Saturation Curve Research Articles

Accurate determination of water saturation in tight sandstone gas reservoirs based on optimized Gaussian process regression

Tight sandstone gas is an important field for the future development of the oil and gas industry. In the tight gas reservoir of Penglaizhen Formation in Shifang gas field, the water saturation (Sw) of sealed coring cores and the NMR irreducible Sw of conventional cores are measured by using the reservoir physical property tester and NMR analyzer. Combined with the scanning electron microscope results, the reservoir has the characteristics of complex pore structure and high-water saturation. The calculation of Sw by Archie formula, Density log, and φD-φN has a large error. Therefore, how to accurately calculate Sw is an outstanding problem that needs to be resolved. In this paper, we selected AC, EDN, XI, and φe as the parameters for modeling. We have proposed the optimized Gaussian process regression (GPR) method to calculate the Sw of tight sandstone reservoirs. The water saturation curve calculated by the optimized GPR model is in good agreement with the core saturation value. In the error results of well data in the study area, it was found that the relative error and root-mean-square error of the optimized GPR model were the lowest, and it had better calculation accuracy. In addition, in the error results of the nuclear magnetic core samples, it was also found that the optimized GPR model's MMRE was 6.65% and the RMSE was 4.95. In tight sandstone reservoirs with complex pore structure and high-water saturation, the optimized GPR model is helpful to reduce the influence of reservoir shale characteristics, low resistivity characteristics and hidden information of parameter data during the calculation of Sw. It can calculate Sw more efficiently and reflect the characteristics of irreducible Sw more accurately. The optimized GPR model developed for water saturation calculation has broad application prospects.

Peaksat: an R package for ChIP-seq peak saturation analysis

BackgroundEpigenomic profiling assays such as ChIP-seq have been widely used to map the genome-wide enrichment profiles of chromatin-associated proteins and posttranslational histone modifications. Sequencing depth is a key parameter in experimental design and quality control. However, due to variable sequencing depth requirements across experimental conditions, it can be challenging to determine optimal sequencing depth, particularly for projects involving multiple targets or cell types.ResultsWe developed the peaksat R package to provide target read depth estimates for epigenomic experiments based on the analysis of peak saturation curves. We applied peaksat to establish the distinctive read depth requirements for ChIP-seq studies of histone modifications in different cell lines. Using peaksat, we were able to estimate the target read depth required per library to obtain high-quality peak calls for downstream analysis. In addition, peaksat was applied to other sequence-enrichment methods including CUT&RUN and ATAC-seq.Conclusionpeaksat addresses a need for researchers to make informed decisions about whether their sequencing data has been generated to an adequate depth and subsequently sufficient meaningful peaks, and failing that, how many more reads would be required per library. peaksat is applicable to other sequence-based methods that include calling peaks in their analysis.

Association between total cholesterol and total bone mineral density in US adults: National Health and Nutrition Examination Survey (NHANES), 2011–2018

BackgroundAccumulated evidence indicates that cholesterol is offensive to bone metabolism. Therefore, we examined the real-world study among total cholesterol and total bone mineral density (BMD). We investigated the relationship between total cholesterol and total BMD among 10,039 US participants aged 20–59 years old over the period 2011–2018 from the NHANES.MethodsTo analyze the relationship among total cholesterol and total BMD, multivariate linear regression models were used. Fitted smoothing curves, generalized additive models, and threshold effect analysis were also conducted.ResultsAfter adjusting for additional covariates, weighted multivariable linear regression models indicated total cholesterol concentration levels exhibited a negative relationship with total BMD, particularly among participants aged 20–29 years. Concerning subgroup analysis, stratified by gender, race/ethnicity and age group, the negative correlation of total cholesterol with total BMD dwelled in both female and male as well as in whites and other races (including Hispanic and Multi-Racial), but not in non-Hispanic blacks and Mexican American. In other races, this relationship presented a nonlinear association (inflection point: 6.7 mmol/L) with a U-shaped curve. Among participants aged 40 to 49 years, this relationship also followed a nonlinear association (inflection point: 5.84 mmol/L), indicating a saturation effect. Moreover, the three types of diabetes status were found to have negative, U-shaped, and positive relationships. In participants with borderline diabetes status, the relationship of total cholesterol with total BMD was a U-shaped curve (inflection point: 4.65 mmol/L).ConclusionsFor US young adults (20–29 years old), our study revealed a negative relationship between total cholesterol and total BMD. This association followed a U-shaped curve (inflection point: 4.65 mmol/L) in borderline diabetes status participants, a saturation curve (inflection point: 5.84 mmol/L) in participants aged 40–49 years and a nonlinear curve (inflection point: 6.7 mmol/L) in other races (including Hispanic and Multi-Racial). Therefore, keeping total cholesterol concentration at a reasonable level for young adults and diabetic population might be an approach to prevent osteoporosis or osteopenia.

Phytate-Induced Dose-Response Auto-Activation of Enzyme in Commercial Recombinant Phytase From Escherichia coli.

Microbial phytase is one of the most widely used enzymes in food industries like cattle, poultry, and aquaculture food. Therefore, understanding the kinetic properties of the enzyme is very important to evaluate and predict its behavior in the digestive system of livestock. Working on phytase is one of the most challenging experiments because of some problems, including free inorganic phosphate (FIP) impurity in phytate (substrate) and interference reaction of the reagent with both phosphates (product and phytate impurity). In the present study, FIP impurity of phytate was removed, and then it was shown that the substrate (phytate) has a dual role in enzyme kinetics: substrate and activator. phytate impurity was decreased by two-step recrystallization prior to the enzyme assay. The impurity removal was estimated by the ISO30024:2009 method and confirmed by Fourier-transform infrared (FTIR) spectroscopy. The kinetic behavior of phytase activity was evaluated using the purified phytate as substrate by non-Michaelis-Menten analysis, including Eadie-Hofstee, Clearance, and Hill plots. The possibility of an allosteric site on phytase was assessed by molecular docking. The results showed a 97.2% decrease in FIP due to recrystallization. The phytase saturation curve had a sigmoidal appearance, and Lineweaver-Burk plot with a negative y-intercept indicated the positive homotropic effect of the substrate on the enzyme activity. A right-side concavity of Eadie-Hofstee plot confirmed it. Hill coefficient was calculated to be 2.26. Molecular docking also showed that Escherichia coli phytase molecule has another binding site for phytate very close to the active site, called "allosteric site". The observations strongly propose the existence of an intrinsic molecular mechanism in Escherichia coli phytase molecules to be promoted for more activity by its substrate, phytate (positive homotropic allosteric effect). In silico analysis showed that phytate binding to the allosteric site caused new substrate-mediated inter-domain interactions, which seems to lead to a more active conformation of phytase. Our results provide a strong basis for animal feed development strategies, especially in the case of poultry food and supplements, regarding a short food passage time in their gastrointestinal tract and variable concentration of phytate along with it. Additionally, the results strengthen our understanding of phytase auto-activation as well as allosteric regulation of monomeric proteins in general.

Quantitative assessment of intracellular/extracellular dimethyl sulfoxide concentrations during freezing with low-temperature confocal Raman micro-spectroscopy.

Although cryopreservation plays an indispensable role in the clinical application of cell therapy, the research on the osmotic behavior of cells during freezing is still at the level of theoretical models, and quantitative experimental data are still lacking. Therefore, the Raman spectra of dimethyl sulfoxide (DMSO) solutions with different standard concentrations (5%-80% v/v) were recorded experimentally to establish a quantitative evaluation method with the intensity ratio of different labeled peaks to the hydrogen bonding peak (as the internal standard) of water molecules in relation to different DMSO concentrations. By using this method, the characteristics of quantitative changes in intra- and extracellular concentrations under three different freezing methods were explored, including direct freezing, ice seeding freezing and vitrification. It was found that the intracellular concentration (@ -50 °C) after the ice seeding (@ -7 °C) freezing (1 °C min-1) method could reach 41.6%-49.2%, significantly higher than that of the direct freezing method (1 °C min-1 to -50 °C) of 32.4%-39.1%. Moreover, it is worth noting that the quantitative values of concentrations (@ -50 °C) of the ice seeding freezing are more consistent with the primary saturation curve of the DMSO solution. Thus, for the first time, it was revealed from the experimental data that the fundamental reason for the improvement of cell survival after ice seeding operation was pre-dehydration, higher concentration and smaller osmotic pressure difference between the inside and outside of the cell. These results also confirmed the validity of the famous two-factor hypothesis and more work will be carried out in depth.

Late Shelf Life Saturation of Golden Delicious Apple Parameters: TSS, Weight, and Colorimetry

This work aims to estimate the shelf life of Golden Delicious apple fruit stored at room temperature by determining the changing trend in color every week using a non-destructive measurement method. Moreover, the study will measure the changes in weight loss (Δm) and the total soluble solids (TSS) contained in the apple. The research focuses on the last stage of ripening and the effect of shelf life affecting consumer behavior; therefore, the examined fruits were picked at the end of the season and were stored at an ambient temperature and in controlled laboratory conditions for six weeks, at 24 °C under 60% RH relative. Color measurements were performed with a portable color sensor, which provided a simple and effective examination method in the case of an appropriate number of fruit samples. The findings showed a significant increase in TSS and weight loss over time. Color varying (ΔE) and chroma (C*) parameters increased with prolonged storage duration, meaning that the color of the apples became darker and more color-saturated at the end of storage. While weight loss and TSS follow a linear tendency in the given storage period, the color changes in deteriorating fruits were characterized by exponential asymptotic regression. It was found that although the moisture content reaches its limit value during the drying process of apples, the saturation of color coordinates allows for determination of the limit parameters of consumption in the linear stage of weight loss. The saturation limits (70.97; 12.77; 56.34 CIELAB L*; a*; b*), the dominant color part (b*), and the growth rate of the saturation curves allow an accurate characterization of ripening from the visual aspect, thus determining the limit parameters of shelf life and improving the critical analysis factors affecting the life of fruits after harvest. By assessing color characteristics using a non-destructive technology, customers may quickly evaluate the quality of apples and make better decisions during their purchase.

Analyzing a Saturation Effect of Nitrogen Fertilization on Baking Volume and Grain Protein Concentration in Wheat

Some wheat cultivars show a linear relationship between grain protein concentration (GPC) and baking volume, but others display a saturation curve. Such a saturation curve could be general, but in some cultivars it might only appear at GPC > 17%. However, such GPC is mostly not achieved in the field. Pot experiments with high nitrogen application reliably result in GPC > 17%. In a pot experiment with a high (N1) and an excessive N level (N2) and four cultivars (Akteur, Arnold, Discus and Hystar), the change in grain protein composition and the relationship between different protein fractions and baking volume at GPC > 17% was investigated. GPC ranged from 17 to 24% and mean nitrogen content per grain from 1.2 to 1.8 mg. The N2 treatment increased GPC and mean nitrogen content per grain in the Akteur and Discus cultivar, but not in Arnold and Hystar. N2 increased concentration of gliadin by 10 to 34% and glutenin macropolymer (GMP) in all cultivars by 12 to 73%. Glutenin concentration was increased by N2 in Akteur and Discus (19 to 36%), but was decreased by N2 in the Arnold and Hystar cultivar. Baking volume was moderately increased by N2 in all cultivars by 6 to 9% and correlated significantly with most glutenin fractions in the Akteur and Discus cultivar, with GMP in Arnold and with HMW-GS to LMW-GS ratio in Hystar. Thus, specific effects on grain protein by N2 were responsible for the increased baking volume in each cultivar. However, as gliadin and its sub-fractions hardly correlated with baking volume, a positive effect of increasing gliadin proteins on baking quality was not obvious.

Vaporization thermodynamics of normal alkyl phenones

In this work, the literature data, experimental measurements and structure–property relationships were combined to obtain reliable vaporization characteristics of the homologous series of linear alkyl phenones. We critically analyzed the available literature vapor pressures and vaporization enthalpies of acetophenone, propiophenone, and heptanophenone, performed vapor pressure measurements of hexano-, octano- (by transpiration method) and octadecanophenone (by TG-FSC method) and established a linear dependence of the enthalpy and Gibbs free energy of vaporization on the chain length. These quantities in combination with the Clarke-Glew equation enable accurate estimation of P – T dependences along the saturation curve. The quantities obtained were verified by comparison between the calculated and experimental data for the less studied homologs and showed quality comparable with the experiment.

Role of facies cycles on the mid-upper Cretaceous Bangestan Reservoir rock typing in the Zagros Basin

The principal objectives of this research were to examine the role of sedimentary cycles and tectonics in the Ahwaz Bangestan Reservoir quality, view the vertical and lateral changes of these sedimentary cycles, and identify rock typing units. There is an urgent need to understand how interpretive data are perceived among diagenetic events, sedimentary cycles, exposure surfaces, disconformities, carbonate fabric units, porosity-permeability relationship, wettability index, and relative permeability and capillary pressure vs. saturation curves. The Ahwaz Bangestan Sequence consists of Ilam and Sarvak Formations from the late Albian to Santonian Stages, in which disconformity surfaces separated the third-order sequences. Early diagenetic processes of the Bangestan sequence include meteoric dissolution and the deposit of marine cement. The meteoric diagenesis plays an essential role in the reservoir quality of these sequences and sedimentary cycles, and the burial cement process reduces the Bangestan Reservoir quality. The Bangestan sediments experience significant disconformity surfaces in the upper Cenomanian and Post-Turonian Stages. Meteoric waters affect these exposure surfaces to 50 m, increase porosity by about 15%, and have a permeability of 5 mD. With this, the results showed that there is a positive relationship between permeability and porosity data of the Bangestan sedimentary facies. In this regard, grainstone and packstone facies in the Ilam Formation demonstrated a higher reservoir quality than other facies, except for secondary chalky facies in Zone C1, where severe meteoric diagenesis occurred before lithification. Besides, the sedimentary model of the Bangestan Reservoir revealed six facies association, including tidal flat, lagoon, back shoal, rudist biostorm, shoal, and deep-marine with terrigenous layers. Given rock typing classification, four geological static rock typing (GSRT) were recognized with good correlation among lagoon, back shoal, rudist biostorm, and shoal facies association. The results demonstrated a positive relationship between permeability and porosity characteristics, leading to higher porosity and permeability in facies association of shoal and rudist biostorm with better GSRT. Besides, facies association of back shoal and lagoon with lower porosity and permeability represented worse GSRT. However, due to different diagenesis events, open-marine facies did not follow an adequate GSRT. Furthermore, three oil-wet geological dynamic rock typing (GDRT) and two water-wet GDRTs were identified, indicating the dynamic behavior of facies association. As a result, facies association with better reservoir quality (i.e., higher permeability and porosity) present higher GDRT, while facies association with worse reservoir quality (i.e., lower permeability and porosity) show lower GDRT.

Reduction of recombination effects in large plane parallel beam monitors for FLASH radiotherapy with scanned ion beams

Purpose:Radiotherapy escalating dose rates above 50Gys−1, might offer a great potential in treating tumours while further sparing healthy tissue. However, these ultra-high intensities of FLASH-RT lead to new challenges with regard to dosimetry and beam monitoring. FLASH experiments at HIT (Heidelberg Ion Beam Therapy Center) and at GSI (GSI Helmholtz Centre for Heavy Ion Research) have shown a significant loss of signal in the beam monitoring system due to recombination effects. To enable accurate beam monitoring, this work investigates the recombination loss of different fill gases in the plane parallel ionisation chambers (ICs). Methods:Therefore, saturation curves at high intensities were measured for the currently used fill gases Ar/CO2 (80/20) and pure He and also for He/CO2 mixtures as alternative fill gases. Furthermore, breakdown voltages and ion mobilities were measured in ICs filled with He/CO2 mixtures. A numerical model for volume recombination in plane parallel ionisation chambers was developed and implemented in Python. This includes a novel simulation method of the space charge effect from the charge carriers in the detector volume and predicts a significant effect on the electric field for high intensity beams. Results:Even at high intensities the He/CO2 mixtures allow operation of the ICs at an electric field strength of 2 kVcm−1 or more which reduces recombination to negligible levels at intensities larger than 3 × 101012C-ions per second. Our measurements show that added fractions of CO2 to He decrease the ion mobility in the fill gas but significantly increase the breakdown voltage in the ICs compared to pure He.

CORRELATION BETWEEN OXYGEN SATURATION OF BLOOD AND FRONTAL TEMPERATURE IN SCREENING FOR COVID-19 IN A TERTIARY HEALTH CARE CENTRE

As the COVID19 cases with new variants are on the rise, methods to screen individuals before entering a hospital or public areas have become pivotal for the control of its spread. For these cases noncontact frontal temperature readings by infrared thermometers are widely used in many places. But the accuracy and reliability of these are questionable due to the environmental interractions, which were corrected by the use of pulse oximeters. Pulse oximeters transcutaneously measure the functional oxygen saturation of arterial blood (PaO2). This is simply a reection of oxygen saturation curve. In patients with a baseline SO2 of 91% at body temperature of 370C, an increase in body temperature to 400C is anticipated to cause a 5% decrease in SO21. This decrease has major potential implication concerning diagnosis.

The Influence of Evaporation and Seasonal Effects on the Water Content in the Unsaturated Zone: A Multi-Year Laboratory Study

The unsaturated zone of the subsurface plays a critical role in the environmental fate and transport of a wide range of environmental contaminants, and is also important for plant growth and agriculture. Quantitative prediction of processes in the unsaturated zone requires knowledge of how water content varies with elevation above the water table, a relationship known as the capillary pressure (Pc)–saturation (S) relationship. While the Pc–S relationship is conventionally thought of as being primarily a property of the porous medium and fluids, previous work found evidence suggesting that it actually results from a dynamic equilibrium between capillary forces and phenomena driven by evaporation. The focus of this work was on gaining a further understanding of the role of evaporation on the Pc–S relationship. The work made use of a tall instrumented laboratory column connected to an external reservoir for maintaining water table height. Following an initial imbibition experiment, the column was saturated and allowed to drain, and then water content was monitored in the column as a function of height over 1207 days (3.31 years). While initial imbibition and drainage were rapid, on the order of hours, redistribution and evaporation effects became apparent over longer time scales (hundreds of hours). A drying front moving downward in the column was apparent from changes in the slopes of saturation vs. time curves as it passed individual sensors; unlike previous experiments with a more fully-vented column, the evaporation front appeared to stall, balanced by the capillary-driven upward flow of water. Over the full multi-year duration of the experiment, seasonal trends in water saturation were apparent, with significant, reversible variations observed that closely followed atmospheric conditions. Specifically, saturation above the water table appeared to increase during the spring and summer months and decrease during the fall and winter months, despite the constant water table location, consistent with a changing driving force for evaporation. This result may suggest the likelihood of seasonal effects in the long-term transport and fate of contaminants in the unsaturated zone.

Optimizing Aluminum Oxyhydroxide Vapor Phase Infiltration for the Vapor Phase Mordanting of Natural Dyes to Polyester Fabrics

Industrial textile dyeing and finishing processes are a significant environmental concern producing large quantities of wastewater that require significant treatment to remove unused synthetic chemicals. Polyester fabrics in particular utilize high temperatures and chemical carrier agents in their dyeing processes. In this work, we present a method for attaching natural dye materials derived from madder root to polyethylene terephthalate fabrics via the introduction of aluminum oxyhydroxides through vapor phase infiltration. Vapor phase infiltration (VPI) is an emerging polymer modification technique that exposes a polymer to metalorganic precursors that diffuse into the polymer and become entrapped as inorganic clusters. The resulting hybrids have unique properties of both organic and inorganic materials. The VPI process has found significant use in modifying the properties of textile materials including their mechanical and optical properties. Here, without VPI treatment, the PET fabric cannot be dyed with this natural dye. This talk will discuss how controlling the inorganic loading of hybrid AlOx-PET fabrics infiltrated with trimethylaluminum (TMA) and co-reacted with water vapor at 80 ˚C and 140 ˚C can optimize fabrics for dyeability while minimizing impact on key fabric mechanical properties. At low temperatures (80 ˚C) the resulting hybrid contains inorganic clusters not strongly bound to the polymer chain while at high temperatures (140 ˚C) the inorganic is chemically bound via the carbonyl group. Inorganic loading was controlled by varying the dose pressure of TMA (moles of TMA) and fabric mass (moles of carbonyl functional group) during VPI and quantified using thermogravimetric analysis (TGA). The resulting hybrid AlOx-PET fabrics had various inorganic loadings from one weight percent aluminum oxyhydroxide to above twenty weight percent. The hybrid fabrics were then dyed with Alizarin (derived from madder root) and the dye absorbance was quantified with UV-Vis spectroscopy. At low inorganic loadings for both temperatures, the strength of color varied with inorganic content, but a steady-state absorbance was reached at around 1.8 percent inorganic loading. At these low inorganic loadings, the hybrid fabrics maintain key mechanical behaviors such as stiffness (as measured by drape) which is seen to increase significantly with additional inorganic loading. In addition to optimizing strength of color and fabric stiffness, the time to dye saturation was also explored by varying dye times and quantifying with UV-Vis. By exploring dye saturation curves for different inorganic loadings and infiltration temperatures, kinetic information was gathered to further optimize this dyeing process for industrialization. Overall, using VPI as a vapor phase mordanting process to fix natural dyes to PET fabrics illustrates the impact that even small quantities of the vapor deposited inorganic can create enough of a base for dye to adhere to, highlighting the practical use of these fabrics in the field of textile sustainability.

Effects of Enzymatically Induced Carbonate Precipitation on Capillary Pressure–Saturation Relations

Leakage mitigation methods are an important part of reservoir engineering and subsurface fluid storage, in particular. In the context of multi-phase systems of subsurface storage, e.g., subsurface CO2 storage, a reduction in the intrinsic permeability is not the only parameter to influence the potential flow or leakage; multi-phase flow parameters, such as relative permeability and capillary pressure, are key parameters that are likely to be influenced by pore-space reduction due to leakage mitigation methods, such as induced precipitation. In this study, we investigate the effects of enzymatically induced carbonate precipitation on capillary pressure–saturation relations as the first step in accounting for the effects of induced precipitation on multi-phase flow parameters. This is, to our knowledge, the first exploration of the effect of enzymatically induced carbonate precipitation on capillary pressure–saturation relations thus far. First, pore-scale resolved microfluidic experiments in 2D glass cells and 3D sintered glass-bead columns were conducted, and the change in the pore geometry was observed by light microscopy and micro X-ray computed tomography, respectively. Second, the effects of the geometric change on the capillary pressure–saturation curves were evaluated by numerical drainage experiments using pore-network modeling on the pore networks extracted from the observed geometries. Finally, parameters of both the Brooks–Corey and Van Genuchten relations were fitted to the capillary pressure–saturation curves determined by pore-network modeling and compared with the reduction in porosity as an average measure of the pore geometry’s change due to induced precipitation. The capillary pressures increased with increasing precipitation and reduced porosity. For the 2D setups, the change in the parameters of the capillary pressure–saturation relation was parameterized. However, for more realistic initial geometries of the 3D samples, while the general patterns of increasing capillary pressure may be observed, such a parameterization was not possible using only porosity or porosity reduction, likely due to the much higher variability in the pore-scale distribution of the precipitates between the experiments. Likely, additional parameters other than porosity will need to be considered to accurately describe the effects of induced carbonate precipitation on the capillary pressure–saturation relation of porous media.

Quantification of organic fluorophores in absorbing media by solid-phase fluorescence excitation–emission matrix (SPF-EEM) spectroscopy of modeled mixtures containing bovine serum albumin (BSA) and colorants

Solid-phase fluorescence excitation–emission matrix (SPF-EEM) spectroscopy is beneficial for investigating the characteristics of natural organic matter (NOM) in the solid phase without extraction procedures. However, inner filter effect (IFE) due to the presence of dark components in samples can make it difficult to quantify the fluorophore concentration. To establish a new method to determine unknown concentrations of a fluorescent material in a sample containing various absorbing materials by SPF spectroscopy, modeled mixtures containing bovine serum albumin (BSA) and colorants at different ratios were examined. Fluorescence intensities of BSA against various concentrations afforded different saturation curves for different colorants in the mixtures, suggesting that it is difficult to use the SPF intensity for quantifying the concentration of fluorescent samples in which IFE has occurred, because one cannot obtain a single calibration curve that does not depend on the absorbing medium that it is mixed in. However, products of the fluorescence intensity and Kubelka–Munk (KM) function at the excitation wavelength were proportional to the first order of BSA weight concentrations, regardless of the colorant type. By using this trend as a calibration curve, it may be possible to quantify the amount of BSA from its SPF-EEM spectrum. In this study, the KM function was obtained using an ultraviolet–visible (UV–Vis) spectrometer with an integrating sphere. To reduce the labor and equipment cost of UV–Vis spectroscopy, a substrate of the KM function also was obtained from the Rayleigh scattering in an SPF-EEM spectrum, which could be used as a parameter for calibration curves that quantify the BSA concentration. Although further studies are required, this study proposed that the product of the SPF intensity and KM function at the excitation wavelength can be partially used for an empirical formula to quantify a variety of fluorescent materials mechanically mixed with various absorbing materials.

Dynamic response characteristics of oil and water distribution during the shut-in period after hydraulic fracturing in shale oil reservoirs

Compared with conventional reservoirs, shale reservoirs are more difficult to develop due to their characteristics of self-generation and self-storage and tightness. Based on the experience accumulated in production practice, the technical method of improving shale oil development through shut-in is put forward. The literature research on shale reservoirs shows that there is a lack of microscopic study on imbibition, the essence of oil–water exchange is not clear enough, and there is a lack of the systematic summary and induction of theoretical knowledge. This article starts from the background of shut-in stimulation of Gulong shale oil, conducts literature research on the related knowledge of shut-in of shale oil from three aspects: characterization of fracture network, shut-in mechanism, and oil and water distribution state, and summarizes the law of shut-in of shale oil in a microscopic aspect. On this basis, a dual-porosity numerical simulation model is established according to the geological and fluid characteristics of the Gulong shale oil reservoir. Through the simulation of a numerical simulation model, the water saturation and pressure maps of the matrix and lamellation-fracture system in the process of shut-in were obtained. It was found that the matrix system basically did not participate in the oil–water exchange in the process of shut-in, so in the subsequent characteristic curve analysis, only the lamellation-fracture system was mapped and analyzed. The water saturation and pressure curves of different distances of the main fracture at different times were made, and it was found that the water saturation and pressure in the main fracture and near fracture areas were higher, and the change was more obvious than that in the far. Thus, the pressure drop curves of the near fracture were used to analyze the flow stage of the fluid. The single variable method is used to analyze the influencing factors from two aspects: the fracture density and permeability of the stimulated zone. The results will give a better understanding of the oil and water distribution during shut-in and guide the duration of shut-in in shale oil reservoirs.

Dosimetry and microdosimetry of monoenergetic neutrons using recombination chamber – Measurements and Monte Carlo simulations

The REM-2 tissue-equivalent recombination chamber was used for dosimetry measurements performed in monoenergetic neutron reference fields at National Physical Laboratory, UK for the neutron energy range from 144 keV to 5 MeV. Measurement data were used for the determination of the recombination index of radiation quality, ambient dose, and finally ambient dose equivalent, H*(10). Results justify the relevance of the application of this measuring method in mixed radiation fields with dominant neutron component, which are present, for example, at photon and proton radiotherapy facilities. The relative response of the chamber in terms of H*(10) in the investigated neutron energy range, resulted in the correction factor at the maximum level of 1.25. Analysis of the saturation curves and use of the recombination microdosimetric method, RMM resulted in the determination of dose distribution at a nanometric level in terms of restricted linear energy transfer, LΔ. Monte Carlo simulations performed with the FLUKA code allowed to obtain double-differential distributions of L which were compared with those obtained during measurements. Comparison between measured and simulated data showed that RMM is a reliable method for microdosimetric investigations in mixed neutron-gamma fields present around medical radiotherapeutic units.

Impaired pancreatic beta-cell function after a single dose of oral iron: A before-and-after (pre-post) study.

Although in vitro and animal studies have shown that iron loading in pancreatic beta cells impairs insulin secretion, no human studies have documented the acute effects of oral iron on beta-cell insulin secretory capacity. In the present study, we determined beta-cell insulin secretory capacity at baseline and after a single oral dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy male individuals. Fifteen healthy male volunteers underwent an oral glucose tolerance test (OGTT) to document baseline glucose tolerance and insulin secretion kinetics (baseline OGTT). One week later, the same subjects underwent a second OGTT, 2 h after an oral dose of ferrous sulphate (120 mg of elemental iron) (post-iron OGTT). Changes in disposition index, insulin secretion kinetics, glucose tolerance, insulin resistance, insulin clearance and iron-related parameters in serum were determined. Compared to baseline OGTT, the areas under the curve (AUC) for serum iron and transferrin saturation increased by 125% and 118%, respectively, in the post-iron OGTT. The disposition index decreased by 20% (p = 0.009) and the AUC for glucose concentrations increased by 5.7% (p < 0.001) during the post-iron OGTT. The insulin secretion rate was marginally lower during the first hour (-3.5%, p = 0.63), but became significantly higher during the second hour (22%, p = 0.005) of the post-iron OGTT. Insulin resistance and insulin clearance rate were not affected by iron intake. The decrease in disposition index and glucose tolerance observed after the oral dose of iron points to an acute iron-induced impairment in pancreatic beta-cell insulin secretory capacity.

Numerical simulations of high viscosity DNAPL recovery in highly permeable porous media under isothermal and non-isothermal conditions

We developed a decimetric size model based on coupling generalized Darcy's law and heat-transfer equations to model viscous dense non-aqueous phase liquid (DNAPL) pumping through highly permeable porous media under non-isothermal conditions. The presence of fingering and non-wetting phase ganglia was modeled through an unsteady capillary diffusion coefficient and an arbitrary heterogeneous permeability field. The model was validated using existing experimental data of a simple case, an oil injection in a 2D tank packed with glass beads. Next, we compared the results of this model against a DNAPL extracting situation in the 2D tank to better understand the two-phase flow behavior in highly permeable porous media. We found that natural convection during heating plays an essential role in heat transfer, especially in the wetting phase zone. By adding the dynamic effect (unsteady conditions) we were better able to describe the presence of the ganglia in porous media. We observed good agreement between modeled and experimental oil saturation curves until the breakthrough point, with a mean relative error of about 10% for low and high flow rates, and 8% and 16% after breakthrough for low and high flow rates, respectively. Extracting viscous oil at low flow rates and high temperature generates less fingering and is well described by the generalized Darcy's law. The remobilization of residual non-wetting ganglia after the breakthrough point at the outlet is, however, difficult to simulate using the generalized Darcy's law. In the end, we treated this issue by using a perturbed permeability field to simulate the observed fingering in the 2D tank.

Investigation of heat and mass transfer and gas–liquid thermodynamic process paths in a humidifier

A humidifier is crucial for water evaporation in a humidification–dehumidification desalination system. Its performance has a significant impact on system efficiency. However, existing models are not fully applicable to the estimation of heat and mass transfer in a humidifier. In this paper, a novel gas–liquid heat and mass transfer model for a humidifier is proposed. It can accurately predict the heat and mass transfer performance in the humidifier. It is observed that increasing liquid inlet temperature improves the humidifier performance most significantly. In the humidifier, the temperature and humidity ratio of air increase in waves along the height. The distributions of the heat and mass transfer rates are primarily dominated by the transfer driving forces. Heat and mass transfer primarily occur at the top and bottom of the humidifier because of the considerable difference in the temperature and humidity ratio at the two terminals. The air rapidly reaches supersaturation during the heated and humidified processes, whereas the supersaturation is low, with the highest being 2.1%. The thermodynamic process path of air in the supersaturation stage can be simplified as lying on the saturation curve. The resulting error is less than 4%.