Assessment of Sinkhole Hazard in the Area of Shallow Mining Workings Using Electrical Resistivity Tomography

This paper presents the results of investigating shallow rock mass layers with the use of electrical resistivity tomography. The aim of the study was to assess the condition of near-surface rock mass layers located above shallow mining workings of a historical mine in view of the possibility of the occurrence of loose zones or possible voids that could pose a sinkhole hazard for the surface. The study was carried out under the conditions of the “Sztygarka” Training Mine and Museum in Dąbrowa Górnicza City (Upper Silesian Coal Basin, Poland), where discontinuous surface deformations occurred in the past in the form of sinkholes. The study and its interpretation indicate the existence of a sinkhole hazard due to the ongoing processes of the transformation of the near-surface rock mass layers above the shallow workings of a historical mine.

Macrostep formation and step dynamics faceted by discontinuous surface tension

Crystalline structures are a fundamental part of both the natural and man-made world and are broadly defined as anything with a highly ordered and regular structure at a microscopic level. Professor Noriko Akutsu from the Faculty of Engineering, Osaka Electro-Communication University, Japan, is an expert in understanding the dynamics of crystal formation, particularly at crystal surfaces. Akutsu is working to understand the fundamental nature of crystal growth and structure. This work is a multidisciplinary project that requires expertise in physics, materials science and engineering. Akutsu uses a variety of models as well as a variety of physical techniques to uncover the intricacies of crystal growth.

Macrostep formation and step dynamics faceted by discontinuous surface tension

Crystalline structures are a fundamental part of both the natural and man-made world and are broadly defined as anything with a highly ordered and regular structure at a microscopic level. Professor Noriko Akutsu from the Faculty of Engineering, Osaka Electro-Communication University, Japan, is an expert in understanding the dynamics of crystal formation, particularly at crystal surfaces. Akutsu is working to understand the fundamental nature of crystal growth and structure. This work is a multidisciplinary project that requires expertise in physics, materials science and engineering. Akutsu uses a variety of models as well as a variety of physical techniques to uncover the intricacies of crystal growth.

Identification of Pavement Model Parameters in the Area of Discontinuous Surface Deformation Based on FWD Tests

Determination of the parameters of the pavement model in the linear discontinuous surface deformation (LDSD) area is presented in the article. The values are based on back calculations which involve results obtained from the elastic half-space model and the elastic—perfectly plastic model implemented in the finite element code compared with the results of the pavement deflection measured with Falling Weight Deflectometer (FWD). Based on the results of the calculations which have been matched to the results of the in situ measurements, the obtained values of the parameters of the pavement model within LDSD zone and outside it, were analysed. The results of pavement tests indicate at least a threefold increase in pavement deflections in the discontinuous deformation zone compared to deflections in the sections not affected by LDSD. The results of in situ tests and computational analysis presented in the paper allow their use in pavement reinforcement design in the area of anticipated LDSD.

Process Description of an Unconventional Biofilm Formation by Bacterial Cells Autoagglutinating Through Sticky, Long, and Peritrichate Nanofibers

<p></p><p>Biofilms are used in environmental biotechnologies including waste treatment and environmentally friendly chemical production. Understanding the mechanisms of biofilm formation is essential to control microbial behavior and improve environmental biotechnologies. <i>Acinetobacter </i>sp. Tol 5 autoagglutinate through the interaction of the long, peritrichate nanofiber protein AtaA, a trimeric autotransporter adhesin. Using AtaA, without cell growth or the production of extracellular polymeric substances, Tol 5 cells quickly form an unconventional biofilm. In this study, we investigated the formation process of this unconventional biofilm, which started with cell–cell interactions, proceeded to cell clumping, and led to the formation of large cell aggregates. The cell–cell interaction was described by DLVO theory based on a new concept, which considers two independent interactions between two cell bodies and between two AtaA fiber tips forming a virtual discontinuous surface. If cell bodies cannot collide owing to an energy barrier at low ionic strengths but approach within the interactive distance of AtaA fibers, cells can agglutinate through their contact. Cell clumping proceeds following the cluster–cluster aggregation model, and an unconventional biofilm containing void spaces and a fractal nature develops. Understanding its formation process would extend the utilization of various types of biofilms, enhancing environmental biotechnologies.</p><p></p>

Process Description of an Unconventional Biofilm Formation by Bacterial Cells Autoagglutinating Through Sticky, Long, and Peritrichate Nanofibers

<p></p><p>Biofilms are used in environmental biotechnologies including waste treatment and environmentally friendly chemical production. Understanding the mechanisms of biofilm formation is essential to control microbial behavior and improve environmental biotechnologies. <i>Acinetobacter </i>sp. Tol 5 autoagglutinate through the interaction of the long, peritrichate nanofiber protein AtaA, a trimeric autotransporter adhesin. Using AtaA, without cell growth or the production of extracellular polymeric substances, Tol 5 cells quickly form an unconventional biofilm. In this study, we investigated the formation process of this unconventional biofilm, which started with cell–cell interactions, proceeded to cell clumping, and led to the formation of large cell aggregates. The cell–cell interaction was described by DLVO theory based on a new concept, which considers two independent interactions between two cell bodies and between two AtaA fiber tips forming a virtual discontinuous surface. If cell bodies cannot collide owing to an energy barrier at low ionic strengths but approach within the interactive distance of AtaA fibers, cells can agglutinate through their contact. Cell clumping proceeds following the cluster–cluster aggregation model, and an unconventional biofilm containing void spaces and a fractal nature develops. Understanding its formation process would extend the utilization of various types of biofilms, enhancing environmental biotechnologies.</p><p></p>