Latest ArticlesThe three-way catalyst (TWC), as a promising approach to control automobile exhaust emission, has been widely studied and applied. However, it still suffers from the high light-off temperature and poor stability. Herein, we synthesized a multicomponent catalyst Rh/Cu-CeSn by using Cu metal doping to modify the Ce-based solid solution, which exhibited good TWC catalytic performance: the light-off temperatures for CO, NO, and C3H6 conversion are 172 ℃, 266 ℃, and 193 ℃, respectively. Moreover, the catalyst still maintained good activity after 12 h of the continuous reaction under high-temperature conditions. The experiments and mechanism studies reveal that due to the redox pair Cu+/Cu2+, the Cu incorporation can effectively inhibit the Rh transition to the oxidation state and greatly enhance the catalytic activity and stability. This work provides a viable strategy for precise characteristic modulation of composite oxide supports during the fabrication of noble metal-based catalysts, which significantly reduces environmental pollution from energy applications.
Rare–earth supramolecular compounds, such as lanthanide organic polyhedrons (LOPs), are of particular interest due to their many possible applications in various fields. Here we report the first syntheses of Ln4(L•+)4–type (Ln, lanthanides; L•+, radical ligand) radical–bridged lanthanide organic tetrahedrons by self–assembly of face–capping triphenylamine (TPA)–cored radical ligand with different lanthanide ions. Remarkable coordination enhanced radical stability has been observed, with half–life times (t1/2) for L1•+, La4(L1•+)4, Eu4(L1•+)4, Gd4(L1•+)4, Tb4(L1•+)4 and Lu4(L1•+)4 estimated to be 53 min, 482 min, 624 min, 1248 min, 822 min and 347 min, respectively. The TPA radical in Ln4(L1•+)4 containing paramagnetic Ln ions (Ln = EuⅢ, GdⅢ and TbⅢ) is observed to be more stable than that in Ln4(L1•+)4 (Ln = LaⅢ and LuⅢ) constructed by diamagnetic Ln ions. This difference in radical stability is possibly due to the magnetic interactions between paramagnetic LnⅢ ions and L1•+ ligands, as confirmed by electron paramagnetic resonance (EPR) in La4(L)4 (L = L1 and L1•+) and Tb4(L)4 (L = L1 and L1•+), and magnetic susceptibility measurements in Tb4(L)4 (L = L1 and L1•+). Our study reveals the coordination of radical ligands with lanthanide ions can improve the radical stability, which is crucial for their applications.
Na3V2(PO4)3 (NVP) is regarded as alternative cathode material for sodium-ion batteries (SIBs) due to its potential high-rate performance and pronounced long-term cycle stability. However, electronic conductivity and tap density are difficult to be balanced. Herein, we report that high-temperature shock (HTS) can prepare "single crystalline like" NVP which combines high-rate capability with high tap density together into one with the assistance of carbon framework and large particle. Thus, high reversible capacity of 110 mAh/g at 0.1 C with 89.9% capacity retention after 1600 cycles at 1 C and specific capacity of 83.5 mAh/g at 50 C rate has been exhibited. This study provides a novel strategy to guide the production of high tap density, and rate performance polyanionic cathode materials.
A pseudocapacitance dominated anode material assembled from Li3VO4 nanocrystals encapsulated in the interlayers of N-doped graphene has been developed via a facile 2D nanospace confined strategy for lithium ion capacitors (LICs). In this contribution, the N-doped graphene synthesized by a faicle solid state reaction using C3N4 nanosheets as template and glucose as carbon source provides sufficient 2D nanospace for the confined and homogeneous growth of Li3VO4 at the nanoscale, and simultaneously efficiently anchors each nanobuilding block inside the interlayers, thus realizing the utilizaiton of full potential of active components. The so-formed 3D hybrids not only ensure intimate electronic coupling between active materials and N-doped graphene, but also realize robust structure integrity. Owing to these unique advantages, the resulting hybrids show pseudocapacitance dominated lithium storage behaviors with capacitive contributions of over 90% at both low and high current rates. The LVO@C@NG delivers reversible capacities of 206 mAh/g at 10 A/g, capacity retention of 92.7% after 1000 cycles at 2 A/g, and a high energy density of 113.6 Wh/kg at 231.8 W/kg for LICs.
In this work, we employed a ring-opening strategy to develop a series of novel N-benzyl arylamide derivatives as tubulin polymerization inhibitors. Notably, 13n (MY-1388) exhibited remarkable antiproliferative potency on fifteen human cancer cell lines, with half maximal inhibitory concentration (IC50) values ranging from 8 nmol/L to 48 nmol/L. Furthermore, 13n effectively suppressed tubulin polymerization by targeting the colchicine-binding site (IC50 = 0.62 µmol/L). 13n also exhibited significant inhibition of cell colony formation, as well as displayed potent effects on inducing G2/M phase cell cycle arrest and promoting apoptosis. Importantly, 13n exhibited enhanced and adequate liver microsomal stability in human and rat liver microsomes, and also exhibited a moderate half-life (T1/2 = 0.938 h) in vivo. Meanwhile, 13n demonstrated effective antitumor effects in vivo in suppressing tumor growth in the MGC-803 xenograft model (tumor growth inhibition (TGI) value was 76.4% at the dosage of 30 mg kg−1 day−1) with a good safety profile. Collectively, these results revealed that 13n represents a promising tubulin polymerization inhibitor that deserves further investigation for its efficacy in treating gastric cancers.
In chemical science, the vertical ionization potential (VIP) is a crucial metric for understanding the electronegativity, hardness and softness of chemical material systems as well as the electronic structure and stability of molecules. Ever since the last century, the model chemistry composite methods have witnessed tremendous developments in computing the thermodynamic properties as well as the barrier heights. However, their performance in realm of the vertical electron processes of molecular systems has been rarely explored. In this study, we for the first time benchmarked the model chemistry composite methods (e.g., CBS-QB3, G4 and W1BD) in comparison with the commonly used Koopmans's theorem (KT), electron propagator theory (e.g., OVGF, D2, P3 and P3+) and CCSD(T) methods in calculating the VIP for up to 613 molecular systems with available experimental measurements. The large-scale test calculations strongly showed that the CBS-QB3 model chemistry composite technique can be well recommended to calculate VIP from the perspectives of accuracy, economy and applicability. Notably, the VIP values of up to 7 molecules were identified to have the absolute errors of larger than 0.3 eV at all calculation levels, which have strong hints that their VIP experimental values should be re-investigated.
It is of great significance to find safe and effective radiosensitizers. A primary investigation has been made on fisetin’s modification of radiation effect, but its radiosensitization and related mechanisms still need to be deeply clarified. Furthermore, fisetin with high hydrophobicity is difficult to dissolve in water, severely limiting its research and application. In this study, we fabricated a safe and soluble radiosensitizer fisetin micelle for precisely enhancing radiotherapy by inhibiting platelet-derived growth factor receptor-β (PDGFRβ)/signal transducer and activator of transcription 1 (STAT1)/signal transducer and activator of transcription 3 (STAT3)/B cell lymphoma 2 (Bcl-2) signaling pathway in the tumor. Systematic and detailed studies were performed to verify its radiosensitization effect in vitro and in vivo. On the cellular level, fisetin micelles selectively increased the radiosensitivity of tumor cells (CT26 and 4T1 cells) and had little effect on the sensitivity of normal mouse cells (L929 cells) to radiation. In the mouse models of colon and breast cancers, fisetin micelles showed an efficient radiosensitization capacity without apparent toxicity. Additionally, we first found that fisetin micelles played a radiotherapy sensitization role by inhibiting the PDGFRβ/STAT1/STAT3/Bcl-2 pathway activity. In general, this work not only confirmed that fisetin micelles precisely exhibit a radiosensitization effect in vitro and in vivo, but also profoundly explored its mechanisms underlying, to provide a theoretical and experimental basis for the clinical application of fisetin micelles.
Planktonic bacteria adhere and subsequently form biofilms on implantable medical devices can cause severe infections that have become the major types of hospital-acquired infections. Traditional coatings for the implants are frequently lack of long-term antifouling and bactericidal activities. It is still a big challenge to simultaneously improve the antifouling and bactericidal activities of the coatings. Herein, we report that mixed-charge glycopolypeptide coatings are of long-term antibacterial activities to efficiently inhibit the biofilm growth. The glycosylation of mixed-charge polypeptides has led to a significant improvement of both antifouling and bactericidal activities. The cooperative effect of the saccharide residues and mixed-charge residues improved the resistance of the polypeptide coatings against protein adsorption. The saccharide and L-glutamic acid (E) residues collectively enhanced the bacterial membrane-disruption of cationic L-lysine (K) residues, leading to potent bactericidal activity. Meanwhile, the glycopolypeptide coatings showed superior biocompatibility, long-term antibiofilm and anti-infection properties in two types of mouse subcutaneous infection models and one type of mouse urinary tract infection model. This work provides a new strategy to achieve antibacterial coatings with long-term activities for preventing implantable medical device associated infections.
The preparation of immobilized enzyme with excellent performance is one of the difficulties that restrict the application of enzyme catalysis technology. Here, Candida rugosa lipase (CRL) was firstly adsorbed on the surface of magnetic zeolitic imidazolate framework-8 (ZIF-8) nanospheres, which was further encapsulated with a mesoporous SiO2 nano-membrane formed by tetraethyl orthosilicate (TEOS) polycondensation. Consequently, lipase could be firmly immobilized on carrier surface by physical binding rather than chemical binding, which did not damage the active conformation of enzyme. There were mesopores on the silica nano-membrane, which could improve the accessibility of enzyme and its apparent catalytic activity. Moreover, silica membrane encapsulation could also improve the stability of enzyme, suggesting an effective enzyme immobilization strategy. It showed that TEOS amount and the encapsulation time had significant effects on the thickness of silica membrane and the enzyme activity. The analysis in enzyme activity and protein secondary structure showed that lipase encapsulated in silica membrane retained the active conformation to the greatest extent. Compared with the adsorbed lipase, the encapsulated lipase increased its thermostability by 3 times and resistance to chemical denaturants by 7 times. The relative enzyme activity remained around 80% after 8 repetitions, while the adsorbed lipase only remained at 7.3%.
Skins expose to kinds of risk factors for damage, such as the hormone drugs, skin care products and ultraviolet radiation, which is accompanied by the production of excessive reactive oxygen species (ROS) and eventually leads to hypertrichosis. This skin disease is not aesthetically pleasing and even causes psychological and spiritual problems such as inferiority, anxiety and irritability. Current therapies are limited and often unsatisfactory, such as pharmacological and physical therapies, which have adverse effects and cause the irreversible destruction of hair follicles. Gold nanoclusters have good biocompatibility and their biosynthesis in vivo is responsive to oxidative stress microenvironment (OSM), which could be a safe and effective drug for ROS-induced skin injury. In our study, we demonstrated that zero valence fluorescent gold nanoclusters (FGNCs) were in situ biosynthesized in the plucking-induced damaged skin but not in the normal skin after the administration of gold precursors (+3), while FGNCs inhibited hair follicle regeneration by negatively regulating nuclear transcription factor kappa B (NFκB)-mediated inflammatory response signaling pathway (NFκB/tumor necrosis factor-α (TNF-α) axis). This OSM-responsive in situ biosynthesis method is facile and safe and holds great promise for curing hypertrichosis associated with skin dermatitis and injury.
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