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1.
Life Sci ; 327: 121698, 2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37080351

RESUMEN

Cholangiocarcinoma (CCA) with a high malignancy is usually diagnosed as advanced and is prone to metastasis and leads to a poor prognosis. It is reported that cordycepin has anti-tumor effect. However, the molecular targets and mechanisms of cordycepin in inhibiting CCA metastasis remains unclear. In order to evaluate the therapeutic effect of cordycepin on CCA metastasis, experiments were conducted in vivo and in vitro. The results showed that cordycepin inhibited the migration and EMT progression of HuCCT1 and QBC939 cells. Cordycepin has a strong hypolipidemic effects, therefore, we examined its effect on lipid metabolism in CCA. Cordycepin inhibits SREBP1 mediated fatty acid synthesis through the AKT/mTOR signaling pathway. Meanwhile, cordycepin can reduce ERO1A expression in HuCCT1 and QBC939 cells. ERO1A plays a role in malignant tumors. ERO1A promotes migration and lipid metabolism of CCA cells through AKT/mTOR signaling pathway. In addition, cordycepin significantly inhibited the tumor metastasis and the serum levels of TG and T-CHO in mice. Taken together, we demonstrate that cordycepin mediated ERO1A/mTOR/SREBP1 axis inhibits lipid metabolism and metastasis in CCA cells in vitro and in vivo. These data suggest that cordycepin can be used as a novel drug for the clinical treatment of CCA and to improve the prognosis.


Asunto(s)
Neoplasias de los Conductos Biliares , Colangiocarcinoma , Animales , Ratones , Neoplasias de los Conductos Biliares/patología , Conductos Biliares Intrahepáticos/metabolismo , Línea Celular Tumoral , Movimiento Celular , Proliferación Celular , Colangiocarcinoma/metabolismo , Metabolismo de los Lípidos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Humanos , Transición Epitelial-Mesenquimal
2.
J Cell Biochem ; 124(1): 3-16, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36334309

RESUMEN

The hallmark feature of metabolic reprogramming is now considered to be widespread in many malignancies, including colorectal cancer (CRC). Of the gastrointestinal tumors, CRC is one of the most common with a high metastasis rate and long insidious period. The incidence and mortality of CRC has increased in recent years. Metabolic reprogramming also has a significant role in the development and progression of CRC, especially lipid metabolic reprogramming. Many studies have reported that lipid metabolism reprogramming is similar to the Warburg effect with typical features affecting tumor biology including proliferation, migration, local invasion, apoptosis, and other biological behaviors of cancer cells. Therefore, studying the role of lipid metabolism in the occurrence and development of CRC will increase our understanding of its pathogenesis, invasion, metastasis, and other processes and provide new directions for the treatment of CRC. In this paper, we mainly describe the molecular mechanism of lipid metabolism reprogramming and its important role in the occurrence and development of CRC. In addition, to provide reference for subsequent research and clinical diagnosis and treatment we also review the treatments of CRC that target lipid metabolism.


Asunto(s)
Neoplasias Colorrectales , Metabolismo de los Lípidos , Humanos , Neoplasias Colorrectales/metabolismo , Proliferación Celular , Movimiento Celular , Apoptosis
3.
Cells Dev ; 172: 203814, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36307062

RESUMEN

This study mainly analyzed the relationship between nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor-ß (TGFß1)/Smad under high glucose environment and its influence on wound healing. Fibroblast NIH-3T3 was used to analyze the effect of high concentration glucose (20 nmol/mL) on cell viability, migration ability, inflammation level and NF-κB pathway. Pyrrolidinedithiocarbamate (PDTC) was used to inhibit NF-κB for rescue experiments. Diabetic mice were used to construct wound healing models. Recombinant TGF-ß1 was used to promote wound healing in diabetic mice. FSL-1 was applied to activate NF-κB to verify the mechanism. High glucose inhibited cell viability and migration ability, promoted the expression of TNF-α, IL-6 and IL-1ß, induced the activation of NF-κB pathway in fibroblasts. Inhibition of NF-κB not only blocked the decrease in cell viability and migration ability induced by high glucose, but also relieved the release of inflammatory factors. TGF-ß1 activated the TGF-ß1/Smad pathway and promoted wound healing in diabetic mice. Activating the NF-κB pathway not only inhibited the activation of the TGF-ß1/Smad pathway, but also alleviated the promoting effect of TGF-ß1 on wound healing. In a high glucose environment, the activation of NF-κB may inhibit the function of fibroblasts by inhibiting the TGF-ß1/Smad pathway, resulting in poor wound healing.


Asunto(s)
Diabetes Mellitus Experimental , FN-kappa B , Animales , Ratones , Glucosa/farmacología , Inflamación/metabolismo , FN-kappa B/metabolismo , Transducción de Señal , Factor de Crecimiento Transformador beta1/metabolismo , Cicatrización de Heridas , Proteínas Smad
4.
Comput Intell Neurosci ; 2022: 1447129, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36093506

RESUMEN

Objective: To compare the effect of three different surgical methods on rabbit Achilles tendon rupture. Methods: The Achilles tendon transection model was constructed by cutting off the inner half of the Achilles tendon. Rabbits were divided into 4 groups: model group, open surgery (OS) group, minimally invasive surgery (MS) group, and conservative treatment (CT) group. Biomechanical evaluation, H&E, and Picrosirius Red staining were applied to evaluate the histological changes and healing. RT-qPCR, Western blot, ELISA, and IHC staining were used to detect the expression of COLIII, IL-1ß, TNF-α, IL-6, CD31, VEGF, bFGF, and TGF-ß1. Results: Different surgery treatments significantly alleviated the histological changes in rabbits. The tension and elasticity of the Achilles tendon were significantly increased after surgery. In addition, surgery treatments notably alleviated the inflammatory responses in vivo via downregulation of IL-1ß, TNF-α, and IL-6 and promoted the tube formation in tissues through upregulating VEGF, bFGF, TGF-ß1, and CD31. Furthermore, MS exhibited best therapeutic efficiency on Achilles tendon rupture healing, compared with OS or CT. Conclusions: Our research revealed the superiority of MS in Achilles tendon rupture treatment at the molecular level compared with OS or CT.


Asunto(s)
Tendón Calcáneo , Traumatismos de los Tendones , Tendón Calcáneo/metabolismo , Tendón Calcáneo/cirugía , Animales , Interleucina-6/metabolismo , Procedimientos Quirúrgicos Mínimamente Invasivos , Conejos , Traumatismos de los Tendones/metabolismo , Traumatismos de los Tendones/cirugía , Factor de Crecimiento Transformador beta1/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo
5.
Comput Math Methods Med ; 2022: 6481846, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35836925

RESUMEN

Objective: To explore the effect of microRNA (miR)-192-5p on the inflammatory and fibrotic responses of tendon cells. Methods: Tendon cells were treated with transforming growth factor-ß1 (TGF-ß1). The expression of miR-192-5p and nuclear factor of activated T cells 5 (NFAT5) in tendon cells were detected by RT-qPCR. The expressions of inflammatory and fibrosis-related factors were detected by RT-qPCR and Western blot. MiR-192-5p binds to NFAT5 targeting by TargetScan and dual-luciferase reporter gene assay. The expression of the NFAT5 gene was detected by RT-qPCR and Western blot. Detection of apoptosis in tendon cells by flow cytometry. Results: MiR-192-5p was downregulated in tendon cells, and the expression level gradually decreased with the prolong of TGF-ß1 treatment. The expression of NFAT5 increased with the treatment time of TGF-ß1. The expression of miR-192-5p decreased collagen III (COLIII), α smooth muscle actin (α-SMA), matrix metalloproteinase- (MMP-) 1, and MMP-8 expression, thereby inhibiting TGF-ß1-induced fibrosis in tendon cells. The expression of miR-192-5p decreased the expression of tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1ß, thereby alleviating TGF-ß1-induced inflammatory response and reduce apoptosis in tendon cells. NFAT5 is a direct target of miR-192-5p in tendon cells. The upregulation of NFAT5 reversed the effect of miR-192-5p on the fibrotic activity and inflammatory response of TGF-ß1-stimulated tendon cells. Conclusions: MiR-192-5p alleviates fibrosis and inflammatory responses of tendon cells by targeting NFAT5.


Asunto(s)
MicroARNs , Factor de Crecimiento Transformador beta1 , Apoptosis/genética , Fibrosis , Humanos , MicroARNs/genética , MicroARNs/metabolismo , Tendones/metabolismo , Factores de Transcripción/genética , Factor de Crecimiento Transformador beta1/genética , Factor de Crecimiento Transformador beta1/metabolismo , Factor de Crecimiento Transformador beta1/farmacología
6.
Chin Med ; 17(1): 69, 2022 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-35698073

RESUMEN

BACKGROUND: Cholangiocarcinoma (CCA) is a rare biliary adenocarcinoma related to poor clinical prognosis. Crowberry is an herbal medicine used to control inflammatory diseases and reestablish antioxidant enzyme activity. Although crowberry shows significant therapeutic efficacy in various tumors and diseases, its anticancer effects and specific molecular mechanisms in CCA are poorly understood. AIM OF THE STUDY: This study was conducted to characterize crowberry effects on CCA cells behavior. MATERIALS AND METHODS: The chemical profiles of crowberry extract was qualitatively analyzed by high-performance liquid chromatography (HPLC) and HPLC-tandem mass spectrometry. MTT, colony formation and EdU assays were performed to measure cell proliferation. The effect of crowberry treatment on CCA cell migration was assessed by wound healing and migration assays. Moreover, Hoechst staining assay and flow cytometry were performed to assess the cell apoptosis rate. Western blotting was used to assess the protein expression levels of key factors associated with apoptosis, the Akt signaling pathway, and the epithelial-mesenchymal transition. A xenograft model was established and immunohistochemical and H&E staining was performed to assess crowberry antitumor effects in vivo. RESULTS: Crowberry clearly inhibited CCA cells proliferation and migration in a dose-dependent manner and induced apoptosis in vitro. Crowberry inactivated the PI3K/Akt signaling pathway by regulating DEK in vitro and significantly inhibited tumor growth by downregulating the DEK expression in xenograft models. CONCLUSION: Crowberry inhibits CCA cells proliferation and migration through a molecular mechanism that includes inhibition of DEK and Akt signaling pathway inhibition in vitro and in vivo.

7.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi ; 38(6): 513-521, 2022 Jun.
Artículo en Chino | MEDLINE | ID: mdl-35732609

RESUMEN

Objective To explore the inhibitory effect of cordycepin on the proliferation and migration of gastric cancer cells and its molecular mechanism. Methods MGC-803 cells were treated with 0, 25, 50, 100 µmol/L of cordycepin and HGC-27 cells with 0, 5, 25, 50 µmol/L of cordycepin for 48 hours. The proliferation ability of MGC-803 and HGC-27 cells was detected by MTT assay and EdU assay; the colony formation ability of cells was detected by colony formation assay; both wound healing assay and cell migration assay were applied to detect the cell migration ability of MGC-803 and HGC-27 cells; the chromatin agglutination was detected by Hoechst 33342 staining; the apoptosis of gastric cancer cells was detected by annexin V-FITC/PI double labeling combined with flow cytometry; Western blot was used to measure the protein expression levels of lipid metabolism-related proteins including sterol regulatory element binding transcription factor 1 (SREBF1), fatty acid synthase (FASN), and acetyl coA carboxylase 1 (ACC1), epithelial-mesenchymal transition (EMT)-related proteins including E-cadherin, vimentin, Snail, Slug, matrix metalloproteinase 2 (MMP2), MMP9, AMPK, and phosphorylated AMPK (p-AMPK), MAPK signaling pathway-related proteins including JNK, phosphorylated JNK (p-JNK), p38 MAPK, and p-p38 MAPK, and apoptosis-related proteins including cleaved caspase-9 (c-caspase-9), c-caspase-3, and cleaved poly (ADP-ribose) polymerase (c-PARP). Results Cordycepin significantly inhibited the proliferation, colony formation, and migration of gastric cancer cells. After cordycepin treatment, the karyopycnosis, karyorrhexis, and apoptosis rate of cancer cells increased, and the expressions of apoptosis-related proteins c-caspase-3, c-caspase-9, and c-PARP increased. The expression of E-cadherin increased, while the expressions of vimentin, Snail, Slug, SREBF1, FASN, ACC1, MMP2, MMP9 significantly decreased; the phosphorylation levels of AMPK, JNK and P38 proteins significantly increased. Conclusion Cordycepin inhibits the proliferation and migration of gastric cancer cells by suppressing the lipid metabolism and EMT process via activating AMPK and MAPK signaling pathway.


Asunto(s)
Desoxiadenosinas , Neoplasias Gástricas , Proteínas Quinasas Activadas por AMP/metabolismo , Apoptosis , Cadherinas/metabolismo , Caspasa 3/metabolismo , Caspasa 9/metabolismo , Línea Celular Tumoral , Proliferación Celular , Desoxiadenosinas/farmacología , Humanos , Metabolismo de los Lípidos , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Inhibidores de Poli(ADP-Ribosa) Polimerasas/farmacología , Inhibidores de Poli(ADP-Ribosa) Polimerasas/uso terapéutico , Neoplasias Gástricas/tratamiento farmacológico , Neoplasias Gástricas/metabolismo , Vimentina/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo
8.
Rev Sci Instrum ; 92(10): 105110, 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34717404

RESUMEN

Natural gas hydrate (NGH) will become a significant potential energy source in the post-oil era due to its large reserves, wide distribution, high energy density, and low pollution. Sand production is one of the main problems that cause the impossible long-term production of NGH. This paper presents an experimental apparatus that was developed to synthesize NGH and hydrate-bearing sediments and was applied to analyze the sand production and sand control mechanism during hydrate exploitation. The sand production and sand control tests of NGH can be conducted over a temperature range varying from 253.15 to 323.15 K and the maximum chamber pressure and overlying pressure up to 30 MPa. This apparatus is mainly composed of the simulated sand production system, the temperature and pressure control system, and the measurement control system. The simulated sand production system consists of a movable overlying pressure loader, a strain sensor, a simulated reservoir chamber, a sand control system, and a sand production monitoring system. A visual gas-liquid-solid separation tank is applied to observe the gas, water, and sand production. The basic principles of this apparatus are discussed, and a series of experiments were performed to verify that sand production and sand control can be practically applied in the exploitation of NGH reservoirs.

9.
Pharmacol Res Perspect ; 9(3): e00791, 2021 05.
Artículo en Inglés | MEDLINE | ID: mdl-34038621

RESUMEN

The pathogenesis of steroid-induced avascular necrosis of femoral head (SANFH) is complex, and there is a lack of effective early prevention method. The aim of the present study was to evaluate the effect of dexamethasone (DEX) on the biological behavior of bone marrow mesenchymal stem cells (BMSCs) and to explore the possibility of DEX in the clinical treatment of SANFH. The effect of DEX on the proliferation of BMSCs was evaluated by Counting Kit-8 assay, western blot assay, and enzyme-linked immunosorbent assay. Flow cytometry and western blot assay were performed to detect the effect of DEX on the apoptosis of BMSCs. Quantitative real-time PCR and western blot assay were performed to detect the effect of DEX on the expression of endoplasmic reticulum stress (ERS)-related genes. Immunoblotting analysis was conducted for detecting the nuclear-cytoplasmic distribution of Nrf2. DEX could significantly inhibit the proliferation of BMSCs and promote apoptosis of BMSCs. DEX could increase the expression of PERK, ATF6, and IRE1a, and induce nuclear translocation of Nrf2. The addition of ML385 could reverse the effect of DEX on BMSCs. DEX could activate the PERK-Nrf2 pathway to promote ERS and finally affect the cell proliferation and apoptosis of BMSCs.


Asunto(s)
Dexametasona/farmacología , Estrés del Retículo Endoplásmico/efectos de los fármacos , Glucocorticoides/farmacología , Células Madre Mesenquimatosas/efectos de los fármacos , Factor 2 Relacionado con NF-E2/metabolismo , eIF-2 Quinasa/metabolismo , Factor de Transcripción Activador 6/genética , Factor de Transcripción Activador 6/metabolismo , Apoptosis/efectos de los fármacos , Proteínas Reguladoras de la Apoptosis/metabolismo , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Endorribonucleasas/genética , Endorribonucleasas/metabolismo , Humanos , Células Madre Mesenquimatosas/metabolismo , Factor 2 Relacionado con NF-E2/genética , Proteínas de Neoplasias/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , eIF-2 Quinasa/genética
10.
Open Life Sci ; 16(1): 408-418, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33981848

RESUMEN

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and stands among the leading causes of cancer-related deaths. Although deregulation of the microbiota in the gastrointestinal tract has been frequently described in CRC, very little is known about the precise molecular mechanisms by which bacteria and their toxins modulate the process of tumorigenesis and behavior of cancer cells. In this study, we produced recombinant Bacteroides fragilis enterotoxin-1 (rBFT1) and demonstrate that rBFT1 could promote cell proliferation in colorectal cancer cells and accelerate tumor growth in vivo. To identify the mechanisms, we further investigated CCL3/CCR5 and NF-κB pathway. We found that CCL3, CCR5, NF-κB, and TRAF-6 were dramatically upregulated after rBFT1 treatment, thus suggesting that the role of rBFT1 in CRC progression may be associated with CCL3/CCR5 and NF-κB pathways. Collectively, our results indicate that rBFT1 serves as a tumor promoter and plays a crucial role in inducing the proliferation of CRC via accelerating CCL3-related molecular pathway, thus giving insights into mechanistic underpinnings for the prevention and treatment of CRC.

11.
Sci Rep ; 11(1): 9197, 2021 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-33911113

RESUMEN

To reveal the kinetic performance of gas molecules in hydrate growth, hydrate formation from pure CO2, flue gas, and biogas was measured using in-situ Raman and macroscopic methods at 271.6 K. In the in-situ Raman measurements, Raman peaks of gases in the hydrate phase were characterised and normalised by taking the water bands from 2800 to 3800 cm-1 as a reference, whose line shapes were not found to have a noticeable change in the conversion from Ih ice to sI hydrate. The hydrate growth was suggested to start with the formation of unsaturated hydrate nuclei followed by gas adsorption. In hydrate formed from all tested gases, CO2 concentrations in hydrate nuclei were found to be 23-33% of the saturation state. In the flue gas system, the N2 concentration reached a saturation state once hydrate nuclei formed. In the biogas system, competitive adsorption of CH4 and CO2 molecules was observed, while N2 molecules hardly evolved in hydrate formation. Combined with micro- and macroscopic analysis, small molecules such as N2 and CO2 were suggested to be more active in the formation of hydrate nuclei, and the preferential adsorption of CO2 molecules took place in the subsequent gas adsorption process.

12.
Nanomaterials (Basel) ; 11(3)2021 Feb 26.
Artículo en Inglés | MEDLINE | ID: mdl-33652869

RESUMEN

The large amounts of natural gas in a dense solid phase stored in the confined environment of porous materials have become a new, potential method for storing and transporting natural gas. However, there is no experimental evidence to accurately determine the phase state of water during nanoscale gas hydrate dissociation. The results on the dissociation behavior of methane hydrates confined in a nanosilica gel and the contained water phase state during hydrate dissociation at temperatures below the ice point and under atmospheric pressure are presented. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) were used to trace the dissociation of confined methane hydrate synthesized from pore water confined inside the nanosilica gel. The characterization of the confined methane hydrate was also analyzed by PXRD. It was found that the confined methane hydrates dissociated into ultra viscous low-density liquid water (LDL) and methane gas. The results showed that the mechanism of confined methane hydrate dissociation at temperatures below the ice point depended on the phase state of water during hydrate dissociation.

13.
RSC Adv ; 11(50): 31583-31589, 2021 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-35496851

RESUMEN

Carbon dioxide hydrate has been intensively investigated in recent years because of its potential use as gas and heat storage materials. To understand the hydrate formation mechanisms, the crystallization of CO2 hydrate from NaCl solutions was simulated at a molecular level. The influence of temperature, pressure, salt concentration and CO2 concentration on CO2 hydrate formation was evaluated. Results showed that the amount of the newly formed hydrate cages pressure went through a fast linear growth period followed by a relatively stable period. Pressure had little effect on CO2 hydrate formation and temperature had a significant influence. The linear growth rate was greatly reduced as the temperature dropped from 255 to 235 K. The salt ion pairs could inhibit CO2 hydrate formation, suggesting that we should choose the lower salinity areas if we want to storage CO2 as gas hydrates in the seabed sediments. The observations in this study can provide theoretical support for the micro mechanism of hydrate formation, and provide a theoretical reference for the technology of hydrate based CO2 storage.

14.
Immunol Invest ; 50(4): 338-355, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-32397769

RESUMEN

Background: The role of T cell Ig and ITIM domain (TIGIT) and programmed cell death-1 (PD-1) in colorectal cancer (CRC) with mismatch repair deficiency is unknown.Methods: This was a study of 60 CRC patients with mismatch repair deficiency and 30 healthy controls between June 2015 and October 2015.Results: The expression of Foxp3, PD-1, and TIGIT was higher in cancer tissues compared with adjacent mucosa (all P < .05). Patients with advanced TNM stage had a significantly higher expression of TIGIT (P = .025) and PD-1 (P = .020) than patients with early-stage CRC. The disease-free survival (DFS) of patients with high TIGIT (HR = 3.96, 95%CI: 1.34-11.69, P = .013) or PD-1 (HR = 214.8, 95%CI: 49.88-925.2, P < .001) expression were better. The overall survival (OS) of the patients with CRC and high expression of PD-1 was worse than those with low expression (HR = 4.01, 95%CI:1.26-12.69, P = .019).Conclusion: TIGIT and PD-1 are upregulated in CRC with mismatch repair deficiency and associated with TNM stage and DFS.


Asunto(s)
Neoplasias Encefálicas/inmunología , Neoplasias Colorrectales/inmunología , Síndromes Neoplásicos Hereditarios/inmunología , Receptor de Muerte Celular Programada 1/inmunología , Receptores Inmunológicos/inmunología , Neoplasias Encefálicas/sangre , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/mortalidad , Estudios de Casos y Controles , Neoplasias Colorrectales/sangre , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/mortalidad , Citocinas/sangre , Factores de Transcripción Forkhead/genética , Humanos , Estimación de Kaplan-Meier , Síndromes Neoplásicos Hereditarios/sangre , Síndromes Neoplásicos Hereditarios/genética , Síndromes Neoplásicos Hereditarios/mortalidad , Receptor de Muerte Celular Programada 1/genética , Receptores Inmunológicos/genética , Linfocitos T/inmunología , Regulación hacia Arriba
15.
J Phys Chem B ; 123(43): 9180-9186, 2019 10 31.
Artículo en Inglés | MEDLINE | ID: mdl-31609605

RESUMEN

Crystal growth of N2 hydrate in a three-phase system consisting of N2 hydrate, liquid water, and gaseous N2 was performed by molecular dynamics simulation at 260 K. Pressure influence on hydrate growth was evaluated. The kinetic properties including the growth rates and cage occupancies of the newly formed hydrate and the diffusion coefficient and concentration of N2 molecules in liquid phase were measured. The results showed that the growth of N2 hydrate could be divided into two stages where N2 molecules in gas phase had to dissolve in liquid phase and then form hydrate cages at the liquid-hydrate interface. The diffusion coefficient and concentration of N2 in liquid phase increased linearly with increasing pressure. As the pressure rose from 50 to 100 MPa, the hydrate growth rate kept increasing from 0.11 to 0.62 cages·ns-1·Å-2 and then dropped down to around 0.40 cages·ns-1·Å-2 once the pressure surpassed 100 MPa. During the hydrate formation, the initial sII N2 hydrate phase set in the system served as a template for the subsequent growth of N2 hydrate so that no new crystal structure was found. Analysis on the cage occupancies revealed that the amount of cages occupied by two N2 molecules increased evidently when the pressure was above 100 MPa, which slowed down the growth rate of hydrate cages. Additionally, a small fraction of defective cages including two N2 molecules trapped in 51265 cages and three N2 molecules trapped 51268 cages was observed during the hydrate growth.

16.
RSC Adv ; 9(26): 14727-14735, 2019 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-35516298

RESUMEN

In this work, the decomposition behaviour of methane hydrate in porous media was investigated microscopically using powder X-ray diffraction, cryogenic scanning electron microscopy and in situ Raman spectroscopy. The effect of grain sizes on the decomposition of methane hydrate was measured. The results showed that bulk hydrates could exist stably at 223 K and atmospheric pressure because of the self-preservation effect. However, hydrate formed in sands was relatively easier to decompose because it had a higher equilibrium pressure compared with bulk hydrate at the same temperature. In this case, there would be a higher decomposition driving force. Interestingly, the complete decomposition time for hydrate formed in sands did not decrease with the decrease in particle size. The shortest decomposition time was observed for the sands with the particle size range of 38-55 µm, which was less than 30 minutes. Moreover methane hydrate was found to decompose faster in the porous medium containing 3.5 wt% NaCl, which suggested that there was almost no self-preservation effect. In situ Raman measurements showed that the integrated intensity ratio of methane in large and small cages (A L/A S) did not change during the decomposition process, suggesting that the methane hydrate crystal units decomposed as an entity in sands. This study provided important data as a basis for drilling fluid technology in hydrate mining.

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