Cry Toxins Use Multiple ATP-Binding Cassette Transporter Subfamily C Members as Low-Efficiency Receptors in Bombyx mori.

Recent studies have suggested that ABC transporters are the main receptors of Cry toxins. However, the receptors of many Cry toxins have not been identified. In this study, we used a heterologous cell expression system to identify Bombyx mori ABC transporter subfamily C members (BmABCCs) that function as receptors for five Cry toxins active in Lepidopteran insects: Cry1Aa, Cry1Ca, Cry1Da, Cry8Ca, and Cry9Aa. All five Cry toxins can use multiple ABCCs as low-efficiency receptors, which induce cytotoxicity only at high concentrations. Surface plasmon resonance analysis revealed that the KD values between the toxins and BmABCC1 and BmABCC4 were 10-5 to 10-9 M, suggesting binding affinities 8- to 10,000-fold lower than those between Cry1Aa and BmABCC2, which are susceptibility-determining receptors for Cry1Aa. Bioassays in BmABCC-knockout silkworm strains showed that these low-efficiency receptors are not involved in sensitivity to Cry toxins. The findings suggest that each family of Cry toxins uses multiple BmABCCs as low-efficiency receptors in the insect midgut based on the promiscuous binding of their receptor-binding regions. Each Cry toxin seems to have evolved to utilize one or several ABC transporters as susceptibility-determining receptors.

Theoretical prediction of two-dimensional ferromagnetic Mn2X2 (X = As, Sb) with strain-controlled magnetocrystalline anisotropy.

Two-dimensional (2D) magnetic materials with large and tunable magnetocrystalline anisotropy (MCA) provide unique opportunities to develop various spintronic devices. We, herein, propose an experimentally feasible 2D material platform, Mn2X2 (X = As, Sb), which is a family of intrinsic ferromagnet. Using first-principles calculations, we show that 2D Mn2X2 (X = As, Sb) with a robust ferromagnetic ground state exhibits not only a large perpendicular magnetic anisotropy (PMA), but also significant strain-driven modulation behaviors under external biaxial strain. The analysis of the results demonstrates that the dominant contribution to the change of MCA of Mn2As2 and Mn2Sb2 primarily arises from the Mn and Sb atoms, respectively. Moreover, we reveal that the underlying origin is the competitive mechanism for the spin-orbit coupling (SOC) between different orbitals and spin channels. These findings indicate that 2D Mn2X2 (X = As, Sb) provides a promising material platform for the next generation of ultra-low energy memory devices.

Intrinsic ferromagnetism in two-dimensional 1T-MX2 monolayers with tunable magnetocrystalline anisotropy.

Two-dimensional (2D) ferromagnetic materials with tunable magnetocrystalline anisotropy (MCA) provide unique opportunities for developing the next-generation data-storage and information devices. Herein we systematically investigate the electronic and magnetic properties of the 1T-MX2 (M = Cr, Mn, Fe, Co; X = As, Sb) monolayers, and identify the stable 2D ferromagnets as well as their MCA energies. Notably, the results demonstrate that the biaxial strain and carrier doping effects have a significant influence on their magnetic behaviors. In addition to the robust FM states, three FM monolayers yield tunable MCA depending on the applied strain type and carrier doping values. The dominant contributions to these complicated modifications in MCA are mainly attributed to the strain or carrier doping induced alterations of specific M-derived 3d states, which in turn lead to the changes of their spin-orbit coupling (SOC) energies. These findings show effective approaches to control 2D magnetism and suggest that these 2D FM materials may be promising candidates to design highly efficient memory devices.

Upconversion luminescence nanosensor for detection of Fe3+ and phosphate ion based on the inner-filter effect.

In this work, an upconversion luminescence (UCL) nanosensor for fast detection of ferric ion (Fe3+) and phosphate ion (Pi) is developed based on the inner-filter effect (IFE) between NaYF4:Yb/Er upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex. Fe3+-HB complex has strong absorption band (450-650 nm), which overlaps with the green emission peak of UCNPs at 545 nm. By adding Fe3+ and Pi, the UCNPs-HB system produces the red-shift change of absorption spectrum, which leads to the "on-off-on" process of IFE. So, with the specific recognition ability of HB for Fe3+ and the competitive complexation of Pi for Fe3+, the proposed nanosensor utilizes the UCL change to achieve the detection of the targets. For the detections of Fe3+, the linear range is 10-600 µM with a limit of detection (LOD) of 2.62 µM, and for Pi, the linear range is 5-100 µM with a LOD of 1.25 µM. The results for selectivity, precision, and recovery test are also satisfactory. Furthermore, the real sample detection shows that the proposed nanaosensor has a great potential in environmental and biological systems. An upconversion luminescence (UCL) nanosensor based on the inner-filter effect (IFE) between upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex for the detection of Fe3+ and phosphate ion has been proposed, which is promising to be a convenient and sensitive assay for monitoring Fe3+ and phosphate ion in different environments and biological systems.

Low-coordinated Co-N3 sites induce peroxymonosulfate activation for norfloxacin degradation via high-valent cobalt-oxo species and electron transfer.

The identification of reactive species in peroxymonosulfate (PMS) activation triggered by carbon-based single atom catalysts is the key to reveal the pollutant degradation mechanism. Herein, carbon-based single atom catalyst with low-coordinated Co-N3 sites (CoSA-N3-C) was synthesized to active PMS for norfloxacin (NOR) degradation. The CoSA-N3-C/PMS system exhibited consistent high performance for oxidizing NOR over a wide pH range (3.0-11.0). The system also achieved complete NOR degradation in different water matrixes, high cycle stability and excellent degradation performance for other pollutants. Theoretical calculations confirmed that the catalytic activity was derived from the favorable electron density of low-coordinated Co-N3 configuration, which was more conductive to PMS activation than other configurations. Electron paramagnetic resonance spectra, in-situ Raman analysis, solvent exchange (H2O to D2O), salt bridge and quenching experiments concluded that high-valent cobalt(IV)-oxo species (56.75%) and electron transfer (41.22%) contributed dominantly to NOR degradation. Moreover, 1O2 was generated in the activation process while not involved in pollutant degradation. This research demonstrates the specific contributions of nonradicals in PMS activation over Co-N3 sites for pollutant degradation. It also offers updated perceptions for rational design of carbon-based single atom catalysts with appropriate coordination structure.

Oxidative Three-Component Selenofunctionalization of Alkenes: Convenient Access to Vicinally Functionalized Selenides.

Three-component selenofunctionalization processes of olefins, diselenides and sulfonamides, water, alcohols, or acids utilizing 1-fluoropyridinium triflate (FP-OTf) as a reaction promoter are reported. Under the optimal conditions, a broad range of vicinally functionalized selenide derivatives was accessible with high yields and excellent functional group compatibilities. Mechanistic studies revealed that the FP-OTf played a key role in this selenofunctionalization process.

Photocatalytic Aerobic Cyclization of N-Propargylamides Enabled by Selenium-π-Acid Catalysis.

A dual catalytic approach combining photocatalyst and selenium-π-acid synergy has been used to cyclized of N-propargylamides. This method offers readily access to oxazole aldehydes under chemical oxidant-free conditions with low catalyst loadings, where air acts as a terminal and gratuitous oxidant. The reaction is demonstrated with a range of substrates, including aryl and alkyl propargyl amides, and in the late-stage functionalization of several amide-containing drug molecules. Mechanistic studies suggest that the acridinium catalyst is able to oxidize diselenide and generate singlet oxygen (1 O2 ), which is responsible for this transformation.

Evolutionary analysis of resident groups' intention to participate in green retrofit PPP projects of traditional apartment complexes.

Green retrofit PPP projects of traditional apartment complexes play an important role in promoting the green and low-carbon transformation of the construction industry and achieving China's "double carbon" goals. The integrated retrofit of apartment complexes presupposes that the resident groups agree to the retrofit. Therefore, it is necessary to study the evolutionary mechanism of residents' intention to green retrofit and the transformation process of their behavior, and to explore how to enhance residents' intention to participate. First, the dissemination model of residents' intention to green retrofit is constructed. Then, the strategic interaction among government, social capitals and residents under the PPP model is introduced into the dissemination model to define the state transformation probability of resident groups. Finally, the evolution laws of residents' intention to green retrofit are analyzed. The results show that: (1) the behavior of government regulation and social capitals' effort to retrofit can motivate the number of the resident agreeing to green retrofit to meet the proportional limit, (2) the faster the government chooses the strategy of regulation and the social capitals choose the strategy of effort to retrofit, the faster the number of residents agreeing to green retrofit reaches a steady state, (3) when the level of government publicity and education is too low, the cost of government regulation or the subsidy given to residents is too high, the green retrofit of traditional apartment complexes cannot be achieved. The research conclusions can provide a reference for the government to formulate green retrofit policies.

N-Fluorobenzenesulfonimide-Mediated Intermolecular Carboselenenylation of Olefins with Aromatics and Diselenides.

Intermolecular carboselenenylation of easily accessible alkenes by utilizing diselenides and N-fluorobenzenesulfonimide (NFSI) under metal-free and mild conditions is reported. Preliminary mechanistic studies indicate that the oxidation of diselenide by NFSI through a single-electron-transfer process produces an active selenenyl cationic radical species that initiates the intermolecular carboselenenylation of olefins, forming key Se-C and C-C bonds. Under optimized conditions, a broad spectrum of functionally and structurally diverse selenoether derivatives with promising yields is accessed with a very high functional group tolerance.

3D Cube FLAIR plus HyperSense compressed sensing is superior to 2D T2WI FLAIR scanning regarding image quality, spatial resolution, detection rate for cortical microinfarcts.

3-dimention (3D) Cube isotropic volumetric magnetic resonance imaging (MRI) facilitates comprehensive recognition of microinfarcts while it takes long scanning time. HyperSense compressed sensing is an emerging technique for accelerating MRI acquisition to reduce scanning time, while its application along with 3D Cube MRI for microinfarcts is seldom reported. Therefore, this study aimed to investigate the efficiency of 3D Cube FLAIR plus HyperSense compressed sensing technique versus conventional 2-dimention (2D) FLAIR scanning in the detection of cortical microinfarcts (CMIs). Totally 59 patients with cerebrovascular disease were enrolled then scanned by 3D Cube FLAIR plus HyperSense compressed sensing and 2D T2WI FLAIR sequences. The image quality scores, signal-to-noise ratio (SNR) for gray matter (GM), SNR for white matter (WM), their contrast-to-noise ratio (WM-to-GM CNR), detected number of CMIs were evaluated. 3D Cube FLAIR plus HyperSense showed a dramatically increased scores of uniformity, artifact, degree of lesion displacement, and overall image quality compared to 2D T2WI FLAIR. Meanwhile, it exhibited similar SNRwm and SNRgm, but a higher WM-to-GM contrast-to-noise ratio compared with 2D T2WI FLAIR. Furthermore, the scanning time of 3D Cube FLAIR plus HyperSense and 2D T2WI FLAIR were both set as 2.5 minutes. Encouragingly, 244 CMIs were detected by 3D Cube FLAIR plus HyperSense, which was higher compared to 2D T2WI FLAIR (106 detected CMIs). 3D Cube FLAIR plus HyperSense compressed sensing is superior to 2D T2WI FLAIR scanning regarding image quality, spatial resolution, detection rate for CMIs; meanwhile, it does not increase the scanning time. These findings may contribute to early detection and treatment of stroke.

Magnetic Resonance Imaging combined with Computed Tomography in the Diagnosis of Multiple Myeloma and the Killing Effect of Doxorubicin Nano-drug Delivery System on Myeloma Cells.

It was to adopt magnetic resonance imaging (MRI) combined with computed tomography (CT) to diagnose multiple myeloma (MM) and evaluate the therapeutic effect of the doxorubicin nano-drug delivery system on MM, providing a more effective method for the treatment of MM. For this aim, eighty-eight patients with MM admitted to our Hospital from June 2019 to July 2020.7 were selected as study subjects and divided into a control group (treated with doxorubicin) and an observation group (treated with doxorubicin-loaded nanoparticles) according to the random number table, 44 cases for each group. MRI and CT were used to examine the two groups of patients to assess the clinical efficacy and side effects of the two treatments and to compare the myeloma cell survival rate and apoptosis rate. Results showed that the diameter of nanoparticles was about 50 nm, the particle size was uniform, the distribution was dense, and the stability was good; the lesion was well-circumscribed on CT scan, and a soft tissue mass could be detected on MRI. The number of patients with effective treatment in the observation group was significantly higher than that in the control group (42 cases vs 34 cases) (P< 0.05); the number of patients with small plate reduction, increased myocardial enzymes, alopecia, liver failure, gastrointestinal reactions, peripheral neuritis, and other adverse reactions in the observation group was significantly lower than that in the control group (total number of patients 48 vs 101) (P< 0.05); the survival rate of myeloma cells in the observation group was obviously inferior to that in the control group (61.3 % vs 88.31 %) (P< 0.05). Conclusion: MRI combined with CT examination can be better used for the diagnosis of the disease, and the study shows that doxorubicin nano-drug delivery preparation is safer and more effective in the treatment of MM disease, which is worthy of clinical promotion.

Iodine pentoxide-mediated oxidative selenation and seleno/thiocyanation of electron-rich arenes.

A simple and efficient method for the regioselective selenation of electron-rich arenes by employing non-metal inorganic iodine pentoxide (I2O5) as a reaction promoter under ambient conditions has been developed. The present protocol showed broad functional group tolerance and easy-to-operate and time-economical features. Additionally, this protocol also allows access to 3-seleno and 3-thiocyanoindoles by the use of readily available selenocyanate and thiocyanate salts. A mechanistic study indicated that the transformation operated through selenenyl iodide-induced electrophilic substitution processes.

Fe@Fe2O3-loaded biochar as an efficient heterogeneous Fenton catalyst for organic pollutants removal.

With increased demand for various chemical raw materials, sudden pollution incidents are more prone to occur during their transportation and usage, threatening the environment and human health. In this study, discarded tea stalks were recycled into composite materials (FSC-X00: X represents the calcination temperature) by impregnating tea stalks in Fe2+ solution combined with subsequent calcination. X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) patterns verified the existence of Fe0 and Fe2O3, and Fe2O3 was gradually reduced to Fe0 when the calcination temperature was raised from 700 °C to 900 °C. FSC-X00 was adopted as a heterogeneous catalyst for activating H2O2 to quickly degrade phenol in the water system. The degradation experiments indicated that FSC-600 exhibited superior degradation performance for phenol (20 mg/L) within 5 min and 80% total organic carbon (TOC) removal rate at pH = 3 within 30 min. The effects of the calcination temperature, the pH value and the amount of H2O2 on the degradation efficiency were investigated. Competing experiments showed that fulvic acid (FA) and inorganic salts Na+ had little effect on the degradation performance. The FSC-600 catalyst can be reused by thermal reduction. In addition, it was found that FSC-600 has a good degradation effect on ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENR), indicating that FSC-600 catalysts are a promising candidate for quick degradation of organic pollutants by Fenton reaction. Electron paramagnetic resonance (EPR) spectra analysis indicated that •OH is the dominant reactive oxygen species (ROS) and part 1O2 from O2 also participated in the degradation. This study provides an example of creating catalysts from organic solid waste for use in emergency treatment for phenol.

Distribution Characteristics of Sub-Surface Cracks in Fused Quartz Ground with Different Worn Wheels.

The crack distribution characteristics in grinding damage have a significant impact on subsequent polishing efficiency and part strength. Grinding tests were carried out on fused quartz using grinding wheels with different wear states. The results showed that the cracks produced by sharp abrasive grits were mainly near chevron cracks and had no preferred direction. However, the blunt abrasive grits produced near partial cone cracks had a preferred direction. At a depth of 96.7 µm from the surface, the amount of cracks in the range of 50°~90° with an inclination angle between the crack and the cutting direction could reach 88.9%. The statistical results showed that the depth and total length of cracks produced by sharp grits were larger than those produced by blunt grits (the maximum crack depth difference was about 40 µm). Therefore, it was concluded that sharp abrasive grits were not conducive to damage control. The findings of this research enhance our understanding of the formation mechanism of grinding damage.

ATP-binding cassette transporter subfamily C members 2, 3 and cadherin protein are susceptibility-determining factors in Bombyx mori for multiple Bacillus thuringiensis Cry1 toxins.

Field-evolved resistance of insect pests to Bacillus thuringiensis (Bt) toxins (Cry toxins) is a threat to the efficacy of Bt-based bio-insecticides and transgenic crops. Recent reports have suggested that ATP-binding cassette transporter subfamily C2 (ABCC2) and cadherin-like receptor play important roles in conferring susceptibility to Cry1 toxins. However, the receptors involved in Bt susceptibility in each insect remain unclear. To determine the receptors that are involved in the susceptibility of Bombyx mori to Cry1 toxins (1Ab, 1Ac and 1Fa), we conducted diet overlay bioassay using B. mori strains disrupted with one or two receptor (s) among BmABCC2, BmABCC3, and cadherin-like receptor (BtR175) generated by transcription activator-like effector nuclease (TALEN)-mediated gene editing. The single-knockout strains for BmABCC2 showed resistance to Cry1Ab and Cry1Ac, whereas only strains with double knockout of BmABCC2 and BmABCC3 exhibited high resistance to Cry1Fa. Progeny populations generated from the crossing of heterozygotes for BtR175 knockout allele included 25% theoretical homozygotes for the BtR175 knockout allele and they showed resistance to Cry1Ab and Cry1Ac. Then, through a cell swelling assay using Sf9 cells ectopically expressing the receptor, we analyzed the mechanisms underlying the different contributions of BmABCC2, BmABCC3, and BtR175 to larval susceptibility. The receptor activity of BmABCC2 for Cry1Ab and Cry1Ac was far higher than that of BmABCC3, and BtR175 synergistically enhanced the receptor activity of BmABCC2. This result well explained the important involvement of BmABCC2 and BtR175 in the larval susceptibility to Cry1A toxins. By contrast, the receptor activities of BmABCC2 and BmABCC3 for Cry1Fa were observed at a similar level and synergistic effect of BtR175 was small. This finding explains the equal importance of BmABCC2 and BmABCC3 and very small contribution of BtR175 on larval susceptibility to Cry1Fa. Thus, we demonstrated the different importance of BmABCC2, BmABCC3, and BtR175 to various Cry1 toxins as susceptibility-determining factors in B. mori larvae and the underlying basis for the observed differences. Furthermore, a weak correlation was indicated between the binding affinity and receptor activities of BmABCC2 and BmABCC3 to Cry1 toxins.

Application study of 3D LAVA-Flex on lumbar intervertebral disc degeneration.

BACKGROUND: Degeneration of the intervertebral discs are very common diseases, indicating the specific or malignant changes in intervertebral disc component, structure and function. Imaging examination is currently used to evaluate the severity of lumbar intervertebral disc degeneration. This study was designed to investigate the diagnostic value of 3D LAVA-Flex in lumbar intervertebral disc degeneration. MATERIAL AND METHODS: Sagittal 3D LAVA-Flex and T2WI scans were performed in 45 patients with lumbar intervertebral disc degeneration. On T2WI, the degenerated intervertebral disc in every patient was evaluated using Pfirrmann grade. Then, the patients were re-evaluated using 3D LAVA-Flex with considerations of the distinction of nucleus pulposus and annulus fibrosus, hypointense signal of intervertebral disc and height of intervertebral disc. The evaluation results were compared between 3D LAVA-Flex and T2WI. Virtual endoscopy was also performed to evaluate the degenerated intervertebral disc. RESULTS: The intermediate-intense signal of nucleus pulposus and complete ring-shaped hyperintense signal of annulus fibrosus were found and the distinction of nucleus pulposus and annulus fibrosus was clear in the normal intervertebral disc on 3D LAVA-Flex. The incidence of linear hypointensity of narrowed intervertebral space (65/91) was higher than that of normal intervertebral space (4/134) (P = 0.000). A good consistency was shown between the LAVA-Flex grade and T2WI-based Pfirrmann grade. Virtual endoscopy based on 3D LAVA-Flex could help clearly show the anatomic relationship between the degenerated disc and intervertebral foramen. CONCLUSIONS: 3D LAVA-Flex and T2WI show similar efficacy in evaluating lumbar intervertebral disc degeneration. 3D LAVA-Flex-based virtual endoscopy possesses great potential in the study of intervertebral disc abnormalities.

Assembly of SPS/MgSi assisted by dopamine with excellent removal performance for ciprofloxacin.

In this work, magnesium silicate-based sulfonated polystyrene sphere composites (SPS/MgSi) were synthesized by one-step (SMD1) and two-step (SMD2) methods. For SMD1, MgSi particles were densely assembled on the surface of SPS, assisted by complexation between Fe3+ and hydroxyl phenol. For SMD2, SPS/SiO2 was firstly obtained by the same method as SMD1, and then SPS/SiO2 was transformed directly to SPS/MgSi under hydrothermal conditions. Therefore, MgSi obtained by the two-step method had an interwoven structure. Compared to SPS, MgSi and SMD1, SMD2 presented a larger specific surface area and more negative surface charges. Therefore, SMD2 showed superior adsorption performance toward CIP with concentrations of 5, 10 and 50 mg/L, and for 50 mg/L, the equilibrium adsorption capacity could reach 329.7 mg/g. The adsorption process is fast and can be described by the pseudo-second-order kinetic model. The relationship between pH value and Zeta potential demonstrated that electrostatic interaction dominated the adsorption process. In addition, competitive adsorption showed that the effect of Na+ was negligible but the effect of Ca2+ was dependent on its concentration. Humid acid (HA) could slightly promote the absorption of CIP by SMD2. After five rounds of adsorption-desorption, the equilibrium adsorption capacity of SMD2 still remained at 288.6 mg/L for 50 mg/L CIP. Notably, SMD2 presented likewise superior adsorption capacity for CIP with concentrations of 10 and 50 mg/L in Minjiang source water. All the results indicated that this synthesis method is universal and that SMD2 has potential as an adsorbent for CIP removal from aquatic environments.

Remediation of organic arsenic contaminants with heterogeneous Fenton process mediated by SiO2-coated nano zero-valent iron.

Given their considerable solubility in water and potentially high toxicity to human health, organoarsenic compounds have become an emerging contaminant. Herein, a heterogeneous Fenton process mediated by SiO2-coated nano zero-valent iron (SiO2-nZVI) was employed to simultaneously remove the p-arsanilic acid (p-ASA, a typical organoarsenic compound) and the released arsenic. The initial pH value significantly influenced on the degradation of p-ASA and at the optimal pH (3.0), p-ASA (10 mg L-1) could be completely oxidized to As(V), NH4+, and plentiful phenolic compounds such as phenol and p-hydroquinone via the cleavage of C-N and C-As bonds within 60 min in pure water. Meanwhile, although the formed lepidocrocite and magnetite on the surface of SiO2-nZVI significantly limited the reutilization, they played a vital role in the adsorption of the released As(V) and the residual arsenic levels in the effluent were as low as 0.031 mg L-1, meeting both the drinking water standard of the World Health Organization (WHO) and the surface water standard of China (0.05 mg L-1). Furthermore, high-level dissolved organic matters (DOM) (> 2 mg C L-1) exhibited strong interference with both the oxidation of p-ASA and adsorption of arsenic, but the interference could be eliminated by increasing the SiO2-nZVI dosage or adding H2O2. Importantly, this system could completely remediate p-ASA in a short time and simultaneously avoid the secondary pollution caused by inorganic arsenic, which was significant for the remediation of organoarsenic pollutants in swine wastewater.

Effects of fish culture on particulate organic matter in a reservoir-type river as revealed by absorption spectroscopy and fluorescence EEM-PARAFAC.

Dam construction and fish culture can change the biogeochemical processes in river, yet their impact on the spectral properties of particulate organic matter (POM) remains to be studied. This was investigated in a reservoir-type river (Minjiang river, SE China) using absorption spectroscopy and fluorescence excitation-emission matrices-parallel factor analysis (EEMs-PARAFAC). Five fluorescent components were identified from POM with PARAFAC. Four components C1-C4 were affected by the seasonal variations of rainfall and runoff, indicating the influences of hydrological condition and terrestrial inputs. The Chlorophyll a concentration (Chl a) correlated significantly with the humic-like C3 (p < 0.05) and the protein-like C4 (p < 0.01), indicating phytoplankton was an important source of C3 and C4. The Chl a and fluorescence intensities of C3-C4 were higher in the fish culture zones than in other areas, and the absorption coefficient a300 and C1-C4 were lower downstream the dam. These results indicated that fish farming in the reservoir probably promoted the production of POM. The a300 and C1 per unit mass of suspended particulate matter (a300/TSM and C1/TSM) correlated significantly with the median particle size (p < 0.01), which might be related to the contribution of micro-phytoplankton. The absorption spectra of POM showed a shoulder peak at ∼280 nm, and its intensity correlated significantly and positively with Chl a (p < 0.01). These results indicated that the peak was probably derived from phytoplankton production. Our results have implications for better understanding the influences of human activities on the dynamics of river POM.

Highly efficient and selective removal of low-concentration antibiotics from aqueous solution by regenerable Mg(OH)2.

The prevalent presence of fluoroquinolone antibiotics in aquatic environments has attracted considerable attention because of their harmful effects on humans and the ecological environment. Magnesium hydroxide nanocrystals were found to act as a simple and effective adsorbent to remove low-concentration ciprofloxacin (CIP) in aqueous solution. The as-prepared Mg(OH)2 nanocrystals exhibited excellent CIP adsorption performance and high selectivity toward CIP molecules compared with other antibiotics or aromatics, e.g., norfloxacin (NOR) and eosin B (EB). The adsorbent showed pH-dependent adsorption, indicating that the adsorption process is probably dominated by an electrostatic interaction mechanism. In addition, structural analysis of the adsorbent indicated that coordination and hydrogen bonding between CIP and Mg(OH)2 nanocrystal might also be involved in the adsorption process. Moreover, the adsorbent could be easily recovered by pyrolysis and hydration without significant reduction of adsorption capacity. The superior adsorption behavior of Mg(OH)2 nanocrystal indicates that it may serve as a potential adsorbent material candidate for the selective removal of CIP from aquatic environments.