Gas Samples Research Articles

Specific molecular peak analysis by ion mobility spectrometry of volatile organic compounds in urine of COVID-19 patients: A novel diagnostic approach

IntroductionSARS-CoV-2 is usually diagnosed from naso-/oropharyngeal swabs which are uncomfortable and prone to false results. This study investigated a novel diagnostic approach to Covid-19 measuring volatile organic compounds (VOC) from patients’ urine. MethodsBetween June 2020 and February 2021, 84 patients with positive RT-PCR for SARS-CoV-2 were recruited as well as 54 symptomatic individuals with negative RT-PCR. Midstream urine samples were obtained for VOC analysis using ion mobility spectrometry (IMS) which detects individual molecular components of a gas sample based on their size, configuration, and charge after ionization. ResultsPeak analysis of the 84 Covid and 54 control samples showed good group separation. In total, 37 individual specific peaks were identified, 5 of which (P134, 198, 135, 75, 136) accounted for significant differences between groups, resulting in sensitivities of 89–94% and specificities of 82–94%. A decision tree was generated from the relevant peaks, leading to a combined sensitivity and specificity of 98% each. DiscussionVOC-based diagnosis can establish a reliable separation between urine samples of Covid-19 patients and negative controls. Molecular peaks which apparently are disease-specific were identified. IMS is an additional non-invasive and cheap device for the diagnosis of this ongoing endemic infection. Further studies are needed to validate sensitivity and specificity.

Geochemistry of Geothermal Fluids in the Three Rivers Lateral Collision Zone in Northwest Yunnan, China: Relevance for Tectonic Structure and Seismic Activity

The Three Rivers Lateral Collision Zone (TRLCZ), situated at the southeastern margin of the Tibetan Plateau, is a crucial frontier where materials from the plateau flow southeastward. This study extensively investigated the hydrochemical characteristics and origin of helium and carbon isotopes in 73 thermal springs within the TRLCZ. The analysis revealed dominant processes, including carbonate and silicate interactions, resulting in elevated concentrations of HCO3− and Na+. The impact of Ca/Mg-rich minerals, particularly dolomite, influenced the cation composition. Additionally, gypsum dissolution, notably in the Lancangjiang Fault and Weixi–Qiaohou Fault, was highlighted through Ca/SO4 ratios. The positive correlation between SO42− and Cl− indicated dilution by shallow cold water, explaining the lower SO42− content in the Jingshajiang–Zhongdian Fault and Nujiang Fault compared to the Weixi–Qiaohou Fault and Lancangjiang Fault. The circulation depth of thermal spring water varied, with the northern Weixi–Qiaohou Fault exhibiting the shallowest circulation depth (~3 km), while the Jingshajiang–Zhongdian Fault and southern segments of the Nujiang Fault displayed deeper depths—ranging from 4 to 7 km. A positive correlation between the circulation depth and fault activity was also observed. The Rc/Ra ratios of free gas samples, predominantly indicating crustal origin, varied from 0.01 Ra to 0.53 Ra. Elevated Rc/Ra ratios in the research area suggested potential minor additions of mantle helium through faults and fractures. Crustal limestone was identified as the primary source of CO2-rich samples, with δ13CCO2 values ranging from −1.6‰ to −7.2‰, while trace amounts of mantle CO2 were found. The spatial distribution of the H2 concentration, CO2 concentration, He concentration, and mantle He proportions in gases indicated that higher values of He concentration and mantle He% always occur near sampling points with deeper circulation depths. However, no similar correlation was observed for H2 and CO2. Most earthquakes of magnitude 5 or greater occurred near the regions with high values of mantle source He release, highlighting the critical role of mantle fluids in the occurrence of earthquakes in the region. In this study, a fluid circulation model was developed to describe the process of fluid (water and gas) circulation migration and earthquake generation in the TRLCZ.

Calibration of MAJIS (Moons And Jupiter Imaging Spectrometer). III. Spectral calibration.

The Moons And Jupiter Imaging Spectrometer (MAJIS) is the visible and near-infrared imaging spectrometer onboard the European Space Agency (ESA)'s Jupiter Icy Moons Explorer mission. Before its integration into the spacecraft, the instrument undergoes an extensive ground calibration to establish its baseline performances. This process prepares the imaging spectrometer for flight operations by characterizing the behavior of the instrument under various operative conditions and uncovering instrumental distortions that may depend on instrumental commands. Two steps of the on-ground calibration campaigns were held at the instrument level to produce the data. Additional in-flight measurements have recently been obtained after launch during the Near-Earth Commissioning Phase. In this article, we present the analyses of these datasets, focusing on the characterization of the spectral performances. First, we describe and analyze the spectral calibration datasets obtained using both monochromatic sources and polychromatic sources coupled with solid and gas samples. Then, we derive the spectral sampling and the spectral response function over the entire field of view. These spectral characteristics are quantified for various operational parameters of MAJIS, such as temperature and spectral binning. The derived on-ground performances are then compared with in-flight measurements obtained after launch and presented in the framework of the MAJIS performance requirements.

A Design Strategy for Removing the Debinding and Sintering Gas in Additive Manufactured Samples of a Bronze/Polylactic Acid Filament

To lower the cost of additive manufacturing of metallic components, the goal of this work is to investigate and optimize a multi‐step process by material extrusion (MEX) of a polylactide filament loaded with bronze to remove the gas produced during the debinding and sintering steps. First, by adjusting the infill (10%, 50%, and 100%), and then by designing and constructing internal passages to aid in the expulsion of gases that occur during the debinding, a calibration cube is created. Additionally, the impact of the cooling period during the debinding is examined. To assess how the technique changes shape, sizes, and internal structure, all the samples are ultimately weighed, scanned, and cut. In order to reduce deformation occurred during the debinding and sintering gases, a new design method has been developed. The method consists of the generation of internal channels which connect the voids of the infill and allow gases to flow out through a central channel. As seen, samples with ejection channels and an intermediate infill (i.e., 50%) both exhibit better attributes.

Transformer Monitoring with Electromagnetic Energy Transmission and Wireless Sensing.

To ensure stable and normal transformer operation, light gas protection of the transformer Buchholz relay is essential. However, false alarms related to light gas protection are common, and troubleshooting them often requires on-site gas sampling by personnel. During this time, the transformer's operating state may rapidly deteriorate, posing a safety threat to field staff. To tackle these challenges, this work presents the near-field, thin-sliced transformer monitoring system that uses Electromagnetic Energy Transmission and Wireless Sensing Device (ETWSD). The system leverages external wireless energy input to power gas monitoring sensors. Simultaneously, it employs Near-Field Communication to obtain real-time concentrations of light gases, along with the electrified state and temperature. In field testing conducted on transformer relays' gas collection chambers, the ETWSD effortlessly monitors parameters within warning ranges, encompassing methane gas concentrations around 1000 ppm, leakage voltage ranging from 0-100 V, and relay working temperatures up to 90 °C. Additionally, to facilitate real-time diagnosis for electrical workers, we have developed an Android-based APP software that displays current light gas concentrations, leakage voltage collection values, and temperature, while also enabling threshold judgment, alarms, and data storage. The developed ETWSD is expected to aid on-site personnel in promptly and accurately evaluating transformer light gas protection error alarm faults. It provides a method for simultaneous, contactless, and rapid monitoring of multiple indicators.

The Predictive Role of Lactate in the Emergency Department in Patients with Severe Dyspnea.

An accurate identification of patients at the need for prioritized diagnostics and care are crucial in the emergency department (ED). Blood gas (BG) analysis is a widely available laboratory test, which allows to measure vital parameters, including markers of ventilation and perfusion. The aim of our analysis was to assess whether blood gas parameters in patients with dyspnea at an increased risk of respiratory failure admitted to the ED can predict short-term outcomes. The study group eventually consisted of 108 patients, with available BG analysis. The clinical and laboratory parameters were retrospectively evaluated, and three groups were distinguished-arterial blood gas (ABG), venous blood gas (VBG), and mixed blood gas. The primary endpoint was short-term, all-cause mortality during the follow-up of median (quartile 1-quartile 3) 2 (1-4) months. The independent risk factors for mortality that could be obtained from blood gas sampling were evaluated. The short-term mortality was 35.2% (38/108). Patients who died were more frequently initially assigned to the red triage risk group, more burdened with comorbidities, and the median SpO2 on admission was significantly lower than in patients who survived the follow-up period. In the multivariable analysis, lactate was the strongest independent predictor of death, with 1 mmol/L increasing all-cause mortality by 58% in ABG (95% CI: 1.01-2.47), by 80% in VBG (95% CI: 1.13-2.88), and by 68% in the mixed blood gas analysis (95% CI: 1.22-2.31), what remained significant in VBG and mixed group after correction for base excess. In each group, pH, pO2, and pCO2 did not predict short-term mortality. In patients admitted to the ED due to dyspnea, at risk of respiratory failure, lactate levels in arterial, venous, and mixed blood samples are independent predictors of short-term mortality.

The Four-Sinker Densimeter: A New Instrument for the Combined Investigation of Accurate Densities and Sorption Phenomena of Pure Gases and Gas Mixtures

An apparatus for high-accuracy gas density and adsorption measurements over the range of temperature from (193 to 423) K and pressure from (0 to 15) MPa is described. This instrument is based on the two-sinker densimetry principle and incorporates a magnetic suspension balance. In addition to the two “density sinkers”, two “sorption sinkers” are weighed to investigate density and adsorption of a gas sample simultaneously. The design of the sinkers increases the resolution of density and adsorption investigations and enables the correction of sorption effects on density measurements. The complete apparatus, including the sinkers, the temperature and pressure measuring systems, and the measurement procedure, is described. For the density range investigated, the uncertainty (k = 2) is between (0.0034 to 0.019) kg·\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\cdot$$\\end{document}m−3, corresponding to (0.060 to 0.011)%. The uncertainty (k = 2) in adsorption load is (0.16 to 0.26) μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}g·\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\cdot$$\\end{document}cm−2. Density measurements at T = (283 and 293) K and pressures up to 10 MPa of high-purity argon and nitrogen validate the instrument for density. Adsorption measurements of high-purity carbon dioxide and propane on a gold surface validate the instrument for adsorption investigation at T = (283 and 293) K and up to the saturation pressure of the investigated gas. The apparatus was used to measure the binary mixture (0.75 CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{CO}_2$$\\end{document} + 0.25 C3H8\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{C}_3\ ext{H}_8}$$\\end{document}). In the future, the apparatus will also be used to accurately determine dew-point densities and pressures of pure gases and gas mixtures.

A Split-Lung Ex Vivo Perfusion Model for Time- and Cost-Effective Evaluation of Therapeutic Interventions to the Human Donor Lung.

With the ongoing shortage of donor lungs, ex vivo lung perfusion (EVLP) offers the opportunity for objective assessment and potential therapeutic repair of marginal organs. There is a need for robust research on EVLP interventions to increase the number of transplantable organs. The use of human lungs, which have been declined for transplant, for these studies is preferable to animal organs and is indeed essential if clinical translation is to be achieved. However, experimental human EVLP is time-consuming and expensive, limiting the rate at which promising interventions can be assessed. A split-lung EVLP model, which allows stable perfusion and ventilation of two single lungs from the same donor, offers advantages scientifically, financially and in time to yield results. Identical parallel circuits allow one to receive an intervention and the other to act as a control, removing inter-donor variation between study groups. Continuous hemodynamic and airway parameters are recorded and blood gas, perfusate, and tissue sampling are facilitated. Pulmonary edema is assessed directly using ultrasound, and indirectly using the lung tissue wet:dry ratio. Evans blue dye leaks into the tissue and can quantify vascular endothelial permeability. The split-lung ex vivo perfusion model offers a cost-effective, reliable platform for testing therapeutic interventions with relatively small sample sizes.

Low-resistance and high-tolerance monolithic spiro-bifluorene-based conjugated microporous polymer for co-capture of PM and CO2 in waste gas

The utilization of solid adsorbents for the co-capture of harmful particulate matter (PM) and carbon dioxide (CO2) in industrial exhaust streams represents a crucial component within the emerging field of waste gas terminal treatment technologies. Extensive research has focused on particulate or powdered adsorbents rather than monolithic materials, whereas monolithic adsorbents exhibit superior advantages in practical industrial applications. Herein, a monolithic spiro-bifluorene-based conjugated micro-porous polymer (DS-CMPs) with hierarchical porous and functionalized hollow nanotube structures was proposed. The favorable characteristics exhibited by DS-CMPs encompass a highly delocalized π-π conjugated skeleton, permanent porosity, unique thermal and chemical stability, precisely defined chemical composition, and excellent water vapor tolerance. These inherent qualities guarantee that DS-CMPs employed for the co-capture of PM and CO2 from exhaust gases exhibit exceptional capture efficiency, low permeation resistance, favorable isosteric heat of adsorption (Qst), and recyclability. The reasons behind the high capture efficiency and low permeation resistance of monolithic DS-CMPs were analyzed through mechanistic exploration and Electrostatic Surface Potential (ESP) calculations. Moreover, the stability inherent in the framework structure and physicochemical properties of DS-CMPs can surmount the notable decline in the capturing capability of porous materials utilized within damp and elevated temperature surroundings. Following exposure to elevated humidity (RH = 86 ± 1 %) and high-temperature (500 ℃) conditions, DS-CMPs exhibited a remarkable capture efficiency exceeding 99.00 % for PM2.5. The self-assembly of monolithic DS-CMPs into a smooth array of nanotube bundles effectively reduces the friction between airflow and material, enhances airflow dispersion, and achieves a minimum permeability resistance of only 8 Pa. At a pressure of 1 bar and temperature of 273 K, the CO2 adsorption capacity of DS-CMPs amounts to 2.72 mmol/g. The high absorption capacity for CO2 is primarily attributed to the presence of a significant microporous/mesoporous ratio and notable surface charge differences. In contrast to powdered adsorbents plagued by sample elution and gas pressure drop issues, the monolithic DS-CMPs showcases good mechanical properties, rendering them readily applicable within industrial bed circulation systems to achieve the co-capture of PM and CO2.

Opinion: Should high-resolution differential mobility analyzers be used in mainstream aerosol studies?

Abstract. Differential mobility analyzers (DMAs) are widely used instruments to measure the size distributions of submicron aerosols. High-resolution DMAs (HRDMAs) are defined here as plain DMAs maintaining a steady flow over an unusually broad range of sheath gas flow rates Q. HRDMAs, first developed by Georg Reischl's group, have existed for a long time. However, they have not been widely adopted, except in the size range below 10 nm, often in new particle formation studies. Here we question the commonly held view that HRDMAs are necessarily complex, bulky and expensive machines, mainly of interest in exotic applications outside mainstream aerosol research. Rather, many studies central to aerosol research could be carried out with HRDMAs with considerable advantage in size range, resolution, sensitivity and measurement speed. DMA manufacturers will hopefully take the challenge of developing commercial HRDMAs of complexity and cost comparable to those of today's commercial instruments, adapted for broad use by aerosol scientists, though with greatly improved flexibility and performance. Some of the technical challenges that still need to be overcome are discussed, such as the development of high-flow condensation counter detectors, and the control of high sample and sheath gas flow rates.

Geochemistry of Liquid Hydrocarbons and Natural Gases Combined with 1D Basin Modeling of the Oligocene Shale Source Rock System in the Offshore Nile Delta, Egypt.

The current study aims to integrate the geochemical characteristics of the Oligocene shale source rock system, oil, condensate, and natural gas samples in the Oligocene sandstone reservoirs from three exploration wells located in the offshore Nile Delta, East Mediterranean Sea, using organic geochemistry and a 1D basin modeling scheme. The Tineh shales exhibit total organic carbon values ranging between 0.90 and 1.89 wt %, along with hydrogen index values in the range of 54-240 mg hydrocarbon/g rock. The geochemical characterization suggests that the shale intervals of the Oligocene Tineh Formation contain type II-III and type III kerogens and, thereby, could be regarded as promising oil- and gas-prone source rocks with high contributions of gas generation potential. The study also reconstructs the 1D thermal and burial history models, showing that the Oligocene Tineh source rock system is in the main oil and wet gas generation phases from the late Miocene to the present time. The simulated basin models reveal the transformation (TR) of 10-50% kerogen to oil during the late Miocene-early Pliocene period and that the Oligocene Tineh source rock system has larger oil generation and expulsion competency, with a TR value of up to 65% during the early Pliocene-Pleistocene time period. The thermogenic gas was also formed during this time and continued to the present day. This study also investigated the presence of oil and condensate in the Oligocene sandstone reservoir samples and revealed that they were generated from mature source rock, ranging from moderately to highly mature stages. This source rock unit was deposited in fluvial to fluvial-deltaic environments under oxic mixed organic conditions and accumulated during the Tertiary time, as evidenced by the presence of the oleanane biomarker dating indicator. The molecular and isotope compositions of natural gases revealed that most of the natural gases in the Oligocene sandstone reservoir are mainly thermogenic methane gases that were generated from mainly mixed organic matter. The thermogenic methane gases were formed mainly from secondary cracking of oil and gas, with small contributions of primary kerogen cracking. The properties of natural gases together with oil and condensate in the Oligocene reservoir rocks suggest that most of the thermogenic methane gases and associated liquid hydrocarbons are derived primarily from the Oligocene shale source rock system and formed by primary kerogen cracking and secondary oil and oil/gas cracking in different thermal maturity stages. Therefore, the Oligocene Tineh Formation can be regarded as self-source generation and self-reservoir rock; hence, an intensive oil exploration and production program can be recommended whenever the Tineh source rock system is is well developed and deeply buried.

Hydrogen Bonding and Molecular Geometry in Isolated Hydrates of 2-Ethylthiazole Characterised by Microwave Spectroscopy.

Broadband microwave spectra of the isolated 2-ethylthiazole molecule, and complexes of 2-ethylthiazole⋅⋅⋅H2O and 2-ethylthiazole⋅⋅⋅(H2O)2 have been recorded by probing a gaseous sample containing low concentrations of 2-ethylthiazole and water within a carrier gas undergoing supersonic expansion. The identified conformer of the isolated 2-ethylthiazole molecule and the 2-ethylthiazole sub-unit within each of 2-ethylthiazole⋅⋅⋅H2O and 2-ethylthiazole⋅⋅⋅(H2O)2 have C1 symmetry. The angle that defines rotation of the ethyl group relative to the plane of the thiazole ring, ∠(S-C2-C6-C7), is -98.6(10)° within the isolated 2-ethylthiazole molecule. Analysis of molecular geometries and non-covalent interactions reveals each hydrate complex contains a non-linear primary, N⋅⋅⋅Hb-O, hydrogen bond between an O-H of H2O and the nitrogen atom while the O atom of the water molecule(s) interacts weakly with the ethyl group. The ∠(Hb⋅⋅⋅N-C2) parameter, which defines the position of the H2O molecule relative to the thiazole ring, is found to be significantly greater for 2-ethylthiazole⋅⋅⋅H2O than for thiazole⋅⋅⋅H2O. The distance between the O atoms is determined to be 2.894(21) Å within the dihydrate complex which is shorter than observed within the isolated water dimer. The primary hydrogen bond within 2-ethylthiazole⋅⋅⋅(H2O)2 is shorter and stronger than that in 2-ethylthiazole⋅⋅⋅H2O as a result of cooperative hydrogen bonding effects.

Sugarcane exudates as nitrification inhibitors; improvement of soybean nitrogen recovery and yield by reducing soil nitrification and N2O emission using 15N tracing techniques

BNI (biological nitrification inhibition) derived from root exudates is typically used in rotation cropping systems to increase the crop nitrogen efficiency (NUE). Recently, the root exudates secreted by three sugarcane varieties in Thailand have been found to inhibit the nitrification and accumulation. The objective of the study was to evaluate the effectiveness of the sugarcane root exudate on (i) soil nitrification rate and N dynamics (soil mineral N and nitrous oxide (N2O) emission) and (ii) growth, yield, and 15N recovery by soybean under greenhouse conditions. The experiment was laid out as a randomized complete block design (RCBD), with five treatments and four replications: (i) N fertilizer (Control); (ii) Control + Uthong 13 sugarcane root exudate (UT13); (iii) Control + Khon Kaen 3 sugarcane root exudate (KK3); (iv) Control + wild cane sugarcane root exudate (Spone) and (v) Control + dicyandiamide (DCD). 15N fertilizer was applied to a micro-plot for 15N recovery. Soybean was planted and fertilized at 75 kg ha−1 N as (NH4)2SO4. Soil samples were collected at 1, 3, 7, 14, 21 and 28 days after N fertilization (DANF) for pH, potential nitrification rate (PNR), NH4+, NO3− and MBN measurement at 0–15 and 15–30 cm soil depths. A gas sample was collected by the soil chamber technique for an N2O emissions study on the soil sampling date. The soybean growth was monitored at 30 and 60 DAP (days after planting) for height, leaf area, leaf area index (LAI), SCMR and dry weight (DW). At soybean harvest, seed yield, yield components and N uptake were recorded. Our study revealed that the sugarcane root exudates significantly decreased PNR up to 14 DANF and increased NH4+ content in soil and reduced commutative N2O–N fluxes after 14 DANF, compared to N treatment (p < 005). The root exudate treatments not only increased growth (total DW and LAI at 60 DAP), yield (number of pods and seeds per plant) and N uptake (17–19%) but also 15N recovery in the total plant. This confirms the capacity of BNIs from sugarcane root exudates. In conclusion, sugarcane root exudates can effectively mitigate N2O emissions and enhance soybean N uptake under greenhouse conditions.

Geochemical evidence for biodegradation in high-rank coals from Qinshui Basin, North China

Understanding the generation of secondary microbial methane (SMM) is important for the evaluation of natural gas resources and instructive for the stimulation of methane production. Coal seams are popular targets for extracting in situ preserved methane and studying microbe-stimulated methane yield. However, few studies have been done on overmature coals. Here we collected gas samples from coals varying from bituminous to meta-anthracite in the Qinshui Basin, North China, and analysed the molecular and stable isotopic compositions to systematically evaluate the influence of biodegradation in high-rank coals in geological settings. The stable isotope signatures (δ13C and δD) of methane are dominated by the thermal decomposition of organic matter in deep coals but inconsistent with the maturity rank of shallow burial coals. The decoupling of coal maturity with C1/C2+ ratios and δ13C-CH4 values, and positive δ13C-CO2 values (−9.2 to +24.4 ‰) suggest biodegradation of light wet gases (C2+ components) and CO2 reduction. Negative trends between δ13C-CO2 and CH4/CO2 in shallow burial coal seams reveal the mutual conversion of CH4 and CO2 and carbon isotope exchange, driven by microorganisms. The calculated isotopic temperatures (33–328 °C) based on the carbon isotope fractionation factors between CH4 and CO2 (1.024–1.069) demonstrate that carbon isotope exchange is prevalent in high-rank coals. It also reveals that the burial depth is an imperative factor in controlling microbial environments and thus the biodegradation process. This study implicates the potential of high-rank coals as the target for microbial-enhanced methane recovery and also implies that microorganisms are widely involved in reservoir carbon cycling.

Water vapor condensation in optical instruments on Mars

Modern high-sensitivity spectrometers rely on photons reflecting thousands of times between extremely reflective mirrors to generate absorption pathlengths that are kilometers long. The absorption spectrum of trace gas species is enhanced when cooling the gas sample, however, should any atmospheric volatiles condense within the gas cell, the highly-reflective mirrors may become marred, drastically cutting down the effective optical path length. In the Martian atmosphere, the first volatile to condense is typically water vapor, thus understanding the variability of the water frost point is essential for determining the performance limit of any optical instrument. We will examine these performance limits and map the maximum temperatures at which water vapor will condense on the Martian surface with respect to a model instrument being prepared for flight. The variability of the frost point with time and solar longitude (Ls) therefore reveals areas of the Martian surface at which the precision of a high-sensitivity spectrometer is optimized. We find that the optimal performance is achieved during northern fall and winter (Ls = 180°–360°) at polar and mid-latitude locations in the northern hemisphere, and during northern spring (Ls = 0°–90°) at equatorial and mid-latitude locations in the southern hemisphere when the frost point reaches the lowest maximums.

A Portable Microplasma Optical Emission Spectrometric Device with Online Digestion Function for Field and Sensitive Determination of Lead in Biological Samples.

Accurate detection and screening of Pb in biological samples is helpful to assess the risk associated with lead pollution to human health. However, conventional atomic spectroscopic instruments are bulky and cumbersome, requiring additional sample pretreatment equipment, and difficult to perform field analysis with. Herein, a portable point discharge (PD) microplasma-optical emission spectrometric (OES) device with online digestion function is designed for field and sensitive determination of lead in biological samples. With rice as a model, online digestion of a batch of six 50 mg samples can be achieved in the HNO3 and H2O2 system within 25 min by a temperature control and timing module. Compared to the conventional microwave digestion, the digestion efficiency of this device reaches 97%. Pb in digestion solution is converted into volatile species by hydride generation (HG) and directly introduced into PD-OES for excitation and detection by a self-designed rotatable and telescopic cutoff gas sampling column. Six samples can be successively detected in 2 min, and argon consumption of the whole process is only <800 mL. Under the optimized conditions, the detection limit of Pb is 0.018 mg kg-1 (0.9 μg L-1) and precision is 3.6%. The accuracy and practicability of the present device are verified by measuring several certified reference materials and real biological samples. By virtue of small size (23.5 × 17 × 8.5 cm3), lightweight (2.5 kg), and low energy consumption (24.3 W), the present device provides a convenient tool for field analysis of toxic elements in biological samples.

Preparation of paper scintillators and their effective use in radiation testing for [formula omitted]- and [formula omitted]- particles in radioactive liquid, solid, and gas contaminants

A paper scintillator, which is composed of an organic scintillator encapsulated in silica nanoparticles adsorbed on three types of micrometer-size silica fine powder (scintillator–silica FP), was prepared by a paper making method. The scintillator–silica FP was found to be distributed throughout the paper scintillator, as shown in its emission images. Surface photoluminescence spectra depended on the amount of scintillator–silica FP and were assigned to the radioluminescence excited upon irradiation with β-particles of 45Ca. The onset channels of the pulse height spectra of 3H, 63Ni, 14C, 45Ca, 204Tl, and 32P indicated their dependence on linear energy from 18.6 to 1711 keV using the H mode in LSC-7400 for the paper scintillator to detect their maximum β-particles energies. The paper scintillator could also detect α-particles from 211At, and its pulse height spectrum was wider than that of a liquid scintillator (LS). Radon gas in air was collected using a gas sampler with the paper scintillator, and radiation from daughter nuclides was detected for 10 days. The adsorption/absorption of tritiated water onto/into the paper scintillator after dipping, dropping, and immersing the paper scintillator into tritiated water led to the detection of β-particles under different conditions of tritiated water for determining whether the radioactivity in the solution, is high or low. The paper scintillator smeared with tritiated contaminants detected tritium without requiring an LS, which is used in a smear paper.

Potential water repellency influenced CO2 and CH4 release from moist soils: Experiments on water-repellent Japanese Andosols

Soil, the largest terrestrial carbon (C) pool on earth is an important source of greenhouse gasses. Soil water repellency (SWR), a moisture-dependent characteristic, is an important factor that affects microbial decomposition and gas release since it causes non-uniform moisture distributions in the soil matrix. It is not clear whether potential water repellency (PWR), measured on dried soils, can influence carbon dioxide (CO2) and methane (CH4) emissions under unsaturated moist conditions. This study aims to fill this knowledge gap using two water-repellent soils, and one non-repellent soil (NRS; control), under two temperature levels. Samples were collected from water-repellent Chamaecyparis obtusa (CYP) and Cryptomeria japonica (CED) forests, and the NRS was collected from Field Science Center in Ibaraki University, Ibaraki, Japan. Capillary-moistened samples were placed in closed chambers and separately exposed to 25 °C and 35 °C. Gas sampling was conducted in 1, 7, 14, 21, and 28 d. The PWR was measured with separate samples under the same conditions. CED soils showed significantly higher PWR compared with the NRS and CYP. The gas emission per g soil organic C (EGC; mg g−1 SOC h−1) was significantly low in CED soils compared with NRS and CYP, while NRS showed the highest emission. EGC of CO2 and CH4 showed significant strong negative correlations with PWR. The emission of CO2 and CH4 significantly increased with increasing temperature, and the Q10 was significantly high for CH4. Results indicated that the sensitivity to elevated PWR was higher for emission of CO2, whereas the sensitivity to the elevated temperature was higher for the emission of CH4. It was clear that PWR can influence moisture distribution in soil matrix in unsaturated moist soils and the processes that limit gaseous C emission. Further experiments are required on possible processes that enable PWR to influence gaseous C emission from moist soils.

High-flow nasal cannula oxygen versus noninvasive ventilation for the management of acute cardiogenic pulmonary edema: a randomized controlled pilot study.

Whether high-flow nasal oxygen can improve clinical signs of acute respiratory failure in acute heart failure (AHF) is uncertain. To compare the effect of high-flow oxygen with noninvasive ventilation (NIV) on respiratory rate in patients admitted to an emergency department (ED) for AHF-related acute respiratory failure. Multicenter, randomized pilot study in three French EDs. Adult patients with acute respiratory failure due to suspected AHF were included. Key exclusion criteria were urgent need for intubation, Glasgow Coma Scale <13 points or hemodynamic instability. Patients were randomly assigned to receive high-flow oxygen (minimum 50 l/min) or noninvasive bilevel positive pressure ventilation. The primary outcome was change in respiratory rate within the first hour of treatment and was analyzed with a linear mixed model. Secondary outcomes included changes in pulse oximetry, heart rate, blood pressure, blood gas samples, comfort, treatment failure and mortality. Among the 145 eligible patients in the three participating centers, 60 patients were included in the analysis [median age 86 (interquartile range (IQR), 90; 92) years]. There was a median respiratory rate of 30.5 (IQR, 28; 33) and 29.5 (IQR, 27; 35) breaths/min in the high-flow oxygen and NIV groups respectively, with a median change of -10 (IQR, -12; -8) with high-flow nasal oxygen and -7 (IQR, -11; -5) breaths/min with NIV [estimated difference -2.6 breaths/min (95% confidence interval (CI), -0.5-5.7), P = 0.052] at 60 min. There was a median SpO 2 of 95 (IQR, 92; 97) and 96 (IQR, 93; 97) in the high-flow oxygen and NIV groups respectively, with a median change at 60 min of 2 (IQR, 0; 5) with high-flow nasal oxygen and 2 (IQR, -1; 5) % with NIV [estimated difference 0.8% (95% CI, -1.1-2.8), P = 0.60]. PaO 2 , PaCO 2 and pH did not differ at 1 h between groups, nor did treatment failure, intubation and mortality rates. In this pilot study, we did not observe a statistically significant difference in changes in respiratory rate among patients with acute respiratory failure due to AHF and managed with high-flow oxygen or NIV. However, the point estimate and its large confidence interval may suggest a benefit of high-flow oxygen. NCT04971213 ( https://clinicaltrials.gov ).

Efficient detection of Streptococcus pyogenes based on recombinase polymerase amplification and lateral flow strip.

This article aims to establish a rapid visual method for the detection of Streptococcus pyogenes (GAS) based on recombinase polymerase amplification (RPA) and lateral flow strip (LFS). Utilizing speB of GAS as a template, RPA primers were designed, and basic RPA reactions were performed. To reduce the formation of primer dimers, base mismatch was introduced into primers. The probe was designed according to the forward primer, and the RPA-LFS system was established. According to the color results of the reaction system, the optimum reaction temperature and time were determined. Thirteen common clinical standard strains and 14 clinical samples of GAS were used to detect the selectivity of this method. The detection limit of this method was detected by using tenfold gradient dilution of GAS genome as template. One hundred fifty-six clinical samples were collected and compared with qPCR method and culture method. Kappa index and clinical application evaluation of the RPA-LFS were carried out. The enhanced RPA-LFS method demonstrates the ability to complete the amplification process within 6min at 33°C. This method exhibits a high analytic sensitivity, with the lowest detection limit of 0.908ng, and does not exhibit cross-reaction with other pathogenic bacteria. The utilization of RPA and LFS allows for efficient and rapid testing of GAS, thereby serving as a valuable method for point-of-care testing.