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The SETD3 enzyme has been identified as the methyltransferase for the His73 methylation in β-actin, and such methylation plays an important role in regulating the actin's biochemical properties and fine-tuning the protein's cellular roles. Further studies have demonstrated that SETD3 may be able to methylase some other residues, including lysine and methionine, that substitute His73 in the β-actin peptide. The activity of SETD3 on the Met73 peptide is low without turnover. Interestingly, it has been shown that the N255V and N255A mutations of SETD3 can increase the activity by about 3-fold for the methionine methylation, while such mutations lead to a significant reduction of k

The maintenance of neural stem cells (NSCs) plays a critical role in neurodevelopment and has been implicated in neurodevelopmental disorders (NDDs). However, the underlying mechanisms linking defective human neural stem cell self-renewal to NDDs remain undetermined. Our previous study found that Supt16 haploinsufficiency causes cognitive and social behavior deficits by disrupting the stemness maintenance of NSCs in mice. However, its effects and underlying mechanisms have not been elucidated in human neural stem cells (hNSCs). Here, we generated Supt16+/− induced pluripotent stem cells (iPSCs) and induced them into hNSCs. The results revealed that Supt16 heterozygous hNSCs exhibit impaired proliferation, cell cycle arrest, and increased apoptosis. As the RNA-seq analysis showed, Supt16 haploinsufficiency inhibited the PI3K/AKT/mTOR pathway, leading to rising autophagy, and further resulted in the dysregulated expression of multiple proteins related to cell proliferation and apoptotic process. Furthermore, the suppression of Supt16 heterozygous hNSC self-renewal caused by autophagy activation could be rescued by MHY1485 treatment or reproduced in rapamycin-treated hNSCs. Thus, our results showed that Supt16 was essential for hNSC self-renewal and its haploinsufficiency led to cell cycle arrest, impaired cell proliferation, and increased apoptosis of hNSCs by regulating the PI3K/AKT/mTOR/autophagy pathway. These provided a new insight to understand the causality between the Supt16 heterozygous NSCs and NDDs in humans.

Along with the continuous consumption in lithium-ion batteries (LIBs), the price of cobalt is inevitably going up in recent years. Therefore, recycling valuable Co element from spent devices, and boosting its service efficiency are becoming two indispensable approaches to promote the utilization of Co in various energy conversion/storage devices. Herein, we realize the recovery of Co from spent LIBs and synthesize a three–dimensional (3D) sea-urchin-like cobalt nitride composite material (labeled as CoN-Gr-2), which is used as a bi-functional catalyst for water splitting. Benefiting from the intrinsic high conductivity, larger surface area and unique 3D sea–urchin–like architecture, CoN-Gr-2 shows an excellent electron transfer efficiency, highly exposed active sites as well as the superior mass transport capacity. The CoN-Gr-2 catalyst exhibits low overpotentials of 128.9 mV and 280 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are comparable to the commercial 20 wt% Pt/C and RuO2 catalysts. Moreover, when adopting CoN-Gr-2 as both anode and cathode materials for overall water splitting (in 1.0 M KOH electrolyte), the assembled cell achieves a current density of 10 mA cm−2 at 1.61 V, which almost close to that of Pt/C||RuO2 benchmark (1.60 V), demonstrating its superior water-splitting efficiency. Meanwhile, the CoN catalysts exhibit strong chemical interaction with the Gr support, suppressing the aggregation of CoN catalysts and maintains their high activity during HER and OER reactions. So, the cell exhibits a high current retention of 97.3% after 40 h. This work successfully develops an industrial chain from recycling Co wastes in spent energy devices to controllably designing 3D sea-urchin-like CoN-Gr with high water splitting efficiency. Therefore, it could further promote the efficient utilization of valuable Co element in various energy devices.

The high theoretical energy density and low cost make lithium-sulfur (Li-S) batteries an ideal choice for next-generation energy storage devices. However, the slow kinetics cause the reaction process to be incomplete and low reaction rate. To solve this problem, a novel cooperative catalytic interface with fine molecular regulation mechanism is designed by taking advantage of the electronic correlation between the catalyst and polysulfides (LiPSs), which multi-step process contains chemical adsorption, catalytic activity center and lithium-ion transfer. The cooperative catalytic interface greatly accelerates the kinetics of LiPSs conversion, precipitation of Li2S in discharging, and insoluble Li2S decomposition in charging process. Therefore, the PdNi@ND-C3N4-based cathode exhibits an outstanding electrochemical performance. Even under the condition of high sulfur loading of 6.0 mg cm−2, the constructed Li-S batteries demonstrate the ultralow capacity decay rate of 0.025% per cycle up to 1000 cycles. Moreover, its catalytic mechanism is deeply analyzed through DFT theory and in(ex)-situ technologies. This work will open a new window for the rational design of Li-S electrocatalyst based on cooperative interface.

Because of the importance of polyfunctional amines, C-N bond formation is important in synthetic organic chemistry. Here we present a neutral amination reaction using azides as the nitrogen source and arylboronic acids with a rhodium(I) catalyst to afford alkyl-aryl and aryl-aryl secondary amines. Natural products and pharmaceutical derivatives were applied, and gram-scale reactions were performed, which demonstrated the utility. Mechanistic experiments and DFT calculations suggested that the reaction involves a metal-nitrene intermediate.

Investigating how electrons propagate through a single molecule is one of the missions of molecular electronics. Electrons, however, are also efficient catalysts for conducting radical reactions, a property that is often overlooked by chemists. Special attention should be paid to electron catalysis when interpreting single-molecule conductance results for the simple reason that an unexpected reaction mediated or triggered by electrons might take place in the single-molecule junction. Here, we describe a counterintuitive structure-property relationship that molecules, both linear and cyclic, employing a saturated bipyridinium-ethane backbone, display a similar conductance signature when compared to junctions formed with molecules containing conjugated bipyridinium-ethene backbones. We describe an ethane-to-ethene transformation, which proceeds in the single-molecule junction by an electron-catalyzed dehydrogenation. Electrochemically based ensemble experiments and theoretical calculations have revealed that the electrons trigger the redox process, and the electric field promotes the dehydrogenation. This finding not only demonstrates the importance of electron catalysis when interpreting experimental results, but also charts a pathway to gaining more insight into the mechanism of electrocatalytic hydrogen production at the single-molecule level.

To deal with the relatively low HER catalysis efficiencies of existing cobalt nitride (CoN) catalysts, it is highly desirable to design new types of CoN catalysts to realize high-efficiency water splitting. Herein, by using simple hydrothermal and nitridation methods, we realize the synthesis of novel three-dimensional (3D) flower-like CoN (CoN-F), CoN porous spheres (CoN-S), and polyhedral CoN (CoN-P) via utilizing various weak bases. Benefiting from a much larger surface area and a unique 3D flower-like architecture (consisting of 2D porous CoN nanosheets), the CoN-F catalyst shows highly exposed active sites and superior mass/electron transfer abilities. Naturally, the CoN-F catalyst exhibits more outstanding hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic performance than either CoN-P or CoN-S. In order to achieve a current density of 10 mA cm−2, 3D flower-like CoN-F needs only low overpotentials of 191.7 mV and 276.2 mV for the HER and OER, respectively. Furthermore, upon using the 3D flower-like CoN-F catalyst as both the anode and cathode material in a two-electrode overall water-splitting cell, the corresponding (−)CoN-F‖CoN-F(+) cell achieves a current density of 10 mA cm−2 at 1.613 V in 1.0 M KOH, which is just 10 mV larger than a (−)Pt/C‖RuO2(+) cell (1.592 V). It outperforms most existing non-precious-metal electrocatalysts, demonstrating superior water-splitting efficiency. In addition, the 3D flower-like CoN-F catalyst shows excellent stability during the alkaline HER and OER, and full water splitting. This work successfully opens a new pathway for boosting the HER/OER electrocatalytic abilities of CoN catalysts through structural design, which may promote the efficient utilization of metal nitrides in various energy storage and conversion devices.

A novel STING agonist, CDGSF, ipsilaterally modified with phosphorothioate and fluorine, was synthesized. The phosphorothioate in CDGSF might be a site for covalent conjugation. Injection of CDGSF generated an immunogenic ("hot") tumor microenvironment to suppress melanoma, more efficiently than dithio CDG. In particular, immunization with SARS-CoV-2 spike protein using CDGSF as an adjuvant elicited an exceptionally high antibody titer and a robust T cell response, overcoming the drawbacks of aluminum hydroxide. These results highlighted the therapeutic potential of CDGSF for cancer immunotherapy and the adjuvant potential of the STING agonist in the SARS-CoV-2 vaccine for the first time.

A novel water-soluble near-infrared fluorescent probe named QX-P with simple synthesis is developed. QX-P has high sensitivity and selectivity to ALP. Moreover, the probe can not only visualize ALP activity in four cell lines, but also real-time image ALP activity during the diagnosis and treatment of diabetes in mice.

The cycloaddition mechanisms of CO2 and epichlorohydrin catalyzed by salophen as an organocatalyst were investigated using B3LYP density functional theory computations. The kinetically most favored neutral pathway involves a concerted and synergistic mechanism of phenolate as a nucleophile and phenol as a H-bonding donor in epoxide ring opening and CO2 addition. The computed apparent barrier (33 kcal mol−1) is in line with the reaction conditions (120 °C and 10 bar CO2). A similar and anionic route with a much lower apparent barrier (17 kcal mol−1) to react under milder conditions has been proposed and this has to be proven experimentally.

The SETD3 enzyme adds a methyl group to Ne2 of His73 in β-actin, and such methylation finetunes actin’s biochemical properties and cellular function. Here, quantum mechanics/molecular mechanics mol...

The properties of Sn-Ce solid solution have a significant effect on the CO oxidation performance of the Pd/Sn1-xCexO2 catalyst. Herein, we compared the effects of Sn-rich and Ce-rich supports on the catalytic performance of the Pd/Sn1-xCexO2 catalysts. Our results show that the active oxygen species on the Ce-rich and Sn-rich supports are mainly the lattice oxygen species and the chemisorbed oxygen species, respectively. Although the active oxygen species on the Ce-rich supports have higher intrinsic activity, the active oxygen species on the Sn-rich supports have better mobility. It leads to an interesting phenomenon that the change trend of the activity of the Pd/Sn1-xCexO2 catalysts with temperature is consistent with that of their supports. Compared with the Ce-rich supports and the corresponding supported Pd catalysts, the catalytic activity of the Sn-rich supports and the corresponding supported Pd catalysts increased faster with the increase of temperature.

Direct CO2 conversion from flue gas into high-value products is of great significance not only in relieving environmental burden but alleviating the energy crisis by a low-cost and energy-saving avenue, yet few studies in this aspect have been reported. Herein, we report metal-node-dependent catalytic performance for solar-energy-powered CO2 reduction to formate in simulated flue gas by bimetallic Ni/Mg-MOF-74. The yield of HCOO− with Ni0.75Mg0.25-MOF-74 as a catalyst in pure CO2 is 0.64 mmol h−1 gMOF−1 which is higher than that of Ni-MOF-74 (0.29 mmol h−1 gMOF−1) and Ni0.87Mg0.13-MOF-74 (0.54 mmol h−1 gMOF−1), whereas monometallic Mg-MOF-74 is almost inactive, indicating that reactivity relies on metal nodes. In simulated flue gas without water vapor at 20 °C, ∼80% of the reactivity in pure CO2 is retained, with HCOO− generation reaching 0.52 mmol h−1 gMOF−1. This activity is comparable to that of the best MOF catalysts in pure CO2, demonstrating that Ni/Mg-MOF-74 not only overcomes the limitation from CO2 concentration, but also has good resistance to other gas components in flue gas at 20 °C. DFT calculations reveal the high output for HCOO− from two crucial factors: strong CO2 binding affinity of Mg sites, and the synergistic effect of Mg and Ni leading to the stabilization of the key *OCOH intermediate with an appropriate energy barrier. This work paves a new route for double-metal MOFs to enhance the CO2 photoreduction reactivity in flue gas.

We developed a green and facile approach for synthesizing Ag@PP6@SWCNT nano-material via in-situ loading silver nanoparticles on the surface of phosphate pillar [6]arene (PP6) functionalized single-walled carbon nanotubes (SWCNT) at room temperature and without using either toxic or organic solvents. Ag nanoparticles (with an average size of 3–4 nm) were uniformly dispersed on the surface of SWCNT via the anchoring effect of PP6. PP6 provided a coordination environment between Ag and –PO 3 2– groups in PP6, and there were the π-π interactions between SWCNT and benzene rings of PP6. The obtained hybrid nano-material Ag@PP6@SWCNT was characterized using UV-vis absorption spectrum, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Compared to commercial Pd/C and Ag@SWCNT catalysts, Ag@PP6@SWCNT exhibited higher catalytic activity for 4-nitrophenol (4-NP) reduction and methylene blue (MB) degradation, respectively. Moreover, because of the excellent supramolecular host-guest recognition capability of PP6, a sensitive and convenient electrochemical sensing platform for detecting paraquat (PQ) was constructed, and had potential applications in sensing highly toxic herbicides.

International audience; The aim of molecular electronics is to miniaturize active electronic devices and ultimately construct single-molecule nanocircuits using molecules with diverse structures featuring various functions, which is extremely challenging. Here, we realize a gate-controlled rectifying function (the on/off ratio reaches ∼60) and a high-performance field effect (maximum on/off ratio >100) simultaneously in an initially symmetric single-molecule photoswitch comprising a dinuclear ruthenium-diarylethene (Ru-DAE) complex sandwiched covalently between graphene electrodes. Both experimental and theoretical results consistently demonstrate that the initially degenerated frontier molecular orbitals localized at each Ru fragment in the open-ring Ru-DAE molecule can be tuned separately and shift asymmetrically under gate electric fields. This symmetric orbital shifting (AOS) lifts the degeneracy and breaks the molecular symmetry, which is not only essential to achieve a diode-like behavior with tunable rectification ratio and controlled polarity, but also enhances the field-effect on/off ratio at the rectification direction. In addition, this gate-controlled symmetry-breaking effect can be switched on/off by isomerizing the DAE unit between its open-ring and closed-ring forms with light stimulus. This new scheme offers a general and efficient strategy to build high-performance multifunctional molecular nanocircuits.

Summary Ammonia is one of the most important bulk chemicals in modern society. However, the highly energy-extensive contemporary industrial production of ammonia was developed in the early 20th century and requires extensive heating of highly pressurized flammable hydrogen gas, whose global production still relies heavily on non-sustainable petroleum. The development of “sustainable” nitrogen fixation process represents a grand aspirational chemical pursuit concerning our future human well-being. Herein, we report an ultra-stable nitride-based photosensitizing semiconductor that enables efficient, sustainable, and mild photochemical nitrogen fixation. The catalyst exhibits strong chemisorption of nitrogen and enables immediate electron donation from its surface vacancy to nitrogen. In addition, it was also demonstrated that the nitride-based semiconductor possesses the potential to minimize electron-hole recombination., Graphical Abstract, Highlights • Efficient photo-N2 fixation • Strong chemisorption of N2 • Uses water as H source, Chemical Reaction; Catalysis; Density Functional Theory (DFT); Nanostructure

To design and prepare heterogeneous catalysts with both high catalytic activity and good stability is still a challenge. Herein, we fabricated a composite Cu/PS-b-PAA film consisting of unique nanoflowers for the heterogeneous catalytic reactions such as hydrogenation of nitroarenes in aqueous solutions at the planar liquid/liquid interface through the interfacial adsorption and self-assembly process. The nanoflowers are comprised of nanoplates with a thickness of about 10 nm. The nanoplates have layered structure composed of an inner layer of hydrophobic PS and two surface layers of hydrophilic PAA where the copper species are dispersed. The composite film exhibited high catalytic activity for the reduction of p-nitroaniline (p-NA) in aqueous solutions and the rate constant reached to 396.45 s−1 g−1. Inaddition, the composite film also showed good stability and high recyclability without any changes in the rate constant and conversion efficiency in 15 successive cycles. These should be attributed to the special structure of the composite nanoflowers. We developed an excellent heterogeneous catalyst system possessed of both high activity and good stability through delicate design and fabrication.

An efficient and completely β-stereoselective glycosylation that did not rely on neighboring group participation is described using 2–20 mol% FeCl3/C as the catalyst and benzylated propargyl glycosides as the donors to reach yields up to 96% under mild condition. With an octatomic-ring intermediate at the α-face of FeCl3/C with alkyne of propargyl glycosides, a panel of aglycones comprising aliphatic, alicyclic, unsaturated alcohols, halogenated alcohols, and phenols with different substitution were examined successfully for the exclusive β-stereoselective glycosylation reaction.

Summary As an important effort to secure the sustainable “fossil alternative,” the direct conversion of the more readily available methanol to the more user-friendly, less toxic, and broadly applicable ethanol poses exciting potential as well as a tremendous scientific challenge. Herein, we report the first photo-driven one-step conversion of methanol to ethanol at ambient temperature, catalyzed by an ultra-stable gallium nitride semiconductor. Mechanistic studies revealed that methyl carbene (methylene), one of the most fascinating C1 building blocks in synthetic chemistry, was generated as a reaction intermediate, which potentially enables a green and novel method for generating carbene. We also found that methanol can be converted to n-propyl alcohol with the same catalyst through a simple change in reaction temperature, giving a unique selectivity and a high-value-added product.

A facile and clean strategy is developed here to synthesize the Au@HP5@SWCNT nanocomposite via in-site loading of Au nanoparticles onto the surface of hydroxyl pillar[5]arene (HP5) functionalized single-walled carbon nanotubes (SWCNT). The process is achieved by π–π stacking and the coordination effect at room temperature, which avoids using toxic chemicals such as N2H4, NaBH4, and organic solvent. The Au nanoparticles with an average size of ∼10 nm are dispersed on the surface of SWCNT by the anchoring effect of HP5 that provides the coordination role between Au and the hydroxyl oxygen in HP5, and by the π–π interaction between SWCNT and the benzene rings of HP5. The obtained hybrid nanomaterial Au@HP5@SWCNT has shown high catalytic activity for the ethanol oxidation reaction (EOR), due to the small sized Au nanoparticles, and the sensitive sensing performance for p-dinitrobenzene (p-DNB) based on the excellent supramolecular host–guest recognition capability of HP5. This nanomaterial, Au@HP5@SWCNT, exhibits preeminent catalysis and sensing properties compared with others including SWCNT, Au@HP5, and HP5@SWCNT, and so has potential value in catalyzing, sensing, and in other fields.

Development of efficient, selective and low-cost photocatalysts, ideally constructed from Earth-abundant elements, is still a big challenge for CO2 photoreduction. Herein, adopting mixed halides strategy, the activity of all-inorganic perovskites toward CO2 reduction is enhanced sharply under simulated sunlight without photosensitizer, meanwhile maintaining high selectivity of CO and CH4 production. Via regulating ratio of Br and Cl, the yield of CO and CH4 changes obviously and the optimized catalyst is CsPb(Br0.5/Cl0.5)3 with a total yield of CO and CH4 up to 875 μmol/g (selectivity of 99%) which outperforms any other reported halide perovskites and is 4.5 and 9.1 folds higher than that of CsPbBr3 and CsPbCl3 under the same condition. The efficient charge separation and moderate stability in mixed-halide perovskites may account for the excellent performance in CO2 reduction. This study may provide a new strategy in design of high performance and low-cost halide perovskite materials for photocatalysis.

We developed a late-stage modification strategy by a phospha-Michael addition reaction between various functional phosphines and unprotected dehydroalanine (Dha) peptides and proteins under mild conditions. This strategy was applied to generate a staple peptide to enhance its cell membrane penetrability, and it was also able to regulate α-synuclein aggregation properties and morphological characteristics with the addition of different charges.

Iron phthalocyanine (FePc) with unique iron-pyrrolic nitrogen (Fe-N) structure has attracted an increasing attention on the oxygen reduction reaction (ORR). Unfortunately, the Fe-N site is not “active” because of its symmetry in the plane and always exhibits unsatisfactory ORR activity. Herein, we design a non-contact scheme of axial carbon substrate induced Fe-N electron localization to improve its ORR performance. Theoretical calculation indicates that the addition of MWCNTs causes the aggregation of electron cloud around Fe-N, enhances the oxygen adsorption capacity and accelerates the ORR rate. The obtained catalyst shows a Tafel slope of 35.8 mV·dec−1, an initial potential of 0.979 V vs. RHE, a half-wave potential of 0.902 V vs. RHE and a limiting current density of 5.42 mA·cm−2 in alkaline medium. The Zn-air battery assembled by this catalyst also demonstrates a large discharge voltage of 1.296 V, considerable power density of 102 mW·cm−2 and superior cycling stability (500 cycles). This work not only simplifies the process of preparing high efficiency transition metal catalysts but also does some tentative explore for realizing the practical use of Zn-air battery.

QM/MM molecular dynamics and potential of mean force (PMF) free-energy simulations are performed for wild-type PRMT7 and E172Q, E181Q, and Q329A mutants in this work, and the catalytic mechanism, product specificity, and the role of key residues for the PRMT7 activity are investigated. The main strategies of PRMT7 in reducing the activation barrier for methyl transfer that are found in this study include (1) formation of reactive (near attack) conformations for the substrate Arg, (2) strengthening the active-site interactions at the transition state, and (3) generation of more effective nucleophiles by changing charge distributions on the target Arg through active-site interactions. More importantly, it is shown that it is a combination of these different factors that determines the PRMT7 methylation activity and substrate/product specificity. By taking these factors into consideration, it is possible to provide explanations for the observed effects of some mutations. For E172Q, E181Q, and Q329A, the simulation results suggest that E172Q has the least activity among the three mutants. The free energy barrier increases by 7 and 3 kcal/mol, respectively, as a result of the E181 → Q and Q329 → A mutations. The results showed that PRMT7 has a preference of adding a methyl group to the ω-guanidino nitrogen Nη2 atom of the substrate Arg and that the second methylation reactions cannot occur, which are consistent with previous investigations.

Methylation of lysine residues in histone proteins is catalyzed by S-adenosylmethionine (SAM)-dependent histone lysine methyltransferases (KMTs), a genuinely important class of epigenetic enzymes of biomedical interest. Here we report synthetic, mass spectrometric, NMR spectroscopic and quantum mechanical/molecular mechanical (QM/MM) molecular dynamics studies on KMT-catalyzed methylation of histone peptides that contain lysine and its sterically demanding analogs. Our synergistic experimental and computational work demonstrates that human KMTs have a capacity to catalyze methylation of slightly bulkier lysine analogs, but lack the activity for analogs that possess larger aromatic side chains. Overall, this study provides an important chemical insight into molecular requirements that contribute to efficient KMT catalysis and expands the substrate scope of KMT-catalyzed methylation reactions.

Interface engineering in heterogeneous catalysis is fascinating because of the modulation of charge-transfer processes and catalytic activity. Herein, by constructing Fe(III)–TiO2 systems with diff...

Heterogeneous catalytic reactions usually proceed at the surfaces of materials, where many intermediates, such as free radicals, usually were believed to be short-lived. Herein, surface long-lived superoxide radicals (O2˙−) were identified in UV-irradiated aqueous suspensions of TiO2 and other metal oxide nanoparticles using an online chemiluminescence system. From the decay dynamics process of O2˙−, a long-lived O2˙− radical was observed on anatase TiO2 at pH = 12. After separation of the photo-excited suspension via filtration, CL was detected from the particles but not the filtrate, thus confirming O2˙− surface adsorption. The unusual stability of O2˙− was also verified using density functional theory (DFT) calculations. The lifetimes of the radicals were estimated on the different kinds of semiconductor surface according to the decay dynamics curves, and followed the order: TiO2 > ZnO > SnO2 > CeO2 > Fe2O3. Furthermore, the function of surface long-lived O2˙− in TiO2 suspensions with regards to photochemical conversion was investigated using NBT as a chemical model; it was found that half of the molecules were reduced by the surface-adsorbed O2˙−. The finding of surface-stabilized, long-lived superoxide radicals may have important implications in relation to the chemistry, biology and toxicology of these radicals.

Cyclic di-GMP (CDG) was applied to MUC1 glycopeptide-based cancer vaccines with physical mixing and built-in (at 2'-OH of CDG) strategies for activating the STING pathway. CDG in both strategies behaved as a potent immunostimulant and contributed to high titers of IgG antibodies and the expression of multiple cytokines.

Herein, we report the performance of the catalytic oxidizing, trapping and releasing NO over the MnO x (Mn 2 O 3 , Mn 3 O 4 and MnO 2 ) model Lean NO x Traps (LNT) catalysts at low temperatures (≤ 200 °C). Among these typical MnO x samples, Mn 2 O 3 has the high NO oxidizability, and can efficiently trap and release NO x in the alternative lean-burn/fuel-rich atmospheres. Our characterization results show that enrichment of the Mn 3+ cations and active surface oxygen species probably plays the important role for NO oxidation. Although MnO 2 has the biggest NO x storage capacity in the lean-burn atmosphere, the strong adsorption strength between MnO 2 and NO x inhibits the release of the stored NO x species in the fuel-rich atmosphere. The in situ DRIFTS and NO-TPD studies indicate that the trapped NO x on Mn 2 O 3 can transform from nitro compounds to nitrites, and then to nitrates along with the increased adsorption temperature.

Herein, we designed a new NOx storage and reduction CuO/K2CO3/MgAl2O4 catalyst operating within the high temperature region of 350–550 °C. Compared with the Al2O3 supported catalyst with the same Cu and K loading, it exhibits superior NOx storage and reduction performance. The NOx reduction percentage (NRP) of the CuO/K2CO3/MgAl2O4 catalyst remains above 90% over a wide temperature range (400–550 °C), and reaches the highest NRP of 99.9% at 450 °C with the N2 selectivity of 99.7%. Uncovered CuO particles with better reducibility exist on the CuO/K2CO3/MgAl2O4 catalyst, with the high NOx oxidation and reduction ability above 400 °C. Potassium carbonates on the CuO/K2CO3/MgAl2O4 catalyst mainly exist in three forms, including free ionic carbonate, bridging bidentate carbonate and chelating bidentate carbonate. Under lean-burn conditions, most of carbonates on the CuO/K2CO3/MgAl2O4 catalyst can store NOx to form nitrates, but only parts of them participate in NOx storage on the CuO/K2CO3/Al2O3 catalyst. The MgAl2O4 support offers additional sites for NOx adsorption, while the formed nitrate on it shows low thermal stability. So, NOx is mainly stored on K2CO3 at high temperatures, because MgAl2O4 can enhance the thermal stability of the supported K2CO3 on it. Our results show that the thermal stability of K2CO3 directly determines the thermal stability of the formed nitrates. Accordingly, the CuO/K2CO3/MgAl2O4 catalyst shows the high NSR activity because of the efficient redox ability of CuO and high thermal stability of K2CO3 at high operating temperatures.

Hexagonal ultrathin nanoplates of basic lead carbonates were synthesized in aqueous lead acetate solution under ambient conditions. The sizes of the nanoplates were found to reach several hundreds of nanometers to micrometers, whereas the plate thickness was only several nanometers, corresponding to 3, 4, or 5 stacking layers along the c-axis. These nanoplates exhibited effective catalytic properties for the hydrogenation of nitroarenes, such as nitrobenzene, 4-nitroaniline, and 4-nitrophenol, and other organic dyes, such as methylene blue and methyl orange in aqueous solutions in the presence of KBH4. Pb nanoclusters were generated in situ during the catalytic process and were well dispersed on the surface of the nanoplates, leading to the formation of a zero-dimensional/two-dimensional (0D/2D) heterostructure. It was also found that the heterostructure exhibited different catalytic behaviors for the hydrogenation of the compounds mentioned above due to the different molecular structures and different adsorption and desorption abilities of the reactants and products. Such a heterostructure can be also anticipated to be an effective photocatalyst due to its strong UV-light absorption, the ultrathin characteristics of the highly crystalline nanoplates and the transfer abilities of the Pb nanoparticles.

UB3LYP computation including dispersion and toluene solvation has been carried to elucidate the mechanisms of alkene hydrogenation catalyzed by bis(imino)pyridine iron dinitrogen complex (iPrPDI)Fe(N2)2, which has low stability towards N2 dissociation. The coordinatively unsaturated complexes, (iPrPDI)Fe(N2) and (iPrPDI)Fe(1-C4H8), favor open-shell singlet ground states. On the basis of our computations, we propose a new mechanism of 1-butene coordination and hydrogenation after N2 dissociation. The hydrogenation of 1-butene undergoes a concerted open-shell singlet transition state involving H2 dissociation, C-H bond formation and C=C bond elongation, as well as the subsequent C-H reductive elimination. In the whole alkene hydrogenation, the H-H bond cleavage is the rate-determining step.

Histone lysine methyltransferases (KMTs) are biomedicinally important class of epigenetic enzymes that catalyse methylation of lysine residues in histones and other proteins. Enzymatic and computational studies on the simplest lysine analogues that possess a modified main chain demonstrate that the lysine's backbone contributes significantly to functional KMT binding and catalysis.

Two new flavonoids, 1 and 2, together with two known flavonoids, tephrosin (3) and 12a-hydroxy-α-toxicarol (4), were isolated from the whole herb of Derris eriocarpa How. The structures and absolute configurations of the new compounds were elucidated on the basis of their MS, NMR, and ECD data. The structures of the known compounds were established by extensive spectroscopic (MS, 1D- and 2D-NMR) analyses and comparison with the literature data. All compounds were isolated from D. eriocarpa for the first time. Compound 3 showed modest inhibitory activities against the growth of human cancer cells HEL and A549 with the IC50 values of 15.03 ± 0.62 and 13.27 ± 0.39 μm, respectively.

Environment-friendly metal-free photocatalysts represent a promising alternative to conventional metal-based semiconductors. In this report, a carbon dots (CDs) decorated graphitic carbon nitride (g-C3N4) photocatalyst was synthesized via a facile impregnation-thermal method. Under visible light irradiation, a very low CDs content of 0.5 web in the g-C3N4/CDs composite resulted in a 3.7 times faster reaction rate for phenol photodegradation than pristine g-C3N4. Spectroscopic and photoelectrochemical characterizations revealed that impregnation of CDs into g-C3N4 not only enhanced the production of photogenerated electron-hole pairs by extending the visible light absorption region due to the upconverted photoluminescence character of CDs, but also facilitated electron-hole separation by band alignment in the g-C3N4/CDs junction, thus yielded more holes, O-center dot(2)- and (OH)-O-center dot radicals to promote phenol degradation. These results highlight the potential application of sustainable metal-free photocatalysts in water purification. (C) 2015 Elsevier B.V. All rights reserved.

Gardenoside is one of the most important effective extractions of a herb for its hepatoprotective properties. The aim of this study was to address the mechanism of Gardenoside on HepG2 cellular steatosis induced by free fatty acids (FFAs). The model of HepG2 steatosis was duplicated by oleic and palmitic acid at the proportion of 2:1 (FFAs mixture) for 24 h, then lipid toxicity was induced. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) were used to detect cell viability and Oil Red O staining method was used to judge the lipid accumulation respectively. Inflammatory cytokines TNF-α, IL-1β, IL-6 and intracellular NFκB were measured after 24 h. The steatosis was significantly decreased after Gardenoside treatment without cytotoxicity. TNF-α, IL-1β, IL-6 were modulated to HepG2 cells by treatment of Gardenoside. In the meantime, the activation of NFκB was inhibited by Gardenoside. Gardenoside has a protective effect on FFA-induced cellular steatosis in HepG2 cells which indicates that Gardenoside might be a potential therapeutic herb against NASH by suppressed supernatant inflammatory cytokine production and intracellular NFkB activity.

N-Heterocyclic carbene (NHC)-catalyzed vinylogous Mukaiyama aldol reaction of ketones was developed. Under the catalysis of 5 mol% NHC, α-keto esters and α-trifluoromethyl ketones reacted with 2-(trimethysilyloxy)furan efficiently to produce γ-substituted butenolides containing adjacent quaternary and tertiary carbon centers in high yields with good diastereoselectivities.

The hydrosilylation of alkenes catalyzed by Fe(CO) 5 is an intricate process involving formation of alkylsilane, vinylsilane, and alkane. Herein, we represent a computational study of this reaction to determine the underlying reaction mechanism using density functional theory (DFT) techniques. On the basis of an extensive exploration of the potential energy surfaces, the modified Chalk–Harrod mechanism was found to be competitive with the Chalk–Harrod mechanism in the stoichiometric reaction of ethylene and trimethylsilane. The source of product selectivity was predicted to be determined by the relative stability of transition state TS(4b–5b) , which is for the ethylene-insertion into Fe Si bond from (H)(Me 3 Si)Fe(CO) 3 (C 2 H 4 ) to (H)(C 2 H 4 SiMe)Fe(CO) 3 , and TS(5a–7a 1 ) for the conversion of ethylene hydrometallation product (Me 3 Si)Fe(CO) 3 (η 2 -H)(C 2 H 4 ) to (C 2 H 5 )(Me 3 Si)Fe(CO) 4 . The relative free energy difference of 3.27 kcal/mol between these two transition states gives a percentage ratio of 79:21 for C 2 H 5 SiMe 3 to C 2 H 4 SiMe 3 , which is qualitatively in agreement with the experimental observations. The largely excessive ethylene favors not only the formation of Fe(CO) 3 (C 2 H 4 )(H)(SiMe 3 ) 4b but also the release of vinylsilane from Fe(CO) 3 (H 2 )(C 2 H 3 SiMe 3 ) or Fe(CO) 4 (C 2 H 3 SiMe 3 ) via the addition of another ethylene molecular to the metal center. Alternatively, in the presence of excessive R 3 SiH, species Fe(CO) 4 (H)(SiR 3 ) will be dominate over Fe(CO) 4 (C 2 H 4 ). In the catalytic process, Fe(CO) 4 (H)(SiR 3 ) plays the main role of active species. The experimental findings were rationalized in terms of two reaction pathways, the accessibility of which depended on the ratio of silane/alkene.

Organized assemblies of noble metal nanoparticles (NPs) exhibit unique optical, electronic and catalytic properties and potential applications in various areas. Many kinds of methods have been developed to fabricate such functional systems. In this work, we report a facile and novel method to fabricate the organized aggregates of Au and Ag NPs. Their freshly prepared hydrosols were used as upper phase, and the DMF/chloroform solutions of different fatty amines were used as bottom phases to form a planar liquid/liquid interface. The mass transfer across the interface occurred immediately, where the DMF droplets containing fatty amines entered into the hydrosols, leading to the formation of organized aggregates of NPs through a self-assembly process of amine molecules. It was found that several kinds of assemblies were generated, including ellipsoidal and spherical superstructures of spherical NPs, networks of spherical NPs and nanorods, and hierarchical structure of nanorods. In addition, networks composed of Au NPs/Ag skeleton satellite-core type nanorods were further constructed, which exhibited good catalytic performance and SERS property.

Halide perovskites have been employed as photocatalysts for CO2 photoreduction due to their excellent optical properties and unique electronic structure. However, their photocatalytic performance is relatively poor. Herein, we demonstrate a new strategy with Mn-doped CsPb(Br/Cl)3 mixed-halide perovskites as catalysts to enhance the efficiency of CO2 photoreduction. By tuning the content of Mn, a series of CsPb(Br/Cl)3:Mn perovskites are obtained and show high efficiency in CO2 conversion to CO and CH4. For the optimum catalyst sample, especially, the yields of CO and CH4 reach 1917 μmol g-1 and 82 μmol g-1 which are 14.2 and 1.4 times higher than those of CsPbBr3. This work provides new insights into improving the reactivity of perovskites in CO2 photoreduction.

This work reports the synthesis of novel cross-linked and functional porous carbon nanosheets (CNSs). The polyvinylpyrrolidone/transition metal acetates/N–N-dimethylformamide precursors are first woven into networks by electrospinning. The resultant precursor networks are transformed into the three-dimensional (3D) hierarchically porous material consisting of cross-linked and meso/macroporous CNSs (i.e., FeCo@NCNS) after pyrolysis. Characterization results prove that abundant ultrafine FeCo@NC units, N–C bonds, metal-nitrogen doped carbon (M-N-C) species and oxygen-containing functional groups disperse along the surfaces of the FeCo@NCNS, which act as electrocatalytic active sites for Oxygen reduction reaction (ORR) and Oxygen evolution reaction (OER). Due to the synergistic effect of the hierarchically porous structures and high-density active sites, the optimal FeCo@NCNS exhibits more positive onset potential (0.98 V relative to a reversible hydrogen electrode (vs. RHE)) and half-wave potential (0.827 V vs. RHE) than Pt/C (0.97 V vs. RHE and 0.819 vs. RHE) for ORR. Meanwhile, the OER potential at 10 mA cm−2 of the FeCo@NCNS (1.597 V vs. RHE) is more negative than RuO2 (1.631). Furthermore, the oxygen electrode activity (ΔE = E10,OER - E1/2,ORR) of the FeCo@NCNS is as low as 0.772 V, which surpasses the state-of-the-art Pt/C(ORR)-RuO2(OER) catalyst combination (ΔE = 0.812 V). Experimental results prove that the FeCo@NCNS is among the best non-precious metal based bifunctional electrocatalyst for ORR and OER.

We report the preparation of protofibrils from oligomeric Aβ40 aggregates, which have been incubated under spatially constrained conditions. The molecular structure of the resultant protofibrils is highly homogeneous, suggesting that the phenomenon of structural polymorphism commonly observed in Aβ40 fibrils may be largely due to multiple nucleation events.

Advanced core-shelled material with a high specific area has been considered as an effective material to remove heavy metal from aqueous solutions. A core-shelled Fe3O4@C hybrid nanoparticle aggregates with environmental-friendly channel in the study. Moreover, the higher exposure of adsorption sites can be achieved for the special configuration that higher Brunauer-Emmet-Teller (BET) surface area reaches up to 238.18 m2 g−1. Thus, a more efficiently heavy metal ion removal is obtained, Pb (II), Cd (II), Cu (II), and Cr (VI) up to 100, 99.2, 96.6, and 94.8%, respectively. In addition, the products are easy to be separated from the aqueous solutions after adsorption, due to the relative large submicrometer size and the enhanced external magnetic fields introduced by the iron-based cores. We provide an ideal mode to remove heavy metal ions using core-shelled Fe3O4@C under the water treatment condition. A new approach is clarified that core-shell nano/micro-functional materials can be synthesized well on large scales which are used in many fields such as environmental remediation, catalyst, and energy.

Ubiquitin-like (UBL) protein modifications play a key role in regulating protein function. In contrast to the ubiquitin (UB) and small ubiquitin-like modifier (SUMO) which are ligated to a massive segment of proteome, the UBL NEDD8 is highly selective for modifying a lysine residue on closely related cullin proteins (CULs). In this study, the X-ray structure of a trapped E3-E2∼NEDD8-target intermediate (RBX1-UBC1∼NEDD8-CUL1-DCN1) is used to build computer models, and combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) and free energy (potential of mean force) simulations are performed to investigate the catalytic mechanism of the NEDD8 transfer from E2 to the lysine residue (K720) on the substrate in the complex. The role of the active site residues is examined. The simulation results show that either E117 or D143 from E2 may be able to work as a general base catalyst to deprotonate K720 on the substrate, and K720 can then perform the nucleophilic attack on the thioester bond linking E2 and NEDD8. It is also shown that the formation of a new isopeptide bond between K720 and NEDD8 and the breaking of the thioester bond are concerted based on the computer simulations. Furthermore, the results suggest that K720 may act as a general acid catalyst to protonate the leaving group of C111 from E2. The free energy barrier for nucleophilic attack is estimated to be 14-15 kcal/mol based on the free energy simulations.