Gas Volume Research Articles

A dynamic framework for calculating the biomass of fattening pigs with an application in estimating the burden of porcine reproductive and respiratory syndrome in the Netherlands

Gaining insight into the size and composition of national pig populations can support decisions on disease control, welfare, and environmental sustainability. However, if one needs to draw meaningful comparisons between the performance of various production systems or countries, a method for standardization is required. One approach to achieve this is by means of biomass estimation. The objective of this study was to develop a biomass estimation framework that can provide detailed and reliable estimates of fattening pig biomass disaggregated by pig life stage (suckling, weaning and fattening), while accounting for the dynamic nature of pig populations. The framework was developed on publicly accessible data pertaining to pig production in the Netherlands, and we additionally assessed availability of required data for several other European countries (Spain, Germany, and Great Britain). Three distinct life stages—suckling piglets, weaning pigs, and fattening pigs—are considered in the framework. Demographic and movement data, including yearly imports, exports, and slaughter numbers, along with standing populations, were collected from official governmental sources. Required production parameters were sourced from representative surveys, with missing parameters supplemented by private industry reports or expert elicitation. The results from the framework for the Netherlands yield insights into the Dutch pig sector. In 2020, 156 million kg, 552 million kg, and 1654 million kg of biomass were produced in the suckling, weaning, and fattening stages, respectively. The evaluation against census data indicated the framework's reliability, with deviations mostly below 10 %. Data availability assessments for Spain, Germany and Great Britain reveal variations in data completeness and underscore the importance of local contacts and language expertise when extending the framework to other countries. The framework's relevance was further demonstrated through an illustrative application, assessing the impact of porcine reproductive and respiratory syndrome on pig biomass in the Netherlands. In the most severe disease scenario, the produced biomass decreased by 13 %, 17 %, and 66 % in the suckling, weaning, and fattening stages, respectively. Beyond disease burden estimation, the biomass estimates can be used as a denominator for various purposes to provide efficiency metrics, such as the amount of antibiotics used or the volume of greenhouse gases emitted per kilogram of pig biomass produced. While the framework could benefit from further refinement regarding resource use and economic values, its current iteration provides a robust and unique foundation for estimating biomass disaggregated by pig life stage, aiding decision-makers in the agricultural and veterinary sector.

Effects of Hyperbaric Oxygen Therapy in Treatment on Diverse Diseases

INTRODUCTION: Hyperbaric oxygen therapy (HBOT) indeed holds significant therapeutic potential across various medical conditions, primarily by increasing the concentration of oxygen delivered to tissues under pressure. Saturating tissues with oxygen allows for the effective alleviation of underlying hypoxia, facilitating healing, tissue repair and mechanisms of action leads to reducing concentration of pro-inflammatory acute phase proteins, interleukins, and cytokines. Conversely, HBOT while also boosting levels of growth factors and other cytokines that promote angiogenesis. REVIEW METHODS: The article was complied by analyzing data from PubMed and Google Scholar regarding effects of hyperbaric therapy. THE STATE OF KNOWLEDGE: Studies indicate that HBOT provides numerous opportunities in the treatment of extensive diseases acress various systems. Neurodegenerative disorders involve progressive nerve cell damage leading to motor or cognitive decline, exacerbated by oxidative stress and inflammation. HBOT has shown promise in delaying disease onset by improving mitochondrial dysfunction in motor neuron disease. In case of intestinal obstruction HBOT reduces intestinal gas volume, diameter of obstructed loops, and improves intestinal contractility. Significant benefits have been observed in conditions such as Crohn's disease and ulcerative colitis. Hyperbaric therapy presents potential benefits for the infertility, improving the environment for blastocyst implantation and pregnancy. CONCLUSION: There is no doubt that HBOT has a beneficial impact on treatment of many systems such as the nervous, cardiovascular, digestive, and skeletal. This innovative approach of hyperbaric therapy extends to selected disorders such as neurodegenerative diseases, Crohn's disease, ulcerative colitis, and infertility.

Investigation of oil spills in pipelines under pressureless flow conditions

In order to assess the losses and environmental impact during oil pipeline operations due to oil spills, it is essential to determine the volume of spilled oil. Generally, the existing mathematical models for calculating the amount of hydrocarbons spilled in accidents are based on the hydraulics of monophasic flow of liquid and gas through openings and tubes. However, appropriate evaluation and calculation methods for multiphase flows are almost non-existent in the literature and regulatory documents. Therefore, the development and application of methods for accurately determining the volume of oil or gas released into the environment from pipelines under various conditions deserve special attention. Analysis shows that in the accident-prone section of pipelines, due to the loss of integrity, a ballast volume forms when the liquid is discharged from the pipeline into the environment. Typically, for assessing oil spills, two points – maximum and minimum – are marked in the profile at the damaged and perforated section. A graph reflecting the distribution of hydrostatic pressure is constructed in this area. It is mistakenly assumed that the pressure at the leak point (at the point with the minimum height) is maximal, using the formula patm+ρghP. However, in reality, atmospheric pressure occurs at the minimum point, which is at the leak site. This article investigates the assessment of pressureless oil spills in pipelines with varying terrain profiles and presents possible scenarios. It also demonstrates, based on the principle of flow continuity, that complete emptying of the pipeline due to accidental leaks is impossible. In the event of oil spills, the complete drainage of the pipeline in a gravity flow mode is only possible if there are perforations at all the extremal points of the pipeline profile.

TECHNOLOGIES FOR DEPOSIT VOLUME ASSESSING IN AN OIL PIPELINE

Deposits of various compositions in the pipelines of oil and gas companies significantly worsen the conditions for transporting fluids between field facilities, their presence increases energy consumption and the possibility of accidents with environmental consequences. In sections where bullets are not using, the most effective way to remove asphalt-resin-paraffin deposits (ARPD) is to use compounds of organic solvents selected in laboratory conditions. One of the factors of their successful application is a preliminary assessment of the deposit volume in a complicated pipeline. The article examines a horizontal section of an oil pipeline with ARPD, closed at both ends, filled with oil with a residual content of associated petroleum gas after the first stage separator. Pressure reduction and the appearance of a certain volume of gas in a free state is initiated in the oil pipeline. The deposit volume is calculated on the basis of a mathematical formula during the injection of an organic solvent of the first portion with an information component.

Frictional loss and permeability estimation of sediment in salt cavern: A combined approach of mathematical model, experimental validation, and numerical simulations

Harnessing gas storage in sediment voids presents a promising trajectory for the future construction of large-scale underground gas reservoirs in low-grade salt mines. This approach not only augments the effective gas volume but also enhances the stability of the cavern. In contrast to traditional gas injection and brine discharge process, where brine is expelled from the upper pure brine space without involving brine seepage in sediment voids, gas storage in sediment voids entails expelling brine from these spaces, thus necessitating an understanding of the brine seepage characteristics in the sediment, which remains unclear. This study presents a comprehensive approach for estimating sediment frictional loss and permeability in interconnected wells, integrating mathematical modeling, experimental validation, and numerical simulation. The mathematical principles governing sediment behavior during in-situ gas/brine injection and brine discharge tests are theoretically elucidated, accompanied by derived formulas. Experimental verification is conducted in the horizontal interconnected wells (Ha4-5) of the Huaian salt mine in Jiangsu, yielding the sediment frictional loss (0.53 MPa) and permeability (6.9 × 10−11 m2). Subsequently, a 2D cross-sectional numerical model is established using the COMSOL software, considering the measured and predicted well morphologies. The model provides insights into the relationship between sediment frictional losses and permeability, yielding an inverse calculation of the average permeability (1.016 × 10−10 m2). Simulation results depict laminar brine flow characteristics in the cavern during gas/brine injection and brine discharge processes, with frictional loss occurring as brine passes through sediment. Examination of the brine seepage and pressure fields in the sediment reveals consistent brine flow velocity after passing through the sediment. This combined approach focuses on investigating the seepage characteristics of sediment at the bottom of salt caverns, offering valuable insights for estimating frictional losses and permeability in similar salt mines.

Releasing long bubbles trapped in thin capillaries via tube centrifugation and inclination

In confined systems, the entrapment of a gas volume with an equivalent spherical diameter greater than the dimension of the channel can form extended bubbles that obstruct fluid circuits and compromise performance. Notably, in sealed vertical tubes, buoyant long bubbles cannot rise if the inner tube radius is below a critical value near the capillary length. This critical threshold for steady ascent is determined by geometric constraints related to the matching of the upper cap shape with the lubricating film surrounding the elongated part of the bubble. Developing strategies to overcome this threshold and release stuck bubbles is essential for applications involving narrow liquid channels. Effective strategies involve modifying the matching conditions with an external force field to facilitate bubble ascent. However, it is unclear how changes in acceleration conditions affect the motion onset of buoyancy-driven long bubbles. This study investigates the mobility of elongated bubbles in sealed tubes with an inner radius near the critical value inhibiting bubble motion in a vertical setting. Two strategies are explored to tune bubble motion, leveraging variations in axial and transversal accelerations: tube rotation around its axis and tube inclination relative to gravity. By revising the geometrical constraints of the simple vertical setting, the study predicts new thresholds based on rotational speed and tilt angle, respectively, providing forecasts for the bubble rising velocity under modified apparent gravity. Experimental measurements of motion threshold and rising velocity compare well with theoretical developments, thus suggesting practical approaches to control and tune bubble motion in confined environments.

Insights into heat treatments of biodegradable Mg-Y-Nd-Zr alloys in clinical settings: Unveiling roles of β' and β1 nanophases and latent in vivo hydrogen evolution

Heat treatment serves as a viable strategy to effectively mitigate the intense corrosion of biodegradable WE43 alloys. However, limited comprehension of the passivation mechanisms underlying heat treatment and the dilemma to quantitatively examine the evolution of hydrogen gas in vivo introduce uncertainties in designing heat treatments for developing clinically applicable WE43. This work aims to advance this knowledge by applying cutting-edge atom probe tomography to provide atomic-scale insights into the passivation roles of rare earth (RE)-rich β1 (Mg3(Y, Nd)) and β' (Mg12NdY) nanophases induced by T6 heat treatment at 250 °C, and employing machine learning-based image analysis techniques to quantitatively unveil WE43’s in vivo gas evolution during a 12-week implantation. It was found that nanosized β1 and β' phases can effectively improve WE43′s corrosion resistance by inducing an accelerated passivation effect on the surface and confining the distribution of hydrogen ions in the matrix. Female rats presented slightly higher corrosion rates than male rats in weeks 1 and 4 but lower hydrogen gas volumes in vivo, while male rats possessed a superior ability to metabolise hydrogen gas in vivo. Notably, latent gas evolution against the corrosion rates was found which peaked at week 4 and subsided at week 12 despite the gradually decreased corrosion rates from week 1 to 12. This study offers insights for engineering heat treatments to develop clinically applicable WE43 with acceptable corrosion rates and in vivo gas generation at various implantation stages. Statement of SignificanceThe study aimed to reveal the role of β1 and β' nanophases on the good corrosion resistance of WE43. The influence of these nanophases on WE43′s corrosion performance has not been totally understood. Similarly, the understanding of hydrogen gas evolution as it relates to the magnesium implant's corrosion rate lacks clarity. Atom probe tomography (APT) indicates β1 and β' nanophases trap hydrogen, removing H2 from the lattice and disabling its catalytic role in Mg oxidation. Machine learning-aided analyses of computed tomography (CT) scan images indicate latent gas evolution, contradicting the monotonic in vivo H2 evolution that is widely accepted.

In vitro rumen degradation, fermentation, and methane production of four agro-industrial protein-rich co-products, compared with soyabean meal

Soyabean is considered an unsustainable protein source for livestock feeds because of the large quantity of input and energy required to cultivate and process it. Other protein-based agro-industrial co-products that are less input-intensive, can mitigate methane (CH4) production and may therefore be more sustainable options instead soyabean. The objective of this study was to compare the effect of replacing the same amount of protein (40 g/kg DM crude protein) as soyabean meal (SBM) with low-carbon local agro-industrial co-products, (brewers’ spent grains, BSG; dried wheat distillers’ grains, WDG; dried corn distillers’ grains, CDG and corn steep liquor CSL), on in vitro rumen degradation, fermentation and gas and methane production. The study used a 72-hour in vitro gas production method with a basal substrate of dried, ground grass silage and wheat. Gas volumes were measured at ten different specific intervals, and CH4 concentrations were analysed via gas chromatography. After 72 hours, in vitro DM degradability (IVDMD) and volatile fatty acid (VFA) concentrations were assessed. Gas and CH4 production curve profiles were fitted to models to determine asymptote production, the extent of degradation in rumen proper (RoP), and the fractional degradation rate (μ) (h−1) in the halfway 50 % of the asymptote production. The IVDMD and estimated RoP at 0.04 h and 0.025 h were lower (P<0.05) for BSG compared to the other treatments, by 4.9-6.6 %; 5.8–9.9 %; 5.2–9.0 %. Gas and CH4 yield (mL/g substrate and mL/g substrate degraded), and pH (SB = 6.77, BSG = 6.80, WDG = 6.74, CDG = 6.84, and CSL = 6.73; P>0.05), were not significantly affected by treatment. Butyrate and valerate were lower (P<0.05) for BSG compared to CSL, and caproate was lower (P<0.001) for BSG compared to the other treatments and in CSL compared to SBM. The results regarding degradability and VFAs concentrations of this study demonstrated that dried wheat distillers’ grains, dried corn distillers’ grains, and corn steep liquor have the potential to replace soyabean meal as protein sources for ruminants, but further reduction of CH4 emissions as a result of such practice may not be expected. Although slightly less degradable, based on their nutrient composition and the fact they did not affect rumen fermentation characteristics, brewers' spent grains can still play a complementary role in ruminant diets, especially in regions where they are locally readily available.

Impact of hydrogen blending on a real-world gas distribution network with a non-uniform elevation profile

Abstract The ongoing energy transition, characterized by the increasing integration of renewable energy sources, has amplified the demand for hydrogen as a clean energy carrier. Hydrogen requires not only efficient generation but also effective distribution. Utilizing the extensive natural gas infrastructure offers a practical solution, leveraging its widespread network and cost-effective capacity to transport large volumes of gas. Nevertheless, hydrogen blending causes significant alterations in gas quality and the fluid dynamic behavior of the whole network. This study aims to investigate the effects of hydrogen blending on the main fluid dynamic parameters, flow rate balancing, and gas quality in a multi-pressure gas distribution network with a non-uniform elevation profile. The proposed real test case leverages and validates the actual geometrical, altitudinal, and topological characteristics. Steady-state simulations with different mixtures, ranging from 2% to 20% hydrogen by volume, were performed. The results show that in the medium-pressure network, it is possible to operate with hydrogen mixtures while remaining within the normative fluid dynamic limits, and a marginal benefit can even be obtained on the minimum recorded pressure. In low-pressure subnetworks, the margin of pressure safety is greatly reduced, and with off-peak demand, even small elevation changes establish the most critical withdrawal node. However, due to the different distribution of gas flows, a decrease in maximum velocity is observed. The analysis shows some new fluid dynamic aspects to be considered to support feasibility analyses for hydrogen blending on gas infrastructure laid over areas with uneven elevations.

Sleep and Respiratory Parameters After Lung Transplantation in Adult Patients With Cystic Fibrosis.

We aimed to explore the prevalence and predictive factors of sleep-disordered breathing (SDB) in patients with cystic fibrosis (pwCF) after lung transplantation (LTX). We prospectively recruited adult pwCF who underwent LTX in our hospital from 2013 to 2022 and invited them for an attended overnight polysomnography (PSG) 1year after transplantation. The apnea-hypopnea index (AHI) was the primary outcome, and SDB was defined as an AHI≥5. Demographic, anthropometric, cardiometabolic, drug treatment, and pulmonary function variables were compared between pwCF with and without SDB. Multiple regression analysis was used to identify significant predictors of SDB. For a subset of participants who had available PSG before transplantation, sleep parameters were compared pre-post transplantation. Sixty-two pwCF (31 females) were enrolled. Thirty participants had SDB, but only 11 of them had moderate-to-severe SDB (AHI≥15). The average Epworth Sleepiness Scale (ESS) score indicated the absence of excessive daytime sleepiness. Older age (p<0.001), male sex (p<0.001), and smaller thoracic gas volume (p=0.002) significantly predicted higher AHI. Comparison between pre- and post-transplantation polysomnographic data showed a significant increase in the percentage of slow wave sleep (p=0.047), as well as a significant improvement in mean nocturnal oxygen saturation (p=0.007). A statistically significant increase in the AHI was also observed (p=0.047), but its clinical importance is uncertain (p=0.476 for the increase in the ESS score). We may conclude that SDB is prevalent in pwCF after LTX, but its severity is mild. Older male pwCF with greater improvement in lung hyperinflation after transplantation might be at risk for SDB and should be followed for symptoms or signs of sleep apnea.

Critical Thresholds for CO2 Foam Generation in Homogeneous Porous Media

Summary Long-distance propagation of foam is one key to deep gas mobility control for enhanced oil recovery and CO2 sequestration. It depends on two processes—convection of bubbles and foam generation at the displacement front. Prior studies with N2 foam show the existence of a critical threshold for foam generation in terms of a minimum pressure gradient ∇pgenmin or minimum total interstitial velocity vt,genmin, beyond which strong-foam generation is triggered. The same mechanism controls foam propagation. There are few data for ∇pgenmin or vt,genmin for CO2 foam. We extend previous studies to quantify ∇pgenmin and vt,genmin for CO2 foam generation and, for the first time, relate ∇pgenmin and vt,genmin to factors including injected quality (gas volume fraction in the fluids injected) fg, surfactant concentration Cs, and permeability K. In each experiment, steady pressure gradient ∇p is measured at fixed injection rate and quality, with total interstitial velocity vt increasing and then decreasing in a series of steps. The trigger for strong-foam generation features an abrupt jump in ∇p upon an increase in vt. In most cases, the data for ∇p as a function of vt identify three regimes, which are coarse foam with low ∇p, an abrupt jump in ∇p, and strong foam with high ∇p. The abrupt jump in ∇p upon foam generation confirms the existence of ∇pgenmin and vt,genmin for CO2 foam. We further show how ∇pgenmin and vt,genmin scale with fg, Cs, and K. Conditions that stabilize lamellae reduce the values of the thresholds: Both ∇pgenmin and vt,genmin increase with fg and decrease with increasing Cs or K. Specifically, ∇pgenmin scales with fg as (fg)2 and vt,genmin scales as (fg)4, and both ∇pgenmin and vt,genmin scale with Cs as (Cs)−0.4. The effect of K on the thresholds for foam generation is greater than the effects of fg and Cs. Our data in artificial consolidated cores show that ∇pgenmin scales with K as K−2 for CO2 foam, in comparison with K−1 for N2 foam in unconsolidated sand/bead packs. More data are needed to verify these correlations. It is encouraging that ∇pgenmin in the cores with K = 270 md or greater is less than 0.17 bar/m (~0.75 psi/ft), two to three orders of magnitude less than for N2 foam. Such low ∇pgenmin can be easily attainable throughout a formation. This suggests that limited ∇p deep in formations is much less of a restriction for long-distance propagation of CO2 foam than for N2 foam. Foam propagation could still be challenging in low-K reservoirs (∇pgenmin ~10 bar/m for K = 27 md). Nevertheless, formation heterogeneity and alternating slug injection of gas and liquid help foam generation and can reduce the values of ∇pgenmin. More research is needed to predict long-distance propagation of foam at low ∇p and vt.

Influence of gas volume fraction on vortex street generation in downhole Oil-gas Two-phase flow

Abstract Vortex flowmeters are suitable for measuring flow rates in downhole environments due to their stability and wide applicability. However, the variability of the downhole environment and the complexity of fluid components severely impact the accuracy of flow measurements. To address this issue, this paper employs numerical simulation methods and uses the VOF model to analyze oil-gas two-phase flow. The results indicate that in two-phase flow, vortex flowmeters can be used for measuring oil-gas mixtures, and when the gas volume fraction is within 12%, the vortex-shedding frequency exhibits a linear relationship with the gas volume fraction. Additionally, it is found that the normalized power of vortex-shedding decreases in an approximately S-shaped curve with increasing gas volume fraction. These conclusions provide guidance for the subsequent calibration of flow rate data.

Numerical simulation and mechanistic model study of gas pocket distribution characteristics in a centrifugal impeller

The formation and extension of the gas pocket in the impeller can lead to the rapid deterioration or even failure of the centrifugal pump's two-phase pressurization. It is difficult to directly measure the characteristic parameters of the gas pocket in the high-speed rotating impeller, such as the void fraction, by experimental methods. In this paper, the two-phase performance of the centrifugal pump is studied by numerical simulation and validated by the experiment. The positive pressure gradient at the end of the blade pressure surface is the main reason why the centrifugal pump can boost at high inlet gas volume fraction (IGVF). As the IGVF increases, both the length and thickness of the gas pocket gradually increase. The head coefficient of the pump has an approximately quadratic relationship with the void fraction in the impeller. The mechanism model of the gas pocket flow is established by the force analysis of the gas pocket and its downstream single bubble in the impeller channel. The model can effectively predict the extension position of the gas pocket and the void fraction in the centrifugal impeller and is validated by numerical simulation.

Operative forecasting of fuel gas consumption in gas transportation companies

In the current context of energy resource conservation and increased effi ciency of gas transportation systems, developing approaches to improve the accuracy of fuel gas consumption forecasting at compressor stations is a pressing task. This paper analyzes approaches and algorithms for forecasting the volumes of gas needed for the technological and internal needs of compressor stations during gas compression within the gas transportation organizations of Gazprom PJSC. A classifi cation of gas consumption for technological needs and losses is presented, emphasizing the importance of managing fuel gas consumption to optimize the cost of natural gas transportation.The goal of this study is to develop an approach for operational forecasting of fuel gas consumption at compressor stations of gas transportation organizations, aimed at increasing economic effi ciency and reducing operating costs. To achieve this goal, the following tasks were undertaken: analysis of existing forecasting methods, investigation of data processing techniques for detecting errors and anomalies, and comparison of various regression models to ensure high forecast accuracy.The study employed data cleaning and preprocessing methods, including the Isolation Forest method for anomaly detection, as well as various regression models such as multiple linear regression, RandomForestRegressor, CatBoostRegressor, and XGBoost. Data segmentation was performed using cluster analysis (KMeans), which allowed for improved model accuracy. Forecast accuracy was assessed using t-tests, F-tests, and the mean absolute percentage error (MAPE) metric.The results of the study confi rmed the high accuracy of the proposed approach, demonstrating its potential for optimizing fuel costs in gas transportation organizations.

Combustion and Energy Parameters of Grape Pomace/Skin Waste in Wine Production—Regent Variety Grafted onto Rootstocks

The study presents the potential use of winemaking residues, specifically grape pomace, for energy purposes. The pomace was obtained from the cultivation of the Regent grape variety on three different rootstocks—125AA, 161-49, and SO4—as well as a control group grown on its own roots. The research included determining the calorific value and combustion heat, conducting a technical and elemental analysis of the potential biofuel, as well as estimating emission indicators (CO, CO2, NOx, SO2, and particulate matter) and the theoretical volume of flue gases based on stoichiometric equations. The study revealed significant differences among the combustion heat, tested properties and calorific value, ash content, and the total volume of flue gases. The highest calorific value (17.7 MJ kg−1) and combustion heat (18.9 MJ kg−1) were obtained for pomace from the SO4SO4 rootstock, while the lowest values were observed in the control group (17.0 MJ·kg−1 and 15.8 MJ·kg−1, respectively). The highest ash content was also recorded for the SO4 rootstock (9.2%), with the lowest in the control group (6.7%). The control group exhibited the lowest CO2 emissions at 1390.50 kg·Mg−1, while the highest emissions were found in the pomace from the SO4 rootstock (1478.8 kg·Mg−1). Regarding the total flue gas volume, the highest volume was estimated for the pomace from the 125AA rootstock (7.8 m3·kg−1) and the lowest for the control group (7.3 m3·kg−1). The research demonstrated that grape pomace possesses favorable energy properties and could serve as a potential biofuel, contributing to the fuel and energy balance of agricultural production enterprises. The analyzed biomass exhibits properties similar to agrobiomass.

Volumetric Passive Acoustic Mapping and Cavitation Detection of Nanobubbles under Low-Frequency Insonation.

Gas bubbles, commonly used in medical ultrasound (US), witness advancements with nanobubbles (NB), providing improved capabilities over microbubbles (MB). NBs offer enhanced penetration into capillaries and the ability to extravasate into tumors following systemic injection, alongside prolonged circulation and persistent acoustic contrast. Low-frequency insonation (<1 MHz) with NBs holds great potential in inducing significant bioeffects, making the monitoring of their acoustic response critical to achieving therapeutic goals. We introduce a US-guided focused US system comprising a one-dimensional (1D) motorized rotating imaging transducer positioned within a low-frequency therapeutic transducer (center frequencies of 105 and 200 kHz), facilitating precise monitoring of NB cavitation activity in three-dimensional (3D) and comparison with MBs. Passive cavitation detection (PCD) revealed frequency-dependent responses, with NBs exhibiting significantly higher stable and inertial cavitation doses compared to MBs of the same gas volume when excited at a center frequency of 105 kHz and peak negative pressures ranging from 100 to 350 kPa. At 200 kHz, MBs showed higher cavitation doses than NBs. PCD showed that 105 kHz enhanced both NBs' and MBs' oscillations compared to 200 kHz. The system was further used for 3D passive acoustic mapping (PAM) to provide spatial resolution alongside PCD monitoring. Two-dimensional PAM was captured for each rotation angle and used to generate a complete 3D PAM reconstruction. Experimental results obtained from a tube phantom demonstrated consistent contrast PAM full-width half-maximum (FWHM) as a function of rotation angle, with similar FWHM between MBs and NBs. Frequency-selective PAM maps distinguished between stable and inertial cavitation via the harmonic, ultraharmonic and broadband content, offering insights into cavitation dynamics. These findings highlight NBs' superior performance at lower frequencies. The developed 3D-PAM technique with a 1D transducer presents a promising technology for real-time, noninvasive monitoring of cavitation-based US therapies.

Assessment of the effect of browse plants’ feed formulation on Goat (&lt;i&gt;Capra aegagrus hircus&lt;/i&gt;) rumen microbial activities and &lt;i&gt;in vitro&lt;/i&gt; gas production

This study assessed the effect of browse Plants feed formulation on Goat (Capra aegagrus hircus) rumen microbial activities and in vitro gas production in Red Sokoto goat (Capra aegagrus hircus) over a period of fourteen (14) weeks. Four selected browse plants- Afzelia africana (TAa) Detarium microcarpum (TDm), Daniellia oliveri (TDo) and Khaya senegalensis (TKs) -were used to formulate diets for animal feeding. Three groups of growing Indigenous Red Sokoto goats were assigned to each of the browse plant diets (BPD), while the control group was placed on a basal diet only. Rumen fluids were collected from the goats intermittently for three (3) consecutive periods, and analyzed for pH, methylene blue-reduction time (MBRT), nitrate reduction, cellulose digestion, glucose fermentation and sedimentation activity rate. The results showed that browse plant feed formulation did not have a significant (p &gt; 0.05) effect on the pH value of the rumen contents. Significant (p &lt; 0.05) reductions in MBRT, nitrate reduction, and glucose fermentation were observed in all treatments except the control diets. However, the period for cellulose digestion significantly increased in all the browse plant-supplemented diet treatments. Furthermore, the volume of gas produced was significantly reduced by 64% (TAa), 62% (TDm), 71% (TDo), and 74% (TKs) in goats fed with browse plants as dietary supplements compared to 7% in the control (Tc). Overall, this study demonstrated that browse plant feed has the potential to significantly reduce the volume of methane produced and released by ruminant animals into the environment.

Simulation Study on Reservoir Stimulation of Multihorizontal Wells for Gas Hydrate Production in Low-Permeability Reservoirs.

The feasibility of hydrate exploitation technology has been verified by two rounds of trial productions in the South China Sea, but it is also faced with the problem of low gas production efficiency. Therefore, this paper proposed four different hydrate production cases with multihorizontal wells and established simulation models. Then, the influence patterns of reservoir stimulation and offset distances on hydrate dissociation, saturation change, and pressure distribution were studied. To understand hydrate dissociation behaviors and production performances, the coupling effects of multihorizontal wells were discussed. Through simulation, the following conclusions could be drawn: (1) hydrate reservoir stimulation could effectively increase gas production. In these four production models, the cumulative gas production in Case C (multihorizontal wells + reservoir stimulation) was 5.27 times that of Case A (only multihorizontal wells) in 330 days. However, in Case D with screen completions, the gas output was 15.58% less compared with Case C. (2) Different offset distances of horizontal wells had a relatively minor impact on the cumulative gas yield and daily gas capacity. In addition, the variation range of hydrate saturation changed with offset distances of horizontal wells, indicating that hydrate dissociation occurred mainly around horizontal wells and fractures. (3) Considering interwells coupling, the daily gas rate and cumulative gas production of inner wells were higher than outer wells, and the cumulative gas volume increased by 6.4% in 330 days. Temporally and spatially, the hydrate saturation variation between wells was significantly faster than the outward expansion from the horizontal wells. Moreover, nearer to the axis of the horizontal wells, the variation in the hydrate saturation was more pronounced. These results could provide theoretical data to optimize marine hydrate development with multihorizontal wells.

Physiological Challenges and Adaptations in Competitive Freediving

Competitive freediving is associated with extreme physiologic challenges due to the effects of apnea, submersion in water, and increased ambient pressure. There has nevertheless been a continued progression of world records across freediving disciplines in recent years, with breath-hold times exceeding 10 minutes, and reaching diving depths beyond 200 meters of seawater. The main physiological determinants of breath-hold endurance are the available oxygen stores, i.e., intrapulmonary gas volume, inspired gas concentration, and rate of oxygen consumption. Other factors such as psychological and inherent factors contribute to the individual tolerance to an increasing respiratory stimulus with prolonged breath-hold duration. A freediving athlete must be able to tolerate apnea to stay underwater long enough to reach great distance or depth and resurface safely. Elite freedivers exhibit somewhat remarkable physiological adaptations such as a more pronounced diving-response and hypercapnia tolerance compared to non-divers, as well as metabolic and cerebrovascular adaptations. To reach great depths, elite freedivers employ a breathing technique called glossophyryngeal insufflation (GI) that is enlarging the ratio of total lung capacity to residual volume, thus, mitigating risk of lung squeeze and increasing intrapulmonary gas volume, and thereby enhancing available oxygen stores. Pulmonary anatomy and physiology could not be accounted to restrict the breath-hold diving depths achieved by competitive athletes. However, the acutely increased intrapulmonary pressure during GI is transmitted to the pulmonary vasculature, thereby eliciting a right ventricular pressure overload, and left ventricular dysfunction that may augment hypotension and syncope during glossopharyngeal insufflation. Due to extreme diffusion gradients between alveolar pN2 and N2 pressures in the body tissues at great depth, N2 will be forced into blood and body tissues during descent, elevating risk of N2 narcosis and decompression illness during deep dives. Breath-hold training and preparation have been shown to enhance breath-hold performance. This review highlights recent data on the profound cardiovascular, respiratory, and gas exchange effects that are observed in competitive freedivers, and discusses possible adaptations and risks for humans.

Single-Use Aircraft Launch System with Small Helium Balloon for 1 kPa Flight Testing

A single-use aircraft launch system using a small helium balloon concept was proposed to elevate the likelihood of successful high-altitude flight tests above 30 km. The system, capable of carrying a payload of 0.5 kg, has been developed and reported. Completing the flight within a range of 92 km, which represents the maximum communication distance between the airborne flight system and the ground station for operational phase control, is imperative. Therefore, a straightforward method for simulating flight trajectories was outlined to determine launch windows and suitable locations to ensure flight completion within uninhabited areas. Simulation studies revealed that the shortest landing distance was obtained during summer at the selected launch site. Additionally, a parameter study was conducted to assess the influence of varying ascent velocities on the targeted flight test altitude, which depends on the payload weight and helium gas volume. Consequently, the parameter study results established the constraints for flight model design. A demonstration flight was conducted in 2023 to validate the feasibility of the system for high-altitude flight experiments. This flight successfully released the flight model at 31 km and recovered flight data before landing on the sea surface. The proposed system concept offers an expedited approach to aircraft design for operating in thin air. It enables component function tests and scaled model flights as an alternative to employing large high-altitude balloons for high-altitude experiments.