Measurement Of Partial Pressure Research Articles

Parameter quantification for oxygen transport in the human brain

Background and objective:Oxygen is carried to the brain by blood flow through generations of vessels across a wide range of length scales. This multi-scale nature of blood flow and oxygen transport poses challenges on investigating the mechanisms underlying both healthy and pathological states through imaging techniques alone. Recently, multi-scale models describing whole brain perfusion and oxygen transport have been developed. Such models rely on effective parameters that represent the microscopic properties. While parameters of the perfusion models have been characterised, those for oxygen transport are still lacking. In this study, we set to quantify the parameters associated with oxygen transport and their uncertainties. Methods:Effective parameter values of a continuum-based porous multi-scale, multi-compartment oxygen transport model are systematically estimated. In particular, geometric parameters that capture the microvascular topologies are obtained through statistically accurate capillary networks. Maximum consumption rates of oxygen are optimised to uniquely define the oxygen distribution over depth. Simulations are then carried out within a one-dimensional tissue column and a three-dimensional patient-specific brain mesh using the finite element method. Results:Effective values of the geometric parameters, vessel volume fraction and surface area to volume ratio, are found to be 1.42% and 627 [mm2/mm3], respectively. These values compare well with those acquired from human and monkey vascular samples. Simulation results of the one-dimensional tissue column show qualitative agreement with experimental measurements of tissue oxygen partial pressure in rats. Differences between the oxygenation level in the tissue column and the brain mesh are observed, which highlights the importance of anatomical accuracy. Finally, one-at-a-time sensitivity analysis reveals that the oxygen model is not sensitive to most of its parameters; however, perturbations in oxygen solubilities and plasma to whole blood oxygen concentration ratio have a considerable impact on the tissue oxygenation. Conclusions:The findings of this study demonstrate the validity of using a porous continuum approach to model organ-scale oxygen transport and draw attention to the significance of anatomy and parameters associated with inter-compartment diffusion.

Nondispersive ultraviolet monitoring of pulsed H2S gas delivery

This article describes time-resolved optical measurements of H2S partial pressure and mass flow in a pulsed gas delivery system approximating injection conditions encountered during atomic layer deposition. A high-speed nondispersive ultraviolet (NDUV) gas analyzer design is employed for in-line H2S detection in a gas delivery line with flowing carrier gas. An in-place analyzer calibration performed in a reference cell yields an H2S detection limit of ≈1.4 Pa (at 22 °C) at a sampling rate of 1 kHz. Flow measurements performed on the delivery line are used to evaluate the effects of adjustable delivery parameters on the time-dependent injection system output. Short pulse widths exhibit partial pressure transients attributed to flow development within the different volumes of the delivery system. After ≈1.0 s of injection, steady-state flow is established across flow elements. A partial pressure of H2S in the delivery line is found to vary linearly with upstream H2S pressure, consistent with choked flow. A stronger scaling of partial pressure is evident when the flow coefficient of the downstream metering valve is adjusted. Estimated steady-state H2S flow rates in the range of 0.05–0.21 mg/s are observed within a limited range of valve flow coefficients. However, further increases in the flow coefficient do not result in increased flow, likely due to conductance limitations in downstream flow system components. The utility of NDUV absorption measurements for high-pressure pulsed gas delivery systems is discussed.

Hydrogen Measurement & Extraction at Nevada Solar One

Hydrogen was measured and extracted from the headspace gas of four expansion vessels that are components of the heat transfer fluid (HTF) subsystem in the Nevada Solar One (NSO) power plant, Boulder City, Nevada. Direct, real-time measurements of hydrogen partial pressures in the headspace gas were accomplished using the recently installed hydrogen mitigation process that was developed jointly by the National Renewable Energy Laboratory (NREL) and Acciona Energy, the owner/operator of NSO. This method combines the two functions of extracting hydrogen from the headspace gas and measuring hydrogen partial pressure in the headspace gas. During 2022 and 2023, we operated the process regularly and made real-time measurements of hydrogen partial pressures. In addition, DLR in Germany measured dissolved hydrogen concentration in the circulating HTF. These two measurements were compared via Henry’s Law and found to be consistent. Measured values also were compared to model results that were generated by the NSO plant model that was written to predict hydrogen levels in the power plant piping and components. The model predicted hourly hydrogen partial pressures in the expansion tanks for two cases - hydrogen extraction off, and hydrogen extraction on. Real-time hydrogen measurements and sampled HTF measurements were compared to hydrogen levels that were predicted for these two cases. We found good agreement between the hydrogen measurements and the modeled hydrogen for the extraction on case. These results indicate that the extraction process is working properly with its expected performance.

Thermodynamics of gaseous strontium and calcium cerates studied by Knudsen effusion mass spectrometry and estimation of relative electron ionization cross-section for CeO2(g).

Ceria-based systems are of great interest because of their unique properties. Such systems may be used as anode materials for SOFCs or in oxygen sensors. Theexploitation of these materials often requires high temperatures. In such conditions, the partial or complete evaporation of materials is possible. Therefore, knowledge of the values of partial pressures and thermodynamic properties is essential to predict and/or prevent possible consequences and accidents. Knudsen effusion mass spectrometry was used to determine partial pressures of vapor species over the SrO-CeO2 and CaO-CeO2 systems. Measurements of partial pressures were performed with a MS-1301 mass spectrometer. Vaporization was carried out using molybdenum or tungsten effusion cells. A theoretical study of gaseous strontium and calcium cerates was performed by several quantum chemical methods: density functional theory (DFT) M06, DFT PBE0, and MP2. The minimum value of relative electron ionization cross-section for CeO2 was estimated. In the temperature range of 2218-2249 K above the SrO-CeO2 system and of 2128-2208 K above the CaO-CeO2 system, gaseous M, MO, MO, CeO2, O, O2 and MCeO3 (M = Sr, Ca) were found. Energetically favorable structures of gaseous SrCeO3 and CaCeO3 were found, and vibrational frequencies were evaluated in the "rigid rotor-harmonic oscillator" approximation. On the basis of the equilibrium constants of gaseous reaction MO + CeO2 = MCeO3, the standard formation enthalpy of gaseous SrCeO3 (-913 ± 26 kJ/mol) and of gaseous CaCeO3 (-917 ± 26 kJ/mol) at 298 K were determined. The estimated value of relative electron ionization cross-section for CeO2 is in agreement with the general rule applicable for dioxides. The stability of SrCeO3 and CaCeO3 gaseous species was confirmed by KEMS. Gas-phase reactions involving gaseous SrO (CaO) and CeO2 with gaseous SrCeO3(CaCeO3) were studied. Enthalpy of formation reaction of gaseous SrCeO3(CaCeO3) from gaseous SrO (CaO) were evaluated theoretically, and the obtained value is in agreement with the experimental one.

Effect of anion α-functionalization on the water affinity of thermo-responsive phosphonium acetate-derived ionic liquids

This study presents a facile method for assessing the effect of anion functional group substitution on the water affinity of phosphonium-acetate ionic liquids. By combining the same cation with three different α-substituted carboxylate anions, the effect of anion functional group substitution on the IL miscibility with water and hygroscopicity was experimentally evaluated and rationalized using COSMO-RS sigma profile analysis. Lower critical solution temperature (LCST) phase separation experiments and water vapor partial pressure measurements revealed that there is a stark α-substitution dependency on the affinity of water for acetate [AcO], pivalate [PivO], and trifluoroacetate [TFA] derived tributyl(octyl)phosphonium [P4448] ILs. It was found that the IL water affinities varied as: [P4448][AcO] > [P4448][PivO] > [P4448][TFA]. With the lowest water partial pressure and no LCST driven phase separation, [P4448][AcO] exhibited a high affinity for water. On the other hand, [P4448][PivO] and [P4448][TFA] exhibited LCST-driven phase separation and room temperature immiscibility, respectively, with higher water partial pressures, as a result of relatively weak water affinities. COSMO-RS sigma profile analysis revealed that the aliphatic carboxylate anions should incorporate apolar interactions commensurate with or greater than the polar hydrogen bond acceptor interactions for phase immiscibility of the corresponding IL with water. It was found that the relative magnitudes of apolar and polar interactions, assessed using the anion sigma profile peak intensity ratio (Ir), are directly correlated with the IL water affinity, and inversely correlated with the solution water activity coefficient. Therefore, it was concluded that Ir forms a quantitative link between the structural changes at the molecular level and the bulk water affinity exhibited by the ionic liquid as a whole.

Novel differential pumping system with extended sampling range: Design and application in the EAST tokamak

A novel differential pumping system (DPS) with an adjustable sampling rate has been developed and implemented in the Experimental Advanced Superconducting Tokamak (EAST). This system is equipped with a high-resolution quadrupole mass spectrometer (QMS), covering a mass range of 1–16 atomic mass units (AMU), alongside a conventional QMS with a broader range of 1–200 AMU. The DPS features a dynamic pressure sampling capability from 10−2 to 105 Pa, utilizing a gas dosing valve and an angle valve, enabling a wide gas sampling ratio range of 10−9 to 3 × 10−2. The high-resolution QMS (QMG700) is adept at directly quantifying the partial pressures of deuterium and helium within mixtures, while the conventional QMS (RGA200) offers indirect measurement of D2 partial pressures above 2 × 10−5 Pa, complemented by direct wide-range mass analysis. During the EAST tokamak campaigns of 2023 and 2024, the DPS was effectively utilized for glow discharge cleaning (GDC) at a pressure of 3 Pa and ion cyclotron wall conditioning (ICWC) at approximately 3 × 10−3 Pa, accurately distinguishing deuterium pressure from the helium environment in the wide pressure range of vacuum vessel. Moreover, the DPS was successfully employed to trace the vacuum leak location in EAST campaign with a pressure of up to hundreds Pa. This DPS is a key tool for gas ingredient analysis and leak detection in the EAST campaigns, providing a valuable reference for the vacuum operation of future fusion reactors.

Recent Technologies for Transcutaneous Oxygen and Carbon Dioxide Monitoring.

The measurement of partial pressures of oxygen (O2) and carbon dioxide (CO2) is fundamental for evaluating a patient's conditions in clinical practice. There are many ways to retrieve O2/CO2 partial pressures and concentrations. Arterial blood gas (ABG) analysis is the gold standard technique for such a purpose, but it is invasive, intermittent, and potentially painful. Among all the alternative methods for gas monitoring, non-invasive transcutaneous O2 and CO2 monitoring has been emerging since the 1970s, being able to overcome the main drawbacks of ABG analysis. Clark and Severinghaus electrodes enabled the breakthrough for transcutaneous O2 and CO2 monitoring, respectively, and in the last twenty years, many innovations have been introduced as alternatives to overcome their limitations. This review reports the most recent solutions for transcutaneous O2 and CO2 monitoring, with a particular consideration for wearable measurement systems. Luminescence-based electronic paramagnetic resonance and photoacoustic sensors are investigated. Optical sensors appear to be the most promising, giving fast and accurate measurements without the need for frequent calibrations and being suitable for integration into wearable measurement systems.

Vacuum partial pressure measurement using low-budget dual comb system

Dual-comb spectroscopy is a powerful tool for gas sensing but its expensive cost is limiting its practical application in many fields. In terms of this issue, we present a low-cost and effective dual-comb generation method without complicated feedback lock electronics and nonlinear optics. The proposed dual combs are seeded with the same CW laser, and modulated by electric-optic modulators driven by a pair of pulse trains with slightly different repetition rates of 200 MHz and 200.25 MHz to generate tooth resolved spectrum. A pair of vacuum partial pressure measurements were performed to demonstrate its feasibility and ability. In the experiment, the built dual-comb apparatus is applied to analyze two standard gas mixtures containing carbon monoxide and carbon dioxide respectively. The relative deviations of measurement results against their certified values for carbon monoxide and carbon dioxide are both below 2%. Furthermore, by averaging a set of measurement results at different wavenumbers, the deviation could further be reduced, indicating that the proposed manner is capable of enabling gas partial pressure measurement with good accuracy and low cost.

Drivers of CO2-carbonate system variability in the coastal ocean south of Honolulu, Hawai’i

This study examines carbonate chemistry variability from 2008 to 2021 in subtropical coastal waters adjacent to Honolulu, Hawai’i. We use surface seawater carbon dioxide partial pressure (pCO2sw) measurements obtained every three hours from two buoys located along the south shore of O’ahu near anthropogenically impacted fringing reefs. The Ala Wai buoy was located 200 m offshore of a canal draining most of Honolulu, while the Kilo Nalu buoy was 1.3 miles (2 km) to the northwest, at a similar distance from shore with fewer terrestrial inputs. We compare pCO2sw variability from diurnal to interannual time scales. A trend analysis reveals a statistically significant increase in pCO2sw of +1.84 ± 0.27 µatm per year over the 11-year period. This rate is slightly lower than the average atmospheric growth rate observed during the same timeframe. In contrast to a nearby open-ocean site, the coastal sites experience amplified shorter-term variability, while seasonal to inter-annual variability is comparable to the open ocean. Ala Wai exhibits greater ranges than Kilo Nalu in all carbonate system variables due to its proximity to the Ala Wai Canal outflow. We examine the drivers that may explain both the similarities and contrasts in carbon dynamics observed between the two locations. Drivers of aragonite saturation state (ΩAr), an important variable for quantifying ocean acidification, are isolated from the in-situ time-series. Interannual salinity variations both due to freshwater pulses and large-scale regional salinity changes have a larger impact on ΩAr than temperature changes, which mostly have an effect seasonally. A large biological contribution to ΩAr is suspected, and further investigated using TA/DIC ratios normalized to median salinity and their slopes. Observed ratios at the south shore sites are evaluated relative to expected ratios derived from an open-ocean reference. Results suggest that dissolution and respiration are the primary biogeochemical processes occurring at these coastal sites. This highlights the significance of carbonate dissolution in anthropogenically impacted coastal waters, which is likely buffering acidification due to anthropogenic CO2 and freshwater inputs at these sites.

Connection between partial pressure, volatility, and the Soret effect elucidated using simulations of nonideal supercritical fluid mixtures.

Building on recent simulation work, it is demonstrated using molecular dynamics simulations of two-component fluid mixtures that the chemical contribution to the Soret effect in two-component nonideal fluid mixtures arises due to differences in how the partial pressures of the components respond to temperature and density gradients. Further insight is obtained by reviewing the connection between activity and deviations from Raoult's law in the measurement of the vapor pressure of a liquid mixture. A new parameter γsS, defined in a manner similar to the activity coefficient, is used to characterize differences deviations from "ideal" behavior. It is then shown that the difference γ2S-γ1S is predictive of the signof the Soret coefficient and is correlated to its magnitude. We hence connect the Soret effect to the relative volatility of the components of a fluid mixture, with the more volatile component enriched in the low-density, high-temperature region, and the less volatile component enriched in the high-density, low-temperature region. Because γsS is closely connected to the activity coefficient, this suggests the possibility that measurement of partial vapor pressures might be used to indirectly determine the Soret coefficient. It is proposed that the insight obtained here is quite general and should be applicable to a wide range of materials systems. An attempt is made to understand how these results might apply to other materials systems including interstitials in solids and multicomponent solids with interdiffusion occurring via a vacancy mechanism.

EPR Monitoring of Oxygenation Levels in Tumors After Chlorophyllide-Based Photodynamic Therapy May Allow for Early Prediction of Treatment Outcome

PurposeMolecular oxygen, besides a photosensitizer and light of appropriate wavelength, is one of the three factors necessary for photodynamic therapy (PDT). In tumor tissue, PDT leads to the killing of tumor cells, destruction of endothelial cells and vasculature collapse, and the induction of strong immune responses. All these effects may influence the oxygenation levels, but it is the vasculature changes that have the main impact on pO2. The purpose of our study was to monitor changes in tumor oxygenation after PDT and explore its significance for predicting long-term treatment response.ProceduresElectron paramagnetic resonance (EPR) spectroscopy enables direct, quantitative, and sequential measurements of partial pressure of oxygen (pO2) in the same animal. The levels of chlorophyll derived photosensitizers in tumor tissue were determined by transdermal emission measurements.ResultsThe noninvasive monitoring of pO2 in the tumor tissue after PDT showed that the higher ΔpO2 (pO2 after PDT minus pO2 before PDT), the greater the inhibition of tumor growth. ΔpO2 also correlated with higher levels of the photosensitizers in the tumor and with the occurrence of a severe edema/erythema after PDT.ConclusionMonitoring of PDT-induced changes in tumor oxygenation is a valuable prognostic factor and could be also used to identify potentially resistant tumors, which is important in predicting long-term treatment response.

Online Electrochemical Mass Spectrometry on Large-Format Li-Ion Cells

Significant progress has been made in real-time analysis methodologies for batteries, particularly with regards to the development of Operando Electrochemical Mass Spectrometry (OEMS) [1]. OEMS provides unprecedented selectivity and sensitivity in analysing the release of volatile species, enabling the detection of side reactions during battery cycling which can provide crucial information about the Solid Electrolyte Interface (SEI) and processes that limit battery life. However, most research thus far has been conducted on model battery systems (~1 mAh) that do not accurately reflect conditions within large-format commercial cells (~10,000 mAh) particularly in terms of electrode areas, electrolyte volumes, and stack pressures. Additionally, the atmosphere within the cell is altered through either continuous flow [2] [3] (in the open approach) or purging [4] (in the semi-closed approach [5]). In both cases, gas is being withdrawn from the cell (10% of cell volume/measurement point) during operation and replaced with a carrier gas (usually Ar). This dilutes the existing environment and prevents further reactions, making it difficult to compare the results to real-life situations.In this work, the development and validation of an entirely closed OEMS system that can be interfaced with large-format commercially available batteries is showcased. Instead of replacing the removed gas, a small amount (0.2 % of cell volume/measurement point) is periodically removed, causing a gradual pressure drop in the cell. Experiments are limited by a minimum internal cell pressure of 700 mbar due to the sensitivity of the pressure sensor and vapour pressures of the electrolyte. Apart from this pressure drop, the internal cell environment is therefore relatively constant allowing us to observe side reaction products that have occurred within a realistic cell environment.We additionally provide a detailed description of an adapter design for interfacing large format prismatic cells with our intermittently closed OEMS (ICEMS) setup. The adapter is placed over a hole in the cell (produced with a drill) and can be easily scaled for different cell geometries. Using this ICEMS setup, we provide operando pressure and gassing data from a calendared BAK PHEV2 cell. The pressure within the cell changes depending on the level of lithiation in the cathode (NMC) and anode (graphite), revealing the multiple phase transitions that occur in both materials during cycling. These transitions can be divided into four regions of interest, where graphite dominates regions I and III (with large pressure increases during charge) and NMC dominates regions II and IV (with pressure decreases during charge). By analysing the gas produced during these transitions, it is clear that structural changes within both electrodes result in side reactions. When graphite undergoes large volume changes (from 1L to 2L and 2 to 1, regions I and III), H2 and C2H4 are released as SEI reformation products, while the c lattice collapse in NMC (during the H2 to H3 transition, region IV) results in CO2 evolution (through O2 release that subsequently reacts with the electrolyte). In addition, we suggest that Lewis bases formed on the graphite through the reduction of electrolyte species ring open EC, forming CO2 [6]. The results of this study suggest that the internal chemistry of commercially available prismatic rechargeable batteries can be studied effectively using ICEMS without significantly altering the battery's chemistry.[1] A. M. Tripathi, W. N. Su, and B. J. Hwang, “In situ analytical techniques for battery interface analysis,” Chem. Soc. Rev., vol. 47, no. 3, pp. 736–751, 2018, doi: 10.1039/c7cs00180k.[2] P. Novák et al., “Advanced in situ characterization methods applied to carbonaceous materials,” J. Power Sources, vol. 146, no. 1–2, pp. 15–20, 2005, doi: 10.1016/j.jpowsour.2005.03.129.[3] N. Tsiouvaras, S. Meini, I. Buchberger, and H. A. Gasteiger, “ A Novel On-Line Mass Spectrometer Design for the Study of Multiple Charging Cycles of a Li-O 2 Battery ,” J. Electrochem. Soc., vol. 160, no. 3, pp. A471–A477, 2013, doi: 10.1149/2.042303jes.[4] R. Lundström and E. J. Berg, “Design and validation of an online partial and total pressure measurement system for Li-ion cells,” J. Power Sources, vol. 485, no. December 2020, 2021, doi: 10.1016/j.jpowsour.2020.229347.[5] L. A. Kaufman and B. D. McCloskey, “Surface Lithium Carbonate Influences Electrolyte Degradation via Reactive Oxygen Attack in Lithium-Excess Cathode Materials,” Chem. Mater., pp. 1–7, 2021, doi: 10.1021/acs.chemmater.1c00935.[6] N. Gogoi et al., “Silyl-Functionalized Electrolyte Additives and Their Reactivity toward Lewis Bases in Li-Ion Cells,” Chem. Mater., vol. 34, no. 8, pp. 3831–3838, 2022, doi: 10.1021/acs.chemmater.2c00345.

The effect of sepsis and reactive oxygen species on skeletal muscle interstitial oxygen pressure during contractions.

This study aims to examine the effect of sepsis on the dynamics of skeletal muscle partial oxygen pressure during muscle contractions as well as the effect of reactive oxygen species (ROS) scavenger (ascorbic acid, Asc). Twenty-seven male Sprague-Dawley rats (2-3 months old) were randomly assigned to three groups; sham, cecal ligation and puncture (CLP), or CLP plus ascorbic acid treatment group (CLP + Asc). Electrical stimuli-induced muscle contractions and partial oxygen pressure measurements were performed at 3 h after CLP. The interstitial oxygen pressure (PO2 is) in the spinotrapezius muscle was measured by the phosphorescence quenching method. The PO2 is at rest was not different between the three groups. The PO2 is decreased from rest to contraction in all groups. Compared to the sham, the time to decrease PO2 is was significantly faster in CLP but not in CLP + Asc (p < .05). Compared to the sham, the PO2 is during muscle contractions was significantly lower in both CLP and CLP + Asc (p < .05, respectively). Our results suggest that CLP-induced sepsis accelerated the decay of PO2 is at the onset of muscle contractions and maintained a low level of PO2 is during muscle contractions.

Elucidating the Performance Limits for Electrochemical CO2 Separation Using Exergy Loss Analysis and Zero-Dimensional Modeling

The use of renewable electricity to power electrochemical CO2 removal and concentration from point sources, air, and seawater is receiving considerable interest as one strategy in our portfolio of options for mitigating climate change. Two common embodiments of this idea involve CO2 separation via electrochemically reversible binding of CO2 to a nucleophilic redox mediator, or a pH swing/gradient in aqueous solution. For either embodiment to be feasible, the energetic cost of regenerating the sorbent should be low at practical separation throughputs. Consequently, there have been a number of efforts to understand how the thermodynamic minimum work input for a given separation cycle varies under different conditions using modeling. In this talk, we demonstrate that the thermodynamic minimum work input for electrochemical CO2 separation is the sum of exergy losses incurred from differences between the partial pressure of CO2 within the CO2 source/exit streams and the partial pressure of CO2 in the sorbent. This framework rationalizes minimum work inputs for pH-swing and redox-mediator-based CO2 separation cycles, and motivates the measurement or estimation of the aforementioned CO2 partial pressures in experimental studies. Applying a zero-dimensional model recently developed in our group to pH-swing-driven CO2 separation, we will then discuss how the total energetic cost of CO2 separation can be simulated under a variety of scenarios relevant to practical CO2 concentration from flue gas.

Nocturnal Hypoventilation in the Patients Submitted to Thoracic Surgery.

Nocturnal hypoventilation may occur due to obesity, concomitant chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and/or the use of narcotic analgesics. The aim of the study was to evaluate the risk and severity of nocturnal hypoventilation as assessed by transcutaneous continuous capnography in the patients submitted to thoracic surgery. The material of the study consisted of 45 obese (BMI 34.8 ± 3.7 kg/m2) and 23 nonobese (25.5 ± 3.6 kg/m2) patients, who underwent thoracic surgery because of malignant (57 patients) and nonmalignant tumors. All the patients received routine analgesic treatment after surgery including intravenous morphine sulfate. Overnight transcutaneous measurements of CO2 partial pressure (tcpCO2) were performed before and after surgery in search of nocturnal hypoventilation, i.e., the periods lasting at least 10 minutes with tcpCO2 above 55 mmHg. Nocturnal hypoventilation during the first night after thoracic surgery was detected in 10 patients (15%), all obese, three of them with COPD, four with high suspicion of moderate-to-severe OSA syndrome, and one with chronic daytime hypercapnia. In the patients with nocturnal hypoventilation, the mean tcpCO2 was 53.4 ± 6.1 mmHg, maximal tcpCO2 was 59.9 ± 8.4 mmHg, and minimal tcpCO2 was 46.4 ± 6.7 mmHg during the first night after surgery. In these patients, there were higher values of minimal, mean, and maximal tcpCO2 in the preoperative period. Nocturnal hypoventilation in the postoperative period did not influence the duration of hospitalization. Among 12 patients with primary lung cancer who died during the first two years of observation, there were 11 patients without nocturnal hypoventilation in the early postoperative period. Nocturnal hypoventilation may occur in the patients after thoracic surgery, especially in obese patients with bronchial obstruction, obstructive sleep apnea, or chronic daytime hypercapnia, and does not influence the duration of hospitalization.

Examination of Lower Limb Microcirculation in Diabetic Patients with and without Intermittent Claudication.

Intermittent claudication is a frequent complaint in lower extremity artery disease, but approximately two thirds of patients are asymptomatic, most of which are diabetic patients. Non-invasive angiological and microrheological tests on diabetic subjects with and without intermittent claudication were performed in the present study. In total, 98 diabetic patients were included and divided into two groups: 20 patients (63.5 ± 8.8 years, 55% men, 45% women) had intermittent claudication, 78 patients (65.5 ± 9.3 years, 61.5% men, 38.5% women) were asymptomatic. Hand-held Doppler ultrasound examination, transcutaneous tissue partial oxygen pressure (tcpO2) measurement, Rydel-Seiffer tuning fork tests, and 6-min walk tests were performed, and erythrocyte aggregation was investigated. Ankle-brachial index (p < 0.02) and tcpO2, measured during provocation tests (p < 0.003) and the 6-min walk test (p < 0.0001), significantly deteriorated in the symptomatic group. A higher erythrocyte aggregation index and faster aggregate formation was observed in claudication patients (p < 0.02). Despite the statistically better results of the asymptomatic group, 13% of these patients had severe limb ischemia based on the results of tcpO2 measurement. Claudication can be associated with worse hemodynamic and hemorheological conditions in diabetic patients; however, severe ischemia can also develop in asymptomatic subjects. Non-invasive vascular tests can detect ischemia, which highlights the importance of early instrumental screening of the lower limbs.

Automated CO2 and CH4 monitoring system for continuous estimation of degassing related to hydropower

Reliable measurement of greenhouse gas emissions from reservoirs is essential for estimating the carbon footprint of the hydropower industry. Among the different emission pathways, degassing downstream of the turbines and spillway is poorly documented mainly because of the safety stakes related to sampling up and downstream the power plants. The alternative being to sample the water from the turbine inside the station, this study aimed to assemble a custom automated CO2 and CH4 monitoring system (SAGES), especially designed for long-term surveys in hydropower facilities, with a special focus on low maintenance requirements. The SAGES combines infrared and laser technologies with a modular programming approach and run with a specifically designed plexiglass equilibration system (PES) that maintain a permanent headspace and avoid clogging by suspended solids. Although the SAGES is based on commercially available devices, it is the first time they are combined and used with the gas equilibrator. To ensure the reliability of the mounting and to control the quality of the readings, the system was tested in laboratory prior to its installation in generating stations. SAGES and PES performances were compared with those of generic devices available on the market although less adapted to the specific deployments targeted. The SAGES gas partial pressure measurements were accurate and linear in the entire range tested: 0 to 5,000 ppm for pCO2 and 0 to 600 and 10,000 ppm for pCH4. Gas PP measurements were comparable to the reference CO2/CH4 sensor and there was no drift during long term deployment. The SAGES/PES installed in 2021 in cascading generating stations of the Romaine complex collected more than 28,000 data points over a 10-month period and required only two maintenances. Results show that the SAGES is a reliable tool that provide long-term CO2 and CH4 dataset in generating stations while requiring minimal energy, care and maintenance. The data collected in turbine water and the recent use of the SAGES in peat land by a collaborative team demonstrate how the SAGES systems can efficiently contribute to the understanding of reservoir carbon cycles.

Sailing through the southern seas of air-sea CO2 flux uncertainty.

The Southern Ocean is among the largest contemporary sinks of atmospheric carbon dioxide on our planet; however, remoteness, harsh weather and other circumstances have led to an undersampling of the ocean basin, compared with its northern hemispheric counterparts. While novel data interpolation methods can in part compensate for such data sparsity, recent studies raised awareness that we have hit a wall of unavoidable uncertainties in air-sea [Formula: see text] flux reconstructions. Here, we present results from autonomous observing campaigns using a novel platform to observe remote ocean regions: sailboats. Sailboats are at present a free of charge environmentally friendly platform that recurrently pass remote ocean regions during round-the-globe racing events. During the past 5 years, we collected [Formula: see text] measurements of the sea surface partial pressure of [Formula: see text] (p[Formula: see text]) around the globe including the Southern Ocean throughout an Antarctic circumnavigation during the Vendée Globe racing event. Our analysis demonstrates that the sailboat tracks pass regions where large uncertainty in the air-sea [Formula: see text] flux reconstruction prevails, with regional oversaturation or undersaturation of the sea surface p[Formula: see text]. Sailboat races provide an independent cross-calibration platform for autonomous measurement devices, such as Argo floats, ultimately strengthening the entire Southern Ocean observing system. This article is part of a discussion meeting issue 'Heat and carbon uptake in the Southern Ocean: the state of the art and future priorities'.

Chlorine partial pressure measurements over CuCl2/CuCl by transpiration method with gas detector tubes

Copper-chlorine compounds often play important roles in many industrial processes, but no reliable values of their thermodynamic quantities have been established. In this work, we measured the equilibrium chlorine partial pressure over CuCl(s) and CuCl2(s) by the transpiration method to find accurate thermodynamic quantities of the copper-chlorine compounds. The temperature dependence of the equilibrium chlorine partial pressure is given by the following equation: logpCl2/bar=9.805±2.535-8633.1±1433.4T/K-1 (from 526 to 604 K), and the standard enthalpy change of the reaction (2 CuCl2(s) ⇌ 2 CuCl(s) + Cl2(g)) at 298.15 K is calculated as (161.7 ± 0.48) kJ mol−1 by the third-law method. This equation and value agree well with a thermodynamic data compilation Thermodynamic Properties of Individual Substances (L.V. Gurvich, I.V. Veyts, and C.B. Alcock, vol. 1, 1989 and V. S. Iorish et al., vol. 5, http://www.chem.msu.su/rus/tsiv/, accessed 18 September 2020).

Monitoring of cerebral perfusion via oxygen partial pressure (ptiO2) measurement and near-field infrared spectroscopy (NIRS) in aneurysmatic subarachnoid haemorrhage

Monitoring of cerebral perfusion via oxygen partial pressure (ptiO2) measurement and near-field infrared spectroscopy (NIRS) in aneurysmatic subarachnoid haemorrhage