A facile and efficient method to produce optically pure benzofuroindolines, especially those without 3‐substituents that are susceptible to rearomatization, through 3+2 annulation of indoles with ...quinones is described. The suitable combination of a BOX ligand CuII hydrate complex and freshly activated molecular sieves functions to give controllably dynamic release of water, which enables the success of this reaction. This reaction can be performed on a gram scale with only 0.5 mol % catalyst loading.
Thinking outside the BOX: A CuII‐catalyzed asymmetric 3+2 annulation of indoles with quinones provides diverse access to the optically pure benzofuroindolines, including those without 3‐substituents that are susceptible to rearomatization, for the first time. The use of a BOX ligand copper hydrate complex in combination with activated molecular sieves for the controlled release of H2O leads to reproducibly high yields and excellent enantioselectivity.
The acoustic velocities of three series of alkali-rich hydrous silicate glasses were determined at ambient conditions using ultrasonic interferometry. The sound velocities and calculated elastic ...properties are nearly linear functions of dissolved water content. The water content derivatives of both compressional d(VP)/d(XH2O) and shear wave velocity d(VS)/d(XH2O) decrease with increasing Na2O content, which suggests that increasing sodium content might weaken the effect of water on acoustic velocities. For each glass series, the shear modulus decreases with increasing water content, whereas the adiabatic bulk modulus (KS) varies little with water content. By comparing our results of KS to previously published data on hydrous alkalic (rhyolite, phonolite, and trachyte) glasses, we speculate that H2O may have a negligible effect on the compressibility of alkalic glasses/melts. The measured densities of each series of glasses were converted to molar volumes and extrapolated to the hypothetical pure water component to derive the partial molar volume of water (VH2O). The resulting VH2O at room pressure and temperature was found to be independent of composition for the three series of glasses, with a value of 10.4 ± 0.5 cm3/mol, whereas the partial molar bulk modulus (KS) of water is composition-dependent, suggesting that VH2O may depend on composition at elevated pressures. Furthermore, the Poisson's ratio (ν) increases linearly with increasing water content for all three composition series. Therefore, the similar behavior of Al-free and Al-bearing glasses implies that water depolymerizes melts in both systems. The decrease of water content derivative of the Poisson's ratio d(ν)/d(XH2O) with increasing Al/(Al+Si) indicates that water interaction with Al-O bonds to produce Al-OH depolymerizes peralkaline silicate melts less effectively than with Si-O bonds to form Si-OH. Hence, we speculate that water prefers to interact with Si-O bonds rather than Al-O bonds in peralkaline silicate systems. The dissolution mechanisms of water between peraluminous and peralkaline melts might be different, which merits further research.
By using the method of weight function, the technique of real analysis, and the theory of special functions, a multi-parameter Hilbert-type integral inequality and its equivalent form are ...established, and their constant factors are proved to be the best possible. The expressions of operator with norm are given. As an application, relevant results in the references and some new inequalities are obtained by assigning some parameter values.
While various static cues such as matrix stiffness have been known to regulate stem cell differentiation, it is unclear whether or not dynamic cues such as degradation rate along with the change of ...material chemistry can influence cell behaviors beyond simple integration of static cues such as decreased matrix stiffness. The present research is aimed at examining effects of degradation rates on adhesion and differentiation of mesenchymal stem cells (MSCs) in vitro on well-defined synthetic hydrogel surfaces. Therefore, we synthesized macromers by extending both ends of poly(ethylene glycol) (PEG) with oligo(lactic acid) and then acryloyl, and the corresponding hydrogels that were obtained after photopolymerization of the macromers were biodegradable. Combining the unique techniques of block copolymer micelle nanolithography with transfer lithography, we prepared a nanoarray of cell-adhesive arginine-glycine-aspartate peptides on this nonfouling biodegradable hydrogel. The biodegradation is caused by hydrolysis of the ester bonds, and different degradation rates in the cell culture medium were achieved by different stages of accelerated pre-hydrolysis in an acidic medium. For the following cell culture and induction, both the matrix stiffness and degradation rate varied among the examined groups. While adipogenic differentiation of MSCs can be understood by the lowered stiffness, the osteogenic differentiation was contradictory with common sense because we found enhanced osteogenesis on soft hydrogels. Higher degradation rates were suggested to account for this interesting phenomenon in the sole osteogenic/adipogenic induction and even more complicated trends in the co-induction. Hence, the degradation rate is a dynamic cue influencing cell behaviors, which should be paid attention to for degradable biomaterials.
Adjuvants have been of great interest to vaccine formulation as immune-stimulators. Prior to the recent research in the field of immune stimulation, conventional adjuvants utilized for aluminum-based ...vaccinations dominated the adjuvant market. However, these conventional adjuvants have demonstrated obvious defects, including poor protective efficiency and potential side effects, which hindered their widespread circulation. Outer membrane vesicles (OMVs) naturally exist in gram-negative bacteria and are capable of engaging innate and adaptive immunity and possess intrinsic adjuvant capacity. They have shown tremendous potential for adjuvant application and have recently been successfully applied in various vaccine platforms. Adjuvants could be highly effective with the introduction of OMVs, providing complete immunity and with the benefits of low toxicity; further, OMVs might also be designed as an advanced mucosal delivery vehicle for use as a vaccine carrier. In this review, we discuss adjuvant development, and provide an overview of novel OMV adjuvants and delivery vehicles. We also suggest future directions for adjuvant research. Overall, we believe that OMV adjuvants would find high value in vaccine formulation in the future.
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•Dicyandiamide is transformed into melamine-cyanaurate complex (MCA) under hydrothermal process.•MCA leads to the formation of mesopores g-C3N4 nanosheets under optimized ...conditions.•The g-C3N4 nanostructure shows a high hydrogen evolution rate of 136.9 μmol/h.•Its apparent quantum efficiency (AQE) is as high as 10.6% at 420 ± 15 nm.
Annealing a supramolecular precursor with a similar structure to the local arrangement over the g-C3N4 building blocks at molecular level is a simple and effective route for preparing g-C3N4 nanostructures. Herein, a facile process for synthesizing the supramolecular precursor is presented, from which the uniform 3D holey g-C3N4 nanosheets with considerably high photocatalytic performance are obtained. The precursor synthesized from hydrothermal treatment of dicyandiamide presents a similar structure to of that the melamine-cyanaurate (MCA) complex prepared by the assembly of melamine and cyanuric acid, while the differences in thermal decomposition and morphology exist. Consequently, the g-C3N4 samples obtained by annealing the two precursors obtained via the different synthesis routes exhibit district microstructures, optical properties, charge recombination and photoelectrochemical behavior, and photocatalytic activity. It is found that the g-C3N4 nanostructure prepared by annealing the hydrothermal product of dicyandiamide shows the hydrogen evolution rate of 136.9 μmol/h, which is 2.5 folds that of the one obtained from the conventional MCA complex and 15-folds of bulk g-C3N4, and its apparent quantum efficiency (AQE) reaches 10.6% at 420 ± 15 nm.
The driving force for active physical and biological systems is determined by both the underlying landscape and nonequilibrium curl flux. While landscape can be experimentally quantified from the ...histograms of the collected real-time trajectories of the observables, quantifying the experimental flux remains challenging. In this work, we studied the single-molecule enzyme dynamics of horseradish peroxidase with dihydrorhodamine 123 and hydrogen peroxide (H₂O₂) as substrates. Surprisingly, significant deviations in the kinetics from the conventional Michaelis–Menten reaction rate were observed. Instead of a linear relationship between the inverse of the enzyme kinetic rate and the inverse of substrate concentration, a nonlinear relationship between the two emerged. We identified nonequilibrium flux as the origin of such non-Michaelis–Menten enzyme rate behavior. Furthermore, we quantified the nonequilibrium flux from experimentally obtained fluorescence correlation spectroscopy data and showed this flux to led to the deviations from the Michaelis–Menten kinetics. We also identified and quantified the nonequilibrium thermodynamic driving forces as the chemical potential and entropy production for such non-Michaelis–Menten kinetics. Moreover, through isothermal titration calorimetry measurements, we identified and quantified the origin of both nonequilibrium dynamic and thermodynamic driving forces as the heat absorbed (energy input) into the enzyme reaction system. Furthermore, we showed that the nonequilibrium driving forces led to time irreversibility through the difference between the forward and backward directions in time and high-order correlations were associated with the deviations from Michaelis–Menten kinetics. This study provided a general framework for experimentally quantifying the dynamic and thermodynamic driving forces for nonequilibrium systems.
Multi-view depth is crucial for describing positioning information in 3D space for virtual reality, free viewpoint video, and other interaction- and remote-oriented applications. However, in cases of ...lossy compression for bandwidth limited remote applications, the quality of multi-view depth video suffers from quantization errors, leading to the generation of obvious artifacts in consequent virtual view rendering during interactions. Considerable efforts must be made to properly address these artifacts. In this paper, we propose a cross-view multi-lateral filtering scheme to improve the quality of compressed depth maps/videos within the framework of asymmetric multi-view video with depth compression. Through this scheme, a distorted depth map is enhanced via non-local candidates selected from current and neighboring viewpoints of different time-slots. Specifically, these candidates are clustered into a macro super pixel denoting the physical and semantic cross-relationships of the cross-view, spatial and temporal priors. The experimental results show that gains from static depth maps and dynamic depth videos can be obtained from PSNR and SSIM metrics, respectively. In subjective evaluations, even object contours are recovered from a compressed depth video. We also verify our method via several practical applications. For these verifications, artifacts on object contours are properly managed for the development of interactive video and discontinuous object surfaces are restored for 3D modeling. Our results suggest that the proposed filter outperforms state-of-the-art filters and is suitable for use in multi-view color plus depth-based interaction- and remote-oriented applications.
The induced built-in electric field by piezoelectric materials has proven to be one of the most effective strategies for modulating the charge-transfer pathway and inhibiting carrier recombination. ...In this work, a series of core-shell structured BaTiO3@TiO2 nanowires (BT@TiO2 NWs) heterojunctions were synthesized and the significant coupling effects between BaTiO3 (BT) and TiO2 resulted in surperior piezo-photocatalytic performance, which was demonstrated by three typical types of dyes with high concentrations. The degradation efficiency of 30 mg/L Rhodamine B (RhB), Methylene blue (MB) and Indigo Carmine (IC) solutions by 0.5 g/L BT@TiO2 NWs reached 99.5% in 75 min, 99.8% in 105 min and 99.7% in 45 min, respectively, which are much higher than piezo-photocatalysis systems reported before. To reveal the coupling mechanisms, photoelectrochemical measurements and band diagram analysis were carried out. The carrier concentration was increased from 2.28 × 1017 cm−3 to 4.91 × 1018 cm−3 and the lifetime of charges was improved from 50.37 ms to 60.98 ms due to the construction of a heterojunction between TiO2 and BT. It was proposed that the tilting and bending of the energy band caused by the introduction of a piezoelectric polarization can facilitate carrier separation both in the bulk phase and at the surfaces of semiconductors, resulting in outstanding piezo-photocatalytic properties for highly concentrated dye degradation. This work provides a universal catalyzer for highly concentrated dye degradation.
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•BaTiO3@TiO2 core-shell nanowires were applied in photo-piezoelectric catalysis for the first time.•The outstanding piezo-photocatalytic properties for high concentrated dye degradation was achieved.•The mechanism of piezo-photoelectric coupling effect of BT@TiO2 heterojunction was revealed.
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