Greater Absorption Research Articles

Withered magnolia-derived BCDs onto 3D flower-like Bi2WO6 for efficient photocatalytic TC degradation and CO2 reduction

The biomass-derived carbon quantum dots (BCDs, explored from the withered magnolia blossom) modified Bi2WO6 (Bi2WO6/BCDs) was prepared and used to remove the water contaminants. The biomass-derived carbon quantum dots-modified Bi2WO6 was synthesized by the unique hydrothermal technology and dialyzed method, showing excellent photocatalytic degradation activity of tetracycline and CO2 photoreduction performance. The Bi2WO6/BCDs showed a better tetracycline (TC) degradation efficiency than that of Bi2WO6 (49 %) under the visible light, when mass of BCDs was 15 μL. Additionally, photo-electrochemical measurements proved the separation efficiency of electron-holes of Bi2WO6 was enhanced, due to the great electron transmission ability and light absorption of BCDs. The mechanism experiment showed that ·O2- was the main activity specie in the TC photodegradation process. Meanwhile, the Bi2WO6/BCDs also showed higher CO2 photoreduction performance to CO (18.2 μmol/g) under UV–vis light than the pure Bi2WO6. The CO2 reduction mechanism also investigated by in-situ FTIR. The favorable photocatalytic performances make the waste biomass carbon act as a new resource of application to wastewater treatment and carbon recycling process.

Preparation, optimization, and characterization of chrysin-loaded TPGS-b-PCL micelles and assessment of their cytotoxic potential in human liver cancer (Hep G2) cell lines

In total, nine TPGS-b-PCL copolymers were synthesized employing distinct TPGS analogues (TPGS 2000, 3500, and 5000). In these copolymers, the length of the PCL chain varied according to the TPGS to PCL molecular weight ratio (1:1, 1:2, and 1:3). The formulation optimization was done by optimizing the drug to polymer ratio, encapsulation efficiency, drug loading, micelle diameter, and polydispersity index (PDI). TPGS3500-b-PCL7000 copolymer (TPGS to PCL ratio 1:2) with drug to polymer ratio 1:30 showed the best percentage encapsulation (63.50 ± 0.45 %) and drug loading (2.05 ± 0.07). The optimal micelle (CHR-M) diameter and PDI were determined to be 94.57 ± 13.40 nm and 0.16 ± 0.02, respectively. CHR-M showed slow release when compared with alcoholic solution of chrysin. Approximately 70.70 ± 6.4 % drug was released in 72 h. The CHR-M demonstrated considerably greater absorption in Hep G2 cells, which confirmed the reliability of the micellar carrier. The MTT assay results showed that the IC50 values for CHR-M were much lower after 24 and 48 h when compared to free chrysin. Therefore, CHR-M may be a viable carrier for active chrysin targeting with improved anticancer potential. Also, it could be a better alternative for the currently available treatment of hepatocellular carcinoma.

Picroside-1-Phytovesicle: A novel approach for Antihepatotoxic activity

Picroside-I, the irridoid glycoside component obtained from Picrorhiza kurroa Royal Ex. Benth. extract was stoichiometrically complexed with phospholipids to form Phytosome. These complexes were characterized by IR and 1H-NMR spectroscopy. The efficacy of phytosome formulation was determined by in vitro GIT absorption study which indicates greater absorption from gastrointestinal tract, resulted in higher plasma levels. The hepatic protection offered by phytosomes was studied against CCl4 induced hepatotoxicity and compared with picroside-I, by measuring bio-chemical parameters in terms of SGOT and SGPT enzyme levels. Phytosomes exhibited appreciable greater hepatoprotection than that of picroside-I alone. Therefore, phytosome can advantageously be used in acute and chronic liver disease of varying origin.

FORMULATION AND EVALUATION OF HERBAL FLOATING TABLET BRAHMI FOR PEPTIC ULCER

The Development and Assessment of a Herbal Floating Tablet for Peptic Ulcer Disease. The goal of creating a herbal floating tablet is to extend the drugs duration in the gastrointestinal tract. This will increase the drugs bioavailability and result in greater absorption than with a convectional dose form. Due to its gastro-retentive feature, the medicine remains at the site of inflammation for a longer amount of time, resulting in a more targeted action and fewer adverse effects than with conventional dose forms. Both industrialised and developing nations have seen a sharp rise in the usage of herbal products in recent years. One of the most significant medicinal plants, Bacopa Monnieri (Brahmi), has several beneficial properties including anti-ulcer, anti-inflammatory, anti-microbial, hepatoprotective, analgesic, antipyretic, anti-bacterial, and anti-fungal properties. Due to a number of factors, peptic ulcer disease is very common in the community. KEYWORDS: Brahmi, Formulation, Quality control parameters, Evaluation

Multi-residue method of pesticides by UPLC-MS/MS in bivalve mollusks samples as a tool for food quality and safety

Bivalve molluscs (BM) are filter animals and bioaccumulators of substances from the environment. This characteristic allows a great absorption of nutrients that makes them a source of protein-rich foods. On the other hand, if there are toxic contaminants in the environment, their absorption by animals may occur. This happens with pesticides coming from agricultural and livestock production systems that can migrate to areas of BM crops. Considering the high nutritional value of bivalve molluscs and their positive impact on the human diet, these products must be carefully evaluated for the possible presence of toxic substances in order to guarantee their safety.
 Thus, the aim of this work was to implement and validate a multi-residue method using tandem mass spectrometry to evaluate pesticide residues commonly used in agricultural production systems present in these matrices. Extraction and cleaning steps were optimized and the method proved to be adequate to quantify 322 pesticides. The samples come from five different areas of culture of bivalve molluscs in the southeast, north and northeast regions of Brazil. The analysis of the mollusc samples showed the presence at the trace level of seven different pesticide residues in four of the five evaluated samples.

Evaluation of novel aqueous piperazine-based physical-chemical solutions as biphasic solvents for CO2 capture: Initial absorption rate, equilibrium solubility, phase separation and desorption rate

Novel aqueous piperazine-based physical–chemical solutions were proposed as promising liquid–liquid biphasic solvents for energy-efficient CO2 capture in order to enhance the absorption and desorption performance. Various phase-change systems including Piperazine (PZ), 1-(2-aminoethyl) piperazine (AEP), methyldiethanolamine (MDEA), sulfolane, 1-propanol and water with different concentration ratios were investigated comprehensively in terms of initial absorption rate, equilibrium solubility, phase splitting and desorption rate in the present work. Experimental results indicated that with the aid of organic solvents, PZ and AEP were proved to be promising candidates to accelerate the initial absorption and desorption rates, as well as enhance the CO2 absorption capacity due to their excellent reaction kinetics. The tunable phase separation property could be achieved by varying the concentration ratios of amine/organic solvent. After achieving equilibrium, the two liquid–liquid phases would not return back to one homogeneous liquid phase. Among these biphasic solvents, aqueous 2.5 M PZ + 2.5 M sulfolane with a large CO2 loading 0.85 mol CO2/mol amine at the phase change point was the optimal choice owing to good phase separation and great absorption and desorption properties. Compared to aqueous 2.5 M PZ single solvent, it demonstrated a 16% higher initial absorption rate, 9% larger CO2 absorption capacity and double desorption rate. This research provided a potential alternative absorbent for CO2 capture.

Inside vertical reconstruction effect enhances internal polarization field in MXenes for regulating photocatalytic water splitting

We theoretically report four photocatalyst candidates, namely, Sc2COS, Sc2CSO, Sc2COSe, and Sc2CSeO. A mirror asymmetry atom structure endows Sc2COS with the largest intrinsic built-in electric field (EF) of 7.53 × 109 V/m among these monolayers, facilitating the separation of photogenerated electron–hole pairs. Sc2CSO and Sc2CSeO with smaller EF are half-reaction water splitting photocatalysts, performing the hydrogen evolution reaction. It is highly interesting that C atoms aligned to the top S or Se atoms move down by about 0.40 Å and are vertically aligned to the bottom O atoms, named as the inside vertical reconstruction. Therefore, Sc2CSO (Sc2CSeO) transforms into Sc2COS (Sc2COSe) with larger EF, suitable for photocatalytic overall water splitting. They have great optical absorption with optical absorption coefficients up to 105 cm−1. Our work reveals the physical mechanism of EF enhancement caused by inside vertical reconstruction effect facilitates overall water splitting, which provides a feasible strategy for theoretically designing intriguing photocatalysts.

Rubberized Geopolymer Mortar and Concrete: A Comprehensive Review.

In many crucial structural applications, a material’s ability to withstand impact is of the utmost importance. The use of crumb rubber particles as a partial replacement of natural aggregates forms rubberized geopolymer concrete (RuGPC), which is found to have great impact resistance and energy absorption capacity. Geopolymer paste and natural aggregates alone are weak in handling the impact loads. The field of Civil engineering has been looking into ways for the last few years to use solid waste and ecologically friendly raw materials as components of concrete in building to embrace sustainability. Greenhouse gas emissions from cement manufacturing and the depletion of natural aggregates are two major issues the construction industry is currently experiencing. RuGPC, which combines the benefits of geopolymer concrete (GPC) and rubberized concrete to create a practical, sustainable building material, has been a hot topic for the past few years. In this paper, the fresh properties, strength and durability characteristics, mixing procedure and curing properties, dynamic and impact properties, microstructures and thermal properties of rubberized geopolymer mortar and concrete are comprehensively reviewed.

Exogenous Auxin and Gibberellin on Fluoride Phytoremediation by Eichhornia crassipes.

High rates of fluorosis were reported worldwide as a result of human consumption of water with fluoride contents. Adjusting fluoride concentration in water as recommended by the World Health Organization (<1.5 mg L-1) is a concern and it needs to be conducted through inexpensive, but efficient techniques, such as phytoremediation. The application of phytohormones was investigated as a strategy to improve this process. Thus, the main goal of this research was to evaluate the effect of exogenous auxin and gibberellin on the tropical duckweed Eichhornia crassipes performance for fluoride phytoremediation. Definitive screening and central composite rotatable designs were used for experiments where fluoride concentration (5~15 mg L-1), phosphorus concentration (1~10 mg L-1), and pH (5~9) were assessed as well throughout 10 days. Fluoride contents were determined in solution and plant tissues by potentiometry. Higher concentrations of fluoride reflected on greater absorptions by plants, though in relative terms removal efficiencies were quite similar for all treatments (~60%). Auxin and acidic conditions favored fluoride removals per mass of plant. Fluoride accumulated mostly in leaves and auxin probably alleviated toxic effects on E. crassipes while gibberellin showed no effect. Therefore, E. crassipes could be employed as a fluoride accumulator plant for water treatment and exogenous auxin may be used to improve the process.

Multifunctional Nanoparticles and Nanopesticides in Agricultural Application

The unscientific application of pesticides can easily cause a series of ecological environmental safety issues, which seriously restrict the sustainable development of modern agriculture. The great progress in nanotechnology has allowed the continuous development of plant protection strategies. The nanonization and delivery of pesticides offer many advantages, including their greater absorption and conduction by plants, improved efficacy, reduced dosage, delayed resistance, reduced residues, and protection from natural enemies and beneficial insects. In this review, we focus on the recent advances in multifunctional nanoparticles and nanopesticides. The definition of nanopesticides, the types of nanoparticles used in agriculture and their specific synergistic mechanisms are introduced, their safety is evaluated, and their future application prospects, about which the public is concerned, are examined.

Number Needed to Treat and Number Needed to Harm From Two Phase 3 Studies of Sublingual Dexmedetomidine for Treating Acute Agitation in Patients With Schizophrenia and Bipolar Disorder

AbstractBackgroundEpisodes of acute agitation can occur in individuals who suffer from schizophrenia or bipolar disorder and these can be a significant challenge for patients and for those who provide care to them. Sublingual dexmedetomidine is a selective alpha2-adrenergic receptor agonist that was recently approved by the US Food and Drug Administration for the treatment of agitation in adults with schizophrenia or bipolar disorder. The sublingual form of dexmedetomidine does not undergo first-pass hepatic metabolism, thus resulting in greater absorption than when ingested. In two Phase 3 studies of adults with schizophrenia or bipolar disorder, sublingual dexmedetomidine significantly reduced acute agitation at 2 hours, as measured by the five-item Positive and Negative Syndrome Scale-Excited Component (PEC). When initially appraising the potential utility of a new medication, number needed to treat (NNT) and needed to harm (NNH) can be helpful to assess the size of the treatment effect and, hence, clinical relevance.ObjectiveCalculation of NNT and NNH through post hoc analysis of Phase 3 data.MethodsPost hoc analysis of data were performed on data from two double-blind, randomized, placebo-controlled studies of sublingual dexmedetomidine in adults with schizophrenia or bipolar disorder experiencing acute agitation. Patients were randomized to a single dose of sublingual dexmedetomidine 180 μg, 120 μg, or placebo. The primary endpoint was mean change from baseline in the PEC total score. A therapeutic response was defined as a ≥40% reduction from baseline in PEC total score at 2 hours. NNT was calculated for PEC response rate for sublingual dexmedetomidine versus placebo. NNH was calculated using the incidence of adverse events for sublingual dexmedetomidine versus placebo. Likelihood to be helped or harmed (LHH) was calculated as the ratio of NNH to NNT.ResultsNNT (95% CI) was 3 (2, 3) for 180 mcg and 3 (3, 4) for 120 ug in patients with schizophrenia and 3 (2, 3) for 180 mcg and 4 (3, 6) for 120 ug in patients with bipolar disorder. NNH was greater than 10 for all AEs except somnolence, where NNH was 7 (5, 10) for all doses pooled from both studies. LLH values were greater than 1 for efficacy versus applicable tolerability outcomes in all cases.ConclusionsThis post hoc analysis demonstrated favorable NNT and NNH values for sublingual dexmedetomidine. In all instances therapeutic response was encountered more frequently than any adverse event. These values compare favorably to similar analyses for other approved agents for the treatment of agitation associated with schizophrenia or bipolar disorder, including intramuscular and inhaled formulations.FundingBioXcel Therapeutics, Inc.

The perception of plastic surgery during the COVID-19 pandemic—an analysis of online search patterns on a medical information platform

In 2020, the COVID-19 pandemic impacted global life and transitioned economies and societal perceptions of life as we knew it. Professional and social life mostly ground to a nadir during the first lockdown in Europe in March. As a consequence, measures aimed at preventing the spread of the virus were established in medical facilities also and elective plastic surgery procedures were temporarily suspended in our clinic and others. A majority of the population, including those potentially contemplating plastic surgery procedures, spent most of their time at home with ample time available to research information about surgical procedures and other topics online. This investigation analyzes the relevance of plastic surgery during the pandemic on the basis of online search behavior patterns. Online traffic data from the online platform http://www.mooci.org were extracted using Google Analytics over a period of 6 months. The parameters analyzed were: pageviews, session duration, and bounce rate. Additionally, differentiation by areas of interest has been obtained. The data were compared and analyzed before and after the beginning of the first hard lockdown in Austria, Germany, and Switzerland. There were no significant differences in regard to pageviews and session duration when comparing time points before and after the beginning of the hard lockdown. The bounce rate exhibited a significant decrease after the beginning of the lockdown, implying a more conscious search for information and greater absorption and retention. There was no difference that could conclusively be attributed to the pandemic in terms of specific areas of interest researched. Society’s demand for information about plastic-surgical procedures continues to be steadily prevalent—despite, or even in particular, during a global pandemic. Providing reliable and readily available information about plastic surgery procedures is an important component of a functioning doctor–patient relationship and informed consent. This information may reflect society’s increased interest in plastic surgery during the pandemic, or be simply reflective of more spare time at hand to allow for such research. Further studies should investigate the relevance of elective procedures over the entire course of the pandemic.

Highly boosted trace-amount terahertz vibrational absorption spectroscopy based on defect one-dimensional photonic crystal.

Although terahertz (THz) spectroscopy demonstrates great application prospects in the fields of fingerprint sensing and detection, traditional sensing schemes face unavoidable limitations in the analysis of trace-amount samples. In this Letter, a novel, to the best of our knowledge, absorption spectroscopy enhancement strategy based on a defect one-dimensional photonic crystal (1D-PC) structure is proposed to achieve strong wideband terahertz wave-matter interactions for trace-amount samples. Based on the Fabry-Pérot resonance effect, the local electric field in a thin-film sample can be boosted by changing the length of the photonic crystal defect cavity, so that the wideband signal of the sample fingerprint can be greatly enhanced. This method exhibits a great absorption enhancement factor, of about 55 times, in a wide terahertz frequency range, facilitating the identification of different samples, such as thin α-lactose films. The investigation reported in this Letter provides a new research idea for enhancing the wide terahertz absorption spectroscopy of trace samples.

Strong light-matter interaction and antireflection functionality of f-TiO2/GaN heterostructure broadband photodetector

Recent research focusing on broadband photodetectors offers a diverse range of applications like civilian, military, medical, etc. However, the available broadband photodetectors unable to retain high state-of-art performance parameters when operating at wide bandwidth. Herein, we report a broadband photodetector based on fibrils like TiO2 (f−TiO2) and GaN heterostructure. The TiO2 thin film has a high density of photo-generated charge carriers due to its great light absorption, antireflective, and highly oxidizing properties. These features of TiO2 enable a considerable increase in photocurrent for f−TiO2/GaN heterostructures compared to bare GaN, which provided a massive gain in the figure-of-merit performance metrics of f−TiO2/GaN-based devices. The fabricated f−TiO2/GaN device exhibits excellent optoelectronic characteristics, such as high responsivity (3.4 × 104 AW−1), outstanding external quantum efficiency (1.2 × 107 %), and detectivity (2.4 × 1012 Jones) under a weak optical signal of 90 nW. The design heterostructure-based photodetector also noticeably responds to illumination between the wavelengths of 250 nm and 780 nm. Additionally, TiO2 exhibits antimicrobial surface behavior, making it the best choice for pervasive biological and medical applications. Thus, TiO2/GaN heterostructure-based device like environmental screening, agriculture, medicine, and biodefense have proven their immense versatility in next-generation sequencing technology, medical science, cutting-edge crops, and creating interactive environments.

Enhanced visible light catalytic activity of holey Ti3C2 based catalyst for azo dyes

The efficient degradation of organic dye pollutions is of great importance for environmental remediation. In this work, we prepared holey Ti3C2 (H-Ti3C2) and further synthesized H-Ti3C2/Ag/AgX (Cl, Br, I) Schottky catalysts by a simple electrostatic self-assembly method, and found that H-Ti3C2 could significantly improve the catalytic activity and stability of AgX. The H-Ti3C2/Ag/AgX composites showed great visible light absorption, obvious photocurrent intensity, and high charge transfer efficiency, ultimately improving photocatalytic efficacy for the degradation of methyl orange (MO) dye. The composite (5 wt%) H-Ti3C2/Ag/AgBr has the greatest photocatalytic activity, degrading 99.2% of the MO solution after 40 min of visible light irradiation, which is 1.08 and 2.02 times more than (5 wt%) Ti3C2 /Ag/AgBr and Ag/AgBr, respectively. The photocatalytic performance of H-Ti3C2/Ag/AgBr for MO dyes remains at 51% after five cycles. This result indicates that combining H-Ti3C2 with other photosensitive semiconductors to improve the catalytic activity and stability offers great possibilities. The present work not only provides a simplified method for the preparation of H-Ti3C2/Ag/AgX composites, but also offers a great possibility for H-Ti3C2 MXene as a co-catalyst to increase the photocatalytic degradation efficiency of organic pollutants.

NIR-II driven photocatalytic hydrogen peroxide-supply on metallic copper-nickel selenide (Cu-Ni0.85Se) nanoparticle for synergistic therapy

Currently, finite intratumoral H2O2 content has restricted the efficacy of chemodynamic therapy (CDT). Here, Cu-Ni0.85Se@PEG nanoparticles are constructed to display intracellular NIR-II photocatalytic H2O2 supplement. The formation mechanism is explored to discover that H2O2 generation is dominated by photo-excited electrons and dissolved O2 via a typical sequential single-electron transfer process. Both density functional theory calculation and experimental data confirm its metallic feature that endows the great NIR-II absorption and photothermal conversion efficiency (59.6 %, 1064 nm). Furthermore, the photothermal-assisting consecutive interband and intraband transition in metallic catalyst contributes to the high redox capacity and efficient separation/transfer ability of photo-generated charges, boosting H2O2 production under 1064 nm laser irradiation. In addition, Cu-Ni0.85Se@PEG possess mimic peroxidase and catalase activity, leading to in-situ H2O2 activation to produce ∙OH and O2 for the enhanced CDT and hypoxia relief. What’s more, the nanomaterials reveal novel biodegradation that is derived from oxidation from insolvable selenide into soluble selenate, resulting in elimination via feces and urine within 2 weeks. Synergistic CDT and photothermal therapy (PTT) further lead to great tumor inhibition and immune response for anti-tumor. The antitumor mechanism and the potential biological process also are investigated by high-throughput sequencing of expressed transcripts (RNAseq). The great treatment performance is responsible for the regulation of related oxidative stress and stimulus genes to induce organelle (mitochondrial) and membrane dysfunction. Besides, the synergistic therapy also can efficiently evoke immune response to further fight against tumor.

4,4−Diaminodiphenyl methane functionalized reduced graphene oxide/CoFe−layered double hydroxide obtained by in−situ hydrothermal as a high−performance absorber

The self−assembly among different two−dimensional materials could effectively improve the self−stacking effect and promote repeated reflection and refraction of incident electromagnetic wave (EMW). The polarization effect caused by the heterogeneous contact also helps the attenuation of EMW. In this study, the in−situ hydrothermal approach was used to effectively fabricate petal−like CoFe−layered double hydroxide sheets (CoFe−LDH) grown on reduced graphene oxide (RGO) functionalized by 4,4−diaminodiphenyl methane (DDM). The microwave absorption properties of DDM−functionalized RGO/CoFe−layered double hydroxide composites (DDM−RGO/LDH) were investigated. When the loading of DDM−RGO is 40.0 ​mg, the reflection loss reached −60.0 ​dB at 5.28 ​GHz, resulting in great EMW absorption performance. The effective absorption bandwidth at 2.00 ​mm is 5.28 ​GHz. The results show that DDM−RGO/LDH has a wide microwave absorption bandwidth and strong absorption capability, thus could be applied as an advanced EMW absorbing material.

Experimental Investigation of Effect of L-Profile Hybrid Aluminium/GFRP to the Axial and Lateral Characteristic.

The current study investigates the effect of a hybrid L-profile aluminium/glass-fiber-reinforced polymer stacking sequence under axial and lateral compression loads. Four stacking sequences are studied: aluminium (A)-glass-fiber (GF)-AGF, GFA, GFAGF, and AGFA. In the axial compression test, the aluminium/GFRP hybrid tends to crush in a more progressive and stable failure than the net aluminium and net GFRP specimens, with a relatively more stable load-carrying capacity throughout the experimental tests. The AGF stacking sequence was second, with an energy absorption of 145.31 kJ, following AGFA at 157.19 kJ. The load-carrying capacity of AGFA was the highest, with an average peak crushing force of 24.59 kN. The second-highest peak crushing force, 14.94 kN, was achieved by GFAGF. The highest amount of energy absorption, 157.19 J, was achieved by the AGFA specimen. The lateral compression test showed a significant increase in load-carrying and energy absorption capacity in the aluminium/GFRP hybrid specimens compared to the net GFRP specimens. AGF had the highest energy absorption with 10.41 J, followed by AGFA with 9.49 J. AGF also had the highest peak crushing force with 2.98 kN, followed by AGFA with 2.16 kN. The most crashworthy stacking sequence among the four variations tested in this experimental research was the AGF stacking sequence because of its great load-carrying capacity, energy absorption, and specific energy absorption in axial and lateral loading. The study provides greater insight into the failure of hybrid composite laminates under lateral and axial compression.

Covalent Bonding of MXene/Reduced Graphene Oxide Composites for Efficient Electromagnetic Wave Absorption

Due to their high conductivity and unique surface chemical characteristics, MXene and reduced graphene oxide (rGO) have received a great deal of attention in the field of electromagnetic wave absorption (EMA). This study describes the covalent modification of rGO with amino-functionalized MXene to create an electromagnetic absorbent material called MXene-rGO composite. After amidation, an amide bond successfully assembles MXene and rGO. The absorber performs admirably when the mass ratio of MXene to rGO is 1:2 (sample MG-3). With a thickness of 2.7 mm, the best reflection loss (RL) is −47.98 dB at 6.4 GHz. Additionally, the best effective absorption bandwidth (EAB) (RL< −10 dB) is 4.08 GHz (11.84–15.92 GHz) with a 1.4 mm matching thickness. The performance of the EMA can be obtained by adjusting the dielectric parameters and the migration rate of the electrons using the covalent bond as a stable carrier channel. The high dielectric loss, superior impedance matching, and strong attenuation ability contribute to the great absorption performance.

Molecular Dynamics Simulation of Adsorption and Absorption Behavior of Shale Oil in Realistic Kerogen Slits

Exploring the occurrence of shale oil is of guiding significance to the exploration and recovery of shale oil. However, most studies focus on adsorption and neglect absorption or study it independently, which weakens the understanding of the coupling relationship between adsorption and absorption and the occurrence mechanism of shale oil in kerogen and its associated pores. Based on molecular dynamics (MD) simulation, the kerogen matrix with a smooth surface is constructed, and the general amber force field is adopted to calculate the adsorption and absorption of shale oil in a type II kerogen slit, and the influences of temperature, pressure, and pore diameter on the occurrence of shale oil are also discussed. Molecules absorbed in the kerogen matrix are mainly retained in the free space formed by the accumulation of aliphatic carbon. The effects of temperature on the distribution of shale oil in adsorption and absorption are opposite. High temperature improves the desorption of molecules from the adsorption sites and causes a lower adsorption and greater absorption. In contrast, pressure and pore diameter only slightly influence the distribution of shale oil. Unexpectedly, the result under aqueous conditions shows that the shale oil was absorbed quickly before the formation of water clusters. Once the water clusters are formed due to the strong hydrogen bonding and adsorbed near the N-, S-, and O-containing groups on the kerogen surface, the matrix gaps are blocked due to the size exclusion, and the absorption is suppressed. Additionally, we established the evolution of the ratio of free-adsorbed–absorbed oil at different temperatures and pressures, which provides a new idea and a new method for detecting the occurrence and mobility evaluation of shale oil under reservoir conditions.