Search Results (30)

The relationship between tearing energy and crack growth rates in elastomers is typically divided into three regions—slow crack growth, fast crack growth, and a transitional region—each described by separate power law relationships, requiring six variables to fully characterize the behavior. This study introduces a novel, unified equation that simplifies this relationship by combining two coexisting energy dissipation mechanisms into a single model with only four variables. The model consists of two terms, one for each energy dissipation mechanism: one term is dominant at slow crack growth rates and limited by a threshold energy, and the other is dominant at fast speeds. The transition region emerges naturally as the dominant mechanism shifts. The model’s simplicity enables new advances, such as predicting fast crack growth tearing and transition energies using only slow crack growth data. This capability is demonstrated across a wide range of non-strain crystallizing rubbers, including filled and unfilled compounds, tested at room temperature and elevated temperatures and in both swollen and unswollen states. This model offers a practical tool for material design, failure prediction, and reducing experimental effort in characterizing elastomer performance. Notably, this is the first model to unify slow, transition, and fast crack growth regimes into a single continuous equation requiring only four variables, enabling the prediction of high-speed behavior using only low-speed experimental data—a major advantage over existing six-parameter models. Full article

This article compares two exfoliation options of multilayered silicate, one considering the action of shear stress and temperature during melt compounding and another taking into account the action of the thermo-mechanical pretreatment of multilayered silicate in a plasticizer common to the starch and polyvinyl alcohol (PVOH), the two polymers from the compound. Increasing the action time of the shear stress and temperature during melt compounding proved to be an ineffective method for silicate exfoliation following the high degradability of starch and PVOH under thermo-mechanical conditions and the loss of hydration of the multilayered silicate under thermo-mechanical conditions. The obtained results prove that, by pretreating before embedding into the desired starch-PVOH matrix, it was possible to cancel the electrostatic attractions between the component lamellae of a multilayered silicate. During melt compounding with the two polymers, new attractions between the obtained lamellae and the polar groups of each polymer from the blend were settled, and so, without the usage of a liquid plasticizer, exfoliated intercalated nanocomposites were achieved. The improved properties and the practical importance of the new nanocomposites regards the obtaining of a non-degradable material that has a white color, better elastic properties and thermal stability, and a higher dissipation capacity of deformation energy. Full article

Musk mallow (Malva moschata) is a perennial European plant that grows in pastures and grass mixtures. M. moschata is a medicinal plant with a high content of polysaccharides, flavonoids, and other biologically active compounds. The sensitivity of the species to herbicides is, however, generally unknown. In our study, we investigated the effects of three herbicides with different active compounds: (1) Propaquizafop (PPQ), (2) Clopyralid (CPR), (3) Metamitron+Quinmerac (MMQ) on primary photosynthetic processes of M. moschata plants cultivated in two different temperatures (12 and 18 °C). Non-photochemical quenching (NPQ) of absorbed light energy by chlorophyll molecules and the parameters derived from fast chlorophyll fluorescence transient (OJIP) were evaluated before and then 1, 2, 5, 24, and 48 h after the herbicides application. Among the herbicides, only MMQ negatively affected the functioning of photosystem II (PSII). The effect, however, was reversible, and the plants reached pre-application values after 48 h. No herbicide-induced changes in NPQ were found over the time after the application. The majority of the OJIP-derived chlorophyll fluorescence parameters were found to be temperature-sensitive. The herbicides tested in our study may be ranked among those with only limited effects on primary photosynthetic processes in PSII. While the application of PPQ and CPR did not bring any negative effects on the functioning of PSII, MMQ application induced a decrease in the potential quantum yield of PSII (F_V/F_M) and activation of protective mechanisms, increased heat dissipation in particular. These changes, however, were fully alleviated 48 h after MMQ application. Full article

This paper provides results on the tribological behavior of experimental Al–Sn–Pb–Si–Cu–Mg–Zn aluminum alloys and describes the adaptation phenomena that reduce wear intensity during friction with steel. The main focus is on tribofilm formation, which plays an important role in friction energy dissipation. The alloys were tested in a rig imitating a journal-bearing shaft couple, and the friction surfaces were studied by the scanning electron microscopy, energy-dispersive analysis and X-ray photoelectron spectroscopytechniques. Based on the analysis, a conclusion on processes and tribochemical reactions was made. Compared to the initial state, eight new compounds were found on the friction surface. In the most wear-resistant alloy, magnesium precipitated from a solid solution with the subsequent oxidation. The same process was detected for zinc in the least wear-resistant alloy due to its low magnesium content. Furthermore, CuSn₃ and PbS compounds, which require >600 °C temperature to compose, were found in tribofilms, indicating that the rubbing body lost thermodynamic equilibrium during friction. The revealed processes are non-spontaneous and decrease the wear intensity of the alloys, as they are accompanied by negative entropy production and dissipation of friction energy. Stepwise depth XPS analysis also showed the functional levels of the tribofilms. Full article

The high-pressure capillary rheometer (HPCR) represents a state-of-the-art instrument for the determination of rheological properties for plastics and rubber compounds. Rubber compounds have an increased tendency to exhibit flow anomalies depending on the compound ingredients and the processing parameters. Combined with non-isothermal effects due to dissipative material heating, this causes rheological material measurements and the resulting material parameters derived from them to be affected by errors, since the fundamental analytical and numerical calculation approaches assume isothermal flow and wall adhesion. In this paper, the applicability of the empirical rheological transfer function of the Cox–Merz rule, which establishes a relationship between shear viscosity measured with a HPCR and complex viscosity measured with a closed cavity rheometer (CCR), is investigated. The Cox–Merz relation could not be verified for an unfilled EPDM raw polymer or for filled, practical rubber compounds. Using a closed cavity rheometer, a methodology based on ramp tests is then introduced to collect wall slip-free steady-state shear viscosity data under isothermal conditions. The generated data show high agreement with corrected viscosity data generated using the HPCR, while requiring less measurement effort. Full article

Soil can be contaminated by pesticide residues through agricultural practices, by direct application or through spray-drift in cultivations. The dissipation of those chemicals in the soil may pose risks to the environment and human health. A simple and sensitive multi-residue analytical method was optimized and validated for the simultaneous determination of 311 active substances of pesticides in agricultural soils. The method involves sample preparation with QuEChERS-based extraction, and determination of the analytes with a combination of GC-MS/MS and LC-MS/MS techniques. Calibration plots were linear for both detectors over the range of five concentration levels, using matrix-matched calibration standards. The obtained recoveries from fortified-soil samples ranged from 70 to 119% and from 72.6 to 119% for GC-MS/MS and LC-MS/MS, respectively, while precision values were <20% in all cases. As regards the matrix effect (ME), signal suppression was observed in the liquid chromatography (LC)-amenable compounds, which was further estimated to be negligible. The gas chromatography (GC)-amenable compounds showed enhancement in the chromatographic response estimated as medium or strong ME. The calibrated limit of quantification (LOQ) value was 0.01 μg g⁻¹ dry weight for most of the analytes, while the corresponding calculated limit of determination (LOD) value was 0.003 μg g⁻¹ d.w. The proposed method was subsequently applied to agricultural soils from Greece, and positive determinations were obtained, among which were non-authorized compounds. The results indicate that the developed multi-residue method is fit for the purpose of analyzing low levels of pesticides in soil, according to EU requirements. Full article

The persistence of fluopyram and tebuconazole has been studied in different crops and agricultural soils. However, the behaviour of these fungicides may be altered when they are applied as a combined formulation in organically amended vineyard soils under field conditions. The purpose of this study is to evaluate the effect of applying spent mushroom substrate (SMS) or this residue re-composted with ophite (SMS + OF) on the adsorption, dissipation, and mobility of the fungicides fluopyram and tebuconazole in vineyard soils. Triplicate 10 m² plots per treatment were set up in two different vineyard soils in the eastern La Rioja region: silt loam (ARN1) and sandy loam (ARN2), respectively, with low organic carbon (OC) content. The organic residues SMS and SMS + OF were applied at doses of 25 and 100 Mg ha⁻¹. The adsorption distribution coefficients (K_d) increased when SMS and SMS + OF were applied, especially at the higher dose (100 Mg ha⁻¹). The dissipation curve of both compounds fitted a two-phase kinetic model, with a very fast initial dissipation rate, followed by slower prolonged dissipation during the second phase. The dissipation half-lives (DT₅₀) ranged between 4.7 and 26.3 days for fluopyram and between 2.3 and 6.3 days for tebuconazole in the different soils, increasing for fluopyram in the ARN1 amended with SMS and SMS + OF. The fungicide residues at 15–30 cm depth were lower in the unamended and amended sandy loam soil (ARN2), indicating that fungicides are dissipated mainly in the topsoil. The results indicate different dissipation mechanisms for both fungicides, as the adsorption by soil OC prevented the dissipation of fluopyram but facilitated the dissipation of tebuconazole, probably due to the formation of non-extractable residues. Full article

Rosmarinus officinalis L. (rosemary) is an aromatic culinary herb. Native to the Mediterranean region, it is currently cultivated worldwide. In addition to its use as a condiment in food preparation and in teas, rosemary has been widely employed in folk medicine and cosmetics. Several beneficial effects have been described for rosemary, including antimicrobial and antioxidant activities. Here, we investigated the mechanisms accounting for the antioxidant activity of the glycolic extract of R. officinalis (Ro) in isolated rat liver mitochondria (RLM) under oxidative stress conditions. We also investigated its protective effect against acetaminophen-induced hepatotoxicity in vivo. A crude extract was obtained by fractionated percolation, using propylene glycol as a solvent due to its polarity and cosmeceutical compatibility. The quantification of substances with recognized antioxidant action revealed the presence of phenols and flavonoids. Dereplication studies carried out through LC-MS/MS and GC-MS, supported by The Global Natural Product Social Molecular Networking (GNPS) platform, annotated several phenolic compounds, confirming the previous observation. In accordance, Ro decreased the production of reactive oxygen species (ROS) elicited by Fe²⁺ or t-BOOH and inhibited the lipid peroxidation of mitochondrial membranes in a concentration-dependent manner in RLM. Such an effect was also observed in liposomes as membrane models. Ro also prevented the oxidation of mitochondrial protein thiol groups and reduced glutathione (GSH). In model systems, Ro exhibited a potent scavenger activity toward 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radicals and superoxide anions. It also demonstrated an Fe²⁺ chelating activity. Moreover, Ro did not exhibit cytotoxicity or dissipate the mitochondrial membrane potential (∆Ψ) in rat liver fibroblasts (BRL3A cells). To evaluate whether such antioxidant protective activity observed in vitro could also be achieved in vivo, a well-established model of hepatotoxicity induced by acute exposure to acetaminophen (AAP) was used. This model depletes GSH and promotes oxidative-stress-mediated tissue damage. The treatment of rats with 0.05% Ro, administered intraperitoneally for four days, resulted in inhibition of AAP-induced lipid peroxidation of the liver and the prevention of hepatotoxicity, maintaining alanine and aspartate aminotransferase (ALT/AST) levels equal to those of the normal, non-treated rats. Together, these findings highlight the potent antioxidant activity of rosemary, which is able to protect mitochondria from oxidative damage in vitro, and effects such as the antioxidant and hepatoprotective effects observed in vivo. Full article

The Yellow River Basin plays an important role in economic and social development and ecological security; therefore, its ecological protection and high-quality development are vital. In order to understand the level of synergistic development between environment and industry in the Yellow River Basin, and to understand the change in synergy degree through spatial and temporal analysis, and finally to propose suggestions to provide a basis for the policy formulation of environmental protection and industrial development, informing the initiatives of the relevant parties—companies and residents, so as to ensure the high-quality development and sustainable development of the Yellow River Basin, this paper is based on the theory of synergetic and dissipative structure, and it expounds the synergetic mechanism by constructing the compound system of environment and industry in the Yellow River Basin and revealing their internal and external interactions. Based on the panel data of 57 prefecture-level cities in the Yellow River Basin from 2010 to 2020, the synergy degree of environment and industry in the Yellow River Basin and its temporal and spatial characteristics are discussed by using the synergy model of compound systems. The results show that: (1) the overall degree of environmental and industrial synergism in the Basin develops from mildly non-synergistic to mildly synergistic, but the level is still low; there are significant temporal and regional differences in synergy degree in the upper, middle and lower reaches of the Basin and among cities. (2) The number of cities in the basin that are in mild synergy is increasing; the synergy degree shows an overall positive global spatial autocorrelation. Full article

Flutriafol is a systemic triazole fungicide that is used to control diseases in various crops. A study was developed to evaluate the metabolism and dissipation of flutriafol in two different scenarios: laboratory and greenhouse conditions. Courgette and tomato samples treated with a commercial product (IMPACT^® EVO) at the manufacturer recommended dose were analyzed, and courgette samples were also treated at double dose. Ultra-high-performance liquid chromatography coupled with Q-Orbitrap mass spectrometry (UHPLC-Q-Orbitrap-MS), performing targeted and non-targeted approaches (suspect screening and unknown analysis), were used to analyze the samples. The dissipation of flutriafol was fitted to a biphasic kinetic model, with a persistence, expressed as half-life (t_1/2), lower than 17 days. During suspect screening, three metabolites (triazole alanine, triazole lactic acid and triazole acetic acid) were tentatively identified. Unknown analysis led to the identification of four additional metabolites (C₁₆H₁₄F₂N₄, C₁₆H₁₄F₂N₄, C₁₉H₁₇F₂N₅O₂ and C₂₂H₂₃F₂N₃O₆). The results revealed that the proposed methodology is reliable for the determination of flutriafol and its metabolites in courgette and tomato, and seven metabolites could be detected at low concentration levels. The highest concentration of metabolites was found in the laboratory conditions at 34.5 µg/kg (triazole alanine). The toxicity of flutriafol metabolites was also evaluated, and some of them could be more toxic than the parent compound. Full article

Carbon monoxide is often produced during the incomplete combustion of volatile organic carbon compounds in industry. In the combustion chamber for oxidizing carbon monoxide emissions, a penta-coaxial port device can be used to improve the process of mixing the fuel and oxidizer. In this study, the conjugate heat transfer analysis was conducted by solving both Reynolds-averaged Navier–Stokes equations with the eddy dissipation model and solid heat conduction equation in the wall using Fluent 2019R2 to simulate the reaction flow of a volatile organic carbon compound burner and heat transfer of the stack insulation layer. The mass fractions of the O₂, CO₂, and CO gases; the temperature; and the velocity distribution in a combustion chamber were computed to investigate how various design parameters of the combustor, including air inlet size and stack height, and air inflow conditions affected the combustion performance. Results show that the size of the air inlet had only a minor effect on combustion efficiency and that the airstream forced by a fan significantly enhanced the combustion performance. In particular, increasing the height of the stack from 2 m to 4 m greatly increased combustion efficiency from 63% to 94%, with a 50% increase in the incoming air flow rate by natural convection, which demonstrates the importance of stack height in combustor design. Full article

Pesticides are extensively used in agriculture to prevent infestation of crops, control plant-associated diseases and pests, and increase crop productivity. With regards to typical agricultural practice, tank mixing of two or more plant protection products or the subsequent applications of herbicides, fungicides, and insecticides are common application strategies to improve pest control. Our study provides evidence that the fungicide mixture consisting of mancozeb, metalaxyl-M, and chlorothalonil, each applied according to their recommended field rates, retarded the degradation of the phenoxy herbicide 4-chloro-2-methylphenoxyacetic acid (MPCA) in soil. MCPA dissipation times were between 1.6 and 1.9 days without and 2.5–3.5 days with co-applied fungicides. Furthermore, the proportions of extractable residues, non-extractable residues, mineralization, volatile organic compounds, and MPCA metabolism were altered by the fungicide mixture, i.e., considerably lower amounts of the main transformation product of MCPA, 4-chloro-2-methylphenol, were formed. The effects induced by the fungicides persisted throughout the experiment. Our results demonstrate that the current situation of considering individual active substances in the authorization process for plant protection products could lead to a discrepancy in the exposure assessment for humans and the environment. For specifically these cases, this calls into question whether the legally required level of protection is provided. Full article

Sea level rise (SLR) due to climate change is expected to alter tidal processes and energy transport, disproportionately affecting coastal communities. Utilizing a nested hydrodynamics model, we provided an integrated investigation of tidal responses to SLR in the Hangzhou Bay (HZB). The scenarios of SLR in the next hundred years count for both non-uniform trends based on historical altimetry data and uniform trends from the latest IPCC projections. In a comparison of model results under different SLR scenarios, we found that the tidal range is amplified by SLR in HZB with stronger amplification at the shallow southern coast. Tidal range change generally increases with the SLR scale; however, neglecting the heterogeneities in the spatial distribution of SLR tends to overestimate the SLR effects. The harmonic analysis illustrates that SLR exaggerates the dominated semidiurnal tides (M₂ and S₂) but dampens their overtides and compound tides (M₄, M₆, and MS₄), of which M₂ amplitude amplification explains 71.2–90.0% of tidal range change. SLR tends to promote tidal energy entering HZB through the Zhoushan Archipelago (ZA) compared to the prototype, while dampened sea-bed roughness and reduced tidal velocity come with a less dissipative environment in HZB, resulting in 6–18% more tidal energy exported upstream. Numerical experiments indicate ZA has significant effects on tidal responses and energy flux generation, therefore, its quantitative influences and physical mechanism are also discussed in this paper. Full article

Plants growing in subtropical regions are often affected by high temperature and high light in summer and low temperature and high light in winter. However, few studies have compared the photoprotection mechanism of tree species at different successional stages in these two environments, although such studies would be helpful in understanding the succession of forest communities in subtropical forests. In order to explore the strategies used by dominant species at different successional stages to cope with these two environmental conditions, we selected two dominant species in the mid-successional stage, Schima superba and Castanopsis chinensis, and two dominant species in the late-successional stage, Machilus chinensis and Cryptocarya chinensis. The cell membrane permeability, chlorophyll fluorescence, chlorophyll content, and a few light-protective substances of these dominant species were measured in summer and winter. The results show that in summer, the young leaves of dominant species in the mid-successional stage showed higher anthocyanin content and superoxide dismutase (SOD) activity, while those in the late-successional stage showed higher flavonoid and total phenolic content, total antioxidant activity, non-photochemical quenching (NPQ), and carotenoid/chlorophyll (Car/Chl) ratio. In winter, young leaves of dominant species in the mid-successional stage were superior to those in the late-successional stage only in terms of catalase (CAT) activity and NPQ, while the anthocyanin, flavonoids, and total phenol content, total antioxidant capacity, and Car/Chl ratio were significantly lower compared to the late-successional stage. Our results show that the dominant species in different successional stages adapted to environmental changes in different seasons through the alterations in their photoprotection strategies. In summer, the dominant species in the mid-successional stage mainly achieved photoprotection through light shielding and reactive-oxygen-species scavenging by SOD, while the antioxidant capacity of trees in the late-successional stage mainly came from an increased antioxidative compounds and heat dissipation. In winter, the dominant species in the mid-successional stage maintained their photoprotective ability mainly through the scavenging of reactive oxygen species by CAT and the heat dissipation provided by NPQ, while those in the late-successional stage were mainly protected by a combination of processes, including light shielding, heat dissipation, and antioxidant effects provided by enzymatic and non-enzymatic antioxidant systems. In conclusion, our study partially explains the mechanism of community succession in subtropical forests. Full article

The filamentous fungus Penicillium canescens, isolated from oil-polluted soil, was evaluated for its ability to dissipate high-molecular-weight polycyclic aromatic hydrocarbons (PAH). The study was conducted in a microcosm containing 180 g of historical PAH-contaminated soil under non-sterile conditions with two incubation temperatures (14 °C and 18 °C) on a 12-h cycle. The experiment was conducted over 8 months, with four experimental conditions created by varying the volumes of the bulking agent and vegetable oil (olive oil) and the time of addition of these compounds. The PAH dissipation performance of the fungal augmentation treatment was compared with that achieved with a biostimulated soil (bulking agent and vegetable oil) and with the untreated soil as control. The greatest PAH dissipation was obtained with P. canescens bioaugmentation (35.71% ± 1.73), with 13 of the 16 US EPA PAH significantly dissipated, at rates above 18%, and particularly high-molecular-weight PAH, composed of more than three fused aromatic rings. Nematode toxicity tests indicated a significant decrease in the toxicity of soil bioaugmented by this fungus. Fulvic and humic contents were significantly increased by this treatment. All these results suggest that bioaugmentation with P. canescens can be used to restore soils with long-term PAH contamination. Full article