Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
1.
Org Biomol Chem ; 21(13): 2754-2767, 2023 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-36917467

RESUMO

ß-D-N4-Hydroxycytidine (NHC) derivatives with structural modifications at the C4', O4' or C6 position and 4'-fluorouridine prodrugs were synthesized and evaluated for their antiviral activities against respiratory syncytial virus (RSV) or influenza virus (IFV) in vitro. The NHC derivatives were found inactive, but 4'-fluorouridine and its prodrugs had potent anti-RSV and anti-IFV activities. 4'-Fluorouridine was proved to be a nucleoside with poor stability, but the tri-ester prodrugs exhibited enhanced stability, especially tri-isobutyrate ester 1a. This prodrug also showed excellent oral pharmacokinetic properties in rats, with potential to be an oral antiviral candidate.


Assuntos
Pró-Fármacos , Vírus Sincicial Respiratório Humano , Ratos , Animais , Pró-Fármacos/química , Antivirais/química , Nucleosídeos , Ésteres
2.
Molecules ; 27(14)2022 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-35889463

RESUMO

Hydrocarbon vapor adsorption experiments (HVAs) are one of the most prevalent methods used to evaluate the proportion of adsorbed state oil, critical in understanding the recoverable resources of shale oil. HVAs have some limitations, which cannot be directly used to evaluate the proportion of adsorbed state oil. The proportion of adsorbed state oil from HVA is always smaller than that in shale oil reservoirs, which is caused by the difference in adsorption characteristics of liquid and gaseous hydrocarbons. The results of HVA need to be corrected. In this paper, HVA was conducted with kaolinite, an important component of shale. A new method is reported here to evaluate the proportion of adsorbed state oil. Molecular dynamics simulations (MDs) of gaseous/liquid hydrocarbons with the same temperature and pressure as the HVAs were used as a reference to reveal the errors in the HVAs evaluation from the molecular scale. We determine the amount of free state of hydrocarbons by HVAs, and then calculate the proportion of adsorbed state oil by the liquid hydrocarbon MD simulation under the same conditions. The results show that gaseous hydrocarbons adsorptions are monolayer at low relative pressures and bilayer at high relative pressures. The liquid hydrocarbons adsorption is multilayer adsorption. The adsorption capacity of liquid hydrocarbons is over 2.7 times higher than gaseous hydrocarbons. The new method will be more effective and accurate to evaluate the proportion of adsorbed state oil.


Assuntos
Gases , Hidrocarbonetos , Adsorção , Caulim , Minerais , Campos de Petróleo e Gás
3.
Bioorg Med Chem ; 46: 116364, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34450570

RESUMO

The nucleoside metabolite of remdesivir, GS-441524 displays potent anti-SARS-CoV-2 efficacy, and is being evaluated in clinical as an oral antiviral therapeutic for COVID-19. However, this nucleoside has a poor oral bioavailability in non-human primates, which may affect its therapeutic efficacy. Herein, we reported a variety of GS-441524 analogs with modifications on the base or the sugar moiety, as well as some prodrug forms, including five isobutyryl esters, two l-valine esters, and one carbamate. Among the new nucleosides, only the 7-fluoro analog 3c had moderate anti-SARS-CoV-2 activity, and its phosphoramidate prodrug 7 exhibited reduced activity in Vero E6 cells. As for the prodrugs, the 3'-isobutyryl ester 5a, the 5'-isobutyryl ester 5c, and the tri-isobutyryl ester 5g hydrobromide showed excellent oral bioavailabilities (F = 71.6%, 86.6% and 98.7%, respectively) in mice, which provided good insight into the pharmacokinetic optimization of GS-441524.


Assuntos
Adenosina/análogos & derivados , Antivirais/farmacologia , SARS-CoV-2/efeitos dos fármacos , Adenosina/farmacocinética , Adenosina/farmacologia , Adenosina/toxicidade , Animais , Antivirais/síntese química , Antivirais/farmacocinética , Antivirais/toxicidade , Chlorocebus aethiops , Masculino , Camundongos Endogâmicos ICR , Testes de Sensibilidade Microbiana , Pró-Fármacos/síntese química , Pró-Fármacos/farmacocinética , Pró-Fármacos/farmacologia , Pró-Fármacos/toxicidade , Células Vero
4.
Phys Chem Chem Phys ; 22(46): 27433-27440, 2020 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-33232404

RESUMO

Active elements play key roles in improving the interfacial bonding between Ag-based fillers and AlN ceramics. An understanding of the influence mechanism of active elements to interfacial adhesion can help us optimize the composition of active filler metals. In this paper, Ag(111)/AlN(0001) interfaces with different terminations and stacking sequences were constructed first. The N-terminated A-site interface was found to have the largest work of adhesion (Wad). Then, the effects of Si, Ti and V dopants on the Ag/AlN interfacial bonding were investigated via first-principles calculations. The results reveal that the Ti and V dopants can increase the values of Wad significantly. Electronic structure analysis reveals that the Si-N, Ti-N and V-N bonds formed at the interface are mainly ionic, and with some composition of covalent. Ti and V atoms can form strong bonds with not only the AlN slab, but also the neighboring Ag layers. It can be concluded that Ag-Ti and Ag-V active fillers are more suited to braze AlN. Ti-N and V-N compounds formed at the interface can greatly improve the interfacial bonding strength.

5.
Acta Pharm Sin B ; 14(1): 207-222, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38261825

RESUMO

Modulating Tankyrases (TNKS), interactions with USP25 to promote TNKS degradation, rather than inhibiting their enzymatic activities, is emerging as an alternative/specific approach to inhibit the Wnt/ß-catenin pathway. Here, we identified UAT-B, a novel neoantimycin analog isolated from Streptomyces conglobatus, as a small-molecule inhibitor of TNKS-USP25 protein-protein interaction (PPI) to overcome multi-drug resistance in colorectal cancer (CRC). The disruption of TNKS-USP25 complex formation by UAT-B led to a significant decrease in TNKS levels, triggering cell apoptosis through modulation of the Wnt/ß-catenin pathway. Importantly, UAT-B successfully inhibited the CRC cells growth that harbored high TNKS levels, as demonstrated in various in vitro and in vivo studies utilizing cell line-based and patient-derived xenografts, as well as APCmin/+ spontaneous CRC models. Collectively, these findings suggest that targeting the TNKS-USP25 PPI using a small-molecule inhibitor represents a compelling therapeutic strategy for CRC treatment, and UAT-B emerges as a promising candidate for further preclinical and clinical investigations.

6.
ACS Omega ; 8(32): 29346-29358, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37599934

RESUMO

Hybrid sedimentary rocks (HSR) represent a significant reservoir type in fine-grained sediments. However, the classification and understanding of HSR reservoirs, including their storage mechanisms and identification of optimal "sweet spots," have been limited due to the lack of clarity regarding the multiple sources of components and their mixing processes. This study focuses on the Lucaogou formation of Jimusaer Sag and aims to highlight the reservoir classification principles, controlling factors, and evolutionary patterns associated with the components of HSR, beginning with examining the microscopic pore structure. The analysis of the microscopic pore structure characteristics reveals the presence of five distinct reservoir types within the HSR. The quality of these reservoirs is governed by various factors, including the composition and support mode of particles, diagenesis, provenance, and sedimentary microfacies. In regions near a provenance with strong hydrodynamic conditions, the HSR predominantly exhibits type I and type II reservoirs, characterized by numerous coarse-grained components and a granular-support mode. As the distance from the provenance increases, transitioning into medium hydrodynamic conditions, the HSR shifts to an interbedded-support mode, primarily developing type III reservoirs. In areas far from the provenance with weak hydrodynamic conditions, HSR reservoir types primarily consist of type IV and type V. Additionally, diagenetic effects such as compaction and calcite cementation further deteriorate intergranular and dissolution pores, consequently diminishing reservoir quality. Notably, during the mixing deposition processes of sand and dolomite, the developmental mode of HSR shifts from type I to type II and type III. Likewise, in the mixing deposition of mud and sand, the HSR transitions from type II to type III and type IV. Similarly, the mixing deposition of dolomite and mud leads to a change in the developmental mode of HSR from type III to type IV and type V. Moreover, this study effectively predicts the occurrence of "sweet spots" using reservoir classification, which reveals their continuous distribution. These findings provide a geological foundation for evaluating "sweet spots" and testing the oil production in HSR reservoirs.

7.
Chem Biol Drug Des ; 99(4): 561-572, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34878718

RESUMO

A series of 2'-deoxy carbocyclic nucleosides characterized by various 6'-substitutions were synthesized and evaluated for their antiviral activities against three viruses, including hepatitis B virus (HBV), hepatitis C virus, and influenza virus. The in vitro antiviral assays indicated that these nucleosides only showed inhibitory activities against HBV, and the substituted groups at the 6' position significantly affected the activity. Among them, the guanosine analog 2b bearing a 6'-α-hydroxyl methyl group was the most potent compound with an EC50 value of 80 nM. The present study provided useful information for the discovery of antiviral carbocyclic nucleosides.


Assuntos
Antivirais , Nucleosídeos , Antivirais/farmacologia , Hepacivirus , Vírus da Hepatite B , Nucleosídeos/farmacologia
8.
Medicine (Baltimore) ; 101(31): e29555, 2022 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-35945754

RESUMO

BACKGROUND: Laryngeal squamous cell carcinoma (LSCC) is one of the most common forms of head and neck cancers. However, few studies have focused on the correlation between competing endogenous RNA (ceRNAs) and immune cells in LSCC. METHODS: RNAseq expression of LSCC and adjacent tissues were downloaded from The Cancer Genome Atlas to establish a ceRNA network. The key gene in ceRNA was screened by the cox regression analysis to establish a prognostic risk assessment model. The CIBERSORT algorithm was then used to screen important tumor-infiltrating cells related to LSCC. Finally, co-expression analysis was applied to explore the relationship between key genes in the ceRNA network and tumor-infiltrating cells. The external datasets were used to validate critical biomarkers. RESULTS: We constructed a prognostic risk assessment model of key genes in the ceRNA network. As it turned out, Kaplan-Meier survival analysis showed significant differences in overall survival rates between high-risk and low-risk groups (P < .001). The survival rate of the high-risk group was drastically lower than that of the low-risk group, and the AUC of 1 year, 3 years, and 5 years were all above 0.7. In addition, some immune infiltrating cells were also found to be related to LSCC. In the co-expression analysis, there is a negative correlation between plasma cells and TUBB3 (r = -0.33, P = .0013). External dataset validation also supports this result. CONCLUSION: In this study, we found that some key genes (SLC35C1, CLDN23, HOXB7, STC2, TMEM158, TNFRSF4, TUBB3) and immune cells (plasma cells) may correspond to the prognosis of LSCC.


Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Neoplasias Laríngeas , RNA Longo não Codificante , Biomarcadores Tumorais/genética , Carcinoma de Células Escamosas/patologia , Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Neoplasias de Cabeça e Pescoço/genética , Proteínas de Homeodomínio/genética , Humanos , Neoplasias Laríngeas/patologia , Proteínas de Membrana/genética , Prognóstico , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , RNA Mensageiro/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Proteínas Supressoras de Tumor/genética
9.
Nanomaterials (Basel) ; 11(2)2021 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-33498236

RESUMO

High frequency supercapacitors (HFSCs) are promising in alternating current line filtering and adaptable storage of high-frequency pulse electrical energy. Herein, we report a facile yet integrated-circuit-compatible fabrication of HFSC electrodes by combining chemical roughening of the sputtered metal (Au) films and in situ trace loading of a pseudocapacitive material (MnO x ). The developed electrode fabrication route is versatile for different substrates, and is described with the application paradigms of both on-chip (with Si/SiO2 substrate) and off-chip (without Si/SiO2 substrate, with Ti substrate as an example in this study) HFSCs. With Au/MnO x films on Si/SiO2 substrates as the working electrodes, the derived on-chip HFSC displayed satisfactory performance in high frequency applications (i.e., an areal capacitance of 131.7 µF cm-2, a phase angle of -78°, and a RC time constant of 0.27 ms, at 120 Hz).

10.
J Nanosci Nanotechnol ; 21(1): 85-97, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33213615

RESUMO

Wettability is an important physical property of shale. This parameter is related to the shale material composition and the fluid properties in the shale pores and plays an important role in the exploration and development of shale oil. Wettability is affected by the scale and roughness. The contact angle at the nanoscale on a smooth surface can better reflect the wettability of shale than the contact angle at higher scales. Molecular dynamics simulations can be used to measure the contact angle on a smooth surface at the nanoscale. This paper focuses on the effects of organic matter and minerals in shale and different components of shale oil on shale wettability. Wetting models of "organic matter-oil component-water," "quartz-oil component-water" and "kaolinite-oil component-water" at the nanoscale were constructed. Molecular dynamics simulation was used to study the morphological changes of different oil components and water on different surfaces. Studies have shown that organic matter is strongly oleophilic and hydrophobic. Polar components in shale oil can make organic matter slightly hydrophilic. It was recognized by quartz wettability experiments and simulation methods at the nanoscale that the cohesive energy of a liquid has a significant influence on the degree of spreading of the liquid on the surface. The "liquid-liquid-solid" wettability experiment is an effective method for determining mineral oleophilic or hydrophilic properties. The nanoquartz in the shale is strongly hydrophilic. The water wetting angle is related to the crude oil component. Nanokaolinite can have a tetrahedral or an octahedral surface; the tetrahedral surface is oleophilic and hydrophobic, and the octahedral surface exhibits strong hydrophilicity. The wettabilities of both surfaces are related to the crude oil component.

11.
J Nanosci Nanotechnol ; 21(1): 225-233, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33213625

RESUMO

Kaolinite is widely distributed in shale formations. Kaolinite has two surface types, Si-O and Al-OH, and the two surfaces have different chemical properties. The surface wettability of kaolinite minerals is closely related to the occurrence of crude oil, the migration process of crude oil, and the filling process of crude oil. In this paper, we focus on the oil-water rock wettability of different alkane hydrocarbons on the different surfaces of kaolinite and construct a model of oil and water with variation of the alkane components on the surface of tetrahedral and octahedral kaolinite. Molecular dynamics methods were used to study the morphological changes in water clusters in different alkanes on different surfaces of kaolinite and to calculate the wetting angles. Studies have shown that the octahedral kaolinite surface is strongly hydrophilic, and the water clusters become monolayers adsorbed on the surface. Water easily displaces the oil on the surface and preferentially drives low carbon number alkanes. The tetrahedral siloxane kaolinite surface is oleophilic, the water molecules in C6H14-C18H38 are clustered on the surface, and the wetting angle of the water cluster in the alkane increases with increasing carbon number. Water has difficulty displacing oil on this surface.

12.
J Nanosci Nanotechnol ; 21(1): 108-119, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33213617

RESUMO

To confirm the rules and transformation conditions of shale gas adsorption and establish a model for evaluating the adsorption capacity of shale gas quantitatively, it is necessary to reveal the shale gas adsorption mechanism. The adsorption mechanism of CH4 and CO2 in Kaolinite slit nanopores has been studied under the simulated conditions of 90 °C and 30 or 50 MPa by the grand canonical Monte Carlo (GCMC) method. The results indicate that CH4 is controlled only by the Van der Waals forces on the mineral surface because CH4 is nonpolar, while CO2 is controlled by both Van der Waals forces and Coulomb forces due to a certain electric quadrupole moment, which makes the adsorption capacity of CO2 on kaolinite greater than that of CH4. Due to the overlapping adsorption potential on the kaolinite surface of micropores (1 nm), the peak of the density profile is higher in the micropores than the peak in the mesopores (4 nm), resulting in the filling effect in the micropores. On the surface of the silicon-oxygen octahedron, the adsorption site for CH4 and CO2 is in the center of the silicone hexagon-ring, and CO2 with a quadrupole moment shifts near the polar oxygen atoms. In contrast, the adsorption sites of CH4 are relatively dispersed on the surface of the aluminum-oxygen octahedron with a hydroxyl group, while the adsorption sites of CO2 are concentrated in the location of the aggregated oxygen atoms. When CH4 and CO2 coexist, CO2 tends to be adsorbed prior to CH4. With the proportion of CO2 increasing, the competitive adsorption effect is gradually aggravated, which suggests the rationality of injecting CO2 to improve the recovery efficiency of shale gas. These findings can provide theoretical support for shale gas exploration and development.

13.
Cancer Manag Res ; 11: 10107-10115, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31819643

RESUMO

INTRODUCTION: Laryngeal cancer is the most common head and neck cancer worldwide. It is urgent to identify the mechanisms underlying laryngeal cancer pathogenesis. In the present study, we investigated the biological functions of Peripherin 2 (PRPH2) in laryngeal cancer and uncovered the molecular mechanism underlying this disease. METHODS: Laryngeal cancer tissues were used to analyze the expression of PRPH2. In vitro transwell matrigel invasion assay and annexin V anoikis assay in laryngeal cancer cells were conducted to investigate PRPH2 related biological functions. Quantitative real-time PCR and Western blotting were performed to investigate the expression and mechanism of PRPH2 in laryngeal cancer. RESULTS: We found that the expression of PRPH2 was significantly downregulated in laryngeal cancer tissues. Overexpression of PRPH2 suppressed the invasion and anoikis inhibition of laryngeal cancer cells. Furthermore, PRPH2 overexpression increased the phosphorylation of YAP and LATS1 and decreased the activities of Rho GTPases, while PRPH2 knockdown had opposite effects. Inhibitors of the Hippo pathway abrogated PRPH2 knockdown-induced laryngeal cancer cell invasion and anoikis inhibition. DISCUSSION: These results suggested that PRPH2 suppresses laryngeal cancer cell invasion and anoikis inhibition by activating Hippo signalling. PRPH2 may serve as a potential therapeutic target for laryngeal cancer in the future.

14.
Rev. bras. med. esporte ; 28(5): 497-500, Set.-Oct. 2022. tab, graf
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1376662

RESUMO

ABSTRACT Introduction: Different loads and volumes in resistance training is the most effective way to muscle hypertrophy stimulation in rehabilitation. Adding different stability planes to balance training will increase the intensity of muscle activation, causing an enhanced exercise load. It is theorized that unstable stimuli in the support environment increased central excitability, improving the ability to mobilize muscle fiber contraction. However, the intensity of this relationship is not clarified. Objective: Investigate how to balance exercise training improves CORE muscle plasticity and the central nervous system. Methods: A total of 36 undergraduate and graduate students were recruited to participate in this experiment. Two movements with bridge exercise were selected for maximal muscle endurance testing. Electromyographic data of the CORE muscles were captured and compared at all execution phases. Results: There was no interaction between the stabilization plane and cognitive tasks. The main effects of the low bridge and high bridge movements on erector spinae muscle activation were 28.88 and 2.06. The main effects of cognitive tasks were 0.33 and 7.88, and the interaction effect was 0.89 0.31. Conclusion: Exercise training can increase capillaries in muscles, increase the cross-sectional area of myofibrils, change the proportion of different types of myofibrils, and increase muscle strength. Evidence Level II; Therapeutic Studies - Investigating the results.


RESUMO Introdução: O treinamento de resistência com diferentes cargas e volumes é a maneira mais eficaz de estimular a hipertrofia muscular na reabilitação. Adicionar diferentes planos de estabilidade ao treinamento equilíbrio aumentará o grau de ativação muscular, causando um aumento na carga de exercícios. Teoriza-se que estímulos instáveis no ambiente de suporte levam ao aumento da excitabilidade central, melhorando a capacidade de mobilizar a contração das fibras musculares. Porém, ainda não sabemos a intensidade dessa relação. Objetivo: Investigar como o treinamento de exercícios com equilíbrio melhora a plasticidade muscular do CORE e o sistema nervoso central. Métodos: Um total de 36 graduandos e pós-graduandos foram recrutados para participar deste experimento. Dois movimentos com exercício ponte foram selecionados para o teste de máxima resistência muscular. Os dados eletromiográficos da musculatura do CORE foram capturados e comparados em todas as fases de execução. Resultados: Não houve interação entre o plano de estabilização e as tarefas cognitivas. Os principais efeitos dos movimentos de ponte baixa e ponte alta na ativação do músculo eretor da espinha foram 28,88 e 2,06, os principais efeitos das tarefas cognitivas foram 0,33 e 7,88, e o efeito de interação foi 0,89 e 0,31. Conclusão: O treinamento de exercícios pode aumentar os capilares nos músculos, aumentar a área transversal das miofibrilas, alterar a proporção de diferentes tipos de miofibrilas e aumentar a força muscular. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.


RESUMEN Introducción: El entrenamiento de resistencia con diferentes cargas y volúmenes es la forma más eficaz de estimular la hipertrofia muscular en la rehabilitación. Añadir diferentes planos de estabilidad al entrenamiento de equilibrio aumentará el grado de activación muscular, provocando un aumento de la carga del ejercicio. Se teoriza que los estímulos inestables en el entorno de apoyo conducen a un aumento de la excitabilidad central, mejorando la capacidad de movilizar la contracción de las fibras musculares. Sin embargo, aún no conocemos la intensidad de esta relación. Objetivo: Investigar cómo el entrenamiento de ejercicios de equilibrio mejora la plasticidad muscular del CORE y del sistema nervioso central. Métodos: Se reclutó a un total de 36 estudiantes de grado y posgrado para participar en este experimento. Se seleccionaron dos movimientos con ejercicio de puente para la prueba de resistencia muscular máxima. Se capturaron los datos electromiográficos de los músculos del CORE y se compararon en todas las fases de la ejecución. Resultados: No hubo interacción entre el plano de estabilización y las tareas cognitivas. Los efectos principales de los movimientos de puente bajo y puente alto sobre la activación de los músculos erectores de la columna vertebral fueron de 28,88 y 2,06, los efectos principales de las tareas cognitivas fueron de 0,33 y 7,88, y el efecto de interacción fue de 0,89 y 0,31. Conclusión: El entrenamiento con ejercicios puede aumentar los capilares en los músculos, incrementar el área transversal de las miofibrillas, cambiar la proporción de los diferentes tipos de miofibrillas y aumentar la fuerza muscular. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

15.
Sci Rep ; 6: 37579, 2016 11 29.
Artigo em Inglês | MEDLINE | ID: mdl-27897232

RESUMO

Understanding the adsorption mechanisms of CO2 and N2 in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO2 and N2 in K-illite with varying pore sizes at the temperature of 333, 363 and 393 K over a broad range of pressures up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and pore wall thickness. The simulation results of the excess adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing excess adsorption amount with the increase of pore size at low pressure, and a reverse trend at high pressure. The excess adsorption amount increases with increasing pressure to a maximum and then decreases with further increase in the pressure, and the decreasing amount is found to increase with the increasing pore size. For pores with size greater larger than 2 nm, the overlap effect disappears.

16.
ACS Appl Mater Interfaces ; 7(45): 25402-12, 2015 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-26517280

RESUMO

Metal-organic frameworks (MOFs) with constricted pores can increase the adsorbate density of gas and facilitate effective CO2 separation from flue gas or natural gas due to their enhanced overlapping of potential fields of the pores. Herein, an MOF with constricted pores, which was formed by narrow channels and blocks of functional groups, was fabricated from the assembly of a methyl-functionalized ligand and Zn(II) centers (termed NPC-7-Zn). Structural analysis of the as-synthesized NPC-7-Zn reveals a series of zigzag pores with pore diameters of ∼0.7 nm, which could be favorable for CO2 traps. For reinforcing the framework stability, a solvothermal metal metathesis on the pristine MOF NPC-7-Zn was performed, and a new Cu(II) MOF (termed NPC-7-Cu) with an identical framework was produced. The influence of the reaction temperatures on the metal metathesis process was investigated. The results show that the constricted pores in NPC-7-Zn can induce kinetic issues that largely slow the metal metathesis process at room temperature. However, this kinetic issue can be solved by applying higher reaction temperatures. The modified MOF NPC-7-Cu exhibits significant improvements in framework stability and thus leads to a permanent porosity for this framework. The constricted pore structure enables enhanced potential fields for these pores, rendering this MOF with high adsorbate densities for CO2 and high adsorption selectivity for a CO2/N2 gas mixture. The adsorption kinetic studies reveal that CH4 has a faster diffusion rate constant than CO2, showing a surface diffusion controlled mechanism for CO2 and CH4 adsorption.

17.
Artigo em Zh | MEDLINE | ID: mdl-18533561

RESUMO

OBJECTIVE: The utility of virtual endoscopy is compared to fiberoptic endoscopy and was also investigated with respect to accuracy of diagnosis and reproduction of images in patients with obstructive sleep apnea hypopnea syndrome (OSAHS). METHOD: Twenty-one patients with OSAHS were examined by helical spiral CT axial images and fiberoptic endoscopy. The helical spiral CT axial data was reconstructed using a VE software program. The results were compared to the fiberoptic endoscopic findings done by the otolaryngologists. All the patients were examined both in the sleeping and nonsleeping status. The dimensions of soft palate, uvula, lingua and epiglottis region were evaluated. RESULT: The results both in the virtual endoscopy evaluation and fiberoptic endoscopy was statistically significant difference in all of region. In the palate region, there was statistically significant difference in the left-and-right dimension, but no difference in the fore-and-aft dimension both in the sleeping and nonsleeping status. CONCLUSION: The dimensions of upper airway were more difference between in the sleeping and nonsleeping status. The change of dimension was more in the left-and-right; the fiberoptic endoscopy has more diagnostic significance in evaluation of dynamic movement of the upper airway; virtual endoscopy evaluation of the upper airway was accurate in assessing stenosis width and length; virtual endoscopy added more information about anatomic structure and pathological change of the upper airway.


Assuntos
Endoscopia/métodos , Apneia Obstrutiva do Sono/diagnóstico por imagem , Apneia Obstrutiva do Sono/diagnóstico , Adulto , Feminino , Humanos , Laringoscopia , Masculino , Pessoa de Meia-Idade , Tomografia Computadorizada Espiral , Tomografia Computadorizada por Raios X
18.
Lin Chuang Er Bi Yan Hou Ke Za Zhi ; 20(10): 449-50, 453, 2006 May.
Artigo em Zh | MEDLINE | ID: mdl-16883790

RESUMO

OBJECTIVE: To study the relationship between otitis media of effusion (OME) and allergy by investigating eosinophil cationic protein in middle ear effusion ( MECP), middle ear effusion IgE (MIgE) and serum eosinophil cationic protein (SECP). METHOD: The specimens drawn from 31 patients of OME were tested with Uni-CAP-100 allergic antigen testing system for the MECP, IgE and SECP. The results then were analyzed by statistical methods. RESULT: MECP were found in all the effusion specimens of 31 patients, the average concentration of which was 56.88 microg/L. The MECP concentration level in nine specimens (28.1%) was significantly elevated. The average concentration of MIgE was 27.2 ku/L. The MIgE concentration level in three specimens (9.7%) was remarkably increased. There was a positive correlation between the MECP level and the MIgE level( P <0.05). The average concentration of SECP was 5.6 microg/L. CONCLUSION: ECP exists in the middle ear effusion of OME. OME is an allergic inflammatory process more localized in middle ear itself in some patients. There may be a complicated allergic mechanism in OME.


Assuntos
Proteínas Granulares de Eosinófilos/metabolismo , Imunoglobulina E/metabolismo , Otite Média com Derrame/metabolismo , Adolescente , Adulto , Idoso , Orelha Média/metabolismo , Proteínas Granulares de Eosinófilos/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA