Kriging surrogate model has extracted extensive attention in reliability evaluation, owing to its excellent applicability and operability nowadays, which confronts with difficulties in balancing the ...efficiency and accuracy for complicated mechanical assets with multiple failure modes. Consequently, this paper devises a multi-performance reliability analysis approach within the surrogate model framework, particularly innovative in its use of cluster mixing weight. Specifically, high-value test points are selected to fit the surrogate model after sorting the samples referring to the corresponding values; then, a cluster-based active learning strategy is employed to accomplish rapid convergence, and the particle swarm algorithm is utilized to optimize relevant parameters. Afterwards, the mixing weight for every performance referring to the contributions to the final reliability is determined, and the failure probability is subsequently predicted. Furthermore, the superiority of the proposed approach with the clustering surrogate model and mixing weight, compared with traditional sampling as well as other surrogate models, has been verified via case studies, contributing to overcoming the multi-performance reliability analysis oriented to complicated mechanical assets.
The aging process and leachate composition of different types of MPs (PS, PS-NH2, PS-COOH and PMMA) with a particle size of 1.0 μm were characterized, and marine microalgae Isochrysis galbana ...OA3011(I. galbana) was used as test organism to investigate the 96 h toxic effects of MPs before and after aging as well as leachate exposure. Except for polymethyl methacrylate (PMMA), all other tested microplastics showed significant aggregation in seawater, which increased with the presence of surface amino and carboxyl groups, in addition, the increase in polymer dispersibility index (PDI) values after aging reflected more severe aggregation. Fourier transform infrared spectrometer (FTIR) showed that the surface amino groups were shed during the aging of PS-NH2, which can likewise be demonstrated by the change in surface electric potential from positive to negative before and after aging. PMMA, due to the addition of plasticizers (HEHP and DIBP detected in high concentration) and its own structure, has stronger resistance to aging than the other three microplastics, and no significant aging phenomenon occurs. As for I. galbana, growth inhibition, oxidative stress and energy metabolism were tested after exposure to different microplastics and their leachate. It was found that high concentrations of A-PS had a greater negative impact on I. galbana, while the toxic effects of PS-NH2 and PS-COOH on I. galbana behaved in a diametrically opposite way before and after aging compared to PS with the inhibitory effect decreasing after aging, which was caused by the shedding of surface groups. As for PMMA, the differences in the toxic effects on microalgae before and after aging were not significant. The inhibitory effect of low concentrations of PAEs (Phthalate acid esters) in the leachate of PS-COOH on I. galbana was not significant, and the stronger inhibitory effect of 4 d L-PS-NH2 was presumed to be the shedding of positively charged groups.
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•The effects of four pristine and aging microplastics (PS, PS-NH2, PS-COOH and PMMA) and their leachates on the growth, oxidative stress and energy metabolism of I. galbana were investigated.•PS-NH2 and PS-COOH are less toxic to I. galbana after aging due to shedding of functional groups.•The harm degrees of different types of microplastics to I. galbana are different before and after aging.•The leachates have toxic effect on I. galbana.
In this study, Gymnodinium aeruginosum was exposed to polystyrene (PS) and polymethyl methacrylate (PMMA) of three particle sizes (0.1 μm, 1.0 μm and 100 μm) and two concentrations (10 mg/L and ...75 mg/L) for 96 h. The density of algae cells, the endpoints that reactive oxygen species (ROS), total protein (TP), malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT), scanning and transmission electron microscopy (SEM and TEM) were used to explore the toxicity mechanism to the microalgae. At a concentration of 75 mg/L, the 96 h inhibition ratios (IR) with particle sizes of 0.1 μm, 1.0 μm and 100 μm on G. aeruginosum were 55.9%, 63.7% and 6.0% for PS, respectively, and 3.0%, 4.1% and ‐0.6% for PMMA, respectively. The most significant changes in ROS, TP, MDA, SOD and CAT were observed at 75 mg/L 1.0 μm of PS when treated for 96 h. When exposed to nanoplastics (NPs) and microplastics (MPs), the algae cells were damaged, and the antioxidant system was activated. Extracellular polymeric substance (EPS) could help to detoxify the algae. In general, PS was more toxic than PMMA. The toxicity of small MNPs (0.1 μm and 1.0 μm) was related to the concentrations, while large MNPs (100 μm) did not.
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•PS is more toxic than PMMA as the toxicity of microplastics was associated with their density.•The toxicity of small MNPs (0.1 μm and 1.0 μm) was related to their concentration while large MNPs (100 μm) not.•Prolonged exposure to MNPs produces no cumulative adverse effect.•Extracellular polymeric substance could help to detoxify the microalgae.•Oxidative stress in microalgae was aroused and the antioxidant system was activated when exposed to MNPs.
It was found that the toxicity of microplastic was related to their density with a fact that prolonged exposure to microplastics produces no cumulative adverse effect.
The acute toxic effects of pristine and aged polystyrene (P-PS and A-PS) and their leaching solutions (L-PS) on microalgae Skeletonema costatum were investigated by measuring algal density and growth ...inhibition rate (IR), chlorophyll concentration and photosynthetic efficiency (Fv/Fm) over 96 h. Total protein (TP), superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) were measured to analyze the oxidative damage to microalgae by microplastics and their leachates. Hydrodynamic diameter of microplastics in seawater, FITR and SEM images were used to study the changes of polystyrene during aging. The interaction of algae cell with microplastics and the cellular ultrastructure changes of cells were analyzed combined with electron microscopy for a comprehensive and systematic understanding on the mechanisms of microplastic toxicity to microalgae. Both high concentration and small size of PS had significant inhibitory effect on the growth of microalgae, and the inhibitory effect was greater with increasing exposure time. The inhibition effect of aged microplastics was more obvious, which was speculated to be caused by the synergistic effect of aged PS itself and leaching solution. The negative effect of leaching solution on microalgae was due to the release of some additives during the aging process. The content of MDA reached the highest value of 54.41 nmol/mgprot in 1.0 μm 50 mg/L A-PS treatment group, and A-PS were found to be more prone to heterogeneous aggregation with algae cells by SEM.
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•The effects of pristine and aged polystyrene (P-PS and A-PS) and their leachate (L-PS) on S. costatum were evaluated.•Smaller particle size and higher concentration of microplastics have greater growth inhibition on S. costatum.•The aged polystyrene (A-PS) were more toxic.•The greater toxicity of aged polystyrene (A-PS) due to the combined effect of the plastic itself and its leaching solution.
•The similar toxic mechanism of nSiO2 and mPS with similar hydrodynamic diameters on H. akishiwo suggested that hydrodynamic diameter was more important than nominal size for the toxic effect.•The ...effects of micro-/nano-particles on microalgae are dose- and time- dependent, inducing a similar process of producing excess reactive oxides and activating cellular defensive systems.•The micro-/nano-particles caused damage to cell membranes, leading to cytoplasmic and organelle efflux.•Surface functional groups of micro-/nano-particles were slightly less influential factor than size of particles.
To investigate the toxic mechanism of SiO2 nanoparticles (nSiO2) and polystyrene microplastics (mPS) on microalgae Heterosigma akashiwo, growth inhibition tests were carried out. The growth and biological responses of the algae exposed to nSiO2 (0.5, 1, 1.5, 2, 5, 10 and 30 mg L−1) and mPS (1, 2, 5, 10, 30 and 75 mg L−1) were explored in f/2 media for 96 h. It was found that the hydrodynamic diameter of the particles seems to be one of the more important factors to influence the algae. nSiO2 and mPS with similar hydrodynamic diameters have the similar toxic mechanism on H. akashiwo, and the effects were dose- and time-dependent. High concentrations of micro-/nano-particles (MNPs) could inhibit the growth of algal cells, however, low concentrations of MNPs did not restrict or even promoted the growth of algae, known as “Hormesis” phenomenon. The 96 h-EC20 values of nSiO2 and mPS on H. akashiwo were 2.69 and 10.07 mg L−1, respectively, and chlorophyll fluorescence parameters indicated that the microalgal photosynthetic system were inhibited. The hydrophilic surface of nSiO2 increased the likelihood of nSiO2 binding to the hydrophilic functional group of microalgae, which may account for the slightly stronger toxic effect of nSiO2 than mPS. The algae continued to produce reactive oxygen species (ROS) under stress conditions. Total protein (TP) levels reduced, and superoxide dismutase (SOD) and catalase (CAT) levels increased to maintain ROS levels in the cells. The decrease in adenosine triphosphate (ATPase) indicated an impact on cellular energy metabolism. Cell membrane damage, cytoplasm and organelle efflux under stress were confirmed by scanning and transmission electron microscopy (SEM and TEM) images. This study contributes to the understanding of the size effect of MNPs on the growth of marine microalgae.
The developmental origins of health and disease concept highlights the impact of early environments on chronic non-communicable diseases like diabetes, cardiovascular disease, and cancer. Studies ...using animal models have investigated how maternal factors such as undernutrition, overnutrition, obesity, and exposure to chemicals or hypoxia affect fetal development and offspring health, leading to issues like low birth weight, high blood pressure, dyslipidemia, and insulin resistance. Given the increasing prevalence of overweight and obesity among reproductive-age women, effective interventions are critical. Maternal exercise during pregnancy has emerged as a key intervention, benefiting both mother and offspring and reducing the risk of disease. This study compares the differences of three exercise models on pregnant rats: voluntary wheel running, motorized treadmills, and swimming. Swimming is the most beneficial option due to its safe and controlled intensity levels. This protocol details the rat breeding methods, swimming training during pregnancy, and post-breeding nursing protocols. This model, suitable for various rat and mouse species, is useful for studying the benefits of maternal exercise on offspring health and intergenerational wellness.
Herein, we report a novel ultrasensitive upconversion intense red fluorescence and colorimetric dual-readout strategy for the determination of alkaline phosphatase (ALP) that initially integrates ...enzyme-triggered cascade signals amplification (ECSAm) with rapid fusing reaction of label-free silver triangular nanoplates (AgTNPs). The sensing strategy involves four aspects. Firstly, AgTNPs with an absorption band at ∼610 nm was synthesized, which can effectively quench upconversion nanoparticles (UCNPs) fluorescence at 670 nm through the fluorescence resonance energy transfer (FRET). Secondly, when in the presence of ALP, l-ascorbic acid 2-phosphate (AAP) was transformed into ascorbic acid (AA) which can react with KIO3 to produce I2. Thirdly, the procreant I2 can quickly adsorb onto the surface of AgTNPs, then etch AgTNPs and the I2 is reduced to I−. Fourthly, the generated I− can further accelerate the fusion of AgTNPs by adsorption effect, which helps achieve ECSAm, allowing the quantitative evaluation of ALP with a satisfying detection limit of 0.035 mU/mL. In addition, the developed method has been further applied to the detection of ALP in human serum with satisfactory results. These results indicate that the dual-readout assay with a well-defined response mechanism shows good prospects in physiological and pathological studies.
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•A upconversion red fluorescent and colorimetric assay for detection of alkaline phosphatase (ALP) activity was designed.•The dual-readout assay was based on enzyme-controlled cascade signals amplification (ECSAm) strategy.•The ECSAm strategy make the bioanalytical system superior to the routine method in sensitivity and selectivity.•The proposed method has been applied to the analysis of ALP in human serum samples.•The present research gives new insight into design of ultrasensitive detection of ALP.
Due to similar charges, atomic radii, and chemical properties of most metal ions, the selective sensing of these metal ions and imaging in vivo is still a challenge. A DNAzyme assemblied and ...near-infrared (NIR) light excited nanosensor was developed to detect and image Pb2+. In this nanosensor, NaYF4:Yb, Er upconversion nanoparticles (UCNPs) introduced as NIR-to-Vis transducer were the donor of luminescence resonance energy transfer (LRET), and DNAzyme-functionalized black hole quencher 1 (BHQ1) acted as energy transfer acceptor. This proposed nanosensor was applied to detecting Pb2+ in solution with high sensitivity and selectivity. Furthermore, we have successfully demonstrated the imaging ability of this nanosensor towords Pb2+ in living cells and early-stage zebrafish with negligible autofluorescence and good photostability. The UCNP-DNAzyme nanosensor would enrich the method of imaging Pb2+ in vivo, and might serve as a potential tool for understanding the metabolic pathways of Pb2+ and the mechanism of lead poisoning in biological system.
A sensitive and selective nanosensor was developed to detect Pb2+ and image it in living cells and early-stage zebrafish based on LRET from NaYF4:Yb, Er UCNPs to DNAzyme-functionalized BHQ1 quencher. Display omitted
•A promising nanosensor for Pb2+ based on LRET from NIR light excited UCNPs to DNAzyme-functionalized BHQ1 quencher has been developed.•The highly sensitive and selective UCNP-DNAzyme nanosensor showed superior performance for in vitro Pb2+ detection.•The UCNP-DNAzyme nanosensor was successfully applied to imaging Pb2+ in living cells and in early-stage zebrafish.
Abstract The three key properties required for microwave dielectric ceramics are suitable dielectric constant ( ε r ), high quality factor ( Q × f ), and near‐zero temperature coefficient of ...resonant frequency ( τ f ). Due to the intricate coupling relationship among these three properties, regulating one often leads to the deterioration of the remaining two. In this study, the synergetic regulation of dielectric properties of Ca 0.7 Nd 0.2 TiO 3 was investigated to reduce τ f to near‐zero while maintaining its high ε r by A‐ and B‐site substitutions. To avoid the seesaw effect and improve the efficiency of composition optimization, machine learning method was introduced in this study. First, the models for predicting dielectric properties were fitted based on a small amount of high‐quality data gathered via a uniform experimental design. Then the dielectric properties of 1037 compositions of (Ca 0.7 Nd 0.2 ) 1− x (Li 0.5 Nd 0.5 ) x Ti 1− y (Mg 1/3 Nb 2/3 ) y O 3 were predicted, from which 69 microwave dielectric ceramics with near‐zero τ f and adjustable ε r of 95–125 were quickly picked out, and 5 of them were proved by experiments with very high prediction accuracy. This work was finished within a period of 1 month, which proves the obvious acceleration of composition designing process of microwave dielectric ceramics with the aid of machine learning.
