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1.
Int Immunopharmacol ; 138: 112474, 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38917529

RESUMO

AIM OF THE STUDY: Research on the mechanism of Huangqin Qingre Chubi Capsules (HQC) in improving rheumatoid arthritis accompanied depression (RA-dep) model rats. METHODS: We employed real-time qPCR (RT-qPCR), western blotting (WB), confocal microscopy, bioinformatics, and other methods to investigate the anti-RA-dep effects of HQC and its underlying mechanisms. RESULTS: HQC alleviated the pathological indexes of inflammation and depression in RA-dep model rats, decreased the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-6, increased the levels of norepinephrine(NE) and serotonin(5-HT), and improved the injury of hippocampus. The analysis of network pharmacology suggests that HQC may target the Wnt/ß-catenin pathway in the treatment of RA-dep. Furthermore, molecular dynamics simulations revealed a strong affinity between HQC and the Wnt1 molecule. RT-qPCR and Western Blot (WB) experiments confirmed the critical role of the Wnt1/ß-catenin signaling pathway in the treatment of RA-dep model rats with HQC. In vitro, the HQC drug-containing serum (HQC-serum) activates the Wnt1/ß-catenin signaling pathway in hippocampal cells and, in conjunction with Wnt1, ameliorates RA-dep. In summary, HQC exerts its anti-inflammatory and antidepressant effects in the treatment of RA-dep by binding to Wnt1 and regulating the Wnt1/ß-catenin signaling pathway. CONCLUSIONS: HQC improved the inflammatory reaction and depression-like behavior of RA-dep model rats by activating Wnt1/ß-catenin signal pathway. This study revealed a new pathogenesis of RA-dep and contributes to the clinical promotion of HQC in the treatment of RA-dep.

2.
Small ; 20(12): e2302410, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37635113

RESUMO

Herein, a hybrid substrate for surface-enhanced Raman scattering (SERS) is fabricated, which couples localized surface plasmon resonance (LSPR), charge transfer (CT) resonance, and molecular resonance. Exfoliated 2D TiS2 nanosheets with semimetallic properties accelerate the CT with the tested analytes, inducing a remarkable chemical mechanism enhancement. In addition, the LSPR effect is coupled with a concave gold array located underneath the thin TiS2 nanosheet, providing a strong electromagnetic enhancement. The concave gold array is prepared by etching silicone nanospheres assembled on larger polystyrene nanospheres, followed by depositing a gold layer. The LSPR intensity near the gold layer can be adjusted by changing the layer thickness to couple the molecular and CT resonances, in order to maximize the SERS enhancement. The best SERS performance is recorded on TiS2-nanosheet-coated plasmonic substrates, with a detectable methylene blue concentration down to 10-13 m and an enhancement factor of 2.1 × 109 and this concentration is several orders of magnitude lower than that of the TiS2 nanosheet (10-11 m) and plasmonic substrates (10-9 m). The present hybrid substrate with triple-coupled resonance further shows significant advantages in the label-free monitoring of curcumin (a widely applied drug for treating multiple cancers and inflammations) in serum and urine.

3.
Zhongguo Zhong Yao Za Zhi ; 48(22): 6154-6163, 2023 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-38114222

RESUMO

This study aims to investigate the mechanism of muscone in inhibiting the opening of mitochondrial permeability transition pore(mPTP) to alleviate the oxygen and glucose deprivation/reoxygenation(OGD/R)-induced injury of mouse hippocampal neurons(HT22). An in vitro model of HT22 cells injured by OGD/R was established. CCK-8 assay was employed to examine the viability of HT22 cells, fluorescence microscopy to measure the mitochondrial membrane potential, the content of reactive oxygen species(ROS), and the opening of mPTP in HT22 cells. Enzyme-linked immunosorbent assay was employed to determine the level of ATP and the content of cytochrome C(Cyt C) in mitochondria of HT22 cells. Flow cytometry was employed to determine the Ca~(2+) content and apoptosis of HT22 cells. The expression of Bcl-2(B-cell lymphoma-2) and Bcl-2-associated X protein(Bax) was measured by Western blot. Molecular docking and Western blot were employed to examine the binding between muscone and methyl ethyl ketone(MEK) after pronase hydrolysis of HT22 cell proteins. After the HT22 cells were treated with U0126, an inhibitor of MEK, the expression levels of MEK, p-ERK, and CypD were measured by Western blot. The results showed that compared with the OGD/R model group, muscone significantly increased the viability, mitochondrial ATP activity, and mitochondrial membrane potential, lowered the levels of ROS, Cyt C, and Ca~(2+), and reduced mPTP opening to inhibit the apoptosis of HT22 cells. In addition, muscone up-regulated the expression of MEK, p-ERK, and down-regulated that of CypD. Molecular docking showed strong binding activity between muscone and MEK. In conclusion, muscone inhibits the opening of mPTP to inhibit apoptosis, thus exerting a protective effect on OGD/R-injured HT22 cells, which is associated with the activation of MEK/ERK/CypD signaling pathway.


Assuntos
Apoptose , Oxigênio , Camundongos , Animais , Espécies Reativas de Oxigênio/metabolismo , Simulação de Acoplamento Molecular , Trifosfato de Adenosina/farmacologia , Quinases de Proteína Quinase Ativadas por Mitógeno/farmacologia , Glucose/metabolismo
4.
Front Vet Sci ; 10: 1230190, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37799402

RESUMO

Introduction: The objective of this study was to investigate the effects of N-carbamylglutamate (NCG) supplementation on the growth performance, hindgut microbiota composition, and short-chain fatty acid (SCFA) contents in Charollais and Small Tail Han crossbred sheep. Methods: A total of 16 female crossbred mutton sheep (Charollais × Small Tail Han), aged 4 months, with an initial body weight of 30.03 ± 0.08 kg, were utilized in a 60 days experiment. The sheep were divided into two groups based on their initial body weight. Each group consisted of 8 replicates, with each individual sheep considered as a replicate. The dietary treatments comprised a basal diet supplemented with either 0.00% or 0.12% NCG. Results and discussion: Our findings indicate that NCG supplementation did not have a significant effect on the growth performance of mutton sheep. However, it did lead to changes in hindgut SCFA contents. Specifically, NCG supplementation increased the content of propanoic acid while decreasing acetic acid and hexanoic acid in the hindgut. Through microbiota analysis using the 16S rRNA technique, we identified Lachnospiraceae_NK3A20_group and Parasutterella as biomarkers for the hindgut microbiota in mutton sheep fed a diet containing NCG. Further analysis of the microbiota composition revealed that NCG supplementation significantly increased the abundance of Lachnospiraceae_NK3A20_group and Parasutterella, while decreasing unclassified_f_Lachnospiraceae and Lachnoclostridium. Correlation analysis between hindgut SCFA contents and microbiota composition revealed that the abundance of Lachnoclostridium was positively correlated with the contents of acetic acid and hexanoic acid, but negatively correlated with propanoic acid. Additionally, the abundance of Lachnospiraceae_NK3A20_group and Parasutterella was positively correlated with the content of propanoic acid, while being negatively correlated with acetic acid and hexanoic acid. Based on these findings, we conclude that dietary supplementation of 0.12% NCG can modulate hindgut SCFA contents in mutton sheep by regulating the composition of the hindgut microbiota.

5.
J Agric Food Chem ; 70(50): 15693-15702, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36479881

RESUMO

Plant diseases seriously affect the growth of crops and the quality and yield of agricultural products. The search for plant-derived pesticide candidates based on natural products is a hot topic of current research. Marine natural products almazoles C-D were efficiently prepared and selected as the lead compounds in this work. Two series of almazole derivatives were designed and synthesized, and their antiviral and fungicidal activities were systematically evaluated. The results of anti-tobacco mosaic virus (anti-TMV) activity showed that almazoles C-D and their derivatives had good anti-TMV activities. Compounds 6, 15, 16a, 16b, 16g, 16l, 16n, 20a, 20d, 20i, and 20n exhibited better anti-TMV activities than the commercial antiviral agent ribavirin. Anti-TMV mechanism studies showed that compound 16b could induce the polymerization of 20S CP (coat protein, CP), thereby affecting the assembly of TMV virus particles. Molecular docking results showed that compounds 15, 16b, and 20n could combine with amino acid residues through hydrogen bonds to achieve an excellent anti-TMV effect. In addition, most of the almazole derivatives were found to have broad-spectrum fungicidal activities against eight kinds of plant pathogens (Fusarium oxysporum f. sp. cucumeris, Cercospora arachidicola Hori, Physalospora piricola, Rhizoctonia cerealis, Alternaria solani, Pyricularia grisea, Phytophthora capsici, and Sclerotinia sclerotiorum). This study provides an important evidence for the research and development of almazole alkaloids containing indole and oxazole structural groups as novel agrochemicals.


Assuntos
Produtos Biológicos , Vírus do Mosaico do Tabaco , Antivirais/farmacologia , Antivirais/química , Relação Estrutura-Atividade , Produtos Biológicos/farmacologia , Produtos Biológicos/química , Simulação de Acoplamento Molecular , Ribavirina/farmacologia , Desenho de Fármacos
6.
Zhongguo Zhong Yao Za Zhi ; 47(19): 5274-5283, 2022 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-36472034

RESUMO

To investigate the protective effect of Tongqiao Huoxue Decoction containing cerebrospinal fluid(TQHXD-CSF) on HT22 cells damaged by oxygen-glucose deprivation/reoxygenation(OGD/R) and whether the mechanism is related to the regulation of ASK1/MKK4/JNK signaling pathway. HT22 cells were subjected to OGD/R to simulate cerebral ischemia-reperfusion injury(CIRI). Then the cells were randomly divided into five groups: blank cerebrospinal fluid(control group), OGD/R group, TQHXD-CSF group, Z-VAD-FMK group(20 µmol·L~(-1)) and TQHXD-CSF+Z-VAD-FMK group. Except the control group, cells in the other groups were reoxygenated for 12 h after 6 h of oxygen and glucose deprivation for modeling OGD/R, and group administration was performed. Cell viability and cytotoxicity were detected by CCK8 and LDH assay kit, respectively and the morphology of HT22 cells was observed by inverted microscope. Western blot and qRT-PCR were employed to detect the protein and mRNA expression levels of Bax, Bcl-2 and caspase-3, respectively. Then HT22 cells were assigned into the control group, OGD/R group, si-NC group, si-ASK1 group, TQHXD-CSF group and TQHXD-CSF+si-ASK1 group. Cell viability, proliferation and apoptosis were determined by CCK8, electric cell-substrate impedance sensing(ECIS), and Hoechst staining and flow cytometry, respectively. The protein expression of MKK4, p-MKK4, JNK, p-JNK, c-Jun, p-c-Jun, Cyt C, Bax, Bcl-2 and caspase-3 was tested by Western blot. The results showed that compared with OGD/R group, TQHXD-CSF significantly enhanced cell viability, improved cell morphology and reduced the protein and mRNA expression levels of Bax, Bcl-2 and caspase-3. In addition, when ASK1 was silenced, compared with OGD/R group, TQHXD-CSF remarkably improved cell viability, and decreased apoptosis rate and the protein expression levels of p-MKK4, p-JNK, p-c-Jun, Cyt C, Bax/Bcl-2 and caspase-3, but the effect was not as good as that of TQHXD-CSF+si-ASK1 group. In conclusion, TQHXD-CSF can inhibit apoptosis mediated by ASK1/MKK4/JNK signaling pathway in OGD/R-damaged HT22 cells, and has protective effect on ischemia-reperfusion injury.


Assuntos
Sistema de Sinalização das MAP Quinases , Traumatismo por Reperfusão , Humanos , Apoptose , Proteína X Associada a bcl-2/metabolismo , Caspase 3/metabolismo , Glucose , Oxigênio/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Traumatismo por Reperfusão/metabolismo , RNA Mensageiro/metabolismo
7.
Biosens Bioelectron ; 218: 114773, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36228393

RESUMO

In-situ real-time detection of drug metabolites and biomolecules in hospitalized patients' urine helps the doctors to monitor their physiological indicators and regulate the use of drug doses. In this work, nitrogen-doped carbon-supported bimetal was prepared into the screen-printed electrodes (SPEs) and applied for real-time monitoring of acetaminophen (AC) and dopamine (DA) in urine. Via one-step pyrolysis of the core-shell cubic precursor (Cu3[Co(CN)6]2@Co3[Co(CN)6]2, CuCo@CoCo), the nitrogen-doped carbon-supported bimetal (CuCo-NC) was formed. The bimetal composites presented twice higher catalytic activity than the counterparts with single metal. In addition, the nanocomposites exhibited strong conductivity after pyrolysis, promoting electron transport efficiency as indicated by impedance measurements. Accordingly, the CuCo-NC based sensor offered excellent sensitivity with the detection limits down to 50 nM and 30 nM at the detection range of 0.1-400 µM and 0.2-200 µM for detection of AC and DA, respectively. Finally, in combination with a miniaturized electrochemical device, the sensor was applied for in-situ real-time monitoring of AC and DA in the urinary bag for up to 12h. As compared with other techniques such as high-performance liquid chromatography, UV-spectrophotometry and fluorescence spectrometer, the biosensor demonstrated the advantages of real-time monitoring, easy operation and excellent portability. However, the multi-component detection and self-calibration function need to be further developed. This method paves a way for the continuous monitoring of drug metabolites and biomolecules of hospitalized patients.


Assuntos
Técnicas Biossensoriais , Dopamina , Humanos , Dopamina/análise , Carbono/química , Nitrogênio/química , Acetaminofen/análise , Técnicas Biossensoriais/métodos , Limite de Detecção
8.
Phytomedicine ; 106: 154437, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36099654

RESUMO

BACKGROUND: Activation of blood stasis is a crucial aspect of stroke treatment, and the Tong-Qiao-Huo-Xue-Decoction (TQHXD) formula is commonly utilized for this purpose. However, the mechanism underlying the protective effects of TQHXD against cerebral ischemia-reperfusion (I/R) injury is unclear. PURPOSE: Identification of the TQHXD components responsible for its protective effects and determination of their mode of action against cerebral I/R injury. METHODS: Gas chromatography (GC) and high-performance liquid chromatography (HPLC) were carried out to determine the active aspects of TQHXD. The active components and targets of TQHXD were looked up in the TCMSP and HERB databases; the Genecards, OMIM, TTD, and DrugBank databases were used to identify targets related to cerebral infarction; and the intersecting targets were obtained. The drug-ingredient-target-disease network and PPI network were subsequently built using Cytoscape 3.7.1 and STRING websites. Autodock VINA was used to perform molecular docking between the core target ASK1 and the active components of TQHXD detected by HPLC and GC. After successfully creating a rat model of middle cerebral artery occlusion (MCAO), the therapeutic effect of TQHXD was observed using triphenyltetrazolium and hematoxylin-eosin staining. We used Tunel-NeuN staining and transmission electron microscopy (TEM) to quantify hippocampal apoptosis. RT-qPCR and western blotting were used to detect protein and mRNA expression, respectively. RESULTS: HPLC and GC identified six active ingredients. Network pharmacology analyses were performed to test 66 intersection targets, including ASK1, MKK4, and JNK. Ferulic acid, HSYA, ligustilide, paeoniflorin, and muscone all displayed high binding affinity with ASK1 in molecular docking studies. The neuroprotective effects of TQHXD in I/R rats were demonstrated in the experimental models. In comparison with the model group, TQHXD decreased the apoptosis rate and reduced the protein levels of p-ASK1, caspase 3, p-MKK4, CytC, p-c-Jun, Bax/Bcl-2, and p-JNK, while considerably increasing the mRNA levels of Bcl-2 and decreasing those of Bax. CONCLUSION: By controlling the ASK1/MKK4/JNK pathway, TQHXD protects neurons from I/R damage and prevents apoptosis. Thus, TQHXD may be effective for the treatment of ischemic stroke. And the mechanism behind these therapeutic actions of TQHXD is supported by this research.


Assuntos
Fármacos Neuroprotetores , Traumatismo por Reperfusão , Animais , Apoptose , Caspase 3/metabolismo , Medicamentos de Ervas Chinesas , Amarelo de Eosina-(YS)/farmacologia , Amarelo de Eosina-(YS)/uso terapêutico , Hematoxilina/farmacologia , Hematoxilina/uso terapêutico , Infarto da Artéria Cerebral Média/tratamento farmacológico , Sistema de Sinalização das MAP Quinases , Simulação de Acoplamento Molecular , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA Mensageiro/metabolismo , Ratos , Traumatismo por Reperfusão/tratamento farmacológico , Proteína X Associada a bcl-2/metabolismo
9.
Adv Sci (Weinh) ; 9(12): e2104738, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35195359

RESUMO

Contact lenses have become a popular health-monitoring wearable device due to their direct contact with the eyes. By integrating biosensors into contact lenses, real-time and noninvasive diagnoses of various diseases can be realized. However, current contact lens sensors often require complex electronics, which may obstruct the user's vision or even damage the cornea. Moreover, most of the reported contact lens sensors can only detect one analyte. Therefore, an optical-based dual-functional smart contact lens sensor has been introduced to monitor intraocular pressure (IOP) and detect matrix metalloproteinase-9 (MMP-9), both of which are key biomarkers in many eye-related diseases such as glaucoma. Specifically, the elevated IOP is continuously monitored by applying an antiopal structure through color changes, without any complex electronics. Together with the peptide modified gold nanobowls (AuNBs) surface-enhanced Raman scattering (SERS) substrate, the quantitative analysis of MMP-9 at a low nanomolar range is achieved in real tear samples. The dual-sensing functions are thus demonstrated, providing a convenient, noninvasive, and potentially multifunctional sensing platform for monitoring health and diagnostic biomarkers in human tears.


Assuntos
Lentes de Contato , Glaucoma , Glaucoma/diagnóstico , Humanos , Pressão Intraocular , Metaloproteinase 9 da Matriz , Tonometria Ocular
10.
Ann Transl Med ; 9(11): 925, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34350240

RESUMO

BACKGROUND: Brain glioblastoma multiforme (GBM) is the most common primary malignant intracranial tumor. The prognosis of this disease is extremely poor. While the introduction of ß-interferon (IFN-ß) regimen in the treatment of gliomas has significantly improved the outcome of patients; The mechanism by which IFN-ß induces increased TMZ sensitivity has not been described. Therefore, the main objective of the study was to elucidate the molecular mechanisms responsible for the beneficial effect of IFNß in GBM. METHODS: Messenger RNA expression profiles and clinicopathological data were downloaded from The Cancer Genome Atlas (TCGA) GBM and GSE83300 dataset from the Gene Expression Omnibus. Univariate Cox regression analysis and lasso Cox regression model established a novel 4-gene IFN-ß signature (peroxiredoxin 1, Sec61 subunit beta, X-ray repair cross-complementing 5, and Bcl-2-like protein 2) for GBM prognosis prediction. Further, GBM samples (n=50) and normal brain tissues (n=50) were then used for real-time polymerase chain reaction experiments. Gene set enrichment analysis (GSEA) was performed to further understand the underlying molecular mechanisms. Pearson correlation was applied to calculate the correlation between the long non-coding RNAs (lncRNAs) and IFN-ß-associated genes. An lncRNA with a correlation coefficient |R2|>0.3 and P<0.05 was considered to be an IFN-ß-associated lncRNA. RESULTS: Patients in the high-risk group had significantly poorer survival than patients in the low-risk group. The signature was found to be an independent prognostic factor for GBM survival. Furthermore, GSEA revealed several significantly enriched pathways, which might help explain the underlying mechanisms. Our study identified a novel robust 4-gene IFN-ß signature for GBM prognosis prediction. The signature might contain potential biomarkers for metabolic therapy and treatment response prediction for GBM patients. CONCLUSIONS: In the present study, we established a novel IFN-ß-associated gene signature to predict the overall survival of GBM patients, which may help in clinical decision making for individual treatment.

11.
Thromb Res ; 179: 87-94, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31100633

RESUMO

INTRODUCTION: Personalized antiplatelet treatment in patients with acute coronary syndrome (ACS) or undergoing percutaneous coronary intervention (PCI) remains challenging in clinical practice. The present study aimed to explore the benefit of genotype-guided antiplatelet treatment with P2Y12 inhibitors in patients with ACS or undergoing PCI. METHODS: A literature search was conducted (from inception to September 2018) in the PUBMED, EMBASE and Cochrane databases. Studies were included in which the genotype-guided P2Y12 inhibitor antiplatelet strategy was compared with the standard strategy in patients with ACS or undergoing PCI. The endpoints were high on-treatment platelet reactivity (HTPR), major adverse cardiovascular events including all-cause mortality, myocardial infarction (MI), stent thrombosis (ST), stroke and target-vessel revascularization (TVR), and major bleedings. RESULTS: A total of 3377 patients in 9 studies (5 RCTs and 4 non-RCTs) were included, in which 91% of the patients were diagnosed with ACS and 88.5% underwent PCI. A total of 1639 patients (48.5%) were assigned to the genotype-guided group, and 1738 (51.4%) assigned to the conventional or standard (STD) group, with an average follow-up time of 7.6 months. After the pooled analysis, significantly lower risks of HTPR (HR: 0.32, 95% CI: 0.18-0.55, P < 10-4), all-cause mortality (HR: 0.55, 95% CI: 0.37-0.83, p = 0.005), MI (HR: 0.43, 95% CI: 0.27-0.67, p = 0.0002) and ST (HR: 0.39, 95% CI: 0.16-0.97, p = 0.004) were observed in the genotype-guided group compared to the STD group. No significant between-group difference was found for the risk of stroke, TVR, and major bleedings after the pooled analysis. CONCLUSION: Genotype-guided antiplatelet treatment could decrease the risks of HTPR, all-cause mortality, MI and ST in patients with ACS or undergoing PCI.


Assuntos
Síndrome Coronariana Aguda/tratamento farmacológico , Intervenção Coronária Percutânea/métodos , Feminino , Genótipo , Humanos , Masculino , Inibidores da Agregação Plaquetária/uso terapêutico
12.
Phys Chem Chem Phys ; 20(2): 1039-1050, 2018 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-29236105

RESUMO

A new global potential energy surface (PES) of the O+ + H2 system was constructed with the permutation invariant polynomial neural network method, using about 63 000 ab initio points, which were calculated by employing the multi-reference configuration interaction method with aug-cc-pVTZ and aug-cc-pVQZ basis sets. For improving the accuracy of the PES, the basis set was extrapolated to the complete basis set limit by the two-point extrapolation method. The root mean square error of fitting was only 5.28 × 10-3 eV. The spectroscopic constants of the diatomic molecules were calculated and compared with previous theoretical and experimental results, which suggests that the present results agree well with the experiment. On the newly constructed PES, reaction dynamics studies were performed using the time-dependent wave packet method. The calculated integral cross sections (ICSs) were compared with the available theoretical and experimental results, where a good agreement with the experimental data was seen. Significant forward and backward scatterings were observed in the whole collision energy region studied. At the same time, the differential cross sections biased the forward scattering, especially at higher collision energies.

13.
Sci Technol Adv Mater ; 15(2): 025003, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27877664

RESUMO

BaTiO3-CoFe2O4 composite films were prepared on (100) SrTiO3 substrates by using a radio-frequency magnetron co-sputtering method at 750 °C. These films contained highly (001)-oriented crystalline phases of perovskite BaTiO3 and spinel CoFe2O4, which can form a self-assembled nanostructure with BaTiO3 well-dispersed into CoFe2O4 under optimized sputtering conditions. A prominent dielectric percolation behavior was observed in the self-assembled nanocomposite. Compared with pure BaTiO3 films sputtered under similar conditions, the nanocomposite film showed higher dielectric constants and lower dielectric losses together with a dramatically suppressed frequency dispersion. This dielectric percolation phenomenon can be explained by the 'micro-capacitor' model, which was supported by measurement results of the electric polarization and leakage current.

14.
Sci Technol Adv Mater ; 13(3): 035006, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27877494

RESUMO

Domain structures of BaTiO3 thick films grown on (100) SrTiO3 single-crystal substrates were engineered using an RF magnetron sputtering deposition process. By tuning the sputtering power and cooling rate and using an off-axis sputtering technique to prepare conducting perovskite oxide bottom electrode with heteroepitaxial quality, we have deposited epitaxial tetragonal single-domain and polydomain BaTiO3 films with a self-assembled three-domain architecture. The electrical properties and microstructure of the BaTiO3 films were characterized, and a c/a1/a2 cellular polydomain structure was clearly observed in as-grown films by optical microscopy. Such a polydomain structure was a consequence of a complete relaxation of misfit stresses of the film. Engineering of this self-assembled microstructure has great potential in providing large, field-tunable pyroelectric and electromechanical responses in next-generation microelectronic devices and micro-electro-mechanical systems (MEMS).

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