Gas Values Research Articles

Strain effects on electronic structure and optics of al-Doped monolayer GaS

This comprehensive study utilises rigorous first-principles calculations to meticulously investigate the influence of uniaxial tensile strain on the electronic configuration and optical behaviours of aluminium-doped gallium sulphide. The study highlights the modulation of electrical properties and optical responses in Al-doped monolayer GaS through the application of tensile strain. Notably, with increasing tensile strain, the bandgap value of the pristine GaS exhibits a pronounced decline, whereas the Al-doped variant maintains a more stable bandgap. A deeper exploration of the state density reveals the emergence of novel electronic states and energy levels in both the pristine and Al-doped monolayer GaS systems as tensile strain is applied. Crucially, the stabilising effect of the doped Al atoms minimises variations in the state density profiles of the Al-doped monolayer GaS systems, in contrast to their pristine counterparts. This result implies that fine control of the electrical structure and optical characteristics of Al-doped monolayer GaS may be achieved by the application of uniaxial tensile strain. The optoelectronic characteristics of GaS and its doped systems are explained in detail by these discoveries, which also offer a crucial theoretical foundation and direction for the use of these materials in optoelectronic devices.

Role of Magma Oceans in Controlling Carbon and Oxygen of Sub-Neptune Atmospheres

Most exoplanets with a few Earth radii are more inflated than bare-rock planets with the same mass, indicating a substantial volatile amount. Neither the origin of the volatiles nor the planet’s bulk composition can be constrained from the mass–radius relation alone, and the spectral characterization of their atmospheres is needed to solve this degeneracy. Previous studies showed that chemical interaction between accreted volatile and possible molten rocky surface (i.e., magma ocean) can greatly affect the atmospheric composition. However, a variety in the atmospheric compositions of such planets with different properties remains elusive. In this work, we examine the dependence of atmospheric H, O, and C on planetary parameters (atmospheric thickness, planetary mass, equilibrium temperature, and magma properties such as redox state) assuming nebula gas accretion on an Earth-like core, using an atmosphere-magma chemical equilibrium model. Consistent with previous work, we show that atmospheric H2O fraction on a fully molten rocky interior with an Earth-like redox state is on the order of 10−2–10−1 regardless of other planetary parameters. Despite the solubility difference between H- and C-bearing species, C/H increases only a few times above the nebula value except for atmospheric pressure ≲1000 bar and H2O fraction ≳10%. This results in a negative O/H–C/O trend and depleted C/O below one-tenth of the nebula gas value under an oxidized atmosphere, which could provide a piece of evidence of rocky interior and endogenic water. We also highlight the importance of constraints on the high-pressure material properties for interpreting the magma–atmospheric interaction of inflated planets.

Precision and uncertainty in natural gas calorific value estimation: advanced combinatorial predictive models for complex pipeline systems

Abstract In recent years, natural gas pipelines have been characterized by multiple intake points, the mixing of different gas sources, and significant variations in gas quality. The existing volumetric measurement system is no longer suitable for the development and operation of natural gas pipelines in China. To ensure accurate and equitable implementation of natural gas measurement, there is a gradual shift towards energy measurement. However, due to numerous measurement interfaces, installing chromatographs at all measurement stations would lead to substantial investment costs. Therefore, predicting the calorific value of natural gas is a key technology for energy measurement. In view of the issues existing in the current methods of obtaining natural gas calorific value, different prediction models of natural gas calorific value are constructed. According to the influencing factors of natural gas calorific value, the uncertainty evaluation is carried out, and the accuracy of different calorific value prediction models is analyzed by case data. The maximum error of regression equation (RE), response surface analysis (RSA), BP neural network and genetic algorithm (GA) prediction model is 2.29%, 0.43%, 0.59% and 0.45% respectively. However, the combined calorific value (CCV)prediction model is 0.41%. The results indicate that the predicted value calculated by the CCV prediction model is closer to the actual value and has higher prediction performance, which provides a new method for the calorific value prediction and measurement management of natural gas.

Differences in the Genesis and Sources of Hydrocarbon Gas Fluid from the Eastern and Western Kuqa Depression

The Kuqa Depression is rich in oil and gas resources and serves as a key production area in the Tarim Basin. However, controversy persists over the genesis of oil and gas in the various structural zones of the Kuqa Depression. This study employs natural gas composition analysis, gas carbon isotope analysis and gold pipe thermal simulation experiments, to comprehensively analyze the differences in the genesis and sources of hydrocarbon gas fluid from the eastern and western Kuqa Depression. The results show that the Kuqa Depression is dominated by alkane gas, with an average gas drying coefficient of 95.6, with nitrogen and carbon dioxide as the primary non-hydrocarbon gases. The average of δ13C1, δ13C2 and δ13C3 values in natural gas are −27.70‰, −20.43‰ and −21.75‰, respectively. Based on comprehensive natural gas geochemical maps, the CO2 in the natural gas from the Tudong and Dabei areas, as well as the KT-1 well of the Kuqa Depression, is thought to be of organic origin. Additionally, natural gas formation in the Tudong area is relatively simple, consisting entirely of thermally generated coal gas derived from the initial cracking of kerogen. The natural gas in the KT-1 well and the Dabei area are mixed gasses, formed by the initial cracking of kerogen from highly evolved lacustrine and coal-bearing source rocks, exhibiting characteristics resembling those of crude oil cracking gas. The methane (CH4) content of natural gas in the Dabei area is high and the carbon isotopes are unusually heavy. Considering the regional geological background, potential source rock characteristics and geochemical features may be related to the large-scale invasion of dry gas contributed by CH4 from highly evolved, underlying coal-bearing source rocks. Consequently, the CH4 content in the mixed gas is generally high (Ln (C1/C2) can reach up to 5.38), while the relative content of heavy components is low, though remains relatively unchanged. Thus, the map of the relative content of heavy components still reflects the characteristics of the original gas genesis (initial cracking of kerogen). Mixed-source gas was analyzed using thermal simulation experiments and natural gas composition ratio diagrams. The contributions of natural gas from deep, highly evolved coal-bearing source rocks in the KT-1 well and the Dabei area accounted for more than 90% and approximately 60%, respectively. This analysis provides theoretical guidance for natural gas exploration in the research area.

Impact of low-pressure pneumoperitoneum and deep neuromuscular blockade on surgeon satisfaction and patient outcomes in laparoscopic cholecystectomy patients: A prospective randomised controlled study.

The impact of laparoscopic surgery on homeostatic systems necessitates careful consideration of intra-abdominal pressure (IAP) management. This study investigated the effects of low-pressure pneumoperitoneum with deep neuromuscular blockade (NMB) on surgeon satisfaction, haemodynamics and post-operative outcomes in laparoscopic cholecystectomy patients. The study design involves prospective randomised control. Ninety patients were assigned to low (7-10 mmHg, n = 45) or normal (12-16 mmHg, n = 45) IAP groups. Deep NMB, guided by train-of-four monitoring, was administered. This study evaluated surgical rating scale scores, haemodynamics and post-operative outcomes through a literature review. A computer programme (IBM, SPSS) was used for statistical analysis. Chi-square and Mann-Whitney U tests were used to analyse patients' IAP levels, additional NMB requirements, surgical rating scale scores and numerical rating scales. Patient demographics and other intraoperative and post-operative variables were analysed with Student's t-test and the Mann-Whitney U test. Values of P < 0.05 were considered to indicate statistical significance. No significant demographic differences were observed. The low-pressure group exhibited lower post-operative pain (P < 0.01) and reduced analgesia requirements (P = 0.00). On analysis of the surgeon rating scale, no disparities were evident between the groups. NMB usage correlated with height and weight (P < 0.01). Heart rate showed no intergroup differences. The MAP measured after 15 min was lower in Group L, and the difference was significant (P = 0.023). The SAP measured after 30 min was lower in Group L, and the difference was significant (P = 0.017). Blood gas values and surgical field visibility were unaffected by the IAP. The positive correlations between NMB, height and weight aligned with previous research. This study highlights successful laparoscopic cholecystectomy under low IAP, deep NMB and favourable post-operative outcomes. Despite these limitations, the findings contribute to optimising laparoscopic surgical approaches.

Application of acetylene in multi-cylinder low heat rejection diesel engine fueled with ternary blend

The depletion of fossil fuels and environmental degradation have driven researchers worldwide to seek suitable alternative fuels for diesel engines. Internal combustion engines typically emit carbon monoxide (CO), hydrocarbon (HC), and smoke, contributing to environmental pollution. To address this issue, petroleum fuels can be substituted with alternative options like acetylene gas, hydrogen, CNG, or LPG. One effective strategy is to incorporate renewable fuels into diesel engines by partially or fully replacing diesel in a dual fuel mode (DFM). This research focuses on alternative renewable fuels for diesel engines like biodiesel and alcohol and its blends. The current research investigates the engine characteristics of diesel engines fueled with ternary blend (TB) fuel and different flow rates of acetylene in DFM. TB fuel was prepared using 70 % diesel, 20 % waste cooking oil biodiesel (WCOB), and 10 % methanol by volume. The induction of acetylene at different flow rates, such as 2, 4, and 6 lpm. Waste cooking oil is used to prepare biodiesel by transesterification. Partially stabilized zirconia (PSZ) is used to coat the cylinder head, piston crown, inlet, and exhaust valves with a thickness of 0.5 mm. The HC, CO, and smoke emissions are decreased by about 35.7 %, 29.8 %, and 21.6 %, respectively, for TB fuel with acetylene at 6 lpm at full load condition. The high calorific value of acetylene gas raised the in-cylinder temperature, significantly accelerating the combustion process. The heat release rate (HRR) and cylinder pressure are increased by 9.8 % and 6.8 %, respectively, at TB fuel with 6 lpm of acetylene induction. Acetylene induces rapid fuel combustion, resulting in increased energy transfer. The brake thermal efficiency (BTE) is improved by about 10.3 % for TB fuel with acetylene at 6 lpm and exhaust gas temperature (EGT) increased to 461oC at full load condition.

Investigations on performance of gasifier engine integration using three different biomasses as feedstocks

The integration of a downdraft gasifier with modified internal combustion engines presents a feasible solution for heat and power production, such as off-grid areas. This study conducted an experimental analysis to evaluate combustion in a modified engine. The morphological characteristics of the agricultural residue used in the gasifier were analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM), along with an examination of the slagging inorganic constituents. The engine used in the experiments was a modified single-cylinder design paired with a downdraft gasifier. Three types of biomass feedstocks—eucalyptus, corncob, and pearl millet in pellet form —were tested. The performance of the downdraft gasifier was stabilized, and the engine was run independently on each type of producer gas at a constant speed under different loads to determine the optimum load. Cylinder pressure measurements were taken to estimate the heat release rate.The study found that power generation was lower than typical woody biomasses due to the lower calorific value of the producer gas from the tested feedstocks. Additionally, lower cylinder pressures and heat release rates were recorded, along with longer combustion durations. The varying proportions of producer gas affected combustion stability. Among the studied ashes, pearl millet corncob (PMC) exhibited the highest slagging tendency, followed by corncob (CC). Morphological analysis indicated that the eucalyptus residue's increased porosity was caused by the volatiles changing, forming pores and tube-like structures. An aliphatic C–H peak (3000–2500 cm⁻1) is absent from the residue, indicating that the aliphatic structure was disturbed during thermochemical conversion. During the gasification process, the residue's crystallinity reduced as it split down.

Cosmic-Ray Feedback on Bistable Interstellar Medium Turbulence

While cosmic rays (E ≳ 1 GeV) are well coupled to a galaxy’s interstellar medium (ISM) at scales of L > 100 pc, adjusting stratification and driving outflows, their impact on small scales is less clear. Based on calculations of the cosmic-ray diffusion coefficient from observations of the grammage in the Milky Way, cosmic rays have little time to dynamically impact the ISM on those small scales. Using numerical simulations, we explore how more complex cosmic-ray transport could allow cosmic rays to couple to the ISM on small scales. We create a two-zone model of cosmic-ray transport, with the cosmic-ray diffusion coefficient set at the estimated Milky Way value in cold gas but smaller in warm gas. We compare this model to simulations with a constant diffusion coefficient. Quicker diffusion through cold gas allows more cold gas to form compared to a simulation with a constant, small diffusion coefficient. However, slower diffusion in warm gas allows cosmic rays to take energy from the turbulent cascade anisotropically. This cosmic-ray energization comes at the expense of turbulent energy which would otherwise be lost during radiative cooling. Finally, we show our two-zone model is capable of matching observational estimates of the grammage for some transport paths through the simulation.

Deciphering origins of hydrocarbon deposits by means of intramolecular carbon isotopes of propane adsorbed on sediments

Hydrocarbons are one of the important fluids within the Earth’s crust, and different biotic and abitoic processes can generate hydrocarbon during geological periods. Tracing the sources and sinks of hydrocarbons can help us better understand the carbon cycle of the earth. In this study, an improved approach of adsorbed hydrocarbons extraction from sediments was established. The improved thermal desorption approach, compound-specific isotope analysis and position-specific isotope analysis were integrated to investigate the molecular and intramolecular isotope fractionation between trace hydrocarbon gases within sediments and geological hydrocarbon deposits. The isotopic compositions of the terminal position carbon of propane (δ13Cterminal) serves as a correlation indicator between trace hydrocarbon gases within sediments and geological hydrocarbon deposits. The tight sandstone gas from the Turpan-Hami Basin is a first case study for the application of this novel method to trace hydrocarbon origins. The results showed that the hydrocarbons in the tight sandstone gases in the study area most likely originated from humic organic matter (type III kerogen) at an early mature stage. δ13Cterminal values of the thermally desorbed propane gases from different source rocks were distinguishable and the values of the tight sandstone gases significantly overlap with those of the Lower Jurassic Sangonghe source rocks, suggesting their genetic relationship. Overall, the results provided novel position-specific carbon isotopic constraints on origins of hydrocarbons.

Enrichment conditions and resource potential of coal-rock gas in Ordos Basin, NW China

To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin, this paper presents a systematic research on the sedimentary environment, distribution, physical properties, reservoir characteristics, gas-bearing characteristics and gas accumulation play of deep coals. The results show that thick coals are widely distributed in the Carboniferous–Permian of the Ordos Basin. The main coal seams Carboniferous 5# and Permian 8# in the Carboniferous–Permian have strong hydrocarbon generation capacity and high thermal evolution degree, which provide abundant materials for the formation of coal-rock gas. Deep coal reservoirs have good physical properties, especially porosity and permeability. Coal seams Carboniferous 5# and Permian 8# exhibit the average porosity of 4.1% and 6.4%, and the average permeability of 8.7×10−3 μm2 and 15.7×10−3 μm2, respectively. Cleats and fissures are developed in the coals, and together with the micropores, constitute the main storage space. With the increase of evolution degree, the micropore volume tends to increase. The development degree of cleats and fissures has a great impact on permeability. The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction. The bright coal seam, which is in the middle and upper section, less affected by ash filling compared with the lower section, and contains well-developed pores and fissures, is a high-quality reservoir interval. The deep coals present good gas-bearing characteristics in Ordos Basin, with the gas content of 7.5–20.0 m3/t, and the proportion of free gas (greater than 10%, mostly 11.0%–55.1%) in coal-rock gas significantly higher than that in shallow coals. The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures. The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity, and the mudstone/limestone (roof)-coal-mudstone (floor) combination generally indicates high coal-rock gas values. The coal-rock gas resources in the Ordos Basin were preliminarily estimated by the volume method to be 22.38×1012 m3, and the main coal-rock gas prospects in the Ordos Basin were defined. In the central-east of the Ordos Basin, Wushenqi, Hengshan–Suide, Yan'an, Zichang, and Yichuan are coal-rock gas prospects for the coal seam #8 of the Benxi Formation, and Linxian West, Mizhi, Yichuan–Huangling, Yulin, and Wushenqi–Hengshan are coal-rock gas prospects for the coal seam #5 of the Shanxi Formation, which are expected to become new areas for increased gas reserves and production.

Technical Note: Lifetime of evaporating droplets in a closed volume

The numerical modeling of heat and mass transfer of droplets within a closed volume containing gas heated in relation to the droplets was conducted. The droplet lifetime at variation of initial values of gas and droplet temperatures and droplet mass fraction has been determined. It was found that droplet lifetime exhibits a weak dependence on the initial droplet temperature and a pronounced dependence on the initial gas temperature. Moreover, it was demonstrated that the droplet lifetime in a closed volume is longer than in infinite space. This is due to the fact that the cooling of the surrounding gas by droplets results in a decrease in the evaporation rate of the droplets. A parameter is proposed which allows for the consideration of the effect of evaporating droplets on the thermal regime of the gas-drop mixture, and which enables the generalization of the results of numerical simulation to obtain an expression for the droplet lifetime in a closed volume. The error in the use of the obtained expression is estimated. It was determined that the margin of error for the calculation results is less than ten percent.

Technical Analysis of the Possibility of Burning Hydrogen in Furnaces of the Metallurgical Sector

This article analyses the possibility of using hydrogen as fuel in furnaces used in the metallurgical industry. The research was conducted for a selected continuous furnace. For this purpose, based on actual measurements, a heat balance of the furnace was prepared to determine its energy indicators. These values were used to verify the developed numerical model in IPSEpro 7.0 software. Numerical calculations were performed for three variants: pure natural gas; 30% hydrogen, 70% natural gas; and 100% hydrogen. The determined values of gas and combustion air streams allowed for achieving the assumed charge temperature in the heating technology. Calculations of the impact of the excess combustion air ratio on process parameters were also carried out. It was found that no changes are required in the exhaust gas removal system, but verification of the fan supplying air to cool the exhaust gases before the recuperator is necessary. The amount of hydrogen required to fuel the continuous furnace also increases significantly (nearly threefold), which may also affect operating costs. At the same time, the emission of carbon dioxide into the atmosphere is completely reduced, which may be an important criterion when considering modernization options for heating furnaces in the metallurgical industry.

Comparative study of grass pyrolysis over regenerated catalysts: Tyre ash, zeolite, and nickel-supported ash and zeolite

This paper presents investigations on catalytic and non-catalytic grass pyrolysis conducted at 500 °C using two reactor scales: a micro-scale reactor and a laboratory fixed-bed reactor. Four catalysts were employed in the catalytic pyrolysis process: car tyre ash, commercial zeolite mordenite-sodium, nickel supported on ash, and nickel supported on zeolite. The use of catalysts reduced the production of oxygenates and promoted the formation of gaseous compounds, with the most pronounced effect observed for nickel supported on zeolite. Catalytic pyrolysis produced chars with yields that were higher than those of the non-catalytic process. The coking behaviour of the spent catalysts was evaluated by analysing carbon content, with the highest content (3 wt% C) obtained for ash after the first cycle. In the second cycle, the deposited carbon content decreased for all catalysts. Furthermore, the employment of catalysts was shown to promote the production of hydrogen, methane, and other hydrocarbons in pyrolysis gas. The higher heating value of the pyrolysis gas was the highest at 21.1 MJ/m³ when the ash catalyst was first used for pyrolysis. Reusing the pyrolysis catalysts slightly reduced the heating value of the gas to 20.3 MJ/m³ over ash and 20.6 MJ/m³ over zeolite.

Potential application of generative artificial intelligence and machine learning algorithm in oil and gas sector: Benefits and future prospects

With the rapid advancement of technology and societies, the global energy sector now acknowledges that by integrating contemporary digital technologies into their operations and capabilities, can improve their competitive advantage and innovation performance and processes. Moreover, energy operators are also facing a significant undertaking: how to best use and secure large amounts of data that promote sustainable productivity performance and minimise potential threats in the oil and gas value chain and project operations. In view of the foregoing, various facets like Generative Artificial Intelligence (GAI) and Machine Learning Algorithms (MLA) are increasingly gaining popularity within oil and gas sector operations. Thus, we explored how GAI and ML algorithms can enhance oil and gas value chain productivity performance. The Principal Component Analysis (PCA) was employed to identify significant GAI and MLA variables influencing performance in the oil and gas value chain, while Structural Equation Modelling (SEM) was used to test regression equations related to their application. The study found that risk portfolios and profiles can be appraised throughout the value chain by effectively utilising GAI and ML algorithms in upstream, midstream and downstream undertakings. While these findings are noteworthy and have significant implications for current practice, the paper advocates that an array of digital technologies beyond GAI and ML can still be examined during future studies to demonstrate a holistic perspective on how digital transformation can be achieved across the energy sector value and project operations.

A pilot study on a 30 t/h biomass gasification-combustion plant

As a renewable energy with zero carbon emission, the utilization of biomass has attracted widely studied. One of the most effective methods is to gasify the biomass into high-quality gas fuel. In the recent years, the majority of research on biomass gasification is conducted in the laboratory. However, it lacks the research in engineering application scale. In this work, a biomass gasification-combustion plant was designed and built to provide the industrial steam with a rate of 30 t/h for a food industrial park. The agricultural and forestry waste biomass was gasified in a gasifier, and then the product gas combusted in a boiler to supply the steam. The characteristics of the product gas from the gasifier were studied. The corrosion and pollutants in the combustion process were investigated. In the gasification process, the main components of the product gas are CO, H2 and CH4. CO and H2 account for 29.55 vol%-30.56 vol% and 11.65 vol%-15.35 vol%, respectively. The calorific value of the product gas is 5.88–6.29 MJ/m3. The tar concentration is 110.58–155.07 g/Nm3. At the outlet of the boiler, the concentration of the filterable particulate matter is 300.25 mg/Nm3, and the particle size is concentrated at 1.00–2.50 μm. The concentration of the condensable particulate matter (CPM) is 157.14 mg/Nm3, and the proportion of water-soluble ions in CPM is 86.36 wt%. The concentration of Cl−, SO42-, NH4+ and Na+ in CPM is relatively high, with the values of 28.83 mg/Nm3, 10.29 mg/Nm3, 7.46 mg/Nm3, and 5.06 mg/Nm3, respectively. During the half-year running, the ash deposition and corrosion were detected in the boiler heating surface and the economizer. The ash deposit in the boiler is mainly composed of the sulfate and silicate, such as CaSO4, Zn2SO4, Na2SO4 and K3Na(SO4)2. The ash deposit in the economizer is primarily composed of the sulfate and a small amount of alkali metal chloride. The flue gas reaches the emission requirement after passing through the pollution control devices and can be discharged into the atmosphere.

Enhancing CO2/CH4 separation performance in PIM-1 based MXene nanosheets mixed matrix membranes

This study presents an approach by integrating MXene nanosheets (Ti2C3Tx) into polymer of intrinsic microporosity (PIM-1) matrix to develop mixed matrix membranes (MMMs) for biogas upgrading. Different concentrations (1–5 wt%) of MXene were incorporated into PIM-1, and the resulting materials were characterized to 1H NMR, FTIR, XRD, TGA, nitrogen adsorption, SEM and EDS to assess their physicochemical properties. The research focused on evaluating the gas separation performance, particularly CO2/CH4 separation, as well as the aging behavior of the MMMs. The incorporating of MXene nanosheets significantly enhanced the CO2 permeability and selectivity of PIM-1 by enhancing gas solubility and diffusivity. The most promising results were observed at 5 wt% filler loading, achieving a 13.5 CO2/CH4 separation selectivity at 7652 Barrer of CO2 permeability. In all membranes with aging time (60 days), there was a decrease in CO2 permeability and a slight increase in CO2/CH4 selectivity, observing that the introduction of MXene slightly mitigates the physical aging process in the PIM-1 polymer. Additionally, the permeability tests revealed higher CO2 permeability and (CO2/CH4) selectivity values for mixed gases compared to single gases. Overall, the study highlights the potential of MXene/PIM-1 MMMs as effective materials for CO2/CH4 separation, outperforming pristine PIM-1.

H i Kinematics and the E(B − V)/N(H i) Ratio

The λ21 cm H i emission that is used to trace the gas-to-dust ratio at high Galactic latitudes has contributions from material beyond the Milky Way disk, with uncertain and likely subsolar metallicity and dust content. These contributions can be isolated kinematically and their presence is clear for sightlines with small mean reddening 〈E(B − V)〉 ≲ 0.03 mag, which have mean ratios 〈N(H i)〉/〈E(B − V)〉 that are 20%–50% above the high-latitude Galactic average 〈N(H i)〉/〈E(B − V)〉 = 8.3 × 1021 cm−2 mag−1. By mapping N(H i) and E(B − V) across H i high-velocity cloud complexes and the Magellanic Clouds, we show that the reddening of this kinematically isolated gas is on average 5 times smaller per H i than the high-latitude average. However, the aggregate contribution of this gas is small and 〈N(H i)〉/〈E(B − V)〉 = 8.3 × 1021 cm−2 mag−1 is the appropriate value for Galactic gas seen at high latitude using the H i and reddening measures employed here and in our previous work.

Validação do analisador i-STAT® cartucho CG8+ para análise hemogasométrica

The aim of this study was to compare values arterial blood gas values obtained by laboratory technical reference with values obtained by the i-STAT® CG8+ analyzer, in order to confirm their validity and thus extrapolate its applicability in academic research in the context of physical activity. Were collected 22 samples of blood from the radial artery of the non-dominant arm of patients admitted to the ITU of the Hospital São João Batista, located in Viçosa, Minas Gerais, in the period from February to March 2013. Were compared between the reference method Ciba Corning Gas System 278 and i-STAT® CG8+ portable analyzer the result of the following variables: pH; PO2 and PCO2 expressed in mmHg; HCO3, and TCO2 BE (base excess) expressed in mmol / L; sO2 and expressed as a percentage of saturation. The student t test, correlation test, and Bland-Altman analysis were used. For all blood parameters monitored in the comparison of mean values between the two methods, no significant difference was found for any of the variables. There was a significant correlation (p&lt;0.0001) and strong, with all correlation coefficients (r) above 0.93, between the two methods for all variables. The Bland-Altman analysis showed that there was agreement between the two methods, with over 90% of the sample between the limits of agreement for all variables. The i-STAT® CG8+ analyzer presented acceptable validity in the resting situation by reference to the Ciba Corning 278 Gas System device, and its use is an excellent strategy for research in the area of sport and health sciences that require fast results in the resting situation and that ensure the effectiveness of decision making.

A Systematic Review and Meta-Analysis of Physiologic Variables in Sheep Fetuses.

The fetal sheep model has been widely used in fetal therapy research. However, there is a significant degree of variability among published normal values. Our study aimed to evaluate the literature available on normal values for hemodynamics, blood gases, and acid-base status in the sheep fetus and to determine the best possible estimation of such physiologic values. We conducted a systematic review with a comprehensive search of several databases. We included 189 articles in the database and over 2,800 sheep fetuses. Analysis revealed a mean umbilical blood flow of 202 mL/kg/min (95% CI: 182 to 223); mean arterial pCO₂ of 49.8 mm Hg (95% CI: 49.2 to 50.3); mean arterial pO₂ of 22.3 mm Hg (95% CI: 21.9 to 22.7); mean arterial pH of 7.35 (95% CI: 7.3487 to 7.3562); and mean arterial oxygen saturation of 59.8 (95% CI; 58 to 61.7). Our findings were punctuated by a high heterogeneity, for which we conducted several subanalyses. The results showed high heterogeneity and small study effect in the literature available and provided our best assessment of relevant variables on normal hemodynamics, blood gases, and acid-base status in the fetus after using strategies to mitigate the risk of bias present in the literature.

Performance of pulse oximeters as a function of race compared to skin pigmentation: a single center retrospective study.

Pulse oximetry (SpO2) is a critical monitor for assessing oxygenation status and guiding therapy in critically ill patients. Race has been identified as a potential source of SpO2 error, with consequent bias and inequities in healthcare. This study was designed to evaluate the incidence of occult hypoxemia and accuracy of pulse oximetry associated with the Massey-Martin scale and characterize the relationship between Massey scores and self-identified race. This retrospective single institute study utilized the Massey-Martin scale as a quantitative assessment of skin pigmentation. These values were recorded peri-operatively in patients enrolled in unrelated clinical trials. The electronic medical record was utilized to obtain demographics, arterial blood gas values, and time matched SpO2 values for each PaO2 ≤ 125 mmHg recorded throughout their hospitalizations. Differences between SaO2 and SpO2 were compared as a function of both Massey score and self-reported race. 4030 paired SaO2-SpO2 values were available from 579 patients. The average error (SaO2-SpO2) ± SD was 0.23 ± 2.6%. Statistically significant differences were observed within Massey scores and among races, with average errors that ranged from - 0.39 ± 2.3 to 0.53 ± 2.5 and - 0.55 ± 2.1 to 0.37 ± 2.7, respectively. Skin color varied widely within each self-identified race category. There was no clinically significant association between error rates and Massey-Martin scale grades and no clinically significant difference in accuracy observed between self-reported Black and White patients. In addition, self-reported race is not an appropriate surrogate for skin color.