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1.
J Stroke Cerebrovasc Dis ; 33(3): 107558, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38262100

RESUMO

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.


Assuntos
Arteriosclerose Intracraniana , Placa Aterosclerótica , Acidente Vascular Cerebral , Humanos , Angiografia por Ressonância Magnética/métodos , Acidente Vascular Cerebral/etiologia , Imageamento por Ressonância Magnética/efeitos adversos , Placa Aterosclerótica/complicações , Hemorragia/complicações , Síndrome de Resposta Inflamatória Sistêmica/complicações , Arteriosclerose Intracraniana/complicações , Arteriosclerose Intracraniana/diagnóstico por imagem , Arteriosclerose Intracraniana/patologia
2.
Langmuir ; 39(39): 13946-13952, 2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37736671

RESUMO

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.

3.
Macromol Rapid Commun ; 44(14): e2300116, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36960603

RESUMO

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.


Assuntos
Elastômeros , Polímeros , Elastômeros/química , Polímeros/química , Hidrogéis/química , Água , Engenharia
4.
Macromol Rapid Commun ; 44(21): e2300360, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37566799

RESUMO

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.


Assuntos
Nanosferas , Nanotubos , Benzopiranos/química , Raios Ultravioleta
5.
Chemistry ; 24(59): 15772-15776, 2018 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-30016566

RESUMO

Metal-organic frameworks (MOFs) have emerged as promising single-site solid catalysts for organic reactions. However, MOF catalysts suffer from pore size limitation and slow diffusion, which are detrimental for photoreactions. Metal-organic layers (MOLs) have unique ultrathin 2D monolayer structures and overcome pore size and diffusion limitations. Here, the synthesis of photoactive Zr-RuBPY MOL based on Zr-oxo clusters and [Ru(bpy)3 ]2+ -containing linkers is reported as well as its application in photocatalytic [2+2] cyclizations of enones and Meerwein addition reactions between aryl diazonium salts, styrenes, and nitriles.

6.
Inorg Chem ; 57(17): 10489-10493, 2018 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-30133263

RESUMO

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.

7.
Nano Lett ; 16(7): 4670-8, 2016 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-27328393

RESUMO

The advancement of human induced pluripotent stem-cell-derived cardiomyocyte (hiPSC-CM) technology has shown promising potential to provide a patient-specific, regenerative cell therapy strategy to treat cardiovascular disease. Despite the progress, the unspecific, underdeveloped phenotype of hiPSC-CMs has shown arrhythmogenic risk and limited functional improvements after transplantation. To address this, tissue engineering strategies have utilized both exogenous and endogenous stimuli to accelerate the development of hiPSC-CMs. Exogenous electrical stimulation provides a biomimetic pacemaker-like stimuli that has been shown to advance the electrical properties of tissue engineered cardiac constructs. Recently, we demonstrated that the incorporation of electrically conductive silicon nanowires to hiPSC cardiac spheroids led to advanced structural and functional development of hiPSC-CMs by improving the endogenous electrical microenvironment. Here, we reasoned that the enhanced endogenous electrical microenvironment of nanowired hiPSC cardiac spheroids would synergize with exogenous electrical stimulation to further advance the functional development of nanowired hiPSC cardiac spheroids. For the first time, we report that the combination of nanowires and electrical stimulation enhanced cell-cell junction formation, improved development of contractile machinery, and led to a significant decrease in the spontaneous beat rate of hiPSC cardiac spheroids. The advancements made here address critical challenges for the use of hiPSC-CMs in cardiac developmental and translational research and provide an advanced cell delivery vehicle for the next generation of cardiac repair.


Assuntos
Estimulação Elétrica , Células-Tronco Pluripotentes Induzidas/citologia , Miócitos Cardíacos/citologia , Nanofios , Diferenciação Celular , Células Cultivadas , Humanos , Silício
8.
Angew Chem Int Ed Engl ; 56(41): 12619-12623, 2017 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-28809077

RESUMO

The alkoxyl radical is an essential and prevalent reactive intermediate for chemical and biological studies. Here we report the first donor-acceptor complex-enabled alkoxyl radical generation under metal-free reaction conditions induced by visible light. Hantzsch ester forms the key donor-acceptor complex with N-alkoxyl derivatives, which is elucidated by a series of spectrometry and mechanistic experiments. Selective C(sp3 )-C(sp3 ) bond cleavage and allylation/alkenylation is demonstrated for the first time using this photocatalyst-free approach with linear primary, secondary, and tertiary alkoxyl radicals.

9.
Angew Chem Int Ed Engl ; 56(40): 12102-12106, 2017 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-28804945

RESUMO

We report the rational design of metal-organic layers (MOLs) that are built from [Hf6 O4 (OH)4 (HCO2 )6 ] secondary building units (SBUs) and Ir[bpy(ppy)2 ]+ - or [Ru(bpy)3 ]2+ -derived tricarboxylate ligands (Hf-BPY-Ir or Hf-BPY-Ru; bpy=2,2'-bipyridine, ppy=2-phenylpyridine) and their applications in X-ray-induced photodynamic therapy (X-PDT) of colon cancer. Heavy Hf atoms in the SBUs efficiently absorb X-rays and transfer energy to Ir[bpy(ppy)2 ]+ or [Ru(bpy)3 ]2+ moieties to induce PDT by generating reactive oxygen species (ROS). The ability of X-rays to penetrate deeply into tissue and efficient ROS diffusion through ultrathin 2D MOLs (ca. 1.2 nm) enable highly effective X-PDT to afford superb anticancer efficacy.


Assuntos
Estruturas Metalorgânicas/química , Nanotecnologia , Fotoquimioterapia , Animais , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Neoplasias do Colo/tratamento farmacológico , Análise de Fourier , Camundongos , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/uso terapêutico , Difração de Pó , Espécies Reativas de Oxigênio/química , Compostos de Rutênio/química , Raios X , Ensaios Antitumorais Modelo de Xenoenxerto
10.
J Am Chem Soc ; 138(7): 2158-61, 2016 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-26864385

RESUMO

We report the design of a phosphorescence/fluorescence dual-emissive nanoscale metal-organic framework (NMOF), R-UiO, as an intracellular oxygen (O2) sensor. R-UiO contains a Pt(II)-porphyrin ligand as an O2-sensitive probe and a Rhodamine-B isothiocyanate ligand as an O2-insensitive reference probe. It exhibits good crystallinity, high stability, and excellent ratiometric luminescence response to O2 partial pressure. In vitro experiments confirmed the applicability of R-UiO as an intracellular O2 biosensor. This work is the first report of a NMOF-based intracellular oxygen sensor and should inspire the design of ratiometric NMOF sensors for other important analytes in biological systems.


Assuntos
Técnicas Biossensoriais , Metaloporfirinas/química , Nanoestruturas/química , Oxigênio/análise , Animais , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Linhagem Celular Tumoral , Sobrevivência Celular , Metaloporfirinas/síntese química , Camundongos
11.
Nano Lett ; 15(5): 2765-72, 2015 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-25826336

RESUMO

The current inability to derive mature cardiomyocytes from human pluripotent stem cells has been the limiting step for transitioning this powerful technology into clinical therapies. To address this, scaffold-based tissue engineering approaches have been utilized to mimic heart development in vitro and promote maturation of cardiomyocytes derived from human pluripotent stem cells. While scaffolds can provide 3D microenvironments, current scaffolds lack the matched physical/chemical/biological properties of native extracellular environments. On the other hand, scaffold-free, 3D cardiac spheroids (i.e., spherical-shaped microtissues) prepared by seeding cardiomyocytes into agarose microwells were shown to improve cardiac functions. However, cardiomyocytes within the spheroids could not assemble in a controlled manner and led to compromised, unsynchronized contractions. Here, we show, for the first time, that incorporation of a trace amount (i.e., ∼0.004% w/v) of electrically conductive silicon nanowires (e-SiNWs) in otherwise scaffold-free cardiac spheroids can form an electrically conductive network, leading to synchronized and significantly enhanced contraction (i.e., >55% increase in average contraction amplitude), resulting in significantly more advanced cellular structural and contractile maturation.


Assuntos
Diferenciação Celular/efeitos dos fármacos , Coração/crescimento & desenvolvimento , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Humanos , Técnicas In Vitro , Nanofios/administração & dosagem , Silício/administração & dosagem , Engenharia Tecidual/métodos , Alicerces Teciduais/química
12.
Vaccine ; 42(5): 1136-1144, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38267332

RESUMO

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.


Assuntos
Infecções Pneumocócicas , Streptococcus pneumoniae , Criança , Humanos , Lactente , Pré-Escolar , Estudos Retrospectivos , Cobertura Vacinal , Vacinação , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas , China , Vacinas Conjugadas
13.
Eur J Radiol ; 165: 110959, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37437435

RESUMO

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.


Assuntos
AVC Isquêmico , Humanos , Estudos Retrospectivos , AVC Isquêmico/diagnóstico por imagem , AVC Isquêmico/terapia , Prognóstico , Tomografia Computadorizada por Raios X/métodos , Aprendizado de Máquina
14.
ACS Omega ; 8(14): 13131-13139, 2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-37065072

RESUMO

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.

15.
Infect Dis Poverty ; 12(1): 110, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38037092

RESUMO

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.


Assuntos
Infecções Pneumocócicas , Criança , Humanos , Lactente , Pré-Escolar , Análise Custo-Benefício , Infecções Pneumocócicas/prevenção & controle , Vacinação , Vacinas Pneumocócicas , Programas de Imunização , Vacinas Conjugadas , China
16.
ACS Catal ; 13(9): 5876-5895, 2023 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-37180964

RESUMO

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.

17.
ACS Appl Mater Interfaces ; 14(1): 2082-2091, 2022 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-34974701

RESUMO

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.

18.
Materials (Basel) ; 15(21)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36363328

RESUMO

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.

19.
Front Microbiol ; 13: 809074, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35154054

RESUMO

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.

20.
Adv Mater ; 33(9): e2008180, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33511689

RESUMO

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.

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