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1.
Int J Mol Sci ; 25(3)2024 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-38339223

RESUMEN

Aralia elata (Miq.) Seem is a medicinal plant that shares a common pathway for the biosynthesis of triterpenoid saponins with Panax ginseng. Here, we transferred the dammarenediol-II synthase gene from P. ginseng (PgDDS; GenBank: AB122080.1) to A. elata. The growth of 2-year-old transgenic plants (L27; 9.63 cm) was significantly decreased compared with wild-type plants (WT; 74.97 cm), and the leaflet shapes and sizes of the transgenic plants differed from those of the WT plants. Based on a terpene metabolome analysis of leaf extracts from WT, L13, and L27 plants, a new structural skeleton for ursane-type triterpenoid saponins was identified. Six upregulated differentially accumulated metabolites (DAMs) were detected, and the average levels of Rg3 and Re in the leaves of the L27 plants were 42.64 and 386.81 µg/g, respectively, increased significantly compared with the WT plants (15.48 and 316.96 µg/g, respectively). Thus, the expression of PgDDS in A. elata improved its medicinal value.


Asunto(s)
Aralia , Plantas Medicinales , Saponinas , Triterpenos , Aralia/genética , Aralia/química , Saponinas/química , Triterpenos/química , Plantas Medicinales/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Hojas de la Planta/metabolismo
2.
Sensors (Basel) ; 23(2)2023 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-36679825

RESUMEN

Artifacts are divergent strip artifacts or dark stripe artifacts in Industrial Computed Tomography (ICT) images due to large differences in density among the components of scanned objects, which can significantly distort the actual structure of scanned objects in ICT images. The presence of artifacts can seriously affect the practical application effectiveness of ICT in defect detection and dimensional measurement. In this paper, a series of convolution neural network models are designed and implemented based on preparing the ICT image artifact removal datasets. Our findings indicate that the RF (receptive field) and the spatial resolution of network can significantly impact the effectiveness of artifact removal. Therefore, we propose a dilated residual network for turbine blade ICT image artifact removal (DRAR), which enhances the RF of the network while maintaining spatial resolution with only a slight increase in computational load. Extensive experiments demonstrate that the DRAR achieves exceptional performance in artifact removal.


Asunto(s)
Artefactos , Procesamiento de Imagen Asistido por Computador , Procesamiento de Imagen Asistido por Computador/métodos , Tomografía Computarizada por Rayos X , Redes Neurales de la Computación
3.
Sensors (Basel) ; 23(3)2023 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-36772535

RESUMEN

In recent years, thanks to the performance advantages of convolutional neural networks (CNNs), CNNs have been widely used in image denoising. However, most of the CNN-based image-denoising models cannot make full use of the redundancy of image data, which limits the expressiveness of the model. We propose a new image-denoising model that aims to extract the local features of the image through CNN and focus on the global information of the image through the attention similarity module (ASM), especially the global similarity details of the image. Furthermore, dilation convolution is used to enlarge the receptive field to better focus on the global features. Moreover, avg-pooling is used to smooth and suppress noise in the ASM to further improve model performance. In addition, through global residual learning, the effect is enhanced from shallow to deep layers. A large number of experiments show that our proposed model has a better image-denoising effect, including quantitative and visual results. It is more suitable for complex blind noise and real images.

4.
Drug Dev Ind Pharm ; 48(5): 189-197, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35730236

RESUMEN

OBJECTIVE: The network pharmacology approach and molecular docking were employed to explore the mechanism of Pyrrosiae Folium (PF) against prostate cancer (PCa). METHODS: The active compounds and their corresponding putative targets of PF were identified by the Traditional Chinese Medicine Systems Pharmacology (TCMSP), the gene names of the targets were obtained from the UniProt database. The collection of genes associated with PCa was obtained from GeneCards and DisGeNET database. We merged the drug targets and disease targets by online software, Draw Venn Diagram. The resulting gene list was imported into R software (v3.6.3) for GO and KEGG function enrichment analysis. The STRING database was utilized for protein-protein interaction (PPI) network construction. The cytoHubba plugin of Cytoscape was used to identify core genes. Further, molecular docking analysis of the hub targets was carried out using AutoDock Vina software (v1.5.6). RESULTS: A total of six active components were screened by PF, with 167 corresponding putative targets, 1395 related targets for PCa, and 113 targets for drugs and diseases. The 'drug-component-disease-target' network was constructed by Cytoscape software and the target genes mainly involved in the complex treating effects associated with response to oxidative stress, cytokine activity, pathways in cancer, PCa pathway, and tumor necrosis factor (TNF) signaling pathway. Core genes in the PPI network were TNF, JUN, IL6, IL1B, CXCL8, RELA, CCL2, TP53, IL10, and FOS. The molecular docking results reveal the better binding affinity of six active components to the core targets. CONCLUSION: The results of this study indicated that PF may be have a certain anti-PCa effect by regulating related target genes, affecting pathways in cancer, TNF signaling pathway, and hepatitis B signaling pathway.


Asunto(s)
Medicamentos Herbarios Chinos , Neoplasias de la Próstata , Medicamentos Herbarios Chinos/farmacología , Medicamentos Herbarios Chinos/uso terapéutico , Humanos , Masculino , Medicina Tradicional China , Simulación del Acoplamiento Molecular , Farmacología en Red , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/genética
5.
Sensors (Basel) ; 21(12)2021 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-34208036

RESUMEN

Object tracking is one of the most challenging problems in the field of computer vision. In challenging object tracking scenarios such as illumination variation, occlusion, motion blur and fast motion, existing algorithms can present decreased performances. To make better use of the various features of the image, we propose an object tracking method based on the self-adaptive feature selection (SAFS) algorithm, which can select the most distinguishable feature sub-template to guide the tracking task. The similarity of each feature sub-template can be calculated by the histogram of the features. Then, the distinguishability of the feature sub-template can be measured by their similarity matrix based on the maximum a posteriori (MAP). The selection task of the feature sub-template is transformed into the classification task between feature vectors by the above process and adopt modified Jeffreys' entropy as the discriminant metric for classification, which can complete the update of the sub-template. Experiments with the eight video sequences in the Visual Tracker Benchmark dataset evaluate the comprehensive performance of SAFS and compare them with five baselines. Experimental results demonstrate that SAFS can overcome the difficulties caused by scene changes and achieve robust object tracking.

6.
Sensors (Basel) ; 17(4)2017 Mar 31.
Artículo en Inglés | MEDLINE | ID: mdl-28362345

RESUMEN

Object tracking has remained a challenging problem in recent years. Most of the trackers can not work well, especially when dealing with problems such as similarly colored backgrounds, object occlusions, low illumination, or sudden illumination changes in real scenes. A centroid iteration algorithm using multiple features and a posterior probability criterion is presented to solve these problems. The model representation of the object and the similarity measure are two key factors that greatly influence the performance of the tracker. Firstly, this paper propose using a local texture feature which is a generalization of the local binary pattern (LBP) descriptor, which we call the double center-symmetric local binary pattern (DCS-LBP). This feature shows great discrimination between similar regions and high robustness to noise. By analyzing DCS-LBP patterns, a simplified DCS-LBP is used to improve the object texture model called the SDCS-LBP. The SDCS-LBP is able to describe the primitive structural information of the local image such as edges and corners. Then, the SDCS-LBP and the color are combined to generate the multiple features as the target model. Secondly, a posterior probability measure is introduced to reduce the rate of matching mistakes. Three strategies of target model update are employed. Experimental results show that our proposed algorithm is effective in improving tracking performance in complicated real scenarios compared with some state-of-the-art methods.

7.
J Asian Nat Prod Res ; 19(1): 9-14, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27256560

RESUMEN

Three new alkaloids namely 8-(4-hydroxyphenyl)-6-methoxy-3,4-dihydroisoquinolin-1(2H)-one (1), 4-aminonigellidine (2), and N-[(4-hydroxy-2-isopropyl-5-methyl)]phenylurea (3), along with six known ones (4-9), were isolated from the seeds of Nigella glandulifera. The structures of 1-3 were determined through spectroscopic analyses (HRESIMS, 1D/2D NMR). Compound 1 was a rare isoquinolinone alkaloid with phenyl substituted at C-8.


Asunto(s)
Alcaloides/aislamiento & purificación , Medicamentos Herbarios Chinos/aislamiento & purificación , Isoquinolinas/aislamiento & purificación , Nigella/química , Compuestos de Fenilurea/aislamiento & purificación , Semillas/química , Alcaloides/química , Medicamentos Herbarios Chinos/química , Indazoles , Isoquinolinas/química , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Compuestos de Fenilurea/química
8.
Sci Adv ; 10(10): eadk3854, 2024 Mar 08.
Artículo en Inglés | MEDLINE | ID: mdl-38446880

RESUMEN

Liquid crystal elastomers (LCEs) have garnered attention for their remarkable reversible strains under various stimuli. Early studies on LCEs mainly focused on basic dimensional changes in macrostructures or quasi-three-dimensional (3D) microstructures. However, fabricating complex 3D microstructures and cross-scale LCE-based structures has remained challenging. In this study, we report a compatible method named melt electrowriting (MEW) to fabricate LCE-based microfiber actuators and various 3D actuators on the micrometer to centimeter scales. By controlling printing parameters, these actuators were fabricated with high resolutions (4.5 to 60 µm), actuation strains (10 to 55%), and a maximum work density of 160 J/kg. In addition, through the integration of a deep learning-based model, we demonstrated the application of LCE materials in temperature field sensing. Large-scale, real-time, LCE grid-based spatial temperature field sensors have been designed, exhibiting a low response time of less than 42 ms and a high precision of 94.79%.

9.
ACS Nano ; 18(18): 11717-11731, 2024 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-38651873

RESUMEN

Evaluating the heterogeneity of extracellular vesicles (EVs) is crucial for unraveling their complex actions and biodistribution. Here, we identify consistent architectural heterogeneity of EVs using cryogenic transmission electron microscopy (cryo-TEM), which has an inherent ability to image biological samples without harsh labeling methods while preserving their native conformation. Imaging EVs isolated using different methodologies from distinct sources, such as cancer cells, normal cells, immortalized cells, and body fluids, we identify a structural atlas of their dominantly consistent shapes. We identify EV architectural attributes by utilizing a segmentation neural network model. In total, 7,576 individual EVs were imaged and quantified by our computational pipeline. Across all 7,576 independent EVs, the average eccentricity was 0.5366 ± 0.2, and the average equivalent diameter was 132.43 ± 67 nm. The architectural heterogeneity was consistent across all sources of EVs, independent of purification techniques, and compromised of single spherical, rod-like or tubular, and double shapes. This study will serve as a reference foundation for high-resolution images of EVs and offer insights into their potential biological impact.


Asunto(s)
Microscopía por Crioelectrón , Vesículas Extracelulares , Vesículas Extracelulares/química , Vesículas Extracelulares/metabolismo , Humanos , Redes Neurales de la Computación , Microscopía Electrónica de Transmisión , Procesamiento de Imagen Asistido por Computador/métodos
10.
Langmuir ; 29(20): 5944-51, 2013 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-23614663

RESUMEN

A sol-gel cooperative assembly method was demonstrated for the fabrication of inverse opal films with an open surface. In this method, a sol-gel silicate precursor was cooperatively assembled into the interstitial spaces of microspheres at the same time when polystyrene templates formed in between two desired substrates. Silica inverse opals with a three-dimensional ordered macroporous (3DOM) structure were obtained after selective removing the colloidal templates by calcination. The open surfaces with a high degree of interconnected porosity and extremely uniform pore size were characterized by scanning electron microscope (SEM). Optical transmission spectra reveals the existence of considerable deep band gaps of up to 70% and steep band edges of up to 6%/nm in the [111] directions of the 3DOM silica samples. A little shrinkage confirmed by transmission spectra is not larger than 3%, in consistent with the results measured by SEM, which revealing the sufficient and compact infiltration into the interstitial spaces by our confined sol-gel coassembly method. With different incidence angles, the positions of pseudogaps can be easily tuned in the wide range from 720 nm to 887 nm, agreed well with the calculated values by the Bragg law. All the results prove that the sol-gel coassembly method with two substrates confinement is a simple, low cost, convenient and versatile method for the fabrication of silica inverse opals without overlayers in large domains.


Asunto(s)
Dióxido de Silicio/química , Coloides/química , Geles/química , Estructura Molecular , Tamaño de la Partícula , Poliestirenos/química , Porosidad , Propiedades de Superficie
11.
Appl Opt ; 52(4): B52-9, 2013 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-23385942

RESUMEN

A sinusoidal phase-modulating He-Ne laser subject to weak optical feedback has been used to develop an interferometer that is capable of performing real-time displacement measurement with nanometer accuracy. The principle and the signal processing method are introduced. A commercial dual-frequency interferometer is included in the displacement measurement in both small and large ranges to evaluate the performance of the developed interferometer. Experimental results show that the average errors and standard deviations of the interferometer are in good agreement with data obtained from the commercial interferometer. The resolution and the multiple feedback effect of the interferometer are discussed in detail. These results show that the development of the interferometer is reasonable and feasible.

12.
Genes (Basel) ; 14(6)2023 05 23.
Artículo en Inglés | MEDLINE | ID: mdl-37372312

RESUMEN

Aralia elata is an important herb due to the abundance of pentacyclic triterpenoid saponins whose important precursors are squalene and OA. Here, we found that MeJA treatment promoted both precursors accumulation, especially the latter, in transgenic A. elata, overexpressing a squalene synthase gene from Panax notoginseng(PnSS). In this study, Rhizobium-mediated transformation was used to express the PnSS gene. Gene expression analysis and high-performance liquid chromatography (HPLC) were used to identify the effect of MeJA on squalene and OA accumulation. The PnSS gene was isolated and expressed in A. elata. Transgenic lines showed a very high expression of the PnSS gene and farnesyl diphosphate synthase gene (AeFPS) and a slightly higher squalene content than the wild-type, but endogenous squalene synthase (AeSS), squalene epoxidase (AeSE), and ß-amyrin synthase (Aeß-AS) gene were decreased as well as OA content. Following one day of MeJA treatment, the expression levels of PeSS, AeSS, and AeSE genes increased significantly. On day 3, the maximum content of both products reached 17.34 and 0.70 mg·g-1, which increased 1.39- and 4.90-fold than in the same lines without treatment. Transgenic lines expressing PnSS gene had a limited capability to promote squalene and OA accumulation. MeJA strongly activated their biosynthesis pathways, leading to enhance yield.


Asunto(s)
Aralia , Ácido Oleanólico , Escualeno , Aralia/química , Farnesil Difosfato Farnesil Transferasa/genética
13.
bioRxiv ; 2023 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-38168235

RESUMEN

Evaluating the heterogeneity of extracellular vesicles (EVs) is crucial for unraveling their complex actions and biodistribution. Here, we identify consistent architectural heterogeneity of EVs using cryogenic transmission electron microscopy (cryo-TEM) which has an inherent ability to image biological samples without harsh labeling methods and while preserving their native conformation. Imaging EVs isolated using different methodologies from distinct sources such as cancer cells, normal cells, and body fluids, we identify a structural atlas of their dominantly consistent shapes. We identify EV architectural attributes by utilizing a segmentation neural network model. In total, 7,576 individual EVs were imaged and quantified by our computational pipeline. Across all 7,576 independent EVs, the average eccentricity was 0.5366, and the average equivalent diameter was 132.43 nm. The architectural heterogeneity was consistent across all sources of EVs, independent of purification techniques, and compromised of single spherical (S. Spherical), rod-like or tubular, and double shapes. This study will serve as a reference foundation for high-resolution EV images and offer insights into their potential biological impact.

14.
Sci Transl Med ; 15(677): eabo3332, 2023 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-36599007

RESUMEN

SARS-CoV-2 continues to accumulate mutations to evade immunity, leading to breakthrough infections after vaccination. How researchers can anticipate the evolutionary trajectory of the virus in advance in the design of next-generation vaccines requires investigation. Here, we performed a comprehensive study of 11,650,487 SARS-CoV-2 sequences, which revealed that the SARS-CoV-2 spike (S) protein evolved not randomly but into directional paths of either high infectivity plus low immune resistance or low infectivity plus high immune resistance. The viral infectivity and immune resistance of variants are generally incompatible, except for limited variants such as Beta and Kappa. The Omicron variant has the highest immune resistance but showed high infectivity in only one of the tested cell lines. To provide cross-clade immunity against variants that undergo diverse evolutionary pathways, we designed a new pan-vaccine antigen (Span). Span was designed by analyzing the homology of 2675 SARS-CoV-2 S protein sequences from the NCBI database before the Delta variant emerged. The refined Span protein harbors high-frequency residues at given positions that reflect cross-clade generality in sequence evolution. Compared with a prototype wild-type (Swt) vaccine, which, when administered to mice, induced serum with decreased neutralization activity against emerging variants, Span vaccination of mice elicited broad immunity to a wide range of variants, including those that emerged after our design. Moreover, vaccinating mice with a heterologous Span booster conferred complete protection against lethal infection with the Omicron variant. Our results highlight the importance and feasibility of a universal vaccine to fight against SARS-CoV-2 antigenic drift.


Asunto(s)
COVID-19 , Animales , Ratones , Humanos , COVID-19/prevención & control , SARS-CoV-2 , Vacunación , Anticuerpos Antivirales , Anticuerpos Neutralizantes
15.
Nanotechnology ; 23(27): 275605, 2012 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-22710561

RESUMEN

Doping is a common and effective approach to tailor semiconductor properties. Here, we demonstrate the growth of large-area sulfur (S)-doped graphene sheets on copper substrate via the chemical vapor deposition technique by using liquid organics (hexane in the presence of S) as the precursor. We found that S could be doped into graphene's lattice and mainly formed linear nanodomains, which was proved by elemental analysis, high resolution transmission microscopy and Raman spectra. Measurements on S-doped graphene field-effect transistors (G-FETs) revealed that S-doped graphene exhibited lower conductivity and distinctive p-type semiconductor properties compared with those of pristine graphene. Our approach has produced a new member in the family of graphene based materials and is promising for producing graphene based devices for multiple applications.


Asunto(s)
Cristalización/métodos , Grafito/química , Hexanos/química , Nanoestructuras/química , Nanoestructuras/ultraestructura , Semiconductores , Conductividad Eléctrica , Ensayo de Materiales , Tamaño de la Partícula , Soluciones , Propiedades de Superficie
16.
Front Plant Sci ; 13: 822942, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35300010

RESUMEN

Aralia elata is a perennial woody plant of the genus Aralia in the family Araliaceae. It is rich in saponins and therefore has a wide range of pharmacological effects. Here, we report a high-quality reference genome of A. elata, with a genome size of 1.21 Gb and a contig N50 of 51.34 Mb, produced by PacBio HiFi sequencing technology. This is the first genome assembly for the genus Aralia. Through genome evolutionary analysis, we explored the phylogeny and whole genome duplication (WGD) events in the A. elata genome. The results indicated that a recent WGD event occurred in the A. elata genome. Estimation of the divergence times indicated that the WGD may be shared by Araliaceae. By analyzing the genome sequence of A. elata and combining the transcriptome data from three tissues, we discovered important genes related to triterpene saponins biosynthesis. Furthermore, based on the embryonic callus induction system of A. elata established in our laboratory, we set up the genetic transformation system of this plant. The genomic resources and genetic transformation system obtained in this study provide insights into A. elata and lays the foundation for further exploration of the A. elata regulatory mechanism.

17.
Int J Biol Macromol ; 207: 750-759, 2022 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-35318079

RESUMEN

The objectives of this study were (1) to prepare Armillariella tabescens mycelia polysaccharides (PAT) with remarkably growth inhibitory effect on typical food-borne pathogenic bacteria using a green and efficient polyamide method and (2) to explore the antibacterial mechanism of PAT for use as a natural antibacterial agent. The sugar and uronic acid contents of PAT were 93.41% and 12.24%, respectively. PAT could inhibit the growth of Escherichia coli, Proteus vulgaris, Bacillus subtilis, and Staphylococcus aureus cells, with minimum inhibitory concentrations of 0.5, 1.0, 4.0, and 4.0 mg/mL, respectively. Ultra-high-resolution field emission scanning electron microscopy and high-resolution transmission electron microscopy analysis revealed cell wall and membrane rupture of E. coli treated with PAT. Further, 0.5-4.0 mg/mL PAT was found to significantly (P < 0.01) and concentration-dependently increase the conductivity of the broth, exudation of the intracellular protein, and alkaline phosphatase and ß-galactosidase activities. Confocal laser scanning microscopy revealed morphological changes in E. coli DNA after PAT treatment and intracellular reactive oxygen species accumulation; flow cytometry revealed E. coli cell apoptosis. Our findings provide a theoretical basis and technical support for the development of PAT as a natural antibacterial product.


Asunto(s)
Infecciones por Escherichia coli , Escherichia coli , Antibacterianos/farmacología , Armillaria , Bacillus subtilis , Humanos , Pruebas de Sensibilidad Microbiana , Polisacáridos/farmacología
18.
IEEE Trans Cybern ; 50(1): 140-152, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30273179

RESUMEN

As a typical model-based evolutionary algorithm, estimation of distribution algorithm (EDA) possesses unique characteristics and has been widely applied in global optimization. However, the commonly used Gaussian EDA (GEDA) usually suffers from premature convergence, which severely limits its search efficiency. This paper first systematically analyzes the reasons for the deficiency of traditional GEDA, then tries to enhance its performance by exploiting the evolution direction, and finally develops a new GEDA variant named EDA2. Instead of only utilizing some good solutions produced in the current generation to estimate the Gaussian model, EDA2 preserves a certain number of high-quality solutions generated in the previous generations into an archive and employs these historical solutions to assist estimating the covariance matrix of Gaussian model. By this means, the evolution direction information hidden in the archive is naturally integrated into the estimated model, which in turn can guide EDA2 toward more promising solution regions. Moreover, the new estimation method significantly reduces the population size of EDA2 since it needs fewer individuals in the current population for model estimation. As a result, a fast convergence can be achieved. To verify the efficiency of EDA2, we tested it on a variety of benchmark functions and compared it with several state-of-the-art EAs. The experimental results demonstrate that EDA2 is efficient and competitive.

19.
ACS Appl Mater Interfaces ; 12(37): 41932-41941, 2020 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-32812740

RESUMEN

Multicore iron oxide nanoparticles, also known as colloidal nanocrystal clusters, are magnetic materials with diverse applications in biomedicine and photonics. Here, we examine how both of their characteristic dimensional features, the primary particle and sub-micron colloid diameters, influence their magnetic properties and performance in two different applications. The characterization of these basic size-dependent properties is enabled by a synthetic strategy that provides independent control over both the primary nanocrystal and cluster dimensions. Over a wide range of conditions, electron microscopy and X-ray diffraction reveal that the oriented attachment of smaller nanocrystals results in their crystallographic alignment throughout the entire superstructure. We apply a sulfonated polymer with high charge density to prevent cluster aggregation and conjugate molecular dyes to particle surfaces so as to visualize their collection using handheld magnets. These libraries of colloidal clusters, indexed both by primary nanocrystal dimension (dp) and overall cluster diameter (Dc), form magnetic photonic crystals with relatively weak size-dependent properties. In contrast, their performance as MRI T2 contrast agents is highly sensitive to cluster diameter, not primary particle size, and is optimized for materials of 50 nm diameter (r2 = 364 mM-1 s-1). These results exemplify the relevance of dimensional control in developing applications for these versatile materials.


Asunto(s)
Medios de Contraste/química , Imagen por Resonancia Magnética , Nanopartículas de Magnetita/química , Óptica y Fotónica , Tamaño de la Partícula , Propiedades de Superficie
20.
Sci Rep ; 10(1): 3762, 2020 Feb 28.
Artículo en Inglés | MEDLINE | ID: mdl-32111861

RESUMEN

The injection of low-salinity brine enhances oil recovery by altering the mineral wettability in carbonate reservoirs. However, the reported effectiveness of low-salinity water varies significantly in the literature, and the underlying mechanism of wettability alteration is controversial. In this work, we investigate the relationships between characteristics of crude oils and the oils' response to low-salinity water in a spontaneous imbibition test, aiming (1) to identify suitable indicators of the effectiveness of low-salinity water and (2) to evaluate possible mechanisms of low-salinity-induced wettability alteration, including rock/oil charge repulsion and microdispersion formation. Seven oils are tested by spontaneous imbibition and fully characterized in terms of their acidity, zeta potential, interfacial tension, microdispersion propensity, water-soluble organics content and saturate-aromatic-resin-asphaltene fractionation. For the first time, the effectiveness of low-salinity water is found to positively correlate with the oil interfacial tension in low-salinity water. Oils with higher interfacial activity are found to respond more positively to low-salinity water. Moreover, cryogenic transmission electron microscopy images suggest that microdispersion is essentially macroemulsion, and its formation is an effective indicator - but not the root cause - of wettability alteration. The repulsive zeta potential for the rock and the oil in low-salinity water is found to be an insufficient condition for wettability alteration in carbonate minerals.

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