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1.
Sensors (Basel) ; 21(4)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670623

RESUMO

Human activity detection plays an important role in social security monitoring. Since human activity is very weak, it is necessary to employ the repeat-pass Interferometric Synthetic Aperture Radar (InSAR) technique to detect the potential activity between two data acquisitions; a high level of coherence is required for detection. With the object of detecting human activity of interest, this paper presents a coherence improvement approach based on sub-aperture InSAR for human activity detection. Different sub-apertures contain different scattering information of the target, as they represent the backscatter of the target from a different range of angles. Integrating corresponding sub-aperture interferometric results can improve the coherence between two complex images compared to the entire synthetic aperture, as well as removing a little disturbance in some circumstances. To validate the method presented in this paper, the actual airborne Ka-band frequency modulated continuous wave (FMCW) InSAR data acquired by the Aerospace Information Research Institute, Chinese Academy of Sciences (AIRCAS) are utilized. The experimental results demonstrate that the proposed method can effectively improve the coherence between two complex SAR images and can validly detect human activity of interest.


Assuntos
Atividades Humanas , Interferometria , Radar , Humanos
2.
Sensors (Basel) ; 21(4)2021 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-33672621

RESUMO

A generalized likelihood ratio test (GLRT) with the constant false alarm rate (CFAR) property was recently developed for adaptive detection of moving targets in focusing synthetic aperture radar (SAR) images. However, in the multichannel SAR-ground moving-target indication (SAR-GMTI) system, image defocus is inevitable, which will remarkably degrade the performance of the GLRT detector, especially for the lower radar cross-section (RCS) and slower radial velocity moving targets. To address this issue, based on the generalized steering vector (GSV), an extended GLRT detector is proposed and its performance is evaluated by the optimum likelihood ratio test (LRT) in the Neyman-Pearson (NP) criterion. The joint data vector formulated by the current cell and its adjacent cells is used to obtain the GSV, and then the extended GLRT is derived, which coherently integrates signal and accomplishes moving-target detection and parameter estimation. Theoretical analysis and simulated SAR data demonstrate the effectiveness and robustness of the proposed detector in the defocusing SAR images.

3.
EMBO Rep ; 22(2): e50967, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33372411

RESUMO

Lysine succinylation (Ksucc) is an evolutionarily conserved and widespread post-translational modification. Histone acetyltransferase 1 (HAT1) is a type B histone acetyltransferase, regulating the acetylation of both histone and non-histone proteins. However, the role of HAT1 in succinylation modulation remains unclear. Here, we employ a quantitative proteomics approach to study succinylation in HepG2 cancer cells and find that HAT1 modulates lysine succinylation on various proteins including histones and non-histones. HAT1 succinylates histone H3 on K122, contributing to epigenetic regulation and gene expression in cancer cells. Moreover, HAT1 catalyzes the succinylation of PGAM1 on K99, resulting in its increased enzymatic activity and the stimulation of glycolytic flux in cancer cells. Clinically, HAT1 is significantly elevated in liver cancer, pancreatic cancer, and cholangiocarcinoma tissues. Functionally, HAT1 succinyltransferase activity and the succinylation of PGAM1 by HAT1 play critical roles in promoting tumor progression in vitro and in vivo. Thus, we conclude that HAT1 is a succinyltransferase for histones and non-histones in tumorigenesis.

4.
BMC Public Health ; 20(1): 1687, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33172411

RESUMO

BACKGROUND: On the basis of the integration constructs from self-determination theory (SDT) and achievement goal theory (AGT), this study aims to investigate the relationship among classroom motivational climate from four perspectives (i.e. autonomy support, relatedness support, task-involving climate and ego-involving climate), three psychological needs (i.e. autonomy, competence and relatedness), self-determined motivation and physical activity (PA) in secondary physical education (PE). METHODS: Participants consisted of 1186 Chinese students aged 11 to 16 years from three secondary schools in Shanghai. Accelerometers were utilized to measure moderate to vigorous physical activity (MVPA). Questionnaires were used to measure SDT variables (i.e. classroom motivational climate, perceived competence, autonomy, relatedness and self-determined motivation). Structural equation modelling (SEM) was adopted to analyse the hypothesised relationship. RESULTS: SEM analysis revealed that task-involving climate and autonomy support were positively associated with autonomy, relatedness and competence. Relatedness support was positively related with autonomy and relatedness, whereas ego-involving climate was only associated with competence. The three psychological needs positively affected self-determined motivation, and self-determined motivation positively affected the MVPA time of secondary school students in PE lessons. CONCLUSION: These findings support a model of motivation that integrates SDT and AGT, provides new insight into understanding MVPA in Chinese PE, and establishes a solid basis for intervention research.

5.
Sensors (Basel) ; 20(5)2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32143515

RESUMO

A digital elevation model (DEM) can be obtained by removing ground objects, such as buildings, in a digital surface model (DSM) generated by the interferometric synthetic aperture radar (InSAR) system. However, the imaging mechanism will cause unreliable DSM areas such as layover and shadow in the building areas, which seriously affect the elevation accuracy of the DEM generated from the DSM. Driven by above problem, this paper proposed a novel DEM reconstruction method. Coherent Markov random field (CMRF) was first used to segment unreliable DSM areas. With the help of coherence coefficients and residue information provided by the InSAR system, CMRF has shown better segmentation results than traditional traditional Markov random field (MRF) which only use fixed parameters to determine the neighborhood energy. Based on segmentation results, the hierarchical adaptive surface fitting (with gradually changing the grid size and adaptive threshold) was set up to locate the non-ground points. The adaptive surface fitting was superior to the surface fitting-based method with fixed grid size and threshold of height differences. Finally, interpolation based on an inverse distance weighted (IDW) algorithm combining coherence coefficient was performed to reconstruct a DEM. The airborne InSAR data from the Institute of Electronics, Chinese Academy of Sciences has been researched, and the experimental results show that our method can filter out buildings and identify natural terrain effectively while retaining most of the terrain features.

6.
J Colloid Interface Sci ; 588: 184-195, 2020 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-33387820

RESUMO

For the design of electrocatalysts, the combination between components and the regulation of material structures tend to be neglected, giving rise to the constraint of catalytic performance and durability. Herein, we developed a graphene oxide quantum dots (GOQDs) with enhanced oxygen content by a one-step cutting method. Then, one-dimensional (1D) carbon nanotubes and two-dimensional (2D) reduced graphene oxide are crosslinked and self-assembled, thus attracting unsaturated-bond-riches GOODs (0D) to uniformly attach to the skeleton, simultaneously achieving nitrogen and sulfur co-doping. To the best of our knowledge, there is no report to prepare bifunctional electrocatalyst with GOQDs. Electrochemical tests show that even without metal-doping, the novel non-metal bifunctional electrocatalyst (N,S-GOQD-RGO/CNT) exhibits a higher half-wave potential (0.84 V) and enhanced limiting current density (5.88 mA cm-2) than commercial Pt/C catalyst. The density functional theory is implemented to reveal the coordination of nitrogen and sulfur co-doping on GOQDs, which results in the improvement of overall catalytic active sites. Furthermore, the rechargeable zinc-air battery based on N,S-GOQD-RGO/CNT exhibits a maximum power density of 134.3 mW cm-2, open circuit potential of 1.414 V, which is better than Pt/C+Ru/C mixed material. The obtained N,S-GOQD-RGO/CNT will provide a perspective application in fuel cells.

7.
Appl Opt ; 58(18): 4884-4891, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31503804

RESUMO

The azimuth multi-channel synthetic aperture ladar (SAL), which arranges multiple telescopes along the flight direction of the platform, transmits signals through a single telescope and receives echoes by multiple telescopes simultaneously to obtain data. The aperture synthesis technology, which has the ability to achieve high resolution through multiple small telescopes, is applied to the multi-channel SAL system to realize the reconstruction of the complete azimuth Doppler spectrum in a short observation time. However, there are gaps inevitably between telescopes, which degrade the results of aperture synthesis. In this work, the effect of gaps on the instantaneous Doppler spectrum of each channel and the influence on the result of the azimuth impulse compression after aperture synthesis are analyzed. In addition, an estimation method of gaps based on the phase errors between channels is proposed to reduce the influence. The estimation accuracy of the proposed method is analyzed, and the effectiveness of the method is verified with simulations. The estimated gaps are used to compensate for the phase discontinuity of the azimuth signal after aperture synthesis caused by gaps. The method improves the result of aperture synthesis and reduces the side-lobe of the azimuth impulse compression after aperture synthesis.

8.
Sci Rep ; 9(1): 1368, 2019 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-30718661

RESUMO

Predicting physical response of an artificially structured material is of particular interest for scientific and engineering applications. Here we use deep learning to predict optical response of artificially engineered nanophotonic devices. In addition to predicting forward approximation of transmission response for any given topology, this approach allows us to inversely approximate designs for a targeted optical response. Our Deep Neural Network (DNN) could design compact (2.6 × 2.6 µm2) silicon-on-insulator (SOI)-based 1 × 2 power splitters with various target splitting ratios in a fraction of a second. This model is trained to minimize the reflection (to smaller than ~ -20 dB) while achieving maximum transmission efficiency above 90% and target splitting specifications. This approach paves the way for rapid design of integrated photonic components relying on complex nanostructures.

9.
Chem Commun (Camb) ; 54(92): 12942-12945, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30289419

RESUMO

Photo-induced free radical production was observed in tetraphenylethylene ligand-based metal-organic frameworks (MOFs). This feature endows the MOFs with reversible, fast, obvious, and controllable photo-induced color/emission transformation, excellent fatigue resistance ability and good light stability.

10.
Chem Commun (Camb) ; 53(60): 8435-8438, 2017 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-28702539

RESUMO

A solvent-dependent oxidative dearomatization-induced divergent [5+2] cascade approach to bicyclo[3.2.1]octanes was described. This novel protocol enables a facile synthesis of a series of diversely functionalized ent-kaurene and cedrene-type skeletons in good yields and excellent diastereoselectivities.

11.
J Org Chem ; 82(11): 5898-5903, 2017 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-28494581

RESUMO

An oxidative N-S bond formation reaction has been established for 1,2,4-thiadiazole synthesis employing molecular iodine as the sole oxidant. The features of the present reaction include no use of transition metals, mild reaction conditions, simple operation, and short reaction time. This versatile synthetic approach is broadly applicable to a variety of imidoyl and guanyl thiourea substrates to produce 5-amino and 3,5-diamino substituted 1,2,4-thiadiazole derivatives, respectively, in an efficient and scalable fashion.

12.
J Org Chem ; 81(20): 9924-9930, 2016 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-27676133

RESUMO

An I2/KI-promoted oxidative C-C bond formation reaction from C(sp3)-H and C(sp2)-H bonds has been used to construct quinazoline skeletons from N,N'-disubstituted amidines. The required substrates are readily prepared from the corresponding acyl chlorides, anilines, and alkyl/benzylamines by sequential amidation, chlorination, and amination reactions. Under the optimal oxidative cyclization conditions, all these amidines were conveniently transformed into the expected products in moderate to good yields. This practical and environmentally benign approach works well with crude amidine intermediates and can also be carried out on a gram scale.

13.
Sensors (Basel) ; 16(2): 150, 2016 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-26821023

RESUMO

In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved.

14.
J Exp Bot ; 66(20): 6233-44, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26175352

RESUMO

Optimal inflorescence architecture is important for plant reproductive success by affecting the ultimate number of flowers that set fruits and for plant competitiveness when interacting with biotic or abiotic conditions. The pedicel is one of the key contributors to inflorescence architecture diversity. To date, knowledge about the molecular mechanisms of pedicel development is derived from Arabidopsis. Not much is known regarding other plants. Here, an SVP family MADS-box gene, NtSVP, in tobacco (Nicotiana tabacum) that is required for pedicel elongation was identified. It is shown that knockdown of NtSVP by RNA interference (RNAi) caused elongated pedicels, while overexpression resulted in compact inflorescences with much shortened pedicels. Moreover, an Arabidopsis BREVIPEDECELLUS/KNAT1 homologue NtBP-Like (NtBPL) was significantly up-regulated in NtSVP-RNAi plants. Disruption of NtBPL decreased pedicel lengths and shortened cortex cells. Consistent with the presence of a CArG-box at the NtBPL promoter, the direct binding of NtSVP to the NtBPL promoter was demonstrated by yeast one-hybrid assay, electrophoretic mobility shift assay, and dual-luciferase assay, in which NtSVP may act as a repressor of NtBPL. Microarray analysis showed that down-regulation of NtBPL resulted in differential expression of genes associated with a number of hormone biogenesis and signalling genes such as those for auxin and gibberellin. These findings together suggest the function of a MADS-box transcription factor in plant pedicel development, probably via negative regulation of a BP-like class I KNOX gene. The present work thus postulates the conservation and divergence of the molecular regulatory pathways underlying the development of plant inflorescence architecture.


Assuntos
Regulação da Expressão Gênica , Proteínas de Homeodomínio/genética , Proteínas de Plantas/genética , Tabaco/genética , Fatores de Transcrição/genética , Proteínas de Homeodomínio/metabolismo , Inflorescência/genética , Inflorescência/crescimento & desenvolvimento , Inflorescência/metabolismo , Proteínas de Plantas/metabolismo , Interferência de RNA , Tabaco/crescimento & desenvolvimento , Tabaco/metabolismo , Fatores de Transcrição/metabolismo
16.
ACS Appl Mater Interfaces ; 6(24): 22166-73, 2014 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-25478992

RESUMO

In the present study, the molecular and magnetic dual-targeted redox-responsive folic acid-cysteine-Fe3O4 microcapsules (FA-Cys-Fe3O4 MCs) have been synthesized via the sonochemical technique, and targeting molecule (folic acid) and Fe3O4 magnetic nanoparticles are introduced into the microcapsule shells successfully. The obtained FA-Cys-Fe3O4 MCs show excellent magnetic responsive ability by the oriented motion under an external magnetic field. The hydrophobic fluorescent dye (Coumarin 6) is successfully loaded into the FA-Cys-Fe3O4 MCs, demonstrating that it could be also easily realized to encapsulate hydrophobic drugs into the FA-Cys-Fe3O4 MCs when the drugs are dispersed into the oil phase before sonication. Cellular uptake demonstrates that FA-Cys-Fe3O4 MCs could target selectively the cells via folate-receptor-mediated endocytosis. Moreover, the FA-Cys-Fe3O4 MCs show their potential ability to be an attractive carrier for drug controlled release owing to the redox responsiveness of the disulfide in the microcapsule shells.


Assuntos
Cápsulas/síntese química , Preparações de Ação Retardada/síntese química , Ácido Fólico/administração & dosagem , Nanopartículas de Magnetita/química , Sonicação/métodos , Cápsulas/efeitos da radiação , Cisteína/química , Difusão , Composição de Medicamentos/métodos , Ácido Fólico/química , Células HeLa , Ondas de Choque de Alta Energia , Humanos , Nanopartículas de Magnetita/administração & dosagem , Nanopartículas de Magnetita/ultraestrutura , Teste de Materiais , Oxirredução/efeitos da radiação , Tamanho da Partícula
17.
Chemistry ; 20(46): 15053-60, 2014 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-25262815

RESUMO

In this study, a concise and stereoselective approach for the divergent total synthesis of (-)-indoxamycins A-F is described. The key steps of the strategy include an Ireland-Claisen rearrangement, an enantioselective 1,6-enyne reductive cyclization, and a tandem 1,2-addition/oxa-Michael/methylenation reaction. The relative and absolute configuration of these natural products has been unambiguously elucidated, and their cytotoxic activities against HT-29 and A-549 tumor cell lines are also reported.


Assuntos
Antineoplásicos/síntese química , Compostos Heterocíclicos com 3 Anéis/síntese química , Propionatos/síntese química , Actinobacteria/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Produtos Biológicos/síntese química , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Linhagem Celular Tumoral , Ciclização , Compostos Heterocíclicos com 3 Anéis/química , Compostos Heterocíclicos com 3 Anéis/farmacologia , Humanos , Modelos Moleculares , Neoplasias/tratamento farmacológico , Propionatos/química , Propionatos/farmacologia , Estereoisomerismo
18.
Org Lett ; 16(12): 3376-9, 2014 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-24895836

RESUMO

A concise and efficient approach for the diastereoselective total synthesis of salvileucalin C, as well as their biosynthetically related diterpenoids salvileucalin D, salvipuberulin, isosalvipuberulin, and dugesin B, has been reported for the first time. The key features of the strategy are based on a Beckwith-Dowd ring expansion, a tandem diastereoselective Stille coupling/debromination/desilylation/lactonization reaction, and a photoinduced electrocyclic ring contraction.


Assuntos
Diterpenos/síntese química , Diterpenos/química , Estrutura Molecular , Salvia/química , Estereoisomerismo
19.
Opt Express ; 22(7): 8533-40, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24718225

RESUMO

A novel wavelength combiner using non-uniform refractive index distribution within a multimode interference device is proposed and simulated. The refractive index step creates separate localized modes with different effective refractive indices and two modes are strongly excited which form the basis of an interferometer. We applied the concept to 1.30/1.31 µm and 1.31/1.55 µm wavelength combiners on an InP substrate. The lengths of the devices are 1272 µm and 484 µm with simulated insertion losses of 0.6 dB and 0.67 dB respectively.

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