Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 31
Filter
Add more filters










Publication year range
1.
J Stroke Cerebrovasc Dis ; 33(3): 107558, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38262100

ABSTRACT

AIM: We aimed to investigate the relationship between systemic inflammatory response index (SIRI) and intracranial plaque features, as well as the risk factors related to the severity and recurrence of cerebral ischemic events. METHODS: We enrolled 170 patients with cerebral ischemic events. Baseline demographic characteristics and laboratory indicators were collected from all participants. All patients were assessed by high-resolution magnetic resonance vessel wall imaging for culprit plaque characteristics and intracranial atherosclerotic burden. Outpatient or telephone follow-up were conducted at 1, 3, and 6 months after discharge. RESULTS: SIRI levels were significantly associated with the enhanced plaque number (r = 0.205, p = 0.007), total plaque stenosis score (r = 0.178, p = 0.020), total plaque enhancement score (r = 0.222, p = 0.004), intraplaque hemorrhage (F = 5.630, p = 0.004), and plaque surface irregularity (F = 3.986, p = 0.021). Higher SIRI levels (OR = 1.892), total plaque enhancement score (OR = 1.392), intraplaque hemorrhage (OR = 3.370) and plaque surface irregularity (OR = 2.846) were independent risk factors for moderate-severe stroke, and these variables were significantly positively correlated with NIHSS (P < 0.05 for all). In addition, higher age (HR = 1.063, P = 0.015), higher SIRI levels (HR = 2.003, P < 0.001), and intraplaque hemorrhage (HR = 4.482, P = 0.008) were independently associated with recurrent stroke. CONCLUSIONS: Higher SIRI levels may have adverse effects on the vulnerability and burden of intracranial plaques, and links to the severity and recurrence of ischemic events. Therefore, SIRI may provide important supplementary information for evaluating intracranial plaque stability and risk stratification of patients.


Subject(s)
Intracranial Arteriosclerosis , Plaque, Atherosclerotic , Stroke , Humans , Magnetic Resonance Angiography/methods , Stroke/etiology , Magnetic Resonance Imaging/adverse effects , Plaque, Atherosclerotic/complications , Hemorrhage/complications , Systemic Inflammatory Response Syndrome/complications , Intracranial Arteriosclerosis/complications , Intracranial Arteriosclerosis/diagnostic imaging , Intracranial Arteriosclerosis/pathology
2.
Vaccine ; 42(5): 1136-1144, 2024 Feb 15.
Article in English | MEDLINE | ID: mdl-38267332

ABSTRACT

BACKGROUND: Pneumococcal Diseases (PDs) remains a serious public health problem around the world and in China. Pneumococcal vaccination is the most cost-effective measure to prevent PDs. In 2021, the government of Weifang City, Shandong Province, China introduced a free dose of domestic 13-valent Pneumococcal Conjugate Vaccine (PCV 13) to vaccinate registered children aged 6 months-2 years. This study aimed to evaluate the vaccination rate of PCV13 in children aged under 5 years before and after the vaccination program to provide evidences for further improving the prevention and control strategy for PDs. METHODS: We collected data from the children's vaccination information management system in Weifang City and analyzed the PCV13 vaccination coverage and characteristics in all vaccination clinics of Weifang City for children aged under 5 years. We compared the differences in vaccination rates by gender, birth year, manufacturer, and county before and after innovative immunization strategy. RESULTS: Among the included 593,784 children aged under 5 years, the PCV13 vaccination rate in Weifang was generally low before the innovative immunization strategy. Urban children had a higher PCV13 coverage than rural children (P < 0.001), and parents tended to vaccinate their children with imported PCV13.The full vaccination rate for domestic and imported PCV13 was 0.67 % and 1.70 %, respectively. After the vaccination program, the PCV13 coverage of children increased significantly in all counties within Weifang City (P < 0.001), especially for children above 12 months of age. Most parents preferred to vaccinate their children with domestic PCV13, and the full vaccination rate of domestic and imported PCV13 was 6.59 % and 0.16 %, respectively. CONCLUSIONS: The vaccination rate of PCV13 in children is still much lower than the global average, posting a severe health challenge that needs to be addressed thoroughly. To improve the prevention and control strategy for PDs, it is recommended to continue to explore other relevant incentives based on the innovative immunization strategy. Furthermore, it is also recommended that China should incorporate PCV13 into the National Immunization Programs (NIP) as soon as possible.


Subject(s)
Pneumococcal Infections , Streptococcus pneumoniae , Child , Humans , Infant , Child, Preschool , Retrospective Studies , Vaccination Coverage , Vaccination , Pneumococcal Infections/prevention & control , Pneumococcal Vaccines , China , Vaccines, Conjugate
3.
Infect Dis Poverty ; 12(1): 110, 2023 Dec 01.
Article in English | MEDLINE | ID: mdl-38037092

ABSTRACT

The World Health Organization (WHO) prioritizes pneumococcal disease as a vaccine-preventable disease and recommends the inclusion of pneumococcal conjugate vaccines (PCV) in national immunization programs worldwide. However, PCV is not included in the National Immunization Program in China and has low vaccination coverage due to its high cost. To address this, Weifang City implemented an innovative strategy for a 13-valent PCV (PCV13) on June 1, 2021. This strategy aimed to provide one dose of PCV13 free of charge for children aged 6 months to 2 years in registered households and to adopt a commercial insurance model with one dose of PCV13 free of charge in 2023 for children over 2 years old. The Health Commission of Weifang and other departments conducted a comprehensive investigation and considered various factors, such as vaccine effectiveness, safety, accessibility, vaccine price, and immunization schedules, for eligible children (under 5 years old). Stakeholder opinions were also solicited before implementing the policy. The Commission negotiated with various vaccine manufacturers to maximize its negotiating power and reduce vaccine prices. The implementation plan was introduced under the Healthy Weifang Strategy. Following the implementation of this strategy, the full course of vaccination coverage increased significantly from 0.67 to 6.59%. However, vaccination coverage is still lower than that in developed countries. Weifang's PCV13 vaccination innovative strategy is the first of its kind in Chinese mainland and is an active pilot of non-immunization program vaccination strategies. To further promote PCV13 vaccination, Weifang City should continue to implement this strategy and explore appropriate financing channels. Regions with higher levels of economic development can innovate the implementation of vaccine programs, broaden financing channels, improve accessibility to vaccination services, and advocate for more localities to incorporate PCV13 into locally expanded immunization programs or people-benefiting projects. A monitoring and evaluation system should also be established to evaluate implementation effects.


Subject(s)
Pneumococcal Infections , Child , Humans , Infant , Child, Preschool , Cost-Benefit Analysis , Pneumococcal Infections/prevention & control , Vaccination , Pneumococcal Vaccines , Immunization Programs , Vaccines, Conjugate , China
4.
Langmuir ; 39(39): 13946-13952, 2023 Oct 03.
Article in English | MEDLINE | ID: mdl-37736671

ABSTRACT

Studies on self-assembling systems with a controllable morphology responding to light stimulation are significant for revealing the process and mechanism of assembly. Here, a molecule of spiropyran derivative (SP) possessing photoresponsive assembly morphology is constructed. SP self-assembles into irregular sheet-like structures whose morphology can be significantly transformed into regular nanospheres under continuous ultraviolet light stimulation. The UV-vis absorption spectra indicate that 56% of SP are isomerized from closed-ring form (SPC) to open-ring form (SPO) with color changes from colorless to magenta. Furthermore, theoretical calculations demonstrate that SPO-SPO aggregates possess stronger van der Waals forces than do SPC-SPC aggregates and tend to form stable intermediates combined with SPO isomers. Therefore, the isomerization of SP from SPC to SPO and the differences in intermolecular interactions are important factors in the morphological transition. Our study provides an efficient strategy to modulate the assembled morphology, which holds great promise to be applied in the field of smart materials.

5.
Macromol Rapid Commun ; 44(21): e2300360, 2023 Nov.
Article in English | MEDLINE | ID: mdl-37566799

ABSTRACT

The construction of tunable morphological systems has important implications for understanding the mechanism of molecular self-assembly. In this study, a spiropyran derivative M1 is reported with light-responsive assembly morphology, which can be tuned from nanosphere to nanorod by ultraviolet light irradiation. The absorption spectra show that M1 molecules are transformed from closed-ring (SP) isomers into open-ring (MC) isomers and start to form H-aggregates with increasing irradiation time. Density functional theory calculations indicate that MC-MC isomers possess stronger binding energy than SP-SP isomers. The MC isomers may thus facilitate the dissociation of the SP-SP aggregates and promote the change of self-assembled morphology with the aid of stronger π-π stackings and dipole-dipole interactions. The research gives an effective method for modulating the morphology of assemblies, with great potential for applications in smart materials.


Subject(s)
Nanospheres , Nanotubes , Benzopyrans/chemistry , Ultraviolet Rays
6.
Eur J Radiol ; 165: 110959, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37437435

ABSTRACT

PURPOSE: Accurate prediction of outcomes for patients with acute ischemic stroke (AIS) is crucial for clinical decision-making. In this study, we developed prediction models based on non-contrast computed tomography (NCCT) radiomics and clinical features to predict the modified Rankin Scale (mRS) six months after hospital discharge. METHOD: A two-center retrospective cohort of 240 AIS patients receiving conventional treatment was included. Radiomics features of the infarct area were extracted from baseline NCCT scans. We applied Kruskal-Wallis (KW) test and recursive feature elimination (RFE) to select features for developing clinical, radiomics, and fusion models (with clinical data and radiomics features), using support vector machine (SVM) algorithm. The prediction performance of the models was assessed by accuracy, sensitivity, specificity, F1 score, and receiver operating characteristic (ROC) curve. Shapley Additive exPlanations (SHAP) was applied to analyze the interpretability and predictor importance of the model. RESULTS: A total of 1454 texture features were extracted from the NCCT images. In the test cohort, the ROC analysis showed that the radiomics model and the fusion model showed AUCs of 0.705 and 0.857, which outperformed the clinical model (0.643), with the fusion model exhibiting the best performance. Additionally, the accuracy and sensitivity of the fusion model were also the best among the models (84.8% and 93.8%, respectively). CONCLUSIONS: The model based on NCCT radiomics and machine learning has high predictive efficiency for the prognosis of AIS patients receiving conventional treatment, which can be used to assist early personalized clinical therapy.


Subject(s)
Ischemic Stroke , Humans , Retrospective Studies , Ischemic Stroke/diagnostic imaging , Ischemic Stroke/therapy , Prognosis , Tomography, X-Ray Computed/methods , Machine Learning
7.
ACS Catal ; 13(9): 5876-5895, 2023 May 05.
Article in English | MEDLINE | ID: mdl-37180964

ABSTRACT

Operando soft and hard X-ray spectroscopic techniques were used in combination with plane-wave density functional theory (DFT) simulations to rationalize the enhanced activities of Zn-containing Cu nanostructured electrocatalysts in the electrocatalytic CO2 hydrogenation reaction. We show that at a potential for CO2 hydrogenation, Zn is alloyed with Cu in the bulk of the nanoparticles with no metallic Zn segregated; at the interface, low reducible Cu(I)-O species are consumed. Additional spectroscopic features are observed, which are identified as various surface Cu(I) ligated species; these respond to the potential, revealing characteristic interfacial dynamics. Similar behavior was observed for the Fe-Cu system in its active state, confirming the general validity of this mechanism; however, the performance of this system deteriorates after successive applied cathodic potentials, as the hydrogen evolution reaction then becomes the main reaction pathway. In contrast to an active system, Cu(I)-O is now consumed at cathodic potentials and not reversibly reformed when the voltage is allowed to equilibrate at the open-circuit voltage; rather, only the oxidation to Cu(II) is observed. We show that the Cu-Zn system represents the optimal active ensembles with stabilized Cu(I)-O; DFT simulations rationalize this observation by indicating that Cu-Zn-O neighboring atoms are able to activate CO2, whereas Cu-Cu sites provide the supply of H atoms for the hydrogenation reaction. Our results demonstrate an electronic effect exerted by the heterometal, which depends on its intimate distribution within the Cu phase and confirms the general validity of these mechanistic insights for future electrocatalyst design strategies.

8.
ACS Omega ; 8(14): 13131-13139, 2023 Apr 11.
Article in English | MEDLINE | ID: mdl-37065072

ABSTRACT

There is growing interest in graphene-reinforced inorganic matrix composites, but progress in this field is far behind that of polymer matrices due to difficulties in the processing of carbon materials in aggressive sintering environments, including oxidation and solubility in the host matrix. Copper-tungsten matrices are of particular interest in the power switching field but are difficult to produce due to the mutual insolubility of metals and poor wetting. Herein, composites were produced by decorating graphene oxide flakes with 8 nm diameter CuWO4·2H2O nanoparticles and then sintering them to form the final shape. The oxide nanoparticles were found to self-assemble into platelets on the surfaces of graphene flakes. Upon sintering, the presence of graphene was found to change the grain morphology from elongated needles to a polyhedral shape. It was found that, despite the nanosize of the CuWO4·2H2O particles used, the sintering conditions did not reduce the matrix to a pure metal; the sintered composites were found to be of mixed phase with copper tungstate and copper oxide present. Raman spectroscopy indicated that the graphene oxide became hydrogenated during the sintering process as a result of the reducing hydrogen atmosphere used.

9.
Macromol Rapid Commun ; 44(14): e2300116, 2023 Jul.
Article in English | MEDLINE | ID: mdl-36960603

ABSTRACT

Biological tissue usually exhibits good water adaptive mechanical properties, which can maintain high strength and toughness in both wet and dry states. However, synthetic tissue like hydrogel usually becomes hard and brittle in its dry state. Herein, this challenge is met by exploring iron-catechol complex (TA-Fe3+ ) as a great platform combining extremely different polymers (elastomer and hydrogel) to construct new tissue-like soft composite materials with two different continuous phases, which have not yet been reported. In its dry state, the xerogel phase becomes a reinforced segment to increase the strength of PB without losing its toughness. In its wet state, this soft material becomes high performance hydrogel, where hydrogel phase absorbs high water and elastomer phase can sustain high loading. Such heterogeneous phase structures provide a good idea for designing the soft materials, exhibiting a trade-off between its high strength and toughness in both wet and dry states. Furthermore, its shape memory behaviors in both its wet and dry state, which shows a great potential application for complex adaptive shape transformation and engineering application like lifting of heavy objects under remote control due to high photo-thermal transition of TA-Fe3+ is explored.


Subject(s)
Elastomers , Polymers , Elastomers/chemistry , Polymers/chemistry , Hydrogels/chemistry , Water , Engineering
10.
Materials (Basel) ; 15(21)2022 Nov 03.
Article in English | MEDLINE | ID: mdl-36363328

ABSTRACT

Copper-tungsten (Cu-W) composites are widely used in high-power and -temperature electrical applications. The combination of these metals, however, leads to compromised physical and electrical properties. Herein, we produce Cu-W-graphene oxide (Cu-W-GO) composites to address this challenge. To ensure uniform density composites, the as-received metal powders were flattened into a flake morphology by ball milling and then mixed with up to 0.5 wt.% GO flakes. The green forms were processed using spark plasma sintering. The GO was found to be well-dispersed amongst the metallic phases in the final composite. The addition of GO reduced the relative density of the composites slightly (4.7% decrease in relative density at 0.5 wt% GO loading for the composites processed at 1000 °C). X-ray diffraction confirmed good phase purity and that no carbide phases were produced. GO was found to improve the mechanical properties of the Cu-W, with an optimal loading of 0.1 wt.% GO found for ultimate compression strength and strain to failure, and 0.3 wt.% optimal loading for the 0.2% offset yield strength. Significantly, the electrical conductivity increased by up to 25% with the addition of 0.1 wt.% GO but decreased with higher GO loadings.

11.
Front Microbiol ; 13: 809074, 2022.
Article in English | MEDLINE | ID: mdl-35154054

ABSTRACT

Studies of methane-oxidizing bacteria are updating our views of their composition and function in paddy and natural wetlands. However, few studies have characterized differences in the methane-oxidizing bacterial communities between paddy and natural wetlands. Here, we conducted a 13C stable isotope-probing experiment and high-throughput sequencing to determine the structure profiling, co-occurrence relationships, and assembly processes of methanotrophic communities in four wetlands of Northeast China. There was a clear difference in community structure between paddy and natural wetlands. LEfSe analyses revealed that Methylobacter, FWs, and Methylosinus were enriched in natural wetlands, while Methylosarcina were prevailing in paddy, all identified as indicative methanotrophs. We observed distinct co-occurrence relationships between paddy and natural wetlands: more robust and complex connections in natural wetlands than paddy wetlands. Furthermore, the relative importance of stochastic processes was greater than that of deterministic processes, as stochastic processes explained >50% of the variation in communities. These results demonstrated that the co-occurrence relationships and assembly processes of active methanotrophic communities in paddy and natural wetlands were distinct. Overall, the results of this study enhance our understanding of the communities of methane-oxidizing bacteria in paddy and natural wetlands of Northeast China.

12.
ACS Appl Mater Interfaces ; 14(1): 2082-2091, 2022 Jan 12.
Article in English | MEDLINE | ID: mdl-34974701

ABSTRACT

Shape memory polymers can change their initial shape under the stimulation of the external environment, but most of the stimulations require not only an external force but also a high temperature, which limits their application to a certain extent. Inspired by the unmatched elongation of cells on both sides of the mimosa petiole in nature, which leads to leaf closure, we designed a new type of shape transformation polymer, which can transform between 2D and 3D by simple stretching and releasing steps at room temperature. Surface patterning on one side of the sample film was realized via a coordination network of Fe3+-COOH to achieve different coordination gradients along its thickness. By this way, different movements of polymer chains along the thickness would lead to 2D-3D transformation upon releasing the stretched sample. Using this method, we obtained a series of transformations from customized 2D materials to complex 3D shapes and explored their potential application in information encryption transmission.

13.
ACS Appl Mater Interfaces ; 13(11): 13034-13043, 2021 Mar 24.
Article in English | MEDLINE | ID: mdl-33719405

ABSTRACT

Mixed matrix membranes (MMMs) for CO2 separation have overcome the trade-off between gas permeability and gas selectivity to some extent. However, most MMMs still are prepared in lab- and pilot-scales since the permeability and selectivity of CO2 are not good enough to reach the economically available requirements. Moreover, the fabrication of few MMMs with good separation performance is time-consuming or need harsh conditions. In this study, a novel MOF-based composite membrane (PAN-γ-CD-MOF-PU membrane) was successfully fabricated by a facile and fast spin-coating method. In the two-step coating process, we applied a uniform selective layer of γ-cyclodextrin-MOF (γ-CD-MOF) on porous polyacrylonitrile and then coated a layer of polyurethane on the γ-CD-MOF layer. The entire membrane formation process was about 30 s. The formation of a unique γ-CD-MOF layer greatly improved the separation ability of CO2 (the CO2 permeability is 70.97 barrers; the selectivity to CO2/N2 and CO2/O2 are 253.46 and 154.28, respectively). The gas separation performance can exceed the Robeson upper limit obviously and the selectivity is better than other MOF-based composite membranes. In addition, the PAN-γ-CD-MOF-PU membrane is strong and flexible. Therefore, the PAN-γ-CD-MOF-PU membrane developed in this study has great potential in large-scale industrial separation of CO2.

14.
Adv Mater ; 33(9): e2008180, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33511689

ABSTRACT

Photocatalytic ammonia synthesis is exciting but quite challenging with a very moderate yield at present. One of the greatest challenges is to develop highly active centers in a photocatalyst for N2 reduction under ambient conditions. Herein, porous carbon-doped anatase TiOx (C-TiOx ) nanosheets with high-concentration active sites of Ti3+ are presented, which are produced by layered Ti3 SiC2 through a reproducible bottom-up approach. It is shown that the high-concentration Ti3+ sites are the major species for the significant increase in N2 photoreduction activity by the C-TiOx . Such bottom-up substitutional doping of C into TiO2 is responsible for both visible absorption and generation of Ti3+ concentration. Together with the porous nanosheets morphology and the loading of a Ru/RuO2 nanosized cocatalyst for enhanced charge separation and transfer, the optimal C-TiOx with a Ti3+ /Ti4+ ratio of 72.1% shows a high NH3 production rate of 109.3 µmol g-1 h-1 under visible-light irradiation and a remarkable apparent quantum efficiency of 1.1% at 400 nm, which is the highest compared to all TiO2 -based photocatalysts at present.

15.
Nat Commun ; 11(1): 4008, 2020 Aug 11.
Article in English | MEDLINE | ID: mdl-32782245

ABSTRACT

Supported atomic metal sites have discrete molecular orbitals. Precise control over the energies of these sites is key to achieving novel reaction pathways with superior selectivity. Here, we achieve selective oxygen (O2) activation by utilising a framework of cerium (Ce) cations to reduce the energy of 3d orbitals of isolated copper (Cu) sites. Operando X-ray absorption spectroscopy, electron paramagnetic resonance and density-functional theory simulations are used to demonstrate that a [Cu(I)O2]3- site selectively adsorbs molecular O2, forming a rarely reported electrophilic η2-O2 species at 298 K. Assisted by neighbouring Ce(III) cations, η2-O2 is finally reduced to two O2-, that create two Cu-O-Ce oxo-bridges at 453 K. The isolated Cu(I)/(II) sites are ten times more active in CO oxidation than CuO clusters, showing a turnover frequency of 0.028 ± 0.003 s-1 at 373 K and 0.01 bar PCO. The unique electronic structure of [Cu(I)O2]3- site suggests its potential in selective oxidation.

16.
ACS Appl Mater Interfaces ; 12(7): 8547-8554, 2020 Feb 19.
Article in English | MEDLINE | ID: mdl-32023031

ABSTRACT

A hierarchical architecture composed of nitrogen (N)-rich carbon@graphitic carbon-coated ZnO nanowire arrays on a graphene fiber (ZnO@C/GF) was fabricated by direct growth of a ZnO@zeolitic imidazolate framework-8 (ZIF-8) core-shell nanowire array on a GF followed by annealing and used as a microelectrode for detection of 2,4,6-trinitrotoluene (TNT). In such a design, ZnO accumulated TNT through a strong nitroxide-zinc interaction and ZIF-8 served as the precursor of the N-rich carbon@graphitic carbon layer that seamlessly connected ZnO with the GF to improve the poor conductivity of ZnO, thus enhancing the sensitivity of the ZnO@C/GF microelectrode. The constructed hierarchical hybrid fiber microsensor exhibited a wide linear response to TNT in a concentration range of 0.1-32.2 µM with a low detection limit of 3.3 nM. This ZnO@C/GF microelectrode was further successfully applied to the detection of TNT in lake and tap water, indicating its promise as a portable sensor for the electrochemical detection of explosive compounds.

17.
J Mater Chem B ; 7(35): 5291-5295, 2019 09 11.
Article in English | MEDLINE | ID: mdl-31464334

ABSTRACT

A novel nitrogen-rich-carbon-coated ZIF-67 embedded three-dimensional-graphene (ZIF-67/NC/3DG) fiber was fabricated via a facile one-pot electrodeposition self-assembly method, and used as a prominent electrode for the non-enzymatic detection of adrenaline (Ad). In this design, the prepared ZIF-67 adsorbs Ad through hydrogen bonding and electrostatic interaction, while polypyrrole functions as the precursor of the conductive NC that seamlessly connects ZIF-67 with the 3DG fiber electrode to ameliorate the poor conductivity of the ZIF-67 moiety and thus improve the sensitivity of the ZIF-67/NC/3DG fiber electrode for detecting Ad. The constructed fiber sensor shows a double linear response over the Ad concentration range of 0.06-95 µM with a high sensitivity of 44.6 mA mM-1 cm-2 and 95.0-5900 µM with a good sensitivity of 11.0 mA mM-1 cm-2, giving a low detection limit of 0.02 µM and excellent repeatability. The ZIF-67/NC/3DG fiber electrode was further successfully applied for the determination of Ad in a real sample of human serum, indicating that this fiber electrode is a promising miniaturized sensor for electrochemical analysis.


Subject(s)
Biosensing Techniques/methods , Electrochemical Techniques/methods , Epinephrine/blood , Metal-Organic Frameworks/chemistry , Electrodes , Graphite/chemistry , Humans , Metal Nanoparticles/chemistry , Mineral Fibers , Nitrogen/chemistry
18.
Dalton Trans ; 48(28): 10565-10573, 2019 Jul 16.
Article in English | MEDLINE | ID: mdl-31215925

ABSTRACT

Ten rare-earth/zinc heterometallic complexes containing both alkoxy-amino-bis(phenolato) and chiral salen ligands were synthesized from the reactions of alkoxy-amino-bis(phenolato) rare-earth complexes with chiral salen zinc complexes via ligand redistribution and THF disassociation. Six of them were characterized by single-crystal X-ray diffraction, which showed 6-coordinate rare-earth and 5-coordinate zinc centres in the complexes. A primary catalytic application of these heterometallic complexes was studied, and it was found that samarium/zinc and dysprosium/zinc heterometallic complexes are highly efficient catalysts for copolymerization of CO2 with cyclohexene oxide while the alkoxy-amino-bis(phenolato) samarium complex and chiral salen zinc complex show very low catalytic activity or no catalytic activity for this copolymerization.

19.
ACS Nano ; 13(2): 2463-2472, 2019 Feb 26.
Article in English | MEDLINE | ID: mdl-30649849

ABSTRACT

Nanostructured carbons with different pore geometries are prepared with a liquid-free nanocasting method. The method uses gases instead of liquid to disperse carbon precursors, leach templates, and remove impurities, minimizing synthetic procedures and the use of chemicals. The method is universal and demonstrated by the synthesis of 12 different porous carbons with various template sources. The effects of pore geometries in catalysis can be isolated and investigated. Two of the resulted materials with different pore geometries are studied as supports for Ru clusters in the hydrogenolysis of 5-hydroxymethylfurfural (HMF) and electrochemical hydrogen evolution (HER). The porous carbon-supported Ru catalysts outperform commercial ones in both reactions. It was found that Ru on bottleneck pore carbon shows a highest yield in hydrogenolysis of HMF to 2,5-dimethylfuran (DMF) due to a better confinement effect. A wide temperature operation window from 110 to 140 °C, with over 75% yield and 98% selectivity of DMF, has been achieved. Tubular pores enable fast charge transfer in electrochemical HER, requiring only 16 mV overpotential to reach current density of 10 mA·cm-2.

20.
Inorg Chem ; 57(17): 10489-10493, 2018 Sep 04.
Article in English | MEDLINE | ID: mdl-30133263

ABSTRACT

A photosensitizing metal-organic layer (MOL), IrBPY-MOL, based on hafnium-oxo clusters and cyclometalated iridium-complex-derived organic linkers, was synthesized and used as an efficient catalyst for photopolymerization of methyl methacrylate and other monomers to afford polymers with high-number-averaged molar masses and low polydispersity indices. The corresponding metal-organic framework (MOF) failed to photopolymerize or exhibited low catalytic efficiency under identical conditions. This work highlights the advantages of MOLs over their MOF counterparts in overcoming pore-size and diffusion limitations in photopolymerization reactions.

SELECTION OF CITATIONS
SEARCH DETAIL
...