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Supercontinuum generation (SCG) from silica-based photonic crystal fibers (PCFs) is of highly technological significance from microscopy to metrology, but has been hindered by silica's relatively low intrinsic optical nonlinearity. The prevailing approaches of filling PCF with nonlinear gases or liquids can endow fibre with enhanced optical nonlinearity and boosted SCG efficiency, yet these hybrids are easily plagued by fusion complexity, environmental incompatibility or transmission mode instability. Here this work presents a strategy of embedding solid-state 2D MoS2 atomic layers into the air-holes of PCF to efficiently enhance SCG. This work demonstrates a 4.8 times enhancement of the nonlinear coefficient and a 70% reduction of the threshold power for SCG with one octave spanning in the MoS2-PCF hybrid. Furthermore, this work finds that the SCG enhancement is highly layer-dependent, which only manifests for a real 2D regime within the thickness of five atomic layers. Theoretical calculations reveal that the critical thickness arises from the trade-off among the layer-dependent enhancement of the nonlinear coefficient, leakage of fundamental mode and redshift of zero-dispersion wavelength. This work provides significant advances toward efficient SCG, and highlights the importance of matching an appropriate atomic layer number in the design of functional 2D material optical fibers.
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Although covalent organic frameworks (COFs) with high π-conjugation have recently exhibited great prospects in perovskite solar cells (PSCs), their further application in PSCs is still hindered by face-to-face stacking and aggregation issues. Herein, metal-organic framework (MOF-808) is selected as an ideal platform for the in situ homogeneous growth of a COF to construct a core-shell MOF@COF nanoparticle, which could effectively inhibit COF stacking and aggregation. The synergistic intrinsic mechanisms induced by the MOF@COF nanoparticles for reinforcing intrinsic stability and mitigating lead leakage in PSCs have been explored. The complementary utilization of π-conjugated skeletons and nanopores could optimize the crystallization of large-grained perovskite films and eliminate defects. The resulting PSCs achieve an impressive power conversion efficiency of 23.61% with superior open circuit voltage (1.20 V) and maintained approximately 90% of the original power conversion efficiency after 2000 h (30-50% RH and 25-30 °C). Benefiting from the synergistic effects of the in situ chemical fixation and adsorption abilities of the MOF@COF nanoparticles, the amount of lead leakage from unpackaged PSCs soaked in water (< 5 ppm) satisfies the laboratory assessment required for the Resource Conservation and Recovery Act Regulation.
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Molecular triplet-triplet annihilation upconversion often experiences drastic luminescence quenching in the presence of oxygen molecules, posing a significant constraint on practical use in aerated conditions. We present an oxygen-immune near-infrared triplet-triplet annihilation upconversion system utilizing non-organometallic cyanine sensitizers (λex = 808 nm) and chemically synthesized benzo[4,5]thieno[2,3-b][1,2,5]thiadiazolo[3,4-g]quinoxaline dyes with a defined dimer structure as annihilators (λem = 650 nm). This system exhibits ultrastable upconversion under continuous laser irradiance (>480 mins) or extended storage (>7 days) in aerated solutions. Mechanistic investigations reveal rapid triplet-triplet energy transfer from sensitizer to annihilators, accompanied by remarkably low triplet oxygen quenching efficiencies ( η O 2 < 13% for the sensitizer, <3.7% for the annihilator), endowing the bicomponent triplet-triplet annihilation system with inherent oxygen immunity. Our findings unlock the direct and potent utilization of triplet-triplet annihilation upconversion systems in real-world applications, demonstrated by the extended and sensitive nanosensing of peroxynitrite radicals in the liver under in vivo nitrosative stress.
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In this work, the ligand-to-metal charge transition and Förster resonance energy transfer process is exploited to derive lanthanide-organic framework (Tb-cpon) modified perovskite solar cells (PSCs) with enhanced performance under UV irradiation. Tb-cpon-modified PSCs exhibit rapid response and reduced degradation due to energy downconversion facilitated by effective coupling of UV-sensitive chromophores to lanthanide luminescent centers, enhancing the spectral response range of the composite films. Furthermore, the characteristic changes of precursor particle sizes suggest formation of Tb-cpon adducts as intermediate products, leading to enhanced crystallinity and reduced defect concentrations in the Tb-cpon-perovskite hybrid film. Accordingly, the Tb-cpon-modified PSC devices obtain a champion efficiency up to 23.72% as well as a sensitive photovoltaic conversion even under pure UV irradiation. Moreover, the unencapsulated devices maintain more than 80% of the initial efficiency after continuous irradiation under a 310 nm UV lamp for 24 h (from the Au electrode side), compared to 21% for the control devices.
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The photovoltaic performance of perovskite solar cells is severely limited by the innate defects of perovskite films. Metal-organic framework (MOF)-based additives with luxuriant skeleton structures and tailored functional groups show a huge potential to solve these problems. Here, a multilateral passivation strategy is performed by introducing two alkyl-sulfonic acid functionalized MOFs, MIL-88B-1,3-SO3H and MIL-88B-1,4-SO3H, respectively, obtained from MIL-88B-NH2 through a post-synthetic process, for coordinating the lead defects and inhibiting non-radiative recombination. The flexible MIL-88B-type frameworks endow both functionalized MOFs with excellent electrical conductivity and preferable carrier transport in the hole-transport materials. Compared with the original MIL-88B-NH2 and MIL-88B-1,4-SO3H, MIL-88B-1,3-SO3H exhibits optimal steric hindrance and multiple passivation groups (-NH2, -NH-, and -SO3H), achieving the champion doped device with an enhanced power conversion efficiency (PCE) of 22.44% and excellent stability, which maintains 92.8% of the original PCE under ambient conditions (40% humidity and 25 °C) for 1200 h.
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Despite the unprecedented progress in lead-based perovskite solar cells (PSCs), the toxicity and leakage of lead from degraded PSCs triggered by deep-level defects and poor crystallization quality increase environmental risk and become a critical challenge for eco-friendly PSCs. Here, a novel 2D polyoxometalate (POM)-based metal-organic framework (MOF) (C5 NH5 )4 (C3 N2 H5 )2 Zn3 (H8 P4 Mo6 O31 )2 ·2H2 O (POMOF) is ingeniously devised to address these issues. Note that the integration of POM endows POMOF with great advantages of electrical conductivity and charge mobility. Ordered POMOF induces the crystallization of high-quality perovskite film and eliminates lead-based defects to improve internal stability. The resultant PSCs achieve a superior power conversion efficiency (23.3%) accompanied by improved stability that maintains ≈90% of its original efficiency after 1600 h. Meanwhile, POMOF with phosphate groups effectively prevents lead leakage through in situ chemical anchoring and adsorption methods to reduce environmental risk. This work provides an effective strategy to minimize lead-based defects and leakage in sustainable PSCs through multi-functional POM-based MOF material.
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Photonic crystal fiber (PCF) embedded with functional materials has demonstrated diverse applications ranging from ultrafast lasers, optical communication to chemical sensors. Many efforts have been made to fabricating carbon nanotube (CNT) based optical fibers by ex situ transfer method; however, often suffer poor uniformity and coverage. Here, the direct growth of CNTs on the inner walls of PCFs by the chemical vapor deposition (CVD) method is reported. A two-step growth method is developed to control the narrow diameter distribution of CNTs to ensure desirable nanotube optical transitions. In the as-fabricated CNT- embedded fiber, third-harmonic generation (THG) has been enhanced by ≈15 times compared with flat CNT film on fused silica. A dual-wavelength all-fiber mode-locked ultrafast laser (≈1561 and ≈1064 nm) is further demonstrated by integrating the 1.36±0.15 nm-diameter CNTs into two kinds of photonic bandgap hollow core PCF (named HC-1550 and HC-1060) as saturable absorbers, using their S11 (≈0.7 eV) and S22 (≈1.2 eV) interband transition respectively. The fiber laser shows stable output of ≈10 mW, ≈800 fs pulse width, and ≈71 MHz repetition rate at 1561 nm wavelength. These results can enable the large-scale applications of CNTs in PCF-based optical devices.
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The diffusion processes in zeolites are important for heterogeneous catalysis. Herein, we show that unique zeolites with "continuum intersecting channels" (e.g., BEC, POS, and SOV), in which two intersections are proximal, are greatly significant to the diffusion process with spontaneous switching of the diffusion pathway under varied loading. At low loading, the synergy of strong adsorption sites and molecular reorientation in intersections contribute to almost exclusive molecular diffusion in smaller channels. With an increase in molecular loading, the adsorbates are transported preferentially in larger channels mainly due to the lower diffusion barrier inside continuum intersection channels. This work demonstrates the ability to adjust the prior diffusion pathway by controlling the molecular loading, which may be beneficial for the separation of the product and byproduct in heterogeneous catalysis.
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OBJECTIVE: To compare the clinical efficacy of open debridement screw fixation combined with bone grafting, percutaneous screw fixation, and percutaneous screw fixation combined with injection of platelet-rich plasma (PRP) for the treatment of Slade and Dodds Grade III to IV scaphoid nonunion (SNU). METHODS: This retrospective study included patients with Grade III (25 patients) and Grade IV (28 patients) SNU. They were treated with open surgery bone grafting and internal fixation (group A), percutaneous screw fixation (group B) or percutaneous screw fixation and PRP injection (group C) from January 2015 to May 2020. The fracture consolidation rate, VAS score, and Mayo wrist function score were compared across the three groups. RESULTS: The consolidation rate was not significantly different among the three groups for both Grade III and IV SNU. However, patients in group C reported significantly less pain and better wrist function 7 days after surgery compared to group A and B, for both nonunion grades. At 3 months after surgery, group C had significantly better VAS and Mayo wrist scores compared to group A for both nonunion grades, and compared to group B for Grade IV SNU. At 6 and 12 months after surgery, patients with Grade IV SNU in groups A and C had significantly better VAS and Mayo wrist scores compared to group B. CONCLUSION: This study suggests that percutaneous screw fixation with PRP injection could be a more effective method for treating Grade IV SNU. This approach may reduce postoperative wrist pain and improve wrist function in the early stages after surgery for patients with both Grade III and IV SNU. TYPE OF STUDY/LEVEL OF EVIDENCE: IV.
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Fracturas Óseas , Fracturas no Consolidadas , Hueso Escafoides , Humanos , Estudios Retrospectivos , Fracturas no Consolidadas/diagnóstico por imagen , Fracturas no Consolidadas/cirugía , Hueso Escafoides/diagnóstico por imagen , Hueso Escafoides/cirugía , Fijación Interna de Fracturas/efectos adversos , Fijación Interna de Fracturas/métodos , Resultado del Tratamiento , Dolor Postoperatorio , Trasplante Óseo/métodosRESUMEN
Herein, a hydroxyl-modified MXene@ZnIn2S4 (Nb4C3Tx MXene@ZIS-OH) overall water splitting photocatalyst with a sandwich structure was prepared through an in-situ growth strategy and peroxyl plasma post-treatment. The Nb4C3Tx MXene@ZIS-OH exhibits outstanding catalytic performance, which generates the release rates of hydrogen (53.8 µmol g-1h-1) and oxygen (26.7 µmol g-1h-1) from the water under visible light irradiation. After four photocatalytic cycling, the photocatalytic overall water splitting activity of Nb4C3Tx MXene@ZIS-OH is still 95.9% of the initial activity, which indicates that Nb4C3Tx MXene@ZIS-OH exhibits excellent cycling stability. Notably, the Nb4C3Tx MXene@ZIS-OH achieves an AQY of 1.2% for the overall photocatalytic water splitting at 380 nm. The sandwich structure and matched heterointerface between high work function Nb4C3Tx MXene and ZnIn2S4 nanosheets promote the electron transport, inhibit the charge recombination, and separate the generated H2 and O2 with effectiveness. Importantly, the Finite-Difference Time-Domain (FDTD) simulation suggests the hydroxyl groups on the surface of ZnIn2S4 could increase the hydrophilicity of photocatalyst and capture the holes generated by photoexcitation, thereby promoting the separation of electron-hole pairs rapidly. This work presents a successful example of constructing overall water splitting photocatalysts by energy level regulation, structure design and functional group modification.
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Photocatalytic removal of sulfonamide antibiotics is an effective strategy to solve environmental pollution. Ag3PO4 is a promising anode material for photocatalytic material with photocatalytic degradation ability under ultraviolet light or natural light. Unfortunately, due to its instability, Ag+ could be reduced to Ag0 which loaded onto the surface of Ag3PO4 during the photocatalytic process, causing self-photocorrosion and resulting in the reduction of photocatalytic activity and stability. Herein, Ag3PO4 nanoparticles loaded with Ag nanoclusters containing Ag vacancies (Ag/Ag3PO4-VAg) were constructed by an in-situ reduction strategy to achieve effectively photocatalytic degradation behavior. The Ag nanoclusters loaded on the surface of Ag3PO4 can not only effectively inhibit the self-photocorrosion but also affords a localized surface plasmon resonance (LSPR) effect in the photocatalytic process, thus leading to the efficient generation and rapid transfer of photogenerated carriers behavior. In addition, the Ag vacancies in Ag3PO4 are crucial to increasing the adsorption energy of H2O for further enhancing the capture and accumulation of electrons. In detail, according to Zeta potential analysis, the strong adsorption sites of sulfamethoxazole (SMX) molecules are generated at the interface of Ag and Ag3PO4, which promote the activation of SMX molecules. A 100 ml of 20 mg/L SMX could be completely degraded within 15 min with an apparent rate constant (Kapp) of 0.306 min-1, which far exceeds the activity of most of the photocatalysts. This work may provide an attractive strategy to address the activity, stability of Ag3PO4 and and realizing the green remediation of SMX wastewater.
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PURPOSE: To investigate the presence and change of nerve fibers and neuropeptide during early development of articular cartilage in neonatal rats. METHODS: Articular cartilage in distal-femoral epiphyses was collected from neonatal Sprague Dawley rats, which were 1-day, 5-day, and 10-day postnatal (P1, P5 and P10). Microscopy, immunofluorescence, transmission and scanning electron microscopy (TEM and SEM) were performed for detection of nerve fibers. Quantitative analysis for substance P (SP) and neuropeptide Y (NPY) was conducted using immunofluorescence and enzyme-linked immunosorbent assay (ELISA). RESULTS: TEM showed the existence of myelinated nerve fibers in the extracellular matrix of articular cartilage in both P1, P5 and P10 rats, and they formed synaptic contacts with chondrocytes. During this time, chondrocytes proceeded with their development, and the nerve fibers gradually degraded. The ELISA results showed significant increase of the sensory neuropeptide SP and the sympathetic neuropeptide NPY in the cartilage tissue. Immunofluorescence results showed the distribution of SP and NPY in the perichondrium, the cartilage canals, the plasma of chondrocytes, and extracellular matrix in the cartilage tissue. CONCLUSIONS: Nerve fibers exist in the matrix of articular cartilage during early development of knee joints in neonatal rats. Nerve fibers form synaptic contacts with chondrocytes at the early stage and then degrade gradually in the course of chondrocyte development. SP and NPY significantly increase in articular cartilage during this very period. These results indicate that the nerve fibers and the neuropeptide they secrete may exert important effect on the development of articular cartilage.
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Cartílago Articular , Animales , Animales Recién Nacidos , Cartílago Articular/metabolismo , Condrocitos/metabolismo , Fibras Nerviosas/química , Fibras Nerviosas/metabolismo , Neuropéptido Y/análisis , Neuropéptido Y/metabolismo , Ratas , Ratas Sprague-Dawley , Sustancia P/análisis , Sustancia P/metabolismoRESUMEN
Conventional oxidation of 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) by air would bring various drawbacks for perovskite solar cells (PSCs), such as low power conversion efficiency (PCE) and poor stability. Here, a series of heteroatom-substituted Keggin-type polyoxometalates (POMs), H4PMo11VO40 (PMo11V), H5PMo10V2O40 (PMo10V2), and H6PMo9V3O40 (PMo9V3) are prepared and applied as p-type dopants to realize quantitative and controllable oxidation of Spiro-OMeTAD under an inert condition. The possible mechanism and electron donor regions in the oxidation of Spiro-OMeTAD are investigated using two-dimensional nuclear magnetic resonance (NMR) spectra and the relationship between POM structures and the oxidation degree of Spiro-OMeTAD is proposed. In addition, the synergistic effect of heteroatoms makes V2-substituted PMo10V2 exhibit appropriate oxidation of Spiro-OMeTAD and promoted the highest efficient hole extraction as well as the decreased charge recombination. Therefore, the champion device doped with PMo10V2 shows a PCE of 20.41% and a superior open circuit voltage (Voc) of 1.133 V, surpassing that of the pristine device (18.61%). This work presents a fresh perspective to the controllable oxidation of Spiro-OMeTAD employing economical inorganic POM dopants, which would promote the commercialization of PSCs.
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Effective contact and collision between reactants and active sites are essential for heterogeneous catalysis. Herein, we investigated molecular diffusion in more than 200 kinds of zeolites, and an intriguing "diffusive skin effect" was observed, whereby molecules migrated along the pore walls of zeolites (i.e., diffusion trajectories) because of the effect of the guest-host interaction and diffusion barrier. Furthermore, it was found that such a "diffusive skin effect" of zeolites would strongly promote the contacts and collisions between reactants and active sites in the reaction process, which might effectively promote the zeolite-catalyzed performance. These new findings will provide some new fundamental understanding of zeolite catalytic mechanisms under confinement effect.
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Fabrication of a visible-light driven photocatalyst is of great vital for the elimination of antibiotics and microorganism in the wastewater and the construction of sustainable green energy systems. In this work, carbon quantum dots (C-dots) were integrated with Cu2O/SrTiO3 p-n heterojunction to optimize the photocatalytic activity. The excellent photocatalytic degradation efficiency of chlortetracycline hydrochloride (CTC·HCl) (92.6% within 90 min) and E. coli inactivation efficiency were observed over C-dots/Cu2O/SrTiO3 under visible light irradiation. It is the synergistic effect of p-n heterojunction and modification of C-dots that facilitates the separation and transfer of electron-holes. Meanwhile, the modification of C-dots improves the harvesting of long wavelength solar light of photocatalysts due to its unique up-conversion photoluminescence (UCPL) characteristics. Eventually, the possible photocatalytic degradation path of the catalyst was inferred by LC-MS spectra, and the degradation mechanism was analyzed. This study sheds light on new possibilities for the application of photocatalysts in various light sources and has broad application prospects in water treatment.
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Puntos Cuánticos , Purificación del Agua , Antibacterianos/farmacología , Catálisis , Escherichia coliRESUMEN
Micro-/nanostructured materials can control the diffraction and propagation of light, thereby providing new optical properties that can be exploited to enhance photocatalytic processes. In this work, a series of the cauliflower-like MoS2/CdS hybrid micro-/nanostructures is synthesized. These structures contain numerous cracks and pores that can enhance the absorption and utilization of light as well as shorten the distance for transferring photogenerated electrons to the catalyst surface. The results of ultraviolet-visible diffuse reflectance absorption spectra show that the composite material has enhanced absorption in the visible light region. Further investigation of the optical characteristics of the synthesized materials using a finite-difference time-domain (FDTD) simulation reveals that the cauliflower-like micro-/nanostructure increases the optical absorption intensity at the MoS2/CdS interface. Notably, the MoS2/CdS hybrid micro-/nanostructures exhibits high photocatalytic hydrogen production activity (9.5 mmol g-1 h-1) and long-lasting cycle stability. This work helps us to further understand the enhancement mechanism of light absorption and utilization by porous structural materials.
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N-doped carbon materials are well known as promising metal-free catalysts and applied in innumerable industrial synthetics. However, most of the N-doped carbon materials obtained by conventional synthetic means exhibit generally low mesoporosity, and their reported pore volumes reached only 1-3 cm3 g-1, which greatly limits their further industrial application in heterogeneous catalysis. Especially for oxidation reaction of alkylbenzenes, this type of reaction is almost always accompanied by many different byproducts, while the reaction activity and selectivity are mainly affected by mesoporosity of catalysts. Traditionally, graphitic carbon nitride (GCN) is commonly considered as a self-sacrificed nitrogen source together with multifarious organic compounds to obtain N-doped carbon materials by a co-pyrolysis process. However, the mechanisms of formation process are still complex and uncontrollable to date. In this work, we present a novel co-pyrolysis synthetic strategy by a facile chemical vapor deposition method for preparing a series of ultrathin N-doped carbon nanosheets with high mesoporosity. More importantly, it is found that GCN containing abundant hydrogen bonds can be irreversibly anchored by carbonaceous gas fragments (CxHy+) released from various organic substances via thermogravimetry-differential thermal analysis coupled with mass spectrometry and X-ray photoelectron spectroscopy analysis, and the CxHy+ fragments exhibit a non-negligible role during the transformation. Our results further demonstrated that the residue of incompletely decomposed GCN is a key point to enlarge porosity in final products which are obtained via mixing pyrolysis between an organic precursor and GCN (or GCN precursors). Benefitting from the outstanding mesoporosity and ultrathin morphology, the representative ABCNS-900 exhibits excellent catalytic performance for oxidizing ethylbenzene to acetophenone with extremely low dosage and high selectivity. Our findings show a universal synthetic strategy for ultrathin N-rich carbon nanosheets with a high mesopore volume, further promoting the application of N-doped carbon materials in heterogeneous catalytic industry.
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Carbon materials with multilevel structural features are showing great potentials in electromagnetic (EM) pollution precaution. With ZIF-67 microcubes as a self-sacrificing precursor, hierarchical carbon microcubes with micro/mesoporous shells and hollow cavities have been successfully fabricated with the assistance of rigid SiO2 coating layers. It is found that the SiO2 layer can effectively counteract the inward shrinkage of organic frameworks during high-temperature pyrolysis due to intensive interfacial interaction. The obtained hollow porous carbon microcubes (HPCMCs) exhibit larger Brunauer-Emmett-Teller surface area and pore volume than porous carbon microcubes (PCMCs) directly derived from ZIF-67 microcubes. The unique microstructure is confirmed to be favorable for conductive loss and interfacial polarization, thus boosting the overall dielectric loss capability of carbon materials. Besides, hollow cavity will also promote multiple reflection of incident EM waves and intensify the dissipation of EM energy. As expected, HPCMCs harvest better microwave absorption performance, including strong reflection loss intensity and broad response bandwidth, than many traditional microporous/mesoporous carbon materials. This study provides a new strategy for the construction of hierarchical carbon materials and may inspire the design of carbon-based composites with excellent EM functions.
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As the issues surrounding antibiotic-resistant strains of Staphylococcus aureus (S. aureus) are becoming increasingly serious concerns, it is imperative to investigate new therapeutic targets to successfully treat patients with S. aureus infections. The two-component signal transduction system is one of the primary pathways by which bacteria adapt to the external environment, and it serves an important role in regulating virulence gene expression, cell wall synthesis, biofilm formation and bacterial activity. There are 17 two-component signaling pathways in S. aureus, among which WalKR/VicSR/YycGF, AirSR/YhcSR, vancomycin resistance associated regulator/sensor and LytRS have been demonstrated to serve vital roles in regulating bacterial resistance, and are hypothesized to be potential targets for the treatment of S. aureus infections. The present review assesses the mechanism of the two-component signaling pathways associated with the development of S. aureus resistance.
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Metal-organic framework (MOF)-supported macroscale resin catalysts, IRA900(xOH)-MIL-101(Al)-NH2 (x means the concentration of NaOH), with spatially isolated antagonistic acid-base active sites were successfully synthesized through a novel strategy by ion exchange and in situ solvothermal methods. The hierarchical pore system of the as-prepared catalysts effectively promotes the mass transfer and contacts with catalytic active centers during the organic reactions. Therefore, the environmentally friendly catalysts exhibit excellent superior activity and stability in one-pot deacetalization-Knoevenagel condensation reaction, and the yield by optimal IRA900(0.2OH)-MIL-101(Al)-NH2 reaches close to 99% after 5 h at 110 °C. Thanks to the millimeter-sized resin carrier and robust sphere morphology, the recycling of the as-prepared catalysts only requires natural sedimentation. This work presents an effective strategy to build low-toxic acid-base catalysts by combining the advantages of ion-exchange resins and functionalized MOF materials.