Visible-light-driven peroxymonosulfate activation by robust TiO2-base nanoparticles for efficient removal of sulfamethoxazole.

In this study, a novel bimetallic Co-Mo-TiO2 nanomaterial was fabricated through a simple two-step method, and applied as photocatalyst to activate peroxymonosulfate (PMS) with high efficiency for sulfamethoxazole (SMX) removal under visible light. Nearly 100% of SMX was degraded within 30 min in Vis/Co-Mo-TiO2/PMS system, and its kinetic reaction rate constant (0.099 min-1) was 24.8 times higher compare with the Vis/TiO2/PMS system (0.014 min-1). Moreover, the quenching experiments and the electronic spin resonance analysis results confirmed that both 1O2 and SO4•- were the dominant active species in the optimal system, and the redox cycles of Co3+/Co2+ and Mo6+/Mo4+ promoted the generation of the radicals during the PMS activation process. Additionally, the Vis/Co-Mo-TiO2/PMS system exhibited a wide working pH range, superior catalytic performance toward different pollutants and excellent stability with 92.8% SMX removal capacity retention after three consecutive cycles. The result of density functional theory (DFT) suggested that Co-Mo-TiO2 exhibited a high affinity for PMS adsorption, as indicated by the length O-O bond from PMS and the Eads of the catalysts. Finally, the possible degradation pathway of SMX in optimal system was proposed through intermediate identification and DFT calculation, and a toxicity assessment of the by-products was also conducted.

Ag3PO4-anchored La2Ti2O7 nanorod as a Z-Scheme heterostructure composite with boosted photogenerated carrier separation and enhanced photocatalytic performance under natural sunlight.

Developing wide spectra-responsive photocatalysts has attracted considerable attention in the photocatalytic technology to achieve excellent catalytic activity. Ag3PO4, with strong response to light spectra shorter than 530 nm, shows extremely outstanding photocatalytic oxidation ability. Unfortunately, the photocorrosion of Ag3PO4 is still the biggest obstacle to its application. Herein, the La2Ti2O7 nanorod was used to anchor Ag3PO4 nanoparticles in this study, and a novel Z-Scheme La2Ti2O7/Ag3PO4 heterostructure composite was constructed. Remarkably, the composite showed strong responsive to most of the spectra in natural sunlight. The Ag0 formed in-situ acted as the recombination center of photogenerated carriers, which promoted their efficient separation and contributed to the improved photocatalytic performance of the heterostructure. When the mass ratio of Ag3PO4 in the La2Ti2O7/Ag3PO4 catalyst was 50%, the degradation rate constant of Rhodamine B (RhB), methyl orange (MO), chloroquine phosphate (CQ), tetracycline (TC), and phenol under natural sunlight irradiation were 0.5923, 0.4463, 0.1399, 0.0493, and 0.0096 min-1, respectively. Furthermore, the photocorrosion of the composite was greatly inhibited, 76.49% of CQ and 83.96% of RhB were still degraded after four cycles. Besides, the holes and O2•- played a significant role in RhB degradation, and it included multiple mechanisms of deethylation, deamination, decarboxylation, and cleavage of ring-structures. Moreover, the treated solution can also show safety to the water receiving environment. Overall, the synthesized Z-Scheme La2Ti2O7/Ag3PO4 composite exhibited immense potential for removing various organic pollutants through photocatalytic technology under natural sunlight irradiation.

Enhanced degradation of tetracycline under natural sunlight through the synergistic effect of Ag3PO4/MIL-101(Fe) photocatalysis and Fenton catalysis: Mechanism, pathway, and toxicity assessment.

Here, we show that the adverse environmental and health effects of tetracycline (TC) can be efficiently reduced by encapsulating Ag3PO4 into MIL-101(Fe) to construct a Ag3PO4/MIL-101(Fe) heterojunction composite through advanced oxidation processes, such as Fenton catalysis, photocatalysis, and photo-Fenton catalysis. Notably, the reaction can be driven by natural sunlight and does not require any artificial energy source. Remarkably, the optimal degradation of TC can be achieved under different compositions of the composite system through photocatalysis and photo-Fenton catalysis. For photo-Fenton catalysis, the maximum degradation rate of TC (2.5730 min-1) is achieved when the mass ratio of MIL-101(Fe) to Ag3PO4 in the composite is 5:1, which is 31.65- and 3.12-fold of that in the Ag3PO4 + PDS + Sunlight and MIL-101(Fe) + PDS+ Sunlight catalyst systems, respectively. Moreover, the internal conversion of matrix during photocatalysis and Fenton catalysis processes inhibits the photocorrosion of Ag3PO4 and improves the reusability of the composite. Furthermore, it is found that both radical and non-radical species participate in the TC degradation. Besides, the degradation products and catalytic mechanism of Ag3PO4 and Ag3PO4/MIL-101(Fe) systems are explored. The toxicity evaluation results suggest that the intermediates produced during Ag3PO4/MIL-101(Fe) catalysis have a lower biotoxicity than those produced during Ag3PO4 catalysis. Overall, this work provides an effective strategy to inhibit the inherent photocorrosion of Ag3PO4 and establishes an efficient catalytic system for the treatment of organic-contaminated wastewater under natural sunlight conditions.

Oxidation of simulated wastewater by Fe2+-catalyzed system: The selective reactivity of chlorine radicals and the oxidation pathway of aromatic amines.

Aromatic amines (AAs), a characteristic pollutant with electron-donating groups in textile industry, having high reactivity with reactive chlorine free radicals, is probably the precursor of chlorinated aromatic products in advanced oxidation treatment. In this study, Fe2+/peroxydisulfate (PDS)/Cl- and Fe2+/H2O2/Cl-systems were used to treat four kinds of AAs (5-Nitro-o-toluidine (NT), 4-Aminoazobenzol (AAB), O-Aminoazotoluene (OAAT), 4,4'-Methylene-bis(2-chloroaniline) (MBCA)) in simulated wastewater, and the selectivity of various reactive species to AAs, the oxidation law and pathway of AAs were explored. The results showed that dichloride anion radical (Cl2·-) could effectively oxidize four AAs, and chlorine radical (·Cl) was strongly reactive to AAB and MBCA, especially MBCA. The largest f - (Fukui function) of MBCA is 0.0822, which is the lowest of the four AAs, so ·Cl might be more sensitive to electrophilic point than hydroxyl radical (·OH). The oxidation pathway of NT and MBCA showed that ·Cl mainly played the role of electron transfer to AAs instead of generating chlorinated products, but the addition of ·OH to -NH2 generated aromatic nitro compounds with higher toxicity than NT and MBCA. Therefore, the electron transfer of ·Cl and Cl2·- could not only improve the removal of AAs but also reduce the generation of toxic products. This study found that the reactivity of reactive chlorine free radicals was not necessarily related to chlorination, which provided a theoretical basis for the further studies into the formation mechanism of chlorination products.

Activated peroxydisulfate by sorghum straw-based biochar for enhanced tartrazine degradation: Roles of adsorption and radical/nonradical processes.

Biochar obtained from biomass waste through pyrolysis has significant potential in wastewater treatment due to its large specific surface area and multi-functional active sites. In current study, sorghum straw (SS) was pyrolyzed to prepare various biochar under nitrogen atmosphere. Adsorption kinetics of prepared biochar toward tartrazine (TTZ) was systematically investigated, and the biochar was also characterized by using multiple techniques to explore the contribution of physicochemical properties to adsorption. Then, the biochar with optimum TTZ adsorption performance, was also applied as a catalyst for peroxydisulfate (PDS) activation to degrade TTZ. Factors including PDS concentration, solution pH, and reaction temperature were examined. The optimized degradation rate constant of TTZ (1.1627 min-1) was achieved under the conditions at 2 mM PDS, pH of 3, and 23 °C. In addition, the free radical trapping experiments and EPR spectra revealed that the reactive substances of electron (e-), 1O2, SO4•-, O2•-, and •OH contributed to TTZ degradation. Density Functional Theory (DFT) also concluded that the atoms C(6), O(12), N(16), N(17), C(18) and N(22) in TTZ molecule showed larger f0 values which are vulnerable to radical attack. Therefore, the synergistic mechanism embodying adsorption and radical/non-radical processes were proposed. Besides, the degradation pathways of TTZ were identified with the aid of HPLC/MS technique, indicating that multiple reaction processes containing the symmetrical cleavage of azo bonds, the asymmetrical cleavage of C-N, desulfonation, and benzene-like structure cracking were involved. Therefore, this study provides a simple and effective catalytic system for TTZ degradation, and also realizes the resource utilization of solid waste.

Two Facile Aniline-Based Hypercrosslinked Polymer Adsorbents for Highly Efficient Iodine Capture and Removal.

Effective capture and safe disposal of radioactive iodine (129I or 131I) during nuclear power generation processes have always been a worldwide environmental concern. Low-cost and high-efficiency iodine removal materials are urgently needed. In this study, we synthesized two aniline-based hypercrosslinked polymers (AHCPs), AHCP-1 and AHCP-2, for iodine capture in both aqueous and gaseous phases. They are obtained by aniline polymerization through Friedel-Crafts alkylation and Scholl coupling reaction, respectively, with high chemical and thermal stability. Notably, AHCP-1 exhibits record-high static iodine adsorption (250 wt%) in aqueous solution. In the iodine vapor adsorption, AHCP-2 presents an excellent total iodine capture (596 wt%), surpassing the most reported amorphous polymer adsorbents. The rich primary amine groups of AHCPs promote the rapid physical capture of iodine from iodine water and iodine vapor. Intrinsic features such as low-cost preparation, good recyclability, as well as excellent performance in iodine capture indicate that the AHCPs can be used as potential candidates for the removal of iodine from radioactive wastewater and gas mixtures.

Rabies Virus-Induced Autophagy Is Dependent on Viral Load in BV2 Cells.

An increasing number of studies are showing that autophagy plays a vital role in viral replication and escape. Rabies virus (RABV), a typical neurotropic virus, has been proven to induce autophagy in neurons. However, there are no reports indicating that RABV can cause autophagy in other cells of the central nervous system. Thus, we aimed to explore the relationship between autophagy and RABV infection in BV2 cells in this study. Results of viral growth curves showed that the titers of microglial BV2 cells infected with RABV peaked at 12 hours post-infection (hpi) and then decreased continuously over time. However, it was found that the viral genome RNA and structural proteins can express normally in BV2 cells. In addition, Western blotting indicated that RABV infection increased LC3-II and p62 expression in BV2 cells. LC3 punctate increased with RABV infection in BV2 cells after the transfection of fluorescent protein-tagged LC3 plasmids. Moreover, autophagy cargo protein further accumulated with RABV infection in Bafilomycin A1-treated cells. Subsequently, RABV infection inhibited the fusion of autophagosomes with lysosomes by using a tandem fluorescent marker. Furthermore, a higher multiplicity of infection induced stronger autophagy. Thus, RABV can induce autophagy in BV2 cells, and the autophagy is positively associated with the viral load.

Artesunate and Dihydroartemisinin Inhibit Rabies Virus Replication.

Rabies is caused by infection of rabies virus (RABV) and remains a serious threat to the global public health. Except for the requirement for cold chain and high cost of human rabies immune globulin, no small molecule drugs are currently available for clinical treatment of rabies. So, it is of great importance to identify novel compounds that can effectively inhibit RABV infection. Artesunate (ART) and dihydroartemisinin (DHA), two derivatives of artemisinin, are widely used for treatment of malaria in adults and children, showing high safety. In this study, we found that both ART and DHA were able to inhibit RABV replication in host cells at a low concentration (0.1 µmol/L). The antiviral effects of ART and DHA were independent of viral strains and cell lines. Pre-treatment with ART or DHA for 2 h in vitro did not affect the viral replication in host cells, implying that ART and DHA neither reduced the viability of RABV directly nor inhibited the binding and entrance of the virus to host cells. Further studies revealed that ART and DHA inhibited RABV genomic RNA synthesis and viral gene transcription. Treatment with ART or DHA (5 mg/kg) by intramuscular injection improved, to some extent, the survival rate of RABV-challenged mice. Combination treatment with derivatives of artemisinin and mannitol significantly improved the survival rate of RABV-challenged mice. The results suggest that ART and DHA have a great potential to be explored as new anti-rabies agents for treatment of rabies.

Finite element analysis of the stress distribution of dental implant crowns with different all-ceramic materials and thicknesses / 口腔疾病防治

Objective@# To compare the stress distribution of different all-ceramic restoration materials and thicknesses in dental crown restorations using the finite element method and provide a reference for the selection and design of clinical crown restoration materials.@*Methods@#A finite element model of mandibular first molar implant crown restoration was created, and 6 crown thickness designs and 4 different crown restoration materials were evaluated, namely, resin-based ceramics (Lava Ultimate and Vita Enamic), lithium disilicate glass-ceramics (IPS e.max CAD), and zirconia ceramic (Cercon) designs. The mandibular first molars were loaded at 600 N, and the stress distribution was analyzed by using the finite element software ANSYS 10.0.@*Results@#The crown stress analysis showed that 156.05 MPa was the highest in 4 mm Cercon group and 18.85 MPa was the lowest in 1 mm Lava Ultimate group. The stress analysis of resin cement showed that 62.52 MPa was the highest in the 4 mm Lava Ultimate group and 16.74 MPa was the lowest in 1 mm IPS e.max CAD group. During the use of the finished platform, the stress concentration of the Lava Ultimate group in the crown prosthesis and resin cement was higher than that of the personalized platform with the same crown thickness.@*Conclusion@# With increasing crown thickness, the maximum principal stress concentration in crown restoration and resin cement increases. Personalized abutments are more conducive to reducing stress concentrations for resin-based ceramics.

Fibrous red phosphorene: a promising two-dimensional optoelectronic and photocatalytic material with a desirable band gap and high carrier mobility.

By using density-functional theory, we have systematically investigated the structural stabilities, electronic structures, and optical properties of monolayer fibrous red phosphorene. We find the monolayer fibrous red phosphorene lattice to be dynamically and thermodynamically stable based on phonon spectra calculation and ab initio molecular dynamics simulation. A small cleavage energy of approximately 0.88 J m-2 is required for creating it from its bulk, suggesting the possibility of exfoliation in experiments. Furthermore, we find that monolayer fibrous red phosphorene is a semiconductor with an indirect bandgap of approximately 2.46 eV, and the bandgap is less susceptible to the number of stacked atomic layers. Moreover, the monolayer is expected to have highly directional anisotropy effective masses and high carrier mobilities (∼104 cm2 V-1 s-1), comparable with those of monolayer black phosphorene. In addition, fibrous red phosphorene nanosheets can absorb visible light as well as their band edge alignments are well positioned for the feasibility of both photo-oxidation and photo-reduction of water within the range of -5 to 5% biaxial strains. These combined properties make the fibrous red phosphorene nanosheets an alternative to diverse nanodevices, and pave the way for a potential photocatalyst.

Inorganic gas sensing of green phosphorene nanosheet: insights from density functional theory.

Our work highlights the functionality of a novel two-dimensional phosphorene allotrope entitled green phosphorene for inorganic gas detection for the first time. Four inorganic molecules, NH3, SO2, HCN and O3, are considered as adsorbates and the adsorption conformation, adsorption energy, charge transfer, density of states, and electronic band structure are systematically scrutinized based on density functional theory. Our calculations show that the adsorption energy of O3 on pristine green phosphorene is the lowest among the four considered gas molecules, suggesting that the substrate is more sensitive to O3. Significant changes in electronic structures confirm the possibility of green phosphorene for O3 detection. Biaxial strains and electric fields were applied to investigate the changes in adsorption behavior. The presence of compressive strain could enhance adsorption sensitivity between O3 and green phosphorene, while the tensile strain induces the dissociative adsorption that not suitable for reversible sensor. Furthermore, by controlling the orientation of external electric field, it is possible to achieve O3 adsorption-desorption cycle, which is of great significance for green phosphorene in the application of reversible gas sensor.

A guideline for homology modeling of the proteins from newly discovered betacoronavirus, 2019 novel coronavirus (2019-nCoV).

During an outbreak of respiratory diseases including atypical pneumonia in Wuhan, a previously unknown ß-coronavirus was detected in patients. The newly discovered coronavirus is similar to some ß-coronaviruses found in bats but different from previously known SARS-CoV and MERS-CoV. High sequence identities and similarities between 2019-nCoV and SARS-CoV were found. In this study, we searched the homologous templates of all nonstructural and structural proteins of 2019-nCoV. Among the nonstructural proteins, the leader protein (nsp1), the papain-like protease (nsp3), the nsp4, the 3C-like protease (nsp5), the nsp7, the nsp8, the nsp9, the nsp10, the RNA-directed RNA polymerase (nsp12), the helicase (nsp13), the guanine-N7 methyltransferase (nsp14), the uridylate-specific endoribonuclease (nsp15), the 2'-O-methyltransferase (nsp16), and the ORF7a protein could be built on the basis of homology templates. Among the structural proteins, the spike protein (S-protein), the envelope protein (E-protein), and the nucleocapsid protein (N-protein) can be constructed based on the crystal structures of the proteins from SARS-CoV. It is known that PL-Pro, 3CL-Pro, and RdRp are important targets for design antiviral drugs against 2019-nCoV. And S protein is a critical target candidate for inhibitor screening or vaccine design against 2019-nCoV because coronavirus replication is initiated by the binding of S protein to cell surface receptors. It is believed that these proteins should be useful for further structure-based virtual screening and related computer-aided drug development and vaccine design.

Five extracellular matrix-associated genes upregulated in oral tongue squamous cell carcinoma: An integrated bioinformatics analysis.

Despite advancements in treatment regimens, the mortality rate of patients with oral tongue squamous cell carcinoma (OTSCC) is high. In addition, the signaling pathways and oncoproteins involved in OTSCC progression remain largely unknown. Therefore, the aim of the present study was to identify specific prognostic marker for patients at a high risk of developing OTSCC. The present study used four original microarray datasets to identify the key candidate genes involved in OTSCC pathogenesis. Expression profiles of 93 OTSCC tissues and 76 normal tissues from GSE9844, GSE13601, GSE31056 and GSE75538 datasets were investigated. Differentially expressed genes (DEGs) were determined, and gene ontology enrichment and gene interactions were analyzed. The four GSE datasets reported five upregulated and six downregulated DEGs. Five upregulated genes (matrix metalloproteinase 1, 3, 10 and 12 and laminin subunit gamma 2) were localized in the extracellular region of cells and were associated with extracellular matrix disassembly. Furthermore, analysis for The Cancer Genome Atlas database revealed that the aforementioned five upregulated genes were also highly expressed in OTSCC and head and neck squamous cell carcinoma tissues. These results demonstrated that the five upregulated genes may be considered as potential prognostic biomarkers of OTSCC and may serve at understanding OTSCC progression. Upregulated DEGs may therefore represent valuable therapeutic targets to prevent or control OTSCC pathogenesis.

Stabilities and novel electronic structures of three carbon nitride bilayers.

We predict three novel phases of the carbon nitride (CN) bilayer, denoted α-C2N2, ß-C2N2 and γ-C4N4, respectively. All of them consist of two CN sheets connected by C-C covalent bonds. The phonon dispersions reveal that all these phases are dynamically stable, because no imaginary frequency is present. The transition pathway between α-C2N2 and ß-C2N2 is investigated, which involves bond-breaking and bond-reforming between C and N. This conversion is difficult, since the activation energy barrier is 1.90 eV per unit cell, high enough to prevent the transformation at room temperature. Electronic structure calculations show that all three phases are semiconductors with indirect band gaps of 3.76/5.22 eV, 4.23/5.75 eV and 2.06/3.53 eV, respectively, by PBE/HSE calculation. The ß-C2N2 has the widest band gap among the three phases. All three bilayers can become metallic under tensile strain, and the indirect gap of γ-C4N4 can turn into a direct one. γ-C4N4 can become an anisotropic Dirac semimetal under uniaxial tensile strain. Anisotropic Dirac cones with high Fermi velocity of the order of 105 m/s appear under 12% strain. Our results suggest that the three two-dimensional materials have potential applications in electronics, semiconductors, optics and spintronics.

Electronic Structure and Band Gap Engineering of Two-Dimensional Octagon-Nitrogene.

A new phase of nitrogen with octagon structure has been predicted in our previous study, which we referred to as octagon-nitrogene (ON). In this work, we make further investigations of its stability and electronic structures. The phonon dispersion has no imaginary phonon modes, which indicates that ON is dynamically stable. Using ab initio molecular dynamic simulations, this structure is found to be stable up to room temperature and possibly higher, and ripples that are similar to that of graphene are formed on the ON sheet. Based on the density functional theory calculation, we find that single layer ON is a two-dimension wide gap semiconductor with an indirect band gap of 4.7 eV. This gap can be decreased by stacking due to the interlayer interactions. Biaxial tensile strain and perpendicular electric field can greatly influence the band structure of ON, in which the gap decreases and eventually closes as the biaxial tensile strain or the perpendicular electric field increases. In other words, both biaxial tensile strain and a perpendicular electric field can drive the insulator-to-metal transition, and thus can be used to engineer the band gap of ON. From our results, we see that ON has potential applications in many fields, including electronics, semiconductors, optics and spintronics.

Structure revision of aspergicin by the crystal structure of aspergicine, a co-occurring isomer produced by co-culture of two mangrove epiphytic fungi.

The structure of aspergicin (1), an antibacterial alkaloid produced by co-culture of two marine-derived mangrove epiphytic fungi, were revised by the co-occurring isomer named as aspergicine (2), whose structure was determined on the basis of spectroscopic analysis and X-ray crystallography.

Band Gap Engineering of Two-Dimensional Nitrogene.

In our previous study, we have predicted the novel two-dimensional honeycomb monolayers of pnictogen. In particular, the structure and properties of the honeycomb monolayer of nitrogen, which we call nitrogene, are very unusual. In this paper, we make an in-depth investigation of its electronic structure. We find that the band structure of nitrogene can be engineered in several ways: controlling the stacking of monolayers, application of biaxial tensile strain, and application of perpendicular electric field. The band gap of nitrogene is found to decrease with the increasing number of layers. The perpendicular electric field can also reduce the band gap when it is larger than 0.18 V/Å, and the gap closes at 0.35 V/Å. A nearly linear dependence of the gap on the electric field is found during the process. Application of biaxial strain can decrease the band gap as well, and eventually closes the gap. After the gap-closing, we find six inequivalent Dirac points in the Brillouin zone under the strain between 17% and 28%, and the nitrogene monolayer becomes a Dirac semimetal. These findings suggest that the electronic structure of nitrogene can be modified by several techniques, which makes it a promising candidate for electronic devices.