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1.
Interdiscip Sci ; 2022 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-35939233

RESUMO

A surge in research has occurred because of current developments in single-cell technologies. Above all, single-cell Assay for Transposase-Accessible Chromatin with high throughput sequencing (scATAC-seq) is a popular approach of analyzing chromatin accessibility differences at the level of single cell, either within or between groups. As a result, it is critical to examine cell heterogeneity at a previously unseen level and to identify both recognized and unknown cell types. However, with the ever-increasing number of cells engendered by technological development and the characteristics of the data, such as high noise, sparsity and dimension, challenges in distinguishing cell types have emerged. We propose scVAEBGM, which integrates a Variational Autoencoder (VAE) with a Bayesian Gaussian-mixture model (BGM) to process and analyze scATAC-seq data. This method combines and takes benefits of a Bayesian Gaussian mixture model to estimate the number of cell types without determining the cluster number in a beforehand. In other words, the size of the clusters is inferred from the data, thus avoiding biases introduced by subjective assessments when manually determining the size of the clusters. Additionally, the method is more robust to noise and can better represent single-cell data in lower dimensions. We also create a further clustering strategy. It is indicated by experiments that further clustering based on the already completed clustering can improve the clustering accuracy again. We test on six public datasets, and scVAEBGM outperforms various dimension reduction baselines. In downstream applications, scVAEBGM can reveal biological cell types.

2.
Artigo em Inglês | MEDLINE | ID: mdl-35876718

RESUMO

Single-Atom Sites (SASs) are commonly stabilized and influenced by neighboring atoms in the host; disclosing the structure-reactivity relationships of SASs in water electrolysis are the grand challenges originating from the enormous support materials with complex structures. Through a multidisciplinary view of the design principles, synthesis strategies, characterization techniques, and theoretical analysis of structure-performance correlations, this timely review is dedicated to summarizing the most recent progress in tailoring bond microenvironments on different supports and discussing the reaction pathways and performance advantages of different SAS structures for water electrolysis . The essences and mechanisms of how SAS structures influence their electrocatalysis and the critical needs for their future developments are discussed. Finally, the challenges and perspectives are also provided to stimulate their practically widespread utilization in water-splitting electrolyzers.

3.
Entropy (Basel) ; 24(6)2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-35741548

RESUMO

The main concern of this paper is finite-time stability (FTS) for uncertain discrete-time stochastic nonlinear systems (DSNSs) with time-varying delay (TVD) and multiplicative noise. First, a Lyapunov-Krasovskii function (LKF) is constructed, using the forward difference, and less conservative stability criteria are obtained. By solving a series of linear matrix inequalities (LMIs), some sufficient conditions for FTS of the stochastic system are found. Moreover, FTS is presented for a stochastic nominal system. Lastly, the validity and improvement of the proposed methods are shown with two simulation examples.

4.
ACS Appl Mater Interfaces ; 13(43): 51174-51185, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34689545

RESUMO

Li-S batteries are considered to be the most promising next-generation advanced energy-storage systems. However, the sluggish reaction kinetics and the "shuttle effect" of lithium polysulfides (LiPSs) severely limit their battery performances. To overcome the complex and multiphase sulfur redox chemistry of LiPSs, in this study, we propose a new type of cobalt-based double catalytic sites (DCSs) codoped mesoporous carbon to immobilize and reversibly catalyze the LiPS intermediates in the cycling process, thus eliminating the shuttle effect and improving the charge-discharge kinetics. The theoretical calculation shows that the well-designed DCS configuration endows LiPSs with both strong and weak binding capabilities, which will facilitate the synergistic and reversible catalytic conversion. Furthermore, the experimental results also confirm that the DCS structure shows significantly enhanced catalytic kinetics than the single catalytic sites. The Li-S battery equipped with the DCS structure displays an extremely high discharge capacity of 918 mA h g-1 at a current density of 0.2 C and can reach a capacity of 867 mA h g-1 after 200 cycles with an ultralow capacity attenuation rate of 0.028% for each cycle. This study opens new avenues to address the catalytic requirements both in discharging and charging processes.

5.
ChemSusChem ; 14(23): 5112-5134, 2021 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-34520128

RESUMO

Water electrolysis is considered to be one of the most promising technologies to produce clean fuels. However, its extensive realization critically depends on the progress in cost-effective and high-powered oxygen evolution reaction (OER) electrocatalysts. As a member of the big family of two-dimensional (2D) materials, nanostructured layered double hydroxides (nLDHs) have made significant processes and continuous breakthroughs for OER electrocatalysis. In this Review, the advancements in designing nLDHs for OER in recent years were discussed with a unique focus on their electronic modulations and in situ analysis on catalytic processes. After a brief discussion on different synthetic methodologies of nLDHs, including "bottom-up" and "top-down" approaches, the general strategies to enhance the catalytic performances of nLDHs reported so far were summarized, including compositional substitution, heteroatom doping, vacancy engineering, and amorphous/crystalline engineering. Furthermore, the in situ OER processes and mechanism analysis on engineering efficient nLDHs electrocatalysts were discussed. Finally, the research trends, perspectives, and challenges on designing nLDHs were also carefully outlined. This progress Review may offer enlightening experimental/theoretical guidance for designing highly catalytic active nLDHs and provide new directions to promote their future prosperity for practical utilization in water splitting.

6.
ACS Appl Mater Interfaces ; 12(47): 53239-53246, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33197169

RESUMO

Due to the dynamic nature of networks and high mobility of molecular chains, self-healing elastomers are usually confronted with the trade-off between self-healing efficiency and mechanical properties. Herein, a self-healing ionomer with both high mechanical performance and high self-healing efficiency has been successfully developed by grafting bromobutyl rubber (BIIR) with pyridine-based derivatives. Interestingly, the substituents on the pyridine ring can be used to regulate the interaction forces of ionic clusters and molecular dynamics. The electron-donating effect of the substituents facilitates stable π-π stacking between pyridyl ions, inducing the formation of regular and large ion aggregates, thereby improving the mechanical strength of the ionomer. Meanwhile, the plasticizing effect of the substituents reduces the activation energy and relaxation temperature of the ionic aggregates, thus endowing the ionomer with a high self-healing efficiency. As a result, the ionomer shows tensile strength as high as 8.1 ± 0.3 MPa under room temperature and self-healing efficiency of 100 ± 3% at 60 °C. Therefore, this strategy can be easily extended to other halogen-containing polymers, leading to a novel class of self-healing ionomers that hold great promise in diverse applications.

7.
Nat Immunol ; 21(11): 1467, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32884131

RESUMO

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

8.
ISA Trans ; 102: 81-90, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32113650

RESUMO

The Pareto game for the model-free continuous-time stochastic system is studied through approximate/adaptive dynamic programming (ADP) in this paper. Firstly, the model-based online iterative algorithm is proposed, and it is proved that the control iterative sequence converges to the Pareto efficient solution, but the algorithm requires complete system parameters. Then, we derive the model-free iterative equation and develop the ADP algorithm to calculate the equation by collecting updated states and input information online. From the derivation of the ADP algorithm, the model-free iterative equation and the model-based iterative equation have the same solution, which means that the ADP algorithm can approximate the Pareto optimal solution. Next, the convergence analysis shows that the Pareto optimal strategy is uniquely determined by the ADP algorithm. Finally, two simulation examples confirm the feasibility of the ADP algorithm.

9.
J Colloid Interface Sci ; 568: 76-80, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32088453

RESUMO

Framework crystallization is an unresolved challenge in the chemistry of covalent organic frameworks (COFs) due to the poorly controlled simultaneous polymerization and crystallization processes. Here, we report the first morphogenesis of COF mesocrystals with two-dimensional hexagonal p6m symmetry through the combination of alkyl amine as a dynamic modulator and 2,4,6- triformylresorcinol imine as an asymmetrical building block. The amine modulator depresses the lateral growth of 2D sheets, and the slow kinetics combined with the asymmetrical conformation of 2,4,6-triformylresorcinol imine lead to the formation of transient imine macrocycles, which further undergo mesoscale self-assembly into nanotubular structures. The nanotubular structures tend to join together into rod-like bundles with ordered hexagonal rods, which finally grow into uniform hexagonal COF mesocrystals. The present strategy opens a nonclassical nucleation and crystal growth approach to create COFs with unexplored mesocrystal structures, which further extends the scope of crystalline framework materials and provides a new strategy for crystal morphogenesis.

10.
Chem Sci ; 12(1): 490-491, 2020 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-34163612

RESUMO

[This corrects the article DOI: 10.1039/C9SC00975B.].

11.
J Colloid Interface Sci ; 558: 32-37, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31580953

RESUMO

The formation of mesostructured polymer and carbon single-crystals is very difficult due to increased complexity of the energy hypersurface and the role of slowed-down kinetics. Here we reported the synthesis of ordered mesostructured phloroglucinol-formaldehyde single crystals through mesoscale self-assembly of reactive monomicelles under acidic conditions which were traditionally thought very difficult to control the morphology because of the rapid polymerization rate. Polymeric and carbon single crystals from unusual curved hexagonal rods and spindles with two-dimensional hexagonal mesostructures, to previously unreported lozenge single-crystal sheets with lamellar mesostructures were obtained. Contrary to the literature reports, the lamellar mesostructured lozenge single-crystal sheets were successfully transformed to graphene-like layered carbons after calcination under 800 °C, and they can be further exfoliated into unprecedented high-quality single-layered carbon nanoribbons. These results unambiguously expanded our understanding about mesocrystals, and opened up new avenues for the efficient production of single-layered carbon nanoribbons which possess promising applications in electrochemical devices.

13.
Chem Sci ; 10(21): 5546-5555, 2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31293739

RESUMO

A direct gas-solid reaction between fluorine gas (F2) and graphene is expected to become an inexpensive, continuous and scalable production method to prepare fluorinated graphene. However, the dependence of the fluorination intercalation of graphene is still poorly understood, which prevents the formation of high-quality fluorinated graphene. Herein, we demonstrate that chemical defects (oxygen group defects) on graphene sheets play a leading role in promoting fluorination intercalation, whereas physical defects (point defects), widely considered to be an advantage due to more diffusion channels for F2, were not influential. Tracing the origins, compared with the point defects, the unstable hydroxyl and epoxy groups produced active radicals and the relatively stable carbonyl and carboxyl groups activated the surrounding aromatic regions, thereby both facilitating fluorination intercalation, and the former was a preferential and easier route. Based on the above investigations, we successfully prepared fluorinated graphene with an ultrahigh interlayer distance (9.7 Å), the largest value reported for fluorinated graphene, by customizing graphene with more hydroxyl and epoxy groups. It presented excellent self-lubricating ability, with an ultralow interlayer interaction of 0.056 mJ m-2, thus possessing a far lower friction coefficient compared with graphene, when acting as a lubricant. Moreover, it was also easy to exfoliate by shearing, due to the diminutive interlayer friction and eliminated commensurate stacking. The exfoliated number of layers of less than three exceeded 80% (monolayer rate ≈ 40%), and no surfactant was applied to prevent further stacking.

14.
Cancer Immunol Res ; 7(7): 1054-1063, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31064778

RESUMO

Activation of RORγ with synthetic small-molecule agonists has been shown to enhance type 17 effector (CD4+ Th17 and CD8+ Tc17 cells) cell functions and decrease immunosuppressive mechanisms, leading to improved antitumor efficacy in adoptive cell transfer and syngeneic murine tumor models. However, whether Tc17 cells possess intrinsic cytotoxicity and the mechanism they use to lyse target cells is controversial. We report here that Tc17 cells were lytic effectors dependent on perforin and granzyme A. In contrast to Tc1 cells, Tc17 cells resisted activation-induced cell death and maintained granzyme A levels, which conferred the ability to lyse target cells in serial encounters. Thus, although the acute lytic capacity of Tc17 cells could be inferior to Tc1 cells, comparable lysis was achieved over time. In addition to direct lytic activity, Tc17 cells infiltrated early into the tumor mass, recruited other CD8+ T cells to the tumor, and enhanced the survival and lytic capability of these cells during repeated target encounters. Synthetic RORγ agonists further augmented Tc17 survival and lytic activity in vitro and in vivo, controlling tumor growth not only through direct cytotoxicity, but also through recruitment and improved function of other effector cells in the tumor microenvironment, which suggests complementary and cooperate activities for effective immunotherapy.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Citotoxicidade Imunológica/imunologia , Imunoterapia Adotiva/métodos , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/agonistas , Subpopulações de Linfócitos T/imunologia , Timoma/terapia , Neoplasias do Timo/terapia , Animais , Granzimas/metabolismo , Interleucina-17/imunologia , Interleucina-17/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Ovalbumina/imunologia , Timoma/imunologia , Timoma/patologia , Neoplasias do Timo/imunologia , Neoplasias do Timo/patologia
15.
J Colloid Interface Sci ; 532: 77-82, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30077831

RESUMO

Here, using reactive monomicelles as building blocks for mesoscale self-assembly, we demonstrate a general strategy for the preparation of robust phloroglucinol-formaldehyde (PF) aerogels with ordered mesoporosity and well-defined biomimetic truss frameworks, and thus possess enhanced mechanical properties and good recoverable compressibility. Besides, the prepared aerogels reveal interesting morphology enhanced sticky superhydrophobicity. A plausible formation mechanism was proposed which involving the formation of spherical reactive F127/PF oligomer monomicelles, then join together and elongate into rod-like micelles, which further aggregate to form ordered hexagonal nanorods and finally growth to form monolithic aerogels. This work encourages the further utilization of mesoscale self-assembly of monomicelles as a general and powerful strategy for the biomimetic synthesis of hierarchically porous monolithic materials possess highly ordered mesoscale structures and excellent mechanical properties.

16.
ACS Appl Mater Interfaces ; 10(34): 28828-28838, 2018 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-30067014

RESUMO

The poor dispersibility, strong interlayer interaction, and inferior crack resistance ability restrict the employment of graphene as a lubricant additive. Herein, we prepared fluorinated graphene with different F/C ratios by direct fluorination of multilayer graphene utilizing F2. Among them, highly fluorinated graphene (HFG) with an F/C ratio of about 1.0 presented prominent thermal stability and excellent tribological performance as an oil-based lubricant additive, whose friction coefficient and wear rate had a 51.4 and 90.9% decrease compared to that of pristine graphene, respectively. It was confirmed that C-F bonds perpendicular to the graphene plane contributed to increasing the interlayer distance and tribological performance of fluorinated graphene, while the randomly oriented CF2 and CF3 groups did not count as influential, as demonstrated via X-ray diffraction, X-ray photoelectron spectroscopy, and polarized attenuated total reflection-Fourier transform infrared spectroscopy. Meanwhile, Raman measurements traced the formation process of integrated and stable HFG tribofilm during friction process, and the corresponding stability was attributed to the physical and chemical interactions between HFG and friction pairs. More interestingly, the outstanding crack resistance ability of HFG preserved the sheet structure from destruction due to decreased in-plane stiffness and out-plane stress, thus constructing the tough tribofilm. The simple and feasible preparation makes HFG a promising candidate as advanced lubricant in industrial fabrication.

17.
Cancer Res ; 78(14): 3888-3898, 2018 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-29769201

RESUMO

Adoptive T-cell transfer therapy is an FDA- approved treatment for leukemia that relies on the ex vivo expansion and reinfusion of a patient's immune cells, which can be engineered with a chimeric antigen receptor (CAR) for more efficient tumor recognition. Type 17 T cells, controlled transcriptionally by RORγ, have been reported to mediate potent antitumor effects superior to those observed with conventionally expanded T cells. Here, we demonstrate that addition of a synthetic, small-molecule RORγ agonist during ex vivo expansion potentiates the antitumor activity of human Th17 and Tc17 cells redirected with a CAR. Likewise, ex vivo use of this agonist bolstered the antitumor properties of murine tumor-specific CD4+ and CD8+ T cells. Expansion in the presence of the RORγ agonist enhanced IL17A production without compromising IFNγ secretion in vitroIn vivo, cytokine neutralization studies revealed that IFNγ and IL17A were required to regress murine melanoma tumors. The enhanced antitumor effect of RORγ agonist treatment was associated with recovery of more donor T cells in the tumor and spleen; these cells produced elevated levels of cytokines months after infusion and expressed markers of long-lived stem and central memory cells such as Tcf7 and CD62L. Conversely, untreated cells mainly exhibited effector phenotypes in the tumor. Cured mice previously treated with agonist-primed T cells were protected from tumor rechallenge. Collectively, our work reveals that in vitro treatment with a RORγ agonist generates potent antitumor Type 17 effector cells that persist as long-lived memory cells in vivoSignificance: RORγ agonists can be used in vitro during T-cell expansion to enhance the efficacy of adoptive cell therapy (e.g., CAR-T) and to provide long-term protection against tumors.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/14/3888/F1.large.jpg Cancer Res; 78(14); 3888-98. ©2018 AACR.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Memória Imunológica/imunologia , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/imunologia , Células Th17/imunologia , Transferência Adotiva/métodos , Animais , Linhagem Celular Tumoral , Citocinas/imunologia , Humanos , Imunoterapia Adotiva/métodos , Interferon gama/imunologia , Interleucina-17 , Ativação Linfocitária/imunologia , Melanoma/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos SCID
18.
J Immunol ; 198(7): 2735-2746, 2017 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-28242647

RESUMO

Integration of signaling and metabolic pathways enables and sustains lymphocyte function. Whereas metabolic changes occurring during T cell activation are well characterized, the metabolic demands of differentiated T lymphocytes are largely unexplored. In this study, we defined the bioenergetics of Th17 effector cells generated in vivo. These cells depend on oxidative phosphorylation (OXPHOS) for energy and cytokine production. Mechanistically, the essential role of OXPHOS in Th17 cells results from their limited capacity to increase glycolysis in response to metabolic stresses. This metabolic program is observed in mouse and human Th17 cells, including those isolated from Crohn disease patients, and it is linked to disease, as inhibiting OXPHOS reduces the severity of murine colitis and psoriasis. These studies highlight the importance of analyzing metabolism in effector lymphocytes within in vivo inflammatory contexts and suggest a therapeutic role for manipulating OXPHOS in Th17-driven diseases.


Assuntos
Diferenciação Celular/imunologia , Colite/imunologia , Ativação Linfocitária/imunologia , Fosforilação Oxidativa , Células Th17/imunologia , Animais , Separação Celular , Modelos Animais de Doenças , Perfilação da Expressão Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Análise de Sequência com Séries de Oligonucleotídeos , Reação em Cadeia da Polimerase em Tempo Real , Transcriptoma
19.
Oncoimmunology ; 5(12): e1254854, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28123897

RESUMO

RORγt is the key transcription factor controlling the development and function of CD4+ Th17 and CD8+ Tc17 cells. Across a range of human tumors, about 15% of the CD4+ T cell fraction in tumor-infiltrating lymphocytes are RORγ+ cells. To evaluate the role of RORγ in antitumor immunity, we have identified synthetic, small molecule agonists that selectively activate RORγ to a greater extent than the endogenous agonist desmosterol. These RORγ agonists enhance effector function of Type 17 cells by increasing the production of cytokines/chemokines such as IL-17A and GM-CSF, augmenting expression of co-stimulatory receptors like CD137, CD226, and improving survival and cytotoxic activity. RORγ agonists also attenuate immunosuppressive mechanisms by curtailing Treg formation, diminishing CD39 and CD73 expression, and decreasing levels of co-inhibitory receptors including PD-1 and TIGIT on tumor-reactive lymphocytes. The effects of RORγ agonists were not observed in RORγ-/- T cells, underscoring the selective on-target activity of the compounds. In vitro treatment of tumor-specific T cells with RORγ agonists, followed by adoptive transfer to tumor-bearing mice is highly effective at controlling tumor growth while improving T cell survival and maintaining enhanced IL-17A and reduced PD-1 in vivo. The in vitro effects of RORγ agonists translate into single agent, immune system-dependent, antitumor efficacy when compounds are administered orally in syngeneic tumor models. RORγ agonists integrate multiple antitumor mechanisms into a single therapeutic that both increases immune activation and decreases immune suppression resulting in robust inhibition of tumor growth. Thus, RORγ agonists represent a novel immunotherapy approach for cancer.

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