Postoperative cognitive dysfunction (POCD) is a common neurological complication in elderly patients after surgery and general anesthesia. The occurrence of POCD seriously affects the postoperative recovery of patients, and leads to prolonged hospital stay, reduced quality of life, increased medical costs, and even higher mortality. There is no definite and effective drug treatment for POCD. More evidence shows that perioperative non-pharmacological intervention can improve postoperative cognitive function and reduce the incidence of POCD. Therefore, our studies summarize the current non-pharmacological interventions of POCD from the aspects of cognitive training, physical activity, transcutaneous electrical acupoint stimulation, noninvasive brain stimulation, non-pharmacological sleep improvement, music therapy, environment, and multimodal combination Interventions, to provide more data for clinical application and research.
Organics are gaining significance as electrode materials due to their merits of multi-electron reaction sites, flexible rearrangeable structures and redox reversibility. However, organics encounter finite electronic conductivity and inferior durability especially in organic electrolytes. To circumvent above barriers, we propose a novel design strategy, constructing conductive network structures with extended π-π superposition effect by manipulating intermolecular interaction. Tetralithium 1,4,5,8-naphthalenetetracarboxylate (LNTC) interwoven by carbon nanotubes (CNTs) forms LNTC@CNTs composite firstly for Li-ion storage, where multiple conjugated carboxyls contribute sufficient Li-ion storage sites, the unique network feature enables electrolyte and charge mobility conveniently combining electron delocalization in π-conjugated system, and the enhanced π-π superposition effect between LNTC and CNTs endows laudable structural robustness. Accordingly, LNTC@CNTs maintain an excellent Li-ion storage capacity retention of 96.4 % after 400â cycles. Electrochemical experiments and theoretical simulations elucidate the fast reaction kinetics and reversible Li-ion storage stability owing to the electron delocalization and π-π superposition effect, while conjugated carboxyls are reversibly rearranged into enolates during charging/discharging. Consequently, a dual-ion battery combining this composite anode and expanded graphite cathode exhibits a peak specific capacity of 122â mAh g-1 and long cycling life with a capacity retention of 84.2 % after 900â cycles.
Three hydrophobic porphyrin titanium-based metal-organic frameworks (MOFs) (HPA/DGIST-1, DPA/DGIST-1, and OPA/DGIST-1) were synthesized through a postsynthetic coordination reaction by using alkylphosphonic acid of different lengths (HPA, hexylphosphonic acid; DPA, dodecylphosphonic acid; OPA, octadecylphosphonic acid). Compared with the hydrophilic DGIST-1, modified DGIST-1 exhibits excellent hydrophobicity and presents good stability in humid atmospheres. Due to the introduction of porphyrin ligands, HPA/DGIST-1, DPA/DGIST-1, and OPA/DGIST-1 showed good visible-light absorption (380-700 nm) and sensitive photogenerated charge responses. When acted as catalysts, these hydrophobic Ti-MOFs can selectively reduce CO2 to HCOO- under visible-light irradiation with average reaction rates of 150.9, 178.5, and 228.3 µmol·h-1·g-1, where these values are 1.3-2.0 times higher than the system mediated by the initial porphyrin Ti-MOF catalyst. 13C NMR spectroscopy demonstrates that the catalytic product HCOO- anion originates from the reactant CO2. The photocatalytic experiments, electron paramagnetic resonance, and photoluminescence spectra tests showed that porphyrin ligands and Ti-O units can act as catalytic activity centers to realize the conversion of CO2 to HCOO-. This work demonstrated that the combination of porphyrin titanium-based MOF and alkyl hydrophobic groups is an effective way to enhance the stability of titanium-based MOFs and maintain their high photocatalytic performance.
A NiCo2O4/NiCo2O4/Ni foam (NCO/NCO/NF) hybrid composite with a wire-penetrated-cage hierarchical structure was synthesized by in situ growth of bimetallic NiCo metal-organic frameworks (NiCo-MOF) on a NiCo layered double hydroxide (NiCo-LDH) nanowire-modified Ni foam (NF) surface and subsequent heat treatment in air. The NCO/NCO/NF hybrid composite shows higher specific surface area and more active sites than its individual components. The wire-penetrated-cage hierarchical structure of NCO/NCO/NF and the synergistic coupling of NCO hollow nanocages (NCO HNCs), NCO nanowires (NCO NWs) and NF provide a fast electron transfer path, improve the conductivity, accelerate the kinetic reaction rate, and enhance the structural stability. When assessed as an electrode for the oxygen evolution reaction (OER), the NCO/NCO/NF hybrid composite exhibits a low overpotential of 310 mV at 10 mA cm-2 and current density retention of 91% after a 100 h oxidation reaction, which indicates that it has excellent catalytic activity and durability in the electrocatalytic OER.
Metal nanoparticles (NPs) stabilized by metal-organic frameworks (MOFs) have been intensively studied in recent decades, while investigations on the location of guest metal NPs relative to host MOF particles remain challenging and very rare. In this work, we have developed several characterization techniques, including high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) tomography, hyperpolarized 129Xe NMR spectroscopy and positron annihilation spectroscopy (PAS), which are able to determine the specific location of metal NPs relative to the MOF particle. The fine PdCu NPs confined inside MIL-101 exhibit excellent catalytic activity, absolute selectivity and satisfied recyclability in the aerobic oxidation of benzyl alcohol in pure water. As far as we know, the determination for the location of metal NPs relative to MOF particles and pore structure information of metal NPs/MOF composites by 129Xe NMR and PAS techniques has not yet been reported.
Highly active and stable copper catalysts were successfully achieved by in situ self-reduction treatment of hierarchical double-shell copper silicate hollow nanofibers. The coexistence of Cu0 and Cu+ species in the as-prepared catalysts demonstrated the strong metal-support interactions and endowed them with outstanding catalytic performance for the RWGS reaction.
The design and synthesis of cheaper and more stable catalysts with comparable electrocatalytic performance to commercial Pt/C towards the oxygen reduction reaction is of importance for their application in fuel cells and metal-air batteries. Herein, we report the generation of nitrogen-doped carbon/MnO2 nanocomposites via pyrolyzing the polypyrrole/MnO2 precursor that is obtained based on the direct redox reaction between polypyrrole and KMnO4. The achieved sample presents an onset and half-wave potential of -0.048 and -0.124 V vs. Hg/HgO, respectively, and a current retention of 93% after 20 000 s chronoamperometry measurement. Meanwhile, it shows stronger methanol tolerance, endowing it with great potential for the corresponding applications. The excellent oxygen reduction reaction catalytic activity originates from the synergistic effect between nitrogen-doped carbon and MnO2, where the former one is helpful for MnO2 to achieve a higher Mn3+/Mn4+ ratio and a higher number of oxygen vacancies, and the existence of the latter one is beneficial for generating a higher ID/IG ratio in the carbon layer. These both contribute to the achievement of large numbers of active sites for the electrocatalytic process.
A comparative study of the adsorption and desorption processes of methanol in two kinds of nanochannels (i.e. MCM-41 and SWNTs) is performed by in situ continuous-flow laser-hyperpolarized 129Xe NMR. The high sensitivity and short acquisition time of hyperpolarized 129Xe allow for probing the molecular dynamics in a confined geometry under real working conditions. Hyperpolarized 129Xe NMR spectra indicate that the methanol adsorption behavior in nanochannels is determined by the characters of adsorption sites and that the methanol adsorption rate in the nanochannels of SWNTs is faster than in MCM-41. The experimental data shown in this work also indicate that there is a change in gas phase 129Xe NMR signal intensity during the adsorption and desorption of methanol in SWNTs. This may be because there is a strong depolarization of hyperpolarized 129Xe in SWNTs.
In this work, a series of three-dimensional porous flower-like zinc doped NiCo2 O4 (ZNCO) nanostructures with different Zn doping level are successfully prepared by a facile solvothermal process without using any templets. The obtained products are characterized by various techniques, and their electrocatalytic performances are also assessed by the oxygen evolution reaction (OER). According to the electrochemical characterization, it is demonstrated that ZNCO-0.15 (i.e., Zn0.15 Ni0.85 Co2 O4 ) nanoflowers show a lower overpotential, smaller Tafel slope, higher electrochemical active surface area (ECSA), as well as a larger turnover frequency (TOF) value than those of Co3 O4 , NiCo2 O4 , and ZnCo2 O4 nanoflowers, indicating that introduction of an optimal content of zinc ions plays an important role in enhancing electrocatalytic performances for OER. The enhanced OER performance of ZNCO-0.15 could be attributed to the increased number of active sites (Co3+ ), accelerated kinetic rate, and promoted conductivity of the catalyst with the incorporation of zinc ions.
Exfoliation of layered bulk g-C3 N4 (CNB) to thin g-C3 N4 sheets in nanodomains has attracted much attention in photocatalysis because of the intriguing properties of nanoscaled g-C3 N4 . This study shows that carbon-rich g-C3 N4 nanosheets (CNSC) can be easily prepared by self-modification of polymeric melon units through successively thermally treating bulk g-C3 N4 in an air and N2 atmosphere. The prepared CNSC not only retain the outstanding properties of nanosheets, such as large surface area, high aspect ratios, and short charges diffusion distance, but also overcome the drawback of enlarged bandgap caused by the quantum size effect, resulting in an enhanced utilization of visible light and photoinduced electron delocalization ability. Therefore, the as-prepared CNSC show a high hydrogen evolution rate of 39.6 µmol h-1 with a turnover number of 24.98 in 1 h at λ > 400 nm. Under irradiation by longer wavelength of light (λ > 420 nm), CNSC still exhibit a superior hydrogen evolution rate, which is 72.9 and 5.4 times higher than that of bulk g-C3 N4 and g-C3 N4 nanosheets, respectively.
Ultrathin (Pt-enriched cage)@CeO2 core@shell nanostructures are successfully fabricated via a facile hard-template method. It is found that the usage of Pd@Ag@CeO2 bi-metallic core@shell nanostructure as the hard template plays an important role in avoiding the independent nucleation of Pt metal during the galvanic replacement process between K2 PtCl4 and Ag components. This unique core@shell samples show extraordinary activity and selectivity for the cinnamaldehyde hydrogenation reaction. It can achieve over 95% conversion with 87% selectivity of hydrocinnamaldehyde in 5 h under 1 atm H2 pressure. It is considered that such high catalytic performance could be attributed to the densely CeO2 -coated core@shell hybrid form as well as the ultrathin nature of the Pt-enriched cage.
Incorporation of CeO2 nanoparticles into the cavity of zeolitic imidazolate framework-8 (ZIF-8) was followed by high-temperature pyrolysis to generate CeO2 @N-doped carbon materials. Introduction of the CeO2 nanoparticles greatly enhanced the catalytic activity of the ZIF-8-derived carbon materials in the oxygen reduction reaction (ORR) owing to the presence of Ce3+ and oxygen vacancies with high content of chemisorbed oxygen in CeO2 and the well-maintained skeleton of the original ZIF-8 with uniform mesoporous structure. The material treated at 900 °C (CeO2 @N-C-900) showed excellent ORR catalytic activity in both acidic and alkaline electrolyte. The ORR onset and half-wave potentials of CeO2 @N-C-900 were 1.003 and 0.908â V versus RHE, respectively, in 0.1 m KOH aqueous solution, which are comparable to those of Pt/C catalysts. Furthermore, it exhibited much better stability and methanol crossover tolerance than Pt/C, indicative of its good potential for applications in energy conversion.
The redox reaction between KMnO4 and Ni was carried out on a chain-like Ni surface under hydrothermal conditions and γ-MnO2 nanosheets were produced through this facile route. The original Ni nanochains, as cores, dominated the final morphology of the composites with MnO2 nanosheets loaded on their surface. The uniform assemblies of MnO2 , with large amounts of exposed sites, allowed them to be good candidates for application in various fields. The reduction of 4-nitrophenol by NaBH4 was selected as model reaction to test the catalytic activity of the samples and the samples could also be made into electrodes for supercapacitor measurement. Both the results revealed the advantages of the γ-MnO2 assembled on the Ni chain surfaces. Furthermore, the magnetic cores facilitated the recycling of the sample and increased the stability upon charge-discharge cycles.
In this paper, a facile strategy is reported for the preparation of well-dispersed Pt nanoparticles in ordered mesoporous silica (Pt@OMS) by using a hybrid mesoporous phenolic resin-silica nanocomposite as the parent material. The phenolic resin polymer is proposed herein to be the key in preventing the aggregation of Pt nanoparticles during their formation process and making contributions both to enhance the surface area and enlarge the pore size of the support. The Pt@OMS proves to be a highly active and stable catalyst for both gas-phase oxidation of CO and liquid-phase hydrogenation of 4-nitrophenol. This work might open new avenues for the preparation of noble metal nanoparticles in mesoporous silica with unique structures for catalytic applications.
The g-C3N4 nanosheets (g-C3N4NS) exhibit more excellent property than common bulk g-C3N4 (g-C3N4-B) due to their large surface areas, improved electron transport ability and well dispersion in water. In this work, ultrathin g-C3N4NS with a thickness of about 2.7nm have been synthesized by a simple thermal exfoliation of bulk g-C3N4, and then Ag2WO4 nanoparticles are in situ loaded on their surface to construct the Ag2WO4/g-C3N4NS heterostructured photocatalysts. Due to their unique physicochemical properties, the as-prepared heterostructures possess a fast interfacial charge transfer and increased lifetime of photo-excited charge carriers, and exhibit much higher photocatalytic activity. Under visible light irradiation, the optimum photocatalytic activity of Ag2WO4/g-C3N4NS composites is almost 53.6 and 26.5 times higher than that of pure g-C3N4-B and Ag2WO4/g-C3N4-B heterostructures towards the degradation of rhodamine B, respectively, and is almost 30.6 and 9.8 times higher towards the degradation of methyl orange, respectively. In addition, the natural sunlight photocatalytic activities of the as-prepared samples are also investigated.
The dynamic evolution of acetyl intermediates in the two different channels of H-mordenite (H-MOR) zeolite during dimethyl ether (DME) carbonylation is tracked by using in situ solid-state NMR spectroscopy under continuous-flow conditions. Thus, the reaction path via methyl acetate produced over active sites in 8 member ring (MR) channels, followed by diffusion into 12 MR channels, is proposed.
Aluminum Silicates/chemistry , Zeolites/chemistry , Acetylation , Carbon Monoxide/chemistry , Gases , Magnetic Resonance Spectroscopy , Molecular Structure
We report the synthesis of sandwich-structured graphene-nickel silicate-Ni ternary composites by using the solvothermal method followed by a simple in situ reduction procedure. The composites show an interesting structure with graphene sandwiched between two layers of well-dispersed Ni nanoparticles (NPs) anchored on ultrathin nickel silicate nanosheets. These ternary composites exhibit enhanced performance as anode materials owing to the synergistic effect between the graphene matrix and electrochemically inert Ni nanoparticles, an effect that holds promise for the design and fabrication of other advanced electrode materials.
An ultrastable [Ag55(MoO4)6](43+) ({Ag55Mo6} for short) nanocluster with a Ag-centered multishell structure in compound [Ag55(MoO4)6(C≡C(t)Bu)24(CH3COO)18](OAc)·2H2O (1) has been obtained. The ultrastability of 1 was demonstrated by Mulliken population analysis. In addition, the potential wide gap semiconductor property and electrochemical properties of 1 were investigated.
Hollow mesoporous structures have recently aroused intense research interest owing to their unique structural features. Herein, an effective and precisely controlled synthesis of hollow rare-earth silicate spheres with mesoporous shells is reported for the first time, produced by a simple hydrothermal method, using silica spheres as the silica precursors. The as-prepared hollow rare-earth silicate spheres have large specific surface area, high pore volume, and controllable structure parameters. The results demonstrate that the selection of the chelating reagent plays critical roles in forming the hollow mesoporous structures. In addition, a simple and low-energy-consuming approach to synthesize highly stable and dispersive gold nanoparticle-yttrium silicate (AuNPs/YSiO) hollow nanocomposites has also been developed. The reduction of 4-nitrophenol with AuNPs/YSiO hollow nanocomposites as the catalyst has clearly demonstrated that the hollow rare-earth silicate spheres are good carriers for Au nanoparticles. This strategy can be extended as a general approach to prepare multifunctional yolk-shell structures with diverse compositions and morphologies simply by replacing silica spheres with silica-coated nanocomposites.
Gold/chemistry , Nanocomposites/chemistry , Nanoparticles/chemistry , Nanospheres/chemistry , Silicates/chemistry , Catalysis , Silicon Dioxide/chemistry
In this paper, TiO(2)/Ag sponge-like nanostructure composites have been prepared by the surface sol-gel method with the template of natural cellulose, which is relatively simple, low-cost, and environmentally friendly. The Ag nanoparticles are deposited on the TiO(2) nanosponges through UV irradiation photoreduction of silver nitrate solutions. The physicochemical properties of as-prepared composites are characterized by XRD, BET, SEM, TEM, XPS and UV-vis DRS techniques. The UV-light photocatalytic activities of the composites are evaluated through the photodegradation of two model organic molecules including RhB and salicylic acid. The experimental results show that the photocatalytic activities of TiO(2)/Ag nanosponge composites are superior to that of P25, pure TiO(2) nanoparticle aggregates synthesized by the hydrothermal method and pure TiO(2) nanosponge. The superior activities of TiO(2)/Ag nanosponge composite photocatalysts can be attributed to the unique nanosponge morphology, uniform dispersion of Ag nanoparticles, and strong interaction between Ag and TiO(2) nanosponges.
