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1.
Anal Chem ; 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38324759

RESUMO

Point-of-care testing (POCT) has attracted great interest because of its prominent advantages of rapidness, precision, portability, and real-time monitoring, thus becoming a powerful biomedical device in early clinical diagnosis and convenient medical treatments. However, its complicated manufacturing process and high expense severely impede mass production and broad applications. Herein, an innovative but inexpensive integrated sandwich-paper three-dimensional (3D) cell sensing device is fabricated to in situ wirelessly detect H2O2 released from living cells. The paper-based electrochemical sensing device was constructed by a sealed sandwiched bottom plastic film/fiber paper/top hole-centered plastic film that was printed with patterned electrodes. A new (Fe, Mn)3(PO4)2/N-doped carbon nanorod was developed and immobilized on the sensing carbon electrode while cell culture solution filled the exposed fiber paper, allowing living cells to grow on the fiber paper surrounding the electrode. Due to the significantly shortening diffusion distance to access the sensing sites by such a unique device and a rationally tuned ratio of Fe2+/Mn2+, the device exhibits a fast response time (0.2 s), a low detection limit (0.4 µM), and a wide detection range (2-3200 µM). This work offers great promise for a low-cost and highly sensitive POCT device for practical clinic diagnosis and broad POCT biomedical applications.

2.
Anal Chem ; 96(19): 7609-7617, 2024 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-38687631

RESUMO

MicroRNAs (miRNAs) play vital roles in biological activities, but their in vivo imaging is still challenging due to the low abundance and the lack of efficient fluorescent tools. RNA aptamers with high affinity and low background emerge for bioimaging yet suffering from low brightness. We introduce a rational design based on target-mediated entropy-driven toehold exchange (EDTE) to induce the release of RNA aptamer and subsequently light up corresponding fluorophore, which achieves selective imaging of miRNAs with good stability in both living cells and tumor-bearing mouse. Through tailoring recognition unit of the EDTE probes, highly sensitive imaging of different miRNAs including miRNA-125b and miRNA-21 is achieved, confirming its universal bioimaging applications. In comparison with the reported "one-to-one" model, the EDTE strategy shows a remarkable 4.6-time improvement in signal/noise ratio for intracellular imaging of the same miRNA. Particularly, it realizes sensitive imaging of miRNA in vivo, providing a promising tool in investigating functions and interactions of disease-associated miRNAs.


Assuntos
Aptâmeros de Nucleotídeos , Entropia , Corantes Fluorescentes , MicroRNAs , MicroRNAs/análise , MicroRNAs/metabolismo , Aptâmeros de Nucleotídeos/química , Animais , Corantes Fluorescentes/química , Camundongos , Humanos , Imagem Óptica , Camundongos Nus
3.
Small ; : e2403719, 2024 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-38973092

RESUMO

Metal phosphides with easy synthesis, controllable morphology, and high capacity are considered as potential anodes for sodium-ion batteries (SIBs). However, the inherent shortcomings of metal phosphating materials, such as conductivity, kinetics, volume strain, etc are not satisfactory, which hinders their large-scale application. Here, a CoP@carbon nanofibers-composite containing rich Co─N─C heterointerface and phosphorus vacancies grown on carbon cloth (CoP1-x@MEC) is synthesized as SIB anode to accomplish extraordinary capacity and ultra-long cycle life. The hybrid composite nanoreactor effectively impregnates defective CoP as active reaction center while offering Co─N─C layer to buffer the volume expansion during charge-discharge process. These vast active interfaces, favored electrolyte infiltration, and a well-structured ion-electron transport network synergistically improve Na+ storage and electrode kinetics. By virtue of these superiorities, CoP1-x@MEC binder-free anode delivers superb SIBs performance including a high areal capacity (2.47 mAh cm-2@0.2 mA cm-2), high rate capability (0.443 mAh cm-2@6 mA cm-2), and long cycling stability (300 cycles without decay), thus holding great promise for inexpensive binder-free anode-based SIBs for practical applications.

4.
Small ; : e2400700, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38488718

RESUMO

Solar-driven carbon dioxide (CO2 ) methanation holds significant research value in the context of carbon emission reduction and energy crisis. However, this eight-electron catalytic reaction presents substantial challenges in catalytic activity and selectivity. In this regard, researchers have conducted extensive exploration and achieved significant developments. This review provides an overview of the recent advances and challenges in efficient selective photocatalytic CO2 methanation. It begins by discussing the fundamental principles and challenges in detail, analyzing strategies for improving the efficiency of photocatalytic CO2 conversion to CH4 comprehensively. Subsequently, it outlines the recent applications and advanced characterization methods for photocatalytic CO2 methanation. Finally, this review highlights the prospects and opportunities in this area, aiming to inspire CO2 conversion into high-value CH4 and shed light on the research of catalytic mechanisms.

5.
Small ; 20(1): e2304938, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37649198

RESUMO

Materials with various single-transition metal atoms dispersed in nitrogenated carbons (M─N─C, M = Fe, Co, and Ni) are synthesized as cathodes to investigate the electrocatalytic behaviors focusing on their enhancement mechanism for performance of Li-S batteries. Results indicate that the order of both electrocatalytic activity and rate capacity for the M─N─C catalysts is Co > Ni > Fe, and the Co─N─C delivers the highest capacity of 1100 mAh g-1 at 1 C and longtime stability at a decay rate of 0.05% per cycle for 1000 cycles, demonstrating excellent battery performance. Theoretical calculations for the first time reveal that M─N─N─C catalysts enable direct conversion of Li2 S6 to Li2 S rather than Li2 S4 to Li2 S by stronger adsorption with Li2 S6 , which also has an order of Co > Ni > Fe. And Co─N─C has the strongest adsorption energy, not only rendering the highest electrocatalytic activity, but also depressing the polysulfides' dissolution into electrolyte for the longest cycle life. This work offers an avenue to design the next generation of highly efficient sulfur cathodes for high-performance Li-S batteries, while shedding light on the fundamental insight of single metal atomic catalytic effects on Li-S batteries.

6.
Small ; : e2402076, 2024 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-38757424

RESUMO

High-rate lithium/sodium ion batteries or capacitors are the most promising functional units to achieve fast energy storage that highly depends on charge host materials. Host materials with lamellar structures are a good choice for hybrid charge storage hosts (capacitor or redox type). Emerging layered transition metal carbo-chalcogenides (TMCC) with homogeneous sulfur termination are especially attractive for charge storage. Using density functional theory calculations, six of 30 potential TMCC are screened to be stable, metallic, anisotropic in electronic conduction and mechanical properties due to the lamellar structures. Raman, infrared active modes and frequencies of the six TMCC are well assigned. Interlayer coupling, especially binding energies predict that the bulk layered materials can be easily exfoliated into 2D monolayers. Moreover, Ti2S2C, Zr2S2C are identified as the most gifted Li+/Na+ anode materials with relatively high capacities, moderate volume expansion, relatively low Li+/Na+ migration barriers for batteries or ion-hybrid capacitors. This work provides a foundation for rational materials design, synthesis, and identification of the emerging 2D family of TMCC.

7.
Chemphyschem ; 25(11): e202400141, 2024 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-38462507

RESUMO

The most challenging obstacle for photocatalysts to efficiently harvest solar energy is the sluggish surface redox reaction (e. g., oxygen evolution reaction, OER) kinetics, which is believed to originate from interface catalysis rather than the semiconductor photophysics. In this work, we developed a light-modulated transient photocurrent (LMTPC) method for investigating surface charge accumulation and reaction on the W-doped bismuth vanadate (W : BiVO4) photoanodes during photoelectrochemical water oxidation. Under illuminating conditions, the steady photocurrent corresponds to the charge transfer rate/kinetics, while the integration of photocurrent (I~t) spikes during the dark period is regarded as the charge density under illumination. Quantitative analysis of the surface hole densities and photocurrents at 0.6 V vs. reversible hydrogen electrode results in an interesting rate-law kinetics switch: a 3rd-order charge reaction behavior appeared on W : BiVO4, but a 2nd-order charge reaction occurred on W : BiVO4 surface modified with ultrathin Bi metal-organic-framework (Bi-MOF). Consequently, the photocurrent for water oxidation on W : BiVO4/Bi-MOF displayed a 50 % increment. The reaction kinetics alternation with new interface reconstruction is proposed for new mechanism understanding and/or high-performance photocatalytic applications.

8.
Mikrochim Acta ; 191(5): 243, 2024 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-38575711

RESUMO

PEDOT: PSS has been used as a biomimetic uric acid (UA) sensor but suffers from unfortunate low detection limit (LOD), narrow detection range and poor stability. Herein, we get graphdiyne (GDY) marry PEDOT:PSS to create a very stable GDY@PEDOT:PSS heterostructure for a biomimetic UA sensor, which accomplishes the lowest LOD (6 nM), the widest detection range (0.03 µM-7 mM) and the longest stability (98.1% for 35 days) among the related UA sensors. The sensor was successfully used to in situ real-time detection of  UA in sweat. The enhancement mechanisms of the sensor were investigated, and results discover that C≡C of GDY and C = C of PEDOT:PSS can cross-link each other by π-π interactions, making not only the former strongly resistant against oxidation deterioration, but also causes the latter to efficiently prevent water swelling of polymer for poor conductivity, thereby leading to high stability from both components. While the stabilized heterostructure can also offer more active sites by enhanced absorption of UA via π-π interactions for highly sensitive detection of UA. This work holds great promise for a practical sweat UA sensor while providing scientific insight to design a stable and electrocatalytically active structure from two unstable components.


Assuntos
Grafite , Suor , Ácido Úrico , Limite de Detecção
9.
Anal Chem ; 94(41): 14109-14117, 2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-35727990

RESUMO

Single-atom catalysis is mainly focused on its dispersed high-density catalytic sites, but delicate designs to realize a unique catalysis mechanism in terms of target reactions have been much less investigated. Herein an iron single atomic site catalyst anchored on 2-D N-doping graphene (Fe-SASC/G) was synthesized and further employed as a biomimetic sensor to electrochemically detect hydrogen peroxide, showing an extremely high sensitivity of 3214.28 µA mM-1 cm-2, which is much higher than that (6.5 µA mM-1 cm-2) of its dispersed on 1-D carbon nanowires (Fe-SASC/NW), ranking the best sensitivity among all reported Fe based catalyst at present. The sensor was also used to successfully in situ monitor H2O2 released from A549 living cells. The mechanism was further systematically investigated. Results interestingly indicate that the distance between adjacent single Fe atomic catalytic sites on 2-D graphene of Fe-SASC/G matches statistically well with the outer length of bioxygen of H2O2 to promote a bridge adsorption of -O-O- for simultaneous 2-electron transfer, while the single Fe atoms anchored on distant 1-D nanowires in Fe-SASC/NW only allow an end-adsorption of oxygen atoms for 1-electron transfer. These results demonstrate that Fe-SASC/G holds great promise as an advanced electrode material in selective and sensitive biomimetic sensor and other electrocatalytic applications, while offering scientific insights in deeper single atomic catalysis mechanisms, especially the effects of substrate dimensions on the mechanism.


Assuntos
Grafite , Adsorção , Biomimética , Carbono , Peróxido de Hidrogênio , Ferro , Oxigênio
10.
Small ; 18(7): e2105376, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34866341

RESUMO

Renewable solar-driven carbon dioxide (CO2 ) conversion to highly valuable fuels is an economical and prospective strategy for both the energy crisis and ecological environment disorder. However, the selectivity and activity of current photocatalysts have great room for improvement due to the diversification and complexity of products. Here, an ambient-stable 2D/2D Co2 P@BP/g-C3 N4 heterojunction is designed for highly selective and efficient photocatalytic CO2 reduction reaction. The resulting Co2 P@BP/g-C3 N4 material has a remarkable conversion of CO2 to carbon monoxide (CO) with an ≈96% selectivity, coupled with a dramatically increased CO generation rate of 16.21 µmol g-1 h-1 , which is 5.4 times higher than pristine graphitic carbon nitride (g-C3 N4 ). In addition, this photocatalyst exhibits good ambient stability of black phosphorus (BP) without oxidation even over 180 days. The excellent photocatalytic selectivity and activity of Co2 P@BP/g-C3 N4 heterojunction are attributed to its lower energy barriers of *COOH, *CO, and *+CO in the process of CO2 reduction, coupled with rapid charge transfer at the heterointerfaces of BP/g-C3 N4 and Co2 P/BP. This is solidly verified by both density functional theory calculation and mechanism experiments. Therefore, this work holds great promise for an ambient-stable efficient and high selectivity photocatalyst in solar-driven CO2 conversion.

11.
Small ; 18(2): e2103866, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34870367

RESUMO

3D ZIF-67-particles-impregnated cellulose-nanofiber nanosheets with oriented macropores are synthesized via directional-freezing-assisted in situ self-assembly, and converted to 3D CoP-nanoparticle (NP)-embedded hierarchical, but macropores-oriented, N-doped carbon nanosheets via calcination and phosphidation. The obtained nanoarchitecture delivers overpotentials at 10 and 50 mA cm-2 and Tafel slope of 82.1 and 113.4 mV and 40.8 mV dec-1 in 0.5 M H2 SO4 , and of 97.1 and 136.6 mV and 51.2 mV dec-1 in 1 M KOH, all of which are superior to those of the most reported non-noble-metal-based hydrogen evolution reaction (HER) catalysts. This catalyst even surpasses commercial Pt/C for a much lower overpotential at high current densities, which is essential for large-scale hydrogen production. Its catalytic activity can be further optimized to become one of the best in both 0.5 M H2 SO4 and 1 M KOH. The outstanding catalytic activity is ascribed to the uniformly-dispersed small CoP NPs in the 3D carbon sheets and the hierarchical nanostructure with rich oriented pores. This work develops a facile, economical, and universal self-assembly strategy to fabricate uniquely nanostructured hybrids to simultaneously promote charge transfer and mass transport, and also offers an inexpensive and high-performance HER catalyst toward industry-scale water splitting.

12.
Phys Chem Chem Phys ; 24(23): 14424-14429, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35648431

RESUMO

We innovatively used a polypropylene (PP) separator as a substrate and PEO-LiTFSI-SN as a paste to coat on both of the PP surfaces, and formed a sandwich-like solid polymer electrolyte (SPE). The SPE shows a conductivity of 4.22 × 10-3 S cm-1 at room temperature and 7.75 × 10-5 S cm-1 at 0 °C. The pyrene-4,5,9,10-tetraone (PTO)||SPE||Li battery shows a maximum discharge specific capacity of 187.8 mA h g-1 at a current density of 20 mA g-1 under 0 °C. After 100 cycles, the capacity could still be obtained at 88.4 mA h g-1, and the coulombic efficiency stayed stable at 98%. This work paved a new way for the development of solid-state organic batteries (SSOBs) at low temperatures.

13.
Anal Chem ; 93(31): 10789-10797, 2021 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-34212722

RESUMO

Single-atom catalysis efficiently exposes the catalytic sites to reactant molecules while rendering opportunity to investigate the catalysis mechanisms at atomic levels for scientific insights. Here, for the first time, atomically dispersed Co atoms are synthesized as biomimetic "enzymes" to monitor superoxide anions (O2•-), delivering ultraordinary high sensitivity (710.03 µA·µM-1·cm-2), low detection limit (1.5 nM), and rapid response time (1.2 s), ranking the best among all the reported either bioenzymatic or biomimetic O2•- biosensors. The sensor is further successfully employed to real-time monitor O2•- released from living cells. Moreover, theoretical calculation and analysis associated with experimental results discover that a mode of end adsorption of the negatively charged O2•- on the Co3+ atom rather than a bridge or/and side adsorption of the two atoms of O2•- on two Co3+ atoms, respectively, plays an important role in the single-atomic catalysis toward O2•- oxidation, which not only facilitates faster electron transfer but also offers better selectivity. This work holds great promise for an inexpensive and sensitive atomic biomimetic O2•- sensor for bioresearch and clinic diagnosis, while revealing that the adsorption mode plays a critical role in single-atom catalysis for a fundamental insight.


Assuntos
Técnicas Biossensoriais , Adsorção , Catálise , Oxirredução , Superóxidos
14.
Small ; 16(37): e2002988, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32776442

RESUMO

Photocatalysis technology using solar energy for hydrogen (H2 ) production still faces great challenges to design and synthesize highly efficient photocatalysts, which should realize the precise regulation of reactive sites, rapid migration of photoinduced carriers and strong visible light harvest. Here, a facile hierarchical Z-scheme system with ZnIn2 S4 /BiVO4 heterojunction is proposed, which can precisely regulate redox centers at the ZnIn2 S4 /BiVO4 hetero-interface by accelerating the separation and migration of photoinduced charges, and then enhance the oxidation and reduction ability of holes and electrons, respectively. Therefore, the ZnIn2 S4 /BiVO4 heterojunction exhibits excellent photocatalytic performance with a much higher H2 -evolution rate of 5.944 mmol g-1 h-1 , which is about five times higher than that of pure ZnIn2 S4 . Moreover, this heterojunction shows good stability and recycle ability, providing a promising photocatalyst for efficient H2 production and a new strategy for the manufacture of remarkable photocatalytic materials.

15.
Chemistry ; 26(71): 17091-17096, 2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-32734617

RESUMO

An Ru-doping strategy is reported to substantially improve both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalytic activity of Ni/Fe-based metal-organic framework (MOF) for overall water splitting. As-synthesized Ru-doped Ni/Fe MIL-53 MOF nanosheets grown on nickel foam (MIL-53(Ru-NiFe)@NF) afford HER and OER current density of 50 mA cm-2 at an overpotential of 62 and 210 mV, respectively, in alkaline solution with a nominal Ru loading of ≈110 µg cm-2 . When using as both anodic and cathodic (pre-)catalyst, MIL-53(Ru-NiFe)@NF enables overall water splitting at a current density of 50 mA cm-2 for a cell voltage of 1.6 V without iR compensation, which is much superior to state-of-the-art RuO2 -Pt/C-based electrolyzer. It is discovered that the Ru-doping considerably modulates the growth of MOF to form thin nanosheets, and enhances the intrinsic HER electrocatalytic activity by accelerating the sluggish Volmer step and improving the intermediate oxygen adsorption for increased OER catalytic activity.

16.
Phys Chem Chem Phys ; 22(4): 2115-2121, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31904063

RESUMO

MXenes represent a family of surface-functionalized two-dimensional (2D) carbides and nitrides with potential applications in the field of flexible electronics, which rely on their elasticity and flexibility. However, the knowledge on such aspects is rather limited. Here, taking the four most typical MXenes, namely, Ti2CTx, Ti3C2Tx, Nb2CTx and Nb4C3Tx (T = O, OH and F) as examples, we evaluate their intrinsic in-plane stiffness and out-of-plane rigidity at the nanoscale with respect to their functional groups, chemical components and thickness by first-principles calculations. We find that both the in-plane stiffness (C) and out-of-plane bending rigidity (D) of MXenes are highly dependent on the thickness of MX and the surface functional groups. Specifically, the thickness and surface functionalization increase C and D significantly. The Foppl-von Karman numbers per area (C/D), as the flexibility descriptor, of MXenes are comparable with that of the MoS2 monolayer, indicating MXenes as a class of strong yet bendable materials. The effective thickness, the critical parameter bridging C and D, of MXenes is determined to be only two-thirds of the average layer spacing. This study provides a fundamental basis for quantifying the rigidity of MXenes at the nanoscale.

17.
BMC Cardiovasc Disord ; 20(1): 229, 2020 05 18.
Artigo em Inglês | MEDLINE | ID: mdl-32423380

RESUMO

BACKGROUND: To explore why bicuspid aortic stenosis has certain clinical differences from the tricuspid morphology, we evaluated the metabolomics profile involved in bicuspid aortic valve (BAV) aortic stenosis prior to and after transcatheter aortic valve replacement (TAVR) in comparison with tricuspid aortic valve (TAV). METHODS: In this TAVR cohort with prospectively collected data, blood samples were obtained before TAVR valve deployment and at the 7th day after TAVR, which were then sent for liquid and gas chromatography-mass spectrometry detection. Besides comparisons between BAV and TAV, BAV patients were also divided in subgroups according to baseline hemodynamics (i.e. maximal transaortic velocity, Vmax) and post-procedural reverse left ventricular (LV) remodeling (i.e. the change in LV mass index from baseline, ∆LVMI) for further analysis. Metabolic differences between groups were identified by integrating univariate test, multivariate analysis and weighted correlation network analysis algorithm. RESULTS: A total of 57 patients were enrolled including 33 BAV patients. The BAV group showed lower arginine and proline metabolism both before and post TAVR than TAV represented by decreased expression of L-Glutamine. In BAV subgroup analysis, patients with baseline Vmax > 5 m/s (n = 11) or the 4th quartile of change in ∆LVMI at one-year follow-up (i.e. poorly-recovered LV, n = 8) showed elevated arachidonic acid metabolism compared with Vmax < 4.5 m/s (n = 12) or the 1st quartile of ∆LVMI (i.e. well-recovered LV, n = 8) respectively. CONCLUSIONS: Difference in arginine and proline metabolism was identified between BAV and TAV in TAVR recipients. Elevated arachidonic acid metabolism may reflect more severe baseline hemodynamics and worse LV reserve remodeling after TAVR in BAV.


Assuntos
Estenose da Valva Aórtica/cirurgia , Valva Aórtica/anormalidades , Metabolismo Energético , Doenças das Valvas Cardíacas/cirurgia , Metabolômica , Substituição da Valva Aórtica Transcateter , Idoso , Valva Aórtica/fisiopatologia , Valva Aórtica/cirurgia , Estenose da Valva Aórtica/sangue , Estenose da Valva Aórtica/etiologia , Estenose da Valva Aórtica/fisiopatologia , Ácido Araquidônico/sangue , Arginina/sangue , Doença da Válvula Aórtica Bicúspide , Biomarcadores/sangue , Feminino , Doenças das Valvas Cardíacas/sangue , Doenças das Valvas Cardíacas/complicações , Doenças das Valvas Cardíacas/fisiopatologia , Hemodinâmica , Humanos , Masculino , Prolina/sangue , Estudos Prospectivos , Recuperação de Função Fisiológica , Substituição da Valva Aórtica Transcateter/efeitos adversos , Resultado do Tratamento , Função Ventricular Esquerda , Remodelação Ventricular
18.
Antonie Van Leeuwenhoek ; 113(2): 293-301, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31583494

RESUMO

A Gram-stain negative, aerobic, non-flagellated, non-gliding, rod-shaped bacterium, designated strain YLY04T, was isolated from the gut microflora of a sea bass (Dicentrarchus labrax L.) collected from the coast of Yuanyao Wharf, Weihai, China. Growth was found to occur at pH 6.0-9.0 (optimum, 7.0-8.0), 4-37 °C (optimum, 28-30 °C) in the presence of 0-11.0% (w/v) NaCl (optimum, 3.0-4.0%). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YLY04T is closely related to Pelagivirga sediminicola BH-SD19T and Roseovarius antarcticus M-S13-148T. Strain YLY04T contains ubiquinone-10 as the sole respiratory quinone and summed feature 8 (C18:1ω7c and/or C18:1ω6c), cyclo-C19:0ω8c, C16:0 and 11-methyl-C18:1ω7c as the major fatty acids. The polar lipids of strain YLY04T were found to consist of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, an unidentified aminolipid, an unidentified phospholipid and three unidentified lipids. The DNA G+C content was determined to be 62.7 mol%. The phenotypic, chemotaxonomic and phylogenetic properties, and genome analysis, indicated that strain YLY04T represents a novel species within the genus Pelagivirga, for which the name Pelagivirga dicentrarchi sp. nov. is proposed. The type strain is YLY04T (= MCCC 1H00334T = KCTC 62452T).


Assuntos
Bass/microbiologia , Ácidos Graxos/metabolismo , Rhodobacteraceae/genética , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , Bass/genética , DNA Bacteriano/genética , Microbioma Gastrointestinal , Genótipo , Fosfolipídeos/metabolismo , Filogenia , RNA Ribossômico 16S/genética , Rhodobacteraceae/classificação , Análise de Sequência de DNA
19.
J Chem Phys ; 153(7): 074701, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32828088

RESUMO

Using a polymer-masking approach, we have developed metal-free 2D carbon electrocatalysts based on single-layer graphene with and without punched holes and/or N-doping. A combined experimental and theoretical study on the resultant 2D graphene electrodes revealed that a single-layer graphene sheet exhibited a significantly higher electrocatalytic activity at its edge than that over the surface of its basal plane. Furthermore, the electrocatalytic activity of a single-layer 2D graphene sheet was significantly enhanced by simply punching microholes through the graphene electrode due to the increased edge population for the hole-punched graphene electrode. In a good consistency with the experimental observations, our density function theory calculations confirmed that the introduction of holes into a graphene sheet generated additional positive charge along the edge of the punched holes and hence the creation of more highly active sites for the oxygen reduction reaction. The demonstrated concept for less graphene material to be more electrocatalytically active shed light on the rational design of low-cost, but efficient electrocatalysts from 2D graphene for various potential applications ranging from electrochemical sensing to energy conversion and storage.

20.
Molecules ; 25(14)2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32650504

RESUMO

In order to improve the mechanical and dielectric properties of radome cyanate, a synergistic reinforcement method is employed to develop a resin-based ternary-composite with high heat-resistance and preferable radar-band transmission, which is expected to be applied to fabricate radomes capable of resisting high temperature and strong electric field. According to copolymerization characteristics and self-curing mechanism, epoxy resin (EP) and bismaleimide (BMI) are employed as reinforcements mixed into a cyanate ester (CE) matrix to prepare CE/BMI/EP composites of a heat-resistant radome material by high-temperature viscous-flow blending methods under the catalysis of aluminum acetylpyruvate. The crystallization temperature, transition heat, and reaction rate of cured polymers were tested to analyze heat-resistance characteristics and evaluate material synthesis processes. Scanning electron microscopy was used to characterize the micro-morphology of tensile fracture, which was combined with the tensile strength test and dynamic thermomechanical analysis to investigate the composite modifications on tenacity and rigidity. Weibull statistics were performed to analyze the experimental results of the dielectric breakdown field, and the dielectric-polarization and wave-transmission performances were investigated according to alternative current dielectric spectra. Compared with the pure CE and the CE composites individually reinforced by EP or BMI, the CE/BMI/EP composite acquires the most significant amelioration in both the mechanical and electrical insulation performances as indicated by the breaking elongation and dielectric breakdown strength being simultaneously improved by 40%, which are consistently manifested by the obviously increased transverse lines uniformly distributed on the fracture cross-section. Furthermore, the glass-transition temperature of CE/BMI/EP composite reaches the highest values of nearly 300 °C, with the relative dielectric constant and dielectric loss being mostly reduced to less than 3.2 and 0.01, respectively. The experimental results demonstrate that the CE/BMI/EP composite is a highly-qualified wave-transmission material with preferences in mechanical, thermostability, and electrical insulation performances, suggesting its prospective applications in low-frequency transmittance radomes.


Assuntos
Cianatos/química , Resinas Epóxi/química , Teste de Materiais , Temperatura Alta , Propriedades de Superfície
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