Boosting Osmotic Energy Harvesting from Organic Solutions by Ultrathin Covalent Organic Framework Membranes.

Extracting osmotic energy from waste organic solutions via reverse electrodialysis represents a promising approach to reuse such industrial wastes and helps to mitigate the ever-growing energy needs. Herein, a molecularly thin membrane of covalent organic frameworks is engineered via interfacial polymerization to investigate its ion transport behavior in organic solutions. Interestingly, a significant deviation from linearity between ion conductance and reciprocal viscosity is observed, attributed to the nanoscale confinement effect on intermolecular interactions. This finding suggests a potential strategy to modulate the influence of apprarent viscosity on transmembrane transport. The osmotic energy harvesting of the ultrathin membrane in organic systems was studied, achieving an unprecedented output power density of over 84.5 W m-2 at a 1000-fold salinity gradient with a benign conversion efficiency and excellent stability. These findings provide a meaningful stepping stone for future studies seeking to fully leverage the potentials of organic systems in energy harvesting applications.

Regulating the Layered Stacking of a Covalent Triazine Framework Membrane for Aromatic/Aliphatic Separation.

Membrane separation of aromatics and aliphatics is a crucial requirement in chemical and petroleum industries. However, this task presents a significant challenge due to the lack of membrane materials that can endure harsh solvents, exhibit molecular specificity, and facilitate easy processing. Herein, we present a novel approach to fabricate a covalent triazine framework (CTF) membrane by employing a mix-monomer strategy. By incorporating a spatial monomer alongside a planar monomer, we were able to subtly modulate both the pore aperture and membrane affinity, enabling preferential permeation of aromatics over aliphatics with molecular weight below 200 Dalton (Da). Consequently, we achieved successful all-liquid phase separation of aromatic/aliphatic mixtures. Our investigation revealed that the synergistic effects of size sieving and the affinity between the permeating molecules and the membrane played a pivotal role in separating these closely resembling species. Furthermore, the membrane exhibited remarkable robustness under practical operating conditions, including prolonged operation time, various feed compositions, different applied pressure, and multiple feed components. This versatile strategy offers a feasible approach to fabricate membranes with molecule selectivity toward aromatic/aliphatic mixtures, taking a significant step forward in addressing the grand challenge of separating small organic molecules through membrane technology.

Enantioselective Toxicity and Potential Endocrine-Disruptive Effects of the Insecticides Flufiprole and Ethiprole on Danio rerio.

Phenylpyrazole insecticides are widely used as chiral pesticides. However, the enantioselective toxicity and potential endocrine-disrupting effects of these insecticides on aquatic organisms remain unclear. Herein, the enantioselective toxicity and potential endocrine-disrupting effects of flufiprole and ethiprole were investigated by using zebrafish embryos/larvae as a model. The acute toxicity of R-flufiprole and R-ethiprole toward zebrafish embryos and larvae was 1.8-3.1-fold higher than that of the S-configuration. Additionally, R-flufiprole and R-ethiprole had a greater effect on the expression of genes related to the hypothalamus-pituitary-gonad axis in zebrafish compared with the S-configuration. Nevertheless, both S-flufiprole and S-ethiprole exhibited a greater interference effect on the expression of genes related to the hypothalamus-pituitary-thyroid axis and a greater teratogenic effect on zebrafish than the R-configuration. Thus, this study demonstrates that both flufiprole and ethiprole exhibit enantioselective acute toxicity and developmental toxicity toward zebrafish. Furthermore, those pesticides potentially possess enantioselective endocrine-disrupting effects.

Tefluthrin induced toxicities in zebrafish: Focusing on enantioselectivity.

Tefluthrin is one of widely used chiral pyrethroid pesticides. The potential enantioselective risk posed by tefluthrin to the aquatic ecosystem is still unclear. In this study, the toxicity differences and corresponding mechanism of tefluthrin on zebrafish were investigated at the enantiomeric level. The results indicated that two tefluthrin enantiomers showed different acute toxicity, developmental toxicity and oxidative stress to zebrafish. The acute toxicity of (1R,3R)-tefluthrin was 130-176 fold as that of (1S,3S)-tefluthrin on zebrafish embryos, larvae and adults. (1R,3R)-Tefluthrin presented approximately 10, 3 and 2 times inhibition effect on the deformity rate, hatching rate and spontaneous movements on embryos as that of (1S,3S)-tefluthrin. Meanwhile, (1R,3R)-tefluthrin caused stronger oxidative stress on zebrafish embryo than (1S,3S)-tefluthrin. The molecular docking results revealed that there were stereospecific binding affinities between tefluthrin enantimers and sodium channel protein (Nav1.6), which may lead to acute toxicity differences. Transcriptome analysis showed that the two tefluthrin enantiomers markedly disturbed differential embryonic genes expression, thereby potentially causing the chronic enantioselective toxicity. The findings of the study reveal the toxicity differences and potential mechanism of tefluthrin enantiomers on zebrafish. These results also provides a foundation for a systematic evaluation of tefluthrin at enantiomer level.

Anomalous Mechanical and Electrical Interplay in a Covalent Organic Framework Monolayer Membrane.

Ion transport through nanoconfinement, driven by both electrical and mechanical forces, has drawn ever-increasing attention, due to its high similarity to stress-sensitive ion channels in biological systems. Previous studies have reported only pressure-induced enhancement in ion conductance in low-permeable systems such as nanotubes, nanoslits, or single nanopores. This enhancement is generally explained by the ion accumulation caused by the capacitive effect in low-permeable systems. Here, we fabricate a highly permeable COF monolayer membrane to investigate ion transport behavior driven by both electrical and mechanical forces. Our results show an anomalous conductance reduction activated by external mechanical force, which is contrary to the capacitive effect-dominated conductance enhancement observed in low-permeable nanopores or channels. Through simulations, we uncovered a distinct electrical-mechanical interplay mechanism that depends on the relative rate between the ion diffusion from the boundary layer to the membrane surface and the ion transport through the membrane. The high pore density of the COF monolayer membrane reduces the charge accumulation caused by the capacitive effect, resulting in fewer accumulated ions near the membrane surface. Additionally, the high membrane permeability greatly accelerates the dissipation of the accumulated ions under mechanical pressure, weakening the effect of the capacitive layer on the streaming current. As a result, the ions accumulated on the electrodes, rather than in the capacitive layer, dominating the streaming current and giving rise to a distinct electrical-mechanical interplay mechanism compared to that in low-permeable nanopores or channels. Our study provides new insights into the interplay between electrical and mechanical forces in ultra-permeable systems.

Essence of the Enhanced Osmotic Energy Conversion in a Covalent Organic Framework Monolayer.

Low membrane conductivity originated from a high membrane thickness has long been the "Achilles heel" of the conventional polymeric membrane, greatly hampering the improvement of the output power density in osmotic power generation. Herein, we demonstrate a molecularly-thin two-dimensional (2D) covalent organic framework (COF) monolayer membrane, featured with ultimate thickness, high pore density, and tight pore size distribution, which performs as a highly efficient osmotic power generator. Despite the large pore size up to 3.8 nm and relatively low surface charge density of 2.2 mC m-2, the monolayer COF membrane exhibits a high osmotic current density of 16.7 kA m-2 and an output power density of 102 W m-2 under 50 times the NaCl salinity gradient (0.5 M/0.01 M). This superior power density could be further improved to 170 W m-2 in the real seawater/river water gradient system. When the large pore size and low surface charge density are considered, this superior performance is not expected. Computational studies further reveal that the ultimate membrane permeability originated from the high membrane porosity, rather than ion selectivity, plays a dominant role in the production of high current density, especially under high salinity. This work provides an alternative strategy to realize improved output power density in ultrapermeable membranes.

Nanoscale Pore-Pore Coupling Effect on Ion Transport through Ordered Porous Monolayers.

Distinct from the conventional view that nanopores are considered independent channels for mass transport, recent study on the covalent organic framework (COF)-based monolayers characteristic of an ordered nanopore array exhibits a series of interesting properties originating from the strong interactions between adjacent pores. These interactions are determined to be highly dependent on interpore distance and pose a significant influence on the ion transport, accounting for the exceptional membrane performance including both selectivity and conductance. In this Perspective, we discuss the recently discovered nanoscale pore-pore coupling as well as the exciting features of porous nanostructures. We also look at the challenges and future opportunities of ion transport in ordered porous monolayers in the aspects of both fundamental research and practical use.

Advancing osmotic power generation by covalent organic framework monolayer.

Osmotic power, also known as 'blue energy', is produced by mixing solutions of different salt concentrations, and represents a vast, sustainable and clean energy source. The efficiency of harvesting osmotic power is primarily determined by the transmembrane performance, which is in turn dependent on ion conductivity and selectivity towards positive or negative ions. Atomically or molecularly thin membranes with a uniform pore environment and high pore density are expected to possess an outstanding ion permeability and selectivity, but remain unexplored. Here we demonstrate that covalent organic framework monolayer membranes that feature a well-ordered pore arrangement can achieve an extremely low membrane resistivity and ultrahigh ion conductivity. When used as osmotic power generators, these membranes produce an unprecedented output power density over 200 W m-2 on mixing the artificial seawater and river water. This work opens up the application of porous monolayer membranes with an atomically precise structure in osmotic power generation.

Artificial shelters provide suitable thermal habitat for a cold-blooded animal.

Human activities such as urbanization often has negative affects wildlife. However, urbanization can also be beneficial to some animals by providing suitable microhabitats. To test the impact of urbanization on cold-blooded animals, we first conducted a snake survey at a national nature reserve (Xianghai natural reserve) and an adjacent tourist bird park (Red-crowned Crane Park). We show high presence of Elaphe dione in the tourist park even with high human activities and predator population (the endangered, red-crowned crane, Grus japonensis). We then radio-tracked 20 individuals of E. dione, set seven camera traps, and recorded the temperature of the snakes and artificial structures in Crane Park to document their space use, activity, and thermal preference, respectively. Our results show E. dione preferred to use artificial facilities to shelter from their predators and for thermoregulation. The high number of rats from the camera traps indicate abundant prey items. Overall, E. dione appears to be adapted to modified habitats and may expand population size at the current study site.

Intrinsic Clearance and Metabolism Pathway of Fosthiazate in Rat and Cock Liver Microsomes: From Chiral Assessment View.

Chiral fosthiazate enters the organisms via environmental exposure and food web enrichment. Liver subcellular fractions of rats (RLM) and cocks (CLM) were prepared to explore the stereoselective metabolism of fosthiazate in vitro. The results indicated that fosthiazate exhibited different stereoselective metabolism behaviors in RLM and CLM. The clearance rate order of RLM to four fosthiazate stereoisomers was (1R,3R)-fosthiazate > (1S,3R)-fosthiazate > (1R,3S)-fosthiazate > (1S,3S)-fosthiazate. However, CLM showed a faster clearance rate to (1S,3S)-fosthiazate and (1S,3R)-fosthiazate than the other two stereoisomers. The molecular docking results revealed that the stereoselectivity was partially due to the stereospecific binding between fosthiazate stereoisomers and cytochrome P450 proteins. The main metabolism pathways of fosthiazate in RLM and CLM were oxidation and hydrolysis with five common metabolites including M299, M243, M227, M103, and M197 being identified by LC-TOF-MS/MS. The present study provides the accurate data on risk assessment of chiral fosthiazate.

Melamine-Doped Covalent Organic Framework Membranes for Enhanced Hydrogen Purification.

Covalent organic frameworks (COFs) are promising materials for membrane separation thanks to their adjustable topological structures and surface properties of nanopores. Herein, a melamine (Me)-doped COF membrane was fabricated by chemically doping the melamine monomer into TpPa COF, which is formed by the condensation reaction between the 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa) monomers via interfacial polymerization. The introduction of melamine monomer allows altering both the pore structure and pore surface of the TpPa COF membrane, leading to enhanced hydrogen purification performance. Specifically, the separation factor of H2 /CO2 gas mixture by using the melamine doped TpPa COF (TpPaMe COF) membrane reaches 12.7, with a hydrogen permeance of 727 GPU, in sharp contrast to the relatively low separation factor and gas permeance of 7.5 and 618 GPU of the undoped TpPa membrane. Besides, the TpPaMe COF membrane shows good running stability, with H2 /CO2 separation performance well surpasses the Robeson 2008 upper bound.

Absolute Configuration, Enantioselective Bioactivity, and Degradation of the Novel Chiral Triazole Fungicide Mefentrifluconazole.

Mefentrifluconazole is a new chiral triazole fungicide with a pair of enantiomers. However, the enantioselective differences in the biological effects and environmental behaviors of mefentrifluconazole are unclear. In the present work, a new simultaneous determination method of mefentrifluconazole enantiomers was established using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The absolute configuration of the two mefentrifluconazole enantiomers was confirmed by comparing the experimental and calculated ECD spectra. The enantioselective bioactivity to target fungi and degradation in cucumber samples were also assessed. The absolute configurations of the two enantiomers eluted on the Superchiral IG-3 column were confirmed as R-(-)-mefentrifluconazole and S-(+)-mefentrifluconazole. The R-(-)-mefentrifluconazole possessed 5-473 times higher bioactivity than S-(+)-mefentrifluconazole toward six kinds of target pathogenic fungi. In addition, R-(-)-mefentrifluconazole exhibited stronger efficacy of suppression of ergosterol biosynthesis. The molecular docking results indicated that R-(-)-mefentrifluconazole had shorter binding distances and lower energies with the target protein than S-(+)-mefentrifluconazole, which may result in the enantioselective bioactivity. The high-efficiency enantiomer of R-(-)-mefentrifluconazole has longer duration in cucumber samples due to the relatively long half-life of 4.0 days. This research has clarified the bioactivity differences and mechanism between mefentrifluconazole enantiomers against target fungi and laid the foundation for an in-depth study of mefentrifluconazole at the chiral level.

Enantioselective Detection, Bioactivity, and Degradation of the Novel Chiral Fungicide Oxathiapiprolin.

Oxathiapiprolin is a novel chiral piperidine thiazole isooxazoline fungicide that contains a pair of enantiomers. An effective analytical method was established for the enantioselective detection of oxathiapiprolin in fruit, vegetable, and soil samples using ultraperformance liquid chromatography-tandem triple quadrupole mass spectrometry. The optimal enantioseparation was achieved on a Chiralpak IG column at 35 °C using acetonitrile and 0.1% formic acid aqueous solution (90:10, v/v) as the mobile phase. The absolute configuration of the oxathiapiprolin enantiomers was identified with the elution order of R-(-)-oxathiapiprolin and S-(+)-oxathiapiprolin by electron circular dichroism spectra. The bioactivity of R-(-)-oxathiapiprolin was 2.49 to 13.30-fold higher than that of S-(+)-oxathiapiprolin against six kinds of oomycetes. The molecular docking result illuminated the mechanism of enantioselectivity in bioactivity. The glide score (-8.00 kcal/mol) for the R-enantiomer was better with the binding site in Phytophthora capsici than the S-enantiomer (-7.50 kcal/mol). Enantioselective degradation in tomato and pepper under the field condition was investigated and indicated that R-(-)-oxathiapiprolin was preferentially degraded. The present study determines the enantioselectivity of oxathiapiprolin about enantioselective detection, bioactivity, and degradation for the first time. The R-enantiomer will be a better choice than racemic oxathiapiprolin to enhance the bioactivity and reduce the pesticide residues at a lower application rate.

Stereoselective environmental fate of fosthiazate in soil and water-sediment microcosms.

The stereoselective fates of chiral pesticides in the environment has been reported in many studies. However, there is little data focused on the fate of chiral fosthiazate in the soil and aquatic ecosystems at chiral view. This study investigated the stereoselective fate of fosthiazate in the soil and aquatic ecosystems using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and liquid chromatography tandem time-of-flight mass spectrometry (LC-TOF/MS/MS). Significant stereoselective degradation among four fosthiazate stereoisomers were found in both greenhouse soil and water-sediment microcosms. In greenhouse soil, (1R,3S)-fosthiazate degraded faster than other three stereoisomers with the half-life of 2.7 d. The fosthiazate stereisomers in the seawater-sediment microcosm degraded more rapidly than in the river water-sediment microcosm. However, (1S,3R)-fosthiazate and (1S,3S)-fosthiazate possessed shorter degradation half-lives than their enantiomers in both microcosms, with the half-lives ranging from 3.4 d to 15.8 d. Ten degradation products were identified in the water-sediment microcosms, and, six of them were reported for the first time. Oxidation and hydrolysis were confirmed as the main degradation pathways of fosthiazate in the water-sediment microcosms. Our results revealed that the (1R,3S)-fosthiazate and (1R,3R)-fosthiazate may cause more serious ecotoxicity due to the longer half-lives than the other two stereoisomers in environment.

Changes in soil and rat gut microbial diversity after long-term exposure to the chiral fungicide epoxiconazole.

In previous articles, it was found that epoxiconazole enantiomers can persist for a long time in the environment, causing severe environmental damage. Herein, we investigated alterations in the soil microbial community and rat gut microbiota after six weeks of treatment with rac-epoxiconazole or one of its enantiomers. The selected concentrations were 1, 2, and 6 times greater than the maximum residue limits (MRLs). The rat gut microbiota relative abundance in the feces significantly changed following exposure to rac-epoxiconazole or one of its enantiomers. At the phylum level, in the R,S-, S,R-epoxiconazole, and rac-treated groups, Firmicutes presented the greatest decrease in abundance; however, Spirochaetes presented the greatest increase in abundance in the rac- and S,R-epoxiconazole-treated groups. In response to R,S-epoxiconazole, Epsilonbacteraeota presented the greatest increase in abundance. In soil samples treated with epoxiconazole, the relative abundance of the soil bacterial community also changed. Proteobacteria presented the greatest decrease in abundance in the S,R- and rac-treated samples. However, Firmicutes presented the greatest increase in abundance. In the R,S-treated soil samples, the situation was the opposite. In general, prolonged exposure to epoxiconazole at high concentrations could initiate noticeable alterations in rat gut microbiota and soil microbial diversity. R,S-epoxiconazole had improved bioactivity and less toxic effects at relatively low concentrations. Therefore, we recommend using R,S-epoxiconazole at a relatively low concentration, which is better for environmental safety.

Toxicity effects of procymidone, iprodione and their metabolite of 3,5-dichloroaniline to zebrafish.

Dicarboximide fungicides mainly including procymidone, iprodione, vinclozolin, and dimethachlon are often applied as protective fungicides, 3,5-dichloroaniline (3,5-DCA) is their common metabolite in plant and environment. In this study, the acute toxicity of procymidone, iprodione and their metabolite of 3,5-DCA toward zebrafish was evaluated by semi-static method. The enrichment and metabolism of procymidone and iprodione in zebrafish were also clarified. The results indicated that procymidone and iprodione exhibited moderately toxic to adult zebrafish with the LC50 of 2.00 mg/L, 5.70 mg/L at 96 h. Both procymidone and iprodione could be metabolized to 3,5-DCA in zebrafish, which showed higher toxic to adult zebrafish with the LC50 of 1.64 mg/L at 96 h. From the perspective of histomorphology, for all treatment groups, the brain of the zebrafish was significantly damaged, while the damage to gut and gills was lighter. For procymidone, the biological concentration factor (BCF8d) were 236 and 246 at the exposure concentration of 0.2 mg/L and 0.04 mg/L, and the BCF8d were 3.2 and 2.4 for iprodione at the exposure concentration of 0.5 mg/L and 0.1 mg/L. Therefore, the procymidone and iprodione were moderate-enriched and low-enriched in zebrafish, respectively.

Covalent organic framework membrane for size selective release of small molecules and peptide in vitro.

The ability to control small drug release is crucial in biomedicine, especially for inhibiting the side effects of drugs, but it is still challenging. Herein, to mimic the controlled release of drugs, the release of organic molecules, e.g., small organic dyes and peptides, through Covalent Organic Framework (COF) membranes with ordered nanoscale pores has been investigated, showing constant zero-order release behaviours. Meanwhile, biological assessments show the good biocompatibility of the COF membrane-based release system, and the high stability of the COF membrane was manifested by the long-term release of small molecules in aqueous media.

Enantioselective disposition and metabolic products of isofenphos-methyl in rats and the hepatotoxic effects.

Isofenphos-methyl (IFP), a chiral organophosphorus pesticide, is one of the main chemicals used to control underground insects and nematodes. Recently, the use of IFP on vegetables and fruits has been prohibited due to its high toxicity. In this study, we investigated the enantioselective distribution and metabolism of IFP and its metabolites, namely, isofenphos-methyl oxon (IFPO) and isocarbophos oxon (ICPO), in male Sprague Dawley (SD) rats. Forty eight hours (48 h) after exposure, ICPO was the main detectable compound in blood (up to 75%) and urine (up to 77%), and we found that (S)-ICPO was significantly more stable than (R)-ICPO (p < 0.05). Therefore, (S)-ICPO was proposed as a suitable candidate biomarker for the biomonitoring of IFP in human urine and blood. After 48 h exposure, 21.2-41.0%, 4.1-15.1%, and 8.6-18.7% of dosed IFP was detected in the liver of racemic, R and S enantiomer-exposed rats, respectively, and R-IFP and R-IFPO showed a faster degradation (p < 0.05). Our results showed that after one week of consecutive exposure to IFP, ICPO was accumulated in the liver of rats in both racemic and enantiopure groups (no difference between the groups, p > 0.05). We found that cytochrome P450 (CYP) (i.e. CYP2C11, CYP2D2 and CYP3A2 enzymes and carboxylesterases) is responsible for the enantioselective metabolism of IFP in liver. In addition, rats exposed to (S)-IFP exhibited hepatic lipid peroxidation, liver inflammation and hepatic fibrosis. This study provides useful information and a reference for the biomonitoring and risk assessment of IFP and organophosphorus pesticide exposure.

Stereoselective environmental behavior and biological effects of the chiral bitertanol.

Bitertanol is a widely used chiral triazole fungicide. The stereoselective environmental behavior and biological effects of bitertanol are not clear. The present study evaluated the stereoselectivity of bitertanol, including its degradation in five typical soils (under laboratory controlled aerobic, anaerobic and sterilization conditions), metabolism in rat liver microsomes (RLM; in vitro), and the endocrine disruption effects on the estrogen receptor (ER) and thyroid hormone receptor (TR) using reporter gene assays. The results indicated that (1S,2R)-bitertanol and (1R,2S)-bitertanol had faster degradation rates in soil than the other stereoisomers. The half-lives of four bitertanol stereoisomers ranged from 9.1 d to 86.6 d in different soils under different conditions. (1S,2R)-bitertanol was preferentially metabolized in RLM. The molecular docking results confirmed the in vitro experiments that (1S,2R)-bitertanol had shortest binding distances and lowest energies with cytochrome P450 enzymes (CYPs). Four bitertanol stereoisomers showed stereoselective antagonistic effects on ER. Additionally, (1S,2R)-bitertanol and (1R,2S)-bitertanol exhibited antagonistic effects on TR. These results suggest that the use of pure (1S,2R)-bitertanol instead of the commercial stereoisomer mix, may help reduce environmental pollution and biological toxicity.

Chiral Organophosphorous Pesticide Fosthiazate: Absolute Configuration, Stereoselective Bioactivity, Toxicity, and Degradation in Vegetables.

Fosthiazate is a widely used chiral organophosphorous nematicide with four stereoisomers. The present study systemically assessed the stereoselectivity of fosthiazate for the first time, including absolute configuration confirmation, stereoselective bioactivity toward nematode and aphid, toxicity to honeybees, and stereoselective degradation in cucumber and pepper under field conditions. The absolute configurations of the four stereoisomers that eluted on the Superchiral IG-3 column were confirmed as (1S,3R)-(-)-fosthiazate, (1S,3S)-(-)-fosthiazate, (1R,3S)-(+)-fosthiazate, and (1R,3R)-(+)-fosthiazate. In comparison to the other two stereoisomers, (1S,3R)-fosthiazate and (1S,3S)-fosthiazate possess more than 100 times bioactivity and 10 times toxicity toward the target and non-target organisms, respectively. The molecular docking found that (1S,3R)-fosthiazate and (1S,3S)-fosthiazate had shorter binding distances and lower energies with acetylcholinesterase (AChE), which illuminated the mechanism of the experimental results. In addition, both of the high-bioactive stereoisomers had faster degradation rates in cucumber and pepper. On the basis of the results of bioactivity, toxicity, and degradation behavior, the stereoisomer mixture with (1S,3R)-fosthiazate and (1S,3S)-fosthiazate will be a better option than racemic fosthiazate to increase the bioactivity and reduce application rates.