Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Más filtros










Base de datos
Intervalo de año de publicación
1.
Ther Adv Respir Dis ; 17: 17534666231212307, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38049958

RESUMEN

BACKGROUND: Little is known about immediate responses of blood perfusion to the balloon pulmonary angioplasty (BPA) procedure. OBJECTIVES: To investigate the changes in pulmonary perfusion of balloon-dilated vessels and untreated vessels with before, immediately after a single BPA and at follow-up. DESIGN: Retrospective single-center cohort study. METHODS: Patients who had chronic thromboembolic pulmonary hypertension (CTEPH) and completed the pulmonary perfusion single photon emission computed tomography (SPECT) imaging before, immediately after BPA and at follow-up were included. We evaluated the perfusion defects of both-lung, BPA target (balloon dilated) and non-target (untreated) vessel segments according to Begic 3-point scale in each lung segment. RESULTS: Forty patients (40 BPA procedures) were included and were given next BPA after 89 (62-125) days. The hemodynamic parameters including mPAP, PVR, and RAP were significantly improved after a single BPA. Visual scoring results of pulmonary perfusion imaging in 40 BPAs showed the perfusion defect scores of target vessels reduced from 5.6 ± 2.6 to 4.2 ± 2.2 (p < 0.001) immediately after BPA, and then further diminished to 3.1 ± 1.9 (p < 0.001) at follow-up. While in the non-target vessels, the post-BPA perfusion defect scores did not change significantly (13.4 ± 4.7 versus 12.8 ± 4.6, p = 0.182), but tended to decrease at follow-up (12.2 ± 4.2). However, there were 17 BPAs of which the post-BPA perfusion defect scores of non-target vessels increased significantly (p < 0.001), but decreased at follow-up. CONCLUSION: In addition to improving the blood perfusion of target vessels, BPA also has a certain effect on the perfusion of some non-target vessels.


Asunto(s)
Angioplastia de Balón , Hipertensión Pulmonar , Embolia Pulmonar , Humanos , Hipertensión Pulmonar/diagnóstico por imagen , Hipertensión Pulmonar/etiología , Hipertensión Pulmonar/terapia , Embolia Pulmonar/diagnóstico por imagen , Embolia Pulmonar/terapia , Estudios Retrospectivos , Estudios de Cohortes , Enfermedad Crónica , Pulmón/diagnóstico por imagen , Angioplastia de Balón/efectos adversos , Angioplastia de Balón/métodos , Perfusión , Arteria Pulmonar/diagnóstico por imagen
2.
Artículo en Inglés | MEDLINE | ID: mdl-37883525

RESUMEN

Due to its high energy density, high-voltage LiCoO2 is the preferred cathode material for consumer electronic products. However, its commercial viability is hindered by rapid capacity decay resulting from structural degradation and surface passivation during cycling at 4.6 V. The key to achieving stable cycling of LiCoO2 at high voltages lies in constructing a highly stable interface to mitigate surface side reactions. In this study, we present a facile in situ coating strategy that is amenable to mass production through a simple wet-mixing process, followed by high-temperature calcination. By capitalizing on the facile dispersion characteristics of nano-TiO2 in ethanol and the ethanol dissolubility of LiPO2F2, we construct a uniform precoating layer on LiCoO2 with nano-TiO2 and LiPO2F2. The subsequent thermal treatment triggers an in situ reaction between the coating reagents and LiCoO2, yielding a uniform composite coating layer. This composite layer comprises spinel-structured compounds (e.g., LiCoTiO4) and Li3PO4, which exhibit excellent chemical and structural stability under high-voltage conditions. The uniform and stable coating layer effectively prevents direct contact between LiCoO2 and the electrolyte, thereby reducing side reactions and suppressing the surface passivation of LiCoO2 particles. As a result, coated LiCoO2 maintains favorable electronic and ionic conductivity even after prolonged cycling. The synergistic effects of spinel-structured compounds and Li3PO4 contribute to the superior performance of LiCoO2, demonstrating a high capacity of 202.1 mA h g-1 (3.0-4.6 V, 0.5 C, 1 C = 274 mA g-1), with a capacity retention rate of 96.7% after 100 cycles.

3.
ACS Appl Mater Interfaces ; 15(4): 5326-5335, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36690409

RESUMEN

The ever-growing demand for portable electronic devices has put forward higher requirements on the energy density of layered LiCoO2 (LCO). The unstable surface structure and side reactions with electrolytes at high voltages (>4.5 V) however hinder its practical applications. Here, considering the high-voltage stability and three-dimensional lithium-ion transport channel of the high-voltage Li-containing spinel (M = Ni and Co) LiMxMn2-xO4, we design a conformal and integral LiNixCoyMn2-x-yO4 spinel coating on the surface of LCO via a sol-gel method. The accurate structure of the coating layer is identified to be a spinel solid solution with gradient element distribution, which compactly covers the LCO particle. The coated LCO exhibits significantly improved cycle performance (86% capacity remained after 100 cycles at 0.5C in 3-4.6 V) and rate performance (150 mAh/g at a high rate of 5C). The characterizations of the electrodes from the bulk to surface suggest that the conformal spinel coating acts as a physical barrier to inhibit the side reactions and stabilize the cathode-electrolyte interface (CEI). In addition, the artificially designed spinel coating layer is well preserved on the surface of LCO after prolonged cycling, preventing the formation of an electrochemically inert Co3O4 phase and ensuring fast lithium transport kinetics. This work provides a facile and effective method for solving the surface problems of LCO operated at high voltages.

4.
Adv Mater ; 34(19): e2200655, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35297509

RESUMEN

Battery safety concerns are becoming more and more prominent with the increasing demands of lithium-ion batteries (LIBs) with higher energy density. The greatest threat to battery safety derives from the easy release of oxygen from the high-capacity layered oxide cathodes at highly delithiated states and subsequent exothermic reactions with reductive agents in batteries. Herein, it is demonstrated that solid electrolyte Li6.5 La3 Zr1.5 Ta0.5 O12 (LLZTO) can supply lithium ions to re-lithiate the charged LiCoO2 at elevated temperatures. Such a re-lithiation process can lower the state-of-charge of LiCoO2 , and thus, inherently postpones its structural decomposition and the associated release of oxygen during the heating process. The LiCoO2 /graphite full cell with 1 wt% addition of LLZTO demonstrates remarkably enhanced safety performances. This work proposes a strategy that through the adoption of solid electrolytes to solve safety issues raised from both flammable liquid electrolytes and high capacity cathodes, to achieve intrinsically safe LIBs or solid-state batteries.

5.
Mol Imaging Biol ; 24(2): 309-320, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-34816283

RESUMEN

PURPOSE: The purpose of this study was to compare the primary staging of F-18 labeled fibroblast activation protein inhibitor ([18F]F-FAPI) with that of F-18 labeled fluordesoxyglucose positron emission tomography/computed tomography ([18F]F-FDG PET/CT) in patients with lung adenocarcinoma (LAD). PROCEDURES: We prospectively analyzed the images of LAD patients who underwent [18F]F-FAPI and [18F]F-FDG PET/CT between May 2020 and August 2021. [18F]F-FAPI and [18F]F-FDG uptakes were compared using the paired samples t test, and lesion numbers were compared using the Wilcoxon signed-rank test. RESULTS: Thirty-four LAD patients were evaluated. Patients showed high [18F]F-FAPI uptake in primary lesions (SUVmax 12.54 ± 3.77). Both [18F]F-FAPI and [18F]F-FDG had 100% detection rates for primary tumors. However, [18F]F-FAPI showed higher SUVmax than [18F]F-FDG in lesions of the lymph nodes, pleura, bones, and other tissues (all P ≤ 0.05). Although the absolute uptake values of [18F]F-FAPI in brain lesions were lower than those of [18F]F-FDG (1.56 ± 2.19 vs.7.34 ± 3.54, P < 0.0001), the tumor-to-background (T/B) ratios were significantly higher than those of [18F]F-FDG (9.53 ± 12.07 vs.1.01 ± 0.49, P < 0.0001). Generally, [18F]F-FAPI PET/CT could visualize more total lesions than [18F]F-FDG (554 vs.464, P = 0.003), especially in lymph nodes (258 vs.229, P = 0.039), the brain (34 vs.9, P = 0.002), and pleura (56 vs.30, P = 0.041). However, contrast-enhanced brain magnetic-resonance imaging (MRI) showed more brain lesions than [18F]F-FAPI PET/CT (56 vs.34, P = 0.002). Compared with the [18F]F-FDG-based TNM stage, the [18F]F-FAPI-based TNM stage was upgraded in six patients (17.6%). CONCLUSIONS: [18F]F-FAPI PET/CT showed a very high detection rate for primary LAD. In addition, 18F-FAPI PET/CT demonstrated clearer tumor delineation and more lesions than [18F]F-FDG PET/CT, especially in lymph nodes, the brain, and pleura. Therefore, [18F]F-FAPI had an advantage over [18F]F-FDG for primary staging of LAD. However, brain MRI could identify more and smaller lesions than [18F]F-FAPI PET/CT.


Asunto(s)
Adenocarcinoma del Pulmón , Neoplasias Pulmonares , Adenocarcinoma del Pulmón/diagnóstico por imagen , Fibroblastos , Fluorodesoxiglucosa F18 , Radioisótopos de Galio , Humanos , Neoplasias Pulmonares/diagnóstico por imagen , Tomografía Computarizada por Tomografía de Emisión de Positrones , Estudios Prospectivos
6.
J Am Chem Soc ; 141(46): 18630-18640, 2019 11 20.
Artículo en Inglés | MEDLINE | ID: mdl-31674779

RESUMEN

Cleavage of carbon-carbon bonds has been found in some important industrial processes, for example, petroleum cracking, and has inspired development of numerous synthetic methods. However, nonpolar unstrained C(aryl)-C(aryl) bonds remain one of the toughest bonds to be activated. As a detailed study of a fundamental reaction mode, here a full story is described about our development of a Ru-catalyzed reductive cleavage of unstrained C(aryl)-C(aryl) bonds. A wide range of biaryl compounds that contain directing groups (DGs) at 2,2' positions can serve as effective substrates. Various heterocycles, such as pyridine, quinoline, pyrimidine, and pyrazole, can be employed as DGs. Besides hydrogen gas, other reagents, such as Hantzsch ester, silanes, and alcohols, can be employed as terminal reductants. The reaction is pH neutral and free of oxidants; thus a number of functional groups are tolerated. Notably, a one-pot C-C activation/C-C coupling has been realized. Computational and experimental mechanistic studies indicate that the reaction involves a ruthenium(II) monohydride-mediated C(aryl)-C(aryl) activation and the resting state of the catalyst is a η4-coordinated ruthenium(II) dichloride complex, which could inspire development of other transformations based on this reaction mode.


Asunto(s)
Hidrocarburos Aromáticos/química , Rutenio/química , Catálisis , Teoría Funcional de la Densidad , Modelos Moleculares , Oxidación-Reducción
7.
ACS Catal ; 8(2): 845-849, 2018 Feb 02.
Artículo en Inglés | MEDLINE | ID: mdl-29868245

RESUMEN

A Co(0)-catalyzed intramolecular alkyne/benzocyclobutenone coupling through C-C cleavage of benzocyclobutenones is described. Co2(CO)8/P[3, 5-(CF3)2C6H3]3 was discovered to be an effective metal/ligand combination, which exhibits complementary catalytic activity to the previously established rhodium catalyst. In particular, the C8-substituted substrates failed in the Rh system, but succeeded with the Co catalysis. Experimental and computational studies show that the initially formed tetrahedral dicobalt-alkyne complex undergoes C1-C2 activation via oxidative addition with Co(0), followed by migratory insertion and reductive elimination to give the ß-naphthol products.

8.
ACS Catal ; 7(2): 1340-1360, 2017 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-29062586

RESUMEN

The transition metal-catalyzed "cut and sew" transformation has recently emerged as a useful strategy for preparing complex molecular structures. After oxidative addition of a transition metal into a carbon-carbon bond, the resulting two carbon termini can be both functionalized in one step via the following migratory insertion and reductive elimination with unsaturated units, such as alkenes, alkynes, allenes, CO and polar multiple bonds. Three- or four-membered rings are often employed as reaction partners due to their high ring strains. The participation of non-strained structures generally relies on cleavage of a polar carbon-CN bond or assistance of a directing group.

9.
Org Lett ; 19(13): 3446-3449, 2017 07 07.
Artículo en Inglés | MEDLINE | ID: mdl-28616988

RESUMEN

A highly diastereoselective α-arylation of cyclic nitriles has been developed via a Negishi cross-coupling of commercially available aryl, heteroaryl, and alkenyl halides with cyclobutyl nitriles in the presence of tetramethylpiperidinylzinc chloride lithium chloride (TMPZnCl•LiCl) and catalytic XPhos-Pd-G2. A variety of electronically diverse electrophiles were well tolerated, and this chemistry was further advanced with application of both cyclopropyl and cyclopentyl nitriles.

10.
ACS Catal ; 6(2): 969-973, 2016 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-27699088

RESUMEN

The first decarbonylative cycloaddition of less-strained cyclic ketones (isatins) with isocyanates is reported. Initiated by C-C activation, this distinct [5-2+2] transformation provides a rapid entry to access various benzimidazolidinone derivatives, through which a wide range of isocyanates can be efficiently coupled with broad functional group tolerance. A modified one-pot process, combining Curtius rearrangement and C-C activation, was also achieved by using acyl azides as the starting materials. Detailed mechanistic study revealed a surprising double-decarbonylative reaction pathway. The novel reactivity discovered in this basic research is expected to shed light on developing new heterocycle formation methods through a C-C/isocyanate coupling.

11.
Chemistry ; 22(51): 18290-18315, 2016 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-27620805

RESUMEN

Cyclobutenones, four-membered ketones bearing an unsaturated carbon-carbon double bond, and their structural sibling benzocyclobutenones, possess unique reactivity. Owing to their inherent high ring strain, such structures readily undergo ring opening under a variety of conditions, including thermolysis, photolysis, and transition metal catalysis, to afford reactive intermediates that can be trapped with nucleophiles, dienophiles, and unsaturated bonds. Their electron-deficient enone moieties are good electrophiles for facile nucleophilic addition. Such properties render cyclobutenones versatile synthons, serving as excellent coupling partners in a vast array of synthetically valuable transformations.

12.
Chem Sci ; 6(10): 5440-5445, 2015 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-28042458

RESUMEN

Here we report a reagent-free rhodium-catalyzed ring-expansion reaction via C-C cleavage of cyclobutenones. A variety of poly-substituted cyclopentenones and 1-indanones can be synthesized from simple cyclobutenones and benzocyclobutenones. The reaction condition is near pH neutral without additional oxidants or reductants. The potential for developing a dynamic kinetic asymmetric transformation of this reaction has also been demonstrated. Further study supports the proposed pathway involving Rh-insertion into the cyclobutenone C-C bond, followed by ß-hydrogen elimination, olefin insertion and reductive elimination.

13.
Tetrahedron ; 70(27-28): 4135-4146, 2014 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-24926108

RESUMEN

A concise approach to access functionalized benzocyclobutenones from 3-halophenol derivatives is described. This modified synthesis employs a [2+2] cycloaddition between benzynes generated from dehydrohalogenation of aryl halides using LiTMP and acetaldehyde enolate generated from n-BuLi and THF, followed by oxidation of the benzocyclobutenol intermediates to provide benzocyclobutenones. The [2+2] reaction can be run on a 10-gram scale with an increased yield. A number of functional groups including alkenes and alkynes are tolerated. Coupling of benzynes with ketene silyl acetals to give 8-substituted benzocyclobutenones is also demonstrated.

14.
Angew Chem Int Ed Engl ; 53(6): 1674-8, 2014 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-24492973

RESUMEN

A tunable rhodium-catalyzed intramolecular alkyne insertion reaction proceeding through the CC cleavage of benzocyclobutenones is described. Selective formation of either the direct or decarbonylative insertion product can be controlled by using different catalytic systems. A variety of fused ß-naphthol and indene scaffolds were obtained in good yields with high functional group tolerance. This work illustrates a divergent approach to synthesize fused-ring systems by CC activation/functionalization.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...