Initial Stage Of Degradation Research Articles

The Potential to Reconstruct 20th Century Soil Organic Carbon Erosion in Rangelands From Small Reservoir Sediments

ABSTRACTSoil erosion and soil organic carbon (SOC) loss are not always linked linearly because SOC‐rich topsoil is eroded at the initial stages of degradation, while horizons with lower SOC content are eroded later, but often at higher rates. Small, silted‐up farm reservoirs potentially document this change during the period of sediment accumulation. This study tests the specific potential of small farm reservoir sediments from the South African Karoo to reconstruct 20th century SOC and total nitrogen (TN) change in rangeland soils. Five reservoir sediment profiles were sampled and texture, total organic carbon (TOC), TN and 137Cs of the samples were analyzed and compared. The results show that there clearly distinguishable flood couplets have been preserved in the sediment, illustrating their suitability for the chronological reconstruction of soil erosion and SOC. With one exception, the older sediments contain more TOC and TN than the younger ones. The TOC changed mostly in earlier than later stages of deposition, which is indicative of soil degradation early after the construction of the dams in the 1920s and 1930s. These distinct changes illustrate that the small reservoir sediments have the potential to reconstruct the impact of land‐use and associated soil erosion on SOC change in rangelands. Their analysis can therefore contribute to a better understanding of the land‐use associated changes of the global carbon cycle during the 20th century.

Impacts of grade control structures on riverbed degradation

Sediment flux of many rivers has been significantly reduced due to human activities caused by economic development, leading to increasingly severe riverbed degradation. To prevent riverbed degradation, grade control structures (GCSs) have been widely applied in degrading channels. Existing studies have not provided a good understanding of the effects of GCSs on flow characteristics and bed morphology in degrading channels, limiting the management of degrading channels. A series of flume tests with no sediment supply are conducted to investigate the effects of GCSs on upstream water levels and riverbed morphology in degrading channels. The experimental results indicate that: (1) in the initial stage of degradation, the water surface slope in the backwater reach is linearly and negatively correlated with the GCS-height Froude number, based on the average flow velocity upstream of the backwater reach due to GCS and the height of GCS; (2) the effective protection bed length upstream of GCS is approximately equal to the length of the reach where the flow velocity is less than the critical velocity for sediment motion in the backwater zone; (3) for sequential GCSs, the effective protection bed length will decrease if GCS is located in the backwater reach of the downstream GCS. A semi-analytical calculation method of the effective protection length and equilibrium bed profile upstream of GCS in degrading channels is proposed based on the critical condition of sediment motion and weir flow formulas. The computed values by the proposed calculation method agree well with the experimental data of the present study.

Disclosing the Nitrogen Sources via Isotope Labeling Technique and the Formation Mechanism of Pyrazine and Alkylpyrazines during the Heat Treatment of N-(1-Deoxy-d-xylulos-1-yl)-alanine and Exogenous Alanine.

The formation pathway and mechanism of various pyrazines were investigated during the thermal treatment of the alanine-xylose Amadori compound (Ala-ARP) and exogenous alanine (Ala). 15N-labeled Ala was used to coheated with Ala-ARP to clarify the nitrogen sources and the respective contributions of exogenous Ala and the regenerated Ala released from Ala-ARP to different pyrazine formation. It was found that exogenous Ala exhibited a priority in capturing glyoxal (GO) to form pyrazine during the thermal degradation of ARP. Compared to the Ala-methylglyoxal (MGO) model, a lower activation energy was required for the Ala-GO reaction, where the reaction dynamics of Ala-GO followed a zero-order model. In addition to forming pyrazine, the interaction between existing exogenous Ala and GO would accelerate the thermal degradation of Ala-ARP and retro-aldolization reaction of deoxyxylosones (DXs) to α-dicarbonyls. During this process, the release of regenerated Ala and MGO was promoted. Accordingly, as GO was expended by exogenous Ala during the initial stage of ARP-Ala degradation, the condensation between regenerated Ala and MGO became intensified, leading to the generation of methylpyrazine and 2,5-dimethylpyrazine. As a result, in the thermally treated mixture of Ala-ARP and exogenous Ala, 55% of the formed pyrazine originated from exogenous Ala, while 63% of the formed methylpyrazine and 57% of the formed 2,5-dimethylpyrazine were derived from regenerated Ala (120 °C, 30 min).

Electrocatalytic degradation of ofloxacin by self-doped copper/carbon cathode materials derived from waste printed circuit boards

Using residual copper metal from waste circuit boards, ordered carbon materials containing copper (PCBs-Cu-800) were synthesized by self-doping for the electrocatalytic degradation of ofloxacin (OFL). Although PCBs-Cu-800 has a smaller specific surface area, its efficiency in degrading OFL was higher than that of carbon materials without copper (PCBs-800), reaching 95.9 % within 2 h. The PCBs-Cu-800 electrode can generate a large amount of H2O2 in the initial stage of degradation, thereby increasing the amount of hydroxyl radicals (·OH) generated and removing OFL. Density functional theory simulations were used to calculate the adsorption energies of O2 on both materials, demonstrating that the self-doped copper model was more prone to O2 adsorption, and elucidating the excellent electrocatalytic performance of PCBs-Cu. The residual copper metal in the raw material is important in the electrocatalytic processes. This study presents an environmentally friendly catalytic material capable of effectively degrading OFL in solution using waste circuit boards and further expands the application scope of advanced electrochemical oxidation technology in wastewater treatment.

Fabrication of geopolymer composites using egg-shell and fly-ash: Comparison between the strength and stability, physio-chemical and mechanical properties

Nowadays, the demand for developing new structural materials, particulate composites made from industrial waste has been preferred along with conventional fiber-reinforced composites. In this work, two new composites were fabricated by reinforcing flyash and eggshell separately in epoxy with equal volume fractions and were termed geopolymer composites. Further thermo-mechanical characterization of these fabricated geopolymer composites was carried out by conducting various mechanical, physical, chemical, and thermal testing methods. The results were compared with the outcomes of neat epoxy composites. It was demonstrated that eggshell-epoxy composites have 28.48 % and 1.5 % more tensile strength than neat epoxy and flyash-epoxy composites. The flexural strength and hardness in a similar fashion were observed as increased by 31.7 %, 7.37 %, and 29.45 %, 15.6 % over neat epoxy and flyash-epoxy composites. The composites were crystalline confirmed from the XRD analysis. In contrast to the above, the thermal conductivity and thermal stability of flyash-epoxy composites were found superior though eggshell-epoxy composite visualized higher stability at the initial stage of thermal degradation. Further, the change of thermal conductivity of these materials with a temperature change was investigated by finite element modeling in MATLAB using the PDE toolbox. It was examined that thermal conductivity increases non-linearly with the increase in temperature up to 700 °C and then follows a uniform trend on further increase.

Multistep kinetic analysis of additive-enhanced plastic degradation

In the realm of non-isothermal degradation kinetics, the utilization of multi-heating rate data has unveiled a fascinating distributed apparent activation energy (Eα) profile when employing isoconversional methods. The advanced isoconversional method (AIC) emerges as a reliable tool, offering Eα values that evolve as chemical reactions progresses. This phenomenon finds its roots in the complex solid-state degradation of plastics, where long-chain hydrocarbons undergo intricate transformations into smaller components through a web of parallel and sequential reactions under the influence of heat. To comprehensively characterize this multifaceted kinetic process, variable pre-exponential factor (A) values were calculated, considering all available heating rate data, in conjunction with the isoconversional principle. These factors complement the changing Eα values, providing crucial insights into the evolving material transformations throughout the reaction. Remarkably, our investigation revealed that in the initial degradation stage, centered around the breakdown of Brominated Flame Retardant (BFR), the reaction follows a contracting spherical model (R3). Transitioning to the subsequent stage, the polymer material undergoes degradation following the diffusion model D4. The incorporation of the isoconversional principle and Criados' masterplot technique effectively facilitates the precise determination of all three kinetic parameters. The process layout we present holds considerable promise for advancing the understanding and control of complex kinetic phenomena.

Degradation of pyrene by Xanthobacteraceae bacterium strain S3 isolated from the rhizosphere sediment of Vallisneria natans: active conditions, metabolite identification, and proposed pathways.

Polycyclic aromatic hydrocarbons (PAHs) were typical environmental contaminants that accumulated continuously in sediment. Microbial degradation is the main way of PAH degradation in the natural environment. Therefore, expanding the available pool of microbial resources and investigating the molecular degrading mechanisms of PAHs are critical to the efficient control of PAH-polluted sites. Here, a strain (identified as Xanthobacteraceae bacterium) with the ability to degrade pyrene was screened from the rhizosphere sediment of Vallisneria natans. Response surface analysis showed that the strain could degrade pyrene at pH 5-7, NaCl addition 0-1.5%, and temperature 25-40°C, and the maximum pyrene degradation (~ 95.4%) was obtained under the optimum conditions (pH 7.0, temperature 28.5°C, and NaCl-free addition) after 72h. Also, it was observed that the effect of temperature on the degradation ratio was the most significant. Furthermore, eighteen metabolites were identified by mass spectrometry, among which (2Z)-2-hydroxy-3-(4-oxo-4H-phenalen-3-yl) prop-2-enoic acid, 7-(carboxymethyl)-8-formyl-1-naphthyl acetic acid, phthalic acid, naphthalene-1,2-diol, and phenol were the main metabolites. And the degradation pathway of pyrene was proposed, suggesting that pyrene undergoes initial ortho-cleavage under the catalysis of metapyrocatechase to form (2Z)-2-hydroxy-3-(4-oxo-4H-phenalen-3-yl) prop-2-enoic acid. Subsequently, this intermediate was progressively oxidized and degraded to phthalic acid or phenol, which could enter the tricarboxylic acid cycle. Furthermore, the pyrene biodegradation by the strain followed the first-order kinetic model and the degradation rate changed from fast to slow, with the rate remaining mostly slow in the later stages. The slow biodegradation rate was probably caused by a significant amount of phenol accumulation in the initial stage of degradation, which resulted in a decrease in bacterial activity or death.

Effects of Invasive Smooth Cordgrass Degradation on Avian Species Diversity in the Dafeng Milu National Nature Reserve, a Ramsar Wetland on the Eastern Coast of China

Invasive smooth cordgrass (Spartina alterniflora) has been expanding rapidly through the coastal wetlands of eastern China and these changes negatively affect local birds. In the Dafeng Milu National Nature Reserve (henceforth referred to as DMNNR), rapid degradation of spartina occurs after an increase in milu (Elaphures davidianus; hereafter elk) numbers and ecological hydrological engineering. We evaluated the impact of such degradation on the abundance and species diversity of birds in the DMNNR during 2017–2021. We found that the area covered by S. alterniflora decreased significantly in the study area at a rate of 310 ha per year and by 62% during 2017–2021 (p < 0.01). With this decrease in the S. alterniflora area, the species richness and abundance of birds first increased and then decreased. Songbird density clearly decreased but species richness did not significantly do so. This research demonstrated that during the initial stages of vegetation degradation, there was a positive effect on bird diversity. With the increasing vegetation degradation increases, both songbirds and waterbirds experience negative impacts. The DMNNR is an important stopover site for waterbirds in the East Asian–Australasian Flyway, and additional measures are needed to control vegetation degradation and to restore the native habitats for birds.

Кратък обзор върху микробиологични аспекти на компостирането

Recycling and disposal of urban waste is one of the goals set by the European Union. The process of composting, which is a cost-effective and environmentally friendly method of processing organic residues, is considered to be one of the ways to achieve these goals. Composting is a biological oxidation process in which organic residues are broken down by a large group of different microorganisms. The present publication presents a brief overview on the composting of organic residues and the participation of individual groups of microorganisms in this process. The decay of materials during composting follows the general biochemical pathways of any other degradation process. In the composting processes and in the finished compost, non-sporeforming bacteria and bacilli, which are most actively involved in the initial stages of degradation of organic substances, occupy a major share in the composition of the general microflora. The share of actinomycetes and micromycetes, which are generally more active in the final stages of organic matter decomposition, is smaller. The amount of actinomycetes increases with increasing temperature in the composting phases. The biogenicity of compost depends on the type of biodegradable agricultural waste used.

Mechanisms of oxidative response during biodegradation of malathion by S. oneidensis MR-1

Malathion, an extensively used organophosphorus pesticide, poses a high potential risk of toxicity to humans and the environment. Shewanella (S.) oneidensis MR-1 has been proposed as a strain with excellent bioremediation capabilities, capable of efficiently removing a wide range of hard-to-degrade pollutants. However, the physiological and biochemical response of S. oneidensis MR-1 to malathion is unknown. Therefore, this study aimed to examine how S. oneidensis MR-1 responds physiologically and biochemically to malathion while also investigating the biodegradation properties of the pesticide. The results showed that the 7-day degradation rates of S. oneidensis MR-1 were 84.1, 91.6, and 94.0% at malathion concentrations of 10, 20, and 30 mg/L, respectively. As the concentration of malathion increased, superoxide dismutase and catalase activities were inhibited, leading to a significant rise in malondialdehyde content. This outcome can be attributed to the excessive production of reactive oxygen species (ROS) triggered by malathion stress. In addition, ROS production stimulates the secretion of soluble polysaccharides, which alleviates oxidative stress caused by malathion. Malathion-induced oxidative damage further exacerbated the changes in the cellular properties of S. oneidensis MR-1. During the initial stages of degradation, the cell density and total intracellular protein increased significantly with increasing malathion exposure. This can be attributed to the remarkable resistance of S. oneidensis MR-1 to malathion. Based on scanning electron microscopy observations, continuous exposure to contaminants led to a reduction in biomass and protein content, resulting in reduced cell activity and ultimately leading to cell rupture. In addition, this was accompanied by a decrease in Na+/K+- ATPase and Ca2+/Mg2+-ATPase levels, suggesting that malathion-mediated oxidative stress interfered with energy metabolism in S. oneidensis MR-1. The findings of this study provide new insights into the environmental risks associated with organophosphorus pesticides, specifically malathion, and their potential for bioremediation.Graphical

Variation of crater morphological parameters in the landing area of Tianwen-1: relationships with the geological environment and climate change

The Zhurong rover of the Tianwen-1 mission successfully landed in the southern part of the Utopian Planitia and the northern region of the dichotomy boundary. Craters within a ~ 134 km2 region surrounding the Zhurong rover were identified and divided into seven degradation classes based on their preservation states and morphological details. Assessing how craters have degraded over time provides insight into local surface processes and then speculates on the climate evolution of the study area. The small depth/diameter (d/D) of craters in the study area may be caused by the rapid filling of sediments or by impact processes occurring in poorly cohesive weathering layers, and may also be associated with the volatile material alteration. As time went by, the process of crater degradation is nonlinear, and the degradation rate of the fresh crater in the study area at the initial stage of degradation may be as high as 0.2 m/Myr. The calculated surface erosion rate for the study area is ~ 10–2–10–3 m/Myr, indicating that the erosion of the Martian surface since the Middle Amazonian occurred in the dry environment dominated by wind-sand erosion.Graphical

A new technique for fault diagnosis in transformer insulating oil based on infrared spectroscopy measurements

AbstractCondition monitoring of the insulating system within power transformers has a massive importance according to the electrical utilities. Dissolved gas analysis (DGA) is frequently used for this purpose. However, DGA lacks the necessary level of accuracy to identify all equipment faults, particularly in their initial stages of degradation. Also, it does not have the capability for real‐time monitoring and relies on manual sampling and laboratory testing, causing potential delays in fault identification. Additionally, the interpretation of DGA data necessitates specialised expertise, which may pose difficulties for smaller entities that have limited access to resources. Therefore, the contribution of this research is to use infrared spectroscopy measurements as a new effective technique substituting the DGA method for fault diagnosis in insulating oil. The inception faults that were considered in this study were the electrical fault (discharges of high energy) and the thermal fault (300°C < Temperature < 700°C). Regarding that, two test cells were crafted especially for serving the simulation processes inside the laboratory for both types of inception faults. Subsequently, six samples of pure paraffinic mineral oil were taken to be degraded in the laboratory. Following that, all of them besides another sample that were not subjected to any kind of faults were taken to be examined by Fourier transform infrared (FTIR) spectroscopy to obtain an overview of the oil's behaviour in each fault case. After that, the FTIR analysis was initially verified utilising the DGA method. Then, for further affirmation, the dielectric dissipation factor (DDF) for all samples was measured. In the final analysis, the verification tests provide experimental evidence about the outperformance of this new optical technique in detecting the transformer's inception faults in addition to proving its potential for being a superior alternative to the well‐known traditional diagnostic techniques.

Degradation of peat-forming plants at the first stages of decomposition in natural and post-pyrogenic peatlands of West Siberia

The aim of the study. Assessment of the phytomass stocks and decomposition rate of peat-forming plants’ residues in peat deposits of natural and post-pyrogenic peatlands at the initial stages of decomposition. Location and time of the study. The study was carried out in 2022 (May-September) at two oligotrophic bog sites: “Bakcharskoye” (field station “Vasyuganye”, IMCES SB RAS) and “Iksinskoye”, which are located in the north eastern spurs of the Great Vasyugan mire in the Bakcharsky and Shegarsky districts of the Tomsk region, Russia. Methods. The phytomass stocks were determined by the cutting method. The following fractions were separated: living phytomass (annual and perennial photosynthetic phytomass, i.e. green parts of grasses, shrubs leaves, mosses); perennial non-photosynthetic phytomass, i.e. shrubs stems, roots of grasses and shrubs; and dead phytomass (mortmass), i.e. litter, moss litter, standing dead phytomass. The decomposition rate of plant residues was determined by the method of litter bags placement in peat (Chamaedaphne calyculata, Sphagnum fuscum, Mixed sample consisting of 60% S. fuscum and 40% Ch. calyculata). In the initial and decomposed samples, the ash content was determined by the dry combustion method. The total carbon and nitrogen content, as well as the carbon and nitrogen isotopic composition, were determined using a DELTA V Advantage isotope ratio mass spectrometer. Results. This short-term study conducted during the growing season in conditions of undisturbed (Natural Ryam) and post-pyrogenic (Gar) phytocenoses showed that due to a significant amount of mortmass (2402 g/m2) Natural Ryam had organic matter stock exceeding that in the Gar by 1.7 times. On average, 59% of organic matter loss from the total losses during the growing season occurred in the first month. In both Gar and Natural Ryam conditions, minimal losses of organic matter were characteristic for Sphagnum fuscum (3.1 and 3.5% respectively). For the remaining samples the Gar conditions were more favorable for the degradation at the initial stages of decomposition. The Mixed sample occupied an intermediate position between its individual components in terms of mass losses. Carbon losses correlated well with mass losses both over 1 month of degradation (r=0.87) and over 4 months (r=0.96). In contrast to carbon, nitrogen accumulated in the Mixed sample at the initial stages of degradation, both after 1 month and 4 months. Conclusions. With smaller phytomass stocks in areas of post-pyrogenic succession, more active decay at the initial stages of organic matter decomposition occurs exactly under these conditions. The impact of post-pyrogenic succession on the rate of organic matter decomposition of Chamaedaphne calyculata plant residues and the Mixed sample was demonstrated. The most intensive decomposition of litter occured during the first month of degradation. Additionally, in the conditions of a burnt bog, a more intense release of nitrogen from all plant residues and accumulation of ash elements in Sphagnum fuscum samples were observed. The mixing of litter components influenced both the rate and dynamics of decomposition. The carbon and nitrogen isotopic composition began to change during the initial stages of decomposition, leading to enrichment with heavier isotopes 15N and 13C. This research emphasizes the importance of studying the processes of plant litter decomposition at the initial stages and considering the plant residue composition when studying the processes of organic matter transformation.

Выделение и характеристика штамма-деструктора дибутилфталата Rhodococcus sp. 5A-K4

The study is devoted to the ability of the bacterial strain 5A-K4, isolated from the rhizosphere of Puccinellia distans (Jacq.) Parl. plants, growing on the territory of industrial development of the Verkhnekamsk salt deposit (Perm krai), to grow on dibutyl phthalate (DBP) as the single carbon source was studied. Based on analysis of the 16S rRNA gene, the strain was identified as a representative of the genus Rhodococcus. Strain 5A-K4 had the highest level of the 16S rRNA gene similarity (99.86%) with Rhodococcus erythropolis NBRC 15567T. The strain grew effectively on a DBP substrate without addition of salt and at a content of 30 g/L NaCl in the cultivation medium. It has been shown that Rhodococcus sp. 5A-K4 is capable of growth at high concentrations of DBP (up to 12 g/L). The genome of the strain 5A-K4 contained the dpeH and mpeH genes, the products of which are involved in the initial stages of DBP degradation. The nucleotide sequences of the dpeH and mpeH genes are homologous to the sequences of the α/β hydrolase genes of strains of the classes Actinomycetes and Bacilli. Based on the data obtained, a pathway for the degradation of DBP by strain 5A-K4 was proposed. Thus, the rhizosphere DBP degrading strain Rhodococcus sp. 5A-K4 can be used as a bacterial agent in the development of phytoremediation methods for soils contaminated with phthalates.

Glaciolacustrine sedimentary pattern of the Eastern White Sea area during the MIS 2

New data on the distribution and age of glaciolacustrine deposits on the Zimny, Abramovsky, Lyamitsky and Tersky shores of the White Sea are presented. It was possible to trace the dynamics of the glaciation development in the studied area during the LGM, as well as to reconstruct the stages of transition of the White Sea basin from the glacier to the sea basin. The glaciolacustrine sediments of the Abramovsky shore characterise the stage of glaciation onset, while those of the Zimny shore - the initial stage of glacier degradation, when a series of small proglacial water bodies adjoined its marginal zone. The glaciolacustrine sediments studied on the Lyamitsky and Tersky shores were formed in large proglacial lakes that immediately preceded the penetration of the Barents Sea waters into the White Sea basin, as a result of which its gradual salinisation occurred and marine sedimentation began.

Microplastic release and sulfate reduction response in the early stage of a simulated landfill

Landfills are essential facilities for treating and disposing municipal solid waste. They emit sulfur-containing odors and serve as an important sink for a new type of pollutant called microplastics (MPs). This study focused on the initial stage of anaerobic degradation to establish the relationship between the release of MPs and odor generation. Our findings show the rapid release of MPs into the leachate in the early stage of landfill and their predominant accumulation in the leachate sediment. The circulating leachate contained 1.45 times higher concentrations of MPs than the noncirculating leachate, with a peak concentration of 39 items·L−1. In addition, fragmentation of MPs occurred. The percentage of MPs with particle sizes of 2.5–5 mm decreased from 66.70 % to 22.32 %, while those measuring 0.1–0.5 mm increased by 33.12 %. A positive correlation was observed between MP release and sulfate reduction. Although leachate circulation increased the release of MPs, it also reduced the overall release time and total amount of MPs exported from the landfill. Compared with the initial landfill waste, the leachate operation mode, regardless of circulation, resulted in a 6.15–8.93-fold increase in MP release. These findings provide a valuable foundation for the simultaneous regulation of traditional pollutant odor and new pollutants (MPs) in landfills.

Enzymatic degradation mechanism of the lamellar stacking structures of poly([R]-3-hydroxybutyrate-co-[R]-3-hydroxyvalerate) fibers

Enzymatic degradation of the lamellar stacking structures of two types of poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] melt-spun fibers (undrawn and drawn fibers) was analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM images of undrawn fibers showed that enzymatic degradation proceeded from the amorphous regions of spherulites on the surface and in the interior of the fibers. In addition, the lamellar crystals of undrawn fibers unraveled when the amorphous regions between the lamellar crystals were preferentially degraded. In contrast, on the drawn fibers, periodic stacking structures of lamellar crystals with a thickness of approximately 300 nm were observed at the initial stage of degradation. Some of these lamellar stacking structures were connected in the drawing direction. Furthermore, SEM images showed that the periodic lamellar stacking structures with thickness of approximately 2 µm appeared as degradation proceeded. TEM images showed that the lamellar crystals of the periodic stacking structures did not unravel at the enzymatic degradation front because the amorphous regions and lamellar crystals were degraded simultaneously, which was attributed to the strong connection between the lamellar crystals of the periodic lamellar stacking structures through tie molecules.

Operation stage division and RUL prediction of bearings based on 1DCNN-ON-LSTM

Remaining useful life (RUL) prediction of bearings is significantly important to ensure reliable operation of bearings. In practice, it is routinely impossible to obtain the full life cycle degradation data of bearings that needs to be used in prediction. The accuracy of the RUL prediction of bearings is often affected by incomplete degradation data. Regarding this situation, this paper proposes a multi-sensor three-stage RUL prediction framework based on the one-dimensional convolutional ordered neuron long short-term memory (1DCNN-ON-LSTM) neural network. Firstly, 1DCNN is used to extract spatial features adaptively from multi-sensor’s data and fuse them into one-dimensional feature. Next, the unsupervised hierarchy mechanism of time series information based ON-LSTM is developed to determine the ‘initial degradation stage point’ and ‘rapid degradation stage point’ of the bearing from the one-dimensional feature. Once the signal features collected by sensors input to the model reach the degradation stage point, select the corresponding sensitive features as input and construct the 1DCNN-ON-LSTM model that performs RUL prediction after the degradation stage point to improve the prediction accuracy of the model. Based on the proposed hierarchy mechanism, the bearings’ operation process is divided into three operation stages: normal stage, initial degradation stage and rapid degradation stage. Finally, the experiments verify that the proposed method can effectively divide the operation stages of bearings to predict the RUL and improve the generalization ability and prediction accuracy of the model.

Stability of Y2O3:Tm,Yb phosphor thin films during cathodoluminescence and upconversion

An Y2O3:Tm,Yb thin film was synthesized by the sol-gel method using spin coating. X-ray powder diffraction revealed the formation of a Y2O3 cubic phase. The cathodoluminescence and upconversion photoluminescence of the film were investigated, including assessment of emission stability. Auger electron spectroscopy was used to monitor its chemical state concurrently with the cathodoluminescence intensity using the same electron beam. Auger peaks associated with carbon, yttrium and oxygen were detected and their Auger peak-to-peak heights indicated that carbon was removed from the surface during the initial stage of degradation, whereas yttrium and oxygen remained almost unchanged. The cathodoluminescence degradation of the Tm emissions at 457 nm and 975 nm exhibited a continuous decline until the electron dose was about 100 C/cm2 and then stabilized. The upconversion photoluminescence intensity of the Tm emission at 488 nm remained stable for a period of 28 h and did not exhibit degradation.

Integrated physiological characteristics and temporal transcriptomic analysis reveal the molecular mechanism of Pseudomonas aeruginosa degrading diesel stimulated by extracellular metabolites of euglena

Diesel pollution poses a serious threat to the ecological environment. Adding environmentally friendly biostimulants to enhance the metabolic function of indigenous microorganisms is currently a preferred strategy to improve remediation efficiency. In this study, cell morphology, physiological characteristics, and molecular level analysis of Pseudomonas aeruginosa LNR1, which was screened from oil-contaminated soil and has a diesel degradation effect, were investigated to elucidate the stimulus mechanisms by which extracellular metabolites of euglena (EME) acting as a biostimulant. The electron microscopy results indicated that EME could restore the bacterial morphological structure. Physiological analysis revealed that EME not only promoted bacterial proliferation and the secretion of extracellular proteins and polysaccharides, but also enhanced electron transfer activity and ATP content. Genomic indicated that strain LNR1 had the potential to degrade diesel efficiently. Transcriptome analysis showed that the stimulating effect of EME on strain LNR1 was distinction at different degradation time points. The initial degradation stage mainly affected the decomposition of polysaccharide and detoxification, while the active degradation stage mainly induced biochemical metabolic processes, such as amino acids and organic substrates. In particular, the expression of a series of functional genes related to pollutant emulsion adsorption, transmembrane transport, signal transduction (quorum sensing, two-component system, chemotactic system) and degradation genes was up-regulated. This study comprehensively revealed the mechanisms by which the biostimulant EME enhanced diesel degradation in strain LNR1 from multiple perspectives. It provides theoretical guidance for the practical application of EME in bioremediation, offering significant societal and economic benefits.