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1.
Proc Natl Acad Sci U S A ; 119(11): e2112109119, 2022 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-35263231

RESUMEN

SignificanceDirect ethanol fuel cells are attracting growing attention as portable power sources due to their advantages such as higher mass-energy density than hydrogen and less toxicity than methanol. However, it is challenging to achieve the complete electrooxidation to generate 12 electrons per ethanol, resulting in a low fuel utilization efficiency. This manuscript reports the complete ethanol electrooxidation by engineering efficient catalysts via single-atom modification. The combined electrochemical measurements, in situ characterization, and density functional theory calculations unravel synergistic effects of single Rh atoms and Pt nanocubes and identify reaction pathways leading to the selective C-C bond cleavage to oxidize ethanol to CO2. This study provides a unique single-atom approach to tune the activity and selectivity toward complicated electrocatalytic reactions.

2.
Small ; 20(1): e2305289, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37649146

RESUMEN

Green fuel from water splitting is hardcore for future generations, and the limited source of fresh water (<1%) is a bottleneck. Seawater cannot be used directly as a feedstock in current electrolyzer techniques. Until now single atom catalysts were reported by many synthetic strategies using notorious chemicals and harsh conditions. A cobalt single-atom (CoSA) intruding cobalt oxide ultrasmall nanoparticle (Co3 O4 USNP)-intercalated porous carbon (PC) (CoSA-Co3 O4 @PC) electrocatalyst was synthesized from the waste orange peel as a single feedstock (solvent/template). The extended X-ray absorption fine structure spectroscopy (EXAFS) and theoretical fitting reveal a clear picture of the coordination environment of the CoSA sites (CoSA-Co3 O4 and CoSA-N4 in PC). To impede the direct seawater corrosion and chlorine evolution the seawater has been desalinated (Dseawater) with minimal cost and the obtained PC is used as an adsorbent in this process. CoSA-Co3 O4 @PC shows high oxygen evolution reaction (OER) activity in transitional metal impurity-free (TMIF) 1 M KOH and alkaline Dseawater. CoSA-Co3 O4 @PC exhibits mass activity that is 15 times higher than the commercial RuO2 . Theoretical interpretations suggest that the optimized CoSA sites in Co3 O4 USNPs reduce the energy barrier for alkaline water dissociation and simultaneously trigger an excellent OER followed by an adsorbate evolution mechanism (AEM).

3.
J Am Chem Soc ; 145(31): 16951-16965, 2023 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-37439128

RESUMEN

Hydrogen has been chosen as an environmentally benign energy source to replace fossil-fuel-based energy systems. Since hydrogen is difficult to store and transport in its gaseous phase, thermochemical liquid organic hydrogen carriers (LOHCs) have been developed as one of the alternative technologies. However, the high temperature and pressure requirements of thermochemical LOHC systems result in huge energy waste and impracticality. This Perspective proposes electrochemical (EC)-LOHCs capable of more efficient, safer, and lower temperature and pressure hydrogen storage/utilization. To enable this technology, several EC-LOHC candidates such as isopropanol, phenolic compounds, and organic acids are described, and the latest research trends and design concepts of related homo/hetero-based electrocatalysts are discussed. In addition, we propose efficient fuel-cell-based systems that implement electrochemical (de)hydrogenation of EC-LOHCs and present prospects for relevant technologies.

4.
World J Surg Oncol ; 21(1): 49, 2023 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-36804879

RESUMEN

BACKGROUND: Skin metastasis from papillary thyroid cancer (PTC) is a rare entity that can occur up to decades after treatment of the primary tumor. Here, we present a patient who developed skin metastasis 10 years after treatment of her primary tumor and describe the molecular findings of the metastatic lesion. CASE PRESENTATION: A 44-year-old female with a history of PTC who underwent a total thyroidectomy and radioactive iodine (RAI) treatment 10 years ago presented with a 1.3-cm skin lesion along the prior thyroidectomy scar. A biopsy revealed metastatic PTC, and the patient underwent surgical excision of the lesion. ThyroSeq molecular testing showed the copresence of BRAFV600E mutation and TERT promoter C228T mutation. The patient subsequently received one round of adjuvant RAI therapy. CONCLUSIONS: A high index of suspicion is warranted in patients with a history of PTC who develop a skin lesion, even several years after remission of the primary disease. In patients with high-risk mutations, such as BRAFV600E and TERT promoter C228T mutations, long-term surveillance of disease recurrence is particularly important.


Asunto(s)
Neoplasias Cutáneas , Telomerasa , Neoplasias de la Tiroides , Humanos , Femenino , Adulto , Cáncer Papilar Tiroideo/genética , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/cirugía , Neoplasias de la Tiroides/patología , Proteínas Proto-Oncogénicas B-raf/genética , Radioisótopos de Yodo , Regiones Promotoras Genéticas/genética , Recurrencia Local de Neoplasia/genética , Neoplasias Cutáneas/genética , Mutación , Telomerasa/genética
5.
Clin Endocrinol (Oxf) ; 97(1): 106-115, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35343605

RESUMEN

OBJECTIVE: Mutations in the telomerase reverse transcriptase (TERT) promoter have been reported as a convincing prognostic factor in papillary thyroid carcinomas (PTCs). We aimed to investigate the frequency of TERT promoter mutations in patients with thyroid cancer and identify the clinicopathological factors associated with them in PTCs. DESIGN: A total of 1086 consecutive cases of thyroid cancer composed of mostly PTCs were included in this study. TERT promoter and BRAF mutations were detected by pyrosequencing and their associations with clinicopathological features of tumour were analyzed. RESULTS: TERT promoter mutations were observed in 1.9% of PTCs, 6.7% of follicular thyroid carcinomas, 8.3% of Hurthle cell carcinomas and 25.0% of poorly differentiated thyroid carcinomas and in a single case of anaplastic thyroid carcinoma. In PTCs, aggressive clinicopathological features, higher stage and BRAF V600E mutation were all found to be associated with TERT promoter mutations. Distant metastasis and disease recurrence were more frequent in TERT promoter-mutated PTCs. In multivariate analysis, age ≥55 years, tall cell variant, mitoses ≥3/10 high-power fields, tumour necrosis, and gross extrathyroidal extension (ETE) were identified as independent factors associated with TERT promoter mutations in PTCs. CONCLUSIONS: This study revealed a relatively low frequency of TERT promoter mutations in Korean patients with PTC. Certain clinicopathological features including old age, tall cell variant, increased mitoses, tumour necrosis and gross ETE were found to be indicative of TERT promoter mutations in PTCs, suggesting that mutational analysis in a particular group of PTCs can be effective in regions with low mutation rates.


Asunto(s)
Carcinoma Papilar , Telomerasa , Neoplasias de la Tiroides , Carcinoma Papilar/genética , Humanos , Persona de Mediana Edad , Mutación , Necrosis , Recurrencia Local de Neoplasia , Proteínas Proto-Oncogénicas B-raf/genética , Telomerasa/genética , Cáncer Papilar Tiroideo/genética , Neoplasias de la Tiroides/genética , Neoplasias de la Tiroides/patología
6.
Angew Chem Int Ed Engl ; 60(19): 10942-10949, 2021 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-33751779

RESUMEN

Atomically ordered intermetallic nanoparticles exhibit improved catalytic activity and durability relative to random alloy counterparts. However, conventional methods with time-consuming and high-temperature syntheses only have rudimentary capability in controlling the structure of intermetallic nanoparticles, hindering advances of intermetallic nanocatalysts. We report a template-directed strategy for rapid synthesis of Pd-based (PdM, M=Pb, Sn and Cd) ultrathin porous intermetallic nanosheets (UPINs) with tunable sizes. This strategy uses preformed seeds, which act as the template to control the deposition of foreign atoms and the subsequent interatomic diffusion. Using the oxygen reduction reaction (ORR) as a model reaction, the as-synthesized Pd3 Pb UPINs exhibit superior activity, durability, and methanol tolerance. The favored geometrical structure and interatomic interaction between Pd and Pb in Pd3 Pb UPINs are concluded to account for the enhanced ORR performance.

7.
Small ; 16(49): e2005305, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33205618

RESUMEN

The electrochemical CO2 reduction reaction (CO2 RR) to syngas represents a promising solution to mitigate CO2 emissions and manufacture value-added chemicals. Palladium (Pd) has been identified as a potential candidate for syngas production via CO2 RR due to its transformation to Pd hydride under CO2 RR conditions, however, the pre-hydridized effect on the catalytic properties of Pd-based electrocatalysts has not been investigated. Herein, pre-hydridized Pd nanocubes (PdH0.40 ) supported on carbon black (PdH0.40 NCs/C) are directly prepared from a chemical reduction method. Compared with Pd nanocubes (Pd NCs/C), PdH0.40 NCs/C presented an enhanced CO2 RR performance due to its less cathodic phase transformation revealed by the in situ X-ray absorption spectroscopy. Density functional theory calculations revealed different binding energies of key reaction intermediates on PdH0.40 NCs/C and Pd NCs/C. Study of the size effect further suggests that NCs of smaller sizes show higher activity due to their more abundant active sites (edge and corner sites) for CO2 RR. The pre-hydridization and reduced NC size together lead to significantly improved activity and selectivity of CO2 RR.

8.
Sensors (Basel) ; 20(14)2020 Jul 18.
Artículo en Inglés | MEDLINE | ID: mdl-32708442

RESUMEN

Gait is a characteristic that has been utilized for identifying individuals. As human gait information is now able to be captured by several types of devices, many studies have proposed biometric identification methods using gait information. As research continues, the performance of this technology in terms of identification accuracy has been improved by gathering information from multi-modal sensors. However, in past studies, gait information was collected using ancillary devices while the identification accuracy was not high enough for biometric identification. In this study, we propose a deep learning-based biometric model to identify people by their gait information collected through a wearable device, namely an insole. The identification accuracy of the proposed model when utilizing multi-modal sensing is over 99%.


Asunto(s)
Identificación Biométrica , Aprendizaje Profundo , Análisis de la Marcha , Zapatos , Dispositivos Electrónicos Vestibles , Biometría , Humanos
9.
J Am Chem Soc ; 141(45): 18256-18263, 2019 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-31621315

RESUMEN

The free energy of H adsorption (ΔGH) on a metallic catalyst has been taken as a descriptor to predict the hydrogen evolution reaction (HER) kinetics but has not been well applied in alkaline media. To assess this, we prepare Pd@Pt and PdH@Pt core-shell octahedra enclosed by Pt(111) facets as model catalysts for controlling the ΔGH affected by the ligand, the strain, and their ensemble effects. The Pt shell thickness is adjusted from 1 to 5 atomic layers by varying the amount of Pt precursor added during synthesis. In an alkaline electrolyte, the HER activity of core-shell models is improved either by the construction of core-shell structures or by the increased number of Pt shells. These experimental results are in good agreement with the ΔGH values calculated by the first-principles density functional theory with a complex surface strained core-shell slab model. However, enhanced HER activities of Pd@Pt and PdH@Pt core-shell nanocrystals over the Pt catalyst are inconsistent with the thermodynamic ΔGH scaling relationship only but can be explained by the work function and apparent ΔGH models that predict the interfacial electric field for the HER.

10.
Chemistry ; 25(29): 7185-7190, 2019 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-30916839

RESUMEN

Controlling the morphology and composition of nanocatalysts constructed from metals and conductive polymers has attracted attention owing to their great potential for the development of high-efficiency catalysts for various catalytic applications. Herein, a facile synthetic approach for ultrathin-polyaniline-coated Pt-Ni nanooctahedra (Pt-Ni@PANI hybrids) with controllable PANI shell thicknesses is presented. Pt-Ni nanooctahedra/C catalysts enclosed by PANI shells with thicknesses from 0.6 to 2.4 nm were obtained by fine control over the amount of aniline. The various Pt-Ni@PANI hybrids exhibited electrocatalytic activity toward the methanol oxidation reaction that is highly dependent on the thickness of the PANI shell. Pt-Ni@PANI hybrids with the thinnest PANI shells (0.6 nm) showed markedly improved electrocatalytic performance for the methanol oxidation reaction compared with Pt-Ni@PANI hybrids with thicker PANI shells, Pt-Ni nanooctahedra/C, and commercial Pt/C due to synergistic benefits of ultrathin PANI shells and Pt-Ni alloy.

11.
Support Care Cancer ; 27(7): 2507-2515, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30397900

RESUMEN

PURPOSE: The aim of this study was to estimate the incidence and predictors of venous thromboembolism (VTE) in medically ill hospitalized elderly cancer patients in a single Korean tertiary hospital. METHODS: Patients were examined for deep vein thrombosis (DVT) by duplex and color Doppler ultrasonography (DUS) of both legs between days 5 and 14 of their hospital stays. The primary endpoint was the incidence of VTE by day 14, which was determined via a composite of DVT detected by routine DUS and symptomatic VTE. RESULTS: A total of 140 patients with 31 hematologic and 109 nonhematologic malignancies were analyzed. The median age was 73 years, and 45.7% of the patients were female. The median length of hospital stay was 12 days. The modified Padua prediction score (PPS) ≥ 4 was 92.9%. The incidence of VTE by day 14 was 7.1%, including six proximal and four distal DVT cases. Being female, having a length of hospital stay of ≥ 13 days, and having a modified Padua prediction score of ≥ 6 were risk factors of VTE in univariate analysis. The incidence of VTE was 2.3%, 7.3%, and 41.7% in patients with 0-1, 2, and 3 of these risk factors, respectively. CONCLUSION: The incidence of VTE in medically ill hospitalized elderly cancer patients was lower in Korean patients than in Western patients. However, the risk of VTE in those with more than two risk factors (female, long length of hospitalization, and high PPS) increased considerably, and pharmacologic thromboprophylaxis is warranted in these cases.


Asunto(s)
Tromboembolia Venosa/epidemiología , Anciano , Anciano de 80 o más Años , Femenino , Hospitalización , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo
12.
Surg Endosc ; 33(3): 861-869, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30006847

RESUMEN

BACKGROUND: Endoscopic screening has been adopted in South Korea for the national screening of gastric cancer (GC). This study aimed to assess the effect on overall survival of GC patients and determine the optimal endoscopic screening interval. METHODS: The baseline characteristics and overall survival of GC patients treated at the National Cancer Center, Korea, between 2010 and 2016 were compared between those without a history of endoscopic evaluation (group N) and those in whom the interval between the last endoscopic evaluations and diagnosis of GC was ≤ 1, 1-2, 2-3, 3-4, or > 4 years (groups 1-5, respectively). RESULTS: A total of 2362 patients met the criteria for the study (1060 in group N and 1302 in groups 1-5). More patients in groups 1-5 were diagnosed with stage I GC (83.7, 83.7, 71.8, 78.2, and 71.6%, respectively) than in group N (62.4%, P < 0.001) and were treated endoscopically (38.8, 33.8, 24.7, 21.8, and 15.5%, respectively, vs. 13.5%; P < 0.001). Group 2 had less-advanced tumor stages (P = 0.001) and was more likely to have received endoscopic treatments (P = 0.026) than group 3. Hazard ratios for death were significantly lower in groups 2 (0.45; 95% confidence interval [CI], 0.32-0.64) and 3 (0.57; 95% CI, 0.33-0.98) than in group N; the decrease was not significant in group 4 (0.49, 95% CI, 0.20-1.20). CONCLUSIONS: Endoscopic screening every 3 years may reduce the mortality of GC patients, though screenings at least every 2 years may benefit patients with less-advanced stages.


Asunto(s)
Detección Precoz del Cáncer , Endoscopía , Neoplasias Gástricas , Adulto , Anciano , Detección Precoz del Cáncer/métodos , Detección Precoz del Cáncer/estadística & datos numéricos , Endoscopía/métodos , Endoscopía/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , República de Corea/epidemiología , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/epidemiología , Neoplasias Gástricas/patología , Análisis de Supervivencia , Factores de Tiempo
13.
J Comput Assist Tomogr ; 43(3): 423-427, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31082947

RESUMEN

PURPOSE: To compare the fenestrated intravenous (IV) catheter and nonfenestrated conventional IV catheter in terms of contrast enhancement and injection pressure for coronary computed tomography angiography. METHODS: Three hundred patients were prospectively and consecutively enrolled to either the 20-gauge nonfenestrated conventional (group 1) IV catheter group or the 20-gauge fenestrated (group 2) or 22-gauge fenestrated (group 3) IV catheter groups. We analyzed mean vascular attenuations in the ascending aorta, left main coronary artery, left ventricular (LV) cavity, and descending aorta. Injection pressure using pound-force per square inch (PSI) and extravasation of contrast media were recorded. RESULTS: Mean attenuations of the left main coronary artery, LV cavity, and descending aorta were significantly higher in group 2 than in group 1 (P ≤ 0.001, P ≤ 0.001, P ≤ 0.001, respectively). Moreover, injection pressure was significantly lower in group 2 than in group 1 (208.3 vs 216.9 PSI, P = 0.006). Mean vascular attenuations of the left main coronary artery, LV cavity, and descending aorta were significantly higher in group 3 than in group 1 (P = 0.016, P = 0.029, P = 0.001, respectively). However, injection pressure was not statistically significant between group 3 and group 1 (213.6 vs 216.9 PSI, P = 0.355). No extravasation occurred in any patient groups during the study. CONCLUSIONS: We suggest that fenestrated IV catheter is useful in terms of higher vascular attenuation and lower injection pressure for coronary computed tomography angiography. It has a potential merit in patients with fragile and small veins.


Asunto(s)
Cateterismo Venoso Central/métodos , Medios de Contraste/administración & dosificación , Tomografía Computarizada Multidetector/métodos , Adulto , Anciano , Catéteres Venosos Centrales , Femenino , Humanos , Inyecciones Intravenosas , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Radiografía Intervencional/métodos
14.
Sensors (Basel) ; 19(8)2019 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-31013773

RESUMEN

In this paper, we proposed a gait type classification method based on deep learning using a smart insole with various sensor arrays. We measured gait data using a pressure sensor array, an acceleration sensor array, and a gyro sensor array built into a smart insole. Features of gait pattern were then extracted using a deep convolution neural network (DCNN). In order to accomplish this, measurement data of continuous gait cycle were divided into unit steps. Pre-processing of data were then performed to remove noise followed by data normalization. A feature map was then extracted by constructing an independent DCNN for data obtained from each sensor array. Each of the feature maps was then combined to form a fully connected network for gait type classification. Experimental results for seven types of gait (walking, fast walking, running, stair climbing, stair descending, hill climbing, and hill descending) showed that the proposed method provided a high classification rate of more than 90%.

15.
Sensors (Basel) ; 19(17)2019 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-31480467

RESUMEN

Recent studies indicate that individuals can be identified by their gait pattern. A number of sensors including vision, acceleration, and pressure have been used to capture humans' gait patterns, and a number of methods have been developed to recognize individuals from their gait pattern data. This study proposes a novel method of identifying individuals using null-space linear discriminant analysis on humans' gait pattern data. The gait pattern data consists of time series pressure and acceleration data measured from multi-modal sensors in a smart insole used while walking. We compare the identification accuracies from three sensing modalities, which are acceleration, pressure, and both in combination. Experimental results show that the proposed multi-modal features identify 14 participants with high accuracy over 95% from their gait pattern data of walking.


Asunto(s)
Marcha/fisiología , Dispositivos Electrónicos Vestibles , Acelerometría , Adulto , Algoritmos , Análisis Discriminante , Femenino , Análisis de la Marcha , Humanos , Masculino , Zapatos , Adulto Joven
16.
Nano Lett ; 18(5): 2930-2936, 2018 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-29634282

RESUMEN

Pt-based nanoframe catalysts have been explored extensively due to their superior activity toward the oxygen reduction reaction (ORR). Herein, we report the synthesis of Pt-Ni multiframes, which exhibit the unique structure of tightly fused multiple nanoframes and reinforced by an embedded dendrite. Rapid reduction and deposition of Ni atoms on Pt-Ni nanodendrites induce the alloying/dealloying of Pt and Ni in the overall nanostructures. After chemical etching of Ni, the newly formed dendrite-embedded Pt-Ni multiframes show an electrochemically active surface area (ECSA) of 73.4 m2 gPt-1 and a mass ORR activity of 1.51 A mgPt-1 at 0.93 V, which is 30-fold higher than that of the state-of-the-art Pt/C catalyst. We suggest that high ECSA and ORR performances of dendrite-embedded Pt-Ni multiframes/C can be attributed to the porous nanostructure and numerous active sites exposed on surface grain boundaries and high-indexed facets.

17.
J Phys Ther Sci ; 31(8): 698-701, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31528012

RESUMEN

[Purpose] Central pontine demyelination is a common osmotic demyelination syndrome. Typically, central pontine demyelination shows high signal intensity with demyelination in the mid-pons. Despite severe imaging findings, patients usually recover. This study investigated the integrity of the corticospinal tract (CST) and corticoreticular pathway (CRP) in patients at 12 months after the onset of central pontine demyelination. [Participants and Methods] This retrospective cross-sectional observational study assessed two patients with central pontine demyelination, who were ultimately able to walk without using an aid or orthosis and to use both hands but with mild residual symptoms. All participants underwent diffusion tensor imaging (DTI) at 12 months after onset. [Results] Both patients had mild ataxia at 12 months after onset. The integrity of the CST was restored in both cases, while the integrity of the CRP recovered partially. [Conclusion] The integrity of the CST and CRP at 12 months after the onset of central pontine demyelination was similar in both cases as well as the recovery status of the hand function and ambulation. These results may be useful in planning therapy for patients with central pontine demyelination.

18.
Sensors (Basel) ; 19(1)2018 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-30583537

RESUMEN

There have been decades of research on face recognition, and the performance of many state-of-the-art face recognition algorithms under well-conditioned environments has become saturated. Accordingly, recent research efforts have focused on difficult but practical challenges. One such issue is the single sample per person (SSPP) problem, i.e., the case where only one training image of each person. While this problem is challenging because it is difficult to establish the within-class variation, working toward its solution is very practical because often only a few images of a person are available. To address the SSPP problem, we propose an efficient coupled bilinear model that generates virtual images under various illuminations using a single input image. The proposed model is inspired by the knowledge that the illuminance of an image is not sensitive to the poor quality of a subspace-based model, and it has a strong correlation to the image itself. Accordingly, a coupled bilinear model was constructed that retrieves the illuminance information from an input image. This information is then combined with the input image to estimate the texture information, from which we can generate virtual illumination conditions. The proposed method can instantly generate numerous virtual images of good quality, and these images can then be utilized to train the feature space for resolving SSPP problems. Experimental results show that the proposed method outperforms the existing algorithms.


Asunto(s)
Cara/fisiología , Interpretación de Imagen Asistida por Computador/métodos , Reconocimiento de Normas Patrones Automatizadas/métodos , Algoritmos , Inteligencia Artificial , Humanos , Aumento de la Imagen , Procesamiento de Imagen Asistido por Computador
19.
Nano Lett ; 17(6): 3926-3931, 2017 06 14.
Artículo en Inglés | MEDLINE | ID: mdl-28493711

RESUMEN

Octahedral Pt alloy nanocrystals (NCs) have shown excellent activities as electrocatalysts toward oxygen reduction reaction (ORR). As the activity and stability of NCs are highly dependent on their structure and the elemental distribution, it is of great importance to understand the formation mechanism of octahedral NCs and to rationally synthesize shape-controlled alloy catalysts with optimized ORR activity and stability. However, the factors controlling the structural and compositional evolution during the synthesis have not been well understood yet. Here, we systematically investigated the structure and composition evolution pathways of Pt-Ni octahedra synthesized with the assistance of W(CO)6 and revealed a unique core-shell structure consisting of a Pt core and a Pt-Ni alloy shell. Below 140 °C, sphere-like pure Pt NCs with the diameter of 3-4 nm first nucleated, followed by the isotropic growth of Pt-Ni alloy on the seeds at temperatures between 170 and 230 °C forming Pt@Pt-Ni core-shell octahedra with {111} facets. Owing to its unique structure, the Pt@Pt-Ni octahedra show an unparalleled stability during potential cycling, that is, no activity drop after 10 000 cycles between 0.6 and 1.0 V. This work proposes the Pt@Pt-Ni octahedra as a high profile electrocatalyst for ORR and reveals the structural and composition evolution pathways of Pt-based bimetallic NCs.

20.
Eur Radiol ; 27(3): 1136-1147, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27380904

RESUMEN

OBJECTIVES: To evaluate the feasibility of a double-acquisition coronary CT angiography (CCTA) protocol in the presence and absence of an intravenous (IV) vasodilator infusion for detecting vasospastic angina. METHODS: Twenty patients with a high clinical probability of vasospastic angina were enrolled. All subjects underwent baseline CCTA without a vasodilator in the early morning followed by a catheterized coronary angiography with ergonovine provocation test. Within 3 days, all subjects underwent repeat CCTA during a continuous IV infusion of nitrate. Vasospastic angina as detected by CCTA was defined as significant stenosis (≥50 %) with negative remodelling without definite plaques or diffuse small diameter (<2 mm) of a major coronary artery with a beaded appearance on baseline CT that completely dilated on IV nitrate CT. The CCTA results were compared to the catheterized ergonovine provocation test as the reference standard. RESULTS: Among 20 patients, the catheterized ergonovine provocation test detected vasospasm in 15 patients. The sensitivity, specificity, positive predictive value and negative predictive value of CCTA in a per-patient-based analysis were 73, 100, 100 and 56 %, respectively. CONCLUSIONS: Double-acquisition CCTA in the presence and absence of IV infusion of nitrate allows noninvasive detection of vasospastic angina with moderate sensitivity and high specificity. KEY POINTS: • Limited data exist regarding the efficacy of CCTA in detecting vasospastic angina. • We propose a double-acquisition CCTA protocol with and without IV nitrate injections. • This protocol provides 100% specificity and moderate sensitivity (73%) in spasm detection.


Asunto(s)
Angina de Pecho/diagnóstico por imagen , Angiografía por Tomografía Computarizada/métodos , Angiografía Coronaria/métodos , Vasoespasmo Coronario/diagnóstico por imagen , Vasos Coronarios/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Angina de Pecho/etiología , Ergonovina , Estudios de Factibilidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Estudios Prospectivos , Sensibilidad y Especificidad , Tomografía Computarizada por Rayos X , Vasodilatadores
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