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In the present study, we extensively explored the high-pressure behaviors and vibrational properties of amblygonite LiAlPO4F with elevated pressures up to 34.3 GPa based on single-crystal X-ray diffraction measurements, Raman spectroscopy, and DFT calculations. The compressibility and elastic properties of amblygonite were determined first. Specifically, the obtained isothermal bulk modulus of LiAlPO4F is 128(4) GPa and the triclinic phase exhibited anisotropic compression with axial compressibility βc > βa > βb with a ratio of 1.11:1.00:1.20. The Raman spectra showed no indication of phase transformation and were used to obtained mode Grüneisen parameters. The average Grüneisen parameter for PO4 tetrahedral sites was smaller than for the LiO4F sites. Our results provide new insights into the phase stability and elastic properties of lithium-fluorite granites at extreme conditions.

The common material of bearing rings is GCr15 bearing steel which is a typical difficult-to-machine material. As an important working surface of the bearing, the inner surface of the raceway plays a vital role in the performance of the bearing. As an important means to solve the high-performance manufacturing of difficult-to-machine materials, longitudinal–torsional ultrasonic processing is widely used in various types of processing. In the presented work, the basic size of the horn is obtained from the wave equation of the forced vibration, and the modal analysis and amplitude test are carried out to verify the rationality of the LUTG structure. Then, according to the probability density function of cutting thickness and the overlapping effect of adjacent abrasive trajectories, the LUTG surface topography prediction model is established by using the height formula of the surface residual material, and the model reliability is verified by using the orthogonal test. The error between the test results and the prediction model is within 13.2%. Finally, based on the response surface method, the optimal process parameters that can meet the requirements of low roughness (Ra) and high material removal rate (MRR) are screened, and the optimal combination of process parameters is obtained as follows: A = 4.5 μm, n = 6493.3 r/min, ap = 28.4 μm, and vf = 21.1 mm/min.

Sub-seafloor sediment is the largest microbial habitat on Earth. The study of microbes in sub-seafloor sediment is largely limited by the technical challenge of acquiring ambient microbial DNA because of sediment heterogeneity. Changes in the extraction method, even just by one step, can affect the extraction yields for complicated sediment samples. In this work, sub-seafloor sediment samples from the Baltic Sea with high organic carbon content were used to evaluate the influence of different grinding beads on DNA extraction. We found that the grinding beads can affect the DNA extraction from the organic-matter- and biosiliceous-clay-rich samples. A mixture of 0.5-mm and 0.1-mm grinding beads exhibited higher DNA yields and recovered more unique taxa than other bead combinations, such as Stenotrophomonas from Gammaproteobacteria and Leptotrichia from Fusobacteria; therefore, these beads are more suitable than the others for DNA extraction from the samples used in this study. This advantage might be magnified in samples with high biomass. On the contrary, the use of only small beads might lead to underestimation for certain Gram-positive strains. Overall, the discovery of abundant widespread deep biosphere clades in our samples indicated that our optimized DNA extraction method successfully recovered the in situ microbial community.

Programmed cell death (PCD) is the result of an intracellular program and is accomplished by a regulated process in both prokaryotic and eukaryotic organisms. Here, we report a programed cell death process in Mycobacterium smegmatis, an Actinobacteria species which involves a transcription factor and a DNase of the HNH family. We found that over-expression of an ArsR family member of the transcription factor, MSMEG_6762, leads to cell death. Transcriptome analysis revealed an increase in the genes’ transcripts involved in DNA repair and homologous recombination, and in three members of HNH family DNases. Knockout of one of the DNase genes, MSMEG_1275, alleviated cell death and its over-expression of programmed cell death. Purified MSMEG_1275 cleaved the M. smegmatis DNA at multiple sites. Overall, our results indicate that the MSMEG_6762 affects cell death and is mediated, at least partially, by activation of the HNH nuclease expression under a stress condition.