In situ detection of bacteria involved in cathodic depolarization and stainless steel surface corrosion using microautoradiography

Aims: To examine the activity of bacteria involved in cathodic depolarization and surface corrosion on stainless steel in an in situ model system. Methods and Results: The microautoradiographic technique (MAR) was used to evaluate the activity of bacterial populations on stainless steel surfaces with a single cell resolution. Anaerobic uptake and fixation of ¹⁴C‐labelled bicarbonate occurred within corrosion sites in the absence of atmospheric hydrogen or other external electron donors, whereas it was taken up and fixed by bacteria at all other stainless steel surfaces in the presence of atmospheric hydrogen. This indicates that the bacteria utilized electrons originating from the corrosion sites due to the ongoing corrosion (cathodic depolarization). Conclusion: Under in situ conditions, bacteria were fixating ¹⁴C‐labelled bicarbonate at corrosion sites in the absence of atmospheric hydrogen. This indicates that electrons transferred to the bacteria provided energy for bicarbonate fixation due to cathodic depolarization. Significance and Impact of the Study: Application of the MAR method showed ongoing biocorrosion in the applied in situ model system and allowed in situ examination of bacterial activity on a single cell level directly on a metal surface providing information about potential corrosion mechanisms. Furthermore, application of fluorescence in situ hybridization in combination with MAR allows for identification of the active bacteria.     

Assessment of Human Health and Ecological Risks Posed by the Uses of Steel-Industry Slags in the Environment

Steel-industry slag, a co-product of iron and steel production, is produced and sold for use in a wide range of applications. A comprehensive study of the potential human health risks associated with the environmental applications (e.g., fill, roadbase, landscaping) of iron- and steel-making slag was performed using characterization data for 73 samples of slag collected from blast furnaces, basic oxygen furnaces, and electric arc furnaces. Characterization data were compared to regulatory health-based “screening” benchmarks to determine constituents of interest. Antimony, beryllium, cadmium, trivalent and hexavalent chromium, manganese, thallium, and vanadium were measured above screening levels and were assessed in an application-specific exposure assessment using standard U.S. Environmental Protection Agency risk assessment methods. A stochastic analysis was conducted to evaluate the variability and uncertainty in the inhalation exposure and risk estimates, and the oral bioaccessibility of certain metals in the slag was quantified. The risk assessment found no significant hazards to human health as a result of the environmental applications of steel-industry slag. However, site-specific ecological risk assessment may be required for slag applications in and around small water bodies with limited dilution volume, because high pH and aluminum were found to leach at levels that may be harmful to aquatic life     

The effect of turbulent flow and surface roughness on biofilm formation in drinking water

There is considerable interest in both Europe and the USA in the effects of microbiological fouling on stainless steels in potable water. However, little is known about the formation and effects of biofilms, on stainless steel in potable water environments, particularly in turbulent flow regimes. Results are presented on the development of biofilms on stainless steel grades 304 and 316 after exposure to potable water at velocities of 0.32, 0.96 and 1.75 m s⁻¹. Cell counts on slides of stainless steel grades 304 and 316 with both 2B (smooth) and 2D (rough) finishes showed viable and total cell counts were higher at the higher flow rates of 0.96 and 1.75 m s⁻¹, compared to a flow rate of 0.32 m s⁻¹. Extracellular polysaccharide levels were not significantly different (P< 0.05) between each flow rate on all stainless steel surfaces studied. higher levels were found at the higher water velocities. the biofilm attached to stainless steel was comprised of a mixed bacterial flora including Acinetobacter sp, Pseudomonas spp, Methylobacterium sp, and Corynebacterium/Arthrobacter spp. Epifluorescence microscopy provided evidence of rod-shaped bacteria and the formation of stands, possibly of extracellular material attached to stainless steel at high flow rates but not at low flow rates. Received 04 February 1998/ Accepted in revised form 12 February 1999     

微型钢板内固定与克氏针内固定治疗掌指关节周围骨折临床疗效的回顾性研究

摘要 目的：对比掌指关节周围骨折采用克氏针内固定或微型钢板内固定治疗后的临床疗效。方法：回顾性分析2019年8月~2022年12月期间江南大学附属医院收治的掌指关节周围骨折97例患者的临床资料。按照不同的内固定方式将患者分为A组（克氏针内固定治疗,47例）和B组（微型钢板内固定,50例）。对比两组治疗指标[手术时间、骨折愈合时间、住院时间、功能锻炼开始时间]、术后指标[指关节总活动度、手总主动活动度评分]、手功能[手指总主动屈曲度量表（TAFS）评分]、手部疼痛,同时观察两组术后并发症发生情况。结果：B组的功能锻炼开始时间、骨折愈合时间均短于A组,手术时间长于A组（P<0.05）,两组住院时间组间对比无差异（P>0.05）。B组的指关节总活动度大于A组,手总主动活动度评分高于A组（P<0.05）。治疗3个月后,两组手部疼痛视觉模拟量表（VAS）评分下降,且B组低于A组（P<0.05）。B组手功能TAFS评分优良率为92.00%,高于A组74.47%（P<0.05）。B组的术后并发症发生率低于A组（P<0.05）。结论：相对于克氏针内固定治疗,微型钢板内固定治疗掌指关节周围骨折,可缩短愈合时间、功能锻炼开始时间,提高手功能,指关节总活动度以及手总主动活动度评分,减轻手疼痛,降低并发症发生率,但其手术时间更长。     

An integrative and prospective approach to regional material flow analysis: Modeling the decarbonization of the North Rhine-Westphalian steel industry

North-Rhine Westphalia is the center of the German and European steel production. Its steel industry is heavily based on the primary production route and emits up to 30 Mt CO₂ annually. One possible and increasingly prominent alternative to reduce these emissions is the hydrogen-based direct reduction. While this technology allows for a near climate-neutral production of primary steel, it poses substantial impacts on regional energy and material flows. Hence, the aim of this paper is to quantify the alterations in energy and material flows over time via integrating top-down energy and material flow models with bottom-up process models. The resulting values of emissions, energy, and material flows are then used to develop prospective scenarios that depict the requirements and consequences of potential pathways toward a climate-neutral steel production by 2045. The outcomes show that decarbonizing the North Rhine-Westphalian steel industry leads to an additional demand for renewable energies of up to 52.5 TWh per year, which represents 10% of the current electricity production in Germany. As securing the green electricity demand is a large challenge, the study also analyzes the impact of a partial recourse to natural gas as a reducing agent in combination with other measures like carbon capture and utilization/storage. The results show that such a recourse would reduce the electricity demand to 36.8 TWh. Hence, the paper illustrates relevant implications of the different scenarios, which can be used by policymakers to develop more realistic and resilient strategies for reaching carbon neutrality.     

Interatomic potential for Fe–Cr–Ni–N system based on the second nearest-neighbor modified embedded-atom method

The interatomic potential for Fe–Cr–Ni–N system based on the second nearest-neighbour modified embedded-atom method has been developed in this work. The potential is based on those for the corresponding lower order systems. The potential parameters for the binary systems, Cr–N, Ni–N, Ni–Fe and Ni–Cr, were determined by fitting the lattice constants, elastic properties, heat of solution and defect binding energies. The potential parameters for the ternary systems were calculated based on the corresponding binary systems. Then, all of them were applied to the quaternary system Fe–Cr–Ni–N to confirm their validity by a simulation of the lattice constants of AISI 316 austenitic stainless steel with a range of nitrogen content. The results were in good agreement with the previous observations and calculations.     

Surface Potential Measurement of Bacteria Using Kelvin Probe Force Microscopy

Surface potential is a commonly overlooked physical characteristic that plays a dominant role in the adhesion of microorganisms to substrate surfaces. Kelvin probe force microscopy (KPFM) is a module of atomic force microscopy (AFM) that measures the contact potential difference between surfaces at the nano-scale. The combination of KPFM with AFM allows for the simultaneous generation of surface potential and topographical maps of biological samples such as bacterial cells. Here, we employ KPFM to examine the effects of surface potential on microbial adhesion to medically relevant surfaces such as stainless steel and gold. Surface potential maps revealed differences in surface potential for microbial membranes on different material substrates. A step-height graph was generated to show the difference in surface potential at a boundary area between the substrate surface and microorganisms. Changes in cellular membrane surface potential have been linked with changes in cellular metabolism and motility. Therefore, KPFM represents a powerful tool that can be utilized to examine the changes of microbial membrane surface potential upon adhesion to various substrate surfaces. In this study, we demonstrate the procedure to characterize the surface potential of individual methicillin-resistant Staphylococcus aureus USA100 cells on stainless steel and gold using KPFM.     

Biofilm Colonization Dynamics and Its Influence on the Corrosion Resistance of Austenitic UNS S31603 Stainless Steel Exposed to Gulf of Mexico Seawater

Viable bacterial counts, chemical markers, phospholipid fatty acid analysis (PLFA), and Fourier-transformed infrared spectroscopy (FTIR), together with electrochemical methods, were used to study biofilm dynamics and its impact on the corrosion resistance of UNS S31603 stainless steels exposed to the Gulf of Mexico seawater. Biofilms progressively accumulated, peaking on day 20, but finally detached. The extracellular polysaccharide (EPS)/cellular biomass ratio remained low most of the time, but reached its highest level (4.2 ± 1.9) also on day 20. Viable bacterial cells reached their highest abundance earlier (∼800 CFU/cm²), on day 15. Biofilms were seen covering the stainless steel surfaces heterogeneously and were composed mainly of gram-negative rods, presumably EPS-producing bacteria. Despite the different levels of biofilm biomass and attachment state, field-exposed steel coupons ennobled significantly and showed more active pitting potentials (∼+500 mV_SCE) than on the abiotic control (+650 mV_SCE), where no significant ennoblement occurred. These results suggest that the heterogeneous distribution of biofilms, as opposed to the quantity of surface-associated biomass, promotes formation of differential aeration cells, and that this in turn contributes to the ennoblement of these steels.     

Receptors and signaling mechanisms for B-lymphocyte activation, proliferation and differentiation - Insights from both in vivo and in vitro approaches

During the last three decades, a number of B-lymphocyte specific surface antigens have been defined some of which may also show activation/differentiation specific expression. Here, we review the various signaling events and the receptor-ligand interactions for B-cell development, activation and differentiation. Our discussion and presentation include reviewing the in vivo and in vitro mechanisms. Focus is on the experiments that give us valuable insights into the B cell signaling mechanisms in vitro. Three significant pathways in B-cell development - c-Kit, FLT-3 and IL-7 signaling pathways are elucidated upon. Both antigen dependent and antigen independent mechanisms of B cell stimulation are also reviewed.     

Fabrication of a Bionic Needle with both Super-Hydrophobic and Antibacterial Properties

Many biological surfaces possess unusual micro-nano hierarchical structures that could influence their wettability, which provide new methods for the construction of novel materials. In this work, silver nanoparticles were successfully coated on the surface of stainless steel needle by a simple electroless replacement reaction process between the AgNO₃ solution and the activated stainless steel needle. After the replacement reaction, porous micro/nanostructures were formed on the surface of the stainless steel needle. By modifying long chains of thiol molecules, the stainless steel needle exhibited good super-hydrophobic property with a contact angle greater than 150°. Moreover, the silver coated stainless steel needle (bionic needle) showed strong antibacterial activity against the gram-negative bacterium Escherichia coli (E. coli). By calculating the area of the inhibition zone against E. coli formed on agar medium, the antibacterial activity of the bionic needle with the contact angle of 152° is much better than that with the contact angle of 138°. The as-prepared bionic needle with both super-hydrophobic and antibacterial properties has the potential to be applied in modern medical devices.