Longer Exposure Times Research Articles

In vitro Antileishmanial Effect of Scrophulariabavanatia Extract on Leishmania (L) tropica [MHOM/NADIM3

Background: Cutaneous Leishmaniasis (CL) is a widespread parasitic disease that causes skin lesions and ulcers. Although the World Health Organization recommends Glucantime as a treatment for CL, this remedy presents unexpected side effects and high costs. This study investigates the in vitro antileishmanial effect of Scrophulariabavanatia hydroalcoholic extract on Leishmaniatropica promastigotes. Objectives: This study aims to evaluate the in vitro antileishmanial effects of a local Scrophulariabavanatia hydroalcoholic extract on Leishmania (L.) tropica [MHOM/NADIM3] promastigotes. Methods: Various concentrations (0.2, 1, 5, 25, and 125 mg/mL) of Scrophulariabavanatia methanol extract were prepared and added to cultures containing the parasite. The amastigote form of the L. tropica strain [MHOM/IR/NADIM3] was isolated from mouse spleens and transformed into promastigotes in Novy-Nicolle-Mac Neal medium. The antileishmanial activity of Scrophulariabavanatia extract was then compared to Glucantime using cell proliferation ELISA. Results: The LC50 values in the stationary stage for both Scrophulariabavanatia extract and Glucantime (mg/mL) were greater than in the dynamic stage. The extract at concentrations of 0.2, 1, 5, 25, and 125 mg/mL did not show significant differences after 24 and 48 hours (P > 0.05) compared to negative controls but did show a significant effect after 72 hours (P = 0.000). The extract demonstrated increased effectiveness with higher concentrations and longer exposure times. Conclusions: Scrophulariabavanatia extract inhibits the survival and growth of Leishmania promastigotes. Future studies should further explore its effects on in vivo survival of the parasite.

Mechanical Properties and Microstructural Characteristics of Steel Pipes after Long-Time Hydrogen Exposure

There are three possibilities to transport hydrogen by high pressure pipeline (i) blending hydrogen into the existing natural gas pipeline system, (ii) after checking the integrity, using the natural gas transporting pipeline system to transport hydrogen, (iii) building a new pipeline system to transport pure hydrogen. In all three cases should be known the behaviour of the pipe material and its welded joints influenced under high pressure hydrogen. For this aim pipeline sections made of P355NH base material were investigated without and with hydrogen exposure, where the exposure time was 41 days. Gas metal arc welding and hybrid tungsten arc welding / gas metal arc welding were applied for preparation of the girth weld joints. Tensile, three point bending and hardness tests, furthermore microstructural investigations were performed both on base materials and girth welds of the pipeline sections. The testing results were analysed and compared with each other (base material vs. welded joints, without exposure vs. with exposure) and with limit values can be found in the literature. Conclusions were drawn on the behaviour of the investigated pipe material and its welded joints.

Quantifying motion blur by imaging shock front propagation with broadband and narrowband X-ray sources

Time-integrated radiography using MeV Bremsstrahlung X-ray sources is the norm for imaging during system-level testing of components and structures under dynamic condition. One source of error in the analysis of the time-integrated radiography data sets stems from motion blur which smears out sharp interfaces to a greater degree with longer exposure times, which become necessary to provide sufficient signal-to-noise with low X-ray penetration of objects of interest. To quantify motion blur, a 1D shock wave through PMMA was investigated experimentally at The Dynamic Compression Sector at The Advanced Photon Source (DCS@APS) with tapered broadband and 25.46 ± 1.06 keV narrowband X-rays. Four cameras with different exposure times were used for each experiment to compare the effect that exposure time has on motion blur. In addition, our methodology to accurately simulate motion blur in terms of transmission and shape is presented and compared to our experimental results and quantified. There is a high level of agreement between the experimental and simulation results across the range of data sets investigated in this study with a percent difference range of 0.29–1.31% for the four shots. The methodology of this work serves as a steppingstone towards a physically validated model that could be used in conjunction with experimental results to deconvolve physical parameters, densities, and interfaces of interest in a way that would not be possible with experimental results alone.

The Harmful Effects of Welding Fumes on Human Dental Enamel-A Microhardness Analysis.

Introduction: Over the years, welding fumes' harmful effects have been demonstrated countless times in the scientific literature. Recently, studies in the field have shown an increasing interest in the negative consequences that these fumes may have on the tissues of the oral cavity. Materials & method: The current study aimed to investigate the impact that welding fumes have on the structure of human dental enamel by analyzing the microhardness of the dental enamel in 15 extracted human teeth, after various exposure times, using the Vickers method. Results: The results obtained after 48, 96, 168, and 336 h of direct exposure of the extracted specimens to the welding fumes show a statistically significant increase in the depreciation of the dental enamel's microhardness, related to the duration of exposure (p < 0.05). An average of 305 Vickers units was observed at the longest exposure time, 336 h, in the present study, whereas in the control group, the microhardness analysis showed an average of 327 Vickers units.

Exposure effects of synthetic glucocorticoid drugs on skeletal developmental and immune cell function in zebrafish

Synthetic glucocorticoids (GCs) are used to treat a wide range of human health conditions and as such are frequently detected in the aquatic environment. This, together with the highly conserved nature of the glucocorticoid system across vertebrates means that the potential for biological effects of GCs in fish is relatively high. Here, we found that exposure of zebrafish (Danio rerio) to environmentally relevant concentrations of 4 of the most widely used synthetic GCs (beclomethasone dipropionate, budesonide, fluticasone propionate, and prednisolone), from 0 to 4 days post fertilisation (dpf), resulted in no effects on embryo-larval development or bone and cartilage formation. However, after exposure to equivalents of human therapeutic plasma levels, developmental abnormalities were observed that included pericardial oedema, blood pooling and alterations in jaw cartilage. Furthermore, using a double transgenic zebrafish osteoblast and chondrocyte reporter line, exposure up to 10 dpf resulted in alterations to lower jaw cartilage and bone development for all compounds at, and above, human therapeutic plasma concentrations. In the case of beclomethasone dipropionate, a reduction in lower jaw intercranial distance was observed at the environmentally relevant concentration of 0.1 μg/L. Using further transgenic reporter lines with fluorescently tagged neutrophils and macrophages, we also show exposure of embryo-larvae (0–4 dpf) to the GCs tested resulted in altered immune cell migration, but only at relatively high exposure concentrations. Collectively, our findings show GC exposure impacts embryo-larval zebrafish development, immune function, and skeletal formation, but predominantly at concentrations greater than those currently reported for the aquatic environment. Despite this, however, it is suggested that studies with longer exposure times, and to mixtures of multiple GCs (many GCs act via the same mechanism of action) are warranted before we can confidently assert that these commonly detected contaminants do not pose a risk to fish in the wild.

Cytotoxicity and genotoxic impacts of LAPONITE® on murine adipose stem cells

This study comprehensively characterized LAPONITE® and evaluated its cytotoxic and genotoxic effects on rat adipose-derived stem cells (ADSCs). Chemical analyses included Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Cytotoxic screening using the Artemia salina lethality test indicated low toxicity. ADSCs exhibited mesenchymal stem cell chracteristics. LAPONITE® demonstrated osteogenic induction capability. MTT assays revealed increased cell viability across concentrations and exposure times. The comet assay for genotoxicity showed no significant differences in damage index between experimental groups, except for a distinction in the frequency of damage between LAPONITE® concentrations at the longest exposure time. This comprehensive assessment provides valuable insights into the safety and potential applications of LAPONITE® in regenerative medicine.

Effect of irradiation on the corrosion of 304 stainless steel in pressurized water reactor (PWR) simulated water chemistry

In this study, the corrosion behavior of pre-ion-irradiated 304 SS is compared to that of un-irradiated 304 SS in simulated Pressurized Water Reactor (PWR) conditions for both early stages of corrosion and longer exposure times. Transmission electron microscopy is used to characterize the oxide scale. The study shows that although the pre-irradiated microstructure does not change the nature of the oxide and its dual-layer structure (i.e. inner/outer oxide layers) formed on 304 SS, the path of growth of the inner oxide layer is affected by the irradiated microstructure resulting in oxide protrusions into the matrix; a mechanism is proposed.

Obtaining Phenolic-Enriched Liquid Fractions and Compostable Pomace for Agriculture from Alperujo Using Standard Two-Phase Olive Oil Mill Equipment

Olive oil extraction by two-phase systems generates a by-product called “alperujo” which presents several difficulties for its valorization. The present work evaluated an industrial approach, based on the application of thermal treatments to alperujo followed by solid/liquid separation using standard two-phase olive oil mill equipment. Treatments consisted of the thermo-malaxation of alperujo at 70 °C for 45 or 90 min, with or without acid addition, followed by solid/liquid separation in an industrial decanter. The solid was characterized concerning subsequent use for composting, while total and hydrophilic phenolics were analyzed in liquid for their recovery. Additionally, a laboratory-scale trial to compare phenolic purification by ethylic acetate extraction with chromatographic procedures was also included. The static respiration index showed that solid fractions presented higher susceptibility to biodegradation processes than raw alperujo. The phenolic content of treated liquid fractions was higher than in raw alperujo. Total phenolics were maximum at the longest exposure time without acid addition, while hydrophilic phenolics were highest at the shortest exposure time in acidified samples. The use of non-ionic resins seemed attractive for obtaining highly concentrated phenolic fractions. The proposed thermal treatments can be applied in olive oil industries, allowing in situ pomace valorization and the recovery of phenolic-enriched liquid fractions.

Electrosynthesis-Induced Pt Skin Effect in Mesoporous Ni-Rich Ni-Pt Thin Films for Hydrogen Evolution Reaction.

A Pt skin effect, i.e., an enrichment of Pt within the first 1-2 nm from the surface, is observed in as-prepared electrodeposited Ni-rich Ni-Pt thin films. This effect, revealed by Rutherford backscattering (RBS), is present for both dense thin films and mesoporous thin films synthesized by micelle-assisted electrodeposition from a chloride-based electrolyte. Due to the Pt skin effect, the Ni-rich thin films show excellent stability at the hydrogen evolution reaction (HER) in acidic media, during which a gradient in the Pt/Ni ratio is established along the thickness of the thin films, while the activity at the HER remains unaffected by this structural change. Further characterization by elastic recoil detection with He ions analysis shows that hydrogen profiles are similar to those of Pt: a surface hydrogen peak coincides with the Pt skin, and a gradient in hydrogen concentration is established during HER in acidic media, together with a considerable uptake in hydrogen. A comparative study shows that in alkaline media, hydrogen evolution has little to no effect on the structural properties of the thin films, even for much longer times of exposure. The mesoporous thin films, in addition to their higher efficiency at HER compared to dense thin films, also show lower internal stress, as determined by Rietveld refinement of grazing incidence X-ray diffraction patterns. The latter also reveal a fully single-phase and nanocrystalline structure for all thin films with varying Ni contents.

High Q factor of photonic cavity with SU-8 photoresist micro-disk for electromagnetic wave control

How to control electromagnetic wave effectively is the key to the realization of applicable filters in many optics technologies. In our work, a SU-8 photoresist micro-disk is written onto a photonic crystal waveguide to control electromagnetic wave. Corresponding simulation and experiment shows that, the quality Q increases as the thickness of SU-8 smaller. When the thickness exceeds 400 nm, the change of thickness has little influence on electromagnetic waves. Besides, the increase of the radius of disc-shaped SU-8 can also increase the Q value. By optimizing the simulation and experimental data, we can successfully create a SU-8 photoresist micro-disk cavity with the thickness of 5 µm and height of 20 nm, the quality factor of Q can reach 8200. However, longer exposure time and more stable experimental equipment is needed if we want to get a larger radius. The method in our work by using SU-8 photoresist micro-disk on photonic crystals to control electromagnetic wave is more practical and flexible, which can provide new significance for research into optical filter.

Evaluation of Single and Combined Temozolomide and Doxorubicin Treatment Responses in Low- and High-Grade Glioma In Vitro.

Astrocytoma, the most common type of glioma, can histologically be low or high grade. Treatment recommendations for astrocytic tumors are based on the histopathological and molecular phenotype. For grade 2 astrocytoma, the combination of radiotherapy and adjuvant chemotherapy with procarbazine, lomustine, and vincristine (PCV) is better than radiotherapy alone. Temozolomide (TMZ) is being increasingly recognized as a replacement for PCV in brain tumor therapy, due to the lower myelotoxicity. TMZ is currently a well-established first-line treatment for grade 3 astrocytoma, grade 4 astrocytoma, and glioblastoma and it is also sporadically used for grade 2 astrocytoma. However, TMZ faces multiple challenges such as adverse effects and drug resistance. In this study, we compared the cytotoxic effect induced by TMZ and doxorubicin (DOXO), alone and in combination, on a low-grade astrocytoma cell line (AC1B) and a high-grade glioma cell line (GB1B). We found that TMZ and DOXO, each produced a cytotoxic effect in monotherapy. GB1B cell line was more sensitive to the treatment than AC1B cells, at a 7- and 10-day exposure to the DOXO. However, when the duration of the treatment was extended to 14 days, GB1B cells became more resistant to DOXO treatment, compared to AC1B cells. Regarding the treatment with TMZ, GB1B exhibited greater resistance to TMZ compared to AC1B, across all studied intervals and the resistance to treatment of GB1B increased with longer exposure time. However, in combined therapy, the drugs did not exert a synergistic effect on any astrocytic cell line. The current data suggest that both TMZ and DOXO exhibit efficient therapeutic effects on low- and high-grade glioma cells. However, no synergistic effect was observed for combined therapy.

Enhancing corrosion resistance of 316L stainless steel through electrochemical deposition of polyaniline coatings in acidic environments

Stainless steel is widely used because of its excellent corrosion resistance in typical environments. However, it is susceptible to corrosion in acidic media, therefore, to address this issue, the electrochemical deposition of polyaniline coatings on 316L stainless steel was investigated using cyclic voltammetry at different potential windows and scan rates. The successful polymerization and surface morphology were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Moreover, thermal stability of the PANI coating was assessed through thermo gravimetric analysis while the corrosion behavior of bare and coated steels immersed in 1M H2SO4 was studied using electrochemical impedance spectroscopy (EIS). Based on the Nyquist plots obtained from the EIS revealed that the corrosion resistance of the PANI coating improved significantly with a decrease in scan rate and by limiting the upper potential, especially during longer exposure times up to 72 h. Results suggest that controlling the deposition parameters and optimizing the electrochemical conditions can lead to even greater improvements in the corrosion resistance of the stainless steel. These findings offer valuable insights for researchers and engineers in the field of materials science and corrosion protection, enabling them to develop more precise and efficient strategies for enhancing the durability and performance of stainless steel in acidic environments.

Tentative identification of phytochelatins, their derivatives, and Cd-phytochelatin complexes in Ocimum basilicum L. roots by Paper Spray Mass Spectrometry.

An unprecedented and direct PS-MS (paper spray ionization mass spectrometry) method was proposed for the detection of native peptides, that is, glutathiones (GSHs), homoglutathiones (hGSHs), and phytochelatins (PCs), in basil (Ocimum basilicum L.) roots before and after cadmium exposure. The roots were submitted to cold maceration followed by sonication with formic acid as the extractor solvent for sample preparation. PS-MS was used to analyze such extracts in the positive mode, and the results allowed for the detection of several GSHs, hGSHs, and PCs. Some of these PCs were not distinguished in the control samples, that is, basil roots not exposed to cadmium. Other PCs were noticed in both types of roots, uncontaminated and cadmium-contaminated, but the intensities were higher in the former samples. Moreover, long-time exposure to cadmium stimulated the formation of some of these PCs and their cadmium complexes. The results, therefore, provided some crucial insights into the defense mechanism of plants against an external stress condition due to exposure to a toxic heavy metal. The present study represents a promising alternative to investigate other crucial physiological processes in plants submitted to assorted stress conditions.

Role of MARK4 in methamphetamine-induced acute kidney injury.

Methamphetamine (METH) is an illicit psychoactive substance that can damage various organs, with the urinary system being one of its significant targets. This study aims to explore the role of microtubule affinity-regulating kinase 4 (MARK4) in METH-induced acute kidney injury (AKI). A total of 10 healthy adult male C57BL/6 mice were randomly divided into a control group and a METH group, 5 mice in each group. The METH group was administered METH (20 mg/kg, intraperitoneally, once daily for 3 consecutive days), while the control group received an equal volume of physiological saline. The mice were executed 24 hours after the final injection, and the success of the AKI model was detected by blood serum creatinine, blood urea nitrogen, and renal HE staining. Proteins differentially expressed between kidney tissues with METH-induced AKI and normal kidney tissues were screened by proteomics techniques and subjected to gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and bioinformatics analysis. The accuracy of proteomic data was validated using Western blotting, and the expression levels of MARK4 and cleaved caspase-3 in mouse kidneys were measured. We further explored the role of MARK4 in METH-induced AKI. Firstly, a METH toxicity model was established in BUMPT cells to screen the appropriate concentration and time of METH treatment; the viability of BUMPT cells after METH treatment and the expression of cleaved caspase-3 were detected by interfering with MARK4 expression through inhibitors. The proteomic analysis of kidney tissues from METH and control groups screened for a total of 17 differentially expressed proteins, of which 11 were up-regulated and 6 were down-regulated (all P<0.05). The expression levels of MARK4 and cleaved caspase-3 were elevated in the kidneys of METH-treated mice (both P<0.05). The activity of BUMPT cells gradually decreased with increasing METH treatment concentration (all P<0.05), where the viability of BUMPT cells decreased to about 60% after METH treatment at 4 mmol/L. Compared with the control group, expression levels of MARK4 and cleaved caspase-3 were increased with higher METH concentrations and longer exposure times in a concentration- and time-dependent manner (all P<0.05). Inhibition of MARK4 expression improved METH-induced decrease in BUMPT cell activity, down-regulated the expression of cleaved caspase-3, and decreased the apoptosis of BUMPT cells induced by METH. MARK4 is highly expressed in a mouse model of METH-induced AKI, and MARK4 mediates METH-induced AKI by regulating cell apoptosis.

Validation of the ERO2.0 code using W7-X and JET experiments and predictions for ITER operation

The paper provides an overview of recent modelling of global material erosion and deposition in the fusion devices Wendelstein 7-X (W7-X), JET and ITER using the Monte-Carlo code ERO2.0. For validating the modelling tool in a three-dimensional environment, W7-X simulations are performed to describe carbon erosion from the graphite test divertor units, which were equipped in operational phase OP 1.2 and analysed post-mortem. Synthetic spectroscopy of carbon line emission is compared with experimental results from the divertor spectrometer measurement system, showing a good agreement in the e-folding lengths in the radial intensity profiles of carbon. In the case of metallic wall materials, earlier modelling of the Be/W environment in JET and ITER is revisited and extended with an updated set of sputtering and reflection data, as well as including the mixing model for describing the Be/W dynamics in the divertor. Motivated by recent H/D/T isotope experiments in JET, limited and diverted configuration pulses are modelled, showing the expected trend of both Be and W erosion increasing with isotope mass. For the JET diverted configuration pulses, it is shown that Be migrates predominantly to the upper part of the inner divertor where it initially leads to strong W erosion. With longer exposure time, the growth of a Be deposited layer leads to a reduction of W erosion in that region. A similar trend is observed in simulations of the ITER baseline Q = 10 scenario, however with a more symmetric Be migration pattern leading to deposition also on the outer divertor.

Hot corrosion Type I of novel Co‐based γ/γ′ superalloys with and without Al‐ and Cr‐diffusion coatings

AbstractCo‐based γ/γ′ superalloys are in development as candidates to replace Ni‐based superalloys in turbine engines, where they will be exposed to hot corrosion. The present study investigates the resistance to high temperature Type I hot corrosion of four alloys of the Co–Ni–Al–W system, which differed in their Co to Ni ratio and their W content. In addition, the alloys are tested not only uncoated but also with an Al and a Cr diffusion coating. The exposures were performed at 950°C with a Na2SO4 deposit of 2.5 mg/cm2 in air containing 0.1% SO2 for 100 and 300 h. The degradation was investigated by material loss measurements. Both coatings proved mostly protective for 100 h, while the uncoated samples were severely degraded. After the longer exposure time, only the Cr‐coating remained partially protective and outmatched the Al‐coating. Further, a positive influence was attributed to a higher Co to Ni ratio (1.4 vs. 0.7) and a higher W content (5 vs. 3 at%).

Biochar mitigates the postponed bioavailability and toxicity of phthalic acid esters in the soil

Observed nowadays wide pollution of the environment with microplastic and phthalic acid esters (PAEs) (such as dimethyl phthalate, DMP; diethyl phthalate, DEP; dibutyl phthalate, DBP; benzyl butyl phthalate, BBP; di-(2-ethylhexyl) phthalate, DEHP and di-n-octyl phthalate, DNOP) is a result of their increased production and usage. Weak bonding with polymer matrix enables their easier mobilization in the environment and increased bioavailability. The aim of the presented studies was the estimation of the fate of six priority PAEs in the soil-vegetable system and the application of biochar to immobilize PAEs in the soil preventing their bioavailability to lettuce. Both the acute (one full lettuce development period) and prolongated effect (lettuce cultivated after 10 weeks from the first PAEs contamination) were estimated to examine the long-time exposure under crop rotation. The addition of 1 % of corn-derived biochar immobilized PAEs in the soil efficiently (up to 4 times increased concentration) with the following order: DBP < DEP < DMP < DEHP < DNOP < BBP. Bioavailable PAEs were determined in lettuce roots (DMP, BBP, DEHP), and lettuce leaves (DEP, DBP, DNOP) but the presence of biochar lowered their content. PAEs, although not available for lettuce, were available for other organisms, confirming that the bioavailability or lack of nutrients is of great importance in PAEs-polluted soil. In long-time experiments, without biochar amendment, all PAEs were 3–12 times more bioavailable and were mainly accumulated in lettuce roots. The biochar addition significantly reduces (1.5–11 times) PAEs bioavailability over time. However, the PAEs content in roots remained significantly higher in samples with crop rotation compared to samples where only lettuce was grown. The results confirmed that biochar addition to the soil reduces their bioavailability and mobility inside the plant, limiting their transport from roots to leaves and reducing the exposure risk but confirming that lettuce leaves may be a safe food when cultivated in PAEs-polluted soil.

Optimization of contrast and dose in x-ray phase-contrast tomography with a Talbot-Lau interferometer

X-ray phase-contrast imaging has become a valuable tool for biomedical research due to its improved contrast abilities over regular attenuation-based imaging. The recently emerged Talbot-Lau interferometer can provide quantitative attenuation, phase-contrast and dark-field image data, even with low-brilliance x-ray tube sources. Thus, it has become a valid option for clinical environments. In this study, we analyze the effects of x-ray tube voltage and total number of images on the contrast-to-noise ratio (CNR) and dose-weighted CNR (CNRD) calculated from tomographic transmission and phase-contrast data of a phantom sample. Constant counting statistics regardless of the voltage was ensured by adjusting the image exposure time for each voltage setting. The results indicate that the x-ray tube voltage has a clear effect on both image contrast and noise. This effect is amplified in the case of phase-contrast images, which is explained by the polychromatic x-ray spectrum and the dependence of interferometer visibility on the spectrum. CNRD is additionally affected by the total imaging time. While submerging the sample into a water container effectively reduces image artefacts and improves the CNR, the additional attenuation of the water must be compensated with a longer exposure time. This reduces dose efficiency. Both the CNR and CNRD are higher in the phase-contrast images compared to transmission images. For transmission images, and phase-contrast images without the water container, CNRD can be increased by using higher tube voltages (in combination with a lower exposure time). For phase-contrast images with the water container, CNRD is increased with lower tube voltages. In general, the CNRD does not strongly depend on the number of tomographic angles or phase steps used.

Glycerophospholipid metabolism changes association with ozone exposure

Exposure to ozone (O3) has been associated with cardiovascular outcomes in humans, yet the underlying mechanisms of the adverse effect remain poorly understood. We aimed to investigate the association between O3 exposure and glycerophospholipid metabolism in healthy young adults. We quantified plasma concentrations of phosphatidylcholines (PCs) and lysophosphatidylcholines (lysoPCs) using a UPLC-MS/MS system. Time-weighted personal exposures were calculated to O3 and co-pollutants over 4 time windows, and we employed orthogonal partial least squares discriminant analysis to discern differences in lipids profiles between high and low O3 exposure. Linear mixed-effects models and mediation analysis were utilized to estimate the associations between O3 exposure, lipids, and cardiovascular physiology indicators. Forty-three healthy adults were included in this study, and the mean (SD) time-weighted personal exposures to O3 was 9.08 (4.06) ppb. With shorter exposure durations, O3 increases were associated with increasing PC and lysoPC levels; whereas at longer exposure times, the opposite relationship was shown. Furthermore, two specific lipids, namely lysoPC a C26:0 and lysoPC a C17:0, showed significantly positive mediating effects on associations of long-term O3 exposure with pulse wave velocity and systolic blood pressure, respectively. Alterations in specific lipids may underlie the cardiovascular effects of O3 exposure.

Microstructure evolution and oxidation resistance properties of oxide dispersion strengthened FeCrAl alloys at 1100 °C

Oxide dispersion strengthened (ODS) FeCrAl alloys were prepared by mechanical alloying (MA) and spark plasma sintering (SPS) technology. To reveal the high temperature oxidation properties, ODS FeCrAl alloys were exposed to dry air for various times (1h, 4h, 10h, 20h, 45h, 70h, and 100h) at 1100 °C to investigate the microstructure evolution. The results illustrated that a flat and adherent alumina scale was gradually thickened on the alloy substrate with the increase of the oxidation time. In particular, it was observed that large-size reactive element (RE) oxides were inclined to be associated with cavities close to the gas interface and these cavities were progressive evolution to be larger-size pores with longer exposure time, while tiny RE oxides were not dispersed with cavities after 100h oxidation. In addition, α-Al2O3 with a double-scale structure were mainly composed of inner columnar grains and outer equiaxed grains, as well, the growth of α-Al2O3 scales illustrated that the oxidation rate decreased with oxidation reaction proceeding. For one thing, Ti segregation along grain boundaries (GBs) near the gas interface decreased the outward diffusion of the Al ions to weaken the oxidation rate. Furthermore, the gradual coarsening of columnar grains near the alloy substrate implied a longer diffusion path of O atoms, thereby accounting for slower oxidation process. To sum up, ODS FeCrAl alloys with thinner oxide thickness demonstrated the superior oxidation resistance than other materials, which would make it one of the promising candidate structural materials applicated in accident-tolerant fuel (ATF) cladding materials.