Partial Pressure Research Articles

The Assessment of Muscle Strength and Cardiorespiratory Parameters Using Simple Tests in Older Adults With Recovery From Mild COVID-19.

To evaluate muscle strength and cardiorespiratory parameters, this study uses simple tests in older adults, including those who have and have not recovered from mild coronavirus disease 2019 (COVID-19). Eighty older adults (age≥60 years old) were divided into two groups: those without previous COVID-19 (control group, n=40) and those with recovery from mild COVID-19 (recovered group, n=40). Muscle strength was assessed using a handgrip strength test and the sit-to-stand test (STS10). Cardiorespiratory parameters were evaluated with a 1-minute sitto- stand (1-min STS) test and a 6-minute walk test (6MWT). Both groups had normal values for body mass index, blood pressure, heart rate, and pulse oxygen saturation. The recovered group showed significant differences in handgrip strength test (24.73±6.99 vs. 22.03±4.36, p=0.041) and duration for the STS10 (25.15±6.11 vs. 33.40±7.56, p<0.001) when compared to the control group. Furthermore, the recovered group had significantly decreased repetitions of a 1-min STS (31.38±4.89 vs. 21.25±3.64, p<0.001) and increased the rate of perceived exertion (RPE) (7.43±1.20 vs. 8.95±1.01, p=0.01) and leg fatigue (1.49±1.13 vs. 3.00±1.04, p=0.03) after performing a 1-min STS when compared with the control group. Moreover, the recovered group had also significantly decreased distances for the 6MWT (421.68±8.28 vs. 384.35±6.17, p<0.001) and increased the post-test RPE (7.63±1.37 vs. 12.05±1.63, p<0.001) and the post-test leg fatigue (1.71±0.88 vs. 5.28±0.91, p<0.001) compared with the control group. Older adults with recovery from mild COVID-19 reported reduced muscle strength and exercise tolerance when compared with older adults without COVID-19.

Characteristics of the pregnancy and labour course in women who underwent COVID-19 during pregnancy.

This study aims to analyze the impact of COVID-19 on pregnancy and labor, focusing on its effects on maternal and child health. The research explores the relationships between coronavirus infection and clinical and laboratory parameters, as well as the risks of pregnancy complications and adverse birth outcomes. The study involved 60 pregnant women diagnosed with COVID-19. A comprehensive evaluation of clinical and laboratory indicators was conducted, employing correlation, regression, logistic analyses to determine risk factors. There was a strong inverse correlation between carbon dioxide levels and haematocrit (-0.76), and a direct correlation between blood pH and partial pressure of oxygen (0.73). COVID-19 was associated with increased risks of preterm labor (OR=1.82), stillbirth (OR=2.11), pre-eclampsia (OR=1.46), and foetal distress. Multivariate analysis revealed a 200 g reduction in neonatal birth weight and higher risks of hospitalisation (OR=1.8), postpartum hemorrhage (OR=2.3), and preterm delivery (OR=2.5). Comorbid conditions such as cardiovascular abnormalities, diabetes, obesity, thrombophilias exacerbated the risks of complications, including pre-eclampsia, neonatal respiratory distress syndrome, venous thromboembolism. COVID-19 infection increases the likelihood of pregnancy complications and adverse outcomes, especially in women with comorbidities. These findings highlight the need for preventive strategies and risk management protocols for pregnant women during future outbreaks, emphasizing the importance of further research in this field.

Empiric gram-negative antibiotics usage among critically ill patients across 13 ICUs of Nepal: A retrospective cohort study

Background This study aims to investigate the associations between patient characteristics and the receipt of empiric broad-spectrum gram-negative antimicrobials among adult patients admitted to ICUs in Nepal. Methods A retrospective cohort study was conducted in 13 ICUs in Nepal between January 1st, 2020, and December 31st, 2022. Empiric antibiotic use was defined as receiving gram-negative antibiotics within the first two days of ICU admission without evidence of infection from culture. Patient characteristics between patients receiving narrow-spectrum antibiotics and broad-spectrum gram-negative antibiotics were compared. Continuous variables were compared using mean and standard deviation, with mean differences and 95% confidence intervals calculated. Categorical variables were compared using the chi-square test. A multi-level multivariable regression model assessed the relationship between selected variables and broad-spectrum antibiotic usage, treating admitting ICU as a random factor. Results Among 12,349 eligible patients, 8720 (70.6%) received Empiric gram-negative antibiotics. Of those, 3240 (37.15%) received empiric narrow-spectrum gram-negative antibiotics, and 5480 (62.8%) received Empiric broad-spectrum gram-negative antibiotics. Patients receiving broad-spectrum gram-negative antibiotics were older (57.4 vs 53.8 yrs); had higher mean heart rates (97.3 vs 89.5 bpm), respiratory rates (24 vs 21.9), a fraction of inspired oxygen ( 50% vs 40%), blood sugar levels (163.4 vs 153.9 mg/dl), total leucocyte counts (12,685 vs 10,647 cells/cu mm) and serum creatinine (2.06 vs 1.03 umol/l) compared to narrow spectrum antibiotics. Similarly, patients receiving broad-spectrum gram-negative antibiotics had lower systolic blood pressure (122.6 vs 126.5 mm Hg), partial pressure of oxygen (96.7 vs 105.3), and pH ( 7.33 vs 7.36) compared to narrow-spectrum antibiotics. On multivariable regression; patients with readmission, cardiac support, and mechanical ventilation were more likely to receive broad-spectrum antibiotics. Conclusion The rate of empiric broad-spectrum gram-negative antibiotics usage in intensive care units is significantly high and associated with features of increased severity of illness.

Characterization of Lipid Production in Chlorella sp. Cultivated in Different Plant Fertilizers

Microalgae have gained attention due to their higher reproduction rate and lipid productivity. In particular, various stress conditions lead to an overproduction of lipids in microalgae cells. The study investigated the influence of additional CO2 introduced with air into the reactor during biomass growth of Chlorella sp. Additionally, increased phosphorus concentration in the medium under stress cultivation (low nitrogen concentration) was examined. The partial pressure of CO2 and its increased availability to Chlorella sp. in the cultivation medium increased biomass growth (1.4 times) and chlorophyll content (2.5 times) in microalgae cells. A high phosphorus fertilizer significantly increased lipid production under stress conditions with CO2 supply to 85.2 mg/g (2.6 times) and without CO2 to 73.8 mg/g (2.2 times). A high concentration of phosphorus in the culture medium stimulated the synthesis of C16:0 (about 38–45%) and C18:1 CIS9 (about 24–30%). The results confirm that the fertilizers can be used as a culture medium to induce stress and stimulate lipid production. Adjusting the composition of the fertilizers and controlling the additional CO2 supply could prove beneficial to increase the content of the desired fatty acids.

Calculation of heat consumption for dissociation gas combustion products

The influence of temperature and partial pressure on the dissociation of carbon dioxide and water vapor is considered. An original analytical method for determining the degree of dissociation of CO2 and H2O is proposed. The calculation of dissociation parameters was carried out in relation to the conditions of gas combustion in a glass furnace. It has been established that the temperature range of 1500‒1800 oC, corresponding to the operating conditions of glass melting furnaces, is characterized by a relatively low degree of dissociation of CO2 and H2O: 4.23 and 1,26 %, respectively. As a consequence, the relative heat costs for dissociation are insignificant and do not exceed 2,48 %. The degree of dissociation and heat consumption for the endothermic effect increase most intensively at the temperature of the gas combustion products above 1800 °C.

Electron-Beam-Evaporated Nickel Oxide Thin Films for Application as a Hole Transport Layer in Photovoltaics

We present the growth of nickel oxide (NiO) thin films as a hole transport material in photovoltaic devices using the e-beam evaporation technique. The metal oxide layers were reactively deposited at a substrate temperature of 200 °C using an electron beam evaporator under an oxygen atmosphere. The oxide films reactively grown through electron-beam evaporation were optimized for carrier transport layers. Optical and structural characterizations were performed using ultraviolet–visible (UV–Vis) spectrometry, X-ray diffraction, contact angle measurements, scanning electron microscopy, and Hall effect measurements. The study of these films confirmed that the NiO layer is a suitable candidate for use as a hole transport layer based on Hall effect measurements. A morphological study using field-emission scanning electron microscopy confirmed the growth of compact, uniform, and defect-free metal oxide layers. Contact angle measurements revealed that the films possessed semi-hydrophilic properties, contributing to improved stability by repelling water from their surfaces. The stoichiometry of the films was influenced by the oxygen pressure during deposition, which affected both their morphological and optical features. The NiO films exhibited a transmittance exceeding 80% in the visible spectrum. These findings highlight the potential applications of such nickel oxide films as hole transport material layers.

Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational Approach.

The optical centers in AlN can frequently exist in various charge states and can be accompanied by many coexisting defect species, creating a complex environment where mutual interactions are inevitable. Therefore, it is an immediate quest to design AlN crystal growth protocols that can target a specific optical center of interest and tune its concentration while preventing the formation of other unwanted point defects. Here, we provide a powerful workflow for point defect engineering in wide band gap, binary semiconductors that can be readily used to design optimal crystal growth protocols through combining CALPHAD-based phase analysis, and ab initio defect calculations. We investigate technologically relevant chromium- and manganese-induced optical centers in AlN, followed by studying the impact of oxygen that can be unintentionally incorporated during crystal growth. We present the dominant defects in all three cases as a function of process parameters along with the optical signatures. In the case of both Cr and Mn doping, the CrAl and MnAl defects are most likely, and increasing nitrogen partial pressure tends to enhance their concentration. We show that it is possible to use nitrogen fugacity as a tool for tuning the intensity of optical signatures. We calculate the CrAl charge transition levels with respect to the valence-band maximum at 2.60 eV (E+/-), 3.83 eV (E0/-), and 5.41 eV (E-/2-) and electron and hole capture transitions with luminescence bands centered at 2.82, 1.91, and 3.15 eV. Unlike the Cr doping, Mn aggregation is unlikely, and the MnAl-VN is the most abundant defect after MnAl under most synthesis conditions. Oxygen tends to form complexes with VAl, and ON-VAl is a prominent defect following ON, with near-UV emission bands at 3.17, 3.26, and 3.81 eV. Our results agree with the available experimental optical signatures of Cr-, Mn-, and O-related centers and provide pathways on how to tune the luminous intensity of these centers through changes in growth conditions.

Cortex kidney tissue partial oxygen pressure depends on percentage of active oxygenation during oxygenated hypothermic machine perfusion.

Preclinical and clinical studies have demonstrated the advantages of oxygenated hypothermic machine perfusion (HMPO2) during kidney preservation. However, the optimal oxygenation levels during HMPO2 remain undetermined. The aim of this study was to compare different levels of oxygenation (0%, 21%, 50%, and 100%) during 22 h of active oxygenated HMP (HMPO2) using oxygen preloading by bubbling oxygenation in the preservation solution and continuous surface oxygenation during MP in a porcine DCD model. After 60 min of warm ischemia time, both kidneys of an 80 kg pig were procured and randomized to one of the following groups: (1) 22-h static cold storage (n = 6), (2) 22-h HMP without active oxygenation (n = 6), (3) 22-h HMPO2 21% O2 (n = 6), (4) 22-h HMPO2 50% O2 (n = 6), and (5) 22-h HMPO2 100% O2 (n = 6). The primary outcome measure was to compare the different oxygen levels among the different groups assessed by cortex kidney tissue oxygen partial pressures (tpO2). Continuous HMPO2 resulted in a significant modification of cortex kidney tpO2. In addition, tpO2 was dependent on the percentage of oxygenation. One hundred percent oxygen resulted in a significantly higher tpO2 compared to all other study groups. In line with that, ATP resynthesis was significantly higher in the HMPO2 100% group. This study demonstrates that continuous HMPO2 results in a significant modification of tpO2 compared with SCS, and the degree of tpO2 is positively correlated with the percentage of active oxygenation during HMP. Metabolic profile analyses (ATP resynthesis) suggest that the aerobic mechanism is better supported with higher oxygen levels (50% and 100% oxygenation).

Interannual and Seasonal Variability of CO2 Parameters in the Tropical Atlantic Ocean

This study examined the carbon cycling dynamics in the tropical Atlantic Ocean from 1985 to 2023, focusing on factors influencing the surface partial pressure of CO2 (pCO2), freshwater input, total alkalinity (ALK), total dissolved carbon (TCO2), and pH levels. The time series data revealed significant trends, with average pCO2 concentrations rising from approximately 350 μatm in the early 1990s to over 400 μatm by 2023. The TCO2 levels increased from about 2000 μmol/kg to 2200 μmol/kg, while ALK rose from approximately 2300 μmol/kg to 2500 μmol/kg. This increase highlights the ocean’s role as a carbon sink, particularly in areas with high biological productivity and upwelling where TCO2 also rose. This study employed Empirical Orthogonal Functions (EOFs) to identify variability modes and understand spatial patterns of pCO2. Freshwater dynamics significantly affect TCO2 concentrations, particularly in coastal regions, where pH can shift from 8.2 to 7.9, exacerbating acidification. Rising sea surface temperatures have been linked to elevated pCO2 values. These findings support the need for ongoing monitoring and effective management strategies to mitigate the impacts of climate change and ensure the sustainability of marine resources. This study documented the long-term trends in tropical Atlantic CO2 parameters linked to the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO).

Assessment of change in end-tidal CO2 after fluid challenge as a marker of fluid responsiveness as measured by the aortic velocity time integral in healthy anesthetized mechanically ventilated dogs.

To evaluate if variation in the end-tidal CO2 partial pressure (∆Petco2) after a fluid challenge could predict fluid responsiveness with a sensitivity of 75% and a specificity of 70% in healthy anesthetized and mechanically ventilated dogs. Diagnostic accuracy study. University hospital. Twenty-seven dogs admitted for neutering. To obtain a balanced sample between fluid responder and nonresponder dogs, a 10-mL/kg lactated Ringer's solution was administered over 15minutes to half of the population before the baseline measurements. All animals then received a fluid challenge of 10mL/kg lactated Ringer's solution in 5minutes. The velocity-time integral of aortic blood flow (VTIAo) was evaluated with Doppler echocardiography before and after a fluid challenge to classify the included dogs as fluid responders or nonresponders. Fluid responsiveness was defined as an increase of ≥15% of the VTIAo after the fluid challenge. Petco2 was evaluated at 1, 5, and 10(T1,T5,T10)minutes after fluid expansion. Area under the receiver operating characteristic curve (AUROC) analysis was used to assess the ability of ∆Petco2 to predict fluid responsiveness at different time points. A total of 13 dogs were fluid responders, and 14 were nonresponders. The best predictive capacity for ∆Petco2 was observed at T10. The AUROC with its 95% confidence interval (CI) for ∆Petco2 at T10 was 0.75 (0.56-0.93), with a sensitivity of 84.62% (95% CI, 54.60-98.10), a specificity of 64.29% (95% CI, 35.10-87.20), a positive predictive value of 68.80% (95% CI, 41.30-89.00), and a negative predictive value of 81.80% (95% CI, 48.20-97.70). The optimal cutoff was 1mmHg. The current study showed that, although minimal, ∆Petco2 predicted fluid responsiveness in the dogs studied.

Investigation of plasma sprayed Sr0·7La0·3TiO3 / La0·2Sr0·8MnO3 Bi-layer interconnector performance and its application in high power tubular solid oxide fuel cells

Atmospheric plasma spraying (APS) has been demonstrated as an efficient and rapid method for manufacturing high-performance solid oxide fuel cells (SOFCs), with interconnects serving as the “wires” for large-scale integration of SOFCs. However, the challenge of producing highly conductive and stable interconnects through plasma spraying remains unresolved. This study developed a Bi-layer perovskite interconnect for segmented-in-series solid oxide fuel cell (SIS–SOFCs). It involved APS-prepared dense N-type interconnects of Sr0·7La0·3TiO3 (LST), achieving low porosity, low leakage rate, and high conductivity LST coatings. The element of Ti valence state changes and conductivity of LST powders, hydrogen-treated powders, LST coatings, and hydrogen-treated coatings were quantitatively analyzed through phase detection and elemental valence state analysis under different oxygen partial pressure conditions to explore the variation of LST coating conductivity. Simultaneously, bi-layer interconnector model using La0·2Sr0·8MnO3(LSM)as the P-type interconnect was established to elucidate the electron transport mechanism within the Bi-layer interconnect under operating conditions and propose optimization schemes for the structural design of tubular serial-connected cell interconnects. The tubular dual-cell combination using LST/LSM Bi-layer interconnectors exhibited a maximum power density of 360 mW/cm2 at 800 °C, with only 33% interconnector loss compared to the maximum power density of 540 mW/cm2 achieved by a single cell at 800 °C. Additionally, it attained the highest open circuit voltage (1.9 V) at 650 °C. This Bi-layer interconnectors has been successfully applied in serial-connected tubular cells with more than 5 cells. Furthermore, the dual-cell combination showed almost no performance loss under 100 h of constant current discharge (0.3 A/cm2) testing. These research findings indicate that the LST/LSM Bi-layer interconnectors prepared using atmospheric plasma spraying is an ideal material system for the functional layer of interconnects in high-power tubular segmented-in-series solid oxide fuel cell structures.

Removal of Trace Benzene from Cyclohexane Using a MOF Molecular Sieve.

Cyclohexane (Cy), commonly produced by the catalytic hydrogenation of benzene (Bz), is used in large quantities as a solvent or feedstock for nylon polymers. Removing trace unreacted Bz from the Cy product is technically difficult due to their similar molecular structures and physical properties. Herein, we report that a metal-organic framework (MOF) adsorbent shows a molecular sieving effect for Bz and Cy with record-high Bz/Cy adsorption selectivities (216, 723, and 1027) in their liquid mixtures (v/v = 1:1, 1:10, and 1:20), and traps Bz molecules effectively even at low partial pressure in the vapor phase (e.g., 2.49 mmol/g at 8.2 Pa) or at low content in liquid-phase Cy (e.g., 128 mg/g at 20 ppm). Over 99% removal of trace Bz (1000 ppm) from liquid Cy could be achieved in one simple stripping step at room temperature using this sorbent, producing a Cy with >99.999% purity. Single-crystal structure analyses for guest-free and Bz-loaded phases of the MOF disclosed that a narrow slit-like pore aperture and the strong uniting of multiple weak host-guest and guest-guest interactions are the co-origin of its distinct adsorption property for Bz and Cy.

Immediate postinjury extracorporeal carbon dioxide removal reduces ventilator requirements and mitigates acute respiratory distress syndrome in swine.

Awareness of ventilator-induced lung injury contributed to increased use of extracorporeal interventions, but not immediately after injury, before acute respiratory distress syndrome (ARDS) ensues. Our objective was to evaluate the role of venovenous extracorporeal carbon dioxide removal (ECCO2R) in management of mechanically ventilated swine with smoke inhalation injury and 40% body surface area burns. Yorkshire swine (n = 29, 43.2 ± 0.5 kg) underwent anesthesia, instrumentation, severe smoke inhalation, and 40% body surface area burns, followed by 72 hours of round-the-clock intensive care unit care with mechanical ventilation, fluids, pressors, bronchoscopic cast removal, computer tomography scans, and arterial blood assays. Within 1 hour after injury, animals received ECCO2R with either MiniLung (Xenios AG, Heilbronn, Germany; n = 10) or Hemolung (ALung Technologies, Pittsburgh, PA; n = 10), or no ECCO2R in injured controls (INJC, n = 12). Immediate postinjury ECCO2R reduced minute ventilation (p < 0.001) and prevented ARDS in 37.5% of MiniLung and 11.1% of Hemolung animals. Time to ARDS (partial pressure of arterial oxygen to fraction of inspired oxygen ratio below 300) was shortest (14 ± 2.2 hours) in INJC, intermediate (21.6 ± 3.5 hours) in Hemolung (HEMO), and most delayed in MiniLung (31.1 ± 7.2 hours, p = 0.0121, log-rank test vs. INJC). Driving pressure was lower in MiniLung versus INJC (p < 0.0001) and HEMO versus INJC (p = 0.0005) at 48 hours. Extracorporeal CO2 removal reduced systemic levels of tumor necrosis factor α versus INJC. In swine with severe smoke inhalation and burns, immediate postinjury ECCO2R reduced ventilator settings, delayed or prevented ARDS, and reduced its severity. Proactive early percutaneous ECCO2R initiation via simplified, purpose-built devices should be considered as a low-maintenance lung injury management approach with significant disease modifying clinical benefit potential.

In Vivo Mouse Abdominal Oxygen Imaging And Assessment of Subcutaneously Implanted Beta Cell Replacement Devices.

Type 1 diabetes (T1D) is an autoimmune disease that leads to the loss of insulin-producing pancreatic beta cells. Beta cell replacement devices or bioartificial pancreas (BAP) have shown promise in curing T1D and providing long-term insulin independence without the need for immunosuppressants. Hypoxia in BAP devices damages cells and imposes limitations on device dimensions. Noninvasive in vivo oxygen imaging assessment of implanted BAP devices will provide the necessary feedback and improve the chances of success. Pulse-mode electron paramagnetic resonance (EPR) oxygen imaging (EPROI) using injectable trityl OX071 as the oxygen-sensitive agent is an excellent technique for obtaining partial oxygen pressure (pO2) maps in vitro and in vivo. In this study, our goal was to optimize in vivo mouse abdominal EPROI and demonstrate proof-of-concept pO2 imaging of subcutaneously implanted BAP devices. All EPROI experiments were performed using a 25 mT EPROI instrument, JIVA-25®. For in vivo EPROI experiments, trityl OX071, a whole-body mouse resonator (∅32mm × 35mm), C57BL6 mice, and the inversion recovery electron spin echo (IRESE) pulse sequence were utilized. We investigated the signal amplitude and pO2 in mouse abdomen region for intravenous (i.v.) and intraperitoneal (i.p.) injection methods with either only a single bolus (B) or bolus plus infusion (BI) for 72.2mM OX071 and the effect of OX071 concentrations from 18 to 72.2 mM for the i.p.-B injection method. We also investigated the impact of animal respiratory rate on mouse abdominal pO2. Finally, we performed proof-of-concept pO2 imaging of two subcutaneously implanted BAP devices, OxySite and TheraCyte. At the end of the four-week study, the TheraCyte devices were extracted and analyzed for fibrosis, vascular differentiation, and immune cell infiltration. We established that mouse abdominal pO2 remains stable irrespective of trityl injection methods, concentrations, imaging time, or animal breathing rate. We demonstrate that the i.p.-B and i.p.-BI methods are suitable for EPROI, and i.p.-B method provides higher signal amplitude compared to i.v.-BIand up to 75min of imaging. An injection with a reduced trityl concentration and higher volume provides higher signal amplitude for i.p.-B method at the beginning. We also highlight the advantage of milder anesthesia for consistent, reliable mouse pO2 imaging. Finally, we demonstrate that EPROI could provide longitudinal noninvasive oxygen assessment of subcutaneously implanted BAP devices in vivo. In vivo EPROI is a reliable technique for mouse abdominal oxygen imaging and longitudinal assessment of subcutaneously implanted BAP devices noninvasively. This work reports abdominal oxygen imaging in the mouse model and demonstrates its application for the assessment of BAP devices. Even though the application focus of this work was on cell therapy, the techniques developed will have a much broader use in the biomedical field.

A Multiscale Mathematical Model for Fetal Gas Transport and Regulatory Systems During Second Half of Pregnancy.

Fetal asphyxia, a condition resulting from the combined effects of hypoxia and hypercapnia, leads to approximately 900,000 annual deaths worldwide. One cause is umbilical cord compression during labor-induced uterine contractions, disrupting the transport of metabolites to and from the placenta, and resulting in asphyxia. Current fetal well-being assessment relies on monitoring fetal heart rate and uterine contractions as indicators of oxygen delivery to the brain. To enhance our understanding of this complex relationship, this study aims to develop a modular mathematical model including fetal blood gas dynamics, the autonomic nervous system, and cerebral blood flow regulation. The novelty of this study lies in the capability of the model to simulate fetal growth. These submodels are part of a larger multiscale mathematical model describing fetal circulation in the second half of pregnancy. The blood gas model realistically replicates partial oxygen and carbon dioxide pressures in umbilical arteries and veins during healthy fetal development reported in the literature. An in silico experiment is conducted to simulate umbilical cord occlusion and is compared with lamb experiments to verify the realism of the regulation models during fetal growth. Our findings suggest that premature infants are more susceptible to umbilical cord occlusion, exhibiting elevated cerebral perfusion pressure and flow. This modular mathematical model may serve as a valuable tool for testing hypotheses related to the fetal regulatory system.

Research and design of multiple gas mixing system in modified atmosphere packaging

Despite the abundant production of fruits and vegetables in Xinjiang, there is an increasing trend in waste rates. Gas-controlled packaging techniques are employed post-harvest to enhance freshness and extend shelf life. However, the multi-gas mixing system at the core of this equipment often encounters challenges such as insufficient stability, limited precision, high costs, and inadequate intelligence. In this context, we have developed and designed a multi-gas mixing system for gas-conditioned packaging. The system integrates Internet of Things technology, uses a programmable controller as the core, proposes a ternary gas distribution model based on the ideal gas equation and Dalton’s law of partial pressures, and utilizes RS-485 bus, TCP/IP protocol, among others. This ensures communication between the equipment and data transmission with the cloud server while enabling remote control of the gas mixing and blending process via a mobile phone terminal. The system runs stably through testing, with the average relative deviations of CO2 and O2 gas concentrations being 0.86% and 0.72%, respectively. This fulfills the technical prerequisites for achieving a gas concentration precision of less than 1%, addressing challenges related to inadequate precision in gas blending, unstable performance, and limited visual representation. Moreover, it significantly reduces equipment costs and operational complexities while serving as a valuable reference for advancing multivariate gas mixing and blending technology in Xinjiang’s fruit and vegetable gas-conditioned packaging.

The influence of yoga exercises with voluntary pulmonary ventilation changes on intracranial arterial blood flow

Introduction. Yoga breathing exercises that involve voluntary changes in pulmonary ventilation parameters can potentially influence cerebral circulation due to changes in CO2 content in arterial blood. Objective. To assess the effect of yoga breathing exercises with changes in pulmonary ventilation levels on blood flow parameters in the middle cerebral artery (MCA). Methods. The study included 21 participants, with an average age of 39.5±8.7 years, who were capable of performing yoga exercises at respiratory rates (RR) of 3–3.5/min and 1–1.5/min. For 5 minutes, participants underwent three stages: free breathing (stage 1), breathing with RR=3–3.5/min (stage 2), and breathing with RR=1–1.5/min (stage 3). During stages 2 and 3, the «full breathing» technique, which involves maximum deep inhalation and exhalation, was employed. Respiratory rate (RR), tidal volume (TI), minute ventilation (MV), end-tidal CO2 partial pressure (PetCO2), and oxygen fraction in exhaled air (FeO2) were recorded using spiro-gas analysis. Transcranial duplex scanning was used to measure peak systolic blood flow velocity (Vps), end-diastolic blood flow velocity (Vd), time-averaged maximum blood flow velocity (TAMAX), and resistance index (RI) in the right MCA. The velocity variation index (VVI) was calculated for each stage. Results. Compared to stage 1 (free breathing), stage 2 (RR = 3–3.5/min) showed an increase in MV and FeO2, a decrease in PetCO2, and reductions in Vps, Vd, and TAMAX, with an increase in RI. VVI decreased statistically insignificantly. In stage 3 (RR = 1–1.5/min), compared to stage 1, there was an increase in PetCO2, a decrease in MV and FeO2, and increases in Vps, Vd, and TAMAX, with a decrease in RI. VVI increased significantly. Conclusions. Yoga breathing exercises at respiratory rates of 3–3.5/min and 1–1.5/min result in multidirectional shifts in ventilation and gas exchange parameters, leading to changes in arterial cerebral blood flow (a decrease and increase in blood flow velocity with an increase and decrease in MV, respectively). VVI, reflecting fluctuations in blood flow velocity, increases significantly with reduced MV, likely due to the vasodilatory effect of CO2.

Theoretical analyses of the performance parameters of PEM fuel cells at various operating temperatures and pressures

In the present study, the performance parameters for a single-cell PEM fuel cell with 50 cm2 active surface area and 0.0178 cm polymer membrane thickness at 4 different operating temperatures (303, 323, 343, and 363 K) and 4 different operating pressures (3, 6, 9, and 12 atm) was investigated by theoretical analysis. Hydrogen and oxygen partial pressures, membrane resistivity, internal resistance, activation, ohmic and concentration losses, cell voltage, power density, and thermal efficiency were calculated using this analysis. It has been observed that the augmentation of temperature and pressure in the fuel cell leads to a favorable increase in cell voltage, power density, and thermal efficiency. The thermal efficiency values were found to be 23% and 39%, respectively at the following conditions: temperatures of 303 K and 363 K, current density of 1 A/cm2, and constant pressure. At the same current density, the thermal efficiency is 29% and 32% at 3 atm and 12 atm operating pressures at a constant temperature. When operated under constant current density and temperature conditions, an increase in the operating pressure of the PEMFC from 3 atm to 12 atm results in a corresponding increase in cell voltage, from 0.4422 V to 0.4755 V, respectively. It was observed that the influence of temperature on the thermal efficiency of the PEM fuel cell was led to be higher than the influence of pressure.

Phase Formation, Microstructure, and Permeability of Fe-Deficient Ni-Cu-Zn Ferrites (II): Effect of Oxygen Partial Pressure

We have investigated the phase formation, microstructure, and permeability of stoichiometric and Fe-deficient Ni-Cu-Zn ferrites of composition Ni0.30Cu0.20Zn0.50+zFe2−zO4−(z/2) with 0 ≤ z ≤ 0.06 sintered at 1000 °C in various oxygen partial pressures pO2, which range from 0.21 atm down to 10−5 atm. The density of the sintered samples is almost independent of the pO2, whereas the grain size of the Fe-deficient ferrites decreases in more reducing atmospheres. Stoichiometric ferrites show a regular growth of single-phase ferrite grains if sintered in air. Sintering at pO2 ≤ 10−2 atm leads to the formation of a small amount of Cu2O at grain boundaries and triple points. Fe-deficient compositions (z &gt; 0) form Cu-poor stoichiometric ferrites, which coexist with a minority CuO phase homogeneously distributed between the grains after sintering in air. At pO2 ≤ 10−2 atm, the CuO grain boundary phase starts to transform into Cu2O, which concentrates at some triple points at pO2 = 10−2 atm, and it is more homogeneously distributed between the ferrite grains at the lower pO2. Formation of the Cu oxide second phases is investigated using XRD, SEM, and EDX. The permeability at 1 MHz of the stoichiometric ferrites (z = 0) is between µ′ = 200 and µ′ = 300 within the studied range of the pO2. The permeability at 1 MHz of the Fe-deficient samples decreases with the pO2, e.g., from µ′ = 750 at pO2 = 0.21 atm to µ′ = 320 at pO2 = 10−5 atm for z = 0.02, respectively.

A comparison of the effect of oxygen partial pressure on microstructural evolution of PAN fibers during industrial carbon fiber production line at different altitudes

Understanding and regulating the oxidative stabilization behavior of polyacrylonitrile (PAN) precursor fibers are critical subjects of high-performance carbon fiber production technologies. Here, we performed continuous stabilization and carbonization of PAN fibers at industrial carbon fiber production lines in different locales (different oxygen partial pressure in atmosphere), and investigated the microstructural evolution of the fibers with a systematically analysis at different stages. Influence of oxygen partial pressure in oxidative stabilization atmosphere on tensile modulus of the obtained carbon fibers was obvious. Oxygen diffused into PAN fibers during oxidative stabilization, more homogeneous and crosslinked structures generated under higher oxygen partial pressure atmosphere, and gave the stabilized fibers lower skin-core ratio. The graphite layers gradually generated in the subsequent carbonization stages, and the gathered graphite layers transformed into graphite microcrystalline, the wide-angle x-ray diffraction (WAXD) demonstrated that higher oxygen partial pressure conditions contributed to the generation of higher crystallite preferred orientation and bigger crystallite size, Raman spectroscopy also confirmed the obtained carbon fibers with higher oxygen partial pressure conditions possessed more ordered graphite structures. Thus, relatively higher oxygen partial pressure in air gave the stabilized fibers more crosslinked structures, and contributed to the formation of high-performance carbon fibers.