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1.
J Phys Chem B ; 125(41): 11540-11547, 2021 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-34636571

RESUMO

Push-pull organic structures characterized by an intramolecular charge transfer (ICT) process and π-electron delocalization are potentially interesting luminescent materials. A series of three-dimensional o-carborane-containing perylene bisimide derivatives (PBIs) were synthesized, and their optical properties were systematically investigated to illustrate the stereo effect, especially on the two-photon absorption (2PA) and optical power limiting (OPL) properties. Open-aperture Z-scan curves showed that all four PBIs displayed strong and broad two-photon absorptivities based on the resonance-enhanced phenomenon. The maximum degenerate two-photon absorption cross section (δ2PA) increased with the number of PBI substituents. The derivative CB-PBI possessed a δ2PA value of ∼2400 GM at 650 nm, a significant enhancement in comparison with that of the parent PBI (∼719 GM), ascribed to the present stereo effect. When the aromatic-donating units changed from naphthyl and pyrenyl to PBI, the generated multidimensional intramolecular charge transfer (ICT) from the aromatic units to the o-carborane cage contributed to the 2PA processes. All of the fluorophores exhibited excellent optical power limiting (OPL) performances as well as a minimum limiting threshold of ∼4.98 mJ/cm2 for CB-PBI. These significant results not only allow us to get deep insight into the nature of the fundamental stereo effect and nonlinear optical (NLO) response involved but also guide us toward the design of new multifunctional luminescent materials.

2.
Comput Math Methods Med ; 2021: 6842752, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34646337

RESUMO

Clustering analysis is one of the most important technologies for single-cell data mining. It is widely used in the division of different gene sequences, the identification of functional genes, and the detection of new cell types. Although the traditional unsupervised clustering method does not require label data, the distribution of the original data, the setting of hyperparameters, and other factors all affect the effectiveness of the clustering algorithm. While in some cases the type of some cells is known, it is hoped to achieve high accuracy if the prior information about those cells is utilized sufficiently. In this study, we propose SCMAG (a semisupervised single-cell clustering method based on a matrix aggregation graph convolutional neural network) that takes into full consideration the prior information for single-cell data. To evaluate the performance of the proposed semisupervised clustering method, we test on different single-cell datasets and compare with the current semisupervised clustering algorithm in recognizing cell types on various real scRNA-seq data; the results show that it is a more accurate and significant model.


Assuntos
Análise por Conglomerados , Redes Neurais de Computação , Análise de Célula Única/estatística & dados numéricos , Aprendizado de Máquina Supervisionado , Algoritmos , Biologia Computacional , Mineração de Dados/estatística & dados numéricos , Bases de Dados de Ácidos Nucleicos , Humanos , RNA-Seq
3.
Sensors (Basel) ; 21(15)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34372398

RESUMO

Accurate semantic image segmentation from medical imaging can enable intelligent vision-based assistance in robot-assisted minimally invasive surgery. The human body and surgical procedures are highly dynamic. While machine-vision presents a promising approach, sufficiently large training image sets for robust performance are either costly or unavailable. This work examines three novel generative adversarial network (GAN) methods of providing usable synthetic tool images using only surgical background images and a few real tool images. The best of these three novel approaches generates realistic tool textures while preserving local background content by incorporating both a style preservation and a content loss component into the proposed multi-level loss function. The approach is quantitatively evaluated, and results suggest that the synthetically generated training tool images enhance UNet tool segmentation performance. More specifically, with a random set of 100 cadaver and live endoscopic images from the University of Washington Sinus Dataset, the UNet trained with synthetically generated images using the presented method resulted in 35.7% and 30.6% improvement over using purely real images in mean Dice coefficient and Intersection over Union scores, respectively. This study is promising towards the use of more widely available and routine screening endoscopy to preoperatively generate synthetic training tool images for intraoperative UNet tool segmentation.


Assuntos
Endoscopia , Processamento de Imagem Assistida por Computador , Humanos , Semântica
4.
Anal Chem ; 93(24): 8501-8507, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34114804

RESUMO

In a film-based fluorescence sensor, luminogens are of vital importance since they play the role of probes or indicators. Traditional organic luminogens like pyrene show high luminescence quantum yields in dilute solutions, but their applications are usually limited by the aggregation-caused quenching (ACQ) effect and bad photochemical stability. Thus, this paper reports a novel aggregation-induced emission luminogen (AIEgen) containing both pyrene and o-carborane (CB-PY), which possesses unique dual-phase emission both in solution and solid state and intramolecular charge transfer (ICT) properties, fulfilling the gap between ACQ and AIE compounds. Importantly, the fluorophore presents extraordinary stability that there was almost no attenuation in the emission intensity of CB-PY in the solid state after 4 months of exposure at ambient conditions. It is these merits that make CB-PY exhibit outstanding sensing performances for volatile organic compounds (VOCs), where the fluorescence test strip shows fast, reversible, and visual discrimination of four organic solvents with varied polarities. Moreover, 92#, 95#, and 98# gasolines could be discriminated with CB-PY, showing different colors under UV illumination.

5.
ACS Appl Mater Interfaces ; 12(9): 11084-11093, 2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32031775

RESUMO

Colorimetric chemosensors have attracted tremendous interest for sensing hazardous substances in an uncomplicated and economical manner. Herein, a series of push-pull dicyanovinyl-substituted oligothiophene derivatives were designed, and the impacts of different end-cappers on their photophysical properties were comprehensively investigated. Interestingly, combined with a zinc porphyrin derivative (Zn-TPP), one dicyanovinyl-substituted oligothiophene derivative (NA-3T-CN) can be further developed into colorimetric and fluorescent sensor array for dual-mode detection of aliphatic amines and hydrazine. The obtained sensors showed satisfactory results between optical response and analyte's concentration both in selective single-sensor type and in enhanced multisensory mode. Based on the fluorescence change of the NA-3T-CN system, the detection limit for N2H4 was calculated to be around 1.22 × 10-5 mol/L in THF. The stained TLC-supported sensor array offers obvious optical changes for down to 0.5 wt % hydrazine solution for naked-eye sensing. An aromatic amine like aniline has no obvious effect on the dicyanovinyl-substituted oligothiophene derivatives. We also found that a zinc porphyrin derivative has an obvious colorimetric response to the presence of hydrazine, ethanolamine, and aniline. Furthermore, smartphone-enabled readout system and data treatment based on RGB changes of the sensor array were performed, and the discrimination capability among hydrazine, aliphatic amines, and aromatic amine was satisfactory. In this regard, related push-pull oligothiophene derivatives not only can be regarded as models for a fundamental understanding of the relationship between molecular structure and photophysical properties but also present potential applications in the field of real-time and visual detection of hazardous chemicals.

6.
Phys Rev E ; 102(6-1): 063306, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33466071

RESUMO

A large-density-ratio and tunable-viscosity-ratio multicomponent multiphase pseudopotential lattice Boltzmann model is used to study the dissolution process of a bubble under pressure. The multi-relaxation-time collision operator, exact-difference-method external force scheme, and scaling coefficient k are applied to ensure the numerical stability of the model. The influence of k in the equation of state (EOS) and intermolecule interaction strength on the stationary bubble evolution process are discussed, and the effect of k on thermodynamic consistency is also analyzed. The results indicate that adjusting the scaling coefficient in the EOS changes the surface tension and interface thickness, and that the gas-liquid interface width w is proportional to 1/sqrt[k]. Considering the effect of k on the surface tension, interface thickness, and thermodynamic consistency, the scaling coefficient should be between 0.6 and 1. Furthermore, the dissolution process of a single bubble under pressure is studied using the developed model, and it is found that the dissolution mass and concentration of dissolved gas increase linearly with increases in the pressure difference, and that the concentration of dissolved gas is proportional to the gas pressure after the fluid system reaches equilibrium. These results are consistent with Henry's law.

7.
Anal Chem ; 91(22): 14451-14457, 2019 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-31621298

RESUMO

Film-based fluorescence sensing is recognized as one of the most optimized techniques for trace analysis of chemicals in the air after the invention of ion mobility spectrometry. The performance of the technique is highly dependent on the design of the film. This paper reports a new fluorescent film which shows unprecedented and discriminative sensing performance to the presence of phenol, o-cresol, m-cresol, and p-cresol in the air with an ultralow detection limit as low as 0.4, 0.3, 10, and 0.8 ppt, respectively. The film was designed via combination of the advantages of aggregation-induced emission (AIE) and those of intramolecular charge transfer (ICT), where the former provides the opportunity to avoid the widely encountered aggregation-caused quenching (ACQ) effect and the latter allows sensitive sensing of the microenvironment change of the film. The biggest challenge of the design is to find a fluorophore possessing both AIE and ICT effects. Fortunately, a newly synthesized biphenyl derivative of o-carborane capped with azetidine moiety (BZPCarb) shows the properties as expected. Importantly, the fluorophore is photochemically stable, a prerequirement for multiple uses of a film device. In addition, the nonplanar structure of the fluorophore is also favorable for film sensing as it could form porous films owing to screening of dense stacking of the molecules. It is the merits that make BZPCarb-based film show outstanding sensing and discriminative performances. Based on the fluorophore and the design, a conceptual high-performance fluorescent vapor sensor for phenolic compounds was developed.

8.
Chem Asian J ; 14(15): 2751-2758, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31210030

RESUMO

A reliable and sensitive detection of biogenic amines (BAs) is essential to ensure food safety and maintain public health. In this study, two naphthyl end-capped terthiophene derivatives, namely, 5-(naphthalen-1-yl)-2,2':5',2''-terthiophene (NA-3T) and 5,5''-di(naphthalen-1-yl)-2,2':5',2''-terthiophene (NA-3T-NA), were employed to develop chemiresistive sensors for detecting gaseous BAs. In contrast to NA-3T, the NA-3T-NA-based sensor showed a higher sensitivity for trimethylamine (TMA) with an experimental detection limit lower than 22 ppm, and for aromatic BAs, including dopamine, histamine, tryptamine, and tyramine. Additionally, the recovery time for TMA was found to be shorter than 23 s. In addition, both sensors were successfully used for an in situ evaluation of meat freshness by monitoring the concentration of relevant volatile BAs. The difference in the sensing performances of the two chemiresistive sensors was tentatively ascribed to different packing structures of the derivatives and the adlayer structures of the films developed with the compounds.


Assuntos
Aminas Biogênicas/análise , Inocuidade dos Alimentos/métodos , Carne/análise , Tiofenos/química , Cristalografia por Raios X , Dopamina/análise , Conformação Molecular , Espectrofotometria , Temperatura , Termogravimetria
9.
Chem Commun (Camb) ; 55(7): 941-944, 2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30601477

RESUMO

The development of sensors for the detection of triacetone triperoxide (TATP) has attracted great attention. Here, we constructed a low-cost, portable, reusable, visible paper-based fluorescent sensor for the sensitive detection of TATP via vapor sampling. Under optimized conditions, the fluorescent film showed a high sensitivity to TATP with a detection limit of lower than 0.5 µg mL-1 in air. The linear range of the response is from 0.5 to 8.0 µg mL-1. In addition, the paper-based sensor exhibited high selectivity to TATP. The presence of potential interferents showed little effect on sensing. Moreover, sensing is fully reversible. Fortunately, the test can also be conducted in a visualized way.

10.
Anal Chem ; 90(23): 14088-14093, 2018 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-30398856

RESUMO

In situ, on line, noncontact, and fast monitoring of the compositions of ethanol-water mixtures via vapor-phase sampling has remained a challenge for years. In this work, we report for the first time a film-based fluorescent sensor showing unprecedented ability to discriminate the compositions of ethanol-water mixtures. Importantly, ethanol contents in the mixtures can vary from 0 to 100% (v/v), the response time is less than 2 s, and the sensing is fully reversible. More importantly, the monitoring was performed via vapor-phase sampling, avoiding sample contamination. The principle behind it is ascribed to the big difference in the fluorescent quantum yield of the sensing unit, a newly designed and synthesized monosubstituted fluorescent o-carborane derivative (ZPCarb), in the two solvents. In addition, the sensor as developed was successfully used for the determination of ethanol contents in four commercial liquors, suggesting its potential application in the quality control of beverages, in monitoring fermentation processes, and in other processes.


Assuntos
Compostos de Boro/química , Etanol/análise , Corantes Fluorescentes/química , Água/análise , Compostos de Boro/síntese química , Corantes Fluorescentes/síntese química , Estrutura Molecular , Volatilização
11.
Soft Matter ; 14(39): 7950-7953, 2018 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-30259041

RESUMO

A novel dynamic-covalent bond-based single network hydrogel was developed, of which the failure compressive stress and strain as well as the failure tensile stress and strain could exceed 27.3 MPa and 98.4% as well as 0.23 MPa and 282.3%, respectively. In addition, the gel shows remarkable slice-resistance and self-healing properties.

12.
Bioinformatics ; 34(12): 2123-2125, 2018 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29385403

RESUMO

Summary: Alternative polyadenylation (APA) is now emerging as a widespread mechanism modulated tissue-specifically, which highlights the need to define tissue-specific poly(A) sites for profiling APA dynamics across tissues. We have developed an R package called TSAPA based on the machine learning model for identifying tissue-specific poly(A) sites in plants. A feature space including more than 200 features was assembled to specifically characterize poly(A) sites in plants. The classification model in TSAPA can be customized by selecting desirable features or classifiers. TSAPA is also capable of predicting tissue-specific poly(A) sites in unannotated intergenic regions. TSAPA will be a valuable addition to the community for studying dynamics of APA in plants. Availability and implementation: https://github.com/BMILAB/TSAPA. Supplementary information: Supplementary data are available at Bioinformatics online.


Assuntos
Biologia Computacional/métodos , Plantas/metabolismo , Poliadenilação , Software , Aprendizado de Máquina , Poli A , Análise de Sequência de DNA , Análise de Sequência de RNA
13.
Adv Colloid Interface Sci ; 252: 1-20, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29395035

RESUMO

Dopamine-based materials are emerging as novel biomaterials and have attracted considerable interests in the fields of biosensing, bioimaging and cancer therapy due to their unique physicochemical properties, such as versatile adhesion property, high chemical reactivity, excellent biocompatibility and biodegradability, strong photothermal conversion capacity, etc. In this review, we present an overview of recent research progress on dopamine-based materials for diagnosis and therapy of cancer. The review starts with a summary of the physicochemical properties of dopamine-based materials in general. Then detailed description is followed on their applications in the fields of diagnosis and treatment of cancers. The review concludes with an outline of some remaining challenges for dopamine-based materials to be used for clinical applications.


Assuntos
Dopamina/química , Dopamina/uso terapêutico , Neoplasias/diagnóstico , Neoplasias/terapia , Animais , Humanos
14.
J Phys Chem B ; 120(46): 11961-11969, 2016 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-27797516

RESUMO

A pyrenyl unit (Py) was chemically connected to a perylene bisimide (PBI) moiety through a long and flexible linker, 4,7,10-trioxa-1,13-tridecanediamine (TOA), resulting in a fluorescent dyad, PBI-TOA-Py. Ultraviolet-visible absorption and fluorescence studies revealed that the two fluorescent units of PBI-TOA-Py behave independently. However, efficient Förster resonance energy transfer (FRET) from the Py unit to the PBI moiety in solution state was also observed. Temperature and solvent effect studies demonstrated that the energy transfer efficiency is highly dependent upon solution temperature and solvent nature. Specifically, for the dimethylformamide (DMF) solution of PBI-TOA-Py, the FRET efficiency is close to 88% at temperatures below ∼40 °C, but the efficiency greatly decreases to nearly zero when the temperature exceeds ∼80 °C. Moreover, addition of HAc into the DMF solution at room temperature could reduce the energy transfer efficiency to nearly zero, suggesting that the excited state energy of Py cannot be directly transferred to the PBI structure even though they are properly and chemically bonded. On the basis of the observations and time-resolved studies, it is believed that the observed efficient FRET from the Py unit to the PBI moiety occurs mainly through Py excimer formation, which could be a result of intermolecular association of the compound. Thus, the applications of the fluorescent dyad in solvent discrimination and trace water determination in organic solvents were verified through example studies.

15.
Phys Chem Chem Phys ; 18(36): 25210-25220, 2016 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-27711634

RESUMO

A new fluorescent conjugate (PNBD) with a structure of D-π-A was designed and synthesized, where the donor (D), the acceptor (A) and the bridge (π) are naphthalyl, dicyanovinyl and phenylethynyl-phenylethynyl, respectively. To improve the solubility of the conjugate, two long alkyl chains were introduced as substituents of the central aromatic ring. Spectroscopic studies demonstrated that PNBD is a strongly solvatochromic probe which is characterized by a large molar absorption coefficient (>32 000 cm-1 M-1), long wavelength absorption (>410 nm), large solvatochromic emission range (470-650 nm), high photochemical stability, and good solubility in common organic solvents. The fluorescent quantum yield of PNBD is limited in some polar solvents due to dual emission, a phenomenon ascribed to radiative decay from a higher excited singlet state. To eliminate dual emission, a covalently bound dimer (BPNBD) of PNBD characterized by weak vibronic coupling, was designed and synthesized. The dimer constituents are linked by a single bond between the naphthalyl moieties of the two PNBD monomers. As expected, BPNBD maintains almost all the strong points of the monomer, exhibits a substantial increase in fluorescence quantum yield, and eliminates dual emission by facilitating efficient internal conversion. Importantly, the use of PNBD and BPNBD in concert provides unprecedented discrimination among solvents of similar structures, such as (CH2Cl2, CHCl3, CCl4), (ethyl ether, THF, dioxane), or (methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, n-decanol), allowing rapid and selective visual identification.

16.
Sci Rep ; 6: 31187, 2016 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-27498703

RESUMO

We synthesized two specially designed pyrenyl (Py) derivatives of phenylboronic acid, PSNB1 and PSNB2, of which PSNB2 self-assemble to form dynamic aggregate in methanol-water mixture (1:99, v/v) via intermolecular H-bonding and pi-pi stacking. Interestingly, the dynamic aggregate shows smart response to presence of fructose (F) as evidenced by fluorescence color change from green to blue. More interestingly, the fluorescence emission of the resulted PSNB2-F changes from blue to green with the addition of formaldehyde (FA). The reason behind is formation of a PSNB2-F dimer via FA cross-linking. Based upon the reactions as found, sensitive and fast sensing of F and FA in water was realized, of which the experimental DLs could be significantly lower than 10 µM for both analytes, and the response times are less than 1 min. It is believed that not only the materials as created may have the potential to find real-life applications but also the strategy as developed can be adopted to develop other dynamic materials.


Assuntos
Ácidos Borônicos/química , Formaldeído/análise , Frutose/análise
17.
ACS Appl Mater Interfaces ; 8(28): 18584-92, 2016 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-27348461

RESUMO

Modification of naphthalene diimide (NDI) resulted in a photochemically stable, fluorescent 3,4,5-tris(dodecyloxy)benzamide derivative of NDI (TDBNDI), and introduction of the long alkyl chains endowed the compound with good compatibility with commonly found organic solvents and in particular superior self-assembly in the solution state. Further studies revealed that TDBNDI forms gels with nine of the 18 solvents tested at a concentration of 2.0% (w/v), and the critical gelation concentrations of five of the eight gels are lower than 1.0% (w/v), indicating the high efficiency of the compound as a low-molecular mass gelator (LMMG). Transmission electron microscopy, scanning electron microscopy, and confocal laser scanning microscopy studies revealed the networked fibrillar structure of the TDBNDI/methylcyclohexane (MCH) gel. On the basis of these findings, a fluorescent film was developed via simple spin-coating of the TDBNDI/MCH gel on a glass substrate surface. Fluorescence behavior and sensing performance studies demonstrated that this film is photochemically stable, and sensitive and selective to the presence of aniline vapor. Notably, the response is instantaneous, and the sensing process is fully and quickly reversible. This case study demonstrates that derivatization of photochemically stable fluorophores into LMMGs is a good strategy for developing high-performance fluorescent sensing films.

18.
Spectrochim Acta A Mol Biomol Spectrosc ; 165: 145-149, 2016 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-27131145

RESUMO

A fluorescent film based on a cholesteryl derivative of perylene bisimide (PTCDI-co-CholDEA) was fabricated via utilization of an electrostatic spinning technique on a glass plate surface. SEM studies revealed that the film was characterized by fibrous network structure. It is the structure and the chemical composition that make the fluorescence emission of the film sensitive to the variation of local environmental humidity. The sensitivity of the sensing is 0.1497 (×10(4)a.u. of the intensity)/1% RH, of which RH is the abbreviation of relative humidity. The maximum quenching efficiency of the film is 55.4% when humidity reaches 97% RH. Furthermore, the sensing process is fully reversible, and presence of other commonly found liquids shows little effect to the monitoring process.

19.
Phys Chem Chem Phys ; 18(17): 12221-30, 2016 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-27079559

RESUMO

A perylene bisimide (PBI) derivative (C-PBI-Py) of pyrene (Py) and cholesteryl residue (C) possessing intra-molecular energy transfer properties and three reference compounds (C-Py, C-PBI, PBI-Py) were designed and synthesized, where C was introduced in order to enhance the solubility of the relevant compounds in organic solvents. UV-vis absorption, steady-state fluorescence, cyclic voltammetric and theoretical calculation studies revealed that: (1) the PBI unit and Py moiety of C-PBI-Py could act as two individual chromophores, (2) the excited state energy of Py could transfer to PBI within a single molecule of the compound, and (3) the PBI moiety of the compound tends to form aggregates and shows PBI excimer emission. Time-resolved and temperature-dependent emission spectroscopy studies revealed the presence of both H-type excimer and J-type excimer, and formation of them via either the Birks' scheme or the pre-formed scheme due to strong π-π stacking that was elucidated by concentration-dependent (1)H NMR spectroscopy measurement. In addition, the studies also indicated that the energy transfer occurs via an electron exchange mechanism (Dexter scheme). Results of this study will be useful in the development of new solvatochromic and other environment-sensitive fluorophores based on alteration of intra-molecular energy transfer efficiency.


Assuntos
Colesterol/química , Corantes Fluorescentes/química , Imidas/química , Perileno/análogos & derivados , Pirenos/química , Corantes Fluorescentes/síntese química , Espectroscopia de Ressonância Magnética , Perileno/química , Teoria Quântica , Solventes/química , Espectrofotometria Ultravioleta , Temperatura , Termodinâmica
20.
Chem Commun (Camb) ; 51(45): 9346-9, 2015 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-25959768

RESUMO

An original simple homogeneous acid medium was used to synthesize polymer/surfactant-free acicular micro-rod particles (10-40 µm long by 0.1-0.3 µm diameter) of the novel [Fe(Htrz)3](CF3SO3)2 complex. The study of the spin crossover properties reveals a rare 50 K hysteretic behavior perfectly centered at room temperature accompanied by a pronounced thermochromism effect, purple in the low spin state and white in the high spin state.

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