Surfactant-Assisted Sulfonated Covalent Organic Nanosheets: Extrinsic Charge for Improved Ion Transport and Salinity-Gradient Energy Harvesting.

Charge-governed ion transport is the vital property of nanofluidic channels for salinity-gradient energy harvesting and other electrochemical energy conversion technologies. 2D nanofluidic channels constructed by nanosheets exhibit great superiority in ion selectivity, but a high ion transport rate remains challenging due to the insufficiency of intrinsic surface charge density in nanoconfinement. Herein, extrinsic surface charge into nanofluidic channels composed of surfactant-assisted sulfonated covalent organic nanosheets (SCONs), which enable tunable ion transport behaviors, is demonstrated. The polar moiety of surfactant is embedded in SCONs to adjust in-plane surface charges, and the aggregation of nonpolar moiety results in the sol-to-gel transformation of SCON solution for membrane fabrication. The combination endows SCON/surfactant membranes with considerable water-resistance, and the designable extrinsic charges promise fast ion transport and high ion selectivity. Additionally, the SCON/surfactant membrane, serving as a power generator, exhibits huge potential in harvesting salinity-gradient energy where corresponding output power density can reach up to 9.08 W m-2 under a 50-fold salinity gradient (0.5 m NaCl|0.01 m NaCl). The approach to extrinsic surface charge provides new and promising insight into regulating ion transport behaviors.

The "Gravity" for global virtual water flows: From quantity and quality perspectives.

The virtual water trade (VWT) has been proposed as a means of balancing national water budgets while also saving water globally. Since humans require both sufficient quantity and quality of water, the drivers of VWT flows should be thoroughly examined, including its three components. Multiregional input-output (MRIO) and gravity methods are used to investigate the influence of multiple factors on the green, blue, and grey water trading flows among 177 countries in 2014. Several factors were found to be strongly correlated with the grey water trade, offering valuable insight into water resource management, especially about water pollution. The findings verify the driving effects of socio-economic status and agricultural activities on virtual water trade. The study shows that the influence of water resources endowment on the virtual water trade flow is relatively small compared to economic structure in determining virtual water trade flows. The paper contributes to the research on the interaction between virtual water trade and various factors, which can assist decision-makers in optimizing economic structure by integrating water quantity and quality factors and realize sustainable management of water resources.

Free-Standing Covalent Organic Framework Membrane for High-Efficiency Salinity Gradient Energy Conversion.

Both high ionic conductivity and selectivity of a membrane are required for efficient salinity gradient energy conversion. An efficient method to improve energy conversion is to align ionic transport along the membrane thickness to address low ionic conductivity in traditional membranes used for energy harvesting. We fabricated a free-standing covalent organic framework membrane (TpPa-SO3 H) with excellent stability and mechanical properties. This membrane with one-dimensional nanochannels and high charge density demonstrated high ionic conductivity and selectivity. Its power density reached up to 5.9 W m-2 by mixing artificial seawater and river water. Based on our results, we attribute the high energy conversion to the high ion conductivity through aligned one-dimensional nanochannels and high ion selectivity via the size of the nanochannel at ≈1 nm in the membrane. This study paves the way for designing covalent organic framework membranes for high salinity gradient energy conversion.

A near-infrared fluorescent probe for H2S based on tandem reaction to construct iminocoumarin-benzothiazole and its application in food, water, living cells.

With the merits of non-destructive, high penetration ability and minimizing autofluorescence, near-infrared (NIR) fluorescent probes have attracted much attention. In this paper, a NIR emission fluorescent turn-on probe THQ-L for H2S was synthesized by the knoevenagel condensation between tetrahydroquinoxaline-6- formaldehyde derivative and 2-benzothiazoleacetonitrile. THQ-L can recognize H2S through tandem reaction triggered by HS- to construct 1,4-diethylpiperazine-modified iminocoumarin-benzothiazole, which produces a strong red fluorescent signal. THQ-L displayed an excellent selectivity toward H2S, a large stokes shift (126 nm), a high signal-to-noise ratio (200-fold), the detection limits of 38.3 nM in PBS (10 mM, pH 7.4, 30% THF). The application study indicates that THQ-L can sensitively detect H2S in red wine, natural waters, living cells and can be prepared for a test paper strip for the qualitative detection of H2S.

Estimation of the potential spread risk of COVID-19: Occurrence assessment along the Yangtze, Han, and Fu River basins in Hubei, China.

Given that the novel coronavirus was detected in stool and urine from diagnosed patients, the potential risk of its transmission through the water environment might not be ignored. In the current study, to investigate the spread possibility of COVID-19 via the environmental media, three typical rivers (Yangtze, Han, and Fu River) and watershed cities in Hubei province of China were selected, and a more comprehensive risk assessment analysis method was built with a risk index proposed. Results showed that the risk index in the Yangtze River Basin is about 10-12, compared to 10-10 and 10-8 in the Han and Fu River Basins, and the risk index is gradually reduced from Wuhan city to the surrounding cities. The safety radius and safety time period for the Yangtze, Han, and Fu River are 8 km/14 h, 20 km/30 h and 36 km/36 h, respectively. The linear relationship between the risk potential calculated by the QMRA model and the multiple linear regression proved that the built index model is statistically significant. By comparing the theoretical removal rates for the novel coronavirus, our study proposed an effective method to estimate the potential spread risk of COVID-19 in the typical river basins.

Renewable antibacterial and antifouling polysulfone membranes incorporating a PEO-grafted amphiphilic polymer and N-chloramine functional groups.

Functionalized polysulfone (PSf) membranes with combined antibacterial and antifouling properties were fabricated by incorporating a poly(ethyleneoxide)-grafted (PEO-grafted) amphiliic polymer. Both antifouling and antibacterial groups were easily introduced onto the membrane surfaces through non-solvent induced phase separon process and a simple chlorination process. It was observed that the functionalized membranes were effectivatie in resisting both protein absorption and bacterial adhesion. Furthermore, the functionalized membrane (M3-Cl) showed mostly suppressed irreversible flux decline and a 97% flux recovery ratio after simple washing during the separation process, indicating excellent antifouling properties. Meanwhile, the functionalized PSf membrane exhibited efficient biocidal activity against E. coli and S. aureus. These modified functionalized PSf membranes also displayed outstanding properties in inhibiting the formation of biofilm. Moreover, the antibacterial feature was renewable by a simple process.

A colorimetric and near-infrared fluorescent probe for detection of hydrogen sulfide and its real multiple applications.

A novel colorimetric and near-infrared fluorescent probe (L) with D-π-A structure derived from 4-diethylaminosalicylaldehyde and 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene)malononitrile has been developed. Probe L displays highly selective and sensitive recognition for H2S over various anions with a large Stokes shift (96 nm) in DMF/H2O (3/7, v/v, PBS-HCl 10 mM, pH = 7.4). A naked-eye observable color change of L solution from colorless to bluish-purple occurred on treatment with H2S. The potential applications of probe L were evaluated and the results show that probe L can detect H2S vapor and H2S in real water, red wine and living cells.

Equilibrium approach towards water resource management and pollution control in coal chemical industrial park.

In this study, an integrated water and waste load allocation model is proposed to assist decision makers in better understanding the trade-offs between economic growth, resource utilization, and environmental protection of coal chemical industries which characteristically have high water consumption and pollution. In the decision framework, decision makers in a same park, each of whom have different goals and preferences, work together to seek a collective benefit. Similar to a Stackelberg-Nash game, the proposed approach illuminates the decision making interrelationships and involves in the conflict coordination between the park authority and the individual coal chemical company stockholders. In the proposed method, to response to climate change and other uncertainties, a risk assessment tool, Conditional Value-at-Risk (CVaR) and uncertainties through reflecting parameters and coefficients using probability and fuzzy set theory are integrated in the modeling process. Then a case study from Yuheng coal chemical park is presented to demonstrate the practicality and efficiency of the optimization model. To reasonable search the potential consequences of different responses to water and waste load allocation strategies, a number of scenario results considering environmental uncertainty and decision maker' attitudes are examined to explore the tradeoffs between economic development and environmental protection and decision makers' objectives. The results are helpful for decision/police makers to adjust current strategies adapting for current changes. Based on the scenario analyses and discussion, some propositions and operational policies are given and sensitive adaptation strategies are presented to support the efficient, balanced and sustainable development of coal chemical industrial parks.

Integrated waste load allocation for river water pollution control under uncertainty: a case study of Tuojiang River, China.

This paper presents a bi-level optimization waste load allocation programming model under a fuzzy random environment to assist integrated river pollution control. Taking account of the leader-follower decision-making in the water function zones framework, the proposed approach examines the decision making feedback relationships and conflict coordination between the river basin authority and the regional Environmental Protection Agency (EPA) based on the Stackelberg-Nash equilibrium strategy. In the pollution control system, the river basin authority, as the leader, allocates equitable emissions rights to different subareas, and the then subarea EPA, as the followers, reallocates the limited resources to various functional zones to minimize pollution costs. This research also considers the uncertainty in the water pollution management, and the uncertain input information is expressed as fuzzy random variables. The proposed methodological approach is then applied to Tuojiang River in China and the bi-level linear programming model solutions are achieved using the Karush-Kuhn-Tucker condition. Based on the waste load allocation scheme results and various scenario analyses and discussion, some operational policies are proposed to assist decision makers (DMs) cope with waste load allocation problem for integrated river pollution control for the overall benefits.

Integrated antimicrobial and antifouling ultrafiltration membrane by surface grafting PEO and N-chloramine functional groups.

Ultrafiltration membranes with integrated antimicrobial and antifouling properties were fabricated using an engineering thermoplastic (carboxylated cardopoly(aryl ether ketone, PEK-COOH). Different molecular weights of PEO (Mw: 120, 350, 550) were grafted to the PEK-COOH membrane surface via EDC/NHS methodology. N-chloramine modified membranes then were prepared by simple exposure to dilute sodium hypochlorite solution. The surface grafting processes were all performed in water (i.e. without organic solvent). With this surface modification, the hydrophilicity of membranes improved significantly and the pure water flux increased compared to the unmodified PEK-COOH membrane. Furthermore, the PEO and N-chloramine modified membranes were resistant not only to both protein adsorption and bacterial adhesion, but also to microbial proliferation. The results of this work suggest that PEO and N-chloramine modified membranes are promising as fouling-resistant membranes.

Preparation and characterization of an antibacterial ultrafiltration membrane with N-chloramine functional groups.

In this study, a cardo poly(aryl ether ketone) ultrafiltration membrane containing an N-chloramine functional group (PEK-N-Cl membrane) was easily obtained via exposure of a cardo poly(aryl ether ketone) ultrafiltration membrane (PEK-NH membrane) to dilute sodium hypochlorite solution. The chlorination process did not harm membrane performance. In addition, the PEK-N-Cl membrane was stable in both air and water. The PEK-N-Cl membrane exhibited excellent antimicrobial properties against both Gram-negative and Gram-positive bacteria (i.e. E. coli and Bacillus subtilis, respectively). The PEK-N-Cl membrane provided 94.2% and 100% reduction of E. coli and Bacillus subtilis, respectively, within 30min of contact times. Moreover, nearly 100% of the E. coli was killed after 2h during the filtration process for the PEK-N-Cl membrane. In addition, the water flux decreased by 42% for the PEK-N-Cl membrane compared to 77.6% for the PEK-NH membrane after filtration of the E. coli solution and incubation on LB nutrient agar plate, indicating that the PEK-N-Cl membrane enhibits antifouling. Furthermore, the PEK-N-Cl membrane is recyclable via subsequent exposure to a sodium hypochlorite solution.

A new 2-(2'-hydroxyphenyl)quinazolin-4(3H)-one derived acylhydrazone for fluorescence recognition of Al3.

A new 2-(2'-hydroxyphenyl)quinazolin-4(3H)-one derived acylhydrazone (QP) was designed and synthesized as a fluorescent sensor. In Tris∙HCl buffer (10mM, pH7.4)/ethanol (1/9, v/v) solution, QP exhibits a highly selective fluorescence response to Al3+ over other metal ions with a significant blue-shifted and enhanced emission at 473nm. QP interacts with Al3+ reversibly through a 1:2 binding ratio with a detection limit of 4.79×10-8M. Potential applicability of QP for Al3+ detection in tap and lake water samples were also examined by 'proof-of-concept' experiments.

A new hydroxynaphthyl benzothiazole derived fluorescent probe for highly selective and sensitive Cu(2+) detection.

A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu(2+) in DMSO/H2O (7/3, v/v, Tris-HCl 10mM, pH=7.4) solution based on Cu(2+) catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205min(-1). Moreover, application of BTNP to Cu(2+) detection in living cells and real water samples was also explored.

Identification of malic enzyme mutants depending on 1,2,3-triazole moiety-containing nicotinamide adenine dinucleotide analogs.

An activity screening between 1,2,3-triazole moiety-containing nicotinamide adenine dinucleotide (NAD) analogs and malic enzyme (ME) mutants identified some mutants capable of taking NAD analogs as the cofactor. One particular pair, ME-L310K/L404S and the analog B-8 had good catalytic efficiency and cofactor specificity. The new system gained about 1200-fold cofactor specificity shift from NAD toward B-8 in terms of oxidative decarboxylation of l-malate. Our results provided insightful information for the development of orthogonal redox system that is of particular important to precisely control engineered metabolic pathways.

Creation of bioorthogonal redox systems depending on nicotinamide flucytosine dinucleotide.

Many enzymes catalyzing biological redox chemistry depend on the omnipresent cofactor, nicotinamide adenine dinucleotide (NAD). NAD is also involved in various nonredox processes. It remains challenging to disconnect one particular NAD-dependent reaction from all others. Here we present a bioorthogonal system that catalyzes the oxidative decarboxylation of l-malate with a dedicated abiotic cofactor, nicotinamide flucytosine dinucleotide (NFCD). By screening the multisite saturated mutagenesis libraries of the NAD-dependent malic enzyme (ME), we identified the mutant ME-L310R/Q401C, which showed excellent activity with NFCD, yet marginal activity with NAD. We found that another synthetic cofactor, nicotinamide cytosine dinucleotide (NCD), also displayed similar activity with the ME mutants. Inspired by these observations, we mutated d-lactate dehydrogenase (DLDH) and malate dehydrogenase (MDH) to DLDH-V152R and MDH-L6R, respectively, and both mutants showed fully active with NFCD. When coupled with DLDH-V152R, ME-L310R/Q401C required only a catalytic amount of NFCD to convert l-malate. Our results opened the window to engineer bioorthogonal redox systems for a wide variety of applications in systems biology and synthetic biology.

Efficient synthesis of triazole moiety-containing nucleotide analogs and their inhibitory effects on a malic enzyme.

Eleven triazole moiety-containing nucleotide analogs were synthesized starting form tetra-O-acetylribose in 55-63% total yields. The synthesis involved two key steps, the lipase-mediated selective deacylation of 1-azido-2,3,5-tri-O-acetyl-ß-D-ribofuranoside and the Huisgen 1,3-dipolar cycloaddition between terminal alkynes and the 1-azido ribofuranoside derivative. These analogs showed inhibitory effects against a recombinant Escherichia coli NAD-dependent malic enzyme.