Atmospheric Dry Air Research Articles

Increasing catalytic efficiency of cobalt centers in oxygen reduction reaction - Evidence from cobalt with salen ligands polymer complex

Substantial research is performed for cobalt-based catalysts for various applications in catalysis, including oxygen reduction reaction (ORR) catalysis in nonaqueous electrolytes. Cobalt exhibits high catalytic activity due to partially filled d-orbitals, which promote the formation of chemisorption bonds with various molecules. The catalytic activity of metal centers can be influenced both by changing their immediate environment and by varying the reaction conditions. This paper investigates the influence of solvent type, electrolyte concentration, and organic framework conductivity on the efficiency of ORR catalysis in non-aqueous electrolytes as illustrated by poly-CoSal polymer complex. The findings show that the increase in the solvent donor number of and conductivity of the organic backbone leads to highly efficient cobalt catalysts, which can be potentially be applied in oxygen cathodes of Li-O2 batteries. CoSal-based catalysts increase the discharge voltage of Li-O2 cells and can operate in dry atmospheric air.

Rotational and vibrational temperatures of transient atmospheric glow plasma

Plasma ignition can significantly improve the efficiency and performance of combustion devices through the enhancement of combustibility limits. Investigating plasma development for fundamental experimental flame conditions (i.e. spherical flame experiments) can provide insight into how plasma thermalizes the combustible mixture and, therefore a better understanding of flame development in future experimental studies. This study observed an ignition system designed to produce spherical flames in quiescent gas inside a constant-volume combustion chamber. Rotational and vibrational temperature measurements of dry atmospheric air glow plasma are reported. Measurements were taken for a transient discharge with currents less than 0.5 A. The electrode wire geometry and discharge variation resulted in an ellipsoid-shaped kernel and plasma region with an abnormal glow discharge. The measured temperatures were compared to the conductive thermal kernel boundary observed with Schlieren imaging. Maximum rotational and vibrational temperatures of 3000 K and 10 000 K, respectively, were observed near the anode electrode for a 0.5 A current. The temperature decreased with the axial distance from the anode, while a constant temperature was observed in the radial direction. Lower currents resulted in a smaller temperature, with minimum measured rotational and vibrational temperatures of 1500 K and 5000 K, respectively. The results were compared with available experimental literature and the variation observed was a result of the transient nature, which resulted in hysteresis in temperature vs discharge current measurements.

Observation of an Extremely Dry Atmospheric Air Column above Bern

The water vapour column density or vertically integrated water vapour (IWV) ranges from about 8 mm in winter to about 25 mm in summer in Bern, Switzerland. However, there can be day episodes when IWV drops to 2 mm or even less so that the atmosphere is extremely dry. We selected an event in February 2021 when the tropospheric water radiometer TROWARA measured a mean IWV value of about 1.5 ± 0.2 mm for a time interval of about one day in Bern. The ECMWF reanalysis ERA5 indicated a slightly higher IWV value of about 2.2 ± 0.4 mm where the uncertainty is the standard deviation of IWV during the time of IWV depression. The ERA5 profiles of relative humidity and specific humidity during this episode are reduced by 50% and more compared to the monthly mean profiles. On a global map, it can be seen that Bern is within a mesoscale dry region on that day with descending wind. Back trajectory analysis gives the result that the dry air masses in Bern came from the North and the trajectories are descending in altitude so that dry air from the mid troposphere came into the lower troposphere. These descending air masses from the North explain the minimum of IWV observed in Bern on 13–14 February 2021. The surface climate in Switzerland was dominated by a cold wave at that time. At the same time, severe cold waves occurred in Greece and Northern America.

A computational study on the energy efficiency of species production by single-pulse streamers in air

We study the energy efficiency of species production by streamer discharges with a single voltage pulse in atmospheric dry air, using a 2D axisymmetric fluid model. Sixty different positive streamers are simulated by varying the electrode geometry, the pulse duration and the applied voltage. Between these cases, the streamer radius and velocity vary by about an order of magnitude, but the variation in the maximal electric field is significantly smaller, about 30%. We find that G-values for the production of N(4S), O(3P), NO and N2O, which have relatively high activation energies, vary by about 30% to 60%. This variation is mainly caused by two factors: differences in the fraction of energy deposited in the streamer head region, and differences in the maximal electric field at the streamer head. When accounting for both factors, our computed G-values are in good agreement with an analytic estimate proposed by Naidis (2012 Plasma Sources Sci. Technol. 21 042001). We also simulate negative streamers and find that their production of N(4S), O(3P) and NO is less energy efficient. The results suggest that energy efficiency can be increased by reducing Joule heating in the streamer channel and by increasing the maximal electric field at the streamer head, for example by using short voltage pulses with a high applied voltage.

Effect of Temperature on the Working Parameters of Negative Corona Discharge with Coaxial Electrodes Configuration

The influence of ambient temperature on the various parameters of negative corona discharge in atmospheric dry air with coaxial cylindrical electrodes is investigated. The calculations are achieved using the finite element method by COMSOL Multiphysics software. The investigation aims to notice the effect many of working temperatures on the I-V characteristic curve of negative corona discharge in the air. The calculations of several parameters (electron density, temperature, ...) are presented visually and discussed. The results of the work are compared with theoretical and experimental data and they are in a good agreement.

O2-CO2 diagram as a tool for comprehension of blood gas abnormalities

The O 2 -CO 2 diagram is an often neglected but very useful tool to understand the implications of arterial blood gas (ABG) analysis, which is a challenging concept not only to the undergraduate medical student but also to practicing clinicians. Here, we present a simplified description of the O2-CO2 diagram that was developed in all its elegance by Rahn and Fenn (6) and subsequently reviewed by others (2, 5). The O2-CO2 diagram plots PCO2 on the y-axis against PO2 on the x-axis. Any set of values of PO2 and PCO2, whether in atmospheric air, tracheal (inspired) air, alveolar air, mixed expired air, arterial blood, or venous blood, can be plotted on this diagram. It will be appreciated at the end of this discussion that 1) there are certain physical limits to what combinations of O2 and CO2 can exist in the alveolus and, therefore, the blood; and 2) even if arterial blood gases are the only available laboratory parameters, one can make reasonable assumptions about alveolar gas composition and assess if a patient has a pure ventilatory defect or a diffusion defect; however, it is difficult to assess mixed disorders without direct measurement of alveolar gas partial pressures. To begin, let us review the composition of atmospheric air, inspired air, and alveolar air (Fig. 1). Dry atmospheric air is composed of 21% O 2, with the rest N2 and negligible CO2. Therefore, PO2 in dry atmospheric air at sea level is 21% of the atmospheric pressure (Patm) of 760 mmHg, which is 159 mmHg. As air passes through the upper airways during inspiration, it is saturated with water vapor, the partial pressure of which at body temperature, pressure, saturated (BTPS) is 47 mmHg. The addition of water vapor dilutes inspired air, thereby reducing both the partial pressure of nitrogen and PO2 proportionally. The PO2 in inspired air is therefore 149 mmHg [21% of (760 47) mmHg] and is henceforth represented as PIO2 . While the inspired air in the conducting zone is composed of N2 ,O 2, and water vapor, a fourth gas, namely, CO2, is added to alveolar air. Since the alveoli are open to the atmosphere and during either phase of respiration alveolar pressure is only slightly different from Patm, it is safe to assume that alveolar pressure at all times is almost equal to Patm or the total pressure of inspired air (760 mmHg). The partial pressures of nitrogen (564 mmHg) and water vapor (47 mmHg) are almost the same in inspired and alveolar air. The remaining 149-mmHg pressure is due to O 2 alone in the inspired air (PI O2 ), whereas in the alveolus, the combined pressures of O 2 (PA O2 ) and CO 2 (PA CO2 ) must be close (but not necessarily equal 1 ) to 149 mmHg. Since O 2 diffuses out of the alveolus, it is obvious that removal of O2 and, therefore, reduction of its partial pressure compensates for the addition of CO2. The crude relationship is therefore as follows:

Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments

Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects (HiRes, AUGER, TA, EUSO, TUS, etc.) use air fluorescence to detect and measure extensive air showers (EAS). The precise knowledge of the Fluorescence Light Yield (FLY) is of paramount importance for the reconstruction of UHECR. The MACFLY—Measurement of Air Cherenkov and Fluorescence Light Yield—experiment has been designed to perform such FLY measurements. In this paper we will present the results of FLY in the 290–440 nm wavelength range for dry air and pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50 GeV. The experiment uses a 90Sr radioactive source for low energy measurement and a CERN SPS e − beam for high energy. We find that the FLY is proportional to the deposited energy ( E d) in the gas and we show that the air fluorescence properties remain constant independently of the electron energy. At the reference point: atmospheric dry air at 1013 hPa and 23 °C, the ratio FLY/ E d = 17.6 photon/MeV with a systematic error of 13.2%.

XPS depth profiling studies of L-CVD SnO 2 thin films

In this paper we present the results of the XPS atomic depth profile analysis, using ion beam sputtering, of L-CVD SnO 2 thin films grown on an atomically clean SiO 2 substrate after annealing at 400 °C in dry atmospheric air. From the evolution of the Sn 3d 5/2, O 1s, Si 2p and C 1s core level peaks our experiments allowed the determination of the in depth atomic concentration of the main components of the SnO 2/SiO 2 interface. Thin (few nm) nearly stoichiometric SnO 2 films are present at the topmost layer of the thin films, and progressive intermixing with SnO and silicon oxide is observed at deeper layer. The interface between the Sn and the Si oxide layers (i.e. the effective Sn oxide thickness) is measured at 13 nm.

Evapotranspiration Responses of Plants and Crops to Carbon Dioxide and Temperature

Summary Atmospheric carbon dioxide (CO2) concentration has risen from about 270 mmol (CO2) mol−1 (air) (i.e., mole fraction of dry atmospheric air basis) before 1700 to about 370 mmol mol −1 currently. General Circulation Models (GCM) have predicted a global temperature rise of 2.8 to 5.2°C for a doubling of CO2. This review examines evapotranspiration and water-use efficiency responses of plants to rising CO2 and climatic changes, especially temperature. Doubling of CO2 will decrease leaf stomatal conductance to water vapor about 40%. However, water use by C3 crop plants under field conditions has usually been decreased only 12% or less for two reasons. Firstly, feedbacks in the energy balance of plant foliage cause leaf temperatures to rise as stomatal conductance is decreased. Increases of leaf temperature raise the vapor pressure of water inside the leaf, which increases the leaf-to-air vapor pressure difference. This increased driving force for transpiration offsets in large part the decreased leaf c...

Design of Dry Barriers for Containment of Contaminants in Unsaturated Soils

AbstractA dry barrier consists of a laterally continuous soil layer that is dried by air flow. Dry atmospheric air is passed through a soil layer (preferably of a coarse texture). accumulates water vapor, then emerges from the formation as moist air. Removal of soil moisture limits or prevent downward water movement. Drying a soil layer with air is possible when atmospheric air contains less water vapor than soil pore gas. The design of an effective dry barrier is highly site dependent and requires knowledge of the site geology, of the extent of the contaminant plume, and climatic conditions. Climatic conditions at the site are important in two ways: (1) the efficiency of atmospheric air in drying: soil depends on its absolute humidity: and (2) the amount of infiltration from precipitation influences how much water has to be removed from the soil to maintain a dry barrier. The size of the barrier, combined with the climatic conditions, determines the air flow required to maintain the system. while the hydraulic characteristics of the soils determine the location and design of air injection and extraction wells. The electric power rate structure must be known to calculate operating costs. The principal factors which determine the feasibility of a dry barrier include: (1) the climate at the site and, most importantly, low‐absolute atmospheric humidity during much of the year; (2) a substantial unsaturated zone; and (3) the ability to circulate air through the unsaturated zone. The amount of initial soil moisture in the layer through which air is circulated may be an important factor in the feasibility of a dry barrier. A design study is presented that illustrates the trade‐offs between high capital costs of constructing a large number of air circulation wells vs. the high operating costs required to pump large volume of air over long distances through fewer wells. This study found that, under conditions similar to those in many arid regions, a dry barrier may be a technically and economically viable method of providing temporary waste containment.

Transpiration from sorghum and soybean growing under ambient and elevated CO 2 concentrations

The increasing concentration of carbon dioxide in the atmosphere ([CO 2]) has several direct effects on plants and these effects may be different for C 3 and C 4 plants. Our objective was to measure hourly and daily whole-plant transpiration rates from the C 4 plant grain sorghum ( Sorghum bicolor (L.) Moench) and the C 3 plant soybean ( Glycine max (L.) Merr.) grown under ambient (359 μmolCO 2 mol −1 dry atmospheric air) and elevated (705 μmol mol −1)[CO 2] values. Transpiration measurements were made for 22 days in August 1994 at Auburn, Alabama, USA, using stem flow gauges on plants growing in open top chambers, n = 8 for each [CO 2] and species. Leaf area averaged slightly more than 0.1 m 2 per plant for sorghum and about 0.2 m 2 per plant for soybean. Averages (15 min and daily) of transpiration, per unit leaf area, were consistently greater from plants growing under the ambient [CO 2] for both sorghum and soybean. Average daily transpiration from plants growing under the elevated [CO 2] was significantly smaller ( P = 0.05) on all but 2 days for soybean and on 9 of the 22 days of measurements for sorghum. Average daily sorghum transpiration was 1128 gm −2 day −1 and 772g m −2 day −1 from plants growing under an ambient and elevated [CO 2], respectively. Corresponding soybean averages were 731g m −2 day −1 and 416g m −2 day −1. The transpiration reduction under elevated [CO 2] was greater for the C 3 plant soybean than for the C 4 plant sorghum. These results support previous studies showing that transpiration, per unit leaf area, from sorghum and soybean will both be reduced if atmospheric [CO 2] continues to increase, although the reduction may be greater for C 3 plants.

A Static Dilution System to Produce Trace Level Gas Standards for Chromatography

Equipment for producing gas standards for quantitative trace chromatographic analysis of extraneous gases in hydrogen is described. Several mixtures of small amounts of dry atmospheric air and ultrapure hydrogen and of concentrated gas mixtures in ultrapure hydrogen are made in a static-type system. In the air samples, the N 2 concentration varies between 0-410 μL/L, and the O 2 concentration varies between 0-115 μL/L. Calibration of the system and method, as well as data showing reproducibility, are reported. The results indicate that the system produces gas standards for quantitative analysis of O 2 , N 2 , and other gases in bulk H 2 . The advantages of this method are its versatility and reliability.

Reduction processes of amorphous GeO2 by hydrogen

A study of the reactivity of amorphous materials compared with that of crystalline materials would appear worthwhile, but little attention has been paid to this problem. In an earlier study, Baba [1] found a difference in the kinetic behaviour between amorphous and hexagonal GeO2 in the hydrogen reduction process. He suggested that the difference is mainly due to differences in surface conditions, i.e. the number of active sites which play a part in the formation of nuclei of the product and their growth. We have observed the same reaction with special reference to the initial process at temperatures of 450 to 530°C and at hydrogen pressures below 300 torr. The e (extent of reaction) against t (time) curves for crystalline GeO2 were sigmoidal, which is commonly encountered in solid-state reactions, whereas the curves for amorphous materials showed a complicated behaviour. This behaviour appeared to be explicable by glass transition and crystallization of the reactant during the reaction. As far as we know, such anomalous behaviour of amorphous material has not yet been reported. Kinetic measurements were carried out isothermally in a static system using a vacuum electrobalance (Cahn RG-2000). The amorphous sample was prepared as described previously [2]. The glass transition temperature (Tg) was found to be in the range 530 to 550 ° C, according to thermal analysis. It was also confirmed that crystallization occurs after prolonged heating above 700 ° C. Prior to use, about 100rag powdered sample was treated for 1 h with atmospheric dry air at a temperature below Tg and then evacuated at reaction temperature for 30min under a vacuum of 10 -5 torr. In some cases, after the reaction was stopped at known extent of reaction, changes in the surface area and structure of the partially reduced sample were observed by the BET adsorption of nitrogen and X-ray diffractometry, respectively.

Thermoelectric and mechanical conversion of solar power

It has been frequently demonstrated that solar energy can produce power by its direct heating effect. It has previously been overlooked, however, that sunshine stores vast amounts of free energy in the atmosphere by lowering its relative humidity, particularly in desert areas. The presently described equipment is a composite of a solar collector, a thermoelectric generator, and a mechanical converter which will generate power from waste heat and stored free energy of dry atmospheric air. The mechanical converter is unusual in its simplicity, its flexibility, and its capability to use small temperature differentials. Although the mechanical converter is described as associated with a reflecting solar collector, field tests may show the mechanical converter to be more practical without the collector, in which case air of the greatest usefulness would be collected from the surface of the solar heated ground by a grid of air ducts. Several cycle variations are possible with the same basic machine, which uses air as the working substance. Although the use of salt or fresh water for evaporation improves the power output, the mechanical converter will operate without evaporating water if water cannot be obtained.

An instrument for the speedy volumetric determination of carbonic acid

The principle of this instrument is the absorption of carbonic acid in a closed receiver by potassium hydrate, and the accurate measurement of the volume of dry atmospheric air required to re-establish the atmospheric pressure after complete absorption. The volume of air used for that purpose will exactly correspond to that of the carbonic acid gas absorbed. It is obvious that whatever be the reading of the barometer, the volume of air corresponding to that of the carbonic acid absorbed, will give the correct proportion of carbonic acid in the air submitted to' analysis ; but to obtain the weight of the gas present, and its proportion by weight, it will be necessary to reduce both the volumes of air analysed and of carbonic acid found to their volume at 0° (C.), and under a pressure of 760 mm. of mercury. Hence the necessity of recording the height of the barometer at the time of the experiment, or one reading may suffice for a number of determinations. The instrument resembles two small gasometers, and consists of two tanks and two bell-jars, or air-holders, each of the latter being made to hold half a cubic foot of air. The bell-jars hang on a metallic cord which connects them with each other, and passes over two pulleys, allowing the bell-jars to be moved up and down alternately in the tanks. The inside of the bell-jars communicates with the outside air by means of a ⋃ -shaped iron pipe, one limb of which opens inside the bell-jar above the fluid it contains, and the other outside on a somewhat lower level for sake of convenience. The tanks or troughs contain glycerine, over which floats a layer of almond oil an inch or two in thickness, and filling approximately the trough. The opening of the pipe above the surface of the oil enters loosely, so as to leave free passage of air, a neck in the bell-jar admitting a thermometer fitted air-tight through it. By this arrangement when the bell-jar is lowered, the thermometer descends into the inner limb of the ⋃ -pipe or stand-pipe without dipping into the oil or glycerine.

XVII. On the change in the elastic force of a constant volume of dry atmospheric air, between 32º F. and 212º F., and on the temperature of the freezing-point of mercury

The author gave a detailed description of his apparatus, and of the method employed in drying the air. The result of his experiments gave as the coefficient of increase of elasticity of air of constant volume for 1° F . 0·002040, this being slightly different from that given by Regnault, which is 0·002036.

On the thermal effects of elastic fluids

The authors had already proved by experiments conducted on a small scale, that when dry atmospheric air, exposed to pressure, is made to percolate a plug of non-conducting porous material, a depression of temperature takes place increasing in some proportion with the pressure of the air in the receiver. The numerous sources of error which were to be apprehended in experiments of this kind conducted on a small scale, induced the authors to apply for the means of executing them on a larger scale; and the present paper contains the introductory part of their researches with apparatus furnished by the Royal Society, comprising a force pump worked by a steam-engine and capable of propelling 250 cubic inches of air per second, and a series of tubes by which the elastic fluid is conveyed through a bath of water, by which its temperature is regulated, a flange at the terminal permitting the attachment of any nozle which is desired.