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1.
J Affect Disord ; 356: 371-378, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38608764

RESUMEN

BACKGROUND: Osteoporosis and major depressive disorder (MDD) represent two significant health challenges globally, particularly among perimenopausal women. This study utilizes NHANES data and Mendelian randomization (MR) analysis to explore the link between them, aiming to provide a basis for intervention strategies for this group. METHODS: The study analyzed NHANES 2007-2018 data using weighted logistic regression in R software to evaluate the link between MDD and osteoporosis risk. Then, a two-sample MR analysis with GWAS summary statistics was performed, mainly using the IVW method. Additional validation included MR Egger, Weighted Median, Mode, and MR-PRESSO methods. RESULTS: The research analysis indicated a significant link between MDD and the risk of osteopenia/osteoporosis. Our analysis revealed a significant positive relationship between MDD and both femoral neck osteoporosis (OR = 6.942 [95 % CI, 1.692-28.485]) and trochanteric osteoporosis (OR = 4.140 [95 % CI, 1.699-10.089]). In analyses related to osteopenia, a significant positive correlation was observed between MDD and both total femoral osteopenia (OR = 3.309 [95 % CI, 1.577-6.942]) and trochanteric osteopenia (OR = 2.467 [95 % CI, 1.004-6.062]). Furthermore, in the MR analysis, genetically predicted MDD was causally associated with an increased risk of osteoporosis via the IVW method (P = 0.013). LIMITATIONS: Our study was limited by potential selection bias due to excluding subjects with missing data, and its applicability was primarily to European and American populations. CONCLUSION: Integrating NHANES and MR analyses, a robust correlation between MDD and osteoporosis was identified, emphasizing the significance of addressing this comorbidity within clinical practice and meriting further investigation.


Asunto(s)
Trastorno Depresivo Mayor , Análisis de la Aleatorización Mendeliana , Osteoporosis , Perimenopausia , Humanos , Femenino , Trastorno Depresivo Mayor/genética , Trastorno Depresivo Mayor/epidemiología , Persona de Mediana Edad , Osteoporosis/genética , Osteoporosis/epidemiología , Estudio de Asociación del Genoma Completo , Encuestas Nutricionales , Enfermedades Óseas Metabólicas/genética , Enfermedades Óseas Metabólicas/epidemiología , Factores de Riesgo , Adulto
2.
Biosens Bioelectron ; 254: 116190, 2024 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-38479340

RESUMEN

It is expected that waterless low-temperature stressful environments will induce stress responses in fish and affect their vitality. In this study, we developed a laser-activated, stretchable, highly conductive liquid metal (LM) based flexible sensor system for fish multi-scale bioimpedance detection. It has excellent conformability, electrical conductivity, bending and cyclic tensile stability. Meanwhile, test result showed that wireless power supply is a potential solution for realizing safe power supply for devices inside waterless low-temperature packages. In addition, a hierarchical regression model (GC-HRM) based on Granger causality was established. The result showed that tissue bioimpedance can induce changes in individual bioimpedance with unidirectional Granger causality. The R2 of the linear regression (LR), support vector regression (SVR) and artificial neural network (ANN) models under single-scale individual bioimpedance were 0.85, 0.90 and 0.78, respectively. By adding the multi-scale bioimpedance features, the R2 of the LR, SVR and ANN models were improved to 0.95, 1.00 and 0.98, respectively.


Asunto(s)
Técnicas Biosensibles , Animales , Redes Neurales de la Computación , Conductividad Eléctrica , Suministros de Energía Eléctrica , Peces , Aprendizaje Automático
4.
J Gynecol Oncol ; 34(2): e19, 2023 03.
Artículo en Inglés | MEDLINE | ID: mdl-36659830

RESUMEN

OBJECTIVE: Endometrial cancer (EC) is a common gynecological malignant tumor. CircRNAs play crucial roles in cancer progression and metastasis. However, the biological functions of circRNAs in EC remain largely unknown. METHODS: CircSMAD2, miR-1277-5p, MFGE8 and relative maker protein expression in EC tissues or cell lines were analyzed by quantitative real-time polymerase chain reaction and Western blot. In vitro and in vivo functional assays, including EDU, CCK8, colony formation, transwell, tube formation and tumor xenograft assays, were conduct to explore the effects of circSMAD2 on EC. Mechanism assays were conducted to confirm the binding between miR-1277-5p and circSMAD2 or MFGE8 expression. RESULTS: Upregulation of circSMAD2 was uncovered in both EC tissues and cell lines. Functionally, silencing of circSMAD2 apparently inhibited the proliferation, migration, invasion and angiogenesis of EC cell lines in vitro. Mechanistically, circSMAD2 sponged miR-1277-5p to upregulate MFGE8 expression. The decrease of miR-1277-5p and increase of MFGE8 were observed both in EC tissues and cell lines. Then MFGE8 knockdown or miR-1277-5p upregulation suppressed EC cell oncogenic biological behavior. Rescue experiments showed that miR-1277-5p mimics countervailed the anticancer effects of circSMAD2 silencing on EC. Besides that, MFGE8 overexpression also attenuated the inhibitory action of miR-1277-5p mimic in EC. Moreover, knockdown of circSMAD2 inhibited EC growth in vivo. CONCLUSION: CircSMAD2 functions as an oncogene in promoting the progression of EC through miR-1277-5p/MFGE8 axis.


Asunto(s)
Hiperplasia Endometrial , Neoplasias Endometriales , MicroARNs , Femenino , Humanos , ARN Circular/genética , Neoplasias Endometriales/genética , Proliferación Celular/genética , MicroARNs/genética , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Antígenos de Superficie , Proteínas de la Leche
5.
Medicine (Baltimore) ; 101(10): e25578, 2022 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-35451376

RESUMEN

ABSTRACT: Natural killer/T-cell lymphoma (NK/TL) is a chemotherapy-sensitive disease, and asparaginase-based chemotherapy has become the standard primary treatment for patients with this malignancy recently. The objective of this study was to evaluate the adverse reactions on blood coagulation of the administered pegylated Escherichia coli (E coli) asparaginase (PEG-ASP) to the NK/TL patients. Clinical data of 71 NK/TL patients (range 13-73 years), who received 239 cycles of chemotherapy treatment containing PEG-ASP in the Hematology Department of Shanxi Province Cancer Hospital of China from January 2016 to December 2019 were analyzed retrospectively. Data of prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen (FBG), and antithrombinIII (ATIII) were obtained at the time points routinely and statistically analyzed. There were statistical differences between the monitored parameters of baseline day0 (the day before use of PEG-ASP, named day0) and those of day3 (the 3rd day after treatment) to day6, and data showed all of the indicators could recover within 21 days. The events included PT prolonged in 33 patients (46.5%), APPT prolonged in 41 patients (57.7%, 20 patients with APTT >60 seconds), FBG decreased in 49 patients (69.0%, 12 patients with FBG <1 g/L), and ATIII decreased in 52 patients (73.2%). The patients' average number of cycles received was 2.3 for PT (>14 seconds), 2.5 for APTT (>35 seconds), 2.7 for FBG (<2 g/L), and 2.6 for D-dimer (>550 ng/mL). Compared with those at day0, PT and APTT prolonged sharply at day3 (P < .05), reached the peak at day12, maintained the prolonged level from day3 to day15, and gradually recovered at day 21. FBG and ATIII significantly decreased at day6 and day3 respectively (P < .05), both of them fell to the minimum at day12, and then returned the normal. The D-dimer levels were no significantly change during the whole treatment course. The APTT >60 seconds or FBG <1 g/L side effects were improved by symptomatic treatment of supplementation of fresh frozen plasma or cryoprecipitate infusion, no concomitant bleeding or thrombotic events emerging. Our data suggested although chemotherapy including PEG-ASP impacted moderately on the coagulation function of NK/TL patients, clinically monitored regularly were necessary and most NK/TL patients can complete the chemotherapy cycles successfully.


Asunto(s)
Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Linfoma de Células T Periférico , Asparaginasa/efectos adversos , Coagulación Sanguínea , Escherichia coli , Fibrinógeno , Humanos , Polietilenglicoles/efectos adversos , Estudios Retrospectivos
6.
Chem Rev ; 121(17): 10559-10665, 2021 09 08.
Artículo en Inglés | MEDLINE | ID: mdl-34255488

RESUMEN

There is an obvious gap between efforts dedicated to the control of chemicophysical and morphological properties of catalyst active phases and the attention paid to the search of new materials to be employed as functional carriers in the upgrading of heterogeneous catalysts. Economic constraints and common habits in preparing heterogeneous catalysts have narrowed the selection of active-phase carriers to a handful of materials: oxide-based ceramics (e.g. Al2O3, SiO2, TiO2, and aluminosilicates-zeolites) and carbon. However, these carriers occasionally face chemicophysical constraints that limit their application in catalysis. For instance, oxides are easily corroded by acids or bases, and carbon is not resistant to oxidation. Therefore, these carriers cannot be recycled. Moreover, the poor thermal conductivity of metal oxide carriers often translates into permanent alterations of the catalyst active sites (i.e. metal active-phase sintering) that compromise the catalyst performance and its lifetime on run. Therefore, the development of new carriers for the design and synthesis of advanced functional catalytic materials and processes is an urgent priority for the heterogeneous catalysis of the future. Silicon carbide (SiC) is a non-oxide semiconductor with unique chemicophysical properties that make it highly attractive in several branches of catalysis. Accordingly, the past decade has witnessed a large increase of reports dedicated to the design of SiC-based catalysts, also in light of a steadily growing portfolio of porous SiC materials covering a wide range of well-controlled pore structure and surface properties. This review article provides a comprehensive overview on the synthesis and use of macro/mesoporous SiC materials in catalysis, stressing their unique features for the design of efficient, cost-effective, and easy to scale-up heterogeneous catalysts, outlining their success where other and more classical oxide-based supports failed. All applications of SiC in catalysis will be reviewed from the perspective of a given chemical reaction, highlighting all improvements rising from the use of SiC in terms of activity, selectivity, and process sustainability. We feel that the experienced viewpoint of SiC-based catalyst producers and end users (these authors) and their critical presentation of a comprehensive overview on the applications of SiC in catalysis will help the readership to create its own opinion on the central role of SiC for the future of heterogeneous catalysis.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Catálisis , Porosidad , Compuestos de Silicona/química , Carbono , Óxidos , Dióxido de Silicio/química
7.
Pulm Pharmacol Ther ; 64: 101949, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32949706

RESUMEN

BACKGROUND: This research aims to illustrate the effect of lncRNA StAR Related Lipid Transfer Domain Containing 13 antisense RN (STARD13-AS)/miR-1248/C3A on lung squamous carcinoma cells growth and metastasis. METHODS: Bioinformatics analysis was applied to detect the expression of STARD13-AS/miR-1248/C3A in lung cancer samples and establish the ceRNA network. Transfection was performed to construct over-expression or knockdown models. PCR was implemented to examine the transfection efficiency. The biological function including growth, invasion and migration of LUSC cells were estimated by CCK-8 analysis, colony formation assay and transwell assay. Luciferase assay was executed to analyze the relationship between C3A and miR-1248, as well as miR-1248 and STARD13-AS. RESULTS: By consulting the TCGA database and GEPIA website, we found that C3A expression was significantly reduced in LUSC samples. Additionally, we also discovered that miR-1248, which was a downstream target of STARD13-AS, was presented as an upstream regulator of C3A. Moreover, STARD13-AS was under expressed in LUSC cells and has a negative effect on LUSC cells growth ability. C3A expression was co-regulated by miR-1248 and STARD13-AS. Importantly, the inhibitory effect of C3A or the promoting effect of miR-1248 on LUSC cells growth, invasion and migration abilities can be regulated by STARD13-AS. CONCLUSIONS: Our findings revealed that overexpression of STARD13-AS restricted the growth and aggressiveness of LUSC cells via regulating miR-1248/C3A.


Asunto(s)
Carcinoma de Células Escamosas , Neoplasias Pulmonares , MicroARNs , ARN Largo no Codificante , Carcinoma de Células Escamosas/genética , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Humanos , Pulmón , Neoplasias Pulmonares/genética , MicroARNs/genética , ARN Largo no Codificante/genética
8.
Chemistry ; 26(16): 3586-3590, 2020 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-31961024

RESUMEN

Cubic silicon carbide (3C-SiC) material feature a suitable bandgap and high resistance to photocorrosion. Thus, it has been emerged as a promising semiconductor for hydrogen evolution. Here, the relationship between the photoelectrochemical properties and the microstructures of different SiC materials is demonstrated. For visible-light-derived water splitting to hydrogen production, nanocrystalline, microcrystalline and epitaxial (001) 3C-SiC films are applied as the photocathodes. The epitaxial 3C-SiC film presents the highest photoelectrochemical activity for hydrogen evolution, because of its perfect (001) orientation, high phase purity, low resistance, and negative conduction band energy level. This finding offers a strategy to design SiC-based photocathodes with superior photoelectrochemical performances.

9.
Small ; 15(38): e1902951, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31353799

RESUMEN

Maximizing activity of Pt catalysts toward methanol oxidation reaction (MOR) together with minimized poisoning of adsorbed CO during MOR still remains a big challenge. In the present work, uniform and well-distributed Pt nanoparticles (NPs) grown on an atomic carbon layer, that is in situ formed by means of dry-etching of silicon carbide nanoparticles (SiC NPs) with CCl4 gas, are explored as potential catalysts for MOR. Significantly, as-synthesized catalysts exhibit remarkably higher MOR catalytic activity (e.g., 647.63 mA mg-1 at a peak potential of 0.85 V vs RHE) and much improved anti-CO poisoning ability than the commercial Pt/C catalysts, Pt/carbon nanotubes, and Pt/graphene catalysts. Moreover, the amount of expensive Pt is a few times lower than that of the commercial and reported catalyst systems. As confirmed from density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) measurements, such high performance is due to reduced adsorption energy of CO on the Pt NPs and an increased amount of adsorbed energy OH species that remove adsorbed CO fast and efficiently. Therefore, these catalysts can be utilized for the development of large-scale and industry-orientated direct methanol fuel cells.

10.
ACS Appl Mater Interfaces ; 10(27): 23029-23036, 2018 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-29914262

RESUMEN

Efficient catalytic hydrogenation of nitroarenes to anilines with molecular hydrogen at room temperature is still a challenge. In this study, this transformation was achieved by using a photocatalyst of SiC-supported segregated Pd and Au nanoparticles. Under visible-light irradiation, the nitrobenzene hydrogenation reached a turnover frequency as high as 1715 h-1 at 25 °C and 0.1 MPa of H2 pressure. This exceptional catalytic activity is attributed to a synergistic effect of Pd and Au nanoparticles on the semiconducting SiC, which is different from the known electronic or ensemble effects in Pd-Au catalysts. This kind of synergism originates from the plasmonic electron injection of Au and the Mott-Schottky contact at the interface between Pd and SiC. This three-component system changes the electronic structures of the SiC surface and produces more active sites to accommodate the active hydrogen that spills over from the surface of Pd. These active hydrogen species have weaker interactions with the SiC surface and thus are more mobile than on an inert support, resulting in an ease in reacting with the N═O bonds in nitrobenzene absorbed on SiC to produce aniline.

11.
J Am Chem Soc ; 138(30): 9361-4, 2016 08 03.
Artículo en Inglés | MEDLINE | ID: mdl-27403658

RESUMEN

Highly selective hydrogenation of cinnamaldehyde to cinnamyl alcohol with 2-propanol was achieved using SiC-supported Au nanoparticles as photocatalyst. The hydrogenation reached a turnover frequency as high as 487 h(-1) with 100% selectivity for the production of alcohol under visible light irradiation at 20 °C. This high performance is attributed to a synergistic effect of localized surface plasmon resonance of Au NPs and charge transfer across the SiC/Au interface. The charged metal surface facilitates the oxidation of 2-propanol to form acetone, while the electron and steric effects at the interface favor the preferred end-adsorption of α,ß-unsaturated aldehydes for their selective conversion to unsaturated alcohols. We show that this Au/SiC photocatalyst is capable of hydrogenating a large variety of α,ß-unsaturated aldehydes to their corresponding unsaturated alcohols with high conversion and selectivity.

12.
ACS Appl Mater Interfaces ; 8(42): 28274-28282, 2016 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-26796978

RESUMEN

Catalysts for the oxygen reduction reaction (ORR) are highly important in fuel cells and metal-air batteries. Cheap ORR catalysts with ultrahigh electrochemical activity, selectivity, and stability are extremely desirable but still remain challenging. Herein, mesoporous NiCo2O4 nanoplate (NP) arrays on three-dimensional (3D) graphene foam are shown to be a highly economical ORR catalyst. This mesoporous mixed-valence oxide can provide more electrocatalytic active sites with increased accessible surface area. In addition, graphene-foam-supported NiCo2O4 NP arrays have a 3D hierarchical porous structure, which is of great benefit to ion diffusion and electron transfer. As a result, the mesoporous NiCo2O4 NP arrays/graphene foam catalyst exhibits outstanding ORR performance with the four-electron reduction of O2 to H2O in alkaline media. Furthermore, the mesoporous catalyst shows enhanced electrocatalytic activity with a half-wave potential of 0.86 V vs RHE and better stability compared with a commercial Pt/C catalyst.

13.
Sci Rep ; 5: 12005, 2015 Jul 20.
Artículo en Inglés | MEDLINE | ID: mdl-26189944

RESUMEN

N-aryl imidazoles play an important role as structural and functional units in many natural products and biologically active compounds. Herein, we report a photocatalytic route for the C-N cross-coupling reactions over a Cu/graphene catalyst, which can effectively catalyze N-arylation of imidazole and phenylboronic acid, and achieve a turnover frequency of 25.4 h(-1) at 25°C and the irradiation of visible light. The enhanced catalytic activity of the Cu/graphene under the light irradiation results from the localized surface plasmon resonance of copper nanoparticles. The Cu/graphene photocatalyst has a general applicability for photocatalytic C-N, C-O and C-S cross-coupling of arylboronic acids with imidazoles, phenols and thiophenols. This study provides a green photocatalytic route for the production of N-aryl imidazoles.


Asunto(s)
Ácidos Borónicos/química , Cobre/química , Grafito/química , Imidazoles/química , Luz , Catálisis
14.
ACS Appl Mater Interfaces ; 7(8): 4772-7, 2015 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-25664816

RESUMEN

NiO nanoparticles are deposited onto SiC particles by atomic layer deposition (ALD). The structure of the NiO/SiC hybrid material is investigated by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The size of the NiO nanoparticles is flexible and can be adjusted by altering the cycle number of the NiO ALD. Electrochemical measurements illustrate that NiO/SiC prepared with 600 cycles for NiO ALD exhibits the highest glucose sensing ability in alkaline electrolytes with a low detection limit of 0.32 µM (S/N = 3), high sensitivity of 2.037 mA mM(-1) cm(-2), a linear detection range from approximately 4 µM to 7.5 mM, and good stability. Its sensitivity is about 6 times of that for commercial NiO nanoparticles and NiO/SiC nanocomposites prepared by a traditional incipient wetness impregnation method. It is revealed that the superior electrochemical ability of ALD NiO/SiC is ascribed to the strong interaction between NiO and the SiC substrate and the high dispersity of NiO nanoparticles on the SiC surface. These results suggest that ALD is an effective way to deposit NiO on SiC for nonenzymatic glucose sensing.


Asunto(s)
Compuestos Inorgánicos de Carbono/química , Técnicas Electroquímicas , Glucosa/análisis , Nanocompuestos/química , Níquel/química , Compuestos de Silicona/química , Técnicas Biosensibles , Nanocompuestos/ultraestructura , Espectroscopía de Fotoelectrones
15.
Nanoscale ; 6(12): 6692-700, 2014 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-24816496

RESUMEN

Vertically oriented TiO2 nanotube arrays (TNTAs) were conformally coated with an ultrathin nitrogen-doped (N-doped) carbon film via the carbonization of a polyimide film deposited by molecular layer deposition and simultaneously hydrogenated, thereby creating a core/shell nanostructure with a precisely controllable shell thickness. The core/shell nanostructure provides a larger heterojunction interface to substantially reduce the recombination of photogenerated electron-hole pairs, and hydrogenation enhances solar absorption of TNTAs. In addition, the N-doped carbon film coating acts as a high catalytic active surface for oxygen evolution reaction, as well as a protective film to prevent hydrogen-treated TiO2 nanotube oxidation by electrolyte or air. As a result, the N-doped carbon film coated TNTAs displayed remarkably improved photocurrent and photostability. The TNTAs with a N-doped carbon film of ∼ 1 nm produces a current density of 3.6 mA cm(-2) at 0 V vs. Ag/AgCl under the illumination of AM 1.5 G (100 mW cm(-2)), which represents one of the highest values achieved with modified TNTAs. Therefore, we propose that ultrathin N-doped carbon film coating on materials is a viable approach to enhance their PEC water splitting performance.

16.
Ying Yong Sheng Tai Xue Bao ; 25(1): 263-71, 2014 Jan.
Artículo en Chino | MEDLINE | ID: mdl-24765870

RESUMEN

Dynamic global vegetation model (DGVM) is an important and efficient tool for study on the terrestrial carbon circle processes and vegetation dynamics. This paper reviewed the development history of DGVMs, introduced the basic structure of DGVMs, and the outlines of several world-widely used DGVMs, including CLM-DGVM, LPJ, IBIS and SEIB. The shortages of the description of dynamic vegetation mechanisms in the current DGVMs were proposed, including plant functional types (PFT) scheme, vegetation competition, disturbance, and phenology. Then the future research directions of DGVMs were pointed out, i. e. improving the PFT scheme, refining the vegetation dynamic mechanism, and implementing a model inter-comparison project.


Asunto(s)
Modelos Teóricos , Plantas , Ciclo del Carbono , Monitoreo del Ambiente , Predicción
17.
Angew Chem Int Ed Engl ; 53(7): 1973-7, 2014 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-24505013

RESUMEN

Copper is a low-cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible-light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm(-2) ) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the NO bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.

18.
Chem Commun (Camb) ; 50(2): 228-30, 2014 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-24226624

RESUMEN

A novel C-Ni-SiC composite using sawtooth-like SiC as support and carbon as modified material was prepared by hydrothermal synthesis and thermochemical pyrolysis. As a supercapacitor electrode, it exhibits very high specific capacitance (1780 F g(-1)) and excellent cycling performance (>96% for 2500 cycles).

19.
Nanotechnology ; 24(47): 475602, 2013 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-24192455

RESUMEN

Highly-qualified graphene was prepared by the ultrasonic exfoliation of commercial expanded graphite (EG) under the promotion of (NH4)2CO3 decomposition. The yield of graphene from the first exfoliation is 7 wt%, and it can be increased to more than 65 wt% by repeated exfoliations. Atomic force microscopy, x-ray photoelectron spectroscopy and Raman analysis show that the as-prepared graphene only has a few defects or oxides, and more than 95% of the graphene flakes have a thickness of ~1 nm. The electrochemical performance of the as-prepared graphene is comparable to reduced graphene oxide in the determination of dopamine (DA) from the mixed solution of ascorbic acid, uric acid and DA. These results show that the decomposition of (NH4)2CO3 molecules in the EG layers under ultrasonication promotes the exfoliation of graphite and provides a low-priced route for large scale production of highly-quality graphene.


Asunto(s)
Carbonatos/química , Grafito/química , Ultrasonido/métodos , Ácido Ascórbico/análisis , Dopamina/análisis , Técnicas Electroquímicas , Electrodos , Microscopía de Fuerza Atómica , Espectroscopía de Fotoelectrones , Soluciones , Espectrometría Raman , Ácido Úrico/análisis , Agua/química
20.
Phys Chem Chem Phys ; 15(38): 16104-10, 2013 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-23986025

RESUMEN

A carbon coated Co-SiC nanocomposite was fabricated via in situ pyrolysis of methane on a hierarchical Co3O4-SiC nanostructure, which was obtained by hydrothermal synthesis. By the reduction of methane, the Co3O4 was in situ converted to cobalt nanoparticles, and coated by carbon or filled in the CNTs. The as-prepared composite exhibits excellent microwave absorption performance in the frequency range of 2-18 GHz. When the match thickness is 1.8 mm, the composite has a reflection loss value below -10 dB in the range 12.2 to 18 GHz, which nearly covers the whole Ku-band (12-18 GHz). When the thickness is 2.6 mm, the reflection loss value below -10 dB distributes at 8.2-11.5 GHz, covering most of the X-band (8-12 GHz). Moreover, by further tuning the match thickness, the composite can selectively absorb some certain frequency bands of microwaves.

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