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1.
Sci Total Environ ; 723: 138020, 2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32217386

RESUMO

Estimating gross primary production and ecosystem respiration from oxygen data is performed widely in aquatic systems, yet these estimates can be challenged by high advective fluxes of oxygen. In this study, we develop a hybrid framework linking data-driven and process-based modelling to examine the effect of storm events on oxygen budgets in a constructed wetland. After calibration against measured flow and water temperature data over a two-month period with three storm events, the model was successfully validated against high frequency dissolved oxygen (DO) data exhibiting large diurnal fluctuations. The results demonstrated that pulses of high-DO water injected into the wetland during storm events were able to dramatically change the wetland oxygen budget. A shift was observed in the dominant oxygen inputs, from benthic net production during non-storm periods, to inflows of oxygen during storm events, which served to dampen the classical diurnal oxygen signature. The model also demonstrated the changing balance of pelagic versus benthic production and hypoxia extent in response to storm events, which has implications for the nutrient attenuation performance of constructed wetlands. The study highlights the benefit of linking analysis of high-frequency oxygen data with process-based modelling tools to unravel the varied responses of components of the oxygen budget to storm events.

2.
Glob Chang Biol ; 2020 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-32125754

RESUMO

Understanding changes in terrestrial carbon balance is important to improve our knowledge of the regional carbon cycle and climate change. However, evaluating regional changes in the terrestrial carbon balance is challenging due to the lack of surface flux measurements. This study reveals that the terrestrial carbon uptake over the Republic of Korea has been enhanced from 1999 to 2017 by analyzing long-term atmospheric CO2 concentration measurements at Anmyeondo Station (36.53°N, 126.32°E) located in the western coast. The influence of terrestrial carbon flux on atmospheric CO2 concentrations (ΔCO2 ) is estimated from the difference of CO2 concentrations that were influenced by the land sector (through easterly winds) and the Yellow Sea sector (through westerly winds). We find a significant trend in ΔCO2 of -4.75 ppmv decade-1 (p < 0.05) during the vegetation growing season (May through October), suggesting that the regional terrestrial carbon uptake has increased relative to the surrounding ocean areas. Combined analysis with satellite measured normalized difference vegetation index and gross primary production shows that the enhanced carbon uptake is associated with significant nationwide increases in vegetation and its production. Process-based terrestrial model and inverse model simulations estimate that regional terrestrial carbon uptake increases by up to 9.9 and 4.2 Tg C decade-1 , accounting for 13.4 and 5.7% of annual domestic carbon emissions averaged for the study period, respectively. Atmospheric chemical transport model simulations indicate that the enhanced terrestrial carbon sink is the primary reason for the observed ΔCO2 trend rather than anthropogenic emissions and atmospheric circulation changes. Our results highlight the fact that atmospheric CO2 measurements could open up the possibility of detecting regional changes in the terrestrial carbon cycle even where anthropogenic emissions are not negligible.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32160604

RESUMO

The temperature coefficient of Raman shift, which regulates the linear-in-temperature dependence of Raman shift, plays a vital role in the experimental determinations of thermal conductivities in two-dimensional (2D) materials. Originating from nonlinear phonon effects, however, its connections to the underlying phonon structure remain poorly understood. Here, we explore the possibility of a simple albeit general relation that relates temperature coefficients to frequencies of the associated phonon modes in 2D materials. Remarkably, by resorting to a renormalized phonon picture, we explicitly show that the ratio between the temperature coefficient of Raman shift and the associated phonon frequency is almost a constant that is varied only between materials. Our general relation fits well to experimental results for typical 2D materials and may have implications for addressing the impact of nonlinear phonon effects on thermal conductivities in 2D materials.

4.
Artigo em Inglês | MEDLINE | ID: mdl-32056126

RESUMO

PURPOSE: Cerebrovascular aneurysms are being observed with rapidly increasing incidence. Therefore, tools are needed for accurate and efficient detection of aneurysms. We used deep learning techniques with CT angiography acquired from multiple medical centers and different machines to develop and evaluate an automatic detection model. METHODS: In this study, we have introduced a deep learning model, the faster RCNN model, in order to develop a tool for automatic detection of aneurysms from medical images. The inputs of the model were 2D nearby projection (NP) images from 3D CTA, which were made by the NP method proposed in this study. This method made aneurysms clearly visible on images and improved the model's performance. The study included 311 patients with 352 aneurysms, selected from three hospitals, and 208 and 103 of these patients, respectively, were randomly selected to train and test the models. RESULTS: The sensitivity of the trained model was 91.8%. For aneurysm sizes larger than 3 mm, the sensitivity of successful aneurysm detection was 96.7%. We achieved state-of-the-art sensitivity for > 3 mm aneurysms. The sensitivities also indicated that there was no significant difference among aneurysms at different locations in the body. Computing time for the detection process was less than 25 s per case. CONCLUSIONS: We successfully developed a deep learning model that can automatically detect aneurysms. The model performed well for aneurysms of different sizes or in different locations. This finding indicates that the deep learning model has the potential to vastly improve clinician performance by providing automated aneurysm detection.

5.
Nat Plants ; 6(2): 131-142, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32055045

RESUMO

Self-incompatibility (SI) is an important mechanism that prevents self-fertilization and inbreeding in flowering plants. The most widespread SI system utilizes S ribonucleases (S-RNases) and S-locus F-boxes (SLFs) as S determinants. In citrus, SI is ancestral, and Citrus maxima (pummelo) is self-incompatible, while Citrus reticulata (mandarin) and its hybrids are self-compatible (SC). Here, we identify nine highly polymorphic pistil-specific, developmentally expressed S-RNases from pummelo that segregate with S haplotypes in a gametophytic manner and cluster with authentic S-RNases. We provide evidence that these S-RNases function as the female S determinants in citrus. Moreover, we show that each S-RNase is linked to approximately nine SLFs. In an analysis of 117 citrus SLF and SFL-like (SLFL) genes, we reveal that they cluster into 12 types and that the S-RNases and intra-haplotypic SLF and SLFL genes co-evolved. Our data support the notion that citrus have a S locus comprising a S-RNase and several SLFs that fit the non-self-recognition model. We identify a predominant single nucleotide mutation, Sm-RNase, in SC citrus, which provides a 'natural' loss of function. We show that SI-SC transitions due to the Sm-RNase initially arose in mandarin, spreading to its hybrids and became fixed. Identification of an evolutionarily distant new genus utilizing the S-RNase-based SI system, >100 million years separated from the nearest S-RNase family, is a milestone for evolutionary comparative studies.

6.
Chem Commun (Camb) ; 56(12): 1811-1814, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31950951

RESUMO

We developed a label-free homogeneous photoelectrochemical biosensing strategy based on the synergy of G-quadruplex/hemin catalysed electron donor consumption and the inner filter effect for highly selective and sensitive microRNA assay.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Hemina/metabolismo , MicroRNAs/análise , Elétrons , Quadruplex G , Humanos , Processos Fotoquímicos
7.
Org Lett ; 22(3): 863-866, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31944776

RESUMO

A novel sp3 C-SCF3 coupling reaction between cycloketone oxime esters and S-trifluoromethyl 4-methylbenzenesulfonothioate was achieved. Ethanol was found to facilitate this transformation by trapping the sulfonyl cation. The metal-free and photocatalyst-free reaction conditions, as well as the broad substrate scope, make this a green protocol for the synthesis of SCF3-substituted nitriles.

8.
Nat Commun ; 11(1): 541, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992713

RESUMO

The fast development of high-resolution electron microscopy (EM) demands a background-noise-free substrate to support the specimens, where atomically thin graphene membranes can serve as an ideal candidate. Yet the preparation of robust and ultraclean graphene EM grids remains challenging. Here we present a polymer- and transfer-free direct-etching method for batch fabrication of robust ultraclean graphene grids through membrane tension modulation. Loading samples on such graphene grids enables the detection of single metal atoms and atomic-resolution imaging of the iron core of ferritin molecules at both room- and cryo-temperature. The same kind of hydrophilic graphene grid allows the formation of ultrathin vitrified ice layer embedded most protein particles at the graphene-water interface, which facilitates cryo-EM 3D reconstruction of archaea 20S proteasomes at a record high resolution of ~2.36 Å. Our results demonstrate the significant improvements in image quality using the graphene grids and expand the scope of EM imaging.


Assuntos
Grafite/química , Microscopia Eletrônica/instrumentação , Microscopia Eletrônica/métodos , Fenômenos Químicos , Microscopia Crioeletrônica/métodos , Elétrons , Desenho de Equipamento , Processamento de Imagem Assistida por Computador , Membranas , Polímeros , Proteínas
9.
J Hazard Mater ; 384: 121216, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31733995

RESUMO

Black soils (Mollisols) are important soil resources for crop production and maintain food safety in China. For keeping soil fertility, the application of animal manure is commonly practiced in black soils. However, the impact of this application on abundance and diversity of antibiotic resistance genes (ARGs) in black soils of China remains unclear. Here, we surveyed the profiles of ARGs in 72 soil samples collected from four long-term experimental stations with different fertilization regimes and from open farmlands in two sites across northeast China using high-throughput quantitative PCR. Results showed that a total of 178 ARGs including mobile genetic elements (MGEs) were detected, and the diversity and abundance of ARGs were significantly increased with manure application. Additionally, the finding of a significant positive correlation between relative abundance of ARGs and MGEs (P < 0.0001), suggesting that horizontal gene transfer may potentially impact the transmission of ARGs. Furthermore, two genes aadA-1-01 and mexF, encoding resistance to aminoglycoside and multidrug, respectively, were recognized as indicators to estimate the abundance of other co-occurring ARGs. These findings provided insights into the soil resistome in black soils of northeast China and also highlighted the environmental risks caused by manure application should not be ignored.

10.
Nano Lett ; 20(1): 780-789, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31830790

RESUMO

Either hypoxia in an acute ischemic stroke before thrombolysis or the oxygen-boost after thrombolysis cause a high level of free radicals, resulting in successive injuries to neurocytes. To treat an ischemic stroke, it is needed to scavenge free radicals, combining sequentially regulating hypoxia and oxygen-boost microenvironment. Here, we report an engineered nanosponge (Mn3O4@nanoerythrocyte-T7, MNET) that could remodel the microenvironment of a stroke by self-adapted oxygen regulating and free radical scavenging. With a long circulation time in blood due to the stealth effect of the erythrocyte and preferential accumulation in the infarct site by the assisting of T7 peptide, MNET exerts a distinct therapeutic effect in two stages of an ischemic stroke: (i) before thrombolysis, rescue neurocyte via rapid free radical scavenging and timely oxygen supply; (ii) after thrombolysis, suppress oxygen-boost via oxygen storage, as well as scavenge free radical to avoid reperfusion injury. MNET holds an attractive potential for ischemic stroke treatment via phased regulation of pathological microenvironment.

11.
Colloids Surf B Biointerfaces ; 186: 110700, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31821968

RESUMO

Recently, fullerene (C60) has been widely used as a nano photosensitizer (PS) for tumor related photodynamic therapy (PDT). However, current PDT based on C60 is severely restricted by the visible light source (shallow tissue penetrating depth) and oxygen dependent (tumor hypoxia). Therefore, taking advantages of the surface plasmon resonance (SPR) effect of gold nanoparticles (GNPs) and "electronic sponge" property of C60, a C60 based hybrid nanostructured photosensitizer (C60@GNPs) with high light stability, near infrared light (NIR) excitation, and oxygen non-dependent properties was rational designed according to the mechanism of PDT. Compared with C60, after GNPs in-situ synthesis, the PDT mechanism of C60@GNPs changed from type II to type I, and the main product of PDT changed from singlet oxygen to hydroxyl radicals. Furthermore, C60@GNPs hybrid could efficiently generate hydroxyl radicals under NIR light excitation even in the hypoxia condition. These results suggest that C60@GNPs hybrid has a great potential for in vivo PDT applications.

12.
Free Radic Biol Med ; 147: 90-101, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31838229

RESUMO

The involvement of reactive oxygen species (ROS) has been suggested in the development of inflammatory bowel disease (IBD). An impaired intestinal barrier function is common in IBD patients. Here, we report the central role of NOX1/NADPH oxidase, a major source of ROS in nonphagocytic cells, in intestinal barrier dysfunction. By in vivo imaging using L-012 as a probe, a time-dependent increase in ROS was demonstrated in the abdomen of wild-type mice (WT) administered lipopolysaccharide (LPS: 6 mg/kg i.p.), but it was almost completely abolished in mice deficient in Nox1 (Nox1-KO) or the inducible nitric oxide synthase gene (iNOS-KO). By ex vivo imaging, increased ROS production was mainly shown in the ileum, where enhanced immunostaining of NOX1 was observed on the apical side of the epithelium. On the other hand, a punctate staining pattern of 3-nitrotyrosine, a marker of peroxynitrite production, was demonstrated in the lamina propria. When LPS-induced intestinal hyperpermeability was assessed by the oral administration of fluorescein isothiocyanate-conjugated dextran (FD-4), it was significantly suppressed in Nox1-KO as well as iNOS-KO. When Nox1-KO adoptively transferred with WT bone marrow were treated with LPS, the serum level of FD-4 was significantly elevated, whereas it remained unchanged in WT receiving bone marrow derived from Nox1-KO. Concomitantly, the activation of matrix metalloproteinase-9 induced by LPS was alleviated not only in intestinal tissue but also in peritoneal macrophages of Nox1-KO. Up-regulation of iNOS by LPS was significantly inhibited in macrophages deficient in Nox1, illustrating a functional hierarchy in NOX1/iNOS signaling. Together, these findings suggest that NOX1 in bone marrow-derived cells, but not epithelial cells, perturbs intestinal barrier integrity during endotoxemia.

13.
Sci Total Environ ; 698: 134137, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31493575

RESUMO

This study conducted on-site measurements of indoor volatile organic compounds (VOCs) in 251 occupied residences in China, with multiple visits throughout a whole year. Over 1000 samples were collected for measurement of VOCs in 8 cities, covering different climate regions. Overall, the concentrations of total VOCs (TVOCs) in occupied residences are in the range of 104-1151 µg/m3, with 20% of the samples over the Chinese standard of 600 µg/m3. A higher concentration was evident in the summer (mean = 705 µg/m3) compared to other seasons, especially winter (mean = 289 µg/m3). The TVOCs of residences in areas with central heating (severe cold regions and cold regions) are generally higher than those in areas without central heating. In winter, temperature was the dominant factor, whereas in summer, the building infiltration rate was the key factor influencing the indoor TVOC levels. The TVOCs concentration was also found to be directly proportional to the city economy level. Twenty-nine VOC species with a detection frequency higher than 40% were identified in all samples. Toluene is the most common VOC, with the highest detection rate (90%). The median concentration for a single VOC was between 1 and 14 µg/m3. Aldehydes were found to be the largest contributors to total VOCs in the Chinese residential buildings (mass proportion 22%), followed by benzene series (20%), alkenes (18%), and alkanes (15%). Aldehydes, especially long-chain saturated carbonyls, are likely to be the characteristic VOCs in the Chinese dwellings, with Chinese cooking as the major emission source. In addition, n-butane/i-butane showed maximum concentration in some residences (approximately 105 µg/m3 higher than other VOCs) owing to cooking fuel.


Assuntos
Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Monitoramento Ambiental , Compostos Orgânicos Voláteis/análise , Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , China , Cidades , Habitação , Estações do Ano
14.
Methods Mol Biol ; 2062: 401-415, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31768987

RESUMO

The RNA exosome is a multisubunit complex typically composed of a catalytically inactive core and the Rrp44 protein, which contains 3'-to-5' exo- and endo-RNase activities. With assistance from nuclear or cytoplasmic cofactors, functional studies implicated the exosome as a critical player in the turnover of almost all RNA species, including mRNAs, rRNA, tRNAs, and other noncoding RNAs. Here, we describe the purification of the yeast 10-subunit exosome and 11-subunit Exosome-Ski7, as well as subsequent sample screening by negative staining EM and structural analysis by cryo-EM.

15.
J Control Release ; 318: 136-144, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31862357

RESUMO

Embolization therapy is an attractive strategy for antitumor therapy, especially for solid tumors. In vivo self-coagulation behavior holds great potential in a new type of tumor embolization therapy. However, spatiotemporal controllable in situ formation of thrombus in tumor is a challenge. Herein, an ultrasound (US)-responsive ultra-sensitive "thrombus constructor" (UUNC), which was prepared by loading thrombin into a nanobubble, and modified with NGR peptide on its surface, is rational designed for tumor embolization therapy. Benefiting from the targeting ability of NGR peptides to tumor neovascularization, UUNC efficiently enriched in tumor vessels, and then released thrombin rapidly to form thrombi in situ of tumor blood vessels in the presence of US. In vivo antitumor experiments demonstrated that UUNC could significantly lead to tumor cell apoptosis and necrosis, and the tumor growth inhibition rate (TGI) was 85.3% with a transient US in tumor, while maintain high stability, and no obvious thrombus was observed in normal tissues. UUNC holds an attractive potential for tumor embolization therapy via spatiotemporal controllable thrombus construct strategy.

16.
Analyst ; 145(3): 873-879, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31845932

RESUMO

In this work, an Au-Ag alloy nanourchin (Au-Ag alloy NU) based electrochemiluminescent (ECL) sensor for the measurement of cardiac troponin I (cTnI) was developed. The as-prepared Au-Ag alloy NUs exhibited higher specific surface area and better conductivity owing to their unique urchin-like morphology, which resulted in excellent electrocatalytic activity towards H2O2 in the luminol-H2O2 ECL system. We have found that the Au-Ag alloy NUs could enhance the ECL signal in the luminol-H2O2 solution. Based on these facts, a facile and label-free ECL immunosensor has been constructed for the analysis of cTnI, a cardiac biomarker, with a wide linear range of 3.5 pg mL-1-350 µg mL-1. This novel ECL immunosensor has good stability and reproducibility, showing potential application in clinical diagnostics. In addition, a non-enzymatic electrochemical sensor for H2O2 was also fabricated, with a wide linear detection range of 100 nM-200 µM, a low limit of detection of 45 nM and a fast response time (less than 2 s).

17.
Adv Healthc Mater ; 9(3): e1901316, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31858730

RESUMO

To enhance the tumor-targeting and tumor cell-specific drug-release capacity of nano drug delivery systems, a magnetic resonance imaging-traceable, magnetic-targeted nanoplatform is developed, and the nanoplatform is prepared by capping mesoporous silica (MSN)-coated iron oxide nanoparticles (IONPs) with programmable DNA hairpin sensor "gates." In normal cells (HL-7702, human liver cells), the nanoplatform is able to entrap the loaded drugs, showing an "OFF" state; the nanoplatform is activated by endogenous miRNA-21 overexpressed in tumor cells (HepG2, human liver tumor cells), which serve as an exclusive key to unlock the nanoplatform through hybridization with programmable DNA hairpin, leading to a rapid drug release, showing an "ON" state. The nanoplatform exhibits high antitumor efficacy and low toxicity in in vitro and in vivo studies owing to its magnetic targeting and tumor cell-activated properties, paving the way for targeted and personalized tumor treatment and showing potential for clinical applications.

18.
Methods Mol Biol ; 2103: 189-198, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31879926

RESUMO

Branched peptide as an attractive mimic of natural peptide is widely used in structural design of functional or therapeutic peptides, to improve their biological activity, stability, and pharmacokinetic properties. In this protocol, we employ a function group of side-chain benzyl ester as the precursor of hydrazide, which could be conveniently used to assemble a branch peptide by native chemical ligation or direct amidation. This method is convergent and efficient, and facilitates the synthesis and application of branched peptides.

19.
J Nanobiotechnology ; 17(1): 117, 2019 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-31783863

RESUMO

BACKGROUND: Cancer cells always develop ways to resist and evade chemotherapy. To overcome this obstacle, herein, we introduce a programmatic release drug delivery system that imparts avoiding drug efflux and nuclear transport in synchrony via a simple nanostructured drug strategy. RESULTS: The programmatic liposome-based nanostructured drugs (LNSD) contained two modules: doxorubicin (DOX) loaded into tetrahedral DNA (TD, ~ 10 nm) to form small nanostructured DOX, and the nanostructured DOX was encapsulated into the pH-sensitive liposomes. In the in vitro and in vivo studies, LNSD shows multiple benefits for drug resistance tumor treatment: (1) not only enhanced the cellular DOX uptake, but also maintained DOX concentration in an optimum level in resistant tumor cells via nanostructure induced anti-efflux effect; (2) small nanostructured DOX efficiently entered into cell nuclear via size depended nuclear-transport for enhanced treatment; (3) improved the pharmacokinetics and biodistribution via reducing DOX leakage during circulation. CONCLUSIONS: The system developed in this study has the potential to provide new therapies for drug-resistant tumor.

20.
Sci Rep ; 9(1): 17928, 2019 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-31784625

RESUMO

Hand-foot-mouth disease (HFMD) is a common infectious disease in children and is particularly severe in Guangxi, China. Meteorological conditions are known to play a pivotal role in the HFMD. Previous studies have reported numerous models to predict the incidence of HFMD. In this study, we proposed a new method for the HFMD prediction using GeoDetector and a Long Short-Term Memory neural network (LSTM). The daily meteorological factors and HFMD records in Guangxi during 2014-2015 were adopted. First, potential risk factors for the occurrence of HFMD were identified based on the GeoDetector. Then, region-specific prediction models were developed in 14 administrative regions of Guangxi, China using an optimized three-layer LSTM model. Prediction results (the R-square ranges from 0.39 to 0.71) showed that the model proposed in this study had a good performance in HFMD predictions. This model could provide support for the prevention and control of HFMD. Moreover, this model could also be extended to the time series prediction of other infectious diseases.

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