Porcine β-defensin 2 (pBD2), a recently discovered porcine defensin that is produced by the intestine, exerts antimicrobial activities and innate immune effects that are linked to intestinal diseases in pigs. Here, we report a codon-optimised protein corresponding to mature pBD2 cDNA that was expressed and purified in Pichia pastoris yeast. The highest amount of secreted protein (3,694.0 mg/L) was reached 144 h into a 150-h induction during high-density cultivation. Precipitation followed by gel exclusion chromatography yielded 383.7 mg/L purified recombinant pBD2 (rpBD2) with a purity of ~93.7 %. Two recombinant proteins of 5,458.5 and 5,258.4 Da were detected in the mass spectrum due to variation in the amino-terminus. The rpBD2 exhibited high antimicrobial activity against a broad range of pig pathogenic bacteria (minimal inhibitory concentration [MIC] 32-128 μg/mL); the highest activity was observed against Salmonella choleraesuis, Staphylococcus aureus and Streptococcus suis (MIC 32-64 μg/mL). However, rpBD2 also inhibited the growth of probiotics such as Lactobacillus plantarum, Bacillus subtilis and Saccharomyces cerevisiae, but at lower efficacies than the pathogens. Purified or unpurified rpBD2 also maintained high activity over a wide range of pH values (2.0-10.0), a high thermal stability at 100 °C for 40 min and significant resistance to papain, pepsin and trypsin. In addition, the activity of rpBD2 towards S. aureus was unaffected by 10 mM dithiothreitol (DTT) and 20 % dimethyl sulphoxide (DMSO). Our results suggest that pBD2 could be produced efficiently in large quantities in P. pastoris and be a substitute for traditional antibiotics for growth promotion in the porcine industry.

Long‐term chemical and mechanical stability of gaskets in proton‐exchange membrane (PEM) fuel cells is critical to the sealing and normal operation of these fuel cells. In this study, the chemical and mechanical degradation of a silicone rubber was investigated. Two compression loads and two simulated environments were used. The weight change of sample was monitored. Optical microscopy was applied to observe the morphological changes on the specimen surface. Attenuated total reflection (ATR)–Fourier transform infrared (FTIR) spectroscopy and X‐ray photoelectron spectroscopy (XPS) were used to investigate the chemical changes on the surface of specimens after exposure to the simulated solutions and subjection to compression loads over time. A compression stress‐relaxation test was used to elucidate the stress‐relaxation property changes of the specimens after exposure to the simulated fuel‐cell environments and the compression loads. Optical microscopy showed that the surface morphology of the specimens changed from initially smooth to slightly rough followed by crack initiation and finally propagation. The ATR–FTIR and XPS results indicate that the surface chemistry of the specimens significantly changed via decrosslinking and chain scission after exposure to the simulated environments and compression loads over time. The compression stress‐relaxation test results indicate that the mechanical properties of the silicone rubber specimens changed significantly. We found that both the acid concentration of the test solution and the compression load significantly affected the degradation of the silicone rubber material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47855.

Synthetic aperture radar (SAR) tomography (TomoSAR) is able to separate multiple scatterers layovered inside the same resolution cell in high-resolution SAR images of urban scenarios, usually with a large number of orbits, making it an expensive and unfeasible task for many practical applications. Targeting at finding out the minimum number of images necessary for tomographic reconstruction, this paper innovatively applies minimum redundancy array (MRA) for tomographic baseline array optimization. Monte Carlo simulations are conducted by means of Two-step Iterative Shrinkage/Thresholding (TWIST) and Truncated Singular Value Decomposition (TSVD) to fully evaluate the tomographic performance of MRA orbits in terms of detection rates, Cramer Rao Lower Bounds, as well as resistance against sidelobes. Experiments on COSMO-SkyMed and TerraSAR-X/TanDEM-X data are also conducted in this paper. The results from simulations and experiments on real data have both demonstrated that introducing MRA for baseline optimization in SAR tomography can benefit from the dramatic reduction of necessary orbit numbers, if the recently proposed TWIST method is used for tomographic reconstruction. Although the simulation and experiments in this manuscript are carried out using spaceborne data, the outcome of this paper can also give examples for airborne TomoSAR when designing flight orbits using airborne sensors.

Due to the intrinsic side-looking geometry of synthetic aperture radar (SAR), time series interferometric SAR is only able to monitor displacements in line-of-sight (LOS) direction, which limits the accuracy of displacement measurement in landslide monitoring. This is because the LOS displacement is only a three dimensional projection of real displacement of a certain ground object. Targeting at this problem, a precise digital elevation model (DEM) assisted slope displacement retrieval method is proposed and applied to a case study over the high and steep slope of the Dagushan open pit mine. In the case study, the precise DEM generated by laser scanning is first used to minimize topographic residuals in small baseline subsets analysis. Then, the LOS displacements are converted to slope direction with assistance of the precise DEM. By comparing with ground measurements, relative root mean square errors (RMSE) of the estimated slope displacements reach approximately 12–13% for the ascending orbit, and 5.4–9.2% for the descending orbit in our study area. In order to validate the experimental results, comparison with microseism monitoring results is also conducted. Moreover, both results have found that the largest slope displacements occur on the slope part, with elevations varying from −138 m to −210 m, which corresponds to the landslide area. Moreover, there is a certain correlation with precipitation, as revealed by the displacement time series. The outcome of this article shows that rock mass structure, lithology, and precipitation are main factors affecting the stability of high and steep mining slopes.

As age-related diseases escalate, deciphering molecular mechanism of immune aging is vital. T cells, crucial in adaptive immunity, undergo aging-related transformations in quantity and quality. The interconnection between aging and alternative splicing of gene expression in different T cell subtype is still unclear. Thus, we examined age-related gene alternative splicing in numerous immune cell subgroups, constructing an aging-associated atlas for alternative splicing across human T cell subtypes. Our study identified numerous age-related alternative splicing events in genes linked to T cell activation, differentiation, migration, and apoptosis. Genes like PDCD4 and ARCN1 with age group-specific alternative splicing events and implicated in T cell aging hint at potential therapeutic targets for immune aging. Overall, our findings present a comprehensive alternative splicing atlas for healthy aging-related molecular programs, introducing fresh perspectives for T cell transformation regulation during aging, and inspiring new approaches for novel T cell aging intervention molecules and methods.