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1.
Small ; : e2001686, 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32521107

RESUMO

Herein, a supermolecular-scale cage-confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO2 nanoparticles are sandwiched uniformly between porous carbon shells and reduced graphene oxide (RGO). Both sandwich structures are derived from hybrid hydrogels doped by two different crosslinkers (with/without oxygen bridge), which can precisely confine Mo source (e.g., PMo12 ). Without adding magnetic components, both absorbents exhibit excellent low frequency absorption performance in combination with electrically tunable ability and enhanced reflection loss value, which is superior over other relative 2D dielectric absorbers and satisfies the requirements of portable electronics. Notably, introducing oxygen bridges in the crosslinker generates a more stable confining configuration, which in turn renders its corresponding derivative exhibiting an extra multifrequency electromagnetic wave absorption trait. The intrinsic electromagnetic wave adjustment mechanism of the ternary hybrid absorbent is also explored. The result reveals that the elevated electromagnetic wave absorbing property is attributed to moderate attenuation constant and glorious impendence matching. The cage-confinement pyrolysis route to fabricate 2D MoO2 -based dielectric electromagnetic wave absorbents opens a new path for the design of electromagnetic wave absorbents used in multi/low frequency.

2.
Nanoscale ; 2020 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-32297884

RESUMO

Herein, we realized the supramolecular confinement of a single polyoxometalate (POM) cluster precisely in a polypyrrole (PPy) hydrogel-wrapped CNT framework with molecular-scale cages. This hybrid hydrogel framework demonstrated an ultra-high loading (67.5 wt%) and extremely uniform dispersion of individual of H3[P(Mo3O10)4] (PMo12) molecules, as demonstrated by sub-ångström-resolution HAADF-STEM. Consequently, it exhibited a better supercapacitor performance than that of the conventional composite system. The flexible solid-state supercapacitor exhibited a high energy density of 67.5 µW h cm-2 at a power density of 700 µW cm-2 and delivered a high capacitance retention of 85.7% after 3000 cycles. Moreover, the flexible device exhibited excellent mechanical stability. Density functional theory calculations revealed that the wrapped "fishnet-like" hydrogel creates a cage structure with a size of 1.8 nm for the precise storage of the PMo12 molecule (diameter = 1.05 nm), leading to the mono-dispersion of single PMo12 molecules on the hybrid hydrogel. The "caging" effect also activates the PMo12 molecule to enhance its charging/discharging performance by introducing new reactive sites for proton transfer. We believe that this design for suitable cage structures can be used for the construction of other POM-based hybrid hydrogels, thereby achieving mono-dispersity and performance enhancement.

3.
Chem Commun (Camb) ; 56(34): 4724-4727, 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32219295

RESUMO

Metal-organic frameworks (MOFs) for enzyme encapsulation-induced biomimetic mineralization under mild reaction conditions are commonly microporous and hydrophobic, which result in a rather high mass transfer resistance of the reactants and restrain the enzyme catalytic activity. Herein, we prepared a type of hierarchical porous and hydrophilic MOF through the biomimetic mineralization of enzymes, zinc ions, 2-methylimidazole, and lithocholic acid. The hierarchical porous structure accelerated the diffusion process of the reactants and the increased hydrophilicity conferred interfacial activity and increased the enzyme catalytic activity. The immobilized enzyme retained higher catalytic activity than the free enzyme and exhibited enhanced resistance to alkaline, organic, and high-temperature conditions. The nanobiocatalyst was reusable and showed long-term storage stability.

4.
J Phys Chem Lett ; : 3005-3013, 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32129627

RESUMO

Au is an ideal noble metal for use as an electrocatalyst for the ethanol oxidation reaction owing to its high performance-to-cost ratio. The catalyst usually exists as nanoparticles (NPs) for high surface area-to-volume ratio. In the present work, a nontraditional physical approach has been developed to fabricate ultrasmall and homogeneous single-crystalline Au NPs by ion bombardment in a precision ion polishing system. Transmission electron microscopy characterizations show that the Au NPs produced with 5 keV Ar+ are highly strained to form twinned crystals, which accumulate a large amount of surface energy, and this was found to be an underlying reason causing strong catalysis. Electrochemistry tests reveal that in alkaline medium the C1 pathway occurs much more preferentially with the strained Au NPs than the normal Au NPs. The surface area-to-volume ratio is no longer the only factor that affects the performance; instead, surface energy might play a more important role in enhancing the catalytic activities.

5.
Sci Adv ; 6(5): eaax5785, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32064336

RESUMO

Mimicking the cellular environment, metal-organic frameworks (MOFs) are promising for encapsulating enzymes for general applications in environments often unfavorable for native enzymes. Markedly different from previous researches based on bulk solution synthesis, here, we report the synthesis of enzyme-embedded MOFs in a microfluidic laminar flow. The continuously changed concentrations of MOF precursors in the gradient mixing on-chip resulted in structural defects in products. This defect-generating phenomenon enables multimodal pore size distribution in MOFs and therefore allows improved access of substrates to encapsulated enzymes while maintaining the protection to the enzymes. Thus, the as-produced enzyme-MOF composites showed much higher (~one order of magnitude) biological activity than those from conventional bulk solution synthesis. This work suggests that while microfluidic flow synthesis is currently underexplored, it is a promising strategy in producing highly active enzyme-MOF composites.

6.
Nanoscale ; 12(5): 3058-3067, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31971199

RESUMO

A material with diverse self-assembled morphologies is extremely important and highly desirable because such samples can provide tunable optical and electronic properties, which are critical in applications such as organic photovoltaics, microelectronics and bio-imaging. Moreover, the synthesis and controllable self-assembly of H-shaped bichromophoric perylenediimides (PDIs) are needed to advance these materials in organic photovoltaics, microelectronics and bio-imaging; however, this has remained a great challenge thus far. Here, we successfully synthesize a novel H-shaped bichromophoric PDI Gemini through the palladium-catalyzed coupling reaction. The as-prepared PDI Gemini exhibited unprecedented tunable self-assembly behavior in solution, yielding diverse low-dimensional superstructures, such as one-dimensional (1D) helices, two-dimensional (2D) rectangular nanocrystals, pyramid-shaped parallelograms, ultralarge micro-sheets, and uniform nanospheres, under different self-assembly conditions. Of particular interest, the 2D hierarchical superstructures along with their formation mechanisms represent the first finding in the self-assembly of PDI-based molecules. This study opens a new avenue for tunable self-assembly of conjugated molecules and affords opportunities for the fabrication of novel self-assembled optical and electronic materials based on PDI molecules.

7.
Nanotechnology ; 31(21): 215602, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31995529

RESUMO

In this paper, Co3Se4 nanoparticles embedded in nitrogen-doped porous carbon polyhedra are synthesized via a facile one-step thermal selenization, using zeolitic imidazolate framework-67 (ZIF-67) as the template. The electrochemical properties of the fabricated nanocomposite are evaluated for use as anodes for lithium ion batteries and found to exhibit a specific capacity (950 mAh g-1 at 0.2 C) and excellent cyclic stability (899 mAh g-1 at 1 C after 1000 cycles). Both are much higher than those of the state-of-the-art Co-Se based nanocomposites. This extraordinary lithium storage is attributed to the synergetic effect between the Co3Se4 nanocrystals and nitrogen-doped porous carbon framework, and is believed to offer a potential candidate anode material for next-generation lithium ion batteries.

9.
Small ; 16(15): e1902751, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31468669

RESUMO

Enzyme-metal hybrid catalysts (EMHCs), which combine enzymatic and metal catalysis, provide tremendous possibilities for new chemoenzymatic cascade reactions. Here, an overview of the representative achievements in the design of EMHCs and their applications in chemoenzymatic cascade reactions are presented. The preparation of hybrid catalysts is classified into two categories: coimmobilized enzyme-metal heterogeneous catalysts and carrier-free enzyme-metal bioconjugates. Examples of one-pot chemoenzymatic cascade processes catalyzed by the hybrid catalysts are then provided as potential applications. Finally, the limitations and future perspectives of EMHCs are discussed.

10.
Blood Adv ; 3(24): 4312-4325, 2019 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-31869417

RESUMO

The rate and extent of natural killer (NK)-cell education after hematopoietic cell transplantation correlates with leukemia control. To study the effect of donor and host HLA on NK-cell reconstitution, single killer-cell immunoglobulin-like receptor (KIR)+ NK cells (exhibiting KIR2DL1, KIR2DL2/KIR2DL3, or KIR3DL1 as their sole receptor) were grouped into 4 groups based on the interaction between donor/host HLA and donor inhibitory KIR in 2 cohorts (n = 114 and n = 276, respectively). On days 90 to 180 after transplantation, the absolute number and responsiveness against K562 cells (CD107a or interferon-γ expression) of single-KIR+ NK cells were higher in pairs where donor and host HLA both expressed ligands for donor inhibitory KIRs than in pairs where 1 or both of the donor and recipient HLA lacked at least 1 KIR ligand. NK-cell responsiveness was tuned commensurate with the number of inhibitory receptors from the donor. When both donor and host expressed the 3 major KIR ligands (HLA-C1, HLA-C2, and HLA-Bw4), NK cells expressing 3 inhibitory receptors (KIR2DL1/2DL3/3DL1) reached the maximum responsiveness against K562 cells compared with those NK cells expressing only 1 or 2 inhibitory receptors. When donor and host HLA both expressed all ligands for donor inhibitory KIRs, patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) showed the lowest recurrence rate after haploidentical hematopoietic stem cell transplantation (haplo-HSCT). In conclusion, this study demonstrates that when both donors and hosts present all the KIR ligands for donor KIRs, reconstituted NK cells achieve better functional education and contribute to least relapse among patients. This observation study was registered at www.clinicaltrials.gov as #NCT02978274.

11.
ACS Appl Mater Interfaces ; 11(44): 41229-41237, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31613588

RESUMO

Traditional vanadium dioxide (VO2) material faced severe challenges of low stability in acid, humid, and oxygenic environments, which hinder its real applications. Here, we report a facile improving process which can enhanced the stability of VO2 nanocrystals in the environments above. Ascorbic acid (AA), as an important antioxidant for organism in medicine and biology, was ingeniously used for enhancing the antioxidation abilities of inorganic material. At the same time, the AA could generate the hydrogen doping occurred on the surface of VO2 nanocrystals, which enhanced their Antiacid abilities simultaneously. The AA treated VO2 nanocrystals retain stable in H2SO4 and H2O2 solution and exhibit high durability in hyperthermal (60 °C) and humid (90%) environment. Characterizations and first-principles theoretical calculations confirmed that the coordination of ascorbic acid molecules on VO2 nanocrystals induced charge-carrier density reorganization and protons transferring electrostatically. Then the formed HxVO2 provides an enhancing formation energy for oxygen vacancy and protects the particles from corrosion. This work is beneficial to the VO2 nanoparticles coated and decorated processes and exhibit good potential for practical application of VO2-based smart windows.

12.
Small ; 15(49): e1903188, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31650707

RESUMO

Conjugated coordination polymers have become an emerging category of redox-active materials. Although recent studies heavily focus on the tailoring of metal centers in the complexes to achieve stable electrochemical performance, the effect on different substitutions of the bridging bonds has rarely been studied. An innovative tailoring strategy is presented toward the enhancement of the capacity storage and the stability of metal-organic conjugated coordination polymers. Two nanostructured d-π conjugated compounds, Ni[C6 H2 (NH)4 ]n (Ni-NH) and Ni[C6 H2 (NH)2 S2 ]n (Ni-S), are evaluated and demonstrated to exhibit hybrid electrochemical processes. In particular, Ni-S delivers a high reversible capacity of 1164 mAh g-1 , an ultralong stability up to 1500 cycles, and a fully recharge ability in 67 s. This tailoring strategy provides a guideline to design future effective conjugated coordination-polymer-based electrodes.

13.
iScience ; 19: 976-985, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31522120

RESUMO

BiVO4 is a promising photoanode material for solar-assisted water splitting in a photoelectrochemical cell but has a propensity to degrade. Investigations carried out here in 0.1 M Na2SO4 electrolyte showed that degradation is by dissolution of V in the electrolyte while Bi is retained on the anode probably in the form of solid Bi oxide (Bi2O3, Bi4O7). Accumulation of Bi oxide on the anode surface leads to passivation from further degradation. Thermodynamic modeling of possible degradation reactions has provided theoretical support to this mechanism. This self-passivation is accompanied by a decrease in photocurrent density, but it protects the anode against extensive photocorrosion and contributes to long-term stability. This is a more definitive understanding of degradation of BiVO4 during water splitting in a photoelectrochemical cell. This understanding is imperative for both fundamental and applied research.

14.
Org Lett ; 21(16): 6539-6542, 2019 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-31364857

RESUMO

Talaromyolides A-D (1-4) and talaromytin (5) were isolated from a marine fungus Talaromyces sp. CX11. Their structures were unambiguously determined by nuclear magnetic resonance (NMR), mass spectrometry, X-ray crystallography experiments, and time-dependent density functional theory electronic circular dichroism calculations. Talaromyolides A and D represent two novel carbon skeletons. Talaromytin exhibits two slowly interconverting conformers in DMSO-d6 and CH3OH-d4 that were studied by temperature-dependent NMR experiments. Talaromyolide D exhibits potent antiviral activity against pseudorabies virus (PRV) with a CC50 value of 3.35 µM.

15.
Nat Commun ; 10(1): 3037, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31292435

RESUMO

The Boltzmann distribution of electrons sets a fundamental barrier to lowering energy consumption in metal-oxide-semiconductor field-effect transistors (MOSFETs). Negative capacitance FET (NC-FET), as an emerging FET architecture, is promising to overcome this thermionic limit and build ultra-low-power consuming electronics. Here, we demonstrate steep-slope NC-FETs based on two-dimensional molybdenum disulfide and CuInP2S6 (CIPS) van der Waals (vdW) heterostructure. The vdW NC-FET provides an average subthreshold swing (SS) less than the Boltzmann's limit for over seven decades of drain current, with a minimum SS of 28 mV dec-1. Negligible hysteresis is achieved in NC-FETs with the thickness of CIPS less than 20 nm. A voltage gain of 24 is measured for vdW NC-FET logic inverter. Flexible vdW NC-FET is further demonstrated with sub-60 mV dec-1 switching characteristics under the bending radius down to 3.8 mm. These results demonstrate the great potential of vdW NC-FET for ultra-low-power and flexible applications.

16.
ACS Appl Mater Interfaces ; 11(25): 22692-22702, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31199111

RESUMO

Poly(tetrafluoroethylene) (Teflon) has been selected as the self-template structural material in the preparation of VO2 films using a reactive magnetron sputtering method and post-annealing process. VO2 films with spontaneous random nanoporous structures growing on quartz glasses have been deliberately established via bottom-up processing through this novel and facile approach. The nanoporous VO2 films exhibit an excellent optical performance based on the localized surface plasmon resonance, with ultrahigh luminous transmittance ( Tlum-L) up to 78.0% and the promoted solar modulation ability (Δ Tsol) of 14.1%. Meanwhile, the ingenious microstructure of the film provides an antireflection function from multiple perspectives on visible light and indicates the potential of the windshield on vehicles for smart solar modulation. The nanoporous films expand the practical application of thermochromic VO2 to a fire-new field, breaking the optical performance envelope of the single-layer dense VO2 film away, and offering a universal method to prepare homogeneous nanoporous structures for thin films.

17.
Nanoscale ; 11(19): 9556-9562, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31049544

RESUMO

Research on VS4 is lagging due to the difficulty in its tailored synthesis. Herein, unique architecture design of one-dimensional VS4 nanowires anchored on reduced graphene oxide is demonstrated via a facile solvothermal synthesis. Different amounts of reduced graphene oxide with VS4 are synthesized and compared regarding their rate capability and cycling stability. Among them, VS4 nanowires@15 wt% reduced graphene oxide present the best electrochemical performance. The superior performance is attributed to the optimal amount of reduced graphene oxide and one-dimensional VS4 nanowires based on (i) the large surface area that could accommodate volume changes, (ii) enhanced accessibility of the electrolyte, and (iii) improvement in electrical conductivity. In addition, kinetic parameters derived from electrochemical impedance spectroscopy spectra and sweep rate dependent cyclic voltammetry curves such as charge transfer resistances and Li+ ion apparent diffusion coefficients both support this claim. The diffusion coefficient is calculated to be 1.694 × 10-12 cm2 s-1 for VS4 nanowires/15 wt% reduced graphene oxide, highest among all samples.

18.
Clin Immunol ; 205: 49-56, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31112757

RESUMO

Mycophenolate mofetil (MMF) is an immunosuppressive agent that is widely used in graft-versus-host disease prophylaxis because of its inhibitory function on T cells and B cells. However, the effect of MMF on natural killer cell reconstitution after allogenic hematological transplantation is largely unknown. The present study examined the effects of different MMF administration durations after haploidentical allo-HSCT on NK cell reconstitution. Ninety patients were enrolled in this study and defined into two groups in term of MMF duration. We found that MMF patients in the long-term MMF group were associated with a poor reconstitution of NK cells and a significantly lower cytotoxicity from day 30 to day 180 post-transplantation. Especially, the long-term MMF group inhibits reconstitution of NKp30 NK subsets, which correlated with higher risk of EBV viremia. Multivariate analysis showed that a better reconstitution of NKp30 cells was associated with lower EBV viremia (HR0.957, p = .04). In vitro experiments demonstrated that the active metabolite of MMF, mycophenolic acid (MPA), inhibited the proliferation and cytotoxicity of NK cells from healthy donors or patients at day 30 post-transplantation. In summary, our findings demonstrated that long-term MMF administration delayed the quality and quantity of NK cells, especially NKp30 subpopulations, which was associated with decreased EBV viremia post allogeneic HSCT.


Assuntos
Infecções por Vírus Epstein-Barr/epidemiologia , Doença Enxerto-Hospedeiro/prevenção & controle , Transplante de Células-Tronco Hematopoéticas , Reconstituição Imune/imunologia , Imunossupressores/administração & dosagem , Células Matadoras Naturais/imunologia , Ácido Micofenólico/administração & dosagem , Viremia/epidemiologia , Adolescente , Adulto , Duração da Terapia , Feminino , Herpesvirus Humano 4 , Humanos , Imunossupressores/uso terapêutico , Células Matadoras Naturais/metabolismo , Leucemia Mieloide Aguda/terapia , Masculino , Pessoa de Meia-Idade , Ácido Micofenólico/uso terapêutico , Síndromes Mielodisplásicas/terapia , Receptor 3 Desencadeador da Citotoxicidade Natural/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Modelos de Riscos Proporcionais , Transplante Homólogo , Adulto Jovem
19.
ACS Appl Mater Interfaces ; 11(17): 15718-15726, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30986032

RESUMO

Artificial metalloenzymes that combine the advantages of natural enzymes and metal catalysts have been getting more attention in research. As a proof of concept, an artificial nanometalloenzyme (CALB-Shvo@MiMBN) was prepared by co-encapsulation of metallo-organic catalyst and enzyme in a soft nanocomposite consisting of 2-methylimidazole, metal ions, and biosurfactant in mild reaction conditions using a one-pot self-assembly method. The artificial nanometalloenzyme with lipase acted as the core, and the metallo-organic catalyst embedded in micropore exhibited a spherical structure of 30-50 nm in diameter. The artificial nanometalloenzyme showed high catalytic efficiency in the dynamic kinetic resolution of racemic primary amines or secondary alcohols compared to the one-pot catalytic reaction of immobilized lipase and free metallo-organic catalyst. This artificial nanometalloenzyme holds great promise for integrated enzymatic and heterogeneous catalysis.

20.
Nanotechnology ; 30(25): 255703, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-30769340

RESUMO

Pursuing excellent photochromic (PC) properties is still a longstanding challenge for energy-efficient smart coatings. Herein, we have prepared a novel series of self-coated crystalline WO3-amorphous WO3-x homojunctions by a one-step hydrothermal process, in which oxalic acid was used as a capping agent to prevent polycondensation and the crystallization of [WO6]. The as-prepared nanopowders with tight interfaces have a large specific surface area and rich surface electrons, which leads to a dramatic PC property reaching up to ΔT sol = 64.74% at the near-infrared (NIR) range of 1000-2600 nm with high luminous transmittance (T lum = 94.6% in the virgin state and T lum = 32.47% in the colored state). Meanwhile, the as-prepared crystalline WO3-amorphous WO3-x homojunction reveals fast reversible PC circulation; most particularly, the self-bleaching rate increases at least three times-the self-bleaching time is less than 8 h. Moreover, as the microstructure of the homojunction is tuned, the solar modulation range can be selective and tuned, so that the solar modulation efficiency is up to the best energy-saving state by controlling the main absorption according to the solar energy distribution.

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