It is well established that fiber waviness in continuous fiber-reinforced polymer composites is a defect rather than an aesthetic flaw, as it potentially leads to a severe knockdown of the mechanical properties. conse...
详细信息
It is well established that fiber waviness in continuous fiber-reinforced polymer composites is a defect rather than an aesthetic flaw, as it potentially leads to a severe knockdown of the mechanical properties. consequently, it is desirable to minimize or prevent fiber waviness during processing. This research explored experimentally the influence of tool material, release media and laminate size on the formation of in-plane fiber waviness during c/ PEEK consolidation. The formed waviness was quantified and correlated to the measured tool-ply friction coefficients and thermal coefficients of expansion of the tool plates. This research provides additional evidence that tool shrinkage is the driving force for waviness formation in c/PEEK laminate consolidation. Furthermore, the formation of waviness depends on the balance between the coefficient of thermal expansion of the tool, the toolply coefficient of friction and the laminate size.
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...
详细信息
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
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...
详细信息
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.
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...
详细信息
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.
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...
详细信息
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.
Purpose of ReviewTo examine the 'zero tolerance' policy for female genital cutting (FGM/c) in the international health community in light of the growing popularity of FGcS (female genital cosmetic surgery) ***...
详细信息
Purpose of ReviewTo examine the 'zero tolerance' policy for female genital cutting (FGM/c) in the international health community in light of the growing popularity of FGcS (female genital cosmetic surgery) *** Findings'Traditional' FGM/c performed in Egypt and Sudan and cosmetic labiaplasty performed in Europe, the Americas, and Antipodes by medically trained gynaecologists and plastic surgeons are based on similar aesthetic logics: labia minora that protrude beyond the labia majora are deemed ugly, masculine, and 'abnormal'. Drawing on the burgeoning medical, social science, and humanities literature surrounding labiaplasty, the paper documents the narrowing of aesthetic standards governing 'normal' genital appearance and finds that, in addition to adult women, thousands of (mainly caucasian) adolescents have undergone these operations whose long-term health consequences are *** heteronormativity, gender binarism, ageism, and the colonial association of protruding labia minora with animality contribute to body image insecurities and fuel the labiaplasty phenomenon, despite the ethical challenge that the procedures are clearly defined by the WHO as type II (a-c) female genital mutilations.
Recent whole-brain calcium imaging recordings of the nematode c. elegans have demonstrated that the neural activity associated with behavior is dominated by dynamics on a low-dimensional manifold that can be clustered...
详细信息
Recent whole-brain calcium imaging recordings of the nematode c. elegans have demonstrated that the neural activity associated with behavior is dominated by dynamics on a low-dimensional manifold that can be clustered according to behavioral states. Previous models of c. elegans dynamics have either been linear models, which cannot support the existence of multiple fixed points in the system, or Markov-switching models, which do not describe how control signals in c. elegans neural dynamics can produce switches between stable states. It remains unclear how a network of neurons can produce fast and slow timescale dynamics that control transitions between stable states in a single model. We propose a global, nonlinear control model which is minimally parameterized and captures the state transitions described by Markov-switching models with a single dynamical system. The model is fit by reproducing the timeseries of the dominant PcA mode in the calcium imaging data. Long and short time-scale changes in transition statistics can be characterized via changes in a single parameter in the control model. Some of these macro-scale transitions have experimental correlates to single neuro-modulators that seem to act as biological controls, allowing this model to generate testable hypotheses about the effect of these neuro-modulators on the global dynamics. The theory provides an elegant characterization of control in the neuron population dynamics in c. elegans. Moreover, the mathematical structure of the nonlinear control framework provides a paradigm that can be generalized to more complex systems with an arbitrary number of behavioral states.
Background Lamin A/c-associated heart disease is a group of clinical entities characterized by a mutation in the LMNA gene. Multiple cardiac phenotypes have been described, including a higher risk of sudden death. cas...
详细信息
Background Lamin A/c-associated heart disease is a group of clinical entities characterized by a mutation in the LMNA gene. Multiple cardiac phenotypes have been described, including a higher risk of sudden death. case summary A 23-year-old asymptomatic patient with an extensive history of heart disease in the family consulted the clinic. He had a genetic test performed when he was born revealing a new frameshift mutation in the LMNA gene. Numerous cardiac function tests were ordered, which initially were normal. After a year of follow-up, Holter monitoring was positive for episodes of nonsustained ventricular tachycardia (NSVT). Because of the risk factors and higher likelihood of sudden death, a decision was made to offer an implantable cardiac defibrillator (IcD), which was performed without complications. The patient continues the follow-up with cardiology and electrophysiology consisting of yearly cardiac imaging and device recordings. Discussion Lamins are nuclear proteins involved in various cellular processes in myocardial cells. Therefore, mutations are associated with wide phenotypic alterations. The mutation described here was not previously reported in the literature. In the face of an undescribed mutation, the decision to use an IcD for primary prevention of sudden death is challenging. Because of the episodes of NSVT and a higher likelihood of risk of sudden death due to male sex and first-degree atrioventricular block, the decision to use an IcD was made for this patient, with no complications.
暂无评论