Carbene-catalyzed [3 + 2 + 1] annulation via C-N radical coupling of iminyl radicals and ketyl radicals.

An N-heterocyclic carbene-catalyzed cascade [3 + 2 + 1] annulation to assemble vinyl azides, aldehydes, and trihalomethyl reagents (Togni's reagent or CCl4) towards 1,3-oxazin-6-ones was reported. The cascade was triggered by an NHC-catalyzed single electron transfer (SET) between aldehydes and trihalomethyl reagents, followed by the addition of trihalomethyl radicals to vinyl azides, a denitrogenated transformation into iminyl radicals, a C-N radical coupling of iminyl radicals and ketyl radicals, and a base-controlled dehalogenative cyclization.

The eco-friendly electrosynthesis of trifluoromethylated spirocyclic indolines and their anticancer activity.

A method for the electrochemical diastereoselective oxytrifluoromethylation of indoles was developed for the eco-friendly synthesis of CF3-containing spirocyclic indolines. The cascade reaction comprised anodic oxidation to obtain CF3 radicals, the addition of radicals to indoles, and intramolecular spirocyclization. The reaction system without external chemical oxidants could easily be scaled up. Antiproliferation assays of these CF3-substituted spirocyclic indolines exhibited their promising activities and selectivities toward several types of cancer cells, including Huh-7, A549, and cisplatin-resistant cancer cells (A549/DDP).

Revisiting the effect of hierarchical structure on the superhydrophobicity.

We have studied the wetting behaviors of surfaces with a single micro-scale structure and a double micro/nano hierarchical structure, respectively. We have found the delayed wetting phenomenon on the single micro scale surface, which indicates that the wetting state transits from the initial Cassie state to the Cassie impregnating one. Furthermore, the droplet rebound becomes incomplete on the single micro scale surface when the impact velocity exceeds a critical value. On the contrary, complete rebound can still be observed when impacting on the micro/nano hierarchical structure. We proposed that, under static deposition the wetting transition occurs though the contact line depinning mechanism, whereas it occurs via sagging mechanism under a dynamic impact. Our results may be helpful for the understanding of superhydrophobicity and the wetting transition on complex structures.

Tunable shape transformation of freezing liquid water marbles.

Liquid water marbles coated with fumed silica nanoparticles exhibit various shape transformations upon freezing which are dependent on the hydrophobicity of the nanoparticles. The shape can be recovered during re-melting. For marbles coated with the most hydrophobic particles, a vertically prolonged morphology with a pointed protrusion on the top is formed on freezing. For marbles coated with less hydrophobic particles, a lateral expanded flying saucer-shaped morphology is formed. The different responses to freezing result from the different heterogeneous nucleation sites owing to the different positions of the particles at the air-water interface. If the particles are more immersed in water, ice embryos tend to form in the concave cavities between the particles. The volume expansion of water caused by freezing and continuous nucleation lead to continuous lateral stretching of the particle network coating the droplet surface and ultimately to the horizontally inflated shape of the marble. If the particles are more exposed to air, nucleation occurs on the convex surface of the particles, similar to that of a bare water droplet on a hydrophobic substrate.

Tuning the wettability of an aluminum surface via a chemically deposited fractal dendrite structure.

We have developed a straightforward method to tune the wettability of an aluminum substrate within a contact angle (CA) range from 2(°) to 170(°) by chemical deposition in CuCl2 solution and fluoroalkylsilane (FAS) modification. The CA of the as-deposited surface decreases with deposition time due to the growth of fractal copper dendrites, which enhance the surface roughness significantly. After subsequent modification with FAS, a superhydrophobic surface with CA 170(°) and sliding angle less than 5(°) has been obtained. With the increase of CA, the maximum spreading of water droplets is reduced. A bouncing behavior is observed for droplets impinging on the superhydrophobic substrate, suggesting its potential application as a self-cleaning surface.

Collaborative Filtering Algorithm-Based Destination Recommendation and Marketing Model for Tourism Scenic Spots.

The information age of rapid development of tourism industry provides abundant travel information, but it also comes with the problem of information overload, which makes it difficult to meet the growing personalized needs of people. The traditional collaborative filtering recommendation algorithm (CFA) also suffers from the problem of data sparsity when the user population increases. Therefore, this study optimizes the CFA through the similarity factor and correlation factor and enhances the tourism sense of travel experience through the satisfaction balance strategy. The experimental results show that the improved CFA method has the highest average accuracy on the overall dataset and the best recommendation performance of the satisfaction balance strategy. Overall, the recommendation model in this study is useful for attraction selection of users and marketing optimization of travel companies.

The Relationship Between Social Media Digitalization and Coronavirus Disease 2019 Fear Among Service Sector Employees.

In the age of digitalization, social media has played a significant role in quickly spreading the news about current affairs. From December 2019 to now, coronavirus disease 2019 (COVID-19), with its several mutated shapes, has more transmissible potential catastrophe and has become a severe phenomenon issue worldwide. The international spread of the epidemic has created fear among people, especially employees working physically in different organizations. The present research aimed to measure the impact of social media on its users in the China. The social media users more often were influenced by shocking news instructively and destructively. The research analysis was based on service sector employees and data collected from 630 respondents via a structured questionnaire. This research was confirmed the negative impact of fear on social media on the performance of employees. This research was also confirmed the moderation impact of the COVID-19 vaccine on the relationship between social media fear and employee performance. This research recommends that the China Censor Board checked the news and its validity to reduce the fear of COVID-19 among employees. This research will become a roadmap for organizations and media controllers to understand the impact of social media during an intense situation. The telecommunication sector will reduce psychological disease and enhance the work capability of employees by controlling unnecessary and unapproved material about sensitive issues.

Synthesis of a Carbon-Loaded Bi2O2CO3/TiO2 Photocatalyst with Improved Photocatalytic Degradation of Methyl Orange Dye.

A microflower-like C/Bi2O2CO3/TiO2 nanocomposite was prepared via a two-step method. Scanning electron microscopy (SEM) showed the sample to have a layered petal-like microstructure consisting of many nanosheets with an average diameter of 2-5 µm, along with activated carbon (AC) or carbon nanotubes (CNTs) and TiO2 nanoparticles deposited on the surface. Compared with pure Bi2O2CO3, Bi2O2CO3/TiO2 photocatalyst loaded with microflower-like carbon has a good degradation rate of methyl orange (MO) under visible light (0.019 min-1). The highest photodegradation efficiency of MO by AC or CNT-loaded Bi2O2CO3/TiO2 microflowers reached a maximum of 95% degradation after 180 minutes of reaction. The results show that the photocatalytic reaction of the hole and the hydroxyl free radical groups were important for the process of the photocatalytic degradation, and the effect of the hole was slightly greater than that of the hydroxyl free radical. After comparing the different photocatalysts, it showed that C and TiO2 could improve the photocatalytic activity of Bi2O2CO3-based photocatalysts.

Transparent Bioreactors Based on Nanoparticle-Coated Liquid Marbles for in Situ Observation of Suspending Embryonic Body Formation and Differentiation.

Transparent liquid marbles coated with hydrophobic silica nanoparticles were used as micro-bioreactors for embryonic stem cell (ESC) culturing. The high transparency of silica liquid marbles enables real-time and in situ monitoring of embryonic body (EB) formation and differentiation. The experimental result shows that ESCs can aggregate with each other close to the bottom of the liquid marble and form EBs, while remaining suspended in the culture media. The differentiation of the suspending EBs into contractile cardiomyocytes has been demonstrated inside the transparent liquid marbles, which enable the in situ microscopic observation. It was also found, through comparison, that ESCs in a bare sessile drop placed on a superhydrophobic substrate tend to anchor onto the substrate and then differentiate following the normal way of cell spreading, i.e., withdrawal from the cell cycle, fusion with nascent myotubes, and final differentiation into cardiomyocytes. In contrast, liquid marble particle shells weaken the adhesion of spherical EBs to the substrate, encouraging them to differentiate in suspension into cardiomyocytes, without anchoring. The results of this study highlight the promising performance of liquid marbles as "one-pot" micro-bioreactors for EB formation and differentiation.