Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 129
Filtrar
1.
Environ Toxicol ; 2024 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-38770826

RESUMO

Lung cancer (LC) is one of the major malignant diseases threatening human health. The study aimed to identify the effect of citrulline on the malignant phenotype of LC cells and to further disclose the potential molecular mechanism of citrulline in regulating the development of LC, providing a novel molecular biological basis for the clinical treatment of LC. The effects of citrulline on the viability, proliferation, migration, and invasion of LC cells (A549, H1299) were validated by CCK-8, colony formation, EdU, and transwell assays. The cell glycolysis was assessed via determining the glucose uptake, lactate production, ATP levels, extracellular acidification rate (ECAR), and oxygen consumption rate (OCR). RNA-seq and molecular docking were performed to screen for citrulline-binding target proteins. Western blotting experiments were conducted to examine the expression of related signaling pathway molecules. In addition, the impacts of citrulline on LC growth in vivo were investigated by constructing mouse models. Citrulline augmented the viability of LC cells in a concentration and time-dependent manner. The proliferation, migration, invasion, glycolysis, and EMT processes of LC cells were substantially enhanced after citrulline treatment. Bioinformatics analysis indicated that citrulline could bind to RAB3C protein. Western blotting results indicated that citrulline activated the IL-6/STAT3 pathway by binding to RAB3C. In addition, animal experiments disclosed that citrulline promoted tumor growth in mice. Citrulline accelerated the glycolysis and activated the IL6/STAT3 pathway through the RAB3C protein, consequently facilitating the development of LC.

2.
Environ Toxicol ; 39(7): 3956-3966, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38587027

RESUMO

BACKGROUNDS: Non-small cell lung carcinoma (NSCLC) is a common type of lung cancer. Prior investigations have elucidated the pivotal role of miR-29b-3p in restraining tumor growth and metastasis. Nonetheless, it remains to be determined whether miR-29b-3p can effectively suppress NSCLC progression and enhance the sensitivity of NSCLC cells to cisplatin. This investigation sought to determine the mechanism by which miR-29b-3p inhibited the advancement of NSCLC and mitigated resistance to cisplatin. METHODS: We initially assessed miR-29b-3p and VEGF levels in NSCLC tissues and cell lines. Next, miR-29b-3p expression was elevated in NSCLC cell lines H1975 and A549 by overexpression plasmid transfection. Following this, a sequence of molecular biology experiments was conducted to evaluate the impact of miR-29b-3p on the biological behaviors of NSCLC cells and their resistance to cisplatin. Additionally, we predicted VEGF was a target gene of miR-29b-3p by bioinformatics analysis. We next employed western blot to evaluate the protein expression of Nrf2 and HO-1 in NSCLC cells. Finally, we elucidated the effects of VEGF and Nrf2/HO-1pathway on NSCLC progression and cisplatin resistance by in vitro assays. RESULTS: In comparison to paracancerous tissues and human normal lung epithelial cells, the expression of miR-29b-3p was notably reduced and VEGF expression was clearly elevated in NSCLC tissues and cells. Moreover, miR-29b-3p upregulated obviously suppressed the biological activities of NSCLC cells and increased their sensitivity to cisplatin. Furthermore, in NSCLC cells, miR-29b-3p bound to VEGF and negatively regulate its transcription. Additionally, miR-29b-3p overexpression also inhibited the Nrf2/HO-1 signaling pathway. Finally, the overexpression of VEGF and the activation of the Nrf2/HO-1 pathway reversed miR-29b-3p-mediated inhibitory effect on biological behaviors of NSCLC cells and increased the cisplatin resistance. CONCLUSION: Our findings indicate that miR-29b-3p impedes NSCLC cells' biological behaviors and augments their sensitivity to cisplatin by targeting VEGF to modulate the Nfr2/HO-1 signaling pathway.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Cisplatino , Resistencia a Medicamentos Antineoplásicos , Heme Oxigenase-1 , Neoplasias Pulmonares , MicroRNAs , Fator 2 Relacionado a NF-E2 , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Cisplatino/farmacologia , Fator 2 Relacionado a NF-E2/metabolismo , Fator 2 Relacionado a NF-E2/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Heme Oxigenase-1/metabolismo , Heme Oxigenase-1/genética , Transdução de Sinais/efeitos dos fármacos , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos
3.
Angew Chem Int Ed Engl ; 63(12): e202315777, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38233351

RESUMO

Electrochemical CO2 reduction can convert CO2 to value-added chemicals, but its selectivity toward C3+ products are very limited. One possible solution is to run the reactions in hybrid processes by coupling electrocatalysis with other catalytic routes. In this contribution, we report the cascade electrocatalytic and thermocatalytic reduction of CO2 to propionaldehyde. Using Cu(OH)2 nanowires as the precatalyst, CO2 /H2 O is reduced to concentrated C2 H4 , CO, and H2 gases in a zero-gap membrane electrode assembly (MEA) reactor. The thermochemical hydroformylation reaction is separately investigated with a series of rhodium-phosphine complexes. The best candidate is identified to be the one with the 1,4-bis(diphenylphosphino)butane diphosphine ligand, which exhibits a propionaldehyde turnover number of 1148 under a mild temperature and close-to-atmospheric pressure. By coupling and optimizing the upstream CO2 electroreduction and downstream hydroformylation reaction, we achieve a propionaldehyde selectivity of ~38 % and a total C3 oxygenate selectivity of 44 % based on reduced CO2 . These values represent a more than seven times improvement over the best prior electrochemical system alone or over two times improvement over other hybrid systems.

4.
Angew Chem Int Ed Engl ; 63(9): e202317828, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38165224

RESUMO

Carbon dioxide reduction reaction (CO2 RR) provides an efficient pathway to convert CO2 into desirable products, yet its commercialization is greatly hindered by the huge energy cost due to CO2 loss and regeneration. Performing CO2 RR under acidic conditions containing alkali cations can potentially address the issue, but still causes (bi)carbonate deposition at high current densities, compromising product Faradaic efficiencies (FEs) in present-day acid-fed membrane electrode assemblies. Herein, we present a strategy using a positively charged polyelectrolyte-poly(diallyldimethylammonium) immobilized on graphene oxide via electrostatic interactions to displace alkali cations. This enables a FE of 85 %, a carbon efficiency of 93 %, and an energy efficiency (EE) of 35 % for CO at 100 mA cm-2 on modified Ag catalysts in acid. In a pure-water-fed reactor, we obtained a 78 % CO FE with a 30 % EE at 100 mA cm-2 at 40 °C. All the performance metrics are comparable to or even exceed those attained in the presence of alkali metal cations.

5.
Cardiovasc Diabetol ; 22(1): 130, 2023 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-37254140

RESUMO

BACKGROUND: The triglyceride-glucose (TyG) index has been recognized as being an alternative cardiometabolic biomarker for insulin resistance associated with the development and prognosis of cardiovascular disease (CVD). However, the prospective relationship between baseline and long-term trajectories of the TyG index and carotid atherosclerosis (CAS) progression has yet to be investigated. METHODS: This longitudinal prospective cohort study included 10,380 adults with multiple general health checks at Peking University Third Hospital from January 2011 to December 2020. The TyG index was calculated as ln (fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2). The latent class trajectory modeling method was used to analyze the TyG index trajectories over the follow-up. Based on univariate and multivariate Cox proportional hazards analyses, hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for the baseline and trajectory of the TyG index. RESULTS: During a median follow-up period of 757 days, 1813 participants developed CAS progression. Each 1-standard deviation (SD) increase in the TyG index was associated with a 7% higher risk of CAS progression after adjusting for traditional CVD risk factors (HR = 1.067, 95% CI 1.006-1.132). Similar results were observed when the TyG index was expressed as quartiles. According to different trajectory patterns, participants were categorized into low-stable, moderate-stable, and high-increasing groups. After multivariate adjustment, the moderate-stable group had a 1.139-fold (95% CI 1.021-1.272) risk of CAS progression. The high-increasing trajectory of the TyG index tended to be associated with CAS progression (HR = 1.206, 95% CI 0.961-1.513). CONCLUSIONS: Participants with higher baseline and moderate-stable trajectory of the TyG index were associated with CAS progression. Long-term trajectories of the TyG index can help to identify individuals at a higher risk of CAS progression who deserve specific preventive and therapeutic approaches.


Assuntos
Doenças Cardiovasculares , Doenças das Artérias Carótidas , Adulto , Humanos , Glucose , Fatores de Risco , Estudos Prospectivos , Glicemia , Medição de Risco , Triglicerídeos , Biomarcadores , Doenças das Artérias Carótidas/diagnóstico por imagem , Doenças das Artérias Carótidas/epidemiologia
6.
Exp Cell Res ; 419(2): 113276, 2022 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-35863454

RESUMO

Chemotherapy resistance limits the efficacy of cisplatin (DDP) when treating non-small cell lung cancer (NSCLC). Circular RNAs (circRNAs) confers a regulatory role in drug resistance. Innovatively, the regulatory role of circular RNA HIPK2 (circHIPK2) in DDP resistance was probed in the work. In this research, tumor tissues and matched normal tissues were obtained from 52 NSCLC patients, and the expressions of circHIPK2, miR-1249-3p and VEGFA in the tissues were detected by qPCR or Western Blot. Correlation analysis of circHIPK2 expression with survival prognosis and clinicopathological features was conducted. Parental NSCLC cell lines (A549, H460) and DDP-resistant cell lines (A549/DDP, H460/DDP) were selected, and the expression of circHIPK2, miR-1249-3p and VEGFA in the cells were detected. Cell IC50 value, proliferation, migration, invasion, apoptosis and angiogenesis were detected. Tumor xenografts were established to detect the role of circHIPK2 in vivo. The binding relationship between circHIPK2, miR-1249-3p and VEGFA was verified by dual luciferase reporter experiment, RNA pull down and RIP experiment. Our data showed that circHIPK2 and VEGFA were abnormally overexpressed and miR-1249-3p was underexpressed in DDP-resistant NSCLC tissues and cell lines. CircHIPK2 knockdown or miR-1249-3p upregulation inhibited DDP resistance, malignant behavior, and angiogenesis in NSCLC. CircHIPK2 by competitive absorption of miR-1249-3p mediated VEGFA. CircHIPK2 promoted the sensitivity of drug-resistant cells to DDP in NSCLC by regulating VEGFA. CircHIPK2 enhanced the growth of DDP-resistant NSCLC cells in vivo. In conclusion, circHIPK2 has the malignant property for angiogenesis and chemoresistance in NSCLC via the network of miR-1249-3p/VEGFA.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , MicroRNAs , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Proteínas de Transporte , Linhagem Celular Tumoral , Proliferação de Células/genética , Cisplatino/farmacologia , Cisplatino/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , MicroRNAs/genética , MicroRNAs/metabolismo , Proteínas Serina-Treonina Quinases/genética , RNA Circular/genética , Fator A de Crescimento do Endotélio Vascular
7.
Angew Chem Int Ed Engl ; 62(8): e202215408, 2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36515631

RESUMO

Aluminum-ion batteries (AIBs) have attracted great attentions in recent years. Organic materials such as polythiophene (PT) are promising cathode for AIBs. However, the capacity and cyclic stability of conventional organic cathode such as PT are limited by the inadequate degree of reaction and the unstable nature of organic materials. To obtain high-performance organic cathode, a new PT with the ability of self-adaptive re-organization was prepared. During cycling, its molecular chain can be re-organized, and the polymerization mode will change from Cα -Cα (α-PT) to Cß -Cß (ß-PT). This change leads to smaller steric hindrance and faster kinetics during ion insertion which can lower the reaction energy barrier and stabilize the molecular structure. Benefited by this, AIBs with this cathode can deliver a specific capacity of 180 mAh g-1 (@2 A g-1 ) and a superb stability of 100 000 cycles at 10 A g-1 . High energy density and power density can also be achieved with this cathode.

8.
Nano Lett ; 21(9): 4092-4098, 2021 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-33881875

RESUMO

Pd is the only metal that can catalyze electrochemical CO2 reduction to formate at close-to-zero overpotential. It is unfortunately subjected to severe poisoning by trace CO as the side product and suffers from deteriorating stability and selectivity with increasing overpotential. Here, we demonstrate that alloying Pd with Cu in the form of two-dimensional nanodendrites could enable highly stable and selective formate production. Such unique bimetallic nanostructures are formed as a result of the rapid in-plane growth and suppressed out-of-plane growth by carefully controlling a set of experimental parameters. Thanks to the combined electronic effect and nanostructuring effect, our alloy product catalyzes CO2 reduction to formate with remarkable stability and selectivity under the working potential as cathodic as -0.4 V. Our results are rationalized by computational simulations, evidencing that Cu atoms weaken the *CO adsorption and stabilize the *OCHO adsorption on neighboring Pd atoms.

9.
Eur J Clin Invest ; 51(3): e13385, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32810282

RESUMO

INTRODUCTION: Atrial fibrillation (AF) and diabetes mellitus (DM) constitute a heavy burden on healthcare expenditure due to their negative impact on clinical outcomes in the Middle East. The Atrial fibrillation Better Care (ABC) pathway provides a simple strategy of integrated approach of AF management: A-Avoid stroke; B-Better symptom control; C-Cardiovascular comorbidity risk management. AIMS: Evaluation of the AF treatment compliance to ABC pathway in DM patients in the Middle East. Assessment of the impact of ABC pathway adherence on all-cause mortality and the composite outcome of stroke/systemic embolism, all-cause death and cardiovascular hospitalisations. METHODS: From 2043 patients in the Gulf SAFE registry, 603 patients (mean age 63; 48% male) with DM were included in an analysis of ABC pathway compliance: A-appropriate use of anticoagulation according to CHA2 DS2 -VASc score; B-AF symptoms management according to the European Heart Rhythm Association (EHRA) scale; C-Optimised cardiovascular comorbidities management. RESULTS: 86 (14.3%) patients were treated in compliance with the ABC pathway. During 1-year follow-up, 207 composite outcome events and 87 deaths occurred. Mortality was significantly lower in the ABC group vs non-ABC (5.8% vs 15.9%, P = .0014, respectively). On multivariate analysis, ABC compliance was associated with a lower risk of all-cause death and the composite outcome after 6 months (OR 0.18; 95% CI: 0.42-0.75 and OR 0.54; 95% Cl: 0.30-1.00, respectively) and at 1 year (OR 0.30; 95% Cl: 0.11-0.76 and OR 0.57; 95% Cl: 0.33-0.97, respectively) vs the non-ABC group. CONCLUSIONS: Compliance with the ABC pathway care was independently associated with the reduced risk of all-cause death and the composite outcome in DM patients with AF, highlighting the importance of an integrated approach to AF management.


Assuntos
Anticoagulantes/uso terapêutico , Fibrilação Atrial/tratamento farmacológico , Complicações do Diabetes , Diabetes Mellitus , Inibidores da Agregação Plaquetária/uso terapêutico , Acidente Vascular Cerebral/prevenção & controle , Idoso , Antiarrítmicos/uso terapêutico , Fibrilação Atrial/complicações , Fibrilação Atrial/fisiopatologia , Doenças Cardiovasculares , Causas de Morte , Embolia/etiologia , Embolia/prevenção & controle , Feminino , Fidelidade a Diretrizes , Fatores de Risco de Doenças Cardíacas , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Oriente Médio , Mortalidade , Guias de Prática Clínica como Assunto , Sistema de Registros , Acidente Vascular Cerebral/etiologia
10.
Arch Biochem Biophys ; 701: 108818, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33617838

RESUMO

Pentraxin 3 (PTX3) has been documented to be involved in the development of chemoresistance, however, the mechanisms by which it regulates cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC) have never been elucidated. Quantitative reverse transcriptase polymerase chain reaction and Western blot were carried to determine the expression of PTX3, ATP-binding cassette sub-family B member 1 (ABCB1)/P-glycoprotein 1 (p-gp), protein kinase B (Akt), phosphorylated Akt and nuclear factor-kappa B (NF-кB) p65. The biological roles of PTX3 in NSCLC progression and NSCLC cell resistance to DDP were evaluated using enzyme-linked immunosorbent assay, cell count kit-8, colony formation assay, flow cytometry, as well as xenograft tumor assay. The expression of PTX3 was increased in the serum of NSCLC patients as well as in NSCLC cell lines. Lower PTX3 level was associated with longer overall survival in lung adenocarcinoma and lung squamous cell carcinoma patients. Furthermore, PTX3 expression was greatly higher in DDP-resistant NSCLC cells than that in NSCLC cells. Silencing of PTX3 restrained the proliferation and promoted the apoptosis of NSCLC cells, as well as sensitized DDP-resistant NSCLC cells to DDP. Additionally, knockdown of PTX3 inhibited the growth of NSCLC tumors in vivo. Upregulation of PTX3 expression was dependent on the activation of Akt/NF-κB signaling. The induction of apoptosis by PTX3 knockdown was enhanced by MK-2206 or JSH-23. In conclusion, knockdown of PTX3 restrained the progression of NSCLC and sensitized NSCLC cells towards DDP, which provides a potential target to restore DDP chemoresponse.


Assuntos
Proteína C-Reativa/metabolismo , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos , Neoplasias Pulmonares/metabolismo , Componente Amiloide P Sérico/metabolismo , Transdução de Sinais , Células A549 , Animais , Proteína C-Reativa/genética , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Componente Amiloide P Sérico/genética , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo
11.
Angew Chem Int Ed Engl ; 60(40): 21741-21745, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34382309

RESUMO

Alloying is a general strategy for modulating the electronic structures of catalyst materials. Compared to more common solid-solution alloys, intermetallic alloys feature well-defined atomic arrangements and provide the unique platform for studying the structure-performance correlations. It is, unfortunately, synthetically challenging to prepare the nanostructures of intermetallic alloys for catalysis research. In this contribution, we prepare intermetallic Pd3 Bi nanocrystals of a uniform size via a facile solvothermal method. These nanocrystals can phase-transform into solid solution alloy via thermal annealing while retaining a similar composition and size. In 0.1 M KHCO3 aqueous solution, the intermetallic Pd3 Bi can selectively reduce CO2 to formate with high selectivity (≈100 %) and stability even at <-0.35 V versus reversible hydrogen electrode, whereas the solid solution alloy has limited formate selectivity of <60 %. Such unique phase-dependence is understood via theoretical simulations showing that the crystallographic ordering of Pd and Bi atoms within intermetallic alloys can suppress CO poisoning and enhance the *OCHO adsorption during electrochemical CO2 reduction to formate.

12.
Angew Chem Int Ed Engl ; 60(11): 5771-5777, 2021 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-33331055

RESUMO

Bifunctional hydrogen electrocatalysis (hydrogen-oxidation and hydrogen-evolution reactions) in alkaline solution is desirable but challenging. Among all available electrocatalysts, Ni-based materials are the only non-precious-metal-based candidates for alkaline hydrogen oxidation, but they generally suffer from low activity. Here, we demonstrate that properly alloying Ni with Mo could significantly promote its electrocatalytic performance. Ni4 Mo alloy nanoparticles are prepared from the reduction of molybdate-intercalated Ni(OH)2 nanosheets. The final product exhibits an apparent hydrogen-oxidation activity exceeding that of the Pt benchmark and a record-high mass-specific kinetic current of 79 A g-1 at an overpotential of 50 mV. A superior hydrogen-evolution performance is also measured in alkaline solution. These experimental data are rationalized by our theoretical simulations, which show that alloying Ni with Mo significantly weakens its hydrogen adsorption, improves the hydroxyl adsorption and decreases the reaction barrier for water formation.

13.
Angew Chem Int Ed Engl ; 60(29): 15844-15848, 2021 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-33973698

RESUMO

The size modulation of catalyst particles represents a useful dimension to tune catalytic performances by impacting not only their surface areas but also local electronic structures. It, however, has remained inadequately explored and poorly elucidated. Here, we report the interesting size-dependent selectivity of electrochemical CO2 reduction on In2 O3 nanocrystals. 5-nm nanoparticles and 15-nm nanocubes with focused size distribution are prepared via a facile solvothermal reaction in oleylamine by carefully controlling a set of experimental parameters. They serve as the precatalysts, and are reduced to In nanocrystals while largely inherit the original size feature during electrochemical CO2 reduction. Catalyst derived from 15-nm nanocubes exhibits greater formate selectivity (>95 %) at lower overpotential and negligible side reactions compared to bulk-like samples (indium foil and 200-nm cubes) as well as the catalyst derived from smaller 5-nm nanoparticles. This unique size dependence is rationalized as a result of the competition among different reaction pathways by our theoretical computations. Smaller is not always better in the catalyst design.

14.
Proc Natl Acad Sci U S A ; 114(50): 13091-13096, 2017 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-29180431

RESUMO

Many problems associated with Li-S and Na-S batteries essentially root in the generation of their soluble polysulfide intermediates. While conventional wisdom mainly focuses on trapping polysulfides at the cathode using various functional materials, few strategies are available at present to fully resolve or circumvent this long-standing issue. In this study, we propose the concept of sulfur-equivalent cathode materials, and demonstrate the great potential of amorphous MoS3 as such a material for room-temperature Li-S and Na-S batteries. In Li-S batteries, MoS3 exhibits sulfur-like behavior with large reversible specific capacity, excellent cycle life, and the possibility to achieve high areal capacity. Most remarkably, it is also fully cyclable in the carbonate electrolyte under a relatively high temperature of 55 °C. MoS3 can also be used as the cathode material of even more challenging Na-S batteries to enable decent capacity and good cycle life. Operando X-ray absorption spectroscopy (XAS) experiments are carried out to track the structural evolution of MoS3 It largely preserves its chain-like structure during repetitive battery cycling without generating any free polysulfide intermediates.

15.
Angew Chem Int Ed Engl ; 59(34): 14378-14382, 2020 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-32485021

RESUMO

Photocatalytic hydrogenation of biomass-derived organic molecules transforms solar energy into high-energy-density chemical bonds. Reported herein is the preparation of a thiophene-containing covalent triazine polymer as a photocatalyst, with unique donor-acceptor units, for the metal-free photocatalytic hydrogenation of unsaturated organic molecules. Under visible-light illumination, the polymeric photocatalyst enables the transformation of maleic acid into succinic acid with a production rate of about 2 mmol g-1 h-1 , and furfural into furfuryl alcohol with a production rate of about 0.5 mmol g-1 h-1 . Great catalyst stability and recyclability are also measured. Given the structural diversity of polymeric photocatalysts and their readily tunable optical and electronic properties, metal-free photocatalytic hydrogenation represents a highly promising approach for solar energy conversion.

16.
Environ Sci Technol ; 53(15): 8574-8584, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31248249

RESUMO

Organic compounds are important contributors to the oxidative potential (OP) of atmospheric aerosols. This study is the first to report the OP of water-soluble organic matter (WSOM) related to the chromophoric substances in PM2.5 over Xi'an, China. The dithiothreitol (DTT) activity levels in PM2.5 extracted by water were quantified as well as the relationships between DTT activity and light absorption and fluorescence properties. The results show that the DTT activity has significantly correlated with colored WSOM, in which we identified three light absorbing substances (BrC1-3) and eight fluorescent substances (C1-8). It is further found that BrC3 and C7 accounted for almost all of the DTT activity by colored WSOM, although these two factors contributed only a small fraction of light absorption and fluorescence. BrC3 and C7 are clearly distinguished from other chromophoric substances because of their long absorption wavelength (λmax = 475 nm) and fluorescence emission wavelength (λmax = 462 nm), respectively. This discovery will help to better interpret and understand the mechanism of oxidation activity generation by light absorbing organic aerosols and provide guidance for predicting the OPs of light absorbing organic aerosols based on their optical properties.


Assuntos
Poluentes Atmosféricos , Material Particulado , Aerossóis , China , Monitoramento Ambiental , Estresse Oxidativo , Água
17.
Angew Chem Int Ed Engl ; 58(26): 8676-8680, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-30882957

RESUMO

Conjugated polymers have emerged as promising candidates for photocatalytic H2 production owing to their structural designability and functional diversity. However, the fast recombination of photoexcited electrons and holes limits their H2 production rates. We have now designed molecular heterostructures of covalent triazine frameworks to facilitate charge-carrier separation and promote photocatalytic H2 production. Benzothiadiazole and thiophene moieties were selectively incorporated into the covalent triazine frameworks as electron-withdrawing and electron-donating units, respectively, by a sequential polymerization strategy. The resulting hybrids exhibited much improved charge-carrier-separation efficiency as evidenced by photophysical and electrochemical characterization. An H2 evolution rate of 6.6 mmol g-1 h-1 was measured for the optimal sample under visible-light irradiation (λ>420 nm), which is far superior to that of most reported conjugated-polymer photocatalysts.

18.
Curr Atheroscler Rep ; 20(7): 32, 2018 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-29781063

RESUMO

PURPOSE OF REVIEW: Decision-making on resuming oral anticoagulant (OAC) after intracerebral hemorrhage (ICH) evokes significant debate among clinicians. Such patients have been excluded from randomized clinical trials. This review article provides a comprehensive summary of the evidence on anticoagulation resumption after ICH. RECENT FINDINGS: OAC resumption does not increase the risk of recurrent ICH and can also reduce the risk of all-cause mortality. OAC cessation exposes patients to a significantly higher risk of thromboembolism, which could be reduced by resumption. The optimal timing of anticoagulation resumption after ICH is still unknown. Both early (< 2 weeks) and late (> 4 weeks) resumption should be reached only after very careful assessment of risks for ICH recurrence and thromboembolism. The introduction of new oral anticoagulants and other interventions, such as left atrial appendage closure, has provided some patients with more alternatives. Given the lack of high-quality evidence to guide clinical decision-making, clinicians must carefully balance the risks of thromboembolism and recurrent ICH in individual patients. We propose a management approach which would facilitate the decision-making process on whether anticoagulation is appropriate, as well as when and how to restart anticoagulation after ICH.


Assuntos
Anticoagulantes/administração & dosagem , Hemorragia Cerebral/induzido quimicamente , Tromboembolia/tratamento farmacológico , Anticoagulantes/uso terapêutico , Hemorragia Cerebral/mortalidade , Humanos , Recidiva , Medição de Risco , Tromboembolia/etiologia , Tromboembolia/prevenção & controle
19.
Environ Sci Technol ; 52(17): 9646-9655, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30071162

RESUMO

To understand the nature and possible sources of environmentally persistent free radicals (EPFRs) in atmospheric aerosols, the present study used a solvent extraction method to fractionate aerosol components with different polarities and solvent resistance in fine particulate matter (PM2.5) from Xi'an, China. The characteristics of EPFRs, that is., their concentration, type and lifetime, were obtained based on their electron paramagnetic resonance spectra. The results showed that the EPFRs in the PM2.5 samples were carbon-centered with a nearby heteroatom ( g = 2.0031) and had a long half-life of more than 3 years. Nearly all of the extractable EPFRs were detected in the water-insoluble organic fraction and showed characteristics indicating that may contain oxygen-centered radical ( g = 2.0038). Most of the total EPFRs in the PM2.5 were derived from solvent-resistant organic matter (88%), which likely consisted of graphene oxide analogues. The results suggest that previous studies may have missed the major proportion of EPFRs in atmospheric particulates if they only focused on solvent-extractable or metallic oxide-formed EPFRs. Our results showed that the EPFR concentration was significantly and positively correlated with the elemental carbon and NO2 concentrations, suggesting that traffic emissions may be an important source of EPFRs in PM2.5 over Xi'an.


Assuntos
Poluentes Atmosféricos , China , Poeira , Radicais Livres , Material Particulado
20.
Nano Lett ; 17(7): 4137-4142, 2017 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-28628326

RESUMO

Sodium-ion batteries are potential low-cost alternatives to current lithium-ion technology, yet their performances still fall short of expectation due to the lack of suitable electrode materials with large capacity, long-term cycling stability, and high-rate performance. In this work, we demonstrated that ultrasmall (∼5 nm) iron selenide (FeSe2) nanoparticles exhibited a remarkable activity for sodium-ion storage. They were prepared from a high-temperature solution method with a narrow size distribution and high yield and could be readily redispersed in nonpolar organic solvents. In ether-based electrolyte, FeSe2 nanoparticles exhibited a large specific capacity of ∼500 mAh/g (close to the theoretical limit), high rate capability with ∼250 mAh/g retained at 10 A/g, and excellent cycling stability at both low and high current rates by virtue of their advantageous nanosizing effect. Full sodium-ion batteries were also constructed from coupling FeSe2 with NASICON-type Na3V2(PO4)3 cathode and demonstrated impressive capacity and cycle ability.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA