Propagation dynamics of the controllable circular Airyprime beam in the Kerr medium.

In this paper, we study the propagation dynamics of the circular Airyprime beam (CAPB) in the Kerr medium for the first time. We investigate the effects of the astigmatism factor, the chirp factor, and vortices on the CAPB propagating in the Kerr medium. At the same time, we are also introducing a special-shaped Airyprime beam (SAPB) during its propagation. The transmission characteristics of the CAPB and the SAPB in the Kerr medium are compared under identical conditions. Our theoretical results provide additional possibilities for CAPB modulation in the Kerr medium, thereby promising wider applicability of CAPB in various research areas.

Identification of ireA, 0007, 0008, and 2235 as TonB-dependent receptors in the avian pathogenic Escherichia coli strain DE205B.

Avian pathogenic Escherichia coli (APEC), a pathotype of extraintestinal pathogenic E. coli, causes one of the most serious infectious diseases of poultry and shares some common virulence genes with neonatal meningitis-associated E. coli. TonB-dependent receptors (TBDRs) are ubiquitous outer membrane ß-barrel proteins; they play an important role in the recognition of siderophores during iron uptake. Here, in the APEC strain DE205B, we investigated the role of four putative TBDRs-ireA, 0007, 0008, and 2235-in iron uptake. Glutathione-S-transferase pulldown assays indicated that the proteins encoded by these genes directly interact with TonB. Moreover, the expression levels of all four genes were significantly upregulated under iron-depleted conditions compared with iron-rich conditions. The expression levels of several iron uptake-related genes were significantly increased in the ireA, 0007, 0008, and 2235 deletion strains, with the upregulation being the most prominent in the ireA deletion mutant. Furthermore, iron uptake by the ireA deletion strain was significantly increased compared to that by the wild-type strain. Moreover, a tonB mutant strain was constructed to study the effect of tonB deletion on the TBDRs. We found that regardless of the presence of tonB, the expression levels of the genes encoding the four TBDRs were regulated by fur. In conclusion, our findings indicated that ireA, 0007, 0008, and 2235 indeed encode TBDRs, with ireA having the most important role in iron uptake. These results should help future studies explore the mechanisms underlying the TonB-dependent iron uptake pathway.

Detection of mcr-1 Gene among Escherichia coli Isolates from Farmed Fish and Characterization of mcr-1-Bearing IncP Plasmids.

The presence of the mcr-1 gene in Escherichia coli isolated from retail freshwater fish was investigated. Seven (3.65%) clonally unrelated original E. coli isolates from grass carp were positive for mcr-1 The mcr-1 genes were encoded by either chromosomes (n = 2) or conjugative plasmids (2 IncI2, 2 IncP, and 1 IncX4). The IncP plasmids were similar to other mcr-1-harboring IncP plasmids from China, though the insertion sites varied. Our report warrants further surveillance of resistance genes in aquaculture.

Designation and characterization of cold-set egg white protein/dextran sulfate hydrogel for curcumin entrapment.

This study aimed to design a cold-set hydrogel of egg white protein (EWP) with good mechanical properties for encapsulating curcumin. Dextran sulfate (DS) and transglutaminase (TGase) were used to control the aggregation and gelation behavior of EWP at preheating step and gelation step, respectively. The optimum soluble protein aggregate size was obtained in the EWP/DS mixture at a mass ratio of 10 under 85 °C preheated (HED10). The presence of TGase further enhanced the cross-linking degree between protein aggregates during the gelation step. The highest gel hardness was found in HED10 hydrogel with TGase, which is almost 10 times the pure EWP gel. Besides, the HED hydrogels effectively slowed down the release rate of curcumin in gastrointestinal digestion. This work provides a theoretical basis for the development of cold-set EWP hydrogel with good mechanical strength by sulfated polysaccharide addition and TGase cross-linking as encapsulation delivery systems.

The level of sulfate substitution of polysaccharide regulates thermal-induced egg white protein gel properties: The characterization of gel structure and intermolecular forces.

Sulfated polysaccharides exhibit great potential for regulating protein-protein interactions. In the present study, three sulfated microcrystalline cellulose (MCS) with different degrees of sulfate substitution (DSS: 0.33, 0.51, 0.61) were synthesized and the effects of DSS on the regulation of egg white protein (EWP) aggregation and gelation properties were investigated. The results found that the improvement of protein mechanical properties by MCS is closely related to the level of sulfate substitution. The higher the DSS, the more ordered protein aggregates and compact gel network formed during heating as compared to that of pure EWP. Lower DSS (0.33) shows little effect on the mechanical properties of EWP. Furthermore, all the MCSs could significantly destroy the tertiary structure of protein molecules during heating, while for the secondary structure, MCS with higher DSS (0.51 and 0.61) could effectively control the decreasing tendency of α-helix and increasing tendency of ß-sheet. Hydrophobic interactions were recognized as the major intermolecular force in the compact mixed gels (EWP/MCS2 and EWP/MCS3 gels, DSS was 0.51 and 0.61, respectively). These findings provide a vital understanding of the gelling mechanism of the protein-polysaccharide system and the application of sulfated polysaccharides in protein-based food products.

Uncertainties of soil organic carbon stock estimation caused by paleoclimate and human footprint on the Qinghai Plateau.

BACKGROUND: Quantifying the stock of soil organic carbon (SOC) and evaluating its potential impact factors is important to evaluating global climate change. Human disturbances and past climate are known to influence the rates of carbon fixation, soil physiochemical properties, soil microbial diversity and plant functional traits, which ultimately affect the current SOC storage. However, whether and how the paleoclimate and human disturbances affect the distribution of SOC storage on the high-altitude Tibetan Plateau remain largely unknown. Here, we took the Qinghai Plateau, the main component of the Tibetan Plateau, as our study region and applied three machine learning models (random forest, gradient boosting machine and support vector machine) to estimate the spatial and vertical distributions of the SOC stock and then evaluated the effects of the paleoclimate during the Last Glacial Maximum and the mid-Holocene periods as well as the human footprint on SOC stock at 0 to 200 cm depth by synthesizing 827 soil observations and 71 environmental factors. RESULTS: Our results indicate that the vegetation and modern climate are the determinant factors of SOC stocks, while paleoclimate (i.e., paleotemperature and paleoprecipitation) is more important than modern temperature, modern precipitation and the human footprint in shaping current SOC stock distributions. Specifically, the SOC stock was deeply underestimated in near natural ecosystems and overestimated in the strongly human disturbance ecosystems if the model did not consider the paleoclimate. Overall, the total SOC stock of the Qinghai Plateau was underestimated by 4.69%, 12.25% and 6.67% at depths of 0 to 100 cm, 100 to 200 cm and 0 to 200 cm, respectively. In addition, the human footprint had a weak influence on the distributions of the SOC stock. We finally estimated that the total and mean SOC stock at 200 cm depth by including the paleoclimate effects was 11.36 Pg C and 16.31 kg C m-2, respectively, and nearly 40% SOC was distributed in the top 30 cm. CONCLUSION: The paleoclimate is relatively important for the accurate modeling of current SOC stocks. Overall, our study provides a benchmark for predicting SOC stock patterns at depth and emphasizes that terrestrial carbon cycle models should incorporate information on how the paleoclimate has influenced SOC stocks.