Thin-wall hollow porous cystic-like graphitic carbon nitride with awakened n→π* electronic transitions and exceptional structural features for superior photocatalytic degradation of sulfamethoxazole.

Effective photoexcitation and carrier migration are the essential aspects to strengthen semiconductor-engaged redox reaction. Herein, a three-dimensional thin-wall hollow porous cystic-like g-C3N4 (HPCN) with curved layer edge was successfully fabricated via a non-template thermal-condensation strategy. The construction of unique distorted structure can evoke the hard-to-activate n→π* electronic transition to some extent, broadening the absorption spectrum to 800 nm. And benefiting from the multiple reflections of incident light, the effective photoactivation can be further achieved. Moreover, the thin-wall porous framework can shorten the diffusion distance and accelerate migration of photogenerated charge, favouring interfacial redox reactions. The optimized HPCN1.0 demonstrated an excellent photocatalytic degradation of SMX under blue-LED light irradiation, which was dramatically superior to that of pristine g-C3N4 (CN, 11.4 times). Ultimately, in consideration of reactions under several influencing factors with four different water samples, we demonstrated that the HPCN photocatalyst could be utilized far more productively for the elimination of SMX under real-world aqueous conditions. This work provides a straightforward approach for the removal of SMX and has immense potential to contribute to global scale environmental remediation.

Activation of peracetic acid via Co3O4 with double-layered hollow structures for the highly efficient removal of sulfonamides: Kinetics insights and assessment of practical applications.

Sulfonamides (SAs) have been of ecotoxicological concern for ambient ecosystems due to their widespread application in the veterinary industry. Herein, we developed a powerful advanced oxidation peracetic acid (PAA) activation process for the remediation of SAs by Co3O4 with double-layered hollow structures (Co3O4 DLHSs). Systematic characterization results revealed that the polyporous hollow hierarchical structure endows Co3O4 DLHSs with abundant active reaction sites and enhanced mass transfer rate, which were conducive for improving the PAA activation efficiency. Laser flash photolysis experiment and mechanism studies indicated that organic radical species were dominant reactive species for SAs removal. The present system is also highly effective under natural water matrices and trace SAs concentration (20 µg/L) condition. More importantly, the chlorella acute toxicity of the SAs solution was eliminated during mineralization process, supporting this catalytic system may be efficaciously applied for the remediation of SAs contamination in ambient waterways.

Analysis of azole fungicides in fish muscle tissues: Multi-factor optimization and application to environmental samples.

Azole fungicides have been reported to be accumulated in fish tissue. In this study, a sensitive and robust method using high-performance liquid chromatography-tandem mass spectrometry combined with ultrasonic extraction, solid-liquid clean-up, liquid-liquid extraction and solid-phase extraction (SPE) for enrichment and purification have been proposed for determination of azole fungicides in fish muscle samples. According to the results of non-statistical analysis and statistical analysis, ethyl acetate, primary secondary amine (PSA) and mixed-mode cation exchange cartridge (MCX) were confirmed as the best extraction solvent, clean-up sorbent and SPE cartridge, respectively. The satisfied recoveries (81.7-104%) and matrix effects (-6.34-7.16%), both corrected by internal standards, were performed in various species of fish muscle matrices. Method quantification limits of all azoles were in the range of 0.07-2.83ng/g. This optimized method was successfully applied for determination of the target analytes in muscle samples of field fish from Beijiang River and its tributaries. Three azole fungicides including climbazole, clotrimazole and carbendazim were detected at ppb levels in fish muscle tissues. Therefore, this analytical method is practical and suitable for further clarifying the contamination profiles of azole fungicides in wild fish species.

Enhanced bioelectricity generation and azo dye treatment in a reversible photo-bioelectrochemical cell by using novel anthraquinone-2,6-disulfonate (AQDS)/MnOx-doped polypyrrole film electrodes.

A novel anthraquinone-2,6-disulfonate/MnOx-doped polypyrrole film (AQDS/Mn/PPy) electrode was prepared by one-step electropolymerization method and was used to improve performance of a reversible photo-bioelectrochemical cell (RPBEC). The RPBEC was operated in polarity reversion depended on dark/light reaction of alga Chlorella vulgaris by which sequential decolorization of azo dye and mineralization of decolorization products coupled with bioelectricity generation can be achieved. The results showed that formation of uniform AQDS/Mn/PPy film significantly enhanced electroactive surface area and electrocatalytic activity of carbon electrode. The RPBEC with AQDS/Mn/PPy electrodes demonstrated 77% increases in maximum power and 73% increases in Congo red decolorization rate before polarity reversion, and 198% increases in maximum power and 138% increases in decolorization products mineralization rate after polarity reversion, respectively, compared to the RPBEC with bare electrode. This was resulted from simultaneous dynamics improvement in half-reaction rate of anode and photo-biocathode due to enhanced electron transfer and algal-bacterial biofilm formation.

Photodegradation of naproxen in water under simulated solar radiation: mechanism, kinetics, and toxicity variation.

The main objective of this study was to investigate the degradation mechanism, the reaction kinetics, and the evolution of toxicity of naproxen in waters under simulated solar radiation. These criteria were investigated by conducting quenching experiments with reactive oxygen species (ROS), oxygen concentration experiments, and toxicity evaluations with Vibrio fischeri bacteria. The results indicated that the degradation of naproxen proceeds via pseudo first-order kinetics in all cases and that photodegradation included degradation by direct photolysis and by self-sensitization via ROS; the contribution rates of self-sensitized photodegradation were 1.4%, 65.8%, and 31.7% via ·OH, (1)O2 and O2(•-), respectively. Furthermore, the oxygen concentration experiments indicated that dissolved oxygen inhibited the direct photodegradation of naproxen, and the higher the oxygen content, the more pronounced the inhibitory effect. The toxicity evaluation illustrated that some of the intermediate products formed were more toxic than naproxen.

Structural mechanism of CCM3 heterodimerization with GCKIII kinases.

Mutation of CCM3 causes cerebral cavernous malformations of the vasculature, leading to focal neurological deficits, seizures, and hemorrhagic stroke. CCM3 can heterodimerize with GCKIII kinases (MST3, MST4, and STK25) to regulate cardiovascular development. Here, we provide direct experimental evidence to prove that CCM3 heterodimerizes with GCKIII in a manner structurally resembling the CCM3 homodimerization. Structural comparison revealed the mechanism and critical residues that drive CCM3-GCKIII heterodimerization versus homodimerization. A flexible linker was identified for CCM3, which mediates a large-scale conformational rotation of the FAT domain relative to the dimerization domain. The conformational flip over of FAT domain removes steric locking in the CCM3 homodimer and allows its disassembly and subsequent heterodimerization with GCKIII. CCM3 forms a stable complex with MST4 in vivo to promote cell proliferation and migration synergistically in a manner dependent on MST4 kinase activity. Collectively, our work offers a structural basis for further functional study.

Structural insights into SUN-KASH complexes across the nuclear envelope.

Linker of the nucleoskeleton and the cytoskeleton (LINC) complexes are composed of SUN and KASH domain-containing proteins and bridge the inner and outer membranes of the nuclear envelope. LINC complexes play critical roles in nuclear positioning, cell polarization and cellular stiffness. Previously, we reported the homotrimeric structure of human SUN2. We have now determined the crystal structure of the human SUN2-KASH complex. In the complex structure, the SUN domain homotrimer binds to three independent "hook"-like KASH peptides. The overall conformation of the SUN domain in the complex closely resembles the SUN domain in its apo state. A major conformational change involves the AA'-loop of KASH-bound SUN domain, which rearranges to form a mini ß-sheet that interacts with the KASH peptide. The PPPT motif of the KASH domain fits tightly into a hydrophobic pocket on the homotrimeric interface of the SUN domain, which we termed the BI-pocket. Moreover, two adjacent protomers of the SUN domain homotrimer sandwich the KASH domain by hydrophobic interaction and hydrogen bonding. Mutations of these binding sites disrupt or reduce the association between the SUN and KASH domains in vitro. In addition, transfection of wild-type, but not mutant, SUN2 promotes cell migration in Ovcar-3 cells. These results provide a structural model of the LINC complex, which is essential for additional study of the physical and functional coupling between the cytoplasm and the nucleoplasm.

Flocculation mechanism by a novel combined aluminum-ferrous-starch flocculant (CAFS).

A combined flocculant (CAFS) was prepared with Al(2)(SO(4))(3)·18H(2)O, FeSO(4)·7H(2)O and starch. The flocculation mechanism of reactive brilliant red X-3B was studied. The results showed that CAFS was a cationic polymeric flocculant with high charge density, and its mesh starch chains grafted polyaluminum and polyferrous. At the preliminary stage, the main flocculation mechanism was adsorption and charge neutralization. At a later stage, the high molecular weight and flexible linear chains of CAFS initiated bridge-aggregation and sweep-flocculation. Moreover, the zeta potential and dynamic changes of flocs were closely related to flocculant dosages and the pH. The optimum dosage of CAFS and pH value were 0.990 mg/L and 5.0. Taken together, these results suggested CAFS as a novel flocculant in water treatment, with good results for the studied conditions.

Calculation of the peak concentration of 2-chlorobenzamide generated in the hydrolysis of the benzoylphenylurea insecticide 1-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea.

1-(2-chlorobenzoyl)-3-(4-chlorophenyl)urea (CCU), a new analogue of diflubenuron and PH-6038, has been widely used in agriculture and forestry as a molt-inhibiting hormone insecticide which was developed in China. 2-Chlorobenzamide, a main degradation product of CCU in the environment, has been identified as a potential carcinogen, so the content of 2-chlorobenzamide from the breakup of CCU will directly affect the environmental safety of CCU. In this paper we describe a simple, rapid, and convenient prediction model for predicting the level and time of occurrence of the peak concentration of 2-chlorobenzamide in the hydrolysis of CCU verified by experimental data. The time for reaching the peak concentration of 2-chlorobenzamide (tm) at 25 degrees C and pH 6 is 13.5 d, and the maximum concentration of 2-chlorobenzamide (ym) is 3.2% of the initial concentration of CCU according to the results from the prediction model. These results are similar to the real values from the experiments, which are 22 d and 1.6% of the initial concentration of CCU, respectively. The difference between the values of the prediction and experiment is discussed, and it is demonstrated that the predicting model is highly credible.

Study of the concentration and separation of cadmium with microcrystalline phenolphthalein modified by crystal violet.

A new method for cadmium separation and concentration with microcrystalline phenolphthalein modified by crystal violet (CV) was developed in the paper. In the presence of potassium iodide (KI) and CV, cadmium are quantitatively absorbed on microcrystalline phenolphthalein in the pH range 1.0-6.0 as the forms of water-insoluble ion-associated complexes (CdI(3)(-)).(CV(+)) and (CdI(4)(2-)).(CV(+))(2). Effect of different parameters such as phenolphthalein amount, stirring time, the concentration of CV and KI, various salts and metal ions was studied in detail. During the present study, a significant enhancement of the extraction of cadmium was observed. Cd(II) can be completely separated from Zn(II), Fe(II), Co(II), Ni(II), Mn(II), Cr(III) and Al(III) in this microcrystalline system and well concentrated without the interference of these metal ions at high level. The possible reactive mechanism of cadmium concentration has been discussed. Analytical results obtained by this new method were very gratifying.