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1.
Nature ; 537(7622): 629-633, 2016 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-27602511

RESUMO

Increasing grain yield is a long-term goal in crop breeding to meet the demand for global food security. Heterosis, when a hybrid shows higher performance for a trait than both parents, offers an important strategy for crop breeding. To examine the genetic basis of heterosis for yield in rice, here we generate, sequence and record the phenotypes of 10,074 F2 lines from 17 representative hybrid rice crosses. We classify modern hybrid rice varieties into three groups, representing different hybrid breeding systems. Although we do not find any heterosis-associated loci shared across all lines, within each group, a small number of genomic loci from female parents explain a large proportion of the yield advantage of hybrids over their male parents. For some of these loci, we find support for partial dominance of heterozygous locus for yield-related traits and better-parent heterosis for overall performance when all of the grain-yield traits are considered together. These results inform on the genomic architecture of heterosis and rice hybrid breeding.


Assuntos
Genes de Plantas/genética , Genoma de Planta , Vigor Híbrido/genética , Oryza/crescimento & desenvolvimento , Oryza/genética , Locos de Características Quantitativas/genética , Alelos , Cruzamentos Genéticos , Genes Dominantes , Genômica , Genótipo , Heterozigoto , Hibridização Genética , Oryza/anatomia & histologia , Fenótipo , Melhoramento Vegetal , Análise de Sequência de DNA
2.
Bioorg Chem ; 116: 105337, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34521046

RESUMO

A phytochemical investigation on the alkaloids from water-soluble part of Sophora alopecuroides led to obtain forty matrine-type alkaloids (1-40) including eighteen new ones (1-18), which covers almost all positions of the oxygen substitution in matrine-type structure. Notably, eight compounds (1-8) belong to rare bis-amide matrine-type alkaloid. The new structures were determined based on extensive spectroscopic data, electronic circular dichroism (ECD) calculations, and six instances, verified by X-ray crystallography. Most of isolates showed anti-neuroinflammatory activities based on the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in BV2 microglia cells. Especially, compound 39 can suppress those two mediator secretions in a dose-dependent manner with IC50 values of 21.6 ± 0.5 and 16.7 ± 0.8 µM, respectively. Further mechanistic study revealed that 39 suppressed the phosphorylation of IκBα and p65 subunit to regulate the NF-κB signaling pathway.


Assuntos
Alcaloides/farmacologia , Anti-Inflamatórios/farmacologia , Quinolizinas/farmacologia , Sophora/química , Alcaloides/química , Alcaloides/isolamento & purificação , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Linhagem Celular , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Interleucina-6/antagonistas & inibidores , Interleucina-6/metabolismo , Camundongos , Modelos Moleculares , Estrutura Molecular , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Quinolizinas/química , Quinolizinas/isolamento & purificação , Sementes/química , Transdução de Sinais/efeitos dos fármacos , Solubilidade , Relação Estrutura-Atividade , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Fator de Necrose Tumoral alfa/metabolismo , Água/química , Matrinas
3.
J Asian Nat Prod Res ; 23(4): 399-406, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32319324

RESUMO

A new sesquiterpene pyridine alkaloid (1), along with four known compounds (2-5), were isolated from the stems and leaves of Euonymus fortunei. The new structure was determined by extensive spectroscopic analyses (IR, UV, NMR, HRESIMS and ECD). In addition, compound 3 showed a stronger anti-respiratory syncytial virus (RSV) activity with an IC50 value of 1.20 ± 0.10 µM than the positive control ribavirin with an IC50 value of 5.62 ± 0.49 µM.[Formula: see text].


Assuntos
Alcaloides , Euonymus , Sesquiterpenos , Estrutura Molecular , Folhas de Planta , Piridinas
4.
Antimicrob Agents Chemother ; 64(10)2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32718963

RESUMO

Phosphoinositide-3 kinase signaling modulates many cellular processes, including cell survival, proliferation, differentiation, and apoptosis. Currently, it is known that the establishment of respiratory syncytial virus infection requires phosphoinositide-3 kinase signaling. However, the regulatory pattern of phosphoinositide-3 kinase signaling or its corresponding molecular mechanism during respiratory syncytial virus entry remains unclear. Here, the involvement of phosphoinositide-3 kinase signaling in respiratory syncytial virus entry was studied. PIK-24, a novel compound designed with phosphoinositide-3 kinase as a target, had potent anti-respiratory syncytial virus activity both in vitro and in vivo PIK-24 significantly reduced viral entry into the host cell through blocking the late stage of the fusion process. In a mouse model, PIK-24 effectively reduced the viral load and alleviated inflammation in lung tissue. Subsequent studies on the antiviral mechanism of PIK-24 revealed that viral entry was accompanied by phosphoinositide-3 kinase signaling activation, downstream RhoA and cofilin upregulation, and actin cytoskeleton rearrangement. PIK-24 treatment significantly reversed all these effects. The disruption of actin cytoskeleton dynamics or the modulation of phosphoinositide-3 kinase activity by knockdown also affected viral entry efficacy. Altogether, it is reasonable to conclude that the antiviral activity of PIK-24 depends on the phosphoinositide-3 kinase signaling and that the use of phosphoinositide-3 kinase signaling to regulate actin cytoskeleton rearrangement plays a key role in respiratory syncytial virus entry.


Assuntos
Infecções por Vírus Respiratório Sincicial , Vírus Sincicial Respiratório Humano , Animais , Camundongos , Fosfatidilinositóis , Infecções por Vírus Respiratório Sincicial/tratamento farmacológico , Transdução de Sinais , Internalização do Vírus
5.
Biol Reprod ; 100(1): 292-299, 2019 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-30137227

RESUMO

This study aimed to investigate whether cadmium induces ovarian granulosa cell damage by activating protein kinase R-like endoplasmic reticulum kinase (PERK)-eIF2α-ATF4 through endoplasmic reticulum (ER) stress and to elucidate the underlying regulation mechanism. Two models of cadmium exposure were established. In one model, ovarian granulosa cells isolated from 21-day-old female Sprague Dawley rats were cultured in vitro for 36 h and exposed to CdCl2 (0, 5, 10, and 20 µM), and in another model, a human ovarian granulosa tumor cell line (COV434) was used to construct the binding immunoglobulin protein (BIP)-knockdown cell line sh-BIP and exposed to 0 and 20 µM CdCl2. After exposure to cadmium for 12 h, the expression mRNA and protein levels of BIP, p-PERK, and p-eIF2α were determined in the two models. miRNAs related to BIP were also detected in granulosa cells after cadmium exposure. We found that mRNA and protein levels of all factors were upregulated in each cadmium-dose group, except for BIP mRNA expression in the 5 µM Cd group. The BIP gene was knocked down in COV434 cells before exposure to cadmium. All factors were upregulated in COV434 cells exposed to Cd, and the expression of the p-eIF2α protein was downregulated in sh-BIP cells exposed to Cd. In addition, no differences in BIP-related miRNAs were detected in cadmium-exposed rat ovarian granulosa cells versus the control group. Cadmium induces ovarian granulosa cell damage by inducing ER stress.


Assuntos
Cádmio/toxicidade , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Células da Granulosa/efeitos dos fármacos , Ovário/efeitos dos fármacos , Fator 4 Ativador da Transcrição/genética , Fator 4 Ativador da Transcrição/metabolismo , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Estresse do Retículo Endoplasmático/fisiologia , Fator de Iniciação 2 em Eucariotos/genética , Fator de Iniciação 2 em Eucariotos/metabolismo , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Células da Granulosa/metabolismo , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/metabolismo , Humanos , Ovário/citologia , Ovário/metabolismo , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Testes de Toxicidade , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismo
7.
Chem Biodivers ; 15(5): e18000080, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29624846

RESUMO

Seven new acetophenone derivatives (acroliones A - G, 1 - 7) and three known ones (8 - 10) were isolated from the leaves of Acronychia oligophlebia. Their structures were elucidated based on extensive spectroscopic analyses (IR, UV, HR-ESI-MS, 1D- and 2D-NMR), X-ray diffraction and comparison with literature data. The anti-inflammatory and antioxidant activities of all isolates were evaluated.


Assuntos
Acetofenonas/farmacologia , Anti-Inflamatórios não Esteroides/farmacologia , Antioxidantes/farmacologia , Compostos de Bifenilo/antagonistas & inibidores , Óxido Nítrico/antagonistas & inibidores , Picratos/antagonistas & inibidores , Rutaceae/química , Acetofenonas/química , Acetofenonas/isolamento & purificação , Animais , Anti-Inflamatórios não Esteroides/química , Anti-Inflamatórios não Esteroides/isolamento & purificação , Antioxidantes/química , Antioxidantes/isolamento & purificação , Cristalografia por Raios X , Camundongos , Modelos Moleculares , Estrutura Molecular , Óxido Nítrico/biossíntese , Folhas de Planta/química , Células RAW 264.7
8.
Tumour Biol ; 39(6): 1010428317707375, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28639906

RESUMO

The Platelet to lymphocyte ratio (PLR) has been reported to predict prognosis of patients with hepatocellular carcinoma (HCC). This study examined the prognostic potential of stratified PLR for HCC patients undergoing curative liver resection. Medical records were retrospectively analyzed for 778 HCC patients undergoing curative liver resection at the Affiliated Tumor Hospital of Guangxi Medical University and the First People's Hospital of Changde between April 2010 and October 2013. Patients were stratified based on quintile analysis of their preoperative PLR, and patients in different quintiles were analyzed for overall survival (OS) and disease-free survival (DFS) using Kaplan-Meier analysis. Independent predictors of death or recurrence were explored using multivariable Cox proportional hazard regression. Higher PLR quintiles were significantly associated with poorer overall survival (p < 0.001). Multivariate analysis showed PLR to be an independent risk factor for OS (p = 0.003). Patients in PLR quintile 5 had lower overall survival than in quintile 1 (hazard ratio (HR) = 2.780, 95% confidence interval (CI): 1.769-4.367, p < 0.001). Although patients in PLR quintile 5 had significantly lower disease-free survival (DFS) than in quintile 1 (HR = 1.534, 95% CI: 1.112-2.117, p = 0.009), this association was not significant after multivariable adjustment (p = 0.220). Subgroup analysis also showed that PLR quintiles were significantly associated with poor OS in patients positive for HBsAg or with cirrhosis (both p < 0.001). Similar results were obtained when PLR was analyzed as a dichotomous variable with cut-off values of 110 and 115. Elevated preoperative PLR may be independently associated with poor OS and DFS in HCC patients following curative resection.


Assuntos
Biomarcadores Tumorais/sangue , Plaquetas , Carcinoma Hepatocelular/sangue , Neoplasias Hepáticas/sangue , Linfócitos , Adulto , Idoso , Carcinoma Hepatocelular/patologia , Intervalo Livre de Doença , Feminino , Humanos , Estimativa de Kaplan-Meier , Neoplasias Hepáticas/patologia , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/sangue , Recidiva Local de Neoplasia/patologia , Contagem de Plaquetas , Prognóstico
9.
Tumour Biol ; 39(3): 1010428317695944, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28351330

RESUMO

The aspartate aminotransferase-to-platelet ratio index has been reported to predict prognosis of patients with hepatocellular carcinoma. This study examined the prognostic potential of stratified aspartate aminotransferase-to-platelet ratio index for hepatocellular carcinoma patients undergoing curative liver resection. A total of 661 hepatocellular carcinoma patients were retrieved and the associations between aspartate aminotransferase-to-platelet ratio index and clinicopathological variables and survivals (overall survival and disease-free survival) were analyzed. Higher aspartate aminotransferase-to-platelet ratio index quartiles were significantly associated with poorer overall survival (p = 0.002) and disease-free survival (p = 0.001). Multivariate analysis showed aspartate aminotransferase-to-platelet ratio index to be an independent risk factor for overall survival (p = 0.018) and disease-free survival (p = 0.01). Patients in the highest aspartate aminotransferase-to-platelet ratio index quartile were at 44% greater risk of death than patients in the first quartile (hazard ratio = 1.445, 95% confidence interval = 1.081 - 1.931, p = 0.013), as well as 49% greater risk of recurrence (hazard ratio = 1.49, 95% confidence interval = 1.112-1.998, p = 0.008). Subgroup analysis also showed aspartate aminotransferase-to-platelet ratio index to be an independent predictor of poor overall survival and disease-free survival in patients positive for hepatitis B surface antigen or with cirrhosis (both p < 0.05). Similar results were obtained when aspartate aminotransferase-to-platelet ratio index was analyzed as a dichotomous variable with cutoff values of 0.25 and 0.62. Elevated preoperative aspartate aminotransferase-to-platelet ratio index may be independently associated with poor overall survival and disease-free survival in hepatocellular carcinoma patients following curative resection.


Assuntos
Aspartato Aminotransferases/sangue , Plaquetas/metabolismo , Carcinoma Hepatocelular/sangue , Neoplasias Hepáticas/sangue , Adulto , Idoso , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/cirurgia , Intervalo Livre de Doença , Feminino , Humanos , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/cirurgia , Masculino , Pessoa de Meia-Idade , Período Pré-Operatório , Prognóstico , Resultado do Tratamento
10.
Planta Med ; 83(1-02): 111-116, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27405107

RESUMO

Five new diterpenoid alkaloids, ajacisines A-E (1-5), were isolated from Delphinium ajacis, along with seven known alkaloids (6-12). On the basis of their spectral data (IR, UV, HR-ESI-MS, 1D and 2D NMR) and chemical properties, the structures of compounds 1-12 were identified. All isolated compounds were evaluated for their in vitro antiviral activities against respiratory syncytial virus, and compounds 3-5 and 8 exhibited moderate to weak effects with IC50 values of 75.2 ± 1.1, 35.1 ± 0.6, 10.1 ± 0.3, and 50.2 ± 0.5 µM, respectively.


Assuntos
Alcaloides/farmacologia , Antivirais/farmacologia , Delphinium/química , Diterpenos/farmacologia , Estrutura Molecular , Vírus Sincicial Respiratório Humano/efeitos dos fármacos , Alcaloides/química , Alcaloides/isolamento & purificação , Antivirais/química , Antivirais/isolamento & purificação , Linhagem Celular Tumoral , Diterpenos/química , Diterpenos/isolamento & purificação , Humanos , Espectroscopia de Ressonância Magnética , Raízes de Plantas/química , Caules de Planta/química
11.
Chem Biodivers ; 14(1)2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27584719

RESUMO

Six new pentacyclic triterpenoids were isolated from the fruit of Camptotheca acuminata. The chemical structures of the new compounds were elucidated by extensive spectroscopic analysis including HR-ESI-MS, IR, UV, 1D- and 2D-NMR. Moreover, the antibacterial activities of compounds 1, 2, 4, 5, and 6 were evaluated against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Dickeya zeae. All these tested compounds showed moderate antibacterial activity against Bacillus subtilis and Dickeya zeae.


Assuntos
Antibacterianos/isolamento & purificação , Camptotheca/química , Triterpenos Pentacíclicos/isolamento & purificação , Antibacterianos/química , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Frutas/química , Estrutura Molecular , Triterpenos Pentacíclicos/química , Triterpenos Pentacíclicos/farmacologia
12.
Chem Biodivers ; 14(7)2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28323385

RESUMO

Six new acylphloroglucinols (1 - 6) were isolated from Dryopteris championii. Their structures were established on the basis of extensive analysis of spectroscopic data and comparison with reported data. The antibacterial activities of the isolates were evaluated against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Dickeya zeae.


Assuntos
Antibacterianos/isolamento & purificação , Dryopteris/química , Floroglucinol/isolamento & purificação , Antibacterianos/química , Bactérias/efeitos dos fármacos , Estrutura Molecular , Floroglucinol/química , Floroglucinol/farmacologia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Análise Espectral
13.
J Org Chem ; 81(19): 9443-9448, 2016 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-27583635

RESUMO

Three novel sesquiterpenoid-based meroterpenoids, drychampones A-C (1-3, respectively), were isolated from Dryopteris championii. Compounds 1 and 3 possessed a novel carbon skeleton which was constructed by an 11/6/6 ring system coupled with a pyronone moiety, and 1-3 were three racemates. Their structures and absolute configurations were elucidated by NMR, MS, and computational methods. The hypothetical biosynthetic pathways of these meroterpenoids and their antibacterial activities were also discussed.


Assuntos
Dryopteris/química , Sesquiterpenos/isolamento & purificação , Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Dicroísmo Circular , Escherichia coli/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Espectroscopia de Prótons por Ressonância Magnética , Sesquiterpenos/química , Sesquiterpenos/farmacologia , Espectrometria de Massas por Ionização por Electrospray , Staphylococcus aureus/efeitos dos fármacos
14.
Bioorg Med Chem Lett ; 26(19): 4687-4691, 2016 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-27575472

RESUMO

Nine new labdane diterpenoids (1-9) were isolated from the aerial parts of Croton laui, along with eight known analogues (10-17). Their structures were identified on the basis of the spectral data (IR, UV, HRESIMS, 1D and 2D NMR), and the structure of 8 was confirmed by single crystal X-ray diffraction analyses. In addition, compounds 1, 4, 7, 8, and 14 showed weak anti-inflammatory activities in LPS-stimulated RAW 264.7 cells.


Assuntos
Anti-Inflamatórios/farmacologia , Croton/química , Diterpenos/isolamento & purificação , Animais , Linhagem Celular , Diterpenos/farmacologia , Camundongos , Análise Espectral/métodos
15.
Zhongguo Yi Liao Qi Xie Za Zhi ; 40(3): 212-3, 2016 May.
Artigo em Zh | MEDLINE | ID: mdl-29775263

RESUMO

Fixed dental prostheses with ceramic were widely used in people for their good strength and aesthetics. As the defect of the products wil lead to failure in prostheses, good quality is essential in daily use. Accroding to analysis the date of the fixed dental prostheses in porosity test, and link with the shape and location of the pores, we have the result that the reject ratio of the fixed dental prostheses in porosity is exceed 40%, the main unqualified category is that big pores with diameter greater than 150 mm exist in ceramic. This may be introduced by the mechanic in the process of brush porcelain by mixing in bubbles or impurities.


Assuntos
Falha de Restauração Dentária , Prótese Parcial Fixa , Cerâmica , Porcelana Dentária , Porosidade
16.
Zhong Yao Cai ; 38(4): 754-7, 2015 Apr.
Artigo em Zh | MEDLINE | ID: mdl-26672341

RESUMO

OBJECTIVE: To investigate the chemical constituents from the branches and leaves of Syzygium samarangense. METHODS: The dried branches and leaves of Syzygium samarangense were powdered and extracted with 95% ethanol, then partitioned with petroleum ether, chloroform and ethyl acetate. The chloroform fraction was subjected to silica gel, Sephdex L-20 and preparative HPLC. The structures were identified by physicochemical properties and spectral data. RESULTS: 14 compounds were respectively isolated and identified as ursolic aldehyde(1), betulin(2), betulinic aldehyde(3), betulinic acid(4), lupeol(5), ß-sitosterol(6), 5, 7-dihydroxy-6-methylflavanone(7), 2', 4'-dihydroxy-6'-methoxy-3'-methyldihydrochalcone (8), 2', 4'-dihydroxy-6'-methoxy-3'-methylchalcone (9), 5, 7-dihydroxy-6, 8-dimethylflavanone (10), 5, 7-dihydroxyflavanone (11), 2', 4'-dihydroxy-6'-methoxy-3', 5'-dimethyldihydrochalcone (12), 2'-hydroxy-4', 6'-dimethoxy-3'-methylchalcone(13) and p-hydroxyb6nzaldehyde(14). CONCLUSION: Compounds 1 - 4 and 14 are isolated from this plant for the first time.


Assuntos
Compostos Fitoquímicos/química , Extratos Vegetais/química , Folhas de Planta/química , Syzygium/química , Triterpenos Pentacíclicos , Compostos Fitoquímicos/isolamento & purificação , Sitosteroides , Triterpenos , Ácido Betulínico
17.
Acta Crystallogr Sect E Struct Rep Online ; 70(Pt 12): o1242-3, 2014 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-25553022

RESUMO

The title compound [systematic name: 3ß-hy-droxy-lup-20(29)-en-28-oic acid methanol monosolvate], C30H48O3·CH3OH, is a solvent pseudopolymorph of a naturally occurring plant-derived lupane-type penta-cyclic triterpenoid, which was isolated from the traditional Chinese medicinal plant Syzygium jambos (L.) Alston. The dihedral angle between the planes of the carb-oxy-lic acid group and the olefinic group is 12.17 (18)°. The A/B, B/C, C/D and D/E ring junctions are all trans-fused. In the crystal, O-H⋯O hydrogen bonds involving the hy-droxy and carb-oxy-lic acid groups and the methanol solvent mol-ecule give rise to a two-dimensional network structure lying parallel to (001).

18.
Artigo em Inglês | MEDLINE | ID: mdl-24427011

RESUMO

In the title compound, [Pb(C20H26O2PS2)2(C5H5N)2], the Pb(II) ion is coordinated by two S,S'-bidentate anions and two pyridine mol-ecules. The PbN2S4 coordination geometry approximates to a penta-gonal bipyramid with one equatorial site vacant. The N atoms occupy the axial sites. One of the pyridine mol-ecules is disordered over two sets of sites in a 0.907 (7):0.093 (7) ratio and one of the tert-butyl groups is disordered over two sets of sites in a 0.534 (6):0.466 (6) ratio. An intra-molecular C-H⋯O inter-action occurs in one of the ligands. In the crystal, pairs of short Pb⋯S contacts [3.4018 (11) Å] generate a centrosymmetric dimeric assembly with the distant S atom lying in the region of the vacant coordination site of the metal atom. No directional packing inter-actions occur.

19.
J Colloid Interface Sci ; 647: 43-51, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37244175

RESUMO

Hexagonal boron nitride (BN) is an attractive filler candidate for thermal interface materials, but the thermal conductivity enhancement is limited by the anisotropic thermal conductivity of BN and disordered thermal pathways in the polymer matrix. Herein, a facile and economic ice template method is proposed, wherein BN modified by tannic acid (BN-TA) directly self-assemble to form vertically aligned nacre-mimetic scaffold without additional binders and post-treatment. The effects of the BN slurry concentration and the ratio of BN/TA on three-dimensional (3D) skeleton morphology are fully investigated. The corresponding polydimethylsiloxane (PDMS) composite via vacuum-impregnation achieves a high through-plane thermal conductivity of 3.8 W/mK at a low filler loading of 18.7 vol%, which is 2433% and 100% higher than that of pristine PDMS and the PDMS composite with randomly distributed BN-TA, respectively. The finite element analysis results theoretically demonstrate the superiority of the highly longitudinally ordered 3D BN-TA skeleton in axial heat transfer. Additionally, 3D BN-TA/PDMS exhibits excellent practical heat dissipation capability, lower thermal expansion coefficient, and enhanced mechanical properties. This strategy offers an anticipated perspective for developing high-performance thermal interface materials to address the thermal challenges of modern electronics.

20.
J Colloid Interface Sci ; 640: 1040-1051, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-36921383

RESUMO

Transition metal selenides (TMSes) with cubic pyrite-type crystal structure have been widely explored as electrocatalysts for oxygen evolution reaction (OER), but the insufficient hydrogen evolution reaction (HER) performance hinders the application of overall water splitting. Herein, we designed and prepared a Mo doped NiSe2-CoSe2 heterostructure aerogel as bifunctional electrocatalyst via facile spontaneous gelation and selenium vapor deposition. The active sites on the heterointerface possessed desirable Gibbs free energy of hydrogen adsorption, leading to better HER performance than single NiSe2 or CoSe2. Moreover, systematically experimental research and density functional theory (DFT) calculations revealed that fine regulated Mo doping improved the electropositivity of heterostructure, promoting the nucleophilic adsorption of water molecule. Benefit from those improvements, the optimal Mo doped NiSe2-CoSe2 aerogel exhibited an extremely low overpotential of 57 mV at the current density of 10 mA·cm-2 for HER with a small Tafel slope value of 38 mV·dec-1. Meanwhile, Mo doping provided higher electron transfer efficiency and better adsorptive property toward reaction intermediate in anodic reaction, resulting in low overpotential of 270 mV at the current density of 100 mA·cm-2 for OER with good electrocatalytic stability. This work provides an anticipated perspective of rational combination of metal doping and heterostructure for advanced electrocatalysts.

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