Acid In Fluid Research Articles

Metal-Phenolic Network Directed Coating of Single Probiotic Cell Followed by Photoinitiated Thiol-Ene Click Fortification to Enhance Oral Therapy.

Probiotics-based oral therapy has become a promising way to prevent and treat various diseases, while the application of probiotics is primarily restricted by loss of viability due to adverse conditions in the gastrointestinal (GI) tract during oral delivery. Layer-by-layer (LbL) single-cell encapsulation approaches are widely employed to improve the bioavailability of probiotics. However, they are generally time- and labor-intensive owing to multistep operation. Herein, a simple yet efficient LbL technique is developed to coat a model probiotic named Escherichia coli Nissle 1917 (EcN) through polyphenol-Ca2+ network directed allyl-modified gelatin (GelAGE) adsorption followed by cross-linking of GelAGE via photoinitiated thiol-ene click reaction to protect EcN from harsh microenvironments of GI tract. LbL single-cell encapsulation can be performed within 1h through simple operation. It is revealed that coated EcN exhibits significantly improved viability against acidic gastric fluid and bile salts, and enhanced colonization in the intestinal tract without loss of proliferation capabilities. Furthermore, oral therapy of coated EcN remarkably relieves the pathological symptoms associated with colitis in mice including down-regulating inflammation, repairing epithelial barriers, scavenging reactive oxygen species (ROS), and restoring the homeostasis of gut microbiota. This simplified LbL coating strategy has great potential for various probiotics-mediated biomedical and nutraceutical applications.

Dolomite dissolution and porosity enhancement simulation with acetic acid: Insights into the influence of temperature and ionic effects

Dolostone reservoirs are crucial for global oil and gas storage, holding a significant portion of hydrocarbon reserves within carbonate formations. Understanding the chemical mechanism of dolomite dissolution with organic acids and associated porosity development in these reservoirs is vital for optimizing hydrocarbon recovery. In this work, two sets of simulation experiments are designed to understand the controls of temperature and ionic effects on porosity enhancement during the dissolution of dolomite with acetic acid. In specific, we discovered a three-step reaction process between dolomite and acetic acid, involving acetic acid dissolution in water, acetic acid dissociation, and dolomite dissolution. Burial environments with higher temperatures reduce the degree of acetic acid dissociation, leading to a corresponding decrease in dolomite dissolution in acetic acid solutions. The presence of salt ions in the solution influences the reaction process, with magnesium chloride (MgCl2) having the most significant enhancing effect on dolomite dissolution, followed by sodium chloride (NaCl), while calcium chloride (CaCl2) has a limited impact. Sodium sulfate (Na2SO4) enhances dolomite dissolution at lower temperatures; however, at higher temperatures (>100 °C), it may reduce dolomite dissolution due to the precipitation of CaSO4. Despite a relatively short open-flow time, episodic burial dissolution of dolomite by acetic acid fluids under overburden pressure leads to a "net increase" in the reservoir space and enhances its connectivity attributes. During burial diagenesis, geological forces episodically drive organic acid fluids to the dolomite reservoir, predominantly dissolving dolomite along pre-existing pore development zones and geological interfaces, exhibiting inheritance, episodicity, and localization characteristics. Overall, this study provides insights into the dissolution and diagenetic processes of dolomite in the presence under acetic acids, from the point of dissolution simulation experiments. Collectively, these findings enhance our understanding of pore-system evolution and fluid-rock interactions in deep carbonate reservoirs.

Epithermal Deposits of Kamchatka, Russia

The results of studying the epithermal deposits of Kamchatka, one of the most promising gold-mining provinces of the Russian Federation, are generalized. The deposits are divided into acid–sulfate (Ac-Sul) and adularia–sericite (Ad-Ser) types (Heald et al., 1987). The disadvantages of the scheme, which is the most popular in the English-language literature and is based on the sulfidation state of mineral parageneses in ores (LS, IS, and HS types), are shown. The classification that we proposed includes differences in mineral associations in circum–ore metasomatites, which are determined by the acidity–alkalinity and an oxidation state of mineral-forming fluids, and are clearly diagnosed at the first stages of studying the deposits. Kamchatka epithermal deposits of the Ad-Ser-type are associated with andesite volcanism of the volcanic belts. Gold ore associations are concentrated in quartz, carbonate–quartz, and adularia–quartz veins, as well as in sericitized metasomatites, which are replaced by argillizites and propylites towards the periphery. The Ad-Ser-type is characterized by combination with polysulfide (Pb, Zn) (Amethyst, Kumroch, Vilyuchinskoe deposits), sulfosalt (Ag, Sb, As, Bi, Sn) (Ozernovskoe, Baranyevskoe), and selenide (Ag, Se) (Amethyst, Asachinskoe, Rodnikovoe) assemblages. Low-fineness native gold (220–310‰) is typical of the early polysulfide assemblage. With an increase in the fugacity of Te and Se, the gold fineness increases to 510–740‰, and with the progressive activity of Sb, As and Bi and the formation of sulfosalt associations, it reaches 998‰. The homogenization temperatures of primary fluid inclusions in quartz from gold-bearing associations of the Ad-Ser-type are 260–250°C; the minerals crystallize from solutions containing no more than 3 wt % NaCl eq. Maletoyvayam, the only Ac-Sul-type deposit in Kamchatka, is localized in quartz, secondary quartzites, and alunite–sericite–kaolinite–quartz metasomatites. Gold-bearing parageneses indicate the leading role of selenium in mineral formation, contain high-fineness native gold, sulfoselenotellurides, tellurides, and selenides of Au, which crystallize from acidic fluids with salinity of 1–5 wt % NaCl eq. at temperatures of 290–175°C.

Evolution processes and diagenetic response of paleo-pore fluids in continental rift basin: A case study of Bonan Sag

Evolution and transport processes of pore fluids are accompanying with the burial process of sedimentary basins. Those processes lead to redistribution of materials and energies, and control the distribution of favorable reservoirs in sedimentary basins too. For petroliferous basins, confirming the evolution processes of pore fluids is useful for favorable reservoirs prediction. In this study, formation waters chemistry characteristics, skeleton particle compositions, and diagenetic products of sandstones were all take into consideration. It is to invert the evolution processes of pore fluids in continental rift basin. This study shows the changes of formation waters, diagenetic products and skeleton particle compositions are regularly with depth. The evolution processes of pore fluids are mainly controlled by basin sinking and uplifting, fluids concentration, mudstones compaction, organic matter evolution, diagenesis. The evolution of pore fluids in Bonan Sag have experienced seven stage: firstly, primary lake water; and then alkaline fluids from mudstone, which is caused by compaction; and then acidic fluids with organic acids; and then the alkaline fluids, which is caused by basin uplifting and water-rock interactions; and then acidic fluids with CO2, which is from cracking of organic matters; and then acidic fluids with CO2/H2S which caused by TSR; at last, alkaline fluids caused by deep buried and water-rock interactions. Changes of pore fluids (physical or chemical) lead parts of minerals in sandstones be unstable, and then dissolved by pore fluids. At the same time, part of dissolved particles in pore fluids reacted with each other, and then precipitated as diagenetic products.

The effect of corrosion inhibitor chemistry on rheology and stability of CO2 and N2 acidic foam under harsh conditions

Utilization of CO2 foam in well-stimulation operations is a realistic practice to reduce carbon emissions by injecting CO2 into subsurface formations. The viscosity and stability of CO2 and N2 acidic foamed fluid is impacted by additives such as corrosion inhibitor and chelating agent and conditions such as pressure. In this study, the apparent foam viscosity was determined using a high pressure - high temperature foam rheometer at a temperature of 150 °C, pressure ranging from 1000–4000 psi, and different shear rates 100-2000 1/s. A foam analyzer was furthermore utilized to characterize foam properties such as foamability, foam stability, and bubble structures at 100 °C and 1000 psi. Different surfactants were used due to their ability to generate stable and viscous foam; Duomeen TTM, Ethoduomeen T13, Armovis VES, and the combination of Duomeen TTM and Armovis VES. Among all surfactants, Duomeen TTM provided the highest foam viscosity with CO2 at both low and high shear rate. Once the surfactant solution was mixed with 1.5 wt% of CI, the foam viscosity dropped sharply. However, the synergic surfactants (i.e., Duomeen TTM and Armovis VES) obtained the highest viscosity once mixed with CI. Also, the effect of CO2 and N2 at different pressures on the viscosity of generated foam was investigated. When the CO2 pressure was raised to 2000 psi, the viscosity of CO2 foam increased by 55% at both low and high shear. In comparison, the N2 foam viscosity increased by 12% at 100 1/s shear rate and by 32% at 1500 1/s. According to the findings, the influence of CI increased as the pH of the foam fluid declined, and thus reduced the foam viscosity. Finally, foam properties such as foamability, foam stability, and bubble structure were determined. N2 foam generated higher foam stability than CO2 foam. The findings of this study can help for a better understanding of the effect of corrosion inhibitor on CO2 and N2 foam viscosity at high temperature and pressure.

경정맥영양주사치료(intravenous nutrition therapy)의 근거 및 임상적 활용 범위

Intravenous nutrition therapy (IVNT) of functional medicine is often used as a confused concept with amino acid fluids or total parenteral nutrition (TPN) fluids due to its name of nutrition therapy. However, IVNT is a fluid treatment method whose composition and purpose are different from amino acid fluids and TPN fluids. IVNT may be applied to alleviating chronic fatigue, liver detoxification, anticancer effects in cancer patients, or relieving side effects from chemotherapy, depending on its components. IVNT can be applied to restore mitochondrial and adrenal dysfunction for alleviating chronic fatigue, and in the liver detoxification process, IVNT provides therapeutic effects through the supply of essential coenzymes and cofactors required for the liver detoxification phase and also reduces hepatic inflammation through antioxidant effects. Anti-cancer effects can be expected in cancer patients through high-dose antioxidant treatment. It is important for clinicians to select appropriate tests before applying IVNT to patients, and to apply appropriate IVNT through accurate differentiation diagnosis. In addition, Clinicians should familiarize with the precautions for each minerals and vitamins and be able to administer IVNT safely and effectively.

Tectonism and fracture-related dissolution induced the formation of the large-scale metamorphic granite reservoir: Implications from Bozhong 26–6 Precambrian bedrock trap, offshore Bohai Bay basin, Northern China

Crystalline rocks in basins are unconventional sites for hydrocarbon exploration. Owing to the lack of primary pores in the bedrock, it remains unclear how later tectonism and dissolution alter crystalline rock within large-scale reservoirs. Notably, the recent discovery of a 200 million-ton oil field of Precambrian metamorphic granite in the Bonan buried hill, Bohai Bay Basin, China provides an important opportunity for exploring this mechanism. Herein, the relationship between fractures and the regional tectonic evolution of this buried metamorphic granite mass, as well as the accompanying phenomena of dissolution and vein filling (which record related fluid interactions contributing to second pore formation from tight crystalline rocks) were investigated. The results indicated that the reservoir space was primarily composed of tectonic fractures and associated dissolution pores (maximum porosity ≤18%). The densely interlaced fractures with dominant NWW-trending flat surfaces indicated that the majority of Precambrian bedrock fractures were induced by Indosinian tectonic compression. The Cenozoic north–south tectonic extensional fault obliquely intersects these NWW-trending fractures, accounting for 73% of the previous dense shearing fractures transformed into open fractures. The dissolution pores were primarily distributed along the fractures and increased the porosity of these fracture-related reservoirs by ≤ 12%. The carbon and oxygen isotopes of the calcite fillings within the fractures suggested that atmospheric freshwater was the primary dissolution fluid, whereas some pores were formed by the dissolution action of deep hydrothermal and organic acid fluids. Thus, regional compressive stress is a necessary tectonic mechanism for the formation of densely interlaced fractures in tight crystalline rocks. The later extensional setting contributing to fracture release and fracture dissolution in the epi-diagenesis stage are two immediate factors in the formation of permeability and storage capacity within buried bedrock traps.

Texture and trace element characteristics of quartz in the Dongyuan porphyry W deposit, eastern China

Most W mineralization in the world is genetically related with highly fractionated granites, but little is known about ore-forming fluid evolution of W mineralization associated with weakly fractionated granites. To reveal the ore-forming fluid evolution of W mineralization related to the weakly fractionated granites, a combined study of field and petrographic observations, mineralogical, morphological, and in-situ geochemical data of different-type quartz from Dongyuan porphyry W deposit in the world-class Jiangnan W belt, China, was carried out. The petrographic observation and cathodoluminescence (CL) imaging revealed the quartz in the Dongyuan W deposit can be divided into hydrothermal quartz (Qz1 with core-edge structure, and Qz2 with oscillating zone) in the mineralized alteration zone, and magmatic quartz (Qz3 with inherited core) in granodiorite porphyry. The LA-ICP-MS results of the Dongyuan quartz samples show that Al may enter the quartz structure with trivalent Al3+ instead of Si4+, monovalent alkali metals and bivalent (Ge2+, Sr2+) cations is mainly of charge compensators in quartz, while Ti possibly is in the form of microinclusions of titanium-containing minerals in quartz. The integrated interpretation of the trace element compositions (e.g., Al and Ti contents, Al/Na ratios) and CL texture of quartz indicate high temperature (>400 °C) and uniform Al-rich acidic fluid are conducive to W precipitation of the Dongyuan deposit. Furthermore, trace element compositions (e.g., Ge, Al) and micro-textures of quartz have the potential for distinguishing magmatic and hydrothermal quartz in the Dongyuan W deposit.

A reactive-transport phase-field modelling approach of chemo-assisted cracking in saturated sandstone

Hydraulic fracturing and acidification techniques are important approaches for deep energy recovery engineering. However, the details of the interactions and impacts between acid fluids and solid porous media remain inadequately modelled, necessitating further research in this domain. Building on this need, we present a novel approach for modelling the chemo-hydro-mechanical response in sandstone during fracture propagation which is induced by the injection of acid fluids into the reservoir. Our comprehensive framework integrates various mechanisms including acidified reactions in sandstone, reactive flow transport, pore pressure diffusion, solid deformation, mass exchanges due to chemical reactions, and fracture propagation in poroelastic media, all within the framework of the phase field approach. To accurately capture the system’s behaviour, we derive its total potential energy, taking into account factors such as poroelasticity, fracture forces acting on the fracture sides, and crack dissipation, while also integrating the mechanical–chemical degradation function into the energy derivations. The progress of chemical degradation, which we treat as a damage parameter, is characterized by mass exchanges, and these in turn manifest as changes in porosity. In order to quantify these mass exchanges, we have established a corresponding mass balance equation specifically for the minerals involved. These changes in porosity can be naturally and effectively described through the volumetric relations of the minerals situated within the solid porous media. The proposed coupled framework is verified through multiple numerical examples. Initially, we validate the model using a classical unit-slit crack example for the solid phase and discuss the predominant influences of porosity alterations on the mechanical response of solid cracking. Following this, we verify the model by injecting water/acid and compare the results with analytical solutions. Finally, a chemical benchmark is employed to calibrate the chemical reaction model and simulate acid fluid injection scenarios.

Chemical pretreatment in lignocellulosic biomass, anaerobic digestion, and biomethanation

The current impacts of climate change necessitate the promotion and use of renewable energy sources to avert the growing environmental and health concerns emanating from fossil fuels. Lignocellulosic biomass (LCB) is a promising, renewable, and sustainable energy source based on its abundance and feedstock properties. Anaerobic digestion (AD) involves a biochemical process that can convert LCB to biogas through hydrolysis and biomethanation processes through the action of microorganisms such as methanogens and sulfate-reducing bacteria. The hydrolysis of LCB releases various reducing sugars, which are essential in the production of biofuels such as bioethanol and biogas, organic acids, phenols, and aldehydes. The resultant biogas can complement energy needs while achieving economic, environmental, and health benefits. Enhancement of the AD process for LCB to bioenergy can be realized through appropriate pretreatment capable of disrupting the complex lignocellulosic structure and freeing cellulose and hemicellulose from the binding lignin for enzymatic saccharification and fermentation. Determining the optimal pretreatment technique for AD is critical for the success of the LCB energy production process. This study evaluated the application of chemical pretreatment to the improvement of LCB digestion for bioenergy production. The study reviews the LCB characteristics, AD processes, and the role of various chemical pretreatment techniques such as acid, alkali, organosolv, ozonolysis, and ionic fluids. The findings of this study create an understanding of the action methods and benefits of different LCB chemical pretreatment techniques while highlighting the outstanding drawbacks that require divergent strategies.

More Than Metal–Organic Frameworks: Intestinal Villi‐Inspired Device as a Therapeutic Platform for Oral Enzyme Delivery

AbstractMacromolecules are fragile when orally administered. An intestinal villi‐inspired metal–organic frameworks (MOFs)‐based smart pill with multiple advantages is developed to offer a salubrious solution for oral delivery of enzymes. In the pill, MOFs accommodate enzymes as carriers exhibit excellent in vitro and in vivo catalytic activities with good oral biosafety, displaying supreme protection from degradation or inhibition in simulated gastrointestinal tract and high tolerance in simulated gastric acid and intestinal fluid. Moreover, the bioinspired pill possesses the morphology of the small intestinal villi obtained via an in situ moulding strategy for enhancing biocatalysis, which is attributed to the increase of surface area. Collaboratively, the adhesive layer renders increased smart pill in vivo retention, which is verified in pigs, providing a clinically translational and versatile platform for long‐term oral macromolecule delivery.

Study on pore structure and permeability sensitivity of tight oil reservoirs

The tight oil reservoir is rich in microscale pores, which has a significant impact on oil and water distribution and seepage. In this paper, first, the microscale pore-throat structure characteristics of tight oil reservoir is analyzed, and the injection medium sensitivity characteristics of the pore-throat structure is explored. Second, considering the dynamic evolution characteristics of permeability, the injection medium influence mode of permeability in tight reservoirs is elucidate. Results show that: (a). The average porosity ratio of microscale pores and small pores (64.35 %) is higher than that of mesoscale pores and large pores (35.65 %), indicating that there are more microscale pores and small pores developed in the reservoir. (b). The mineral content of reservoir rock is 23.93 % quartz, 8.48 % potassium feldspar, 27.28 % plagioclase, 17.63 % calcite, 5.65 % dolomite and 17.03 % clay mineral. (c). Acidic fluids have a weak improvement effect on the porosity of tight sandstone. The average total porosity change rate after interaction with 3 % HF is 8.06 %. (d). Acidic fluids have weak improvement on reservoir pore structure and strong improvement on reservoir permeability. Alkaline fluids have a strong improvement effect on reservoir fluids, but have a moderate to weak improvement effect on reservoir permeability.

Integrated PK/PD Modeling Relates Smoothened Inhibitor Biomarkers to The Heterogeneous Intratumor Disposition of Cetuximab in Pancreatic Cancer Tumor Models

Therapeutic antibodies have shown little efficacy in the treatment of pancreatic ductal adenocarcinomas (PDAC). Tumor desmoplasia, hypovascularity, and poor perfusion result in insufficient tumor cell exposure, contributing to treatment failure. Smoothened inhibitors of hedgehog signaling (sHHi) increase PDAC tumor permeability, perfusion, and drug delivery, and provide a tool to develop a quantitative, mechanistic understanding as to how the temporal dynamics of tumor priming can impact intratumor distribution of monoclonal antibodies (mAb). A linked pharmacokinetic (PK)/pharmacodynamic (PD) model was developed to integrate the plasma and tumor PK of a sHHi priming agent with its effects upon downstream stromal biomarkers Gli1, hyaluronic acid, and interstitial fluid pressure in PDAC patient-derived xenograft (PDX) tumors. In parallel, in situ tumor concentrations of cetuximab (CTX: anti-epidermal growth factor receptor; EGFR) were quantified as a marker for tumor delivery of mAb or antibody-drug conjugates. A minimal, physiologically-based pharmacokinetic (mPBPK) model was constructed to link sHHi effects upon mechanistic effectors of tumor barrier compromise with the intratumor distribution of CTX, and CTX occupancy of EGFR in tumors. Integration of the mPBPK model of mAb deposition and intratumor distribution with the PK/PD model of tumor responses to priming not only identified physiological parameters that are critical for tumor antibody distribution, but also provides insight into dosing regimens that could achieve maximal tumor disposition of therapeutic antibodies under conditions of transient PDAC tumor permeability barrier compromise that mechanistically-diverse tumor priming strategies may achieve.

Genetic Mechanism of Tabular-Shaped Orebody of the Hailijin Sandstone-Type Uranium Deposit in the Songliao Basin: Constraints on the Clay Mineralogy of Ore-Bearing Sandstone

The Hailijin (HLJ) sandstone-type uranium deposit was newly discovered in the southwestern Songliao Basin in recent years. Different from the roll-front orebody of the sandstone-type uranium deposits with (phreatic oxidation) interlayer redox origin (or phreatic oxidation), the orebody of the HLJ uranium deposit is tabular-shaped and multi-stratiform. The kaolinite content in ore-controlling gray sandstones is significantly higher than that in oxidized sandstones, which have the highest kaolinite content in the less oxidized zone of sandstone-type uranium deposits in the basins of western China (such as Yili Basin and Turpan-Hami Basin). In order to identify the properties of ore-forming fluids and the genesis of the tabular-shaped orebody of the HLJ uranium deposit, trace element, scanning electron microscopy (SEM), X-ray diffraction (XRD), and uranium mineral electron probe (EPMA) analyses of different geochemical zone sandstones in ore-bearing strata were carried out. As a result, kaolinite, illite, and illite/smectite formation (I/S) appear to alternate with one another in ore-controlling gray sandstones, and the content of kaolinite is the highest in ores. SEM analysis also suggests that uranium minerals are commonly adsorbed on the surface of foliated and vermicular kaolinite or trapped within micropores of kaolinite. In this case, it is inferred that kaolinite in ore-controlling gray sandstones is of epigenetic origin, and the ore-bearing sandstones have undergone at least one transformation of acidic fluids. Combined with the regional paleoclimate, regional tectonics, and regional burial history, it is concluded that the acidic fluid originated from the uranium-rich source rocks of the Lower Cretaceous Jiufotang Formation, and the tabular-shaped orebody of the HLJ uranium deposit was formed by exudative metallogeny. When the uranium-rich acidic organic fluids exuded upward from deep levels along the faults to the target strata, the solubility of uranium and other polymetallic elements decreased because of the decrease in temperature and pressure, and uranium eventually precipitated and accumulated in sandstones with suitable permeability and porosity. However, it cannot be ruled out that the superimposition and transformation of uranium mineralization was caused by phreatic oxidation or local interlayer redox during the interval of exudative metallogeny.

Predestinative role acidic cerebrospinal fluid on the destiny of central channel in spinal cord following subarachnoid hemorrhage: an experimental study.

Acidosis is the most dangerous complication in subarachnoid hemorrhage (SAH). This study aimed to investigate the effect of acidic cerebrospinal fluid on central canal structures after SAH. Twenty-eight hybrid rabbits were studied. Blood and cerebrospinal fluid pH values were recorded before/during/after the experimental procedures. The structures related to the central canals at the level of C5 of the cervical spinal cord were then examined histopathologically. The relationship between pH values of ependymal cells and degenerated epithelial cell densities was statistically analyzed. Mean blood pH values and degenerated ependymal cell density (n/mm2) were as follows: 7.351 ± 0.033/23 ± 7 in control, 7.322 ± 0.059/78 ± 13 in SHAM, and 7.261 ± 0.048/254 ± 62 in study animals. Gross examinations revealed swelling, edema, pia-arachnoid adhesions, ventral canal dilatation, arachnoiditis, central canal hemorrhage, occlusions, and dilatation in the spinal cord. Cerebrospinal fluid acidosis-induced central channel pathologies should be considered an important complication of SAH following SAH.

Screening and genome analysis of lactic acid bacteria with high exopolysaccharide production and good probiotic properties

Exopolysaccharide (EPS) is a biological polymer produced by lactic acid bacteria (LAB) with various health-beneficial biological activities, such as hypoglycemic, antioxidant, hypocholesterolemic, and immune-regulatory effects. As a food-grade material, EPS could be used directly in food processing and production. In this study, 48 laboratory-preserved LAB strains were screened for high exopolysaccharide production, the best five of which were M-1 (0.90 g/L), M-2 (0.79 g/L), MY04 (1.15 g/L), M-5 (0.85 g/L) and M-7 (0.75 g/L). The prebiotic properties of these five strains were compared and MY04 had the best overall properties, with good resistance to acid, bile salts, and simulated gastrointestinal fluid, strong antibacterial activity and high intestinal adhesion capacity. Whole genome sequence analysis of virulence factors and drug resistance genes, determined that Lactiplantibacillus plantarum MY04 is safe for human consumption and a promising probiotic candidate for development of novel functional foods.

Supernormal enrichment of cadmium in sphalerite via coupled dissolution-reprecipitation process

Supernormal enrichment of cadmium in sphalerite is frequently observed in some sedimentary-hosted zinc-lead deposits, although related fluid process remains unconstrained. At the Jinding Mississippi Valley-type deposit, a considerable portion of cadmium has been remobilized from early sphalerite through coupled dissolution-reprecipitation reaction to form high-grade ores. Here we report natural occurrence of various sulfide nanoparticles and related textures in sphalerite that help document this process. A nanoscale study by transmission electron microscopy provides a rare glimpse of phase transition of cadmium from lattice-bond impurity, composition anomaly along planar defects, aggregates of hexagonal cadmium sulfide nanoparticles, to crystalline greenockite inclusions. Such a process may be mediated by oxidative dissolution on early-formed cadmiferous sphalerite during injection of cadmium-rich oxidative acidic fluids. This study provides an alternative mechanism versus exclusively solid-state diffusion for dispersed elements’ redistribution in hydrothermal ore deposits. It also sheds light on artificial synthesis of II-VI semiconductor nanomaterials by similar methods.

Evolution characteristics and exploration targets of Permian clastic rock reservoirs in Bohai Bay Basin, East China

Based on core observation, thin section examination, fluid inclusions analysis, carbon and oxygen isotopic composition analysis, and other approaches, the structural and burial evolution histories were investigated, and the diagenetic evolution process and genetic/development models were systematically discussed of the Upper Paleozoic Permian clastic rock reservoirs in the Bohai Bay Basin, East China. The Bohai Bay Basin underwent three stages of burial and two stages of uplifting in the Upper Paleozoic. Consequently, three stages of acid dissolution generated by the thermal evolution of kerogen, and two stages of meteoric freshwater leaching occurred. Dissolution in deeply buried, nearly closed diagenetic system was associated with the precipitation of authigenic clay and quartz, leading to a limited increase in storage space. Different structural uplifting–subsidence processes of tectonic zones resulted in varying diagenetic–reservoir-forming processes of the Permian clastic reservoirs. Three genetic models of reservoirs are recognized. The Model I reservoirs with pores formed in shallow strata and buried in shallow to medium strata underwent two stages of exposure to long-term open environment and two stages of meteoric freshwater leaching to enhance pores near the surface, and were shallowly buried in the late stage, exhibiting the dominance of secondary pores and the best physical properties. The Model II reservoirs with pores formed in shallow strata and preserved due to modification after deep burial experienced an early exposure-open to late burial-closed environment, where pore types were modified due to dissolution, exhibiting the dominance of numerous secondary solution pores in feldspar and the physical properties inferior to Model I. The Model III reservoirs with pores formed after being regulated after multiple periods of burial and dissolution experienced a dissolution of acidic fluids of organic origin under a near-closed to closed environment, exhibiting the dominance of intercrystalline micropores in kaolinite and the poorest physical properties. The target reservoirs lied in the waterflood area in the geological period of meteoric freshwater leaching, and are now the Model II deep reservoirs in the slope zone–depression zone. They are determined as favorable options for subsequent exploration.

Ascorbate oxidation driven by PM2.5-bound metal(loid)s extracted in an acidic simulated lung fluid in relation to their bioaccessibility

The oxidative potential (OP) is defined as the ability of inhaled PM components to catalytically/non-catalytically generate reactive oxygen species (ROS) and deplete lung antioxidants. Although several studies have measured the OP of particulate matter (PM OP) soluble components using different antioxidants under neutral pH conditions, few studies have measured PM OP with acidic lung fluids. This study provides new insights into the use of acidic rather than neutral fluids in OP assays. Thus, the first aim of this study was to clarify the effect of using an acidic lung fluid on ascorbic acid (AA) depletion. This was achieved by measuring the oxidative potential (OP-AA) of individual compounds known to catalyze the AA oxidation (CuSO4, CuCl2, and 1,4-NQ) in artificial lysosomal fluid (ALF, pH 4.5), a commonly used acidic simulated lung fluid, and in a neutral fluid (phosphate-buffered saline (PBS1x), pH 7.4). Our results from these individual compounds showed a significant decrease of OP-AA in the acidic fluid (ALF) with respect to the neutral fluid (PBS). Then, the second aim of this work was to investigate whether the OP-AA assay could be applied to PM2.5 samples extracted in acidic conditions. For this purpose, OP-AA and bioaccessible concentrations of metal(loid)s (V, Mn, Fe, Ni, Cu, Zn, As, Mo, Cd, Sb, and Pb) of PM2.5 samples collected in an urban-industrial area that were extracted in ALF were analyzed. The mean volume-normalized OP (OP-AAv) value was 0.10 ± 0.07 nmol min−1 m−3, clearly lower than the values found in the literature at neutral pH. OP-AAv values were highly correlated with the ALF-bioaccessible concentration of most of the studied metal(loid)s, mainly with Cu and Fe.

Characterization and Performance Evaluation of Modified Apatite Ore as a New Acid-Soluble Weighting Agent for Drilling Fluids

Summary Drilling in oil and gas reservoir formations requires the solid weighting agent used in drilling fluids to have good acid solubility to facilitate plugging removal in subsequent operations. Limestone is the most commonly used acid-soluble weighting agent, but its low density and significant thickening effect lead to a low weighting limit. To achieve control of drilling fluid density, rheology, sag stability, and acid solubility, the feasibility of using apatite (AP) ore as an acid-soluble weighting agent for drilling fluids has been discussed after it was modified by the nitrogen-containing organic polybasic phosphonic acid sodium salt. The basic characteristics of AP and modified AP (MAP) were analyzed. After that, the rheological, filtration, and sag stability properties of MAP-weighted water-based drilling fluids with densities of 1.2 g/cm3 and 1.6 g/cm3 were evaluated, and acid solubility, filter-cake permeability, core permeability damage, and plugging removal tests by acid solutions were performed to evaluate the formation protection effect. The results show that the density of AP is 2.98 g/cm3, and the main component is hydroxyapatite. Its negative electricity and hydrophilicity were enhanced after surface modification, so its dispersion stability in water was enhanced, thereby improving the rheology, filtration, and sag stability properties of the MAP-weighted drilling fluid. The solubility of MAP in 10% HCl solution reached 90.13%, and the core contamination experiments show that after being soaked in HCl solution, the return permeability of contaminated cores reached higher than 90%, indicating that the MAP invading the core can be efficiently dissolved and removed in the acidic working fluids used in the subsequent completion and stimulation operations, thus effectively protecting the reservoir formation. The properties of MAP are superior to those of limestone, and it can be used as a new acid-soluble weighting agent for drilling fluids, considering both drilling fluid performance regulation and reservoir formation protection.