Internal Concentration Research Articles

Acoustic parameters and wave velocity field evolution characteristics in the high-stress region of granite

The risks of underground engineering originate from disturbances caused by the alterations to the stress field within rock masses. To understand the variations in the stress field within rock masses under local stress conditions, a set of double-hole pullout tests was used to design. The MS/AE location and tomography were used to investigate the evolution characteristics of the internal stress concentration area in granite. Results show that acoustic emission events transition from scattered and nucleated to regionally aggregated, then developing into arc-shaped patterns, ultimately exhibiting a trend of semi-spherical distribution. The increase in the fractal dimension of the spatial distribution of acoustic emission events indicates increased stress concentration degree, whereas a decrease signifies dispersion or transfer. Tomography results demonstrate the dynamic development process of local stress zones, with initial velocity anomalies as the core, continuously aggregating and expanding, showing an increasing difference trend compared to the velocity outside the region.

Enhancing efficiency in closed agricultural greenhouses: A data-driven predictive model for energy consumption

Abstract Predicting energy consumption in agricultural greenhouses is essential to effectively allocate resources, enhance plant growth, and minimize energy inefficiencies. Various factors affect the energy consumption inside the greenhouse including external climate conditions and internal microclimate. Proper understanding of these factors is crucial for maintaining an ideal growing environment and optimizing energy efficiency. This drives the need to investigate the interaction between these factors and greenhouse energy consumption, encompassing the energy needed for cooling and the supply of water and nutrients. This work aims at developing a dynamic model that predicts the total energy consumption of a closed agricultural greenhouse to improve microclimate control and energy efficiency. The study is conducted within a closed-loop agricultural greenhouse with no natural ventilation. Inside, the air is cooled and continuously circulated without being exchanged with ambient air through a heating, ventilation, and air conditioning (HVAC) system. The data-driven model encompasses external climate parameters such solar radiation, ambient temperature, and relative humidity; along with microclimate parameters such as internal temperature, humidity, and CO2 concentration to predict overall energy consumption. The study examines two machine learning models, deep neural networks (DNN) and extreme gradient boosting (XGBoost), for forecasting energy consumption, and assesses their performance using the coefficient of determination (R2), the root mean square error (RMSE), and the mean absolute error (MAE). Results reveal that the DNN model surpasses the XGBoost model, exhibiting a superior predictive performance with an R2 of 80.9%, RMSE of 171.1 kWh and MAE of 130.3 kWh. This study demonstrates its practicality in assisting with energy consumption analyses and identifying inefficient energy usage patterns within closed agricultural greenhouses.

Viability of Total Ammoniacal Nitrogen Recovery Using a Polymeric Thin-Film Composite Forward Osmosis Membrane: Determination of Ammonia Permeability Coefficient.

Total ammoniacal nitrogen (TAN) occurs in various wastewaters and its recovery is vital for environmental reasons. Forward osmosis (FO), an energy-efficient technology, extracts water from a feed solution (FS) and into a draw solution (DS). Asymmetric FO membranes consist of an active layer and a support layer, leading to internal concentration polarization (ICP). In this study, we assessed TAN recovery using a polymeric thin-film composite FO membrane by determining the permeability coefficients of NH4+ and NH3. Calculations employed the solution-diffusion model, Nernst-Planck equation, and film theory, applying the acid-base equilibrium for bulk concentration corrections. Initially, model parameters were estimated using sodium salt solutions as the DS and deionized water as the FS. The NH4+ permeability coefficient was 0.45 µm/s for NH4Cl and 0.013 µm/s for (NH4)2SO4 at pH < 7. Meanwhile, the NH3 permeability coefficient was 6.18 µm/s at pH > 9 for both ammonium salts. Polymeric FO membranes can simultaneously recover ammonia and water, achieving 15% and 35% recovery at pH 11.5, respectively.

Non-invasive biomonitoring of polar bear feces can be used to estimate concentrations of metals of concern in traditional food.

The Arctic faces increasing exposure to environmental chemicals such as metals, posing health risks to humans and wildlife. Biomonitoring of polar bears (Ursus maritimus) can be used to quantify chemicals in the environment and in traditional foods consumed by the Inuit. However, typically, these samples are collected through invasive or terminal methods. The biomonitoring of feces could be a useful alternative to the current metal monitoring method within the Arctic. Here, we aim to 1) quantify the relationship between concentrations of metals in the feces and tissues (muscle, liver, and fat) of polar bears using predictive modeling, 2) develop an easy-to-use conversion tool for use in community-based monitoring programs to non-invasively estimate contaminant concentrations in polar bears tissues and 3) demonstrate the application of these models by examining potential exposure risk for humans from consumption of polar bear muscle. Fecal, muscle, liver, and fat samples were harvested from 49 polar bears through a community-based monitoring program. The samples were analyzed for 32 metals. Exploratory analysis indicated that mean metal concentrations generally did not vary by age or sex, and many of the metals measured in feces were positively correlated with the internal tissue concentration. We developed predictive linear regression models between internal (muscle, liver, fat) and external (feces) metal concentrations and further explored the mercury and methylmercury relationships for utility risk screening. Using the cross-validated regression coefficients, we developed a conversion tool that contributes to the One Health approach by understanding the interrelated health of humans, wildlife, and the environment in the Arctic. The findings support using feces as a biomonitoring tool for assessing contaminants in polar bears. Further research is needed to validate the developed models for other regions in the Arctic and assess the impact of environmental weathering on fecal metal concentrations.

The osmoregulated metabolism of trehalose contributes to production of type 1 fimbriae and bladder colonization by extraintestinal Escherichia coli strain BEN2908.

In Escherichia coli, the disaccharide trehalose can be metabolized as a carbon source or be accumulated as an osmoprotectant under osmotic stress. In hypertonic environments, E. coli accumulates trehalose in the cell by synthesis from glucose mediated by the cytosolic enzymes OtsA and OtsB. Trehalose in the periplasm can be hydrolyzed into glucose by the periplasmic trehalase TreA. We have previously shown that a treA mutant of extraintestinal E. coli strain BEN2908 displayed increased resistance to osmotic stress by 0.6 M urea, and reduced production of type 1 fimbriae, reduced invasion of avian fibroblasts, and decreased bladder colonization in a murine model of urinary tract infection. Since loss of TreA likely results in higher periplasmic trehalose concentrations, we wondered if deletion of otsA and otsB genes, which would lead to decreased internal trehalose concentrations, would reduce resistance to stress by 0.6 M urea and promote type 1 fimbriae production. The BEN2908ΔotsBA mutant was sensitive to osmotic stress by urea, but displayed an even more pronounced reduction in production of type 1 fimbriae, with the consequent reduction in adhesion/invasion of avian fibroblasts and reduced bladder colonization in the murine urinary tract. The BEN2908ΔtreAotsBA mutant also showed a reduction in production of type 1 fimbriae, but in contrast to the ΔotsBA mutant, resisted better than the wild type in the presence of urea. We hypothesize that, in BEN2908, resistance to stress by urea would depend on the levels of periplasmic trehalose, but type 1 fimbriae production would be influenced by the levels of cytosolic trehalose.

A practical semi-empirical model for predicting the SoH of lithium-ion battery: A novel perspective on short-term rest

In this paper, the semi-empirical battery degradation prediction model proposed considers electrochemical degradation characteristics and represents degradation effects under various conditions, including different states of charge (SoC) areas. This model is specifically designed to address degradation during cycling and short-term rest periods in lithium-ion batteries using liquid electrolytes. Cycle aging incorporates the impact of solid electrolyte interphase (SEI) growth, a known dominant factor, and the model for short-term resting periods captures potential aging impacts on subsequent cycles due to internal material concentration gradients, moving away from the traditionally used calendar life approach. The derivation of the model presented in this paper is based on 14 data sets under different SoC conditions and 8 data sets under various Crates, explaining the degradation effects at 10 % SoC intervals and three different Crate points. Moreover, the model's performance was validated through capacity prediction for two data sets experimented with dynamic operational schedules of actual energy storage systems (ESS), including various conditions. The results showed a root mean square error (RMSE) of 0.564 and a mean absolute percentage error (MAPE) of 0.346. The superiority of this model is demonstrated by comparing its performance with four other types of degradation models derived through the same process in the validation data.

Dynamic evolution of residual stress upon manufacturing Al-based diesel engine diaphragm

Abstract As a thin-walled complex structure, the manufacturing of Al-based diesel engine diaphragms involves casting and heat treatment. Residual stress is introduced during the uneven temperature field in casting and heat treatment, as well as the plastic deformation and cutting heat during mechanical processing. This research investigates the evolution and accumulation models of residual stress in casting and heat treatment for Al-based diesel engine diaphragms using ProCAST and ABAQUS software, combining with the experimental tests. To mitigate residual stress, the optimal parameter combination for casting temperature, knockout temperature, and mold preheating temperature in casting process is explored. The results indicate that the knockout temperature has the most significant influence on casting residual stress, and mold preheating is beneficial for reducing residual stress. Despite improvements, some internal stress concentration areas persist on the knockout casting surface. Furthermore, T6 heat treatment proves to be effective in eliminating more than 50% of the residual stress.

The role of defects in high-silica zeolite hydrolysis and framework healing

The stability of high silica zeolites under standard laboratory and mild steaming conditions is understood to be due to the lack of hydrophilic Al-O-Si moieties, which can be targeted by water via hydrolysis reactions with relatively low barriers. However, in hydrophobic high-silica and siliceous frameworks, the specific interactions between water and the internal framework sites are incompletely understood. In particular, the behaviour of common internal defects, including partial hydrolysis species and silanol nests are not established, despite their expected role in accelerating the decomposition of the framework. In this work, we utilise machine learning potentials combined with density functional calculations to rigorously sample the hydrolysis processes in siliceous zeolites with topologies CHA and MFI under low water conditions and quantify the effect of defects. Internal silanol defect sites are found to accelerate zeolite decomposition primarily by bypassing the initial, high-barrier hydrolysis step. Subsequent steps proceed with lower reaction barriers. However, all reaction steps are found to be highly activated, and unlikely to occur rapidly at room temperature under conditions of low internal water concentration. Exchange-healing routes, which reverse hydrolysis while incorporating oxygen from water molecules are found to be competitive along the entire hydrolysis pathway in CHA, providing an additional source of stabilization against hydrolytic decomposition.

Explicit expression for water permeation flux in forward osmosis desalination process

Forward osmosis (FO) is a membrane process of water separation and purification. FO uses the osmotic pressure difference across a semipermeable membrane. The effective osmotic pressure at the membrane–solution interface on both the feed and permeate sides of the membrane is the main driving force for the generation of the water flux. The major hindrance to the permeation of the water flux is the prevalence of concentration polarization on both sides of the membrane. Concentration polarization inhibits permeate flux by increasing the osmotic pressure at the membrane active layer interface on the feed side of the membrane. This work focused on the development of a mathematical model for water flux in the FO process. Combined film theory model and diffusion transport through the membrane were utilized. The effect of internal concentration polarization and external concentration polarization on the flux was studied. Both internal and external concentration polarization were taken into consideration in both membrane orientations, i.e., active layer facing the feed solution and active layer facing the draw solution. The obtained explicit expression for water permeation flux in forward osmosis desalination process shows excellent agreement with the literature data.

Amphistomy: stomata patterning inferred from 13C content and leaf-side-specific deposition of epicuticular wax.

The benefits and costs of amphistomy (AS) vs. hypostomy (HS) are not fully understood. Here, we quantify benefits of access of CO2 through stomata on the upper (adaxial) leaf surface, using 13C abundance in the adaxial and abaxial epicuticular wax. Additionally, a relationship between the distribution of stomata and epicuticular wax on the opposite leaf sides is studied. We suggest that the 13C content of long-chain aliphatic compounds of cuticular wax records the leaf internal CO2 concentration in chloroplasts adjacent to the adaxial and abaxial epidermes. This unique property stems from: (1) wax synthesis being located exclusively in epidermal cells; and (2) ongoing wax renewal over the whole leaf lifespan. Compound-specific and bulk wax 13C abundance (δ) was related to amphistomy level (ASL; as a fraction of adaxial in all stomata) of four AS and five HS species grown under various levels of irradiance. The isotopic polarity of epicuticular wax, i.e. the difference in abaxial and adaxial δ (δab - δad), was used to calculate the leaf dorsiventral CO2 gradient. Leaf-side-specific epicuticular wax deposition (amphiwaxy level) was estimated and related to ASL. In HS species, the CO2 concentration in the adaxial epidermis was lower than in the abaxial one, independently of light conditions. In AS leaves grown in high-light and low-light conditions, the isotopic polarity and CO2 gradient varied in parallel with ASL. The AS leaves grown in high-light conditions increased ASL compared with low light, and δab - δad approached near-zero values. Changes in ASL occurred concomitantly with changes in amphiwaxy level. Leaf wax isotopic polarity is a newly identified leaf trait, distinguishing between hypo- and amphistomatous species and indicating that increased ASL in sun-exposed AS leaves reduces the CO2 gradient across the leaf mesophyll. Stomata and epicuticular wax deposition follow similar leaf-side patterning.

Accelerated pork salting using needle electrode-derived pulsed electric fields

This study aimed to evaluate the effects of pulsed electric field (PEF) pretreatment on the NaCl content, protein composition, and microstructure of pork during the marination process. The results showed that needle PEF could promote salt penetration into the center of pork pieces. Under optimal PEF conditions (3.0 kV/cm, 200 Hz, and 2400 pulses), the marination time could be reduced by almost 12 h. Protein characterization also revealed that PEF pretreatment changes myofibrillar protein properties by promoting salt penetration toward the center of pork. Furthermore, microstructural analysis demonstrated that the enhanced marination effect could be attributed to the PEF treatment-induced expansion of gaps between muscle bundles. Industrial relevanceIn this study, a PEF-assisted curing technique significantly (P < 0.05) improved salt penetration into the center of pork. Reducing the differences between internal and external salt concentrations can produce a more homogeneous marinade and reduce the marination time. Our findings suggest that PEF pretreatment is a promising and effective pretreatment technique for curing meat products.

Quantifying the protective efficacy of GN anti-chloride admixture on durable performance of concrete in chloride ion erosion environments

This study evaluates the effectiveness of GN (Graphene Nanoplatelets) salt inhibitor-treated concrete in inhibiting chloride ion diffusion and corrosion compared to untreated concrete under various erosion conditions. Through an accelerated indoor chloride erosion test lasting 180 days, we examined the temporal changes in internal chloride ion concentration with and without the GN salt inhibitor. Quantitative assessment of the inhibitor's impact was achieved by introducing reduction factors for surface chloride concentration and diffusion coefficient. Our findings reveal a significant reduction of 31.3 % in chloride ion diffusion coefficient and 22.67 % in surface chloride concentration in concrete treated with GN salt inhibitor. This indicates the inhibitor's potential to extend the service life of gearbox and substation foundations exposed to chloride ion erosion environments.

Potentiometric Application of CeFeMoP and CeAlMoP in Zr(IV) Ions Analysis: A Comparative Study

Two cerium-based ionophores Cerium(III) ironmolybdophosphate (CeFeMoP) and Cerium(III) aluminomolybdophosphate (CeAlMoP), were synthesised, having ion exchange capacities of 5.76±0.1 and 5.6±0.2 meq/gm respectively. Electroanalytical studies of synthesised heteropolyacid salts have been done using epoxy resin as binder material to form membranes of variable compositions. The potentiometric observation supports the behaviour of 40% membrane in both cases. CeFeMoP-based electrode showed a linear range from concentration 1x10-6 to 1x10-1 M and a limit of detection 6.31×10-7 M. In contrast, these parameters in the case of CeAlMoP are of linear range from 1x10-7 M to 1x10-1 M, response time 22 seconds and a limit of detection 5.01 × 10-7 M. Membranes yielded a rapid response time of 15 seconds in the case of CeFeMoP. The membranes performed very well in the case of internal concentration variations of the same solution and several other types of non-aqueous media. The FIM method proves the selectivity of the electrode even in the presence of interfering ions. CeFeMoP based sensor performed over a constant potential behaviour in pH values ranging between 3.32-8.26 while CeAlMoP based electrode worked in the pH range of 3.25-10.54 for a constant internal concentration of Zr(IV) ions. The two sensors also performed well as indicator electrodes as well as in real-time sample analysis. Hence, it is concluded that these sensors derived from CeFeMoP and CeAlMoP are quite effective in analyzing the Zr(IV) ions in various samples with quick response time and a lifetime of around 8 and 7 months respectively. A real field study was also performed by using an ICP-MS analyzer.

Global and local breakthrough curves: A concept for filtration design through analysis of internal concentration distribution using CFD

Evaluating the filtration performance of a filter design traditionally relies on a global breakthrough curve, which represents changes in outlet concentration over time. This curve does not account for adsorption phenomena inside the filter, often necessitating trial-and-error experimentation for optimizing filter shape. To address this issue, we introduce an innovative approach that employs computational fluid dynamics (CFD) to define local breakthrough curves. These curves represent concentration changes over time at specific points within the filter. By comparing these local breakthrough curves with the conventional global breakthrough curve, we aim to enhance the precision of filter designs. This optimization strategy seeks to achieve shapes that meet predetermined performance targets or improve the efficiency of existing filters. Utilizing CFD-generated local breakthrough curves in the optimization process enables the prediction of essential filter elements required to meet specified performance criteria, such as height and thickness. Moreover, this method identifies underperforming areas in existing filters and suggests strategic avenues for improvement. Our results underscore the utility of CFD-informed local breakthrough curves as invaluable tools for streamlining the filter design optimization process.

From hazard to risk prioritization: a case study to predict drug-induced cholestasis using physiologically based kinetic modeling

Cholestasis is characterized by hepatic accumulation of bile acids. Clinical manifestation of cholestasis only occurs in a small proportion of exposed individuals. The present study aims to develop a new approach methodology (NAM) to predict drug-induced cholestasis as a result of drug-induced hepatic bile acid efflux inhibition and the resulting bile acid accumulation. To this end, hepatic concentrations of a panel of drugs were predicted by a generic physiologically based kinetic (PBK) drug model. Their effects on hepatic bile acid efflux were incorporated in a PBK model for bile acids. The predicted bile acid accumulation was used as a measure for a drug’s cholestatic potency. The selected drugs were known to inhibit hepatic bile acid efflux in an assay with primary suspension-cultured hepatocytes and classified as common, rare, or no for cholestasis incidence. Common cholestasis drugs included were atorvastatin, chlorpromazine, cyclosporine, glimepiride, ketoconazole, and ritonavir. The cholestasis incidence of the drugs appeared not to be adequately predicted by their Ki for inhibition of hepatic bile acid efflux, but rather by the AUC of the PBK model predicted internal hepatic drug concentration at therapeutic dose level above this Ki. People with slower drug clearance, a larger bile acid pool, reduced bile salt export pump (BSEP) abundance, or given higher than therapeutic dose levels were predicted to be at higher risk to develop drug-induced cholestasis. The results provide a proof-of-principle of using a PBK-based NAM for cholestasis risk prioritization as a result of transporter inhibition and identification of individual risk factors.

Optimization the growth and quality of ‘Picual’ olive plants according to the dose of slow-release fertilizer

Due to its importance for oil production in Brazil and worldwide, the ‘Picual’ olive trees deserves special attention of to its good climatic adaptation and high yield and stability in the oil produced. However, there is a need to generate more technical information to improve the propagation and production system for nursery plants. The use of slow-release fertilizer (SRF) affects the quality standard of the plants formed in the nursery. The purpose of this study was to evaluate the effect of doses (0, 1.5, 3.0, 6.0, and 12 g L−1) of the SRF, Osmocote® (NPK 14-14-14), on morphological, biochemical and nutritional parameters of ‘Picual’ olive plants. It was found that the average value of maximum technical efficiency dose (MTED) for several morphological variables (plant height, stem diameter, total plant dry weight and root volume) was 7.18 g L−1. Furthermore, an Osmocote® dose of 8.35 g L−1 resulted in optimal leaf number and area. For the carbohydrate concentration (sucrose, starch and Total Soluble Sugar) in leaves, the best average values were obtained at 4.51, 5.48 and 6.12 g L−1 of Osmocote®, respectively. Additionally, the best growth responses of plants may also be due to increased internal macronutrient concentration such as nitrogen (N), phosphorus (P) and potassium (K) after treatment with 7.87 g L−1 of Osmocote®. The use of SRF (Osmocote®) is a viable alternative in the production of ‘Picual’ plants, as it promotes good morphological characteristics, synthesis of photosynthetic products as well as satisfactory nutritional status and plant growth.

Adaptive state-of-health temperature sensitivity characteristics for durability improvement of PEM fuel cells

To obtain the temperature sensitivity characteristics of the proton exchange membrane fuel cell under different degradation levels, accelerated durability tests and temperature sensitivity tests of the fuel cell are first performed, and the temperature characteristics under different degradation states are analyzed by electrochemical impedance spectroscopy and polarization curve. Besides, an adaptive state-of-health transient thermal model of fuel cells is developed to investigate the effect of operating temperature on the internal gas concentration and hydrothermal distribution characteristics of the fuel cell from a mechanistic perspective. The experimental results of temperature sensitivity validate that the adaptive state-of-health transient thermal model can effectively monitor the steady and transient performance of the fuel cell. Subsequently, a mathematical model is proposed to describe the relationship among the load current, state of health, and optimal temperature using the temperature sensitivity test data and the transient thermal model of the adaptive state of health, which provides important insights into the optimal temperature range tailored to the current state of health of fuel cells to ensure efficient and stable operation of fuel cells all the time and contributes to the fine design of an optimal degradation adaptive temperature control strategy.

Accurate photosynthetic parameter estimation at low stomatal conductance: effects of cuticular conductance and instrumental noise

Accurate estimation of photosynthetic parameters is essential for understanding plant physiological limitations and responses to environmental factors from the leaf to the global scale. Gas exchange is a useful tool to measure responses of net CO2 assimilation (A) to internal CO2 concentration (Ci), a necessary step in estimating photosynthetic parameters including the maximum rate of carboxylation (Vcmax) and the electron transport rate (Jmax). However, species and environmental conditions of low stomatal conductance (gsw) reduce the signal-to-noise ratio of gas exchange, challenging estimations of Ci. Previous works showed that not considering cuticular conductance to water (gcw) can lead to significant errors in estimating Ci, because it has a different effect on total conductance to CO2 (gtc) than does gsw. Here we present a systematic assessment of the need for incorporating gcw into Ci estimates. In this study we modeled the effect of gcw and of instrumental noise and quantified these effects on photosynthetic parameters in the cases of four species with varying gsw and gcw, measured using steady-state and constant ramping techniques, like the rapid A/Ci response method. We show that not accounting for gcw quantitatively influences Ci and the resulting Vcmax and Jmax, particularly when gcw exceeds 7% of the total conductance to water. The influence of gcw was not limited to low gsw species, highlighting the importance of species-specific knowledge before assessing A/Ci curves. Furthermore, at low gsw instrumental noise can affect Ci estimation, but the effect of instrumental noise can be minimized using constant-ramping rather than steady-state techniques. By incorporating these considerations, more precise measurements and interpretations of photosynthetic parameters can be obtained in a broader range of species and environmental conditions.

Impact of Photosynthetic Efficiency on Watermelon Cultivation in the Face of Drought

Water availability is a limiting factor for plant production, especially in Brazilian semi-arid regions. The main aim of the study was to investigate the physiological effects of drought during the fruiting stage of watermelon cultivation. A completely randomized block design with four replications and six treatments varied by the number of lateral drip tapes (1 or 2) and the duration of drought stress (0, 4, and 8 days) was used. The following parameters were evaluated: relative chlorophyll content, relative leaf water content, electrolyte leakage, CO2 assimilation (A), stomatal conductance (gs), internal CO2 concentration, leaf temperature, transpiration (E), water use efficiency (WUE), carboxylation efficiency (CE), yield, thickness, diameter, length, and fruit °brix, at 4 and 8 days of drought. Drought negatively affected photosynthesis, particularly in treatments with a single dripper and 4 days of drought, resulting in reductions of up to 60% in A, 68% in gs, 44% in E, 58% in WUE, and 59% in CE, but did not have a significant effect on watermelon yield after 4 or 8 days of irrigation. It was concluded that drought influences the physiological responses of watermelon plants, mainly in reducing photosynthesis, but does not drastically affect fruit productivity in short periods of stress.

Morpho-physiological responses of potato cultivars under weed competition

Morpho-physiological responses of potato cultivars under weed competition