Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Plants (Basel) ; 13(5)2024 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-38475433

RESUMO

As one of the most prominent gene families, R2R3-MYB transcription factors significantly regulate biochemical and physiological processes under salt stress. However, in Sophora alopecuroides, a perennial herb known for its exceptional saline alkali resistance, the comprehensive identification and characterization of SaR2R3-MYB genes and their potential functions in response to salt stress have yet to be determined. We investigated the expression profiles and biological functions of SaR2R3-MYB transcription factors in response to salt stress, utilizing a transcriptome-wide mining method. Our analysis identified 28 SaR2R3-MYB transcription factors, all sharing a highly conserved R2R3 domain, which were further divided into 28 subgroups through phylogenetic analysis. Some SaR2R3-MYB transcription factors showed induction under salt stress, with SaR2R3-MYB15 emerging as a potential regulator based on analysis of the protein-protein interaction network. Validation revealed the transcriptional activity and nuclear localization of SaR2R3-MYB15. Remarkably, overexpression of SaR2R3-MYB15 in transgenic plants could increase the activity of antioxidant enzymes and the accumulation of proline but decrease the content of malondialdehyde (MDA), compared with wild-type plants. Moreover, several salt stress-related genes showed higher expression levels in transgenic plants, implying their potential to enhance salt tolerance. Our findings shed light on the role of SaR2R3-MYB genes in salt tolerance in S. alopecuroides.

3.
Nat Commun ; 15(1): 1658, 2024 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-38395887

RESUMO

Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention, yet their origin remains a topic of debate. The discovery of ScV6Sn6, a bilayer kagome metal featuring an intriguing [Formula: see text] CDW order, offers a novel platform to explore the underlying mechanism behind the unconventional CDW. Here, we combine high-resolution angle-resolved photoemission spectroscopy, Raman scattering and density functional theory to investigate the electronic structure and phonon modes of ScV6Sn6. We identify topologically nontrivial surface states and multiple van Hove singularities (VHSs) in the vicinity of the Fermi level, with one VHS aligning with the in-plane component of the CDW vector near the [Formula: see text] point. Additionally, Raman measurements indicate a strong electron-phonon coupling, as evidenced by a two-phonon mode and new emergent modes. Our findings highlight the fundamental role of lattice degrees of freedom in promoting the CDW in ScV6Sn6.

4.
Adv Sci (Weinh) ; 10(30): e2303944, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37635198

RESUMO

Neuromorphic vision based on photonic synapses has the ability to mimic sensitivity, adaptivity, and sophistication of bio-visual systems. Significant advances in artificial photosynapses are achieved recently. However, conventional photosyanptic devices normally employ opaque metal conductors and vertical device configuration, performing a limited hemispherical field of view. Here, a transparent planar photonic synapse (TPPS) is presented that offers dual-side photosensitive capability for nearly panoramic neuromorphic vision. The TPPS consisting of all two dimensional (2D) carbon-based derivatives exhibits ultra-broadband photodetecting (365-970 nm) and ≈360° omnidirectional viewing angle. With its intrinsic persistent photoconductivity effect, the detector possesses bio-synaptic behaviors such as short/long-term memory, experience learning, light adaptation, and a 171% pair-pulse-facilitation index, enabling the synapse array to achieve image recognition enhancement (92%) and moving object detection.

5.
Eur Heart J ; 44(18): 1622-1632, 2023 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-36893798

RESUMO

AIMS: The available literature on morbidity risk of cardiovascular diseases associated with ambient ozone pollution is still limited. This study examined the potential acute effects of exposure to ambient ozone pollution on hospital admissions of cardiovascular events in China. METHODS AND RESULTS: A two-stage multi-city time-series study approach was used to explore the associations of exposure to ambient ozone with daily hospital admissions (n = 6 444 441) for cardiovascular events in 70 Chinese cities of prefecture-level or above during 2015-17. A 10 µg/m3 increment in 2-day average daily 8 h maximum ozone concentrations was associated with admission risk increases of 0.46% [95% confidence interval (CI): 0.28%, 0.64%] in coronary heart disease, 0.45% (95% CI: 0.13%, 0.77%) in angina pectoris, 0.75% (95% CI: 0.38%, 1.13%) in acute myocardial infarction (AMI), 0.70% (95% CI: 0.41%, 1.00%) in acute coronary syndrome, 0.50% (95% CI: 0.24%, 0.77%) in heart failure, 0.40% (95% CI: 0.23%, 0.58%) in stroke and 0.41% (95% CI: 0.22%, 0.60%) in ischemic stroke, respectively. The excess admission risks for these cardiovascular events associated with high ozone pollution days (with 2-day average 8-h maximum concentrations ≥100 µg/m3 vs. < 70 µg/m3) ranged from 3.38% (95% CI: 1.73%, 5.06%) for stroke to 6.52% (95% CI: 2.92%, 10.24%) for AMI. CONCLUSION: Ambient ozone was associated with increased hospital admission risk for cardiovascular events. Greater admission risks for cardiovascular events were observed under high ozone pollution days. These results provide evidence for the harmful cardiovascular effects of ambient ozone and call for special attention on the control of high ozone pollution.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Infarto do Miocárdio , Ozônio , Acidente Vascular Cerebral , Humanos , Ozônio/efeitos adversos , Ozônio/análise , Poluição do Ar/efeitos adversos , Poluição do Ar/análise , Poluentes Atmosféricos/efeitos adversos , Poluentes Atmosféricos/análise , Material Particulado/análise , Infarto do Miocárdio/epidemiologia , Acidente Vascular Cerebral/epidemiologia , Hospitais
6.
Nat Commun ; 13(1): 4996, 2022 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-36008407

RESUMO

Neuromorphic electronics, which use artificial photosensitive synapses, can emulate biological nervous systems with in-memory sensing and computing abilities. Benefiting from multiple intra/interactions and strong light-matter coupling, two-dimensional heterostructures are promising synaptic materials for photonic synapses. Two primary strategies, including chemical vapor deposition and physical stacking, have been developed for layered heterostructures, but large-scale growth control over wet-chemical synthesis with comprehensive efficiency remains elusive. Here we demonstrate an interfacial coassembly heterobilayer films from perylene and graphene oxide (GO) precursors, which are spontaneously formed at the interface, with uniform bilayer structure of single-crystal perylene and well-stacked GO over centimeters in size. The planar heterostructure device exhibits an ultrahigh specific detectivity of 3.1 × 1013 Jones and ultralow energy consumption of 10-9 W as well as broadband photoperception from 365 to 1550 nm. Moreover, the device shows outstanding photonic synaptic behaviors with a paired-pulse facilitation (PPF) index of 214% in neuroplasticity, the heterosynapse array has the capability of information reinforcement learning and recognition.


Assuntos
Grafite , Perileno , Plasticidade Neuronal , Sinapses/fisiologia
7.
Small ; 17(34): e2102060, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34288427

RESUMO

Inspired by the 2D bilayer lipid membranes in nature, a unique supramolecular "push-pull" synergetic strategy toward self-assembled 2D organic crystals (2DOCs) is proposed in this work, which can effectively suppress the interlayer 3D stacking while maintaining the assembly of the intralayer for 2D growth. For this purpose, a model molecule PF-Py consisting of a planar supramolecular "attractor" and a nonplanar steric "repellor" is designed for the solution self-assembly process. Well-defined 2DOCs including crystal nanosheets and millimeter-sized crystal films with layered amphiphile-like packing are obtained, which is analogical to the cell membranes of living organisms. Thanks to the special packing mode, the 2DOCs have fascinating integrated photoelectric property, with high mobility of 7.8 × 10-2 cm2 V-1 s-1 , high crystalline state photoluminescence quantum yield of 55%, and superior deep-blue laser characteristics with a low threshold of 5.51 µJ cm-2 . This supramolecular synergetic strategy advances the design of 2D organic semiconductor crystals for high performance optoelectronics.


Assuntos
Semicondutores
8.
Nanoscale ; 12(18): 9964-9968, 2020 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-32373816

RESUMO

Two spirocyclic aromatic hydrocarbon derivatives were prepared to clarify the molecular geometry effects on the regulation of the crystalline morphologies and photophysical behaviors of organic nanocrystals. Due to the different structural symmetry of a spiro-center, distinguishing nanocrystal morphologies with unique crystallization-enhanced/quenched emission was achieved.

9.
Nanoscale ; 11(12): 5158-5162, 2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30865748

RESUMO

Three pyrene-based spirocyclic aromatic hydrocarbons (Py-SAHs) were prepared to clarify the roles of molecular segments in regulating the morphologies and photophysical properties of organic microcrystals. Due to the different supramolecular steric hindrance (SSH) effect between bulky groups and pyrene rings, distinct nanocrystal morphologies with unique photoluminescence properties were realized.

10.
Adv Sci (Weinh) ; 5(12): 1800747, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30581695

RESUMO

Three diazafluorene derivatives triphenylamine (TPA)(PDAF) n (n = 1, 2, 3) serving as small molecular elements are designed and synthesized via concentrated sulfuric acid mediated Friedel-Crafts reaction. With highly nonplanar topological configuration, TPA(PDAF)3 shows weaker intermolecular interaction in the solid states and thus exhibits single nanomolecular behavior, which is crucial for charge stored and retained in an organic field-effect transistor (OFET) memory device. Furthermore, diazafluorene derivatives possess a completely separate highest occupied molecular orbital/lowest unoccupied molecular orbital, which offers ideal hole and electron trapping sites. As charge storage elements, triphenylamine groups provide the hole trapping sites, while diazafluorene units provide the electron trapping sites and act as a hole blocking group to restrain the leakage of stored holes trapped in triphenylamine. The pentacene-based OFET memory device with solution-processing TPA(PDAF)3 shows a good hole-trapping ability, high hole trapping density (4.55 × 1012 cm-2), fast trapping speed (<20 ms), a large memory window (89 V), and a tunable ambipolar memory behavior. The optimized device shows a large ON/OFF current ratio (2.85 × 107), good charge retention (>104 s), and reliable endurance properties. This study suggests that diazafluorene based donor-acceptor small molecular elements have great promise for high-performance OFET memory.

11.
Proc Natl Acad Sci U S A ; 115(33): 8311-8315, 2018 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-30061416

RESUMO

Anomalous surface states with Fermi arcs are commonly considered to be a fingerprint of Dirac semimetals (DSMs). In contrast to Weyl semimetals, however, Fermi arcs of DSMs are not topologically protected. Using first-principles calculations, we predict that ß-cuprous iodide (ß-CuI) is a peculiar DSM whose surface states form closed Fermi pockets instead of Fermi arcs. In such a fermiological Dirac semimetal, the deformation mechanism from Fermi arcs to Fermi pockets stems from a large cubic term preserving all crystal symmetries and from the small energy difference between the surface and bulk Dirac points. The cubic term in ß-CuI, usually negligible in prototypical DSMs, becomes relevant because of the particular crystal structure. As such, we establish a concrete material example manifesting the lack of topological protection for surface Fermi arcs in DSMs.

12.
Nanoscale ; 10(28): 13310-13314, 2018 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-29987277

RESUMO

Three isomers were prepared by covalently grafting carbazole (Cz) onto spiro[fluorene-9,9'-xanthene] (SFX) at different positions. Due to the complicated and variable roles of molecular segments, an evolution of the corresponding molecular packing mode was realized, accompanied by the change of nanocrystal morphology and photoluminescence properties.

13.
Small ; 14(6)2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29235730

RESUMO

Rational molecular design for the organic nanocrystal morphology still remains a challenge due to the structural diversity and complicated weak intermolecular interactions. In this work, a typical attractor-repulsor molecule N,N-diphenyl-4-(9-phenyl-fluoren-9-yl) phenylamine (TPA-PF) is designed to explore a general assembly strategy for 2D nanocrystals. Via an interdigital lipid bilayer-like (ILB) molecular packing mode, large-sized lamellar 2D nanosheets are obtained with a length:width:thickness ratio as ≈2500:1000:1. The d-spacing of the largest (001) plane is 1.32 nm, which equals to the thickness of a single interdigital stacking layer. The synergetic effect of the attractive supramolecular segment (TPA) and the repulsive bulky group (PF) is supposed to be the critical factor for the ILB packing that leads to the 2D structures. The attractor-repulsor molecule design is expected to be an effective strategy for the growth of 2D nanocrystals based on small organic molecules.

14.
J Dairy Sci ; 99(10): 7881-7885, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27423950

RESUMO

Powdered infant formula is considered as the main transmission vehicle for Cronobacter sakazakii infections including meningitis, septicemia, and necrotizing enterocolitis. The effects of high-pressure processing treatment on inactivation of C. sakazakii ranging from 100 to 400 MPa for 3.0, 5.0, and 7.0 min in whole milk and skim milk were studied. Significant differences in inactivation of C. sakazakii were observed in milk samples under different pressures for 3 to 7 min compared with untreated samples, and C. sakazakii was not detected after 400 MPa for 3 min. The lethality rates of C. sakazakii cells in whole and skim milk with an initial level of 10(4) cfu/mL after 100 and 200 MPa treatments were not significantly different, but relatively higher lethality rates were found in whole milk after 300 MPa treatment than in skim milk. Finally, the scanning electron micrographs indicated that cellular envelope and intracellular damage of C. sakazakii cells were apparent after 300 and 400 MPa for 5.0 min compared with the untreated cells, and a progressive increase of injured cells with increased pressure treatment was found. It was concluded that C. sakazakii was sensitive to high-pressure processing treatment and that high-pressure processing treatment with 400 MPa for 3.0 min can be used to control C. sakazakii contamination in milk samples.


Assuntos
Cronobacter sakazakii/efeitos dos fármacos , Leite , Animais , Microbiologia de Alimentos , Fórmulas Infantis , Pressão
15.
Ann Surg ; 259(6): 1080-5, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24374518

RESUMO

OBJECTIVE: The aim of this study was to compare the postoperative chronic pain and other postoperative complications after the use of the self-gripping Progrip meshes and the application of conventional suture-fixed Lichtenstein procedure. BACKGROUND: Chronic pain after inguinal hernia repair is a complex problem. Many efforts have been put to reduce the postoperative chronic pain after open inguinal hernia repair, and the results are conflicting. METHODS: A systematic literature review was undertaken to identify studies comparing the outcomes of open inguinal hernia repair with self-gripping Progrip meshes and the conventional Lichtenstein technique. RESULTS: The present meta-analysis pooled the effects of outcomes of total 1353 patients enrolled into 5 randomized controlled trials and 2 prospective comparative studies. Statistically, there was no difference in the incidence of chronic pain [odds ratio = 0.74, 95% confidence interval (CI) (0.51-1.08)]. And there was no statistical difference in the incidence of acute postoperative pain [odds ratio = 1.32, 95% CI (0.68-2.55)], hematoma or seroma [odds ratio = 0.89, 95% CI (0. 56-1.41)], wound infection [risk difference = -0.01, 95% CI (-0.02 to 0.01)], and recurrence [risk difference = 0.00, 95% CI (-0.01 to 0.01)]. The self-gripping mesh group was associated with a shorter operating time (1-9 minutes). CONCLUSIONS: When the self-gripping mesh compared with the conventional suture fixed Lichtenstein technique, while there was a difference in operative time, there were no differences in pain (chronic or acute) or other complications.


Assuntos
Hérnia Inguinal/cirurgia , Herniorrafia/métodos , Complicações Pós-Operatórias , Telas Cirúrgicas , Técnicas de Sutura , Desenho de Equipamento , Saúde Global , Herniorrafia/efeitos adversos , Humanos , Incidência , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/prevenção & controle
16.
Am J Surg ; 207(4): 602-12, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24139670

RESUMO

BACKGROUND: The aim of this meta-analysis was to compare the effectiveness and complications of the laparoscopic procedure and open techniques in the treatment of recurrent inguinal hernias. METHODS: The electronic databases MEDLINE, Embase, PubMed, and Cochrane Library were used to search for randomized controlled trials and comparative trials about laparoscopic and open procedures on recurrent inguinal hernia repair from January 1999 to September 2012. RESULTS: A total of 1,311 patients enrolled into 6 randomized controlled trials and 5 comparative studies were included in this meta-analysis. Our pooled data showed that the laparoscopic procedure was associated with a lower incidence of wound infection and a shorter sick leave. However, there were no differences in other complication rates or the operation time between the 2 methods. CONCLUSIONS: The laparoscopic technique in the treatment of recurrent inguinal hernia was associated with less wound infection rates and a faster recovery to normal activity, whereas other complication rates, including the re-recurrence rate, were comparable between these 2 methods. Laparoscopic and open procedures could be performed with equal operation time.


Assuntos
Hérnia Inguinal/cirurgia , Herniorrafia/métodos , Laparoscopia/métodos , Laparotomia/métodos , Humanos , Recidiva , Resultado do Tratamento
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA