CO2 Fluid Research Articles

On the phase behaviors of CH4-CO2 binary clathrate hydrates: Equilibrium with aqueous phase.

We explore the solubilities of guest CH4 and/or CO2 in the aqueous state coexisting with the corresponding hydrate. The equilibrium conditions are estimated by calculating the chemical potentials of water and guest species in the hydrate on the basis of a statistical mechanical theory using pairwise intermolecular potentials. This requires the least computational cost while covering a wide range of temperature, pressure, and composition of guest species, even for the binary hydrate. The nonstoichiometric nature, one of the most important characters of hydrates, is invariably taken into account when evaluating its phase behaviors and the driving force for nucleation of hydrates. The two-phase equilibrium concerning CO2 hydrate is evaluated considering a low but finite value of CO2 solubility in water. It is found that the finite solubility gives rise to a small systematic deviation of the dissociation temperature of CO2 hydrate. The solubility of CO2 coexisting with fluid CO2 decreases with temperature but the opposite temperature dependence is obtained in the presence of hydrate, as in the case of CH4. This method is applied to CH4-CO2 binary hydrates of various guest compositions. We also find a significant difference in composition of guests among the phases involved in the equilibria.

Deep syntectonic burial of the Anthracite belt, Eastern Pennsylvania

Fluid inclusion microthermometry and Raman spectroscopy of fluid inclusions in quartz veins from the Pennsylvanian rocks of the Anthracite belt, eastern Pennsylvania support a deep burial model of coalification in favor of focused orogenic hot fluid flow. High-temperature (250 to 255 °C) trapping of CH4 ± CO2 saturated aqueous fluids and CH4 ± CO2 inclusions indicate fluid trapping at depths of 11.5 to 13.4 km under a cover of Pennsylvanian to Permian(?) syntectonic load. In the folded rocks to the south of the Anthracite belt, CH4 ± CO2 fluid inclusions indicate a sediment load that was up to 16.3 km thick. Re-equilibrated aqueous fluid inclusions from veins in Silurian through Devonian rocks give the same range of trapping conditions but a wide range of fluid salinities suggesting that folding, fracturing, and meteoric recharge resulted in the intermixing of fluids from throughout the stratigraphic succession.

Transport of Au–Ag Nanoparticles in Dense Carbon Dioxide Fluid of the Middle Crust

Individual fluid inclusions with dense carbon dioxide hosted in quartz from the gold-bearing interval penetrated by the SD-3 Kola Superdeep Borehole were studied using modern techniques. The composition and density of the carbon dioxide fluid were determined by Raman spectroscopy and microthermometry. The density of the fluid is 0.37–1.14 g/cm3 and contains minor admixtures of nitrogen (0.3–1.8 mol %) and water (0.1–0.4 mol %). LA-ICP-MS data indicate that the carbon dioxide fluid inclusions contain high concentrations of Au (1–2611 ppm) and Ag (1–4389 ppm), and high-precision optical data indicate that the high-density CO2 fluid of the inclusions contains Au–Ag nanoparticles. Evidently, gold and silver were transported from the Earth’s mantle to the crust by high-density carbon dioxide fluid in the form of nanoparticles.

Depths in a Day—a New Era of Rapid-Response Raman-Based Barometry Using Fluid Inclusions

Abstract Rapid-response petrological monitoring is a major advance for volcano observatories, allowing them to build and validate models of plumbing systems that supply eruptions in near-real time. The depth of magma storage has recently been identified as high-priority information for volcanic observatories, yet this information is not currently obtainable via petrological monitoring methods on timescales relevant to eruption response. Fluid inclusion barometry (using micro-thermometry or Raman spectroscopy) is a well-established petrological method to estimate magma storage depths and has been proposed to have potential as a rapid-response monitoring tool, although this has not been formally demonstrated. To address this deficiency, we performed a near-real-time rapid-response simulation for the September 2023 eruption of Kīlauea, Hawaiʻi. We show that Raman-based fluid inclusion barometry can robustly determine reservoir depths within a day of receiving samples—a transformative timescale that has not previously been achieved by petrological methods. Fluid inclusion barometry using micro-thermometric techniques has typically been limited to systems with relatively deep magma storage (>0.4 g/cm3 i.e. > 7 km) where measurements of CO2 density are easy and accurate because the CO2 fluid homogenizes into the liquid phase. Improvements of the accuracy of Raman spectroscopy measurements of fluids with low CO2 density over the past couple of decades has enabled measurements of fluid inclusions from shallower magmatic systems. However, one caveat of examining shallower systems is that the fraction of H2O in the fluid may be too high to reliably convert CO2 density to pressure. To test the global applicability of rapid response fluid inclusion barometry, we compiled a global melt inclusion dataset (>4000 samples) and calculate the fluid composition at the point of vapor saturation (${\mathrm{X}}_{{\mathrm{H}}_2\mathrm{O}}$). We show that fluid inclusions in crystal hosts from mafic compositions (<57 wt. % SiO2)—likely representative of magmas recharging many volcanic systems worldwide—trap fluids with ${\mathrm{X}}_{{\mathrm{H}}_2\mathrm{O}}$ low enough to make fluid inclusion barometry useful at many of the world’s most active and hazardous mafic volcanic systems (e.g. Iceland, Hawaiʻi, Galápagos Islands, East African Rift, Réunion, Canary Islands, Azores, Cabo Verde).

Fluorescence visualization dynamics of carbonated water injection processes in homogeneous glass micromodels

Understanding the flow behavior of oil–water phases in porous media is crucial for revealing the kinetic mechanisms underlying oil–water movement. In this study, we designed and constructed a fluorescence visualization experimental platform for carbonated water injection (CWI). We evaluated the effects of nine distinct injection rates on oil production and CO2 sequestration capabilities using three types of homogeneous porous structure micromodels. The microscale oil–water seepage behavior at the pore scale was also explored. The experimental results indicate that optimally increasing the injection rate can improve displacement efficiency, whereas excessively high rates may lead to viscous and capillary fingering. The geometry of the micromodels, particularly the hexagonal matrix, demonstrates potential advantages in enhancing oil displacement due to its uniform flow paths. The capillary number (Ca) significantly influences oil droplet capture behavior within micromodels. For instance, micromodel A captures the largest ganglion area at low Ca values, with a noticeable reduction in average ganglion area as Ca increases. Conversely, micromodels B and C exhibit similar trends in ganglion size variation at high Ca values, suggesting a more uniform impact of pore structure on oil droplet capture behavior. At elevated Ca values, capillary forces exert a more uniform and controlled effect on oil droplet capture and release, minimizing size variability. Additionally, the injection rate plays a critical role in CO2 sequestration, with higher rates promoting convective mixing between CO2 and reservoir fluids, thereby enhancing dissolution and storage efficiency. The complexity of the pore structure, characterized by the presence of micropores and macropores, affects the dissolution kinetics and mobility of CO2, influencing sequestration efficiency. These experimental findings provide valuable insights into the dynamics of oil–water motion and the potential for enhanced oil recovery (EOR) and CO2 storage, offering essential guidance for optimizing CWI strategies in the petroleum industry.

On the Significance of Hydrate Formation/Dissociation during CO2 Injection in Depleted Gas Reservoirs

Summary The study aims to quantitatively assess the risk of hydrate formation within the porous formation and its consequences on injectivity during storage of CO2 in depleted gas reservoirs considering low temperatures caused by the Joule-Thomson (JT) effect and hydrate kinetics. Hydrates formed during CO2 storage operation can occupy porous spaces in the reservoir rock, reducing the rock’s permeability and thus becoming a hindrance to the storage project. The aim was to understand which mechanisms can mitigate or prevent the formation of hydrates. The key mechanisms we studied included water dry-out, heat exchange with surrounding rock formation, and capillary pressure. A semicompositional thermal reservoir simulator is used to model the fluid and heat flow of CO2 through a reservoir initially composed of brine and methane. The simulator can model the formation and dissociation of both methane and CO2 hydrates using kinetic reactions. This approach has the advantage of computing the amount of hydrate deposited and estimating its effects on the porosity and permeability alteration. Sensitivity analyses are also carried out to investigate the impact of different parameters and mechanisms on the deposition of hydrates and the injectivity of CO2. Simulation results for a simplified model were verified with results from the literature. The key results of this work are as follows: (1) The JT effect strongly depends on the reservoir permeability and initial pressure and could lead to the formation of hydrates within the porous media even when the injected CO2 temperature was higher than the hydrate equilibrium temperature; (2) the heat gain from underburden and overburden rock formations could prevent hydrates formed at late time; (3) permeability reduction increased the formation of hydrates due to an increased JT cooling; and (4) water dry-out near the wellbore did not prevent hydrate formation. Finally, the role of capillary pressure was quite complex, as it reduced the formation of hydrates in certain cases and increased in other cases. Simulating this process with heat flow and hydrate reactions was also shown to present severe numerical issues. It was critical to select convergence criteria and linear system tolerances to avoid large material balance and numerical errors.

Characteristics of antimony mineralization in the Yangla polymetallic deposit, northwestern Yunnan, SW China: Insights from calcite Sm-Nd dating and C-O-Sr isotopes

Calcite is the main gangue mineral in antimony (Sb) deposits, and its compositions can reflect the physicochemical conditions of Sb mineralization. The Yangla is the largest Sb deposit (10 kt Sb @ 14.87 %) in the Jinshajiang suture zone (SW China), and the lode-type Sb orebodies are stratabound or developed along NE-trending fracture zones in marble. To constrain the time of Sb mineralization and establish any genetic link with the local magmatism and wallrocks, we performed calcite Sm-Nd dating and bulk C-O and in-situ Sr isotope analyses. The results show that the Sb mineralization (∼155 Ma) was considerably younger than the Cu-Pb-Zn mineralization (∼230 Ma), skarn alteration (∼234 Ma), and granitoid emplacement (∼230 Ma) at Yangla, but much older than the local W mineralization (∼30 Ma). The initial 87Sr/86Sr ratio of calcite (0.71972–0.72208) is much higher than that of the Triassic granodiorite (0.71149– 0.71990) and Carboniferous basalt (0.70562–0.70995), suggesting mixed source of calcite from the ore fluids and Devonian wallrocks. The ore-related calcite has δ13CPDB (−4.53 to − 2.33 ‰) and δ18OSMOW (+14.98 to + 16.30 ‰) values that fall between the granite and marine carbonate isotopic fields. This suggests that the ore-forming fluid may be related to the low-temperature alteration of granites and marine carbonate dissolution. Simulated precipitation temperature calculation for the ore-related calcite yielded 200–150 °C, and the calcite C-O isotopes suggest that fluid mixing, fluid-rock interactions, and CO2 degassing may have precipitated the stibnite in the fracture zones under low-temperature conditions. Our new geochemical results and published data suggest that the Yangla polymetallic mineralization was multiphase, comprising the Indosinian Cu-Pb-Zn (∼230 Ma), Yanshanian Sb (∼155 Ma), and Himalayan W-Sb (∼30 Ma) metallogenic events.

OPTIMISATION METHOD FOR OBTAINING A BIOLOGICALLY ACTIVE SUBSTANCES FROM THE PLANT PETROSIMONIA BRACHIATA

Kazakhstan is rich in medicinal plants, so it needs to be studied. Ten species of the Petrosimonia belonging to the Chenopodiaceae family are growing in Kazakhstan. These plants have been adapted to harsh climatic conditions in the country’s salty, saline, and desert areas. Petrosimonia plants are a new species that has not been fully studied. Chinese scientists studied Petrosimonia sibirica species and found that the plant contains alkaloids, steroids, terpenes, flavonoids, and phenolic acids and has antibacterial activity (Wen, 2015; Ying, 2016). The qualitative and quantitative compositions of biologically active substances in P. sibirica, P. Glaucescens, P. triandra, and P. brachiata growing in Kazakhstan were studied. To prepare phytopreparations from P. Sibirica, P. Glaucescens and P. triandra plants were extracted using the classical maceration method, and individual representatives of biologically active compounds were isolated (Toktarbek, 2021; Seitimova, 2022). In this study, a phytochemical study of P. brachiata was conducted. The method for obtaining biologically active complexes with high efficiency was optimised by using supercritical fluid and ultrasonic extraction methods. These methods have a short extraction time, can be carried out at room temperature, are cost effective, and are a modern green chemical approach. Using supercritical fluid CO2 extraction (180 bar, 2 hours), the plant was purified from lipophilic substances. Further, a biologically active complex was obtained by pouring 70% ethanol-water solvent into the plant raw material and performing ultrasound extraction. The obtained complex was analysed by thin-layer chromatography using different organic solvent systems. Based on our analysis, steroids, terpenes, phenolic acids, and flavonoid glycosides were found in the extract. Hexane and ethyl acetate fractions were obtained as a result of liquid-liquid extraction of the extract using organic solvents. Stigmasterol 3-O-β-D-galactopyranoside, isovanillic acid, quercetin 3-O-β-D-glucopyranoside, and isorhamnetin 3-O-α-L-rhamnopyranoside were isolated by washing the hexane and ethyl acetate fractions in a silica gel column with an organic solvent system. The isolated compounds will be tested for biological activity.

An estimate of chlorine fugacity in the low water fluid of the system С-О-(Н)-NaCl in the cumulus of ultrabasic-basic intrusions

At high PT parameters of the cumulates of ultramafic-mafic intrusions at low fO2 (below the QFM buffer), platinum dissolves in the fluid with CO as a carbonyl complex of the native metal. The high solubility of platinum as PtCl2 in brines with NaCl, which is associated with the formation of low-sulfide PGE deposits, is achieved at high oxygen fugacity (above the NNO buffer). It is assumed that at low oxygen fugacity in the low water CO–CO2 fluid, native Pt can also be converted into a cation-soluble form by chlorination. Experimental data (Р = 200 MPa, Т = 950oC, fO2 QFM and fluid CO–CO2) on the reaction of NaCl with magnetite and chromite, accessor minerals of mafic-ultramafic intrusions, with the formation of iron and chromium chlorides are presented. As shown by thermodynamic calculations, the equilibrium in the FeCl3–FeCl2 pair provides the high chlorine fugacity (fCl2). This fugacity is only 3–4 orders of magnitude lower than fCl2 in the Pt–PtCl2 equilibrium and 2.5–3 orders of magnitude higher than in the aqueous fluid 1 M HCl at the same P–T–fO2 parameters.

Metallogenic model of the Lykling ophiolite-hosted lode Au deposit, Scandinavian Caledonides: Insight from fluid inclusions, mineral chemistry and stable isotope geochemistry

The Lykling lode Au deposit represents a unique example of gold mineralization in the Upper Allochthone of the Scandinavian Caledonides. The mineralization is hosted by the Early Ordovician Lykling Ophiolite Complex and the intruding trondhjemite unit and spatially associated with two generations of mafic dykes that crosscut both the ophiolitic complex and trondhjemite. Field observations indicate that the mafic dykes did not play an active role in the emplacement of Au at Lykling, however their contacts with the immediate host rocks (i.e., gabbro and trondhjemite) may have focused ore-forming fluids.Three main stages in the evolution of the hydrothermal system in the Lykling area are documented by two generations of auriferous quartz veins: 1) older quartz-carbonate veins hosted by moderately angled brittle-ductile shear zones and 2) younger quartz-sulfide veins that fill steeply dipping brittle faults. Stage 1 resulted in deposition of barren quartz and gold-free pyrite from moderately saline NaCl-CaCl2-H2O ± CO2 fluids at temperatures between ∼310–330 °C and pressures in the range from 2.7 to 3.5 kbars. Under the given physicochemical conditions Au was mobile in the form of its chloride complexes. Stage 2 is associated with multiple episodes of ductile deformation punctuated by concomitant brecciation reflecting brittle-ductile transition processes. Fluid inclusion data reveals a decrease in temperature and pressure that may result in the formation of stable Au-bisulfide complexes and making the hydrothermal mobility of Au sensitive to changes in pressure. Consequently, the fluctuation in pressure controlled by the development of brittle-ductile structures likely resulted in the precipitation of native gold in quartz veins. Stage 3 represents a pure brittle event which is accompanied by a significant decrease in the fCO2/fS2 ratio. Mixing of higher-temperature and moderate-salinity fluids with cooler fluids has been recognized as the principal trigger for deposition of sulfides and a paragenetically late phase of native gold in the Lykling hydrothermal system.The Lykling ophiolite-hosted lode Au deposit shows numerous similarities with orogenic gold deposits elsewhere, including structural controls during mineralizing events, deposition from moderately to low salinity CO2-bearing aqueous solutions, deposition from a focused fluid flow along trans-crustal fault zones with a mixed brittle-ductile character and the spatial association with regionally metamorphosed terranes. In contrast to the great majority of the known orogenic gold deposits, the Lykling ophiolite-hosted lode Au deposit records a magmatic origin of volatiles. Therefore, taking into consideration field relationships and the regional setting of the Lykling deposit, we argue that its formation is concomitant with emplacement of the Sunnhordland Batholith during post-collisional thinning of the crust and associated localized uplift within the Lykling Ophiolite Complex.

Comparative investigation of heat extraction performance in 3D self-affine rough single fractures using CO2,N2O and H2O as heat transfer fluid

The type and thermophysical properties of heat transfer fluids significantly impact the heat extraction rate of Enhanced Geothermal Systems (EGS). Studies based on field-scale stochastic discrete fracture network geometric models have certain limitations and uncertainties. To compare the heat extraction performance of heat transfer fluids H2O, CO2, and N2O in a core-scale (φ50 × 100 mm) rough single fracture in hot dry rock, we first constructed the fracture geometry with rock surface roughness characteristics using a fractal self-affine function, with a joint roughness coefficient (JRC) of 12.38. Then, at temperatures ranging from 37 to 300°C and a pressure of 30 MPa, we established a thermo-hydraulic (TH) coupling model based on the thermophysical parameter equations of the three heat transfer fluids. Finally, we conducted a comparative study of the changes in the outlet mean temperature and heat extraction rate after flowing through the fracture, as well as the temperature distribution on the fracture surface, under conditions of constant inlet flow velocity with varying inlet temperature and constant inlet temperature with varying inlet flow velocity. The results indicate that (1) with the increase in inlet flow velocity and temperature, the outlet mean temperature and heat extraction rate of CO2 and N2O at the fracture outlet are essentially the same and lower than those of H2O. (2) When the inlet flow velocity increases from 0.005 m/s to 0.025 m/s, the thermal convection effect from the rock matrix to the fluid in the fracture predominates, and flow velocity is the main factor affecting the heat transfer process between the fluid and the rock matrix. When the inlet temperature increases from 37°C to 57°C, the thermal conduction effect from the rock matrix to the fluid in the fracture predominates, and temperature is the main factor affecting the heat transfer process between the fluid and the rock matrix.(3)When maintaining constant inlet temperature, increasing inlet flow velocity from 0.005 m/s to 0.025 m/s results in CO2 experiencing a maximum heat extraction rate increase of 118.85 W. In contrast, N2O experiences 117.05 W, and H2O experiences 266.4 W.(4) When the inlet flow rate is constant, the maximum increase in heat extraction rate for CO2 is 15.34 W as the inlet temperature increases from 37 °C to 57 °C; for N2O, it is 13.9 W; and for H2O, it is 45.45 W.

In-depth phytochemical profiling of Roscoea purpurea (Kakoli): Comparative UHPLC-MS/QToF and GC-MS/MS analysis of supercritical CO2 fluid - and conventional solvent - based extractive processes

The remarkable biodiversity of medicinal plants worldwide highlights their significance in traditional and alternative medicine. Astavarga, a group of eight medicinal herbs from the Himalayan region of India, including Roscoea purpurea (commonly known as Kakoli), is esteemed in Ayurveda for its health-promoting and rejuvenating properties. In this comprehensive study, we aimed to develop and optimise robust UHPLC-MS/QToF (Ultra-high-performance liquid chromatography-mass spectrometry coupled with quadrupole time of flight) and GC-MS/MS (Gas chromatography-tandem mass spectrometry) methods to identify the phytochemicals in R. purpurea root hydromethanolic extract and essential oil. We also conducted a comparative assessment of supercritical fluid extraction and conventional solvent extraction methods for the first time in R. purpurea root, highlighting their relevance to the medicinal field. Using the UHPLC/MS-QToF method, we identified a total of fifty-six phytometabolites, while sixteen volatile constituents were discerned within the essential oil of R. purpurea by GC-MS/MS method. Among the volatile constituents, β-eudesmol (40.84 %), guaiac acetate (10.55 %), and γ-eudesmol (10.31 %) were emerged as the principal components. Our findings were further compared with the volatile constituents extracted via supercritical fluid extraction and conventional solvent extraction methods. Notably, our research unveiled the presence of a carotenoid metabolite, 15-methyl retinol, for the first time. Furthermore, our fatty acid analysis of the supercritical fluid extract revealed elevated levels of unsaturated fatty acids, particularly oleic and linoleic acids. The methods were validated in terms of system specificity also. The discovery of these well-recognised therapeutically active components in R. purpurea significantly enhances its potential, highlighting its unique profile among medicinal plants in the Himalayan region and its suitability for traditional Ayurveda.

Fracture Evolution during CO2 Fracturing in Unconventional Formations: A Simulation Study Using the Phase Field Method

With the introduction of China’s “dual carbon” goals, CO2 is increasingly valued as a resource and is being utilized in unconventional oil and gas development. Its application in fracturing operations shows promising prospects, enabling efficient extraction of oil and gas while facilitating carbon sequestration. The process of reservoir stimulation using CO2 fracturing is complex, involving coupled phenomena such as temperature variations, fluid behavior, and rock mechanics. Currently, numerous scholars have conducted fracturing experiments to explore the mechanisms of supercritical CO2 (SC-CO2)-induced fractures in relatively deep formations. However, there is relatively limited numerical simulation research on the coupling processes involved in CO2 fracturing. Some simulation studies have simplified reservoir and operational parameters, indicating a need for further exploration into the multi-field coupling mechanisms of CO2 fracturing. In this study, a coupled thermo-hydro-mechanical fracturing model considering the CO2 properties and heat transfer characteristics was developed using the phase field method. The multi-field coupling characteristics of hydraulic fracturing with water and SC-CO2 are compared, and the effects of different geological parameters (such as in situ stress) and engineering parameters (such as the injection rate) on fracturing performance in tight reservoirs were investigated. The simulation results validate the conclusion that CO2, especially in its supercritical state, effectively reduces reservoir breakdown pressures and induces relatively complex fractures compared with water fracturing. During CO2 injection, heat transfer between the fluid and rock creates a thermal transition zone near the wellbore, beyond which the reservoir temperature remains relatively unchanged. Larger temperature differentials between the injected CO2 fluid and the formation result in more complicated fracture patterns due to thermal stress effects. With a CO2 injection, the displacement field of the formation deviated asymmetrically and changed abruptly when the fracture formed. As the in situ stress difference increased, the morphology of the SC-CO2-induced fractures tended to become simpler, and conversely, the fracture presented a complicated distribution. Furthermore, with an increasing injection rate of CO2, the fractures exhibited a greater width and extended over longer distances, which are more conducive to reservoir volumetric enhancement. The findings of this study validate the authenticity of previous experimental results, and it analyzed fracture evolution through the multi-field coupling process of CO2 fracturing, thereby enhancing theoretical understanding and laying a foundational basis for the application of this technology.

Supercritical CO2 Fluid Extraction and Microencapsulation of Oil from Anchovy (Engraulis mordax) By-Products.

Fish by-products are discarded as waste, which has a significant impact on the environment. They have no economic value, but there are many opportunities to turn them into high value products. Due to significant quantities generated internationally and the continuous expansion of the market for ω-3 and ω-6 fatty acids as nutraceuticals, innovative technological approaches are needed to transform this waste into marketable products with added value, while limiting the risk of environmental pollution. In this study, two temperatures (40 and 60 °C) at a constant pressure during the extraction of anchovy by-products with supercritical CO2 fluid were used to determine extraction yield, fatty acid, tocopherol and phytosterol composition, followed by microencapsulation with two matrices based on the transglutaminase-mediated crosslinking reaction between whey protein isolates and casein. Before microencapsulation, the binding parameters were estimated using quenching studies. The results showed a higher content of total fatty acids when extracted at 40 °C, resulting in two fractions on a dry mass basis of (712±12) mg/g in the fraction obtained in the separator with code S40 and (732±10) mg/g in the fraction obtained in the separator with code S45, respectively. The monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) accounted for 40-44 %. The extracts showed a higher mass fraction of eicosapentaenoic acid ((28.7±1.0) mg/g) in fraction S45 when extracted at 60 °C. A minimum inhibitory and bactericidal concentration of 0.66 μg/mL against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 was found for all fractions. Higher binding constants were found for palmitoleic and oleic acids than for palmitic acid. The control variant, without crosslinking, enabled the microencapsulation of a higher amount of fatty acids, while in both powders the sum of MUFAs and PUFAs was 40 %. The approaches used in our study open up new opportunities for adding value to the fish by-products through extraction and microencapsulation, extending their potential use to food, cosmetics and nutraceuticals.

Analysis of influence mechanism of CO2-water coupling fracturing sandstone

The existence of hard rock layers has a serious impact on coal seam mining, in order to explore the acidification and crushing mechanism of hard sandstone rock layers, this paper adopts the self-developed CO2-water-rock coupling test device to carry out the testing of mechanical properties and internal structural characteristics of rock samples before and after the coupling action of the three sandstones, and analyzes the influencing factors of sandstone CO2 coupling crushing. The study shows that: the lower the temperature of CO2-water-rock coupling, the higher the pore pressure, the higher the volume fraction of CO2 in the coupling fracturing fluid, and the longer the coupling time, the greater the decrease in the mechanical strength of the rock samples, and the more complicated the splitting damage pattern is, and the CO2-water-rock coupling makes the pore and fracture volume fraction and fractal dimension of three kinds of sandstone samples increase to varying degrees, whereas the volume fraction of minerals and the fractal dimension decrease, and the CO2-water-rock coupling results in a decrease in the volume fraction of minerals and fractal dimension, and a decrease in the volume fraction of minerals and fractal dimension. The pore volume fraction and fractal dimension of the three sandstone samples increased to different degrees, while the mineral volume fraction and fractal dimension decreased, and the pore volume fraction and fractal dimension of the three sandstone samples decreased. The damage pattern of sandstone samples after coupling is affected by both chemical and mechanical damages. When using coupling fracturing fluid with 8 % CO2, the degree of mineral dissolution and dissolution is the largest, and the dissolution effect is larger than the precipitation effect, which has the most significant effect on the morphology type and connectivity of microscopic pore cracks, and the study in this paper has certain theoretical and practical value for the chemical softening of sandstone.

Thermos-economic performance of a novel CCHP system driven by low-grade thermal energy based on CO2 and organic fluids

A novel combined cooling, heating and power (CCHP) system is proposed based on mixture consisting of CO2 and organic fluids to meet the seasonal energy demand in buildings. Thermodynamic model was constructed based on the laws of thermodynamics, and seasonal operation modes were also established. Techno-economic performance was analyzed and the performance of mixture consisting of CO2 and organic fluids compared with CO2 and pure organic fluids. Results show that the temperature of the turbine inlet in trans-critical power cycle should be 10 °C lower than the heat source temperature, with the turbine inlet pressure being approximately 1.4 times as large as critical pressure. Turbine inlet temperature is negatively correlated to the payback period and levelized energy cost while turbine inlet pressure is positively correlated to the system economic performance. The carbon dioxide content is negatively correlated to net power output, thermal efficiency and exergy efficiency, while coefficient of performance will hit the bottom with the carbon dioxide content, except CO2/Propane. For the carbon dioxide content is between 5 % and 10 %, the system overall performance is also close to optimal value. In general, CO2/R134a (0.10/0.90) and CO2/R1234ze(E) (0.10/0.90) is recommendable.

Spotlight on Secondary Metabolites Produced by an Early-Flowering Apulian Artichoke Ecotype Sanitized from Virus Infection by Meristem-Tip-Culture and Thermotherapy.

Globe artichoke (Cynara cardunculus L. subsp. scolymus) is an important crop of the Mediterranean basin characterized by many properties, like hepatoprotective, anticarcinogenic, antioxidant, antibacterial, and beneficial to human health. The high bioactive compounds (BACs) content, as polyphenols, has attracted the research interest in artichoke extracts. We analysed the changes in polyphenol transcriptome profile between sanitized (S) virus-free and non-sanitized (NS) artichoke plants, focusing on genes involved in phenylpropanoid metabolic pathway and flavonoid biosynthesis. A total of 2458 upregulated and 2154 downregulated differentially expressed genes (DEGs) were functionally characterized. Among them, 31 and 35 KEGG orthology entries characterized by upregulated and downregulated DEGs, respectively, were involved in the biosynthesis of other secondary metabolites. A downregulation of PAL, C4H, 4CL, HST/HQT, C3'H, CCoAMT, CCR1, and F5H, was observed in S artichoke compared to NS one, whereas the CSE, CHS, and CHI genes were upregulated in S samples. Transcriptome results were compared to the polyphenols accumulation in S and NS artichoke leaves. A higher content of total polyphenols was observed in older leaves of NS samples, compared to extracts obtained from young leaves or from S plants, and this result was associated with the presence of viral infections in NS plants. In all the conditions tested, the most represented compound was chlorogenic acid, followed by luteolin-7-O-glucoside. The different composition of each extract was evaluated by a polyphenol dose-response treatment on the rodent hepatoma FaO cell line to the accumulation of reactive oxygen species (ROS). A significant reduction in ROS content ranging between -40% and -48% was observed when 10-20 mg/L of polyphenols from NS or S plants were used, characterized by a specific profile of compounds. To reduce MetOH residues in polyphenol extracts, a supercritical fluid CO2 extraction was evaluated to propose a sustainable green extraction.

Optimization of supercritical CO2 fluid extraction process, component analysis, and antioxidant spectral activity correlation of Huoluo Xiaoling Dan

ABSTRACT This study elucidated the optimization conditions, GC-MS analysis conditions, total antioxidant activity, and components closely related to antioxidant activity for supercritical extraction of active ingredients in Huoluo Xiaoling Dan (HLXLD). The yield, octyl acetate content, and total antioxidant activity of HLXLD under different conditions were obtained through orthogonal experiments, and the optimal supercritical extraction conditions were determined to be 45°C, 25 MPa, and 4 h. The supercritical extract was subjected to GC-MS analysis and matched with the WILEY and NIST databases, resulting in the qualitative identification of 37 chemical components with a matching degree above 60. The similarity evaluation system of traditional Chinese medicine fingerprint was used to evaluate all orthogonal experimental samples, with a similarity ranging from 0.522 to 0.989. Thirteen common characteristic peaks were selected, and the quantification of these peaks was performed using peak area normalization method. The combination of the content of common characteristic peaks in different samples and their total antioxidant activity was analyzed using multivariate statistical methods such as principal component analysis and multiple regression equation. It was found that five components, F3, F2, F5, F7 and F12, among the common characteristic peaks were closely related to antioxidant activity.

Effects of supercritical CO2 fluids on pore structure and fractal characteristics of bituminous coal

Enhanced coalbed methane recovery with CO2 coal seam storage (CO2-ECBM) technology is an important way to achieve China's strategic goals of carbon peak and carbon neutrality. Presently, to date there has been rarely research conducted on the effect of coal sample scale on pore structure under supercritical CO2 (ScCO2) fluids. In this study, a high-pressure geological environment simulation system was adopted to analyze coal samples of different scales for ScCO2 saturation. Subsequently, low-pressure nitrogen gas adsorption (LP-N2GA), mercury intrusion porosimetry (MIP), and low-field nuclear magnetic resonance (LF-NMR) were used to analyze the pore structure and fractal dimension changes in saturated coal samples at different scales. The experimental results show that the mesopore ratios of cylindrical and granular coal decrease by an average of 1.68% and 2.30%, respectively, after the saturation of ScCO2. The proportion of macropores in cylindrical coal increased by an average of 5.50% after ScCO2 saturation, while the proportion of macropores in granular coal changed by 176.86% compared to cylindrical coal. The fractal dimension of the ScCO2 saturated coal samples obtained with LP-N2GA, MIP, and LF-NMR all show a decreasing trend, again confirming the modification of the coal pore surface by ScCO2. Finally, a conceptual model is presented to analyze the mechanism of the effect of coal sample scale on the pore structure under ScCO2. The difference in the transport paths of ScCO2 molecules at different coal scales is the main reason for the difference in the evolution of the pore structure. In addition, the impact of the amount of adsorption obtained in the laboratory using coal samples of different scales on the assessment of the CO2 storage capacity was discussed. Therefore, the results of this study are expected to provide a reference for the CO2 storage capacity assessment of the CO2-ECBM project.

DiadFit: An open-source Python3 tool for peak fitting of Raman data from silicate melts and CO2 fluids

DiadFit: An open-source Python3 tool for peak fitting of Raman data from silicate melts and CO2 fluids