Influence of carbon nanotubes localization and transfer on electrical conductivity in PA66/(PS/PPE)/CNTs nanocomposites

The localization and transfer of carbon nanotubes (CNTs) in PA66/(PS/PPE)/CNTs nanocomposites were investigated using several methods including TEM/EDS techniques, surface energy and wetting coefficient calculations, electrical conductivity measurements, and rheological analysis. The CNTs were found to be dispersed preferentially in the polyamide 66 (PA66) phase and not in the miscible polystyrene (PS)/poly(phenylene ether) (PPE) blend phase because CNTs have a higher affinity for PA66. The electrical conductivity of the PA66/(PS/PPE)/CNTs nanocomposites significantly increased compared to the PA66/CNTs nanocomposites at the same CNT loading. The nanocomposites were prepared with three different compounding procedures. The nanocomposites prepared with sequence III (premixing PS/PPE and CNTs, and then blending the (PS/PPE)/CNTs with PA66) yielded a better CNT dispersion that resulted in a higher electrical conductivity. The CNT dispersion was determined by TEM and rheological analysis. Additionally, the nonlinear-linear viscoelastic ratio (NLR) was used to quantify the degree of CNT dispersion. Because the CNTs initially dispersed in the unfavorable PS/PPE phase were transferred as individual rods into the preferred PA66 phase during the second step of compounding sequence III, the nanocomposite prepared with sequence III had a higher NLR value, that is, a better CNT dispersion compared to the other nanocomposite prepared with different compounding sequences

Isolation and Characterization of Efficient Active Compounds Using High-Performance Centrifugal Partition Chromatography (CPC) from Anti-Inflammatory Activity Fraction of Ecklonia maxima in South Africa

Ecklonia maxima is a brown seaweed, which is abundantly distributed in South Africa. This study investigated an efficient approach using high-performance centrifugal partition chromatography (HPCPC), which has been successfully developed for the isolation and purification of phlorotannins, eckmaxol, and dieckol from the ethyl acetate fraction of E. maxima (EEM). We evaluated EEM for its inhibitory effect against lipopolysaccharide (LPS)-induced inflammatory responses in zebrafish embryos. The separation of eckmaxol and dieckol from samples of EEM using HPCPC was found to be of high purity and yield under an optimal solvent system composed of n-hexane:ethyl acetate:methanol:water (2:7:3:7, v/v/v/v). To evaluate the anti-inflammatory efficacy of EEM containing active compounds, zebrafish embryos exposed to LPS were compared with and without EEM treatment for nitric oxide (NO) production, reactive oxygen species (ROS) generation, and cell death two days after fertilization. These evaluations indicate that EEM alleviated inflammation by inhibiting cell death, ROS, and NO generation induced by LPS treatment. According to these results, eckmaxol and dieckol isolated from brown seaweed E. maxima could be considered effective anti-inflammatory agents as pharmaceutical and functional food ingredients

Meningeal lymphatic vessels at the skull base drain cerebrospinal fluid

© 2019, The Author(s), under exclusive licence to Springer Nature Limited.Recent work has shown that meningeal lymphatic vessels (mLVs), mainly in the dorsal part of the skull, are involved in the clearance of cerebrospinal fluid (CSF), but the precise route of CSF drainage is still unknown. Here we reveal the importance of mLVs in the basal part of the skull for this process by visualizing their distinct anatomical location and characterizing their specialized morphological features, which facilitate the uptake and drainage of CSF. Unlike dorsal mLVs, basal mLVs have lymphatic valves and capillaries located adjacent to the subarachnoid space in mice. We also show that basal mLVs are hotspots for the clearance of CSF macromolecules and that both mLV integrity and CSF drainage are impaired with ageing. Our findings should increase the understanding of how mLVs contribute to the neuropathophysiological processes that are associated with agein

Mapping the human genetic architecture of COVID-19

The genetic make-up of an individual contributes to the susceptibility and response to viral infection. Although environmental, clinical and social factors have a role in the chance of exposure to SARS-CoV-2 and the severity of COVID-191,2, host genetics may also be important. Identifying host-specific genetic factors may reveal biological mechanisms of therapeutic relevance and clarify causal relationships of modifiable environmental risk factors for SARS-CoV-2 infection and outcomes. We formed a global network of researchers to investigate the role of human genetics in SARS-CoV-2 infection and COVID-19 severity. Here we describe the results of three genome-wide association meta-analyses that consist of up to 49,562 patients with COVID-19 from 46 studies across 19 countries. We report 13 genome-wide significant loci that are associated with SARS-CoV-2 infection or severe manifestations of COVID-19. Several of these loci correspond to previously documented associations to lung or autoimmune and inflammatory diseases3,4,5,6,7. They also represent potentially actionable mechanisms in response to infection. Mendelian randomization analyses support a causal role for smoking and body-mass index for severe COVID-19 although not for type II diabetes. The identification of novel host genetic factors associated with COVID-19 was made possible by the community of human genetics researchers coming together to prioritize the sharing of data, results, resources and analytical frameworks. This working model of international collaboration underscores what is possible for future genetic discoveries in emerging pandemics, or indeed for any complex human disease