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Carbon fibres (CF) are commonly used as carriers in biofilm-based wastewater treatment. The surface properties of the CF are herein modified using a combination of nitric acid oxidation and urea to optimise the carrier to immobilise bacterial cells. The capacity of the CF carriers to immobilise bacterial cells and activated sludge is evaluated using bacterial cell adhesion and sludge immobilisation tests. The total interaction energy profiles between the CF supports and bacterial cells were calculated according to the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory to explain the mechanism by which these modifications enhance this immobilisation capacity. CF-U has a high capacity for immobilising bacterial cells and activated sludge (3.7 g-sludge/g-CF supports) owing to its low total interaction energy. Nitric acid oxidation reduced the diiodomethane contact angle of CF from 55.1° to 38.5°, which reduced the Lifshitz-van der Waals interaction energy, while urea modification further increased the zeta potential of CF from 12.8 mV to −0.7 mV, thereby reducing the electrostatic interaction energy. Experiments and DLVO theory both determined that a combination of nitric acid oxidation and urea modification significantly enhanced the ability of CF to immobilise microorganisms. [ABSTRACT FROM AUTHOR]

A series of Ti41Zr25Be34-xNix (x = 4, 6, 8, 10 at.%) and Ti41Zr25Be34-xCux (x = 4, 6, 8 at.%) bulk metallic glasses were investigated to examine the influence of Ni and Cu content on the viscosity, thermoplastic formability, and nanoindentation of Ti-based bulk metallic glasses. The results demonstrate that Ti41Zr25Be30Ni4 and Ti41Zr25Be26Cu8 amorphous alloys have superior thermoplastic formability among the Ti41Zr25Be34-xNix and Ti41Zr25Be34-xCux amorphous alloys due to their low viscosity in the supercooled liquid region and wider supercooled liquid region. The hardness and modulus exhibit obvious variations with increasing Ni and Cu content in Ti-based bulk metallic glasses, which can be attributed to alterations in atomic density. Optimal amounts of Ni and Cu in Ti-based bulk metallic glasses enhance thermoplastic formability and mechanical properties. The influence of Ni and Cu content on the hardness of Ti-based bulk metallic glasses is discussed from the perspective of the mean atomic distance. [ABSTRACT FROM AUTHOR]

Optimizing supports for microorganisms is required for bioreactors. Carbon fibres (CF) were employed as supports for microorganisms. To optimize CF supports for immobilizing bacterial cells, we used methods of nitric acid oxidation and calcium ion coverage. We evaluated the capacity of these CF supports (untreated CF, nitric acid oxidation CF and Ca2+-covered CF) via bacterial cell adhesion tests, based on extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory. The results implied that because of the high hamaker constants, oxidized CF supports had higher capacity in this regard than untreated CF supports. However, the growing oxygen groups increased the negative zeta potential of CF supports, thus likely to reduce their capacity, in accordance with XDLVO theory. Since the Ca2+ coverage could decrease the negative zeta potentials of CF without reducing the hamaker constants, it could enhance the capacity of oxidized CF supports. We concluded that a combination of nitric acid oxidation and Ca2+ coverage could increase the capacity of CF supports to immobilize bacterial cells. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF) is widely used as a sludge biofilm support material for wastewater treatment. Carbon nanotubes/carbon fiber (CNTs/CF) hybrid material was prepared by ultrasonically assisted electrophoretic deposition (EPD). CF supports (CF without handling, CF oxidized by nitric acid, CNTs/CF hybrid material) were evaluated by sludge immobilization tests, bacterial cell adsorption tests and Derjaguin −Landau −Verwey −Overbeek (DLVO) theory. We found that the CNTs/CF hybrid material has a high capacity for adsorbing activated sludge, nitrifying bacterial sludge and pure strains (Escherichia coli and Staphylococcus aureus). CNTs deposited on CF surface easily wound around the curved surface of bacterial cell which resulted in capturing more bacterial cells. DLVO theory indicated the lowest total interaction energy of CNTs/CF hybrid material, which resulted in the highest bacteria cell adsorption velocity. Experiments and DLVO theory results proved that CNTs/CF hybrid material is a super support material for sludge biofilms. [ABSTRACT FROM AUTHOR]

Objective: This meta-analysis aims to investigate the effects of prenatal prophylactic antibiotics on the diversity of intestinal flora in premature infants, with a focus on elucidating the rationale behind this investigation and the potential impact of altered intestinal flora on the health of preterm infants, such as increased susceptibility to infections, impaired nutrient absorption, and compromised immune function., Methods: Relevant literature consistent with the effects of prenatal prophylactic antibiotics on intestinal flora diversity in preterm infants was systematically searched and screened from both domestic and foreign databases, including Wanfang Medical Center, CNKNET, VIpp, and PubMed. Meta-analysis was performed using RevMan 5.2 software. Inclusion criteria for the study were: (1) comparison of prophylactic antibiotic use versus non-use, (2) no restrictions on subjects' characteristics, (3) follow-up loss < 20%, (4) institutional approval, (5) publication within the time frame from January 2017 to December 2022, (6) minimal missing data or suppliable by author contact, and (7) no major errors in sequencing or detection. Outcome measures included intestinal flora composition, phylum flora content, abundance index, and Shannon index, comparing antibiotic-treated and non-treated groups. RevMan 5.2 software was used for statistical analysis. Counting data was expressed as risk ratio (RR), and weighted mean difference (WMD) or standard mean difference (SMD) was selected as analysis statistics., Results: The study encompassed five Chinese literature sources, with one deemed low quality and four high quality. No significant publication bias was observed. Among the included studies, a significant reduction in the intestinal flora abundance index ACE was noted in the treated group compared to the non-treated group (RR: -8.10, 95% CI: -8.81 to -7.40, P < .00001). ACE estimates species richness in a microbial community by considering both abundant and rare species. Higher ACE values indicate greater diversity. Similarly, the Shannon diversity index was lower in the medication group compared to the non-medication group (RR: 0.73, 95% CI: 0.64 to 0.82, P < .00001). Shannon Diversity Index measures species diversity and evenness within a community. Higher values indicate higher diversity, considering both the number of species and their relative abundance. Analysis of Firmicutes content revealed a higher level in the treated group (RR: -6.44, 95% CI: -7.26 to -5.63, P < .00001). Additionally, lower Proteus (RR: 10.96, 95% CI: 9.47 to 12.45, P < .00001) and Klebsiella (RR: 15.96, 95% CI: 15.31 to 16.62, P < .00001) content was observed in the treated group. Conversely, Enterococcus content was higher in the treated group (RR: 2.18, 95% CI: 1.84 to 2.52, P < .00001), along with a higher proportion of Enterococcus (RR: 0.45, 95% CI: 0.27 to 0.76, P = .003). These findings collectively suggest that prophylactic antibiotic use in preterm infants significantly alters the composition of intestinal flora., Conclusion: Our findings suggest that prophylactic antibiotic use in preterm infants leads to a notable reduction in intestinal flora diversity, potentially impacting their health outcomes. Decreased microbial diversity has been linked to gastrointestinal issues, infections, and weakened immune function. These results highlight the importance of cautious antibiotic use in this vulnerable population and the need for further research to better understand and mitigate the potential health implications.