Search

A reinforced concrete column and steel beam (RCS) hybrid frame structure with replaceable members was proposed in this paper. Non-linear pushover analyses were conducted to investigate the overall mechanical performance of the proposed structural system. Based on the residual deformation of replaceable links after an earthquake, a method for evaluating the replaceability of members of the RCS hybrid frame was proposed. The acceptable residual inter-storey drift and residual rotation drift at the end of the link were adopted as the two indices in this method. Numerical models and full-scale experiments were performed to systematically investigate the stress and deformation of the entire section of the replaceable steel links. The residual deformation was shown to increase with an increase in the inter-storey drift (θ) and decrease with an increase in the length ratio. Then the control values of the acceptable residual deformation indices were determined through a statistical analysis of the residual deformation of links with different length ratios and link-column connection modes: when the residual inter-storey drift was less than 0.0048 rad and the residual rotation drift at the end of the links was less than 0.0074 rad, the link could be easily replaced. These findings can provide reference for similar structural designs.

With the rapid development of economy, the past decades have experienced more and more severe energy depletion and environmental pollution issues, hence it is urgent to develop more environmental-friendly energy devices, such as fuel cells, metal-air batteries, water electrolysis and so on. However, such devices have long been suffering from the sluggish reaction kinetics and high energy barriers, plus the conventional electrocatalysts used in these devices mostly are noble-metal-based materials, such as Pt/C, IrO2, and RuO2. These noble-metal-based electrocatalysts possess significant disadvantages such as high price, limited reserves, and undesirable stability, and these factors together hinder their large-scale industrial application and the inhomogeneity of the catalyst structure at the atomic level also impose great challenges to disclose the underlying catalytic mechanism. Noble metal nanoclusters, as a promising type of electrocatalyst with definitive composition and structure, have been attracting increasingly research efforts. This review aims to summarize the recent achievements of molecular metal nanoclusters employed in electrocatalytic processes, with particular elaboration on oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), as well as to unravel the catalytic mechanism and establish the relationship between its structure and functionality. Specifically, the size effect, the metal core configuration, charge effect, size effect, ligand effect, and metal-ligand binding motifs of the metal clusters that would impact the electrocatalytic performance are comprehensively discussed. In the end, the outlook and perspective including challenges and opportunities are proposed. We anticipate this review would be beneficial for gaining a deeper understanding of engineering nanoclusters for electrocatalysis and to expand its application in electrocatalysis.

Bi2S3 is a n-type (negative type) semiconductor that has a narrow band gap and an ideal band edge position for hydrogen generation. However, high charge recombination rate, low photoelectrochemical (PEC) efficiency and poor stability are of major concerns of Bi2S3 as a photoelectrode. Herein, we report an efficient Vanadium-rich Bi2S3 nanowires (atomic ratio of V to Bi is 1/22) that have been prepared on fluorine-doped tin oxide (FTO) substrate by an in-situ solution-processed reaction with BiVO4 film as precursor. The resulting V-rich photoelectrode demonstrates notably high charge separation efficiency and fast charge transport with respect to pristine Bi2S3 nanowires. As a result, the photocurrent density of ca. 10 mA·cm−2 at -0.2 V vs Ag/AgCl is obtained under visible light illumination. In addition, V-rich Bi2S3 generates IPCE (incident photocurrent-to-current conversion efficiency) of 50% at 460 nm and 45% at 760 nm, demonstrating a 2.0 and 2.8-fold increase, respectively, when compared with pristine Bi2S3. This enhancement is probably due to increased light absorption, less charge recombination, and faster charge transfer. More importantly, in contrast to pristine Bi2S3 sample that suffers detrimental photocorrosion in sulfide containing electrolyte, V-rich Bi2S3 nanowires retain 84.6% of its initial photocurrent over the course of 1 h. These findings are expected to shed light on engineering high-performance and robust metal sulfide materials for photoelectrochemical application.

Tetrastigma hemsleyanum Diels et Gilg (THDG) is used as a Chinese traditional anti-inflammatory medicine for about thousands of years. In this work, Tetrastigma hemsleyanum Diels et Gilg's polysaccharide (TP) can inhibit E. coli's growth in initial dosing period. Compared with the antibacterial effect of Achyranthe's polysaccharide (AP) from their metabolic profile, it's obviously that their metabolic sites for E. coli were inconsistent. Moreover, TP could not only increase the level of fructose-6-phosphate (F6P), decrease the level of fructose-1,6-diphosphate (FBP), but also charge the amount of the two differential metabolic with the change of the concentration and the dosing time. Actually, F6P could transform into FBP by catalyze of 6-phosphofructokinase-1(6-PFK-1), which is an important process in glycolysis. Furthermore, FBP was considered have positively correlated with E. coli's growth rate. Therefore, TP can inhibit the E. coli's proliferation by interfering with the process for glycolysis and gluconeogenesis. Based on the experimental result, we proposed a new mouthwash method to evaluate the anti-bacterial activity. Compared with AP, TP can inhibit the E. coli's growth within 2 h with a low concentration (0.5%) and a short dosing time (5 min). This study extends the applications of THDG and establishes a new assessment method for the pharmacology activity of Chinese herbal medicine.

Cysteine, a critical residue for catalytic process but also vulnerable to oxidative damage, was conventionally expressed as a buried catalytic site in most redox enzymes. In the present work, specific surface-exposed sites of a NADH oxidase from Lactobacillus rhamnosus (LrNox) were selected and mutated to cysteine to investigate its effects on catalytic function because LrNox has a buried catalytic cysteine but no surface-exposed one. The results showed that exception of the sites on dimer interface, the activities of LrNox mutants were improved to vary degrees when the polar uncharged and alanine residues were mutated to cysteine. But the cysteine mutations of polar charged and nonpolar residues except alanine showed obvious decline in catalytic activity. Substituting of Ala85 and Thr96 with other residues suggested that the cysteine mutation showed the highest activity. Structural analysis suggested that even a single cysteine mutation on the specific non-conserved surface area of LrNox could induce changes on the conformation of catalytic cysteine and lower the activation free energy to improve the catalytic activity.

The trans to cis isomerization of the azobenzene chromophore in most azobenzene-based photoresponsive molecularly imprinted polymers (MIPs) is initiated by UV irradiation. This limits the application of these materials in cases where UV light toxicity is an issue, such as in biological systems, food monitoring, and drug delivery. Herein we report a tetra-ortho-methyl substituted azobenzene, (4-[(4-methacryloyloxy)-2,6-dimethyl phenylazo]-3,5-dimethyl benzenesulfonic acid (MADPADSA). The photoswitching of MADPADSA could be induced by visible-light irradiation (550 nm for trans to cis and 475 nm for cis to trans) in 4-hydroxyethylpiperazineethanesulfonic acid (HEPES) buffer-ethanol (4:1, v/v) at pH 7.0, however, the photoisomerization was slow. With the use of MADPADSA as a functional monomer, NaYF4:Yb3+,Er3+ as a substrate, 4-ethylphenol (4-EP) as a template, a novel photoresponsive surface molecularly imprinted polymer NaYF4:Yb3+,Er3+@MIP was obtained. The NaYF4:Yb3+,Er3+@MIP displayed rapid visible-light-induced photoswitching. The NaYF4:Yb3+,Er3+ substrate could efficiently increase the trans to cis isomerization rate of the photoresponsive MIP on its surface, which was faster than that of the corresponding azobenzene monomer MADPADSA. Possible reasons for this effect were investigated by fluorescence spectroscopy. NaYF4:Yb3+,Er3+@MIP displayed good specificity toward 4-EP with a specific binding constant (Kd) of 3.67 × 10−6 mol L−1 and an apparent maximum adsorption capacity (Qmax) of 10.73 μmol g−1, respectively. NaYF4:Yb3+,Er3+@MIP was applied to determine the concentration of 4-EP in red wine with good efficiency and a limit of detection lower than the value that could cause an unpleasant off-flavor.

A composite adsorbent based on a metal–organic framework MIL-101 (Cr3F(H2O)2O(BDC)3; BDC: terephthalic acid) loaded with N,N′-dimethylethylenediamine (dmeda) was synthesized by post-synthesis modification method, and the crystal structure and thermal stability of MIL-101 were maintained. The composite is shown to enhance capacity and selectivity for post-combustion carbon dioxide capture, even if its BET specific surface area decreases by 52% compared to MIL-101. At 273 K and 298 K under 1 bar, dmeda-MIL-101 exhibited 8.7% and 18.7% increase in CO2 capacity respectively (from 2.30 mmol/g of MIL-101 to 2.50 mmol/g at 273 K, and from 1.35 mmol/g of MIL-101 to 1.59 mmol/g at 298 K). At 273 K and 298 K under a 0.15 bar CO2/0.75 bar N2 mixture, the CO2/N2 selectivities of MIL-101 and dmeda-MIL-101 were calculated by Ideal Adsorbed Solution Theory (IAST), according to single-component gas sorption experiment data. The improved capacity and selectivity are consequences of the higher isosteric heat of CO2 adsorption (33.9 kJ/mol at zero coverage), which is due to the interaction between amines and CO2.

Airborne fine particulate matter (PM2.5) has been known capable of causing lung inflammation and fibrosis, as a result of a series of chronic respiration diseases. Although NLRP3 inflammasome activation is essential for development of many chronic diseases, the relationship between PM2.5-induced toxicological effect and NLRP3 inflammasome activation is rarely investigated. Since PM2.5 contains a large population of nanosized materials and many types of nanomaterials can activate NLRP3 inflammasome, the NLRP3 inflammasome activation and lung fibrosis induced by PM2.5 were investigated in the present study. PM2.5 was found capable of causing weak cell death but potent IL-1β secretion in THP-1 cells, which was involved in NLRP3 inflammasome activation as evidenced by Z-YVAD-FMK inhibited IL-1β secretion and overexpressed ASC and NLRP3 protein in PM2.5 treated cells. PM2.5 could be internalized into cells through multiple endocytosis processes, such as phagocytosis and pinocytosis (macropinocytosis, clathrin- and caveolin-mediated endocytosis), and activate NLRP3 inflammasome through cathepsin B release, ROS production, and potassium efflux. After 21 days of exposure to PM2.5 through oropharyngeal aspiration, Balb/c mice showed increased IL-1β and TGF-β1 levels in the bronchoalveolar lavage fluid (BALF) of lung and significant collagen deposition around small airways of mice, suggesting potential lung inflammation and pulmonary fibrosis.

A double-phthalate-ester imprinted photoresponsive polymer was fabricated for simultaneous detection of phthalate esters. Specifically, three azobenzene derivatives with different steric characteristics (0, 2, and 4 methyl substituents at the ortho position) were used as functional monomers, supported by ZnO nanoscale support rods. Dibutyl phthalate and dicyclohexyl phthalate esters were used as double templates. The three photoresponsive molecularly imprinted polymers were fabricated with a triethanolamine trimethacrylate ester cross-linker, and were characterized by ultraviolet–visible absorption, Fourier-transform infrared spectroscopy, scanning and transmission electron microscopy, and N2 adsorption–desorption analysis. Steric hindrance affected both photoresponsive properties and binding properties. As the steric hindrance increased, the trans→cis rate constant and the binding capacities decreased. Hence, the polymer with the least steric hindrance was used for the simultaneous detection of phthalate esters in plastic cups and toys. The doubly imprinted polymer was more effective for detection or extraction of the phthalate esters than was a single-phthalate-ester imprinted polymer.

As customers' green awareness improves, a growing number of Chinese companies are seeking to implement green management. However, in the implementation process, many green brands have engaged in greenwashing. After greenwashing, brand trust between green brands and their stakeholders can suffer a great deal of damage. A valid brand strategy and underlying mechanism should be identified to repair green brand trust after greenwashing. This study focuses on brand strategies and their underlying mechanisms adopted from institutional theory for green brand trust repair after greenwashing. Based on an organizational-level trust repair model, this study finds that companies should adopt a “timely-considered-timely” or “timely-considered-considered” brand strategy with three separate stages of brand trust repair, as opposed to other timely or considered brand strategy combinations, in order to achieve an optimal green brand trust repair effect. Moreover, this study also shows that the “considered-timely-timely” brand strategy achieves the worst green brand trust repair effect and that green brand legitimacy plays a significant mediating role in the brand trust repair process. These findings enrich the theories of brand management, green marketing, and trust repair and offer important managerial implications to help enterprises repair damaged trust.

Compared to the octahedral metal–organic framework CuBTC (also called HKUST-1), an interesting hexagonal prism shaped CuBTC/carboxyl-functionalized graphene composite was synthesized through a precursor-resolvothermal method. Based on structural characterization results of the composite, the mechanism of crystal morphology-control was proposed that carboxyl-functionalized graphene plays a dual role of structure-directing nucleation sites and framework linkers in the process of CuBTC crystal growth. The precursor-resolvothermal method provides an effective way to transform the morphology of metal–organic frameworks, and the results also demonstrate the possibility of using functionalized graphene to synthesize a wide range of structural motifs in metal–organic frameworks with adjustable metrics. On the basis of maintaining thermal stability, the composite exhibited about a 6% increase in CO2 capacity (from 6.39 mmol·g−1 of CuBTC to 6.77 mmol·g−1 at 273 K and 1 atm).

This paper reports a photoresponsive hollow molecularly imprinted polymer for the determination of trace triamterene in biological sample. The photoresponsive hollow molecularly imprinted polymer was prepared on sacrificial silica microspheres via surface imprinting technique through atom transfer radical polymerization using a novel water-soluble azobenzene derivative, 4-[(4-methacryloyloxy)phenylazo]-3,5-dimethyl benzenesulfonic acid, as the functional monomer, and the sacrificial silica core was subsequently removed using HF etching method with 1.25vol.% HF ethanolic solution. The morphologies and properties of the photoresponsive hollow molecularly imprinted polymer were further characterized and compared systematically with the corresponding photoresponsive surface molecularly imprinted polymer. Compared with surface imprinted polymer, the hollow material displayed higher binding capacity, better recognition ability, faster mass-transfer rate, and larger isomerization rate constants toward triamterene. The static binding properties of the imprinted materials were investigated under three irradiation conditions. The photoresponsive hollow molecularly imprinted polymer showed better specificity toward triamterene than its structural analogues (folic acid and caffeine) as examined by UV-vis and HPLC. The photoresponsive hollow molecularly imprinted polymer was utilized for the determination of trace triamterene in biological samples (human urine and serum) with advantages of simple sample pre-treatment, good recovery and good sensitivity.