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1.
J Colloid Interface Sci ; 606(Pt 1): 204-212, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34388571

RESUMO

Exploring high-efficiency metal-free electrocatalysts towards N2 reduction reaction (NRR) is of great interest for the development of electrocatalytic N2 fixation technology. Herein, we combined boron nitride quantum dots (BNQDs) and graphitic carbon nitride (C3N4) to design a metal-free BNQDs/C3N4 heterostructure as an effective and durable NRR catalyst. The electronically coupled BNQDs/C3N4 presented an NH3 yield as high as 72.3 µg h-1 mg-1 (-0.3 V) and a Faradaic efficiency of 19.5% (-0.2 V), far superior to isolated BNQDs and C3N4, and outperforming nearly all previously reported metal-free catalysts. Theoretical computations unveiled that the N2 activation could be drastically enhanced at the BNQDs-C3N4 interface where interfacial BNQDs and C3N4 cooperatively adsorb N2 and stabilize *N2H intermediate, leading to the significantly promoted NRR process with an ultra-low overpotential of 0.23 V.

2.
J Hazard Mater ; 423(Pt A): 127053, 2022 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-34523495

RESUMO

Nickel@MXene quantum dots (Ni@MQDs), as novel flower-like hybrid materials, were firstly prepared through a simple reduction method. The Ni@MQDs exhibited an outstanding catalytic performance for Cr (VI) reduction with a low activation energy (Ea = 18.9 kJ mol-1) and a high kinetic constant (k = 0.4779 min-1) in the presence of formic acid (HCOOH). Density functional theory calculations demonstrated that Ni@MQDs exhibited an upshift of d-band center of active Ni atoms to promote the adsorption of both HCOOH and active H atoms, as well as an improved conductivity to boost the catalytic reaction kinetics, leading to the most favorable catalytic performance. This work may open up a new avenue towards the design and synthesis of novel MQDs-based hybrid catalysts for wastewater treatment.

3.
Chem Commun (Camb) ; 57(77): 9930-9933, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34498632

RESUMO

We demonstrate that MoS2 quantum dots (QDs) can be an effective and durable catalyst for the electrocatalytic N2 reduction reaction (NRR), showing an NH3 yield of 39.6 µg h-1 mg-1 with a faradaic efficiency of 12.9% at -0.3 V, far superior to MoS2 nanosheets and outperforming most reported NRR catalysts. Density functional theory computations unravel that the MoS2 QDs can dramatically facilitate N2 adsorption and activation via side-on patterns, resulting in an energetically-favored enzymatic pathway with an ultra-low overpotential of 0.29 V.

4.
Small ; 17(40): e2102363, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34499407

RESUMO

Electrochemical N2 fixation represents a promising strategy toward sustainable NH3 synthesis, whereas the rational design of high-performance catalysts for the nitrogen reduction reaction (NRR) is urgently required but remains challenging. Herein, a novel hexagonal BN quantum dots (BNQDs) decorated Nb2 CTx -MXene (BNQDs@Nb2 CTx ) is explored as an efficient NRR catalyst. BNQDs@Nb2 CTx presents the optimum NRR activity with an NH3 yield rate of 66.3 µg h-1 mg-1 (-0.4 V) and a Faradaic efficiency of 16.7% (-0.3 V), outperforming most of the state-of-the-art NRR catalysts, together with an excellent stability. Theoretical calculations revealed that the synergistic interplay of BNQDs and Nb2 CTx enabled the creation of unique interfacial B sites serving as NRR catalytic centers capable of enhancing the N2 activation, lowering the reaction energy barrier and impeding the H2 evolution.


Assuntos
Pontos Quânticos , Compostos de Boro , Nióbio , Nitrogênio , Tomografia Computadorizada por Raios X
5.
Chemosphere ; 281: 130977, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289625

RESUMO

Per-, Poly-fluoroalkyl substances (PFASs) accumulation in benthic environments is mainly determined by material mixing and represents a significant challenge to river remediation. However, less attention has been paid to the effects of sediment distribution on PFASs accumulation, and how PFASs influence microbial community coalescence and biogeochemical processes. In order to identify correlations between PFASs distribution and benthic microbial community functions, we conducted a field study and quantified the ecological constrains of material transportation on benthic microorganisms. Perfluorohexanoic acid (PFHxA) contributed most to the taxonomic heterogeneity of both archaeal (12.199%) and bacterial (13.675%) communities. Genera Methanoregula (R2 = 0.292) and Bacillus (R2 = 0.791) were identified as indicators that respond to PFASs. Phylogenetic null modeling indicated that deterministic processes (50.0-82.2%) dominated in spatial assembly of archaea, while stochasticity (94.4-97.8%) dominated in bacteria. Furthermore, spatial mixing of PFASs influenced broadly in nitrogen cycling of archaeal genomes, and phosphorus mineralization of bacterial genomes (p < 0.05). Overall, we quantified the effect of PFASs on community assembly and highlighted the constrains of PFASs influence on benthic geochemical potentials, which may provide new insights into riverine remediation.


Assuntos
Fluorcarbonetos , Microbiota , Archaea/genética , Ecossistema , Fluorcarbonetos/análise , Sedimentos Geológicos , Filogenia , Rios
6.
J Nucl Cardiol ; 28(2): 560-574, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30993654

RESUMO

BACKGROUND: This study aimed to compare the accuracy of gated-SPECT (GSPECT) and gated-PET (GPET) in the assessment of left ventricular (LV) end-diastolic volumes (EDVs), end-systolic volumes (ESVs) and LV ejection fractions (LVEFs) among patients with prior myocardial infarction (MI). METHODS: One hundred and sixty-eight consecutive patients with MI who underwent GSPECT and GPET were included. Of them, 76 patients underwent CMR in addition to the two imaging modalities. The measurements of LV volumes and LVEF were performed using Quantitative Gated SPECT (QGS), Emory Cardiac Toolbox (ECTB), and 4D-MSPECT (4DM). RESULTS: The correlation between GPET, GSPECT, and CMR were excellent for LV EDV (r = 0.855 to 0.914), ESV (r = 0.852 to 0.949), and LVEF (r = 0.618 to 0.820), as calculated from QGS, ECTB, and 4DM. In addition, subgroup analysis revealed that EDV, ESV, and LVEF measured by GPET were accurate in patients with different extents of total perfusion defect (TPD), viable myocardium, and perfusion/metabolic mismatch. Furthermore, multivariate regression analysis identified that mismatch score was associated with the difference in EDV (P < 0.05) measurements between GPET and CMR. CONCLUSIONS: In patients with MI, LV volumes and LVEF scores measured by both GSPECT and GPET imaging were comparable to those determined by CMR, but should not be interchangeable in individual patients.

7.
J Hazard Mater ; 401: 123252, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-32634663

RESUMO

Determination of the effects of Escherichia coli (E. coli) pollution on agricultural pond ecosystems with vegetation at different life stages is essential for the protection of ecological functions. However, no comprehensive study has yet shown the responses of epiphytic microbial communities to E. coli invasion during plant decay. Thus, this study was conducted to clarify variation in the decay of the following aquatic plants-Myriophyllum aquaticum, Nymphaea tetragona and Phragmites australis after E. coli pollution. Exogenous E. coli especially shifted the epiphytic microbial composition and distribution of P. australis. Stronger effects of E. coli on the archaeal community (edges/nodes = 0.818 < 1, modularity = 0.654; lower clustered structure, 0.389) were found than on the bacterial community (edges/nodes = 1.538 > 1, modularity = 1.291 > 0.654; higher clustered, 0.593). During plant decomposition, E. coli weakened methanogenesis by regulating the network of core genera Methanobacterium and Methanospirillum (spearman, P < 0.05), stimulated the accumulation of organic matters in water (P < 0.05). Similarly, nitrification and denitrification increased and decreased through network regulation in relative biomass of genera Devosia and Desulfovibrio (P < 0.05), respectively. The results provided theoretical supports for eutrophication management in pond ecosystems threatened by E. coli pollution.


Assuntos
Escherichia coli , Microbiota , Archaea , Escherichia coli/genética , Nutrientes , Plantas
8.
Chem Commun (Camb) ; 56(85): 13009-13012, 2020 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-32996944

RESUMO

ZrB2 is first explored as an earth-abundant metal diboride catalyst for highly efficient nitrogen reduction reaction (NRR). The synthesized ZrB2 nanocubes exhibited a highly attractive NRR performance with an NH3 yield of 37.7 µg h-1 mg-1 and a Faradaic efficiency 18.2% at -0.3 V (RHE). Theoretical calculations unraveled that active Zr centers enabled the effective activation of the N2 molecule via a unique tetranuclear side-on mode and concurrently impeded hydrogen evolution by restricting H+ adsorption.

9.
Dalton Trans ; 49(36): 12559-12564, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32926054

RESUMO

Ambient electrocatalytic N2 reduction reaction (NRR) provides an eco-friendly way for artificial NH3 production, while an efficient NRR process requires active and stable electrocatalysts. In this communication, we exploit the spinel ferrite NiFe2O4 as a promising NRR catalyst. The developed NiFe2O4 nanocubes/reduced graphene oxide (NiFe2O4/RGO) exhibited an appealing NRR performance with an NH3 yield of 32.2 µg h-1 mg-1 and a faradaic efficiency (FE) of 9.8% at -0.5 V (RHE), as well as a high catalytic durability. Mechanistic investigations revealed that the surface Fe atoms serve as key NRR active sites for favorable N2 adsorption and H+ suppression. These findings may facilitate the understanding and exploration of Earth-abundant spinel ferrite catalysts for electrochemical dinitrogen fixation.

10.
Chem Commun (Camb) ; 56(72): 10505-10508, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32776057

RESUMO

The electrocatalytic N2 reduction reaction (NRR) offers a sustainable route for ambient NH3 production. To ensure a high NRR efficiency, it is critically important to design active electrocatalysts which possess a strong electron-donating capability to activate the stable N[triple bond, length as m-dash]N bond and facilitate the protonation process. Herein, inspired by the FeV-cofactor as a catalytic site for biological N2 fixation, we show that the FeVO4 can be a highly efficient and durable NRR catalyst. The developed FeVO4 porous nanorods delivered a favorable combination of both high NH3 production rate (52.8 µg h-1 mg-1) and high faradaic efficiency (15.7%), surpassing those of nearly all the previously reported Fe- and V-based catalysts. Theoretical computations revealed that the high NRR performance of FeVO4 originated from the Fe2c-V2c dimer (2c means two-fold coordinated bond) as a dual electron-donation center to effectively activate the NRR with a low overpotential.

11.
Chem Commun (Camb) ; 56(71): 10345-10348, 2020 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-32760985

RESUMO

The antimony sulfide Sb2S3 is firstly explored as a Janus catalyst for highly selective nitrogen reduction reaction (NRR). The developed Sb2S3 nanoflowers delivered an excellent faradaic efficiency of 24.1% and a high NH3 yield of 33.4 µg h-1 mg-1 at -0.3 V. Theoretical calculations revealed that the high NRR selectivity of Sb2S3 originated from the Janus role of active Sb centers: on one hand, Sb exhibited a strong Sb5p-N2p hybridization upon initial N2 protonation, capable of effectively activating the NRR with a low reaction barrier. On the other hand, Sb could concurrently impede the hydrogen evolution by hindering the H+ adsorption.

12.
Angew Chem Int Ed Engl ; 59(47): 20868-20872, 2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-32749018

RESUMO

The radial conjugated π-system of cycloparaphenylenes (CPPs) makes them intriguing fluorophores and unique supramolecular hosts. However, the bright photoluminescence (PL) of CPPs was limited to the blue light and the supramolecular assembly behavior of large CPPs was rarely investigated. Here we present the synthesis of tetra-benzothiadiazole-based [12]cycloparaphenylene (TB[12]CPP), which exhibits a lime to orange PL with an excellent quantum yield up to 82 % in solution. The PL quantum yield of TB[12]CPP can be further improved to 98 % in polymer matrix. Benefiting from its enlarged size, TB[12]CPP can accommodate a fullerene derivative or concave-convex complexes of fullerene and buckybowl through the combined π-π and C-H⋅⋅⋅π interactions. The latter demonstrates the first case of a ternary supramolecule of CPPs.

13.
Chem Commun (Camb) ; 56(70): 10227-10230, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32749406

RESUMO

The nitrogen reduction reaction (NRR) is a key step in electrochemical nitrogen fixation and exploring high-performance electrocatalysts is of paramount significance for achieving the desired NRR efficiency. Herein, we demonstrate that bimetallic MnMoO4 can be a highly active and durable NRR catalyst. The developed MnMoO4 nanorods-reduced graphene oxide presented a favorable combination of both high NH3 yield (60.3 µg h-1 mg-1) and high faradaic efficiency (14.7%), surpassing nearly all of the previously reported Mn and Mo-based NRR catalysts. Theoretical calculations revealed that the surface-terminated Mn and Mo atoms functioned as dual-active-centers to synergistically boost the NRR and suppress the adverse hydrogen evolution.

14.
ACS Appl Mater Interfaces ; 12(33): 37258-37264, 2020 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-32814395

RESUMO

Electrochemical nitrogen fixation offers a promising route for sustainable NH3 production, while the rational design of effective and durable electrocatalysts is urgently required for an effective nitrogen reduction reaction (NRR) process. Herein, we explore lithium iron oxide (LiFeO2) as a potential NRR catalyst. The developed LiFeO2/reduced graphene oxide (rGO) delivered a combination of both a high NH3 yield (40.5 µg h-1 mg-1) and high Faradaic efficiency (16.4%), exceeding those of nearly all the previously reported Li- and Fe-based catalysts. Theoretical computations showed that Fe and Li atoms on the LiFeO2 (111) facet synergistically activated N2 while Fe atoms served as the key active centers. Meanwhile, the undesired HER can be well impeded on both Fe and Li atoms to enable a high NRR selectivity.

15.
Cancer Med ; 9(18): 6524-6532, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32705800

RESUMO

OBJECTIVE: We aimed to assess the impact of the treatment modality on the outcome of small cell neuroendocrine cervical carcinoma (SCNEC) using the Surveillance Epidemiology and End Results (SEER) database. METHODS: Patients from the SEER program between 1981 and 2014 were identified. Significant factors for cancer-specific survival (CSS) and overall survival (OS) were analyzed using the Kaplan-Meier survival and Cox regression methods. RESULTS: A total of 503 SCNEC patients were identified. The 5-year CSS and OS were 36.6% and 30.6%, respectively. The International Federation of Gynecology and Obstetrics (FIGO) stage I to IV distributions was 189 (37.6%), 108 (21.5%), 95 (18.9%), and 111 patients (22.0%), respectively. Within the patients with known treatment strategies, 177 (45.9%) were treated with radical surgery and 209 (54.1%) underwent primary radiotherapy. Local treatment strategies were independent prognostic factor for CSS and OS. The 5-year CSS for radical surgery and primary radiotherapy was 50.0% and 27.9%, respectively (P < .001). The 5-year OS for those who received radical surgery and primary radiotherapy was 57.8%, and 29.6%, respectively (P < .001). In FIGO stage I SCNEC, patients treated with radical surgery had superior CSS (P = .001) and OS (P = .003) than those with primary radiotherapy. However, in FIGO stage II and III SCNEC, there were no differences in CSS and OS with respect to different local treatment strategies. Our results also found that the addition of brachytherapy impacted OS in the FIGO stage III SENCE (P = .002). The 5-year CSS and OS of patients with FIGO IV were only 11.7% and 7.1%, respectively. CONCLUSIONS: SCNEC is a rare disease with aggressive clinical behavior. The findings indicate that radical surgery should be suggested for early-stage SCNEC and combining radiation therapy with brachytherapy should be suitable for patients with advanced stage.


Assuntos
Antineoplásicos/uso terapêutico , Braquiterapia , Carcinoma Neuroendócrino/terapia , Carcinoma de Células Pequenas/terapia , Histerectomia , Exenteração Pélvica , Neoplasias do Colo do Útero/terapia , Antineoplásicos/efeitos adversos , Braquiterapia/efeitos adversos , Braquiterapia/mortalidade , Carcinoma Neuroendócrino/mortalidade , Carcinoma Neuroendócrino/patologia , Carcinoma de Células Pequenas/mortalidade , Carcinoma de Células Pequenas/patologia , Bases de Dados Factuais , Feminino , Humanos , Histerectomia/efeitos adversos , Histerectomia/mortalidade , Estadiamento de Neoplasias , Exenteração Pélvica/efeitos adversos , Exenteração Pélvica/mortalidade , Medição de Risco , Fatores de Risco , Programa de SEER , Fatores de Tempo , Resultado do Tratamento , Estados Unidos , Neoplasias do Colo do Útero/mortalidade , Neoplasias do Colo do Útero/patologia
16.
J Environ Manage ; 261: 110204, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32148275

RESUMO

The effects of exogenous Escherichia coli on nitrogen cycling (N-cycling) in freshwater remains unclear. Thus, seven ecosystems, six with submerged plants-Potamogeton crispus (PC) and Myriophyllum aquaticum (MA)-and one with no plants were set up. Habitats were assessed before and after E. coli addition (107 colony-forming units/mL). E. coli colonization of freshwater ecosystems had significant effects on bacterial community structure in plant surface biofilms and surface sediments (ANOVA, P < 0.05). It reduced the relative abundance of nitrosification bacteria (-70.94 ± 26.17%) and nitrifiers (-47.86 ± 23.68%) in biofilms which lead to significant reduction of ammoxidation in water (P < 0.05). The N-cycling intensity from PC systems was affected more strongly by E. coli than were MA systems. Furthermore, the coupling coefficient of exogenous E. coli to indigenous N-cycling bacteria in sediments (6.061, average connectivity degree) was significantly weaker than that in biofilms (9.852). Additionally, at the genus level, E. coli were most-closely associated with N-cycling bacteria such as Prosthecobacter, Hydrogenophaga, and Bacillus in sediments and biofilms according to co-occurrence bacterial network (Spearman). E. coli directly changed their abundance, so that the variability of species composition of N-cycling bacterial taxa was triggered, as well. Overall, exogenous E. coli repressed ammoxidation, but promoted ammonification and denitrification. Our results provided new insights into how pathogens influence the nitrogen cycle in freshwater ecosystems.


Assuntos
Ecossistema , Escherichia coli , Bactérias , Nitrogênio , Ciclo do Nitrogênio
17.
ACS Appl Mater Interfaces ; 12(10): 11789-11796, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32091874

RESUMO

Electroreduction of N2 represents a promising technique for ambient NH3 synthesis, but exploring efficient electrocatalysts for nitrogen reduction reaction (NRR) remains a key challenge. Herein, we reported our experimental and theoretical findings that FeMoO4 could be a new candidate for effective and durable NRR in neutral solution. The developed FeMoO4 nanorods exhibited a fascinating NRR activity with an NH3 yield of 45.8 µg h-1 mg-1 (-0.5 V) and a Faradaic efficiency of 13.2% (-0.3 V). Mechanistic studies disclosed that Fe and Mo synergistically promoted the N2 adsorption and accelerated the electron transfer on FeMoO4, whereas the unsaturated 3-fold coordinated Mo (Mo3c) sites served as the main active centers for stabilizing the key *N2H intermediate and reducing the reaction energy barrier.

18.
ACS Appl Mater Interfaces ; 12(6): 7081-7090, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31965787

RESUMO

The electrochemical nitrogen reduction reaction (NRR) is a very efficient method for sustainable NH3 production, but it requires effective catalysts to expedite the NRR kinetics and inhibit the concomitant hydrogen evolution reaction (HER). Two-dimensional (2D)/2D interface engineering is an effective method to design powerful catalysts due to intimate face-to-face contact of two 2D materials that facilitates the strong interfacial electronic interactions. Herein, we explored a 2D/2D MoS2/C3N4 heterostructure as an active and stable NRR catalyst. MoS2/C3N4 exhibited a conspicuously improved NRR performance with an NH3 yield of 18.5 µg h-1 mg-1 and a high Faradaic efficiency (FE) of 17.8% at -0.3 V, far better than those of the individual MoS2 or C3N4 component. Density functional theory calculations revealed that the interfacial charge transport from C3N4 to MoS2 could enhance the NRR activity of MoS2/C3N4 by promoting the stabilization of the key intermediate *N2H on Mo edge sites of MoS2 and concurrently decreasing the reaction energy barrier. Meanwhile, MoS2/C3N4 rendered a more favorable *H adsorption free energy on S edge sites than on Mo edge sites of MoS2, thereby protecting the NRR-active Mo edge sites from the competing HER and leading to a high FE.

20.
ACS Appl Mater Interfaces ; 11(35): 31806-31815, 2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31424200

RESUMO

Electrocatalytic N2 reduction reaction (NRR) provides an effective and renewable approach for artificial NH3 production, but still remains a grand challenge because of the low NH3 yield and Faradaic efficiency (FE). Herein, we reported that the SnO2 quantum dots (QDs) supported on reduced graphene oxide (RGO) could efficiently and stably catalyze NRR at ambient conditions. The NRR performance of resulting SnO2/RGO was studied by both experimental techniques and density functional theory calculations. It was found that the ultrasmall SnO2 QDs (2 nm) grown on RGO could provide abundant sites for efficient N2 adsorption. Significantly, the strongly electronically coupled SnO2 QDs and RGO brought about the enhanced conductivity and the decreased work function, which led to a considerably lowered energy barrier of *N2 → *N2H that was the rate-determining step of the NRR process. Meanwhile, the SnO2/RGO exhibited inferior hydrogen evolution reaction activity. As a result, the SnO2/RGO delivered a high NH3 yield of 25.6 µg h-1 mg-1 (5.1 µg cm-2h-1) and an FE of 7.1% in 0.1 M Na2SO4 at -0.5 V (vs RHE), together with the outstanding selectivity and stability, endowing it as a promising electrocatalyst for N2 fixation.

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