The COVID-19 pandemic has raised the problem of efficient, low-cost materials enabling the effective protection of people from viruses transmitted through the air or via surfaces. Nanofibers can be a ...great candidate for efficient air filtration due to their structure, although they cannot protect from viruses. In this work, we prepared a wide range of nanofibrous biodegradable samples containing Ag (up to 0.6 at.%) and Cu (up to 20.4 at.%) exhibiting various wettability. By adjusting the magnetron current (0.3 A) and implanter voltage (5 kV), the deposition of TiO
and Ag
implantation into PCL/PEO nanofibers was optimized in order to achieve implantation of Ag
without damaging the nanofibrous structure of the PCL/PEO. The optimal conditions to implant silver were achieved for the PCL-Ti0.3-Ag-5kV sample. The coating of PCL nanofibers by a Cu layer was successfully realized by magnetron sputtering. The antiviral activity evaluated by widely used methodology involving the cultivation of VeroE6 cells was the highest for PCL-Cu and PCL-COOH, where the VeroE6 viability was 73.1 and 68.1%, respectively, which is significantly higher compared to SARS-CoV-2 samples without self-sanitizing (42.8%). Interestingly, the samples with implanted silver and TiO
exhibited no antiviral effect. This difference between Cu and Ag containing nanofibers might be related to the different concentrations of ions released from the samples: 80 μg/L/day for Cu
versus 15 µg/L/day for Ag
. The high antiviral activity of PCL-Cu opens up an exciting opportunity to prepare low-cost self-sanitizing surfaces for anti-SARS-CoV-2 protection and can be essential for air filtration application and facemasks. The rough cost estimation for the production of a biodegradable nanohybrid PCL-Cu facemask revealed ~$0.28/piece, and the business case for the production of these facemasks would be highly positive, with an Internal Rate of Return of 34%.
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The morphology of bulk heterojunction organic photovoltaic cells controls many of the performance characteristics of devices. However, measuring this morphology is challenging because of the small ...length-scales and low contrast between organic materials. Here we use nanoscale photocurrent mapping, ultrafast fluorescence and exciton diffusion to observe the detailed morphology of a high-performance blend of PTB7:PC71BM. We show that optimized blends consist of elongated fullerene-rich and polymer-rich fibre-like domains, which are 10-50 nm wide and 200-400 nm long. These elongated domains provide a concentration gradient for directional charge diffusion that helps in the extraction of charge pairs with 80% efficiency. In contrast, blends with agglomerated fullerene domains show a much lower efficiency of charge extraction of ~45%, which is attributed to poor electron and hole transport. Our results show that the formation of narrow and elongated domains is desirable for efficient bulk heterojunction solar cells.
The emergence of novel avian influenza viruses in migratory birds is of concern because of the potential for virus dissemination during fall migration. We report the identification of novel highly ...pathogenic avian influenza viruses of subtype H5N8, clade 2.3.4.4, and their reassortment with other avian influenza viruses in waterfowl and shorebirds of Siberia.
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The Pennsylvanian and Early Permian were times of extreme sea-level changes of >
100 to perhaps up to 200
m. For example, glacio-eustatic sea-level changes are well documented from the US ...Midcontinent, Moscow Basin and Yangtze Platform, where more than 100 stacked subtidal to supratidal sequences have been described. In contrast, carbonates developed in the Ural Mountains and South Guizhou of the Yangtze Platform were deposited in ramp and slope settings. δ
13C values of whole rock samples from the US Midcontinent and Moscow Basin were intensively affected by diagenesis. Only well-preserved brachiopod shells maintained their original carbon isotope ratios. In contrast, limestones deposited in the deeper water slope environments were not affected by meteoric diagenesis and are interpreted to have mainly retained their carbon isotope ratios. Mean δ
13C values of slope carbonates of the Yangtze Platform increase from about 3‰ during the Viséan and Serpukhovian to 5‰ at the Carboniferous–Permian boundary and decrease to values around 2‰ in the early Kungurian. This positive δ
13C excursion coincides with low δ
13C values in the Yangtze Platform successions, which were reset by meteoric diagenesis. The highest δ
13C values recorded in the slope succession coincide with the inferred maximum glaciation that caused pronounced sea-level lowstands. Short-lived, but significant negative δ
13C excursions in the Chinese slope succession are interpreted to reflect changes in ocean circulation due to sea-level rises which caused enhanced production and/or preservation of organic matter which influenced the subsequent early diagenetic cementation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK
Nanocrystallite-liquid phase transitions are studied for 1-octadecene confined in the pores of chemically functionalized silica gels. These silica gels possess similar fractal geometries of the pore ...system but differ in chemical termination of the surface, specific surface area (
F
) and pore volume (
V
). Linear dependencies of the melting temperature and specific melting heat on the
F
/
V
ratio are found for a series of silica gels with identical surface termination. A thermodynamic model based on experimental data is established, which explains the observed shift of the phase transition parameters for porous matrices with different surface chemistries. In addition, this model allows evaluation of actual changes in nanocrystallite density, surface tension and entropy upon melting.
Melting temperatures of 1-octadecene confined in the pores of chemically functionalized silica gels
vs.
the ratio of surface area to pore volume.
Heat flow generation and manipulation in nanometer-sized solids using light represents one of the up-and-coming tasks in thermonanophotonics. Enhanced light-matter interaction due to plasmon ...resonance permits metallic nanostructures to absorb light energy efficiently, and it results in extra optical heating. The net temperature increment of nanostructures is directly dependent on heat exchange with a thermostat. However, to the best of our knowledge, precise tailoring of optical heating at a fixed pump power is still of no practical implementation. In this paper, we focus on the tunable optical heating of a plasmonic nanostructure exposed to moderate light intensity (MW cm
−2
) based on slowing down heat exchange through a 1D waveguide heatsink bridging the nanostructure and the highly thermal conducting thermostat. The rationale for this concept is evidenced through optical heating of a 2D array of stacked titanium nitride (TiN) (plasmonic refractory nanoheater) and height-controlled silicon (Si) (1D waveguide heatsink) cylinders. Depending on the Si pillar height, the temperature rise of a TiN : Si voxel ranges from a few up to thousands of degrees at a fixed pump power. The temperature of the TiN : Si voxel is remotely measured from the Raman shift of the Si pillar. Using ellipsometry, we find a temperature threshold of 400 °C, above which the thin TiN film is chemically degraded due to oxidation. The latter enables fine tailoring of thermal gradients using TiN : Si voxels of equal size but different permittivity. These findings contribute towards the development of tunable thermoplasmonics by demonstrating programmable non-uniform temperature profiles in the steady-state regime under continuous-wave laser illumination for a variety of thermo-optical applications.
A 2D array of TiN : Si voxels, consisting of stacked TiN and Si cylinders, with controllable temperature increase range through varying the height of Si pillars.
Among well-studied and actively developing compounds are polyoxometalates (POMs), which show application in many fields. Extending this class of compounds, we introduce a new subclass of polyoxometal ...clusters (POMCs) Mo
O
(μ-L)
(L = pyrazolate (pz) or triazolate (1,2,3-trz or 1,2,4-trz)), structurally similar to POM, but containing binuclear Mo
O
clusters linked by bridging oxo- and organic ligands. The complexes obtained by ampoule synthesis from the binuclear cluster Mo
O
(C
O
)
(H
O)
in a melt of an organic ligand are soluble and stable in aqueous solutions. In addition to the detailed characterization in solid state and in aqueous solution, the biological properties of the compounds on normal and cancer cells were investigated, and antiviral activity against influenza A virus (subtype H5N1) was demonstrated.
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Superlensing plays a crucial role in near- and far-field optical imaging with sub-wavelength resolution. One of the ways to expand optical bandwidth is surface plasmon resonances in layered ...metal-dielectric nanostructures. These resonances are commonly excited at a tunable single frequency. In this study, we propose the concept of a multimode far-field superlens made of a titanium oxynitride (TiON) thin film, that is a disordered metal-dielectric refractory nano-composite. These films exhibit a double epsilon-near-zero (2-ENZ) behavior near the percolation threshold and, therefore, favor super-coupling the incident laser light to surface plasmon resonances, not using such couplers as a prism, a grating,
etc.
We experimentally observe stimulated Raman gain emission from nano-structured TiON thin films exposed to low-power continuous-wave laser light. It is shown that superresolution of <
λ
/80 (near-field) and <
λ
/8 (far-field) is achieved due to both the enhanced third-order optical nonlinearity and the multiplicative nature of four-wave mixing. The multimode tunable far-field superlens will impact emerging diffraction-free far-field optical microscopy, random Raman lasing on meta-atoms and broadband thermophotovoltaics.
Beating the diffraction limit in far-field optical imaging becomes possible due to stimulated Raman scattering in percolated metal-dielectric nanocomposites.
We report the results of X-ray diffraction (XRD) measurements of the dogs’ claws and show the feasibility of using this approach for early, non-invasive cancer detection. The obtained two-dimensional ...XRD patterns can be described by Fourier coefficients, which were calculated for the radial and circular (angular) directions. We analyzed these coefficients using the supervised learning algorithm, which implies optimization of the random forest classifier by using samples from the training group and following the calculation of mean cancer probability per patient for the blind dataset. The proposed algorithm achieved a balanced accuracy of 85% and ROC-AUC of 0.91 for a blind group of 68 dogs. The transition from samples to patients additionally improved the ROC-AUC by 10%. The best specificity and sensitivity values for 68 patients were 97.4% and 72.4%, respectively. We also found that the structural parameter (biomarker) most important for the diagnostics is the intermolecular distance.
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Two variants of highly pathogenic avian influenza A(H5N8) virus were detected in dead poultry in Western Siberia, Russia, during August and September 2020. One variant was represented by viruses of ...clade 2.3.4.4b and the other by a novel reassortant between clade 2.3.4.4b and Eurasian low pathogenicity avian influenza viruses circulating in wild birds.
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