Bacterial adhesion onto mineral surfaces and subsequent biofilm formation play key roles in aggregate stability, mineral weathering, and the fate of contaminants in soils. However, the mechanisms of bacteria-mineral interactions are not fully understood. Atomic force microscopy (AFM) was used to determine the adhesion forces between bacteria and goethite in water and to gain insight into the nanoscale surface morphology of the bacteria-mineral aggregates and biofilms formed on clay-sized minerals. This study yields direct evidence of a range of different association mechanisms between bacteria and minerals. All strains studied adhered predominantly to the edge surfaces of kaolinite rather than to the basal surfaces. Bacteria rarely formed aggregates with montmorillonite, but were more tightly adsorbed onto goethite surfaces. This study reports the first measured interaction force between bacteria and a clay surface, and the approach curves exhibited jump-in events with attractive forces of 97 ± 34 pN between E. coli and goethite. Bond strengthening between them occurred within 4 s to the maximum adhesion forces and energies of −3.0 ± 0.4 nN and −330 ± 43 aJ (10−18 J), respectively. Under the conditions studied, bacteria tended to form more extensive biofilms on minerals under low rather than high nutrient conditions.

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Study Design. Bibliometric analysis. Objective. This study aims to identify and summarize the articles related to sacral fracture surgery, to compare the papers from different countries and journals, to show the trends of researches on sacral fracture surgery. Summary of Background Data. In recent years, studies on sacral fracture are growing rapidly, but there were no bibliometric studies regarding sacral fracture surgery. Methods. Excel 2016 and VOSviewer were used to identify and summarize the articles from Web of Science between 1900 and 2018. Publication number, publication year, publication country, publication organization, publication source, author, sum of times cited, H-index, and journal's impact factors were recorded and analyzed. Bibliometric maps of co-citations and maps of co-occurrence of keywords are drawn. Results. A total of 611 publications were extracted. United States published most articles (227, 37.2%), both total citations (3536) and H-index (32) of United States ranked first of all the countries. The most productive organization on sacral fracture surgery is Johns Hopkins University (14). Spine (43) published the most articles on sacral fracture surgery. The latest keyword “patterns” appeared in 2017 in 5 articles. Other relatively new keywords include “proximal junctional kyphosis,” “spondylopelvic dissociation,” “fragility fracture,” “lumbopelvic fixation” that appeared in 2017 in eight, six, six, and 25 articles, respectively. Conclusion. This bibliometric study showed that there is a growing trend both in published articles related to sacral fracture surgery and relative research interest in the last 30 years. United States dominates the research regarding sacral fracture surgery. Johns Hopkins University, Johannes Gutenberg University of Mainz, and Harborview Medical Center are the best institutions related to sacral fracture surgery research. Spine, J Orthop Trauma, and Injury are the top three productive journals on sacral fracture surgery. Sacral fracture patterns, proximal junctional kyphosis, spondylopelvic dissociation, fragility fracture, and lumbopelvic fixation may be the new research hotspot in this field. Level of Evidence: 5