Mixture Of Oxygen Research Articles

Analgosedation in Pediatric Emergency Care: A Comprehensive Scoping Review

Effective management of pain and anxiety in pediatric emergency room is crucial for ensuring both the physical and emotional well-being of young patients. Analgosedation, a combination of analgesia and sedation, is commonly used to facilitate various procedures in children. However, selecting the optimal agent and administration route remains challenging due to the unique pharmacological profiles and side effects of available drugs. This scoping review aims to provide a comprehensive analysis of the pharmacological agents used for procedural analgosedation in pediatric emergency settings, focusing on their efficacy, safety, administration routes, and potential side effects. A systematic review of the literature was conducted, focusing on key agents such as ketamine, midazolam, dexmedetomidine, fentanyl, and nitrous oxide. Studies were included based on their relevance to pediatric procedural sedation, particularly in emergency settings. Literature analysis showed that ketamine and fentanyl are effective for managing moderate to severe pain, with a rapid onset of action. Fentanyl is preferred for acute pain management following fractures and burns, while ketamine and midazolam are commonly used for emergency analgosedation. Dexmedetomidine, which induces sedation similar to natural sleep, is particularly effective in preventing pain and agitation during procedures and is well tolerated in children, especially those with developmental disorders. Nitrous oxide, when used in a 50% oxygen mixture, offers a valuable option for conscious sedation during mildly to moderately painful procedures, maintaining respiratory and airway reflexes. No single drug is ideal for all pediatric patients and procedures and the choice of agent should be tailored to the specific clinical scenario, considering both the sensory and affective components of pain. Future research should prioritize large-scale comparative studies, the exploration of combination therapies, and the development of non-pharmacological adjuncts to enhance the safety and efficacy of pediatric analgosedation.

Semiconductor WO3 thin films deposited by pulsed reactive magnetron sputtering

A pulsed reactive magnetron sputtering system with a tungsten target and a gas mixture of argon and oxygen was investigated as a source for the deposition of semiconductor WO3 thin films on soda lime glass substrates and on the glass with transparent conductive SnO2:F (FTO) electrode. The reactive sputtering process was performed in HiPIMS mode with low pulse repetition frequency fp ≈ 50–100 Hz and short pulse duration in HiPIMS discharge Ton = 100 μs. The second mode investigated was the mid-frequency (MF) magnetron discharge with pulse frequency fp = 40 kHz and pulse length Ton = 15 μs. The plasma parameters were investigated for both HiPIMS and MF modes using the planar RF probe operating at the frequency fprobe = 350 kHz and the grid QCM with biased collector electrode. Ion density ni and tail electron temperature (Te) were determined in both pulsed reactive magnetron sputtering discharge modes with time resolution. The maximum value ni ≈ 5 · 1017 m−3 was found in the reactive HiPIMS mode, and the maximum value ni ≈ 7 · 1016 m−3 was found in the reactive MF (40 kHz) mode. The degree of ionization of sputtered particles in reactive HiPIMS was determined for different values of (QO2) and was found to be in the range of ri ≈ 0.1–0.3. The deposition rate determined by QCM in reactive HiPIMS was practically independent on (QO2), but in the case of reactive MF, the measured deposition rate decreased significantly with increasing (QO2). The WO3 films deposited in both modes have a predominantly monoclinic crystal structure. The light and dark conductivity and the light/dark conductivity ratio (Ld) were measured under dark conditions and UV light illumination. At higher (QO2), the maximum value of Ld ≈ 300 was found for MF deposited WO3 and the maximum value of Ld ≈ 30 was found for HiPIMS deposited WO3. The photoelectrochemical measurement of WO3 deposited on FTO electrodes confirmed the n-type conductivity, and these films functioned as photoanodes in photoelectrochemical cells. MF deposited WO3 films systematically exhibited slightly higher photocurrents than HiPIMS deposited WO3. It was shown that these optimum photocurrents for HiPIMS and MF were found at QO2 ≈ 80 sccm and could not be improved by further increasing of (QO2).

Effect of oxygen plasma treatment on the properties of ALD hafnium oxide films

In this work, we studied the effect of processing hafnium oxide samples prepared by atomic layer deposition in a gas discharge plasma of a mixture of argon and oxygen in a ratio of 1:10. It has been shown that such treatment preserves the amorphous structure of the film and reduces the content of oxygen vacancies in the film. This is important for the use of the film in the gate dielectric of a transistor. Processing in plasma leads to a change in its properties, namely: an increase in density and refractive index, as well as a decrease in the intensity of emission bands that are associated with an oxygen vacancy. The plasma temperature and ion energy were determined from the argon emission spectra. The activation energy for the diffusion of oxygen ions in hafnium oxide films has been calculated to be 0.43 eV.

Direct One-Stage Plasma Chemical Synthesis of Nanostructured Thin Films of the System β-Ga<sub>2</sub>O<sub>3</sub>-GaN of Different Composition

For the first time, nanostructured thin films of the β-Ga2O3−GaN system were obtained by plasma chemical deposition from the gas phase (PECVD) on c-sapphire substrates. High-purity metallic gallium, as well as high-purity gaseous nitrogen and oxygen were used as sources of macro components. The low-temperature nonequilibrium plasma of an inductively coupled HF (40.68 MHz) discharge at a reduced pressure (0.01 Torr) was the initiator of chemical transformations between the starting substances. A mixture of oxygen and nitrogen was used as a plasma-forming gas. The plasma chemical process was studied using the optical emission spectroscopy (OES) method. The obtained thin films of the β-Ga2O3−GaN system with a GaN phase content of 2 to 7% were characterized by various analytical methods.

Effect of ultrahigh frequency ozone therapy on oxidative metabolism in the blood of rats with ischemic skin flaps: A preclinical experimental randomized study

Background. Maintaining and restoring skin microcirculation in surgical flaps, as well as accelerating rehabilitation after skin flap transplantation, in order to mitigate the consequences of burns and injuries, remain a pressing issue. In addition to various timings and techniques for plastic surgery, physiotherapeutic approaches prove to be efficient and include low-intensity electromagnetic radiation in millimeter waves as their prominent techniques. In recent years, experts have paid an increasing attention to the application of low-intensity electromagnetic radiation across different frequency ranges for the enhancement of microcirculation in patients after surgical correction of burn consequences. However, this approach is yet to be further validated. Objective. To investigate the effect of different combinations of ultrahigh frequency electromagnetic radiation with ozone therapy on the oxidative metabolism of blood in rats using a model of ischemic skin flaps. Methods. A preclinical experimental randomized study was conducted on 100 adult male Wistar rats weighing between 200 and 250 grams. Five equal-sized groups of animals were formed in the study: Group 1: intact (no interventions), and Groups 2, 3, 4, and 5: after surgical intervention (modeling of ischemic skin flaps). Animals in Group 2 (control group) received no therapeutic procedures. Rats in Groups 3 and 5 underwent a 10-minute course of electromagnetic radiation exposure with a dose of 0.06 mJ for seven days. Animals in Group 3 were exposed to electromagnetic radiation of ultrahigh frequency with a range of 53–78 GHz. Animals in Group 4 received injections of ozonized saline solution (with a saturating ozone concentration in the ozonized oxygen mixture of 3000 µg/L) daily for 7 days, administered intraperitoneally at a volume of 1 mL. Group 5 underwent a combined treatment: daily exposure to ultrahigh frequency electromagnetic radiation along with intraperitoneal ozone therapy (the application modalities of these treatments were similar to those used in Groups 3 and 4, respectively). The intensity of lipid peroxidation, peroxide resistance in erythrocytes, and overall antioxidant system activity were assessed in order to investigate the balance of pro- and antioxidant systems in plasma and erythrocytes. Additionally, the study involved determination of the level of malondialdehyde content and evaluation of the activity of superoxide dismutase and catalase in erythrocytes. The obtained date were analyzed, using MS Office 2013 (Microsoft Corporation, USA) and Statistica 10 (StatSoft, USA). Results. The conducted analysis revealed an antioxidant effect from ultrahigh frequency electromagnetic radiation, with this effect being enhanced by ozone therapy. In addition, the study detected the inhibition of free radical oxidation under the ultrahigh frequency electromagnetic radiation and ozone therapy. Conclusion. Thus, the positive effects of the studied therapeutic factors manifest at the systemic level, as evidenced by the optimization of biochemical parameters and indicators of oxidative metabolism in the plasma of animal blood. It has been established that ultrahigh frequency electromagnetic radiation, administered in a noise mode, exerts a regulatory effect on pro- and antioxidant systems in the body, as demonstrated in a model of transplanted skin flap. This intervention leads to a reduction in the severity of oxidative stress and an enhancement of antioxidant reserves in the blood. The observed effect is further amplified with the additional application of ozone therapy.

Impact of DBD Plasma Jet Treatment on the Enamel Surface of Primary Teeth.

The impact of cold atmospheric plasma (CAP) treatment on the enamel of twelve primary teeth (incisors, canines, and molars) collected from six children was examined in order to evaluate the possibility of using the CAP technique in dental applications. A radio-frequency dielectric barrier discharge (DBD) plasma jet operating at a voltage of 3.25 kV using a mixture of helium and oxygen as the working gas was used for the generation of plasma as part of the electro-technological method for the treatment of biological material. The plasma exposure time for the primary teeth was 5, 10, and 20 min. The properties of tooth enamel (color, contact angles, surface roughness, surface topography, elemental composition) were examined before (control) and after the plasma treatment. As shown by the results, the plasma treatment time is a key parameter that can induce desired features, such as whitening or improved wettability. However, with prolonged plasma treatment (20 min), the enamel surface may be permanently damaged. The cold-plasma-treated samples were characterized by a higher value of the brightness L* parameter and thus a lighter color, compared to the CAP-untreated teeth. It was also evidenced that the plasma treatment increased the hydrophilicity of tooth surfaces, and the contact angles effectively decreased with the time of the CAP treatment. The tooth surface also became much more heterogeneous and rough with much greater amplitudes in heights. The surface of the primary teeth after the CAP treatment lost its homogeneity, as evidenced by the SEM micrographs. The analysis of the elemental composition revealed only minor changes after the plasma process, which may suggest that the observed morphological changes in the enamel surface are mainly physical and are not a consequence of chemical reactions between the enamel and the reactive components of the cold plasma. Plasma treatment of teeth opens up new possibilities of using this method as an alternative to whitening or pre-treatment before other dental procedures.

The effect of porous non-metallic balls on detonation propagation in hydrogen–oxygen mixtures

In this study, the influence of porous non-metallic balls on the dynamics of detonation propagation in hydrogen–oxygen mixtures is studied in stainless steel tubes with square cross-sections. The effect of the length and thickness of the balls is considered in detail. Four pressure transducers are used to record the detonation time-of-arrival, and the average velocity of detonation propagation is calculate. The smoked foil technique is performed to register the detonation cellular structures. The results indicate that increasing the filling length and thickness of the balls leads to a significant increase in velocity loss, critical pressure, and re-initiation distance during detonation propagation. Two propagation modes are observed near the critical pressure. In sub-critical mode, the detonation wave is attenuated and failed eventually, propagating to the end of the tube in the form of a low-speed deflagration wave. In super-critical mode, the detonation propagation can be promoted by inducing a vertical transverse wave generated by the detonation wave passing through a group of small balls. It is worth noting that the increase in filling thickness of the small balls leads to a greater velocity loss compared to the increase in filling length. However, an increase in the filling length will cause the detonation wave to undergo a longer and more sustained weakening process as it passes through the small balls, thereby resulting in a longer re-initiation distance and a lower average velocity over a short distance after re-initiation. By increasing the filling length of the small balls to 312 mm, the transition of the detonation wave from multi-head detonation to double-head detonation can be observed, and then successfully turns into stable detonation. However, when filling double-layer small balls, even in super-critical conditions, the attenuated detonation wave cannot achieve re-initiation over a short distance.

Formation of Active Particles in Methane, Nitrogen, and Oxygen Mixtures under Simultaneous Action of an Electric Field and an Electron Beam

Formation of Active Particles in Methane, Nitrogen, and Oxygen Mixtures under Simultaneous Action of an Electric Field and an Electron Beam

Research on the initiation and wavefront evolution of diverging cylindrical detonations of acetylene and oxygen mixtures

The present study focuses on fundamental research about the transition from a planar detonation to a cylindrical detonation and the propagation of the diverging cylindrical detonation. We aim to figure out the mechanism of the transition and propagation of the diverging cylindrical detonation by analyzing the cellular pattern and critical initial pressure. The findings highlight that the successful detonation in a cylindrical chamber via transition through a straight channel is predominantly influenced by diffraction at the corners and the successive continuous reflections between the front and rear walls. Depending on the initial pressure, the initiation modes exhibit characteristics of subcritical, critical, and supercritical three-stage processes. Sustained propagation of cylindrical detonations necessitates increasing the number of cells to match the growth rate in the front region. Experimental investigations reveal two distinct modes of cell number increase: mild and violent. In the case of the former, cell number increase predominantly occurs on a scale of two to three times the characteristic cell size of the Chapman-Jouguet detonation. In contrast, a decaying Mach stem undergoes twisting and evolves into local kinks, leading to the development of new triple-wave points. The latter mode typically occurs near the limit, where cell increase primarily arises from randomly occurring local explosions, and operates on a scale of ten times the characteristic cell size or the chamber diameter. In addition, a numerical study of two-dimensional fundamental problems abstracted from the experiment is conducted to help interpret experimental results and reveal more about the physics of the problem.

Outcomes of heliox use in children with respiratory compromise: A 10-year single institution experience.

Heliox, a mixture of helium and oxygen, has been shown to improve laminar airflow and decrease airway resistance in children. This study aims to describe the outcomes of heliox use in children with respiratory compromise and to identify variables associated with a need for airway surgical intervention. A retrospective cohort study of patients who received heliox between 2012 and 2022 at a tertiary care children's hospital. A hundred and thirty-eight heliox treatments were recorded in 119 children. Twelve patients were excluded. Most (n = 100, 84%) patients had significant comorbidities. On average, patients spent a cumulative mean of 94 ± 187 h on heliox therapy per hospital admission. Patients with croup or asthma without known airway pathology presented at an older age than patients with other indications for heliox therapy (4.0 ± 4.7 vs. 2.2 ± 3.6 years, p = 0.04) and were significantly less likely to have background diseases (n = 14, 52% vs. n = 74, 93%, p < 0.0001). Overall, 51 (47.7%) patients were recommended tracheostomy placement, airway reconstruction, or palliative care. Cumulative use of heliox for more than 47 h was associated with an increased risk of needing tracheostomy or airway reconstruction (odds ratio 6.2, 95% confidence intervals 2.56-14.13, p < 0.0001). In multivariable regression analysis, neuromuscular disease, intracranial neuropathology, and cumulative time of heliox were associated with a need for definitive airway intervention. Heliox may be used as a temporizing agent in children with upper airway obstruction. The effectiveness of heliox use for more than 47 h in children, especially in the presence of neuromuscular disease and intracranial neuropathology should be reconsidered.Level of evidence: 4.

Sustenance of hydrogen–oxygen cellular detonation with ozone additions in confined space

The sustenance of cellular detonation under weak confinement is studied through two-dimensional (2D) numerical simulations of hydrogen–oxygen mixtures surrounded by inert gas. The results show that in the weakly confined space, the cellular detonation with Chapman-Jouguet velocity can survive by increasing the width of the reactant layer and enhancing the reactivity of reactants, which ensures enough triple points and high reactivity in the reactant layer for detonation sustenance since transverse shocks cannot be regenerated and reinforced by boundary reflection. By adding ozone into the system and changing the width of the reactant layer, the relationship between induction length and detonation sustenance is established. It is found that the sustenance of cellular detonation in the weakly confined space is related to the ratio of the reactant layer width to the induction length. Ozone reactions can reduce the induction length and enhance reactivity, thereby promoting the generation of new transverse shocks and significantly improving the sustenance of cellular detonation in weakly confined space.

The starting temperature of high-flow nasal cannula and perceived comfort in critically ill patients: A pragmatic randomized controlled trial.

High-flow nasal cannula (HFNC) therapy is a non-invasive respiratory treatment characterized by high tolerability, which largely derives from the patient's comfort. The primary aim of this study was to explore whether the patient's perceived comfort was the same regardless of different approaches used to reach the target humidification temperature. The secondary aim was to assess the patient's perceived nasal dryness and humidity. This single-centre, pragmatic, randomized trial was registered at clinicaltrials.gov (NCT05688189). Patients in the intensive care unit (ICU) in need of HFNC therapy were randomly assigned to one of three study arms: a two-step increase (31 to 34 to 37°C), a one-step increase in temperature (34-37°C) or no temperature increase (started and remained at 37°C). The patients were asked to rate their perceived comfort, as well as their perceived nasal dryness and humidity on a scale from 1 (lowest value) to 5 (highest value). We enrolled 21 patients, aged 34-85 years. The mean (±1 standard deviation) comfort level was 3.3 (1.3) for patients who received a one-step increase, 3.1 (1.3) for those who received no increase and 2.7 (1.7) for those who received a two-step increase (p = .714). There was also no difference in nasal dryness (p = .05) or humidity (p = .612) across the study arms. Greater comfort was fairly correlated with less nasal humidity (ρ = -0.34, 95% confidence interval -0.68 to 0.07) but not with nasal dryness (ρ = 0.01, p = .94). After 30 min of HFNC therapy at a target temperature of 37°C, overall comfort was rated similarly in the three study arms. Additional studies are needed to accumulate evidence corroborating the findings of this study. The temperature of the mixture of air and oxygen is a fundamental component of HFNC therapy. A pragmatic approach irrespective of the initial temperature setting seems to yield a similar comfort score in hospitalized patients with mild respiratory failure because of extrapulmonary causes.

The Influence of Fuel Type on MotorcycleVehicle Exhaust Emission Tests

A vehicle engine's performance can be determined through exhaust emission tests. Exhaust emissions contain air pollutants that result from incomplete fuel combustion in the vehicle's combustion chamber. This is usually due to improper oxygen and air mixture conditions. Gasoline (CxHy) burns and reacts with oxygen (O2) to produce carbon dioxide (CO2), water (H2O), as well as non-toxic gases like nitrogen (N2) and water vapor (H2O (g)). However, it also generates toxic gases such as CO, HC, and Nitrogen Oxides (NOx). Motorcycle exhaust emission tests are commonly conducted using a gas analyzer. In this study, a gas analyser was used to measure the amount of CO, CO2, HC, O2, and NOx emitted from motorcycle exhausts. The tests were carried out using the Vario 160 ABS motorcycle with different types of fuel: RON 92 (S), RON 92 (P), RON 90, RON 98, and RON 92 (R). The data was collected at idle, as well as at 1600 rpm, 1800 rpm, and 2000 rpm. Three measurements were taken for each variable, and the average was calculated. The results showed that RON 98 fuel resulted in better combustion compared to RON 90 and RON 92, as indicated by the CO2 content at idle, which was 13.95%. Additionally, when the motorcycle's engine was throttled, RON 98 fuel did not produce any NOx. The study also revealed that RON 92 (S) fuel led to better combustion compared to both of RON 92 (P) and RON 92 (R), as evidenced by the CO content of 0.05%, CO2 content of 13.63%, HC content of 204 ppm, O2 content of 0.03%, and NOx content of 4 ppm at idle.

Экспериментальные исследования горения смесей водорода, кислорода и азота в частично ограниченном пространстве

Experimental studies of the peculiarities of combustion of hydrogen, oxygen, and nitrogen mixtures in a partially confined space when changing the space limitation within the wide range from 12 to 81 % of the total space, e.g., premises, industrial sites, or stands where hydrogen and oxygen spills or their discharge in a gaseous state are potential, have been carried out. The experiments have been conducted on a stand with hydrogen and oxygen mixtures containing nitrogen 2Н2 + О2 + 2N2 and hydrogen and oxygen mixtures 2Н2 + О2. According to the results of the studies, partial limitation of the space does not significantly affect the combustion rate of such mixtures. At the same time, during combustion in a partially confined space, the pressure in the compression wave increases compared to the pressure in a free space. Increasing the space limitation during ignition caused pressure rise in the mixture compression waves. During the tests with 2Н2 + О2 + 2N2 with one wall of the stand space limitation, at the ignition of the mixture, pressure sensors placed opposite the wall registered, on average, a 50 % higher pressure compared with the sensors facing the open space. These sensors showed the same pressure values as for the mixture combustion in a free space. The increase of the installation space limitation with three walls during ignition led to further pressure rise in a partially confined space. The same effect has been registered for 2Н2 + О2 mixtures. During the experiments, the limitation of the installation’s free space with only one wall caused the double rise of blast wave compression pressure compared with experiments without a wall. The results of studies confirm that with the increase of the stand space limitation, the mixture ignition pressure increases, which is conditioned by the interaction of falling and reflected waves.

Low-emission hydrogen production from gasification of Australian coals – Process simulation and technoeconomic assessment

Although renewable energy-based technologies such as water electrolysis and biomass gasification for hydrogen production are cleaner than fossil energy-based routes, there are still prevailing challenges associated with the high cost and operational challenges in the scale-up of those technologies in the short term. Considering the abundance of coal as a current primary source of energy in Australia, the use of coal to produce hydrogen is not only in line with Australia's resource endowment but is also expected to become a supplement to the other hydrogen production pathways during the global energy transition period. This paper presents a comprehensive techno-economic assessment of low-emission hydrogen production from Australian coal gasification integrated with carbon capture and storage (CCS). The study explores four cases of hydrogen production, comparing Australian brown coal (Victorian brown coal) and black coal (Queensland black coal) gasification. Variations in gasifiers, gasification agents, and associated operating conditions contribute to differences in energy efficiency, costs, and CO2 emissions among the cases. The findings reveal a levelized cost of hydrogen from coal gasification ranging between A$4.12–4.90 per kg of hydrogen. Notably, entrained flow gasification of Victorian brown coal in a mixture of oxygen and steam environment demonstrates advantages under the current market conditions. However, less mature technologies like dual fluidized bed gasifiers could emerge as viable alternatives if deployed on a commercial scale. The study also addresses direct carbon emissions from the process, indicating a CO2 emission intensity range of 16.3–20.9 kg CO2/kg H2 without CCS and 0.1–1.1 kg CO2/kg H2 with CCS for the four cases. These insights contribute valuable information for decision-making in the pursuit of sustainable and economically feasible hydrogen production methods during the ongoing energy transition.

Neural network-assisted emission spectra analysis of gases using MEMS sensor: Predicting chemical composition and pressure

The paper explores the potential use of neural networks to predict the chemical composition as well as the total and partial pressure of individual gases in the mixture based on their emission spectra. Excitation/ionization of gas particles is ensured by a miniature MEMS (micro-electro-mechanical) sensor. The impact of measurement conditions on the generated spectra and possible challenges in analysis are addressed. The trained neural networks achieved a mean absolute error of approximately 1.4% in determining the chemical composition of a mixture of methane and hydrogen and 0.8% for a mixture of nitrogen and oxygen. For pressure prediction, spanning several orders of magnitude, a general model predicting pressure for ten different gases achieved a relative mean absolute error of 4.5%. Additionally, a model for gas classification achieved an accuracy of over 99%.

Long-term hypothermic storage of oocytes of the European common frog Rana temporaria at various pressure regimes in gas mixtures based on oxygen, carbon monoxide, and nitrous oxide

In recent years, the challenge of preserving amphibian biodiversity has increasingly been addressed through technologies for the short-term storage of unfertilized spawn at low positive temperatures. Previously the possibility of using a 6.5 atm gaseous mixture of carbon monoxide and oxygen for prolonged hypothermic preservation of unfertilized oocytes for more than 4 days was shown. This study aimed to investigate the viability of oocytes R. temporaria preserved under conditions of hypothermia at 2.5, 3 and 6.5 excess atm pressure in the various gas mixture compositions (CO, N2O, O2) and pure oxygen. The use of pressure up to 3 excess atmospheres was significantly beneficial compared to 6.5 atm at the 7 days storage period. The results indicate that oxygen pressure is a critical factor in maintaining oocyte viability. Admixing CO or N2O to oxygen reduced variability in the results but did not significantly affect the measured indicators (fertilization, hatching) in the experimental groups. The composition CO + O2 (0.5/3.5 ratio, 3 excess atm) reliably extended the shelf life of viable oocytes, indistinguishable from native controls by fertilization and hatching rates, to 4 days. After 7 days, oocytes exhibited fertilization and hatching rates that were 79 % and 48 % compared to native control. Reducing the pressure of the preserving gas mixture to 3 atm, as utilized in this study, simplifies the practical implementation of gas preservation technology for maintaining endangered amphibian species during breeding in laboratory conditions.

Adaptive generic model control scheme for an optimized external heat integrated air separation column using unscented kalman filter

An External Heat-Integrated Air Separation Column (E-HIASC) process is a promising air separation technology. This study focuses on the operational stability of the optimized E-HIASC process for separating nitrogen, oxygen, and argon mixtures. The operation stability of process is achieved through an Adaptive Generic Model Control (AGMC) scheme which is designed by incorporating the identified E-HIASC state-space dynamic model into the controller algorithm. The controller synthesizes the Generic Model Control (GMC) algorithm, decoupled ARX model, and Unscented Kalman Filter (UKF) algorithm to enable the auto-regression and exogenous (ARX) for model identification and the UKF algorithm to estimate time-varying parameters and compute unmeasured E-HIASC state parameters required in the GMC algorithm. A Generic Model Control (GMC) and Multivariable PID (M-PID) control schemes were also designed for benchmarking study. Simulation results show that an AGMC scheme performs better than the GMC and M-PID schemes in tracking the product concentration set point and disturbances rejection.

Quantification of O2 Crossover and Concurrent Faradaic Efficiency Loss of H2 Production Via PEM Water Electrolysis

PEM water electrolyzers (PEMWEs) are considered to be a key technology for the decarbonization of major sectors by being able to store fluctuating renewable energy as chemical energy in the form of hydrogen gas. While the scarcity of the necessary iridium catalyst on the anode limits widespread application minding the high loadings still needed today,1 there are additional efficiency losses that are still to be fully understood.By employing a proton exchange membrane, PEMWEs are able to produce hydrogen at elevated pressure on the cathode while keeping the balance of plant costs low as the anode can still be operated with liquid water at close to ambient pressure. Hydrogen crossover to the anode compartment through the membrane is significantly increased at elevated cathode pressures, which is majorly considered a safety issue. As the anode catalyst does not serve as a good hydrogen oxidation reaction catalyst, explosive mixtures of hydrogen and oxygen can form at the anode (and its exhaust) depending on the membrane type and thickness, current density, temperature, hydrogen partial pressure at the cathode, cathode catalyst layer structure etc.2-4 Aside of safety concerns – which can be bypassed by the use of recombination interlayers in the membrane5 – gas crossover also reduces the Faradaic efficiency of the system as parts of the hydrogen produced cannot be used further because it does not reach the cathode exhaust.A so far not majorly considered additional Faradaic efficiency loss stems from oxygen crossover from the anode to the cathode. As the platinum based cathode catalyst is very active for the oxygen reduction reaction, basically all of the oxygen crossing over to the cathode compartment recombines with the hydrogen present, forming liquid water.6 The permeability of oxygen through common PEM materials is significantly lower than that of hydrogen.7 But due to the osmotic drag from the anode to the cathode as well as possibly high bubble pressures of oxygen at the anode catalyst layer / membrane interface,8 oxygen crossover deserves closer attention.In this study we show quantification of the oxygen crossover in operating PEMWE single cells by a full balance of the gases detected at both the anode and cathode exhaust using an online mass spectrometer. A direct correlation of Faradaic efficiency of the oxygen and hydrogen produced matches the expected chemical recombination on the cathode, which serves as a direct measure of the oxygen crossover to the cathode compartment during PEMWE operation. Depending on the exact operating conditions the Faradaic efficiency loss caused by oxygen crossover can easily be in the percentage range, stressing the importance of having a closer look at the oxygen crossover characteristics of PEMWE cells in order to improve the Faradaic efficiency of the system. Taie, Z.; Peng, X.; Kulkarni, D.; Zenyuk, I. V.; Weber, A. Z.; Hagen, C.; Danilovic, N., Pathway to Complete Energy Sector Decarbonization with Available Iridium Resources using Ultralow Loaded Water Electrolyzers. ACS Appl Mater Interfaces 2020, 12, 52701-52712.Bernt, M.; Schröter, J.; Möckl, M.; Gasteiger, H. A., Analysis of Gas Permeation Phenomena in a PEM Water Electrolyzer Operated at High Pressure and High Current Density. J. Electrochem. Soc. 2020, 167.Ito, H.; Miyazaki, N.; Ishida, M.; Nakano, A., Cross-permeation and consumption of hydrogen during proton exchange membrane electrolysis. Int. J. Hydrogen Energy 2016, 41, 20439-20446.Trinke, P.; Keeley, G. P.; Carmo, M.; Bensmann, B.; Hanke-Rauschenbach, R., Elucidating the Effect of Mass Transport Resistances on Hydrogen Crossover and Cell Performance in PEM Water Electrolyzers by Varying the Cathode Ionomer Content. J. Electrochem. Soc. 2019, 166, F465-F471.Zhang, Z.; Han, Z.; Testino, A.; Gubler, L., Platinum and Cerium-Zirconium Oxide Co-Doped Membrane for Mitigated H2 Crossover and Ionomer Degradation in PEWE. J. Electrochem. Soc. 2022, 169.Schalenbach, M.; Carmo, M.; Fritz, D. L.; Mergel, J.; Stolten, D., Pressurized PEM water electrolysis: Efficiency and gas crossover. Int. J. Hydrogen Energy 2013, 38, 14921-14933.Schalenbach, M.; Hoefner, T.; Paciok, P.; Carmo, M.; Lueke, W.; Stolten, D., Gas Permeation through Nafion. Part 1: Measurements. The Journal of Physical Chemistry C 2015, 119, 25145-25155.Weber, C. C.; Wrubel, J. A.; Gubler, L.; Bender, G.; De Angelis, S.; Buchi, F. N., How the Porous Transport Layer Interface Affects Catalyst Utilization and Performance in Polymer Electrolyte Water Electrolysis. ACS Appl Mater Interfaces 2023, 15, 34750-34763.

Conscious Sedation Using Nitrous Oxide and Midazolam for Dental Procedures in Pediatric Patients in Armed Forces Hospital – Our Experience

Abstract Background and Aim: Management of pain and anxiety associated with dental procedures in pediatric age group is a big challenge. In this part of the world, counselling has been the main modality for managing such patients. It is associated with mixed outcome. We share our experience of managing 23 patients using a combination of inhalational nitrous oxide- oxygen and intravenous midazolam with satisfactory outcomes. Material and Methods: Patients aged more than six years, American society of anaesthesiologists classification (ASA) I or II, procedure that could be finished within one hour like pulpectomies, root canal treatments, extraction and multiple restorations were accepted for conscious sedation. Complete blood count was done and pre-anaesthetic checkup (PAC) with written informed consent from the parent was taken for the dental procedure under conscious sedation. We placed the nasal mask of the Conscious sedation anesthesia machine and made the child inhale Oxygen/Nitrous oxide mixture. After inhaling variable concentration of nitrous oxide/ oxygen mixture in proportion increasing from 30:70 to 70:30, procedure was done. After completion of the procedure, the patient was administered hundred percent oxygen for five minutes. Results: We have done a total of twenty-three cases till now with ages between five to seventeen years. The duration of procedures ranged from 30 min to one and half hour. Two patients less than six years were found to be uncooperative for the procedure. Conclusion: Minimum age group that was suitable for conscious sedation was six years and above. Frequent meetings and counselling by the same team should be facilitated prior to taking up for the procedure.