Acoustic emission and fractal characteristics of red beds soft rock under water-force coupling.

Groundwater has a significant influence on the mechanical properties of surrounding rock. Aiming at the large deformation of surrounding rock of red layer soft rock tunnel affected by groundwater, the uniaxial graded loading tests were carried out on red beds soft rock with different water content. The failure process of the specimen was monitored by acoustic emission (AE) and the crack evolution law was analyzed, and the scanning electron microscopy (SEM) was used to compare the microstructure of the specimens before and after immersion. Combined with fractal theory, the monofractal and multifractal characteristics of AE ringing count during the loading process of red beds soft rock were analyzed. The results show that, with the gradual increase of water content, the AE ringing count before the yield stage gradually decreased, and the corresponding cumulative ringing count at the same time gradually decreased, and the decrease was large in the early stage of immersion, and decreased in the later stage. The cumulative ringing curve gradually slowed down, the internal crack appeared earlier, the cumulative ringing curve stepped significantly, the AE signal amplitude gradually weakened, and the bandwidth of each frequency band gradually decreased. The failure of red beds soft rock with different water content is dominated by shear crack, and with the gradual increase of water content, the proportion of shear crack increases gradually, and the AE b value decreases gradually. With the gradual increase of the relative peak strength, the correlation dimension D of red beds soft rock with different water content increases first and then decreases. At 80% of the relative peak strength, the correlation dimension D reaches its maximum value and then drops sharply until it is maintained at a relatively low level, and the correlation dimension D gradually decreases with the water content. The fitting correlation coefficients of different water content (lnC(r), lnr) are all above 0.9, indicating that the AE ringing count of water-bearing red beds soft rock has fractal characteristics, and the higher the correlation coefficient, the higher the self-similarity of AE ringing count sequence. As the weight q gradually increases, the generalized fractal dimension D(q) gradually decreases. When q ≠ 0, under the condition of the same q, D(q) presents a trend of first increasing and then decreasing. The multifractal characteristics of AE ringing count of red beds soft rock with different water content is inverted 'U' shape. From the natural state to immerse 1 d, the ∆α gradually increases, and from 1 to 7 d, the ∆α gradually decreases, where Δα = αmax - αmin represents the spectral width of the multifractal spectrum. When saturation is not reached, ∆f < 0 indicates that the number of cracks in the specimen is small, when saturation is reached, ∆f > 0 indicates that a large number of cracks are generated inside the specimen and macro cracks are formed, where Δf = f (αmax) - f (αmin) represents the frequency relationship between different signals of different sizes. This research can provide a reliable theoretical basis for the construction and maintenance of large deformation of water-rich soft rock tunnel excavation, and have certain engineering significance.

Enhancing the biosynthesis of nicotinamide mononucleotide in Lactococcus lactis by heterologous expression of FtnadE.

BACKGROUND: Nicotinamide mononucleotide (NMN), a key intermediate of nicotinamide adenine dinucleotide, plays an important in anti-aging and disease. Lactococcus lactis, an important probiotic lactic acid bacteria (LAB), has shown great potential for the biosynthesis of NMN, which will significantly affect the probiotic effects of the dairy products. RESULTS: We used the CRISPR/nCas9 technique to knockout nadR gene of L. lactis NZ9000 to enhance the accumulation of NMN by 61%. The nadE* gene from Francisella tularensis with codon optimization was heterologous in L. lactis NZ9000ΔnadR and has a positive effect on NMN production. Combined with optimization of the concentration of substrate nicotinamide, a final intracellular NMN titer was 2289 µmol L-1  mg-1 with 10 g L-1 nicotinamide supplement, which was 5.7-fold higher than that of the control. The transcription levels of key genes (pncA, nadD and prs1) involved in NMN biosynthesis were up-regulated by more than two-fold, indicating that the increase of NMN titer was attributed to FtnadE* heterologous expression. CONCLUSION: Our study provides a better understanding of the NMN biosynthesis pathway in L. lactis, and can facilitate NMN production in LAB via synthetic biology approaches. © 2022 Society of Chemical Industry.

Fast and high-accuracy measurement of particle size and location from a linear interferogram.

In this paper, we propose, to the best of our knowledge, a novel method of simultaneously detecting and evaluating the location and size of particles from a compression particle interferogram. The 2D position of the particle can be determined with high accuracy, as evaluated by the unidirectional gradient-match with the conjoint to centroid method. The fast-Rife method provides sub-pixel accuracy and high speed for estimating the fringe frequency from the Fourier spectrum of a particle interferogram. The capability mentioned above is well verified using synthetic and experimental data. The computational load falls almost 50%, and the relative error of the measured particle diameter is less than 1.12% for homogeneous solutions of polystyrene spheres of 50 µm and 70 µm. The results demonstrate that the method presented here is considerably promising for its application to a high-density particle field, such as spray, in accurately measuring both the particle size and its location.

Emerging prospects of protein/peptide-based nanoassemblies for drug delivery and vaccine development.

Proteins have been widely used in the biomedical field because of their well-defined architecture, accurate molecular weight, excellent biocompatibility and biodegradability, and easy-to-functionalization. Inspired by the wisdom of nature, increasing proteins/peptides that possess self-assembling capabilities have been explored and designed to generate nanoassemblies with unique structure and function, including spatially organized conformation, passive and active targeting, stimuli-responsiveness, and high stability. These characteristics make protein/peptide-based nanoassembly an ideal platform for drug delivery and vaccine development. In this review, we focus on recent advances in subsistent protein/peptide-based nanoassemblies, including protein nanocages, virus-like particles, self-assemblable natural proteins, and self-assemblable artificial peptides. The origin and characteristics of various protein/peptide-based assemblies and their applications in drug delivery and vaccine development are summarized. In the end, the prospects and challenges are discussed for the further development of protein/peptide-based nanoassemblies.

A blend hydrogel based on polyoxometalate for long-term and repeatedly localized antibacterial application study.

Herein, a polyoxometalate (POM)-based blend hydrogel system was in situ constructed by incorporating cetyltrimethylammoniumbromide (CTAB)-encapsulated POM cationic micelles to bare hydrogel matrixes followed by copolymerization of multivalent crosslinking groups. It was demonstrated that the fabricated blend hydrogel possessed tunable physicochemical properties, good swelling behavior (maximum swelling rate of 229% in buffer solution of pH 8.0), excellent local action and sustained release of POM component (release ratio achieved nearly 100% at the time of 120 min). Antibacterial activity study revealed that the introduction of POM greatly improved the bioavailability of itself, namely, leading to a more effective enhancement of therapeutic effects (survival ratio of both strains less than 5%). Besides, bactericidal rates (ca. 51%) were achieved even after six runs repeated, thereby verifying the biological application potential of this material. Finally, the practical application potentials were investigated and future prospects in relevant research areas were forecasted.

Involvement of GLWamide neuropeptides in polyp contraction of the adult stony coral Euphyllia ancora.

The existence and function of neurons remain largely unexplored in scleractinian corals. To gain a better understanding of neuronal functions in coral physiology, this study focused on Glycine-Leucine-Tryptophan-amide family neuropeptides (GLWamides), which have been shown to induce muscle contraction and larval metamorphosis in other cnidarians. Molecular identification and functional characterization of GLWamides in the adult stony coral Euphyllia ancora were performed. We successfully elucidated the full-length cDNA of GLWamide preprohormone in E. ancora (named EaGLW preprohormone). The deduced amino acid sequence was predicted to contain six potential GLWamide peptides. Tissue distribution analysis demonstrated that transcripts of EaGLW preprohormone were mainly expressed in the mouth (including the pharynx) and tentacles of the polyps. Immunodetection with an anti-GLWamide monoclonal antibody revealed that GLWamide neurons were mainly distributed in the epidermis of the mouth region and tentacle, in agreement with the distribution patterns of the transcripts. Treatment of the isolated mouth and tentacles with synthetic GLWamide peptides induced the contraction of these isolated tissues. Treatment of polyps with synthetic GLWamide peptides induced the contraction of polyps. These results suggest that GLWamides are involved in polyp contraction (myoactivity) in adult scleractinians. Our data provide new information on the physiological function of neuropeptides in scleractinians.

Optimization of defined medium for recombinant Komagataella phaffii expressing cyclodextrin glycosyltransferase.

The cyclodextrin glycosyltransferase (CGTase) is an important enzyme for cyclodextrin (CD) production, and is also widely used in the biotechnology, food, and pharmaceuticals industries. Secretory CGTase production by recombinant Komagataella phaffii using defined medium is a promising approach because of low cost, less impurity protein. It was found that no CGTase was expressed using traditional defined medium (basal salt medium [BSM]) because of pH value decreasing significantly. CGTase was expressed by recombinant K. phaffii through pH maintenance in range of 5.5-7.0. ß-CGTase activity increased to 122.0 U/mL after optimization of glycerol, phosphate buffer, pH value, ammonium sulfate, temperature, methanol, and additives based on BSM, establishing a modified defined medium. These results showed that it was necessary to establish recombinant K. phaffii-based special defined medium although the same host cell used for different heterologous protein expression.

Phenylquinoline transient receptor potential vanilloid 1 antagonists for the treatment of pain: Discovery of 1-(2-phenylquinoline-4-carbonyl)-N-(4-(trifluoromethyl)phenyl)pyrrolidine-3-carboxamide.

Reported herein is the design, synthesis, and pharmacologic characterization of a class of TRPV1 antagonists constructed on a phenylquinoline platform that evolved from Cinchophen lead. This design composes three sections: a phenylquinoline headgroup attached to an aliphatic carboxamides, which is tethered at a phenyl tail group. Optimization of this design led to the identification of 37, comprising a pyrrolidine linker and a trifluoromethyl-phenyl tail. In the TRPV1 functional assay, using cells expressed hTRPV1, 37 antagonized capsaicin-induced Ca2+ influx, with an IC50 value of 10.2 nM. In the complete mice analgesic model, 37 exhibited better antinociceptive activity than the positive control BCTC in diverse pain models. All of these results suggested that 37 could be considered as a lead candidate for the further development of antinociceptive drugs.

Energy Charge as an Indicator of Pexophagy in Pichia pastoris.

Pichia pastoris is a good model for pexophagy research owing to its diverse pexophagy modes (macropexophagy and micropexophagy) exhibited during carbon-source shift from methanol to other carbon sources. The critical condition that triggers activation of macropexophagy and micropexophagy is important for clarifying the P. pastoris pexophagy mechanism and human peroxisomal disorders. In this study, the pexophagy modes of P. pastoris were confirmed by green fluorescent protein expression and alcohol oxidase and formate dehydrogenase activities. Furthermore, intracellular energy charge (EC) was found to be a determinant of pexophagy activation. During methanol induction, the EC was about 0.5. And the final EC value was related to the pexophagy mode when carbon source switched from methanol to others. Macropexophagy and micropexophagy occurred when the EC increased to 0.6-0.75 and above 0.75, respectively. Thus, different EC values were considered as the important factor to trigger different pexophagy modes in P. pastoris. The results obtained in this study could help in achieving better control of the pexophagy modes to study the pexophagy mechanism.