Within 40 min, hexagonal boron nitride (
h
-BN) was rapidly synthesized via microwave heating without using catalyst and protective gas. Melamine and boric acid were used as raw materials, and carbon ...fiber was utilized as microwave absorber, respectively. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) were used to characterize the structures and morphologies of the samples. Results indicated that the whisker-like
h
-BN with diameters of 200–500 nm and lengths of 15–25 μm were successfully obtained. The specific surface area of the product was 510.941 m
2
g
−1
. The maximum adsorption capacity for methylene blue solution of the as-obtained
h
-BN was high up to ~ 230 mg g
−1
at room temperature. The excellent adsorption performance of the samples may be attributed to the oxygen-containing functional groups and defects formed during the high-energy microwave irradiation.
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•Top/bottom heterostructured SnO2/Sn was formed during electrocatalysis CO2 reduction.•The sample was examined by operando Raman and X-ray photoelectron spectroscopy.•The SnO2/Sn ...delivers a FE of 94% for formate and current density of 113.6 mA cm−2 at − 1.18 V.•DFT calculations show that formate was more favored on SnO2/Sn than SnO2 and Sn.
Design and engineering of low-cost, high-performance catalysts is a critical step in electrochemical CO2 reduction (CO2R) to value-added chemicals and fuels. Herein, SnO2 nanoparticles were grown onto carbon cloth (SnO2/CF) by a facile hydrothermal procedure and exhibited excellent electrocatalytic activity towards CO2R due to reconstruction into SnO2/Sn Mott-Schottky heterojunctions during CO2R electrolysis, as manifested in X-ray diffraction, X-ray photoelectron spectroscopy, and operando Raman spectroscopy measurements. The heterostructured SnO2/Sn electrode delivered a high faradaic efficiency of 93 ± 1% and a partial current density of 28.7 mA cm−2 for formate production at − 1.0 V vs. reversible hydrogen electrode in an H-type cell (which remained stable for 9 h), and 174.86 mA cm−2 at − 1.18 V on a gas-diffusion electrode in a flow cell. Density functional theory calculations show that the SnO2/Sn heterostructures in situ formed under CO2R conditions helped decrease the energy barrier to form formate as compared to pristine SnO2 and Sn, and were responsible for the high activity and selectivity of formate production. Results from this study unravels the evolution dynamics of SnO2 catalysts under CO2R condition and provides a further understanding of the active component of SnO2 catalyst in CO2R.
Ultrafast terahertz spectroscopy accesses the dark excitonic ground state in resonantly excited (6,5) single-walled carbon nanotubes via internal, direct dipole-allowed transitions between the ...lowest-lying dark-bright pair state of ∼6 meV. An analytical model reproduces the response that enables the quantitative analysis of transient densities of dark excitons and e-h plasma, oscillator strength, transition energy renormalization, and dynamics. Nonequilibrium, yet stable, quasi-one-dimensional quantum states with dark excitonic correlations rapidly emerge even with increasing off-resonance photoexcitation and experience a unique crossover to complex phase-space filling of both dark and bright pair states, different from dense two- and three-dimensional excitons influenced by the thermalization, cooling, and ionization to free carriers.
Protein modification by chemical reagents has played an essential role in the treatment of human diseases. However, the reagents currently used are limited to the covalent modification of cysteine ...and lysine residues. It is thus desirable to develop novel methods that can covalently modify other residues. Despite the fact that the carboxyl residues are crucial for maintaining the protein function, few selective labeling reactions are currently available. Here, we describe a novel reactive probe, 3-phenyl-2H-azirine, that enables chemoselective modification of carboxyl groups in proteins under both in vitro and in situ conditions with excellent efficiency. Furthermore, proteome-wide profiling of reactive carboxyl residues was performed with a quantitative chemoproteomic platform.
The technological demand to push the gigahertz (10(9) hertz) switching speed limit of today's magnetic memory and logic devices into the terahertz (10(12) hertz) regime underlies the entire field of ...spin-electronics and integrated multi-functional devices. This challenge is met by all-optical magnetic switching based on coherent spin manipulation. By analogy to femtosecond chemistry and photosynthetic dynamics--in which photoproducts of chemical and biochemical reactions can be influenced by creating suitable superpositions of molecular states--femtosecond-laser-excited coherence between electronic states can switch magnetic order by 'suddenly' breaking the delicate balance between competing phases of correlated materials: for example, manganites exhibiting colossal magneto-resistance suitable for applications. Here we show femtosecond (10(-15) seconds) photo-induced switching from antiferromagnetic to ferromagnetic ordering in Pr0.7Ca0.3MnO3, by observing the establishment (within about 120 femtoseconds) of a huge temperature-dependent magnetization with photo-excitation threshold behaviour absent in the optical reflectivity. The development of ferromagnetic correlations during the femtosecond laser pulse reveals an initial quantum coherent regime of magnetism, distinguished from the picosecond (10(-12) seconds) lattice-heating regime characterized by phase separation without threshold behaviour. Our simulations reproduce the nonlinear femtosecond spin generation and underpin fast quantum spin-flip fluctuations correlated with coherent superpositions of electronic states to initiate local ferromagnetic correlations. These results merge two fields, femtosecond magnetism in metals and band insulators, and non-equilibrium phase transitions of strongly correlated electrons, in which local interactions exceeding the kinetic energy produce a complex balance of competing orders.
Alzheimer's disease (AD), the most common neurodegenerative disorder, is characterized by memory loss and cognitive dysfunction. The accumulation of misfolded protein aggregates including amyloid ...beta (Aβ) peptides and microtubule associated protein tau (MAPT/tau) in neuronal cells are hallmarks of AD. So far, the exact underlying mechanisms for the aetiologies of AD have not been fully understood and the effective treatment for AD is limited. Autophagy is an evolutionarily conserved cellular catabolic process by which damaged cellular organelles and protein aggregates are degraded via lysosomes. Recently, there is accumulating evidence linking the impairment of the autophagy–lysosomal pathway with AD pathogenesis. Interestingly, the enhancement of autophagy to remove protein aggregates has been proposed as a promising therapeutic strategy for AD. Here, we first summarize the recent genetic, pathological and experimental studies regarding the impairment of the autophagy–lysosomal pathway in AD. We then describe the interplay between the autophagy–lysosomal pathway and two pathological proteins, Aβ and MAPT/tau, in AD. Finally, we discuss potential therapeutic strategies and small molecules that target the autophagy–lysosomal pathway for AD treatment both in animal models and in clinical trials. Overall, this article highlights the pivotal functions of the autophagy–lysosomal pathway in AD pathogenesis and potential druggable targets in the autophagy–lysosomal pathway for AD treatment.
Multiple factors including gene mutations impair autophagy–lysosomal pathway, and exaggerate AD progression. Enhancing autophagy can reduce Aβ levels, promote pathological tau degradation and thus is a promising therapeutic strategy for Alzheimer's disease. Display omitted
Traditional Chinese medicine in COVID-19 Lyu, Ming; Fan, Guanwei; Xiao, Guangxu ...
Acta pharmaceutica Sinica. B,
11/2021, Volume:
11, Issue:
11
Journal Article
Peer reviewed
Open access
COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread across the globe, posing an enormous threat to public health and safety. Traditional Chinese ...medicine (TCM), in combination with Western medicine (WM), has made important and lasting contributions in the battle against COVID-19. In this review, updated clinical effects and potential mechanisms of TCM, presented in newly recognized three distinct phases of the disease, are summarized and discussed. By integrating the available clinical and preclinical evidence, the efficacies and underlying mechanisms of TCM on COVID-19, including the highly recommended three Chinese patent medicines and three Chinese medicine formulas, are described in a panorama. We hope that this comprehensive review not only provides a reference for health care professionals and the public to recognize the significant contributions of TCM for COVID-19, but also serves as an evidence-based in-depth summary and analysis to facilitate understanding the true scientific value of TCM.
The potential mechanisms of TCM remedy in three phases of distinct disease stages for COVID-19 are systematically described within a panorama by integrating available clinical and preclinical evidence. Display omitted
The mechanism of action of artemisinin and its derivatives, the most potent of the anti-malarial drugs, is not completely understood. Here we present an unbiased chemical proteomics analysis to ...directly explore this mechanism in Plasmodium falciparum. We use an alkyne-tagged artemisinin analogue coupled with biotin to identify 124 artemisinin covalent binding protein targets, many of which are involved in the essential biological processes of the parasite. Such a broad targeting spectrum disrupts the biochemical landscape of the parasite and causes its death. Furthermore, using alkyne-tagged artemisinin coupled with a fluorescent dye to monitor protein binding, we show that haem, rather than free ferrous iron, is predominantly responsible for artemisinin activation. The haem derives primarily from the parasite's haem biosynthesis pathway at the early ring stage and from haemoglobin digestion at the latter stages. Our results support a unifying model to explain the action and specificity of artemisinin in parasite killing.
Fourier transform infrared spectroscopy was used to characterize the structure of phenol formaldehyde (PF) resin pyrolyzed at different temperatures, and pyrolysis gas chromatography mass ...spectrometry was used to observe the volatiles. A pyrolysis mechanism has been consequently deduced, and several previous ambiguities have been clarified. The occurrence of carbon monoxide and carbon dioxide is attributed to the oxidization of methylene. However, not oxidization, but methylene scission is mainly responsible for the decomposition of PF resin. At the same time, methylene radicals combine with other small molecules and form some volatiles such as ethylene and methanol. With the elevation of heat treatment temperature, PF resin is progressively transformed into amorphous carbon by pyrolysis and polycyclic reactions.
The potential damage during the pyrolysis of phenol–formaldehyde (PF) resin in the manufacturing of carbon/carbon components is serious. Accurately modeling the kinetics of the pyrolysis reaction can ...lead to improvements in processing. To study the pyrolysis kinetics of PF resin, non-isothermal pyrolysis kinetics is investigated using thermogravimetric analysis (ТGA) at controlled heating rates. The research indicates that the pyrolysis process consists of three consecutive and overlapping stages. PEAKFIT was employed to separate overlapping regions, and then pyrolysis kinetic triplet of PF resin is calculated. With the determined apparent activation energies, the most probable mechanism functions and the corresponding pre-exponential factor, the model agrees well with the experimental data.
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