Different Types Of Atmospheres Research Articles

Influence of the environment on the morphology, optical and electrical characteristics of the PEDOT:PSS polymer

The paper presents the results of studying the influence of the environment on the surface structure, optical and electrical characteristics of the PEDOT:PSS film. The studies have been carried out in three different types of atmosphere under the same conditions of thermal annealing of the films. It has been established that the modification of the surface of a polymer film with ethanol and isopropanol in vacuum, in a nitrogen atmosphere, and in the air atmosphere leads to a change in the surface morphology and the optical electric transport properties of the polymer. Depending on the environment, when the PEDOT:PSS film is modified with a certain concentration of ethyl and isopropyl alcohols, the absorption spectra show a shift in the absorption maximum responsible for PEDOT to the short-wavelength region of the spectrum, as well as a decrease in the absorption peak of the part of the spectrum responsible for the absorption of the aromatic fragment PSS. It is identified that the structural features of the PEDOT:PSS surface morphology affect the electrical transport parameters of the films: Rh is the resistance of the PEDOT:PSS polymer film, Rext is the charge carrier transfer resistance at the PEDOT:PSS/electrode interface, keff is the effective charge carrier extraction rate and τeff is the effective transit time of charge carriers. The optimal technological parameters for film production have been determined, at which the electrical transport properties of PEDOT:PSS polymer film are increased.

Influence of the environment on the morphology, optical and electrical characteristics of the PEDOT:PSS polymer

The paper presents the results of studying the influence of the environment on the surface structure, optical and electrical characteristics of the PEDOT:PSS film. The studies have been carried out in three different types of atmosphere under the same conditions of thermal annealing of the films. It has been established that the modification of the surface of a polymer film with ethanol and isopropanol in vacuum, in a nitrogen atmosphere, and in the air atmosphere leads to a change in the surface morphology and the optical electric transport properties of the polymer. Depending on the environment, when the PEDOT:PSS film is modified with a certain concentration of ethyl and isopropyl alcohols, the absorption spectra show a shift in the absorption maximum responsible for PEDOT to the short-wavelength region of the spectrum, as well as a decrease in the absorption peak of the part of the spectrum responsible for the absorption of the aromatic fragment PSS. It is identified that the structural features of the PEDOT:PSS surface morphology affect the electrical transport parameters of the films: Rh is the resistance of the PEDOT:PSS polymer film, Rext is the charge carrier transfer resistance at the PEDOT:PSS/electrode interface, keff is the effective charge carrier extraction rate and τeff is the effective transit time of charge carriers. The optimal technological parameters for film production have been determined, at which the electrical transport properties of PEDOT:PSS polymer films are increased.

Stability of Hybrid Organic-Inorganic Perovskite CH3NH3PbBr3 Nanocrystals under Co-Stresses of UV Light Illumination and Temperature.

Hybrid organic–inorganic metal halide perovskite nanocrystals (NCs) are among the candidates for color conversion materials in displays, especially in NC-based micro-light-emitting diode (micro-LED) displays. However, these NCs are still lacking long-term stability, which has hindered their large-scale applications. We mimic the working conditions, which include ultraviolet light illumination at 323 K and three different types of atmosphere (N2, vacuum, and air), respectively, to investigate the stability of CH3NH3PbBr3 NCs embedded in the polyvinylidene fluoride matrix. X-ray diffraction results indicate the generation of NH4Pb2Br5, which is produced from the encapsulated CH3NH3PbBr3 NCs in all three atmospheres, and the decomposition generates a large amount of accompanying interface defects at the surface area of NCs, resulting in the significant decrease of the photoluminescence (PL) intensity. This work highlights the stability-related mechanism of CH3NH3PbBr3 NCs under combined external stresses that mimic operating conditions. In addition, this work also suggests a new method for conducting aging tests and contributes to developing effective routes towards higher stability of perovskite NCs.

Melting behaviour of uranium-americium mixed oxides under different atmospheres

In the context of a comprehensive campaign for the characterisation of transmutation fuels for next generation nuclear reactors, the melting behaviour of mixed uranium-americium dioxides has been experimentally studied for the first time by laser heating, for Am concentrations up to 70 mol. % under different types of atmospheres. Extensive post-melting material characterisations were then performed by X-ray absorption spectroscopy and electron microscopy. The melting temperatures observed for the various compositions follow a markedly different trend depending on the experimental atmosphere. Uranium-rich samples melt at temperatures significantly lower (around 2700 K) when they are laser-heated in a strongly oxidizing atmosphere compressed air at (0.300 ± 0.005) MPa, compared to the melting points (beyond 3000 K) registered for the same compositions in an inert environment (pressurised Ar). This behaviour has been interpreted on the basis of the strong oxidation of such samples in air, leading to lower-melting temperatures. Thus, the melting temperature trend observed in air is characterized, in the purely pseudo-binary dioxide plane, by an apparent maximum melting temperature around 2850 K for 0.3 < x(AmO2) < 0.5. The melting points measured under inert atmosphere uniformly decrease with increasing americium content, displaying an approximately ideal solution behaviour if a melting point around 2386 K is assumed for pure AmO2. In reality, it will be shown that the (U, Am)-oxide system can only be rigorously described in the ternary U-Am-O phase diagram, rather than the UO2-AmO2 pseudo-binary, due to the aforementioned over-oxidation effect in air. Indeed, general departures from the oxygen stoichiometry (Oxygen/Metal ratios ≠ 2.0) have been highlighted by the X-ray Absorption Spectroscopy (XAS). Finally, to help interpret the experimental results, thermodynamic computations based on the CALPHAD method will be presented.

Study of the kinetic parameters of thermal and oxidative degradation of various residual materials

The thermal decomposition of three biomass residues was studied in this work: cork powder, paper sludge and sewage sludge. Firstly, characterization of the materials was carried out by elemental and proximate analysis and FT-IR spectroscopy. Experiments were carried out in a thermobalance to obtain thermogravimetric curves (TG) and differential thermogravimetric curves (DTG). Two different types of atmosphere were investigated: pyrolysis (100% N2) and combustion (80% N2 20% O2). The effect of the heating rate (5 K min−1, 10 K min−1 and 20 K min−1) was also investigated. Moreover, important combustion parameters were calculated, namely ignition and burnout temperatures and calorific value. A model was proposed for each of the materials and atmospheres in order to calculate the kinetic parameters. The proposed model fitted adequately to the obtained experimental data in all cases, giving and R2 higher than 0.995 and 0.9858 in TG and DTG curves respectively.

Atmospheric corrosion of ASTM A-242 and ASTM A-588 weathering steels in different types of atmosphere

ABSTRACTThe work analyses the atmospheric corrosion resistance of two widely used weathering steels: ASTM A-242 and ASTM A-588. The steels were exposed for up to 5 years in different types of atmosphere: rural, urban, industrial and marine. The atmospheric corrosion resistance of the steels was evaluated and the rust layers formed on them were characterised by X-ray diffraction, optical microscopy and scanning electron microscopy. The most relevant conclusions reached include the following: (a) the visual appearance (colouring) of the rust, rust texture, nature of the corrosion products and compactness of the rust layers formed are similar in both types of weathering steel. (b) No great differences are observed in the corrosion resistance. Slight differences occur in the industrial atmosphere, where ASTM A-242 presents 10–13% less corrosion than ASTM A-588. (c) In the C2-C3 ISO corrosivity atmosphere both types of weathering steels are adequate for unpainted use. However are not suitable in higher ISO corrosivity atmosphere.

Remarkably improved electrical conductivity of ZnO ceramics by cold sintering and post-heat-treatment

High quality ZnO ceramics are required for transparent conductive oxide (TCO) films. In this work, high dense ZnO ceramics with density of ~ 97.5% were sintered by using Cold Sintering Process (CSP), and various post-heat-treating conditions (different types of atmosphere and temperature) were applied to optimize the microstructure and electrical conductivity. After post-heat-treatment, the crystallinity was improved, the relative density increased to > 99.0%, while the grain size exhibited small variations. The most significant improvements in electrical conductivity were observed for the sample post-heat-treated in Ar atmosphere, with more than four orders of enhancement from 0.0005 S/cm for the as-cold-sintered one to a maximum of 16.4 S/cm after post-heat-treating at 500 °C. Our work demonstrated an effective method for preparing high performance ZnO ceramics at ultralow temperature.

Algoritmo teórico para la estimación de la radiación solar global para una atmósfera despejada

En este trabajo se desarrolló un algoritmo para la estimación de la radiación solar global, para una atmósfera despejada, mediante el modelamiento de las ecuaciones teóricas de transferencia radiativa de onda corta (0,3 µm - 2,8 µm). Se determinaron las transmitancias espectrales de la radiación solar directa, debidas a la dispersión de Rayleigh y Mie. Mediante el software Propiedades Ópticas de Aerosoles y Nubes (Optical Properties of Aerosols and Clouds, OPAC) se calculó la Profundidad Óptica de los Aerosoles (Aerosol Optical Depth, AOD) para cuatro diferentes tipos de atmósferas, indispensable para la determinación del índice de turbidez de Ångström. Así mismo, se calcularon la transmitancias espectrales por absorción de la radiación solar directa, incluyendo aerosoles, vapor de agua, ozono y aire seco (mezcla de gases). El contenido de O3 se obtuvo de los datos diarios existentes en base de datos de la NASA. Para la componente difusa de la radiación solar, se dedujo una nueva expresión para el cálculo de la fracción de la radiación solar dispersada por los aerosoles hacia la superficie terrestre. La comparación estadística entre los resultados obtenidos con el algoritmo desarrollado, los datos medidos de la radiación global (estación Potsdam - Alemania) y los resultados de otros tres modelos radiativos, entre 2012 y 2014, muestra que el nuevo modelo permite calcular los valores horarios de la radiación solar global con suficiente precisión. © 2018. Acad. Colomb. Cienc. Ex. Fis. Nat.

Vacancy-like defects in nanocrystalline SnO2: influence of the annealing treatment under different atmospheres

The study of electronic and chemical properties of semiconductor oxides is motivated by their several applications. In particular, tin oxide is widely used as a solid state gas sensor material. In this regard, the defect structure has been proposed to be crucial in determining the resulting film conductivity and then its sensitivity. Here, the characteristics of vacancy-like defects in nanocrystalline commercial high-purity tin oxide powders and the influence of the annealing treatment under different atmospheres are presented. Specifically, SnO2 nanopowders were annealed at 330 °C under three different types of atmospheres: inert (vacuum), oxidative (oxygen) and reductive (hydrogen). The obtained experimental results are discussed in terms of the vacancy-like defects detected, shedding light to the basic conduction mechanisms, which are responsible for gas detection.

UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars at the 1AU equivalent distance for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present day levels at 2.0 Gyr ago, 0.8 Gyr ago and modern Earth (Following Kaltenegger et al. 2007). In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth-Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5V) receives 300 times less biologically effective radiation, about 2 times modern Earth-Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

Evaluation of Atmospheric Corrosivity Indexes in the City of Tuxpan Veracruz

Faculty of Chemical Sciences in collaboration with the Institute of Engineering of the Universidad Veracruzana has developed a project for the construction of the Corrosivity Map of the State of Veracruz. Among the activities of the project is the evaluation of the indixes of atmospheric corrosivity in the city of Tuxpan Veracruz, due to the industrial, urban activities and to be located in a coastal area, characteristics that influence the corrosion of metallic materials exposed to the atmosphere. A exposition panel was installed with specimens of aluminum wire on steel screws, copper screws and plastic screws to study corrosivity indexes through mass loss in every season of year, and thus classify the different types of atmospheres; marine, industrial and rural-urban according to the values specified in the standard (ISO 8408, 9223, 9224). Corrosivity indexes obtained indicate a domain of rural-urban atmosphere product of excessive urban activities in the region. Expected to detect high levels of marine atmosphere by the presence of chlorides and particles resulting City location front of coast. However, corrosivity indexes for marine atmosphere are within the limit allowed by the normative.

Rethinking affective atmospheres: Technology, perturbation and space times of the non-human

This paper develops literatures on affective atmospheres to rethink the status of technical objects in human geographical analysis. Suggesting that narratives of affect and affordance have difficulty accounting for objects when they are not directly encountering one another, the paper draws upon Levi Bryant’s discussion of allopoietic objects and Graham Harman’s analysis of space and time to advance the concept of perturbation. In doing so, the paper argues that technical objects are not lifeless mechanisms but actively produce spatio-temporal atmospheres, which shape the humans who are immersed in these atmospheres. Using the iPhone 4 as a thought experiment to think through the different types of atmosphere that can be generated by technical objects, the paper suggests that geographers should attune themselves to these atmospheres and recognize the role they play in the organization and experience of space and time for humans.

Investigation of reactive HiPIMS + MF sputtering of TiO2 crystalline thin films

A hybrid high-power impulse magnetron sputtering (HiPIMS)+mid-frequency (MF) magnetron sputtering system was used for the deposition of crystalline TiO2 thin films at a low substrate temperature. Ion velocity distribution functions (IVDFs) were measured in a pulsed magnetron discharge at substrate positions depending on the type of plasma excitation and on the working gas mixtures. Several different pulsed discharge configurations were used: (i) HiPIMS, (ii) pulsed bipolar MF with frequency 350kHz and (iii) both HiPIMS+MF connected in parallel to the magnetron cathode. The timing of HiPIMS excitation was set to period time T=10ms with “ON” time TON=100μs. Ti targets were sputtered in three different types of atmospheres: (i) inert pure Ar, (ii) a reactive mixture of Ar+O2 and (iii) a reactive mixture of Ar+O2+N2 with a constant gas pressure p=1Pa. All IVDFs were measured using a time-resolved retarding field energy analyzer (RFEA) located in the substrate position. TiO2 thin films were deposited under identical experimental conditions on silica (SiO2) glass substrate, glass with an indium tin oxide (ITO) electrode and polycarbonate polymer foil. The thin film properties are discussed with respect to the measured plasma parameters. It is shown that the combination of HiPIMS+MF excitation in a reactive atmosphere effectively reduces the delay between the edge of cathode voltage and current onset. The highest ion energy was reached in the case of an inert Ar atmosphere due to the highest ratio of fast Ti+ ions in the overall ion flux. All TiO2 thin films deposited in reactive atmospheres formed pure rutile phase regardless of the excitation mode; however, those films deposited by a HiPIMS+MF excitation mode exhibited the greatest ability to produce a photocurrent. Furthermore, HiPIMS+MF was the best setting for the deposition of crystalline TiO2 on polycarbonate foil because of the low heating flux on the substrate and suitable plasma parameters leading to the formation of the rutile phase.

The effect of model assumptions on computations of cosmic ray induced ionization in the atmosphere

The longitudinal profile of atmospheric cascades is sensitive to the energy, mass of the primary particle and to atmospheric state. In this work are compared ionization yield functions Y for winter, summer and US standard profiles of Earth's atmosphere. The various profiles are obtained on the basis of CORSIKA 6.52 code simulations using FLUKA 2006 and QGSJET II hadronic interaction subroutines. The energy deposit of proton induced cascade processes in the atmosphere is calculated for different types of atmospheres. The ion pair production in the atmosphere and the contribution of the different shower components, precisely the electromagnetic, muon and hadronic is estimated according applied atmospheric types. In addition simulations with different hadronic interaction models GHEISHA 2002, FLUKA 2006 and QGSJET II are carried out. The ion pair production in the atmosphere and the contribution of different shower components is estimated according the assumed hadronic interaction models. The yield function Y for total ionization, respectively, for the different components is compared. The observed differences are widely discussed. General conclusion concerning the application of various atmospheric profiles and hadron interaction models is carried out.

Phase evolution in a Cu–18 at.% Li alloy as a function of temperature under different atmospheres

Scanning electron microscopy (SEM), neutron diffraction (ND) and thermal analysis studies were used to check the behaviour of powders of Cu–18 at.% Li alloy in the temperature range between room temperature and 973 K under different types of atmospheres. After heating at 973 K the remaining lithium content is about 15 at.% and 13 at.%, in the tests under argon and vacuum, respectively. In contrast, if the sample is heated in air or in nitrogen, the lithium content in solid solution in the alloy at temperatures of about 873 K is very low (3 at.%). Consequently the alloy is in solid state at temperature as high as 1273 K. The heating of the alloy powders in nitrogen and in air, at atmospheric pressures, leads to the growth of lithium nitride, which was not expected.

Free amino acids in muscle of Norway lobster ( Nephrops novergicus ( L.)) in controlled and modified atmospheres during chilled storage

Changes in free amino acids (FAAs) in relation to freshness were examined in the muscle of Norway lobster during bulk storage in controlled and modified atmospheres containing two different gas mixes (1: 60/15/25 and 2: 40/40/20, CO 2%/O 2%/N 2%). The essential free amino acids in the highest concentrations were threonine, leucine, valine, lysine and arginine, all over 40 mg/100 g. Threonine, valine, lysine and arginine concentrations decreased significantly ( p<0.05) during storage. These decreases were more pronounced in the lots kept in the CO 2-rich mix (1) than the lots kept in the O 2-rich mix (2) and this was independent of whether the storage was under controlled (C) or modified (M) atmosphere. The dipeptide anserine showed decreases with the same trend. The most abundant non-essential FAAs were glycine, alanine and glutamic acid (57.9, 57.2 and 31.2 mg/100 g, respectively), along with the dipeptide anserine (52.9 mg/100 g). The non-essential FAAs presented differences attributable to the gas mixes used. No differences were detected in any of the FAA groups studied with respect to the different types of atmospheres (C or M). Only ornithine and tryptophan levels increased significantly ( p<0.05) in the course of storage. These increases were significantly ( p<0.05) different only in the control lot. These FAAs would appear to be suitable as freshness indices for Norway lobster stored in ice. Moreover, the significant ( p<0.05) decrease of the dipeptide anserine could be a suitable freshness index for Norway lobster stored in either ice or in atmospheres (C or M).

Characterization of corrosion products formed on steels in the first months of atmospheric exposure

The corrosion products of carbon steel and weathering steel exposed to three different types of atmospheres, at times ranging from one to three months, have been identified. The steels were exposed in an industrial site, an urban site (Sao Paulo City, Brazil), and a humid site. The effect of the steel type on the corrosion products formed in the early stages of atmospheric corrosion has been evaluated. The corrosion products formed at the various exposure locations were characterized by Raman microscopy, X-Ray diffraction (XRD) and their morphology was observed by Scanning Electron Microscopy (SEM). Three regions of different colours (yellow, black and red) have been identified over the steel coupons by Raman microscopy. Analysis carried out on each of these areas led to the characterization of the correspondent oxide/hydroxide phases. The main phases present were lepidocrocite (g-FeOOH) and goethite (a-FeOOH). Small amounts of magnetite (Fe3O4) were also eventually encountered.

Influence of the annealing conditions on the properties of ZnO thin films

The effect of annealing treatment (in the presence of different types of atmospheres) on the performances of zinc oxide thin films (intrinsic and doped with In and Al) prepared by spray pyrolysis have been studied, with the aim to determine more adequate conditions to improve the properties of the films. The results show that the annealing treatment leads to substantial changes in the structural, electrical and optical characteristics of ZnO thin films. The most significant improvements were obtained after annealing in forming gas (reduction atmosphere) at 200°C during 2 h. The ZnO:In film after heat treatment was the one that exhibited the lowest resistivity (ρ=5.2×10−2 Ωcm) and a high transmittance (T=86%).

The atmospheric corrosion mechanism of 55%Al-Zn coating on steel

This paper presents the results of a study aimed at understanding the atmospheric corrosion mechanism of the 55%Al-Zn coating (Galvalume) on steel and a comparison with the behaviour of galvanized sheets (Sendzimir). Research has been carried out in different types of atmosphere in Spain, Brazil and Portugal. Unlike the galvanized coating, which suffers a generalized attack of its surface, the 55%Al-Zn coating undergoes a localized type of attack which commences in the interdendritic regions of the material. An analysis is also made of the additional protection which may be provided by a chemical passivating treatment applied on both types of coating.

Long‐term atmospheric cathodic protection of 55 % Al‐Zn coating on steel and its comparison with galvanized steel

AbstractThis paper presents the results obtained in a 5 year study of the galvanic protection afforded to the base steel by a 55 % Al‐Zn Made in Spain by CSI Planos under the trademark Algafort which has been licensed by BIEC International, Inc. This product is commercially available in U.S.A. under the trademark Galvalume. coating and its comparison with a galvanized coatin., in different types of atmospheres. While both coatings hardly supply cathodic protection (CP) in rural and urban atmospheres, in marine and industrial type atmospheres they present excellent galvanic performance, which is conditioned only by the duration of the anodic material on the steel substrate. This duration is considerably greater in the 55% Al‐Zn coating, due to its lower corrosion rate in the atmosphere.