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1.
Fundam Clin Pharmacol ; 38(1): 113-125, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37490927

RESUMEN

BACKGROUND: Dihydroartemisinin (DHA) is an artemisinin derivative known for its antimalarial properties. It has also shown potential as an anti-tumor and anti-angiogenic agent. However, its specific role in inhibiting angiogenesis in breast cancer is not well understood. OBJECTIVES: We aimed to investigate the anti-angiogenesis effect of DHA on breast cancer and explore its potential as a therapeutic drug. Our objectives were to assess the impact of DHA on neovascularization induced by MDA-MB-231 cells, evaluate its effects on vessel sprout and tube-formation in vascular endothelial cells, and analyze the expression of key angiogenesis-related proteins. METHODS: Using a chicken chorioallantoic membrane (CAM) model, we cultured MDA-MB-231 cells and treated them with DHA. We assessed neovascularization and cultured vascular endothelial cells with DHA-treated cell media to evaluate vessel sprout and tube-formation. Protein expression levels of VEGF, MMP-2, and MMP-9 were analyzed using Western blotting. RESULTS: DHA significantly attenuated neovascularization induced by MDA-MB-231 cells. It also suppressed vessel sprout and tube-formation of HUVEC cells when exposed to DHA-treated cell media. Furthermore, DHA downregulated the expression of VEGF, MMP-2, and MMP-9 proteins. Mechanistically, DHA inhibited the phosphorylation of PI3K, AKT, ERK, and NF-κB proteins in tumor cells. CONCLUSIONS: Our study provides evidence of the inhibitory effect of DHA on breast cancer angiogenesis. These findings support the potential of DHA as an anti-breast cancer drug and warrant further investigation for its therapeutic applications.


Asunto(s)
Artemisininas , Neoplasias , Factor A de Crecimiento Endotelial Vascular , Humanos , Factor A de Crecimiento Endotelial Vascular/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Metaloproteinasa 2 de la Matriz/metabolismo , Angiogénesis , Inhibidores de la Angiogénesis/farmacología , Células Endoteliales de la Vena Umbilical Humana , Línea Celular Tumoral
2.
Curr Med Sci ; 43(4): 655-667, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37391677

RESUMEN

OBJECTIVE: Tumor-associated macrophages (TAMs) of the M2 phenotype are frequently associated with cancer progression. Invasive cancer cells undergoing epithelial-mesenchymal transition (EMT) have a selective advantage as TAM activators. Cyclin D1b is a highly oncogenic splice variant of cyclin D1. We previously reported that cyclin D1b enhances the invasiveness of breast cancer cells by inducing EMT. However, the role of cyclin D1b in inducing macrophage differentiation toward tumor-associated macrophage-like cells remains unknown. This study aimed to explore the relationship between breast cancer cells overexpressing cyclin D1b and TAMs. METHODS: Mouse breast cancer 4T1 cells were transfected with cyclin D1b variant and co-cultured with macrophage cells in a Transwell coculture system. The expression of characteristic cytokines in differentiated macrophages was detected using qRT-PCR, ELISA and zymography assay. Tumor-associated macrophage distribution in a transplanted tumor was detected by immunofluorescence staining. The proliferation and migration ability of breast cancer cells was detected using the cell counting kit-8 (CCK-8) assay, wound healing assay, Transwell invasion assay, and lung metastasis assay. Expression levels of mRNAs were detected by qRT-PCR. Protein expression levels were detected by Western blotting. The integrated analyses of The Cancer Genome Atlas (TCGA) datasets and bioinformatics methods were adopted to discover gene expression, gene coexpression, and overall survival in patients with breast cancer. RESULTS: After co-culture with breast cancer cells overexpressing cyclin D1b, RAW264.7 macrophages were differentiated into an M2 phenotype. Moreover, differentiated M2-like macrophages promoted the proliferation and migration of breast cancer cells in turn. Notably, these macrophages facilitated the migration of breast cancer cells in vivo. Further investigations indicated that differentiated M2-like macrophages induced EMT of breast cancer cells accompanied with upregulation of TGF-ß1 and integrin ß3 expression. CONCLUSION: Breast cancer cells transfected with cyclin D1b can induce the differentiation of macrophages into a tumor-associated macrophage-like phenotype, which promotes tumor metastasis in vitro and in vivo.


Asunto(s)
Neoplasias Pulmonares , Macrófagos Asociados a Tumores , Animales , Ratones , Macrófagos Asociados a Tumores/metabolismo , Macrófagos Asociados a Tumores/patología , Macrófagos/metabolismo , Neoplasias Pulmonares/metabolismo , Diferenciación Celular , Fenotipo
3.
Science ; 380(6651): 1252-1257, 2023 06 23.
Artículo en Inglés | MEDLINE | ID: mdl-37347869

RESUMEN

The hinge of bivalve shells can sustain hundreds of thousands of repeating opening-and-closing valve motions throughout their lifetime. We studied the hierarchical design of the mineralized tissue in the hinge of the bivalve Cristaria plicata, which endows the tissue with deformability and fatigue resistance and consequently underlies the repeating motion capability. This folding fan-shaped tissue consists of radially aligned, brittle aragonite nanowires embedded in a resilient matrix and can translate external radial loads to circumferential deformation. The hard-soft complex microstructure can suppress stress concentration within the tissue. Coherent nanotwin boundaries along the longitudinal direction of the nanowires increase their resistance to bending fracture. The unusual biomineral, which exploits the inherent properties of each component through multiscale structural design, provides insights into the evolution of antifatigue structural materials.


Asunto(s)
Materiales Biocompatibles , Bivalvos , Animales , Biomineralización
4.
Int J Antimicrob Agents ; 62(1): 106841, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-37160241

RESUMEN

In the current study, a population pharmacokinetic (PPK) model was developed for biapenem in patients with febrile neutropenia (FN) and haematological malignancies. Through Monte Carlo simulation, optimal administration regimens were suggested based on the developed PPK model. In a prospective, single-centre, open-label study, 174 plasma samples from 120 Chinese patients with FN and haematological malignancies were analysed by chromatography, and PK parameters were analysed by NONMEM. The drug clearance process was influenced by crucial covariates, namely creatinine clearance (CLCR) and concomitant posaconazole (POS). The ultimate PPK model was as follows: CL (L/h)=29.81 × (CLCR/121.38)0.806 × (1-POS × 0.297); volume of distribution (L)=114. For the target of ≥40% fT>minimum inhibitory concentration (MIC) (duration that the plasma level exceeds the MIC of the causative pathogen) and achieving the probability of target attainment ≥90%, the PK/pharmacodynamic breakpoint was 2 mg/L for the 2.4 g/day dosing regimen consisting of 600 mg q6h and 800 mg q8h. The breakpoint was 1 mg/L for the 1.2 g/day dosing regimen consisting of 300 mg q6h and 600 mg q12h. Empirical therapy would benefit from utilizing higher dosages and extended infusion durations. Therefore, it is suggested that patients with symptoms that are strongly suggestive of Pseudomonas aeruginosa or Acinetobacter baumannii infection may be suitable for combined treatment with other antibacterial drugs.


Asunto(s)
Infecciones por Acinetobacter , Neutropenia Febril , Neoplasias Hematológicas , Humanos , Método de Montecarlo , Estudios Prospectivos , Antibacterianos/farmacología , Infecciones por Acinetobacter/tratamiento farmacológico , Neutropenia Febril/tratamiento farmacológico , Neoplasias Hematológicas/complicaciones , Neoplasias Hematológicas/tratamiento farmacológico , Pruebas de Sensibilidad Microbiana
5.
Mol Med Rep ; 27(4)2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36896766

RESUMEN

Anemone flaccida Fr. Schmidt, a Traditional Chinese Medicine, has been used in the treatment of rheumatoid arthritis (RA) for numerous years. However, the specific mechanisms remain to be elucidated. Thus, the present study aimed to investigate the main chemical constituents and potential mechanisms of Anemone flaccida Fr. Schmidt. The ethanol extract obtained from Anemone flaccida Fr. Schmidt (EAF) was analyzed using mass spectrometry to determine the main components and the therapeutic effects of EAF on RA were verified using a collagen­induced arthritis (CIA) rat model. Results of the present study demonstrated that synovial hyperplasia and pannus of the model rats were significantly improved following EAF treatment. Moreover, the protein expression levels of VEGF and CD31­labeled neovascularization were significantly reduced in the synovium of CIA rats following treatment with EAF, compared with those of the untreated model group. Subsequently, in vitro experiments were carried out to verify the impact of EAF on synovial proliferation and angiogenesis. Results of the western blot analysis revealed that EAF inhibited the PI3K signaling pathway in endothelial cells, which is associated with anti­angiogenesis. In conclusion, results of the present study demonstrated the therapeutic effects of Anemone flaccida Fr. Schmidt on RA and preliminarily revealed the mechanisms of this drug in the treatment of RA.


Asunto(s)
Anemone , Artritis Experimental , Artritis Reumatoide , Animales , Ratas , Anemone/química , Artritis Experimental/tratamiento farmacológico , Artritis Experimental/patología , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/patología , Células Endoteliales , Etanol/farmacología , Hiperplasia/tratamiento farmacológico , Hiperplasia/patología , Fosfatidilinositol 3-Quinasas , Membrana Sinovial/patología , Extractos Vegetales/farmacología
6.
Heliyon ; 9(3): e14349, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36925544

RESUMEN

Repair of osteochondral defects and regeneration of cartilage is a major challenge. In this work, the mesenchymal stem cells (MSCs)-laden hydrogel was designed using silk fibroin (SF) and gelatin methacrylate (GelMA), to encapsulate platelet-rich plasma (PRP). Initially, GelMA was synthesized, and SF was prepared using silkworm cocoon, then MSCs-laden SF/GelMA (SG) hydrogel was fabricated. The physicochemical properties of the hydrogels were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscope, and rheometry. After hydrogel preparation, the viability of MSCs in the hydrogels was investigated via CCK-8 analysis and fluorescent images. The MSCs-laden SG hydrogel containing PRP was subsequently injected into the cartilage defect area in Sprague Dawley rats. Hematoxylin and eosin (H&E), Masson staining, and Mankin scores evaluation confirmed the new cartilage formation in 8 weeks. The results presented in the study, therefore, showed that the prepared MSCs-laden SG hydrogel loaded with PRP has the potential for cartilage reconstruction, which is crucial to the treatment of knee osteoarthritis.

7.
Stem Cells Int ; 2023: 3827999, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36818162

RESUMEN

Background: Pyroptosis is closely related to the programmed death of cancer cells as well as the tumor immune microenvironment (TIME) via the host-tumor crosstalk. However, the role of pyroptosis-related genes as prognosis and TIME-related biomarkers in skin cutaneous melanoma (SKCM) patients remains unknown. Methods: We evaluated the expression profiles, copy number variations, and somatic mutations (CNVs) of 27 genes obtained from MSigDB database regulating pyroptosis among TCGA-SKCM patients. Thereafter, we conducted single-sample gene set enrichment analysis (ssGSEA) for evaluating pyroptosis-associated expression patterns among cases and for exploring the associations with clinicopathological factors and prognostic outcome. In addition, a prognostic pyroptosis-related signature (PPRS) model was constructed by performing Cox regression, weighted gene coexpression network analysis (WGCNA), and least absolute shrinkage and selection operator (LASSO) analysis to score SKCM patients. On the other hand, we plotted the ROC and survival curves for model evaluation and verified the robustness of the model through external test sets (GSE22153, GSE54467, and GSE65904). Meanwhile, we examined the relations of clinical characteristics, oncogene mutations, biological processes (BPs), tumor stemness, immune infiltration degrees, immune checkpoints (ICs), and treatment response with PPRS via multiple methods, including immunophenoscore (IPS) analysis, gene set variation analysis (GSVA), ESTIMATE, and CIBERSORT. Finally, we constructed a nomogram incorporating PPRS and clinical characteristics to improve risk evaluation of SKCM. Results: Many pyroptosis-regulated genes showed abnormal expression within SKCM. TP53, TP63, IL1B, IL18, IRF2, CASP5, CHMP4C, CHMP7, CASP1, and GSDME were detected with somatic mutations, among which, a majority displayed CNVs at high frequencies. Pyroptosis-associated profiles established based on pyroptosis-regulated genes showed markedly negative relation to low stage and superior prognostic outcome. Blue module was found to be highly positively correlated with pyroptosis. Later, this study established PPRS based on the expression of 8 PAGs (namely, GBP2, HPDL, FCGR2A, IFITM1, HAPLN3, CCL8, TRIM34, and GRIPAP1), which was highly associated with OS, oncogene mutations, tumor stemness, immune infiltration degrees, IC levels, treatment responses, and multiple biological processes (including cell cycle and immunoinflammatory response) in training and test set samples. Conclusions: Based on our observations, analyzing modification patterns associated with pyroptosis among diverse cancer samples via PPRS is important, which can provide more insights into TIME infiltration features and facilitate immunotherapeutic development as well as prognosis prediction.

8.
Oncol Lett ; 24(2): 275, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35782905

RESUMEN

Cisplatin (DDP) is a potent and widely applied chemotherapeutic agent. However, its clinical efficacy for the treatment of liver cancer is limited by adverse effects and the development of resistance. Combinatorial therapy may alleviate these issues. Dihydroartemisinin (DHA) is a first-generation derivative of artemisinin. The effects of DDP on liver cancer when applied in combination with DHA have not previously been studied. Therefore, the present study aimed to investigate the effects of DHA combined with DDP on HepG2 cells and their potential underlying molecular mechanisms. HepG2 cells were treated with different concentrations of DHA and/or DDP. Cell Counting Kit-8 assay was used to assess the cell viability. Cell proliferation and apoptosis were quantified using flow cytometry, acridine orange/ethidium bromide (AO/EB) fluorescent dual staining and the colony formation assay. Cell migration was quantified using the Transwell and wound healing assays. The HepG2 cell protein expression levels of Fas, Fas-associated death domain (FADD), procaspase-3, cleaved caspase-3, pro-caspase-8, cleaved caspase-8, Bax, Bcl-2, E-cadherin and N-cadherin, were detected via western blotting. Gelatin zymography was used to assess the levels of MMP-9 secreted by HepG2 cells into the supernatant. Following combined DHA and DDP treatment, the percentage of apoptotic cells was significantly increased, whereas cell proliferation and migration were significantly reduced, compared with cells treated with DDP only. DHA and DPP in combination significantly inhibited the expression of MMP-9, significantly increased the protein expression levels of Fas, FADD, Bax and E-cadherin, significantly increased the ratio of cleaved caspase-3 and cleaved caspase-8 to their precursor proteins and significantly decreased the protein expression levels of Bcl-2 and N-cadherin. The findings of the present study suggested that, DHA may confer synergistic effects with DDP in potentially promoting apoptosis and inhibiting the epithelial-mesenchymal transition for the treatment of liver cancer.

9.
Langmuir ; 38(26): 8135-8152, 2022 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-35731695

RESUMEN

A modified many-body dissipative particle dynamics (mDPD) model is rigorously calibrated to achieve realistic fluid-fluid/solid interphase properties and applied for mesoscale flow simulations to elucidate the transport mechanisms of heptane liquid and water, respectively, through pore networks formed by packed silica nanoparticles with a uniform diameter of 30 nm. Two million CPU core hours were used to complete the simulation studies. Results show reduction of permeability by 54-64% in heptane flow and by 88-91% in water flow, respectively, compared to the Kozeny-Carman equation. In these nanopores, a large portion of the fluids are in the near-wall regions and thus not mobile due to the confinement effect, resulting in reduced hydraulic conductivity. Moreover, intense oscillations in the calculated flow velocities also indicate the confinement effect that contests the external driven force to flow. The generic form of Darcy's law is considered valid for flow through homogeneous nanopore networks, while permeability depends collectively on pore size and surface wettability. This fluid-permeability dependency is unique to flow in nanopores. In addition, potential dependence of permeability on pore connectivity is observed when the porosity remains the same in different core specimens.

10.
Materials (Basel) ; 15(3)2022 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-35160949

RESUMEN

Liquid-vapor molecular dynamics (LVMD) simulations are performed to reinvestigate the phase transition and solvation force oscillation behavior of a simple argon liquid film confined between two solid surfaces. Our simulations present a novel scenario in which the n → n - 1 layering transitions are accompanied by the formation, climb, and annihilation of Frank partial dislocations during the squeeze-out process under compression. This is indicated by the splitting of the repulsive peaks in the solvation force profile. The detailed analysis reveals that the formation-climb-annihilation mechanism of Frank dislocation occurs during approach and disappears during receding, which would result in force hysteresis. In combination with our recent works, this study provides new insights into the physical property of nanoconfined lubricant films in boundary lubrication.

11.
Langmuir ; 36(26): 7277-7288, 2020 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-32525322

RESUMEN

The phase behavior of hydrocarbon fluids confined in porous media has been reported to deviate significantly from that in the bulk environment due to the existence of sub-10 nm pores. Though experiments and simulations have measured the bubble/dew points and sorption isotherms of hydrocarbons confined in both natural and synthetic nanopores, the confinement effects in terms of the strength of fluid-pore interactions tuned by surface wettability and chemistry have received comparably less discussion. More importantly, the underlying physics of confinement-induced phenomena remain obfuscated. In this work, we studied the phase behavior and capillary condensation of n-hexane to understand the effects of confinement at the molecular level. To systematically investigate the pore effects, we constructed two types of wall confinements; one is a structureless virtual wall described by the Steele potential and the other one is an all-atom amorphous silica structure with surface modified by hydroxyl groups. Our numerical results demonstrated the importance of fluid-pore interaction, pore size, and pore morphology effects in mediating the pressure-volume-temperature (PVT) properties of hydrocarbons. The most remarkable finding of this work was that the saturation pressure predicted from the van der Waals-type adsorption isothermal loop could be elevated or suppressed relative to the bulk phase, as illustrated in the graphical abstract. As the surface energy (i.e., fluid-pore interaction) decreased, the isothermal vapor pressure increased, indicating a greater preference for the fluid to exist in the vapor state. Sufficient reduction of the fluid-pore interactions could even elevate the vapor pressure above that of the bulk fluid.

12.
Chinese Pharmacological Bulletin ; (12): 1713-1717, 2017.
Artículo en Chino | WPRIM (Pacífico Occidental) | ID: wpr-667971

RESUMEN

Aim To evaluate the correlation between in vitro release and in vivo absorption of azithromycin cat-ionic micron niosomes (ACMNS)by Wagner-Nelson method and deconvolution method. Methods The in vitro release behavior of ACMNS was studied by dy-namic membrane dialysis. After a single dose of intra-gastric administration with ACMNS and AM in rats,the AM concentrations in plasma were determined by high performance liquid chromatography(HPLC). Wagner-Nelson and deconvolution method were used to reveal the in vitro / in vivo correlation. Results X used as cu-mulative in vitro release and Fa as the absorption per-centage,the regression equation was established:F a =3. 0524X - 5. 7709,r = 0. 8976,and X used as cumu-lative in vitro release and R as input function,the re-gression equation was established:R = 2. 3413X -58. 687,r = 0. 5217. r < r( 2,0. 05) = 0. 9500 (P <0. 05). Conclusion There is no correlation between in vitro release and in vivo absorption of ACMNS.

13.
Langmuir ; 32(44): 11366-11374, 2016 11 08.
Artículo en Inglés | MEDLINE | ID: mdl-27741570

RESUMEN

The effect of layer charge on the intercalation of supercritical carbon dioxide (scCO2)-H2O mixture in Na-montmorillonite clay interlayers under T = 323 K and P = 90 bar geologic sequestration conditions has been further investigated. This effect includes the charge amount and its location (within either octahedral or tetrahedral layers due to isomorphic substitutions). Two clay models with different layer charges are used in this study. Simulation results show that the increase of charge amount shifts the monolayer-to-bilayer (1W-to-2W) hydration transition toward the lower relative humidity (RH), increasing water sorption at the expense of reducing the overall sorption amount of CO2 in the clay interlayer. However, the combination of the influence of charge amount and charge location leads to insignificant changes in equilibrium basal spacings of the high- and low-charge clays. Molecular dynamics simulations show that the CO2 dimers, which are frequently seen in low-charge clay interlayers, vanish in high-charge clay interlayers even at low RH of 30%.

14.
J Microbiol Biotechnol ; 25(5): 620-8, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25394604

RESUMEN

A fungal strain, R9, was isolated from the South Atlantic sediment sample and identified as Aspergillus fumigatus. An antifungal protein, AfAFPR9, was purified from the culture supernatant of Aspergillus fumigatus R9. AfAFPR9 was identified to be restrictocin, which is a member of the ribosome-inactivating proteins (RIPs), by MALDI-TOF-TOF-MS. AfAFPR9 displayed antifungal activity against plant pathogenic Fusarium oxysporum, Alternaria longipes, Colletotrichum gloeosporioides, Paecilomyces variotii, and Trichoderma viride at minimum inhibitory concentrations of 0.6, 0.6, 1.2, 1.2, and 2.4 µg/disc, respectively. Moreover, AfAFPR9 exhibited a certain extent of thermostability, and metal ion and denaturant tolerance. The iodoacetamide assay showed that the disulfide bridge in AfAFPR9 was indispensable for its antifungal action. The cDNA encoding for AfAFPR9 was cloned from A. fumigatus R9 by RTPCR and heterologously expressed in E. coli. The recombinant AfAFPR9 protein exhibited obvious antifungal activity against C. gloeosporioides, T. viride, and A. longipes. These results reveal the antifungal properties of a RIP member (AfAFPR9) from marine-derived Aspergillus fumigatus and indicated its potential application in controlling plant pathogenic fungi.


Asunto(s)
Antifúngicos/química , Aspergillus fumigatus/genética , Proteínas Fúngicas/química , Sedimentos Geológicos/microbiología , Proteínas Recombinantes/química , Proteínas Inactivadoras de Ribosomas/química , Secuencia de Aminoácidos , Antifúngicos/metabolismo , Antifúngicos/farmacología , Aspergillus fumigatus/química , Aspergillus fumigatus/metabolismo , Océano Atlántico , Secuencia de Bases , Disulfuros , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/farmacología , Hongos/efectos de los fármacos , Viabilidad Microbiana/efectos de los fármacos , Datos de Secuencia Molecular , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacología , Proteínas Inactivadoras de Ribosomas/genética , Proteínas Inactivadoras de Ribosomas/metabolismo , Proteínas Inactivadoras de Ribosomas/farmacología
15.
J Phys Chem B ; 118(37): 10956-65, 2014 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-25167085

RESUMEN

The grand-canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations are performed to investigate the methane aqueous fluids in Na-montmorillonite clay interlayer under near-surface geological temperature and pressure conditions (T = 300 K and P = 20-50 bar). The chemical potentials of water and methane under these T/P conditions are calculated using the Widom's insertion method. These chemical potentials are used in the GCMC simulations to determine the contents of different species in the clay interlayer, especially in those that correspond to the equilibrium stable spacing distances. Simulation results show that initial clay swelling is dominated by water adsorption into the clay interlayer, followed by the intercalation of methane as the basal spacing increases. However, it is found that this methane intercalation process is strongly influenced by the relative humidity and the total gas pressure of the system. High relative humidity may facilitate water molecules entering the clay interlayer region and inhibit the intercalation of methane molecules. MD simulations show that sodium ions are fully hydrated by water molecules and clay surface oxygen atoms, while methane molecules are not fully coordinated. This situation is attributed to the less water content in clay interlayer and the subsequent formation of methane dimer or trimer clusters due to the hydrophobic nature of small hydrocarbon molecules.

16.
J Chem Phys ; 139(7): 074704, 2013 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-23968104

RESUMEN

Grand canonical Monte Carlo (GCMC) and liquid-vapor molecular dynamics (LVMD) simulations are performed to investigate the squeezing and phase transition of a simple liquid argon film confined between two solid surfaces. Simulation results show that the LVMD simulation is capable of capturing the major thermodynamic equilibrium states of the confined film, as predicted by the GCMC simulations. Moreover, the LVMD simulations reveal the non-equilibrium squeeze out dynamics of the confined film. The study shows that the solvation force hysteresis, observed in many surface force experiments, is attributed to two major effects. The first is related to the unstable jumps during the laying transitions of the confined film, in which the gradient of force profile is larger than the driving spring constant. The second effect is related to the squeeze out dynamics of the confined film even though the first effect is absent. In general, these two dynamic processes are non-equilibrium in nature and involve significant energy dissipations, resulting in the force hysteresis.

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