Equivalent Gas Research Articles

CHOS gas/fluid‐induced reduction in ureilites

AbstractUreilite meteorites contain regions of localized olivine reduction to Fe metal widely accepted to have formed by redox reactions involving oxidation of graphite, a process known as secondary smelting. However, the possibility that other reductants might be responsible for this process has largely been ignored. Here, 17 ureilite samples are investigated to assess whether, instead of smelting involving only solid reactants, a CHOS gas/fluid could have caused much of the smelting. Features consistent with gas‐ or supercritical fluid‐driven reduction were found to be abundant in all ureilites, such as fracture‐focused smelting, plume‐like reaction fronts, and addition of sulfur. Many of these are developed away from graphite. In some ureilites, it is clear that the redox process coincided with annealing, and we suggest that this was caused by enhanced diffusion facilitated by a higher density gas or fluid, rather than slow cooling, which requires elevated pressure. The C‐CO and CH4‐C‐H2O buffers were modeled to examine their relative potential to drive reduction. This modeling showed that a CH4‐rich fluid is able to produce the observed mineral compositions at elevated pressures. This result, coupled with the observed textures, is used to develop a likely series of reactions. We suggest that at higher pressures, a H2‐CH4‐H2S‐S2‐bearing fluid‐like phase, and at lower pressures, an equivalent gas, were able to infiltrate grain boundaries and fine fractures. Sulfidation to form troilite may have acted to maintain highly reduced gas/fluid conditions. The presence of hydrocarbons in ureilites supports a role for reduction driven by CHOS gas/fluid.

Energy calibration of the GEMPix in the energy range of 6 keV to 2 MeV

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 μm pixel pitch and a total of 262,144 pixels (512×512 pixels). A continuous flow of a gas mixture (here propane-based tissue equivalent gas) is supplied externally at a rate of 5 L/h. By placing a sealed 241Am source outside of the detector and varying the source-detector distance, the residual energy of alpha particles entering the sensitive volume of the GEMPix through a thin Mylar window is varied. An alpha spectrometry measurement was performed to determine the emission spectrum of the source, and this spectrum was then used as an input to a FLUKA Monte Carlo simulation to obtain the residual energy of the alpha particles. Thus, a calibration curve from 5.9 keV (from an 55Fe source) up to more than 2 MeV was obtained, which is needed for future applications of the detector, in particular for microdosimetry.

Implicit solvation in domain based pair natural orbital coupled cluster (DLPNO-CCSD) theory.

A nearly linear scaling implementation of coupled-cluster with singles and doubles excitations (CCSD) can be achieved by means of the domain-based local pair natural orbital (DLPNO) method. The combination of DLPNO-CCSD with implicit solvation methods allows the calculation of accurate energies and chemical properties of solvated systems at an affordable computational cost. We have efficiently implemented different schemes within the conductor-like polarizable continuum model (C-PCM) for DLPNO-CCSD in the ORCA quantum chemistry suite. In our implementation, the overhead due to the additional solvent terms amounts to less than 5% of the time the equivalent gas phase job takes. Our results for organic neutrals and open-shell ions in water show that for most systems, adding solvation terms to the coupled-cluster amplitudes equations and to the energy leads to small changes in the total energy compared to only considering solvated orbitals and corrections to the reference energy. However, when the solute contains certain functional groups, such as carbonyl or nitrile groups, the changes in the energy are larger and estimated to be around 0.04 and 0.02 kcal/mol for each carbonyl and nitrile group in the solute, respectively. For solutes containing metals, the use of accurate CC/C-PCM schemes is crucial to account for correlation solvation effects. Simultaneously, we have calculated the electrostatic component of the solvation energy for neutrals and ions in water for the different DLPNO-CCSD/C-PCM schemes. We observe negligible changes in the deviation between DLPNO-CCSD and canonical-CCSD data. Here, DLPNO-CCSD results outperform those for Hartree-Fock and density functional theory calculations.

An innovative hybrid solar preheating intercooled gas turbine using parabolic trough collectors

In this study, a new hybrid solar preheating intercooled gas turbine (SP-IcGT), is presented, in which a parabolic trough solar technology is used to preheat the compressed air before entering the combustor. The performance of the new hybrid gas turbine was evaluated and compared with the conventional hybrid solar preheating gas turbine (SP-GT). Several performance indicators were used in the analysis under Guangzhou (China) weather data. It is observed that the SP-IcGT is superior to the SP-GT system as it can boost the fuel-based efficiency by 19.35% versus 0.26% for the SP-GT system. In addition, the SP-IcGT has a much lower specific fuel consumption (about 7017 kJ/kWh) compared with the 10362 kJ/kWh for SP-GT. The highest fuel-based efficiency of 51.4% is obtained for the SP-IcGT with 47.4% improvement over the SP-GT, which exhibits a levelized electricity cost of 4.58 US/kWh. Meanwhile, fuel consumption and greenhouse gas emissions can be reduced greatly by integrating solar energy with the intercooled gas turbine. The SP-IcGT is more economical than applying carbon capture to the equivalent conventional gas turbine plant combined while achieving the same reduction of CO2 emissions. Overall, the SP-IcGT is an attractive system under different climates.

Numerical and experimental study on high-speed hydrogen–oxygen combustion gas flow and aerodynamic heating characteristics

The need to increase the payload capacity of the rockets motivates the development of high-power rocket engines. For a chemical propulsion system, this results in an increasing thermal load on the structure, especially the combustion chamber and nozzle must be able to withstand the extreme thermal load caused by high-temperature and high-pressure combustion gas. In order to protect the structure from the effect of increasing heat flux, it is necessary to counteract such effect with more advanced thermal management technology. This requires us to accurately predict the aerodynamic heating of the structure by high-temperature and high-speed combustion gas. In this study, a high-temperature combustion gas tunnel developed in the laboratory is used to produce high-speed combustion gas. Combined with the results of numerical calculation, the flow and aerodynamic heating characteristics of air and hydrogen–oxygen combustion gas under the same total temperature and pressure are analyzed and compared. The comparison revealed that the combustion gas flow in the nozzle has higher static temperature, velocity, and smaller Mach number. When the combustion gas flows around the sphere, the shock standoff distance and stagnation pressure are smaller than those of air, and the wall heat flux is much larger than that of air. The active chemical reaction in the combustion gas makes the aerodynamic heating of the structure more severe. Finally, through the analysis of a large amount of data, a semi-empirical formula for the heat flux of the stagnation point heated by a high-speed hydrogen and oxygen equivalent ratio combustion gas is obtained.

Enhancement of toluene oxidation performance over Cu–Mn composite oxides by regulating oxygen vacancy

Oxygen vacancy plays an important role in regulating the chemical and catalytic properties of catalysts. In this paper, Cu-Mn composite oxide catalyst was firstly synthesized by hydrothermal method and then modified by urea solid reaction treatment to obtain CM-X catalysts (X = 2, 4, 6, where × represents the weight ratio of urea/CM catalyst) with different oxygen vacancy concentrations. The relationship between the structure and catalytic performance of these catalysts was analyzed by a variety of characterization techniques. The CM-4 sample showed the maximum specific surface area, which enhanced the adsorption capacity of the catalyst to the reactants. Moreover, there existed a large number of oxygen vacancies in CM-4 samples, leading to the amount increase of adsorbed oxygen species on the surface and high migration ability of lattice oxygen, which can improve the catalyst reducibility and oxygen species activity. Therefore, the CM-4 catalyst showed the excellent catalytic activity and stability for toluene oxidation, and toluene could be completely oxidized into CO2 and H2O at 215 °C under the equivalent gas hourly space velocity (GHSV) of 22,500 mLg-1h−1. And it was found by in situ DRIFTS experiment that the oxidation of toluene occurs via the benzyl alcohol-benzoate-anhydride reaction pathway on CM-4 catalyst.

Experimental study on the conductance of pure and binary gas mixtures

A binary gas mixture conductance measurement apparatus with an independent gas distribution system was established, the constant volume method to measure the conductance of the mixed gas was used. Also, the conductance of pure gas Ar, He, N2 and binary gas mixtures Ar–He, N2–He, Ar–N2 through a short tube under different gas distribution chamber pressures and different molar fractions were measured. Meanwhile, the equivalent single gas method was used to calculate the conductance of binary gas mixtures. To verify the accuracy of this method, the relative error between the calculated and the measurement was carried out. The result shows that the equivalent single gas method is suitable for a small Knudsen number (1/Kn≥10), the molar fraction of lighter species is low and a small difference in the molecular mass of the components in the mixed gas. The uncertainty of conductance measurement is better than 3.1%.

Enhanced carbon dioxide sequestration by direct injection of flue gas doped with hydrogen into hydrate reservoir: Possibility of natural gas production

Methane recovery from the natural gas hydrates (NGH) represent the largest source of hydrocarbon energy in the world. However, the existing methods of methane recovery are constrained by low efficiency and ecological impact. One method which can offer methane recovery with simultaneous reduction in atmospheric carbon accumulation is carbon dioxide (CO2) injection into methane (CH4) dominated hydrates. This method may also ensure long term CO2 storage in the cages of recovered methane. However, obtaining huge amount of pure CO2 and its storage stability at real saline conditions of hydrate media are two important aspects for a sustainable methane recovery project. This study focuses on reducing reliance on pure CO2 and therefore, an equivalent flue gas composition of CO2 and nitrogen (N2, 0–80 mol%) is tested for hydrate potential. The study is an experimental investigation of CO2 hydrate formation (N2 as binary gas) in common seabed conditions of 2–8 °C and 35–75 bar. The inclusion of N2 was found to depress the conditions of hydrate formation of CO2 and at high N2 composition [40 mol% for saline water and 45 mol% for fresh water], no hydrates formed. The presence of salt was also found to reduce the amount of gas consumption which inhibited the hydrate formation. Further, the role of hydrogen (H2) (in minute compositions, 0.1 and 1 mol%) was investigated as a promoter to enhance hydrate formation at unstable conditions (gas mixtures with higher N2 composition). H2 showed significant increase in gas consumption by 12–18%. Increasing H2 composition (from 0.1 to 1 mol%) was able to restore hydrate formation under saline conditions even in the presence of >40 mol% N2. Based on this study, the use of H2 is recommended as a promoter to ensure long term storage of CO2 in hydrates with its simultaneous usage for sustainable CH4 production.

Analysis of micro-dose spectrum influencing factors based on tissue equivalent proportional counter

The tissue equivalent proportional counter (TEPC) is often used in the measurement of ionizing radiation. However, there are many factors that can cause the micro-dose spectrum’s distortion and affect the accuracy of the measurement. In the TEPC design process, several factors can be analyzed through simulation methods. The simulation capabilities of the TEPC physical process are established and verified in this paper. The wall material, tissue equivalent gas, and electrode are selected as the main objects, and the corresponding design choices are given. The wall material has a great impact on the spectrum, and y¯F and y¯D show that A-150 plastic is closer to the human tissue in the TEPC physical process simulation. Both the two tissue equivalent gases have good simulation accuracy. After further analysis, propane-based equivalent gas is the better choice. Among the three electrode sizes, the size of 0.006 35 cm is the most suitable one for TEPC. The analysis results and analysis methods can provide references for the important elements design of TEPC.

Aerosol emissions from water-lean solvents for post-combustion CO2 capture

Advanced water-lean solvents (WLS) for post-combustion CO2 capture have been gaining interest due to their ability to reduce the parasitic penalty from energy needed for solvent regeneration. Commercial implementation of these novel CO2 capture technologies hinges on successful control of amine emissions.RTI conducted a parametric study of fundamental and operational variables influence on overall amine aerosol and vapor emissions from our water-lean solvent eCO2Sol™ using our 6-kW equivalent bench-scale gas absorption system. The parametric testing used a simulated flue gas with 15 % CO2, 2.3–4.2 % H2O, and 0–6 ppm sulfite (SO3) to examine the impact of the presence of aerosols to the capture performance and amine emissions from the system. The SO3 reacts with water in the flue gas to create H2SO4, which forms liquid aerosol droplets and provide nucleation sites for growth of aerosols. Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer instruments monitored the aerosol particle size distribution.Parametric testing results suggested that the presence of the aerosols in the flue gas could increase the overall amine emissions by 10X compared to the baseline emissions from WLS’s vapor pressure. Principal component analysis (PCA) and projection to latent squares (PLS) developed models to predict the aerosol-based amine emissions from process data. The predictive PLS model had a correlation coefficient (Q2) of 0.92 and could predict the aerosol-based emissions from the NAS process with ±15 % accuracy (average absolute deviation, AAD). The PLS regression model also identified key variables affecting aerosol-based emissions from WLS.

Integrating environmental and social impacts into optimal design of guayule and guar supply chains

Guayule and guar are two desert-dwelling crops that can provide raw materials year-round for bioproducts such as rubber, resin, guar gum, and guar meal. Both crops are low-water-use, drought-tolerant, as well as heat-resistant, and these features enable their great potential for the agricultural economy in the Southwestern U.S. However, there exist challenges when considering the design of their supply chains in not only the economic benefits but also the environmental and social impacts, such as the process facility location and transportation problems. Furthermore, the optimal supply chains are heavily dependent on the amount of crop production, which can be measured by the adoption rate, i.e., the percentage of current crops in the field that is switched to either guayule or guar. In this paper, stochastic scenarios are utilized to capture the uncertainties of the adoption rates of each field. Afterward, a stochastic optimization is deployed to identify optimal decisions for facility locations, transportations from fields to facilities, and finally to customers, with a multi-objective approach to quantify the economic benefits (minimizing the costs of supply chains), environmental impacts (minimizing CO2 equivalent greenhouse gas emissions), and social impacts (maximizing the local accrued jobs). Based on the Geographic Information System for capturing field information and relevant factors, and deciding facility locations, the model is formulated as a complex large-scale mixed-integer linear optimization problem. For an efficient solution, the Benders Decomposition algorithm is implemented. The proposed approaches are evaluated based on the cases of two areas: Maricopa and Pinal counties in Arizona for the guayule supply chain, and Dona Ana County in New Mexico for the guar supply chain.

Medical Applications of the GEMPix

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 µm pixel pitch and a total of 262,144 pixels. A continuous flow of a gas mixture such as Ar:CO2:CF4, Ar:CO2 or propane-based tissue equivalent gas is supplied externally at a rate of 5 L/h. This article reviews the medical applications of the GEMPix. These include relative dose measurements in conventional photon radiation therapy and in carbon ion beams, by which on-line 2D dose images provided a similar or better performance compared to gafchromic films. Depth scans in a water phantom with 12C ions allowed measuring the 3D energy deposition and reconstructing the Bragg curve of a pencil beam. Microdosimetric measurements performed in neutron and photon fields allowed comparing dose spectra with those from Tissue Equivalent Proportional Counters and, additionally, to obtain particle track images. Some preliminary measurements performed to check the capabilities as the detector in proton tomography are also illustrated. The most important on-going developments are: (1) a new, larger area readout to cover the typical maximum field size in radiation therapy of 20 × 20 cm2; (2) a sealed and low-pressure version to facilitate measurements and to increase the equivalent spatial resolution for microdosimetry; (3) 3D particle track reconstruction when operating the GEMPix as a Time Projection Chamber.

Aerosol Emissions from Water-lean Solvents for Post-combustion CO2 Capture

Advanced water-lean solvents (WLS) for post-combustion CO2 capture have been gaining interest due to their ability to reduce the parasitic penalty from energy needed for solvent regeneration. Commercial implementation of these novel CO2 capture technologies hinges on successful control of amine emissions. RTI conducted a parametric study of fundamental and operational variables influence on overall amine aerosol and vapor emissions from our water-lean solvent eCO2Sol™ using our 6-kW equivalent bench-scale gas absorption system. The parametric testing used a simulated flue gas with 15 % CO2, 2.3–4.2 % H2O, and 0–6 ppm sulfite (SO3) to examine the impact of the presence of aerosols to the capture performance and amine emissions from the system. The SO3 reacts with water in the flue gas to create H2SO4, which forms liquid aerosol droplets and provide nucleation sites for growth of aerosols. Scanning Mobility Particle Sizer and Aerodynamic Particle Sizer instruments monitored the aerosol particle size distribution. Parametric testing results suggested that the presence of the aerosols in the flue gas could increase the overall amine emissions by 10X compared to the baseline emissions from WLS’s vapor pressure. Principal component analysis (PCA) and projection to latent squares (PLS) developed models to predict the aerosol-based amine emissions from process data. The predictive PLS model had a correlation coefficient (Q2) of 0.92 and could predict the aerosol-based emissions from the NAS process with ±15 % accuracy (average absolute deviation, AAD). The PLS regression model also identified key variables affecting aerosol-based emissions from WLS.

Can the 1.5 ℃ warming target be met in a global transition to 100% renewable energy?

<abstract> <p>First, we recognize the valuable previous studies which model renewable energy growth with complete termination of fossil fuels along with assumptions of the remaining carbon budgets to reach IPCC warming targets. However, these studies use very complex combined economic/physical modeling and commonly lack transparency regarding the sensitivity to assumed inputs. Moreover, it is not clear that energy poverty with its big present impact in the global South has been eliminated in their scenarios. Further, their CO<sub>2</sub>-equivalent natural gas emission factors are underestimated, which will have significant impact on the computed greenhouse gas emissions. Therefore, we address this question in a transparent modeling study: can the 1.5 ℃ warming target still be met with an aggressive phaseout of fossil fuels coupled with a 100% replacement by renewable energy? We compute the continuous generation of global wind/solar energy power along with the cumulative carbon dioxide equivalent emissions in a complete phaseout of fossil fuels over a 20 year period. We compare these computed emissions with the state-of-the-science estimates for the remaining carbon budget of carbon dioxide emissions consistent with the 1.5 ℃ warming target, concluding that it is still possible to meet this warming target if the creation of a global 100% renewable energy transition of sufficient capacity begins very soon which will likely be needed to power aggressive negative carbon emission technology. The latter is focused on direct air capture for crustal storage. More efficient renewable technologies in the near future will make this transition easier and promote the implementation of a global circular economy. Taking into account technological improvements in 2<sup>nd</sup> law (exergy) efficiencies reducing the necessary global energy demand, the renewable supply should likely be no more than 1.5 times the present level, with the capacity to eliminate global energy poverty, for climate mitigation and adaptation.</p> </abstract>

Thermal and gas purification of natural graphite for nuclear applications

Natural graphite such as flake graphite and microcrystalline graphite have important applications in nuclear engineering, especially in high-temperature gas-cooled reactors. Owing to requirements for low ash content and total equivalent boron content, thermal and gas purification is necessary for producing natural graphite powder with nuclear-grade purity. In this study, representative Chinese flake graphite and microcrystalline graphite were purified thermally or with halogens at graphitization temperatures. By thermal purification at 3000 °C, natural flake graphite and microcrystalline graphite containing at least 99.9% carbon was achieved. The metallic impurities remaining after thermal purification were mainly elements that formed carbides with extraordinarily high melting/boiling points, such as B, Ti, Ta, V, W, and Mo. Gas purification with halogens further increased the purity of natural flake graphite and microcrystalline graphite to nuclear grade, that is, the ash content and total equivalent boron content were less than 50 ppm and 0.01 ppm, respectively. Meanwhile, an investigation of the purification mechanism helped to understand the chemistry and thermodynamics of thermal purification of natural graphite.

Pharmaceutical and Supply Waste in Oculofacial Plastic Surgery at a Hospital-Based Outpatient Surgery Center.

To investigate the financial and environmental waste burden of unused disposable surgical supplies and pharmaceutical products in oculofacial plastic surgery at a hospital-based outpatient surgery center. This descriptive study was performed at a single academic hospital-based outpatient surgery center. Unused pharmaceuticals and disposable surgical materials were recorded for each of 34 consecutive oculofacial plastic surgeries performed by the same surgical team. Pharmaceutical products were grouped as local anesthetic (tetracaine, bupivacaine, lidocaine, and sodium bicarbonate), intraoperative (basic saline solution, methylene blue, and oxymetazoline hydrochloride), or antiseptic/antimicrobial (erythromycin ointment and hydrogen peroxide). Percentage of unused pharmaceutical product and disposable surgical material were calculated and extrapolated to direct costs to the institution and greenhouse gas emissions. The mean percentage of disposable surgical supply waste per case was 11.6% ($29.32). The mean percentage of pharmaceutical waste was 96.1% ($271.84) for local anesthetic, 71.0% ($163.47) for intraoperative medications, and 26.7% ($2.19) for antiseptic medication. The mean emissions per surgical case for unused disposable surgical equipment and unused pharmaceutical product were 10 and 103 kg of carbon equivalent gases (kg CO2-e), respectively. Surgical supply waste was nominal, but pharmaceutical waste was considerable in this single hospital-based outpatient surgery center study. There may exist opportunities for quality improvement in waste, especially pharmacologic burden, in oculofacial plastic surgery.

Liquid CO 2 high‐pressure fracturing of coal seams and gas extraction engineering tests using crossing holes: A case study of Panji Coal Mine No. 3, Huainan, China

Owing to the low coal permeability coefficients and poor gas extraction efficiencies associated with the extraction of coal in the Huainan coal mining area, the aim of this study was to design, for the first time, a high-pressure low-temperature liquid CO2 (LCO2) pump for engineering tests with respect to the fracturing of coal seams and the improvement of CH4 recovery in China. To reasonably calculate the initiation pressure for the coal seam fracturing as well as the gas flow parameters, theoretical analysis with field testing were integrated in the design. In addition, considering the interim gas extraction standard, the gas extraction equivalent radius based on this standard was calculated. The test results revealed a maximum LCO2 pressure of 20.6 MPa, which surpasses the theoretical maximum pressure (19.5 MPa) required for the fracturing of coal seams. During the entire gas extraction process, the CO2 concentrations in boreholes K1 and K3 decrease exponentially with time, showing attenuation coefficients of 0.0205 and 0.0231, respectively. The attenuation coefficients of the three attenuation stages of the original coal seam gas flow rate were 0.0314, 0.2142, and 0.1198, which were higher than those corresponding to the test area. The CH4 concentration in boreholes K1 and K3 in the test area were both higher than that in the original coal seam, and the maximum CH4 flow rates in these boreholes were 1.31- and 1.72-fold higher than that in the original coal seam, respectively. The comparative analysis of CH4 concentrations and flow rates indirectly showed an improvement in the permeability of the coal seam. Further, a quantitative equivalent gas extraction evaluation method based on LCO2 fracturing of coal seam and gas displacement was proposed. Furthermore, based on a comprehensive evaluation, the effective displacement radius caused by the LCO2 fracturing test was 9 m, with a displacement efficiency of 23.95%, and a displacement volume ratio of 0.21. This method offered the possibility of realizing the quantitative evaluation of the LCO2 injection amount and the gas extraction effect, and provides a basis for optimizing the LCO2 fracturing of coal seams as well as the gas extraction process.

A high-resolution emission inventory of air pollutants from primary crop residue burning over Northern India based on VIIRS thermal anomalies

Emissions from the crop residue burning adversely affect the regional and global air quality including public health. In this study, a district-wise comprehensive emission inventory of key pollutants (PM2.5, PM10, CO, CO2, SO2, NOx, N2O, NH3, CH4, NMVOC, EC, OC, PAH) emitted during primary crop residue burning was developed using activity data for the major agrarian states of north India for the agricultural year 2017–18. The emissions were scaled to the spatial resolution of 1 km grid to study the spatial distribution of crop residue burning activities using VIIRS Thermal anomalies datasets. An estimated 20.3 Mt and 9.6 Mt of crop residue were burned in Punjab and Haryana, resulting in an emission of 137.2 Gg and 56.9 Gg of PM2.5 and 163.7 Gg and 72.1 of PM10 Gg for respective states. The emissions of EC, OC, and PAHs were 8.6 Gg, 45.7 Gg, and 0.08 Gg in Punjab, whereas in Haryana emissions were 3.7 Gg, 17.7 Gg, and 0.03 Gg, respectively. The results show that rice and wheat crops were major contributor to residue burnt at the field (>90%) leading to the high load of atmospheric emissions in the IGP region. Further, CO2 equivalent greenhouse gas emissions were 34.8 Tg and 17.3 Tg for Punjab and Haryana, respectively. Around 30000 and 8500 active fires were detected by VIIRS over the agricultural area of Punjab and Haryana during the studied year. The GIS-based bottom-up approach using gridded emission inventory shows pollutant distribution dominates over the south-western part of Punjab and north-western region of Haryana. The proximity of these regions to Delhi and transboundary movement of emissions towards Indo-Gangetic plains causes high air pollution episodes. The high-resolution inventory of various pollutants will be useful for regional air quality models to better predict and manage the hotspot of air pollution.

Lower size limit of the simulated biological target by TEG counter

The gas gain in the range of 1.0–2 × 105 was measured for propane-based tissue equivalent gas mixtures in the pressure range of 9–500 hPa. The Zastawny and Mitev et al. models of avalanche growth were used to analyse the obtained data. Both models showed that for low pressures of the working mixture, (i.e., below 80 hPa), there were non–equilibrium states of the development of the electron avalanche. The minimum size of the simulated biological target was determined on the basis of the measurements.

Rheology in the Presence of Carbon Dioxide (CO2) to Study the Melt Behavior of Chemically Modified Polylactide (PLA).

For the preparation of polylactide (PLA)-based foams, it is commonly necessary to increase the melt strength of the polymer. Additives such as chain extenders (CE) or peroxides are often used to build up the molecular weight by branching or even crosslinking during reactive extrusion. Furthermore, a blowing agent with a low molecular weight, such as carbon dioxide (CO2), is introduced in the foaming process, which might affect the reactivity during extrusion. Offline rheological tests can help to measure and better understand the kinetics of the reaction, especially the reaction between the polymer and the chemical modifier. However, rheological measurements are mostly done in an inert nitrogen atmosphere without an equivalent gas loading of the polymer melt, like during the corresponding reactive extrusion process. Therefore, the influence of the blowing agent itself is not considered within these standard rheological measurements. Thus, in this study, a rheometer equipped with a pressure cell is used to conduct rheological measurements of neat and chemical-modified polymers in the presence of CO2 at pressures up to 40 bar. The specific effects of CO2 at elevated pressure on the reactivity between the polymer and the chemical modifiers (an organic peroxide and as second choice, an epoxy-based CE) were investigated and compared. It could be shown in the rheological experiments that the reactivity of the chain extender is reduced in the presence of CO2, while the peroxide is less affected. Finally, it was possible to detect the recrystallization temperature Trc of the unmodified and unbranched sample by the torque maximum in the rheometer, representing the tear off of the stamp from the sample. Trc was about 13 K lower in the CO2-loaded sample. Furthermore, it was possible to detect the influences of branching and gas loading simultaneously. Here the influence of the branching on Trc was much higher in comparison to a gas loading.