Transmission Electron Microscopic Morphological Study and Flow Cytometric Viability Assessment of Acinetobacter baumannii

Multidrug-resistant (MDR) Acinetobacter baumannii infections are difficult to treat owing to the extremely limited armamentarium. Expectations about antimicrobial peptides' use as new powerful antibacterial agents have been raised on the basis of their unique mechanism of action. Musca domestica cecropin (Mdc), a novel antimicrobial peptide from the larvae of Housefly (Musca domestica), has potently active against Gram-positive and Gram-negative bacteria standard strain. Here we evaluated the antibacterial activity of Mdc against clinical isolates of MDR-A. baumannii and elucidate the related antibacterial mechanisms. The minimal inhibitory concentration (MIC) of Mdc was 4 μg/mL. Bactericidal kinetics of Mdc revealed rapid killing of A. baumannii (30 min). Flow cytometry using viability stain demonstrated that Mdc causes A. baumannii membrane permeabilization in a concentration- and time-dependent process, which correlates with the bactericidal action. Moreover, transmission electron microscopic (TEM) examination showed that Mdc is capable of disrupting the membrane of bacterial cells, resulting in efflux of essential cytoplasmic components. Overall, Mdc could be a promising antibacterial agent for MDR-A. baumannii infections

Evolution mechanism of principal modes in climate dynamics

Eigen analysis has been a powerful tool to distinguish multiple processes into different simple principal modes in complex systems. For a non-equilibrium system, the principal modes corresponding to the non-equilibrium processes are usually evolving with time. Here, we apply the eigen analysis into the complex climate systems. In particular, based on the daily surface air temperature in the tropics (30? S–30? N, 0? E–360? E) between 1979-01-01 and 2016-12-31, we uncover that the strength of two dominated intra-annual principal modes represented by the eigenvalues significantly changes with the El Niño/southern oscillation from year to year. Specifically, according to the ‘regional correlation’ introduced for the first intra-annual principal mode, we find that a sharp positive peak of the correlation between the El Niño region and the northern (southern) hemisphere usually signals the beginning (end) of the El Niño. We discuss the underlying physical mechanism and suppose that the evolution of the first intra-annual principal mode is related to the meridional circulations; the evolution of the second intra-annual principal mode responds positively to the Walker circulation. Our framework presented here not only facilitates the understanding of climate systems but also can potentially be used to study the dynamical evolution of other natural or engineering complex systems. © 2020 The Author(s)

Deformation Analysis and Fixture Design of Thin-walled Cylinder in Drilling Process Based on TRIZ Theory

Thin-walled cylindrical workpiece is easy to deform during machining and clamping processes due to the insufficient rigidi. Moreover, it’s also difficult to ensure the perpendicularity of flange holes during drilling process. In this paper, the element birth and death technique is used to obtain the axial deformation of the hole through finite element simulation. The measured value of the perpendicularity of the hole was compared with the simulated value to verify then the rationality of the simulation model. To reduce the perpendicularity error of the hole in the drilling process, the theory of inventive principle solution (TRIZ) was used to analyze the drilling process of thin-walled cylinder, and the corresponding fixture was developed to adjust the supporting surface height adaptively. Three different fixture supporting layout schemes were used for numerical simulation of drilling process, and the maximum, average and standard deviation of the axial deformation of the flange holes and their maximum hole perpendicularity errors were comparatively analyzed, and the optimal arrangement was optimized. The results show that the proposed deformation control strategy can effectively improve the drilling deformation of thin-walled cylindrical workpiece, thereby significantly improving the machining quality of the parts

BAG Family Gene and Its Relationship with Lung Adenocarcinoma Susceptibility

Background and objective BAG genes (Bcl-2-associated athanogene) belong to a recently discovered multifunctional anti-apoptosis gene family that regulate various physiological processes which include apoptosis, tumorigenesis, neural differentiation, stress response and cell cycle and so on. The expression status of BAG family genes are related to certain tumor incidence and prognosis. The aim of this study is to explore the association of the BAG family gene expression status with the susceptibility of lung adenocarcinoma. Methods The gene expression data of BAG family genes from 29 cases of lung adenocarcinoma tissues and matched pericancerous lung tissess were generated by microarray chips. Cox regression was used to analyze the association between the expression of BAG family genes and the susceptibility of lung adenocarcinoma and the results were verified by GEO database. Results The expression levels of BAG-1, BAG-2, BAG-5 in cancer tissues were significantly downregulated compared with matched pericancerous lung tissues and were protective factors of lung adenocarcinoma (P < 0.05, OR < 1); while the expression level of BAG-4 in cancer tissues were remankably upregulated compared with the matched pericancerous lung tissues and was risk factor of lung adenocarcinoma (P < 0.05, OR > 1). Conclusion BAG-1, BAG-2, BAG-5 might be the potential protective factors while BAG-4 is possible risk factor of lung adenocarcinoma

Ubiquitous short-range order in multi-principal element alloys

Recent research in multi-principal element alloys (MPEAs) has increasingly focused on the exploration and exploitation of short-range order (SRO) to enhance material performance. However, the understanding of SRO formation and the precise tuning of it within MPEAs remains poorly understood, limiting the comprehension of its impact on material properties and impeding the advancement of SRO engineering. Here, leveraging advanced additive manufacturing techniques that produce samples with a wide range of cooling rates (up to 10^7 K/s) and an improved quantitative electron microscopy method, we characterize SRO in three CoCrNi-based MPEAs to unravel the role of processing route and thermal history on SRO. Surprisingly, irrespective of the processing and thermal treatment applied, all samples exhibit similar levels of SRO, suggesting that prevalent SRO may form during the solidification process. Atomistic simulations of solidification verify that local chemical ordering arises in the liquid-solid interface (solidification front) even under the extreme cooling rate of 10^11 K/s. This phenomenon stems from the swift atomic diffusion in the supercooled liquid, which matches or even surpasses the rate of solidification. Therefore, SRO is an inherent characteristic of most MPEAs, insensitive to variations in cooling rates and annealing treatments typically available in experiments. Integrating thermal treatment with other strategies, such as mechanical deformation and irradiation, might be more effective approaches for harnessing SRO to achieve controlled material properties.Comment: 27 pages, 5 figure