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In the present work polymeric composite films materials based on polyvinyl alcohol (PVA), glycerol and silver nitrate the conducted composites with high mechanical characteristics were created. In the process of composites drying, glycerol acts as a reducing agent and the formation of silver nanoparticles occurs, moreover the reducing take places at room temperature. The AgNO3 content is varied from 0.01 to 30 wt.%. Taking into account the physical-mechanical and conducting properties of composites, it is established that the optimum content of glycerol in the final material is equal to 30 wt%. The formation of metallic silver was confirmed by an appearance of a surface plasmon resonance band at 420-430 nm in UV spectra and the appearance of two diffraction peaks at 38.17° and 44.15° in X-ray diffraction pattern as well, corresponding to the crystallographic planes (111) and (200) of a face centered cubic lattice of Ag0. Dielectric spectroscopy data show that the increasing of glycerol content up to 30-40 wt.% leads to enhance the conductivity by three orders in comparison with the initial PVA. An increase in the silver content resulted in further rise of the conductivity, reaching value of 5.72 10-6 S/cm at 15 wt.% of silver concentration, at room temperature (20 °C). At 100-120 °C, the conductivity was the highest for the composite with 25 wt.% of AgNO3 - 3.67-3.84 10-4 S/cm. The resulting samples had high physical and mechanical properties: relative elongation of about 400%, tensile strength of 32-36 MPa. Studies of the dynamic light scattering of films solution with Ag NPs showed that the smallest size was for the sample with 0.5 wt.% - 6.3 nm. [ABSTRACT FROM AUTHOR]

Using observations from the Global‐scale Observations of the Limb and Disk (GOLD) mission, we investigate post‐sunset ionospheric responses to the September 2019 Antarctic sudden stratospheric warming –first ever from a synoptic perspective. Observations reveal a prevalent quasi‐6‐day periodicity in the equatorial ionization anomaly region over South America and the Atlantic, coincident with enhanced quasi‐6‐day wave (Q6DW) activity in the mesosphere (Liu et al., 2021, https://doi.org/10.1029/2020JA028909). The atmosphere‐ionosphere coupling via large‐scale waves is rarely studied over the ocean due to the lack of observations. More importantly, further analyses suggest that multiple pathways are involved in transmitting the quasi‐6‐day periodicity from the middle atmosphere into the post‐sunset F‐region ionosphere, including modulation of F‐region field aligned winds and pre‐reversal enhancements by the tides and or Q6DW. A remarkable depletion in electron density, attributable to the overall change in thermosphere composition driven by the dissipative tides and or Q6DWs, is also seen during the period of enhanced Q6DW activity. Plain Language Summary: The equatorial ionization anomaly (EIA) owes an appreciable amount of variability to the lower/middle atmosphere wave forcing of various scales. The 2019 September Antarctic sudden stratospheric warming (SSW)—rarely occurs in the southern hemisphere—provides a great opportunity to explore the effects atmospheric waves have on the EIA, as a bunch of waves gets significantly reinforced following the polar vortex disruption. Combining the observations made by the NASA GOLD and TIMED missions reveals a coincident quasi‐6‐day modulation of the post‐sunset EIA crests and mesospheric temperatures during the course of this SSW event, demonstrating a solid case that the ionosphere couples with the atmosphere via planetary‐scale waves. Key Points: A prominent quasi‐6‐day periodicity in the post‐sunset equatorial ionization anomaly (EIA) is observed during the 2019 Antarctic sudden stratospheric warming, coincident with mesospheric quasi‐6‐day waves (Q6DWs)The EIA displays an overall depletion over South America and the Atlantic when the Q6DWs are quite activeMultiple mechanisms play roles in coupling of the Q6DW with the post‐sunset EIA [ABSTRACT FROM AUTHOR]

Using methods of thermomechanical analysis, heat conductivity and heating—cooling cycles of polyepoxy and its composites with oxides of metal Al(III) and Fe(III). specimens were studied. The energy activation of processes expansion of studied specimens and its modulus of elasticity vs. filler concentrations and conditions of curing were defined from results of investigation. First show, those specimens filled thermosets, carried into physical fields are smart polymers, which save memory about state of initial acquired structure. [ABSTRACT FROM AUTHOR]

Structure, specific capacity, heatproof and thermal expansion of filled polyepoxy have been studied by FTIR--spectroscopy, DSC and Thermo mechanicals methods. Was established, that due to chemical building of PAn it have capacity to phase compatibility with different nature. Usege of external physical fields permit to create of composites with forecast thermophysical and thermomechanical properties. Suggest definition of phenomena relaxational structure. [ABSTRACT FROM AUTHOR]

It was shown, that repeated loading behavior of the system containing structurizing filler depending on gypsum concentration possesses extreme character. The system behavior during first loading cycle depends of physical bonding leveling the polyurethane to a greater extent than of filler concentration and/or filler presence. Equilibrium loss coefficients are sharply different for filled and unfilled system. The presence of filler results in increasing of equilibrium loss coefficient. [ABSTRACT FROM AUTHOR]

The addition of silver ions or nanoparticles to impart antimicrobial properties to polymeric or other materials is a widely used method. However, it should be noted that the antiviral and antimicrobial effect of silver nanoparticles that come into contact with the environment, associated with their size, with a decrease in the size of nanoparticles, their effectiveness increases sharply. In the present work, we used a biodegradable polymer polylactide (PLA), which is obtained by condensation of lactic acid or ring-opening polymerization of lactide. These studies will further contribute to the development of new safe materials, in particular for food packaging, which is undoubtedly an urgent problem. The work aims is to obtain the silver-containing polymer composites based on polylactide by thermochemical reduction of Ag+ ions using natural (chitosan) and synthetic (polyethyleneimine (PEI)) polymers and to study the structure, morphology, thermomechanical and antimicrobial properties of the obtained nanocomposites. Thermochemical reduction of Ag+ ions in the bulk of polymer films, containing PLA, silver palmitate as a precursor of Ag NP and reducing agent (PEI or chitosan), has been performed by keeping them at 100–170 °C within 5 minutes. The polymeric film composites, cast from chloroform solution, were heated in an oven using precise thermal regulator VRT-3. As a result of reduction, the films get attained silver color, the Ag content in the bulk of films varied from 1 to 4 wt. %, and the thickness of the films was 110 μm. Structure, morphology, thermomechanical and antimicrobial properties of two types of nanocomposites – PLA-Ag-PEI and PLA-Agchitosan, formed by the thermochemical reduction of Ag+ in polymer films have been studied using wide-angle X-ray scattering (WAXS) (a DRON-4-07 diffractometer), a transmission electron microscope (TEM) (JEM-1230 JEOL, Japan), and thermomechanical analysis (a UIP-70M device). Antimicrobial activity of the obtained nanocomposites was investigated applying reference strains of opportunistic bacteria Staphylococcus aureus and Escherichia coli. It has been found that thermochemical reduction of Ag+ ions in the bulk of polymer films, when using synthetic or natural polymers (PEI or chitosan) as a reducing and stabilizing agent of silver nanoparticles occurs at 160 °C during 5 minutes. It has been found that the average size of Ag nanoparticles in the polymeric matrix is equal to ~ 7 and ~ 4 nm for PEI and chitosan, respectively. It has been shown that PLA-Ag-chitosan nanocomposites have much higher antimicrobial activity against S. aureus and E. coli strains as compared to PLA-Ag-PEI nanocomposites. [ABSTRACT FROM AUTHOR]

NRLMSIS® 2.0 is an empirical atmospheric model that extends from the ground to the exobase and describes the average observed behavior of temperature, eight species densities, and mass density via a parametric analytic formulation. The model inputs are location, day of year, time of day, solar activity, and geomagnetic activity. NRLMSIS 2.0 is a major, reformulated upgrade of the previous version, NRLMSISE‐00. The model now couples thermospheric species densities to the entire column, via an effective mass profile that transitions each species from the fully mixed region below ~70 km altitude to the diffusively separated region above ~200 km. Other changes include the extension of atomic oxygen down to 50 km and the use of geopotential height as the internal vertical coordinate. We assimilated extensive new lower and middle atmosphere temperature, O, and H data, along with global average thermospheric mass density derived from satellite orbits, and we validated the model against independent samples of these data. In the mesosphere and below, residual biases and standard deviations are considerably lower than NRLMSISE‐00. The new model is warmer in the upper troposphere and cooler in the stratosphere and mesosphere. In the thermosphere, N2 and O densities are lower in NRLMSIS 2.0; otherwise, the NRLMSISE‐00 thermosphere is largely retained. Future advances in thermospheric specification will likely require new in situ mass spectrometer measurements, new techniques for species density measurement between 100 and 200 km, and the reconciliation of systematic biases among thermospheric temperature and composition data sets, including biases attributable to long‐term changes. Key Points: A major, reformulated upgrade to NRLMSISE‐00 is presented using extensive new data sets from the ground to ~100 km altitudeVertical structure of the atmosphere is now self‐consistently coupled; O density now extends down to 50 kmNew model is warmer in upper troposphere, cooler in stratosphere and mesosphere; thermospheric N2 and O densities are lower [ABSTRACT FROM AUTHOR]

The objective of this work is to study the peculiarities of structural organization, morphology, thermomechanical, electrical and antimicrobial properties of nanocomposites based on pectin-polyethyleneimine interpolyelectrolyte complexes and silver nanoparticles in dependence on the type of reducing agent being applied for chemical reduction of silver ions in the interpolyelectrolyte-metal complexes. The average size of Ag nanoparticles is shown to be increased with decreasing of the activity of reducing agent (E0) and equals to 3.8 nm, 4.3 nm, and 15.8 nm, respectively, when engaging sodium borohydride (–1.24 V), hydrazine (–1.15 V) and ascorbic acid (–0.35 V). Moreover, it was found that the crystallite size of Ag nanoparticles also had the smallest value for nanocomposites obtained involving NaBH4 as reducing agent. Ag-containing nanocomposites prepared by reduction of silver ions in interpolyelectrolyte-metal complexes while applying a range of reducing agents are characterized by different electrical properties and polymer matrix' glass transition temperature. The influence of silver nanoparticles' size incorporated in the polymer matrix on the antimicrobial activity of nanocomposites has been established. The inhibition zone diameter of Staphylococcus aureus and Escherichia coli was higher for nanocomposites obtained using sodium borohydride and hydrazine compared to nanocomposites where ascorbic acid was used as the reducing agent. [ABSTRACT FROM AUTHOR]

The objective of this work is to study the peculiarities of structural organization, morphology, thermomechanical and antimicrobial properties of nanocomposites based on pectin-polyethyleneimine polyelectrolyte complexes and silver nanoparticles in dependence of the type of reducing agent, which was applied for chemical reduction of silver ions. It was shown that the average size of Ag nanoparticles was increased with decreasing the power of reducing agent and equals 3,8; 4,3 and 17,3 nm when using sodium borohydride, hydrazine and ascorbic acid respectively. It was found that the crystallite size of Ag also was the smallest for NaBH4 as reducing agent, although the narrowest size distribution of silver nanoparticles in the polymer matrix is observed when reducing silver ions by hydrazine. The influence of the size of silver nanoparticles in the polymer matrix on the antimicrobial activity of nanocomposites has been established. The inhibition zone diameter of Staphylococcus aureus and Escherichia coli were the highest (19 and 20 mm, respectively) for the nanocomposite obtained using hydrazine. [ABSTRACT FROM AUTHOR]

Structural organization, morphology and thermomechanical properties of nanocomposites based on pectin, polyethyleneimine and Cu nanoparticles, formed by the thermal reduction method from interpolyelectrolyte–metal complexes (IMC) pectin–Cu 2+ –polyethyleneimine have been investigated using WAXS (wide-angle X-ray scattering), SAXS (small-angle X-ray scattering) methods as well as TEM (transmission electron microscopy) and thermomechanical analysis. It is defined that thermal reduction of Cu 2+ ions in IMC bulk (while films are heated to the temperature around 170 °C and higher temperatures) results in nanocomposites based on interpolyelectrolyte complexes “pectin–polyethyleneimine” and Cu nanoparticles being formed. In its turn, thermal reduction of copper ions is found out to take place owing to polyethyleneimine (namely, on account of electrons transfer from the amino groups’ nitrogen atoms of polyethyleneimine to Cu 2+ ions). It has been shown by thermomechanical analysis that the optimal time for complete thermal reduction of Cu 2+ ions to metallic copper at T = 170 °C is 30 min. The antimicrobial investigations of the elaborated nanocomposites revealed they possess a high antimicrobial activity against S. aureus and E. coli strains. [ABSTRACT FROM AUTHOR]

This study presents the ionospheric effects caused by the series of geomagnetic storms of September 9-14, 2005. The behavior of different ionospheric parameters over the Yakutsk, Irkutsk, Millstone Hill and Arecibo stations during the considered period have been numerically calculated, using a global self-consistent model of the thermosphere, ionosphere, and protonosphere (GSM TIP) developed at WD IZMI-RAN. The model calculations of disturbances of the ionospheric parameters during storms qualitatively agree with the experimental data at these midlatitude stations. We suggest that the causes of the quantitative differences between the model calculations and the observational data were the use of the 3-hour Kp index of geomagnetic activity and the dipole approximation of geomagnetic field in GSM TIP, with additional contributions from the effects of solar flares which are not considered in GSM TIP. [ABSTRACT FROM AUTHOR]

Products by chemical modification of rapeseed oils have been studied by FTIR-spectroscopy, mass-spectrometry and thermophysical methods. It was established that heat polymerization of rapeseed oil decrease of crystallization possibility and facilitate thermodestruction processes. Appears in molecular chains of epoxy cycles or hydroxyl group's change of its thermo resistivity. [ABSTRACT FROM AUTHOR]