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C5F10Ohas recently been found to be a very promising alternative to SF6. This paper is devoted to the investigation of compositions, thermodynamic properties, and transport coefficients of high-temperature C5F10O mixed with CO2 and O2. Firstly, the partition functions and enthalpies of formation for a few molecules (CxFy and CxFyO) which are likely to exist in the mixtures, are calculated based on the G4(MP2) theory. The isomers of the above molecules are selected according to their Gibbs energy. The compositions of C5F10O-CO2-O2 mixtures are then determined using the minimization of the Gibbs free energy. Next, the thermodynamic properties (mass density, specific enthalpy, and specific heat) are derived from the previously calculated compositions. Lastly, the transport coefficients (electrical conductivity, viscosity, and thermal conductivity) are calculated based on Chapman-Enskog method. It is found that, as an arc quenching gas,C5F10O could not recombine into itself with the temperature decreasing down to room temperature after the arc extinction. Besides, the key species at room temperature are always CF4, CO2, and C4F6 if graphite is not considered. When taken into account, graphite will replace C4F6 as one of the dominate particles. The mixing of CO2 with C5F10O plasma significantly affects the thermodynamic properties (e.g. vanishing and/or shifting of the peaks in specific heat) and transport coefficients (e.g. reducing viscosity and changing the number of peaks in thermal conductivity), while the addition of O2 with C5F10O-CO2 mixtures has no remarkable influence on both thermodynamic and transport properties. [ABSTRACT FROM AUTHOR]

This paper contains new, representative reference equations for the thermal conductivity of carbon dioxide. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, we incorporated recent theoretical calculations to extend the temperature range of the experimental data. Moreover, in the critical region, the experimentally observed enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter. The correlation is applicable for the temperature range from the triple point to 1100 K and pressures up to 200 MPa. The overall uncertainty (at the 95% confidence level) of the proposed correlation varies depending on the state point from a low of 1% at very low pressures below 0.1 MPa between 300 and 700 K, to 5% at the higher pressures of the range of validity. [ABSTRACT FROM AUTHOR]

This paper describes a semi-quantitative method, suitable for a student laboratory exercise that shows that the acoustic properties of the soundbox of a musical instrument depend on the sound speed of the atmosphere surrounding and filling the instrument. A gas tent was constructed and used to enclose instruments in helium, carbon dioxide and mixtures thereof, allowing the sound speed to be varied from 250 to 1000 m/s. Soundboard admittance data were taken using a guitar and a violin as examples. The data, expressed as contour plots, show clearly the qualitative relationship between air and wood modes, and the guitar data are compared with a simple mechanical model. Experimental details of the construction and operation of gas tent are given, with attention paid to safety issues. [ABSTRACT FROM AUTHOR]

Manganese (II) oxide (MnO), manganese (IV) oxide (MnO2), cobalt (II,III) oxide (Co3O4), and nickel (II) oxide (NiO) were analyzed with time-of-flight secondary ion mass spectrometry using 70 keV gas cluster ion beams. The obtained mass spectra are influenced by projectile chemistry and to a lesser extent velocity. Gas cluster ion beams containing CO2 or H2O enhanced the relative yield of metal oxide and metal hydroxide secondary ions compared to beams containing only Ar. For all gas cluster ion beams tested, steady-state ion ratios [MxOy]+/[Mx]+ were reached. For manganese oxides, the [MnxOy]+/[Mnx]+ ratio reflected the metal oxidation state whereas the [MnxOyHz]+/[Mnx]+ ion ratios did not. This study demonstrates that secondary ion mass spectrometry using 70 keV gas cluster ion beams provides a novel approach to the quantitative analysis of the surface and subsurface regions of metal oxides related to energy-storage materials. [ABSTRACT FROM AUTHOR]

The solid-liquid solubility data for well defined nonaqueous binary and ternary systems are reviewed. One component includes hydroxybenzoic acid, hydroxybenzoate, and hydroxybenzoic acid salt, and another component includes a variety of organic compounds (hydrocarbons, alcohols, halogenated hydrocarbons, carboxylic acids, esters, et al.) and carbon dioxide. The ternary systems include mixtures of organic substances of various classes and carbon dioxide. The total number of compilation sheets is 270 for six types of system. Almost all data are expressed as mass percent and mole fraction as well as the originally reported units, while some data are expressed as molar concentration. Critical evaluation was carried out for the binary nonaqueous systems of 2-, 3-, and 4-hydroxybenzoic acids and hydroxybenzoates (methylparaben, ethylparaben, propylparaben, and butylparaben) in alcohols, 1-heptane, and benzene. [ABSTRACT FROM AUTHOR]

The effects of temperature and nanometer-sized bubbles (NBs) on a superior electric storage capacitor for anodically oxidized films of AlY10 amorphous alloys were determined at temperatures ranging from 275 to 298 K in 0.4 M H2SO4 solutions with NBs of ozone, oxygen, and carbon dioxide. The AAO specimen obtained by solution with carbon dioxide NBs at 278 K showed longer discharging time. The discharging time increases with increasing charging time and then saturates after around 70 s. The increment in temperature makes the structure from simple series capacitor with large capacitance to simple parallel capacitor with lower capacitance and larger resistance. The stability of NBs in water could be explained by enclosure in protonated polyhedral water clusters. The collapse of clusters with oxygen NBs result in the formation of OH− radicals and its resulting elution of Al, while carbon oxide NBs prevent the formation of OH− radicals, promoting sluggish oxidation that is required for the formation of AlO6 clusters. [ABSTRACT FROM AUTHOR]

Calcium carbonate (CaCO3) is one of the most abundant minerals and of high importance in many areas of science including global CO2 exchange, industrial water treatment energy storage, and the formation of shells and skeletons. Industrially, calcium carbonate is also used in the production of cement, glasses, paints, plastics, rubbers, ceramics, and steel, as well as being a key material in oil refining and iron ore purification. CaCO3 displays a complex polymorphic behaviour which, despite numerous experiments, remains poorly characterised. In this paper, we report the use of a segmented-flow microfluidic reactor for the controlled precipitation of calcium carbonate and compare the resulting crystal properties with those obtained using both continuous flow microfluidic reactors and conventional bulk methods. Through combination of equal volumes of equimolar aqueous solutions of calcium chloride and sodium carbonate on the picoliter scale, it was possible to achieve excellent definition of both crystal size and size distribution. Furthermore, highly reproducible control over crystal polymorph could be realised, such that pure calcite, pure vaterite, or a mixture of calcite and vaterite could be precipitated depending on the reaction conditions and droplet-volumes employed. In contrast, the crystals precipitated in the continuous flow and bulk systems comprised of a mixture of calcite and vaterite and exhibited a broad distribution of sizes for all reaction conditions investigated. [ABSTRACT FROM AUTHOR]

Adsorption using carbon-based materials has been established to be a feasible method for separating carbon dioxide and hydrogen to mitigate the emission of carbon dioxide into the atmosphere and for the collection of fuel for energy sources, simultaneously. We carried out density functional theory calculation with dispersion correction to investigate the physisorption characteristics of carbon allotropes such as graphene and graphyne for the competitive adsorption of CO2 and H2. It is worth noting that the graphyne represented preferable adsorption energies, short bond lengths and energy charges for both gases, compared with the characteristics observed with graphene. We found that in graphyne, both the affinitive adsorption of CO2, and the competitive adsorption of CO2 and H2, took place at the hollow site between acetylene links, which do not exist in graphene. We demonstrate that in the presence of H2, the CO2 adsorption selectivity of graphyne is higher than that of graphene, because of the improved electronic properties resulting from the acetylene links. [ABSTRACT FROM AUTHOR]

A comprehensive database of experimental and computed data for the viscosity of carbon dioxide (CO2) was compiled and a new reference correlation was developed. Literature results based on an ab initio potential energy surface were the foundation of the correlation of the viscosity in the limit of zero density in the temperature range from 100 to 2000 K. Guided symbolic regression was employed to obtain a new functional form that extrapolates correctly to 0 and to 10 000 K. Coordinated measurements at low density made it possible to implement the temperature dependence of the Rainwater-Friend theory in the linear-in-density viscosity term. The residual viscosity could be formulated with a scaling term rg/T, the significance of which was confirmed by symbolic regression. The final viscosity correlation covers temperatures from 100 to 2000 K for gaseous CO2 and from 220 to 700 K with pressures along the melting line up to 8000 MPa for compressed and supercritical liquid states. The data representation is more accurate than with the previous correlations, and the covered pressure and temperature range is significantly extended. The critical enhancement of the viscosity of CO2 is included in the new correlation. [ABSTRACT FROM AUTHOR]

The mechanism of CO2 plasma ashing process was evaluated. CO2 plasma is a good candidate for the ashing process for photoresists because it generates a lot of CO2 ions. These ions can ash equivalent amounts of carbon film with less low-k damage than can oxygen radicals. A high ratio of CO2 ions to oxygen radicals in CO2 plasma can make the ashing process efficient with less low-k damage. The ratio can be controlled by changing the CO2 flow rate, chamber pressure, and radio frequency (RF). When a lower RF frequency of 2 MHz as a plasma generator was used, the authors reduced sidewall low-k damage in patterned structures. CO2 ions can perform anisotropic ashing because the velocity distribution of CO2 ions is directional due to acceleration with a plasma sheath. [ABSTRACT FROM AUTHOR]

A high fidelity computational fluid dynamic model is used to simulate the flow, pressure, and density fields generated in a cylindrical and a conical resonator by a vibrating end wall/piston producing high-amplitude standing waves. The waves in the conical resonator are found to be shock-less and can generate peak acoustic overpressures that exceed the initial undisturbed pressure by two to three times. A cylindrical (consonant) acoustic resonator has limitations to the output response observed at one end when the opposite end is acoustically excited. In the conical geometry (dissonant acoustic resonator) the linear acoustic input is converted to high energy un-shocked nonlinear acoustic output. The model is validated using past numerical results of standing waves in cylindrical resonators. The nonlinear nature of the harmonic response in the conical resonator system is further investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude nonlinear oscillations observed in the conical resonator can potentially enhance the performance of pulse tube thermoacoustic refrigerators and these conical resonators can be used as efficient mixers. [ABSTRACT FROM AUTHOR]

Silk is the generic name given to the fibrous proteins spun by a number of arthropods. During metamorphosis, the larva of the silk producing arthropods excrete silk-fiber from its mouth and spun it around the body to form a protective structure called cocoon. An adult moth emerges out from the cocoon after the dormant phase (pupal phase) varying from 2 weeks to 9 months. It is intriguing how CO/O and ambient temperature are regulated inside the cocoon during the development of the pupa. Here we show that the cocoon membrane is asymmetric, it allows preferential gating of CO from inside to outside and it regulates a physiological temperature inside the cocoon irrespective of the surrounding environment temperature. We demonstrate that under simulating CO rich external environment, the CO does not diffuse inside the cocoon. Whereas, when CO was injected inside the cocoon, it diffuses out in 20 s, indicating gating of CO from inside to outside the membrane. Removal of the calcium oxalate hydrate crystals which are naturally present on the outer surface of the cocoon affected the complete blockade of CO flow from outside to inside suggesting its role to trap most of the CO as hydrogen bonded bicarbonate on the surface. The weaved silk of the cocoon worked as the second barrier to prevent residual CO passage. Furthermore, we show that under two extreme natural temperature regime of 5 and 50 °C, a temperature of 25 and 34 °C respectively were maintained inside the cocoons. Our results demonstrate, how CO gating and thermoregulation helps in maintaining an ambient atmosphere inside the cocoon for the growth of pupa. Such natural architectural control of gas and temperature regulation could be helpful in developing energy saving structures and gas filters. [ABSTRACT FROM AUTHOR]

Permeation of water vapor, oxygen, nitrogen, and carbon dioxide through polymer films is measured by the programed valving mass spectrometry (PVMS) method. The results are calibrated with a standard permeation rate for each gas to determine the detection sensitivity. The calibrated lower detection limits are 1.90×10-7 g/m2 day for water vapor, 2.81×10-2 cm3/m2 day for oxygen, 2.15×10-2 cm3/m2 day for nitrogen, and 3.29×10-2 cm3/m2 day for carbon dioxide. The lower detection limits presented here for water vapor, nitrogen, and carbon dioxide are more than two orders of magnitude lower than the corresponding values offered by the NIST-traceable standard techniques. In addition, the PVMS water vapor lower detection limit meets the sensitivity requirement for detecting “ultrabarrier” water vapor permeation rates, while the oxygen lower detection limit is higher than that offered by the standard technique. However, the results suggest a modified measurement protocol and/or system modifications to overcome this limitation. Effusivity through a flow orifice was also examined using the PVMS method for the above gases. The effusion results from the flow orifice, combined with the permeation results from polymer samples, provide insight into the factors that may influence gas detection sensitivities. [ABSTRACT FROM AUTHOR]

The study of the propagation of ultrasound within a gas jet is extended to obtain waveguide effects, where the jet collimates the ultrasonic beam from a transducer within the flow. Two methods have been investigated to achieve this—cooling the gas within the air jet, and using a different gas whose acoustic velocity is lower than air. Cooling an air jet to a temperature less than that of the surrounding air produced a noticeable waveguide effect. In addition, studies have been carried out using other selected gases, such as carbon dioxide (CO2) with a lower acoustic velocity than air, and helium (He) with a higher value. The former gas enhanced confinement of the ultrasonic beam, whereas the latter caused divergence. An ideal solution was found to be a CO2/air mixture, which produced a well-collimated sound field along the axis, while limiting the excess attenuation of pure CO2 gas jets. The effectiveness of the waveguide using mixed gas jets in producing images in air-coupled testing of solids is demonstrated. © 2003 Acoustical Society of America. [ABSTRACT FROM AUTHOR]