Isolation and purification of Tartary buckwheat polysaccharides and their effect on gut microbiota.

Tartary buckwheat (Fagopyrum tataricum) is rich in polysaccharides that can be utilized by the gut microbiota (GM) and provide several health benefits. However, the mechanisms underlying the action of these polysaccharides remain unclear to date. In this study, Tartary buckwheat polysaccharides (TBP) were purified, and five fractions were obtained. The composition of these fractions was determined using ion chromatography. Different TBP components were investigated regarding their probiotic effect on three species of Bifidobacteria and Lactobacillus rhamnosus. In addition, the effect of TBP on GM and short-chain fatty acids (SCFAs) was evaluated. Results showed that the probiotic effect of TBP fraction was dependent on their composition. The polysaccharides present in different fractions had specific probiotic effects. TBP-1.0, mainly composed of fucose, glucose, and d-galactose, exhibited the strongest proliferation effect on L. rhamnosus, while TBP-W, rich in glucose, d-galactose, and fructose, had the best promoting effect on Bifidobacterium longum and Bifidobacterium adolescentis growth. Furthermore, TBP-0.2, composed of d-galacturonic acid, d-galactose, xylose, and arabinose, exhibited its highest impact on Bifidobacterium breve growth. The composition of GM was significantly altered by adding TBP during fecal fermentation, with an increased relative abundance of Lactococcus, Phascolarctobacterium, Bacteroidetes, and Shigella. Simultaneously, the level of SCFA was also significantly increased by TBP. Our findings indicate that Tartary buckwheat can provide specific dietary polysaccharide sources to modulate and maintain GM diversity. They provide a basis for Tartary buckwheat commercial utilization for GM modulation.

Design of Concrete Mix Proportion Based on Particle Packing Voidage and Test Research on Compressive Strength and Elastic Modulus of Concrete.

According to the basic principle of dense packing of particles, and considering the interaction between particles, a dense packing model of granular materials in concrete was proposed. During the establishment of this model, binary particle packing tests of crushed stone and sand were carried out. The fitting analysis of the test results determines the relationship between the particle size ratio and the remaining volume fraction of the particle packing, and then the actual void fraction of the particle packing was obtained, based on which the water-binder ratio was combined to determine the amount of various materials in the concrete. The proposed concrete mix design method was used to prepare concrete, and its compressive strength and elastic modulus were tested experimentally. The test results show that the aggregate volume fraction of the prepared concrete increased, and the workability of the concrete mixture with the appropriate amount of water reducing agent meets the design requirements. When the water-binder ratio was 0.42, 0.47, or 0.52, the compressive strength of the concrete increased compared with the control concrete, and the degree of improvement in compressive strength increased with the decrease in water-binder ratio; when the water-binder ratio was 0.42, 0.47, or 0.52, the static elastic modulus of the concrete increased compared with the control concrete, and the degree of improvement in elastic modulus also increased with the decrease in water-binder ratio. The elastic modulus and compressive strength of the prepared concrete have a positive correlation. Findings show that the concrete mix design method proposed by this research is feasible and advanced in a sense.

Live-Cell Imaging of Neurotransmitter Release with a Cell-Surface-Anchored DNA-Nanoprism Fluorescent Sensor.

Neurotransmitters are essential chemical mediators for neuronal communication in variable neuromodulations. However, the progress of neuroscience is hampered by the shortage of suitable sensors to track neurotransmitters with high spatial and temporal resolution. Here, we introduce a self-assembled DNA-nanoprism fluorescent probe capable of nongenetically engineering the cell surface for ultrasensitive imaging of the neurotransmitter release at a single live-cell level. The DNA-nanoprism structure conjugated with three cholesterol tails enables the probe to rapidly and stably anchor on the cell surface within 10 min. The in situ detection of neurotransmitters is achieved by equipping the DNA-nanoprism with an aptamer-based "turn-on" fluorescent sensory module for the transmitter of interest. In a proof-of-concept study, we directly visualized the transient dopamine (DA) release on the cell surface with selective responsivity and high spatiotemporal precision and further explored the dynamic correlation between DA release and calcium influx triggered by high K+. This study provides a robust and sensitive tool for cell-surface-targeted imaging of neuromodulations, which might open up a new avenue to improve the understanding of neurochemistry and advance neuroscience research.