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.
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.
We report the fabrication of 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays by a facile hydrothermal process and their use as photoelectrodes in a photoelectrochemical (PEC) cell for ...high-performance solar water splitting. The morphology, microstructure, and phase of pristine TiO2 and 2D ZnIn2S4 nanosheet/1D TiO2 nanorod heterojunction arrays were characterized in detail. PEC measurements showed that 2D/1D heterojunction arrays offered enhanced photocurrent density (3 times higher than that of pristine TiO2), negatively shifted onset potential from 0.05 to −0.53 V, and high light on/off cycle stability. Electrochemical impedance investigation attested to a significant improvement of the interface electron transfer kinetics in this heterojunction, thus facilitating electron–hole separation, transfer, and collection, which resulted in enhanced PEC properties.
Background and Purpose
Spermidine, a natural polyamine, is abundant in mammalian cells and is involved in cell growth, proliferation, and regeneration. Recently, oral spermidine supplements were ...cardioprotective in age‐related cardiac dysfunction, through enhancing autophagic flux. However, the effect of spermidine on myocardial injury and cardiac dysfunction following myocardial infarction (MI) remains unknown.
Experimental Approach
We determined the effects of spermidine in a model of MI, Sprague–Dawley rats with permanent ligation of the left anterior descending artery, and in cultured neonatal rat cardiomyocytes (NRCs) exposed to angiotensin II (Ang II). Cardiac function in vivo was assessed with echocardiography. In vivo and in vitro studies used histological and immunohistochemical techniques, along with western blots.
Key Results
Spermidine improved cardiomyocyte viability and decreased cell necrosis in NRCs treated with angiotensin II. In rats post‐MI, spermidine reduced infarct size, improved cardiac function, and attenuated myocardial hypertrophy. Spermidine also suppressed the oxidative damage and inflammatory cytokines induced by MI. Moreover, spermidine enhanced autophagic flux and decreased apoptosis both in vitro and in vivo. The protective effects of spermidine on cardiomyocyte apoptosis and cardiac dysfunction were abolished by the autophagy inhibitor chloroquine, indicating that spermidine exerted cardioprotective effects at least partly through promoting autophagic flux, by activating the AMPK/mTOR signalling pathway.
Conclusions and Implications
Our findings suggest that spermidine improved MI‐induced cardiac dysfunction by promoting AMPK/mTOR‐mediated autophagic flux.
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