This study systematically investigated the correlations between fluorescence distributions characterized by the excitation–emission matrix (EEM) and hydrophobic/hydrophilic composition of dissolved ...organic matter (DOM) in membrane bioreactors (MBRs). On the basis of samples from 10 full-scale MBRs, we performed point-to-point comparisons among different components using an EEM fluorescence quotient (FQ) method and obtained a hydrophobic/hydrophilic fluorophore distribution map via Wilcoxon signed rank test. Hydrophobic acids/bases (HOA/HOB) concentrated in the low-wavelength region excitation wavelength (Ex) < 235 nm, while hydrophilic substances (HIS) were enriched in the region of Ex > 235 nm especially with emission wavelength (Em) = 300–360 nm. Quantitatively, EEM regional contribution to whole wavelength fluorescence was found to significantly correlate with the hydrophobic/hydrophilic proportions of DOM, with Pearson’s coefficients of 0.94 and 0.78 (p < 0.01) for HOA and HIS, respectively. We established a linear regression model showing the HOA proportion as a function of the EEM regional contribution at (Ex, Em) = (200–285, 340–465 nm), with R 2 = 0.876, which was validated via leave-one-out cross-validation and Monte Carlo simulation. This study shows a statistically hydrophobicity-dependent fluorescence property across different MBRs, and it might be applied to provide a quick estimation of hydrophobic/hydrophilic composition of DOM in wastewater treatment systems based on EEM monitoring.
The synthesis of sulfones
via
a selective functionalization of C-H-bonds represents a powerful alternative to classical methods for the preparation of this important compound class. Within the last ...decade, significant progress has been made in this field. This review highlights recent advances in the area of metal-catalyzed as well as metal-free transformations for the direct sulfonylation of C(sp
2
)-H and C(sp
3
)-H bonds.
This review highlights recent advances in the synthesis of sulfones
via
the selective functionalization of C-H-bonds.
Inverse synthetic aperture radar (ISAR) imaging is an important technique for moving target identification and classification. For the space spinning targets, a long-time observation is required to ...estimate the spinning parameter in the conventional ISAR imaging methods. However, for the advanced multifunctional radar, which is used for multi-target surveillance, a long-time observation for only one target is the loss outweighs the gain. To decrease the observation time, we propose a novel imaging method for spinning space targets with short time observation in this paper. Firstly, we build the imaging model by using the azimuth rotation angle caused by the spinning motion rather than the translation motion to obtain the azimuth resolution. Secondly, we utilize the orthogonal coding signals with different delays to obtain enough equivalent pulses in the short observation time. Moreover, since the equivalent pulses are block-missing to avoid overlapping of the transmitting duration and the receiving duration, we transform the imaging problem to the compressed sensing (CS) problem and solve it by modifying the Smoothed L0-norm (SL0) algorithm. Finally, both the simulations and the experiments on real data are shown to demonstrate the validity of the proposed method. Since the observing time of the proposed method only needs to cover a small percentage of one spinning period, the proposed method can be used in multi-target surveillance such as satellites and space debris.
The outbreak of white spot syndrome (WSS) is a looming challenge, due to dramatic losses to the crustacean aquaculture industry. However, at present, there are no prophylactic or therapeutic means to ...control this infectious viral disease. Here, we screened fifteen medicinal plants for their inhibitory activity on the white spot syndrome virus (WSSV), using red swamp crayfish (Procambarus clarkii) as a model species. The results showed that the crude extracts of Pinellia ternata (Thunb.) Breit. had the highest inhibitory effect (91.59%, 100 mg/kg) on WSSV proliferation, and its main component, beta-sitosterol, showed a much higher activity (95.79%, 50 mg/kg). Further, beta-sitosterol potently reduced (p < 0.01) viral loads and viral gene transcription levels in a concentration-dependent fashion, and significantly promoted the survival rate of WSSV-challenged crayfish (57.14%, 50 mg/kg). The co-incubation assay indicated that beta-sitosterol did not influence the infectivity of WSSV particles. Both pre- and post-treatment of beta-sitosterol exerted a significant inhibitory effect (p < 0.01) on the viral load in vivo. Mechanistically, beta-sitosterol not only interfered with the expression of viral genes (immediate early gene 1, ie1; DNA polymerase, DNApol) that are important in initiating WSSV transcription, but it also attenuated the hijacking of innate immune signaling pathways (Toll, IMD, and JAK/STAT pathways) by viral genes to block WSSV replication. Moreover, the expression of several antiviral immune, antioxidant, pro-inflammatory, and apoptosis-related genes changed significantly in beta-sitosterol-treated crayfish. Beta-sitosterol is a potent WSSV inhibitor and has the potential to be developed as an effective anti-WSSV agent against a WSS outbreak in crustacean aquaculture.
Developing efficient strategy for nanomaterials dispersion is the key for promoting the utilization of cellulose-based composite in energy storage devices. In this study, an instant synthesis method ...for cellulose nanofiber (CNF)/reduced graphene oxide (rGO) composite film with a deep eutectic solvent (DES) based on choline chloride and urea as a media is developed. This DES shows favorable abilities of recyclability, materials dispersion, and could adjust the pH value for reaction systems of neutral to alkaline which in favor of electrostatic repulsion arising from deprotonated carboxyl groups at the composite surface. As-obtained films feature excellent flexibility, high electrical conductivity (as high as 26.47 S∙cm−1) and well electrochemical properties. Furthermore, a little amount of nitrogen atoms (~3.0 at%) could be introduced in the composite at a mild condition. Overall, this approach offers the potential for cost-effective, environmentally friendly and large-scale production of cellulose-based electrode and numerous advanced applications.
•DES was used as a media for cellulosic-composite electrode fabrication.•The effect of DES on composite materials was investigated.•Highest areal specific capacitance of 226.83 mF∙cm−2 at 1 mA∙cm−2 was achieved.•DES can be recycled and reused for cellulosic-composite electrode preparation.
The recently emerging vinylene-linked covalent organic frameworks (VCOFs) stand out from other COFs with exceptional chemical stability and favorable light-emitting properties, promising sensing ...applications for acids/bases or in strong acidic/basic conditions. Here we systematically investigated the reversible color and fluorescent response of a VCOF functionalized with pyridyl groups to acids/pH. The COF was synthesized with a record surface area for VCOFs and shows reversible hydrochromic and acidochromic behaviors and concomitant fluorescence quenching. The mechanisms were probed with systematical experimental comparison with relevant COFs and model molecules in combination with orbital analysis. The response is related to significant electronic changes in the ground and photoexcited states as a result of protonation or hydrogen bonding at pyridyl sites. The COF in aqueous dispersion displays a reversible fluorescence transition with pH change, which follows the Hill equation for multisite protonation. The COF-modified test paper shows immediate and remarkable color change and fluorescence turn-off/on when alternately exposed to HCl and NH3 gases. The work illustrates the great potential of developing highly robust sensory COFs through the vinylene approach.
A vinylogous tetrathiafulvalene (TTFV) monomer was prepared and copolymerized with fluorene to give a conformationally switchable conjugated copolymer. This copolymer was shown to undergo a ...conformational change upon protonation with trifluoroacetic acid (TFA). When mixed with single-walled carbon nanotubes (SWNTs), this TTFV–fluorene copolymer exhibited strong interactions with the SWNT surface, leading to stable, concentrated nanotube dispersions in toluene. Photoluminescence excitation mapping indicated that the copolymer selectively disperses low-diameter SWNTs, as would be expected from its ability to form a tightly coiled conformation on the nanotube surface. Addition of TFA to the copolymer–SWNT dispersion resulted in a rapid conformational change and desorption of the polymer from the SWNT surface, resulting in precipitation of pure SWNTs that were completely free of polymer. Importantly, the nanotubes isolated after dispersion and release by the TTFV–fluorene copolymer were more pure than the original SWNTs that were initially dispersed.
Medical education has evolved rapidly, with the development of flipped classrooms and team-based learning based on lecture-based learning, but the novel model of combining flipped classrooms with ...team-based learning has been poorly investigated in orthopedic education.
A femoral neck fracture teaching mode was chosen to 109 clinical internship students to explore the effectiveness of flipped classroom combined with team-based learning in internship education. They were enrolled and randomly divided into either the flipped classroom combined with team-based learning group (FTG, n = 55) or the traditional lecture-based classroom group (n = 54). All students completed the learning according to the course flow and took before-class and after-class tests. The questionnaires were used to compare students perceptions and satisfaction with the different teaching methods and were utilized to assess the strengths and weaknesses of the 2 groups.
The post-class test scores of both groups significantly improved compared to pre-class test scores. Regarding the post-class test scores, FTG's was significantly higher than the traditional lecture-based classroom group's, mainly in clinical areas such as imaging analysis, fracture classification, treatment options, and management of postoperative complications, but there was no significant difference in the mastery of basic theoretical knowledge. The students were more satisfied with the FTG and believed that it improved their various competencies, but with significantly more time spent.
FTG is generally recognized as a promising option for training clinical interns and is worth spreading as it has outstanding merits in developing students clinical competence.
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►A dynamic criterion allows the identification of solid and liquid-like molecules without the limitation of structural order parameters. ►By using a self-adaptive approach and an ...interface detecting method based on an integration procedure, a system can be maintained roughly at steady state during a crystal growth simulation. ►The growths of both CH
4 and H
2S hydrates predict unusual polycrystalline structures. ►The heterogeneous crystal growth simulation may provide insights into microscopic mechanisms for annealing of defect structures.
We briefly review previous investigations of formation mechanisms of gas hydrates and then describe a variety of methodologies employed in molecular simulations of their crystal growth. A dynamic criterion for identification of solid and liquid-like molecules allows differentiation without the limitations of structural order parameters, with the fraction of molecules labeled incorrectly as low as 0.01%. We demonstrate that an interface detecting method based on an integration procedure can provide very good estimates of the interface positions. Results from simulations examining crystal growth behavior of CH
4 and H
2S hydrate are reported, including polycrystalline structures and annealing mechanisms.
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