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1.
BMC Neurol ; 24(1): 179, 2024 May 27.
Artículo en Inglés | MEDLINE | ID: mdl-38802755

RESUMEN

BACKGROUND: Accumulating neuroimaging evidence indicates that patients with cervical dystonia (CD) have changes in the cortico-subcortical white matter (WM) bundle. However, whether these patients' WM structural networks undergo reorganization remains largely unclear. We aimed to investigate topological changes in large-scale WM structural networks in patients with CD compared to healthy controls (HCs), and explore the network changes associated with clinical manifestations. METHODS: Diffusion tensor imaging (DTI) was conducted in 30 patients with CD and 30 HCs, and WM network construction was based on the BNA-246 atlas and deterministic tractography. Based on the graph theoretical analysis, global and local topological properties were calculated and compared between patients with CD and HCs. Then, the AAL-90 atlas was used for the reproducibility analyses. In addition, the relationship between abnormal topological properties and clinical characteristics was analyzed. RESULTS: Compared with HCs, patients with CD showed changes in network segregation and resilience, characterized by increased local efficiency and assortativity, respectively. In addition, a significant decrease of network strength was also found in patients with CD relative to HCs. Validation analyses using the AAL-90 atlas similarly showed increased assortativity and network strength in patients with CD. No significant correlations were found between altered network properties and clinical characteristics in patients with CD. CONCLUSION: Our findings show that reorganization of the large-scale WM structural network exists in patients with CD. However, this reorganization is attributed to dystonia-specific abnormalities or hyperkinetic movements that need further identification.


Asunto(s)
Imagen de Difusión Tensora , Tortícolis , Sustancia Blanca , Humanos , Tortícolis/diagnóstico por imagen , Tortícolis/patología , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/patología , Femenino , Masculino , Imagen de Difusión Tensora/métodos , Persona de Mediana Edad , Adulto , Red Nerviosa/diagnóstico por imagen , Red Nerviosa/patología , Anciano
2.
BMC Neurol ; 24(1): 174, 2024 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-38789945

RESUMEN

BACKGROUND: The thalamus has a central role in the pathophysiology of idiopathic cervical dystonia (iCD); however, the nature of alterations occurring within this structure remain largely elusive. Using a structural magnetic resonance imaging (MRI) approach, we examined whether abnormalities differ across thalamic subregions/nuclei in patients with iCD. METHODS: Structural MRI data were collected from 37 patients with iCD and 37 healthy controls (HCs). Automatic parcellation of 25 thalamic nuclei in each hemisphere was performed based on the FreeSurfer program. Differences in thalamic nuclei volumes between groups and their relationships with clinical information were analysed in patients with iCD. RESULTS: Compared to HCs, a significant reduction in thalamic nuclei volume primarily in central medial, centromedian, lateral geniculate, medial geniculate, medial ventral, paracentral, parafascicular, paratenial, and ventromedial nuclei was found in patients with iCD (P < 0.05, false discovery rate corrected). However, no statistically significant correlations were observed between altered thalamic nuclei volumes and clinical characteristics in iCD group. CONCLUSION: This study highlights the neurobiological mechanisms of iCD related to thalamic volume changes.


Asunto(s)
Imagen por Resonancia Magnética , Tálamo , Tortícolis , Humanos , Masculino , Femenino , Persona de Mediana Edad , Tortícolis/diagnóstico por imagen , Tortícolis/patología , Imagen por Resonancia Magnética/métodos , Tálamo/diagnóstico por imagen , Tálamo/patología , Adulto , Anciano , Núcleos Talámicos/diagnóstico por imagen , Núcleos Talámicos/patología
3.
Clin Oral Investig ; 28(6): 326, 2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38763957

RESUMEN

OBJECTIVES: To three-dimensionally assess differences in craniomaxillofacial skeletal development in patients with operated unilateral cleft lip and palate (UCLP) treated with/without presurgical nasoalveolar molding (PNAM) with a mean age of 5 years. MATERIALS AND METHODS: Cone-beam CT radiographs of 30 patients with UCLP who had undergone PNAM and 34 patients with UCLP who did not receive PNAM were analyzed. The data were stored in DICOM file format and were imported into the Dolphin Imaging program for 3D image reconstruction and landmark identification. 33 landmarks, 17 linear and three angular variables representing craniofacial morphology were analyzed and compared by using the Mann-Whitney U tests. RESULTS: The vast majority of linear variables and 3D coordinates of landmark points reflecting craniofacial skeletal symmetry were not significantly different between the two groups. In terms of craniofacial skeletal development, the PNAM group had a significantly smaller anterior nasal spine offset in the midsagittal plane and a greater maxillary length compared to the non-PNAM group. CONCLUSIONS: Evaluations performed in early childhood showed that treatment with/without PNAM in the neonatal period was not a major factor influencing craniomaxillofacial hard tissue development in patients with UCLP; moreover, PNAM treatment showed significant correction of skeletal deviation at the base of the nose. CLINICAL RELEVANCE: Follow-up in early childhood has shown that PNAM treatment administered during the neonatal stage does not impede maxillary development and has benefits in correcting nasal floor deviation. It is a viable option for improving nasal deformity in children with unilateral cleft lip and palate.


Asunto(s)
Labio Leporino , Fisura del Paladar , Tomografía Computarizada de Haz Cónico , Imagenología Tridimensional , Modelado Nasoalveolar , Humanos , Labio Leporino/terapia , Labio Leporino/diagnóstico por imagen , Fisura del Paladar/terapia , Fisura del Paladar/diagnóstico por imagen , Estudios Retrospectivos , Masculino , Femenino , Preescolar , Imagenología Tridimensional/métodos , Resultado del Tratamiento , Desarrollo Maxilofacial , Puntos Anatómicos de Referencia , Lactante
4.
Brain Commun ; 6(2): fcae117, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38638150

RESUMEN

The thalamus is considered a key region in the neuromechanisms of blepharospasm. However, previous studies considered it as a single, homogeneous structure, disregarding potentially useful information about distinct thalamic nuclei. Herein, we aimed to examine (i) whether grey matter volume differs across thalamic subregions/nuclei in patients with blepharospasm and blepharospasm-oromandibular dystonia; (ii) causal relationships among abnormal thalamic nuclei; and (iii) whether these abnormal features can be used as neuroimaging biomarkers to distinguish patients with blepharospasm from blepharospasm-oromandibular dystonia and those with dystonia from healthy controls. Structural MRI data were collected from 56 patients with blepharospasm, 20 with blepharospasm-oromandibular dystonia and 58 healthy controls. Differences in thalamic nuclei volumes between groups and their relationships to clinical information were analysed in patients with dystonia. Granger causality analysis was employed to explore the causal effects among abnormal thalamic nuclei. Support vector machines were used to test whether these abnormal features could distinguish patients with different forms of dystonia and those with dystonia from healthy controls. Compared with healthy controls, patients with blepharospasm exhibited reduced grey matter volume in the lateral geniculate and pulvinar inferior nuclei, whereas those with blepharospasm-oromandibular dystonia showed decreased grey matter volume in the ventral anterior and ventral lateral anterior nuclei. Atrophy in the pulvinar inferior nucleus in blepharospasm patients and in the ventral lateral anterior nucleus in blepharospasm-oromandibular dystonia patients was negatively correlated with clinical severity and disease duration, respectively. The proposed machine learning scheme yielded a high accuracy in distinguishing blepharospasm patients from healthy controls (accuracy: 0.89), blepharospasm-oromandibular dystonia patients from healthy controls (accuracy: 0.82) and blepharospasm from blepharospasm-oromandibular dystonia patients (accuracy: 0.94). Most importantly, Granger causality analysis revealed that a progressive driving pathway from pulvinar inferior nuclear atrophy extends to lateral geniculate nuclear atrophy and then to ventral lateral anterior nuclear atrophy with increasing clinical severity in patients with blepharospasm. These findings suggest that the pulvinar inferior nucleus in the thalamus is the focal origin of blepharospasm, extending to pulvinar inferior nuclear atrophy and subsequently extending to the ventral lateral anterior nucleus causing involuntary lower facial and masticatory movements known as blepharospasm-oromandibular dystonia. Moreover, our results also provide potential targets for neuromodulation especially deep brain stimulation in patients with blepharospasm and blepharospasm-oromandibular dystonia.

5.
Chemistry ; 30(15): e202303886, 2024 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-38212975

RESUMEN

Hydrogen production from photocatalysis via the usage of multicomponent photocatalysts represents a promising pathway for carbon peaking and carbon neutrality, owing to their structural advantages in dealing with the three crucial processes in photocatalysis, namely, light harvesting, charge transfer, and surface redox reactions. We demonstrate the fabrication of a MOF-based multicomponent photocatalyst, denoted as semiconductor/MOF/cocatalyst, by a one-pot electrochemical synthetic route. The as-fabricated multicomponent photocatalyst has a clean interface among the components, leading to close connections that contribute to high-quality heterojunction and facilitate photogenerated charge transfer and separation, thereby the efficient hydrogen evolution. The hydrogen production rate of the resultant ZrO2 /Zr-MOF/Pt is 1327 µmol ⋅ g-1 ⋅ h-1 , which is much higher than that of ZrO2 /Zr-MOF (15 µmol ⋅ g-1 ⋅ h-1 ) and pure Zr-MOF (10.1 µmol ⋅ g-1 ⋅ h-1 ), as well as the photodeposited-Pt products ZrO2 /Zr-MOF/PtPD (287 µmol ⋅ g-1 ⋅ h-1 ) and Zr-MOF/PtPD (192 µmol ⋅ g-1 ⋅ h-1 ) obtained by the step-wise synthetic approach. The work gives a good inspiration for the rational design and construction of MOF-based multicomponent photocatalysts through the one-pot electrosynthesis.

6.
Psychol Health Med ; 29(4): 721-731, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36967555

RESUMEN

The objective of the study is to explore the influence of self-esteem on the happiness levels of college students and the mediating roles of social avoidance and loneliness. 1021 college students between 18 and 24 years of age completed the Self-esteem Scale, General Well-being Scale, Social Avoidance and Distress Scale, UCLA Loneliness Scale and Interpersonal Trust Scale.And descriptive statistical analysis and correlation analysis, structural equation model analysis were conducted. The result turns out that Self-esteem negatively predicted the happiness levels of college students. Self-esteem indirectly predicted happiness through three paths: mediating the roles of social avoidance, mediating the roles of loneliness and the chain-mediated roles of social avoidance and loneliness in college students.Interpersonal Trust moderated the relationship between loneliness and happiness.The higher the self-esteem levels of the college students, the less happiness they experienced.


Asunto(s)
Felicidad , Soledad , Humanos , Autoimagen , Estudiantes , China
7.
Inorg Chem ; 62(48): 19795-19803, 2023 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-37987702

RESUMEN

Nickel-iron-based layered double hydroxides (NiFe-LDHs) are promising catalysts for the oxygen evolution reaction (OER) because of their high activity, availability, and low cost. Defect engineering, particularly the formation of oxygen vacancies, can improve the catalytic activity of NiFe-LDHs. However, the controllable introduction of uniform oxygen vacancies remains challenging. Herein, an n-butyllithium treatment method is developed to tune oxygen vacancy defects and change the degree of amorphization in NiFe-LDHs via deep reduction, followed by partial oxidization at low temperatures. Interestingly, the Ni in the NiFe-LDHs is selectively reduced to the alloy state by n-butyllithium, whereas Fe is not. The different structural transformations of Ni and Fe during the treatment successfully produce an oxygen-defect-rich amorphous/crystalline electrocatalyst. Under optimal conditions, the treated NiFe-LDHs exhibit high OER activity with an overpotential of 223 mV at 10 mA cm-2 (68 mV lower than that of a commercial IrO2 electrocatalyst) and long-term stability. Notably, the n-butyllithium treatment can be applied to other electrocatalysts, such as CoFe-LDHs and IrO2 (treated IrO2 with an overpotential of 197 mV at 10 mA cm-2). This n-butyllithium reduction/partial oxidization treatment constitutes a novel top-down strategy for the controllable modification of metal oxide structures, with various energy-related applications.

8.
FASEB J ; 37(11): e23241, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37847512

RESUMEN

Cementum, a constituent part of periodontal tissues, has important adaptive and reparative functions. It serves to attach the tooth to alveolar bone and acts as a barrier delimit epithelial growth and bacteria evasion. A dynamic and highly responsive cementum is essential for maintaining occlusal relationships and the integrity of the root surface. It is a thin layer of mineralized tissue mainly produced by cementoblasts. Cementoblasts are osteoblast-like cells essential for the restoration of periodontal tissues. In recent years, glucose metabolism has been found to be critical in bone remodeling and osteoblast differentiation. However, the glucose metabolism of cementoblasts remains incompletely understood. First, immunohistochemistry staining and in vivo tracing with 18 F-fluorodeoxyglucose (18 F-FDG) revealed significantly higher glucose metabolism in cementum formation. To test the bioenergetic pathways of cementoblast differentiation, we compared the bioenergetic profiles of mineralized and unmineralized cementoblasts. As a result, we observed a significant increase in the consumption of glucose and production of lactate, coupled with the higher expression of glycolysis-related genes. However, the expression of oxidative phosphorylation-related genes was downregulated. The verified results were consistent with the RNA sequencing results. Likewise, targeted energy metabolomics shows that the levels of glycolytic metabolites were significantly higher in the mineralized cementoblasts. Seahorse assays identified an increase in glycolytic flux and reduced oxygen consumption during cementoblast mineralization. Apart from that, we also found that lactate dehydrogenase A (LDHA), a key glycolysis enzyme, positively regulates the mineralization of cementoblasts. In summary, cementoblasts mainly utilized glycolysis rather than oxidative phosphorylation during the mineralization process.


Asunto(s)
Cemento Dental , Ácido Láctico , Diferenciación Celular , Inmunohistoquímica , Glucosa
9.
Neuroscience ; 531: 50-59, 2023 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-37709002

RESUMEN

Selective impairment in recognizing facial expressions of disgust was reported in patients with focal dystonia several years ago, but the basic neural mechanisms remain largely unexplored. Therefore, we investigated whether dysfunction of the brain network involved in disgust recognition processing was related to this selective impairment in blepharospasm. Facial emotion recognition evaluations and resting-state functional magnetic resonance imaging were performed in 33 blepharospasm patients and 33 healthy controls (HCs). The disgust processing network was constructed, and modularity analyses were performed to identify sub-networks. Regional functional indexes and intra- and inter-functional connections were calculated and compared between the groups. Compared to HCs, blepharospasm patients demonstrated a worse performance in disgust recognition. In addition, functional connections within the sub-network involved in perception processing rather than recognition processing of disgust were significantly decreased in blepharospasm patients compared to HCs. Specifically, decreased functional connections were noted between the left fusiform gyrus (FG) and right middle occipital gyrus (MOG), the left FG and right FG, and the right FG and left MOG. We identified decreased functional activity in these regions, as indicated by a lower amplitude of low-frequency fluctuation in the left MOG, fractional amplitude of low-frequency fluctuation in the right FG, and regional homogeneity in the right FG and left MOG in blepharospasm patients versus HCs. Our results suggest that dysfunctions of the disgust processing network exist in blepharospasm. A deficit in disgust emotion recognition may be attributed to disturbances in the early perception of visual disgust stimuli in blepharospasm patients.


Asunto(s)
Blefaroespasmo , Reconocimiento Facial , Humanos , Blefaroespasmo/diagnóstico por imagen , Emociones , Encéfalo/diagnóstico por imagen , Imagen por Resonancia Magnética , Mapeo Encefálico , Expresión Facial
10.
ACS Appl Mater Interfaces ; 15(40): 47016-47024, 2023 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-37768597

RESUMEN

Electroreduction of carbon dioxide into readily collectable and high-value carbon-based fuels is greatly significant to overcome the energy and environmental crises yet challenging in the development of robust and highly efficient electrocatalysts. Herein, a bismuth (Bi) heterophase electrode with enriched amorphous/crystalline interfaces was fabricated via cathodically in situ transformation of Bi-based metal-phenolic complexes (Bi-tannic acid, Bi-TA). Compared with amorphous or crystalline Bi catalyst, the amorphous/crystalline structure Bi leads to significantly enhanced performance for CO2 electroreduction. In a liquid-phase H-type cell, the Faraday efficiency (FE) of formate formation is over 90% in a wide potential range from -0.8 to -1.3 V, demonstrating a high selectivity toward formate. Moreover, in a flow cell, a large current density reaching 600 mA cm-2 can further be rendered for formate production. Theoretical calculations indicate that the amorphous/crystalline Bi heterophase interface exhibits a favorable adsorption of CO2 and lower energy barriers for the rate-determining step compared with the crystalline Bi counterparts, thus accelerating the reaction process. This work paves the way for the rational design of advanced heterointerface catalysts for CO2 reduction.

11.
Front Plant Sci ; 13: 1011859, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36311065

RESUMEN

Fusarium wilt, caused by Fusarium oxysporum f. sp. cucumerinum (Fo), is a severe soil-borne disease affecting cucumber production worldwide, particularly under monocropping in greenhouses. Silicon (Si) plays an important role in improving the resistance of crops to Fusarium wilt, but the underlying mechanism is largely unclear. Here, an in vitro study showed that 3 mmol·l-1 Si had the best inhibitory effect on the mycelial growth of F. oxysporum in potato dextrose agar (PDA) culture for 7 days. Subsequently, the occurrence of cucumber wilt disease and its mechanisms were investigated upon treatments with exogenous silicon under soil culture. The plant height, stem diameter, root length, and root activity under Si+Fo treatment increased significantly by 39.53%, 94.87%, 74.32%, and 95.11% compared with Fo only. Importantly, the control efficiency of Si+Fo was 69.31% compared with that of Fo treatment. Compared with Fo, the activities of peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) significantly increased by 148.92%, 26.47%, and 58.54%, while the contents of H2O2, O 2 · - , and malondialdehyde (MDA) notably decreased by 21.67%, 59.67%, and 38.701%, respectively, in roots of cucumber plants treated with Si + Fo. Compared with Fo treatment, the net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), maximum RuBisCO carboxylation rates (Vcmax), maximum RuBP regeneration rates (Jmax), and activities of ribulose-1,5-bisphosphate carboxylase (RuBisCO), fructose-1,6-bisphosphatase (FBPase), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the expression of FBPA, TPI, SBPase, and FBPase in Si+Fo treatment increased significantly. Furthermore, Si alleviated stomatal closure and enhanced endogenous silicon content compared with only Fo inoculation. The study results suggest that exogenous silicon application improves cucumber resistance to Fusarium wilt by stimulating the antioxidant system, photosynthetic capacity, and stomatal movement in cucumber leaves. This study brings new insights into the potential of Si application in boosting cucumber resistance against Fusarium wilt with a bright prospect for Si use in cucumber production under greenhouse conditions.

12.
Dalton Trans ; 51(40): 15376-15384, 2022 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-36149364

RESUMEN

The rational design and fabrication of high-performance and durable bifunctional non-noble-metal electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are still a great challenge in the practical applications of rechargeable zinc-air (Zn-air) batteries. Herein, we report a simple yet robust route to synthesize cobalt nanoparticles rooted in the hierarchically hollow nitrogen-doped carbon frameworks (Co@HNCs). This strategy employs the pyrolysis of nanostructured hollow Co-based metal-organic framework (ZIF-67) precursors produced by selective linker cleaving with pyrazino(2,3-f)(1,10)phenanthroline-2,3-dicarboxylic acid molecules (H2PPDA). The designed hierarchically architecture is favorable for the accessibility of the active sites in the catalyst, which affords enhanced bifunctional performance for ORR and OER. Moreover, when used as a cathode in liquid and all-solid-state Zn-air batteries, the resultant Co@HNCs delivers high efficiency and outstanding durability, even outperforming the benchmark Pt/C + RuO2. This work provides a feasible design avenue to achieve advanced dual-phasic oxygen electrocatalyst and promotes the development of rechargeable Zn-air batteries.

13.
Cleft Palate Craniofac J ; 59(3): 307-319, 2022 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33827285

RESUMEN

OBJECTIVE: The objective of this systematic review was to evaluate the evidence regarding skeletal maturation in patients with cleft lip and/or palate (CL/P) and to investigate whether the skeletal maturation is delayed in these patients. DESIGN: Systematic review. METHODS: Electronic and manual searches of scientific literature were conducted in 4 databases (MEDLINE, Embase, Cochrane Library, and Web of Science). Cohort studies that compared the skeletal maturation of patients with CL/P with that of children without CL/P were eligible for inclusion. The quality of included cohort studies was assessed using the Newcastle-Ottawa Scale. PATIENTS AND PARTICIPANTS: Patients of any sex and ethnicity with CL/P and children without CL/P were included in this systematic review. MAIN OUTCOME MEASURES: Difference in skeletal maturation between patients with CL/P and patients without CL/P. RESULTS: Thirteen retrospective cohort studies were included in this systematic review. Ten studies were considered of high quality and 3 were considered of general quality. The results of the included studies comparing skeletal maturation of patients with CL/P and children without CL/P were heterogeneous. CONCLUSION: Heterogeneity of skeletal maturation assessment methods, chronological age, sex, cleft type, and race may influence the final results of clinical studies on skeletal maturation in patients with CL/P. Overall, there is limited evidence to determine whether the skeletal maturation level of patients with CL/P is delayed compared to that of normal children. Further studies are needed to determine the skeletal maturation patterns in patients with CL/P.


Asunto(s)
Labio Leporino , Fisura del Paladar , Niño , Humanos , Estudios Retrospectivos
14.
Nanoscale ; 13(29): 12651-12658, 2021 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-34477615

RESUMEN

A facile and large-scale construction of robust and inexpensive trifunctional self-supporting electrodes for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in metal-air batteries and water splitting is crucial but remains challenging. Herein, we report a direct and up-scalable all-solid-phase strategy for the synthesis of a porous three-dimensional electrode consisting of cobalt nanoparticles wrapped in nitrogen-doped carbon tubes (Co/N-CNTs), which are in situ planted onto the surface of a cobalt foam. The resultant Co/N-CNTs can directly serve as a self-supporting and adhesive-free electrode with excellent and durable catalytic performances for the ORR, OER and HER. The metal framework substrate with an open-pore architecture is favorable for electron and mass transfer and allows fast catalytic kinetics. More importantly, when used in Zn-air batteries and overall water splitting, the as-prepared Co/N-CNT electrode displays a remarkable performance, implying bright perspects for practical application.

15.
Nat Commun ; 11(1): 3049, 2020 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-32546781

RESUMEN

Atomic interface regulation is thought to be an efficient method to adjust the performance of single atom catalysts. Herein, a practical strategy was reported to rationally design single copper atoms coordinated with both sulfur and nitrogen atoms in metal-organic framework derived hierarchically porous carbon (S-Cu-ISA/SNC). The atomic interface configuration of the copper site in S-Cu-ISA/SNC is detected to be an unsymmetrically arranged Cu-S1N3 moiety. The catalyst exhibits excellent oxygen reduction reaction activity with a half-wave potential of 0.918 V vs. RHE. Additionally, through in situ X-ray absorption fine structure tests, we discover that the low-valent Cuprous-S1N3 moiety acts as an active center during the oxygen reduction process. Our discovery provides a universal scheme for the controllable synthesis and performance regulation of single metal atom catalysts toward energy applications.

16.
Adv Mater ; 31(44): e1904496, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31512296

RESUMEN

Single-atom catalysts (SACs) feature the maximum atom economy and superior performance for various catalysis fields, attracting tremendous attention in materials science. However, conventional synthesis of SACs involves high energy consumption at high temperature, complicated procedures, a massive waste of metal species, and poor yields, greatly impeding their development. Herein, a facile dangling bond trapping strategy to construct SACs under ambient conditions from easily accessible bulk metals (such as Fe, Co, Ni, and Cu) is presented. When mixing graphene oxide (GO) slurry with metal foam and drying in ambient conditions, the M0 would transfer electrons to the dangling oxygen groups on GO, obtaining Mδ+ (0 < δ < 3) species. Meanwhile, Mδ+ coordinates with the surface oxygen dangling bonds of GO to form MO bonds. Subsequently, the metal atoms are pulled out of the metal foam by the MO bonds under the assistance of sonication to give M SAs/GO materials. This synthesis at room temperature from bulk metals provides a versatile platform for facile and low-cost fabrication of SACs, crucial for their mass production and practical application in diverse industrial reactions.

17.
Nat Commun ; 10(1): 3734, 2019 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-31427572

RESUMEN

Single-atom metal catalysts have sparked tremendous attention, but direct transformation of cheap and easily obtainable bulk metal oxide into single atoms is still a great challenge. Here we report a facile and versatile gas-transport strategy to synthesize isolated single-atom copper sites (Cu ISAS/NC) catalyst at gram levels. Commercial copper (I) oxide powder is sublimated as mobile vapor at nearly melting temperature (1500 K) and subsequently can be trapped and reduced by the defect-rich nitrogen-doped carbon (NC), forming the isolated copper sites catalyst. Strikingly, this thermally stable Cu ISAS/NC, which is obtained above 1270 K, delivers excellent oxygen reduction performance possessing a recorded half-wave potential of 0.92 V vs RHE among other Cu-based electrocatalysts. By varying metal oxide precursors, we demonstrate the universal synthesis of different metal single atoms anchored on NC materials (M ISAS/NC, where M refers to Mo and Sn). This strategy is readily scalable and the as-prepared sintering-resistant M ISAS/NC catalysts hold great potential in high-temperature applications.

18.
Chem Commun (Camb) ; 55(46): 6563-6566, 2019 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-31111857

RESUMEN

Co single atoms anchored on ultrathin two-dimensional nitrogen-doped carbon (Co SAs/2D N-C) were in situ derived from 2D metal-organic frameworks (MOFs). These ultrathin nanosheets functionalized by the isolated Co atoms possess a high density of active sites and accessible surfaces, exhibiting an exceptional catalytic performance in the oxidation of silanes.

19.
J Am Chem Soc ; 141(11): 4505-4509, 2019 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-30832476

RESUMEN

Developing a facile route to access active and well-defined single atom sites catalysts has been a major area of focus for single atoms catalysts (SACs). Herein, we demonstrate a simple approach to generate atomically dispersed platinum via a thermal emitting method using bulk Pt metal as a precursor, significantly simplifying synthesis routes and minimizing synthesis costs. The ammonia produced by pyrolysis of Dicyandiamide can coordinate with platinum atoms by strong coordination effect. Then, the volatile Pt(NH3) x can be anchored onto the surface of defective graphene. The as-prepared Pt SAs/DG exhibits high activity for the electrochemical hydrogen evolution reaction and selective oxidation of various organosilanes. This viable thermal emitting strategy can also be applied to other single metal atoms, for example, gold and palladium. Our findings provide an enabling and versatile platform for facile accessing SACs toward many industrial important reactions.

20.
Adv Mater ; 31(12): e1808043, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30721541

RESUMEN

The development of robust and efficient trifunctional catalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen reaction (HER) is central to regenerative metal-air batteries and overall water splitting. It is still a big challenge to achieve an efficient integration of three functions in one freestanding electrode. Herein, a facile and upscalable strategy is demonstrated, to construct cobalt nanoparticle-encapsulated 3D conductive films (Co/CNFs), which were induced by in situ solid diffusion from bulk cobalt metal. Under high-temperature, volatile cobalt species from bulk cobalt foil are trapped by the contacted nitrogen-rich carbons, followed by catalytic growth of interconnected carbon tubes, forming the 3D structured film. This resulting film can be directly preformed as self-supporting and binder-free electrode, which simultaneously facilitates the ORR, OER, and HER with excellent activities and superior stability. Furthermore, such "all-in-one" film also exhibits remarkable performance for Zn-air batteries and overall water splitting, demonstrating its feasibility for practical applications.

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