Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
BMC Gastroenterol ; 24(1): 98, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38438982

RESUMO

BACKGROUND AND AIM: The optimal management strategy for early gastric cancer (EGC) a topic of contention. This study aims to compare the prognostic outcomes of endoscopic submucosal dissection (ESD) and surgical treatment in patients diagnosed with EGC. METHODS: In thisretrospective cohort study, we analyzed data from539 patients diagnosed with EGC between January 2012 and December 2020 from two centers. We compared Clinicopathological features, procedure-related complications, recurrence rate, overall survival, and disease specific survival between the 262 patients who underwent ESD and the 277 patients who underwent surgical treatment. ESD procedures were conducted using a dual knife by experienced endoscopists, while surgical treatments included laparoscopic or open gastrectomy. Regular ollow-up examinations were conducted post-treatment. RESULTS: The two groups exhibited comparable baseline characteristics. Multivariable Cox regression analysis identified vascular invasion as a risk factor for worse recurrence-free survival (RFS), and overall survival (OS) in patients with early gastric cancer. The ESD group experienced fewer overall postoperative complications compared to the surgical treatment group. Kaplan-Meier curves demonstrated no significant differences in recurrence rate or overall survival between the two groups. CONCLUSIONS: Both ESD and surgical treatment emerged as safe and effective approaches for managing EGC. The choice of treatment should be tailored to individual patient factors. ESD can be considered an alternative treatment option for selected patients who are not suitable candidates for surgery. Further studies are warranted to determine the long-term outcomes of ESD and surgical treatment for EGC.


Assuntos
Ressecção Endoscópica de Mucosa , Neoplasias Gástricas , Humanos , Prognóstico , Estudos de Coortes , Ressecção Endoscópica de Mucosa/efeitos adversos , Estudos Retrospectivos , Neoplasias Gástricas/cirurgia
2.
Biomimetics (Basel) ; 8(5)2023 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-37754188

RESUMO

This work designed a free-flying space robot (FFSR) that simulates the on-orbit assembly of large space telescopes, drawing inspiration from the flexible movement of water striders on water surfaces. Initially, we developed the system structure of the robot, including the corresponding air-floating ground simulation system. This system enables floating movement of the robot in a gravity-free environment through the utilization of planar air bearings. Subsequently, we established the kinematics and dynamics models for the FFSR. Following that, we propose a novel adaptive boundary layer fuzzy sliding mode control (ABLFSMC) method to achieve trajectory tracking control of the FFSR. The virtual angle and angular velocity are formulated to serve as references for the angle and angular velocity in the body coordinate system. Furthermore, a fuzzy logic system is employed to minimize the chattering effect of the sliding mode control. The global stability of the proposed controller is guaranteed through the Lyapunov stability theory. Finally, we validate the effectiveness of the proposed control method as well as the high trajectory tracking accuracy of the developed FFSR through simulation and experimental results, respectively. Overall, our findings present a crucial experimental platform and development opportunity for the ground-based validation of technologies concerning the on-orbit assembly of large space telescopes.

3.
Artigo em Inglês | MEDLINE | ID: mdl-37028093

RESUMO

This study investigates a force-controlled auxiliary device for freehand ultrasound (US) examinations. The designed device allows sonographers to maintain a steady target pressure on the US probe, thereby improving the US image quality and reproducibility. The use of a screw motor to power the device and a Raspberry Pi as the system controller results in a lightweight and portable device, while a screen enhances user-interactivity. Using gravity compensation, error compensation, an adaptive proportional-integral-derivative algorithm, and low-pass signal filtering, the designed device provides highly accurate force control. Several experiments using the developed device, including clinical trials relating to the jugular and superficial femoral veins, validate its utility in ensuring the desired pressure in response to varying environments and prolonged US examinations, enabling low or high pressures to be maintained and lowering the threshold of clinical experience. Moreover, the experimental results show that the designed device effectively relieves the stress on the sonographer's hand joints during US examinations and enables rapid assessment of the tissue elasticity characteristics. With automatic pressure tracking between probe and patient, the proposed device offers potentially significant benefits for the reproducibility and stability of US images and the health of sonographers.


Assuntos
Fenômenos Mecânicos , Humanos , Reprodutibilidade dos Testes , Ultrassonografia/métodos
4.
Artigo em Inglês | MEDLINE | ID: mdl-35675230

RESUMO

This study presents a portable device that ensures precise contact force between a subject and a probe to improve the stability and reproducibility of ultrasound (US) acquisition. The mechanical portion of the device includes a servo motor, gears, and a ball screw linear actuator; two photoelectric switches are used to limit the stroke. A combined force and position control system is developed, and a pressure threshold is introduced to reduce the chattering of the system so that it can be applied to US examinations of tissues of different stiffness levels. Force control experiments were conducted on the device, and the results showed that the device can overcome the chattering of a physician's hand and movement caused by a subject's respiration. Additionally, the stability of the US acquisition was substantially improved. Based on clinical trials on humans, this device was observed to improve the consistency of ultrasonic results and the repeatability of images, and it assisted sonographers with maintaining suitable contact force and improving imaging quality. The device can either be handheld by a physician or easily integrated with a manipulator as an autonomous robotic US acquisition device, thereby validating its potential for US applications.


Assuntos
Fenômenos Mecânicos , Robótica , Humanos , Reprodutibilidade dos Testes , Ultrassonografia , Movimento
5.
Nanomicro Lett ; 14(1): 209, 2022 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-36315297

RESUMO

A rational regulation of the solar water splitting reaction pathway by adjusting the surface composition and phase structure of catalysts is a substantial approach to ameliorate the sluggish reaction kinetics and improve the energy conversion efficiency. In this study, we demonstrate a nanocrystalline iron pyrophosphate (Fe4(P2O7)3, FePy)-regulated hybrid overlayer with amorphous iron phosphate (FePO4, FePi) on the surface of metal oxide nanostructure with boosted photoelectrochemical (PEC) water oxidation. By manipulating the facile electrochemical surface treatment followed by the phosphating process, nanocrystalline FePy is localized in the FePi amorphous overlayer to form a heterogeneous hybrid structure. The FePy-regulated hybrid overlayer (FePy@FePi) results in significantly enhanced PEC performance with long-term durability. Compared with the homogeneous FePi amorphous overlayer, FePy@FePi can improve the charge transfer efficiency more significantly, from 60% of FePi to 79% of FePy@FePi. Our density-functional theory calculations reveal that the coexistence of FePi and FePy phases on the surface of metal oxide results in much better oxygen evolution reaction kinetics, where the FePi was found to have a typical down-hill reaction for the conversion from OH* to O2, while FePy has a low free energy for the formation of OH*.

6.
J Hazard Mater ; 408: 124900, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33383456

RESUMO

Environmentally friendly ammonia (NH3) decomposition has attracted a lot of interests in recent years to resolve the issue of water eutrophication from a wastewater and achieve a clean H2 storage. Here, we report a novel strategy for solar-driven ammonia decomposition by introducing a highly-activated iron phosphate (FePi) over-layer on the surface of α-Fe2O3 nanorods photoanode (FePi/Fe2O3), and innovatively propose a photoelectrochemical (PEC) ammonia degradation system with enhanced performance. After a facile electrochemical (EC) activation, the FePi over-layer is converted into FeOOH. The EC-activated over-layer provides the efficient active sites for the ammonia adsorption process, which promotes the high catalytic kinetics for ammonia oxidation reaction (AOR). Due to the synergistic effect of the electrocatalytic and the photocatalytic process, the FePi/Fe2O3 exhibits the enhanced PEC AOR performance, which competes with water oxidation reaction (WOR). Comparing to the initial concentration of ammonia, the FePi/Fe2O3 achieves a 54.4% ammonia degradation rate within 3 h at 1.23 V vs. reversible hydrogen electrode (RHE) under 1 sun illumination, which demonstrates the reliable ammonia decomposition performance. This study confirms that it is feasible to achieve PEC ammonia decomposition in an aqueous solution without chloride mediators and provides a promising strategy for the harmless treatment of ammonia wastewater.

7.
Polymers (Basel) ; 12(8)2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32785176

RESUMO

In this study, a solution-processable compact vanadium oxide (V2O5) film with a globular nanoparticulate structure is introduced to the hole transport layer (HTL) of polymer bulk-heterojunction based solar cells comprised of PTB7:PC70BM by using a facile metal-organic decomposition method to replace the conventionally utilized poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). For this, a biocompatible structure-determining agent, polyethylene glycol (PEG, Mn 300), is used as an additive in the precursor to form the nanoparticulate compact V2O5 (hereafter referred to as NP-V2O5) film, which possesses an outstandingly smooth surface morphology. The introduction of NP-V2O5 HTL via the solution process with a neutral pH condition successfully improved the stability by preventing the decomposition of indium tin oxide (ITO) glass and the penetration of heavy-metal components and moisture, which are considered as the crucial drawbacks of using PEDOT:PSS. Over 1440 h (60 days) of the stability test, an organic solar cell (OSC) with NP-V2O5 showed a significant durability, maintaining 82% of its initial power conversion efficiency (PCE), whereas an OSC with PEDOT:PSS maintained 51% of its initial PCE. Furthermore, due to the positive effects of the modified surface properties of NP-V2O5, the PCE was slightly enhanced from 7.47% to 7.89% with a significant improvement in the short-circuit current density and fill factor.

8.
Nanoscale Res Lett ; 14(1): 163, 2019 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-31089900

RESUMO

Wafer-scale, conformal, two-dimensional (2D) TiO2-Ga2O3 n-p heterostructures with a thickness of less than 10 nm were fabricated on the Si/SiO2 substrates by the atomic layer deposition (ALD) technique for the first time with subsequent post-deposition annealing at a temperature of 250 °C. The best deposition parameters were established. The structure and morphology of 2D TiO2-Ga2O3 n-p heterostructures were characterized by the scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), etc. 2D TiO2-Ga2O3 n-p heterostructures demonstrated efficient photocatalytic activity towards methyl orange (MO) degradation at the UV light (λ = 254 nm) irradiation. The improvement of TiO2-Ga2O3 n-p heterostructure capabilities is due to the development of the defects on Ga2O3-TiO2 interface, which were able to trap electrons faster.

9.
Nanoscale Res Lett ; 14(1): 173, 2019 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-31134408

RESUMO

Please be advised that the name of one of the coauthors in the original article [1] has been incorrectly spelled: 'Ranish M. Ramachandran' should be 'Ranjith K. Ramachandran'.

10.
Nanoscale Res Lett ; 13(1): 195, 2018 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-29978416

RESUMO

In this work, p-Co3O4/n-ZnO heterostructures were fabricated on Ni substrate by hydrothermal-decomposition method using cobaltous nitrate hexahydrate (Co(NO3)2·6H2O) and zinc acetate dihydrate (Zn(CH3COO)2·2H2O) as precursors with zinc acetate concentration varying from 5.0 to 55.0 mM. Structure and morphology of the developed samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Effect of zinc acetate concentration on the photocatalytic activity of p-Co3O4/n-ZnO heterostructures was investigated by degradation of methyl orange (MO) under the UV light irradiation. The fabricated p-Co3O4/n-ZnO heterostructures exhibited higher photocatalytic activity than pure Co3O4 particles. In order to obtain the maximum photocatalytic activity, zinc acetate concentration was optimized. Specifically, at 35 mM of zinc acetate, the p-Co3O4/n-ZnO showed the highest photocatalytic activity with the degradation efficiency of MO reaching 89.38% after 72 h irradiation. The improvement of photocatalytic performance of p-Co3O4/n-ZnO heterostructures is due to the increased concentration of photo-generated holes on Co3O4 surface and the higher surface-to-volume ratio in the hierarchical structure formed by nano-lamellas.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA