Chemical exposure and local hypoxia caused by mask-wearing may result in skin physiology changes. The effects of methylparaben (MeP), a commonly used preservative in personal care products, and ...hypoxia on skin health were investigated by HaCaT cell and ICR mouse experiments. MeP exposure resulted in lipid peroxidation and interfered with cellular glutathione metabolism, while hypoxia treatment disturbed phenylalanine, tyrosine, and tryptophan biosynthesis pathways and energy metabolism to respond to oxidative stress. A hypoxic environment increased the perturbation of MeP on the purine metabolism in HaCaT cells, resulting in increased expression of proinflammatory cytokines. The synergistic effects were further validated in a mouse model with MeP dermal exposure and “mask-wearing” treatment. CAT, PPARG, and MMP2 were identified as possible key gene targets associated with skin health risks posed by MeP and hypoxia. Network toxicity analysis suggested a synergistic effect, indicating the risk of skin inflammation and skin barrier aging.
•Hypoxia exacerbated the lipid peroxidation in normal keratinocytes caused by MeP exposure.•Hypoxia increased the interference of MeP on purine metabolism pathway of HaCaT cell and ICR mouse.•Hypoxia elevated MeP-induced oxidative damage and skin pro-inflammatory risk.•Network toxicity revealed CAT, PPARG and MMP2 as the possible key genes for MeP and hypoxia synergistic effect.
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•Effect of S. baltica on texture and flavour of golden pomfret were investigated.•S. baltica decreased fish hardness, and the storage and loss moduli of proteins.•MHC, MyBP-C and ...actin were degraded by S. baltica.•S. baltica produced dimethyl sulfide, 2-methyl-butanal and 3-methyl-butanal.
Shewanella baltica has a high spoilage ability to decompose nutrients in fish. To investigate the role of S. baltica in fish protein and flavour during spoilage, the texture, rheology, protein patterns and volatile compounds of golden pomfret inoculated with S. baltica during 10-day storage were tested. During storage, S. baltica reduced the hardness of fish sticks by 29.73–49.24 %. Compared to the control (G0′: 20.27 ± 2.15 kPa), inoculated samples showed lower moduli (G0′: 16.71 ± 0.82–17.50 ± 1.80 kPa). Their myosin heavy chains, myosin-binding protein C and actin were decomposed into smaller proteins, which was validated by the lower intensities of molecules with Mw 160–176 kDa. Furthermore, S. baltica generated volatile spoilage markers, including dimethyl sulfide, 2-methyl-butanal and 3-methyl-butanal. This study reveals the mechanism of fish texture and flavour changes induced by S. baltica, and provides insights into controlling bacterial spoilage of seafood.
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•Nanoemulsified clove essential oil (NCEO)-fish gelatin (FG) was prepared.•NCEO-FG inhibited the growth of Pseudomonas spp. on fillets.•NCEO-FG effectively delayed the deterioration ...of tilapia fillets.•NCEO-FG disturbed metabolisms of Pseudomonas spp.•Pseudomonas spp. developed a defense system within 24 h.
Fish products suffer Pseudomonas-causing spoilage quickly during refrigeration storage, which could be solved by applying edible coating derived from nanoemulsified clove essential oils and fish gelatin (NCEO-FG). This study aimed to evaluate the effects and mechanism of NCEO-FG in preserving tilapia (Oreochromis niloticus) fillets that were inoculated with Pseudomonas spp. (Pseudomonas sp. strain ABa3, P. psychrophila strain ABe3, and P. fragi strain BBa3). NCEO caused remarkable leakage of proteins (198.5–252.8 μg/L) and nucleic acids (0.30–0.34 of OD260). After being incorporated into FG, NCEO-FG effectively delayed the deterioration of tilapia fillets because it significantly reduced the surviving bacteria populations (0.78 – 1.80 log CFU/g reductions) and inhibited the proteolysis and oxidation during cold storage. Further, the metabolic responses of NCEO-FG coated Pseudomonas spp. were revealed using NMR spectroscopy: the reducing levels of metabolites (e.g., pyruvate, amino acids, and betaine) suggested that the NCEO-FG disturbed energy and amino acid metabolisms of bacteria cells. However, the levels of metabolites (e.g., amino acids and osmoprotectants) were upregulated after 3 h and then back to normal concentration after 24 h, which indicated a defense system was built in bacterial cells to tolerate NCEO-FG. In short, this study confirmed that NCEO-FG could control the Pseudomonas-causing spoilage in fish fillets via elucidating the metabolisms.
Although next-generation sequencing technology has been used to delineate RNA modifications in recent years, the paucity of appropriate converting reactions or specific antibodies impedes the ...accurate characterization and quantification of numerous RNA modifications, especially when these modifications demonstrate wide variations across developmental stages and cell types. In this study, we developed a high-throughput analytical platform coupling ultra-performance liquid chromatograph (UPLC) with complementary mass spectrometry (MS) to identify and quantify RNA modifications in both synthetic and biological samples. Sixty-four types of RNA modifications, including positional isomers and hypermodified ribonucleosides, were successfully monitored within a 16-min single run of UPLC–MS. Two independent methods to cross-validate the purity of RNA extracted from Caenorhabditis elegans (C. elegans) were developed using the coexisting C. elegans and Escherichia coli (E. coli) as a surveillance system. To test the validity of the method, we investigated the RNA modification landscape of three model organisms, C. elegans, E. coli, and Arabidopsis thaliana (A. thaliana). Both the identity and molarity of modified ribonucleosides markedly varied among the species. Moreover, our platform is not only useful for exploring the dynamics of RNA modifications in response to environmental cues (e.g., cold shock) but can also help with the identification of RNA-modifying enzymes in genetic studies. Cumulatively, our method presents a novel platform for the comprehensive analysis of RNA modifications, which will be of benefit to both analytical chemists involved in biomarker discovery and biologists conducting functional studies of RNA modifications.
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•UPLC-MS platform was developed for monitoring 64 RNA modifications.•Purity of eukaryotic RNA samples was cross-validated by UPLC-MS and RT-qPCR assays.•Global RNA modification landscapes of model organisms were investigated.•Dynamics of RNA modification landscape in response to cold shock was monitored.•Gene tgt-1 encodes a queuosine-modifying enzyme in C. elegans genome.
Epidemiological and experimental data have associated exposure to fine particulate matter (PM2.5) with various metabolic dysfunctions and diseases, including overweight and type 2 diabetes. Adipose ...tissue is an energy pool for storing lipids, a necessary regulator of glucose homeostasis, and an active endocrine organ, playing an essential role in developing various related diseases such as diabetes and obesity. However, the molecular mechanisms underlying PM2.5-impaired functions in adipose tissue have rarely been explored. In this work, metabolomics based on liquid chromatography-mass spectrometry was performed to study the adverse impacts of PM2.5 exposure on brown adipose tissue (BAT) and white adipose tissue (WAT) in the diabetic mouse model. We found the effects of PM2.5 exposure by comparing the different metabolites in both adipose tissues of male db/db mice using real-ambient PM2.5 exposure. The results showed that PM2.5 exposure changed the purine metabolism in mice, especially the dramatic increase of xanthine content in both WAT and BAT. These changes led to significant oxidative stress. Then the results from real-time quantitative polymerase chain reaction showed that PM2.5 exposure could cause the production of inflammatory factors in both adipose tissues. Moreover, the increased reactive oxygen species (ROS) promoted triglyceride accumulation in WAT and inhibited its decomposition, causing increased WAT content in db/db mice. In addition, PM2.5 exposure significantly suppressed thermogenesis and affected energy metabolism in the BAT of male db/db mice, which may deteriorate insulin sensitivity and blood glucose regulation. This research demonstrated the impact of PM2.5 on the adipose tissue of male db/db mice, which may be necessary for public health.
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•The impacts of PM2.5 exposure on both WAT and BAT of diabetic mice were studied.•Exposure to PM2.5 increased xanthine (precursor of uric acid) and ROS production.•PM2.5 promoted lipogenesis and inhibited lipolysis in the WAT of male db/db mice.•Thermogenesis in the BAT of male db/db mice was impaired after PM2.5 exposure.•Xanthine-derived ROS mediated the PM2.5-caused adipose tissue dysfunction in male db/db mice.
The effects of surface roughness on the vortex-induced vibration (VIV) of a flexible cylinder have been studied experimentally. The drag, lift, tension, vortex-shedding frequency, vibration ...frequency, and displacement response of cylinders with different roughnesses are compared. The results indicate that a pure VIV lock-in phenomenon occurs in the in-line direction earlier than in the cross-flow direction, and thus the VIV response in the in-line direction is larger than in the cross-flow direction in the low-reduced-velocity range. The tension in the cylinder has two peak frequencies. One peak is the dominant frequency, which coincides with the dominant frequency of the drag and is induced by the VIV in the in-line direction. The other peak is at half of the dominant frequency, at the dominant frequency of the lift; it is caused by the VIV in the cross-flow direction. Rough cylinders have a smaller displacement response, a narrower lock-in region, and a higher vortex-shedding frequency than a smooth cylinder.
•The displacements of flexible cylinders with different surface roughnesses were studied.•The hydrodynamics of flexible cylinders with different surface roughnesses were considered.•The lock-in regions of flexible cylinders with different surface roughnesses were discussed.•The relationships between the drag coefficients and the displacements were researched.
•Wake interference between two tandem offshore floating VAWTs is investigated.•Effect of platform pitch motion on power and wake of floating turbine array is evaluated.•Parametric analysis of effects ...of varied pitch characteristics is performed.•Mechanism of pitch motion alleviating negative effect of wake interference is revealed.•Provide a basic reference for designing offshore floating wind farms.
The wake interference within the offshore wind farms, especially with the tandem arrangement scenario, affects the designed total power output. Also, the six degrees of freedom motions of the platforms not only can change the aerodynamics of the offshore floating wind turbines, but also may influence the wake interference between them. In the present study, the effect of the platform pitch motion on the wake interference between two tandem offshore floating vertical-axis wind turbines (VAWTs) is characterized using the improved delayed detached-eddy simulation (IDDES). First, the power performance of the downstream turbine (VAWT Ⅱ) at different separation distances, 2D ≤ LS ≤ 10D, and tip speed ratios, 0.4 ≤ TSRⅡ ≤ 1.5, are analyzed, assuming that the upstream turbine (VAWT Ⅰ) is bottom-fixed and operates at an optimal TSRⅠ of 1.2. Then, the effects of the pitch amplitude, 5° ≤ APⅠ ≤ 15°, and pitch period, 2TⅠ ≤ TPⅠ ≤ 8TⅠ, on the wake interference are characterized by assuming that the platform pitch motion of VAWT Ⅰ follows a prescribed simple harmonic law. The results show that locating VAWT Ⅱ in the medium wake region of VAWT Ⅰ, e.g., LS = 6D, can appropriately balance the power performance and space cost of the bottom-fixed turbine array. Also, the platform pitch motion can reduce the mean velocity deficit in the core wake region of VAWT Ⅰ. The mean wake deficit reduction increases the averaged power coefficient of VAWT Ⅱ, e.g., up to 22.67% when LS = 6D, TSRⅡ = 1.2, APⅠ = 15°, and TPⅠ = 4TⅠ. In addition, relatively larger pitch amplitudes and smaller pitch periods will further alleviate the negative effect of the wake interference. This study may serve as a reference for designing offshore floating wind farms.
The drag force coefficients of a flexible riser undergoing vortex-induced vibration (VIV) in sheared flow are investigated for Reynolds numbers (Re) up to 1.2×105. Based on the drag forces ...theoretically calculated by the beam theory using the strains measured in a scale model test, the properties and distribution of the drag coefficients are investigated, and a new empirical model for estimating the drag coefficient on a flexible riser undergoing VIV is proposed. The results show that VIV leads to non-uniform distribution of the drag coefficient and amplifies the drag coefficient, and the local drag coefficient can reach up to 3.2. For Re values from 1.0×104–1.2×105, the mean drag coefficient is between 1.3 and 2.0 and decreases as Re increases. Furthermore, the empirical drag coefficient prediction model obtained from experiments under low Re is not suitable for high Re. The corrected empirical prediction model, which accounts for the effect of the flow velocity, the VIV dominant mode number and the dominant frequency, can be used to predict riser drag coefficients under VIV more accurately at high Re values up to 1.2×105.
•Drag coefficients for flexible risers under VIV were experimentally investigated.•VIV amplifies drag coefficients. Local drag coefficient of risers can reach 3.2.•Drag coefficient is between 1.3 and 2.0, and decreases as Re increases.•An empirical prediction model is proposed for estimating the drag coefficient.
Virtual instrument technology has been increasingly used in university physics experiment teaching. An experimental platform is specifically constructed for studying low-frequency vibrations in ...university physics, which is based on a computer and its internal sound card, along with a program developed in LabVIEW programming environment to perform control and measurement on our experimental platform. The proposed platform effectively replaces the conventional signal generator and oscilloscope traditionally used in such experiments by integrating virtual instruments and essential experimental equipment. The platform offers various functionalities, such as synchronous transmission and reception of low-frequency signals, frequency measurement, dynamic frequency sweep measurement, and measurement using the three-point approximation method. The proposed platform has been successfully applied in experiments involving forced vibration, resonance of tuning forks, and dynamic measurement of Young's modulus. Unlike conventional low-frequency vibration experiments, the proposed experimental platform optimizes efficiency, reduces costs, and offers opportunities for enhancing the instructional content of experiments. Furthermore, the incorporation of state-of-the-art computer technology enhances students' engagement and enthusiasm for learning.
