Mass Spectrometry Imaging of Low-Molecular-Weight Phenols Liberated from Plastics

The abundant and heterogeneous distribution of toxic phenol from plastics has drawn worldwide attention. However, the common analysis methods failed to identify the accurate species of these phenolic hazards from plastics in a direct and nondestructive approach. Herein, we demonstrate the layered double hydroxides (LDHs) as a novel matrix in matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) for low-molecular-weight phenols leaked from plastics. LDHs own abundant hydroxyl groups to facilitate chemoselectivity and ionization of phenols through the formation of hydrogen bonds with these phenols. More importantly, the LDH matrix could provide a distinguishable signal for the homolog and isomeride of these phenolic hazards. The developed method could realize nondestructive and in situ mapping of phenolic hazards in plastics. Our success could help to track the low-molecular-weight compounds liberated from plastics and supply spatial information for polluted plastics. We anticipated that the proposed approach could provide sufficient information to evaluate and alarm the safety of food packaging plastics

Table_1_Exploring public attitudes toward live-streaming fitness in China: A sentiment and content analysis of China's social media Weibo.DOCX

ObjectivesLive-streaming fitness is perceived by the Chinese government as an invaluable means to reduce the prevalence of physical inactivity amid the COVID-19 pandemic. This study aims to investigate the public altitudes of the Chinese people toward live-streaming fitness and provide future health communication strategies on the public promotion of live-streaming fitness accordingly.MethodsThis study collected live-streaming fitness-related microblog posts from July 2021 to June 2022 in Weibo, the Chinese equivalent to Twitter. We used the BiLSTM-CNN model to carry out the sentiment analysis, and the structured topic modeling (STM) method to conduct content analysis.ResultsThis study extracted 114,397 live-streaming fitness-related Weibo posts. Over 80% of the Weibo posts were positive during the period of the study, and over 85% were positive in half of the period. This study finds 8 topics through content analysis, which are fitness during quarantine; cost reduction; online community; celebrity effect; Industry; fitness injuries; live commerce and Zero Covid strategy.ConclusionsIt is discovered that the public attitudes toward live-streaming fitness were largely positive. Topics related to celebrity effect (5–11%), fitness injuries (8–16%), live commerce (5–9%) and Zero Covid strategy (16–26%) showed upward trends in negative views of the Chinese people. Specific health communication strategy suggestions are given to target each of the negative topics.</p

Amplified Fluorescence Quenching of Lucigenin Self-Assembled inside Silica/Chitosan Nanoparticles by Cl^–

Fluorescence sensing of an analyte based on the fluorophore collective effect is a reliable, sensitive sensing approach. Many ultralow targets can be detected on the basis of the high sensitivity and signal amplification of the fluorescence sensing system. However, the complicated synthesis procedures, harsh conditions required to design and control the fluorescence molecular probes and conjugated chain length, and the higher cost of synthesis are still challenges. To address these issues, we developed a simple, rapid, and sensitive collective effect based fluorescence sensing platform. In this sensing platform, the fluorophore unit was self-assembled on the wall of the nanopores of the porous structural silica/chitosan nanoparticles (SCNPs) on the basis of the electrostatic interaction and supermolecular interaction between the fluorophores and SiO^– groups and chitosan. Since these self-assembled fluorophores are close enough to communicate with each other on the basis of the space confinement effect of the pore size, many fluorophore units could interact with a single analyte and produce an amplified fluorescence sensing ability. Chloride ion, an important anion in biological fluids, and lucigenin, a typical fluorescent dye, were used as a model to confirm the proof-of-concept strategy. Our results showed that, compared to free-state lucigenin in solution, the assembled-state lucigenin in SCNPs presented an about 10-fold increase in its Stern–Volmer constant when the concentration of Cl^– was lower than 10 mM, and this fluorescence nanosensor was also successfully used to sense the chloride ion in living cells

Nickel-Catalyzed Selective Decarbonylation of α‑Amino Acid Thioester: Aminomethylation of Mercaptans

The nickel-catalyzed aminomethylation of mercaptans has been disclosed that offers efficient and expedient access to synthesize α-aminosulfides. The intramolecular fragment coupling shows excellent chemoselectivity. This transformation shows good functional-group compatibility, tolerates a wide range of electron-withdrawing, electron-neutral, and electron-donating substituents in this process, and can serve as a powerful synthetic tool for the synthesis of α-aminosulfides at a gram scale. Thus, the newly developed methodology enables a facile route for C–S bond formation in a straightforward fashion

Data_Sheet_1_Substrate-Assisted Visualization of Surfactant Micelles via Transmission Electron Microscopy.doc

The visualization of the micellar morphological evolution for surfactant has drawn much attention due to its self-assemble ability to fold into various structures. However, the direct observation of the soft materials with low atomic number has been hampered because of the poor scattering contrast and complex staining process by the traditional transmission electron microscopy (TEM) techniques. Herein, we reported a novel strategy to the visualization of surfactant micelles with the assistance of layered double hydroxides (LDHs) via TEM. Owing to the uniformly distributed metal ions and positive charges in the LDHs, the surfactant at the micelle-water interface reacted with LDHs to form a stabilized architecture through electrostatic and hydrogen-bond interactions. The morphologies of the surfactant can be clearly observed through the surfactant-LDHs architectures, exhibiting high contrast by TEM techniques. Significantly, the micellar evolutions involving the spherical, rodlike, and wormlike shapes were successfully distinguished. Our results may provide great possibilities and inspirations for the visualization for morphology of soft matters.</p

To Distinguish Electrostatic, Coordination Bond, Nonclassical Polarization, and Dispersion Forces on Cation–Clay Interactions

Recent research has suggested that inorganic ions give rise to complex interfacial adsorption effects, but people do not fully understand the mechanisms at present. In this study, the interface adsorption energies of H+ (without extranuclear electron), Li+, and Cs+ (with extranuclear electrons but possessing a large difference in ionic radius) on montmorillonite surface were estimated to elucidate the contribution of electrostatic, coordination bond, nonclassical polarization, and dispersion forces to interface adsorption energies. The results showed that under given cationic concentrations, the equilibrium adsorption energies followed the sequence of Cs+ > H+ > Li+. Moreover, the adsorption energies of H+ (with minimum ion radius) were close to Cs+ (with largest ion radius) but much larger than that of Li+ under relative low cationic concentrations, whereas the adsorption energies of Cs+, H+, and Li+ approached each other under the highest cationic concentration of 0.1 mol L–1, although their ionic sizes are in great difference. With these results, we conclude the following: for Li+, the observed adsorption energy could be fully explained by the classic electrostatic force; for H+, the nonelectrostatic adsorption energy was from the coordinate bond between H+ and O atom at surface, and the coordinate bond adsorption energy of H+ was electric-field-dependent; for Cs+, under relative low electrolyte concentrations, the nonelectrostatic adsorption energy was from the nonclassic polarizability of Cs+, and under the high electrolyte concentration of 0.1 mol L–1, the nonelectrostatic adsorption energy was from the dispersion force of Cs+ and NO3– through ion pair adsorption

Nickel/Copper Cooperative Catalysis Decarbonylative Heteroarylation of Aryl Anhydrides with Benzoxazoles via C–O/C–H Coupling

A new strategy for the synthesis of 2-arylbenzoxazole derivatives via nickel-/copper-catalyzed decarbonylative heteroarylation of aryl anhydrides via C–O/C–H coupling has been developed. The reaction is promoted by a user-friendly, inexpensive, and air- and moisture-stable Ni precatalyst. A variety of 2-arylbenzoxazole derivatives have been successfully synthesized and have good functional group tolerance in this process, which afforded products in moderate-to-excellent yields

Specific Anion Effects for Aggregation of Colloidal Minerals: A Joint Experimental and Theoretical Study

In this work, dynamic light scattering experiments and density functional calculations were combined to demonstrate the specific anion effects for the aggregation of negatively charged colloidal minerals. Although the aggregation kinetics is dominated by electrolyte cations, anions also play a significant role. The critical coagulation concentrations and activation energies indicated a clear Hofmeister series for the various anions as H₂PO₄^– < Cl^– < NO₃^– < SO₄^2– < HPO₄^2– < PO₄^3–. Moreover, interaction energies of anions with cations and proton affinities of anions were explored as the influencing factors for anion specificities, which were corroborated by measurement of surface charge densities. Owing to the largest interactions with cations, PO₄^3– causes the most pronounced inhibition effect to the aggregation kinetics and corresponds to the strongest anion specificity. Proton exchange from H₂PO₄^– reduces the negative charges of minerals and accelerates the aggregation process, thus resulting in an inferior anion specificity than NO₃^–. Density functional calculations indicated that proton transfer from minerals to OH^– can occur facilely and increase the negative charges of minerals, as confirmed by charge density measurements and dilution experiments. This further adds to the aggregation difficulty and causes OH^– to show distinctly stronger anion specificity than other univalent anions