Measurement Of Partial Pressure Research Articles

Modeling and Experimental Analysis of pH Swing-Based Approaches to Electrochemical CO2 Capture

The use of renewable electricity to drive large-scale electrochemical CO2 removal and concentration from point sources, air, and seawater is receiving considerable interest as one strategy for mitigating climate change.1 The low concentration of CO2 in air however makes rapid and energy-efficient CO2 capture challenging. Understanding and optimizing the energetic cost of CO2 separation at practically reasonable throughputs is a prerequisite for engineering devices that can be widely deployed.I will review our past and current efforts at developing electrochemical pH-swing-based CO2 separation (EPCS) using a combination of modeling and experiments. In EPCS, CO2 is captured from a mixture of gases into an aqueous electrolyte in the form of (bi)carbonate ions when its pH is increased from acidic to strongly alkaline conditions, and then released as a pure gas when the pH is reversed. We have shown that CO2 separation is experimentally possible for less than 100 kJ/molCO2 using such a pH swing cycle that is driven by proton-coupled electron transfer (PCET).2 Thermodynamic modeling shows that the minimum work input for electrochemical CO2 separation is the sum of exergy losses incurred from differences in CO2 partial pressure between the CO2 source/exit streams and the electrolyte. 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 future experimental studies.More recently, we have begun to consider a new design for EPCS in which PCET-active species are conformally attached to the internal surface area of a highly porous electrode, and effect a reversible pH swing in an adjacent layer of aqueous electrolyte upon redox cycling. We have formulated a continuum reaction-transport model that simulates reactive CO2 capture into and release from the electrolyte layer, as well as transport of (bi)carbonate species, and protons, in response to an applied current or voltage. Possible pathways toward achieving an energetic cost of direct air capture of CO2 less than 100 kJ/molCO2 will be discussed, as well as our efforts toward experimental demonstration of this concept. References Renfrew, S. E.; Starr, D. E.; Strasser, P., Electrochemical Approaches toward CO2 Capture and Concentration. ACS Catalysis 2020, 10 (21), 13058-13074.Jin, S.; Wu, M.; Gordon, R. G.; Aziz, M. J.; Kwabi, D. G., pH swing cycle for CO2 capture electrochemically driven through proton-coupled electron transfer. Energy & Environmental Science 2020.

Comprehensive mass transfer analysis of CO2 absorption in high potential ternary AMP-PZ-MEA solvent using three-level factorial design.

Mass transfer of CO2 absorption in 2-amino-2-methyl-1-propanol (AMP)-piperazine (PZ)-monoethanolamine (MEA) was statistically investigated in terms of overall mass transfer coefficient ([Formula: see text]) and CO2 removal percentage. The parameters of interest were lean solvent flux (A), rich gas flux (B), CO2 loading in the lean solvent (C), and ratio of the sampling height to the total column height [Formula: see text] (D). From ANOVA, A was the most impactable parameter on both responses with three-quarters of the overall contribution. Regarding the three-level factorial design, a second-order polynomial increasing trend of [Formula: see text] was observed as C and/or D increased. Additionally, [Formula: see text] linearly increased as A increased but was not affected by B. On the other hand, the CO2 removal percentage linearly increased as A and/or D increased but linearly decreased as B and/or C increased. Surface analysis suggested the optimum condition for both responses at a high level of A, low level of B, low level of C, and middle level of D. In this work, D was statistically investigated and included in the predictive correlation for [Formula: see text] for the first time. The main advantage of the proposed correlation over the recently reported correlations was that it did not require a measurement of CO2 partial pressure along the column height. For each amine component in the blend, (i) AMP played a positive key role in cyclic capacity and solvent regeneration duty, (ii) PZ enhanced transfer rate, and (iii) MEA elevated total amine concentration. As a result, 1.5:1.5:3 was recommended due to (i) elevations of 68.2% [Formula: see text], 14% CO2 removal percentage, 15.1% absorption capacity, and 66.7% cyclic capacity and (ii) reduction of 50% regeneration duty compared with 5M MEA. With respect to the other literature-reported solvents, AMP-PZ-MEA is very competitive in terms of transfer coefficient, cyclic capacity, and solvent regeneration heat duty.

Tightly-Coupled Visual-Inertial-Pressure Fusion Using Forward and Backward IMU Preintegration

In this work, we present a visual-inertial-pressure (VIP) fusion method for underwater robot localization. Specifically, this letter focuses on the tightly-coupled fusion of pressure measurements into a visual inertial odometry (VIO) based on sliding window optimization. Previous works used to associate partial pressure measurements with the nearest keyframes, which not only fail to utilize all the pressure measurement information but also introduce measurement errors that only lead to sub-optimal solutions. Inspired by the current tightly-coupled visual-inertial-GPS and visual-inertial-UWB fusion methods, this letter uses IMU preintegration algorithm to derive the pressure factors. Furthermore, we propose a backward IMU preintegration method and the pressure factors are derived using forward or backward IMU preintegration based on the time-offset between the pressure measurements and the adjacent keyframes. Quantitative and qualitative analyses through simulation and real-world datasets experiments demonstrate the effectiveness of the method with negligible time cost.

End-tidal Anesthetic Concentration: Monitoring, Interpretation, and Clinical Application

Age-adjusted fraction of minimum alveolar concentration derived from end-tidal anesthetic partial pressure measurement remains a useful drug advisory display to help prevent awareness if interpreted with proper understanding of the quantal and probabilistic nature of minimum alveolar concentration, semantics, drug interactions, and hysteresis.

Mass spectrometric study of the laser-produced carbon vapor up to 4500 K

The mass spectrometric measurements of the molecular composition in a carbon vapor produced by the laser-induced sublimation of pyrolitic graphite have been carried out up to 4500 K, temperature that stands very close to the carbon's triple point. The measurements of the relative partial pressure of the dominant С3 molecule up to the maximum temperature achieved did not deliver any unanticipated results, which could be attributed to any kind of the phase transitions. This has therefore indirectly confirmed that the temperature of the carbon triple point cannot be below 4500 К. The widely known problem of a significant deviation of evaporation coefficients of carbon molecules from unity has been largely addressed by a comparative analysis of the evaporation of two planes of pyrolitic graphite. The technical means that allowed for the mass spectrometric study of the carbon sublimation at extreme temperatures are further discussed in detail.

The importance of hydrology in routing terrestrial carbon to the atmosphere via global streams and rivers

SignificanceStream/river carbon dioxide (CO2) emission has significant spatial and seasonal variations critical for understanding its macroecosystem controls and plumbing of the terrestrial carbon budget. We relied on direct fluvial CO2 partial pressure measurements and seasonally varying gas transfer velocity and river network surface area estimates to resolve reach-level seasonal variations of the flux at the global scale. The percentage of terrestrial primary production (GPP) shunted into rivers that ultimately contributes to CO2 evasion increases with discharge across regions, due to a stronger response in fluvial CO2 evasion to discharge than GPP. This highlights the importance of hydrology, in particular water throughput, in terrestrial-fluvial carbon transfers and the need to account for this effect in plumbing the terrestrial carbon budget.

Feasibility of Transcutaneous Method for Carbon Dioxide Monitoring in an Intensive Care Unit

Background: Transcutaneous partial pressure of carbon dioxide (PtCO2) monitorization provides a continuous and non-invasive measurement of partial pressure of carbon dioxide (pCO2). In addition, peripheral oxygen saturation (SpO2) can also be measured and followed by this method. However, data regarding the correlation between PtCO2 and arterial pCO2 (PaCO2) measurements acquired from peripheric arterial blood gas is controversial. Objective: We aimed to determine the reliability of PtCO2 with PaCO2 based on its advantages, like non-invasiveness and continuous applicability. Methods: Thirty-five adult patients with hypercapnic respiratory failure admitted to our tertiary medical intensive care unit (ICU) were included. Then we compared PtCO2 and PaCO2 and both SpO2 measurements simultaneously. Thirty measurements from the deltoid zone and 26 measurements from the cheek zone were applied. Results: PtCO2 could not be measured from the deltoid region in 5 (14%) patients. SpO2 and pulse rate could not be detected at 8 (26.7%) of the deltoid zone measurements. Correlation coefficients between PtCO2 and PaCO2 from deltoid and the cheek region were r: 0,915 and r: 0,946 (p = 0,0001). In comparison with the Bland-Altman test, difference in deltoid measurements was -1,38 ± 1,18 mmHg (p = 0.252) and in cheek measurements it was -5,12 ± 0,92 mmHg (p = 0,0001). There was no statistically significant difference between SpO2 measurements in each region. Conclusion: Our results suggest that PtCO2 and SpO2 measurements from the deltoid region are reliable compared to the arterial blood gas analysis in hypercapnic ICU patients. More randomized controlled studies investigating the effects of different measurement areas, hemodynamic parameters, and hemoglobin levels are needed.

Partial Pressure of Oxygen in Stunted and Normal Growth Children and Risk Factors for Stunting by Altitude

Background Risk factors for stunting are not only during a child’s growth period, but also during maternal period. Pregnant mothers at high altitude could influence stunted growth to the child due to low oxygen partial pressure. Aim Observing and comparing risk factors for stunting by altitude and other contributing factors. Methods This was a cross-sectional study conducted to patients <5 years old in Ulu Pungkut highland (700 meters above sea level) and Desa Singkuang lowland (4 – 6 meters above sea level) from March 2019. Anthropometric and oxygen partial pressure measurements were done to 38 children in the highland and 38 children in the lowland with stunted and normal growth. Results PaCO2, total CO2 and HCO3 values were significantly different among the research subjects residing in the lowland and highland (p<0.0001). There were no significant differences in oxygen partial pressure between children with stunted and normal growth. Conclusion Subjects in highland and lowland had significant differences in PaCO2, total CO2 and HCO3 between different altitudes in this study. However, oxygen partial pressure was not significantly different between stunted and normal growth children.

Study of oxygen-ion conductivity and luminescence in the ZrO2 – Nd2O3 system: Impact of local heterogeneity

Stabilized fluorites and pyrochlores with different types of substitution in the (Nd2O3 − ZrO2 system (NdZrO)) have been studied by Raman spectroscopy, X-ray diffraction, and impedance spectroscopy methods. Ionic and proton conductivity maps for 9 compositions in the NdZrO system are presented. Oxygen partial pressure measurements show a typical ionic conductor behavior, with a significantly increase of conductivity for (Nd2−xZrx)Zr2O7+x/2 (x = 1.27) fluorite and (Nd2−xZrx)Zr2O7+x/2 (x = 0.4, 0.2) pyrochlores. For the same compositions the strong luminescence was observed. Strong luminescence and high oxygen-ion conductivity of these solid solutions can be associated with the presence of phases with the different degree of structural disorder (tetragonal phase, fluorite) in local nanodomains in fluorite or pyrochlore matrix in the ZrO2 − Nd2Zr2O7 region. Really, Raman spectra of (Nd2−xZrx)Zr2O7+x/2 (x = 0.5 − 0.2) solid solutions demonstrated the fluorite + pyrochlore structural type in the short-range order. Fluorite nanodomains in pyrochlore matrix (ZrO2 – Nd2Zr2O7 region) resulting from an order–disorder transition can only be detected at a radiation wavelength comparable to the fluorite nanodomain size. Thus, using Raman spectroscopy the broad isomorphism range in the ZrO2 – Nd2Zr2O7 system has been shown to be nonuniform.

Arterial and Mixed Venous Kinetics of Desflurane and Sevoflurane, Administered Simultaneously, at Three Different Global Ventilation to Perfusion Ratios in Piglets with Normal Lungs.

Previous studies have established the role of various tissue compartments in the kinetics of inhaled anesthetic uptake and elimination. The role of normal lungs in inhaled anesthetic kinetics is less understood. In juvenile pigs with normal lungs, the authors measured desflurane and sevoflurane washin and washout kinetics at three different ratios of alveolar minute ventilation to cardiac output value. The main hypothesis was that the ventilation/perfusion ratio (VA/Q) of normal lungs influences the kinetics of inhaled anesthetics. Seven healthy pigs were anesthetized with intravenous anesthetics and mechanically ventilated. Each animal was studied under three different VA/Q conditions: normal, low, and high. For each VA/Q condition, desflurane and sevoflurane were administered at a constant, subanesthetic inspired partial pressure (0.15 volume% for sevoflurane and 0.5 volume% for desflurane) for 45 min. Pulmonary arterial and systemic arterial blood samples were collected at eight time points during uptake, and then at these same times during elimination, for measurement of desflurane and sevoflurane partial pressures. The authors also assessed the effect of VA/Q on paired differences in arterial and mixed venous partial pressures. For desflurane washin, the scaled arterial partial pressure differences between 5 and 0 min were 0.70 ± 0.10, 0.93 ± 0.08, and 0.82 ± 0.07 for the low, normal, and high VA/Q conditions (means, 95% CI). Equivalent measurements for sevoflurane were 0.55 ± 0.06, 0.77 ± 0.04, and 0.75 ± 0.08. For desflurane washout, the scaled arterial partial pressure differences between 0 and 5 min were 0.76 ± 0.04, 0.88 ± 0.02, and 0.92 ± 0.01 for the low, normal, and high VA/Q conditions. Equivalent measurements for sevoflurane were 0.79 ± 0.05, 0.85 ± 0.03, and 0.90 ± 0.03. Kinetics of inhaled anesthetic washin and washout are substantially altered by changes in the global VA/Q ratio for normal lungs.

Monitoring Mitochondrial Partial Oxygen Pressure During Cardiac Arrest and Extracorporeal Cardiopulmonary Resuscitation. An Experimental Pilot Study in a Pig Model.

Introduction: Ischemia and reperfusion are crucial in determining the outcome after cardiac arrest and can be influenced by extracorporeal cardiopulmonary resuscitation (ECPR). The effect of ECPR on the availability and level of oxygen in mitochondria remains unknown. The aim of this study was to find out if skin mitochondrial partial oxygen pressure (mitoPO2) measurements in cardiac arrest and ECPR are feasible and to investigate its course.Materials and Methods: We performed a feasibility test to determine if skin mitoPO2 measurements in a pig are possible. Next, we aimed to measure skin mitoPO2 in 10 experimental pigs. Measurements were performed using a cellular oxygen metabolism measurement monitor (COMET), at baseline, during cardiac arrest, and during ECPR using the controlled integrated resuscitation device (CIRD).Results: The feasibility test showed continuous mitoPO2 values. Nine experimental pigs could be measured. Measurements in six experimental pigs succeeded. Our results showed a delay until the initial spike of mitoPO2 after ECPR initiation in all six experimental tests. In two experiments (33%) mitoPO2 remained present after the initial spike. A correlation of mitoPO2 with mean arterial pressure (MAP) and arterial partial oxygen pressure measured by CIRD (CIRD-PaO2) seemed not present. One of the experimental pigs survived.Conclusions: This experimental pilot study shows that continuous measurements of skin mitoPO2 in pigs treated with ECPR are feasible. The delay in initial mitoPO2 and discrepancy of mitoPO2 and MAP in our small sample study could point to the possible value of additional measurements besides MAP to monitor the quality of tissue perfusion during cardiac arrest and ECPR.

Effect of electrode temperature on measurements of transcutaneous carbon dioxide partial pressure and oxygen partial pressure in very low birth weight infants.

To evaluate the accuracy and safety of measurements of transcutaneous carbon dioxide partial pressure (TcPCO2) and transcutaneous oxygen partial pressure (TcPO2) at electrode temperatures lower than the value used in clinical practice in very low birth weight infants. A total of 45 very low birth weight infants were enrolled. TcPCO2 and TcPO2 measurements were performed in these infants. Two transcutaneous monitors were placed simultaneously for each subject. One electrode was set and maintained at 42℃ used in clinical practice for neonates (control group), and the other was successively set at 38℃, 39℃, 40°C, and 41℃ (experimental group). The paired t-test was used to compare the measurement results between the groups. A Pearson correlation analysis was used to analyze the correlation between the measurement results of the experimental group and control group, and between the measurement results of experimental group and arterial blood gas parameters. There was no significant difference in TcPCO2 between each experimental subgroup (38-41℃) and the control group. TcPCO2 in each experimental subgroup (38-41℃) was strongly positively correlated with TcPCO2 in the control group (r>0.9, P<0.05) and arterial carbon dioxide partial pressure (r>0.8, P<0.05). There were significant differences in TcPO2 between each experimental subgroup (38-41℃) and the control group (P<0.05), but TcPO2 in each experimental subgroup (38-41℃) was positively correlated with TcPO2 in the control group (r=0.493-0.574, P<0.05) and arterial oxygen partial pressure (r=0.324-0.399, P<0.05). No skin injury occurred during transcutaneous measurements at all electrode temperatures. Lower electrode temperatures (38-41℃) can accurately measure blood carbon dioxide partial pressure in very low birth weight infants, and thus can be used to replace the electrode temperature of 42°C. Transcutaneous measurements at the lower electrode temperatures may be helpful for understanding the changing trend of blood oxygen partial pressure.

This Month in Anesthesiology

This Month in Anesthesiology

High-vacuum setup for permeability and diffusivity measurements by membrane techniques

The knowledge of the permeability and diffusivity (the diffusion coefficient) of materials to different gases is essential for a wide range of applications, such as food packaging, gas separation techniques, and vacuum technology. In this paper, we describe a versatile high-vacuum apparatus for permeation measurements, based on a membrane technique, with the aim of increasing the reliability of results and allowing measurements of permeability of different materials whose permeability spanning several orders of magnitude. The apparatus is equipped with a residual gas analyzer for measurements of partial and total pressure, a spinning rotor gauge for accurate determination of pressure, a calibrated leak to determine pumping speed and capacitance diaphragm gauges for accurate pressure measurements greater than 10−2 Pa. The apparatus works in a static or a dynamic mode. Its performance is tested on polydimethylsiloxane with N2 and Viton® with He as tracer gases. The lower measurement limit of the apparatus depends mainly on the degassing of the inner walls of the chamber. With the procedure described in this paper, it is possible measured permeability from 10−5 cm2/s to 10−10 cm2/s.

Rapid and precise partial pressure measurement of multiple gas species with mid-infrared electro-optic dual-comb spectroscopy

In order to overcome the shortcoming of the TDLAS method, a partial pressure measurement method based on dual comb spectroscopy is proposed. The comb-based partial pressure measurement system comes with excellent performance in nearly all criteria: high detection sensitivity, high measurement speed, and synchronous survey of multiple-gas partial pressures. The experimental system was built in the mid-infrared band of 88.42–90.10 THz with a spectral resolution of 54.5 MHz and used for partial pressure measurement of CH4 and C2H4. Two electro-optics (EO) optical frequency combs (OFC) with a repeat frequency of ～25 GHz are spectrally interpolated to increase spectral sampling ratio using an acousto-optic frequency shifter, so that they could be utilized for high-resolution gas sensing. The measurement result demonstrates the excellent performance of this system in partial pressure measurement. The deviation of the measurement results of two gases CH4 and C2H4 from the true value are about 3%. Moreover, once the gas absorption line strength is accurately calibrated, the accuracy of partial pressure measurement will be further improved.

Influence of Residual Contaminants in Li-Ion Battery Electrolytes Investigated Via Operando Total and Partial Pressure Analysis

Gas evolution in Li-ion batteries (LIB) is triggered by an intricate mix of potential-induced electrochemical and thermally activated reactions. A small percentage of these reactions lead to the formation of interphases capable of stabilizing the electrodes when operating outside of a stable potential window of the electrolyte. The most well-known example thereof is the solid electrolyte interphase (SEI), but the formation process is still not fully understood. What makes interphase reactions complicated to understand is that many compounds that form are metastable and will over time decompose or further react with other species at the interphase.1 Advanced operando and/or in situ characterisation techniques are highly advantageous when monitoring the formation of metastable compounds during charge/discharge of the battery. Online electrochemical gas analysis (OEMS) is a technique where volatile species evolving in LIBs can be monitored by utilizing mass spectrometry. The use of online gas analysis for LIBs has been around for 20 years,2 where adaptations have continuously improved the characterisation of interphase and decomposition processes in LIBs.3 In this presentation our newest improvements to online gas analysis will be presented, where simultaneous partial and total pressure measurements for Li-ion cells are possible. By combining the two techniques in the same experiment and utilizing improved gas connections throughout the OEMS system we gain refined calibration protocols, possibility to map out unidentified volatile species and selective detection of volatile compounds evolving on a ~0.1 nmol/min scale.4 The detailed gas profile of the classical LiCoO2/Graphite (LCO/G) system with 1 M LiPF6 ethylene dicarbonate:diethyl carbonate (1:1 volume ratio) during overcharge and elevated temperature (50°C) will be used as the basis to discuss interphase and decomposition reactions in LIBs (Figure 1). The gas profiles for LiCoO2/LiFePO4 and Graphite/LiFePO4 cells will be presented along with the LCO/G cell to further derive where gases originate in a Li-ion cell and what chemical and electrochemical processes play major roles in non-reversible interphase reactions in LIB systems. Finally, the influence of residual contamination in electrolytes will be discussed as it makes a major impact on the gas evolution in LIBs, which will be showcased in a glassy carbon/LiFePO4 model system with varying volumes of electrolyte. The influence of contamination needs to be put in the spotlight to further our understanding of metastable processes in complex systems such as LIBs and to improve their overall performance.[[Figure 1 goes here]]Figure 1. Stacked gas and total pressure profiles in a LiCoO2/Graphite cell with 1M LiPF6 ethylene dicarbonate:diethyl carbonate electrolyte during cyclic voltammetry to overcharge potentials at elevated temperature (50°C). References (1) Heiskanen, S. K.; Kim, J.; Lucht, B. L. Generation and Evolution of the Solid Electrolyte Interphase of Lithium-Ion Batteries. Joule 2019, 3 (10), 2322–2333.(2) Imhof, R.; Novák, P. In Situ Investigation of the Electrochemical Reduction of Carbonate Electrolyte Solutions at Graphite Electrodes. J. Electrochem. Soc. 1998, 145 (4), 1081–1087.(3) Tripathi, A. M.; Su, W. N.; Hwang, B. J. In Situ Analytical Techniques for Battery Interface Analysis. Chem. Soc. Rev. 2018, 47 (3), 736–751.(4) Lundström, R; Berg; EJ; Submitted to J. Power. Sources. Figure 1

Electrical properties of CaWO4–SiO2 composites

Composite materials (1 − f) CaWO4 – fSiO2 with volume fraction of SiO2f ≤ 1.0 were prepared by the solid state method. The obtained composites have been examined by SEM-EDS, the electrochemical impedance technique, conductivity measurements versus oxygen partial pressure and EMF measurements in order to evaluate ion transport numbers. It was shown that heterogeneous doping of the poor oxygen ion conductor CaWO4 with nano-SiO2 even at low concentration (f < 0.03) leads to an increase in ionic conductivity of the composites by more than an order of magnitude. The enhancement of conductivity in this system was explained by an additional contribution of the interface regions formed between the host and nanoparticles of dispersoid. A general mixing rule was applied for the calculation of electric conductivity of the (1 − f)CaWO4 – fSiO2 composite as a function of SiO2 concentration. Theoretical dependences were analyzed and compared with the experimental results.

Bedside monitoring of lung volume available for gas exchange

BackgroundBedside measurement of lung volume may provide guidance in the personalised setting of respiratory support, especially in patients with the acute respiratory distress syndrome at risk of ventilator-induced lung injury. We propose here a novel operator-independent technique, enabled by a fibre optic oxygen sensor, to quantify the lung volume available for gas exchange. We hypothesised that the continuous measurement of arterial partial pressure of oxygen (PaO2) decline during a breath-holding manoeuvre could be used to estimate lung volume in a single-compartment physiological model of the respiratory system.MethodsThirteen pigs with a saline lavage lung injury model and six control pigs were studied under general anaesthesia during mechanical ventilation. Lung volumes were measured by simultaneous PaO2 rate of decline (VPaO2) and whole-lung computed tomography scan (VCT) during apnoea at different positive end-expiratory and end-inspiratory pressures.ResultsA total of 146 volume measurements was completed (range 134 to 1869 mL). A linear correlation between VCT and VPaO2 was found both in control (slope = 0.9, R2 = 0.88) and in saline-lavaged pigs (slope = 0.64, R2 = 0.70). The bias from Bland–Altman analysis for the agreement between the VCT and VPaO2 was − 84 mL (limits of agreement ± 301 mL) in control and + 2 mL (LoA ± 406 mL) in saline-lavaged pigs. The concordance for changes in lung volume, quantified with polar plot analysis, was − 4º (LoA ± 19°) in control and − 9° (LoA ± 33°) in saline-lavaged pigs.ConclusionBedside measurement of PaO2 rate of decline during apnoea is a potential approach for estimation of lung volume changes associated with different levels of airway pressure.

The Influence of Combined Physical Therapy Procedures on Oxygen Partial Pressure in Tissues Surrounding Ulcer in Patients With Venous Leg Ulcers.

Venous ulcers in lower legs remain a profound treatment problem in contemporary medicine. Proper healing requires, among other things, sufficient blood supply and provision of suitable amount of oxygen to the treated tissues. The aim of the study was to assess the influence of combined physical therapy applied in patients with chronic venous leg ulcers on the oxygen partial pressure values. Fifty-four patients (25 females and 29 males), in the age range of 38 to 89 years with chronic venous leg ulcers, underwent a cycle of 15 procedures with the use of Laserobaria-S device. During a procedure, the patient's lower limb was simultaneously exposed to oxygen having the pressure of 1.5 ATA, low-frequency magnetic field, and low-energy light radiation. Before procedures, directly after the first procedure, as well as on completion of the entire therapeutic cycle, the patients underwent oxygen partial pressure measurements in the tissues surrounding the ulceration area, by means of transcutaneous oximetry, with the use of Medicap Précise 8008s device. The combined physical therapy shows a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, from the average of 68.63 ± 17.04 mm Hg before commencing the therapeutic cycle, to the average of 74.20 ± 18.92 mm Hg after the first procedure (P < .001) and to the average value of 83.79 ± 20.74 mm Hg (P < .001) after completion of therapeutic cycle. Combined physical therapy procedures cause a statistically significant increase of oxygen partial pressure values in tissues surrounding the ulceration, assessed using the objective method of transcutaneous oximetry, both in women and men.

Applications of Vacuum Measurement Technology in China’s Space Programs

The significance of vacuum measurement technology is increasingly prominent in China’s thriving space industry. Lanzhou Institute of Physics (LIP) has been dedicated to the development of payloads and space-related vacuum technology for decades, and widely participated in China’s space programs. In this paper, we present several payloads carried on satellites, spaceships, and space stations; the methodologies of which covered the fields of total and partial pressure measurement, vacuum and pressure leak detection, and standard gas inlet technology. Then, we introduce the corresponding calibration standards developed in LIP, which guaranteed the detection precision of these payloads. This review also provides some suggestions and expectations for the future development and application of vacuum measurement technology in space exploration.