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Developing effective and practical electrocatalyst under industrial electrolysis conditions is critical for renewable hydrogen production. Herein, we report the self-supporting NiFe LDH-MoSx integrated electrode for water oxidation under normal alkaline test condition (1 M KOH at 25 °C) and simulated industrial electrolysis conditions (5 M KOH at 65 °C). Such optimized electrode exhibits excellent oxygen evolution reaction (OER) performance with overpotential of 195 and 290 mV at current density of 100 and 400 mA·cm−2 under normal alkaline test condition. Notably, only overpotential of 156 and 201 mV were required to achieve the current density of 100 and 400 mA·cm−2 under simulated industrial electrolysis conditions. No significant degradations were observed after long-term durability tests for both conditions. When using in two-electrode system, the operational voltages of 1.44 and 1.72 V were required to achieve a current density of 10 and 100 mA·cm−2 for the overall water splitting test (NiFe LDH-MoSx/INF || 20% Pt/C). Additionally, the operational voltage of employing NiFe LDH-MoSx/INF as both cathode and anode merely require 1.52 V at 50 mA·cm−2 at simulated industrial electrolysis conditions. Notably, a membrane electrode assembly (MEA) for anion exchange membrane water electrolysis (AEMWEs) using NiFe LDH-MoSx/INF as an anode catalyst exhibited an energy conversion efficiency of 71.8% at current density of 400 mA·cm−2 in 1 M KOH at 60 °C. Further experimental results reveal that sulfurized substrate not only improved the conductivity of NiFe LDH, but also regulated its electronic configurations and atomic composition, leading to the excellent activity. The easy-obtained and cost-effective integrated electrodes are expected to meet the large-scale application of industrial water electrolysis.

Aerospace aircraft has significantly improved the life quality of human beings and extended the capability of space explosion since its appearance in 1903, in which liquid propellants or fuels provide the key power source. For jet fuels, its property of energy density plays an important role in determining the flight range, load, and performance of the aircraft. Therefore, the design and fabrication of high-energy-density (HED) fuels attract more and more attention from researchers all over the world. Herein, we briefly introduce the development of liquid jet fuels and HED fuels and demonstrate the future development of HED fuels. To further improve the energy density of fuel, the approaches of design and construction of multi-cyclic and stained molecule structures are proposed. To break through the density limit of hydrocarbon fuels, the addition of energetic nanoparticles in HED fuels to produce nanofluid or gelled fuels may provide a facile and effective method to significantly increase the energy density. This work provides the perspective for the development of HED fuels for advanced aircrafts.

Carbon nitride (C3N4) is promising for photocatalytic hydrogen production, but photogenerated electrons and holes in C3N4 usually tend to exist as excitons due to intrinsic Coulomb interactions making its photocatalytic activity unsatisfactory. Herein, a well-designed intramolecular C3N4-based donor-acceptor (D-A) photocatalytic system was constructed to promote exciton dissociation. Due to its good chemical compatibility with melamine and appropriate sublimation property, 2-amino-4,6-dichloropyrimidine unit was chosen as the monomer to react with melamine to construct intramolecular D-A system (CNClx). The hydrogen evolution rate of CNCl0.15 is 15.3 times higher than that of bulk C3N4 under visible light irradiation, with apparent quantum efficiency of 13.6% at 420 nm. The enhanced activity is attributed to introduced electron-withdrawing −Cl group as terminal group in the resulted CNClx samples, which can build internal electric field to promote the exciton dissociation into free electron and hole. In addition, lower work function value of CNClx samples indicates that internal electric field can help free electrons and holes transfer to the surface of CNClx samples for photocatalytic reaction.

Cypripedium subtropicum is the only known winter-green species in the genus Cypripedium, whereas the other nearly 50 species keep their leaves for less than half the year. Life form has an important effect on carbon acquisition and adaptation of plants. However, the physiological mechanism behind it remains unclear. In this study, we investigated vegetative anatomy and photosynthetic performance of C. subtropicum across with its leaf ages. These anatomical and photosynthetic traits were also compared with typical Cypripedium spp. and other members of subfamily Cypripedioideae. The obtained results confirmed that this species exhibited many characters of shade plants, such as thin leaves, extremely low photosynthetic rate and light saturation point and high chlorophyll content. Unlike the strategy adopted by typical Cypripedium spp. that quickly achieve annual carbon gain with a high assimilation rate in a short growing season, C. subtropicum obtains its carbon through a low assimilation rate but a much longer leaf lifespan. The local climate and favourable light condition guaranteed the comparable carbon income in winter to compensate for its low photosynthetic capacity. The long-lived, thin leaves of C. subtropicum, differing from the long-lived, thick leathery leaves in conduplicate-leaved genera, represent a distinct adaptive strategy in subfamily Cypripedioideae. Our findings shed light on the divergent and convergent evolution in slipper orchids, and we hope these findings will contribute to the conservation of such an endangered orchid.

Platinum is the archetypal electrocatalyst for oxygen reduction—a key reaction in fuel cells and zinc–air batteries. Although dispersing platinum as single atoms on a support is a promising way to minimize the amount required, catalytic activity and selectivity are often low due to unfavourable O2 adsorption. Here we load platinum onto α-Fe2O3 to construct a highly active and stable catalyst with dispersed Pt–Fe pair sites. We propose that the Pt–Fe pair sites have partially occupied orbitals driven by strong electronic coupling, and can cooperatively adsorb O2 and dissociate the O=O bond, whereas OH* can desorb from the platinum site. In alkaline conditions, the catalyst exhibits onset and half-wave potentials of 1.15 V and 1.05 V (versus the reversible hydrogen electrode), respectively, mass activity of 14.9 A mg−1Pt (at 0.95 V) and negligible activity decay after 50,000 cycles. It also shows better performance than 20% Pt/C in a zinc–air battery and H2–O2 fuel cell in terms of specific energy density and platinum utilization efficiency. Atomically dispersed platinum electrocatalysts for oxygen reduction promise minimized platinum usage, but catalytic activity and selectivity are often low due to unfavourable O2 adsorption. To circumvent this issue, Gao and colleagues load platinum onto α-Fe2O3, making a highly active and stable catalyst with dispersed Pt–Fe pair sites.

The synthesis of dibenzofurans and bicycloalkanes from biomass is important for sustainable high-value chemicals and high-density fuels. Currently, their biomass-based precursor is mainly derived from lignin with limited yields. Herein, we propose a cellulose-based synthesis route for dibenzofurans with a yield of 72.3% via the integration of oxidative coupling of 1,2,4-benzenetriol to diphenol combined with subsequent dehydration under environmentally friendly reaction conditions. After hydrodeoxygenation, bicycloalkanes are obtained with a yield of 70.5% by catalysis performed over Pd/C and various zeolites. This work provides a powerful cellulose-based strategy for the synthesis of dibenzofurans and bicycloalkanes, which was previously unattainable in the conventional lignin-based route.

Fuel blending generally exhibits better low-temperature flow properties (i.e. low viscosity, low freezing point) than pure component fuel. Here, a fuel bending containing bicyclohexane and (cyclopentylmethyl)cyclohexane was synthesized directly by hydroisomerization of cyclohexylphenol to reduce the freezing point. The selectivity of (cyclopentylmethyl)cyclohexane formed by isomerization is enhanced through inhibiting the quick hydrogenation of intermediates using mixing acid catalyst and metal catalyst. Zeolite with strong Bronsted acid site and big surface area, such as HZSM-5 is better for the isomerization. Catalyzed by mixture of Pd/C and HZSM-5, the obtained fuel blending improves the freezing point from 2.6 °C to−22 °C compared with pure bicyclohexane, meanwhile keep the high density of 0.880 g/mL unchanged. The improved low-temperature property is contributed to the formation of (cyclopentylmethyl)cyclohexane. Moreover, the pathways of isomerization and its competition with hydrodeoxygenation are also investigated.

The photocatalysis is a very promising technique to address the serious issues of environmental pollution. Among the common photocatalysts, the graphitic carbon nitride (g-C3N4) is widely used for the photodegradation of organic pollutants due to its proper band structure. To further improve the photocatalytic performance of g-C3N4, a novel composite photocatalyst of Co3O4/PT-C3N4 has been prepared by using a one-pot calcination method, in which cobalt tetroxide (Co3O4) nanoparticles as the cocatalyst are introduced on the surface of rectangular hollow g-C3N4 substrate (PT-Co3O4). As a result, the obtained composite photocatalyst (Co3O4/PT-C3N4) delivers an excellent photodegradation performance for diesel oil under a simulated sunlight, which can improve the separation efficiency of the photo-induced electron–hole pairs. The Co3O4/PT-C3N4 composite photocatalyst exhibits a high degradation efficiency of 96.27% after 2 h of visible light, which is much higher than that of the PT-C3N4 photocatalyst. Moreover, the composite photocatalyst can still maintain a high photodegradation efficiency after 10 cycles, exhibiting an excellent cyclic stability. The photo-induced carriers generated by the Co3O4/PT-C3N4 composite photocatalyst follow the Z-scheme heterojunction transfer mechanism. This work gives a fresh idea for the exploration of new high-performance photocatalyst for the treatment of organic environmental pollutants.

Tsaokols A (1) and B (2), two complicated flavanol-monoterpenoid hybrids, were isolated from the dried fruits of Amomum tsao-ko under the guidance of LCMS and bioassay. Their structures were determined by extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 shared a flavanol backbone fused with 5/7 and 5/6 bicyclic monoterpenoid scaffolds, which were biogenetically condensed by Michael addition and acetalization. Compounds 1 and 2 exhibited significant α-glucosidase inhibitory activity with IC50 values of 18.8 and 38.6 μmol/L (acarbose, IC50 = 213 μmol/L). Docking study supported the strong interactions of 1 and 2 bonding with enzyme by mainly hydrophobic and hydrogen-bond effects. Compounds 1 and 2 could be fast distinguished by the diagnostic ions at m/z 289 and 313 in negative MS2 experiments.

Sericin, a silk protein, has a high potential for use as an extracellular matrix in tissue engineering applications. In this study, novel gelatin (GEL) and silk sericin (SS) were incorporated with a polyvinyl alcohol) PVA hydrogel nanocomposite (GEL-SS-PVA) scaffold that can be applied to repair cartilage. Glutaraldehyde was used as a cross-linking agent, with hydrochloric acid acting as an initiator. The microstructure characteristics of the obtained GEL-SS and GEL-SS-PVA scaffolds were also examined using FTIR and XRD spectra and their enhanced thermal stability was assessed by TGA. The blended GEL-SS and GEL-SS-PVA scaffolds were confirmed by SEM analysis to be highly porous with optimum pore sizes of 172 and 58 µm, respectively. Smaller pore sizes and improved uniformity were observed as the concentration of PVA in the GEL-SS-PVA scaffold increased. PVA decreased the tensile strength and elongation of the membranes but increased the modulus. Swelling studies showed high swellability and complete degradation in the presence of phosphate-buffered saline. Cytocompatibility of the GEL-SS-PVA scaffolds showed that these had the highest potential to promote cell proliferation as evaluated with standard microscopy using L929 fibroblasts. The prepared GEL-SS composite scaffold incorporated with the PVA hydrogel was implanted in full-thickness articular cartilage defects in rats. The repair effect of cartilage defects was observed and evaluated among the GEL-SS-PVA, GEL-SS, and control operation groups. The defects were almost completely repaired after 14 weeks in the GEL-SS-PVA group, thereby indicating that the GEL-SS-PVA composite had a favorable effect on articular cartilage defects in rat knee joint repair.

In order to reveal the correlation effect on the electronic properties in particular 5f electron occupation numbers of Pu/U ions in a (Pu,U) mixed oxide-PuUO4, a first principles calculation is performed by using density functional theory (DFT) plus a dynamical mean field theory (DMFT) scheme with the spin-orbit coupling (SOC) and on-site Coulomb repulsion for correlation effect due to localized Pu/U 5f orbitals. Results demonstrate that Pu/U 5f electron occupation numbers in the ground state of PuUO4 are mainly composed of 5f4/5f5 and 5f2/5f3 configurations, and exhibiting the intermediate occupation (IO) numbers with average 5f occupation numbers of about nf = 4.879 and 2.423 for Pu and U ions, respectively, irrespective of different Pu and U lattice sites in PuUO4. Pu 5f j = 5/2 and j = 7/2 components are in moderately and weakly correlated states, respectively, while U 5f j = 5/2 and j = 7/2 manifolds are both in weakly correlated states. jj and LS coupling schemes are feasible for Pu and U 5f electrons, respectively. In order to directly compare with the experimental angle-resolved photoemission spectrum (ARPES), we also estimate the momentum-resolved electronic spectrum function for this system.

Two sesquiterpenoid trimers, artematrotrimers A (1) and B (2), and two sesquiterpenoid dimers, artematrodimers A (3) and B (4), possessing unprecedented scaffolds with a methylene-bridged connection were identified from Artemisia atrovirens. Their structures and absolute stereochemistry were determined by comprehensive spectroscopic data, single-crystal X-ray diffraction analyses, and ECD calculations. Compounds 1–4 represent a new type of sesquiterpenoid oligomers featuring the connections between hetero sesquiterpenoid units via one or two C–C bonds. A possible biosynthetic pathway for 1–4 was also proposed. Compound 3 showed obvious cytotoxicity against HepG2 and Huh7 cell lines with IC50 values of 21.9 and 22.6 μM, respectively.

Detecting traffic signs is an essential task for intelligent and connected vehicles. In this study, a modified model based on the method of You Only Look Once (YOLO) is proposed for detecting different types of Chinese signs, including mandatory, prohibitory, danger warning, guide, and tourist signs. Images of Chinese traffic signs are collected in real scenes and a new dataset is established. The modified model combines the DenseNet method with the YOLOv3 network. Dense blocks are used to strengthen feature propagation and promote feature reuse in those feature layers with low resolution in the YOLOv3 network. Experimental results on the test dataset reveal that the average precision of the modified model, the original YOLOv3, and the YOLOv2 networks are 95.92, 94.59, and 89.39%, respectively. Further comparative analyses that give more detailed experimental evaluation results are conducted on the designed model, including (i) the performance of the designed model based on five categories; (ii) the influence of training set size on the designed model; (iii) the performance of the designed model on occlusion and no object conditions in real scenes. The experimental results show that the modified model is effective at fast and accurate Chinese traffic sign detection in real scenes.

Spinel-type manganese-cobalt oxides have been regarded as important class of electrocatalysts for oxygen reduction reaction (ORR). However, they are usually synthesized through oxidation-precipitation under aqueous ammonia and then crystallization at high temperature (150–180 °C), which not only increases the energy consumption but also induces the growth of particles that is unfavorable for ORR. Herein, through a facile precipitation-dehydration method, ultrasmall spinel manganese-cobalt oxide nanoparticles (~5 nm) homogeneously dispersed on conductive carbon black (MnxCo3-xO4/C) were fabricated at low temperature (60 °C). And the bimetallic composite oxide (Mn1.5Co1.5O4/C) with cubic spinel structure and high Mn content exhibits remarkable enhancement of ORR activity and stability compared with single metal oxide (both Mn3O4/C and Co3O4/C). The essential reason for the enhancement of activity can be attributed to the presence of the mixed Mn3+ and Mn4+ cations in Mn1.5Co1.5O4/C. Moreover, the ORR activity of Mn1.5Co1.5O4/C is comparable to that of commercial 20 wt% Pt/C, and the relative current density only decreases 1.4% after 12 h test, exceeding that of Pt/C and most reported manganese-cobalt oxide electrocatalysts.

Developing effective, stable, and economical electrocatalysts to achieve highly efficient overall water splitting under a large current density in industries is critical for renewable H2 production...

The development of enantioconvergent cross-coupling of racemic alkyl halides directly with heteroarene C(sp2 )-H bonds has been impeded by the use of a base at elevated temperature that leads to racemization. We herein report a copper(I)/cinchona-alkaloid-derived N,N,P-ligand catalytic system that enables oxidative addition with racemic alkyl bromides under mild conditions. Thus, coupling with azole C(sp2 )-H bonds has been achieved in high enantioselectivity, affording a number of potentially useful α-chiral alkylated azoles, such as 1,3,4-oxadiazoles, oxazoles, and benzo[d]oxazoles as well as 1,3,4-triazoles, for drug discovery. Mechanistic experiments indicated facile deprotonation of an azole C(sp2 )-H bond and the involvement of alkyl radical species under the reaction conditions.

In this study, a new Cd(II)-bearing coordination polymer with the chemical formula of {[Cd4(meda)3(dpe)4(H2O)4]·(NO3)2·2(H2O)}n (1, H2meda = 3,3′-methylenedibenzoic acid, dpe = 1,2-di(pyridin-4-yl)ethane) has been successfully prepared by reaction of Cd(NO3)·4H2O with a V-shape carboxyl ligand H2meda along with the linear dipyridine ligand dpe under the hydrothermal conditions. Due to its intensive luminescence, complex 1 could be utilized as the sensor of detecting Al3+ ion, and its detection limit is 4 × 10−6 M. Firstly, the toxicity of the compound on the normal liver cells was determined with Cell Counting Kit-8 detection kit. The triglyceride in liver cells was detected by detection kit after compound treatment and the relative expression of 15-lox and 12-lox in L02 cells was also measured by RT-PCR after compound treatment. In addition, multiple functional groups that provided by the synthesized Cd(II) complex have been studied by using molecular docking simulation for the confirmation of possible binding modes that formed between ligand and receptor.

Photocatalysis via direct solar-to-chemical energy conversion is an intriguing approach for alleviating the pressure of high energy consumption caused by social development. However, photocatalytic efficiency is greatly restricted by unsatisfactory light-harvesting capacity, high carrier recombination rates, and sluggish reaction kinetics. Indeed, vacancy engineering is an attractive strategy to regulate photocatalytic reaction performance to maximize the utilization and storage of solar energy. In this review, we summarize recent progress about the important roles of vacancy defects on solar-driven photocatalytic applications. The current advanced characterization techniques, especially for in situ/operando techniques, are first presented for elucidating the structure-performance relationships of defective semiconductors in photocatalysis. Subsequently, the crucial roles of vacancies in enhancing photocatalytic performance are highlighted from three important processes: light absorption, carrier separation and migration, and surface reaction. Finally, based on the above understanding, perspectives and opportunities about defective materials are considered for various photocatalytic applications.

Firstly, a novel pyrazole-pyrazoline fluorescent probe was developed and synthesized. The probe can be used to determine Fe3+ ions in a series of cations in tetrahydrofuran aqueous solution with high selectivity and high sensitivity. After the addition of iron ions, the fluorescence intensity is significantly reduced, Its structure was characterized by 1H NMR, 13C NMR and HR-ESI-MS. UV absorption spectra and Fluorescence spectroscopy were used to study the selective recognition of probe M on metal ions. The probe M can selectivity and sensitivity to distinguish the target ion from other ions through different fluorescence phenomena. In addition, the binding modes of M with Fe3+ were proved to be 1:1 stoichiometry in the complexes by Job’s plot, IR results. The combination of probe M and iron ions is 1:1, and the detection limit is 3.9 × 10−10 M. The binding mode and sensing mechanism of M with Fe3+ was verified by theoretical calculations using Gaussian 09 based on B3LYP/6-31G(d) basis.

A new class of chiral cyclopentadienyl rhodium(I) complexes (CpRhI ) bearing C2 -symmetric chiral bridged-ring-fused Cp ligands was prepared. The complexes were successfully applied to the asymmetric C-H activation reaction of N-methoxybenzamides with quinones, affording a series of chiral hydrophenanthridinones in up to 82 % yield with up to 99 % ee. Interestingly, structure analysis reveals that the side wall of the optimal chiral CpRhI catalyst is vertically more extended, horizontally less extended, and closer to the metal center in comparison with the classic binaphthyl and spirobiindanyl CpRhI complexes, and may thus account for its superior catalytic performance.

A new class of C2 -symmetric, chiral cyclopentadienyl ligand based on planar chiral ferrocene backbone was developed. A series of its corresponding rhodium(I), iridium(I), and ruthenium(II) complexes were prepared as well. In addition, the rhodium(I) complexes were evaluated in the asymmetric catalytic intramolecular amidoarylation of olefin-tethered benzamides via C-H activation.

A flexible-robust copper(II) metal-organic framework, denoted as LIFM-100, has been successfully synthesized using a fluorinated linear dicarboxylate to link copper ions. LIFM-100 exhibits a breathing effect, which can transform reversibly between a large form (lp) and a narrow form (np) from single crystal to single crystal. In addition, LIFM-100 shows good thermal and chemical stability. By the introduction of trifluoromethyl functional groups and uncoordinated carboxyl acids, LIFM-100 features a good CO2/R22 adsorption/separation performance at 298 K, showing potential in natural gas purification and CO2/R22 capture.

Photocatalytic heterogeneous organic transformation is considered as an efficient, clean atomic economy and low energy consumption strategy for organic synthesis. Conjugated polymers (CPs)-based ma...

Compounds containing 4H-1,3-benzo-xazine core usually possess characteristic features and have been applied in the fields of organic synthesis, pharmaceutical research, materials science and bioscience. Here we reported convenient and direct access to 4H-1,3- benzo-xazines and their derivatives through intramolecular cyclization of olefinic amides or ureas with good to excellent yields in the presence of TMSOTf. The properties (mild conditions, metal or additives-free, wide substrate scope and functional group tolerance) of the process made it a promising strategy to synthesize various benzo-xazines and their derivatives.

Thermal oxidation stability is an important parameter for jet fuel practical application. In this work, in order to evaluate the influence of deoxygenation on fuel stability, samples of typical fuels (JP-10 and RP-3) were subjected to deoxygenation by nitrogen purge and then subjected to accelerated thermal oxidation (180°C, 200°C, and 220°C). The parameters of hydroperoxide number, total acid number, size distribution of insoluble oxidation products, and concentration of remaining antioxidant (butylated hydroxytoluene, MIT) were monitored and analyzed. The results show that deoxygenation and thermal oxidation have very little influence on the fuel physical properties (density, net heating value, and kinematic viscosity). However, deoxygenation significantly reduces hydroperoxide number, total acid number, and remaining BHT concentration in the fuel after accelerated oxidation. Moreover, the deoxygenation treatment also inhibits the formation of soluble macromolecular oxidatively reactive species (SMORS) and insoluble oxidation products such as gums and deposits.

Random screening suggested that the EtOH extract of Artemisia myriantha (Asteraceae) and its EtOAc fraction had cytotoxicity against HepG2 cells with inhibitory ratios of 30.6% and 53.5% at 50.0 μg/mL. Bioassay-guided isolation of the most active fractions (Fr. C and Fr. D) afforded 19 new sesquiterpenolides, artemyrianolides A-S (1-19), involving 13 germacranolides (1-13), four guaianolides (14-17), and two eudesmanolides (18 and 19), together with 16 known sesquiterpenoids (20-35). The new compounds were characterized by physical data analyses (HRESIMS, IR, 1D and 2D NMR, ECD), and the absolute configurations of compounds 1, 2, and 11 were determined by X-ray crystallography. Structurally, compounds 2 and 11-13 maintain an uncommon cis-fused 10/5 bicyclic system and compound 12 possesses an unusual (7S) configuration. Twenty of the compounds exhibited cytotoxicity against HepG2, Huh7, and SMMC-7721 cell lines. Compound 9 showed cytotoxic activity on both HepG2 and Huh7 cells with IC50 values of 8.6 and 8.8 μM, and compounds 8 and 33 showed cytotoxicity to the three human hepatoma cell lines with IC50 values of 4.9 and 7.4 μM (HepG2), 4.3 and 7.8 μM (Huh7), and 3.1 and 9.8 μM (SMMC-7721), respectively.

Known for excellent stability, porosity and functionality, the high-valent Zr4+ metal-organic frameworks (Zr-MOFs) still meets synthetic challenge in modulating the strength of Zr-Ocarboxylate linkage. Herein we explore the unusual coordination dynamics of fluorinated Zr-MOFs by designing two trifluoromethyl modified ligands with distinct geometry preference to form a family of thermodynamic and kinetic products. The low-connecting kinetic Zr-MOFs possess substitutable coordination sites to endow Zr6 -cluster with extra dynamic behaviors, thus opening a post-synthetic pathway to sequential reassembly/disassembly processes. Comprehensive factors, including ligand geometry, Zr6 -cluster connectivity, acid modulator and reaction temperature/concentration, have been studied for controllable syntheses. The stability, hydrophobicity and gas adsorption/separation properties of obtained Zr-MOFs are explored. This work sheds light on the understanding of the dynamic coordination chemistry of Zr-MOFs beyond strong Zr-O bond, which poses a versatile platform for modification and functionalization of Zr-MOFs.

Upgrading furanic aldehydes (such as furfural or 5-hydroxymethyl furfural) to cyclopentanone compounds (such as cyclopentanone or 3-hydroxymethyl cyclopentanone) is of great significance for the sy...

Ni-based alloys are considered as the efficient catalyst for hydrogen-storage materials decomposition. Herein, we applied an in-situ melt-quenching method to dope Mo in Ni-based alloy for catalytic hydrogen evolution from hydrogen-storage materials. Importantly, Mo doped Ni-based catalyst exhibits more than 6 times higher TOF value than that of pure Ni both in AB hydrolysis and hydrazine decomposition, because Mo acts as an electron donor to improve the reducibility of Ni. Hydrogen evolution kinetics were studied over a range of temperatures (303–353 K) and initial feed concentrations (catalyst/hydrogen-storage materials (wt/wt) ratios = 0.2–10). Under optimal reaction conditions, the H2 evolution rate reaches 1.92 mol H2/(molcat min) and 0.05 mol H2/(molcat min) in the hydrolysis of ammonia borane and decomposition of hydrazine, which are 6.42 and 6.44 times higher than undoped Ni catalyst, respectively. And the apparent activation energy of ammonia borane hydrolysis and hydrazine decomposition were evaluated to be 26.66 ± 3.31 kJ/mol and 40.01 ± 3.38 kJ/mol, respectively.

Abstract Two new sesquiterpenoids, artemlavanins A (1) and B (3), together with fifteen known compounds (2 and 4−17) were isolated from the EtOH extract of Artemisia lavandulaefolia. The structures of new compounds were elucidated by extensive spectroscopic analyses (HRESIMS, 1D and 2D NMR) and ECD calculations. Compound 1 was a sesquiterpenoid lactone possessing a rearranged eudesmane skeleton; compounds 2–5, 6–8, 9 and 10–12 belonged to the eudesmane, guaiane, oppositane and farnesane sesquiterpenoids, respectively; compounds 13–17 were the phenyl derivatives with a 4-hydroxyacetophenone moiety. Twelve compounds (1–3, 5–7, 10–12, 14, 15 and 17) displayed cytotoxicity against hepatic stellate cell line LX2 (HSC-LX2) with IC50 values ranging from 35.1 to 370.3 μM. Compounds 2, 7, 10–12 and 17 exhibited the stronger cytotoxicity than silybin (IC50, 169.6 μM) with IC50 values of 82.1, 35.1, 95.0, 83.8, 81.6 and 90.1 μM. Compound 7 as the most active one showed significant inhibition on the deposition of human collagen type I (Col I), human hyaluronic acid (HA) and human laminin (HL) with IC50 values of 10.7, 24.5 and 13.3 μM. Graphic Abstract

In Orchidaceae, pollination is mostly animal-mediated, and one-third of species have evolved a deceptive pollination mechanism without rewards. Cypripedium is a representative lineage of nonrewarding orchids restricted to temperate regions. Cypripedium subtropicum flowers are pollinated by hoverflies and have hairy tufts that visually resemble an aphid colony covered with honey dew. We recorded the behavior of hoverflies on the flowers, determined the breeding system of the species and the structure of hairy tufts, and investigated the roles of hairy tufts and floral volatiles in this specialized pollination by using pollination experiments, scanning electron microscopy, bioassays and chemical analyses. The white hairy tufts covering the sidelobes of the labellum provide edible rewards and serve as crucial visual lures for hoverflies. The flowers emit primarily (E)-β-farnesene and a smaller amount of β-pinene that were found to attract hoverflies. Our results suggest that C. subtropicum uses both visual mimicry of an aphid-colonized labellum with a reward and chemical mimicry of aphid alarm pheromones to attract hoverflies for pollination. This is the first described example of a rewarding mimicry system in plants, where the models are animals with their secretions and the reward is similar in nutrients to that of the model mimicked.

Developing sulfonic-acid-supported catalysts with superacidity and hydrophobicity is of great importance for many acid-catalyzed reactions where H2O is generated. Herein, a novel hydrophobic supera...

International audience; Calix[4]arenes have the ability to encapsulate biomimetic guests, offering interesting opportunities to explore their molecular recognition, very close to biological scenarios. In this study, p-sulfonatocalix[4]arene (C4 A) anions and hydrated alkali cations have been used for the in situ recognition of cationic 1,ω-diammonium-alkanes and 1,ω-amino-acids of variable lengths. NMR spectroscopy illustrates that these systems are stable in aqueous solution and the interaction process involves several binding states or stabilized conformations within the C4 A anion, depending of the nature of the guest. DOSY experiments showed that monomeric 1 : 1 host-guest species are present, while the cation does not influence their selfassembly in solution. The folded conformations observed in the solid-state X-ray single-crystal structures shed light on the constitutional adaptivity of flexible chains to environmental factors. Futhermore, a comprehensive screening of 30 single crystal structures helped to understand the in situ conformational fixation and accurate determination of the folded structures of the confined guest molecules, with a compression up to 40 % compared with their linear conformations.

A chiral CpRhIII-catalyzed asymmetric C–H activation reaction of N-methoxybenzamides with quinones has been developed to efficiently forge chiral tricyclic hydrophenanthridinone scaffolds in ≤88% y...

A C2-symmetric chiral spirocyclic diol aza-SPINOL containing a spirooxindole scaffold has been designed, synthesized, and optically resolved. The product could be synthesized on gram scale in an ov...

In this study, we consider the singular Sturm-Liouville (S-L) problem with transmission conditions (TC). The eigenvalues of the singular S-L problem with TC are investigated. By defining a new Hilbert space which is related to TC, the self-adjointness of the S-L problem in this associated Hilbert space is proved. And we give the condition for $$\lambda $$ being the eigenvalue of the singular S-L problem. Furthermore, the asymptotic behavior of eigenvalues of the singular S-L problem is described.

Abstract Uncariae Ramulus Cum Uncis (Gou-Teng), the dried hook-bearing stems of several Uncaria plants (Rubiaceae), is a well-known herbal medicine in China. The clinical application of Gou-Teng is bewildered for the morphological and chemical similarity between different species. In order to discern their chemical and biological difference, an ultra-fast liquid chromatography equipped with ion trap time-of-flight mass spectrometry (UFLC-IT/TOF-MS) combining with melatonin (MT1 and MT2) and 5-hydroxytryptamine (5-HT1A and 5-HT2C) receptors agonistic assay in vitro was conducted on seven Uncaria species. As a result, 57 compounds including 35 indole alkaloids, ten flavonoids, five triterpenoids, five chlorogenic analogues, and two other compounds were characterized based on their MS/MS patterns and UV absorptions. Specifically, cadambine-type and corynanthein-type alkaloids were exclusively present in U.rhynchophylla and U.scandens, whereas corynoxine-type alkaloids were commonly detected in all the seven Uncaria plants. Three Uncaria species, U. rhynchophylla, U. macrophylla, and U. yunnanensis showed obviously agnostic activity on four neurotransmitter receptors (MT1, MT2, 5-HT1A, and 5-HT2C). This first-time UFLCMS-IT-TOF analyses integrated with biological assay on seven Uncaria plants will provide scientific viewpoints for the clinical application of Gou-Teng. Graphic Abstract

Rationally constructing hetero-structures of iron species for efficient oxygen reduction reaction (ORR) remains challenging. Herein, an efficient and robust strategy has been developed for building and tailoring FeOx/Fe hetero-structures. By tuning the temperature of H2 treatment, highly dispersed FeOx/Fe hetero-structures with controllable composition and multiple exposed crystal planes have been obtained to increase the electro-conductivity and hydrophilicity for efficient ORR. The resulting as-prepared Fe2O3@NC-450 exhibited remarkable ORR activity with an Eonset value of 1.001 V, E1/2 of 0.838 V and limited current density of 6.71 mA cm−2, which are superior to those of commercial 20 wt% Pt/C (Eonset = 0.994 V, E1/2 = 0.828 V, 5.19 mA cm−2). Moreover, Fe2O3@NC-450 provided a high power density of 156.6 mW cm−2, which is 2.3 times that of 20 wt% Pt/C (68 mW cm−2) in a zinc–air battery test. In addition, Fe2O3@NC-450 had a discharge time of 29 h, which is longer than that of 20 wt% Pt/C (23.5 h). This work provides an alternative efficient way to rationally construct hetero-structures of metal oxides and metal for next-generation ORR catalysts and metal–air batteries.

This paper deals with a class of inverse spectral problems of fourth-order boundary value problems with eigenparameter-dependent boundary conditions. Under the equivalent conditions of the problem and a certain type of matrix eigenvalue problem some coefficient functions are reconstructed from the given three sets of interlacing real numbers and several additional conditions. The key technique is the method of inverse matrix eigenvalue problems of a two-banded matrix.

Photocatalysis has been regarded as a promising strategy for hydrogen production and high-value-added chemicals synthesis, in which the activity of photocatalyst depends significantly on their electronic structures, however the effect of electron spin polarization has been rarely considered. Here we report a controllable method to manipulate its electron spin polarization by tuning the concentration of Ti vacancies. The characterizations confirm the emergence of spatial spin polarization among Ti-defected TiO2, which promotes the efficiency of charge separation and surface reaction via the parallel alignment of electron spin orientation. Specifically, Ti0.936O2, possessing intensive spin polarization, performs 20-fold increased photocatalytic hydrogen evolution and 8-fold increased phenol photodegradation rates, compared with stoichiometric TiO2. Notably, we further observed the positive effect of external magnetic fields on photocatalytic activity of spin-polarized TiO2, attributed to the enhanced electron-spin parallel alignment. This work may create the opportunity for tailoring the spin-dependent electronic structures in metal oxides., Photocatalyst activity depends significantly on the material’s electronic structures. Here, authors manipulate the electron spin polarization of TiO2 by tuning the concentration of Ti vacancies and show improved photocatalytic activities.

The shortage of water resources and increasingly serious water pollution have driven the development of high-efficiency water treatment technology. Among a variety of technologies, adsorption is widely used in environmental remediation. As a class of typical adsorbents, metal oxides have been developed for a long time and continued to attract widespread attention, since they have unique physicochemical properties, including abundant surface active sites, high chemical stability, and adjustable shape and size. In this review, the basic principles of the adsorption process will be first elucidated, including affecting factors, evaluation index, adsorption mechanisms, and common kinetic and isotherm models. Then, the adsorption properties of several typical metal oxides, and key parameters affecting the adsorption performance such as particle/pore size, morphology, functionalization and modification, supports and calcination temperature will be discussed, as well as their application in the removal of various inorganic and organic contaminants. In addition, desorption and recycling of the spent adsorbent are summarized. Finally, the future development of metal oxide based adsorbents is also discussed.

In past two decades, we have witnessed significant improvements in theoretical and experimental investigation for metallic Pu, its compounds and alloys, in particular self-irradiation induced aging mechanism, electronic structure, and surface corrosion, however, huge challenges still exist for the phase stability of these Pu-based systems which are sensitive to external factors such as temperature, pressure and chemical doping. In this work we have reviewed the recent progress on the multi-scale characterization for the electronic, structural and magnetic properties related to the phase stability of Pu-based systems, in particular Pu-Ga alloy, such as the phase stability induced aging mechanism, phase diagram, phase transformation, double C curve kinetics of time–temperature-transformation (TTT) diagram for δ → α′ martensitic transformation, and thermodynamical calculation. Finally, future directions on the phase stability of these Pu-based systems are also discussed.

Carbon nanotube (CNT)-supported Ni-modified MoS2 catalysts with ultra-high loading were synthesized with the assistance of citric acid. The morphology of the nanoflake arrays could be controlled to give abundant stepped sites, which favored the hydrogenation desulfurization pathway of dibenzothiophene. The catalyst exhibited excellent performance and stability for hydrodesulfurization of model oil and coal-to-liquid fuel.

Fluorescence imaging is a target-specific molecular imaging technology using absorption coefficient of fluorophore. For this imaging model governed by an inverse problem for the coupled diffusion system, which describes the interaction of the excitation field from several boundary sources and the corresponding emission field, we reformulate it as an optimization problem. For solving this non-quadratic optimizing problem, we propose a decomposition scheme, which extracts the horizontal information of the target from the boundary measurement data directly. The realizability of this hybrid imaging scheme is rigorously proved mathematically for cubic and ellipsoid targets, by constructing an indicator function for the horizontal location of the target explicitly. Then based on this horizonal location as a good initial guess for the iteration process, the cost functional is optimized efficiently using the trust domain scheme. Numerical implementations are provided to show the validity of the proposed scheme.

Ferric oxides and (oxy)hydroxides, although plentiful and low-cost, are rarely considered for oxygen evolution reaction (OER) owing to the too high spin state (eg filling ca. 2.0) suppressing the bonding strength with reaction intermediates. Now, a facile adsorption-oxidation strategy is used to anchor FeIII atomically on an ultrathin TiO2 nanobelt to synergistically lower the spin state (eg filling ca. 1.08) to enhance the adsorption with oxygen-containing intermediates and improve the electro-conductibility for lower ohmic loss. The electronic structure of the catalyst is predicted by DFT calculation and perfectly confirmed by experimental results. The catalyst exhibits superior performance for OER with overpotential 270 mV @10 mA cm-2 and 376 mV @100 mA cm-2 in alkaline solution, which is much better than IrO2 /C and RuO2 /C and is the best iron-based OER catalyst free of active metals such as Ni, Co, or precious metals.

Green reactions not only provide us chemical products without any pollution, but also offer us the viable technology to realize difficult tasks in normal conditions. Photo-, photoelectro-, and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future. Especially, some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products, such as H2 evolution (H2 production), O2 evolution/reduction, CO2 reduction, N2 reduction (or N2 fixation) reactions. We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction (HER), at the same time, we also need highly efficient O2 reduction reaction (ORR) in fuel cells for improving the reaction kinetics. Moreover, we can get the clean oxidant O2 from water through O2 evolution reaction (OER), and carry out some reactions without posing any pollution to reaction systems. Furthermore, we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction (CRR). Last but not the least, we can get ammonia from N2 reduction reaction (NRR), which can decrease energy input compared to the traditional Hubble process. These reactions, such as HER, ORR, OER, CRR, and NRR could be realized through solar-, photoelectro- and electro-assisted ways. For them, the catalysts used play crucial roles in determining the efficiency and kinds of products, so we should consider the efficiency of catalysts. However, the cost, synthetic methods of catalysts should also be considered. Nowadays, significant progress has been achieved, however, many challenges still exist, reaction systems, catalysts underlying mechanisms, and so on. As extremely active fields, we should pay attention to them. Under the background, it has motivated us to contribute with a roadmap on ‘Gas-Involved Photo- and Electro-Catalysis’.

In the field of transition-metal-catalyzed C-H activation, N-methoxyamides are widely used as C-H activation substrate. Unexpectedly, in this work N-methoxyamides were found to work as efficient amidation reagents in the rhodium(III)-catalyzed C-H activation with boric acid as a cocatalyst. This reaction features broad substrate scope and good yields.

In this work, we report a series of poly(itaconic acid‐co‐acrylic acid‐co‐acrylamide) (poly(IA‐co‐AAc‐co‐AAm)) hydrogels via frontal polymerization (FP). FP starts on the top of the reaction mixture with aid of heating provided from soldering iron gun. Once polymerization initiated, no further energy is required to complete the process. The influences of IA/AAc weight ratios on frontal velocities, temperatures, and conversions on the reaction time are thoroughly investigated and discussed where the amount of AAm monomer remains constant. Fourier transform‐infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscope (SEM), dynamic mechanical analysis, and the swelling measurement are applied to characterize the as‐synthesized poly(IA‐co‐AAc‐co‐AAm) hydrogels. Interestingly, the swelling ratios of the hydrogels are changed with different IA/AAc contents, and the maximum swelling ratios are ~4439% in water. SEM images describe highly porous morphologies and explain good swelling capabilities. Moreover, the poly(IA‐co‐AAc‐co‐AAm) hydrogels exhibit superior pH‐responsive ability. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2214–2221

Numerous studies have assessed Research and Development (R&D) investment using the real option pricing approach. This paper proposes a more general real option pricing method that both cons...

Construction of junctions between semiconductors is an effective way to promote charge separation and thus improve the photoelectrochemical and photocatalytic performance. Specifically, p-n homojunctions are more efficient due to the larger driving force and lower transfer barrier over the interface. Herein, we fabricated ZnO p-n homojunctions by depositing n-type ZnO nanoparticles (with oxygen vacancy) on the surface of p-type ZnO (with metal vacancy). The structures of the composite were well characterized by TEM, XRD, TG, XPS and EPR analyses. Meanwhile, both the “V-shaped” Mott-Schottky plots and anodic shift of onset potentials confirmed the existence of p-n homojunction, which exhibits much more efficient charge transfer and separation than pure type ZnO as indicated by PL and EIS measurements. As a result, p-n homojunction exhibited activity of 3.2-fold and 3.3-fold higher than pure p-ZnO in photodegradation of phenol and as photocathode in photoelectrochemical water splitting, respectively. This work provides a new strategy for the design and fabrication of highly efficient photocatalysts with promoted charge separation.