Explore the vast range of titles available.

The high-temperature oxidation behavior of low-carbon steel (AISI 1015, AISI 8617, AISI 4115) was investigated over the temperature range from 600 to 1000 °C in humid air containing 25% water vapor. Mass gain of oxidation measurement was performed to study the oxidation kinetics. The microstructure, thickness, and composition of the oxide scale formed were investigated via optical microscope (OM), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and electron probe microanalyzer (EPMA). The oxidation process was performed from 2 to 100 min. As the oxidation time increased, the trend of mass gain per unit area switched from a linear to a parabolic law, regardless of the steel grade used. As the chromium content increased, the duration of time during which the oxidation rate followed a linear relationship decreased. In the low-alloy steel with higher chromium content, the thickness of the mixed oxide layer containing Cr increased and the oxidation rate decreased at all oxidation temperatures.

Background: This study aimed to evaluate the changes in fat utilization associated with transitioning from a traditional to a vegan Mediterranean diet in healthy, physically active men during a ramp exercise test. Methods: In a controlled crossover design, fourteen healthy, physically active men followed a traditional Mediterranean diet for three weeks (baseline). Then, participants transitioned to a four-week isocaloric vegan version of the Mediterranean diet, matched for macronutrient distribution but excluding all animal foods. Immediately after each dietary intervention, participants completed an incremental exercise test (from 30% to 70% of VO2peak) on a cycle ergometer in a fasted state to determine peak fat oxidation (PFO) and its associated exercise intensity (Fatmax). Exercise heart rate and the rating of perceived exertion were also recorded at each exercise intensity. Results: The traditional and vegan Mediterranean diets provided comparable amounts of energy (2599.6 ± 180.8 and 2634.9 ± 148.3 kcal/day, p = 0.140) and total fat (97.0 ± 17.8 and 99.0 ± 13.2 g/day; p = 0.620). However, the vegan Mediterranean diet contained a lower proportion of saturated fat (25.2 ± 6.8 vs. 13.6 ± 4.4% of total fat, p < 0.010). Still, the dietary transition was not associated with modifications in PFO (0.323 ± 0.153 and 0.347 ± 0.147 g/min; p = 0.678) or Fatmax (40.51 ± 7.30 and 40.51 ± 10.71%VO2peak; p = 1.000) during exercise. Moreover, the dietary transition did not significantly change the response curves across exercise intensities for fat oxidation (p = 0.553), heart rate (p = 0.280), or the rating of perceived exertion (p = 0.433). Conclusions: Switching from a traditional to a vegan Mediterranean diet did not affect fat oxidation, exercise intensity at peak fat oxidation, or perceptual responses during exercise in healthy, active men. These findings suggest that physically active individuals can adopt a vegan version of the Mediterranean diet without compromising fat utilization during submaximal aerobic exercise. Clinical Trial Registry: NCT06008886. Date of registration: 28 July 2023.

Antibiotics are mostly collected by sewage systems, but not completely removed within wastewater treatment plants. Their release to aquatic environment poses a great threat to public health. This study evaluated the removal of a widely used fluoroquinolone antibiotic, ciprofloxacin, in enriched nitrifying culture through a series of experiments by controlling ammonium concentrations and inhibiting functional microorganisms. The removal efficiency of ciprofloxacin at an initial concentration of 50 μg L−1 reached 81.86 ± 3.21% in the presence of ammonium, while only 22.83 ± 8.22% of ciprofloxacin was removed in its absence. A positive linear correlation was found between the ammonia oxidation rate (AOR) and ciprofloxacin biodegradation rate. These jointly confirmed the importance of the AOB-induced cometabolism in ciprofloxacin biodegradation, with adsorption and metabolic degradation pathways playing minor roles. The continuous exposure of AOB to ciprofloxacin led to decreases of ammonia monooxygenase (AMO) activities and AOR. The antibacterial effects of ciprofloxacin and its biodegradation products were further evaluated and the results revealed that biodegradation products of ciprofloxacin exhibited less toxicity compared to the parent compound, implying the potential application of cometabolism in alleviation of antimicrobial activity. The findings provided new insights into the AOB-induced cometabolic biodegradation of fluoroquinolone antibiotics.

Conventional aerobic methanotrophs oxidize methane (CH4) and covert CH4-derived carbon (C) into biomass at the oxic-anoxic interface of inundated rice paddy fields, playing indispensable role in mitigating greenhouse gas emissions and loss of organic C from methanogenesis. Two phylogenetically distinct groups of methanotrophs, type I (γ-proteobacteria) and type II (α-proteobacteria) methanotrophs, often co-exist in rice paddy soil and compete for CH4 biotransformation. Since these two methanotrophic groups also possess differential kinetics of CH4 oxidation and pathways of C assimilation, the consequence of their niche differentiation and metabolic differences in soil is expected to affect the CH4 oxidation rate and C conversion efficiency. Here, we examined the microbiology, chemistry, and CH4 metabolism in 24 geographically different paddy soils, covering four climate zones of eastern China. High-throughput sequencing of pmoA gene displayed a clear separation of in situ methanotrophic compositions between temperate (warm and mid-temperate) and warmer (subtropics and tropics) climate zones, likely driven by soil pH. Both methanotrophic groups were detected in soils but proportions of type I methanotrophs increased in temperate soils of higher pH (accounting for 76.1 ± 12.4% and 44.1 ± 14.8% in warm temperate and mid-temperate, respectively). Type II methanotrophs prevailed in warmer zones (accounting for 66.2 ± 21.6% and 70.5 ± 12.1% in tropics and subtropics, respectively) where soils were more acidic. Higher incorporation of 13C for synthesis in C14+C16 PLFAs (63.1–93.4% of total production of 13C-PLFAs) was found based on microcosm incubation, reflecting type I methanotrophs dominated the CH4 assimilation in paddy soils. Particularly, temperate soils with increased proportions of type I methanotrophs showed higher CH4 oxidation rate and C conversion efficiency. Collectively, this study depicts a continental-scale disparity of methanotrophic dynamics that tightly associates with consequence of niche differentiation of different types of methanotrophs and highlights the importance of microbiological control to maximize the rate and efficiency of methanotrophy.

Interaction of aluminum conductor alloy AlTi0.1 (Al + 0.1 wt % Ti) containing 0.01, 0.05, 0.1 and 0.5 wt % strontium additives with atmospheric oxygen in the range 723–823 K without formation of a liquid phase has been investigated by the thermogravimetric method. The kinetic parameters, true rate constants and activation energies of the oxidation process were determined for the studied compositions. It was revealed that, with an increase in the strontium content from 0.01 to 0.5 wt %, the oxidation rate of the initial alloy AlTi0.1 increases with a simultaneous decrease in the apparent activation energy of the oxidation process from 140.0 to 116.9 kJ/mol. An increase in the oxidation rate is explained by the interaction of strontium oxide with aluminum oxide with the formation of spinel, which simplifies the access of oxygen to the reaction surface. The oxidation kinetics of alloys is approximated by a hyperbolic law.

We conducted multiple small (2011–2012) and one large sampling campaign (2013) at selected profiles along the Elbe River. With the data we were able to outline spatial and temporal variability of methane concentration, oxidation and emissions in one of the major rivers of Central Europe. The highest methane concentrations were found in human-altered riverine habitats, i.e., in a harbor (1,888 nmol L−1), in a lock and weirs (1409 ± 1545 nmol L−1), and in general in the whole “impounded” river segment (383 ± 215 nmol L−1). On the other hand, the lowest methane concentrations were found in the “lowland” river segment (86 ± 56 nmol L−1). The methane oxidation rate was more efficient in the “natural” segment (71 ± 113 nmol L−1day−1, which means a turnover time of 49 ± 83 day−1) than in the “lowland” segment (4 ± 3 nmol L−1day−1, which means a turnover time of 39 ± 45 day−1). Methane emissions from the surface water into the atmosphere ranged from 0.4 to 11.9 mg m−2 day−1 (mean 2.1 ± 0.6 mg m−2 day−1) with the highest CH4 emissions at the Meissen harbor (94 kg CH4 year−1). Such human-altered riverine habitats (i.e., harbors and similar) have not been taken into consideration in the CH4 budget before, despite them being part of the river ecosystems, they may be significant CH4 hot-spots. The total CH4 diffusive flux from the whole Elbe was estimated to be approximately 97 t CH4 year−1.

A lab-scale pure moving bed sequencing batch biofilm reactor (MBSBBR) was employed to investigate changes in nitrification kinetics and microbial diversity. The MBSBBR operated under different aeration strategies (defined by the ratio of the duration of the subphases with (t1) and without (t2) aeration (R = t2/t1)) − continuous (R = 0) and intermittent (with constant time of non-aerated subphases (t2 = 10 min) and variable duration of subphases with aeration (t1 = 40 min–R = 1/4, t1 = 30 min–R = 1/3, t1 = 20 min–R = 1/2) and dissolved oxygen (DO) concentrations (6 mg/L; 3.5 mg/L). Moreover, the reactor’s organic (OLR) and nitrogen (NLR) loading rates were changed in the following ranges: OLR—537–402 gCOD/m3·d, NLR—64–48 gN/m3·d. The obtained results showed that, irrespective of changes introduced in particular series, a highly effective nitrification process (93.36 ± 2.13%) was achieved. The activity of bacteria capable of oxidizing ammonia nitrogen changed differently from that of bacteria capable of oxidizing nitrites (NOB). An increase in R was the primary factor changing the activity of ammonia-oxidizing microorganisms. NOB activity was affected only by the reduction of OLR and NLR. NOB were the predominant bacterial group, consistent with the kinetics studies. A DO decrease caused an increase in the abundance of AOB, NOB, and Comammox bacteria. Comammox bacteria were the most abundant at R = 1/2 and DO = 3.5 mg/L.

Abstract—A critical analysis of experimental and computational studies on the actual ecological problem of the formation of acidic drainage waters in dumps of sulfide-containing rocks has been carried out. The focus is placed onto assessing reasons for changes in the oxidation rate of pyrite (r), which is the most common sulfide. The dependences of r on temperature, pH, and contents of O2 and Fe3+ in the solution remain almost the only ones expressed in the form of equations. The slow stage of Fe2+ oxidation in acidic solutions cannot control r under natural conditions, because this process is accelerated by iron-oxidizing bacteria. The value of r also changes depending on the type and content of isomorphic admixtures in pyrite, decreases under the influence of some ligands and other sulfides (galvanic effect), and varies with time. The effect of time is usually explained by the formation of a surface protective layer of reaction products, but a probable alternative explanation is the dissolution (disappearance) of surface defects. Depending on the content and activity of minerals that produce and neutralize acid, the weathering of dumps can proceed with the formation of acidic or near-neutral solutions. Scenarios of the processes are predicted using static and kinetic tests, which have significant disadvantages because of the differences between the laboratory and field conditions. The use of mathematical modeling for this purpose is promising, but so far it is limited due to the simplification of models and calculation errors. However, the simulation has clearly showed that the value of r in the dumps is controlled by the rate of O2 delivery, which in turn depends on the pore size, the degree of pore filling with water, and the temperature and pressure gradients. To prevent and recultivate acidic drainage waters, materials are used that isolate individual grains of sulfides (microencapsulation) or the entire dump from O2 penetration, alkaline materials that neutralize acid, bactericides that reduce the activity of iron-oxidizing bacteria, and bioreactors in which metal sulfides are deposited under the action of sulfate-reducing bacteria.

Methanotrophs use methane (CH 4 ) as a carbon source. They are particularly active in temperate forest soils. However, the rate of change of CH 4 oxidation in soil with afforestation or reforestation is poorly understood. Here, soil CH 4 oxidation was examined in New Zealand volcanic soils under regenerating native forests following burning, and in a mature native forest. Results were compared with data for pasture to pine land-use change at nearby sites. We show that following soil disturbance, as little as 47 years may be needed for development of a stable methanotrophic community similar to that in the undisturbed native forest soil. Corresponding soil CH 4 -oxidation rates in the regenerating forest soil have the potential to reach those of the mature forest, but climo-edaphic fators appear limiting. The observed changes in CH 4 -oxidation rate were directly linked to a prior shift in methanotrophic communities, which suggests microbial control of the terrestrial CH 4 flux and identifies the need to account for this response to afforestation and reforestation in global prediction of CH 4 emission.

The growing global population and increasing demand for agricultural products have exerted significant pressure on agricultural systems. As a result, soil organic matter depletion and degradation have become prevalent issues, including in regions such as South Bohemia, Czech Republic, where conventional farming practices are predominant. Soil organic matter (SOM) plays a critical role in soil health, crop productivity, and the sustainability of agricultural systems, with changes occurring in both the total and labile fractions of the organic matter pools. However, changes in the total soil organic matter carbon pool (TOC) resulting from agricultural practices occur gradually and may become evident only after several years, posing challenges for timely management adjustments. Therefore, the identification of early indicators of SOM dynamics is crucial for implementing prompt corrective actions. The aim of this study was to evaluate the effects of sustainable management practices, such as cultivated crops (Pisum sativum and Lupinus albus), selected entomopathogenic and myco parasitic fungi (MEHA) (Trichoderma virens and Metarhizium brunneum), and lactic acid bacteria (LAB) on the labile fraction of the SOM pool (CLSOM) and identify potential early indicators. Our findings demonstrated that the type of crop and applied microorganisms (treatments) significantly affected the CLSOM in peas, and the crop growth stages affected the TOC in both pea and lupin. Growth stages also showed an impact on the CLSOM in lupin. Moreover, in both crops, the change in CLSOM correlated with changes in the SOM oxidation rate constant (k), carbon lability index (LI), carbon management index (CMI), and carbon enrichment ratio (ER). Conversely, changes in the TOC did not exhibit significant correlations, except for LI and CMI, which showed a positive correlation with the TOC in peas (p < 0.05). Furthermore, the separate application of MEHA and LAB on seeds or leaves resulted in increased SOM carbon pools compared with the combined application. The application of these beneficial microorganisms in pea and lupin crops showed potential in maintaining or increasing CLSOM, which can be assessed early through indicators such as k, LI, CMI, and ER. Contributing to the development of sustainable soil management strategies, future research should further investigate different crops and microorganisms—and the mechanisms underlying their observed relationships—and explore additional early indicators to refine and optimize sustainable agricultural practices.