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1.
Artigo em Inglês | MEDLINE | ID: mdl-32224457

RESUMO

Existing enhancement methods are empirically expected to help the high-level end computer vision task: however, that is observed to not always be the case in practice. We focus on object or face detection in poor visibility enhancements caused by bad weathers (haze, rain) and low light conditions. To provide a more thorough examination and fair comparison, we introduce three benchmark sets collected in real-world hazy, rainy, and low-light conditions, respectively, with annotated objects/faces. We launched the UG2+ challenge Track 2 competition in IEEE CVPR 2019, aiming to evoke a comprehensive discussion and exploration about whether and how low-level vision techniques can benefit the high-level automatic visual recognition in various scenarios. To our best knowledge, this is the first and currently largest effort of its kind. Baseline results by cascading existing enhancement and detection models are reported, indicating the highly challenging nature of our new data as well as the large room for further technical innovations. Thanks to a large participation from the research community, we are able to analyze representative team solutions, striving to better identify the strengths and limitations of existing mindsets as well as the future directions.

2.
Sci Eng Ethics ; 2020 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-32215814

RESUMO

The last two decades have witnessed the rising prevalence of both co-publishing and retraction. Focusing on research collaboration, this paper utilizes a unique dataset to investigate factors contributing to retraction probability and elapsed time between publication and retraction. Data analysis reveals that the majority of retracted papers are multi-authored and that repeat offenders are collaboration prone. Yet, all things being equal, collaboration, in and of itself, does not increase the likelihood of producing flawed or fraudulent research, at least in the form of retraction. That holds for all retractions and also retractions due to falsification, fabrication, and plagiarism (FFP). The research also finds that publications with authors from elite universities are less likely to be retracted, which is particularly true for retractions due to FFP. China stands out with the fastest retracting speed compared to other countries. Possible explanations, limitations, and policy implications are also discussed.

3.
Nano Lett ; 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32207976

RESUMO

The dimensionality of the crystal structure plays an important role in the electronic structures of materials. Ruddlesden-Popper perovskite oxides offer an attractive platform for studying this role due to dimensional flexibility. The effects of dimensionality on physical properties in those oxides have been widely reported. However, the study of dimensional dependence on the chemical properties is still lacking. Here, we synthesized a series of Ruddlesden-Popper perovskite nickelates LanSrNinO3n+1 (n = 1, 2, 3, and ∞) to explore the role of dimensionality on oxygen-evolution reaction (OER) performance. As the dimensionality increased with n, the nickelates exhibited an enhanced OER activity. We found that the weakening of electron correlations among Ni 3d electrons by increasing the dimensionality induced an insulator-to-metal transition and a strengthened Ni-O hybridization, both of which accelerated the OER kinetics. This work sets up a bridge between the dimensionality and electrocatalysis, which provides guidance for designing highly efficient oxygen-evolving catalysts.

4.
Sci Total Environ ; 722: 137756, 2020 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-32208242

RESUMO

Ammonia (NH3), as a dominant alkaline gas in the atmosphere, plays a vital role in Chinese urban haze formation process, but its source in urban areas of China is controversial. To identify the sources of urban NH3 in the semi-arid region of East Asia, real-time measurements of NH3 and NH4+ of PM2.5 in the urban atmosphere of Xi'an, inland China during the winter and summer of 2017 were performed and their stable nitrogen isotope composition were analyzed. NH3 was 38.0 ± 9.4 µg/m3 in the summer, which is 1.5 times higher than that in the winter. Concentration of NH3 in both seasons well correlated with that of PAHs in PM2.5 and the mass ratio of (BbF + BeP + IP + BghiP) to the total PAHs, suggesting that fossil fuel combustion is an important source of NH3 in Xi'an. Moreover, diurnal variation pattern of NH3 was consistent with that of CO in the summer, peaking in the morning and evening rush hours, respectively, further indicating an importance of the contribution of traffic emissions to NH3 in the city. Based on the source apportionment by using isotope mixing model, we found that 66.4% and 62.5% of NH3 in the urban atmosphere were contributed by non-agricultural sources in the summer and winter, respectively. Our work revealed that non-agricultural sources dominate the atmospheric NH3 of Xi'an, where haze pollution is still severe, and suggested that emission controls of non-agricultural NH3 could be an effective way to mitigate the air pollution problem in the semi-arid region of East Asia.

5.
Environ Pollut ; 256: 113401, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753639

RESUMO

This study reveals the impact of biomass burning (BB) on secondary organic aerosols (SOA) formation in the North China Plain (NCP). Filter samples were analyzed for secondary inorganic aerosols (SIA), oxalic acid (C2) and related aqueous-phase SOA compounds (aqSOA), stable carbon isotope composition of C2 (δ13C(C2)) and aerosol liquid water content (ALWC). Based on the PM2.5 loadings, BB tracer concentrations, wildfire spots and air-mass back trajectories, we distinguished two episodes from the whole campaign, Episode I and Episode II, which were characteristic of regional and local BB, respectively. The abundances of PM2.5 and organic matter in the two events were comparable, but concentrations and fractions of SIA, aqSOA during Episode I were much higher than those during Episode II, along with heavier δ13C(C2), suggesting an enhanced aqSOA formation in the earlier period. We found that the enhancement of aqSOA formation during Episode I was caused by an increased ALWC, which was mainly driven by SIA during the regional BB event. Our work showed that intensive burning of crop residue in East Asia can sharply enhance aqSOA production on a large scale, which may have a significant impact on the regional climate and human health.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Biomassa , Carbono/análise , Isótopos de Carbono/análise , China , Clima , Extremo Oriente , Compostos Orgânicos/análise , Material Particulado/análise , Estações do Ano , Água , Incêndios Florestais
6.
Nano Lett ; 19(12): 8774-8779, 2019 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-31675477

RESUMO

The obstacle for efficient electrochemical water splitting lies in the kinetically sluggish oxygen evolution reaction. Despite the various efforts that have been made to understand and tune the active sites for oxygen evolution reaction, an insight into the configurations of active sites from the electronic perspective is still lacking. Here, we report an atomic doping strategy to break the Oh symmetry of the CoO6 octahedron in LiCoO2. The specific activity of the La-doped LiCoO2 was 3.14 mA cm-2 at the overpotential of 0.35 V, which was 8.3 times higher than that of pristine LiCoO2. The overpotential with a value of 330 mV at 10 mA cm-2 was the lowest among the LiCoO2-based OER electrocatalysts ever reported. Mechanistic studies revealed that the superior activity originated from the asymmetric octahedral coordination of Co, resulting in the enhanced electronic conductivity and Co-O hybridization for the accelerated oxygen evolution kinetics. This work opens a door to enhance the catalytic performance through the manipulation of local symmetry.

7.
Inorg Chem ; 58(21): 14490-14497, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31600068

RESUMO

In this paper, we utilized the energy-transfer process between upconversion nanoparticles (UCNPs) and organic dye molecules to enhance the upconversion quantum yield (UCQY) of a UCNPs-dye system and tune the luminescence output color. The results indicate that adding an energy dissipation pathway to the energy donor through an energy-transfer process can decrease the ratio of nonradiative transition and cause a new radiative pathway. Through calculation of the rate equations, we studied the effects of the energy-transfer efficiency and activator type on the UCQY enhancement. On the basis of calculations of the CIE color coordinates, tunable color from Er3+, Tm3+, Ho3+, and Tb3+ ions was generated by surface decorating of an organic dye. The approach described here provides a new way to optimize the UCQY and manipulate the emission through energy transfer in a nanoscopic region.

8.
Opt Express ; 27(16): 22237-22245, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31510520

RESUMO

Berry phase can be used to generate quantum state which is robust to environmental noises in quantum information processing. Recently, the relationship between Berry phase and quantum phase transition attracts great attention in the research about topological states of matter. Here, we investigate the behavior of Berry phase in an anti parity-time symmetric system consisting of a metal nanoparticle and semiconductor quantum dot. The change of Berry phase undergoes a sudden death around exceptional point, i.e., Berry phase keeps unchanged in symmetry unbroken region, while it can be well adjusted through changing the strength and frequency of input light in symmetry broken region. The result demonstrated in this paper may be of significant importance in quantum computation and topological physics.

9.
Angew Chem Int Ed Engl ; 58(41): 14764-14769, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31452325

RESUMO

Developing bifunctional catalysts for both hydrogen and oxygen evolution reactions is a promising approach to the practical implementation of electrocatalytic water splitting. However, most of the reported bifunctional catalysts are only applicable to alkaline electrolyzer, although a few are effective in acidic or neutral media that appeals more to industrial applications. Here, a lithium-intercalated iridium diselenide (Li-IrSe2 ) is developed that outperformed other reported catalysts toward overall water splitting in both acidic and neutral environments. Li intercalation activated the inert pristine IrSe2 via bringing high porosities and abundant Se vacancies for efficient hydrogen and oxygen evolution reactions. When Li-IrSe2 was assembled into two-electrode electrolyzers for overall water splitting, the cell voltages at 10 mA cm-2 were 1.44 and 1.50 V under pH 0 and 7, respectively, being record-low values in both conditions.

10.
Inorg Chem ; 58(14): 9351-9357, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31246450

RESUMO

We designed and synthesized NaYF4:Yb,Tm@LiLuF4:Nd core-shell nanoparticles, which can emit at ∼800 nm under 980 nm excitation and at ∼1060 nm under 808 nm excitation, simultaneously having an upconversion and downshifting mechanism for near-infrared (NIR) emission. After surface modification with sodium citrate, the soluble nanoparticles were used in the in vitro NIR luminescence imaging to compare the penetration depth and the scattering of tissue. Furthermore, to determine the differences between the upconversion and downshifting fluorescence for biological imaging, the soluble nanoparticles also were operated on the aforementioned two modes for in vivo imaging.


Assuntos
Diagnóstico por Imagem/métodos , Elementos da Série dos Lantanídeos/química , Nanopartículas Metálicas/química , Animais , Luminescência , Camundongos , Espectroscopia de Luz Próxima ao Infravermelho
11.
Org Lett ; 21(14): 5514-5518, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31251635

RESUMO

An organocatalytic asymmetric arylmethylation/N-hemiacetalization of 2-indolyl methane derivatives and 2-enals was developed. Notably, the 2-methyl of indole was readily deprotonated to produce highly reactive nucleophilic species by introducing the nitro group at the C3 position of the indole ring. A spectrum of valuable chiral dihydropyrido[1,2-a]indoles were efficiently constructed with excellent enantioselectivity (up to >99% ee). Furthermore, the corresponding products could be easily functionalized via simple deprotonation and treatment with other electrophiles with excellent diastereoselectivities (>20:1 dr).

12.
ACS Appl Mater Interfaces ; 11(17): 15298-15305, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30977992

RESUMO

The difficulty of near-infrared (NIR) ratiometric detection imaging lies in the lack of high-efficiency NIR probes and the overlapping interference between two emission peaks. To achieve more accurate detection in living organisms, dual NIR-emissive luminescent nanoprobes were designed under the same excitation at 808 nm. The Er3+ ion-doped nanoparticles were employed as a reference with their fluorescence emission at 1525 nm. Meanwhile, a cyanine dye molecule (Cy925) was combined on the surface of nanoparticles as the ClO- recognition site with its NIR emission at 925 nm. The ratiometric nanoprobe relied on the ratio of aforementioned two separated NIR peaks ( I925nm/ I1525nm), featuring deeper imaging penetration depth and low autofluorescence. This nanoprobe was verified to be sensitive and highly selective to ClO- through photoluminescence titration. The in vitro detection experiment developed reasonable work curves, guaranteeing that we can detect the change in concentration of ClO- in mice limbs with arthritis through in vivo imaging experiments.


Assuntos
Corantes Fluorescentes/química , Ácido Hipocloroso/análise , Nanopartículas/química , Animais , Articulação do Tornozelo/diagnóstico por imagem , Artrite/induzido quimicamente , Artrite/diagnóstico por imagem , Carbocianinas/química , Extremidades/diagnóstico por imagem , Feminino , Fluoretos/química , Ácido Hipocloroso/química , Camundongos , Camundongos Endogâmicos BALB C , Espectroscopia de Luz Próxima ao Infravermelho , Ítrio/química
13.
Inorg Chem ; 58(6): 3916-3924, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-30816702

RESUMO

The development of bimetallic transition-metal sulfide and nitrogen-doped carbon composites with unique hollow structure is highly desirable for energy storage applications but is also challenging. In the present work, we demonstrate a facile metal-organic framework engaged strategy for synthesizing bimetallic nickel cobalt sulfide and nitrogen-doped carbon composites with hollow spherical structure (denoted as hollow Ni-Co-S- n/NC composites) and a Ni/Co molar ratio ( n value) that can be easily controlled. When evaluated as electrode materials for both supercapacitors and lithium ion batteries, it is found that the hollow Ni-Co-S-0.5/NC composite with a Ni/Co molar ratio of 0.5 exhibits optimal electrochemical performance. The hollow Ni-Co-S-0.5/NC composite exhibits a high specific capacity of 543.9 C g-1 at 1 A g-1 and maintains a capacity retention of 67.3% when the current density is increased to 20 A g-1. An asymmetric supercapacitor based on the hollow Ni-Co-S-0.5/NC composite is fabricated, which shows good electrochemical performance with a high energy density of 39.6 W h kg-1 at a power density of 808 W kg-1. For lithium storage, the hollow Ni-Co-S-0.5/NC composite manifests a high reversible discharge capacity of 755.0 mA h g-1 at 200 mA g-1 for 200 cycles as well as good rate capability. The excellent electrochemical performance could be attributed to the desirable structural, compositional, and component advantages. This work could offer new insight into the rational design and synthesis of highly efficient electrode materials for both supercapacitors and lithium ion batteries.

14.
J Youth Adolesc ; 48(4): 655-667, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30830534

RESUMO

To date, several gene-by-environment (G×E) meta-analyses have been conducted to provide cumulative G×E evidence from previous inconsistent empirical studies; however, these meta-analyses have mainly focused on the serotonin transporter gene (5-HTTLPR). The present study aimed to conduct the first meta-analysis that tested whether and how an important dopaminergic gene-the catechol-O-methyltransferase (COMT) gene contributed to differences in child and adolescent environmental sensitivity. A total of 22 studies with 20,528 participants involving in various developmental outcomes (e.g., externalizing problems, emotional problems, cognitive development and social behaviors) met the inclusion criteria. The pooled effect size of environment-outcome associations in the Met-allele carriers (r = 0.11, 95% CI = [0.07, 0.15], p < .001) did not significantly differ from that in the Val/Val homozygotes (r = 0.14, 95% CI = [0.08, 0.20], p < 0.001) (Qcontrast (1) = 0.37, p = 0.54). The aggregated Liptak-Stouffer Z-score that combined the p-values of the COMT-environment interaction yield a nonsignificant result (p = 0.52). Moreover, outcome domain, sample age, ethnicity and assessment methods for the environment and the outcome did not moderate the effect sizes. Thus far, the COMT Val158Met polymorphism fails to explain the differences in sensitivity to environment. Future studies might incorporate more factors, such as polygenic effects of genetic pathways, epigenetics (EpiG) processing and sexual dimorphism, into the COMT-environment interaction equation.


Assuntos
Catecol O-Metiltransferase/genética , Interação Gene-Ambiente , Adolescente , Alelos , Criança , Comportamento Infantil , Desenvolvimento Infantil , Cognição , Feminino , Genótipo , Humanos , Masculino , Polimorfismo Genético
15.
JCI Insight ; 4(4)2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30668548

RESUMO

Abnormal activation of neddylation modification and dysregulated energy metabolism are frequently seen in many types of cancer cells. Whether and how neddylation modification affects cellular metabolism remains largely unknown. Here, we showed that MLN4924, a small-molecule inhibitor of neddylation modification, induces mitochondrial fission-to-fusion conversion in breast cancer cells via inhibiting ubiquitylation and degradation of fusion-promoting protein mitofusin 1 (MFN1) by SCFß-TrCP E3 ligase and blocking the mitochondrial translocation of fusion-inhibiting protein DRP1. Importantly, MLN4924-induced mitochondrial fusion is independent of cell cycle progression, but confers cellular survival. Mass-spectrometry-based metabolic profiling and mitochondrial functional assays reveal that MLN4924 inhibits the TCA cycle but promotes mitochondrial OXPHOS. MLN4924 also increases glycolysis by activating PKM2 via promoting its tetramerization. Biologically, MLN4924 coupled with the OXPHOS inhibitor metformin, or the glycolysis inhibitor shikonin, significantly inhibits cancer cell growth both in vitro and in vivo. Together, our study links neddylation modification and energy metabolism, and provides sound strategies for effective combined cancer therapies.

16.
Nanoscale ; 11(6): 2959-2965, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30693936

RESUMO

Ratiometric fluorescent sensors, which can provide a built-in correction for environmental effects, have attracted significant attention for analytical sensing and optical imaging with the potential to provide a precise and quantitative analysis. Herein, we report a strategy based on dye-sensitized upconversion for the design of dual-excitation upconverion ratiometric probes possessing same emission peaks under a large separation in the excitation spectra (980 nm and 808 nm). Specifically, effective enhancement of upconversion luminescence could be attributed to Cy787 dyes present on the surface of nanoparticles, and it subsequently decreased upon the addition of ClO- under an 808 nm irradiation, whereas the signal under 980 nm excitation remained essentially constant, thus allowing for quantitative ratiometric monitoring of ClO-. The rationally designed dye-sensitized upconverion nanosystem exhibits excellent sensitivity for ClO- with a quantification limit of 3.6 nM in aqueous solutions. We have also demonstrated that the designed nanoprobe is a promising material for semi-quantitative detection of ClO- in an arthritis mouse model.


Assuntos
Corantes Fluorescentes/metabolismo , Ácido Hipocloroso/análise , Nanocompostos/química , Nanotecnologia/métodos , Imagem Óptica/métodos , Animais , Artrite Experimental/diagnóstico por imagem , Camundongos
17.
J Hazard Mater ; 367: 348-355, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30599407

RESUMO

The emerging ionic porous organic materials have achieved various applications in different fields, however, there is limited study on using them to capture ionic pollutants from water. Here we demonstrate a facile method to prepare a cationic porous organic polymer via catalyst-free Schiff base reaction. The imidazolium-based polymer (ImPOP-1) was constructed through copolymerizing cationic molecules with low-cost benzidine. The as-prepared ImPOP-1 exhibits high capacity (e.g., 476.2 mg g-1 for Pd (II) and 578.5 mg g-1 for AO7-), excellent selectivity (e.g., more than 99% removal efficiency for Pd (II) in the presence of 100 times excess of SO42-), and fast kinetics (e.g., 98.6% removal efficiency within 5 min for Pd (II) ions) to the anionic pollutants including organic dyes and heavy metal ions. The excellent performance on scavenging anionic pollutants from water suggests that ImPOP-1 holds promising potential as an ion exchange material for water remediation.

18.
Biotechnol J ; 14(1): e1800195, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29799175

RESUMO

Patient X: A 67-year-old Caucasian man slips on a patch of ice. He has abrasions to his hands and has sustained significant damage to his hip. At the emergency room, he informs clinicians he takes atorvastatin, metformin, and glimepiride to treat hypertension and Type 2 Diabetes Mellitus (T2DM). X-rays reveal a fractured hip, which will require total hip replacement surgery.


Assuntos
Biotecnologia/métodos , Saúde Pública , Edição de Genes , Humanos , Medicina de Precisão , Engenharia Tecidual
19.
Anticancer Drugs ; 30(2): 128-137, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30335624

RESUMO

Physalin B (PB) is one of the major constituents of Physalis alkekengi var. franchetii, a well-known Chinese traditional herb. In this study, we demonstrated for the first time that PB exhibits significant antiproliferative and apoptotic activity in A549 human lung cancer cells in a concentration-dependent and time-dependent manner. Flow cytometric analyses indicated that PB-induced G2/M arrest through down-regulation of cyclin B1 and cell division control protein cyclin-dependent kinase 1, and up-regulation of p21. The reduction in the level of cyclin B1/cyclin-dependent kinase 1 complex down-regulated oxidative phosphorylation multisubunit activity to reduce mitochondrial energetic homeostasis. Moreover, defects in mitochondrial ATP synthesis and mitochondrial membrane potential were found in PB-treated cell lines. These abnormalities led to an increase in intracellular superoxide and apoptosis. Thus, as an inhibitor of mitochondrial energetic homeostasis, PB demonstrates potent antitumor activities and may be developed as an alternative therapeutic agent against non-small-cell lung cancer.

20.
Chemosphere ; 215: 413-421, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30336318

RESUMO

TSP and 9-stage size-segregated samples were simultaneously collected in Xi'an during the spring of 2013 and analyzed for organic aerosols (OA) on a molecular level. n-Alkanes were the dominant compound class during the whole campaign, followed by fatty acids. High molecular weight (HMW) n-alkanes and fatty acids dominated in the coarse mode particles (>1.1 µm) during the dust event, indicating they were mostly originated from surface soil and plants in the upwind regions. Low-volatile anthropogenic compounds such as benzo(e)pyrene (BeP) and bisphenol A (BPA) dominated in the fine mode particles during the whole campaign. In contrast, semi-volatile anthropogenic compounds such as phenanthrene (Phe) and di-n-butyl phthalates (DBP) showed a bimodal size distribution with a significant increase in the coarse mode during the dust event due to their vaporization from the fine mode particles and the subsequent adsorption on the dust surface. Secondary organic aerosols (SOA) in Xi'an during the dust storm period were predominantly enriched on the coarse particles, which can be ascribed to the adsorption and subsequent oxidation of gas-phase hydrophilic organics on the aqueous-phase of hygroscopic dust surface (e.g., mirabilite). Our work suggested an important role of multiphase reaction in evolution of aerosol chemistry during the dust long-range transport process.


Assuntos
Aerossóis/química , Poluentes Atmosféricos/análise , Poeira/análise , Monitoramento Ambiental/métodos , Estações do Ano , Aerossóis/análise , Poluentes Atmosféricos/química , Alcanos/análise , Alcanos/química , China , Ácidos Graxos/análise , Ácidos Graxos/química , Compostos Orgânicos/química , Tamanho da Partícula , Volatilização
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