Search Results (20)

To study the influence of the main roof period pressure on the instability mechanism of rock pillars with burst liability, the composite loading mode of “pre-cycling loading + continuous loading with a constant rate” was used to conduct compression experiments on rock samples. Meanwhile, the mechanical behaviour response characteristics of rock samples were discussed. Experiment results are shown as follows: (1) mechanical properties of rock samples were strengthened by closing primary pores under pre-cycling loading. The surface roughness and secondary crack number decreased gradually with the pre-cycling threshold; (2) the Kaiser effect of AE (Acoustic Emission) signals was significant in the second and third pre-cycling loading and unloading stages. The Kaiser effect disappeared in the continuous loading stage; (3) AF-RA (Average Frequency-Risetime Amplitude) signals were distributed in a dense-sparse-dense form. Low AF and high RA shear type cracks were more common. Shear failure was the dominant failure mode in rock samples. Full article

In the first part of this article devoted to the assessment of the fatigue life of structural steels at low temperatures, a study was conducted on the effect of pre-cycling in a low-cycle fatigue mode on the time dependences of acoustic emission parameters. Commonly used St-3 steel was tested at −60 °C with varying durabilities, after which it was fractured once during static tests. The multilevel acoustic model used made it possible to estimate the structural parameter $\gamma$ at the stage of elastoplastic deformation. The stage of active development of microcracks and their coalescence corresponds to a homogeneous fracture with stable acoustic emission characteristics (signal duration, amplitude variation coefficient, etc.). It was shown that regardless of the maximum voltage (460, 480, and 500 MPa) in the cycle and the operating times of up to 0.3, 0.5, and 0.7, the structural parameter remains within the known limits. The parameters of the Weibull law distribution and the logarithmically normal distribution for the coefficient γ were obtained, theoretical and calculated fatigue curves were plotted, and a method was proposed for evaluating the number of cycles before fracture under irregular loading conditions in the real operation of pressure vessels based on the “rainflow” cycles counting method. Full article

Background: Climate change poses significant challenges to global health, At the same time, the healthcare sector itself, with its high resource demands, also contributes substantially to global warming. Anesthesia, particularly through the use of volatile inhalation anesthetics, is a key contributor in this respect. The present exploratory study examines staff perceptions of precycling and recycling strategies aimed at reducing the environmental impact of anesthetic gases at the General Hospital Vienna, Austria. This large institution has recently implemented major changes, including the shutdown of the centralized nitrous oxide supply and the introduction of anesthetic gas recycling systems on anesthesia machines, alongside other precycling measures. Methods: We conducted a cross-sectional online survey of anesthesia team members (n = 103, 61.2% females) to assess current perceptions related to anesthetic gas usage, focusing on precycling and recycling aspects, and their willingness to engage in further sustainability efforts. Results: We found that participants expressed an, in general, positive attitude towards environmental protection measures and a high willingness to make additional efforts to recycle anesthetics. Thus, the anesthesia team members in our institution may be inclined to support strategies like minimizing the use of volatile anesthetics. Conclusions: These preliminary insights could inform actionable recommendations for advancing sustainable practices in anesthesiology at our hospital. Full article

Duathlon consists of two durations of running separated by cycling in a format similar to triathlon. The addition of cycling and the associated loadings on the neuromuscular system can modify spatiotemporal variables in running including trunk motion, which can impact running economy. Changes to trunk motion can be inferred by measuring accelerations of the centre of mass (CoM). However, there is scarce research into trunk dynamics in duathlon. Therefore, the aim of this study was to use an inertial sensor (an accelerometer) to compare acceleration magnitudes of the trunk in the vertical, mediolateral, and anteroposterior directions during a simulated field-based duathlon. Specifically, running performance and magnitudes of trunk acceleration were compared pre and post a cycling load. Ten well-trained duathletes (seven males, three females (mean ± SD; age: 31.1 ± 3.4 years; body mass: 70.9 ± 6.9 kg; body height: 177 ± 5.82 cm; 9.45 ± 1.7 weekly training hours per week; 9.15 ± 5.2 years training experience)) completed a 5 km run performed at a self-selected pace (described as moderate intensity) prior to 20 km of continuous cycling at four varied cadence conditions. This was immediately followed by a 2.5 km run. Mean completion times for the final 2.5 km in running pre-cycling (4.03:05 ± 0.018) compared to the 2.5 km in running post-cycling (4.08:16 ± 0.024) were significantly different. Regarding trunk acceleration, the largest difference was seen in the vertical direction (y axis) as greater magnitudes of acceleration occurred during the initial 1 km of running post-cycling combined with overall significant alterations in acceleration between running pre- and post-cycling (p = 0.0093). The influence of prior cycling on trunk acceleration activity in running likely indicates that greater vertical and mediolateral trunk motion contributes to decremental running performance. In future, further advanced simulation and analysis could be performed in ecologically valid contexts whereby multiple accelerometers might be used to model a more complete set of dynamics. Full article

Lignohumates are increasing in popularity in agriculture, but their chemistry and effects on plants vary based on the source and processing. The present study evaluated the ability of two humates (H1 and H2) to boost maize plant performance under different phosphorus (P) availability (25 and 250 μM) conditions in hydroponics, while understanding the underlying mechanisms. Humates differed in chemical composition, as revealed via elemental analysis, phenol and phytohormone content, and thermal and spectroscopic analyses. H1 outperformed H2 in triggering plant responses to low phosphorus by enhancing phosphatase and phytase enzymes, P acquisition efficiency, and biomass production. It contained higher levels of endogenous auxins, cytokinins, and abscisic acid, likely acting together to stimulate plant growth. H1 also improved the plant antioxidant capacity, thus potentially increasing plant resilience to external stresses. Both humates increased the nitrogen (N) content and acted as biostimulants for P and N acquisition. Consistent with the physiological and biochemical data, H1 upregulated genes involved in growth, hormone signaling and defense in all plants, and in P recycling particularly under low-P conditions. In conclusion, H1 showed promising potential for effective plant growth and nutrient utilization, especially in low-P plants, involving hormonal modulation, antioxidant enhancement, the stimulation of P uptake and P-recycling mechanisms. Full article

This work aimed to answer fundamental questions about the optimal processing and formulation of hard carbon electrodes typical of those anticipated in commercial sodium-ion cells. Procedurally simple tests were proposed to compare the effects of slurry mixing energy and conductive additives on the morphology of and conductive networks in electrodes made with hard carbons from two different manufacturers. Long-range and short-range electronic conductivity was quantified with high repeatability for samples of each hard carbon electrode produced on different days. The most significant changes induced by mixing energy were observed in the electrodes produced without conductive additives, which was found to relate to post-processing particle size. Hard carbon from one source was pulverized by high energy mixing, replacing the electronic effect of conductive additives while increasing pore tortuosity and impedance. These findings recommend evaluating the dry electrode through-resistance as a complement to quantifying pre-cycling impedance to validate mixing protocol and the application of conductive additives in hard carbon electrodes. These procedures can also serve as reliable low-cost methods for quality control at early stages of sodium-ion anode manufacturing. Full article

Increasing consumption produces a large amount of cotton textile waste, the conversion of which into porous metals used for energy purposes is of practical value. In this paper, a porous, Ni-based, hollow microtubular weave (Ni-HTW) is obtained from cotton weave by high-temperature carbonization and hydrothermal synthesis with high-temperature reduction. The Ni-based, hollow microtubules in this weave have a diameter of 5–10 μm and a wall thickness of about 1 μm, and every 15 microtubules form a loose bundle with a diameter of 150–200 μm. For improved performance, Ni(OH)₂ nanosheets are further electrodeposited on the fibers’ surface of the Ni-HTW to form a nano-Ni(OH)₂/Ni-HTW composite electrode with a core–shell heterostructure where Ni is the core and Ni(OH)₂ the shell. The combination of hollow microtubule weave morphology and nanosheet structure results in a large specific surface area and abundant active sites, and the composite electrode shows excellent electrocatalytic performance and long-term stability for methanol oxidation (MOR) and urea oxidation (UOR). The current densities can reach 303.1 mA/cm² and 342.5 mA/cm² at 0.8 V, and 92.29% (MOR) and 84.41% (UOR) of the pre-cycle current densities can be maintained after 2000 consecutive cycles. Full article

The interaction between fatigue damage and hydrogen in TC4 welded joints was analyzed considering specimens with different pre-cycles. The fracture failure caused by hydrogen-induced fatigue damage was investigated using tensile testing and microstructural observations. The results indicate that increasing the number of pre-cycles increases the specimens’ initial dislocation density, enhancing the severity of the hydrogen-induced embrittlement phenomenon. The hydrogen-enhanced local plasticity mechanism, manifested by fracture along the grain boundary, dominates the tensile process in fatigue-damaged hydrogen-filled welded joints after 10,000 and 20,000 pre-cycles. After 30,000 pre-cycles, the hydrogen-enhanced decohesion mechanism dominates the tensile process, manifesting as a transgranular cleavage decoupling fracture. Full article

The present study, concerned with high-performance ORR catalysts, may be a valuable resource for a wide range of researchers within the fields of nanomaterials, electrocatalysis, and hydrogen energy. The objects of the research are electrocatalysts based on platinum–copper nanoparticles with onion-like and solid-solution structures. To evaluate the functional characteristics of the catalysts, the XRD, XRF, TEM, HAADF-STEM, and EDX methods, as well as the voltammetry method on a rotating disk electrode have been used. This work draws the attention of researchers to the significance of applying a protocol of electrochemically activating bimetallic catalysts in terms of the study of their functional characteristics on the rotating disk electrode. The choice of the potential range during the pre-cycling stage has been shown to play a crucial role in maintaining the durability of the catalysts. The activation of the PtCu/C catalyst during cycling of up to 1.0 V allows for an increase in the durability of the catalysts with onion-like and solid-solution structures of nanoparticles by 28% and 23%, respectively, as compared with activation of up to 1.2 V. Full article

The recovery of phosphorus (P) from milk processing flotation sludges (MFS) using pyrolysis can contribute to a sustainable reuse of P by converting waste to fertiliser. The objectives of this study were to quantify the recovery and transformation of P following MFS pyrolysis and compare the efficacy of raw and pyrolysed MFS as organic P fertilisers. Phosphorus retention in biochars was high (98 ± 0.73% yield), leading to the enrichment of P relative to the raw MFS by a factor of 4.3–4.5. Pyrolysis of the MFS at 450 °C led to a 3-fold increase in the proportion of P in the HCl-extractable fraction (65 ± 0.32%), a 2-fold reduction in NaOH-P (30 ± 2.1%), and negligible amounts of P in the H₂O-P and NaHCO₃-P fractions. The bioavailability of P in raw MFS and 450 °C biochar was compared to a soluble P fertiliser in P-limiting plant bioassays. In the short-term (70 day) trial where ryegrass was grown on three soil types (Arenosol, Vertisol or Ferralsol), biochar MFS showed higher efficacy as a P fertiliser than raw MFS in the acidic Ferralsol, whereas the opposite response was observed in the near-neutral Arenosol. In the Vertisol, neither the raw MFS nor biochar produced more cumulative biomass or P uptake than any of the nil P controls. Over a longer 200-day period, raw MFS and biochar applied to the Arenosol were about 20% as efficient at providing P to ryegrass plants as the water-soluble K₂PO₄, suggesting that higher application rates of MFS or biochar would be required to match synthetic fertilisers in the short term. Full article

This paper focuses on the LiFePO₄ (LFP) battery, a classical and one of the safest Li-ion battery technologies. To facilitate and make the cathode manufacture more sustainable, two Kynar^® binders (Arkema, France) are investigated which are soluble in solvents with lower boiling points than the usual solvent for the classical PVDF binder. Li-LFP and graphite-Li half cells and graphite-LFP full cells are fabricated and tested in electrochemical impedance spectroscopy, cyclic voltammetry (CV) and galvanostatic charge-discharge cycling. The diffusion coefficients are determined from the CV plots, employing the Rendles-Shevchik equation, for the LFP electrodes with the three investigated binders and the graphite anode, and used as input data in simulations based on the single-particle model. Microstructural and surface composition characterization is performed on the LFP cathodes, pre-cycling and after 25 cycles, revealing the aging effects of SEI formation, loss of active lithium, surface cracking and fragmentation. In simulations of battery cycling, the single particle model is compared with an equivalent circuit model, concluding that the latter is more accurate to predict “future” cycles and the lifetime of the LFP battery by easily adjusting some of the model parameters as a function of the number of cycles on the basis of historical data of cell cycling. Full article

In order to close the phosphorus cycle in the long term, efficient recycling processes are necessary to ensure that this critical nutrient can be returned to arable land. Sewage sludge recycling is of particular importance due to the relatively high phosphorus content of sewage sludge. In this article, the current recycling paths of Austrian sewage sludge are highlighted, focusing on the advantages and limitations of sewage sludge composting. In addition to nutrient contents, pollutant loads were also analyzed in order to also discuss the limitations of this recycling pathway. Therefore, data from Austrian composting plants with focus on sewage sludge are used. The results show that the currently relevant pollutants (heavy metals) are predominantly below the limits prescribed for recycling and spreading on arable land. However, in order to decide on a recycling path at an early stage, a pollutant monitoring system must be in place. Due to pollution, mono-incineration with subsequent phosphorus recovery is also currently being discussed in Austria. Mono-incineration can represent an important component of sewage sludge disposal, because some sewage sludges are not suitable for composting due to potential environmental hazards. Therefore, it is important that evidence-based limit values and measures for the reduction in pollutants for input sources are determined. Full article

The plastic flow behaviors of FCC polycrystalline aluminum after pre-cyclic tension-compression deformation are mainly investigated in tension–torsion stress space by the physically based crystal plasticity model introducing a back-stress. A global finite element model (GFEM) constructed of sufficient grains was established to simulate the same-size thin-walled tube specimen constrained and loaded as the experiments of yield surfaces. The computational results showed that the shape of subsequent yield surfaces and the plastic flow directions directly depended on the given offset strain levels and the applied re-loading paths under different pre-cyclic deformations. The angle deviation between the plastic flow direction and the theoretical orthogonal direction further indicated that there was a large difference between them in the inverse pre-straining direction, but the difference was negligible in the pre-straining direction. From the influence of the anisotropic evolution of the subsequent yield surfaces on plastic flow, we found that the plastic normality rule followed the smooth yield locus; conversely, the significant non-associated flow was attributed to the distorted yield locus. Furthermore, it was also demonstrated that the anisotropic evolution and the plastic flow trend of the subsequent yield surfaces obtained by experiments can be better reproduced by the crystal plasticity model. Full article

Conversion-type electrode materials for lithium-ion batteries experience significant structural changes during the first discharge–charge cycle, where a single particle is taken apart into a number of nanoparticles. This structural evolution may affect the following lithium insertion reactions; however, how lithiation occurs in pre-cycled electrode materials is elusive. In this work, in situ transmission electron microscopy was employed to see the lithium-induced structural and chemical evolutions in pre-cycled nickel oxide as a model system. The introduction of lithium ions induced the evolution of metallic nickel, with volume expansion as a result of a conversion reaction. After pre-cycling, the phase evolutions occurred in two separate areas almost at the same time. This is different from the first lithiation, where the phase change takes place successively, with a boundary dividing the reacted and unreacted areas. Structural changes were restricted at the areas having large amount of fluorine, implying the residuals from the decomposition of electrolytes may have hindered the electrochemical reactions. This work provides insights into phase and chemical evolutions in pre-cycled conversion-type materials, which govern electrochemical properties during operation. Full article

Increasing amounts of disposable food packaging waste are contributing towards a global environmental crisis, and approaches to successfully preventing such waste—called precycling—are urgently needed. The human ability to define oneself as a member of a group (social identity) may represent a powerful source for realizing environmental endeavors. Therefore, in this article we conceptualize precycling behavior in households as pro-environmental behavior embedded in social identity processes. To explore precycling, we combined food diaries and qualitative virtual interviews with 26 households in Berlin, Germany. We analyzed our data based on the Social Identity Model of Pro-Environmental Action (SIMPEA). Starting from the behavioral element of the model (response), we substantiate the concept of precycling suggesting that it can be distinguished into six types of behavior. Furthermore, we propose that the enactment of these precycling behaviors is shaped by social identity processes and social influence in different groups, including: the household itself, neighbors, family and friends, or food collectives. We conclude that these processes are important to realizing precycling in small and private groups as well as in larger collectives. Implications are derived for empirical research and theoretical development as well as for public programs and intervention studies. Full article