Probing eukaryotic cell mechanics via mesoscopic simulations

10.1371/journal.pcbi.1005726PLoS Computational Biology139e100572

More Precise Shaping of Guide Screws with Trapezoidal Thread

© 2020, Allerton Press, Inc. Abstract: How does the thread-cutter configuration with respect to the workpiece axis in roughing affect the shape precision of the external trapezoidal thread and the margin in final grinding? That question is investigated in the present work. An algorithm is outlined for determining the transverse profile of the helical channel in the external trapezoidal thread at the inner, central, and outer diameters. The channel profile calculated from that algorithm determines the cutting-edge profile at the front surface of a cutter positioned perpendicularly to the part’s helical surface for preliminary machining

Automated Microscopic Analysis of Metal Sulfide Colonization by Acidophilic Microorganisms.

Industrial biomining processes are currently focused on metal sulfides and their dissolution, which is catalyzed by acidophilic iron(II)- and/or sulfur-oxidizing microorganisms. Cell attachment on metal sulfides is important for this process. Biofilm formation is necessary for seeding and persistence of the active microbial community in industrial biomining heaps and tank reactors, and it enhances metal release. In this study, we used a method for direct quantification of the mineral-attached cell population on pyrite or chalcopyrite particles in bioleaching experiments by coupling high-throughput, automated epifluorescence microscopy imaging of mineral particles with algorithms for image analysis and cell quantification, thus avoiding human bias in cell counting. The method was validated by quantifying cell attachment on pyrite and chalcopyrite surfaces with axenic cultures of <i>Acidithiobacillus caldus</i> , <i>Leptospirillum ferriphilum</i> , and <i>Sulfobacillus thermosulfidooxidans.</i> The method confirmed the high affinity of <i>L. ferriphilum</i> cells to colonize pyrite and chalcopyrite surfaces and indicated that biofilm dispersal occurs in mature pyrite batch cultures of this species. Deep neural networks were also applied to analyze biofilms of different microbial consortia. Recent analysis of the <i>L. ferriphilum</i> genome revealed the presence of a diffusible soluble factor (DSF) family quorum sensing system. The respective signal compounds are known as biofilm dispersal agents. Biofilm dispersal was confirmed to occur in batch cultures of <i>L. ferriphilum</i> and <i>S. thermosulfidooxidans</i> upon the addition of DSF family signal compounds. <b>IMPORTANCE</b> The presented method for the assessment of mineral colonization allows accurate relative comparisons of the microbial colonization of metal sulfide concentrate particles in a time-resolved manner. Quantitative assessment of the mineral colonization development is important for the compilation of improved mathematical models for metal sulfide dissolution. In addition, deep-learning algorithms proved that axenic or mixed cultures of the three species exhibited characteristic biofilm patterns and predicted the biofilm species composition. The method may be extended to the assessment of microbial colonization on other solid particles and may serve in the optimization of bioleaching processes in laboratory scale experiments with industrially relevant metal sulfide concentrates. Furthermore, the method was used to demonstrate that DSF quorum sensing signals directly influence colonization and dissolution of metal sulfides by mineral-oxidizing bacteria, such as <i>L. ferriphilum</i> and <i>S. thermosulfidooxidans</i>