Supercritical Fluid Research Articles

Synthesis and characterization of nano-biopolymer carriers loaded with clove (Syzygium aromaticum L.) extract as an anticancer agent: an in vitro study

The objective of this work was to design a new drug nanoparticle (NP) composed of chitosan/β-cyclodextrin/sodium tripolyphosphate/alginate (CS/βCD/TPP/AL) loaded with a clove extract (CE) for potential anticancer effects. The extract was prepared by two extraction methods: hydroalcoholic maceration (MAC) with 80% MeOH and supercritical fluid (SCF). The MACCE and SCFCE CE NPs had particle sizes of 71 nm and 20 nm, respectively with irregular spherical shapes. The nanocarriers achieved entrapment efficiencies of over 90%. MACCE-NPs and SCFCE-NPs released 18.35% and 10.12% of the extract after 6 h, respectively. Cell viability decreased to 54%, 7%, and 12% in HeLa, U87, and KB cell lines, respectively, after a 48-hour treatment with SCFCE-NPs and 75%, 8%, and 17% after treatment with MACCE-NPs, significantly reduced compared to the control. It is concluded that NPs containing CE exhibit a higher degree of toxicity due to better penetration into cells.

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.

Simulation and optimization of fatty acid extraction parameters from Nannochloropsis sp. using supercritical carbon dioxide

Microalgae, which are rich in fatty acids, have potential applications in various sectors such as bioenergy, health, food, and biomaterials. The Supercritical Fluid Extraction (SFE) method is commonly used to extract microalgae. This research estimated the process parameters of desorption rate constant (kd) and binary diffusion coefficient (DAB) for SFE fatty acid from Nannochloropsis sp. using a mathematical model called as hot sphere diffusion. Desorption models were used to model the release of fatty acids into the solvent (supercritical carbon dioxide). The parameter estimation process was conducted at temperatures of 313 and 333 K and pressures of 12.5, 20, and 30 MPa. The value of kd increased with increasing pressure and temperature and DAB values were obtained at varying pressures and temperatures.

Evaluating the anti-yeast, anti-diabetic, wound healing activities of Moringa oleifera extracted at different conditions of pressure via supercritical fluid extraction

Plants represent a great source of medicines, and for their components to be discovered, extraction processes must be developed, especially methods based on green technology. Supercritical fluid extraction (SFE) was employed as a green method for Moringa oleifera extraction in the present investigation. The maximum yield of extraction was obtained at 25 MPa. Moreover, the extraction at 25 MPa induced the release of various phenols and flavonoids, as analyzed via high-performance liquid chromatography. The investigation revealed the concentrations of chlorogenic, gallic, rosmarinic, and coumaric acids to be 150.59, 89.90, 44.75, and 29.41 µg/mL, respectively at 25 MPa. However, their concentrations were 0.73, 1.53, 0.24, and 0.04 µg/mL, respectively at 15 MPa; vs. 4.73, 2.62, 1.06, and 0.50 at 35 MPa, respectively. Totals of saponin, flavonoid, phenolic, tannins, and alkaloid were recorded in maximum yield at 25 MPa. Moringa oleifera extracted at 35 MPa reflected highest inhibition zones of 27 ± 0.1, 30 ± 0.2, and 30 ± 0.1 mm against C. glabrata, C. tropicalis, and C. albicans, correspondingly. α-Amylase and α-glucosidase activities were greatly suppressed by the M. oleifera extract at 25 MPa with less IC50 (12.97 µg/mL and 6.0 µg/mL), than the IC50 (53.46 and 22.02 µg/mL) at 15 MPa, compared with acarbose IC50 (5.52 and 2.64 µg/mL), correspondingly.

Binary phase behavior of select organosulfur compounds in supercritical carbon dioxide: A Monte Carlo molecular simulation study.

Pressure-composition binary phase diagrams were determined for methanethiol, dimethyl sulfide, thiophene, benzothiophene, or dibenzothiophene with carbon dioxide at temperatures from 363 to 453K and pressures from 2 to 20 MPa. Utilizing Gibbs ensemble Monte Carlo molecular simulation, phase coexistence compositions were determined, along with the impact of 4% water cosolvent on select results. Solution structure as a function of pressure and temperature is characterized via radial distribution functions. Comparison to available experimental composition data gives overall mean absolute percentage deviations of 2.2% for thiophene, 37% for methanethiol, and 99% for benzothiophene. Solubilities in a CO2-rich phase are calculated to be sufficient to allow extraction and detection of the compounds studied here via supercritical fluid chromatography and mass spectrometry as a possible analysis approach for future Mars rover missions.

Optimization of Oil and Tocopherol Extraction from Maqui (Aristotelia chilensis (Mol.) Stuntz) by Supercritical CO2 Procedure.

This study focused on the oil extraction from freeze-dried maqui (Aristotelia chilensis) by supercritical fluid extraction with carbon dioxide (SFE-CO2). The basic objective was to optimize the oil yield and the tocopherol concentration. A Box/Behnken experimental design was developed with three processing variables: supercritical pressure (74, 187, and 300 bar), temperature (35, 48, and 60 °C), and extracting time (30, 135, and 240 min). Multiple optimizations, based on the combination of factor levels at 274 bar, 240 min, and 60 °C, led to the highest oil yield and tocopherol values. The validation of the optimized conditions of maqui oil extraction led to an oil yield of 8% and values of 735, 53, and 97 (mg·kg-1 oil) for α-tocopherol, α-tocotrienol, and γ-tocopherol, respectively. A higher concentration of tocopherol compounds was observed when compared to the employment of the conventional extracting method. The optimized SFE-CO2 method led to an oil extract exhibiting higher Hydrophilic-Oxygen Radical Absorbance Capacity (H-ORAC) assay and total phenol content (22 μmol Trolox equivalents·g-1 oil and 28 mg gallic acid equivalents·g-1 oil) than the oil obtained by the conventional procedure. A practical and accurate oil extraction is proposed for obtaining tocopherol-enriched oil including high concentrations of valuable lipophilic antioxidants.

Circulating adrenal and gonadal steroid hormones heterogeneity in active young males and the contribution of 11-oxy androgens

The classical androgens, testosterone and dihydrotestosterone, together with dehydroepiandrosterone, the precusrsor to all androgens, are generally included in diagnostic steroid evaluations of androgen excess and deficiency disorders and monitored in androgen replacement and androgen suppressive therapies. The C11-oxy androgens also contribute to androgen excess disorders and are still often excluded from clinical and research-based steroids analysis. The contribution of the C11-oxy androgens to the androgen pool has not been considered in androgen deficiency. An exploratory investigation into circulating adrenal and gonadal steroid hormones in men was undertaken as neither the classical androgens nor the C11-oxy androgens have been evaluated in the context of concurrent measurement of all adrenal steroid hormones. Serum androgens, mineralocorticoids, glucocorticoids, progesterones and androgens were assessed in 70 healthy young men using ultra high performance supercritical fluid chromatography and tandem mass spectrometry. Testosterone, 24.5 nmol/L was the most prominent androgen detected in all participants while dihydrotestosterone, 1.23 nmol/L, was only detected in 25% of the participants. The 11-oxy androgens were present in most of the participants with 11-hydroxyandrostenedione, 3.37 nmol, in 98.5%, 11-ketoandrostenedione 0.764 in 77%, 11-hydroxytestosterone, 0.567 in 96% and 11-ketotestosterone: 0.440 in 63%. A third of the participants with normal testosterone and comparable 11-ketotestosterone, had significantly lower dehydroepiandrosterone (p < 0.001). In these males 11-hydroxyandrostenedione (p < 0.001), 11-ketoandrostenedione (p < 0.01) and 11-hydroxytestosterone (p < 0.006) were decreased. Glucocorticoids were also lower: cortisol (p < 0.001), corticosterone (p < 0.001), cortisone (p < 0.006) 11-dehydrocorticosterone (p < 0.001) as well as cortisol:cortisone (p < 0.001). The presence of dehydroepiandrosterone was associated with 16-hydroxyprogesterone (p < 0.001), which was also significantly lower. Adrenal and gonadal steroid analysis showed unexpected steroid heterogeneity in normal young men. Testosterone constitutes 78% of the circulating free androgens with the 11-oxy androgens abundantly present in all participants significantly contributing 22%. In addition, a subset of men were identified with low circulating dehydroepiandrosterone who showed altered adrenal steroids with decreased glucocorticoids and decreased C11-oxy androgens. Analysis of the classical and 11-oxy androgens with the additional measurement of dehydroepiandrosterone and 16-hydroxyprogesterone may allow better diagnostic accuracy in androgen excess or deficiency.

Supercritical fluids for the isolation and formulation of bioactive substances

Technologies involving sub- and supercritical fluids offer the possibility to obtain new products with special characteristics, which are especially needed in the pharmaceutical industry. The use of sub- or supercritical fluids for processing can also address legal limits for solvent residues and restrictions on the use of conventional solvents, while enabling new processes that are environmentally friendly and sustainable. Extraction of substances from plant materials, their in situ formulation in products with specific properties, particle formation, foaming, deposition, and sterilization have attracted much attention among the applications of supercritical fluids. This short overview reports the current status and expected future developments of research into sub- and supercritical fluid technologies.

Molecular simulation on inhomogeneous microaggregation and pyrolysis mechanics of supercritical methylcyclohexane

Affected by the microaggregation of supercritical fluids, supercritical pyrolysis of hydrocarbon fuels shows unique product distributions and pathways. In this work, the role of inhomogeneous microaggregation during supercritical pyrolysis are clarified via computational method, with the benchmark of methylcyclohexane. Characteristic pyrolysis behaviors under supercritical conditions are intimately revealed and characterized through collective variable-driven hyperdynamics (CVHD) simulations. Liquid-like atoms, which representing the inhomogeneity of supercritical fluids are described by the trained machine-learning classifier, then proposed as the specific reason for the increase in the variety and frequency of bimolecular reactions. In addition, the intrinsic pyrolysis mechanism has also been confirmed to regulate the inhomogeneity effect on reactions through comparisons between different hydrocarbons.

Comparison of quantity, quality and antibacterial activity of essential oil Mentha longifolia (L.) L. under different traditional and modern extraction methods.

Extraction is the first and most important step in obtaining the effective ingredients of medicinal plants. Mentha longifolia (L.) L. is of considerable economic importance as a natural raw material for the food and pharmaceutical industries. Since the effect of different extraction methods (traditional and modern methods) on the quantity, quality and antimicrobial activity of the essential oil of this plant has not been done simultaneously; the present study was designed for the first time with the aim of identifying the best extraction method in terms of these features. For this purpose, extracting the essential oil of M. longifolia with the methods of hydrodistillation with Clevenger device (HDC), steam distillation with Kaiser device (SDK), simultaneous distillation with a solvent (SDE), hydrodistillation with microwave device (HDM), pretreatment of ultrasonic waves and Clevenger (U+HDC) and supercritical fluid (SF) were performed. Chemical compounds were identified by gas chromatography coupled with mass spectrometer (GC-MS). Antimicrobial activity of essential oils against various clinical microbial strains was evaluated by agar diffusion method and determination of the minimum inhibitory concentration and minimum bactericidal concentration (MIC and MBC). The results showed that the highest and lowest yields of M. longifolia leaf essential oil belonged to HDC (1.6083%) and HDM (0.3416%). The highest number of compounds belonged to SDK essential oil and was equal to 72 compounds (with a relative percentage of 87.13%) and the lowest number of compounds was related to the SF essential oil sample (7 compounds with a relative percentage of 100%). Piperitenone (25.2-41.38%), piperitenone oxide (22.02-0%), pulegone (10.81-0%) and 1,8-cineole (5-35.0%) are the dominant and main components of M. longifolia essential oil were subjected to different extraction methods. Antimicrobial activity results showed that the lowest MIC value belonged to essential oils extracted by HDM, SDK, SDE and U+HDC methods with a value of 1000 μg/mL was observed against Gram-negative bacteria Shigella dysenteriae, which was 5 times weaker than rifampin and 7 times weaker than gentamicin. Therefore, it can be concluded that in terms of efficiency of the HDC method, in terms of the percentage of compounds of the HDM method, and in terms of microbial activity, the SDK, HDM and U+HDC methods performed better.

Advanced and Potential Methods for Extraction of Bioactive Compounds from Avocado Peel—A Review

Extraction techniques are continuously developed by the scientific community. Meanwhile, avocado peel is a by-product of avocado processing and a source of bioactive compounds. The purpose of this review was to summarize the use of advanced techniques for extracting bioactive compounds from avocado peel to help understand which techniques have and have not been applied to avocado peel. Three primary databases were used to collect the information, including Google Scholar, Scopus, and Web of Science, by using the keywords “avocado”, “peel”, and “extraction”. Additional keywords related to the extraction technique were also used, including “Microwave-Assisted Extraction”, “Ultrasound-Assisted Extraction”, “Enzyme-Assisted Extraction”, “Pressurized Liquid Extraction”, “Supercritical Fluid Extraction”, “Natural Deep Eutectic Solvents”, “Three-phase partitioning (TPP)”, “Pulsed-Electric Field”, “High Voltage Electric Discharge Plasma”, “Centrifugal Partition Extraction”, and “Surfactant-Mediated Extraction”. The results show that microwave-assisted extraction, ultrasound-assisted extraction, enzyme-assisted extraction, pressurized liquid extraction, supercritical fluid extraction, TPP, and natural deep eutectic solvent extraction have been used to retrieve bioactive compounds from avocado peel. Other techniques have not yet been applied for the extraction of bioactive compounds from avocado peel. This article is the first review discussing the advanced extraction technique for retrieving bioactive compounds from avocado peel. This article creates a paradigm for future studies.

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.

Development of a Two-Dimensional Supercritical Fluid Chromatography System in Multiple Heart-Cutting Modes.

In this study, we present the development of a loop-based two-dimensional supercritical fluid system in multiple heart-cutting modes (mSFC-SFC), with diode-array and mass spectrometric detection. The instrument design was developed to be as simple as possible, based on a single SFC instrument, with the sole addition of three external 2-port 6-position valves. The objective was to achieve the most complete transfer of a peak from the first to the second dimension, whatever the composition of the mobile phase, i.e., whatever the proportion of carbon dioxide and methanol cosolvent along a wide gradient elution. Thanks to fine adjustment of the valve switching times, the first-dimension peaks were parked in 50 μL or 100 μL loops and later discharged to the second dimension. The interest of this instrument was then demonstrated with a sample application on a natural product: an extract of Citrus aurantium L. bark was analyzed, with a particular focus on chiral flavonoids, neohesperidin, and naringin. In this system, the first dimension was an achiral separation of the flavonoids, based on a polar diethylamine-bonded silica stationary phase (ACQUITY Torus DEA), while the second dimension used a stereoselective polysaccharide stationary phase (CHIRALPAK IB-3) to resolve flavonoid diastereomers. Excellent repeatability was demonstrated, with relative standard deviation values on retention times and peak areas all below 2%, together with excellent peak capacity and peak shapes (no distortion observed), making it possible to quantify diastereomers in the second-dimension separation. This good repeatability was also shown for the transfer rate between the two dimensions, which reached a value of 83%. Finally, transferring a compressible sample from the first to the second dimension is demonstrated to yield excellent performance, despite the large loop volume.

Impact of extraction techniques and process optimization on antioxidant and antibacterial potential of Kalanchoe pinnata leaf extract

ABSTRACT Kalanchoe pinnata (Lam.) Pers. is an ethnomedicinal plant known for its antioxidant, antibacterial, and therapeutic potential. The current study was an effort to explore the impact of extraction technique on the phytochemical, antioxidant, and antibacterial profile of the plant extracts. K. pinnata leaf extracts were prepared using conventional solvent extraction (100% methanol; 50% methanol: 50% water; 100% water), microwave-assisted extraction at 700-W power (3 min; 6 min; 9 min), and supercritical fluid extraction (SFE) (3500 psi; 4500 psi; 5500 psi). Best results were attained from SFE in terms of total phenolic content (240 ± 3 mg GAE/g), total flavonoid content (165.2 ± 0.4 mg QE/g), 2,2-diphenyl-1-picrylhydrazyl radical scavenging potential (91.9 ± 0.4%), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid assay value (8.04 ± 0.03 mMol TE/g) and ferric reducing antioxidant power assay value (471.7 ± 0.8 µg/mL). K. pinnata leaf extracts have been found to be most effective against Yersinia pseudotuberculosis (22.20 ± 0.95 mm) and least effective againstProteus vulgaris (0 ± 0 mm). High-performance liquid chromatography analysis of K. pinnata extract showed that it contains flavanol quercetin (2.0 ± 0.1 mg/g). It is evident from the findings of current study that K. pinnata extract can effectively treat bacterial infections and can cure metabolic disorders by reducing oxidative stress. Application of advance extraction techniques enhances the biological activity of plant extracts.

Research on the Supercritical CO2 Extraction Process of Hetian Rose Essential Oil

A longstanding concern in plant essential oil extraction is how to optimize extraction efficiency with limited materials. Supercritical CO2 extraction has been proven effective in enhancing the yield and efficiency of extracting plant essential oils. However, the impact of temperature, pressure, and co-solvent content on extracting Hetian rose essential oil remains unclear. There is a lack of research on the influence of pretreatment methods. This study focuses on investigating supercritical CO2 extraction of rose essential oils from Xinjiang Hetian. The research analyzes the effects of pressure and temperature on the extraction rate and validates the efficiency by calculating the solubility of essential oils in supercritical fluid. Under conditions of 35 MPa, 40 °C, 10 L/h, and a particle size of 0.8 mm, this study evaluates the extraction efficiency using Xinjiang Hetian rose materials pretreated with salt solutions at concentrations of 5%, 10%, and 20%, as well as enzyme solutions at concentrations of 2%, 5%, and 10%. Results indicate that appropriate solution concentration can enhance the extraction effect and mass transfer process, but excessively low or high concentrations do not contribute to improved extraction reactions. The highest extraction rate (8.99%) is achieved using a salt solution concentration of 10%, while the lowest (4.21%) is obtained with a salt solution concentration of 20%.

Effects of Extraction Methods on Volatile Oil Profiles of Cinnamomi ramulus–Zingiberis rhizoma recens Couplet Medicines

Cinnamomi ramulus (CR, Guizhi in Chinese) and Zingiberis rhizoma recens (ZRR, Shengjiang in Chinese) are couplet medicines (drug pairs or drug combinations) in traditional Chinese medicine prescriptions. They contain a high amount of volatile oils which endow them with unique flavors and pharmacological activities. Extraction methods have a great influence on the extraction efficiency and composition of volatile oils. Firstly, the volatile oils of CR and ZRR were extracted by steam distillation (SD) and analyzed by GC-MS to obtain their chemical profiles. In total, 35 and 55 compounds were identified in the volatile oils of CR and ZRR, respectively. In order to find a suitable extraction method for the couplet medicine CR-ZRR, subsequently, steam distillation (SD), azeotropic distillation (AD) and supercritical fluid extraction (SFE) were applied to extract the volatile oils from CR-ZRR. The average extraction yields by SD, AD and SFE were 0.573%, 0.62% and 2.135%, respectively. The chemical composition of the volatile oils was then analyzed by GC-MS. In total, 73, 59 and 71 compounds were identified from the extracts obtained by SD, AD and SFE, respectively. Principal component analysis (PCA) and OPLS-DA showed that citral, (E)-cinnamaldehyde dimethyl acetal, zingiberene, cinnamaldehyde and β-sesquiphellandrene were the main contributors to distinguish the volatile oils that were obtained by different processes. Considering the chemical diversity and the total content of the main bioactive components of the volatiles oils, SD was more suitable for CR-ZRR volatile oil extraction. This study provides a basis for elucidating the chemical composition and suitable extraction method for the volatile oils of CR-ZRR.

Optimization of Conventional and Supercritical Fluid Extraction of Lycopene Rich Extract from Heiyai (Elaeagnus latifolia L.)

Optimization of Conventional and Supercritical Fluid Extraction of Lycopene Rich Extract from Heiyai (Elaeagnus latifolia L.)

Nanosuspension as a Novel Nanovehicle for Drug Delivery: A Recent Update on Patents and Therapeutic Applications

Abstract: Solubility is a critical factor for the therapeutic action of drugs and does not depend on the administration of routes. Various conventional methods are used to enhance the solubility of the drug, which show limited applicability. Nanotechnology is used to improve the solubility and bioavailability of drugs that belong to BCS classes II and IV. Nanosuspension is the dispersion of pure drug nanoparticles in aqueous with a minimum amount of surfactant, stabilizing the formula-tion. Various techniques, such as the bottom-up approach, dissocubes, nanopure, nanoedge, nano-jet process, supercritical fluid, dry co-grinding, milling media, and nanoprecipitation, have been used to formulate nanosuspension. Nanosuspension can be administered orally, inhalation, trans-dermal, ocular, injectable, topical, and pulmonary. To resolve the problem of solubility and stabil-ity, nanosuspension has received much attention because of its technical simplicity, cost-effectiveness, and ease of significant scale-up. Nanosuspension can control particle size surface charge properties and release the drug at specific sites at an optimal rate. Recently, more than 100 patents have been published on nanosuspension. This review article covers the different prepara-tion methods, formulation composition, marketed products, characterization, and recent patents on nanosuspension. The various benefits and evaluation of the parameters of nanosuspension are discussed briefly. This patent-based review will enhance the knowledge of control drug delivery and related patents on nanosuspension.

Impact fracturing of rock-like material using carbon dioxide under different temperatures and pressures

Unconventional resources (oil, gas, and geothermal) are often buried deep underground within dense rock strata and complex geological structures, making it increasingly difficult to create volumetric fractures through conventional hydraulic fracturing. This paper introduces a novel method of supercritical energetic fluid thermal shock fracturing. It pioneers a CO2 deflagration impact triaxial pneumatic fracturing experimental system, using high-strength similar materials to simulate deep, hard rock masses. The study investigates the rock-breaking process and crack propagation patterns under supercritical CO2 thermal shock, revealing and discussing the types of thermal shock-induced fractures, their formation conditions, and discrimination criteria. The research indicates that higher supercritical CO2 thermal shock pressures and faster pressure release rates facilitate the formation of radial branching fractures, circumferential cracks, and branch cracks. Typically, CO2 thermal shock generates 3–5 radial main cracks, which is significantly more than the single main crack formed by hydraulic fracturing. The formation of branched cracks is often caused by compression-shear failure and occurs under relatively harsh conditions, determined by the confining pressure, rock properties, peak thermal shock pressure, and the pressure sustained post-decompression. The findings are expected to offer a safe, efficient, and controllable shockwave method of supercritical fluid thermal shock fracturing for the exploitation of deep unconventional oil and gas resources.

Artificially high stability of the sodium hydromolybdate ion pair in aqueous solution. Comment on Guan et al. (2023) “Different metal coordination in sub- and super-critical fluids: Do molybdenum (IV) chloride complexes contribute to mass transfer in magmatic systems?”, Geochim. Cosmochim. Acta 354, 240–251

Artificially high stability of the sodium hydromolybdate ion pair in aqueous solution. Comment on Guan et al. (2023) “Different metal coordination in sub- and super-critical fluids: Do molybdenum (IV) chloride complexes contribute to mass transfer in magmatic systems?”, Geochim. Cosmochim. Acta 354, 240–251