In a recent paper published in this journal it was presented an interesting study on the 2019 outburst of the 15Bootids and it was suggested the possibility that comet c/539W1 was the parent comet of this meteor showe...
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In a recent paper published in this journal it was presented an interesting study on the 2019 outburst of the 15Bootids and it was suggested the possibility that comet c/539W1 was the parent comet of this meteor shower. It was also deducted from the method employed that this parent comet could have had a first passage through perihelion around the year AD1260. In this paper, we review both assumptions and we propose the possibility that the previous perihelion passage of the parent comet of the 15-Bootids was observed and recorded as c/ 1245D1.
Environmental pollutants like microplastics are posing health concerns on aquatic animals and the ecosystem. Microplastic toxicity studies using caenorhabditis elegans (c. elegans) as a model are evolving but methodol...
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Environmental pollutants like microplastics are posing health concerns on aquatic animals and the ecosystem. Microplastic toxicity studies using caenorhabditis elegans (c. elegans) as a model are evolving but methodologically hindered from obtaining statistically strong data sets, detecting toxicity effects based on microplastics uptake, and correlating physiological and behavioural effects at an individual-worm level. In this paper, we report a novel microfluidic electric egg-laying assay for phenotypical assessment of multiple worms in parallel. The effects of glucose and polystyrene microplastics at two concentrations on the worms' electric egg-laying, length, diameter, and length contraction during exposure to electric signal were studied. The device contained eight parallel worm-dwelling microchannels called electric traps, with equivalent electrical fields, in which the worms were electrically stimulated for egg deposition and fluorescently imaged for assessment of neuronal and microplastic uptake expression. A new bidirectional stimulation technique was developed, and the device design was optimized to achieve a testing efficiency of 91.25%. Exposure of worms to 100 mM glucose resulted in a significant reduction in their egg-laying and size. The effects of 1 mu m polystyrene microparticles at concentrations of 100 and 1000 mg/L on the electric egg-laying behaviour, size, and neurodegeneration of N2 and NW1229 (expressing GFP pan-neuronally) worms were also studied. Of the two concentrations, 1000 mg/L caused severe egg-laying deficiency and growth retardation as well as neurodegeneration. Additionally, using single-worm level phenotyping, we noticed intra-population variability in microplastics uptake and correlation with the above physiological and behavioural phenotypes, which was hidden in the population-averaged results. Taken together, these results suggest the appropriateness of our microfluidic assay for toxicological studies and for assessing the phen
Needle optimization is widely used in visible and infrared region, but it is rarely utilized in X-ray and extreme ultraviolet waveband. We use Needle optimization to design Pt/c X-ray supermirrors, and the grazing inc...
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Needle optimization is widely used in visible and infrared region, but it is rarely utilized in X-ray and extreme ultraviolet waveband. We use Needle optimization to design Pt/c X-ray supermirrors, and the grazing incidence angles are 1.0, 1.4, and 1.7 degree, respectively. A modified target is introduced into optilayer software. A good result is obtained by Optilayer software combined with IMD software. The difference of design results between block method and needle optimization is discussed.
This study investigated the oxidation behaviours of a TiAl (TNM) alloy oxidized at 650 ?c in argon and oxygen. The oxidation mass gains were similar in both atmospheres up to 200 h of oxidation. Between 200 and 500 h,...
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This study investigated the oxidation behaviours of a TiAl (TNM) alloy oxidized at 650 ?c in argon and oxygen. The oxidation mass gains were similar in both atmospheres up to 200 h of oxidation. Between 200 and 500 h, the mass gains increased by 20 % in the O2 atmosphere. This study examined the triplex oxide scales of outer (Ti?Al) O layer-by-layer and Mo/Nb-rich TiAl oxides on the TNM alloy after oxidation in Ar and O2. The scale structures formed in Ar and O2 were similar but differed from those formed in air, and the respective TNM samples? oxidation behaviours were different.
In this paper, the tensile damage and fracture behavior of carbon fiber reinforced silicon carbide (c/Sic) minicomposites with single- and multiple-layer interphases are investigated. The effect of the interphase on t...
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In this paper, the tensile damage and fracture behavior of carbon fiber reinforced silicon carbide (c/Sic) minicomposites with single- and multiple-layer interphases are investigated. The effect of the interphase on the tensile damage and fracture behavior of c/Sic minicomposites is analyzed. The evolution of matrix cracking under the tensile load of the c/Sic minicomposite with a notch is observed using the digital image correlation (DIc) method. The damage evolution process of the c/Sic minicomposite can be divided into four main stages, namely, (1) an elastic response coupled with partial re-opening of thermal microcracking;(2) multiple matrix microcracking perpendicular to the applied loading;(3) crack opening and related fiber/matrix, bundle/matrix, and inter-bundle debonding;and (4) progressive transfer of the load to the fibers and gradual fiber failure until composite failure/fracture. On the fracture surface, a large number of fibers pulling out of the samples with both single-layer and multi-layer interphases can be clearly observed.
This study elucidates the impact of the microstructure of Fe-16cr-0.2c on oxide layer formation at 650 degrees c in Ar0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. Th...
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This study elucidates the impact of the microstructure of Fe-16cr-0.2c on oxide layer formation at 650 degrees c in Ar0.5 % SO2. A cold-rolled and two heat-treated states of the alloy were exposed for up to 1000 h. The samples were characterised in detail from microstructural and chemical perspectives using scanning electron microscopy (SEM), X-ray diffraction (XRD) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The microstructural modification of the alloy by heat-treatment was advantageous. It was found that cr-carbides support chromia formation and reduce sulphidation when their area fraction is low and diameter is small.
Full-carbon/ceramic brake pairs have been recently proposed to achieve profound applications of c/c-Sic brake materials in brake systems with a high-energy load. Severe wear rate and a high and unstable coefficient of...
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Full-carbon/ceramic brake pairs have been recently proposed to achieve profound applications of c/c-Sic brake materials in brake systems with a high-energy load. Severe wear rate and a high and unstable coefficient of friction (cOF) of the traditional c/c-Sic disc-pads pairs prevented further development of this material. In this study, FeSi75 alloy and cu were mixed to form an infiltration agent to modify the c/c-Siccomposites. We examined the braking performance of the Fe-Si-cu modified c/c-Sic brake pads mated with traditional needled c/c-Sic brake disc using a lab-scale dynamometer. The results revealed that the Fe-Si-cu blending modification yielded a significant wear reduction of the brake disc and pads. After a series of braking tests, the worn surface morphology was characterized, and the wear resistance improvement mechanism was analyzed.
Surface properties of engineered nanomaterials (ENMs) have been shown to influence their interaction with biological systems. However, studies to date have largely focused on hydrophilic materials, likely due to bioco...
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Surface properties of engineered nanomaterials (ENMs) have been shown to influence their interaction with biological systems. However, studies to date have largely focused on hydrophilic materials, likely due to biocompatibility concerns and aqueous exposure conditions necessary for many model systems. Therefore, a knowledge gap exists in nanotoxicity literature for impacts of hydrophobic ENMs, with studies of hydrophobic materials largely limited to carbon ENMs. Here we demonstrate testing of hydrophobic quantum dots (QDs) using the nematode c. elegans, a model soil organism cultured on solid media and amenable to hydrophobic exposures. To evaluate the influence of hydrophobicity, we compared cdSe/ZnS QDs functionalized with hydrophobic trioctylphosphine oxide (TOPO) to identical QDs functionalized with hydrophilic dihydrolipoic acidpolyethylene glycol (DHLA-PEG) and alternative hydrophobiccdSe/ZnS QDs functionalized with oleic acid (OA). Results show that hydrophobic TOPO QDs are significantly more toxic than hydrophilic DHLA-PEG QDs, and substitution of TOPO with OA yields relatively non-toxic hydrophobic QDs. Fluorescence microscopy shows TOPO QDs loosely associated with the organism's cuticle, but atomic force microscopy shows no difference in cuticle structure from exposure. Importantly, TOPO ligand alone is as toxic as TOPO QDs, and our data suggests that TOPO may impact neuromuscular function, perhaps upon displacement from the QD surface. This study demonstrates the importance of examining ligand-specific impacts of hydrophobic ENMs and indicates OAfunctionalized QDs as a potential alternative to TOPO QDs for reduced toxicity.
Three co-8cr-xAl alloys (x = 0, 3, 5 wt.%) were exposed to three mixtures (Gas 1: H2-cO2, Gases 2 and 3: H2cO2-H2S) at 900 degrees c for 20 h. Gas 1 produced external chromia scales (plus internal alumina for co-8cr-3...
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Three co-8cr-xAl alloys (x = 0, 3, 5 wt.%) were exposed to three mixtures (Gas 1: H2-cO2, Gases 2 and 3: H2cO2-H2S) at 900 degrees c for 20 h. Gas 1 produced external chromia scales (plus internal alumina for co-8cr-3/5Al). Gas 2, with p(S2) below stability of co sulfides, favored a transition from external chromia scales, observed in Gas 1, to exclusive external alumina scales for both co-8cr-3/5Al alloys. conversely, Gas 3 was very aggressive for both co-8cr and co-8cr-3Al, forming a liquid co-S phase, while with co-8cr-5Al it still formed external Al2O3 scales. Al additions improved the alloys resistance to the sulfur attack.
The corrosion behaviour of Alloy 690 under four different zinc addition scenarios was investigated in circulating water containing 2 ppm Li and 1000 ppm B at 330 degrees c. The corrosion rates, release rates, and oxid...
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The corrosion behaviour of Alloy 690 under four different zinc addition scenarios was investigated in circulating water containing 2 ppm Li and 1000 ppm B at 330 degrees c. The corrosion rates, release rates, and oxide thicknesses were quantified using gravimetric analyses and oxide compositions. With earlier zinc addition, the corrosion and release rates were accordingly lower and the oxide films were also thinner. This study elaborates on how the radiation source term is suppressed by the zinc addition and the behavior of zinc incorporation into spinel oxides.
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