Compact, UAV compatible, broadband, uncooled Spectrometer for multi-species atmospheric gas analysis

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This study investigates the optical and electronic properties of SnOx/Graphene Oxide (SnOx/GO) heterostructures, focusing on their sensitivity and selectivity to methane adsorption and its tunable light absorption capabilities across different wavelength ranges. By categorizing SnOx/GO heterostructures into four types based on the oxygen mole fraction (x) of SnOx, notable differences are observed in their light absorption, extinction coefficient, and reflectance. Among these, Type-C heterostructures demonstrate the highest absorption coefficient (~1.8 × 10⁵ cm ⁻ ¹), indicating strong potential for UV and visible light applications. Building upon the optimized Type-C SnOx/GO heterostructure, we further examine the effect of varying concentrations of methane molecules adsorbed on its surface. This leads to the classification of four additional heterostructure types- Type-I to Type-IV which are based on the methane molecules concentration adsorbed on the surface of an optimized SnOx/GO heterostructure. The interaction with methane further modulates the optoelectronic properties of heterostructure, with Type-II heterostructures demonstrating the highest extinction coefficient (~8.0 at 1000 nm) and strong near-infrared absorption. In contrast, Type-IV structures, characterized by the highest methane concentration, show a significant increase in reflectance (~0.85) and a reduction in absorption. Additionally, an energy distribution analysis of various atmospheric gases, such as CH₄, H₂O, and CO₂ were conducted to evaluate the selectivity of SnOx/GO heterostructure based sensors. The aim was to ensure minimal interference from other ambient gases. The analysis revealed that CH₄ exhibits a more negative energy state, indicating higher stability and a greater affinity for adsorption on the sensor surface compared to the other atmospheric gases. This stabilization highlights the interaction dynamics of the material, reinforcing its potential for diverse applications, including UV absorption, infrared transparency, and trace methane detection. Overall, these findings establish SnOx/GO heterostructures, particularly the Type-C variant with an optimal oxygen mole fraction (x), as promising candidates for advanced optical and methane gas-sensing technologies.

An apparatus has been designed and built to determine automatically the rate of release of helium from various solids as a function of temperature. The diffusion of He in single crystals of neutron irradiated LiH is used to describe the operation of the apparatus. Samples can be maintained in a vacuum or in an automatically maintained gas (other than noble gas) atmosphere and held at temperatures from 200 to 1400°C. Helium evolved from the sample is periodically removed. A quantitative determination and standardization for He are automatically performed. If a gas atmosphere is used, this is removed from the helium by use of a titanium sublimation pump. The He which remains is then measured with a low resolution high sensitivity residual gas analyzer (partial pressure gauge). The system is capable of measuring at least 10−10 cm3 STP helium.

Ice cores provide the only direct archive of past atmospheric greenhouse gases (GHG). However, physical and chemical processes occurring before, during, and after bubble enclosure can alter the atmospheric signal recorded in ice. In particular, gas diffusion within the bubble-clathrate transition zone (BCTZ) has been shown to generate centimeter-scale, non-atmospheric variability, which we refer to as the “Lüthi effect” (Lüthi et al., 2010). Below the BCTZ, diffusive smoothing dampens these non-atmospheric signals but also atmospheric variability. While the Lüthi effect and diffusive smoothing have been documented for CO2 and the δO2/N2 ratio, their impact on N2O and CH4 remains poorly constrained. In addition, chemical reactions within the ice can alter atmospheric signals, particularly for N2O, which has been shown to be produced in situ by nitrate reduction in dust-rich Antarctic ice during glacial periods.Here we investigate diffusion and in situ production processes potentially affecting CO2, CH4, and N2O by analyzing five samples from the BCTZ of the Talos Dome ice core (TALDICE). GHG concentrations were measured at centimeter-scale resolution using a novel laser sublimation extraction system coupled to a quantum cascade laser absorption spectrometer (Mächler et al., 2023). δO2/N2 ratios were analyzed by isotope ratio mass spectrometry following the recapture of the same samples after GHG measurements with the laser spectrometer.Our results show for the first time that N2O and CH4 are also affected by the Lüthi effect in the BCTZ. The strong 1:1 correlation between CO2 and N2O variability suggests similar diffusion coefficients for these gases. These findings provide new constraints on N2O diffusion, relevant for modeling diffusive smoothing in deep and old ice such as the recently drilled Beyond EPICA ice core. Consistent with previous studies, our results indicate that the N2O record in TALDICE is not significantly affected by the aforementioned in situ production during glacial periods. The atmospheric N2O signal can therefore be retrieved when measurements are either spatially averaged to smooth the centimeter-scale variability induced by the Lüthi effect, obtained above the BCTZ, or taken well below the BCTZ where diffusive smoothing has attenuated this variability.ReferencesLüthi, D., Bereiter, B., Stauffer, B., Winkler, R., Schwander, J., Kindler, P., Leuenberger, M., Kipfstuhl, S., Capron, E., Landais, A., Fischer, H., and Stocker, T. F.: CO2 and O2/N2 variations in and just below the bubble–clathrate transformation zone of Antarctic ice cores, Earth and Planetary Science Letters, 297, 226–233, https://doi.org/10.1016/j.epsl.2010.06.023, 2010.Mächler, L., Baggenstos, D., Krauss, F., Schmitt, J., Bereiter, B., Walther, R., Reinhard, C., Tuzson, B., Emmenegger, L., and Fischer, H.: Laser-induced sublimation extraction for centimeter-resolution multi-species greenhouse gas analysis on ice cores, Atmos. Meas. Tech., 16, 355–372, https://doi.org/10.5194/amt-16-355-2023, 2023.

This paper is intended to serve as a scientific basis to start discussions of the available environmental sampling techniques and equipment that have been used in the past that could be considered for use within the context of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) on-site inspections (OSI). This work contains information on the techniques, equipment, costs, and some operational procedures associated with environmental sampling that have actually been used in the past by the United States for the detection of nuclear explosions. This paper also includes a discussion of issues, recommendations, and questions needing further study within the context of the sampling and analysis of aquatic materials, atmospheric gases, atmospheric particulates, vegetation, sediments and soils, fauna, and drill-back materials.

Field tests are a practical method to assess aerobic fitness, but they demonstrate greater error variability than laboratory tests. The principal goals of this study were to identify potential sources of systematic error in 2 commonly used field tests (Cooper's 12-minute run [12MR] and the multistage shuttle run [MSR]) and estimate the reliability of the 2 tests from these data. In addition, criterion-related validity evidence for field tests was evaluated via Bland-Altman plots. To assess trends across test protocol and test trials, 60 subjects (mean age = 21.8 ± 3.6 years) completed 6 test trials, including 3 trials of each field test. Of these 60 individuals, 21 volunteers completed an incremental treadmill run and expired gas analysis (TR) that was used to establish criterion-related validity evidence for the 2 field tests. G-study analysis of the field test data returned a high reliability coefficient (ϕ = 0.96), with the largest amount of systematic error variance (4.3%) attributable to an interaction between subjects and test occasions. The MSR predicted Vo2max scores lower than those measured in the laboratory setting (p < 0.01), whereas 12MR and TR scores were not different (p > 0.05). However, Bland-Altman plots showed the 12MR to underestimate Vo2max scores at lower Vo2max values and overestimate Vo2max scores at higher values, a trend not observed in the MSR data. These data suggest high overall reliability for Vo2max field tests in young, healthy individuals. Nevertheless, test administrators must use caution when attempting to use field test data to predict criterion Vo2max scores. The MSR appears to be a more useful tool than the 12MR because of a consistent mean bias across fitness levels.

Preliminary results of absolute wavelength calibration of imaging X-ray crystal spectrometer on EAST

UV detection for excimer lamps using CVD diamond in various gaseous atmospheres

The technique of matrix isolation combined with Fourier transform infrared spectroscopy has been developed as a sensitive method for atmospheric trace gas analysis. Matrices of solid CO2 are grown at 77K using natural CO2 as the matrix material, in which the atmospheric trace gases are embedded. Analysis of the matrix by FTIR absorption spectroscopy yields simultaneous measurements of a wide range of atmospheric trace gas species, including unstable and reactive ones, with detection limits typically around 101i molecules or 10-11 mixing ratio from a 20-40 litre air sample.

The performance of a separated crystal X-ray monochromator during wiggler heating — Preliminary results

Steep ramp test protocol for preoperative risk assessment and short-term high-intensity interval training to evaluate, improve, and monitor cardiorespiratory fitness in surgical oncology.

Design, analyses, and field test of a 0.7 m conical shaped charge

Currently, hydraulic isolation of wells drilled with nonaqueous fluids (NAFs) relies heavily on the elimination of mud from the annuli before the placement of cement. Failure to expel all NAFs will result in residual fluid channels that will compromise well integrity and can even serve as nonproductive communication pathways during subsequent stimulation treatments. To mitigate this risk, an interactive cementing system is presented that is designed to reduce conductivity of the residual mud channels. Although mud removal remains an integral part of the cementing process, this new cement formulation was developed to improve zonal isolation in the case of poor mud removal. The unique cement system reacts with the hydrocarbons present in NAFs, leading to a reduction of channel permeability and mobility. This significantly improves the likelihood of hydraulic isolation. Specialized testing protocols were developed to enable the demonstration of the capabilities of this new system. In addition, API testing methods and analytical techniques were used to optimize the slurry. The development of the new cement system focused on the optimization of the active component concentration to give a favorable interaction with NAF, and at the same time, minimize the effect on cement rheology and mechanical properties. Procedures developed in-house demonstrated that the new system effectively reduces hydraulic conductivity of microannuli as well as channels up to several tenths of inches in size. Zonal isolation laboratory experiments were extrapolated to predict whether the modified channels can withstand the range of differential pressures typically seen between neighboring fracturing stages. This is the most critical operation that the cement sheath would be subject to. Field tests are on-going at the time of writing this manuscript, and the preliminary results will be presented and discussed in this paper.

A brief review of the analytical methotis for the analysis of ozone in air leads to the opinion that present methods are not completely adequate. The possible use of a new technique employing the reaction between peroxy compounds and aromatic iso-cyanates is investigated and the preliminary results indicated this approach might have advantages over present methods. However, further field testing is necessary to document the practicality of this technique.

A field test was run during 1997 and 1998 to collect preliminary data on a solvent gas injection process. The site selected for the test was a "typical" Frog Lake, Alberta, Cummings formation reservoir that had been depleted using PC pump-based cold production methods on both 4 hectare (10 acre) and 8.1 hectare (20 acre) spacing. At the time of solvent injection, area average recovery from the test location was 9.5%, and the existence of wormholes in the reservoir was strongly suggested by regional well-to-well water migration and production of reservoir sand at high initial rates and cumulative volumes. A solvent containing 33 volume % propane and 67 volume % methane was injected at two converted central producers until cumulative volumes of 2 million m3 and 4 million m3 were achieved. This paper discusses field observations during the injection, soak, and production periods. A number of circumstances contributed to a poor economic result, but the operational and technical information obtained should prove helpful to operators considering application of solvent injection processes. Introduction Cold Production in Western Canadian Regional Heavy Oil Sands PC pump-based cold production has expanded rapidly following initial development in the 1980s. This exploitation methodology provides a large percentage of the produced oil volume for most Western Canadian heavy oil producers. Some producers use only this method. Despite continued efforts to improve PC pump-based cold production technology, current methods generally leave 80 to 95% of the OOIP behind at economic limit. While this is a large oil-inplace target for follow-up EOR processes, the cold production process appears to have strongly altered reservoir conditions. Wormhole channels have been implied and described on the basis of observed high produced sand volumes and rapid migration of edge water and injected fluids and tracers(1–3). The reservoirs are generally pressure depleted. Solution gas, which appears to help power production through mechanisms described as either foamy oil flow(4–6) or more recently as extremely low gas mobility(7), often appears to "blow down" at the end of a well's life. Water influx, likely through wormhole networks, sometimes occurs at wells distant from the original oil/water contact. Thermal Production in Western Canadian Regional Heavy Oil Sands During the 1960s, operators attempted steam processes in selected heavy oil regional sands to recover a higher fraction of OOIP. It was soon determined that the typical H-40 casings with non-thermal cement would not withstand the resulting thermal stresses. Insulated tubing strings with or without packers were tried, but these strings were expensive, fragile, and often did not achieve theoretical performance in the field. Thermal completions in newer wells avoided wellbore failure due to the use of premium tubulars and collars, but other problems occurred. Often the steam had to be injected at pressures exceeding the formation parting (fracture) pressure to achieve acceptable heat transfer rates to the reservoir. This resulted in rapid steam channeling to neighboring wells, or to neighboring formations.