The application of hydrogels for enamel remineralization.

Enamel is composed of numerous uniformly wide, well-oriented hydroxyapatite crystals. It possesses an acellular structure that cannot be repaired after undergoing damage. Therefore, remineralization after enamel defects has become a focal point of research. Hydrogels, which are materials with three-dimensional structures derived from cross-linking polymers, have garnered significant attention in recent studies. Their exceptional properties make them valuable in the application of enamel remineralization. In this review, we summarize the structure and formation of enamel, present the design considerations of hydrogels for enamel remineralization, explore diverse hydrogels types in this context, and finally, shed light on the potential future applications in this field.

The phylogeny and distribution of Wolbachia in two pathogen vector insects, Asian citrus psyllid and Longan psyllid.

Background: Wolbachia is the most abundant bacterial endosymbiont among insects. It can play a prominent role in the development, reproduction and immunity of its given insect host. To date, Wolbachia presence is well studied within aphids, whiteflies and planthoppers, but relatively few studies have investigated its presence in psyllids. Methods: Here, the infection status of Wolbachia in five species of psyllid, including Asian citrus psyllid Diaphorina citri and longan psyllid Cornegenapsylla sinica was investigated. The phylogenetic relationships of different Wolbachia lines and their infection density and patterns in D. citri and C. sinica from different countries was also examined. Results: The infection rates of Wolbachia in D. citri and C. sinica were both 100%, and their sequencing types are ST173 and ST532 respectively. Phylogenetic analysis revealed that the Wolbachia lines in D. citri and C. sinica both belong to the Con subgroup of Wolbachia supergroup B. In addition, Wolbachia displayed a scattered localization pattern in the 5th instar nymphs and in the reproductive organs of both D. citri and C. sinica but differed in other tissues; it was highest in the midgut, lowest in the salivary glands and medium in both the testes and ovaries. Conclusion: Our findings assist in further understanding the coevolution of Wolbachia and its psyllid hosts. Given that Wolbachia could play an important role in insect pest control and pathogen transmission inhibition, our findings may also provide new insights for development of control strategies for D. citri and C. sinica.

Silencing of V-ATPase-E gene causes midgut apoptosis of Diaphorina citri and affects its acquisition of Huanglongbing pathogen.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is among the most important pests of citrus. It is the main vector of the Huanglongbing (HLB) pathogen Candidatus Liberibacter asiaticus (CLas), which causes severe losses in citrus crops. Control of D. citri is therefore of paramount importance to reduce the spread of HLB. In this regard, using RNA interference (RNAi) to silence target genes is a useful strategy to control psyllids. In this study, using RNAi, we examined the biological functions of the V-ATPase subunit E (V-ATP-E) gene of D. citri, including its effect on acquisition of CLas. The amino acid sequence of V-ATP-E from D. citri had high homology with proteins from other insects. V-ATP-E was expressed at all D. citri life stages analyzed, and the expression level in mature adults was higher than that of teneral adults. Silencing of V-ATP-E resulted in a significant increase in mortality, reduced body weight, and induced cell apoptosis of the D. citri midgut. The reduced expression of V-ATP-E was indicated to inhibit CLas passing through the midgut and into the hemolymph, leading to a majority of CLas being confined to the midgut. In addition, double-stranded RNA of D. citri V-ATP-E was safe to non-target parasitic wasps. These results suggest that V-ATP-E is an effective RNAi target that can be used in D. citri control to block CLas infection.

Prediction of Droplet Sliding on the Continuity of the Three-Phase Contact Line.

Many animals and plants have evolved wonderful hydrophobic abilities to adapt to the complex climate environment. The microstructure design of a superhydrophobic surface focuses on bionics and will be restricted by processing technology. Although certain functions can be achieved, there is a lack of unified conclusion on the wetting mechanism and a few quantitative analyses of the continuity of the three-phase contact line. Therefore, the relationship between the surface microstructure of the lattice pattern and the critical sliding angle of the water droplet in the Cassie state was investigated in this paper, and we proposed a method to quantitatively analyze the continuity of the three-phase contact line by a dimensionless length f. The results showed that the three-phase contact line was an important factor to determine the sliding performance of the droplet. The upward traction force generated by the surface tension through the force analysis on the three-phase contact line can enhance the sliding ability of the droplet on the solid surface. There was a good negative linear correlation between the critical sliding angle and dimensionless length, which provided a guiding basis for the optimal design of superhydrophobic surfaces.

Exploring Contact Angle Hysteresis Behavior of Droplets on the Surface Microstructure.

It is confirmed that surfaces with specific microstructures could exhibit good superhydrophobic properties, and there are also a lot of conclusions about droplet hysteresis behavior. However, most of the research methods are based on two-dimensional ideal model and experimental observation at the macroscale. Further research needs to be conducted about the hysteresis behavior of droplets on the microstructure surface under three-dimensional conditions. In this paper, the influence of curvature variation of the liquid surface between pillars on the contact angle hysteresis (CAH) has been investigated. The simulation results were in good agreement with the experimental measurements. Analyses were conducted on the morphology change and force of the liquid surface between pillars, and an index was proposed to describe the degree of difficulty of liquid surface movement. It was revealed that a change in the direction of the surface tension at the three-phase interface caused by curvature variation of the liquid surface between pillars played an important role in the movement of the liquid surface. The greater the surface tension component in the normal direction of the liquid surface, the more likely it was for the liquid surface to advance or recede. The local curvature of the liquid surface increased or the angles between the pillars increased, and the effect of the CAH would be weakened.

[Isolation and characterization of two marine algicidal bacteria against the Phaeocystis globosa].

The algae-lysis bacteria Y01 and Y04 were isolated from seawater, during a red tide survey of the Zhuhai Estuary in southern China. The algae-lysis bacteria Y01 and Y04 were Gram-positive bacteria which can remove P. globosa in 6 days. The lysing process was observed by microscope and SEM, both of them could directly lyse P. globosa. The strains were identified by the sequence analysis of 16S rDNA. The length of the two bacteria's sequences were 1 468 bp and 1 548 bp (strain Y01: DQ531607; strain Y04: DQ531608). The DNA sequence similarity searches showed that share more than 99.7% sequence homology with some strain of Bacillus. The algae-lysing bacteria would provide a possibility to control P. globosa red-tide by microbial agents.