (p-NP) in aqueous medium via fluorescence resonance energy transfer (FRET) mechanisms. Under optimum conditions, fluorescence probs of N-CDs had strong selectivity to p-NP, and the fluorescence intensity was linearly proportional to p-NP concentration from 0.5 to 70.0 μM with a detection limit of 0.201 μM. The corresponding cell experiments were also performed, indicating that the prepared N-CDs possessed low cytotoxicity and good biocompatibility. Meanwhile, the N-CDs can be used for the determination of p-NP in river water and industrial wastewater.

Uranium mining, refining and spent fuel reprocessing are mostly carried out in an acidity and high water ratio environment. But there are currently fewer fluorescent probes that can meet this requirement. For this purpose, it is a urgent problem to design and synthesis fluorescent sensor for detection of uranium in these conditions. A novel triphenylamine-based fluorescent sensor (USC-001) has been design and prepared for the detection of uranyl ions in acidic and high water ratio environments and biologic samples. And even though the concentration of other metal ions is 5 times higher than that of uranyl ions, the probe is still have good selectivity to UO22+. In addition, a large number of auxiliary simulation calculations and experiment not only reveal the mechanism of the influence of water ratio on the change of the fluorescence spectrum, but also propose the mechanism and coordination mode of USC-001 for identifying UO22+. Furthermore, USC-001 has been successfully used to detect uranyl ions in actual water samples and biological cells.

Hierarchical silicon dioxide-@-layered double hydroxide (SiO2@LDH) nanocomposites were synthesized by a facile in situ co-precipitation method, and characterized by XRD, FESEM, FT-IR and XPS in detail. The sorption of uranium (U(VI)) and methyl orange (MO) on SiO2@LDH were investigated as a function of pH, ionic strength, contact time and temperature. The results indicated that the sorption of U(VI) and MO were strongly dependent on pH, and weakly dependent on ionic strength, demonstrating that the interaction of U(VI) was mainly dominated by inner-sphere surface complexation and the sorption of MO was mainly attributed to electrostatic attraction due to the high removal efficiency (∼98% within 4 h for U(VI) ions, and ∼92% within 10 min for MO). The kinetics sorption of U(VI) and MO both followed the pseudo-second-order model well, suggesting that the sorption processes were chemical sorption. The sorption isotherms of U(VI) and MO on SiO2@LDH were well fitted by the Langmuir model, and the maximum sorption capacities of SiO2@LDH were calculated to be 303.1 mg·g−1 for U(VI) and 166.1 mg·g−1 for MO. The thermodynamic parameters revealed that the sorption of U(VI) and MO was spontaneous process. Integrating the experimental result analysis, the hierarchical SiO2@LDH may be a promising material for the efficient elimination of radionuclides and dyes from aqueous solutions in natural environmental pollution cleanup.

There remains much debate regarding the perceived tradeoffs of using freshwater and sediment diversions for coastal restoration in terms of balancing the need for wetland restoration versus preserving eastern oyster ( Crassostrea virginica ) production. Further complicating the issue, climate change-induced sea-level rise (SLR) and land subsidence are also expected to affect estuarine water quality. In this study, we developed a process-based numerical modeling system that couples hydrodynamic, water quality, and oyster population dynamics. We selected Breton Sound Estuary (BSE) (∼2740 km 2 ) in the eastern Mississippi River Deltaic Plain since it is home to several of the largest public oyster seed grounds and private leases for the Gulf coast. The coupled oyster population model was calibrated and validated against field observed oyster growth data. We predicted the responses of oyster population in BSE to small- (142 m 3 s −1 ) and large-scale (7080 m 3 s −1 ) river diversions at the Caernarvon Freshwater Diversion structure planned in the 2012 Coastal Master Plan (Louisiana) under low (0.38 m) and high (1.44 m) relative sea-level rise (RSLR = eustatic SLR + subsidence) compared to a baseline condition (Year 2009). Model results showed that the large-scale diversion had a stronger negative impact on oyster population dynamics via freshening of the entire estuary, resulting in reduced oyster growth rate and production than RSLR. Under the large-scale diversion, areas with optimal oyster growth rates (>15 mg ash-free dry weight (AFDW) oyster −1 wk −1 ) and production (>500 g AFDW m −2 yr −1 ) would shift seaward to the southeastern edge of the estuary, turning the estuary into a very low oyster production system. RSLR however played a greater role than the small-scale diversion on the magnitude and spatial pattern of oyster growth rate and production. RSLR would result in an overall estuary-wide decrease in oyster growth rate and production as a consequence of decreased salinities in the middle and lower estuary because rising sea level likely causes increased stage and overbank flow downstream along the lower Mississippi River.

A modified gelcasting approach was used to fabricate the microscale randomized 1–3 piezoelectric array, which involves the in situ polymerization of hydantion epoxy resin and 3,3′-Diaminodipropylamine (DPTA) in the lead zirconate titanate (PZT) suspensions with low viscosity and high solid loading. Rheological results demonstrated that the hydantion epoxy resin concentration had little effect on the viscosity of the premix solution, and therefore the optimized solid loading of the suspensions with 15.0 wt% resin could reach as high as 55.0 vol%. Weibull analysis also revealed that a more homogenous microstructure was obtained derived from the 55.0 vol% PZT suspension, where the Weibull modulus and the characteristic flexural strength reached the maximum value of 12.57 and 80.94 MPa. The excellent randomized piezoelectric pillar array with superior structural integrity and high fidelity was successfully fabricated.

The base-free O- difluoromethylation of 1,3-diones with difluorocarbene generated from difluoromethylene phosphobetaine (Ph 3 P + CF 2 CO 2 − ) is described. The convenient reactions proceeded smoothly to give difluoromethyl enol ethers in moderate to good yields.

In this paper, we specifically designed and synthesized an excellent colorimetric and ratiometric fluorescent sensor DPA-CI for rapid and convenient detection of the highly toxic phosgene. DPA-CI was developed by incorporated a diphenylamine (DPA) and a 2-imine-3-benzo[d]imidazole as the enhanced push–pull electronic structure into the coumarin fluorophore matrix. The sensor DPA-CI towards phosgene sensing exhibited both visible colorimetric and ratiometric fluorescent color change in solution and in gaseous conditions with TICT and AIE mechanism respectively, which can be easily distinguished by using the naked eye. Also, the sensor DPA-CI showed splendid sensing performance such as excellent selectivity, rapid response (less than 8 s in THF and 2 min in gaseous condition), and fair sensitivity (limit of detection less than 0.11 ppm in gaseous condition and 0.27 μM in solution). The design strategy based on enhanced push–pull electronic structure with AIE and TICT properties will be helpful to construct a solid optical sensor with excellent potential application prospects for portable and visual sensing of gaseous phosgene through distinct color and ratiometric fluorescence change by the naked eyes.

It is of great importance to design a fluorescent sensor with high selectivity, sensitivity and large Stokes shift to zinc detection for environmental water sample and in vivo. Herein, A novel Zn2+ fluorescent sensor with larger Stokes shift (110 nm) 1-((5-(4-(diphenylamino)phenyl)pyridine-2-imino)methyl)naphthalene-2-ol (abbr. TPA-PN) was designed and synthesized. In DMF-H2O (V: V = 1: 1, pH = 7.0) solution, it could achieve high selectivity and sensitivity to Zn2+, there was a linear responsive range of 0–20 μM of concentration of Zn2+ ions for the sensor, the detection limit was as low as 19.134 nM and the binding constant was calculated to be 3.24 × 104 M−1. The species of TPA-PN and zinc were clarified at different pH. Besides, the interaction properties and fluorescence mechanism were demonstrated by the species theory, density functional theory (DFT) calculation, 1H NMR titration, FT-IR and MS. Most importantly, it provided a new real-time, on-site method and showed excellent potential in-vivo imaging ability.

It is an important challenge to develop a chemosensor for trace uranyl ion in an aqueous medium for sustainable development of nuclear energy and environmental conservation. A conjugated fluorescent polymer sensor P2 based on amidoxime groups and polyfluorene, which showed good hydrophilous resulting adequate contact with uranyl ions and selectivity and sensitivity even in the presence of other metal ions in DMA/H2O (v/v = 20:80, pH = 6.0) solution, for uranyl ion was designed and prepared in this work. And it possesses good thermal stability and a larger Stokes shift (108 nm). Importantly, the fluorescence quenching occurred when P2 combining uranium. It had a good linear relationship with UO22+ concentration in the range of 10 to 200 nM with a fairly low LOD 7.4 × 10−9 M. Interaction properties between the sensor P2 and UO22+ and the fluorescent mechanism were investigated by density functional theory (DFT). More importantly, the sensor can be successfully used for the detection of uranyl ion in environmental solutions. This work suggests that conjugated fluorescent polymer with amidoxime groups will be a prospective sensor of uranyl ion in the environmental sample.

Self-organization is a process of establishing and reinforcing local structures through feedbacks between internal population dynamics and external factors. In reef-building systems, substrate is collectively engineered by individuals that also occupy it and compete for space. Reefs are constrained spatially by the physical environment, and by mortality, which reduces production but exposes substrate for recruits. Reef self-organization therefore depends on efficient balancing of production and occupancy of substrate. To examine this, we develop a three-dimensional individual-based model (IBM) of oyster reef mechanics. Shell substrate is grown by individuals as valves, accumulates at the reef level, and degrades following mortality. Single restoration events and subsequent dynamics are simulated for a case study in South Carolina (USA). Variability in model processes is included on recruitment, spatial environmental constraints, and predation, over multiple independent runs and five predator community scenarios. The main goal for this study is to summarize trends in dynamics that are robust across this uncertainty, and from these generate new hypotheses and predictions for future studies. Simulation results demonstrate three phases following restoration: initial transient dynamics with considerable shell loss, followed by growth and saturation of the live population, and then saturation of settlement habitat several years later. Over half of simulations recoup initial shell losses as populations grow, while others continue in decline. The balance between population density, substrate supporting the reef, and exposed surfaces for settlement is mediated by overall population size and size structure, presence of predators, and relative amounts of live individuals and intact dead shells. The efficiency of settlement substrate production improves through time as population size structure becomes more complex, and the population of dead valves accumulates.

A novel rhodamine-based dual probe Rh-2 for trivalent ferric ions (Fe(3+)) was successfully designed and synthesized, which exhibited a highly sensitive and selective recognition towards Fe(3+) with an enhanced fluorescence emission in methanol-water media (v/v=7/3, pH=7.2). The probe Rh-2 could be applied to the determination of Fe(3+) with a linear range covering from 3.0×10(-7) to 1.4×10(-5)M and a detection limit of 1.24×10(-8)M. Meanwhile, the binding ratio of Rh-2 and Fe(3+) was found to be 1:1. Most importantly, the fluorescence and color signal changes of the Rh-2 solution were specific to Fe(3+) over other commonly coexistent metal ions. Moreover, the probe Rh-2 has been used to image Fe(3+) in living cells with satisfying results.

Understanding the rate and extent of 63Ni(II) sorption and desorption on/from mineral surfaces are important to predict its mobility performance in the natural environment. We herein systematically investigated the effects of pH, electrolyte cations, humic acid (HA) and temperature on 63Ni(II) sorption/desorption on/from Na-montmorillonite. The results indicated that the sorption/desorption of 63Ni(II) on/from Na-montmorillonite were strongly dependent on pH and electrolyte cations. Desorption abilities of 63Ni(II) were Na+ ≈ K+ > Ca2+ ≈ Mg2+ at the cationic concentration of 0.2 mol/L, which was associated with the clay tactoid size. The kinetic results suggested that 63Ni(II) sorption/desorption initially increased rapidly and remained constant as time increasing. The presence of HA influenced 63Ni(II) sorption clearly and promoted 63Ni(II) desorption as a result of the dissolution of ternary surface complexes. Increasing temperature was favorable for the sorption reaction owing to the formation of strong inner-sphere complexes, however, hampered the desorption reaction because of the increased stability of inner-sphere complexes or the aggregation of montmorillonite. The results are crucial to understand the physicochemical behavior of radionickel in the natural environment.

With the fast development of nanoscience and nanotechnology, the nanomaterials have attracted multidisciplinary interests. The high specific surface area and large numbers of oxygen-containing functional groups of graphene oxides (GOs) make them suitable in the preconcentration and solidification of radionuclides from wastewater. In this paper, mainly based on the recent work carried out in our laboratory, the efficient elimination of radionuclides using GOs and GO-based nanomaterials as adsorbents are summarized and the interaction mechanisms are discussed from the results of batch techniques, surface complexation modeling, spectroscopic analysis and theoretical calculations. This review is helpful for the understanding of the interactions of radionuclides with GOs and GO-based nanomaterials, which is also crucial for the application of GOs and GO-based nanomaterials in environmental radionuclide pollution management and also helpful in nuclear waste management.

Coastal ecosystems are especially vulnerable to global change; e.g., sea level rise (SLR) and extreme events. Over the past century, global change has resulted in salt-tolerant (halophytic) plant species migrating into upland salt-intolerant (glycophytic) dominated habitats along major rivers and large wetland expanses along the coast. While habitat transitions can be abrupt, modeling the specific drivers of abrupt change between halophytic and glycophytic vegetation is not a simple task. Correlative studies, which dominate the literature, are unlikely to establish ultimate causation for habitat shifts, and do not generate strong predictive capacity for coastal land managers and climate change adaptation exercises. In this paper, we first review possible drivers of ecotone shifts for coastal wetlands, our understanding of which has expanded rapidly in recent years. Any exogenous factor that increases growth or establishment of halophytic species will favor the ecotone boundary moving upslope. However, internal feedbacks between vegetation and the environment, through which vegetation modifies the local microhabitat (e.g., by changing salinity or surface elevation), can either help the system become resilient to future changes or strengthen ecotone migration. Following this idea, we review a succession of models that have provided progressively better insight into the relative importance of internal positive feedbacks versus external environmental factors. We end with developing a theoretical model to show that both abrupt environmental gradients and internal positive feedbacks can generate the sharp ecotonal boundaries that we commonly see, and we demonstrate that the responses to gradual global change (e.g., SLR) can be quite diverse.

Let E , F ⊂ R be two given closed intervals, and let τ: E → F and θ: F → E be continuous maps. In this paper, we consider Koto’s chaos, sensitivity and accessibility of a given system Ψ ( u , v ) = ( θ ( v ) , τ ( u ) ) on a given product space E × F where u ∈ E and v ∈ F. In particular, it is proved that for any Cournot map Ψ ( u , v ) = ( θ ( v ) , τ ( u ) ) on the product space E × F, the following hold: (1) If Ψ satisfies Kato’s definition of chaos then at least one of Ψ 2 | Q 1 and Ψ 2 | Q 2 does, where Q 1 = { ( θ ( v ) , v ) : v ∈ F } and Q 2 = { ( u , τ ( u ) ) : u ∈ E } . (2) Suppose that Ψ 2 | Q 1 and Ψ 2 | Q 2 satisfy Kato’s definition of chaos, and that the maps θ and τ satisfy that for any e > 0, if ∣ ( τ ∘ θ ) n ( v 1 ) − ( τ ∘ θ ) n ( v 2 ) ∣ ɛ and ∣ ( θ ∘ τ ) m ( u 1 ) − ( θ ∘ τ ) m ( u 2 ) ∣ ɛ for some integers n, m > 0, then there is an integer l(n, m, e) > 0 with ∣ ( τ ∘ θ ) l ( n , m , ɛ ) ( v 1 ) − ( τ ∘ θ ) l ( n , m , ɛ ) ( v 2 ) ∣ ɛ and ∣ ( θ ∘ τ ) l ( n , m , ɛ ) ( u 1 ) − ( θ ∘ τ ) l ( n , m , ɛ ) ( u 2 ) ∣ ɛ . Then Ψ satisfies Kato’s definition of chaos.

Hydrology is a critical driver controlling mangrove wetlands structural and functional attributes at different spatial and temporal scales. Yet, human activities have negatively affected hydrology, causing mangrove diebacks and coverage loss worldwide. In fact, the assessment of mangrove water budgets, impacted by natural and human disturbances, is limited due to a lack of long-term data and information that hinders our understanding of how changes in hydroperiod and salinity control mangrove productivity and spatial distribution. In this study, we implemented a mass balance-based hydrological model (RHYMAN) that explicitly considers groundwater discharge in the Shark River estuary (SRE, southwestern Everglades) located in a karstic geomorphic setting and influenced by regional hydrological restoration. We used long-term hydroperiod and porewater salinity (PWS) datasets obtained from 2004 to 2016 for model calibration and validation and to determine spatiotemporal variability in water levels and PWS at three riverine mangrove sites (downstream, SRS-6; midstream, SRS-5; upstream, SRS-4) along SRE. Model results agree with a distinct PWS pattern along the estuarine salinity gradient where the highest PWS occurs at SRS-6 (mean: 25, range: 22–30 ppt), followed by SRS-5 (17, 14–25 ppt) and SRS-4 (5, 3–13 ppt). A commensurate increase in PWS over a thirteen-year period indicates a long-term reduction in freshwater inflow coupled with sea-level rise (SLR). Increasing freshwater scenario simulation results show a significant reduction (17–27%) in PWS along the estuary in contrast with a high SLR scenario when salinity increases up to 1.1 to 2.5 times that of control values. Model results show that freshwater inflow and SLR are key drivers controlling mangrove wetlands PWS in this karstic coastal region. Given its relatively simple structure, this mass balance-based hydrological model could be used in other environmental settings to evaluate potential habitat and regime shifts due to changes in hydrology and PWS under regional hydrological restoration management.

With the development of nuclear power, the negative environmental impact such as radioactive pollution has become an urgent issue to impede the utilization of nuclear energy. The construction of promising organic-inorganic hybrid materials is considered as an effective strategy for environmental remediation of radioactive contamination. In this work, two-dimensional transition metal carbide (MXene), an emerging inorganic layered material, has been successfully modified by carboxyl terminated aryl diazonium salt to both enhance its chelating ability to radionuclides and improve its water stability. The carboxyl functionalized Ti3C2Tx MXene (TCCH) shows excellent removal ability for U(VI) and Eu(III), evidenced by ultrafast adsorption kinetics (3 min), high maximum adsorption capacities (344.8 mg/g for U and 97.1 mg/g for Eu) and high removal percentage of radionuclides from artificial groundwater (> 90%). The adsorption of U(VI) and Eu(III) on TCCH are in good accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. Ionic strength experiments, X-ray photoelectron spectroscopy (XPS) and Extended X-ray absorption fine structure (EXAFS) analyses were conducted to assess the detailed adsorption mechanism. The results reveal that the adsorption of U(VI) on TCCH follows an inner-sphere configuration, whereas the adsorption of Eu(III) is determined by both inner-sphere complexation and electrostatic interaction.

Offering a substantial method to convert HCl to Cl2 over CuCl2/pumice, Deacon process is of great importance in chemical industry. In the process, the difficulty of Cl2 formation/desorption and catalyst re-oxidation have been unanimously recognized as the origin of the instability of CuO-based catalysts. In this work, the stability of the CuO/Al2O3 catalyst was significantly improved by adding Co. The fabricated CuO(12)–CoOx(13)/Al2O3 catalyst showed unprecedented stability with HCl conversion (xHCl) above 80%, lasting for at least 1000 h. The X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and H2-temperature programmed reduction (H2-TPR) characterizations suggested that the addition of Co greatly enhanced the dispersion of CuO on Al2O3 and hindered the reduction of CuO due to their strong interaction. The results of reaction kinetics suggested that the lattice oxygen participated in the reaction and the reaction order on oxygen was estimated to be 0.15, suggesting that the catalyst obeyed the Mars-van Krevelen (M-K) mechanism, while only small amount of oxygen was required to maintain the activity of catalysts compared to CuO/Al2O3. Density functional theory (DFT) calculations proved that the CuO–CoOx/Al2O3 ternary system was more stable than CuO/Al2O3 binary system and easier to be oxidized by O2, which greatly reduced the difficulty of Cl2 associative desorption.

Uranium is a kind of natural radionuclide, when the human body is exposed to higher uranium radioactive conditions, it will cause adverse effects on their health. Therefore, the analysis and detection of uranyl ions in the environment is a vital prerequisite for preventing uranium pollution. A bipolar bidentate ligand isophthalaldehyde-tetrapyrrole (IPTP) was first synthesized and a study was characterized by its structure and spectral properties. In the present work, an innovative electrochemical sensor by using IPTP as a ligand for uranyl (VI) ion (UO22+), α-methacrylic acid as functional monomer and uranyl (VI) ion as a template, a relatively stable structure was constructed by stirring at 35 °C. Then, the polymer sol-gel was acquired by combining sol-gel processing under alkaline conditions, which was added dropwise to the surface of a carbon paste electrode (CPE) which had been modified with graphene (GR). The introduction of graphene allowed the reduction peak current of uranyl ions to be increased significantly. Under the optimum experimental conditions (pH=5 and the adsorption time=20 min), the ion-imprinted sensor was designed by adopting differential pulse voltammetry (DPV) for the sensing of uranyl (VI) ions. The detection technique successfully achieved the determination of uranyl ion in the concentration range 1.0 × 10−10 mol L − 1 to 1.0 × 10−7 mol L − 1, in practical soil samples with excellent repeatability and recovery (97.3%-102.9%).

Colorless and highly toxic phosgene has long been considered to be a great menace to human health and national security. Excellent AIE + TICT characteristic ratiometric and colorimetric fluorescent sensor TPE-CI was constructed with the combination of the TICT based 3-benzo[d]imidazole-chromen-2-imine unit and AIE based tetraphenylethene (TPE) unit. TPE-CI can detect phosgene not only in organic solvent through a change from the TICT process to the AIE process, but also in solid-state through a new change from the AIE + TICT process to the AIE process. TPE-CI exhibited convenient to use as a test strip, rapid response (less than 6 s in solvent and 2 min in air atmosphere), excellent selectivity and fair sensitivity for visual inspection of trace phosgene in the organic solvent and in the gas phase. The limit of detection (LOD) was calculated and derived as 0.36 μM in solvent and 0.27 ppm in the air atmosphere, which was far below the acute phosgene exposure level of human response. The satisfactory results indicate that this AIE + TICT strategy may offer valuable thinking to develop convenient solid-state optical sensors with dual ratiometric and colorimetric fluorescence response for gaseous phosgene identification.

It is still a challenge for scientists to eliminate interference and improve chromatic aberration in designing colorimetric uranyl ions sensors, and it is also not clear how the species of uranium and sensor synergistically affect the coloration mechanism and coordination mode of ligands containing nitrogen or oxygen atoms at different pH. Herein, we design and synthesize 2-(5′-(p-(diphenylamino)phenyl)-2′-pyridylazo)-5-(diethylamino)phenol (abbr. S-LH) for the colorimetric detection of uranyl ions in mixed solvents. The rational introduced triphenylamine group by density functional theory (DFT) calculation enhances the chromaticity difference of the S-LH toward uranyl ions, making the detection limits of the uranyl ions approximately one order of magnitude lower than that of the present UV–vis and visual method. The species of S-LH and uranium at different pH are clarified and it well explains the reason of different color changes after adding uranyl ions. Stability constant experiments show that S-LH has excellent anti-interference to other metal ions during detecting uranium. The coordination structure of S-LH towards UO22+ is further confirmed by HRMS, 1H NMR titration, and DFT calculation. Finally, colorimetric test strips with S-LH are prepared to detect uranium in Xiang River, providing an on-site and real-time method to detect uranyl ions in the environment.