Latest ArticlesHerein, copper ion doped calcium alginate (Cu2+/CaAlg) composite hydrogel filtration membranes were prepared by using natural polymer sodium alginate (NaAlg) as raw material. The thermal stability and structure of the composite membranes were characterized by thermogravimetric analysis and infrared spectroscopy. The mechanical strength, anti-fouling performance, hydrophilicity and filtration performance of the membrane were studied. The results show that Cu2+/CaAlg hydrogel membrane has excellent mechanical properties and thermal stability. The anti-swelling ability of the membrane was greatly enhanced by doping Cu2+. After three alternate filtration cycles, the flux recovery rate of Cu2+/CaAlg hydrogel membrane can still reach 85%, indicating that the membrane has good anti-pollution performance. When the operation pressure was 0.1 MPa, the rejection of coomassie brilliant blue G250 reached 99.8% with a flux of 46.3 L m-2 h-1, while the Na2SO4 rejectionwas less than 10.0%. The Cu2+/CaAlg membrane was recycled after 24 h in the filtration process, and its flux and rejection rate did not decrease significantly, indicating that the hydrogel membrane has long-term application potential. The Cu2+/CaAlg membrane has a wide range of applications prospect in dye desalination, fine separation and biopharmaceutical technology fields.
A template-free carbonization-activation route is developed to fabricate sub-nanopore-containing porous carbon by using a novel polypyrrole (PPy) hydrogel as a precursor. This design of PPy hydrogel precursor containing molecular-scale grids (diameter ~2.0 nm) allows for homogeneous N, O-codoping into the porous carbon scaffold during the pyrolysis process. A subsequent activation step produces activated porous carbons (APCs) with tailored pore structures, which renders the APCs abundant sub-nanopores on their surface to increase the specific capacitance as extra capacitance sites. Coupled with large specific surface area and abundant heteroatoms, the optimized APC4/1 displays excellent specific capacitance of 379 F/g for liquid-state supercapacitor and 230 F/g for solid-state supercapacitor. The solid-state supercapacitor shows a high energy density of 22.99 Wh/kg at power density of 420 W/kg, which is higher than most reported porous carbon materials and satisfy the urgent requirements of elementary power source for electric vehicles. Moreover, this method can be easily modified to fabricate sub-nanopore-containing porous carbons with preferred structures and compositions for many applications.
Functional groups in the molecule play an important role in the molecular organization process. To reveal the influence of functional groups on the self-assembly at interface, herein, the self-assembly structures of three liquid crystal molecules, which only differ in the functional groups, are explicitly characterized by using scanning tunneling microscopy (STM). The high-resolution STM images demonstrate the difference between the supramolecular assembly structures of three liquid crystal molecules, which attribute to the hydrogen bonding interaction and π-π stacking interaction between different functional groups. The density functional theory (DFT) results also confirm the influence of these functional groups on the self-assemblies. The effort on the self-assembly of liquid crystal molecules at interface could enhance the understanding of the supramolecular assembly mechanism and benefit the further application of liquid crystals.
CO oxidation at ceria surfaces has been studied for decades, and many efforts have been devoted to understanding the effect of surface reduction on the catalytic activity. In this work, we theoretically studied the CO oxidation on the clean and reduced CeO2(111) surfaces using different surface cells to determine the relationships between the reduction degrees and calculated reaction energetics. It is found that the calculated barrier for the direct reaction between CO and surface lattice O drastically decreases with the increase of surface reduction degree. From electronic analysis, we found that the surface reduction can lead to the occurrence of localized electrons at the surface Ce, which affects the charge distribution at surface O. As the result, the surface O becomes more negatively charged and therefore more active in reacting with CO. This work then suggests that the localized 4f electron reservoir of Ce can act as the "pseudo-anion" at reduced CeO2 surfaces to activate surface lattice O for catalytic oxidative reactions.
Azithromycin loaded fumaryl diketopiperazine (FDKP) dry powder inhalationwas designed and prepared for the treatment of community-acquired pneumonia. The solubility of FDKP and stability of azithromycin solution was investigated. Formulation of azithromycin loaded FDKP microparticle was investigated and optimized by the single factor experiment. High-pressure homogenization and spray drying conditions were also optimized to prepare the particles by spray drying azithromycin dissolved FDKP microparticle suspension at pH 4.5. The in vitro antibacterial efficiency and in vitro dispersion performance was also investigated to confirm the antibacterial efficiency, dispersion and deposition behavers. FDKP/azithromycin mass ratio (3:2) was the optimized formulation of azithromycin loaded FDKP microparticle with the maximal drug loading efficiency. High-pressure homogenization and spray drying conditions were also optimized. The in vitro antibacterial results indicated that only with the antibiotic concentration higher than mutant prevention concentration could totally inhibit the reproduction of bacteria. In vitro dispersion performance of azithromycin loaded FDKP microparticles (AZM@FDKP-MPs) also shows remarkable improvement of dispersion and deposition behavers of AZM. AZM@FDKP-MPs dry powder inhalation as a targeting delivery route has better potential for lung infection treatment.
To date, investigations onto the regulation of reactants mass transfer has been paid much less attention in environmental catalysis. Herein, we demonstrated that by rationally designing the adsorption sites of multi-reactants, the pollutant destruction efficiency, product selectivity, reaction stability and secondary pollution have been all affected in the catalytic chlorobenzene oxidation (CBCO). Experimental results revealed that the co-adsorption of chlorobenzene (CB) and gaseous O2 at the oxygen vacancies of CeO2 led to remarkably high CO2 generation, owning to their short mass transfer distance on the catalyst surface, while their separated adsorptions at Brönsted HZSM-5 and CeO2 vacancies resulted in a much lower CO2 generation, and produced significant polychlorinated byproducts in the off-gas. However, this separated adsorption model yielded superior long-term stability for the CeO2/HZSM-5 catalyst, owning to the protection of CeO2 oxygen vacancies from Cl poisoning by the preferential adsorption of CB on the Brönsted acidic sites. This work unveils that design of environmental catalysts needs to consider both of the catalyst intrinsic property and reactant mass transfer; investigations of the latter could pave a new way for the development of highly efficient catalysts towards environmental pollution control.
Here, the selective adsorption behaviors of guest molecule COR in two hexamer host grids were investigated by means of scanning tunnelling microscope (STM). The assembled structures of small functional organic molecules TTBTA and TATBA were thermodynamically stable. Interestingly, the introduction of the guest molecule COR destroyed the original hexamer structure of TTBTA and combined with it to form a new triangular host-guest system. Different from TTBTA, the introduction of the guest molecule COR did not affect the six-membered ring structure of TATBA. Furthermore, the co-assembly structure of TTBTA/TATBA/COR was established and the guest molecule COR showed preferential adsorption to the TATBA host grid. Density functional theory (DFT) calculations had been performed to disclose the mechanism of the involved assemblies.
By pairing two fluorophores according to their optical properties such as absorption spectral overlap and absorptivity, fluorescent quantum yield and emission spectral separation, a bifunctional fluorescent probe, TQBF-NBD, was rationally designed and synthesized to discriminatively sense Hcy/Cys and GSH with good selectivity and sensitivity. It is noted that this probe could work under a single-wavelength excitation and displayed a mega-large Stokes shift. TQBF-NBD reacted with Hcy/Cys to give a mixed green-red fluorescence and displayed a red fluorescence upon the treatment with GSH. Distinguishable imaging of intracellular Hcy/Cys from GSH with the help of TQBF-NBD was realized in living cells and zebrafish.
A highly novel and direct synthesis of benzoxazinones was developed via Cp*Co(Ⅲ)-catalyzed C–H activation and [3+3] annulation between sulfoxonium ylides and dioxazolones. The reaction is conducted under base-free conditions and tolerates various functional groups. Starting from diverse readily available sulfoxonium ylides and dioxazolones, a variety of benzoxazinones could be synthesized in one step in 32%-75% yields.
Doping and increasing specific surface area by forming highly porous structures are two effective ways to enhance the photocatalytic performances of TiO2 particles. Here for the first time, we report a new facile method to prepare the macroporous-mesoporous C-, S-, N-doped TiO2 (C/S/N-TiO2) microspheres via polyHIPE microspheres as templates. The chemical and crystalline structures of these hierarchical porous TiO2 microspheres are analyzed with FTIR, XPS, EDS, and XRD. The macroporous-mesoporous structures are confirmed with SEM observation and BET analysis. UV–vis DRS spectra analysis shows that the band gaps of C doped TiO2, C/N doped TiO2, C/S doped TiO2 and C/S/N doped TiO2 are estimated to be 3.07, 3.01, 2.94 and 2.81 eV, respectively, which are significantly narrower than that of TiO2 nanoparticles (3.23 eV). Photoluminescence spectra demonstrate that the recombination of electrons and holes in these macroporous-mesoporous TiO2 microspheres is also suppressed. The hierarchical porous C/S/N-TiO2 microspheres show high visible-light catalytic efficiency and excellent cycling stability to degrade RhB dye.
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