Latest ArticlesNitrogen reduction reactions (NRR) under room conditions remain the challenge for N2 activation on metal-based catalysis materials. Herein, the M-doped CeO2(111) (M = Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) with oxygen vacancies, are systematically investigated by spin-polarized DFT + U calculations. We discuss briefly the situation of OVs on pure and reduced cerium, and we found that (1) doping TMs can promote the formation of oxygen defects, apart from Ti and V-dopant, (2) the O atoms are easier to escape connecting to M atoms than the ones of adjacent atoms connecting to the Ce(III), the value of OVs formation energies decrease as the TMs radius decrease. Also, our computational results show that Cr-doped, Mn-doped, Fe-doped, and Co-doped CeO2(111) adsorbs N2 strongly than the stoichiometric surface and other M-doped CeO2 surfaces with adsorption energies of −0.82, −1.02, −0.83 and −1.05 eV. Through COHP analysis, it is found that the predicted active sites have good catalytic performance.
The synthesis of high-value multi-carbon products through the electrochemical reduction of carbon monoxide (COER) is one of the promising avenues for carbon utilization and energy storage, in which searching for efficient electrocatalysts that exhibit moderate CO intermediate binding strength and low kinetic barrier for C-C coupling is a key issue. Herein, by means of comprehensive density functional theory (DFT) computations, we theoretically designed three synergistic coupling catalysts by co-doping transition metal (TM = Fe, Co and Ni) and boron (B) into the two-dimensional black phosphorene (BP), namely TM-B@BP for COER to C2 products. DFT computations and ab initio molecular dynamics simulations reveal the good stability and high feasibility of these proposed TM-B@BP catalysts for practical applications and future experimental synthesis. More interestingly, high-value ethylene (C2H4), ethane (C2H6) and ethanol (C2H5OH) products can be obtained on these three designed electrocatalysts with ultra-small limiting potentials (−0.20~−0.41 V) and low kinetic energy barriers of C-C coupling (0.52~0.91 eV). Meanwhile, the competitive one-carbon (C1) products and hydrogen evolution reaction can also be effectively suppressed. The promising activity and selectivity of these three designed electrocatalysts render them ideal candidates for CO electroreduction, thus providing a cost-effective opportunity to achieve a sustainable production of high value C2 chemicals and fuels.
Conductive hydrogels have attracted considerable attention owing to their potential for use as electronic skin and sensors. However, the loss of the inherent elasticity or conductivity in cold environments severely limits their working conditions. Generally, organic solvents or inorganic salts can be incorporated into hydrogels as cryoprotectants. However, their toxicity and/or corrosive nature as well as the significant water loss during the solvent exchange present serious difficulties. Herein, a liquid-like yet non-toxic polymer-polyethylene glycol (PEG) was attempted as one of the components of solvent for hydrogels. In the premixed PEG-water hybrid solvent, polyacrylamide (PAAm) was in situ polymerized, overcoming the inevitable water loss induced by the high osmotic pressure of the PEG solution and achieving tailored water capacity. Interestingly, the mechanical strength ("soft-to-rigid" transition) and anti-freezing properties of organohydrogels can be simultaneously tuned over a very wide range through adjusting PEG content. This was due to that with increasing PEG in solvent, the PAAm chains transformed from stretching to curling conformation, while PEG bonded with water molecules via hydrogen bonds, weakening the crystallization of water at subzero temperature. Additionally, a highly conductive Ti3C2Tx-MXene was further introduced into the organohydrogels, achieving a uniform distribution triggered by the attractive interaction between the rich functional groups of the nanofillers and the polymer chains. The nanocomposite hydrogels demonstrate high electrical conductivity and strain sensitivity, along with a wide working temperature window. Such a material can be used for monitoring human joint movement even at low temperature and has potential applications in wearable strain sensors.
Chloride ion batteries (CIB) are considered to be one of the most promising energy storage devices. As cathode materials for CIBs, metal chlorides have many advantages, such as high theoretical energy density, abundant elemental resources and ideal discharge voltage plateau. However, the dissolution and huge volume change of metal chlorides during cycling lead to considerable short lifespan, which limits their potential application for CIBs. Herein, the bismuth chloride nanocrystal is confined in mesocellular carbon foam matrix by a new vacuum impregnation approach. The mesocellular carbon foam with large interconnected pores (15.7 or 23.2 nm) may buffer the large volume variation of bismuth chloride during charge and discharge, giving rise to significantly enhanced electrochemical performance. The as-prepared bismuth chloride@mesocellular carbon foam cathode delivered an initial discharge capacity of 298 mAh/g and a reversible capacity of 91 mAh/g after 60 cycles. In contrast, the pure bismuth chloride cathode almost cannot discharge after 30 cycles. This is the first report that the metal chloride cathode can achieve a prolonged cycling in CIBs.
Although peroxidase-like nanozymes have made great progress in bioanalysis, few current nanozyme-based biosensors are constructed for discriminating isomers of organic compounds. Herein, fluorescent metal-organic framework (MOF)-based nanozyme is utilized for phenylenediamine isomers discrimination and detection. NH2-MIL-101(Fe), as a member of Fe-based MOFs, functions as not only fluorescent indicator but also peroxidase mimics. In the presence of H2O2, NH2-MIL-101(Fe) can catalyze the oxidation of o-phenylenediamine (OPD) and p-phenylenediamine (PPD) into their corresponding oxidation products (OPDox and PPDox), which in turn quench its intrinsic fluorescence at 445 nm via inner filter effect (IFE). Differently, a new fluorescence peak at 574 nm is observed for OPDox. Thus, a ratiometric fluorescence method for the detection of OPD can be designed with the fluorescence intensity ratio F574/F445 as readout. This proposed strategy displays excellent discrimination ability for three phenylenediamines and may open new applications of MOFs in environmental science.
Colorectal cancer (CRC) is still the leading cause of cancer death worldwide, but the clinical effect of drug therapy such as irinotecan is not an ideal way at present. In recent years, probiotics have attracted much attention, and the combination of probiotics may play an important role in the prevention and treatment of CRC. This work proposed a cellular chip-MS system, to study the synergistic effects of probiotic Lactobacillus rhamnosus GG (L.GG) and irinotecan on HCT116 cells by cell viability and on-line mass spectrometry (MS) analysis. The double-layer chip sandwiched with a polycarbonate membrane can co-culture HCT116 cells and L.GG. And the solid phase microextraction chip can be used for desalination and concentration. Finally, the extracted chemicals were entered the electrospray ionization quadrupole time-of-flight MS to detect irinotecan metabolites. The results showed that with the increasing concentration of co-cultured L.GG, the percentage of living HCT116 cells decreased, but the relative amount of metabolized SN-38 by HCT116 cells increased. Therefore, the microfluidic system can be used to detect and monitor the synergistic effect of irinotecan-L.GG combination on HCT116 cells. In summary, our study provided experimental evidence for the first time with potential applications of irinotecan-L.GG combination in CRC treatment, and the cellular chip-MS system as a powerful tool can be used in the experiments of probiotics as new drugs.
Azulene, one of representative nonbenzenoid aromatic hydrocarbons, exhibits unique molecular structure and distinctive physical and chemical properties. Herein, azulenoisoindigo (AzII), an azulene-based isoindigo analogue, is designed and synthesized, which has a twisted molecular backbone and R/S-isomers in single crystals. Interestingly, AzII shows the characteristics of both isoindigo and azulene, such as reversible redox behavior and reversible proton responsiveness. UV-vis-NIR, 1H NMR and electron paramagnetic resonance (EPR) measurements were carried out to get insights into the possible mechanism of the proton-responsive property of AzII. The results demonstrated that only one azulenyl moiety of molecule of AzII was protonated and deprotonated, and the protonated AzII can be further oxidized to form azulenium cation radicals.
Application of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate the spatiotemporal alterations of lipids in biological tissues has brought many significant results. However, the presence of structural isomers varying in C=C double bond (DB) locations makes isomer-resolved MSI an urgent need. Herein, we introduce a new type of light-driven on-tissue [2 + 2] cycloaddition reaction coupled with MALDI-MS/MS imaging to identify lipid DB position isomers and their spatial signatures in biological tissues. 3-Benzoylpyridine was introduced as a novel derivatization reagent, and it exhibited great reactivity toward lipid C=C bond to form oxetanes under both ultraviolet light and visible light irradiation. With this approach, DB position isomers of lipids were imaged with highly differential levels in distinct regions of rat brain, providing an accurate and spatially resolved approach to study tissue lipidomics.
Pharmaceutical salt formation is the most preferred and effective method to enhance the physicochemical properties of APIs. The aim of the study was to design and synthesize a series of new salts to improve the solubility of Imatinib (IM). Two stable salts with malonic acid (S1) and citric acid (S5), one metastable salt with fumaric acid (S2), two unstable salts with citric acid (S3, S4) were obtained for the first time. Single crystal and powder X-ray diffraction, Fourier transform infrared, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the novel salts. The solubility and stability of the solid were also evaluated, and three salts (S1, S2, S5) had a more than 20 folds of solubility and a faster dissolution rate improved as compared to the pure drug in water and pH 6.8 buffer, respectively.
N6-methyldeoxyadenosine (6mdA) modification is considered as a new epigenetic mark that may play important roles in various biological processes. However, it remains unclear about the effect of 6mdA on DNA replication in human cells. Herein, we combined next-generation sequencing with shuttle vector technology to explore how 6mdA affects the efficiency and accuracy of DNA replication in human cells. Our results showed that 6mdA neither blocked DNA replication nor induced mutations in human cells. Moreover, we found that the depletion of translesion synthesis DNA polymerase (Pol) κ, Pol η, Pol ι or Pol ζ did not significantly change the biological consequences of 6mdA during replication in human cells. The negligible impact of 6mdA on DNA replication is consistent with its potential role in epigenetic gene expression.
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