Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 75
Filtrar
1.
Adv Mater ; : e2402239, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38519452

RESUMO

In this work, a distinctive "metal-ion organic hybrid interface" (MOHI) between polyimide (PI) and calcium niobate (CNO) nanosheets was designed. The metal ions in the MOHI could achieve atomic-level matching not only with the inorganic CNO but also with the PI chains, forming uniform and strong chemical bonds. These results were demonstrated by experiment and theory calculations. Significantly, the MOHI reduced the free volume and introduced deep traps across the filler-matrix interfacial area, thus suppressing the electric field distortion in PI-based composite dielectrics. Consequently, PI-based dielectric containing the MOHI exhibited excellent energy storage performance. The energy storage densities (Ue) of the composite dielectric reached 9.42 J cm-3 and 4.75 J cm-3 with energy storage efficiency (η) of 90% at 25 °C and 150 °C respectively, which are 2.6 and 11.6 times higher than those of pure PI. This study provides new ideas for polymer-based composite dielectrics in high energy storage. This article is protected by copyright. All rights reserved.

2.
Med Image Anal ; 94: 103148, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38554550

RESUMO

Deep learning methods show great potential for the efficient and precise estimation of quantitative parameter maps from multiple magnetic resonance (MR) images. Current deep learning-based MR parameter mapping (MPM) methods are mostly trained and tested using data with specific acquisition settings. However, scan protocols usually vary with centers, scanners, and studies in practice. Thus, deep learning methods applicable to MPM with varying acquisition settings are highly required but still rarely investigated. In this work, we develop a model-based deep network termed MMPM-Net for robust MPM with varying acquisition settings. A deep learning-based denoiser is introduced to construct the regularization term in the nonlinear inversion problem of MPM. The alternating direction method of multipliers is used to solve the optimization problem and then unrolled to construct MMPM-Net. The variation in acquisition parameters can be addressed by the data fidelity component in MMPM-Net. Extensive experiments are performed on R2 mapping and R1 mapping datasets with substantial variations in acquisition settings, and the results demonstrate that the proposed MMPM-Net method outperforms other state-of-the-art MR parameter mapping methods both qualitatively and quantitatively.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Metacrilatos , Humanos , Processamento de Imagem Assistida por Computador/métodos , Encéfalo , Imageamento por Ressonância Magnética/métodos
3.
Clin Exp Hypertens ; 46(1): 2328147, 2024 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-38488417

RESUMO

BACKGROUND: Several studies indicate that the cystathionine ß-synthase (CBS) gene T833C, G919A and 844ins68 polymorphisms in the 8th exon region may be correlated with coronary artery disease (CAD) susceptibility, but the results have been inconsistent and inconclusive. Thus, a meta-analysis was conducted to provide a comprehensive estimate of these associations. METHODS: On the basis of searches in the PubMed, EMBASE, Cochrane Library, Wanfang, VIP, and CNKI databases, we selected 14 case - control studies including 2123 cases and 2368 controls for this meta-analysis. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated accordingly using a fixed-effect or random-effect model. RESULTS: The results indicated an increased risk between the CBS T833C gene polymorphisms and susceptibility to CAD under the dominant model (CC+CT vs. TT: OR = 1.92, 95% CI: 1.11 ~ 3.32), recessive model (CC vs. CT+TT: OR = 1.88, 95% CI: 1.17 ~ 3.03), and homozygous model (CC vs. TT: OR = 2.46, 95% CI: 1.04 ~ 5.83). In these three genetic models, no significant association was identified for CBS G919A (AA+AG vs. GG: OR = 1.48, 95% CI: 0.45 ~ 4.82),(AA vs. AG+GG: OR = 1.58, 95% CI: 0.93 ~ 2.70),(AA vs. GG: OR = 1.66, 95% CI: 0.40 ~ 6.92) or CBS 844ins68 (II+ID vs. DD: OR = 1.04, 95% CI: 0.80 ~ 1.35),(II vs. ID+DD: OR = 1.09, 95% CI: 0.51 ~ 2.36),(II vs. DD: OR = 1.10, 95% CI: 0.51 ~ 2.39). CONCLUSIONS: This meta-analysis suggests that the CBS T833C gene polymorphism is significantly associated with the risk of CAD and it shows a stronger association in Asian populations. Individuals with the C allele of the CBS gene T833C polymorphism might be particularly susceptible to CAD.


Assuntos
Doença da Artéria Coronariana , Humanos , Doença da Artéria Coronariana/genética , Cistationina beta-Sintase/genética , Polimorfismo Genético , Homozigoto , Éxons/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único/genética
4.
Org Lett ; 26(11): 2266-2270, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38451860

RESUMO

A sustainable, cyanide-free synthesis of alkyl nitriles via the aerobic oxidative deconstruction of unstrained cycloalkanones with ammonium salts has been developed. Using inexpensive and stable ammonium salts as the nitrogen source, a variety of alkyl nitriles containing a distal carbonyl group were obtained in good yields under visible-light-promoted iron catalysis. This protocol is characterized by mild conditions, abundant and environmentally benign materials, and high atom and step economy with minimal waste generation. The primary mechanism study revealed that 1O2 is likely to be involved in this reaction.

5.
Opt Express ; 32(4): 4944-4953, 2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38439233

RESUMO

Single-frequency fiber lasers at S-, C-, and L-bands play a crucial role in various applications such as optical network expansion, high-precision metrology, coherent lidar, and atomic physics. However, compared to the C-band, the S- and L-bands have wavelength deviations and suffer from excited-state absorption, which limits the output performance. To address this issue, a strategy called ion hybridization has been proposed to increase the differences in site locations of rare earth (RE) ions in the laser matrix, thereby achieving a broader gain bandwidth. This strategy has been applied to an Er3+/Yb3+ co-doped modified phosphate fiber (EYMPF), resulting in gain coefficients per unit length greater than 2 dB/cm at S-, C-, and L-bands. To demonstrate its capabilities, several centimeter-long EYMPFs have been used to generate single-frequency laser outputs at S-, C- and L-bands with kHz-linewidths, high signal-to-noise ratios (>70 dB), and low relative intensity noise (<-130 dB/Hz) in a compact short linear-cavity configuration.

6.
JACS Au ; 4(2): 491-501, 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38425939

RESUMO

Site-selective excitation (SSE), which is usually realized by tuning the wavelength of absorbed light, is an ideal way to study bond-selective chemistry, analyze the crystal structure, investigate protein conformation, etc., eventually leading to active manipulation of desired processes. Herein, SSE has been explored in (110)-, (100)-, and (011)-faced rutile TiO2, a prototypical material in both surface science and photocatalysis fields. Using ultraviolet photoelectron spectroscopy and photon energy-, substrate orientation-, and laser polarization-dependent two-photon photoemission spectroscopy (2PPE), intra-atomic 3d → 3d transition from the split Ti3+ 3d orbitals, i.e., band gap states and excited states at ∼1.00 eV below and ∼2.40 eV above the Fermi level, respectively, has been proven for all of the samples, suggesting that it is a common property of this material. The distinct structure of rutile TiO2 results in the anisotropic 3d → 3d transitions with the transition dipole moment along the long axes ([110] and [11̅0]) of TiO6 blocking units. This anisotropy facilitates the selective excitation of Ti3+ ions in the two types of TiO6, which cannot be realized by conventional wavelength tuning, via polarization alignment of the excitation source. Discovery in this work builds the foundation for future investigation of site-selective photophysical and photochemical processes and eventually possible active manipulation in this material at the atomic level.

7.
Nat Commun ; 15(1): 1839, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38424039

RESUMO

Untethered capsules hold clinical potential for the diagnosis and treatment of gastrointestinal diseases. Although considerable progress has been achieved recently in this field, the constraints imposed by the narrow spatial structure of the capsule and complex gastrointestinal tract environment cause many open-ended problems, such as poor active motion and limited medical functions. In this work, we describe the development of small-scale magnetically driven capsules with a distinct magnetic soft valve made of dual-layer ferromagnetic soft composite films. A core technological advancement achieved is the flexible opening and closing of the magnetic soft valve by using the competitive interactions between magnetic gradient force and magnetic torque, laying the foundation for the functional integration of both drug release and sampling. Meanwhile, we propose a magnetic actuation strategy based on multi-frequency response control and demonstrate that it can achieve effective decoupled regulation of the capsule's global motion and local responses. Finally, through a comprehensive approach encompassing ideal models, animal ex vivo models, and in vivo assessment, we demonstrate the versatility of the developed magnetic capsules and their multiple potential applications in the biomedical field, such as targeted drug delivery and sampling, selective dual-drug release, and light/thermal-assisted therapy.


Assuntos
Sistemas de Liberação de Medicamentos , Gastroenteropatias , Animais , Fenômenos Físicos
8.
Opt Lett ; 49(3): 434-437, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38300025

RESUMO

Single-frequency fiber lasers (SFFLs), 1083 nm, have been extensively applied in 4He optical pumping magnetometers (OPMs) for magnetic field detection. However, the sensitivity and accuracy of OPMs are constrained by the frequency stability of SFFLs. Focusing on this concern, the frequency-stabilized performance of the 1083 nm SFFLs is successfully improved by externally tailoring the laser linewidth to match the spectral width of the error signal in saturated absorption spectroscopy. Thereinto, a high-intensity error signal of saturated absorption is generated as a large number of 4He atoms with a wide range of velocities interacting with the 1083 nm laser. Consequently, the root mean square value of the fluctuating frequency after locking is effectively decreased from 24.6 to 13.6 kHz, which achieves a performance improvement of 44.7%. Such a strategy can provide a technical underpinning for effectuating an absolute frequency stabilization with higher precision based on atomic and molecular absorption spectroscopy techniques.

9.
Adv Mater ; 36(16): e2311460, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38163922

RESUMO

Ordered mesoporous crystalline frameworks (MCFs), which possess both functional frameworks and well-defined porosity, receive considerable attention because of their unique properties including high surface areas, large pore sizes, tailored porous structures, and compositions. Construction of novel crystalline mesoporous architectures that allows for rich accessible active sites and efficient mass transfer is envisaged to offer ample opportunities for potential energy-related applications. In this review, the rational synthesis, unique structures, and energy applications of MCFs are the main focus. After summarizing the synthetic approaches, an emphasis is placed on the delicate control of crystallites, mesophases, and nano-architectures by concluding basic principles and showing representative examples. Afterward, the currently fabricated components of MCFs such as metals, metal oxides, metal sulfides, and metal-organic frameworks are described in sequence. Further, typical applications of MCFs in rechargeable batteries, supercapacitors, electrocatalysis, and photocatalysis are highlighted. This review ends with the possible development and synthetic challenges of MCFs as well as a future prospect for high-efficiency energy applications, which underscores a pathway for developing advanced materials.

10.
Biosensors (Basel) ; 14(1)2024 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-38275310

RESUMO

Carcinoembryonic antigen (CEACAM5), as a broad-spectrum tumor biomarker, plays a crucial role in analyzing the therapeutic efficacy and progression of cancer. Herein, we propose a novel biosensor based on specklegrams of tapered multimode fiber (MMF) and two-dimensional convolutional neural networks (2D-CNNs) for the detection of CEACAM5. The microfiber is modified with CEA antibodies to specifically recognize antigens. The biosensor utilizes the interference effect of tapered MMF to generate highly sensitive specklegrams in response to different CEACAM5 concentrations. A zero mean normalized cross-correlation (ZNCC) function is explored to calculate the image matching degree of the specklegrams. Profiting from the extremely high detection limit of the speckle sensor, variations in the specklegrams of antibody concentrations from 1 to 1000 ng/mL are measured in the experiment. The surface sensitivity of the biosensor is 0.0012 (ng/mL)-1 within a range of 1 to 50 ng/mL. Moreover, a 2D-CNN was introduced to solve the problem of nonlinear detection surface sensitivity variation in a large dynamic range, and in the search for image features to improve evaluation accuracy, achieving more accurate CEACAM5 monitoring, with a maximum detection error of 0.358%. The proposed fiber specklegram biosensing scheme is easy to implement and has great potential in analyzing the postoperative condition of patients.


Assuntos
Técnicas Biossensoriais , Neoplasias , Humanos , Antígeno Carcinoembrionário , Proteínas Ligadas por GPI
11.
Environ Res ; 244: 117849, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38061591

RESUMO

Arsanilic acid (p-AsA), a prevalently used feed additive, is frequently detected in environment posing a great threat to humans. Potassium ferrate (Fe(VI)) was an efficient way to tackle arsenic contamination under acid and neutral conditions. However, Fe(VI) showed a noneffective removal of p-AsA under alkaline conditions due to its oxidation capacity attenuation. Herein, a magnetic iron-doped carbon nanotubes (F-CNT) was successfully prepared and further catalyzed Fe(VI) to remove p-AsA and total As species. The Fe(VI)/F-CNT system showed an excellent capability to oxidize p-AsA and adsorb total As species over an environment-related pH range of 6-9. The high-valent iron intermediates Fe(V)/Fe(IV) and the mediated electron-transfer played a significant part in the degradation of p-AsA according to the probes/scavengers experiments and galvanic oxidation process. Moreover, the situ formed iron hydroxide oxide and F-CNT significantly improved the adsorption capacity for total As species. The electron-donating groups (semiquinone and hydroquinone) and high graphitization of F-CNT were responsible for activating Fe(VI) based on the analysis of X-ray photoelectron spectroscopy (XPS). Density functional theory calculations and the detected degradation products both indicated that the amino group and the C-As bond of p-AsA were main reactive sites. Notably, Fe(VI)/F-CNT system was resistant to the interference from Cl-, SO42-, and HCO3-, and could effectively remove p-AsA and total As species even in the presence of complex water matrix. In summary, this work proposed an efficient method to use Fe(VI) for degrading pollutants under alkaline conditions and explore a new technology for livestock wastewater advanced treatment.


Assuntos
Arsênio , Compostos Férricos , Nanotubos de Carbono , Poluentes Químicos da Água , Purificação da Água , Humanos , Ferro/química , Ácido Arsanílico/química , Elétrons , Oxirredução , Poluentes Químicos da Água/análise , Purificação da Água/métodos
12.
J Am Chem Soc ; 146(2): 1701-1709, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38157406

RESUMO

Mesoporous materials with crystalline frameworks have been widely explored in many fields due to their unique structure and crystalline feature, but accurate manipulations over crystalline scaffolds, mainly composed of uncontrolled polymorphs, are still lacking. Herein, we explored a controlled crystallization-driven monomicelle assembly approach to construct a type of uniform mesoporous TiO2 particles with atomically aligned single-crystal frameworks. The resultant mesoporous TiO2 single-crystal particles possess an angular shape ∼80 nm in diameter, good mesoporosity (a high surface area of 112 m2 g-1 and a mean pore size at 8.3 nm), and highly oriented anatase frameworks. By adjusting the evaporation rate during assembly, such a facile solution-processed strategy further enables the regulation of the particle size and mesopore size without the destruction of the oriented crystallites. Such a combination of ordered mesoporosity and crystalline orientation provides both effective mass and charge transportation, leading to a significant increase in the hydrogen generation rate. A maximum hydrogen evolution rate of 12.5 mmol g-1 h-1 can be realized, along with great stability under solar light. Our study is envisaged to extend the possibility of mesoporous single crystal growth to a range of functional ceramics and semiconductors toward advanced applications.

13.
J Org Chem ; 89(1): 589-598, 2024 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-38149374

RESUMO

A general domino annulation reaction of sulfonylmethyl isocyanide with trifluoroacetic anhydride in the presence of copper chloride as an additive is developed. The reaction affords 2,5-bis(trifluoromethyl)oxazoles in modest to good yields under mild conditions. A wide variety of sulfonylmethyl isocyanide and perfluorocarboxylic anhydride substrates are amenable to this transformation. Under a higher copper salt loading conditions, the reaction led to the formation of monotrifluoromethyl-substituted oxazole product.

14.
Opt Lett ; 48(23): 6116-6119, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38039205

RESUMO

Aiming at applications like expanding usable wave band of optical telecommunication and preparing Sr optical lattice clocks, a 1627 nm single-frequency fiber laser (SFFL) is demonstrated based on a 7-m-long self-designed Er-doped hybridized glass fiber (EDHF) and a linear cavity configuration with a loop mirror filter (LMF). By inserting a 10-m-long unpumped commercial Er-doped fiber as a dynamic Bragg grating into the LMF, a stable single-longitudinal-mode (SLM) laser with an output power of about 10 mW is obtained. The optical signal-to-noise ratio (OSNR) of SFFL is over 50 dB, and the linewidth is about 3.7 kHz. The measured relative intensity noise (RIN) is less than -140 dB/Hz at frequencies of over 0.5 MHz, and a power variation in 1 h is less than ±0.26%. To our best knowledge, it is the first demonstration of a SFFL operating at the U-band. This 1627 nm SFFL can provide advanced light source technology support for many cutting-edge applications.

15.
BMC Cancer ; 23(1): 1171, 2023 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-38037003

RESUMO

BACKGROUND: The aim of the study is to explore the role of preoperative folate receptor-positive circulating tumor cell (FR+CTC) levels in predicting disease-free survival (DFS) and overall survival (OS) in patients with esophageal squamous cell carcinomas (ESCC). METHODS: Three ml blood samples were prospectively drawn from ESCC patients, and ligand-targeted polymerase chain reaction (LT-PCR) was used for the quantification of FR+CTCs. Other serum indicators were measured by traditional methods. Clinicopathological characteristics were obtained from the hospital medical record system, DFS and OS data were obtained by follow-up. The correlation between clinico-pathological characteristics, DFS, and OS and FR+CTCs were analyzed, respectively. Risk factors potentially affecting DFS and OS were explored by Cox regression analysis. RESULTS: there were no significant correlations between FR+CTCs and patient age, sex, albumin, pre-albumin, C-reactive protein (CRP), ferritin and CRP/Albumin ratio, tumor size, grade of differentiation, lymph node metastasis, TNM stage, perineural invasion/vessel invasion (all P > 0.05). Nevertheless, preoperative FR+CTCs were an independent prognostic factor for DFS (HR 2.7; 95% CI 1.31-, P = 0.007) and OS (HR 3.37; 95% CI 1.06-, P = 0.04). DFS was significantly shorter for patients with post-operative FR+CTCs ≥ 17.42 FU/3ml compared with patients < 17.42 FU/3ml (P = 0.0012). For OS, it was shorter for patients with FR+CTCs ≥ 17.42 FU/3ml compared with patients < 17.42 FU/3ml, however, the difference did not reach statistical significance (P = 0.51). CONCLUSIONS: ESCC patients with high FR+CTCs tend to have a worse prognosis. FR+CTCs may monitor the recurrence of cancers in time, accurately assess patient prognosis, and guide clinical decision-making. TRIAL REGISTRATION: The study was approved by the Sichuan Cancer Hospital & Institute Ethics Committee (No. SCCHEC-02-2022-050).


Assuntos
Neoplasias Esofágicas , Carcinoma de Células Escamosas do Esôfago , Células Neoplásicas Circulantes , Humanos , Células Neoplásicas Circulantes/patologia , Estudos Retrospectivos , Neoplasias Esofágicas/patologia , Prognóstico , Albuminas , Proteína C-Reativa , Ácido Fólico
16.
Opt Express ; 31(22): 37019-37029, 2023 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-38017839

RESUMO

We have proposed and demonstrated a weak acoustic signal detection technology based on phase-sensitive optical time-domain reflectometry (Φ-OTDR). Non-contact acoustic signals transmitting through air gap between the sound source and the receiver are difficult to detect due to fast attenuation. In order to improve the detection ability of non-contact weak acoustic signals, we demonstrate that multi-mode fiber (MMF) is a better solution than single-mode fiber (SMF) benefiting from its larger core and higher Rayleigh backscattering (RBS) capture coefficient. The frequency signal-to-noise ratio (SNR) has been enhanced by 9.26 dB. Then, with the help of 3D printing technology, elastomers have been designed to further enhance the detection ability due to the high-sensitive response to acoustic signals. Compared with the previous reported "I" type elastomer, the location and frequency SNR enhancement caused by our new proposed "n" type elastomer are 8.39 dB and 11.02 dB in SMF based system. The values are further improved to 10.51 dB and 13.38 dB in MMF and "n" type elastomer integrated system. And a phase-pressure sensitivity of -94.62 dB re rad/µPa has been achieved at 2.5 kHz. This non-contact weak acoustic signal detection technique has great application potential in the quasi-distributed partial discharge (PD) detection of smart grid.

17.
Metab Eng ; 80: 25-32, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37689258

RESUMO

Optically pure D-amino acids are key chemicals with various applications. Although the production of specific D-amino acids has been achieved by chemical synthesis or with in vitro enzyme catalysts, it is challenging to convert a simple carbon source into D-amino acids with high efficiency. Here, we design an artificial metabolic pathway by engineering bacteria to heterologously express racemase and N-acetyltransferase to produce N-acetyl-D-amino acids from L-amino acids. This new platform allows the cytotoxicity of D-amino acids to be avoided. The universal potential of this acetylation protection strategy for effectively synthesizing optically pure D-amino acids is demonstrated by testing sixteen amino acid targets. Furthermore, we combine pathway optimization and metabolic engineering in Escherichia coli and achieve practically useful efficiency with four specific examples, including N-acetyl-D-valine, N-acetyl-D-serine, N-acetyl-D-phenylalanine and N-acetyl-D-phenylglycine, with titers reaching 5.65 g/L, 5.25 g/L, 8.025 g/L and 130 mg/L, respectively. This work opens up opportunities for synthesizing D-amino acids directly from simple carbon sources, avoiding costly and unsustainable conventional approaches.


Assuntos
Aminoácidos , Escherichia coli , Aminoácidos/genética , Acetilação , Escherichia coli/metabolismo , Fenilalanina , Engenharia Metabólica , Carbono/metabolismo
18.
Biosens Bioelectron ; 241: 115667, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37696221

RESUMO

Hemoglobin content is recognized as a momentous and fundamental physiological indicator, especially the precise detection of trace hemoglobin is of great significance for early diagnosis and prevention of tumors, cancer, organic injury, etc. Therefore, high-sensitivity hemoglobin detection is imperative. However, effective detection methods and reliable detection systems are still lacking and remain enormous challenges. Herein, we present a synthetical strategy to break through the existing bottleneck based on polarization-differential spectrophotometry and high-performance single-frequency green fiber laser. Importantly, this framework not only has precisely extracted the two-dimensional information of intensity and polarization during the interaction between laser and hemoglobin, but also has taken advantage of the high monochromaticity and fine directivity in the optimized laser source to reduce the undesirable scattered disturbance. Thus, the hemoglobin detection sensitivity of 7.2 × 10-5 g/L has advanced a hundredfold compared with conventional spectrophotometry, and the responsive dynamic range is close to six orders of magnitude. Results indicate that our technology can realize high-sensitivity detection of trace hemoglobin content, holding promising applications for precision medicine and early diagnosis as an optical direct and fast detection method.


Assuntos
Técnicas Biossensoriais , Espectrofotometria/métodos , Hemoglobinas/análise , Lasers , Luz
19.
Brain Sci ; 13(9)2023 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-37759832

RESUMO

Bilingualism is known to enhance cognitive function and flexibility of the brain. However, it is not clear how bilingual experience affects the time-varying functional network and whether these changes depend on the age of bilingual onset. This study intended to investigate the bilingual-related dynamic functional connectivity (dFC) based on the resting-state functional magnetic resonance images, including 23 early bilinguals (EBs), 30 late bilinguals (LBs), and 31 English monolinguals. The analysis identified two dFC states, and LBs showed more transitions between these states than monolinguals. Moreover, more frequent left-right switches were found in functional laterality in prefrontal, lateral temporal, lateral occipital, and inferior parietal cortices in EBs compared with LB and monolingual cohorts, and the laterality changes in the anterior superior temporal cortex were negatively correlated with L2 proficiency. These findings highlight how the age of L2 acquisition affects cortico-cortical dFC pattern and provide insight into the neural mechanisms of bilingualism.

20.
Nanomaterials (Basel) ; 13(16)2023 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-37630886

RESUMO

As an encouraging photocatalyst, crystalline carbon nitride (CCN) exhibits unsatisfactory photocatalytic activity and stability due to its rapid recombination of photo-generative carriers. Herein, high-crystalline g-C3N4 was prepared, including CCN obtained in KCl (K-CCN), LiCl-KCl mixture (Li/K-CCN), and LiCl-NaCl-KCl mixture (Li/Na/K-CCN), via the molten salt strategy using pre-prepared bulk carbon nitride (BCN) as a precursor. The obtained BCN sample was formed by heptazine-based units, which convert into triazine-based units for K-CCN. Heptazine and triazine are two isotypes that co-exist in the Li/K-CCN and Li/Na/K-CCN samples. Compared with BCN and other CCN samples, the as-prepared Li/Na/K-CCN sample exhibited the optimal photocatalytic hydrogen evolution rates (3.38 mmol·g-1·h-1 under simulated sunlight and 2.25 mmol·g-1·h-1 under visible light) and the highest apparent quantum yield (10.97%). The improved photocatalytic performance of the Li/Na/K-CCN sample is mainly attributed to the construction of type-II heterojunction and the institution of the built-in electric field between triazine-based CCN and heptazine-based BCN. This work provides a new strategy for the structural optimization and heterostructure construction of crystalline carbon nitride photocatalysts.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...