Excess Gas Research Articles

A review on the mechanical and biocorrosion behaviour of iron and zinc-based biodegradable materials fabricated using powder metallurgy routes

Abstract Over the past two decades, research on alloys and composites based on Mg, Fe, and Zn has focused on biodegradable orthopaedic implants. Mg-based materials face issues like excessive corrosion rates and hydrogen gas evolution, while Fe and Zn-based materials show lower corrosion rates. However, these rates are slower than the optimal rate, which can be modified using powder metallurgy (PM) manufacturing. The PM process offers precise control over porosity distribution which in turn affects the mechanical and corrosion properties of the fabricated specimen. The highest rate of corrosion i.e. 0.944 mmpy was observed with the alloying of 2 wt% Pd in Fe and by using conventional sintering technique. Similarly, Zn-based samples fabricated by conventional sintering was found to exhibit higher corrosion rate as compared to microwave and spark plasma sintered specimen. PM-fabricated Fe and Zn-based bone scaffolds have been investigated for in-vitro corrosion and osseointegration. A higher porosity in the Fe and Zn scaffolds (>60 %) resulted in high corrosion rate which adversely impacted the cell proliferation. This timely review critically assessed PM-fabricated Fe and Zn-based materials that have the potential to transform regenerative medicine and patient care by redefining the field of biodegradable implants.

Multiphysics Field Coupled to a Numerical Simulation Study on Heavy Oil Reservoir Development via Electromagnetic Heating in a SAGD-like Process

Conventional thermal recovery methods for heavy oil suffer from significant issues such as high water consumption, excessive greenhouse gas emissions, and substantial heat losses. In contrast, electromagnetic heating, as a waterless method for heavy oil recovery, offers numerous advantages, including high thermal energy utilization, reduced carbon emissions, and volumetric heating of the reservoir, making it a focus of recent research in heavy oil thermal recovery technologies. This paper presents a numerical simulation study of electromagnetic heating for heavy oil recovery, using a heavy oil block in the Bohai Bay oilfield in China as a case study. Firstly, a multiphysics field coupled to a mathematical model was established, considering the impact of the temperature on the heavy oil viscosity, the threshold pressure gradient of non-Darcy flow, and the dielectric properties of the reservoir, along with heat dissipation from overlying and undercover sandstone and gravitational effects on fluid flow. Secondly, a numerical simulation method for the coupled multiphysics fields was developed, and the convergence and stability of the numerical simulation method were tested. Finally, a sensitivity analysis based on the numerical simulation results identified the factors affecting heavy oil production. It was found that electromagnetic heating significantly enhances heavy oil production, and the threshold pressure gradient greatly influences the prediction of heavy oil production. Moreover, heat dissipation from the overlying and undercover sandstone severely reduces cumulative oil production. When the production well is located below the electromagnetic heating antenna, larger well spacing results in higher cumulative heavy oil production. Higher heavy oil production is achieved when the antenna is positioned at the center of the reservoir for the studied cases. Power has a big effect on increasing heavy oil production, but its influence diminishes as power increases. There exists an optimal range of electromagnetic frequencies for maximum cumulative production, and higher water saturation leads to poorer electromagnetic heating efficiency. This study provides a theoretical foundation and technical support for the numerical simulation technology and development plan optimization of heavy oil reservoirs subjected to electromagnetic heating.

Pre-treated municipal solid waste bottom ash as alkali-activated mortar precursor

Pre-treated incinerator bottom ash was used as a precursor of alkali-activated mortars. Control mortars were produced using coal fly ash. Different combinations of alkaline activator were tested (sodium oxide/binder ratio (4%, 6%, 8%, 10% and 15%) and silicon dioxide/sodium oxide ratio (0, 0.5, 1.0, 1.5 and 2.0)) and the influence of these on the mortar's mechanical performance was evaluated. The mortars were tested in both fresh (for density and workability) and hardened states (for dry density, compressive and flexural strengths and modulus of elasticity) after 7, 28, 91 and 182 days. The first stage of work was precursor pre-treatment in a sodium hydroxide solution to prevent the expansion of fresh specimens due to the reaction of aluminium with the alkaline activator. The pre-treatment was effective in preventing excessive hydrogen gas generation during setting, leading to dimensional stability and improved strength. Different optimum sodium oxide contents were observed after 28 days (i.e. 15% for fly ash specimens and 8% for bottom ash specimens). The results of a simplified life-cycle assessment showed that such mixes exhibited lower overall carbon dioxide emissions when compared with cement-based counterparts. However, this trend was reversed with increasing contents of sodium hydroxide and sodium silicate.

Machine learning-based phenogroups and prediction model in patients with functional gastrointestinal disorders to reveal distinct disease subsets associated with gas production.

Symptom-based subtyping for functional gastrointestinal disorders (FGIDs) has limited value in identifying underlying mechanisms and guiding therapeutic strategies. Small intestinal dysbiosis is implicated in the development of FGIDs. We tested if machine learning (ML) algorithms utilizing both gastrointestinal (GI) symptom characteristics and lactulose breath tests could provide distinct clusters. This was a prospective cohort study. We performed lactulose hydrogen methane breath tests and hydrogen sulfide breath tests in 508 patients with GI symptoms. An unsupervised ML algorithm was used to categorize subjects by integrating GI symptoms and breath gas characteristics. Generalized Estimating Equation (GEE) models were used to examine the longitudinal associations between cluster patterns and breath gas time profiles. An ML-based prediction model for identifying excessive gas production in FGIDs patients was developed and internal validation was performed. FGIDs were confirmed in 300 patients. K-means clustering identified 4 distinct clusters. Cluster 2, 3, and 4 showed enrichments for abdominal distention and diarrhea with a high proportion of excessive gas production, whereas Cluster 1 was characterized by moderate lower abdominal discomforts with the most psychological complaints and the lowest proportion of excessive gas production. GEE models showed that breath gas concentrations varied among different clusters over time. We further sought to develop an ML-based prediction model to determine excessive gas production. The model exhibited good predictive capabilities. ML-based phenogroups and prediction model approaches could provide distinct FGIDs subsets and efficiently determine FGIDs subsets with greater gas production, thereby facilitating clinical decision-making and guiding treatment.

A numerical model for evaluating the long-term migration and phase transition behavior of foam-assisted injection of CO2 in saline aquifers

Geological Carbon Storage (GCS) is a rapidly developing technology with the potential to mitigate the environmental impact of excessive greenhouse gas emissions. Foam-assisted injection of CO2 can effectively alter fluid rheological properties, thereby enhancing sweep efficiency. In this paper, a numerical model to evaluate the long-term migration behavior of foam-assisted injected CO2 in saline aquifers is developed. It is found that foam-assisted injection improves storage efficiency and reduces the plume migration distance compared to direct CO2 injection. This creates higher demands on the injection pressure but minimizes the risk of leakage. The effects of injection strategy, volume fraction of foam, and reservoir heterogeneity were investigated. Modeling results show that the injection strategy with a high foam volume fraction enhances the sweep efficiency and improves the transition rate of injected CO2 to the dissolved state. This can effectively enhance the long-term security of the sequestration. Simulations of layered formations indicates that foams can potentially inhibit the rapid migration of plumes along high-permeability zones. Our study provides insights for foam-assisted injection to enhance reservoir storage efficiency and long-term safety for GCS.

Закономерности износа плазмотронов при плазменной резке толстолистового проката на токе обратной полярности

The introduction describes the features of the process of plasma cutting of various metals and alloys using reverse-polarity plasma torches with and the features of cutting thick sheets. The purpose of the work is to study the wear process of plasma torches operating on reverse polarity current when cutting thick rolled sheets of aluminum and titanium alloys. Research methods include optical and scanning electron microscopy, filming of the cutting process and visual inspection of plasma torch elements after receiving specimens. Results and discussion. The section shows the appearance of the main working elements of the plasma torch after cutting in various modes, which led to both stable and gradual wear and to catastrophic failure of the plasma torch. The results of structural studies of the main characteristic zones of nozzles and electrodes after cutting are presented. The studies carried out made it possible to establish the main reasons for the failure of the working elements reverse-polarity plasma torches. The causes of catastrophic failure of plasma torches include failure to maintain the gap between the nozzle and the electrode and melting of the channel of gas supply into the discharge chamber. The wear of nozzles and electrodes in a stable mode can be intensified due to abnormal operation of the starting arc, the presence of manufacturing inaccuracies and excess gas pressure. In conclusion, the main conclusions based on the results of the research are formulated. The process of wear of electrodes, nozzles and body elements of plasma torches during operation at high electric arc power values is described.

Productivity and Profitability of Diversified Legume-based Cropping Systems in the Indo-gangetic Plains of India as Influenced by Nutrient Management

Background: The continuing adoption of the rice-wheat cropping system (RWCS) and indiscriminate use of inorganic fertiliser has led to a decrease in soil fertility, an increase in multiple micronutrient deficiencies, a decrease in the water table and excessive greenhouse gas emissions, especially in the Indo Gangetic Plains. Adoption of crop diversification strategies, including legumes in cropping systems with integrated use of organic and inorganic nutrient sources, could be a viable option for achieving higher fodder tonnage and sustainable crop production in aforesaid ecologies. Methods: A field experiment was conducted during the kharif, rabi and summer seasons of 2018-19 and 2019-20 in a split-plot design comprising four cropping systems (CS) i.e., rice-wheat, rice-berseem, pearl millet-oats-moong bean and maize-cowpea-wheat in main plots; and four nutrient management (NM) practices i.e., 100% RDF (recommended dose of fertiliser), 100% RDF + cow urine (foliar spray), 100% RDF + PGPR (seed treatments) and 75% RDF + cow urine + PGPR were assigned in sub-plots with three replications of each treatment. Result: Investigations revealed that the significantly highest system productivity, net returns and higher nutrient availability were obtained under the rice-berseem cropping system with 100% RDF + PGPR treatment. The magnitude of increment in system productivity of the rice–berseem cropping system was 35.06, 57.87 and 87.29% over rice-wheat, maize-cowpea-wheat and pearl millet-oats-moong bean cropping system, respectively. The legume-based cropping system has strengthened and sustained crop productivity and profitability. The results of the present work confirmed that the adoption of legume-based crop diversification has significantly alleviated the crop yield of dairy-based farming systems.

A Field Experiment on Pro-Social Nudges: The Snowballing Problem

In contrast to traditional economic methods to address negative externalities, the study of pro-social nudges within the field of behavioral economics is quickly developing (Carlsson et al., 2019, 2021; Schubert, 2017). The aim of pro-social nudges is to reduce a negative externality to a defined group or community. This study uses a natural field experiment to examine the impact of a pro-social nudge on a local negative externality of hot rooms in college residence buildings and the resulting more global externality of excess greenhouse gas emissions. These externalities are the result of the interplay between the heating system and the propensity of students to open their windows causing the system to produce more heat to everyone––labeled the snowballing problem. This study suggests the nudge did not reduce the negative externalities, rather it may have backfired and exacerbated the existing problem (room temperatures increased 0.5–1.6 F° after the intervention). As the results illustrate, addressing negative externalities with pro-social nudges may be particularly challenging because they often target behavior that benefits a larger society and requires the individual to experience some short-term disutility.

Investigation of the Gas Permeation Stream through Gas Diffusion Electrodes for CO2 Electrolysis and Possible Links to Selectivity

The electrochemical reduction of CO2 (eCO2R) is one promising attempt to create value added products from excess greenhouse gas with renewable energy. However, to become commercially relevant, some challenges have to be outgrown. To overcome the challenge of mass transport limitations on planar electrodes, Gas-Diffusion-Electrodes (GDE) have been implemented for eCO2R, allowing to reach sufficient reaction rates with the CO2 directly being delivered to the catalyst layer [1]. A major issue in the application of GDEs for eCO2R represents flooding of the mostly carbon based gas diffusion media by the alkaline electrolyte during application. This phenomenon results in a detrimental change of the 3-phase boundary and is accompanied by a loss of activity and a breakdown of performance [2]. A possible approach to avoid flooding of the GDE during eCO2R is to apply a backpressure in order to increase the capillary pressure inside the GDE, which needs to be balanced accurately, since excess backpressure can cause a CO2 crossover stream through the GDE into the electrolyte compartment [3]. In our work we investigate the permeation behavior of GDEs in a customized flow cell and investigate how to influence it via electrode preparation. A deeper understanding of the permeation characteristics of GDEs could lead to a better choice of operation points regarding flooding issues. However, the operation point itself and the preparation of GDEs could impact not only the flooding behavior of the electrode but also selectivity of the reaction. The eCO2R is taking place ~10 µm away from the gas-liquid boundary. The distribution of the two phases inside the GDE is crucial for the reaction pathway [4]. Therefore, we examine possible links of permeation behavior and electrode preparation on selectivity.In detail, our setup contains a customized flow cell in which the pressure in the gas compartment is adjusted with a needle valve and monitored via a pressure transmitter. The gas-crossover stream through the GDE is then registered by collecting the gas transferred to the liquid electrolyte in a measuring cylinder.For electrode preparation, commercial carbon based GDLs (25BC-Sigracet, H23C8-Freudenberg) are pretreated by either spray coating a carbon-ionomer-layer on top of the microporous layer or sputter coating with copper first. In the second step, a galvanostatic deposition of copper is carried out on the pretreated GDLs.The permeation behavior is tested for the non-coated commercial GDLs, the GDLs after the pretreatment step and after deposition of copper without and with current applied, respectively. In our experiments the crossover stream related to backpressure through the GDL H23C8 was lower compared to the crossover stream through GDL 25BC, most likely being linked to differences in the porosity and cracks of the MPL (Figure 1A). However, when comparing identically prepared GDEs based on different GDL types at the same crossover stream, only minor changes in selectivity can be observed (Figure 1B). It was also found that the crossover stream was influenced by the coating of the electrode. While sputter coating (spu) has a minor impact on gas permeation, spray coating (spr) leads to a significant change. These observations could be related to increased electrode wetting after spray- but not after sputter coating. The permeation behavior after galvanic deposition of copper is comparable, independent of the pretreatment procedure. Comparing the selectivity of GDEs with the different pretreatment procedure, a significant change in selectivity can be observed (Figure 1C). In the next steps, it will be crucial to investigate if this selectivity change is related to a different gas-liquid distribution in the GDE or to other factors as the composition of the coating layer to successfully influence operation stability and selectivity.

Development of a broad range of two-colour ozone indicator

The antiviral and antibacterial properties of ozone gas have been utilised for air and on-site disinfection. However, excess ozone gas exposure is toxic to humans, necessitating the monitoring of exposure levels. While this has been achieved using ozone indicators, determining exposure levels at intermediate time points during exposure remains challenging owing to the current ones being capable of measuring exposure only at endpoints. Shifts in the endpoint are also difficult as the coverage ranges of the indicators are dependent on a single colour dye. The indicator that covers a wide range is desirable to treat various pathogenic microorganisms. The aim of this study was to develop a two-colour ozone indicator with a broad coverage range that does not compromise the performance of the individual dyes. Exposure levels were indicated by visible changes in colour density and phase, aiding the measurement of exposure at the endpoints and during the exposure period, thereby maintaining better safety profiles for exposed individuals. Additionally, a theoretical approach for the development of two-colour indicators has been described.

Thermo-Economic Comparison between Three Different Electrolysis Technologies Powered by a Conventional Organic Rankine Cycle for the Green Hydrogen Production Onboard Liquefied Natural Gas Carriers

The high demand for natural gas (NG) worldwide has led to an increase in the size of the LNG carrier fleet. However, the heat losses from this type of ship’s engines are not properly managed, nor is the excess boil-off gas (BOG) effectively utilised when generation exceeds the ship’s power demand, resulting in significant energy losses dissipated into the environment. This article suggests storing the lost energy into green H2 for subsequent use. This work compares three different electrolysis technologies: solid oxide (SOEC), proton exchange membrane (PEME), and alkaline (AE). The energy required by the electrolysis processes is supplied by both the LNG’s excess BOG and engine waste heat through an organic Rankine cycle (ORC). The results show that the SOEC consumes (743.53 kW) less energy while producing more gH2 (21.94 kg/h) compared to PEME (796.25 kW, 13.96 kg/h) and AE (797.69 kW, 10.74 kg/h). In addition, both the overall system and SOEC stack efficiencies are greater than those of PEME and AE, respectively. Although the investment cost required for AE (with and without H2 compression consideration) is cheaper than SOEC and PEME in both scenarios, the cost of the H2 produced by the SOEC is cheaper by more than 2 USD/kgH2 compared to both other technologies.

Discharge and mass transfer characteristics of atmospheric pressure gas-solid two-phase gliding arc

In this work, a gas-solid two-phase gliding arc discharge (GS-GAD) reactor was built. Gliding arc was formed in the gap between the blade electrodes, and solid powder was deposited on the sieve plate positioned beneath the blade electrodes. A range of experimental parameters, including the inter-electrode spacing, gas flow rate, applied voltage, and the type of the powder, were systematically varied to elucidate the influence of solid powder matter on the dynamics of gliding arc discharge (GAD). The discharge images were captured by ICCD and digital camera to investigate the mass transfer characteristics of GS-GAD, and the electrical parameters, such as the effective values of voltage, current, and discharge power were record to reveal the discharge characteristics of GS-GAD. The results demonstrate that powder undergoes spontaneous movement towards the upper region of the gliding arc due to the influence of electric field force. Increasing the discharge voltage, decreasing relative dielectric constant of the powder and reducing the electrode-to-sieve-plate distance all contribute to a greater involvement of powder in the GAD process, subsequently resulting in an enhanced powder concentration within the GAD region. Additionally, powder located beneath the gliding arc experiences downward resistance caused by the opposing gas flow and arc. Excessive gas flow rate notably hampers the powder concentration within the discharge region, and the velocity of powder motion in the upper part of the GAD region is reduced. Under the condition of electrode-to-sieve-plate distance of 30 mm, gas flow rate of 1.5 L/min, and peak-to-peak voltage of 31 kV, the best combination of arc gliding and powder spark discharge phenomena can be achieved with the addition of Al2O3 powder.

Impact of ventilated tunnels on smoke peculiarities in train carriage fires with multiple lateral openings

This research investigates the dynamics of smoke dispersion in a subway train carriage with multiple lateral openings within a ventilated subway tunnel. Numerous extensive full-scale numerical simulations were conducted to analyze the thermal plume distribution within multiple lateral openings of a train carriage, and the longitudinal and transverse maximum excess ceiling temperature. The results reveal that the heat release rates have a greater impact on the airflow in the carriage than velocities ,even when the longitudinal ventilation velocity reaches 8 m/s or the heat release rate reaches 15 MW. The multiple lateral openings cause significant differences in smoke flow characteristics compared to tunnels with both ends open. Additionally, the transverse maximum ceiling excess temperature inclines towards the lateral opening side due to asymmetrical air entrainment. The analysis of longitudinal maximum ceiling excess temperature identified two regions based on the dimensionless heat release rate, showing a linear increase followed by a constant phase dependent on the heat release rate, with a maximum longitudinal excess gas temperature of 1242 K. Additionally, a relationship between the dimensionless heat release rate and the transverse dimensionless maximum ceiling excess temperature was established. This study can be used as a guide for smoke exhaust mitigation and fire safety measures in the event of subway train carriage fires.

Assessment of climate change on river streamflow under different representative concentration pathways

Climate change and excessive greenhouse gas emissions profoundly impact hydrological cycles, particularly in arid and semi-arid regions, necessitating assessments of their effects on water resource management, agriculture, soil fertility, nutrient transport, hydropower generation, and flood risk. This study investigates climate change repercussions on streamflow in the Zarrineh River Basin, Iran, across three decadal intervals (2020–2029, 2055–2064, and 2090–2099) aiming to develop effective adaptation and mitigation strategies. Four General Circulation Models (GCMs), chosen based on distinct Representative Concentration Pathways (RCPs) determined by the annual mean temperature gradient, are employed. These models generate daily maximum (Tmax) and minimum (Tmin) temperatures along with precipitation data. Subsequently, these variables are integrated into the Soil and Water Assessment Tool (SWAT) model to analyze river flow alterations for each decadal timeframe. Comparison between future projections and observed climate data reveals a gradual decline in precipitation and Tmax, coupled with a substantial increase in Tmin. The average precipitation diminishes from 0.77 mm in the period 1985–1994 to a range of 0.42–0.28 mm in 2090–2099. The simulated flow at the basin outlet highlights that the GCM with the highest annual mean temperature gradient yields the lowest streamflow, while conversely, the model with the lowest gradient generates the highest. Consequently, streamflow experiences a decline from 52 m3/s in 1985–1994 to a range of 41–20 m3/s in 2090–2099.

Active control effect of shielding gas flow on high-power fiber laser welding plume

Plume are common physical phenomena in fiber laser keyhole welding and have serious negative effects on the welding process. Based on this, this paper explores the regulation law of conventional shielding gas flow on plume. The results show that the shielding gas has a very significant effect on the suppression of the slender part of the plume, and the greater the gas flow rate, the better the plume removal effect. The addition of the shielding gas makes the welding process more stable, the molten pool flows stably, and the frequency of spatter eruption is reduced. Under the experimental conditions, the optimal shielding gas flow rate is around 15 l/min, and the penetration depth and width are increased by about 10% and decreased by about 22%, respectively, compared with that without adding the shielding gas. Based on the gas flow simulation, the gas flow pressure (about 132 Pa) generated by an appropriate amount of shielding gas (about 15 l/min) can press the liquid column and spatter near the keyhole mouth into the molten pool to avoid the spatter eruption. Excessive shielding gas flow will interfere with the flow of the molten pool excessively, and the weld surface will show a serious undercut phenomenon.

Exergoenvironment evaluation of carbon resource conversion and utilization via CO2 direct hydrogenation for methanol and power cogeneration

CO2 hydrogenation technology is pivotal for achieving low-carbon and sustainable development goals by curbing carbon dioxide emissions and enabling new value chains. Traditional CO2 hydrogenation systems face challenges like excessive unreacted gas cycling and inefficient component usage. This study employed direct CO2 hydrogenation for methanol production, and integrated the chemical looping combustion (CLC) concept to enhance energy efficiency and carbon cycle utilization in methanol-electricity production. The proposed method has yielded remarkable results, attaining an exergy efficiency of 57.72 %, with CO2 equivalent emissions at 0.27 kgCO2/kgCH3OH. Furthermore, it has demonstrated a reduction of approximately 9.60 % in energy consumption and an impressive 83.63 % decrease in carbon emissions compared to the reference system. Exergoenvironmental analysis was conducted for the entire process and individual units. The results indicated superior environmental performance of the cogeneration system compared to the single-production system when the recycling ratio of unreacted gas (Ru) ranged from 1.64 to 2.72. Furthermore, CLC was identified as a key area requiring optimization within the system and determined by the values of rb,k and B˙D,k. This observation remains consistent even as Ru changes. The system showcases significant potential in thermodynamics and environmental sustainability, and lays a theoretical foundation and innovative perspective for CO2 utilization technologies.

DIFFICULT MASK VENTILATION IN OBESE PATIENTS: ANALYSIS OF PREDICTIVE FACTOR

American Society of Anesthesiologists (ASA), DMV is defined as the clinical situation. developing when it not possible for the anesthesiologist to provide adequate ventilation because of one or more of the following problems: inadequate mask seal, excessive gas lead or excessive resistance to the ingress or egress of gas. Materials and Methods:-This is a prospective randomised observational study in patients with morbid obesity (n = 90body mass index[BMI] >30 kg/m2. Patients were preoperatively assessed for age, height, weight, BMI,modified Mallampati test results,mouth opening [inter- incisor gap (cm)], thyromental distance (cm), sternomental distance (cm), mandibular protrusion,mandibular length (ML), neck circumference (NC) by anesthesiologist. Mask ventilation was graded according to four point Han scale. Conclusion:In conclusion, male sex, snoring history, NC ≥43 cm, ML ≥9 cm and NC/TMD <5 cm were correlated with DMV in obese patients.According to the current investigation the three predictive factors are strongly associated.In the present study we demonstrated that (a)age >49 years, (B)Neck circumference >43cm,and (C) and short neck are strongly associated with DMV in obese patients.

Anesthesia and its environmental impact: approaches to minimize exposure to anesthetic gases and reduce waste.

In today's era of modern healthcare, the intersection between medical practices and environmental responsibility has gained significant attention. One such area of focus is the practice of anesthesia, which plays a crucial role in various surgical procedures. Anesthetics such as nitrous oxide and volatile halogenated ethers (desflurane, isoflurane, sevoflurane) are examples of medical gases that are strong greenhouse gases that contribute to global warming. During medical procedures, most of these anesthetic agents are released into the atmosphere, which exacerbates their influence on the environment. Also anesthesia delivery systems have traditionally utilized high flow rates of gases, leading to not only excessive consumption but also a considerable environmental impact in terms of greenhouse gas emissions. However, the emergence of low-flow anesthesia (LFA) presents a promising solution for achieving emission reduction and cost savings, thereby aligning healthcare practices with sustainability goals. Understanding LFA involves the administration of anesthetic gases to patients at reduced flow rates compared to conventional high-flow methods. This practice requires precision in gas delivery, often incorporating advanced monitoring and control systems. By optimizing gas flow to match the patient's requirements, LFA minimizes wastage and excessive gas release into the environment, subsequently curbing the carbon footprint associated with healthcare operations. Decreasing volatile anesthetic delivery provides safe and effective strategies for anesthesia providers to decrease costs and reduce environmental pollution. Current literature support in favor of LFA represents an area of cost containment and an opportunity to lessen the environmental impact of anesthesia. This article will cover the concept of LFA, the distinctions between low flow and minimal flow, and the potential advantages of LFA, such as those related to patient safety, the environment, and the economy.

New insight into groundwater 4He ages based on Ne isotopic equilibrium in Jianghan Plain, Central China

The change of hydrostatic pressure caused by the fluctuation of groundwater table in the aquifer will lead to the partial dissolution of excess 4He gas, resulting in the isotope imbalance of 3He/4He-4He. The dissolved Ne in groundwater is mainly derived from the atmosphere, and its isotopic composition can correct the isotopic imbalance of 3He/4He-4He. We collected thirty-eight groundwater samples from the second aquifer of the Jianghan Plain, and the isotopic concentrations and ratios of He and Ne were measured. 21Ne/22Ne-20Ne/22Ne illustration is proposed to estimate the shares of atmospheric and mantle components. The 21Ne content and isotopic ratios of atmospheric and mantle components are used to estimate a calculated Ne content. The difference between the calculated Ne content and the measured Ne content (∆Ne) is used to evaluate the percentage of error estimated“excess air”. The accumulation of crustal 4He is corrected with the measured 4He content and the percentage of error estimated “excess air”. We found the maximum percentage of error estimated “excess air” was 7.57 % occurring in the groundwater samples from the second aquifer of Jianghan Plain, and the disequilibrium of 3He/4He-4He led to overestimation of the share of mantle He. The percentage of mantle He in total dissolved components is reassessed and range from 0.03 % to 0.74 %, indicating the mantle component is minor. The reassessed 4He ages (1.79 ka to 21.90 ka) were uniformly older than those estimated by traditional method which only use the measured 3He/4He ratio to distinguish the crust 4He (1.28 ka to 18.74 ka). 4He age is significantly underestimated up to 47.05 %.

Iron Oxide Direct Reduction and Iron Nitride Formation Using Ammonia: Review and Thermodynamic Analysis

The steel industry is one of the main contributors to global greenhouse gas emissions, responsible for about 7 to 9% of the world’s total output. The steel sector is under pressure to move toward net-zero emissions by reducing its consumption of coke as the main method of reducing iron-rich feed materials to iron. Due to its well-developed synthesis process, high supply chain, straightforward handling technologies, and highly developed long-standing infrastructure, ammonia has the potential to become a replacement for coke as a future iron ore reductant. This work reviews previous research on ammonia direct reduction of iron oxides and the possible formation of iron nitrides. A thermodynamic assessment using FactSage 8.2 thermochemical software was carried out examining the behavior of ammonia gas as the reductant upon heating, detailed evaluations of the stable phases present under different reaction conditions and using different feed materials, and the formation and stability of iron nitride phases. The results suggest that the reduction of hematite with ammonia occurs in two steps below 570 °C and three steps above 570 °C. The ratio of Fe2O3/NH3 was predicted to affect the reduction reactions by promoting a greater reduction degree and simultaneously lowering the initial temperature needed for reduction, while the excess gas concentration can suppress FeO formation. A predominance area diagram was developed showing the main areas of stable phases as a function of the partial pressure of NH3 and temperature. The formation of iron nitrides during the process was predicted and these were not expected to cause issues for the formation of iron due to their instability under the conditions studied. This analysis can be used to inform further experimental studies regarding ammonia reduction of iron oxide.Graphical